Patent Publication Number: US-10774015-B2

Title: Reduced polymer formation for selective ethylene oligomerizations

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of and claims priority to U.S. patent application Ser. No. 15/167,024 filed May 27, 2016, published as U.S. Patent Application Publication US 2017/0341999 A1, and entitled “Reduced Polymer Formation for Selective Ethylene Oligomerizations,” which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to processes, system, and reaction system configurations for oligomerization of ethylene. 
     BACKGROUND 
     The development of alpha olefin oligomerization techniques for the selective production of linear alpha olefins (C 6  to C 20 ) which do not utilize triethylaluminum (TEA) as part of the catalyst system has been a challenge. Both the economics and relative efficiency of TEA-based techniques have been difficult to match in alternative techniques. Some commercial success has been achieved using alternative techniques which use homogeneous catalyst systems; however, these techniques require extended secondary processing to recover the linear alpha olefins from undesired fractions/products such as butene or waxes. Other alternative techniques utilizing diphosphinyl amine chromium compound complexes have been developed as well. The diphosphinyl amine chromium compound complexes based catalyst systems can produce desired linear alpha olefins without the drawbacks of the alternative techniques which use homogeneous catalyst systems. There is an ongoing need for improvements to diphosphinyl amine chromium compound complex (and related chromium compound complex) based oligomerization techniques. 
     SUMMARY 
     Disclosed is a process comprising: a) introducing into a reaction zone containing a C 3+  olefin (any disclosed herein) and optionally an organic reaction medium (any disclosed herein) wherein the reaction zone is substantially devoid of ethylene, i) ethylene ii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iii) the organic reaction medium, and iv) optionally hydrogen; and b) forming an ethylene oligomer product in the reaction zone; wherein the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. 
     Also disclosed is a process comprising: a) contacting in a reaction zone i) a C 3+  olefin (e.g., any disclosed herein), ii) ethylene, iii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iv) an organic reaction medium (any disclosed herein), and v) optionally hydrogen into the reaction zone; and c) forming an ethylene oligomer product; wherein the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. 
     Also disclosed is a process comprising: a) contacting i) ethylene, ii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iii) an organic reaction medium (any described herein), and iv) optionally hydrogen in a reaction zone; b) forming an ethylene oligomer product in the reaction zone; wherein ethylene, the catalyst system, and the organic reaction medium are introduced into the reaction zone and for a period of time a C 3+  olefin is introduced into the reaction zone. 
     Also disclosed is a process comprising: a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); b) for a period of time separately feeding to the reaction zone a feedstock mixture comprising ethylene and i) a C 3+  olefin (e.g., any described herein), and ii) at least a portion of an organic reaction medium (e.g., any described herein), or iii) combinations of i) and ii); wherein the feedstock mixture is substantially free of the catalyst system; c) contacting the catalyst system and the feedstock mixture in the reaction zone; and d) forming an ethylene oligomer product in the reaction zone. 
     Also disclosed is a process comprising: a) contacting i) ethylene, ii) at least a portion of an organic reaction medium (e.g., any disclosed herein), and iii) for a period of time a C 3+  olefin (e.g., any disclosed herein) to form a feedstock mixture; b) subsequent to a), contacting in a reaction zone the feedstock mixture with a catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) forming an ethylene oligomer product in the reaction zone. 
     Also disclosed is a process comprising: a) diluting ethylene by addition of at least i) a portion of an organic reaction medium (any described herein), ii) for a period of time a C 3+  olefin (e.g., any described herein), or iii) for a period of time at least a portion of an organic reaction medium (any described herein) and a C 3+  olefin to form a feedstock mixture prior to contacting the ethylene with a catalyst system in a reaction zone; b) contacting in the reaction zone the feedstock mixture and the catalyst system, wherein the catalyst system comprises i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) forming an ethylene oligomer product in the reaction zone. 
     Also disclosed is a system comprising: a) a feedstock mixture comprising ethylene, an organic reaction medium (e.g., any described herein), and for a period of time a C 3+  olefin (e.g., any described herein); b) a catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) a reaction zone receiving the feedstock mixture separately from the catalyst stream. 
     Also disclosed is a process comprising: a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); b) separately feeding to the reaction zone a feedstock mixture comprising i) ethylene, ii) an organic reaction medium (e.g., any described herein), and iii) for a period of time a C 3+  olefin (e.g., any described herein) to contact the catalyst system; wherein during a reaction zone startup the feedstock mixture C 3+  olefin:ethylene weight ratio periodically or continuously decreases; c) forming an ethylene oligomer product in the reaction zone; and d) operating the reaction zone in about steady-state conditions subsequent to the reaction zone start-up; wherein the period of time is a reaction zone period of time or a C 3+  olefin/ethylene feed period of time. 
     Also disclosed is a process for startup of a reaction zone, the process comprising: for a period of time contacting in the reaction zone 1) ethylene, 2) a catalyst system comprising a) a chromium component comprising a chromium compound (any described herein), b) a heteroatomic ligand (any described herein), and c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and b) an aluminoxane (any disclosed herein), 3) an organic reaction medium, and 4) optionally hydrogen to form an ethylene oligomer product; wherein: the catalyst system is fed to the reaction zone, a feedstock mixture comprising i) ethylene, ii) an organic reaction medium (any described herein), and iii) a C 3+  olefin (any described herein) is fed to the reaction zone for a period of time, wherein the feedstock mixture is substantially free of the catalyst system prior to the feedstock mixture contacting the catalyst system in the reaction zone. 
     Also disclosed is a reaction system comprising: a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein) to the reaction zone; a second reaction zone inlet configured to introduce ethylene, an organic reaction medium, and optionally hydrogen to the reaction zone; a C 3+  olefin feed line in fluid communication with the first reaction zone inlet, the second reaction zone inlet, or a third reaction zone inlet configured to introduce a C 3+  olefin to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. 
     Also disclosed is a reaction system comprising: a reaction zone; a reaction zone inlet configured to introduce a catalyst system, ethylene, an organic reaction medium, and a C 3+  olefin to the reaction zone; an ethylene feed line comprising ethylene, a C 3+  olefin feed line comprising a C 3+  olefin, an organic reaction medium feed line comprising an organic reaction medium and optionally a hydrogen feed line comprising hydrogen all in fluid communication with the reaction zone inlet, wherein the organic reaction medium feed line combines with the ethylene feed line to form a feedstock mixture feed line in fluid communication with the reaction zone inlet; a catalyst system feed line comprising catalyst system in fluid communication with the reaction zone inlet, wherein the catalyst system feed line combines with the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, or a dispersed feedstock mixture feed line formed by passing the feedstock mixture feed line through a mixing device; one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone, wherein the catalyst system comprises (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), and wherein the C 3+  olefin feed line joins with one or more of the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, the dispersed feedstock mixture feed line, or a combined feed line formed by joining the catalyst system feed line and the dispersed feedstock mixture feed line. 
     Also disclosed is a reaction system comprising: a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein) to the reaction zone; a second reaction zone inlet configured to introduce ethylene and optionally hydrogen to the reaction zone; a third reaction zone inlet configured to introduce an organic reaction medium to the reaction zone; a C 3+  olefin feed line in fluid communication with one or more of the first reaction zone inlet, the second reaction zone inlet, the third reaction zone inlet, or a fourth reaction zone inlet which is configured to introduce the C 3+  olefin directly to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description, reference will now be made to the accompanying drawings 
         FIG. 1  shows a process flow diagram of a reaction system according to the present disclosure. 
         FIG. 2  shows a process flow diagram of another reaction system according to the present disclosure. 
         FIG. 3  shows a process flow diagram of another reaction system according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the description herein, various ranges and/or numerical limitations can be expressly stated below. It should be recognized that unless stated otherwise, it is intended that endpoints are to be interchangeable. Further, any ranges include iterative ranges of like magnitude falling within the expressly stated ranges or limitations. 
     Furthermore, various modifications can be made within the scope of the invention as herein intended, and embodiments of the invention can include combinations of features other than those expressly claimed. In particular, flow arrangements other than those expressly described herein are within the scope of the invention. 
     Unless otherwise specified, the terms “contact” and “combine,” and their derivatives, can refer to any addition sequence, order, or concentration for contacting or combining two or more components of the disclosed embodiments. Combining or contacting of oligomerization components can occur in one or more reaction zones under suitable contact conditions such as temperature, pressure, contact time, flow rates, etc. 
     Regarding claim transitional terms or phrases, the transitional term “comprising”, which is synonymous with “including,” “containing,” “having” or “characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. A “consisting essentially of” claim occupies a middle ground between closed claims that are written in a “consisting of” format and fully open claims that are drafted in a “comprising” format. Absent an indication to the contrary, when describing a compound or composition “consisting essentially of” is not to be construed as “comprising,” but is intended to describe the recited component that includes materials which do not significantly alter composition or method to which the term is applied. For example, a feedstock consisting of a material A can include impurities typically present in a commercially produced or commercially available sample of material A. When a claim includes different features and/or feature classes (for example, a method step, feedstock features, and/or product features, among other possibilities), the transitional terms comprising, consisting essentially of, and consisting of apply only to the feature class that is utilized and it is possible to have different transitional terms or phrases utilized with different features within a claim. For example a method can comprise several recited steps (and other non-recited steps) but utilize a catalyst system preparation consisting of specific steps can utilize a catalyst system comprising recited components and other non-recited components. 
     Within this specification, use of “comprising” or an equivalent expression contemplates the use of the phrase “consisting essentially of,” “consists essentially of,” or equivalent expressions as alternative embodiments to the open-ended expression. Additionally, use of “comprising” or an equivalent expression or use of “consisting essentially of” in the specification contemplates the use of the phrase “consisting of,” “consists of,” or equivalent expressions as an alternative to the open-ended expression or middle ground expression, respectively. For example, “comprising” should be understood to include “consisting essentially of,” and “consisting of” as alternative embodiments for the aspect, features, and/or elements presented in the specification unless specifically indicated otherwise. 
     While compositions and methods are described in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components or steps. 
     The terms “a,” “an,” and “the” are intended, unless specifically indicated otherwise, to include plural alternatives, e.g., at least one. For instance, the disclosure of “a trialkylaluminum compound” is meant to encompass one trialkylaluminum compound, or mixtures or combinations of more than one trialkylaluminum compound unless otherwise specified. 
     Unless otherwise indicated, the definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2 nd  Ed (1997), can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition can be applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls. 
     Groups of elements of the Periodic Table are indicated using the numbering scheme indicated in the version of the Periodic Table of elements published in  Chemical and Engineering News,  63(5), 27, 1985. In some instances, a group of elements can be indicated using a common name assigned to the group; for example, alkali metals for Group 1 elements, alkaline earth metals (or alkaline metals) for Group 2 elements, transition metals for Groups 3-12 elements, and halogens for Group 17 elements. 
     For any particular compound disclosed herein, the general structure or name presented is also intended to encompass all structural isomers, conformational isomers, and stereoisomers that can arise from a particular set of substituents, unless indicated otherwise. Thus, a general reference to a compound includes all structural isomers unless explicitly indicated otherwise; e.g., a general reference to hexene includes 1-hexene, 2-hexene, 3-hexene, and any other hydrocarbon having 6 carbon atoms (linear, branched or cyclic) and a single carbon carbon double bond. Additionally, the reference to a general structure or name encompasses all enantiomers, diastereomers, and other optical isomers whether in enantiomeric or racemic forms, as well as mixtures of stereoisomers, as the context permits or requires. For any particular formula or name that is presented, any general formula or name presented also encompasses all conformational isomers, regioisomers, and stereoisomers that can arise from a particular set of substituents. 
     A chemical “group” is described according to how that group is formally derived from a reference or “parent” compound, for example, by the number of hydrogen atoms formally removed from the parent compound to generate the group, even if that group is not literally synthesized in this manner. By way of example, an “alkyl group” formally can be derived by removing one hydrogen atom from an alkane, while an “alkylene group” formally can be derived by removing two hydrogen atoms from an alkane. Moreover, a more general term can be used to encompass a variety of groups that formally are derived by removing any number (“one or more”) hydrogen atoms from a parent compound, which in this example can be described as an “alkane group,” and which encompasses an “alkyl group,” an “alkylene group,” and materials have three or more hydrogens atoms, as necessary for the situation, removed from the alkane. Throughout, the disclosure of a substituent, ligand, or other chemical moiety can constitute a particular “group” implies that the well-known rules of chemical structure and bonding are followed when that group is employed as described. When describing a group as being “derived by,” “derived from,” “formed by,” or “formed from,” such terms are used in a formal sense and are not intended to reflect any specific synthetic methods or procedure, unless specified otherwise or the context requires otherwise. 
     The term “organyl group” is used herein in accordance with the definition specified by IUPAC: an organic substituent group, regardless of functional type, having one free valence at a carbon atom. Similarly, an “organylene group” refers to an organic group, regardless of functional type, derived by removing two hydrogen atoms from an organic compound, either two hydrogen atoms from one carbon atom or one hydrogen atom from each of two different carbon atoms. An “organic group” refers to a generalized group formed by removing one or more hydrogen atoms from carbon atoms of an organic compound. Thus, an “organyl group,” an “organylene group,” and an “organic group” can contain organic functional group(s) and/or atom(s) other than carbon and hydrogen, that is, an organic group can comprise functional groups and/or atoms in addition to carbon and hydrogen. For instance, non-limiting examples of atoms other than carbon and hydrogen include halogens, oxygen, nitrogen, phosphorus, and the like. Non-limiting examples of functional groups include ethers, aldehydes, ketones, esters, sulfides, amines, phosphines, and so forth. An “organyl group,” “organylene group,” or “organic group” can be aliphatic, inclusive of being cyclic or acyclic, or can be aromatic. “Organyl groups,” “organylene groups,” and “organic groups” also encompass heteroatom-containing rings, heteroatom-containing ring systems, heteroaromatic rings, and heteroaromatic ring systems. “Organyl groups,” “organylene groups,” and “organic groups” can be linear or branched unless otherwise specified. Finally, it is noted that the “organyl group,” “organylene group,” or “organic group” definitions include “hydrocarbyl group,” “hydrocarbylene group,” “hydrocarbon group,” respectively, and “alkyl group,” “alkylene group,” and “alkane group,” respectively, as members. 
     For the purposes of this application, the term or variations of the term “organyl group consisting of inert functional groups” refers to an organyl group wherein the organic functional group(s) and/or atom(s) other than carbon and hydrogen present in the functional group are restricted to those functional group(s) and/or atom(s) other than carbon and hydrogen which do not complex with a metal compound and/or are inert under the process conditions defined herein. Thus, the term or variation of the term “organyl group consisting of inert functional groups” further defines the particular organyl groups that can be present within the organyl group consisting of inert functional groups. Additionally, the term “organyl group consisting of inert functional groups” can refer to the presence of one or more inert functional groups within the organyl group. The term or variation of the term “organyl group consisting of inert functional groups” definition includes the hydrocarbyl group as a member (among other groups). Similarly, an “organylene group consisting of inert functional groups” refers to an organic group formed by removing two hydrogen atoms from one or two carbon atoms of an organic compound consisting of inert functional groups and an “organic group consisting of inert functional groups” refers to a generalized organic group consisting of inert functional groups formed by removing one or more hydrogen atoms from one or more carbon atoms of an organic compound consisting of inert functional groups. 
     For purposes of this application, an “inert functional group” is a group which does not substantially interfere with the process described herein in which the material having an inert functional group takes part and/or does not complex with the metal compound of the metal complex. The term “does not complex with the metal compound” can include groups that could complex with a metal compound but in particular molecules described herein may not complex with a metal compound due to its positional relationship within a ligand. For example, while an ether group can complex with a metal compound, an ether group located at a para position of a substituted phenyl phosphinyl group in a N 2 -phosphinyl amidine can be an inert functional group because a single metal compound cannot complex with both the para ether group and the N 2 -phosphinyl amidine group in a single metal complex molecule. Thus, the inertness of a particular functional group is not only related to the functional group&#39;s inherent inability to complex the metal compound but can also be related to the functional group&#39;s position within the metal complex. Non-limiting examples of inert functional groups which do not substantially interfere with processes described herein can include halo (fluoro, chloro, bromo, and iodo), nitro, hydrocarboxy groups (e.g., alkoxy, and/or aroxy, among others), sulfidyl groups, and/or hydrocarbyl groups, among others. 
     The term “hydrocarbon” whenever used in this specification and claims refers to a compound containing only carbon and hydrogen. Other identifiers can be utilized to indicate the presence of particular groups in the hydrocarbon (e.g. halogenated hydrocarbon indicates that the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the hydrocarbon). The term “hydrocarbyl group” is used herein in accordance with the definition specified by IUPAC: a univalent group formed by removing a hydrogen atom from a hydrocarbon. Similarly, a “hydrocarbylene group” refers to a group formed by removing two hydrogen atoms from a hydrocarbon, either two hydrogen atoms from one carbon atom or one hydrogen atom from each of two different carbon atoms. Therefore, in accordance with the terminology used herein, a “hydrocarbon group” refers to a generalized group formed by removing one or more hydrogen atoms (as necessary for the particular group) from a hydrocarbon. A “hydrocarbyl group,” “hydrocarbylene group,” and “hydrocarbon group” can be acyclic or cyclic groups, and/or can be linear or branched. A “hydrocarbyl group,” “hydrocarbylene group,” and “hydrocarbon group” can include rings, ring systems, aromatic rings, and aromatic ring systems, which contain only carbon and hydrogen. “Hydrocarbyl groups,” “hydrocarbylene groups,” and “hydrocarbon groups” include, by way of example, aryl, arylene, arene, alkyl, alkylene, alkane, cycloalkyl, cycloalkylene, cycloalkane, aralkyl, aralkylene, and aralkane groups, among other groups, as members. 
     The term “alkane” whenever used in this specification and claims refers to a saturated hydrocarbon compound. Other identifiers can be utilized to indicate the presence of particular groups in the alkane (e.g. halogenated alkane indicates that the presence of one or more halogen atoms replacing an equivalent number of hydrogen atoms in the alkane). The term “alkyl group” is used herein in accordance with the definition specified by IUPAC: a univalent group formed by removing a hydrogen atom from an alkane. Similarly, an “alkylene group” refers to a group formed by removing two hydrogen atoms from an alkane (either two hydrogen atoms from one carbon atom or one hydrogen atom from two different carbon atoms). An “alkane group” is a general term that refers to a group formed by removing one or more hydrogen atoms (as necessary for the particular group) from an alkane. An “alkyl group,” “alkylene group,” and “alkane group” can be acyclic or cyclic groups, and/or can be linear or branched unless otherwise specified. Primary, secondary, and tertiary alkyl groups are derived by removal of a hydrogen atom from a primary, secondary, or tertiary carbon atom, respectively, of an alkane. The n-alkyl group can be derived by removal of a hydrogen atom from a terminal carbon atom of a linear alkane. 
     An aliphatic compound is an acyclic or cyclic, saturated or unsaturated carbon compound, excluding aromatic compounds. Thus, an aliphatic compound is an acyclic or cyclic, saturated or unsaturated carbon compound, excluding aromatic compounds; that is, an aliphatic compound is a non-aromatic organic compound. An “aliphatic group” is a generalized group formed by removing one or more hydrogen atoms (as necessary for the particular group) from the carbon atom of an aliphatic compound. Aliphatic compounds and therefore aliphatic groups can contain organic functional group(s) and/or atom(s) other than carbon and hydrogen. 
     The term “substituted” when used to describe a compound or group, for example, when referring to a substituted analog of a particular compound or group, is intended to describe any non-hydrogen moiety that formally replaces a hydrogen in that group, and is intended to be non-limiting. A group or groups can also be referred to herein as “unsubstituted” or by equivalent terms such as “non-substituted,” which refers to the original group in which a non-hydrogen moiety does not replace a hydrogen within that group. “Substituted” is intended to be non-limiting and include inorganic substituents or organic substituents. 
     The term “olefin” whenever used in this specification and claims refers to hydrocarbons that have at least one carbon-carbon double bond that is not part of an aromatic ring or an aromatic ring system. The term “olefin” includes aliphatic and aromatic, cyclic and acyclic, and/or linear and branched hydrocarbons having at least one carbon-carbon double bond that is not part of an aromatic ring or ring system unless specifically stated otherwise. Olefins having only one, only two, only three, etc. . . . carbon-carbon double bonds can be identified by use of the term “mono,” “di,” “tri,” etc. . . . within the name of the olefin. The olefins can be further identified by the position of the carbon-carbon double bond(s). 
     The term “alkene” whenever used in this specification and claims refers to a linear or branched aliphatic hydrocarbon olefin that has one or more carbon-carbon double bonds. Alkenes having only one, only two, only three, etc. . . . such multiple bonds can be identified by use of the term “mono,” “di,” “tri,” etc. . . . within the name. Alkenes can be further identified by the position of the carbon-carbon double bond(s). Other identifiers can be utilized to indicate the presence or absence of particular groups within an alkene. For example, a haloalkene refers to an alkene having one or more hydrogen atoms replaced with a halogen atom. 
     The term “alpha olefin” as used in this specification and claims refers to an olefin that has a carbon-carbon double bond between the first and second carbon atoms of the longest contiguous chain of carbon atoms. The term “alpha olefin” includes linear and branched alpha olefins unless expressly stated otherwise. In the case of branched alpha olefins, a branch can be at the 2-position (a vinylidene) and/or the 3-position or higher with respect to the olefin double bond. The term “vinylidene” whenever used in this specification and claims refers to an alpha olefin having a branch at the 2-position with respect to the olefin double bond. By itself, the term “alpha olefin” does not indicate the presence or absence of other carbon-carbon double bonds unless explicitly indicated. 
     The term “normal alpha olefin” whenever used in this specification and claims refers to a linear aliphatic mono-olefin having a carbon-carbon double bond between the first and second carbon atoms. It is noted that “normal alpha olefin” is not synonymous with “linear alpha olefin” as the term “linear alpha olefin” can include linear olefinic compounds having a double bond between the first and second carbon atoms and additional double bonds. 
     The term “reaction zone effluent,” and it derivatives generally refers to all materials which exit the reaction zone through a reaction zone outlet which discharges a reaction mixture and can include reaction system feed(s) (e.g., ethylene, catalyst system or catalyst system components, and/or organic reaction medium), and/or reaction product(s) (e.g., oligomer product including oligomers and non-oligomers. The term “reaction zone effluent” and its derivatives can be qualified to refer to certain portions by use of additional qualifying terms. For example, while reaction zone effluent refers to all material which exits the reaction system through the reaction zone outlet/discharge, a reaction zone oligomer product effluent refers to only the oligomer product within the reaction zone effluent. 
     The terms “room temperature” or “ambient temperature” are used herein to describe any temperature from 15° C. to 35° C. wherein no external heat or cooling source is directly applied to the reaction vessel. Accordingly, the terms “room temperature” and “ambient temperature” encompass the individual temperatures and any and all ranges, subranges, and combinations of subranges of temperatures from 15° C. to 35° C. wherein no external heating or cooling source is directly applied to the reaction vessel. The term “atmospheric pressure” is used herein to describe an earth air pressure wherein no external pressure modifying means is utilized. Generally, unless practiced at extreme earth altitudes, “atmospheric pressure” is about 1 atmosphere (alternatively, about 14.7 psi or about 101 kPa). 
     Features within this disclosure that are provided as minimum values can be alternatively stated as “at least” or “greater than or equal to” any recited minimum value for the feature disclosed herein. Features within this disclosure that are provided as maximum values can be alternatively stated as “less than or equal to” for the feature disclosed herein. 
     Within this disclosure the normal rules of organic nomenclature prevail. For instance, when referencing substituted compounds or groups, references to substitution patterns are taken to indicate that the indicated group(s) is (are) located at the indicated position and that all other non-indicated positions are hydrogen. For example, reference to a 4-substituted phenyl group indicates that there is a non-hydrogen substituent located at the 4 position and hydrogens located at the 2, 3, 5, and 6 positions. References to compounds or groups having substitution at positions in addition to the indicated position can be referenced using comprising or some other alternative language. For example a reference to a phenyl group comprising a substituent at the 4 position refers to a phenyl group having a non-hydrogen substituent group at the 4 position and hydrogen or any non-hydrogen group at the 2, 3, 5, and 6 positions. 
     Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. 
     Processes, systems, and/or reaction systems described herein can utilize steps, features, compounds and/or equipment which are independently described herein. The process and/or methods described herein may or may not utilize step identifiers (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second etc., among others), feature identifiers (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second etc., among others), and/or compound and/or composition identifiers (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second etc., among others). However, it should be noted that processes, systems, and/or reaction systems described herein can have multiple steps, features (e.g. reagent ratios, formation conditions, among other considerations), and/or multiple compounds and/or composition using no descriptor or sometimes having the same general identifier. Consequently, it should be noted that the processes, systems, and/or reaction systems methods described herein can be modified to use an appropriate step or feature identifier (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second etc., among others), feature identifier (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second etc., among others), and/or compound identifier (e.g., first, second, etc.) regardless of step, feature, and/or compound identifier utilized in the a particular aspect and/or embodiment described herein and that step or feature identifiers can be added and/or modified to indicate individual different steps/features/compounds utilized within the process, systems, and/or reaction systems methods without detracting from the general disclosure. 
     Processes, systems, and/or reaction systems for forming ethylene oligomer products are described herein. Such processes generally comprise contacting ethylene and a catalyst system to form an ethylene oligomer product under oligomerization conditions. As used herein, the term “oligomerization” and its derivatives, refers to processes which produce a mixture of products containing at least 70 weight percent products containing from 2 to 30 ethylene units. Similarly, as used herein, an “ethylene oligomer” is a product that contains from 2 to 30 ethylene units while an “ethylene oligomer product” includes all products made by the process including the “ethylene oligomers” and products which are not “ethylene oligomers” (e.g., products which contain more than 30 monomer units). Further the terms “ethylene oligomer product” and “ethylene oligomerization product” can be used interchangeably. 
     As used herein, the term “trimerization,” and it derivatives, refers to a process which produces a mixture of products containing at least 70 weight percent products containing three and only three ethylene units. As used herein a “trimer” is a product which contains three and only three ethylene units while a “trimerization product” includes all products made by the trimerization process including trimer and product which are not trimers (e.g. dimers or tetramers). Generally, a “trimerization” process using ethylene produces an oligomer product containing at least 70 weight percent hexene(s). 
     As used herein, the term “tetramerization,” and its derivatives, refers to a process which produces a mixture of products containing at least 70 weight percent products containing four and only four ethylene units. As used herein a “tetramer” is a product which contains four and only four ethylene units while a “tetramerization product” includes all products made by the tetramerization process including tetramer and products which are not tetramers (e.g. dimers or trimer). Generally, a “tetramerization” process using ethylene produces an oligomer product containing at least 70 weight percent octene(s). 
     As used herein, the term “trimerization and tetramerization,” and it derivatives, refers to a process which produces an oligomer product containing at least 70 weight percent products containing three and/or four and only three and/or four ethylene units. As used herein a “trimerization and tetramerization product” includes all products made by the “trimerization and tetramerization” process including trimer, tetramer, and products which are not trimers or tetramers (e.g. dimers). Generally, a “trimerization and tetramerization” process using ethylene produces an oligomer product containing at least 70 weight percent hexene(s) and/or octene(s). 
     As used herein, mass and weight in any form (e.g., mass or weight, mass ratio or weight ratio) can be used interchangeably. 
     As used herein, the phrases “the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone,” “the C 3+  olefin and the C 3+  olefin of the reaction zone C 3+  olefin:ethylene weight ratio is not an ethylene oligomer formed in-situ within the reaction zone,” “the C 3+  olefin of the reaction zone and/or the C 3+  olefin of the C 3+  olefin to ethylene reaction zone weight ratio is not an ethylene oligomer formed in-situ within the reaction zone,” and similar terms used herein, refer to the C 3+  olefin which is used in particular aspects and embodiments disclosed herein. In particular, these phases specifically indicate that the C 3+  olefin to which they refer is not an ethylene oligomer formed in-situ within the reaction zone. That is to say that while the C 3+  olefin to which they refer can have the identity of an ethylene oligomer that is formed in the reaction zone, the C 3+  olefin to which they refer was not formed in the reaction as a consequence of the oligomerization reaction the is occurring in the reaction zone. For example, an olefin comprising 1-hexene and/or 1-octene can be added to the reaction which is producing 1-hexene and/or 1-octene, however, since the 1-hexene and/or 1-octene was added to the reaction, it is not an ethylene oligomer produced in-situ within the reaction zone and thus would be considered in the noted phrases while the 1-hexene and/or 1-octene produce in-situ within the reaction zone would not be not considered in the noted phrases. 
     Various aspects and embodiments described herein may refer to a substituted group or compound. In an embodiment, each substituent of any aspect or embodiment calling for a substituent can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. In an embodiment, each hydrocarbyl substituent can be a C 1  to C 10  hydrocarbyl group; or alternatively, a C 1  to C 5  hydrocarbyl group. In an embodiment, each hydrocarboxy group can be a C 1  to C 10  hydrocarboxy group; or alternatively, a C 1  to C 5  hydrocarboxy group. 
     In an embodiment, any halide substituent of any aspect or embodiment calling for a substituent can be a fluoride, chloride, bromide, or iodide; alternatively, a fluoride or chloride. In some embodiments, any halide substituent of any aspect or embodiment calling for a substituent can be a fluoride; alternatively, a chloride; alternatively, a bromide; or alternatively, an iodide. 
     In an embodiment, any hydrocarbyl substituent of any aspect or embodiment calling for a substituent can be an alkyl group, an aryl group, or an aralkyl group; alternatively, an alkyl group; alternatively, an aryl group; or alternatively, an aralkyl group. In an embodiment, any alkyl substituent of any aspect or embodiment calling for a substituent can be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a 2-pentyl group, a 3-pentyl group, a 2-methyl-1-butyl group, a tert-pentyl group, a 3-methyl-1-butyl group, a 3-methyl-2-butyl group, or a neo-pentyl group; alternatively, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, or a neo-pentyl group; alternatively, a methyl group; alternatively, an ethyl group; alternatively, an isopropyl group; alternatively, a tert-butyl group; or alternatively, a neo-pentyl group. In an embodiment, any aryl substituent of any aspect or embodiment calling for a substituent can be phenyl group, a tolyl group, a xylyl group, or a 2,4,6-trimethylphenyl group; alternatively, a phenyl group; alternatively, a tolyl group, alternatively, a xylyl group; or alternatively, a 2,4,6-trimethylphenyl group. In an embodiment, any aralkyl substituent of any aspect or embodiment calling for a substituent can be benzyl group or an ethylphenyl group (2-phenyleth-1-yl or 1-phenyleth-1-yl); alternatively, a benzyl group; alternatively, an ethylphenyl group; alternatively a 2-phenyleth-1-yl group; or alternatively, a 1-phenyleth-1-yl group. 
     In an embodiment, any hydrocarboxy substituent of any aspect or embodiment calling for a substituent can be an alkoxy group, an aryloxy group, or an aralkoxy group; alternatively, an alkoxy group; alternatively, an aryloxy group, or an aralkoxy group. In an embodiment, any alkoxy substituent of any aspect or embodiment calling for a substituent can be a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentoxy group, a 2-pentoxy group, a 3-pentoxy group, a 2-methyl-1-butoxy group, a tert-pentoxy group, a 3-methyl-1-butoxy group, a 3-methyl-2-butoxy group, or a neo-pentoxy group; alternatively, a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a neo-pentoxy group; alternatively, a methoxy group; alternatively, an ethoxy group; alternatively, an isopropoxy group; alternatively, a tert-butoxy group; or alternatively, a neo-pentoxy group. In an embodiment, any aryloxy substituent of any aspect or embodiment calling for a substituent can be phenoxy group, a toloxy group, a xyloxy group, or a 2,4,6-trimethylphenoxy group; alternatively, a phenoxy group; alternatively, a toloxy group, alternatively, a xyloxy group; or alternatively, a 2,4,6-trimethylphenoxy group. In an embodiment, any aralkoxy substituent of any aspect or embodiment calling for a substituent can be benzoxy group. 
     Aspects disclosed herein can provide the materials listed as suitable for satisfying a particular feature of the embodiment delimited by the term “or.” For example, a particular feature of the disclosed subject matter can be disclosed as follows: Feature X can be A, B, or C. It is also contemplated that for each feature the statement can also be phrased as a listing of alternatives such that the statement “Feature X is A, alternatively B, or alternatively C” is also an embodiment of the present disclosure whether or not the statement is explicitly recited. 
     Disclosed herein are processes, systems, and reactions systems for the oligomerization of ethylene to form an ethylene oligomer product comprising normal linear alpha olefins (NAO). In particular, processes, systems, and/or reaction systems described herein can selectively trimerize, tetramerize, or trimerize and tetramerize ethylene to produce an ethylene oligomer product containing hexenes (e.g., 1-hexene) and/or octenes (e.g., 1-octene). It has been unexpectedly found that the selective ethylene oligomerization processes, systems, and/or reaction systems using the catalyst systems disclosed herein are sensitive to specific reactor feed conditions. It has been unexpectedly found that large amounts of polymer can form during the startup of the reaction zone of a selective ethylene oligomerization. This polymer formation can decrease as reaction zone on stream time increases. Particularly, and while not wishing to be bound by theory, it is believed that in the absence of a significant amount of C 3+  olefin the catalyst systems disclosed herein can have a greater propensity to produced polymer and thus during a reaction zone startup when very little olefin is present the catalyst system can produce a large amount of polymer. It has been discovered that the presence of a C 3+  olefin during the initial phase of selective ethylene oligomerization (e.g., during the startup of a selective ethylene oligomerization reaction zone) can reduce that amount of polymer formed and can lead to the improved operation of processes, systems, and/or reaction systems for selective ethylene oligomerizations. It has also believed, without being limited by theory, that polymer can form with use of the herein disclosed selective oligomerization catalyst systems when concentrated portions of ethylene are contacted with a catalyst system. Thus, the contacting of a high concentration of ethylene with the selective ethylene oligomerization catalyst system can be another situation which can make polymer plugging and/or fouling of reaction zone components a limiting factor in oligomer production. In this later situation, it has been discovered that contacting (or diluting) the ethylene with an organic reaction medium prior to contacting ethylene with the catalyst system can reduce polymer formation when compared to contacting a high concentration of ethylene with the catalyst system and provide improved operation of processes, systems, and/or reaction systems. Further it has be found that 1) the presence of a C 3+  olefin during the startup of a selective ethylene oligomerization and 2) the contacting (or diluting) the ethylene with organic reaction medium prior to the contact of the ethylene with the catalyst systems either during the startup of an selective ethylene oligomerization, after the startup of a selective ethylene oligomerization, or both can lead to improved operation of processes, systems, and/or reaction systems for selective ethylene oligomerizations. The disclosed processes, systems, and/or reaction systems can reduce the amount of polymer formed 1) during startup of a selective ethylene oligomerization reaction, 2) reduce the amount of polymer formed during normal operation of a selective ethylene oligomerization reaction, and/or 3) increases hexenes and/or octenes productivity and/or production and thus avoid fouling and/or plugging of the reaction zone and/or reaction system components. 
     The disclosed processes, systems, and/or reaction systems (e.g., those illustrated in  FIGS. 1 to 3 ) can comprise a) contacting i) ethylene, ii) a catalyst system comprising (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, (a) a chromium component comprising a chromium compound heteroatomic ligand complex, and (b) an aluminoxane), iii) an organic reaction medium, and iv) optionally hydrogen; and forming an ethylene oligomer product in a reaction zone. In an embodiment, a C 3+  olefin can be present in the reaction zone of the disclosed processes, systems, and/or reaction systems for a period of time, where the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. In a combinable embodiment of the processes, systems, and/or reaction systems disclosed herein, the reaction zone can have a C 3+  olefin to ethylene reaction zone weight ratio that over a period of time decreases from at least an initial value (any disclosed herein) to less than a final value (any disclosed herein). In an embodiment of the processes, systems, and/or reaction systems disclosed herein, the period of time can be initiated at a point in time when the reaction zone is not producing ethylene oligomer product and/or when the flow rate of ethylene is zero. 
