Membrane-Based Separation Processes Enhanced with an Absorption Device

A salt ion membrane may be paired with an absorption device to provide advantaged separation processes comprising: introducing a first aqueous salt stream and a mixed feed stream comprising at least one olefin and at least one paraffin to a salt ion membrane under conditions effective to form at least two phases; obtaining an olefin-rich permeate stream and an olefin-lean retentate stream from the salt ion membrane, in which the olefin-rich permeate stream and/or the olefin-lean retentate stream further comprises a salt ion membrane aqueous salt phase; introducing at least a portion of the olefin-lean retentate stream and a second aqueous salt stream to an absorption device under conditions effective to promote olefin extraction; obtaining an olefin-rich aqueous salt stream from the absorption device; and providing at least a portion of the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream.

FIELD

The present disclosure relates to hydrocarbon separation processes and, more particularly, membrane-based processes for separating at least one olefin from at least one paraffin.

BACKGROUND

Olefinic hydrocarbons (olefins) are among the world's most useful chemical components. Ethylene and propylene are among the highest volume petrochemical products used in chemical production, while 1-butene (butene-1), isobutylene, and isoamylene are widely used as petrochemical products and as intermediates in the production of motor gasoline. Similarly, olefinic hydrocarbons having from 6 to 12 carbon atoms are also useful petrochemical products, including as motor gasoline blend components, given their considerably higher octane value compared to their paraffinic hydrocarbon counterparts of the same carbon number.

Olefins may be produced by thermal or catalytic reactions of a wide range of naturally occurring hydrocarbon feedstocks, including natural gas (predominantly methane), ethane, propane, butanes, pentanes, liquid petroleum fractions including naphtha and atmospheric gas oil, and even whole crude with gaseous hydrocarbons removed. Historically, the dominant processes in industry have involved cracking chemistry, such as Steam Cracking and Fluidized Catalyst Cracking. More recently, processes have been commercialized to produce light olefins like propylene and butenes through catalytic dehydrogenation of their corresponding paraffins, i.e., propane and n-butane.

Olefin production processes may create a desired olefin in combination with a considerable concentration of many other hydrocarbon species ranging from simple paraffins like methane to complex hydrocarbons like multi-ring aromatic compounds. Heteroatomic compounds may also be produced in some cases, typically if one or more heteroatoms was present in a hydrocarbon feedstock or present in the reaction conditions used to produce the olefin. Paraffins having the same number of carbon atoms as a desired olefin or having one carbon atom more or less than a desired olefin may be commonly produced, although an even wider breadth of paraffins may frequently occur, oftentimes in combination with additional olefins as well. Residual paraffins from a hydrocarbon feedstock may also be present. For example, Steam Cracking of an ethane feedstock may afford a C2 stream comprising about 60-80 wt % ethylene and about 20-40 wt % ethane, while a naphtha feedstock may afford a C2 stream comprising about 80-90 wt % ethylene and about 10-20 wt % ethane in combination with a C3 stream comprising about 85-95 wt % propylene and about 5-15 wt % propane. Catalytic dehydrogenation of propane may afford a C3 stream comprising about 30-60 wt % propylene and about 40-70 wt % propane.

While olefins may be used to create many types of products, their largest use is in polymer synthesis, where high-purity ethylene and propylene feedstocks may be highly desired. For example, the minimum ethylene purity for polyethylene production may be about 99.9 wt %, or even about 99.95 wt %, with the balance of materials being paraffin compounds including methane, ethane and propane, for example. Similarly, the minimum propylene purity for creating polypropylene polymers and copolymers may be at least about 99.5 wt %, again with the balance of materials usually being paraffins. There may be additional limitations on olefin purity such as, for example, heteroatomic compound amounts less than 100 ppm by weight relative to olefin, highly unsaturated hydrocarbons such as dienes or acetylenes less than 100 ppm by weight relative to olefin, and less than 100 ppm by weight olefins other than a desired olefin (e.g., propylene and butenes in ethylene, and ethylene, butenes and pentenes in propylene).

Thus, separation of olefins from paraffins is among the most widely practice separations in the petrochemical industry, especially from paraffins having the same number of carbon atoms or paraffins within one carbon atom of a desired olefin. Such separations have conventionally been conducted by fractional distillation processes that may be very energy intensive and necessitate a large capital equipment investment. For example, separation of ethylene from ethane may utilize a distillation column having about 130 theoretical plates and a reflux ratio of about 6, and that is conducted at a distillation temperature of about −20° C. or below, which may necessitate use of an expensive refrigeration system. Separation of propylene from propane via distillation may be conducted above ambient temperatures but utilize a distillation column having as many as about 200 theoretical plates and a reflux ratio of about 11-17. For reference, ethylene and propylene distillation processes may produce polymer-grade ethylene and propylene with purities of about 99.9 wt % and about 99.5 wt %, respectively, at a recovery of olefins from a hydrocarbon feed of up to about 99.9 wt % and about 99.0 wt %, respectively for ethylene and propylene, even from hydrocarbon feedstocks having an olefin concentration as low as about 30 wt %. Usually, the higher the carbon number, the more energy intensive and expensive the separation of an olefin from its corresponding paraffin becomes. As such, large-scale separation of olefins larger than propylene by distillation may become cost- and energetically prohibitive.