     A disclosed process can comprise a) introducing into a reaction zone containing a C 3+  olefin and optionally an organic reaction medium wherein the reaction zone can be substantially devoid of ethylene; i) ethylene ii) a catalyst system comprising (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iii) the organic reaction medium, and iv) optionally hydrogen; and b) forming an ethylene oligomer product in the reaction zone. In an embodiment of this process, the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. In a combinable embodiment of this process, the reaction zone can have a C 3+  olefin to ethylene zone mass ratio that over a period of time decreases from at least an initial value (any disclosed herein) to less than a final value (any disclosed herein). 
     A disclosed process or system can comprise a) contacting in a reaction zone i) a C 3+  olefin, ii) ethylene, iii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand, and (c) an aluminoxane (any disclosed herein) (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex, and (b) an aluminoxane), iv) an organic reaction medium, and v) optionally hydrogen into the reaction zone; and c) forming an ethylene oligomer product. 
     Another disclosed process can comprise a) contacting i) ethylene, ii) a catalyst system comprising (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex, and (b) an aluminoxane), iii) an organic reaction medium, and iv) optionally hydrogen in a reaction zone; b) forming an ethylene oligomer product in the reaction zone; wherein ethylene, the catalyst system, and the organic reaction medium are introduced into the reaction zone and for a period of time a C 3+  olefin is introduced into the reaction zone. In an embodiment, ethylene, the organic reaction medium, and for the period of time the C 3+  olefin can be separately introduced into the reaction zone; alternatively, ethylene and at least a portion of the organic reaction medium can be contacted to form a feedstock mixture prior to the ethylene contacting the catalyst system and the feedstock mixture can be introduced into the reaction zone, and for the period of time the C 3+  olefin can be separately introduced to the reaction zone; or alternatively, ethylene, at least a portion of the organic reaction medium, and for the period of time the C 3+  olefin can be contacted to form a feedstock mixture prior to the ethylene contacting the catalyst system and the feedstock mixture introduced into the reaction zone. When the ethylene and the C 3+  olefin are separately introduced into the reaction zone, the processes can further comprise introducing the C 3+  olefin to the reaction zone prior to introducing the ethylene, the catalyst system, or both the ethylene and the catalyst system to the reaction zone. In an embodiment, the reaction zone can have a C 3+  olefin:ethylene weight ratio that over a period of time decreases from at least an initial value (any disclosed herein) to less than a final value (any disclosed herein) and wherein the C 3+  olefin and the C 3+  olefin of the reaction zone C 3+  olefin:ethylene weight ratio is not an ethylene oligomer formed in-situ within the reaction zone. 
     A disclosed process can comprise a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane (or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane); b) for a period of time separately feeding to the reaction zone a feedstock mixture comprising ethylene and i) a C 3+  olefin, and ii) at least a portion of an organic reaction medium, or iii) combinations of i) and ii); wherein the feedstock mixture is substantially free of the catalyst system; c) contacting the catalyst system and the feedstock mixture in the reaction zone; and d) forming an ethylene oligomer product in the reaction zone. Another disclosed process can comprise a) contacting i) ethylene, at least a portion of an organic reaction medium, and for a period of time a C 3+  olefin to form a feedstock mixture; b) subsequent to a), contacting in a reaction zone the feedstock mixture with a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane (or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane); and c) forming an ethylene oligomer product in the reaction zone. A further disclosed process can comprise a) diluting ethylene by addition of i) at least a portion of an organic reaction medium, ii) for a period of time a C 3+  olefin, or iii) for a period of time at least a portion of an organic reaction medium and C 3+  olefin to form a feedstock mixture prior to contacting the ethylene with a catalyst system in a reaction zone; b) contacting in the reaction zone the feedstock mixture and the catalyst system, wherein the catalyst system comprises i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane (alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane); and c) forming an ethylene oligomer product in the reaction zone. A disclosed system can comprise: a) a feedstock mixture comprising ethylene, an organic reaction medium, and for a period of time a C 3+  olefin; b) a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane (or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane; and c) a reaction zone receiving the feedstock mixture separately from the catalyst stream. In an embodiment, the system can further comprise a reaction zone effluent line comprising an ethylene oligomer product formed in the reaction zone. In some embodiments of the processes and systems, 1) the C 3+  olefin can be dispersed in the feedstock mixture, for a period of time, prior to introducing/feeding the feedstock mixture into the reaction zone and/or 2) ethylene can be dispersed within the feedstock mixture prior to ethylene contacting the catalyst system. In another combinable embodiment of the processes and systems, ethylene can be dispersed within the feedstock mixture prior to introduction of the feedstock mixture into the reaction zone. In an embodiment of the processes and systems, the period of time can occur during a reaction zone startup. 
     A disclosed process can comprise a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane (or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane); b) separately feeding to the reaction zone a feedstock mixture comprising i) ethylene, ii) an organic reaction medium, and iii) for a period of time a C 3+  olefin to contact the catalyst system. In an embodiment, the period of time can occur during a reaction zone startup. Another disclosed process can comprise a startup of a reaction zone, where the process can comprise for a period of time contacting in the reaction zone 1) ethylene, 2) a catalyst system comprising a) a chromium component comprising a chromium compound, b) a heteroatomic ligand, and c) an aluminoxane (or alternatively, a catalyst system comprising a) a chromium component comprising a heteroatomic ligand chromium compound complex) and b) an aluminoxane), 3) an organic reaction medium, and 4) optionally hydrogen to form an ethylene oligomer product; wherein: the catalyst system can be introduced/fed to the reaction zone in a feedstock mixture comprising i) ethylene, ii) at least a portion of the organic reaction medium, and iii) for a period of time a C 3+  olefin is introduce/fed to the reaction zone, wherein the feedstock mixture is substantially free of the catalyst system prior to the feedstock mixture contacting the catalyst system in the reaction zone. In an embodiment of these processes, for the period of time the C 3+  olefin is part of the feedstock mixture introduced/fed to the reaction zone, the C 3+  olefin can be dispersed the feedstock mixture prior to introducing/feeding the feedstock mixture into the reaction zone and/or ethylene can be dispersed within the feedstock mixture prior to ethylene contacting the catalyst system. 
     A disclosed reaction system can comprise a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex, and (b) an aluminoxane) to the reaction zone; a second reaction zone inlet configured to introduce ethylene, an organic reaction medium, and optionally hydrogen to the reaction zone; a C 3+  olefin feed line in fluid communication with the first reaction zone inlet, the second reaction zone inlet, or a third reaction zone inlet configured to introduce a C 3+  olefin to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. In an embodiment, the reaction system can further comprise a catalyst system feed line flowing the catalyst system to the first reaction zone inlet; an ethylene feed line comprising the ethylene; an organic reaction medium feed line comprising the organic reaction medium, wherein the organic reaction medium feed line and the ethylene feed line can combine to yield a feedstock mixture which can introduced to the reaction zone via the second reaction zone inlet, wherein the C 3+  olefin feed line can combine with at least one of the catalyst system feed line, the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, or a dispersed feedstock mixture feed line formed by passing the feedstock mixture through a mixing device prior to flowing to the reaction zone via the second reaction zone inlet. In a combinable embodiment, the reaction system can further comprise a pump in fluid communication with the second reaction zone inlet and can be located upstream of a point where the ethylene feed line and the organic reaction medium feed line join to produce the feedstock mixture; and a mixing device positioned between i) the joining of the ethylene feed line and the organic reaction medium feed line and ii) the second reaction zone inlet to disperse the ethylene and the organic reaction medium prior to the feedstock mixture entering the reaction zone. In another combinable reaction system embodiment, during steady state operation the first reaction zone inlet can be configured to periodically or continuously introduce the catalyst system to the reaction zone, the second reaction zone inlet can be configured to periodically or continuously introduced the feedstock mixture to the reaction zone, and the one or more reaction zone outlets can be configured to periodically or continuously discharge the reaction zone effluent from the reaction zone. 
     Another disclosed reaction system can comprise a reaction zone; a reaction zone inlet configured to introduce a catalyst system, ethylene, an organic reaction medium, and a C 3+  olefin to the reaction zone; an ethylene feed line comprising ethylene, a C 3+  olefin feed line comprising a C 3+  olefin, an organic reaction medium feed line comprising an organic reaction medium and optionally a hydrogen feed line comprising hydrogen all in fluid communication with the reaction zone inlet, wherein the organic reaction medium feed line can combine with the ethylene feed line to form a feedstock mixture feed line in fluid communication with the reaction zone inlet; a catalyst system feed line comprising the catalyst system in fluid communication with the reaction zone inlet, wherein the catalyst system feed line combines with the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, or a dispersed feedstock mixture feed line formed by passing the feedstock mixture feed line through a mixing device; one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone, wherein the catalyst system comprises (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex, and (b) an aluminoxane), and wherein the C 3+  olefin feed line can join with one or more of the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, the dispersed feedstock mixture feed line, or a combined feed line formed by joining the catalyst system feed line and the dispersed feedstock mixture feed line. In an embodiment, the reaction system can further comprise a mixing device positioned between i) the joining of the ethylene feed line and the organic reaction medium feed line and ii) the reaction zone inlet to disperse the ethylene within the feedstock mixture prior to the feedstock mixture joining with the catalyst system and entering the reaction zone. In a combinable embodiment, the reaction zone inlet can be configured to periodically or continuously introduce the catalyst system and the feedstock mixture to the reaction zone, and the one or more reaction zone outlets can be configured to periodically or continuously discharge the reaction zone effluent from the reaction zone. 
     A further disclosed reaction system can comprise a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound, (b) a heteroatomic ligand, and (c) an aluminoxane (or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex, and (b) an aluminoxane) to the reaction zone; a second reaction zone inlet configured to introduce ethylene and optionally hydrogen to the reaction zone; a third reaction zone inlet configured to introduce an organic reaction medium to the reaction zone; a C 3+  olefin feed line in fluid communication with one or more of the first reaction zone inlet, the second reaction zone inlet, the third reaction zone inlet, or a fourth reaction zone inlet which is configured to introduce the C 3+  olefin directly to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. In an embodiment, the reaction system can further comprise a catalyst system feed line flowing the catalyst system to the first reaction zone inlet; an ethylene feed line flowing ethylene to the second reaction zone inlet; and an organic reaction medium feed line flowing the organic reaction medium to the third reaction zone inlet, wherein the C 3+  olefin feed line i) can combine with at least one of the catalyst system feed line, the ethylene feed line, or the organic reaction medium feed line, or ii) can flow directly to the fourth reaction zone inlet. 
     In an embodiment, the processes, systems, and/or reaction system disclosed herein can further comprise, removing/withdrawing a reaction zone effluent comprising an ethylene oligomer product from the reaction zone. In an embodiment, the processes, systems, and/or reactions systems disclosed herein can be continuous processes, systems, and/or reaction systems wherein the feeds (e.g., ethylene, catalyst system or catalyst system components, organic reaction medium, C 3+  (where applicable in the processes, systems, and/or reaction systems), and any other feeds can be periodically or continuously introduced/fed to the reaction zone and a reaction zone effluent comprising the ethylene oligomer product can be periodically or continuously removed/withdrawn from the reaction zone. 
     In an embodiment of the processes, systems, and/or reaction system disclosed herein, the reaction zone can have a C 3+  olefin to ethylene reaction zone mass ratio that over a period of time can decrease; or alternatively, have a C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone that over a period of time can decrease from at least an initial value (any disclosed herein) to less than a final value (any disclosed herein). Generally, the C 3+  olefin of the reaction zone and/or the C 3+  olefin of the C 3+  olefin to ethylene reaction zone mass ratio is not an ethylene oligomer formed in-situ within the reaction zone. In a combinable embodiment, the applicable processes, systems, and/or reaction system disclosed herein can have ethylene and the C 3+  olefin fed/introduced to the reaction zone (either separately, together in a feedstock mixture, or both) wherein a C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can decrease; or alternatively, decrease from at least an initial value to less than a final value over a period of time. In further combinable embodiment, the C 3+  olefin to ethylene reaction zone mass ratio and/or the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can decreases in steps; or alternatively, can decrease periodically or continuously. 
     Generally, the catalyst system, the catalyst system components (e.g., the chromium component, the aluminoxane, among others), the organic reaction medium, the ethylene oligomer product, the conditions at which the ethylene oligomer product can be formed (or the reaction zone can operate), the C 3+  olefin, the reaction zone, a reaction zone C 3+  olefin:ethylene weight ratio, a reaction zone period of time, a feedstock mixture C 3+  olefin:ethylene weight ratio, a feedstock mixture period of time, an ethylene to organic reaction medium mass ratio, an (ethylene+C 3+  olefin) to organic reaction medium mass ratio, components of the reaction system, and any other features disclosed herein for the processes, systems, and/or reaction system disclosed herein are independently described herein. Additionally, further steps that can be utilized in the processes, systems, and/or reaction system are independently disclosed herein. These independent descriptions can be utilized without limitation, and in any combination, to further describe the processes, systems, and/or reaction systems disclosed herein. In particular these independent descriptions can be utilized without limitation, and in any combination, to further describe the processes, systems, and/or reaction systems where for a period of time a C 3+  olefin which is not an ethylene oligomer formed in-situ within the reaction zone, is present in the reaction zone. 
     During the reaction zone period of time a C 3+  olefin:ethylene weight ratio in the reaction zone can decrease from at least an initial value to less than a final value. In an embodiment, the reaction zone C 3+  olefin:ethylene weight ratio at least initial value independently can be any at least initial value disclosed herein and the reaction zone C 3+  olefin:ethylene weight ratio less than final value independently can be any less than final value disclosed herein. In an embodiment, the reaction zone C 3+  olefin:ethylene weight ratio at least initial value can be a value of at least 0.5:1, 0.75:1, 1:1, 1.5:1, 2:1, 3:1, 5:1, 10:1, 25:1, 50:1, or 100:1. In an embodiment, the reaction zone C 3+  olefin:ethylene weight ratio less than final value can be a value less than 0.2:1, 0.15:1, 0.1:1, 0.08:1, 0.06:1, 0.04:1, 0.02:1, or 0.01:1. In an embodiment, the reaction zone C 3+  olefin:ethylene weight ratio can decrease from any reaction zone C 3+  olefin:ethylene weight ratio greater than initial value disclosed herein to any reaction zone C 3+  olefin:ethylene weight ratio less than final value disclosed herein. Thus, in some non-limiting embodiments, the reaction zone C 3+  olefin:ethylene weight ratio can decrease from at least 0.5:1 to less than 0.2:1, from at least 1:1 to less than 0.2:1, from at least 2:1 to less than 0.15:1, from at least 3:1 to less than 0.1:1, from at least 5:1 to less than 0.15:1, from at least 10:1 to less than 0.2:1, from a value of at least 100:1 to less than 0.1:1. Other embodiments, for which the reaction zone C 3+  olefin:ethylene weight ratio can decrease from a reaction zone C 3+  olefin:ethylene weight ratio initial value to a reaction zone C 3+  olefin:ethylene weight ratio final value are readily apparent to those skilled in the art with the aid of this disclosure. In an embodiment, the reaction zone period of time can begin when the reaction zone C 3+  olefin:ethylene weight ratio falls below the reaction zone C 3+  olefin:ethylene weight ratio greater than initial value. In an embodiment, the reaction zone period of time can end when the reaction zone C 3+  olefin:ethylene weight ratio falls below the less than final value. In an embodiment, the reaction zone period of time can begin when the reaction zone is not producing ethylene oligomer product and/or when the flow rate of ethylene to the reaction zone is zero. In an embodiment, the reaction zone period of time can encompass a time where the reaction zone C 3+  olefin:ethylene weight ratio decreases from about 1:0 to about 0:1. In an embodiment, the reaction zone period of time represents the startup of the reaction zone. 
     In any embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone (either separately, together in a feedstock mixture, or both), a C 3+  olefin:ethylene weight ratio fed/introduced (either separately, together in a feedstock mixture, or both) to the reaction zone can decrease from at least an initial value to less than a final value over a period of time. In an embodiment, the at least initial value of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone independently can be any at least initial value disclosed herein and the less than final value of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone independently can be any less than final value disclosed herein. In an embodiment, the at least initial value can be a value of at least 0.5:1, 0.75:1, 1:1, 1.5:1, 2:1, 3:1, 5:1, 10:1, 25:1, 50:1, or 100:1. In an embodiment, the less than final value can be a value less than 0.2:1, 0.15:1, 0.1:1, 0.08:1, 0.06:1, 0.04:1, 0.02:1, or 0.01:1. In an embodiment, the C 3+  olefin:ethylene weight ratio can decrease from any greater than initial value disclosed herein to any less than final value disclosed herein. Thus, in some non-limiting embodiments, the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can decrease from at least 0.5:1 to less than 0.2:1, from at least 1:1 to less than 0.2:1, from at least 2:1 to less than 0.15:1, from at least 3:1 to less than 0.1:1, from at least 5:1 to less than 0.15:1, from at least 10:1 to less than 0.2:1, from a value of at least 100:1 to less than 0.1:1. Other embodiments for which the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can decrease from an initial value to a final value are readily apparent to those skilled in the art with the aid of this disclosure. In an embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can begin when the C3+ olefin:ethylene weight ratio falls below the greater than initial value. In an embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can end when the feedstock mixture C 3+  olefin:ethylene weight ratio falls below the less than final value. In another embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can begin when the feedstock mixture has an initial C 3+  olefin:ethylene weight ratio of about 1:0; or alternatively, the flow rate of ethylene is about zero. In an embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can end when the feedstock mixture has a C 3+  olefin:ethylene weight ratio of about 0:1; or alternatively, the flow rate of the C 3+  olefin is about 0. In an embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can encompass a time where the feedstock mixture C 3+  olefin:ethylene weight ratio decreases from about 1:0 to about 0:1. In an embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone, the period of time can occur during the startup of the reaction zone. 
     In an embodiment, the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease (e.g., from any at least initial value disclosed herein to any less than final value described herein) can provide a benefit to the ethylene oligomerization processes, systems, and/or reaction systems described herein (e.g., a decrease in polymer production among other benefits described herein). In an embodiment, the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease can be greater than or equal to 5, 10, 15, 20, 25, or 30 minutes; alternatively or additionally less than or equal to 6, 4, 3, 2, 1.5, or 1 hour. In an embodiment, the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease can range from any greater than or equal to value described herein to any less than or equal to described herein. In some non-limiting embodiments, the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease can range from greater than or equal to 5 minutes to less than or equal to 6 hours; alternatively, greater than or equal to 10 minutes to less than or equal to 4 hours; alternatively, greater than or equal to 15 minutes to less than or equal to 4 hours; alternatively, greater than or equal to 20 minutes to less than or equal to 3 hours; alternatively, greater than or equal to 25 minutes to less than or equal to 3 hours; alternatively, greater than or equal to 30 minutes to less than or equal to 3 hours; alternatively, greater than or equal to 30 minutes to less than or equal to 2 hours; or alternatively, greater than or equal to 30 minutes to less than or equal to 1.5 hours. Other ranges over which the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease are readily apparent to those skilled in the art with the aid of this disclosure. Additionally, multiple periods of time over which the reaction zone period of time and/or the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease can be utilized and these multiple periode of time can have the same duration; or alternatively, at least one of the multiple periods of time can have a duration which is different from the duration of at least another of the multiple periods of time. 
     The reaction zone period of time and the C 3+  olefin/ethylene feed period of time over which the C 3+  olefin:ethylene weight ratio can decrease can occur over the same time, e.g., simultaneously. Alternatively, a portion of the reaction zone period of time can overlap a portion of the C 3+  olefin/ethylene feed period of time. For example, the reaction zone period of time can lag behind the C 3+  olefin/ethylene feed period of time period since, due to residence time consideration for the reaction zone  110 , there will be a lag in time between when a decrease in the C 3+  olefin:ethylene weight ratio can be observed in the feed to the reaction zone  110  and when a decrease in the C 3+  olefin:ethylene weight ratio can be observed in the reaction zone  110  itself. Alternatively, the reaction zone period of time and the C 3+  olefin/ethylene feed period of time do not overlap. For example, the lag in time between when a decrease in the C 3+  olefin:ethylene weight ratio can be observed in the feed to the reaction zone  110  and when a decrease in the C 3+  olefin:ethylene weight ratio can be observed in the reaction zone  110  itself may be long enough that the periods of time (e.g., the reaction zone period of time and the C 3+  olefin/ethylene feed period of time) occur sequentially or in series (over time). 
     In any embodiment wherein ethylene and the C 3+  olefin are fed/introduced to the reaction zone (either separately, together in a feedstock mixture, or both), ethylene, the C 3+  olefin, or both can be contacted with the organic reaction medium (e.g., at least a portion of the organic reaction medium) prior to contacting the catalyst system. In other embodiments, the ethylene, the C 3+  olefin, or both can be dispersed with the organic reaction medium (e.g., at least a portion of the organic reaction medium) prior to contacting the catalyst system. 
     In an embodiment wherein the feedstock mixture comprises ethylene and the organic reaction medium (e.g., at least a portion of the organic reaction medium), ethylene and organic reaction medium can be contacted prior to ethylene contacting the catalyst system. In an embodiment, ethylene can be dispersed in the organic reaction medium (e.g., at least a portion of the organic reaction medium) prior to ethylene contacting the catalyst system. In some embodiments, ethylene and the organic reaction medium can be contacted, and/or the ethylene can be dispersed in the organic reaction medium prior to ethylene contacting the catalyst system in the reaction zone; or alternatively, prior to the ethylene contacting the catalyst system outside the reaction zone. In an embodiment, wherein ethylene and the organic reaction medium are contacted, and/or the ethylene is dispersed in the organic reaction medium prior to ethylene contacting the catalyst system in the reaction zone, the contact and/or dispersion can occur during the reaction zone period of time (e.g., during reaction zone startup), or after the reaction zone period of time (e.g., after reaction zone startup). 
     In an embodiment, wherein the feedstock mixture comprises ethylene, the C 3+  olefin, and the organic reaction medium (e.g., at least a portion of the organic reaction medium), ethylene, the C 3+  olefin, and organic reaction medium can be contacted prior to ethylene contacting the catalyst system. In an embodiment, ethylene and/or the C 3+  olefin can be dispersed in the organic reaction medium (e.g., at least a portion of the organic reaction medium) prior to feedstock mixture contacting the catalyst system. In some embodiments, ethylene and/or the C 3+  olefin and the organic reaction medium can be contacted, and/or the ethylene and/or C 3+  olefin can be dispersed in the organic reaction medium prior to ethylene contacting the catalyst system in the reaction zone; or alternatively, prior to the ethylene contacting the catalyst system outside the reaction zone. 
     In another aspect of the disclosed processes, systems, and/or reaction systems, the presence of the C 3+  olefin in the reaction zone for a period of time or the introduction/feeding of the C 3+  olefin to the reaction zone for a period time can be utilized in conjunction with the contacting ethylene with at least a portion of the organic reaction medium to form a feedstock mixture prior to contacting ethylene with the catalyst system. In this aspect, the contacting of the ethylene with the at least a portion of the organic reaction medium can occur during the period of time of where the C 3+  olefin is present in the reaction zone for a period of time or the where C 3+  olefin is introduced/fed to the reaction zone; alternatively, after the period of time of where the C 3+  olefin is present in the reaction zone for a period of time or the where C 3+  olefin is introduced or fed to the reaction zone; or alternatively, during and after the period of time of where the C 3+  olefin is present in the reaction zone for a period of time or the where C 3+  olefin is introduced or fed to the reaction zone. In some embodiments, where ethylene is contacted with at least a portion of the organic reaction medium to form a feedstock mixture prior to contacting ethylene with the catalyst system, the C 3+  olefin can be present in the feedstock mixture for the period of time when the C 3+  olefin is introduced/fed to the reaction zone. In this situation, the C 3+  olefin can be contacted 1) with ethylene before the ethylene contacts the organic reaction medium; 2) with the organic reaction medium prior to ethylene contacting the organic reaction medium; and/or 3) with the feedstock mixture after the ethylene contacts the organic reaction medium. In an embodiment where the C 3+  olefin is part of the feedstock mixture during the period of time of where the C 3+  olefin can be introduced/fed to the reaction zone, the minimum (ethylene+C 3+  olefin) concentration in the feedstock mixture can be 4 mass %, 10 mass %, 25 mass %, 35 mass %, or 40 mass % based upon the total mass of the feedstock mixture; alternatively or additionally, the maximum (ethylene+C 3+  olefin) concentration of the feedstock mixture cam be 65 mass %, 60 mass %, 55 mass %, 50 mass %, 48 mass % based upon the total mass in the feedstock mixture. In an embodiment, the (ethylene+C 3+  olefin) concentration in the feedstock mixture can from any minimum (ethylene+C 3+  olefin) concentration in the feedstock mixture disclosed herein to any maximum (ethylene+C 3+  olefin) concentration in the feedstock mixture disclosed herein. In some non-limiting embodiments, the (ethylene+C 3+  olefin) concentration in the feedstock mixture can be in a range of from 4 mass % to 60 mass %, from 10 mass % to 60 mass %, from 25 mass % to 55 mass %, 35 mass % to 50 mass %, or 40 mass % to 48 mass % based upon the total mass in the feedstock mixture. Other (ethylene+C 3+  olefin) concentrations in the feedstock mixture ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     It is contemplated that the C 3+  olefin can be present in the reaction zone of the disclosed processes, systems, and reaction systems (e.g.,  FIGS. 1 to 3 ) via: i) combination of the C 3+  olefin with ethylene before ethylene is introduced/fed to the reaction zone or before ethylene joins with organic reaction medium to form the feedstock mixture, ii) combination of the C 3+  olefin with organic reaction medium before the organic reaction medium is introduced/fed to the reaction zone or before ethylene joins with organic reaction medium to form the feedstock mixture, iii) introducing/feeding the C 3+  olefin directly to the reaction zone; iv) combination of the C 3+  olefin with the catalyst system prior to the catalyst system being introduced/fed to the reaction zone or prior to the catalyst system combining with another line outside the reaction zone; v) combination of the C 3+  olefin with the feedstock mixture, vi) combination of the C 3+  olefin with the dispersed feedstock mixture when the feedstock mixture is dispersed prior to entering the reaction zone; vii) combination of the C 3+  olefin with a combined feed stream which includes ethylene, the organic reaction medium, and the catalyst system prior to being introduced/fed to the reaction zone; or viii) any combination of i)-vii). It is also contemplated that when a feedstock mixture comprising ethylene is formed, the feedstock mixture can be contacted with the catalyst system inside the reaction zone (an example of which is shown in  FIG. 2 ) or outside the reaction zone (an example of which is shown in  FIG. 3 ). It is further contemplated that ethylene and the organic reaction medium can be dispersed in the feedstock mixture prior to introducing the feedstock mixture to the reaction zone and prior to or after contact of the feedstock mixture with the catalyst system. For example, as shown in  FIG. 2 , the catalyst system can be introduced into the reaction zone (via line  152  which feeds to the first reaction zone inlet  111 , discussed in detail below) separately from feedstock mixture (via line  192  which feeds to the reaction zone inlet  113 , also discussed in detail below). Alternatively, as shown in  FIG. 3 , the catalyst system and the feedstock mixture can be contacted prior to entering the reaction zone  110  (line  152  combines with dispersed line  192  before the components enter the reaction zone inlet  119 , discussed in detail herein). 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can have operating conditions) during the reaction zone period of time where the reaction zone C 3+  olefin:ethylene weight ratio is decreasing. In some embodiments, the ethylene oligomer product formation conditions (or reaction zone operating conditions) can be any described herein with the exception of any ethylene oligomer product formation conditions (or reaction zone operating conditions) which do not take into consideration embodiments and aspects that the reaction zone contains both ethylene and the C 3+  olefin and/or C 3+  olefin:ethylene reaction zone weight ratio is decreasing (e.g., the reaction zone ethylene concentration, the ethylene to chromium mass ratio, among others). Alternatively, the ethylene oligomer product formation conditions (or reaction zone operating conditions) can be any of the ethylene oligomer product formation conditions (or the reaction zone operating conditions) described herein which take into consideration that the reaction zone contains both ethylene and the C 3+  olefin and/or C 3+  olefin:ethylene reaction zone weight ratio is decreasing (e.g., the reaction zone ethylene concentration, the ethylene to chromium mass ratio, among others). 
     Aspects of the disclosure relate to initiating ethylene oligomerization (startup) of a reaction zone in any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein. Startup can occur when the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) is empty or after reaction zone cleaning (a hard startup) or when the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) contains components for an ethylene oligomerization reaction but is not producing ethylene oligomer product (a soft startup). An example of a soft startup situation can be when the flow of ethylene and/or catalyst system is temporarily stopped to address a process, system or reaction system issue and it is desired to again start oligomerization reactions without emptying and/or cleaning the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ). 
     Startup of any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein can include a reaction zone commencing stage (hereafter commencing stage), and/or a reaction zone phasing stage (hereafter phasing stage). In some embodiments, the startup of any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein can further include an optional reaction zone filling stage (hereafter filling stage). Temporally, the filling stage can occur before the commencing stage and phasing stage. 
     The filling stage of any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein can involve filling the reaction zone (e.g., reaction zone  110 ), either empty, already containing components for an ethylene oligomerization reaction, or simultaneously with one or more components for an ethylene oligomerization reaction, with the C 3+  olefin (e.g., using any one or more appropriate C 3+  olefin lines in  FIGS. 1-3 ). Reaction zone filling can occur for any period of time needed to provide the desired amount of C 3+  olefin to the reaction zone (or attain any desired reaction zone C 3+  olefin:ethylene ratio disclosed herein). In an aspect, the reaction zone (e.g., reaction zone  110 ) can be filled with the C 3+  olefin while no ethylene is being fed or introduced into the reaction zone. Alternatively, the reaction zone (e.g., reaction zone  110 ) can be filled with the C 3+  olefin and ethylene (using any C3+ olefin:ethylene weight ratio disclosed herein, or to achieve any reaction zone C 3+  olefin to ethylene C 3+  olefin weight ratio disclosed herein). In some embodiments, the reaction zone can contain, or can be substantially devoid of, organic reaction medium, catalyst system, hydrogen, and/or scrub agent. 
     The commencing stage can involve feeding/introducing one or more of the ethylene oligomerization components to the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ). During the commencing stage, the organic reaction medium, the catalyst system, optionally the C 3+  olefin, and optionally, hydrogen can be fed/introduced into the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) before ethylene is fed/introduced to the reaction zone. The organic reaction medium, the catalyst system, optionally the C 3+  olefin, and optionally hydrogen can be fed/introduced to the reaction zone in any manner and/or any order including adding one or more simultaneously. For example, a non-limiting order of feeding/introducing the ethylene oligomerization components to the reaction zone during startup can be to first feed/introduce organic reaction medium to the reaction zone (e.g., using any one or more appropriate lines  162 ,  191 ,  192 , and  193  in  FIGS. 1-3 ), then feed/introduce the catalyst system and optionally hydrogen to the reaction zone in any order (e.g., using the catalyst system feed line  152  and/or one or more appropriate lines  144 ,  142 ,  191 ,  102 , and  193  for hydrogen flow in  FIGS. 1-3 ), and then feed/introduce the C 3+  olefin to the reaction zone (e.g., using any one or more appropriate lines  146  and  147   a, b, c, d, e, f , or  g  in  FIGS. 1-3 ). Another non-limiting order of feeding/introducing the ethylene oligomerization components to the reaction zone during startup can be to first feed/introduce organic reaction medium to the reaction zone (e.g., using any one or more appropriate lines  162 ,  191 ,  192 , and  193  in  FIGS. 1-3 ), then feed/introduce the C 3+  olefin to the reaction zone (e.g., using any one or more appropriate lines  146  and  147   a, b, c, d, e, f , or  g  in  FIG. 1 ), and then then feed/introduce the catalyst system and optionally hydrogen to the reaction zone in any order (e.g., using the catalyst system feed line  152  and/or one or more appropriate lines  144 ,  142 ,  191 ,  102 , and  193  for hydrogen flow in  FIGS. 1-3 ). Other orders of feeding/introducing the ethylene oligomerization components to the reaction zone during startup are readily apparent to those having ordinary skill in the art. 
     In an alternative, the C 3+  olefin can be fed/introduced to the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) in the phasing stage (e.g., introduced simultaneously, but not necessarily combined with ethylene). In such alternative, the organic reaction medium, the catalyst system, and optionally, hydrogen can be fed/introduced to the reaction zone in the commencing stage in any order such as those described herein. In another alternative, the C 3+  olefin can be fed/introduced to the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) in the filling stage (e.g., using any one or more appropriate C 3+  olefin feed lines  146  and  147   a, b, c, d, e, f , or  g  in  FIGS. 1-3 ); that is, the C 3+  olefin is not introduced to the reaction zone in the commencing stage or the phasing stage. 
     The phasing stage or any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein can involve decreasing the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) C 3+  olefin:ethylene weight ratio over a period of time. In an embodiment, decreasing the reaction zone C 3+  olefin:ethylene weight ratio over a period of time can be accomplished by feeding/introducing ethylene to a reaction zone containing the C 3+  olefin and/or decreasing the C 3+  olefin:ethylene weight ratio of the C 3+  olefin and ethylene being fed/introduced to the reaction zone. In an aspect, the C 3+  olefin can be fed/introduced (e.g., using any one or more appropriate C 3+  olefin feed lines  146  and  147   a, b, c, d, e, f , or  g  in  FIGS. 1-3 ) to the reaction zone (e.g., reaction zone  110  of  FIGS. 1 to 3 ) in the filling stage, and then decreasing the reaction zone C 3+  olefin:ethylene weight ratio by feeding/introducing ethylene to the reaction zone using any one or more appropriate lines  142 ,  191 ,  192 , and  193  in  FIGS. 1-3 . In another aspect, the ethylene and C 3+  olefin can be fed/introduced (e.g., using any appropriate lines  142 ,  191 , 192 , and  193  for ethylene and one or more appropriate lines  146  and  147   a, b, c, d, e, f , or  g  for C 3+  olefin) to the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ) such that C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone and/or the reaction zone C 3+  olefin:ethylene weight ratio decreases from at least an initial value to less than a final value over a period of time. Embodiments for the decrease of the reaction zone C 3+  olefin:ethylene weight ratio and the decrease of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone are independently provided herein and can be utilized without limitation to further describe the phasing stage of any process, system, and/or reaction system (e.g.,  FIGS. 1 to 3 ) described herein. Without being limited by theory, it is believed that decreasing the reaction zone C 3+  olefin:ethylene weight ratio during reaction zone startup can reduce the formation of polymer during reaction zone startup (hard startup or soft startup) as described herein. 
     In an aspect, the phasing stage can be initiated by feeding/introducing ethylene to the reaction (e.g., reaction zone  110  of  FIGS. 1-3  using any appropriate line  142 ,  191 ,  192 , and  193  for flow of ethylene). The phasing stage can be initiated after or simultaneously with feeding/introducing the C 3+  olefin to the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3  using a any appropriate line  142 ,  191 ,  192 , and  193  for flow of ethylene). 
     The decrease in the reaction zone C 3+  olefin:ethylene weight ratio and/or the decrease of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone during the phasing stage is not limited to a particular technique and can occur via linear decrease (e.g., a constant increase over a given period of time), a step change decrease (e.g., decrease by changing a set value at set points of time during the period of time), or a combination thereof. During the phasing stage the decrease in the reaction zone C 3+  olefin:ethylene weight ratio and/or the decrease of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can be accomplished by increasing the ethylene flow rate and/or decreasing C 3+  olefin flowrate to the reaction zone until the desired reaction zone C 3+  olefin:ethylene weight ratio and/or C 3+  olefin:ethylene weight ratio is achieved. Alternatively, the decrease in the reaction zone C 3+  olefin:ethylene weight ratio and/or the decrease of the C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone can be accomplished by increasing the ethylene flow rate and decreasing C 3+  olefin flowrate to the reaction zone until the desired reaction zone C 3+  olefin:ethylene weight ratio and/or C 3+  olefin:ethylene weight ratio is achieved. 
     After ending the phasing stage, ethylene, the organic reaction medium, the catalyst system, and optionally hydrogen can be fed/introduced to the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ) to achieve the desired ethylene oligomerization operation and/or reaction zone conditions (e.g., ethylene oligomerization and/or reaction zone conditions to achieve steady state operation). In an aspect, it is contemplated that no significant amount of C 3+  olefin is fed/introduced to the reaction zone during steady state operation of the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ). Thus, no significant amount of C 3+  olefin is introduced to the reaction zone via a reaction zone inlet (e.g., any reaction zone inlet of  FIGS. 1-3 ) during steady state operation. As used herein no significant amount of C 3+  olefin is fed/introduced to the reaction zone during steady state operation of the reaction zone is defined as a C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone of less than 0.1:1, 0.08:1, 0.06:1, 0.04:1, 0.02:1, or 0.01:1. 