Membranes are an emerging technology for the separations of olefins from paraffins. Although various membrane technologies have been developed, “facilitated transport” membranes are among those with high promise for large-scale commercial applications. Such facilitated transport membranes may feature a copper or silver salt as a cationic constituent embedded within a membrane material in the presence of water, either as a vapor or as a liquid, leading such membranes to be referred to herein as “salt ion membranes.” Non-limiting examples of such facilitated transport membranes are disclosed in U.S. Patent Application Publication 2018/0093230, and U.S. Pat. Nos. 9,782,724 and 10,507,435, each of which is incorporated herein by reference. Illustrative facilitated transport membrane may employ a porous membrane material comprising a hydrophilic polymer such as chitosan, hyaluronic acid and/or sodium alginate, in which the cationic constituent of the salt resides. Hydrophilic polymers such as these may afford good olefin-paraffin separation selectivity in the presence of water, which may be in a liquid phase and/or a vapor phase.

Facilitated transport membranes are not without their difficulties, however. Like any membrane operating with a pressure drop through the membrane material (in this case, the partial pressure of the olefin), the pressure drop is the only driving force for promoting separation. As chemical potentials equalize, the separation eventually runs out of driving force to carry an olefin over to a permeate side of the membrane material. Thus, for a single membrane stage, one may achieve either a relatively high recovery of the olefins from a hydrocarbon feed with a modest olefin purity, or incomplete recovery of the olefins a hydrocarbon feed but with high olefin purity. Further, the lower the olefin concentration in a given hydrocarbon feed, the lower the olefin recovery that can be practically achieved at a specified olefin purity. This dichotomy is the single greatest disadvantage of membrane separation technologies and is the primary reason they have seen so little industrial application to date. As noted above, olefin syntheses are often complicated and expensive, and high-purity olefins obtained in high yield are needed for many applications, conditions which single-stage membrane separations are presently unable to provide.

By way of example, U.S. Pat. No. 10,507,435 describes a membrane-based olefin separation process that provides propylene at 99.5 wt % purity, but only at about 70 wt % recovery from a hydrocarbon feed containing a relatively high loading of propylene (70 wt % in hydrocarbon feed), an undesirable amount of yield loss in most circumstances. While olefin recovery may be improved using multiple membranes in “membrane cascades,” again as described in U.S. Pat. No. 10,507,435, such cascades may be expensive to build and operate relative to a single membrane stage. For example, a substantially larger membrane contact area may be needed in downstream membrane stages, especially for ethylene, propylene, butenes, or pentenes separations. In addition, to keep the olefin partial pressure sufficiently high throughout the membrane cascade, expensive and energy-intensive compressors may be needed to circulate low pressure, vapor-phase permeate from downstream membrane stages to an upstream membrane stage.

Another alternative for separating olefins from paraffins involves contacting an aqueous salt solution, such as an aqueous copper or silver salt, with a hydrocarbon feed containing one or more olefins, in essentially an extractive separation process. Without being bound by theory or mechanism, a cationic portion of the metal salt is believed to form an olefin pi-bond complex that is of significantly lower volatility than the corresponding paraffins, which do not form a pi-bond complex and thus allows ready separation of the paraffins from the olefins. Aqueous silver nitrate has been studied in particular depth, especially for ethylene and ethane, as described in U.S. Pat. Nos. 4,174,353 and 6,395,952, incorporated herein by reference, and “Separation and Purification Technology/Edition 1,” edited by Norman N. Li, Joseph M. Calo, Publisher: Taylor & Francis, Jul. 21, 1992; Chapter 3: Olefin Recovery and Purification via Silver Complexation, Keller, et al. While such complexation-based extractive separation technologies may avoid some of the problems of conventional olefin distillations while achieving similar olefin recovery and purity, capital equipment and operating expenses are still significant concerns. Moreover, a large metal salt inventory is often needed, particularly outside of an absorption column where contact takes place to form the complex, such as within a vent column, heat exchangers, and a stripping column. Further, recycling of vent column vapor to the absorption column may be conducted to improve olefin recovery and may utilize a compressor, thereby increasing process complexity and capital equipment needs still further.