     During steady state operation, ethylene, the organic reaction medium, the catalyst system, and optionally, hydrogen can be periodically or continuously introduced to the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ). Moreover, in some embodiments, reaction zone effluent can be periodically or continuously removed from the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ). For example, reaction zone inlets (e.g., the reaction zone inlets of  FIGS. 1-3 ) can be configured to periodically or continuously introduce the catalyst system, ethylene, organic reaction medium, and optionally hydrogen to the reaction zone while a reaction zone outlet (e.g., the reaction zone outlets of  FIGS. 1-3 ) can be configured to periodically or continuously discharge or remove the reaction zone effluent from the reaction zone. In some embodiments, the desired ethylene oligomerization operation can include contacting ethylene with the organic reaction medium to form the feedstock mixture prior to ethylene contacting the catalyst system. Additionally, when ethylene is contacted with the organic reaction medium to form the feedstock mixture prior to ethylene contacting the catalyst system ethylene can be dispersed with the organic reaction medium prior to ethylene contacting the catalyst system. In an embodiment wherein the ethylene and the organic reaction medium are contacted, and/or the ethylene can be dispersed in the organic reaction medium prior to ethylene contacting the catalyst system in the reaction zone (e.g., reaction zone  110  of  FIGS. 1-3 ), the ethylene can contact the catalyst system in the reaction zone; or alternatively, ethylene can contact the catalyst system outside the reaction zone. 
     In an embodiment, any process, system, and/or reaction system described herein can further comprise preparing the catalyst system. In an embodiment, the catalyst system can be prepared by 1) contacting the chromium component (any described herein) and the aluminoxane compound (any described herein) to form a catalyst system mixture, and 2) aging the catalyst system mixture in the substantial absence of ethylene to form and aged catalyst system mixture. In an embodiment the catalyst system mixture can be aged for a period of time. Typically, the minimum aging time can be 5 seconds, 10 seconds, 30 seconds, 1 minute, 5 minutes, 10 minutes, or 20 minutes; additionally or alternatively, the maximum aging time can be 48 hours, 36 hours, 24 hours, 18 hours, 12 hours, 6 hours, 4 hours, or 2 hours. Generally, the aging time can be in a range from any minimum time disclosed herein to any maximum time disclosed herein. Accordingly, suitable non-limiting ranges for the aging time can include from 5 seconds to 48 hours, from 10 seconds to 36 hours, from 30 seconds to 24 hours, from 1 minute to 18 hours, from 5 minutes to 6 hours, from 10 minutes to 4 hours, or from 20 minutes to 2 hours. Other appropriate ranges for the aging time are readily apparent from this disclosure. In further embodiments, the catalyst system mixture can be aged at any suitable temperature, ranging from sub-ambient temperatures, to ambient temperature (approximately 25° C.), to elevated temperatures. While not limited thereto, the catalyst system mixture can be aged at a temperature in a range from 0° C. to 100° C., from 10° C. to 75° C., from 15° C. to 60° C., or from 20° C. to 40° C. In these and other embodiments, these temperature ranges also are meant to encompass circumstances where the catalyst system mixture can be aged at a series of different temperatures, instead of at a single fixed temperature, falling within the respective ranges. In a non-limiting embodiment, a substantial absence of ethylene can be a maximum molar ratio of ethylene to chromium component of 5:1, 4:1, 3:1, 2:1, 1:1, 0.5:1, 0.25:1, or 0.1:1. In some non-limiting embodiments, the substantial absence of ethylene can be a maximum ethylene partial pressure 10 psig (69 kPa), 5 psig (34 kPa), 4 psig (28 kPa), 3 psig (21 kPa), 2 psig (14 kPa), 1 psig (7 kPa), or 0.5 psig (3.4 kPa). In some embodiments, the catalyst system can be formed by contacting a diluent and/or a solvent with the chromium component (any described herein) and the aluminoxane (any described herein). In an embodiment, the diluent and/or solvent can be any organic reaction medium described herein. In embodiments where the catalyst system can be formed by contacting a diluent and/or a solvent with the chromium component (any described herein) and the aluminoxane, the chromium component to solvent and/or diluent weight ratio can range from 1:100 to 1:15,000, or 1:150 to 1:10,000. 
     While in one embodiment the catalyst system can be prepared prior to entering the reaction zone, the processes, system, and reaction systems described herein, the catalyst system also can be formed in-situ within the reaction zone. That is to say that all of the components of the catalyst system (e.g., the chromium component comprising a chromium compound, the heteroatomic ligand, and the aluminoxane; or alternatively, the chromium component comprising a heteroatomic ligand chromium compound complex, and the aluminoxane) do not contact each other until after they are introduced/fed into the reaction zone. In the in-situ catalyst system preparation embodiments of the processes, system, and reaction systems described herein, two or more components of the catalyst system can be separately introduced/fed to reaction zone (e.g., via two or more feed lines and reaction zone inlets). Generally, the two or more separately introduced/fed catalyst system components can be i) introduced/fed to the reaction zone separately from the other feeds to the reaction zone, ii) introduced/fed with other feeds to the reaction zone, or iii) some introduced/fed to the reaction zone separate from the other feeds to the reaction zone and some introduced/fed with other feeds to the reaction zone. For example, for a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane, the chromium component comprising the chromium compound and heteroatomic ligand can be introduced/fed to the reaction zone separately (either individually or in combination) from the other feeds to the reaction zone while the aluminoxane can be introduced/fed to the reaction zone with the organic reaction medium or introduced/fed separately from the feeds to the reaction zone; or alternatively, the chromium component comprising the chromium compound and the heteroatomic ligand can be introduced/fed to the reaction zone with a portion of the organic reaction medium (either separately or in combination) while the aluminoxane can be introduced/fed to the reaction zone with a different portion of the organic reaction medium or introduced/fed separately from the other feeds to the reaction zone. In another example, for a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane, the chromium component comprising the heteroatomic ligand chromium compound complex can be introduced/fed to the reaction zone separately from the other feeds to the reaction zone while the aluminoxane can be introduced/fed to the reaction zone with the organic reaction medium or introduced/fed separately from the feeds to the reaction zone; or alternatively, the chromium component comprising the heteroatomic ligand chromium compound complex can be introduced/fed to the reaction zone with a portion of the organic reaction medium while the aluminoxane can be introduced/fed to the reaction zone with a different portion of the organic reaction medium or introduced/fed separately from the other feeds to the reaction zone. These herein provided examples are non-limiting and are only meant to describe possible ways the catalyst system components can be separately introduced/fed to the reaction zone for the in-situ formation of the catalyst system within the reaction zone. Other ways of separately introducing/feeding two or more components of the catalyst system to the reaction zone are readily apparent to those having ordinary skill in the art. 
       FIG. 1  shows a process flow diagram of a reaction system  100  according to the present disclosure. The system  100  includes one or more of an ethylene source  140  in fluid communication with an ethylene feed line  142 ; a C 3+  olefin source  145  in communication with a C 3+  feed line  146 ; a catalyst system source  150  in fluid communication with a catalyst system feed line  152 ; an organic reaction medium source  160  in fluid communication with an organic reaction medium feed line  162 ; an optional scrub agent source  170  in communication with a scrub agent feed line  172 ; an optional hydrogen feed line  144  feeding to the ethylene feed line  142 ; an optional pump  180 ; a reaction zone  110  having a first reaction zone inlet  111 , a second reaction zone inlet  213 , a third reaction zone inlet  215 , a fourth reaction zone inlet  115 , and a reaction zone outlet  117  representing one or more reaction zone outlets; and a heat exchanger  120 . It is contemplated that the reaction system  100  of  FIG. 1  can include appropriate equipment (e.g., valves, control devices, sensors, electrical writing, insulation) which are not shown in  FIG. 1  yet can be included according to those skilled in the art with the aid of this disclosure. 
     The first reaction zone inlet  111  (representing one or more reaction zone inlets) can be configured to introduce a catalyst system (which can be optionally combined with C 3+  olefin for a period of time) as described herein to the reaction zone  110 , the second reaction zone inlet  213  (representing one or more reaction zone inlets) can be configured to introduce ethylene (which can be optionally combined with C 3+  olefin for a period of time) to the reaction zone  110 , the third reaction zone inlet  215  (representing one or more reaction zone inlets) can be configured to introduce organic reaction medium (which can be optionally combined with C 3+  olefin for a period of time) to the reaction zone  110 , and the reaction zone outlet  117  (representing one or more reaction zone outlets) can be configured to discharge or remove a reaction zone effluent comprising an ethylene oligomer product from the reaction zone  110  via line  118 . Valve  130  can be used in line  118  to control a flow of the reaction zone effluent in line  118  and/or to control a pressure of the reaction zone  110 . Reaction zone effluent in line  118  can then feed to equipment (not shown) for isolating various streams (e.g., the desired oligomer) from the reaction zone effluent. 
     The catalyst system can flow through catalyst system feed line  152  from the catalyst system source  150  to the first reaction zone inlet  111 , where the catalyst system can be fed to the reaction zone  110 . Although  FIG. 1  is described as flowing a pre-mixed or pre-prepared catalyst system to the reaction zone  110  via line  152 , an alternative aspect of the disclosed catalyst systems can be one where two or more of the components of the catalyst system can be separately introduced/fed to the reaction zone where the catalyst system in prepared in-situ within reaction zone  110  (as opposed to ex-situ mixing or preparation outside the reaction zone  110 ). That is, in an aspect of the disclosed reaction system, the catalyst system components can be introduced/fed separately to the reaction zone  110 . For example, for a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane, the chromium component and heteroatomic ligand can flow to the reaction zone  110  via line  152 , while the aluminoxane can flow to the reaction zone  110  via one or more of: line  142 ; line  162 ; line  172 ; lines  146 ,  147   a , and  142 ; lines  146 ,  147   b , and  162 ; lines  146  and  147   c ; and directly to the reaction zone  110  via another line and one of the reaction zone inlets  215 ,  215 , and  115  or another reaction zone inlet (not shown). For a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane, the chromium component can flow to the reaction zone  110  via line  152 , while the aluminoxane can flow to the reaction zone  110  via one or more of: line  142 ; line  162 ; line  172 ; lines  146 ,  147   a , and  142 ; lines  146 ,  147   b , and  162 ; lines  146  and  147   c ; and directly to the reaction zone  110  via another line and one of the reaction zone inlets  215 ,  215 , and  115  or another reaction zone inlet. The herein described examples are non-limiting and are only meant to describe possible ways the catalyst system components can be separately introduced/fed to the reaction zone  110  for the in-situ formation of the catalyst system within the reaction zone. Any description of line  152  in  FIG. 1  as containing the catalyst system herein can equally apply to aspects where only a part of the catalyst system is in line  152  while other parts are fed to the reaction zone  110  elsewhere in the system  100  and/or processes implemented therein. 
     The catalyst system feed line  152  can optionally include a solvent and/or diluent with the catalyst system. The solvent and/or diluent can be any organic reaction medium described herein. In an embodiments, the solvent and/or diluent can be the organic reaction medium utilized in the process, system, or reaction system. The catalyst system can be dispersed in the solvent and/or diluent in the catalyst system feed line  152 . For example, the catalyst system feed line  152  can include a mixing device (not shown), similar to mixing device  190  (described herein) discussed for  FIG. 2  or in a precontactor apparatus (not shown), which can be configured to disperse the catalyst system in the diluent prior to the catalyst system entering the reaction zone  110  via first reaction zone inlet  111 . When solvent and/or diluent and the catalyst system are present in the catalyst system feed line  152  of  FIG. 1 , the chromium:solvent and/or diluent mass ratio can be any disclosed herein. 
     Optionally, scrub agent (described herein) can flow in the scrub agent feed line  172 . In an embodiment some or all of the aluminoxane of the catalyst system can flow in the scrub agent feed line  172 . For example, all of the aluminoxane of the catalyst system can flow in scrub agent feed line  172  in the in-situ generation of the catalyst system; or alternatively, the aluminoxane can flow in both the catalyst system feed line  152  and the scrub agent feed line  172 . In an embodiment, the scrub agent may not be an aluminoxane of the catalyst system. 
     Organic reaction medium can flow in organic reaction medium feed line  162  from the organic reaction medium source  160  to the suction side  181  of pump  180 . 
     At least a portion of the organic reaction medium can be contacted with a scrub agent (e.g., an alkylaluminum compound, any described herein) prior to introduction to the reaction zone  110 .  FIG. 1  shows scrub agent can be added via feed line  172  to the organic reaction medium feed line  162  such that line  162  can contain both the scrub agent and the organic reaction medium. Alternatively, the scrub agent may not be combined with the organic reaction medium in the organic reaction medium feed line  162 . In a non-limiting embodiment where the catalyst system is formed in-situ within reaction zone  110 , an aluminoxane can be utilized as the scrub agent and can be all or a portion of the aluminoxane component of the catalyst system. Alternatively, the scrub agent is not combined with the organic reaction medium in the organic reaction medium. The scrub agent is independently disclosed herein and can be utilized to further described reaction system  100 . The scrub agent is independently disclosed herein and can be utilized to further described reaction system  100 . 
     In embodiments where the organic reaction medium and ethylene are contacted to form a feedstock mixture, at least a portion of the organic reaction medium can be contacted with the scrub agent (e.g., an alkylaluminum compound, any described herein) prior to contact of the portion of organic reaction medium with ethylene.  FIG. 1  shows the scrub agent can be added via line  172  to the organic reaction medium feed line  162 , before the organic reaction medium contacts ethylene via combination of the organic reaction medium feed line  162  with the ethylene feed line  142 . The scrub agent is independently disclosed herein and can be utilized to further describe reaction system  100 . 
     In  FIG. 1 , all of the organic reaction medium can be fed to the reaction zone via line  162 . However, as is discussed herein, it is contemplated that only a portion of the total amount of organic reaction medium which is used in the system  100  is in line  162  and optionally contacted with the scrub agent prior to introduction to the reaction zone  110 ; e.g., the other portions can be mixed with the catalyst system in catalyst system feed line  152 . 
     Ethylene flows in ethylene feed line  142  from the ethylene source  140  to the second reaction zone inlet  213 . 
     Hydrogen optionally can be used to control the selective ethylene oligomerization reaction. The hydrogen can be fed into the ethylene feed line  142  via hydrogen feed line  144 . The combination of hydrogen with ethylene in the ethylene feed line  144  can be upstream of valve  143  as shown in  FIG. 1 ; or alternatively, downstream of valve  143 . While the hydrogen feed line  144  in  FIG. 1  is shown as feeding to the ethylene feed line  142 , it is contemplated that the hydrogen feed line  144  can fluidly connect to any reaction zone inlet (e.g., reaction zone inlet  111 , reaction zone inlet  115 , reaction zone inlet  213 , or reaction zone inlet  215 ) directly or via another line (e.g., line  146 , line  147   a, b, c , or  d , line  152 , line  162 , or line  172 ). 
     The C 3+  olefin can be introduced, for a period of time, to reaction system  100  via one or more of lines  147   a - d  (the alternative nature being shown as dashed lines). For example, the C 3+  olefin, which can be introduced for a period of time, can flow from the C 3+  olefin source  145  via line  146  and one or more of: i) line  147   a  to combine with ethylene flowing in ethylene feed line  142 , ii) line  147   b  to combine with the organic reaction medium flowing in line  162 , iii)  147   c  to add the C 3+  olefin directly to the reaction zone  110 , and iv) line  147   d  to combine with the catalyst system flowing in line  152 . 
     When introducing the C 3+  olefin, which can be introduced for a period of time, via line  146  and line  147   a , the C 3+  olefin can combine with ethylene flowing in ethylene feed line  142 . The ethylene feed line  142  (comprising ethylene, the C 3+  olefin, and optionally hydrogen) can connect to the reaction zone  110  via the second reaction zone inlet  213 . In the aspect where the C 3+  olefin is introduced which can be introduced for a period of time via line  146  and line  147   a , the C 3+  olefin can flow via lines  146 ,  147   a , and  142 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   b , the C 3+  olefin can combine with the organic reaction medium (which can optionally previously combined with the scrub agent) flowing in the organic reaction medium feed line  162 . The organic reaction medium line  162  (comprising the organic reaction medium, the C 3+  olefin, and optionally scrub agent) can flow to the reaction zone  110  via the third reaction zone inlet  215 . In the aspect where the C 3+  olefin is introduced for a period of time via line  146  and line  147   b , the C 3+  olefin can flow via lines  146 ,  147   b , and  162  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   c , the C 3+  olefin can flow directly to the reaction zone  110  via the fourth reaction zone inlet  115  which can be configured to introduce the C 3+  olefin for a period of time to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   d , the C 3+  olefin can combine with the catalyst system flowing in catalyst system feed line  152 . In such an aspect, the catalyst system can flow for a period of time with the C 3+  olefin in line  152  to the reaction zone  110  via the first reaction zone inlet  111 . With respect to the timing of the flow of the C 3+  olefin relative to the flow of ethylene for a period of time, the flow of C 3+  olefin can commence before or simultaneously with the flow of ethylene regardless which of lines  147   a ,  147   b ,  147   c , and/or  147   d  the C3+ olefin flows. Alternatively, the flow of the C 3+  olefin can commence before the flow of ethylene (when the reaction zone  110  is empty, for example, during hard startup, or when the reaction zone  110  already contains material, for example, in a soft startup after temporary cessation of the flow of ethylene and/or catalyst system to the reaction zone  110  to address process or system issues), then be stopped temporarily, and then again commenced before or at the same time (simultaneously) as the flow of ethylene and/or catalyst system. With respect to the timing of the flow of the C 3+  olefin relative to the flow of catalyst system for a period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the catalyst system regardless of which lines  147   a ,  147   b ,  147   c , and/or  147   d  the C 3+  olefin flows. With respect to the timing of the flow of the C 3+  olefin relative to the flow of organic reaction medium for a period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the organic reaction medium regardless of which lines  147   a ,  147   b ,  147   c , and/or  147   d  the C 3+  olefin flows. With respect to the timing of the flow of the C 3+  olefin relative to the flow of scrub agent for a period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the scrub agent regardless of which lines  147   a ,  147   b ,  147   c , and/or  147   d  the C 3+  olefin flows. 
     It is noted that in the system  100  of  FIG. 1 , ethylene can be fed to the reaction zone  110  separately with respect to the catalyst system and with respect to the organic reaction medium. That is, ethylene can be fed to the reaction zone  110  via line  142  and via second reaction zone inlet  213 ; while, the catalyst system can be fed to the reaction zone  110  via line  152  and via first reaction zone inlet  111 , and while the organic reaction medium can be fed to the reaction zone  110  via line  162  and via the third reaction zone inlet  215 . 
     The separately fed ethylene can be substantially free of the catalyst system or at least a chromium component of the catalyst system. By “substantially free” it is meant that the ethylene has equal to or less than 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 wt. % of the catalyst system present based on the total weight of the catalyst system entering the reaction zone  110 . 
       FIG. 2  shows a process flow diagram of a reaction system  200  according to the present disclosure. The system  200  includes one or more of an ethylene source  140  in fluid communication with an ethylene feed line  142 ; a C 3+  olefin source  145  in communication with a C 3+  feed line  146 ; a catalyst system source  150  in fluid communication with a catalyst system feed line  152 ; an organic reaction medium source  160  in fluid communication with an organic reaction medium feed line  162 ; an optional scrub agent source  170  in communication with a scrub agent feed line  172 ; an optional hydrogen feed line  144  feeding to the ethylene feed line  142 ; an optional pump  180 ; an optional mixing device  190 ; a reaction zone  110  having a first reaction zone inlet  111 , a second reaction zone inlet  113 , an optional third reaction zone inlet  115 , and a reaction zone outlet  117  representing one or more reaction zone outlets; and a heat exchanger  120 . It is contemplated that the reaction system  200  of  FIG. 2  can include appropriate equipment (e.g., valves, control devices, sensors, electrical writing, insulation) which are not shown in  FIG. 2  yet can be included according to those skilled in the art with the aid of this disclosure. 
     The first reaction zone inlet  111  (representing one or more reaction zone inlets) can be configured to introduce a catalyst system (which can be optionally combined with C 3+  olefin for a period of time) as described herein to the reaction zone  110 , the second reaction zone inlet  113  (representing one or more reaction zone inlets) can be configured to introduce a feedstock mixture (which can be optionally combined with C 3+  olefin for a period of time) to the reaction zone  110 , and the reaction zone outlet  117  (representing one or more reaction zone outlets) can be configured to discharge or remove a reaction zone effluent comprising an ethylene oligomer product from the reaction zone  110  via line  118 . Valve  130  can be used in line  118  to control a flow of the reaction zone effluent in line  118  and/or to control a pressure of the reaction zone  110 . Reaction zone effluent in line  118  can then feed to equipment (not shown) for isolating various streams (e.g., the desired oligomer) from the reaction zone effluent. 
     The catalyst system can flow through catalyst system feed line  152  from the catalyst system source  150  to the first reaction zone inlet  111 , where the catalyst system can be fed to the reaction zone  110 . Although  FIG. 2  is described as flowing a pre-mixed or pre-prepared catalyst system to the reaction zone  110  via line  152 , an alternative aspect of the disclosed catalyst systems can be one where two or more of the components of the catalyst system can be separately introduced/fed to the reaction zone where the catalyst system in prepared in-situ within of the reaction zone  110  (as opposed to ex-situ mixing or preparation outside the reaction zone  110 ). That is, in an aspect of the disclosed reaction system, the catalyst system components can be introduced/fed separately to the reaction zone  110 . For example, for a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane, the chromium component and heteroatomic ligand can flow to the reaction zone  110  via line  152 , while the aluminoxane can flow to the reaction zone  110  via one or more of: lines  172 ,  162 ,  191 , and  192 ; lines  162 ,  191 , and  192 ; lines  142 ,  191 , and  192 ; lines  191  and  192 ; line  192 ; and directly to the reaction zone  110  via another line and/or another reaction zone inlet (not shown). For a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane, the chromium component can flow to the reaction zone  110  via line  152 , while the aluminoxane can flow to the reaction zone  110  via one or more of: lines  172 ,  162 ,  191 , and  192 ; lines  162 ,  191 , and  192 ; lines  142 ,  191 , and  192 ; lines  191  and  192 ; line  192 ; and directly to the reaction zone  110  via another line and/or another reaction zone inlet. The herein described examples are non-limiting and are only meant to describe possible ways the catalyst system components can be separately introduced/fed to the reaction zone  110  for the in-situ formation of the catalyst system with the reaction zone. Any description of line  152  in  FIG. 2  as containing the catalyst system herein can equally apply to aspects where only a part of the catalyst system is in line  152  while other parts are fed to the reaction zone  110  elsewhere in the system  200  and/or processes implemented therein. 
     The catalyst system feed line  152  can optionally include a solvent and/or diluent with the catalyst system. The solvent and/or diluent can be any organic reaction medium described herein. In some embodiments, the solvent and/or diluent can be the organic reaction medium used in the feedstock mixture. The catalyst system can be dispersed in the solvent and/or diluent in the catalyst system feed line  152 . For example, the catalyst system feed line  152  can include a mixing device, similar to mixing device  190  (described herein) or in a precontactor apparatus (not shown), which can be configured to disperse the catalyst system in the diluent prior to the catalyst system entering the reaction zone  110  via first reaction zone inlet  111 . When solvent and/or diluent and the catalyst system are present in the catalyst system feed line  152  of  FIG. 2 , the chromium:solvent and/or diluent mass ratio can be any disclosed herein. 
     Optionally, scrub agent (described herein) can flow in the scrub agent feed line  172 . In an embodiment some or all of the aluminoxane of the catalyst system can flow in the scrub agent feed line  172 . For example, all of the aluminoxane of the catalyst system can flow in scrub agent feed line  172  in the in-situ generation of the catalyst system; or alternatively, the aluminoxane can flow in both the catalyst system feed line  152  and the scrub agent feed line  172 . In an embodiment, the scrub agent may not be an aluminoxane of the catalyst system. 
     In embodiments where the organic reaction medium and ethylene are contacted to form a feedstock mixture, at least a portion of the organic reaction medium can be contacted with the scrub agent (e.g., an alkylaluminum compound, any described herein) prior to contact of the portion of organic reaction medium with ethylene.  FIG. 2  shows the scrub agent can be added via line  172  to the organic reaction medium feed line  162 , before the organic reaction medium contacts ethylene via combination of the organic reaction medium feed line  162  with the ethylene feed line  142 . The scrub agent is independently disclosed herein and can be utilized to further describe reaction system  200 . 
     Organic reaction medium (optionally combined with the catalyst system) can flow in organic reaction medium feed line  162  from the organic reaction medium source  160 , through the pump  180 , and to the point where the ethylene feed line  142  and the organic reaction medium feed line  162  join. 
     At least a portion of the organic reaction medium can be contacted with a scrub agent (e.g., an alkylaluminum compound, any described herein) prior to introduction to the reaction zone  110 .  FIG. 2  shows scrub agent can be added via feed line  172  to the organic reaction medium feed line  162  such that line  162  can contain both the scrub agent and the organic reaction medium. Alternatively, the scrub agent may not be combined with the organic reaction medium in the organic reaction medium feed line  162 . In a non-limiting embodiment where the catalyst system is formed in-situ within reaction zone  110 , an aluminoxane can be utilized as the scrub agent and all or a portion of the aluminoxane component of the catalyst system. The scrub agent is independently disclosed herein and can be utilized to further described reaction system  200 . 
     In embodiments where the organic reaction medium and ethylene are contacted to form a feedstock mixture, at least a portion of the organic reaction medium can be contacted with the scrub agent (e.g., an alkylaluminum compound) prior to contact of the portion of organic reaction medium with ethylene.  FIG. 2  shows the scrub agent can be added via line  172  to the organic reaction medium feed line  162 , before the organic reaction medium contacts ethylene via combination of the organic reaction medium feed line  162  with the ethylene feed line  142 . Alternatively, the scrub agent may not be combined with the organic reaction medium in the organic reaction medium feed line  162 . The scrub agent is independently disclosed herein and can be utilized to further described reaction system  200 . 
     In  FIG. 2 , all of the organic reaction medium can be fed to the reaction zone via line  162  However, as is discussed herein, it is contemplated that only a portion of the total amount of organic reaction medium which is used in the system  200  can be in line  162  and optionally contacted with the scrub agent prior to introduction to the reaction zone  110 ; e.g., the other portions can be mixed with the catalyst system in catalyst system feed line  152  and/or can be included in a bypass line which feeds directly to the reaction zone  110 . Alternatively, the scrub agent may not be combined with the organic reaction medium, and the organic reaction medium feed line  162  can flow directly to the suction side  181  of pump  180 . 
     Ethylene (which can be optionally combined with C 3+  olefin for a period of time and/or optionally combined with hydrogen) can flow in ethylene feed line  142  from the ethylene source  140  and can combine with organic reaction medium (which can be optionally previously combined with scrub agent and/or C 3+  olefin) flowing in line  162  on the head side  182  of the pump  180 . Alternatively, ethylene can be combined with the organic reaction medium flowing in line  162  on the suction side  181  of the pump  180 . 
     Combination of the ethylene in line  142  with the organic reaction medium in line  162  can yield a feedstock mixture in feedstock mixture feed line  191 . The feedstock mixture can flow through an optional mixing device  190  where ethylene and the organic reaction medium (which can be optionally previously combined with scrub agent and/or C 3+  olefin) can be dispersed, and subsequently can flow via dispersed feedstock mixture feed line  192  as a dispersed feedstock mixture to the second reaction zone inlet  113 . 
     Hydrogen optionally can be used to control oligomerization reactions. The optional hydrogen can be fed into the ethylene feed line  142  of reaction system  200  via hydrogen feed line  144 . The combination of hydrogen with ethylene in the ethylene feed line  144  can be upstream of valve  143  as shown in  FIG. 2 ; or alternatively, downstream of valve  143 . While the hydrogen feed line  144  in  FIG. 2  is shown as feeding to the ethylene feed line  142 , it is contemplated that the hydrogen feed line  144  can fluidly connect to any reaction zone inlet (e.g., reaction zone inlet  111 , reaction zone inlet  113 , or reaction zone inlet  115 ) directly or via another line (e.g., line  146 , line  147   a, b, c, d, e , or  f , line  152 , line  162 , line  172 , line  191 , or line  192 ). 
     The C 3+  olefin can be introduced, for a period of time, to reaction system  200  via any one or more of lines  147   a - f  (the alternative nature being shown as dashed lines). For example, the C 3+  olefin, which can be introduced/fed for a period of time to the reaction zone, can flow from the C 3+  olefin source  145  via line  146  and: i) via line  147   a  to combine with ethylene flowing in ethylene feed line  142 , before ethylene joins with organic reaction medium flowing in feed line  162  to form the feedstock mixture in feedstock mixture line  191 , ii) via line  147   b  to combine with the organic reaction medium flowing in line  162 , before the organic reaction medium joins with ethylene to form the feedstock mixture in line  191 , iii) via line  147   c  to add the C 3+  olefin directly to the reaction zone  110 , iv) via line  147   d  to combine with the catalyst system flowing in line  152 ; v) via line  147   e  to combine with the feedstock mixture flowing in line  191 , vi) via  147   f  to combine with the dispersed feedstock mixture flowing in line  192 , or vii) any combination of i)-vi). 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   a , the C 3+  olefin can combine with ethylene flowing in ethylene feed line  142 . The ethylene feed line  142  (comprising ethylene, the C 3+  olefin, and optionally hydrogen) can join with the organic reaction medium (which can be optionally previously combined with scrub agent) line  162  to form the feedstock mixture line  191 . That is, in an aspect where the C 3+  olefin flows in line  147   a , the feedstock mixture includes ethylene, organic reaction medium (which can be optionally previously combined with scrub agent), and the C 3+  olefin (and optionally hydrogen). The feedstock mixture can flow into the optional mixing device  190  where ethylene, the organic reaction medium (which can be optionally previously combined with scrub agent), the C 3+  olefin, and optionally hydrogen are dispersed in the feedstock mixture. The dispersed components in line  191  can flow from the optional mixing device  190  in the dispersed feedstock mixture line  192  to the reaction zone  110  via the second reaction zone inlet  113 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   a , the C 3+  olefin can flow via lines  146 ,  147   a ,  142 ,  191 , and  192  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   b , the C 3+  olefin can combine with the organic reaction medium (which can be optionally previously combined with scrub agent) flowing in the organic reaction medium feed line  162 . The organic reaction medium line  162  (comprising the organic reaction medium, the C 3+  olefin, and optionally scrub agent) can join with the ethylene feed line  142  (comprising ethylene and optionally hydrogen) to form the feedstock mixture line  191 . That is, in an aspect where the C 3+  olefin flows in line  147   b , the feedstock mixture in line  191  includes ethylene, organic reaction medium, and the C 3+  olefin (and optionally scrub agent and/or hydrogen). The feedstock mixture can flow into the optional mixing device  190  where ethylene, the organic reaction medium, and the C 3+  olefin (and optionally the scrub agent and/or hydrogen) can be dispersed in the feedstock mixture. The dispersed feedstock mixture can flow from the optional mixing device  190  in the dispersed feedstock mixture line  192  to the reaction zone  110  via the second reaction zone inlet  113 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   b , the C 3+  olefin can flow via lines  146 ,  147   b ,  162 ,  191 , and  192  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   c , the C 3+  olefin flows directly to the reaction zone  110  via the reaction zone inlet  115  which is configured to introduce the C 3+  olefin to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   d , the C 3+  olefin can combine with the catalyst system flowing in catalyst system feed line  152 . In such an aspect, the catalyst system can flow for a period of time with the C 3+  olefin in line  152  to the reaction zone  110  via the first reaction zone inlet  111 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   d , the C 3+  olefin can flow via lines  146 ,  147   d , and  152  to the reaction zone  110  via the first reaction zone inlet  111 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   e , the C 3+  olefin can combine with the feedstock mixture in line  191 . In such an aspect, the feedstock mixture entering the optional mixing device  190  can contain the C 3+  olefin in addition to ethylene, and the organic reaction medium (and optionally the scrub agent and/or hydrogen). In the mixing device  190 , ethylene, the organic reaction medium, and the C 3+  olefin (and optionally the scrub agent and/or hydrogen) can be dispersed in the feedstock mixture. The dispersed feedstock mixture flows from the optional mixing device  190  in dispersed feedstock mixture line  192  to the reaction zone  110  via the second reaction zone inlet  113 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   e , the C 3+  olefin can flow for a period of time via lines  146 ,  147   e ,  191 , and  192  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   f , the C 3+  olefin can combine with the dispersed feedstock mixture in line  192 . In such an aspect, the feedstock mixture entering the mixing device  190  can comprise ethylene and organic reaction medium (and optionally scrub agent and/or hydrogen); the dispersed feedstock mixture exiting the optional mixing device  190  can comprise ethylene and the organic reaction medium (optionally scrub agent and/or hydrogen) dispersed in the feedstock mixture; and after line  147   c  containing the C 3+  olefin can combine with line  192 , the dispersed feedstock mixture additionally can comprise the C 3+  olefin. In certain aspects, the C 3+  olefin may or may not be dispersed in the dispersed feedstock mixture contained in line  192 . The dispersed feedstock mixture additionally containing the C 3+  olefin can flow to the reaction zone  110  via the second reaction zone inlet  113 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   f , the C 3+  olefin can flow via lines  146 ,  147   f , and  192  to the reaction zone  110 . 
     With respect to the timing of the flow of the C 3+  olefin relative to the flow of ethylene for a period of time, the flow of C 3+  olefin can commence before or simultaneously with the flow of ethylene regardless which of lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e , and/or  147   f  the C 3+  olefin flows. Alternatively, the flow of the C 3+  olefin can commence before the flow of ethylene (when the reaction zone  110  is empty, for example, during hard startup, or when the reaction zone  110  already contains material, for example, in a soft startup after temporary cessation of the flow of ethylene and/or catalyst system to the reaction zone  110  to address process or system issues), then be stopped temporarily, and then again commenced before or at the same time (simultaneously) as the flow of ethylene and/or catalyst system. With respect to the timing of the flow of the C 3+  olefin relative to the flow of catalyst system for a period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the catalyst system regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e , and/or  147   f  the C 3+  olefin flows. With respect to the timing of the flow of the C 3+  olefin relative to the flow of organic reaction medium for a period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the organic reaction medium regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e , and/or  147   f  the C 3+  olefin flows. With respect to the timing of the flow of the C 3+  olefin relative to the flow of scrub agent for the period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the scrub agent regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e , and/or  147   f  the C 3+  olefin flows. 
     It is noted that in the system  200  of  FIG. 2 , the feedstock mixture comprising ethylene and at least a portion of the organic reaction medium (in the case of  FIG. 2 , all of the organic reaction medium used in system  200 ) can be fed to the reaction zone  110  separately with respect to the catalyst system. That is, the feedstock mixture is fed to the reaction zone  110  via lines  191  and  192  and via second reaction zone inlet  113 ; while, the catalyst system can be fed to the reaction zone  110  via line  152  and via first reaction zone inlet  111 . 
     The separately fed feedstock mixture in any of lines  191  and  192  is substantially free of the catalyst system or at least a chromium component of the catalyst system. By “substantially free” it is meant that the feedstock mixture has equal to or less than 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 wt. % of the catalyst system present based on weight of the feedstock mixture entering the reaction zone  110 . 
       FIG. 3  shows a process flow diagram of another reaction system  300  according to the present disclosure. The system  300  includes one or more of an ethylene source  140  in fluid communication with an ethylene feed line  142 ; a catalyst system source  150  in fluid communication with a catalyst system feed line  152 ; a C 3+  olefin source  145  in communication with a C 3+  feed line  146 ; an organic reaction medium source  160  in fluid communication with an organic reaction medium feed line  162 ; an optional scrub agent source  170  in communication with a scrub agent feed line  172 ; an optional hydrogen feed line  144  feeding to the ethylene feed line  142 ; an optional pump  180 ; an optional mixing device  190 ; a reaction zone  110  having a reaction zone inlet  119 , an optional reaction zone inlet  115  for C 3+  olefin, and a reaction zone outlet  117  representing one or more reaction zone outlets; and a heat exchanger  120 . It is contemplated that the reaction system  300  of  FIG. 3  can include appropriate equipment (e.g., valves, control devices, sensors, electrical writing, insulation) which are not shown in  FIG. 3  yet would be included according to those skilled in the art with the aid of this disclosure. 
     The reaction zone inlet  119  (representing one or more reaction zone inlets) can be configured to introduce the catalyst system and the feedstock mixture to the reaction zone  110 , and the reaction zone outlet  117  (representing one or more reaction zone outlets) can be configured to discharge a reaction zone effluent comprising an ethylene oligomer product from the reaction zone  110  via line  118 . Valve  130  can be used in line  118  to control a flow of the reaction zone effluent in line  118  and/or to control a pressure of the reaction zone  110 . Reaction zone effluent in line  118  can then feed to equipment (not shown) for isolating various streams (e.g., the desired oligomer) from the reaction zone effluent. 
     The catalyst system can flow through catalyst system feed line  152  from the catalyst system source  150  to combine with an optionally dispersed feedstock mixture in line  192  (containing the ethylene, organic reaction medium, the catalyst system, optionally hydrogen, and optionally the C 3+  olefin for a period of time). Joining line  152  and line  192  yields combined feed line  193 , which in  FIG. 3 , can feed to the reaction zone  110  via reaction zone inlet  119 . Although  FIG. 3  is described as flowing a pre-mixed or pre-prepared catalyst system to the reaction zone  110  via lines  152  and  193 , an alternative aspect of the disclosed catalyst systems can be one where two of more of the components of the catalyst system can be separately introduce/fed to the reaction zone where the catalyst system is prepared in-situ within reaction zone  110  (as opposed to ex-situ mixing or preparation outside the reaction zone  110 ). That is, in an aspect of the disclosed reaction system, the catalyst system components can be introduced/fed separately to the reaction zone  110  or enter the system  300  at different points. For example, for a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane, the chromium component and heteroatomic ligand can flow to the reaction zone  110  via lines  152  and  193 , while the aluminoxane can flow to the reaction zone  110  via one or more of: lines  172 ,  162 ,  191 ,  192 , and  193 ; lines  162 ,  191 ,  192 , and  193 ; lines  142 ,  191 ,  192 , and  193 ; lines  191 ,  192 , and  193 ; lines  192  and  193 ; line  193 ; and directly to the reaction zone  110  via another line and/or another reaction zone inlet (not shown). For a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane, the chromium component can flow to the reaction zone  110  via line  152 , while the aluminoxane can flow to the reaction zone  110  via one or more of: lines  172 ,  162 ,  191 ,  192 , and  193 ; lines  162 ,  191 ,  192 , and  193 ; lines  142 ,  191 ,  192 , and  193 ; lines  191 ,  192 , and  193 ; lines  192  and  193 ; line  193 ; and directly to the reaction zone  110  via another line and/or another reaction zone inlet. The herein described examples are non-limiting and are only meant to describe possible ways the catalyst system can be separately introduced/fed to the reaction zone  110  for the in-situ formation of the catalyst system within the reaction zone. Any description of line  152  in  FIG. 3  as containing the catalyst system herein can equally apply to aspects where only a part of the catalyst system is in line  152  while other parts are fed to the reaction zone  110  elsewhere in the system  300  and/or processes implemented therein. 
     Alternatively (not shown), the catalyst system feed line  152  can combine with the feedstock mixture in line  191 , and the feedstock mixture feed line  191  (containing the ethylene, organic reaction medium, the catalyst system, optionally hydrogen, and optionally for a period of time the C 3+  olefin) can flow directly to the reaction zone  110  via reaction zone inlet  119  or can flow through mixing device  190  to yield a dispersed mixture (containing dispersed feedstock mixture, including ethylene, the organic reaction medium, the catalyst system, optionally hydrogen, and optionally for a period of time the C 3+  olefin) which subsequently flows to the reaction zone  110  via line  192  and reaction zone inlet  119 . 
     Alternatively (not shown), the catalyst system feed line  152  can combine with the organic reaction medium feed line  162 . In such an aspect, the organic reaction medium feed line  162  (containing the organic reaction medium and catalyst system) can join with the ethylene feed line  142  to form the feedstock mixture feed line  191  comprising ethylene, organic reaction medium, catalyst system, optionally hydrogen, and optionally for a period of time the C 3+  olefin. Line  191  which additionally includes the catalyst system can flow directly to the reaction zone  110  via reaction zone inlet  119  or can flow through mixing device  190  to yield a dispersed feedstock mixture (containing ethylene, organic reaction medium, the catalyst system, optionally hydrogen, and optionally for a period of time the C 3+  olefin) which subsequently flows to the reaction zone  110  via line  192  and reaction zone inlet  119 . 
     In any of the above-described alternative catalyst system injection aspects, the C 3+  olefin for a period of time can combine with the catalyst system feed line  152  prior to the catalyst system feed line  152  joining with any of line  192  (e.g., via line  147   d  shown  FIG. 3 ), line  191 , line  162 , or line  142 . 
     The catalyst system feed line  152  can optionally include a solvent and/or diluent along with the catalyst system. The solvent and/or diluent can be any organic reaction medium described herein. In an embodiment, the solvent and/or diluent can be the organic reaction medium utilized in the process. The catalyst system can be dispersed in the solvent and/or diluent in the catalyst system feed line  152 . For example, the catalyst system feed line  152  can include a mixing device (not shown), similar to mixing device  190  or in a precontactor apparatus (not shown), which is configured to disperse the catalyst system in the solvent and/or diluent prior to the catalyst system combining with the dispersed ethylene feed stock mixture in line  192 . When the solvent and/or diluent and the catalyst system are present in the catalyst system feed line  152  in  FIG. 3 , the chromium:diluent mass ratio can be any disclosed herein. 
     Organic reaction medium (optionally combined with the catalyst system) can flow in organic reaction medium feed line  162  from the organic reaction medium source  160 , through the pump  180 , and to the point where the ethylene feed line  142  and the organic reaction medium feed line  162  join. 
     Similar to the system  200  of  FIG. 2 , at least a portion of the organic reaction medium in the system  300  of  FIG. 3  can be contacted with a scrub agent (e.g., an alkylaluminum compound, any described herein) prior to introduction of the portion of the organic reaction medium to the reaction zone  110 .  FIG. 3  shows scrub agent can be added via feed line  172  to the organic reaction medium feed line  162  such that the organic reaction medium feed line  162  can contain both the organic reaction medium and the scrub agent. Alternatively, the scrub agent may not be combined with the organic reaction medium in the organic reaction medium feed line  162 . The scrub agent is independently disclosed herein and can be utilized to further described reaction system  300 . 
     Likewise, similar to the system  200  of  FIG. 2 , at least a portion of the organic reaction medium in the system  300  of  FIG. 3  can be contacted with the scrub agent (e.g., an alkylaluminum compound) prior to contact of the portion of organic reaction medium with ethylene.  FIG. 3  shows the co-catalyst can be added via line  172  to the organic reaction medium feed line  162 , before the organic reaction medium contacts ethylene via combination of the organic reaction medium feed line  162  with the ethylene feed line  142 . Alternatively, the scrub agent may not be combined with the organic reaction medium in the organic reaction medium feed line  162 . The scrub agent is independently disclosed herein and can be utilized to further described reaction system  300 . 
     In  FIG. 3 , all of the organic reaction medium can be fed to the reaction zone via line  162 . However, as is discussed herein, it is contemplated that only a portion of the total amount of organic reaction medium which is used in the system  300  is in line  162  and optionally contacted with the scrub agent prior to introduction/feeding to reaction zone  110 : e.g., the other portions can be mixed with the catalyst system in catalyst system feed line  152  and/or can be included in a bypass line which can feed directly to the reaction zone  110 . Alternatively, the scrub agent may not be combined with the organic reaction medium, and the organic reaction medium feed line  162  can flow directly to the suction side  181  of pump  180 . 
     Ethylene (which can be optionally combined with the C 3+  olefin for a period of time, and/or optionally hydrogen and/or the catalyst system) can flow in ethylene feed line  142  from the ethylene source  140  and can combine with organic reaction medium (which is optionally previously combined with scrub agent, C 3+  olefin, and/or catalyst system) flowing in line  162  on the head side  182  of the pump  180 . Alternatively, ethylene can be combined with the organic reaction medium flowing in line  162  on the suction side  181  of the pump  180 . 
     Combination of the ethylene in line  142  with the organic reaction medium in line  162  yields a feedstock mixture in feedstock mixture line  191 . The feedstock mixture flows through an optional mixing device  190  where ethylene and the organic reaction medium (which can be optionally previously combined with scrub agent and/or C 3+  olefin) can be dispersed, and subsequently flow as a dispersed feedstock mixture in dispersed feedstock mixture line  192 . 
     The feedstock mixture can be contacted with the catalyst system prior to introduction of the feedstock mixture into the reaction zone  110 . In  FIG. 3 , the feedstock mixture in the form of dispersed feedstock mixture in line  192  can combine with the catalyst system in line  152  to form a combined feed line  193  which can flow to the reaction zone inlet  119  and feeds to the reaction zone  110 . Alternatively, the feedstock mixture can be contacted with the catalyst system in line  152  via combination with line  191  and before the feedstock mixture enters the optional mixing device  190 . 
     Hydrogen optionally can be used to control oligomerization reactions. The optional hydrogen can be fed into the ethylene feed line  142  of reaction system  300  via hydrogen feed line  144 . The combination of hydrogen with ethylene in the ethylene feed line  144  can be upstream of valve  143  as shown in  FIG. 3 ; or alternatively, downstream of valve  143 . While the hydrogen feed line  144  in  FIG. 3  is shown as feeding to the ethylene feed line  142 , it is contemplated that the hydrogen feed line  144  can fluidly connect to any reaction zone inlet (e.g., reaction zone inlet  115  or reaction zone inlet  119 ) directly or via another line (e.g., line  146 , line  147   a, b, c, d, e, f , or  g , line  152 , line  162 , line  172 , line  191 , line  192 , or line  193 ). 
     The C 3+  olefin can be introduced for a period of time to reaction system  300  via any one or more of lines  147   a - g  (the alternative nature being shown as dashed lines in  FIG. 3 ). For example, the C 3+  olefin, which can be introduced/fed for a period of time to the reaction zone, can flow from the C 3+  olefin source  145  via line  146  and: i) via line  147   a  to combine with ethylene flowing in feed line  142 , before ethylene joins with organic reaction medium flowing in feed line  162  to form the feedstock mixture in feedstock mixture line  191 , ii) via line  147   b  to combine with the organic reaction medium flowing in line  162 , before the organic reaction medium joins with ethylene to form the feedstock mixture in line  191 , iii) via line  147   c  to add the C 3+  olefin directly to the reaction zone  110  via optional reaction zone inlet  115 , iv) via line  147   d  to combine with the catalyst system flowing in line  152 ; v) via line  147   e  to combine with the feedstock mixture flowing in line  191 , vi) via line  147   f  to combine with the dispersed feedstock mixture flowing in line  192 , vii) via line  147   g  to combine with the components of the combined feedstock mixture  193  before entry into the reaction zone  110  via reaction zone inlet  119 , or viii) any combination of i)-vii). 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   a , the C 3+  olefin can combine with ethylene flowing in ethylene feed line  142 . The ethylene feed line  142  (comprising ethylene, the C 3+  olefin, optionally hydrogen, and optionally catalyst system) can join with the organic reaction medium (which can be optionally previously combined with scrub agent) line  162  to form the feedstock mixture line  191 . That is, in an aspect where the C 3+  olefin flows in line  147   a , the feedstock mixture includes ethylene, organic reaction medium (which can be optionally previously combined with scrub agent), and the C 3+  olefin (and optionally hydrogen, and optionally the catalyst system). The feedstock mixture feed line  191  can flow into the mixing device  190  where the components in line  191  are dispersed. The dispersed components (e.g., the dispersed feedstock mixture) can flow from the optional mixing device  190  in the dispersed line  192 . In aspects where the catalyst system has not previously been joined to a line upstream of the reaction zone inlet  119 , the components in dispersed line  192  can join with the catalyst system feed line  152  to form the combined feed line  193  which contains the dispersed components of line  191  and the catalyst system. Line  193  subsequently can flow to the reaction zone  110  via the reaction zone inlet  119 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   a , the C 3+  olefin can flow via lines  146 ,  147   a ,  142 ,  191 ,  192 , and  193  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   b , the C 3+  olefin can combine with the organic reaction medium (which can be optionally previously combined with scrub agent) flowing in the organic reaction medium feed line  162 . The organic reaction medium line  162  (comprising the organic reaction medium, the C 3+  olefin, and optionally catalyst system and/or optionally scrub agent) can join with the ethylene feed line  142  (comprising ethylene and optionally hydrogen) to form the feedstock mixture line  191 . That is, in an aspect where the C 3+  olefin flows in line  147   b , the feedstock mixture in line  191  includes ethylene, organic reaction medium, and the C 3+  olefin (optionally scrub agent, optionally hydrogen, and/or optionally catalyst system). The feedstock mixture feed line  191  can flow into the optional mixing device  190  where the components in line  191  can be dispersed. The dispersed components (e.g., the dispersed feedstock mixture) can flow from the optional mixing device  190  in the dispersed line  192 . In aspects where the catalyst system has not previously been joined to a line upstream of the reaction zone inlet  119 , the components in dispersed line  192  can join with the catalyst system feed line  152  to form the combined feed line  193  which contains the dispersed components of line  191  and the catalyst system. Line  193  subsequently can flow to the reaction zone  110  via the reaction zone inlet  119 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   b , the C 3+  olefin can flow via lines  146 ,  147   b ,  162 ,  191 ,  192 , and  193  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   c , the C 3+  olefin can flow directly to the reaction zone  110  via the reaction zone inlet  115  which is configured to introduce the C 3+  olefin to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   d , the C 3+  olefin can combine with the catalyst system flowing in catalyst system feed line  152 . In such an aspect, the catalyst system can flow for a period of time with the C 3+  olefin in line  152  to join with the feedstock mixture outside the reaction zone  110 . In  FIG. 3 , line  152  combines with the dispersed feedstock mixture in line  192  to form the combined feed stream  193 , which flows to the reaction zone  110  via the reaction zone inlet  119 . In the aspect where the C3+ olefin is introduced via line  146  and line  147   d , the C 3+  olefin can flow via lines  146 ,  147   d ,  152 , and  193  to the reaction zone  110  via the reaction zone inlet  119 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   e , the C 3+  olefin can combine with the feedstock mixture in line  191 . The feedstock mixture feed line  191  can flow into the optional mixing device  190  where the components (including C 3+  olefin) in line  191  can be dispersed. The dispersed components (e.g., the dispersed feedstock mixture) can flow from the optional mixing device  190  in dispersed line  192 . In aspects where the catalyst system has not previously been joined to a line upstream of the reaction zone inlet  119 , the components in dispersed line  192  can join with the catalyst system feed line  152  to form the combined feed line  193  which contains the dispersed components of line  191  and the catalyst system. Line  193  subsequently can flow to the reaction zone  110  via the reaction zone inlet  119 . In the aspect where the C 3+  olefin can be introduced/fed for a period of time via line  146  and line  147   e , the C 3+  olefin can flow via lines  146 ,  147   e ,  191 ,  192 , and  193  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   f , the C 3+  olefin can combine with the dispersed feedstock mixture in line  192 . In such an aspect, the feedstock mixture entering the mixing device  190  can comprise ethylene and organic reaction medium (and optionally scrub agent, hydrogen, and/or catalyst system. The dispersed components (e.g., the dispersed feedstock mixture) can flow from the optional mixing device  190  in dispersed line  192 . Line  147   f  containing the C 3+  olefin can combine with dispersed line  192 . In aspects where the catalyst system has not previously been joined to a line upstream of the reaction zone inlet  119 , the components (including the C 3+  olefin) in dispersed line  192  can join with the catalyst system feed line  152  to form the combined feed line  193  which can contain the components of line  192  (e.g., the dispersed feedstock mixture and C 3+  olefin) and the catalyst system. Line  193  subsequently can flow to the reaction zone  110  via the reaction zone inlet  119 . In the aspect where the C 3+  olefin is introduced via line  146  and line  147   f , the C 3+  olefin can flow via lines  146 ,  147   f ,  192 , and  193  to the reaction zone  110 . 
     When introducing the C 3+  olefin for a period of time via line  146  and line  147   g , the C 3+  olefin can combine with the combined feed components in combined feed line  193 . In the aspect where the C 3+  olefin for a period of time can be introduced/fed via line  146  and line  147   g , the C 3+  olefin can flow via lines  146 ,  147   g , and  193  to the reaction zone  110 . 
     With respect to the commencement of the flow of the C 3+  olefin relative to the commencement of the flow of ethylene for the period of time, the flow of C 3+  olefin can commence before or simultaneously with the flow of ethylene regardless which of lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e ,  147   f , and/or  147   g  the C 3+  olefin flows. Alternatively, the flow of the C 3+  olefin can commence before the flow of ethylene (when the reaction zone  110  is empty, for example, during hard startup, or when the reaction zone  110  already contains material, for example, in a soft startup after temporary cessation of the flow of ethylene and/or catalyst system to the reaction zone  110  to address process or system issues), then be stopped temporarily, and then again commenced before or at the same time (simultaneously) as the flow of ethylene and/or catalyst system. 
     With respect to the commencement of the flow of the C 3+  olefin relative to the commencement of the flow of catalyst system for the period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the catalyst system regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e ,  147   f , and/or  147   g  the C 3+  olefin flows. 
     With respect to the commencement of the flow of the C 3+  olefin relative to the commencement of the flow of organic reaction medium for the period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the organic reaction medium regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e ,  147   f , and/or  147   g  the C 3+  olefin flows. 
     With respect to the commencement of the flow of the C 3+  olefin relative to the commencement of the flow of scrub agent for the period of time, the flow of the C 3+  olefin can commence before, simultaneously, or after the flow of the scrub agent regardless of which lines  147   a ,  147   b ,  147   c ,  147   d ,  147   e ,  147   f , and/or  147   g  the C 3+  olefin flows. 
     Reaction zone  110  in  FIGS. 1-3  is shown as a single continuous stirred-tank reactor operating in continuous mode with a continuous stirred-tank configuration. Various alternative configurations and/or operating modes that can achieve desired ethylene oligomerization results are contemplated for the reaction zone  110  and are discussed in more detail herein. In  FIGS. 1-3 , thermocouple  114  can read the temperature of the reaction zone  110  as the reaction proceeds. Stirrer  116  of  FIGS. 1-3  operated by motor  112  can agitate the contents of the reaction zone  110 . The stirrer  116  of  FIGS. 1-3  can be an impeller coupled to the motor  112  via a rod. Heat exchanger  120  of  FIGS. 1-3  can receive line  122  and can provide line  124  to the reaction zone  110  in order to maintain a temperature of the reaction zone  110 . 
     A reaction zone effluent comprising an ethylene oligomer product formed in the reaction zone  110  in  FIGS. 1-3  can flow in line  118  from reaction zone outlet  117 . In some embodiments, the ethylene oligomer product in line  118  can flow to the product recovery zone (not shown). The product recovery zone can include catalyst system deactivation, an oligomer product separation where the ethylene oligomer product (e.g., hexenes and/or octenes) can be recovered from the reaction zone effluent via techniques known in the art with the aid of this disclosure (e.g., distillation, flashing, absorption, stripping), by-product separation and/or isolation, and/or any steps which can facilitate the handling of the reaction zone effluent and the isolation of the desired ethylene oligomers. 
     The reaction zone of any process, system and/or reaction system (e.g., reaction zone  110  of the figures) can comprise any reactor which can oligomerize ethylene to an ethylene oligomer product. In an embodiment, the reaction zone of any process, system, or reaction system described herein can comprise a stirred tank reactor, a plug flow reactor, or any combination thereof; alternatively, a stirred tank reactor; or alternatively, a plug flow reactor. In an embodiment, the reaction zone of any process, system, or reaction system described herein can comprise an autoclave reactor, a continuous stirred tank reactor, a loop reactor, a gas phase reactor, a solution reactor, a tubular reactor, a recycle reactor, a bubble reactor, or any combination thereof; alternatively, an autoclave reactor; alternatively, a stirred tank reactor; alternatively, a loop reactor; alternatively, a gas phase reactor; alternatively, a solution reactor; alternatively, a tubular reactor; alternatively, a recycle reactor; or alternatively, a bubble reactor. In some embodiments, the reaction zone can comprise multiple reactor; or alternatively, only on reactor. When multiple reactors are present, each of the reactors can be the same or different types of reactors. The reaction zone (e.g., reaction zone  110 ) can comprise single or multiple reactors of any of the types disclosed herein operating in batch or continuous mode; alternatively, continuous mode. 
     Aspects and/or embodiments of the processes, systems, and/or reaction systems described herein can utilize a pump. In an embodiment, the pump can be any pump which can pump the organic reaction medium to the reaction zone. Generally, the pump can have a suction side which receives the organic reaction medium and a head side which provides the organic reaction medium at a pressure suitable for flow to the reaction zone.  FIG. 1 ,  FIG. 2 , and  FIG. 3  provide non-liming examples of reaction systems which can utilize a pump  180  having suction side  181  and head side  182 . In  FIG. 1 , pump  180  is in fluid communication with the reaction zone inlet  215 . In  FIG. 2 , pump  180  is in fluid communication with the reaction zone inlet  113 . In  FIG. 3 , pump  180  is in fluid communication with reaction zone inlet  119 .  FIG. 1 ,  FIG. 2 , and  FIG. 3  show that pump  180  can be located upstream of the point where ethylene (e.g., from the ethylene feed line  142 ) and the organic reaction medium (e.g., from the organic reaction medium feed line  162  which optionally contains scrub agent and/or catalyst system) join/combine to form the feedstock mixture. Feeding ethylene in this configuration can reduce flashing and recompression. In an embodiment, the pump  180  can be configured to receive the catalyst system and/or the scrub agent combined with the organic reaction medium on the suction side  181  of the pump  180 ; alternatively, the catalyst system and/or the scrub agent can be combined with the organic reaction medium on the head side  182  of the pump  180 ; alternatively, the catalyst system can be combined with the organic reaction medium on the suction side  181  of the pump  180  while the scrub agent can be combined with the organic reaction medium and catalyst system on the head side  182  of the pump; alternatively, the scrub agent can be combined with the organic reaction medium on the suction side  181  of the pump  180  while the catalyst system can be combined with the organic reaction medium and scrub agent on the head side  182  of the pump  180 . In the system  300  in  FIG. 3 , pump  180  can be configured to receive the catalyst system combined with the organic reaction medium on the suction side  181  and to pump the catalyst system combined with the organic reaction medium and optional scrub agent on the head side  182  of the pump  180 . 
     In configurations where the reaction zone  110  has a recycle features, a pump can be included in the path of the reaction zone  110  suitable for passing contents of the reaction zone  110  to heat exchangers. For example a pump suitable for pumping reaction zone contents can be placed in line  122  of  FIG. 1 ,  FIG. 2 , or  FIG. 3  to pass the contents to the heat exchanger  120 . 
     Aspects and/or embodiments of the processes, systems, and/or reaction systems described herein can utilize a mixing device to mix/disperse the ethylene and the organic reaction medium. In an embodiment, the mixing device can be any device which can mix/disperse the organic reaction medium and ethylene in the feedstock mixture. Such mixing/dispersing can be implemented to minimize areas of high ethylene concentration within the feedstock mixture. The mixing device can provide mixing of ethylene and the organic reaction medium via agitation of the flow there through. For example, the mixing device can be a static mixer having fixed baffles (e.g., in a helical arrangement, or any other baffle arrangement) placed within a housing, where the baffles continuously blend the ethylene and organic reaction medium to disperse the ethylene and the organic reaction medium in the feedstock mixture. Alternatively, the mixing device can have moving parts such as a propeller or impeller.  FIG. 1  shows an optional mixing device  190  that can be positioned between i) the joining of the ethylene feed line  142  and the organic reaction medium feed line  162  and ii) the second reaction zone inlet  113  such that ethylene and the organic reaction medium are dispersed in the feedstock mixture prior to the feedstock mixture entering the reaction zone  110 .  FIG. 2  shows an optional mixing device  190  can be positioned between i) the joining of the ethylene feed line  142  and the organic reaction medium feed line  162  and ii) the reaction zone inlet  119  such that ethylene and the organic reaction medium are dispersed in the feedstock mixture prior to the ethylene feedstock combining with the catalyst system and prior to the feedstock mixture entering the reaction zone  110 . In some embodiments, the mixing/dispersion of the ethylene and the organic reaction medium can be accomplished using a precontactor device such a vessel with a mixing device. 
     Lines  118 ,  122 ,  124 ,  142 ,  146 ,  147   a - g ,  152 ,  162 ,  172 ,  191 ,  192 , and  193  shown in the figures can be appropriate metal piping or tubing for ethylene oligomerization reaction system components. 
     The reaction zone inlets  111 ,  113 ,  115 ,  119 ,  213 , and  215  as well as the reaction zone outlet  117 , shown in the figures can be in the form of flanges and/or appropriate piping and valves for receiving the various feed components and removing the reaction zone effluent from the reaction zone  110 . The reaction zone outlet  117  can be one or more physical outlets. For example, the reaction zone  110  shown in  FIG. 1 ,  FIG. 2 , and  FIG. 3  can have one outlet  117 ; alternatively, the reaction zone  110  can have one or more other outlets in addition to outlet  117 ; alternatively, the reaction zone  110  can include multiple reactors, each having a single outlet or multiple outlets which amount to more than one outlet for the collection of multiple reactors which define the reaction zone  110 . Additionally, each reaction zone inlet which is shown as a single reaction zone inlet can represent one or more reaction inlets feeding the designated materials to the reaction zone. 
     Ethylene for any of the processes, systems, and/or reaction systems described herein (e.g., ethylene source  140 ) can be oligomerization or polymerization grade ethylene. By “oligomerization or polymerization grade ethylene” it is meant that ethylene is present in ethylene feed line  142  in an amount of at least 98.0, 98.5, 99.0, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8, 99.9, 99.99, 99.999 mol % based on the total moles of components in the ethylene composition (e.g., ethylene feed line  142 ). The ethylene for any of the processes, systems, and/or reaction systems (e.g., ethylene source  140 ) can be any source of oligomerization or polymerization grade ethylene, for example, a storage tank or a line from a cracking process, monomer recovery process, and the like. In an embodiment of the processes, systems, and/or reaction systems (e.g., reaction systems  100 ,  200 , and  300 ) disclosed herein, substantially all of the ethylene used in the disclosed processes, systems, and/or reaction systems (e.g., reaction systems  100 ,  200 , and  300 ) can be contacted with the catalyst system and/or introduced/fed to the reaction zone via the feedstock mixture. By “substantially all” it is meant that at least 99.0, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8, 99.9, 99.99, 99.999 mol % of the total ethylene used by the processes, systems, and/or reactions systems (e.g. reaction systems  100 ,  200 , or  300 ) described herein can be introduced/fed to the reaction zone via the feedstock mixture. 
     The C 3+  olefin can be one or a combination of olefins having three or more carbon atoms. In an aspect, the C 3+  olefin can be a C 3  to C 18  olefin, a C 4  to C 14  olefin, or a C 6  to C 12  olefin. In an embodiment, any olefin which can be utilized in the processes, systems, and/or reaction systems described herein can be an internal olefin, or an alpha olefin. In some embodiments, the internal olefin or alpha olefin can be branched or linear; alternatively, branched; or alternatively, linear. In some embodiments, as the C 3+  olefin any olefin which can be utilized in the processes, systems, and/or reaction systems described herein can be a normal alpha olefin. Suitable non-limiting examples of the C 3+  olefin include one or more of propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, or any combination thereof. In an embodiment, the C 3+  olefin can comprise iso-butene. In an embodiment, the C 3+  olefin can comprise, or consist essentially of, propene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexedecene, 1-octacene, or any combination thereof; alternatively, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, or any combination thereof; alternatively, 1-hexene, 1-octene, 1-decene, 1-docene, or any combination thereof; alternatively, 1-hexene, 1-octene, or any combination thereof; alternatively, propene; alternatively, 1-butene; alternatively, 1-hexene; alternatively, 1-octene; alternatively, 1-decene; or alternatively, 1-dodecene. The C 3+  olefin source  145  can be any source of olefins having 3 or more carbon atoms, including a recycle line which flows a C 3+  olefin recovered from an oligomer product to the C 3+  olefin feed line  146 . 
     The processes, systems, and/or reaction systems described herein can use an organic reaction medium. Generally, the organic reaction can act as a solvent or a diluent in the processes described herein. In an aspect, the organic reaction medium can be a hydrocarbon, a halogenated hydrocarbon, or a combination thereof, for example. Hydrocarbons and halogenated hydrocarbons which can be used as an organic reaction medium can include, for example, aliphatic hydrocarbons, aromatic hydrocarbons, petroleum distillates, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, or combinations thereof. Aliphatic hydrocarbons which can be useful as an organic reaction medium include C 3  to C 20  aliphatic hydrocarbons, or C 4  to C 15  aliphatic hydrocarbons, or C 5  to C 10  aliphatic hydrocarbons, for example. The aliphatic hydrocarbons which can be used as an organic reaction medium can be cyclic or acyclic and/or can be linear or branched, unless otherwise specified. Non-limiting examples of suitable acyclic aliphatic hydrocarbon organic reaction mediums that can be utilized singly or in any combination include propane, iso-butane, n-butane, butane (n-butane or a mixture of linear and branched C 4  acyclic aliphatic hydrocarbons), pentane (n-pentane or a mixture of linear and branched C 5  acyclic aliphatic hydrocarbons), hexane (n-hexane or mixture of linear and branched C 6  acyclic aliphatic hydrocarbons), heptane (n-heptane or mixture of linear and branched C 7  acyclic aliphatic hydrocarbons), octane (n-octane or a mixture of linear and branched C 8  acyclic aliphatic hydrocarbons), or combinations thereof. Non-limiting examples of suitable cyclic aliphatic hydrocarbons which can be used as an organic reaction medium include cyclohexane, and methyl cyclohexane, for example. Aromatic hydrocarbons which can be useful as an organic reaction medium include C 6  to C 10  aromatic hydrocarbons. Non-limiting examples of suitable aromatic hydrocarbons that can be utilized singly or in any combination as an organic reaction medium include benzene, toluene, xylene (including ortho-xylene, meta-xylene, para-xylene, or mixtures thereof), ethylbenzene, or combinations thereof. Halogenated aliphatic hydrocarbons which can be useful as an organic reaction medium include C 1  to C 15  halogenated aliphatic hydrocarbons, C 1  to C 10  halogenated aliphatic hydrocarbons, or C 1  to C 5  halogenated aliphatic hydrocarbons, for example. The halogenated aliphatic hydrocarbons which can be used as an organic reaction medium can be cyclic or acyclic and/or can be linear or branched, unless otherwise specified. Non-limiting examples of suitable halogenated aliphatic hydrocarbons which can be utilized as an organic reaction medium include methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, and combinations thereof. Halogenated aromatic hydrocarbons which can be useful as an organic reaction medium include C 6  to C 20  halogenated aromatic hydrocarbons, or C 6  to C 10  halogenated aromatic hydrocarbons, for example. Non-limiting examples of suitable halogenated aromatic hydrocarbons which can be used as a solvent include chlorobenzene, dichlorobenzene, or combinations thereof, for example. 
     The choice of organic reaction medium can be made on the basis of convenience in processing. For example, isobutane can be chosen to be compatible with solvents and diluents used in processes using the product(s) of the process described herein (e.g., using the product for the formation of polymer in a subsequent processing step). In some embodiments, the organic reaction medium can be chosen to be easily separable from the one or more of the oligomer in the ethylene oligomer product. In some embodiments, an oligomer of the ethylene oligomer product can be utilized as the reaction system solvent. For example, when 1-hexene is an oligomer of an ethylene trimerization process, 1-hexene can be chosen as the reaction system solvent to decrease the need for separation. 
     The organic reaction medium source (e.g., organic reaction medium source  160 ) can be any source for an organic reaction medium, including a storage tank of the organic reaction medium and any line from an oligomerization process, a polymerization process, monomer recovery process, and the like. 
     While in  FIG. 1 ,  FIG. 2 , and  FIG. 3  the entire supply of organic reaction medium is shown flowing in line  162  from the organic reaction medium source  160  to the reaction zone  110 , it is contemplated that only a portion of the total amount of organic reaction medium used in systems  100 ,  200 , and  300  flows in line  162 , and that a bypass line can be alternatively utilized to flow another portion of the organic reaction medium (e.g., a portion which is not combined with any other reaction component) directly to the reaction zone  110  and in parallel flow to line  162 . Additionally or alternatively, a portion of the total amount of organic reaction medium in the system  100 ,  200 , or  300  can be utilized in the catalyst system feed line  152 . That is, a portion of the organic reaction medium can be used to dilute or act as a carrying fluid for the catalyst system in catalyst system feed line  152 . 
     As described herein, aspects and embodiments of the disclosed processes, systems and/or reaction systems can include combining ethylene and an organic reaction medium to form a feedstock mixture. The minimum ethylene concentration in the feedstock mixture can be 4 mass %, 10 mass %, 25 mass %, 35 mass %, or 40 mass % based upon the total mass in the feedstock mixture; alternatively or additionally, at a maximum ethylene concentration of the feedstock mixture cam be 65 mass %, 60 mass %, 55 mass %, 50 mass %, 48 mass % based upon the total mass in the reaction zone. In an embodiment, ethylene concentration in the feedstock mixture can from any minimum ethylene concentration in the feedstock mixture disclosed herein to any maximum ethylene concentration in the feedstock mixture disclosed herein. In some non-limiting embodiments, the ethylene concentration in the feedstock mixture can be in a range of from 4 mass % to 60 mass %, from 10 mass % to 60 mass %, from 25 mass % to 55 mass %, 35 mass % to 50 mass %, or 40 mass % to 48 mass % based upon the total mass in the reaction zone. Other ethylene concentrations in the feedstock mixture ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     Aspects and embodiments of the herein described processes, systems, and/or reaction systems can utilize a catalyst system comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane; or alternatively, i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane. Generally, the chromium compound, the heteroatomic ligand, the heteroatomic ligand chromium compound complex, the aluminoxane, and any other element of the catalyst system described herein are independent elements of their respective catalyst systems. These catalyst system elements are independently described herein and can be utilized without limitation, and in any combination, to further describe catalyst system utilized in aspects and/or embodiments of the processes, systems, and/or reaction systems described herein. 
     Generally, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can have formula CrX p  where X represents a monoanionic ligand, and p represent the number of monoatomic ligands (and the oxidation state of the chromium in the chromium compound. The monoanionic ligand (X), and p are independent elements of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein and are independently described herein. The independent descriptions of the monoanionic ligand (X) and p can be utilized without limitation, and in any combination, to further describe the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein. 
     Generally, the chromium atom of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can have any positive oxidation state available to a chromium atom. In an embodiment, the chromium atom can have an oxidation state of from +2 to +6; alternatively, from +2 to +4; or alternatively, from +2 to +3. In some embodiments, the chromium atom of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can have an oxidation state of +1; alternatively, +2; alternatively, +3; or alternatively, +4. 
     The monoanion, X, of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can be any monoanion. In an embodiment, the monoanion, X, can be a halide, a carboxylate, a β-diketonate, a hydrocarboxide, a nitrate, or a chlorate. In some embodiments, the monoanion, X, can be a halide, a carboxylate, a β-diketonate, or a hydrocarboxide. In any aspect or embodiment, the hydrocarboxide can be an alkoxide, an aryloxide, or an aralkoxide. Generally, hydrocarboxide (and subdivisions of hydrocarboxide) are the anion analogues of the hydrocarboxy group. In other embodiments, the monoanion, X, can be a halide, a carboxylate, a β-diketonate, or an alkoxide; or alternatively, a halide or a β-diketonate. In other embodiments, the monoanion, X, can be a halide; alternatively, a carboxylate; alternatively, a β-diketonate; alternatively, a hydrocarboxide; alternatively, an alkoxide; or alternatively, an aryloxide. Generally, the number, p, of monoanions can equal the oxidation state of the metal atom. In an embodiment, the number, p, of monoanions, X, can be from 2 to 6; alternatively, from 2 to 4; alternatively, from 2 to 3; alternatively, 1; alternatively, 2; alternatively, 3; or alternatively, 4. 
     Generally, each halide monoanion, X, of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be fluorine, chlorine, bromine, or iodine; or alternatively, chlorine, bromine, or iodine. In an embodiment, each halide monoanion, X, of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can be chlorine; alternatively, bromine; or alternatively, iodine. 
     Generally, each carboxylate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be a C 1  to C 20  carboxylate; or alternatively, a C 1  to C 10  carboxylate. In an embodiment, each carboxylate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be acetate, a propionate, a butyrate, a pentanoate, a hexanoate, a heptanoate, an octanoate, a nonanoate, a decanoate, an undecanoate, or a dodecanoate; or alternatively, a pentanoate, a hexanoate, a heptanoate, an octanoate, a nonanoate, a decanoate, an undecanoate, or a dodecanoate. In some embodiments, each carboxylate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be acetate, propionate, n-butyrate, valerate (n-pentanoate), neo-pentanoate, capronate (n-hexanoate), n-heptanoate, caprylate (n-octanoate), 2-ethylhexanoate, n-nonanoate, caprate (n-decanoate), n-undecanoate, or laurate (n-dodecanoate); alternatively, valerate (n-pentanoate), neo-pentanoate, capronate (n-hexanoate), n-heptanoate, caprylate (n-octanoate), 2-ethylhexanoate, n-nonanoate, caprate (n-decanoate), n-undecanoate, or laurate (n-dodecanoate); alternatively, capronate (n-hexanoate); alternatively, n-heptanoate; alternatively, caprylate (n-octanoate); or alternatively, 2-ethylhexanoate. In some embodiments, the carboxylate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can be triflate (trifluoroacetate). 
     Generally, each β-diketonate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complex independently can be any C 1  to C 20  a β-diketonate; or alternatively, any C 1  to C 10  β-diketonate. In an embodiment, each β-diketonate monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be acetylacetonate (i.e., 2,4-pentanedionate), hexafluoroacetylacetone (i.e., 1,1,1,5,5,5-hexafluoro-2,4-pentanediuonate), or benzoylacetonate); alternatively, acetylacetonate; alternatively, hexafluoroacetylacetone; or alternatively, benzoylacetonate. 
     Generally, each hydrocarboxide monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be any C 1  to C 20  hydrocarboxide; or alternatively, any C 1  to C 10  hydrocarboxide. In an embodiment, each hydrocarboxide monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be a C 1  to C 20  alkoxide; alternatively, a C 1  to C 10  alkoxide; alternatively, a C 6  to C 20  aryloxide; or alternatively, a C 6  to C 10  aryloxide. In an embodiment, each alkoxide monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be methoxide, ethoxide, a propoxide, or a butoxide. In some embodiments, each alkoxide monoanion of the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein independently can be methoxide, ethoxide, isopropoxide, or tert-butoxide; alternatively, methoxide; alternatively, an ethoxide; alternatively, an iso-propoxide; or alternatively, a tert-butoxide. In an aspect, the aryloxide can be phenoxide. 
     In a non-limiting embodiment, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complex can comprise, can consist essentially of, or consist of, a chromium(II) halide, a chromium(III) halide, a chromium(II) carboxylate, chromium(III) carboxylate, a chromium(II) β-diketonate, or a chromium(III) β-diketonate. In some non-limiting embodiments, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complex can consist essentially of, or consist of, a chromium(II) halide, a chromium(II) carboxylate, or a chromium(II) β-diketonate; or alternatively, a chromium(III) halide, a chromium(III) carboxylate, or a chromium(III) β-diketonate. In other non-limiting embodiments, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complex can comprise, can consist essentially of, or consist of, a chromium(II) halide; alternatively, a chromium(III) halide; alternatively, a chromium (II) carboxylate; alternatively, a chromium(III) carboxylate; alternatively, a chromium(II) β-diketonate; or alternatively, a chromium(III) β-diketonate. 
     In a non-limiting embodiment, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can comprise, can consist essentially of, or consist of, chromium(II) chloride, chromium(III) chloride, chromium(II) fluoride, chromium(III) fluoride, chromium(II) bromide, chromium(III) bromide, chromium(II) iodide, chromium(III) iodide, chromium(II) acetate, chromium(III) acetate, chromium(II) 2-ethylhexanoate, chromium(III) 2-ethylhexanoate, chromium(II) triflate, chromium(III) triflate, chromium(II) nitrate, chromium(III) nitrate, chromium(II) acetylacetonate, chromium(III) acetylacetonate, chromium(II) hexafluoracetylacetonate, chromium(III) hexafluoracetylacetonate, chromium(III) benzoylacetonate, or chromium(III) benzoylacetonate. In some non-limiting embodiments, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein can comprise, can consist essentially of, or consist of, chromium(III) chloride, chromium(III) fluoride, chromium(III) bromide, chromium(III) iodide, chromium(III) chloride (THF) complex, chromium(III) acetate, chromium(III) 2-ethylhexanoate, chromium(III) triflate, chromium(III) nitrate, chromium(III) acetylacetonate, chromium(III) hexafluoracetylacetonate, or chromium(III) benzoylacetonate. In further embodiments, the chromium compound or the chromium compound of the heteroatomic ligand chromium compound complexes described herein described herein can be chromium(III) chloride, or chromium(III) acetylacetonate; alternatively, chromium(III) chloride; or alternatively, chromium(III) acetylacetonate. 
     In an embodiment, the heteroatomic ligand or the heteroatomic ligand of the heteroatomic ligand chromium compound complex can have the formula (R 1s ) m X 1a (L 1s )X 1s (R 1s ) n  while the heteroatomic ligand of the heteroatomic ligand chromium compound complex can have the formula: 
     