SUMMARY

In various aspects, the present disclosure provides processes comprising: providing a mixed feed stream comprising at least one olefin and at least one paraffin; introducing at least a first portion of the mixed feed stream and a first aqueous salt stream to a salt ion membrane under conditions effective to form at least two phases while contacting the salt ion membrane; wherein the salt ion membrane is more permeable to olefins than to paraffins; obtaining an olefin-rich permeate stream and an olefin-lean retentate stream from the salt ion membrane, the olefin-lean retentate stream comprising at least a portion of the at least one olefin from the mixed feed stream; wherein at least one of the olefin-rich permeate stream and the olefin-lean retentate stream further comprises a salt ion membrane aqueous salt phase; introducing at least a portion of the olefin-lean retentate stream and a second aqueous salt stream to an absorption device under conditions effective to promote olefin extraction into the second aqueous salt stream; obtaining from the absorption device an olefin-rich aqueous salt stream comprising at least a portion of the at least one olefin from the olefin-lean retentate stream, and an olefin-lean hydrocarbon stream comprising at least a portion of the at least one paraffin from the mixed feed stream; and providing at least a portion of the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream.

These and other features and attributes of the disclosed methods and compositions of the present disclosure and their advantageous applications and/or uses will be apparent from the detailed description which follows.

DETAILED DESCRIPTION

The present disclosure relates to hydrocarbon separation processes and, more particularly, membrane-based processes for separating at least one olefin from at least one paraffin.

Definitions

Various specific embodiments, versions and examples of the invention will now be described, including preferred embodiments and definitions that are adopted herein for purposes of understanding the claimed invention. While the following detailed description gives specific preferred embodiments, those skilled in the art will appreciate that these embodiments are exemplary only, and that the invention may be practiced in other ways. For purposes of determining infringement, the scope of the invention will refer to any one or more of the appended claims, including their equivalents, and elements or limitations that are equivalent to those that are recited. Any reference to the “invention” may refer to one or more, but not necessarily all, of the inventions defined by the claims.

In this disclosure, a process may be described as comprising at least one “step.” It should be understood that each step is an action or operation that may be carried out once or multiple times in the process, in a continuous or discontinuous fashion. Unless specified to the contrary or the context clearly indicates otherwise, multiple steps in a process may be conducted sequentially in the order as they are listed, with or without overlapping with one or more other step, or in any other order, as the case may be. In addition, one or more or even all steps may be conducted simultaneously with regard to the same or different batch of material. For example, in a continuous process, while a first step in a process is being conducted with respect to a raw material just fed into the beginning of the process, a second step may be carried out simultaneously with respect to an intermediate material resulting from treating the raw materials fed into the process at an earlier time in the first step. Preferably, the steps are conducted in the order described.

Unless otherwise indicated, all numbers indicating quantities in this disclosure are to be understood as being modified by the term “about” in all instances. It should also be understood that the precise numerical values used in the specification and claims constitute specific embodiments. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measured data inherently contain a certain level of error due to the limitation of the technique and equipment used for making the measurement.

As used herein, the indefinite articles “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. Thus, for example, embodiments using “a fractionation column” include embodiments where one, two or more fractionation columns are used, unless specified to the contrary or the context clearly indicates that only one fractionation column is used.

As used herein, the term “consisting essentially of” means a composition, feed, stream or effluent that includes a given component or group of components at a concentration of at least about 60 wt %, preferably at least about 70 wt %, more preferably at least about 80 wt %, more preferably at least about 90 wt %, or still more preferably at least about 95 wt %, based on the total weight of the composition, feed, stream or effluent.

The following abbreviations may be used herein for the sake of brevity: RT is room temperature (and is 23° C. unless otherwise indicated), kPag is kilopascal gauge, psig is pound-force per square inch gauge, barg is bar gauge, psia is pounds per square inch absolute, and WHSV is weight hourly space velocity.

As used herein, “wt %” means percentage by weight, “vol %” means percentage by volume, “mol %” means percentage by mole, “ppm” means parts per million, and “ppm wt” and “wppm” are used interchangeably to mean parts per million on a weight basis. All concentrations herein are expressed on the basis of the total amount of the composition in question. All ranges expressed herein should include both end points as two specific embodiments unless specified or indicated to the contrary.

Nomenclature of elements and groups thereof used herein are pursuant to the Periodic Table used by the International Union of Pure and Applied Chemistry after 1988. An example of the Periodic Table is shown in the inner page of the front cover of Advanced Inorganic Chemistry, 6th Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