       
         
         
             
             
         
       
     
     In some embodiments, the heteroatomic ligand or the heteroatomic ligand of the heteroatomic ligand chromium compound complex can have two groups capable of being described by the formula (R 1s ) m X 1a (L 1s )X 1s (R 1s ) n . In instances wherein the heteroatomic ligand can have two groups capable of being described by the formula (R 1s ) m X 1a (L 1s )X 1s (R 1s ) n , the two L 1s  groups are linked and the heteroatomic ligand and the heteroatomic ligand chromium compound complex can have the formulas: 
                         
respectively.
 
     In the heteroatomic ligand or the heteroatomic ligand of the heteroatomic ligand chromium compound complex having formula (R 1s ) m X 1a (L 1s )X 1s (R 1s ) n  or having two linked (R 1s ) m X 1a (L 1s )X 1s (R 1s ) n  groups, each X 1s  and each X 2s  is independently selected from the group consisting of N, P, O, and S; each L 1s  is an independent linking group between the respective X 1s s and X 2s s; each m and each n are independently 1 or 2; and each R 1s  and each R 2s  are independently hydrogen, an organyl group (or alternatively, an organyl group consisting essentially of inert functional group; or alternatively, a hydrocarbyl group), or a heterohydrocarbyl group, where when there are two or more R 1s s and/or two R 2s s, each R 1s  can be the same or different (alternatively, the same; or alternatively, different) and/or each R 2s  can be the same or different (alternatively, the same; or alternatively, different). Additionally, in the heteroatomic ligand chromium compound complex, X is a monoanionic ligand and p is the number of monoanionic ligands in the heteroatomic ligand chromium compound complex. L 1s , X 1s , X 2s , R 1s , R 2s , m, and n are independent elements of any heteroatomic ligand or any heteroatomic ligand of the heteroatomic ligand chromium compound complex which have an L 1s , X 1s , X 2s , R 1s , R 2s , m, and/or n and are independently described herein. These independent descriptions of L 1s , X 1s , X 2s , R 1s , R 2s , m, and n can be utilized without limitation, and in any combination, to further describe any heteroatomic ligand or any heteroatomic ligand of the heteroatomic ligand chromium compound complex which have an L 1s , X 1s , X 2s , R 1s , R 2s , m, and/or n. Additionally, X and p are independent elements of the chromium compound of the heteroatomic ligand chromium compound complex, are independently described herein, and can be utilized without limitation, and in any combination, to further describe the chromium compound of the heteroatomic ligand chromium compound complex, and can be utilized without limitation, and in any combination with L 1s , X 1s , X 2s , R 1s , R 2s , m, and n of the heteroatomic ligand to further describe the heteroatomic ligand chromium compound complexes contemplated herein. 
     Each X 1s  and each X 2s  of any heteroatomic ligand described herein or any heteroatomic ligand of any heteroatomic ligand chromium compound complex described herein having an X 1s  and/or X 2s  can be independently selected from N, P, O, and S; alternatively, independently selected from N and P; or alternatively, independently selected from O and S. In some embodiments, each X 1s  and each X 2s  can be N; alternatively, P; alternatively O; or alternatively S. Each m and each n of any heteroatomic ligand described herein or any heteroatomic ligand of any heteroatomic ligand chromium compound complex described herein having an m and/or n can be independently selected from 1 or 2; alternatively, 1; or alternatively, 2. Is some particular embodiments, each m and/or each n can be 1 when X 1s  and/or X 2s , respectively, is O or S; alternatively, O; or alternatively, S. In some other particular embodiments, each m and/or each n can be 2 when X 1s  and/or X 2s , respectively, is N or P; alternatively, N; or alternatively, P. 
     In a non-limiting embodiment, the heteroatomic ligand can have the formula R 1s S(L 1s )SR 1s , (R 1s ) 2 P(L 1s )P(R 1s ) 2 , or (R 1s ) 2 N(L 1s )N(R 1s ) 2 ; alternatively, R 1s S(L 1s )SR 1s   n ; alternatively, (R 1s ) 2 P(L 1s )P(R 1s ) 2 ; or alternatively, (R 1s ) 2 N(L 1s )NP(R 1s ) 2  while heteroatomic ligand chromium compound complex can have any one of the formulas. 
                         
In non-limiting embodiments where the heteroatomic ligand or the heteroatomic ligand of the heteroatomic ligand chromium compound complex has two linked heteroatomic groups, the heteroatomic ligand can have the formula selected from one or more of
 
                         
while the heteroatomic ligand chromium compound complex can have any one of the formulas
 
     
       
         
         
             
             
         
       
     
     In an embodiment, each L 1s  of any heteroatomic ligand described herein or any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein independently can be any group capable of linking group X 1s  and X 2s . In some embodiments, each L 2s  independently can be an organylene group, an amin-di-yl group, or a phosphin-di-yl group; alternatively, an organylene group consisting of inert functional groups, an amin-di-yl group, or a phosphin-di-yl group; alternatively, a hydrocarbylene group, an amin-di-yl group, or a phosphin-di-yl group; alternatively an amin-di-yl group or a phosphin-di-yl group; alternatively, an organylene group; alternatively, an organylene group consisting of inert functional groups; alternatively, a hydrocarbylene group; alternatively, an amin-di-yl group; or alternatively, a phosphin-di-yl group. In an embodiment, the L 1s  organylene group that can be utilized as L 1s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or, a C 1  to C 5  organylene group. In an embodiment, the L 1s  organylene group consisting of inert functional groups that can be utilized as L 1s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or, a C 1  to C 5  organylene group consisting of inert functional groups. In an embodiment, the L 1s  hydrocarbylene group that can be utilized as L 1s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  hydrocarbylene group. In an embodiment, the amin-di-yl group that can be utilized as L 1s  can be a C 1  to C 30 , a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  amin-di-yl group. In an embodiment, the phosphin-di-yl group that can be utilized as L 1s  can be a C 1  to C 30 , a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  phosphin-di-yl group. 
     In an embodiment, the each organylene L 1s  group can have the formula -(L 3s )NR 5 (L 4s )- or -(L 3s ) alternatively, -(L 3s )NR 5 (L 4s ) or alternatively, -(L 3s )PR 5 (L 4s )-. In an embodiment, the each amin-di-yl group can have the formula —N(R 5 )—. In an embodiment, each phosphin-di-yl group can have the formula —P(R 5 )—. In these L 1s  group formulas, the dashes represent the undesignated valance to which the X 1s  and X 2s  of the heteroatomic ligand described herein or the heteroatomic ligand of the heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein attach. In some non-limiting embodiments, the heteroatomic ligand can have Structure PNP1, Structure PNP2, Structure NRN, Structure PRP, Structure SRN, Structure PRN, and Structure NRP; alternatively, Structure PNP1 or Structure PNP2; alternatively, Structure PRP, Structure SRN, or Structure PRN; alternatively, Structure PNP 1; alternatively, Structure PNP2; alternatively, Structure NRN; alternatively, Structure PRP; alternatively, Structure SRN; alternatively, Structure PRN; or alternatively, Structure NRP. In some non-limiting embodiments, the heteroatomic ligand chromium compound complex having a heteroatomic ligand (R 1s ) m X 1s (L 1s )X 1s )R 1s ) n  which can be utilized in catalyst systems described herein can have Structure PNCr1, Structure PNPCr2, Structure NRNCr, Structure PRPCr, Structure SRNCr, Structure PRNCr, and Structure NRPCr; alternatively, Structure PNPCr1 or Structure PNPCr2; alternatively, Structure PRPCr, Structure SRNCr, or Structure PRNCr; alternatively, Structure PNPCr1; alternatively, Structure PNPCr2; alternatively, Structure NRNCr; alternatively, Structure PRPCr; alternatively, Structure SRNCr; alternatively, Structure PRNCr; or alternatively, Structure NRPCr. 
                         
R 5s , L 2s , L 3s , L 4s , R 11s , R 12s , R 13s , and R 14s  are each independent elements of any of the organylene groups described herein, any of the amin-di-yl groups described herein, any of the phosphin-di-yl groups described herein, any of the heteroatomic ligands having Structure PNP1, Structure PNP2, Structure NRN, Structure PRP, Structure SRN, Structure PRN, and Structure NRP, and any heteroatomic ligand portion of the heteroatomic ligand chromium compound complexes having Structure PNCr1, Structure PNPCr2, Structure NRNCr, Structure PRPCr, Structure SRNCr, Structure PRNCr, and Structure NRPCr in which they occur and are independently described herein. The independent descriptions of R 5s , L 2s , L 3s , L 4s , R 11s , R 12s , R 13s , and R 14s  can be utilized without limitation, and in any combination, to further describe any of the organylene groups described herein, any of the amin-di-yl groups described herein, any of the phosphin-di-yl groups described herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein in which they occur. Similarly, CrX p  is an independent element of the heteroatomic ligand chromium compound complexes having Structure PNCr1, Structure PNPCr2, Structure NRNCr, Structure PRPCr, Structure SRNCr, Structure PRNCr, and Structure NRPCr and is independently described herein. The independent description of CrX p  can be utilized without limitation, and in any combination, to further describe the chromium compound portion of any heteroatomic ligand chromium compound complex described herein and/or any heteroatomic ligand chromium compound complex structure provided herein. Additionally, the independent description of CrX p  can be utilized without limitation, and in any combination, with the independently described R 5s , L 2s , L 3s , L 4s , R 11s , R 12s , R 13s , and R 14s  provided herein to further describe any heteroatomic ligand chromium compound complex structure provided herein.
 
     Generally, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  of any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein having a R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  and/or independently can be an organyl group; alternatively, an organyl group consisting of inert functional groups; or alternatively, a hydrocarbyl group. In an embodiment, the organyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  organyl group. In an embodiment, the organyl group consisting of inert functional groups which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  organyl group consisting of inert functional groups. In an embodiment, the hydrocarbyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  hydrocarbyl group. In further embodiments, R 1s  and R 2s , R 11s  and R 12s , and/or R 13s  and R 14s  can be joined to form a ring or a ring system. 
     In an embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  of any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein having a R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be independently can be an alkyl group, a substituted alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aryl group, a substituted aryl group, an aralkyl group, or a substituted aralkyl group; alternatively, an alkyl group or a substituted alkyl group; alternatively, a cycloalkyl group or a substituted cycloalkyl group; alternatively, an aryl group or a substituted aryl group; alternatively, an aralkyl group or a substituted aralkyl group; or alternatively, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. In other embodiments, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  of any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein having a R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  independently can be an alkyl group; alternatively, a substituted alkyl roup, alternatively, a cycloalkyl group; alternatively, a substituted cycloalkyl group; alternatively, an aryl group; alternatively, a substituted aryl group; alternatively, an aralkyl group; or alternatively, a substituted aralkyl group. 
     In any aspect or embodiment disclosed herein, each alkyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 1  to C 20 , a C 1  to C 10 , or a C 1  to C 5  alkyl group. In any aspect or embodiment disclosed herein, each substituted alkyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 1  to C 20 , a C 1  to C 10 , or a C 1  to C 5  substituted alkyl group. In any aspect or embodiment disclosed herein, each cycloalkyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 4  to C 20 , a C 4  to C 15 , or a C 4  to C 10  cycloalkyl group. In any aspect or embodiment disclosed herein, each substituted cycloalkyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 4  to C 20 , a C 4  to C 15 , or a C 4  to C 10  substituted cycloalkyl group. In any aspect or embodiment disclosed herein, each aryl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 6  to C 20 , a C 6  to C 15 , or a C 6  to C 10  aryl group. In any aspect or embodiment disclosed herein, each substituted aryl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 6  to C 20 , a C 6  to C 15 , or a C 6  to C 10  substituted aryl group. In any aspect or embodiment disclosed herein, each aralkyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 7  to C 20 , a C 7  to C 15 , or a C 7  to C 10  aralkyl group. In any aspect or embodiment disclosed herein, each substituted aryl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  independently can be a C 7  to C 20 , a C 7  to C 15 , or a C 7  to C 10  substituted aralkyl group. Each substituent of a substituted alkyl group (general or specific), a substituted cycloalkyl group (general or specific), a substituted aryl group (general or specific), and/or substituted aralkyl group (general or specific) can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens, substituent hydrocarboxy groups, and substituent hydrocarboxy groups can be utilized without limitation to further describe a substituted group (general or specific) which can be utilized R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . 
     In an embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group; alternatively, a methyl group, an ethyl group, an iso-propyl (2-propyl) group, a tert-butyl (2-methyl-2-propyl) group, or a neopentyl (2,2-dimethyl-1-propyl) group; alternatively, a methyl group; alternatively, an ethyl group; alternatively, a n-propyl (1-propyl) group; alternatively, an iso-propyl (2-propyl) group; alternatively, a tert-butyl (2-methyl-2-propyl) group; or alternatively, a neopentyl (2,2-dimethyl-1-propyl) group. In some embodiments, the alkyl groups which can be utilized as each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s  independently can be substituted. Each substituent of a substituted alkyl group independently can be a halogen or a hydrocarboxy group; alternatively, a halogen; or alternatively, a hydrocarboxy group. Substituent halogens and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens and substituent hydrocarboxy groups can be utilized without limitation to further describe a substituted alkyl group (general or specific) which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . 
     In an embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl group, or a substituted cyclohexyl group; alternatively, a cyclopentyl group or a substituted cyclopentyl group; or alternatively, a cyclohexyl group or a substituted cyclohexyl group; alternatively, a cyclopentyl group; alternatively, a substituted cyclopentyl group; alternatively, a cyclohexyl group; or alternatively, a substituted cyclohexyl group. In an embodiment, the substituted cycloalkyl group, which can be utilized for any of R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a 2-substituted cyclohexyl group, a 2,6-disubstituted cyclohexyl group, a 2-substituted cyclopentyl group, or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group or a 2,6-disubstituted cyclohexyl group; alternatively, a 2-substituted cyclopentyl group or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group or a 2-substituted cyclopentyl group; alternatively, a 2,6-disubstituted cyclohexyl group or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group; alternatively, a 2,6-disubstituted cyclohexyl group; alternatively, a 2-substituted cyclopentyl group; or alternatively, a 2,6-disubstituted cyclopentyl group. In an embodiment, one or more substituents of a multi-substituted cycloalkyl group utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  can be the same or different; alternatively, all the substituents of a multi-substituted cycloalkyl group can be the same; or alternatively, all the substituents of a multi-substituted cycloalkyl group can be different. Each substituent of a substituted cycloalkyl group (general or specific) having a specified number of ring carbon atoms independently can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen, alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens, substituent hydrocarbyl groups, and substituent hydrocarboxy groups can be utilized without limitation to further describe a substituted cycloalkyl group (general or specific) which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . 
     In a non-limiting embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a cyclohexyl group, a 2-alkylcyclohexyl group, or a 2,6-dialkylcyclohexyl group; alternatively, a cyclopentyl group, a 2-alkylcyclopentyl group, or a 2,5-dialkylcyclopentyl group; alternatively, a cyclohexyl group; alternatively, a 2-alkylcyclohexyl group; alternatively, a 2,6-dialkylcyclohexyl group; alternatively, a cyclopentyl group; alternatively, a 2-alkylcyclopentyl group; or alternatively, a 2,5-dialkylcyclopentyl group. Alkyl substituent groups (general and specific) are independently described herein and these alkyl substituent groups can be utilized, without limitation, to further describe alkylcyclohexyl groups (general or specific), dialkylcyclohexyl groups (general or specific), alkylcyclopentyl groups (general or specific), and/or dialkylcyclopentyl groups (general or specific) which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . Generally, the alkyl substituents of a disubstituted cyclohexyl or cyclopentyl group can be the same, or alternatively, the alkyl substituents can be different. In some non-limiting embodiments, each R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a 2-methylcyclohexyl group, a 2-ethylcyclohexyl group, a 2-isopropylcyclohexyl group, a 2-tert-butylcyclohexyl group, a 2,6-dimethylcyclohexyl group, a 2,6-diethylcyclohexyl group, a 2,6-diisopropylcyclohexyl group, or a 2,6-di-tert-butylcyclohexyl group; alternatively, a 2-methylcyclohexyl group, a 2-ethylcyclohexyl group, a 2-isopropylcyclohexyl group, or a 2-tert-butylcyclohexyl group; or alternatively, a 2,6-dimethylcyclohexyl group, a 2,6-diethylcyclohexyl group, a 2,6-diisopropylcyclohexyl group, or a 2,6-di-tert-butylcyclohexyl group. 
     In an embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group or a substituted phenyl group; alternatively, a phenyl group; or alternatively, a substituted phenyl group. In an embodiment, the substituted phenyl group which can be utilized for each R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a 2-substituted phenyl group, a 3-substituted phenyl group, a 4-substituted phenyl group, a 2,4-disubstituted phenyl group, a 2,6-disubstituted phenyl group, a 3,5-disubstituted phenyl group, or a 2,4,6-trisubstituted phenyl group; alternatively, a 2-substituted phenyl group, a 4-substituted phenyl group, a 2,4-disubstituted phenyl group, or a 2,6-disubstituted phenyl group; alternatively, a 3-substituted phenyl group or a 3,5-disubstituted phenyl group; alternatively, a 2-substituted phenyl group or a 4-substituted phenyl group; alternatively, a 2,4-disubstituted phenyl group or a 2,6-disubstituted phenyl group; alternatively, a 2-substituted phenyl group; alternatively, a 3-substituted phenyl group; alternatively, a 4-substituted phenyl group; alternatively, a 2,4-disubstituted phenyl group; alternatively, a 2,6-disubstituted phenyl group; alternatively, a 3,5-disubstituted phenyl group; or alternatively, a 2,4,6-trisubstituted phenyl group. In an embodiment, one or more substituents of a multi-substituted phenyl group utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s  can be the same or different; alternatively, all the substituents can be the same; or alternatively, all the substituents can be different. Each substituent of a substituted phenyl group (general or specific) independently can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens, substituent hydrocarbyl groups, and substituent hydrocarboxy group can be utilized without limitation to further describe a substituted phenyl group (general or specific) which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . 
     In a non-limiting embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-alkylphenyl group, a 3-alkylphenyl group, a 4-alkylphenyl group, a 2,4-dialkylphenyl group, a 2,6-dialkylphenyl group, a 3,5-dialkylphenyl group, or a 2,4,6-trialkylphenyl group; alternatively, a 2-alkylphenyl group, a 4-alkylphenyl group, a 2,4-dialkylphenyl group, a 2,6-dialkylphenyl group, or a 2,4,6-trialkylphenyl group; alternatively, a 2-alkylphenyl group or a 4-alkylphenyl group; alternatively, a 2,4-dialkylphenyl group or a 2,6-dialkylphenyl group; alternatively, a 3-alkylphenyl group or a 3,5-dialkylphenyl group; alternatively, a 2-alkylphenyl group or a 2,6-dialkylphenyl group; alternatively, a 2-alkylphenyl group; alternatively, a 4-alkylphenyl group; alternatively, a 2,4-dialkylphenyl group; alternatively, a 2,6-dialkylphenyl group; or alternatively, a 2,4,6-trialkylphenyl group. Alkyl substituent groups (general and specific) are independently described herein and these alkyl substituent groups can be utilized, without limitation, to further describe any alkyl substituted phenyl group which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . Generally, the alkyl substituents of dialkylphenyl groups (general or specific) or trialkylphenyl groups (general or specific) can be the same, or alternatively, the alkyl substituents can be different. In some non-limiting embodiments, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-methylphenyl group, a 2-ethylphenyl group, a 2-n-propylphenyl group, a 2-isopropylphenyl group, a 2-tert-butylphenyl group, a 2,6-dimethylphenyl group, a 2,6-diethylphenyl group, a 2,6-di-n-propylphenyl group, a 2,6-diisopropylphenyl group, a 2,6-di-tert-butylphenyl group, a 2-isopropyl-6-methylphenyl group, or a 2,4,6-trimethylphenyl group; alternatively, a phenyl group, a 2-methylphenyl group, a 2-ethylphenyl group, a 2-n-propylphenyl group, a 2-isopropylphenyl group, or a 2-tert-butylphenyl group; or alternatively, a phenyl group, a 2,6-dimethylphenyl group, a 2,6-diethylphenyl group, a 2,6-di-n-propylphenyl group, a 2,6-diisopropylphenyl group, a 2,6-di-tert-butylphenyl group, a 2-isopropyl-6-methylphenyl group, or a 2,4,6-trimethylphenyl group. 
     In a non-limiting embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-alkoxyphenyl group, or a 4-alkoxyphenyl group. In some non-limiting embodiments, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-methoxyphenyl group, a 2-ethoxyphenyl group, a 2-isopropoxyphenyl group, a 2-tert-butoxyphenyl group, a 4-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-isopropoxyphenyl group, or a 4-tert-butoxyphenyl group; alternatively, a 2-methoxyphenyl group, a 2-ethoxyphenyl group, a 2-isopropoxyphenyl group, or a 2-tert-butoxyphenyl group; or alternatively, a 4-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-isopropoxyphenyl group, or a 4-tert-butoxyphenyl group. 
     In a non-limiting embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-halophenyl group, a 4-halophenyl group, or a 2,6-dihalophenylgroup. Generally, the halides of a dihalophenyl group can be the same, or alternatively, the halides can be different. In some embodiments, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a phenyl group, a 2-fluorophenyl group, a 4-fluorophenyl group, or a 2,6-difluorophenyl group. 
     In an embodiment, each R 1s , R 2s , R 11s , R 12s , R 13s , and R 14s , when present in any heteroatomic ligand described herein, any heteroatomic ligand of the heteroatomic ligand chromium compound complex described herein, any heteroatomic ligand formula or structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein, independently can be a benzyl group or a substituted benzyl group; alternatively, a benzyl group; or alternatively, a substituted benzyl group. Each substituent of a substituted benzyl group (general or specific) independently can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen, alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens, substituent hydrocarbyl groups, and substituent hydrocarboxy groups can be utilized without limitation to further describe a substituted benzyl group (general or specific) which can be utilized as R 1s , R 2s , R 11s , R 12s , R 13s , and/or R 14s . 
     Generally, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be an organyl group; alternatively, an organyl group consisting of inert functional groups; or alternatively, a hydrocarbyl group. In an embodiment, the organyl group which can be utilized as R 5s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  organyl group. In an embodiment, the organyl group consisting of inert functional groups which can be utilized as R 5s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  organyl group consisting of inert functional groups. In an embodiment, the hydrocarbyl group which can be utilized as R 5s  can be a C 1  to C 20 , a C 1  to C 15 , a C 1  to C 10 , or a C 1  to C 5  hydrocarbyl group. 
     In an embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be an alkyl group, a substituted alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aryl group, a substituted aryl group, an aralkyl group, or a substituted aralkyl group. In some embodiments, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be an alkyl group or a substituted alkyl group; alternatively, a cycloalkyl group or a substituted cycloalkyl group; alternatively, an aryl group or a substituted aryl group; alternatively, an aralkyl group or a substituted aralkyl group; or alternatively, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. In other embodiments, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be an alkyl group; alternatively, a substituted alkyl group, alternatively, a cycloalkyl group; alternatively, a substituted cycloalkyl group; alternatively, an aryl group; alternatively, a substituted aryl group; alternatively, an aralkyl group; or alternatively, a substituted aralkyl group. 
     In any aspect or embodiment disclosed herein, the alkyl group which can be utilized as R 5s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  alkyl group. In any aspect or embodiment disclosed herein, the substituted alkyl group which can be utilized as R 5s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  substituted alkyl group. In any aspect or embodiment disclosed herein, the cycloalkyl group which can be utilized as R 5s  can be a C 4  to C 20 , a C 4  to C 15 , or a C 4  to C 10  cycloalkyl group. In any aspect or embodiment disclosed herein, the substituted cycloalkyl group which can be utilized as R 5s  can be a C 4  to C 20 , a C 4  to, or a C 4  to C 10  substituted cycloalkyl group. In any aspect or embodiment disclosed herein, the aryl group which can be utilized as R 5s  can be a C 6  to C 20 , a C 6  to C 15 , or a C 6  to C 10  aryl group. In any aspect or embodiment disclosed herein, the substituted aryl group which can be utilized as R 5s  can be a C 6  to C 20 , a C 6  to C 15 , or a C 6  to C 10  substituted aryl group. In any aspect or embodiment disclosed herein, each aralkyl group which can be utilized as R 5s  can be a C 7  to C 20 , a C 7  to C 15 , or a C 7  to C 10  aralkyl group. In any aspect or embodiment disclosed herein, the substituted aryl group which can be utilized as R 5s  can be a C 7  to C 20 , a C 7  to C 15 , or a C 7  to C 10  substituted aralkyl group. Each substituent of a substituted alkyl group (general or specific), substituted cycloalkyl group (general or specific), substituted aryl group (general or specific), and/or substituted aralkyl group (general or specific) can be a halogen, hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxyl group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently disclosed herein. These substituent halogens, substituent hydrocarbyl groups, and substituent hydrocarboxy groups can be utilized without limitation to further describe a substituted group (general or specific) which can be utilized R 5s . 
     In an embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group; alternatively, a methyl group, an ethyl group, an n-propyl (1-propyl) group, an isopropyl (2-propyl) group, an n-butyl (1-butyl) group, a sec-butyl (2-butyl) group, an isobutyl (2-methyl-1-propyl) group, a tert-butyl (2-methyl-2-propyl) group, an n-pentyl (1-pentyl) group, a 2-pentyl group, a 3-pentyl group, a 2-methyl-1-butyl group, a tert-pentyl (2-methyl-2-butyl) group, a 3-methyl-1-butyl group, a 3-methyl-2-butyl group, or a neo-pentyl (2,2-dimethyl-1-propyl) group; alternatively, a methyl group, an ethyl group, an iso-propyl (2-propyl) group, a tert-butyl (2-methyl-2-propyl) group, or a neopentyl (2,2-dimethyl-1-propyl) group; alternatively, a methyl group; alternatively, an ethyl group; alternatively, a n-propyl (1-propyl) group; alternatively, an iso-propyl (2-propyl) group; alternatively, a tert-butyl (2-methyl-2-propyl) group; or alternatively, a neopentyl (2,2-dimethyl-1-propyl) group. In some embodiments, the alkyl groups which can be utilized as R 5s  can be substituted. Each substituent of a substituted alkyl group independently can be a halogen or a hydrocarboxy group; alternatively, a halogen; or alternatively, a hydrocarboxy group. Substituent halogens and substituent hydrocarboxy groups (general and specific) are independently described herein and these substituent groups can be utilized without limitation to further describe a substituted alkyl group (general or specific) which can be utilized as R 5s . 
     In an embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a cyclopentyl group, a substituted cyclopentyl group, a cyclohexyl group, a substituted cyclohexyl group; alternatively, a cyclopentyl group or a substituted cyclopentyl group; alternatively, a cyclohexyl group or a substituted cyclohexyl group; alternatively, a cyclopentyl group; alternatively, a substituted cyclopentyl group; alternatively, a cyclohexyl group; or alternatively, a substituted cyclohexyl group. In further embodiments, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a 2-substituted cyclohexyl group, a 2,6-disubstituted cyclohexyl group, a 2-substituted cyclopentyl group, or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group or a 2,6-disubstituted cyclohexyl group; alternatively, a 2-substituted cyclohexyl group or a 2,6-disubstituted cyclohexyl group; alternatively, a 2-substituted cyclopentyl group or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group or a 2-substituted cyclopentyl group; alternatively, a 2,6-disubstituted cyclohexyl group or a 2,6-disubstituted cyclopentyl group; alternatively, a 2-substituted cyclohexyl group; alternatively, a 2,6-disubstituted cyclohexyl group; alternatively, a 2-substituted cyclopentyl group; or alternatively, a 2,6-disubstituted cyclopentyl group. In an embodiment, one or more substituents of a multi-substituted cycloalkyl group utilized as R 5s  can be the same or different; alternatively, all the substituents of a multi-substituted cycloalkyl group can be the same; or alternatively, all the substituents of a multi-substituted cycloalkyl group can be different. Each substituent of a cycloalkyl group (general or specific) having a specified number of ring carbon atoms independently can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently described herein and these substituent groups can be utilized without limitation to further describe a substituted cycloalkyl group (general or specific) which can be utilized as R 5s . 
     In a non-limiting embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a cyclohexyl group, a 2-alkylcyclohexyl group, or a 2,6-dialkylcyclohexyl group; alternatively, a cyclopentyl group, a 2-alkylcyclopentyl group, or a 2,5-dialkylcyclopentyl group; alternatively, a cyclohexyl group; alternatively, a 2-alkylcyclohexyl group; alternatively, a 2,6-dialkylcyclohexyl group; alternatively, a cyclopentyl group; alternatively, a 2-alkylcyclopentyl group; or alternatively, a 2,5-dialkylcyclopentyl group. Alkyl substituent groups (general and specific) are independently described herein and these alkyl substituent groups can be utilized, without limitation, to further describe alkylcyclohexyl groups (general or specific), dialkylcyclohexyl groups (general or specific), alkylcyclopentyl groups (general or specific), and/or dialkylcyclopentyl groups (general or specific) which can be utilized as R 5 ′. Generally, the alkyl substituents of a disubstituted cyclohexyl or cyclopentyl group can be the same, or alternatively, the alkyl substituents can be different. In some non-limiting embodiments, R 5s  heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a 2-methylcyclohexyl group, a 2-ethylcyclohexyl group, a 2-isopropylcyclohexyl group, a 2-tert-butylcyclohexyl group, a 2,6-dimethylcyclohexyl group, a 2,6-diethylcyclohexyl group, a 2,6-diisopropylcyclohexyl group, or a 2,6-di-tert-butylcyclohexyl group. In other non-limiting embodiments, R 5s  can be a 2-methylcyclohexyl group, a 2-ethylcyclohexyl group, a 2-isopropylcyclohexyl group, or a 2-tert-butylcyclohexyl group; or alternatively, a 2,6-dimethylcyclohexyl group, a 2,6-diethylcyclohexyl group, a 2,6-diisopropylcyclohexyl group, or a 2,6-di-tert-butylcyclohexyl group. In an embodiment, R 5s  heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a cyclopentyl group, a 2-methylcyclopentyl group, a cyclohexyl group, or a 2-methylcyclohexyl group; alternatively, a cyclopentyl group or a cyclohexyl group; or alternatively, a 2-methylcyclopentyl group or a 2-methylcyclohexyl group. 
     In an embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a phenyl group or a substituted phenyl group; alternatively, a phenyl group; or alternatively, a substituted phenyl group. In some embodiments, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a 2-substituted phenyl group, a 4-substituted phenyl group, a 2,4-disubstituted phenyl group, a 2,6-disubstituted phenyl group, or a 2,4,6-trisubstituted phenyl group; alternatively, a 2-substituted phenyl group or a 4-substituted phenyl group; alternatively, a 2,4-disubstituted phenyl group, a 2,6-disubstituted phenyl group, or a 2,4,6-trisubstituted phenyl group; alternatively, a 2,4-disubstituted phenyl group or a 2,6-disubstituted phenyl group; alternatively, a 2-substituted phenyl group; alternatively, a 4-substituted phenyl group; alternatively, a 2,4-disubstituted phenyl group; alternatively, a 2,6-disubstituted phenyl group; or alternatively, a 2,4,6-trisubstituted phenyl group. In an embodiment, one or more substituents of a multi-substituted phenyl group utilized as R 5s  can be the same or different; alternatively, all the substituents can be the same, or alternatively, all the substituents can be different. Each substituent of a substituted phenyl group (general or specific) independently can be a halogen, a hydrocarbyl group, or a hydrocarboxy group; alternatively, a halogen or a hydrocarbyl group; alternatively, a halogen or a hydrocarboxy group; alternatively, a hydrocarbyl group or a hydrocarboxy group; alternatively, a halogen; alternatively, a hydrocarbyl group; or alternatively, a hydrocarboxy group. Substituent halogens, substituent hydrocarbyl groups (general and specific), and substituent hydrocarboxy groups (general and specific) are independently described herein and these substituent groups can be utilized without limitation to further describe a substituted phenyl group (general or specific) which can be utilized as less. 
     In a non-limiting embodiment, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a phenyl group, a 2-alkylphenyl group, a 4-alkylphenyl group, a 2,4-dialkylphenyl group, a 2,6-dialkylphenyl group, or a 2,4,6-trialkylphenyl group; alternatively, a 2-alkylphenyl group, a 2,4-dialkylphenyl group, a 2,6-dialkylphenyl group, or a 2,4,6-trialkylphenyl group. Alkyl substituent groups (general and specific) are independently described herein and these alkyl substituent groups can be utilized, without limitation, to further describe any alkyl substituted phenyl group which can be utilized as R 5s . Generally, the alkyl substituents of dialkylphenyl groups (general of specific) or trialkylphenyl groups (general or specific) can be the same, or alternatively, the alkyl substituents can be different. In some non-limiting embodiments, R 5s  of any organylene L 1s  group disclosed herein, any amin-di-yl group disclosed herein, any phosphin-di-yl group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein can be a phenyl group, a 2-methylphenyl group, a 2-ethylphenyl group, a 2-n-propylphenyl group, a 2-isopropylphenyl group, a 2-tert-butylphenyl group, a 2,6-dimethylphenyl group, a 2,6-diethylphenyl group, a 2,6-di-n-propylphenyl group, a 2,6-diisopropylphenyl group, a 2,6-di-tert-butylphenyl group, a 2-isopropyl-6-methylphenyl group, or a 2,4,6-trimethylphenyl group; alternatively, a phenyl group, a 2-methylphenyl group, a 2,6-dimethylphenyl group, or a 2,4,6-trimethylphenyl group. 
     Generally, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be an organylene group; alternatively, an organylene group consisting of inert functional groups; or alternatively, a hydrocarbylene group. In an embodiment, the organylene group which can be utilized as L 2s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  organylene group. In an embodiment, the organylene group consisting of inert functional groups which can be utilized as L 2s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  organylene group consisting of inert functional groups. In an embodiment, the hydrocarbylene group which can be utilized as L 2s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  hydrocarbylene group. In an embodiment, L 1s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be a C 1  to C 20 , C 1  to C 15 , or a C 1  to C 10  alkylene group. 
     In an embodiment, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be —(CR P R P ) m — where each R P  and R P′  can independently be hydrogen, methyl, ethyl, propyl, isopropyl, or butyl groups and m can be an integer from 1 to 12. In some embodiments, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be a methylene group (—CH 2 —), an ethylene group (—CH 2 CH 2 —), a propylene group (—CH 2 CH 2 CH 2 —), a —CH(CH 3 )CH 2 — group, —C(CH 3 ) 2 — group, a butylene group (—CH 2 CH 2 CH 2 —CH 2 —), or a —CH 2 CH(CH 3 )—CH 2 — group. In other embodiments, L 1s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be a methylene group (—CH 2 —), an ethylene group (—CH 2 CH 2 —), or a —CH(CH 3 )CH 2 -group; alternatively, a methylene group(—CH 2 —); alternatively, an ethylene group (—CH 2 CH 2 —); alternatively, a propylene group (—CH 2 CH 2 CH 2 —); alternatively, a —CH(CH 3 )CH 2 — group; alternatively, a —C(CH 3 ) 2 — group; or alternatively, a —CH 2 CH(CH 3 )—CH 2 — group. 
     In an embodiment, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be 1,2-cyclohexylene, a substituted 1,2-cyclohexylene, 1,3-cyclohexylene, a substituted 1,3-cyclohexylene, 1,4-cyclohexylene, a substituted 1,4-cyclohexylene, 3,3′-bicyclohexylene, a substituted 3,3′-bicyclohexylene, 4,4′-bicyclohexylene, a substituted 4,4′-bicyclohexylene, bis(3-cyclohexylene)methane, a substituted bis(3-cyclohexylene)methane, bis(4-cyclohexylene)methane, a substituted bis(4-cyclohexylene)methane, 1,2-bis(3-cyclohexylene)ethane, a substituted 1,2-bis(3-cyclohexylene)ethane, 1,2-bis(4-cyclohexylene)-ethane, a substituted 1,2-bis(4-cyclohexylene)ethane, 1,2-bis(3-cyclohexylene)propane, a substituted 1,2-bis(3-cyclohexylene)propane, 1,2-bis(4-cyclohexylene)propane, a substituted 1,2-bis(4-cyclohexylene)-propane, 2,2-bis(3-cyclohexylene)propane, a substituted 2,2-bis(3-cyclohexylene)propane, 2,2-bis(4-cyclohexylene)propane, or a substituted 2,2-bis(4-cyclohexylene)propane. In some embodiments, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be a substituted 1,2-cyclohexylene, a substituted 1,3-cyclohexylene, a substituted 1,4-cyclohexylene, a substituted 3,3′-bicyclohexylene, a substituted 4,4′-bicyclohexylene, a substituted bis(3-cyclohexylene)methane, a substituted bis(4-cyclohexylene)methane, a substituted 1,2-bis(3-cyclohexylene)ethane, a substituted 1,2-bis(4-cyclohexylene)ethane, a substituted 1,2-bis(3-cyclohexylene)propane, a substituted 1,2-bis(4-cyclohexylene)propane, a substituted 2,2-bis(3-cyclohexylene)propane, or a substituted 2,2-bis(4-cyclohexylene)propane. In an embodiment, each substituent of a substituted cyclohexylene, a substituted bis(cyclohexylene)methane, a substituted bis(cyclohexylene)ethane, or a substituted 1,2-bis(3-cyclohexylene)propane which can be utilized as L 2s  can be a hydrocarbyl group. Substituent groups (general and specific) are independently disclosed herein and can be utilized without limitation to further describe a substituted cyclohexylene (general or specific), a substituted bis(cyclohexylene)methane (general or specific), a substituted bis(cyclohexylene)ethane (general or specific), or a substituted 1,2-bis(3-cyclohexylene)propane (general or specific) which can be utilized as L 2s . 
     In an embodiment, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be 1,2-phenylene, a substituted 1,2-phenylene, 1,3-phenylene, a substituted 1,3-phenylene, 1,4-phenylene, a substituted 1,4-phenylene, 3,3′-biphenylene, a substituted 3,3′-biphenylene, 4,4′-biphenylene, a substituted 4,4′-biphenylene, bis(3-phenylene)methane, a substituted bis(3-phenylene)methane, bis(4-phenylene)methane, a substituted bis(4-phenylene)methane, 1,2-bis(3-phenylene)ethane, a substituted 1,2-bis(3-phenylene)ethane, 1,2-bis(4-phenylene)ethane, a substituted 1,2-bis(4-phenylene)ethane, 1,2-bis(3-phenylene)propane, a substituted 1,2-bis(3-phenylene)propane, 1,2-bis(4-phenylene)propane, a substituted 1,2-bis(4-phenylene)propane, 2,2-bis(3-phenylene)propane, a substituted 2,2-bis(3-phenylene)propane, 2,2-bis(4-phenylene)propane, or a substituted 2,2-bis(4-phenylene)propane. In some embodiments, L 2s  of the heteroatomic ligand having Structure PNP2 and/or the heteroatomic ligand chromium compound complex having Structure PNPCr2 can be a substituted 1,2-phenylene, a substituted 1,3-phenylene, a substituted 1,4-phenylene, a substituted 3,3′-biphenylene, a substituted 4,4′-biphenylene, a substituted bis(3-phenylene)methane, a substituted bis(4-phenylene)methane, a substituted 1,2-bis(3-phenylene)ethane, a substituted 1,2-bis(4-phenylene)ethane, a substituted 1,2-bis(3-phenylene)propane, a substituted 1,2-bis(4-phenylene)propane, a substituted 2,2-bis(3-phenylene)propane, or a substituted 2,2-bis(4-phenylene)propane. In an embodiment, each substituent of a substituted phenylene (general or specific), a substituted biphenylene (general or specific), a substituted bis(phenylene)methane (general or specific), a substituted bis(phenylene)ethane (general or specific), and/or a substituted bis(phenylene)propane (general or specific) which can be utilized as L 2s  can be a hydrocarbyl group. Substituent hydrocarbyl groups (general and specific) are independently disclosed herein and can be utilized without limitation to further describe a substituted phenylene (general or specific), a substituted biphenylene (general or specific), a substituted bis(phenylene)methane (general or specific), a substituted bis(phenylene)ethane(general or specific), and/or a substituted bis(phenylene)propane (general or specific) which can be utilized as L 2 ′. 
     Generally, L 3s  and L 4s  of any organylene L 1s  group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein independently can be an organylene group; alternatively, an organylene group consisting of inert functional groups; or alternatively, a hydrocarbylene group. In an embodiment, the organylene group which can be utilized as L 3s  and/or L 4s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  organylene group. In an embodiment, the organylene group consisting of inert functional groups which can be utilized as L 3s  and/or L 4s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  organylene group consisting of inert functional groups. In an embodiment, the hydrocarbylene group which can be utilized as L 3s  and/or L 4s  can be a C 1  to C 20 , a C 1  to C 15 , or a C 1  to C 10  hydrocarbylene group. In an embodiment, L 3s  and L 4s  of any organylene L 1s  group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein independently can be a C 1  to C 20 , C 1  to C 15 , or a C 1  to C 10  alkylene group. 
     In an embodiment, L 3s  and L 4s  of any organylene L 1s  group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein independently can be —(CR P R P′ ) m — where each R P  and R P′  can independently be hydrogen, methyl, ethyl, propyl, isopropyl, or butyl groups and m can be an integer from 1 to 12. In some embodiments, L 3s  and L 4s  of any organylene L 1s  group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein independently can be a methylene group (—CH 2 —), an eth-1,2-ylene group (—CH 2 CH 2 —), an ethen-1,2-ylene group (—CH═CH—), a prop-1,3-ylene group (—CH 2 CH 2 CH 2 —), a prop-1,2-ylene group (—CH(CH 3 )CH 2 —), a prop-2,2-ylene group (—C(CH 3 ) 2 —), a 1-methylethen-1,2-ylene group (—C(CH 3 )═CH—), a but-1,4-ylene group (—CH 2 CH 2 CH 2 —CH 2 —), a but-1,3-ylene group (—CH 2 CH 2 CH(CH 3 )—), a but-2,3-ylene group (—CH(CH 3 )CH(CH 3 )—), a but-2-en-2,3-ylene group (—C(CH 3 )C(CH 3 )—), a 3-methylbut-1,3-ylene group (—CH 2 CH 2 C(CH 3 ) 2 —), a 1,2-cyclopentylene group, a 1,2-cyclohexylene group, or a phen-1,2-ylene group; alternatively, a methylene group (—CH 2 —), an eth-1,2-ylene group (—CH 2 CH 2 —), a prop-1,3-ylene group (—CH 2 CH 2 CH 2 —), a prop-1,2-ylene group (—CH(CH 3 )CH 2 —), a prop-2,2-ylene group (—C(CH 3 ) 2 —), a but-1,4-ylene group (—CH 2 CH 2 CH 2 —CH 2 —), a but-1,3-ylene group (—CH 2 CH 2 CH(CH 3 )—), a but-2,3-ylene group (—CH(CH 3 )CH(CH 3 )—), a 1,2-cyclopentylene group, a 1,2-cyclohexylene group, or a phen-1,2-ylene group; alternatively, an eth-1,2-ylene group (—CH 2 CH 2 —), a prop-1,3-ylene group (—CH 2 CH 2 CH 2 —), a prop-1,2-ylene group (—CH(CH 3 )CH 2 —), a but-1,3-ylene group (—CH 2 CH 2 CH(CH 3 )—), a but-2,3-ylene group (—CH(CH 3 )CH(CH 3 )—), a 1,2-cyclopentylene group, a 1,2-cyclohexylene group, or a phen-1,2-ylene group. In some embodiments, L 3 s and  Los  of any organylene L 1s  group disclosed herein, any heteroatomic ligand structure provided herein, and/or any heteroatomic ligand chromium compound complex structure provided herein independently can be an eth-1,2-ylene group (—CH 2 CH 2 —); alternatively, a prop-1,3-ylene group (—CH 2 CH 2 CH 2 —); alternatively, a prop-1,2-ylene group (—CH(CH 3 )CH 2 —); alternatively, a but-1,3-ylene group (—CH 2 CH 2 CH(CH 3 )—); alternatively, a but-2,3-ylene group (—CH(CH 3 )CH(CH 3 )—); alternatively, a 1,2-cyclopentylene group; alternatively, a 1,2-cyclohexylene group; or alternatively, a phen-1,2-ylene group. 
     While not shown, one of ordinary skill in the art will recognize that a neutral ligand can be associated with the chromium compounds or heteroatomic ligand chromium compound complexes described herein. Additionally it should be understood that while chromium compounds or heteroatomic ligand chromium compound complexes provided herein do not formally show the presence of a neutral ligand, the chromium compounds or heteroatomic ligand chromium compound complexes having neural ligands (e.g., nitriles and ethers, among others) are fully contemplated as potential chromium compounds or heteroatomic ligand chromium compound complexes that can be utilized in the catalyst system used in aspects and embodiments of the herein described inventions. 
     In a non-limiting embodiment, the heteroatomic ligand can be any one or more of HL 1, HL 2, HL 3, HL 4. HL 5, HL 6, HL 7, HL 7, and HL 9. In some non-limiting embodiments, the diphosphino amine transition metal compound complex can be a chromium compound complex of any one or more of HLCr 1, HLCr 2, HLCr 3, HLCr 4, HLCr 5, HLCr 6, HLCr 7, HLCr 8, and HLCr 9. In other non-limiting embodiments, the diphosphino amine transition metal compound complex can be a chromium(III) chloride or chromium(III) acetylacetonate complex of any one or more of HLCr 1, HLCr 2, HLCr 3, HLCr 4, HLCr 5, HLCr 6, HLCr 7, HLCr 8, and HLCr 9. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Generally, the aluminoxane utilized in the catalyst systems which are utilized in the processes, systems, and/or reaction systems disclosed herein can be any aluminoxane which can, in conjunction with the chromium compound complexes and the heteroatomic ligand or alternatively the heteroatomic ligand chromium compound complex, catalyze the formation of an ethylene oligomer product. In a non-limiting embodiment, the aluminoxane can have a repeating unit characterized by the Formula I: 
                         