As used herein, the term “hydrocarbon” means (i) any compound consisting of hydrogen and carbon atoms or (ii) any mixture of two or more such compounds in (i). The term “Cn hydrocarbon,” where n is a positive integer, means (i) any hydrocarbon compound comprising carbon atom(s) in its molecule at the total number of n, or (ii) any mixture of two or more such hydrocarbon compounds in (i). Thus, a C2 hydrocarbon can be ethane, ethylene, acetylene, or mixtures of at least two of such at any proportion. A “Cm to Cn hydrocarbon” or “Cm-Cn hydrocarbon,” where m and n are positive integers and m<n, means any of Cm, Cm+1, Cm+2, . . . , Cn−1, Cn hydrocarbons, or any mixtures of two or more thereof. Thus, a “C2 to C3 hydrocarbon” or “C2-C3 hydrocarbon” can be any of ethane, ethylene, acetylene, propane, propene, propyne, propadiene, cyclopropane, and any mixtures of two or more thereof at any proportion between and among the components. A “saturated C2-C3 hydrocarbon” can be ethane, propane, cyclopropane, or any mixture thereof of two or more thereof at any proportion. A “Cn+ hydrocarbon” means (i) any hydrocarbon compound comprising carbon atom(s) in its molecule at the total number of at least n, or (ii) any mixture of two or more such hydrocarbon compounds in (i). A “Cn− hydrocarbon” means (i) any hydrocarbon compound comprising carbon atoms in its molecule at the total number of at most n, or (ii) any mixture of two or more such hydrocarbon compounds in (i). A “Cm hydrocarbon stream” means a hydrocarbon stream consisting essentially of Cm hydrocarbon(s). A “Cm-Cn hydrocarbon stream” means a hydrocarbon stream consisting essentially of Cm-Cn hydrocarbon(s).

As used herein, an “aromatic hydrocarbon” is a hydrocarbon comprising an aromatic ring in the molecule structure thereof. An aromatic compound may have a cyclic cloud of pi electrons meeting the Hückel rule. A “non-aromatic hydrocarbon” means a hydrocarbon other than an aromatic hydrocarbon.

An “effluent” or a “feed” is sometimes also called a “stream” in this disclosure. Where two or more streams are shown to form a joint stream and then supplied into a vessel, it should be interpreted to include alternatives where the streams are supplied separately to the vessel where appropriate. Likewise, where two or more streams are supplied separately to a vessel, it should be interpreted to include alternatives where the streams are combined before entering into the vessel as joint stream(s) where appropriate.

The term “selectivity” refers to the degree to which a particular reaction forms a specific product, rather than another product, or the degree to which a separation process separates a specific component from another component, rather than the other component being retained with the specific component. Selectivity is based on the product formed or separated, regardless of the conversion/yield of a particular reaction or the extent of separation of a component of interest from a mixture. The selectivity for a given component can be defined as weight percent (wt %) of that component relative to the total weight of other components that are formed or separated with a component of interest.

As used herein, the term “liquid-phase” means separation conditions in which a stream is substantially in liquid phase. “Substantially in liquid phase” means ≥90 wt %, preferably ≥95 wt %, preferably ≥99 wt %, and preferably the entirety of the stream is in liquid phase.

As used herein, the term “vapor-phase” means separation conditions in which a stream is substantially in vapor phase. “Substantially in vapor phase” means ≥90 wt %, preferably ≥95 wt %, preferably ≥99 wt %, and preferably the entirety of the stream is in vapor phase.

As used herein, the term “rich” or “enriched,” when describing a component in a stream, means that the stream comprises the component at a concentration higher than a source material from which the stream is derived. As used herein, the term “depleted” or “lean,” when describing a component in a stream, means that the stream comprises the component at a concentration lower than a source material from which the stream is derived.

Unless otherwise specified herein, any stream herein that is “rich” in a particular component may “consist of” or “consist essentially of” that component. “Consisting essentially of,” as used herein, means that a composition, feed, stream or effluent comprises a given component at a concentration of at least about 60 wt %, preferably at least about 70 wt %, more preferably at least about 80 wt %, more preferably at least about 90 wt %, still more preferably at least about 95 wt %, based on the total mass of the composition, feed, stream or effluent in question.

Unless otherwise specified herein, any stream that is “lean” in a particular component may be “free of” or “substantially free of” that component. “Essentially free of” and “substantially free of,” as interchangeably used herein, mean that a composition, feed, stream or effluent comprises a given component at a concentration of at most about 10 wt %, preferably at most about 8 wt %, more preferably at most about 5 wt %, more preferably at most about 3 wt %, still more preferably at most about 1 wt %, based on the total mass of the composition, feed, stream or effluent in question.

Olefin Separation Processes

As discussed above, separation of a hydrocarbon feed comprising a mixture of at least one olefin and at least one paraffin may be problematic. Distillation processes may be energy-intensive and cost-prohibitive, including large capital equipment investments. Complexation-based separations have not yet progressed to a point of economic viability. Membrane-based separations using a single membrane are unable to simultaneously afford high olefin purity and high olefin recovery, and membrane cascades may be expensive and complicated to implement.