wherein R′ is a linear or branched alkyl group. Alkyl groups for metal alkyl compounds are independently described herein and can be utilized without limitation to further describe the aluminoxanes having Formula I. Generally, n of Formula I can be greater than 1; or alternatively, greater than 2. In an embodiment, n can range from 2 to 15; or alternatively, range from 3 to 10.
 
     In an aspect, each alkyl group of the aluminoxane independently can be, comprise, or consist essentially of, a C 1  to C 20  alkyl group; alternatively, a C 1  to C 10  alkyl group; or alternatively, a C 1  to C 6  alkyl group. In an embodiment, each alkyl group of the aluminoxane independently can be, comprise, or consist essentially of, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group; alternatively, a methyl group, a ethyl group, a butyl group, a hexyl group, or an octyl group. In some embodiments, each alkyl group or the aluminoxane independently can be, comprise, or consist essentially of, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an iso-butyl group, an n-hexyl group, or an n-octyl group; alternatively, a methyl group, an ethyl group, an n-butyl group, or an iso-butyl group; alternatively, a methyl group; alternatively, an ethyl group; alternatively, an n-propyl group; alternatively, an n-butyl group; alternatively, an iso-butyl group; alternatively, an n-hexyl group; or alternatively, an n-octyl group. 
     In a non-limiting embodiment, the aluminoxane can be, comprise, or consist essentially of, methylaluminoxane (MAO), ethylaluminoxane, modified methylaluminoxane (MMAO), n-propylaluminoxane, iso-propyl-aluminoxane, n-butylaluminoxane, sec-butylaluminoxane, iso-butylaluminoxane, t-butylaluminoxane, 1-pentyl-aluminoxane, 2-entylaluminoxane, 3-pentyl-aluminoxane, iso-pentyl-aluminoxane, neopentylaluminoxane, or mixtures thereof. In some non-limiting embodiments, the aluminoxane can be, comprise, or consist essentially of, methylaluminoxane (MAO), modified methylaluminoxane (MMAO), isobutyl aluminoxane, t-butyl aluminoxane, or mixtures thereof. In other non-limiting embodiments, the aluminoxane can be, comprise, or consist essentially of, methylaluminoxane (MAO); alternatively, ethylaluminoxane; alternatively, modified methylaluminoxane (MMAO); alternatively, n-propylaluminoxane; alternatively, iso-propyl-aluminoxane; alternatively, n-butylaluminoxane; alternatively, sec-butylaluminoxane; alternatively, iso-butylaluminoxane; alternatively, t-butyl aluminoxane; alternatively, 1-pentyl-aluminoxane; alternatively, 2-pentylaluminoaxne; alternatively, 3-pentyl-aluminoxane; alternatively, iso-pentyl-aluminoxane; or alternatively, neopentylaluminoxane. 
     The scrub agent which can be utilized in aspects and embodiments of any of the processes, systems, and/or reaction systems described herein can be any compound(s) which can remove water, oxygen, and/or other species detrimental to the ability of the catalyst system to oligomerize ethylene. In some embodiments, the scrub agent can be an organoaluminum compound. In an embodiment, the organoaluminum compound can be an alkylaluminum compound. In an embodiment, the alkylaluminum compound can be a trialkylaluminum, an alkylaluminum halide, an alkylaluminum alkoxide, or any combination thereof. In some embodiments, the alkylaluminum compound can be a trialkylaluminum, an alkylaluminum halide, or any combination thereof; alternatively, a trialkylaluminum, an alkylaluminum halide, or any combination thereof; or alternatively, a trialkylaluminum. In other embodiments, the alkylaluminum compound can be a trialkylaluminum; alternatively, an alkylaluminum halide; or alternatively, an alkylaluminum alkoxide. In yet other embodiments, the alkylaluminum compound which can be utilized as the scrub agent can be an aluminoxane (described herein). In a non-limiting embodiment, the trialkylaluminum compound can be, comprise, or consist essentially of, trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, or mixtures thereof. In some non-limiting embodiments, the trialkylaluminum compound can be, comprise, or consist essentially of, trimethylaluminum, triethylaluminum, tripropylaluminum, tri-n-butylaluminum, tri-isobutylaluminum, trihexylaluminum, tri-n-octylaluminum, or mixtures thereof; alternatively, triethylaluminum, tri-n-butylaluminum, tri-isobutylaluminum, trihexylaluminum, tri-n-octylaluminum, or mixtures thereof; alternatively, triethylaluminum, tri-n-butylaluminum, trihexylaluminum, tri-n-octylaluminum, or mixtures thereof. In other non-limiting embodiments, the trialkylaluminum compound can be, comprise, or consist essentially of, trimethylaluminum; alternatively, triethylaluminum; alternatively, tripropylaluminum; alternatively, tri-n-butylaluminum; alternatively, tri-isobutylaluminum; alternatively, trihexylaluminum; or alternatively, tri-n-octylaluminum. In a non-limiting embodiment, the alkylaluminum halide can be, comprise, or consist essentially of, diethylaluminum chloride, diethylaluminum bromide, ethylaluminum dichloride, ethylaluminum sesquichloride, or mixtures thereof. In some non-limiting embodiments, the alkylaluminum halide can be, comprise, or consist essentially of, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, or mixtures thereof. In other non-limiting embodiments, the alkylaluminum halide can be, comprise, or consist essentially of, diethylaluminum chloride; alternatively, diethylaluminum bromide; alternatively, ethylaluminum dichloride; or alternatively, ethylaluminum sesquichloride. In particular aspects of this invention, the organoaluminum compound can comprise trimethylaluminum (TMA), triethylaluminum (TEA), tri-n-propylaluminum (TNPA), tri-n-butylaluminum (TNBA), triisobutylaluminum (TIBA), tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminum chloride, or combinations thereof. 
     In an embodiment, the alkylaluminum compound which can be utilized as the scrub agent can be an aluminoxane. Aluminoxanes are independently disclosed herein (e.g., as a component of the catalyst system) and any of the general or specific aluminoxanes disclosed herein can be utilized without limitation as the scrub agent utilized in the processes, systems and/or reaction systems disclosed herein. 
     The herein described scrub agent optionally can be indirectly introduced to the reaction zone  110  from a scrub agent source  170  via feed line  172 . The scrub agent feed line  172 , when present in system  100 ,  200 , or  300 , is defined as having at least one scrub agent. 
     Generally, the ethylene oligomer product that can be produced using the processes, systems, and/or reaction system described herein can be formed at conditions (or alternatively, the reaction zone  110  can have any conditions) which can 1) facilitate ethylene oligomer product formation, 2) provide a desired ethylene oligomer product formation rate, 3) provide acceptable catalyst system productivity, 4) provide acceptable oligomer selectivity, and/or 5) provide acceptable polymer formation. In an embodiment, conditions under which the ethylene oligomer product can be formed (or alternatively, the reaction zone can have any conditions) can include one or more of catalyst system component ratios, chromium concentration, pressure, ethylene partial pressure, ethylene concentration, presence of hydrogen (and its partial pressure and/or hydrogen to ethylene weight ratio), temperature, reaction time, single pass ethylene conversion, and catalyst system productivity. Catalyst system component ratios, chromium concentration, pressure, ethylene partial pressure, ethylene concentration, presence of hydrogen (and its partial pressure and/or hydrogen to ethylene weight ratio), temperature, reaction time, single pass ethylene conversion, and catalyst system productivity are independently described herein and these independent descriptions can be used without limitation and in any combination to describe the process, system, or reaction zone conditions at which the ethylene oligomer product can be formed for any of the processes, systems, and/or reaction systems described herein. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum aluminum of the aluminoxane to chromium of the chromium component (e.g., the chromium compound or the heteroatomic ligand chromium compound complex) molar ratio (i.e., minimum Al to Cr molar ratio) of 10:1, 50:1, 75:1, or 100:1; alternatively or additionally, at a maximum aluminum of the aluminoxane to chromium of the chromium component (e.g., the chromium compound or the heteroatomic ligand chromium compound complex) molar ratio (i.e., maximum Al to Cr molar ratio) of 5,000:1, 3,000:1, 2,000:1, 1,500:1, or 1,000:1. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at an Al to Cr molar ratio ranging from any minimum Al to Cr molar ratio disclosed herein to any maximum Al to Cr molar ratio disclosed herein. In a non-limiting embodiment, the Al to Cr molar ratio can range from 10:1 to 5,000:1, from 50:1 to 3,000:1, from 50:1 to 3,000:1, from 75:1 to 2,000:1, from 100:1 to 2,000:1, of from 100:1 to 1,000:1. Other Al to Cr molar ratio ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum heteroatomic ligand to chromium compound (either as the chromium compound of as the chromium compound of the heteroatomic ligand chromium compound complex) equivalent ratio (i.e., minimum heteroatomic ligand to Cr equivalent ratio) of 0.8:1, 0.9:1, or 0.95:1; alternatively or additionally, at a maximum heteroatomic ligand to chromium compound (either as the chromium compound of as the chromium compound of the heteroatomic ligand chromium compound complex) equivalent ratio (i.e., minimum heteroatomic ligand to Cr equivalent ratio) of 5:1, 4:1, 3:1, or 2.5:1. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at an heteroatomic ligand to Cr equivalent ratio ranging from any minimum heteroatomic ligand to Cr equivalent ratio disclosed herein to any maximum heteroatomic ligand to Cr equivalent ratio disclosed herein. In a non-limiting embodiment, the heteroatomic ligand to Cr molar ratio can range from 0.8:1 to 5:1, from 0.9:1 to 4:1, from 0.90:1 to 3:1, from 0.95:1 to 3:1, or from 0.95:1 to 2.5:1. Other heteroatomic ligand to Cr equivalent ratio ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum reaction zone chromium concentration of the chromium component (e.g., the chromium compound or the heteroatomic ligand chromium compound complex) concentration (i.e., minimum chromium concentration) of 1×10 −6  Cr equivalents/liter, 1×10 −5  Cr equivalents/liter, or 5×10 −4  Cr equivalents/liter; alternatively or additionally, at a maximum reaction zone chromium concentration of the chromium component (e.g., the chromium compound or the heteroatomic ligand chromium compound complex) of 1 Cr equivalents/liter, 5×10 −1  Cr equivalents/liter, or 1×10 −1  Cr equivalents/liter. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a reaction zone chromium concentration ranging from any minimum chromium concentration disclosed herein to any maximum chromium concentration disclosed herein. In a non-limiting embodiment, the reaction zone chromium concentration can range from 1×10 −6  Cr equivalents/liter to 1 Cr equivalents/liter, from 1×10 −5  Cr equivalents/liter to 5×10 −1  Cr equivalents/liter, from 5×10 −4  Cr equivalents/liter to 1×10 −1  Cr equivalents/liter. Other chromium concentration ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum pressure of 5 psi (34.5 kPa), 50 psi (345 kPa); 100 psi (689 kPa), 150 psi (1.03 MPa), 250 psi (1.72 MPa), 500 psi (3.5 MPa), or 600 psi (4.1 MPa); alternatively or additionally, at a maximum pressure of 2,500 psi (17.2 MPa), 2,000 psi (13.8 MPa), 1,500 psi (10.3 MPa), 1400 psi (9.65 MPa), 1250 psi (8.62 MPa), or 1000 psi (6.89 MPa). In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a pressure ranging from any minimum pressure disclosed herein to any maximum pressure disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at a pressure from 5 psi (34.5 kPa) to 2,500 psi (17.2 MPa), from 5 psi (34.5 kPa) to 2,000 psi (13.8 MPa), from 50 psi (345 kPa) to 2,000 psi (13.8 MPa), from 100 psi (689 kPa) to 2,000 psi (13.8 MPa), from 100 psi (689 kPa) to 1,500 psi (10.3 MPa), from 500 psi (3.5 MPa) to 1500 psi (10.3 MPa), from 150 psi (1.03 MPa) to 1250 psi (8.62 MPa), from 250 psi (1.72 MPa) to 1000 psig (6.89 MPa), or from 600 psi (4.1 MPa) to 1400 psi (9.65 MPa). Other pressure ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum ethylene partial pressure of 5 psi (34.5 kPa), 50 psi (345 kPa); 100 psi (689 kPa), 150 psi (1.03 MPa), 250 psi (1.72 MPa), or 500 psi (3.5 MPa); alternatively or additionally at a maximum ethylene partial pressure of 2,500 psi (17.2 MPa), 2,000 psi (13.8 MPa), 1,500 psi (10.3 MPa), 1250 psi (8.62 MPa), or 1000 psi (6.89 MPa). In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at an ethylene partial pressure ranging from any minimum ethylene partial pressure disclosed herein to any maximum ethylene partial pressure disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone  110  can operate) at an ethylene partial pressure from 5 psi (34.5 kPa) to 2,500 psi (17.2 MPa), from 5 psi (34.5 kPa) to 2,000 psi (13.8 MPa), from 50 psi (345 kPa) to 2,000 psi (13.8 MPa), from 100 psi (689 kPa) to 2,000 psi (13.8 MPa), from 100 psi (689 kPa) to 1,500 psi (10.3 MPa), from 500 psi (3.5 MPa) to 1500 psi (10.3 MPa), from 150 psi (1.03 MPa) to 1250 psi (8.62 MPa), from 150 psi (1.03 MPa) to 1250 psi (8.62 MPa), or from 250 psi (1.72 MPa) to 1000 psi (6.89 MPa). Other ethylene partial pressure ranges are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum ethylene concentration of 4 mass %, 10 mass %, 25 mass %, 35 mass %, or 40 mass % based upon the total mass in the reaction zone; alternatively or additionally, at a maximum ethylene concentration of 70 mass %, 65 mass %, 60 mass %, 55 mass %, 50 mass %, 48 mass % based upon the total mass in the reaction zone. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at an ethylene concentration ranging from any minimum ethylene concentration disclosed herein to any maximum ethylene concentration disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at an ethylene concentration from 4 mass % to 70 mass %, from 4 mass % to 60 mass %, from 10 mass % to 60 mass %, from 25 mass % to 55 mass %, 35 mass % to 50 mass %, or 40 mass % to 48 mass % based upon the total mass in the reaction zone. Other ethylene concentration ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum ethylene:chromium mass ratio of 50,000:1, 150,000:1, 250,000:1, or 400,000:1; alternatively or additionally, at a maximum ethylene:chromium mass ratio of 5,000,000:1, 2,500,000:1, 1,500,000:1, or 1,000,000:1. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at an ethylene:chromium mass ratio ranging from any minimum ethylene:chromium mass ratio disclosed herein to any maximum ethylene:chromium mass ratio disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at an ethylene:chromium mass ratio from 50,000:1 to 5,000,000:1, 150,000:1 to 2,500,000:1, 250,000:1 to 1,500,000:1, or 400,000:1 to 1,000,000:1. Other ethylene:chromium mass ratio ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment wherein hydrogen is utilized, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum hydrogen partial pressure of 1 psi (6.9 kPa), 2 psi (14 kPa); 5 psi (34 kPa), 10 psi (69 kPa), or 15 psi (103 kPa); alternatively or additionally at a maximum hydrogen partial pressure of 200 psi (1.4 MPa), 150 psi (1.03 MPa), 100 psi (689 kPa), 75 psig (517 kPa), or 50 psi (345 kPa). In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen partial pressure ranging from any minimum hydrogen partial pressure disclosed herein to any maximum hydrogen partial pressure disclosed herein. In some non-limiting embodiments wherein hydrogen is utilized, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen partial pressure from 1 psi (6.9 kPa) to 200 psi (1.4 MPa), from 5 psi (34 kPa) to 150 psi (1.03 MPa), from 10 psi (69 kPa) to 100 psi (689 kPa), or from 15 psi (100 kPa) to 75 psig (517 kPa). Other hydrogen partial pressure ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment wherein hydrogen is utilized, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum hydrogen to ethylene mass ratio of (0.05 g hydrogen)/(kg ethylene), (0.1 g hydrogen)/(kg ethylene), (0.25 g hydrogen)/(kg ethylene), (0.4 g hydrogen)/(kg ethylene), or (0.5 g hydrogen)/(kg ethylene); alternatively or additionally, at a maximum hydrogen to ethylene mass ratio can be (5 g hydrogen)/(kg ethylene), (3 g hydrogen)/(kg ethylene), (2.5 g hydrogen)/(kg ethylene), (2 g hydrogen)/(kg ethylene), or (1.5 g hydrogen)/(kg ethylene). In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen to ethylene mass ratio ranging from any minimum hydrogen to ethylene mass ratio disclosed herein to any maximum hydrogen to ethylene mass ratio disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen to ethylene mass ratio from (0.05 g hydrogen)/(kg ethylene) to (5 g hydrogen)/(kg ethylene), from (0.25 g hydrogen)/(kg ethylene) to (5 g hydrogen)/(kg ethylene), from (0.25 g hydrogen)/(kg ethylene) to (4 g hydrogen)/(kg ethylene), from (0.4 g hydrogen)/(kg ethylene) to (3 g hydrogen)/(kg ethylene), from (0.4 g hydrogen)/(kg ethylene) to (2.5 g hydrogen)/(kg ethylene), from (0.4 g hydrogen)/(kg ethylene) to (2 g hydrogen)/(kg ethylene), or from (0.5 g hydrogen)/(kg ethylene) to (2 g hydrogen)/(kg ethylene). Other hydrogen to ethylene mass ratio ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum hydrogen:chromium mass ratio of 1:1, 50:1, 100:1, or 200:1; alternatively or additionally at a maximum hydrogen:chromium mass ratio of 100,000:1, 50,000:1, 10,000:1, or 3,000:1. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen:chromium mass ratio ranging from any minimum hydrogen:chromium mass ratio disclosed herein to any maximum hydrogen:chromium mass ratio disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at a hydrogen:chromium mass ratio from 1:1 to 100,000:1, 50:1 to 50,000:1, 100:1 to 10,000:1, or 200:1 to 3,000:1. Other hydrogen:chromium mass ratio ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a minimum temperature of 0° C., 25° C., 40° C., or 50° C.; alternatively or additionally at a maximum temperature of 200° C., 150° C., 100° C., or 90° C. In an embodiment, the ethylene oligomer product can be formed (or the reaction zone can operate) at a temperature ranging from any minimum temperature disclosed herein to any maximum temperature disclosed herein. In some non-limiting embodiments, the ethylene oligomer product can be formed (or the reaction zone can operate) at a temperature from 0° C. to 200° C., from 25° C. to 150° C., from 40° C. to 100° C., from 50° C. to 100° C., or from 50° C. to 90° C. Other temperature ranges that can be utilized are readily apparent to those skilled in the art with the aid of this disclosure. 
     The reaction time (or residence time), for example, in the reaction zone can comprise any time that can produce the desired quantity of ethylene oligomer product; alternatively, any reaction time (or residence time) that can provide a desired catalyst system productivity; alternatively, any reaction time (or residence time) that can provide a desired ethylene conversion. Relating to forming the ethylene oligomer product, the ethylene oligomer product can be formed over a period of time (or an average time) that can produce the desired quantity of olefin product or polymer product, provide a desired catalyst system productivity, and/or provide a desired conversion of monomer. In some embodiments, the time can range from 1 minute to 5 hours; alternatively, ranges from 5 minutes to 2.5 hours; alternatively, ranges from 10 minutes to 2 hours; or alternatively, ranges from 15 minutes to 1.5 hours. In some embodiments (in continuous process embodiments), the reaction time (or residence time) can be stated as an average reaction time (or average residence time) and can range from 1 minute to 5 hours; alternatively, ranges from 5 minutes to 2.5 hours; alternatively, ranges from 10 minutes to 2 hours; or alternatively, ranges from 15 minutes to 1.5 hours. 
     In an embodiment, the processes, systems, and/or reaction systems described herein can have and ethylene conversion of at least 30%, 35%, 40%, or 45%. 
     In an embodiment, the processes, systems, and/or reactions systems described herein can have a catalyst system productivity of greater than 10,000, 50,000,100,000, 150,000, 200,000, 300,000, or 400,000 grams (C 6 +C 8 ) per gram of chromium. In some embodiments (but not necessarily all embodiments), the processes, systems, and/or reaction systems described herein can have a productivity higher than a productivity in an otherwise similar process which does not contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system; alternatively, does not introduce or feed the feedstock mixture into the reaction zone separately from the catalyst system; or alternatively, productivity higher than a productivity in an otherwise similar process which does not: i) contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system, and/or ii) introduce or feed the feedstock mixture into the reaction zone separately from the catalyst system. In an embodiment (but not all embodiments), the productivity can increased by 5%, 7.5%, 10%, or 12.5%. 
     In some aspects and embodiments (but not necessarily all aspects and/or embodiments), the processes, systems, and reaction systems described herein can produce less polymer per gram of ethylene oligomer product than an otherwise similar process which does not contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system; alternatively, does not introduce or feed the feedstock mixture into the reaction zone separately from the catalyst system; or alternatively, produce less polymer per gram of ethylene oligomer product than an otherwise similar process which does not: i) contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system, and/or ii) introduce or feed the feedstock mixture into the reaction zone, e.g., reaction zone  110 , separately from the catalyst system. In an embodiment (but not all embodiments), the mass of polymer per mass of oligomer in the reaction zone can decrease by 10%, 25%, 40%, 50%, 60%, 70%, or 80%. 
     Depending upon the catalyst system utilized, the processes, systems, and/or reaction systems described herein can be an ethylene oligomerization process, system, and/or reaction system, an ethylene trimerization process, system, or reaction system, an ethylene tetramerization process, system, or reaction system or an ethylene trimerization and tetramerization process system, or reaction system; alternatively, an ethylene oligomerization process system, or reaction system; alternatively, an ethylene trimerization process, system, or reaction system; alternatively, an ethylene tetramerization process, system, or reaction system; or alternatively an ethylene trimerization and tetramerization process, system, or reaction system. In an ethylene trimerization embodiment, the ethylene oligomer product can comprise at least 70 wt. % hexenes, at least 75 wt. % hexenes, at least 80 wt. % hexenes, at least 85 wt. % hexenes, or at least 90 wt. % hexene based upon the weight of the ethylene oligomer product. In some ethylene trimerization embodiments, the ethylene oligomer product can comprise from 70 wt. % to 99.8 wt. % hexenes, from 75 wt. % to 99.7 wt. % hexenes, or from 80 wt. % to 99.6 wt. % hexenes based upon the weight of the ethylene oligomer product. In an ethylene tetramerization embodiment, the ethylene oligomer product can comprise at least 70 wt. % octene, at least 75 wt. % octene, at least 80 wt. % octenes, at least 85 wt. % octenes, or at least 90 wt. % octenes based upon the weight of the ethylene oligomer product. In some ethylene tetramerization embodiments, the ethylene oligomer product can comprise from 70 wt. % to 99.8 wt. % octenes, from 75 wt. % to 99.7 wt. % octenes, or from 80 wt. % to 99.6 wt. % octenes based upon the weight of the ethylene oligomer product. In an ethylene trimerization and tetramerization embodiment, the ethylene oligomer product can comprise at least 70 wt. % hexenes and octenes, at least 75 wt. % hexenes and octenes, at least 80 wt. % hexenes and octenes, at least 85 wt. % hexene and octene, or at least 90 wt. % hexenes and octenes based upon the weight of the ethylene oligomer product. In some ethylene trimerization and tetramerization embodiments, the ethylene oligomer product can comprise from 70 wt. % to 99.8 wt. % hexenes and octenes, from 75 wt. % to 99.7 wt. % hexenes and octenes, or from 80 wt. % to 99.6 wt. % hexenes and octenes based upon the weight of the ethylene oligomer product. 
     In ethylene oligomerization, ethylene trimerization, or ethylene trimerization and tetramerization embodiments, the ethylene trimer can comprise at least 85 wt. % 1-hexene; alternatively, at least 87.5 wt. % 1-hexene; alternatively, at least 90 wt. % 1-hexene; alternatively, at least 92.5 wt. % 1-hexene; alternatively, at least 95 wt. % 1-hexene; alternatively, at least 97 wt. % 1-hexene; or alternatively, at least 98 wt. % 1-hexene by weight of the ethylene trimer, or from 85 wt. % to 99.9 wt. % 1-hexene; alternatively, from 87.5 wt. % to 99.9 wt. % 1-hexene; alternatively, from 90 wt. % to 99.9 wt. % 1-hexene; alternatively, from 92.5 wt. % to 99.9 wt. % 1-hexene; alternatively, from 95 wt. % to 99.9 wt. % 1-hexene; alternatively, from 97 wt. % to 99.9 wt. % 1-hexene; or alternatively, from 98 wt. % to 99.9 wt. % 1-hexene by weight of the ethylene trimer. 
     In ethylene oligomerization, ethylene tetramerization, or ethylene trimerization and tetramerization embodiments, the ethylene tetramer can comprise at least 85 wt. % 1-octene; alternatively, at least 87.5 wt. % 1-octene; alternatively, at least 90 wt. % 1-octene; alternatively, at least 92.5 wt. % 1-octene; alternatively, at least 95 wt. % 1-octene; alternatively, at least 97 wt. % 1-octene; or alternatively at least 98 wt. % 1-octene by weight of the ethylene tetramer or from 85 wt. % to 99.9 wt. % 1-octene; alternatively, from 87.5 wt. % to 99.9 wt. % 1-octene; alternatively, from 90 wt. % to 99.9 wt. % 1-octene; alternatively, from 92.5 wt. % to 99.9 wt. % 1-octene; alternatively, from 95 wt. % to 99.9 wt. % 1-octene; alternatively, from 97 wt. % to 99.9 wt. % 1-octene; or alternatively, from 98 wt. % to 99.9 wt. % 1-octene by weight of the ethylene tetramer. 
     The processes, systems, and/or reaction systems described herein can provide various advantages. Without being limited to theory, it is believed that the presence of a C 3+  olefin during the initial startup of oligomerization processes, systems, and/or reaction systems can decrease the mass of polymer during the startup of a selective oligomerization process, system, and/or reaction system. This reduction in the mass of polymer during startup of oligomerization processes, systems, and/or reaction systems described herein can lead to improved process, system, and/or reaction system operability and/or productivity. Another source of polymer formation can result when high concentrations of ethylene contact the catalyst system. The processes, systems, and/or reaction systems (e.g., reaction systems  100 ,  200 , and/or  300 ) described herein can reduce the amount of polymer formed by the use of a C 3+  olefin during the initial stages of ethylene oligomerization and/or contacting ethylene with at least a portion of the organic reaction medium prior to ethylene contacting the catalyst system. For example, the mass of undesirable polymer (e.g., polyethylene in contrast to desired oligomers of ethylene) per mass of oligomer formed in the reaction zone (e.g., reaction zone  110  in systems  100 ,  200 , and  300 ) can be less than a mass of polymer per mass of oligomer in the reaction zone of otherwise similar processes, systems, and/or reaction systems where the reaction zone C 3+  olefin:ethylene weight ratio does not decrease over the period of time. 
     Additionally, the mass of polymer (e.g., polyethylene in contrast to desired oligomers of ethylene) per mass of oligomer in the reaction zone (e.g., reaction zone  110  the processes, systems, and/or reactions systems (e.g., reaction system  200  and  300 ) can be less than a mass of polymer per mass of oligomer in the reaction zone of otherwise similar systems or process which do not include contacting ethylene with at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst systems disclosed herein. The mass of polymer per mass of oligomer in the reaction zone (e.g., reaction zone  110 ) for the processes, systems, and/or reaction systems (e.g., reaction systems  200  and  300 ) can be less than a mass of polymer per mass of oligomer in the reaction zone of an otherwise similar system or process which does not introduce or feed the feedstock mixture to the reaction zone separately from the catalyst systems disclosed herein. 
     Additionally, the productivity of the processes, system, and/or reaction systems (e.g., reaction systems  100 ,  200 , and  300 ) can be higher than other similar processes, systems, and/or reaction system where the C 3+  olefin is not introduced to the reaction zone  110  and/or ethylene is introduced into the reaction zone  110  which does not contain C 3+  olefin. Productivity is defined as the mass of liquid ethylene oligomer product (or alternatively, C 6  product, C 8  product, or (C 6 +C 8 ) product) formed per mass of chromium or aluminum. 
     Additionally, the productivity of the processes, systems, and/or reaction systems (e.g., reaction systems  200  and  300 ) and processes, systems, and/or reaction systems can be greater than other similar systems and processes which do not contact ethylene with at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst systems disclosed herein. The productivity of the processes, systems, and/or reaction systems (e.g., reaction systems  200  and  300 ) can be greater than other similar processes, systems, and/or reaction systems which do not introduce or feed the feedstock mixture to the reaction zone  110  separately from the catalyst systems disclosed herein. 
     The disclosed processes, systems, and/or reaction systems can provide improved commercial applicability for the use of catalysts systems in ethylene oligomerization. While not wishing to be bound by theory, it is believed that longer operating times are possible because the disclosed systems and processes can reduce polymerization during oligomerization, thus reducing the levels of problematic fouling and plugging which can occur in oligomerization reactor components. 
     Further, the disclosed systems and processes provide improved ethylene utilization as indicated by improved ethylene conversion and higher C 6  purity in the ethylene oligomer product. 
     PROPHETIC EXAMPLES 
     The subject matter having been generally described, the following examples are given as particular aspects of the disclosure and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification of the claims to follow in any manner. 
     The catalyst system would be prepared in a dry box by mixing 36 mg of Chromium Component I into 6 mL of ethylbenzene and stirring until the chromium component would be fully dissolved. The aluminoxane MMAO-3A (7 wt. % Al) would then be added to the chromium component/ethylbenzene mixture in an amount to achieve an Al:Cr molar ratio of approximately 800:1 and would be mixed for 5 to 10 minutes. The chromium component/ethylbenzene/aluminoxane mixture would then be diluted with methyl cyclohexane (MCH) in a charger vessel to provide a catalyst system mixture having a chromium component concentration of 0.025 mg/mL. The charger vessel would then be removed from the drybox and would be attached to feed line  152 . 
     