The present disclosure provides advantaged separation processes for separating a feed mixture comprising at least one olefin and at least one paraffin, referred to herein as a “mixed feed stream.” In particular, the separation processes disclosed herein couple membrane-based separation (e.g., using a facilitated transport membrane, such as a salt ion membrane) with olefin complexation aspects of extractive separation using a suitable metal salt. That is, the separation processes disclosed herein may enhance or augment membrane-based separation of at least one olefin from at least one paraffin with an absorption device that promotes contact of one or more olefins with an aqueous salt solution capable of forming a complex with one or more olefins. As disclosed herein, a salt ion membrane may facilitate olefin recovery in high purity, even though a low recovery of olefins may occur, and an absorption device may facilitate recovery of olefins otherwise not recovered from a permeate side of the salt ion membrane. Accordingly, the processes disclosed herein may achieve both high olefin purity and high recovery with a single membrane stage and a single absorption device.

The separation processes disclosed herein are based upon the recognition that an aqueous salt solution suitable to promote olefin complexation also may contact a salt ion membrane to promote separation therein as well, thereby allowing the membrane separation process and the complexation process to be effectively coupled together with one another. When coupled together appropriately, as discussed in further detail herein, the salt ion membrane may promote high-purity separation of at least one olefin from at least one paraffin, and the absorption device and its associated aqueous salt solution may increase the extent of recovery of at least one olefin. An aqueous salt solution that both contacts a salt ion membrane and is used for promoting olefin complexation in an absorption device may be referred to herein as a “salt ion membrane aqueous salt phase.” As such, the present disclosure advantageously overcomes the primary difficulties associated with conventional membrane-based and extraction-based olefin separation processes, while providing energetic advantages over conventional distillation-based olefin separation technologies.

In addition to facilitating advantaged separation of at least one olefin from at least one paraffin with both high olefin recovery and purity, the separation processes disclosed herein may offer numerous other advantages as well, as discussed in greater detail hereinafter. Foremost, the separation processes disclosed herein are readily configurable to convey the salt ion membrane aqueous salt phase from the salt ion membrane to an absorption device in various manners depending on process-specific factors, such as whether the salt ion membrane aqueous salt phase is primarily transferred across the salt ion membrane (e.g., in a permeate stream) or retained without being transferring across the salt ion membrane (e.g., in a retentate stream). When located in the retentate stream, the salt ion membrane aqueous salt phase may be at least partially separated from one or more olefins in the retentate stream before being circulated to the absorption device for promoting olefin complexation, or the salt ion membrane aqueous salt phase may be conveyed directly within an olefin-lean retentate stream to the absorption device. Salt ion membrane aqueous salt phase may likewise be separated from the permeate stream before being circulated to the absorption device. Further, a permeate stream and/or a retentate stream obtained from the salt ion membrane, or a salt ion membrane aqueous salt phase obtained therefrom, may be further processed (conditioned) to increase or decrease an olefin concentration or olefin absorption capacity as process needs dictate. Particular process configurations are discussed in greater detail hereinbelow in reference to the drawings.

Moreover, the separation processes disclosed herein may be conducted with a one-to-one ratio of salt ion membrane and separation device, which may afford capital equipment savings and process simplification relative to membrane cascades employing multiple membranes. Preferably, the separation processes may be conducted with one salt ion membrane and one absorption device in a given process stream. Of course, multiple process streams may be separated in parallel, if desired, with one salt ion membrane and one absorption device being housed in each process stream.

Further advantageously, the separation processes disclosed herein may circulate the salt ion membrane aqueous salt phase and any complexed olefins contained therein as a liquid stream. Circulation of complexed olefins as a liquid stream may provide significant advantages over circulating or recycling gas streams or mixed gas-liquid streams comprising one or more uncomplexed olefins. Liquid circulation pumps capable of circulating a liquid stream are considerably less complex and less expensive to operate than are compressors and like capital equipment needed to pressurize a gas stream into a state suitable for circulation.

According to various embodiments of the present disclosure, separation processes disclosed herein may comprise: providing a mixed feed stream comprising at least one olefin and at least one paraffin; introducing at least a first portion of the mixed feed stream and a first aqueous salt stream to a salt ion membrane under conditions effective to form at least two phases while contacting the salt ion membrane; obtaining an olefin-rich permeate stream and an olefin-lean retentate stream from the salt ion membrane, the olefin-lean retentate stream comprising at least a portion of the at least one olefin from the mixed feed stream; wherein at least one of the olefin-rich permeate stream and the olefin-lean retentate stream further comprises a salt ion membrane aqueous salt phase; introducing at least a portion of the olefin-lean retentate stream and a second aqueous salt stream to an absorption device under conditions effective to promote olefin extraction into the second aqueous salt stream; obtaining from the absorption device an olefin-rich aqueous salt stream comprising at least a portion of the at least one olefin from the olefin-lean retentate stream, and an olefin-lean hydrocarbon stream comprising at least a portion of the at least one paraffin from the mixed feed stream; and providing at least a portion of the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream. As discussed in further detail herein, the salt ion membrane is more permeable to olefins than to paraffins. Additional details in regard to the foregoing are provided hereinafter.

The second aqueous salt stream introduced to the absorption device may comprise at least a portion of the salt ion membrane aqueous salt phase. The salt ion membrane aqueous salt phase introduced to the absorption device may be sourced from the olefin-rich permeate stream and/or the olefin-lean retentate stream, as discussed further hereinbelow. In particular, the salt ion membrane aqueous salt phase introduced to the absorption device as at least a portion of the second aqueous salt stream may be separated from the olefin-rich permeate stream and/or the olefin-lean retentate stream before being provided as the at least a portion of the second aqueous salt stream. In more specific examples, the olefin-rich permeate stream may further comprise at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream may be obtained from the salt ion membrane aqueous salt phase comprising the olefin-rich permeate stream. In other examples, the olefin-lean retentate stream may comprise at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream may be obtained from the salt ion membrane aqueous salt phase comprising the olefin-lean retentate stream. Further details are provided hereinbelow in reference to the drawings.

Mixed feed streams separable according to the disclosure herein may be a hydrocarbon feed obtained from any source and comprise a mixture of at least one olefin and at least one paraffin. A plurality of olefins and/or a plurality of paraffins may be present in various instances. The at least one olefin may comprise one or more of ethylene, propylene, or one or more higher olefins having least 4 and no greater than about 12 carbon atoms. The higher olefins may be straight-chain (normal or linear) or branched, and an olefin moiety therein may be present at any position within the olefin. Linear alpha olefins (LAOs), including ethylene and/or propylene, and/or internal olefins or vinylidene olefins may be separable from one or more paraffins according to the disclosure herein. Mixtures of more than one type of olefin may be present in the mixed feed stream, including any combination of olefins having differing numbers of carbon atoms and/or olefin isomers (geometric and/or positional isomers), including branched olefins, linear olefins, and differing double bond locations.

Similarly, the one or more paraffins within the mixed feed stream may comprise one or more of methane, ethane, propane, and one or more higher paraffins having at least 4 and no greater than about 12 carbon atoms. Higher paraffins may be linear and/or branched, and the mixed feed stream may comprise any combination of linear paraffins, branched paraffins, cyclic paraffins, and/or paraffins having differing numbers of carbon atoms. The mixed feed stream may comprise one paraffin isomer or multiple paraffin isomers for a given number of carbon atoms. Mixtures of more than one type of paraffin may be present in the mixed feed stream, including any combination of paraffins having differing numbers of carbon atoms and/or paraffin isomers, including branched paraffins, cyclic paraffins, and/or linear paraffins.

Optionally, the mixed feed stream may comprise a gas, such as nitrogen, argon, or any combination thereof.

Further optionally, the mixed feed stream may comprise one or more contaminants, which may interact with the cationic substituent of the metal salt within the salt ion membrane and/or the various aqueous salt streams contacted with one or more components of the mixed feed stream. If present, the concentration of the one or more contaminants may be about 10 wppm or below, or about 1 wppm or below, each based on total mass of the mixed feed stream. Contaminants that may be present include, but are not limited to, hydrogen, hydrocarbons containing an acetylene moiety, heteroatomic organic compounds, heteroatomic species including sulfur, oxygen, mercury or arsenic atoms or ions, such as elemental dioxygen (O2), heteroatom hydrides, (e.g., hydrogen sulfide (H2S) and arsine (AsH3)), or within a carbonaceous compound (e.g., carbon monoxide (CO), carbon dioxide (CO2), ethyl mercaptan (CH3CH2SH) or thiophene (C4H4S)).

If needed, the mixed feed stream may be purified to remove one of more components or contaminants that may interfere with the separation processes disclosed herein. Suitable purification processes may be determined by the type(s) of components or contaminants that are present and will be familiar to persons having ordinary skill in the art.

The mixed feed stream may be provided to the salt ion membrane as a vapor, a liquid, or a combination thereof in any ratio of vapor to liquid. The temperature of the mixed feed stream when contacting the salt ion membrane may range from about 5° C. to about 80° C., or from about 20° ° C. to about 70° ° C., or from about 40° C. to about 65° C. The pressure of the mixed feed stream may range from about 2 bar to about 40 bar, or about 5 bar to about 30 bar, or about 8 bar to about 25 bar.

The concentration of olefins in the mixed feed stream may range from about 1 wt % to about 99 wt %, or about 5 wt % to about 95 wt %, or about 10 wt % to about 90 wt %, each based on total mass of the mixed feed stream. Paraffins may constitute the balance of the mixed feed stream, and thus may comprise at least about 1 wt % and no greater than about 99 wt % of the mixed feed stream.

The first and second aqueous salt streams may each comprise a metal salt capable of forming a complex with the at least one olefin. The metal salt may comprise a copper salt, a silver salt, or any combination thereof, such as a Ag (I) salt, a Cu (I) salt, or any combination thereof. Suitable anion forms for the metal salt may include but are not limited to, nitrate, chlorate, tetrafluoroborate, and trifluoroacetate anion, preferably nitrate. Both the first and second aqueous salt streams may comprise silver nitrate in particular examples. The concentration of metal salt in the first and second aqueous salt streams may range from about 0.5 M to about 10 M, or about 1 M to about 9 M, or about 3 M to about 8 M.