       
         
         
             
             
         
       
     
     Table 1 below shows a summary of the prophetic operating parameters for oligomerization of ethylene in Examples 1 to 2: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Prophetic Operating Parameters 
               
            
           
           
               
               
               
            
               
                   
                 Example 1 
                 Example 2 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                 Temperature (° C.) 
                 70 
                 70 
               
               
                 Pressure (psig; MPag) 
                 900; 6.21 
                 900; 6.21 
               
               
                 Organic Reaction Medium 
                 Cyclohexane 
                 Cyclohexane 
               
               
                 Organic Reaction Medium Feed Rate (g/h) 
                 400 
                 400 
               
               
                 Hydrogen Feed Rate (sccm) 
                 24 
                 24 
               
               
                 Catalyst System Feed Rate (mL/h) 
                 15.7 
                 15.7 
               
               
                   
               
            
           
         
       
     
     In Table 1 and the other tables included herein, use of “g” refers to grams, “h” refers to hours, “mL” refers to milliliters, “min” refers to minutes, “sccm” refers to standard cubic centimeters per minute, “MPag” refers to megapascals gauge, and “psig” refers to pounds per square inch gauge. 
     The organic reaction medium (cyclohexane) would be treated with mole sieves and copper oxide prior to being used for the ethylene oligomerization. 
     Prophetic Example 1 (Comparative) 
     In Example 1 (comparative), the oligomerization of ethylene would be performed without using C 3+  olefin in the reaction zone during reaction zone startup. The maximum flow rate of ethylene in Example 1 would be 200 g/h. 
     A 300 cc autoclave reactor having the feed line configurations shown in  FIG. 2  would be used as the reaction zone  110  and reaction system for Example 1. Although the system  200  of  FIG. 2  would be used for Example 1, the lines  146  and  147   a - f , which can provide C 3+  olefin, would not be used in Example 1. That is, a C 3+  olefin would not be utilized in Example 1 for comparison purposes to Example 2. As can be seen in  FIG. 2 , the ethylene feed line  142  would join with the organic reaction medium feed line  162  to yield the feedstock mixture feed line  191 , which would flow through a mixing device  190  (which would be a static mixer). Dispersed feedstock mixture would leave the mixing device  190  in line  192 , which would feed to the reaction zone  110  via second reaction zone inlet  113 . The catalyst system feed line  152  would feed to the reaction zone  110  via first reaction zone inlet  111  without any combination with other streams or dilution. For Example 1, the control valve  130  shown in  FIG. 2  would be a pair of control valves placed in parallel flow, with the second valve of the two control valves being used only upon plugging of the first control valve, if plugging were to occur. That is, the second of the two control valves would be used as a backup to the first of the two control valves so as to keep the experiment running, if needed. 
     Prior to startup, the reactor would be pressure tested with nitrogen and purged to ensure that no residual air or moisture would be present in the reactor. 
     For startup, the organic reaction medium (anhydrous cyclohexane) would be pumped using pump  180  from the organic reaction medium source  160  to the reaction zone  110  via line  162 , pump  180 , line  191 , mixing device  190 , and line  192 . Once flow of the organic reaction medium was established, the pressure of the reaction zone  110  would be adjusted to 900 psig (6.21 MPag), and the temperature would be increased to 70° C. After the pressure and temperature were reached, hydrogen flow at 24 sccm would be initiated via line  144 , line  142 , line  191 , mixing device  190 , and line  192 , and catalyst system flow rate in line  152  would then be set to 15.7 mL/h to get a reaction zone chromium concentration of about 0.5 ppm by mass. Catalyst system flow rate would then be set to 15.7 mL/h. Thirty minutes after setting the catalyst system flow rate, ethylene would be fed at 50 g/h to the reaction zone  110  via line  142 , line  191 , mixing device  190 , and line  192 . Every 15 minutes thereafter, the ethylene flow rate would be increased by 50 g/h until 200 g/h was reached (i.e., ethylene would be ramped to 200 g/h in 1 hour). 
     The first of the two control valves would plug within approximately 150 minutes after beginning ethylene feed to the reaction zone  110 . The run would be terminated approximately 250 minutes after beginning ethylene feed to the reaction zone  110  due to plugging/fouling of the autoclave reactor and additional plugging of the second of the two control valves. During the run reaction zone effluent sample would be periodically removed via a sample port located on the reaction zone effluent line  118 . After run completion, the reactor would be disassembled, the polymer recovered and weighed. The total amount of polymer formed in Example 1 is believed to be about 3 wt. % of the total amount of hexene and octene produced, which would be about 25 g of polymer. 
     Prophetic Example 2 
     In Example 2, the oligomerization of ethylene would be performed using 1-hexene as the C 3+  olefin during reaction zone startup. 
     In Example 2, a 300 cc autoclave reactor having the configuration shown in  FIG. 2  would be used. The catalyst system feed line  152  would be fed directly to the reaction zone  110 , and ethylene and hydrogen from line  142  would be combined with the organic reaction medium feed line  162  to yield the feedstock mixture in line  191 . In Example 2, 1-hexene would flow through line  146 , line  147   a , line  142 , line  191 , mixing device  190  (which would be a static mixer), and line  192  to the reaction zone  110 . For Example 2, the control valve  130  shown in  FIG. 2  would be a pair of control valves placed in parallel flow, with the second valve of the two control valves being used only upon plugging of the first control valve, if plugging were to occur. That is, the second of the two control valves would be used as a backup to the first of the two control valves so as to keep the experiment running, if needed. 
     Prior to startup, the reactor would be pressure tested with nitrogen and purged to ensure that no residual air or moisture would be present in the reactor. 
     For startup, the organic reaction medium (anhydrous cyclohexane) would be pumped using pump  180  from the organic reaction medium source  160  to the reaction zone  110  via line  162 , pump  180 , line  191 , and line  192 . Once flow of the organic reaction medium was established, the pressure of the reaction zone  110  would be adjusted to 900 psig (6.21 MPag), and the temperature would be increased to 70° C. After the pressure and temperature were reached, hydrogen flow at 24 sccm would be initiated via line  144 , line  142 , line  191 , mixing device  190 , and line  192 , and catalyst system flow rate via line  152  would then be set to 15.7 mL/h to get a total concentration of Cr to about 0.5 ppm. Thirty minutes after setting the catalyst flow, 1-hexene flow would be initiated at 200 g/hour. After 15 minutes, the 1-hexene flow rate would be reduced by 50 g/hour and the ethylene flow would be initiated at 50 g/hour. Thereafter, every 15 minutes the 1-hexene flow rate would be reduced by 50 g/hour and the ethylene flow rate would be increased by 50 g/hour until the 1-hexene flow rate would become zero and the ethylene flow rate would become 200 g/hour (approximately 1 hour after initiating the 1-hexene flow. The ethylene oligomerization would be continued until the complete consumption of the catalyst system mixture at approximately 350 minutes. During the run reaction zone effluent samples would be periodically removed via a sample port located on the reaction zone effluent line  118 . After run completion, the reactor would be disassembled, the polymer recovered and weighed. The total amount of polymer formed in Example 2 is believed to be about 2-5 g of polymer. 
     The total amount of polymer formed in Example 2 would be reduced by about 10 times compared to the amount of polymer formed in Example 1. All other performance metrics including selectivity, productivity, purity, and yield would remain approximately the same between Example 1 and Example 2 or the performance metrics including productivity and yield would increase for Example 2 over Example 1. 
     Surprisingly and unexpectedly, the presence of 1-hexene during startup in Example 2 would significantly decrease the formation of polymer when using the catalyst systems comprising i) a chromium component comprising a chromium compound, ii) a heteroatomic ligand, and iii) an aluminoxane; or alternatively, i) a chromium component comprising a heteroatomic ligand chromium compound complex, and ii) an aluminoxane. 
     While Example 2 would utilize the configuration of system  200  shown in  FIG. 2 , it is expected that the configuration of system  100  in  FIG. 1  and system  300  of  FIG. 3  would perform similarly because any ethylene can be contacted with the catalyst system in the presence of C 3+  olefin at reaction conditions—even though no feedstock mixture is utilized in  FIG. 1  and even though the contact between ethylene and the catalyst system in  FIG. 3  is outside the reaction zone  110 . Thus, it is expected that system  100  and system  300  would have the same surprising and unexpected results as system  200 . 
     Additional Disclosure 
     Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an aspect of the present invention. Thus, the claims are a further description and are an addition to the detailed description of the present invention. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference. 
     Embodiment 1 
     A process comprising: a) introducing into a reaction zone containing a C 3+  olefin (any disclosed herein) and optionally an organic reaction medium (any disclosed herein) wherein the reaction zone is substantially devoid of ethylene; i) ethylene ii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iii) the organic reaction medium, and iv) optionally hydrogen; and b) forming an ethylene oligomer product in the reaction zone; wherein the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. 
     Embodiment 2 
     A process comprising: a) contacting in a reaction zone i) a C 3+  olefin (e.g., any disclosed herein), ii) ethylene, iii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iv) an organic reaction medium (any disclosed herein), and v) optionally hydrogen into the reaction zone; and c) forming an ethylene oligomer product; wherein the C 3+  olefin is not an ethylene oligomer formed in-situ within the reaction zone. 
     Embodiment 3 
     A process comprising: a) contacting i) ethylene, ii) a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), iii) an organic reaction medium (any described herein), and iv) optionally hydrogen in a reaction zone; b) forming an ethylene oligomer product in the reaction zone; wherein ethylene, the catalyst system, and the organic reaction medium are introduced into the reaction zone and for a period of time a C 3+  olefin is introduced into the reaction zone. 
     Embodiment 4 
     The process of embodiment 2 or 3, wherein ethylene, the organic reaction medium, and for the period of time the C 3+  olefin are separately introduced into the reaction zone. 
     Embodiment 5 
     The process of embodiment 2 or 3, wherein ethylene and at least a portion of the organic reaction medium are contacted to form a feedstock mixture prior to the ethylene contacting the catalyst system and the feedstock mixture and for the period of time the C 3+  olefin are separately introduced to the reaction zone. 
     Embodiment 6 
     The process of embodiment 4 or 5, further comprising introducing the C 3+  olefin to the reaction zone prior to introducing the ethylene, the catalyst system, or both the ethylene and the catalyst system to the reaction zone. 
     Embodiment 7 
     The process of embodiment 2 or 3, wherein ethylene, at least a portion of the organic reaction medium, and for the period of time the C 3+  olefin are contacted to form a feedstock mixture prior to the ethylene contacting the catalyst system. 
     Embodiment 8 
     A process comprising: a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); b) for a period of time separately feeding to the reaction zone a feedstock mixture comprising ethylene and i) a C 3+  olefin (e.g., any described herein), and ii) at least a portion of an organic reaction medium (e.g., any described herein), or iii) combinations of i) and ii); wherein the feedstock mixture is substantially free of the catalyst system; c) contacting the catalyst system and the feedstock mixture in the reaction zone; and d) forming an ethylene oligomer product in the reaction zone. 
     Embodiment 9 
     A process comprising: a) contacting i) ethylene, ii) at least a portion of an organic reaction medium (e.g., any disclosed herein), and iii) for a period of time a C 3+  olefin (e.g., any disclosed herein) to form a feedstock mixture; b) subsequent to a), contacting in a reaction zone the feedstock mixture with a catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) forming an ethylene oligomer product in the reaction zone. 
     Embodiment 10 
     A process comprising: a) diluting ethylene by addition of at least i) a portion of an organic reaction medium (any described herein), ii) for a period of time a C 3+  olefin (e.g., any described herein), or iii) for a period of time at least a portion of an organic reaction medium (any described herein) and a C 3+  olefin to form a feedstock mixture prior to contacting the ethylene with a catalyst system in a reaction zone; b) contacting in the reaction zone the feedstock mixture and the catalyst system, wherein the catalyst system comprises i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and ii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) forming an ethylene oligomer product in the reaction zone. 
     Embodiment 11 
     A system comprising: a) a feedstock mixture comprising ethylene, an organic reaction medium (e.g., any described herein), and for a period of time a C 3+  olefin (e.g., any described herein); b) a catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); and c) a reaction zone receiving the feedstock mixture separately from the catalyst stream. 
     Embodiment 12 
     The system of embodiment 11, further comprising a reaction zone effluent line comprising an ethylene oligomer product formed in the reaction zone. 
     Embodiment 13 
     The process of any one of embodiments 7-10 or the system of any one of embodiments 10-11, wherein for the period of time the C 3+  olefin is dispersed in the feedstock mixture prior to introducing/feeding the feedstock mixture into the reaction zone. 
     Embodiment 14 
     The process of any one of embodiments 5-10, 13, or the system of any one of embodiments 11-13, wherein ethylene is dispersed within the feedstock mixture prior to ethylene contacting the catalyst system. 
     Embodiment 15 
     The process of any one of embodiments 5-10, 13-14, or the system of any one of embodiments 11-14, wherein ethylene is dispersed with the organic reaction medium prior to introduction of the feedstock mixture into the reaction zone. 
     Embodiment 16 
     The process of any one of embodiments 5-10, 13-15, or the system of any one of embodiments 10-14, wherein the period of time occurs during a reaction zone startup. 
     Embodiment 17 
     A process comprising: a) feeding a catalyst system to a reaction zone, the catalyst system comprising i) a chromium component comprising a chromium compound (any described herein), ii) a heteroatomic ligand (any described herein), and iii) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising i) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and ii) an aluminoxane (any disclosed herein); b) separately feeding to the reaction zone a feedstock mixture comprising i) ethylene, ii) an organic reaction medium (e.g., any described herein), and iii) for a period of time a C 3+  olefin (e.g., any described herein) to contact the catalyst system; wherein during a reaction zone startup the feedstock mixture C 3+  olefin:ethylene weight ratio periodically or continuously decreases; c) forming an ethylene oligomer product in the reaction zone; and d) operating the reaction zone in about steady-state conditions subsequent to the reaction zone start-up; wherein the feedstock mixture comprising i) ethylene, ii) a C 3+  olefin, and iii) an organic reaction medium is fed to the reaction zone for a period of time. 
     Embodiment 18 
     A process for startup of a reaction zone, the process comprising: for a period of time contacting in the reaction zone 1) ethylene, 2) a catalyst system comprising a) a chromium component comprising a chromium compound (any described herein), b) a heteroatomic ligand (any described herein), and c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and b) an aluminoxane (any disclosed herein), 3) an organic reaction medium, and 4) optionally hydrogen to form an ethylene oligomer product; wherein: the catalyst system is fed to the reaction zone, a feedstock mixture comprising i) ethylene, ii) an organic reaction medium (any described herein), and iii) a C 3+  olefin (any described herein) is fed to the reaction zone for a period of time, wherein the feedstock mixture is substantially free of the catalyst system prior to the feedstock mixture contacting the catalyst system in the reaction zone. 
     Embodiment 19 
     The process of embodiment 17 or 18, wherein for the period of time the C 3+  olefin is dispersed in the feedstock mixture prior to introducing/feeding the feedstock mixture into the reaction zone. 
     Embodiment 20 
     The process of any one of embodiments 17-19, wherein ethylene is dispersed within the feedstock mixture prior to ethylene contacting the catalyst system. 
     Embodiment 21 
     The subject matter of any one of embodiments 5-20, wherein the period of time begins at a point when the reaction zone is not producing the ethylene oligomer product. 
     Embodiment 22 
     The subject matter of any one of embodiments 5-21, wherein over a C 3+  olefin/ethylene feed period of time period of time a C 3+  olefin:ethylene weight ratio fed/introduced to the reaction zone decreases from a value of at least 0.5:1 (or any other at least value disclosed herein) to a value less than 0.2:1 (or any other less than value disclosed herein). 
     Embodiment 23 
     The subject matter of any one of embodiments 5-22, wherein the C 3+  olefin:ethylene weight ratio has an initial value of about 1:0. 
     Embodiment 24 
     The subject matter of any one of embodiments 5-23, wherein the C 3+  olefin:ethylene weight ratio decreases to a value of about 0:1. 
     Embodiment 25 
     The subject matter of any one of embodiments 1-24, wherein over a reaction zone period of time the reaction zone has a C 3+  olefin to ethylene zone weight ratio that decreases from a value of at least 0.5:1 (or any other reaction zone at least value disclosed herein) to a value less than 0.2:1 (or any other reaction zone less than value disclosed herein), wherein the C 3+  olefin in the reaction zone and the C 3+  olefin of the C 3+  olefin:ethylene weight ratio is not an ethylene oligomer formed in-situ within the reaction zone. 
     Embodiment 26 
     The subject matter of any one of embodiments 1-25, further comprising contacting the C 3+  olefin with the catalyst system prior to introducing (or feeding) the C 3+  olefin and the catalyst system to the reaction zone. 
     Embodiment 27 
     The subject matter of any one of embodiments 1-26, wherein substantially no C 3+  olefin is introduced or fed to the reaction zone after the period of time, wherein the period of time is a reaction zone period of time or a C 3+  olefin/ethylene feed period of time. 
     Embodiment 28 
     The subject matter of any one of embodiments 1-27, wherein the reaction zone is operated under steady-state conditions after the period of time (or subsequent to the reaction zone start-up period), wherein the period of time is a reaction zone period of time or a C 3+  olefin/ethylene feed period of time. 
     Embodiment 29 
     The subject matter of any one of embodiments 1-27, wherein the contacting of ethylene and the organic reaction medium to form the feedstock mixture occurs subsequently, but not exclusively, after the period of time (or after reaction zone startup), wherein the period of time is a reaction zone period of time or a C 3+  olefin/ethylene feed period of time. 
     Embodiment 30 
     The subject matter of any one of embodiments 27-29, wherein substantially all of the ethylene is introduced to the reaction zone via the feedstock mixture. 
     Embodiment 31 
     The subject matter of any one of embodiment 27-30, wherein the catalyst system is introduced into the reaction zone separately from feedstock mixture. 
     Embodiment 32 
     The subject matter of any one of embodiments 1-31, wherein the at least a portion of the organic reaction medium is contacted with an alkylaluminum compound prior to introduction of the at least a portion of the organic reaction medium to the reaction zone. 
     Embodiment 33 
     The subject matter of any one of embodiments 1-32, wherein the at least a portion of the organic reaction medium is contacted with an alkylaluminum compound prior to contact of ethylene with the at least a portion of the organic reaction medium. 
     Embodiment 34 
     The subject matter of any one of embodiments 1-33, wherein the catalyst system mixture comprises a diluent. 
     Embodiment 35 
     The subject matter of embodiment 36, wherein the diluent comprises the organic reaction medium. 
     Embodiment 36 
     The subject matter of any one of embodiments 1-34, wherein a reaction zone effluent comprising the ethylene oligomer product is removed from the reaction zone. 
     Embodiment 37 
     The subject matter of any one of embodiments 1-36, wherein hexenes and/or or octenes are separated from the reaction zone effluent. 
     Embodiment 38 
     The subject matter of any one of embodiments 1-37, wherein the feedstock mixture, the catalyst system, and optionally, hydrogen are periodically or continuously introduced into the reaction zone and a reaction zone effluent comprising the ethylene oligomer product is periodically or continuously removed from the reaction zone. 
     Embodiment 39 
     The subject matter of any one of embodiments 1-38, wherein a mass of polymer per mass of oligomer in the reaction zone is less than the mass of polymer per mass of oligomer in the reaction zone in an otherwise similar process or system where a C 3+  olefin:ethylene weight ratio does not decrease over the period of time. 
     Embodiment 40 
     The subject matter of any one of embodiments 1-39, wherein a mass of polymer per mass of oligomer in the reaction zone is less than the mass of polymer per mass of oligomer in the reaction zone in an otherwise similar process or system which does not: i) contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system, or ii) introduce or feed the feedstock mixture into the reaction zone separately from the catalyst system. 
     Embodiment 41 
     The subject matter of any one of embodiments 1-40, having a productivity higher than a productivity in an otherwise similar process or system where the reaction zone C 3+  olefin:ethylene weight ratio does not decrease over the period of time. 
     Embodiment 42 
     The subject matter of any one of embodiments 1-41, having a productivity higher than a productivity in an otherwise similar process or system which does not: i) contact ethylene with the at least a portion of the organic reaction medium prior to contact of ethylene with the catalyst system, or ii) introduce or feed the feedstock mixture into the reaction zone separately from the catalyst system. 
     Embodiment 43 
     A reaction system comprising: a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein) to the reaction zone; a second reaction zone inlet configured to introduce ethylene, an organic reaction medium, and optionally hydrogen to the reaction zone; a C 3+  olefin feed line in fluid communication with the first reaction zone inlet, the second reaction zone inlet, or a third reaction zone inlet configured to introduce a C 3+  olefin to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. 
     Embodiment 44 
     The reaction system of embodiment 43, further comprising: a catalyst system feed line flowing the catalyst system to the first reaction zone inlet; an ethylene feed line comprising the ethylene; an organic reaction medium feed line comprising the organic reaction medium, wherein the organic reaction medium feed line and the ethylene feed line combine to yield the feedstock mixture which is introduced to the reaction zone via the second reaction zone inlet, wherein the C 3+  olefin feed line combines with at least one of the catalyst system feed line, the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, or a dispersed feedstock mixture feed line formed by passing the feedstock mixture through a mixing device prior to flowing to the reaction zone via the second reaction zone inlet. 
     Embodiment 45 
     The reaction system of embodiment 43 or 44, further comprising: a pump in fluid communication with the second reaction zone inlet and which is located upstream of a point where the ethylene feed line and the organic reaction medium feed line join to produce the feedstock mixture; and a mixing device positioned between i) the joining of the ethylene feed line and the organic reaction medium feed line and ii) the second reaction zone inlet to disperse the ethylene and the organic reaction medium prior to the feedstock mixture entering the reaction zone. 
     Embodiment 46 
     The reaction system of any one of embodiments 43-45, wherein during steady state operation, the first reaction zone inlet is configured to periodically or continuously introduce the catalyst system to the reaction zone, the second reaction zone inlet is configured to periodically or continuously introduced the feedstock mixture to the reaction zone, and the one or more reaction zone outlets are configured to periodically or continuously discharge the reaction zone effluent from the reaction zone. 
     Embodiment 47 
     A reaction system comprising: a reaction zone; a reaction zone inlet configured to introduce a catalyst system, ethylene, an organic reaction medium, and a C 3+  olefin to the reaction zone; an ethylene feed line comprising ethylene, a C 3+  olefin feed line comprising a C 3+  olefin, an organic reaction medium feed line comprising an organic reaction medium and optionally a hydrogen feed line comprising hydrogen all in fluid communication with the reaction zone inlet, wherein the organic reaction medium feed line combines with the ethylene feed line to form a feedstock mixture feed line in fluid communication with the reaction zone inlet; a catalyst system feed line comprising catalyst system in fluid communication with the reaction zone inlet, wherein the catalyst system feed line combines with the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, or a dispersed feedstock mixture feed line formed by passing the feedstock mixture feed line through a mixing device; one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone, wherein the catalyst system comprises (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein), and wherein the C 3+  olefin feed line joins with one or more of the ethylene feed line, the organic reaction medium feed line, the feedstock mixture feed line, the dispersed feedstock mixture feed line, or a combined feed line formed by joining the catalyst system feed line and the dispersed feedstock mixture feed line. 
     Embodiment 48 
     The reaction system of embodiment 47, further comprising: a mixing device positioned between i) the joining of the ethylene feed line and the organic reaction medium feed line and ii) the reaction zone inlet to disperse the ethylene and the organic reaction medium prior to the feedstock mixture joining with the catalyst system and entering the reaction zone. 
     Embodiment 49 
     The reaction system of any one of embodiments 47-48, wherein the reaction zone inlet is configured to periodically or continuously introduce the catalyst system and the feedstock mixture to the reaction zone, and the one or more reaction zone outlets are configured to periodically or continuously discharge the reaction zone effluent from the reaction zone. 
     Embodiment 50 
     A reaction system comprising: a reaction zone; a first reaction zone inlet configured to introduce a catalyst system comprising (a) a chromium component comprising a chromium compound (any described herein), (b) a heteroatomic ligand (any described herein), and (c) an aluminoxane (any disclosed herein); or alternatively, a catalyst system comprising (a) a chromium component comprising a heteroatomic ligand chromium compound complex (any described herein), and (b) an aluminoxane (any disclosed herein) to the reaction zone; a second reaction zone inlet configured to introduce ethylene and optionally hydrogen to the reaction zone; a third reaction zone inlet configured to introduce an organic reaction medium to the reaction zone; a C 3+  olefin feed line in fluid communication with one or more of the first reaction zone inlet, the second reaction zone inlet, the third reaction zone inlet, or a fourth reaction zone inlet which is configured to introduce the C 3+  olefin directly to the reaction zone; and one or more reaction zone outlets configured to discharge the reaction zone effluent comprising an ethylene oligomer product from the reaction zone. 
     Embodiment 51 
     The reaction system of embodiment 50, further comprising: a catalyst system feed line flowing the catalyst system to the first reaction zone inlet; an ethylene feed line comprising flowing ethylene to the second reaction zone inlet; and an organic reaction medium feed line flowing the organic reaction medium to the third reaction zone inlet, wherein the C 3+  olefin feed line i) combines with at least one of the catalyst system feed line, the ethylene feed line, or the organic reaction medium feed line, or ii) flows directly to the fourth reaction zone inlet. 
     Embodiment 52 
     The subject matter of any one of embodiments 1-51, wherein the C 3+  olefin comprises a C 4  to C 16  internal olefin or alpha olefin. 
     Embodiment 53 
     The subject matter of any one of embodiments 1-51, wherein the C 3+  olefin comprises 1-hexene, 1-octene, or 1-hexene and 1-octene. 
     Embodiment 54 
     The subject matter of any one of embodiments 1-53, wherein the heteroatomic ligand has the structure 
                         
(or alternatively, the heteroatomic ligand chromium complex has the structure
 
                         
where each X 1s  is independently selected from the group consisting of N, P, O, and S; L 1s  is an organylene linking group linking X 1s s; m and n are independently 1 or 2; each R 1s  is independently an organyl group; X is a monoanionic ligand; and p is from 2 to 6.
 
     The inventions illustratively disclosed herein suitably can be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above can vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. 
     All publications and patents mentioned herein are incorporated herein by reference. The publications and patents mentioned herein can be utilized for the purpose of describing and disclosing, for example, the constructs and methodologies that are described in the publications, which might be used in connection with the presently described invention. The publications discussed throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. This concludes the detailed description. The particular embodiments disclosed above are illustrative only, as the invention can be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above can be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims herein.