Compositionally, the first and second aqueous salt streams may be similar to one another and comprise the same metal salt(s), with the exception that the second aqueous salt stream may have a lower olefin concentration than does the first aqueous salt stream (unless both the first and second aqueous salt streams comprise substantially no olefins). More typically, both the first and second aqueous salt streams comprise at least some olefins, and the second aqueous salt stream has a lower olefin concentration. At least a portion of the second aqueous salt stream may comprise a salt ion membrane aqueous salt phase obtained from the olefin-lean retentate stream and/or the olefin-rich permeate stream, optionally after further conditioning thereof.

The olefin concentration of the first and second aqueous salt streams may depend on the nature of and conditions within the absorption device, as well as conditions outside the absorption device and further processing taking place outside the absorption device. Factors influencing the olefin concentration in the first and second aqueous salt streams may include, for example, temperature, pressure, number of extraction stages, concentration of the metal salt, particularly the concentration of the metal salt in the second aqueous salt stream provided to the absorption device, the olefin concentration in the olefin-lean retentate stream provided to the absorption device, and the relative mass rates of introduction of the second aqueous salt stream and the olefin-lean retentate stream introduced to the absorption device.

A concentration of olefins in the first and second aqueous salt streams may range from about 0.5 mol % to about 20.0 mol % within the condition ranges described herein. The olefin concentration may also depend upon the particular olefin(s) that is/are present in the mixed feed stream, as each may have its own distinct equilibrium behavior. For example, at 30° C. and 10 bar in a 7 M solution of silver nitrate, the solubility of ethylene is about 9 mol %, while the solubility of propylene is about 11 mol %. At 30° C. and 3 bar in a 4 M solution of silver nitrate, the solubility of propylene is about 3 mol %, while the solubility of 1-butene is about 5 mol %. The pressure in these examples is with reference to a single, pure olefin in a vapor phase. Mixtures of olefins may adhere to the equilibrium value for each pure component according to its specific concentration in the mixed feed stream.

In addition to one or more olefins, the first and second aqueous salt streams may also comprise one or more paraffins. When present, the one or more paraffins may be present at a concentration that is at least an order of magnitude lower than that of the one or more olefins, due primarily to the phase equilibria of these compounds and the lack of complexation of the one or more paraffins by the metal salt. Otherwise, factors affecting the paraffin concentrations in the first and second aqueous salt streams are similar to those described above for olefins. In addition, the first and second aqueous salt streams optionally may comprise one or more of the contaminants that may be present in the mixed feed stream.

Conditions effective to form at least two phases while contacting the salt ion membrane may include any combination of conditions that result in the mixed feed stream and the first aqueous salt stream forming two or more different phases. The mixed feed stream and the first aqueous salt stream contacting the salt ion membrane may form two liquid phases, a liquid phase and a gas phase, or two gas phases. Three or more phases may be present in some instances. Additional details are provided below.

Salt ion membranes suitable for use in the disclosure herein are facilitated transport membranes that comprise at least one metal salt within their membrane structure. Examples of suitable salt ion membranes are described in U.S. Pat. Nos. 10,507,435; 10,258,929; 9,782,724; and 7,361,800, and U.S. Patent Application Publication 2018/0093230, each of which is incorporated herein by reference. Other suitable salt ion membranes are described in further detail in U.S. Pat. No. 10,569,233 and U.S. Patent Application Publications 2017/0354918, 2018/0001277, and 2018/0001268, each of which are also incorporated herein by reference as well. The at least one metal salt associated with the membrane structure may also be a metal salt suitable for incorporation in the first and second aqueous salt streams for promoting olefin complexation. Additional salt ion membrane details follow hereinafter. Suitable salt ion membranes may be more permeable to olefins than to paraffins.

When a first side of the salt ion membrane is contacted with a mixed feed stream and a first aqueous salt stream, at least a portion of the one or more olefins from the mixed feed stream may migrate across the salt ion membrane to a second side of the salt ion membrane and the one or more paraffins may be substantially retained upon the first side of the salt ion membrane. Therefore, the first side of the salt ion membrane may be referred to herein as the “retentate side” of the salt ion membrane, and the second side of the salt ion membrane may be referred to as the “permeate side” of the salt ion membrane.

Suitable salt ion membranes may include “fixed site” or “supported liquid” types, each of which may comprise a copper (I) salt, a silver (I) salt, or any combination thereof to facilitate transport of at least one olefin from the retentate side of the salt ion membrane to the permeate side of the salt ion membrane.

U.S. Patent Application Publication US 2018/0001277 and U.S. Pat. No. 10,258,929 describe suitable salt ion membranes comprising a carboxylic acid-functionalized polyimide, in which the carboxylic acid functional groups are ion-exchanged or chelated with metal cations such as silver (I) or copper (I) cations. The salt ion membranes may comprise a relatively porous, thin, dense skin layer fabricated from a polyimide, a blend of two or more different polyimides or a blend of a polyimide and a polyethersulfone, and a relatively porous, thin, dense skin layer of comprising a hydrophilic polymer such as chitosan or sodium alginate, a metal salt (e.g., silver nitrate) or a mixture of a metal salt (e.g., silver nitrate) and hydrogen peroxide.

U.S. Patent Application Publication 2017/0354918 describes suitable salt ion membranes comprising a relatively hydrophilic, nanoporous support membrane, a hydrophilic polymer inside the pores of the nanoporous support membrane, a thin, nonporous, hydrophilic polymer layer coated on the surface of the support membrane, and one or more metal salts incorporated in the hydrophilic polymer on the surface of the support membrane and in the hydrophilic polymer inside the pores of the nanoporous support membrane. The average pore diameter of the nanoporous support membrane may be about 10 nm or less. The hydrophilic polymer comprising the support membrane may include polymers such as, for example, polyethersulfone (PES), a blend of polyethersulfone and polyimide, cellulose acetate, cellulose triacetate, and a blend of cellulose acetate and cellulose triacetate. The hydrophilic polymer within the pores may include polymers such as, for example, chitosan, sodium carboxylmethyl-chitosan, carboxylmethyl-chitosan, hyaluronic acid, sodium hyaluronate, carbopol, polycarbophil calcium, poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), sodium alginate, alginic acid, poly(vinyl alcohol) (PVA), poly(ethylene oxide) (PEO), poly(ethylene glycol) (PEG), poly(vinylpyrrolidone) (PVP), gelatin, carrageenan, sodium lignosulfonate, and mixtures thereof. The nanoporous support membrane can be either an asymmetric integrally skinned membrane or a thin film composite membrane with either flat sheet (spiral wound) or hollow fiber geometry. Again, metal salts such as Cu (I), Ag (I), or any combination thereof may be present in the membrane.

U.S. Pat. No. 10,569,233 describes suitable salt ion membranes comprising a nanoporous polyethersulfone/polyvinylpyrrolidone blend support membrane, a hydrophilic polymer inside nanopores of the support membrane, a hydrophilic polymer coating layer on a surface of the support membrane and metal salts in the hydrophilic polymer coating layer and in the hydrophilic polymer inside the nanopores of the support membrane. Again, metal salts such as Cu (I), Ag (I), or any combination thereof may be present in the membrane.

U.S. Pat. No. 7,361,800 describes suitable salt ion membranes comprising a polysaccharide having Ag (I), Cu (I), or any combination thereof bound thereto. Examples of suitable polysaccharides may include natural polysaccharides such as alginic acid, pectic acid, chondroitin, hyaluronic acid and xanthan gum; cellulose, chitin, pullulan, derivatives such as C1-6 esters, ethers and alkylcarboxy derivatives thereof and phosphates of these natural polysaccharides such as partially methyl esterified alginic acid, carbomethoxylated alginic acid, phosphorylated alginic acid and aminated alginic acid; salts of anionic cellulose derivatives such as carboxymethyl cellulose, cellulose sulfate, cellulose phosphate, sulfoethyl cellulose and phosphonoethyl cellulose; and semi-synthetic polysaccharides such as guar gum phosphate and chitin phosphate. Specific examples of suitable polysaccharides include those composed of salts of chitosan and its derivatives such as N-acylated chitosan, chitosan phosphate and carbomethoxylated chitosan. The salt ion membranes may also include blends of a polysaccharide as a majority component (e.g., at least about 60 wt % based on total mass) and one or more other polymers as a minority component (e.g., up to about 40 wt %), such as, for example, polyvinyl alcohol (PVA), neutral polysaccharides such as starch and pullulan, and grafted ionized polysaccharides obtained by grafting a hydrophilic vinyl monomer such as acrylic acid.

U.S. Pat. No. 9,782,724 describes a suitable supported liquid salt ion membrane. In the case of a supported liquid salt ion membrane, the first aqueous salt stream may serve as a replenishment liquid for maintaining membrane performance. The membrane may similarly comprise natural or functionalized polysaccharides, such as chitosan, as discussed above. Metal salts such as Cu (I), Ag (I), or any combination thereof may be present in the supported liquid within the salt ion membrane.

U.S. Patent Application Publication 2018/0111099 describes suitable salt ion membranes incorporating fluorinated silver ionomers as a membrane material. The ionomers may contain pendant sulfonic acid groups.

The salt ion membrane may be maintained under conditions similar to those at which the mixed feed stream and the first aqueous salt stream are supplied thereto. Thus, the salt ion membrane may be maintained at a temperature of about 5° C. to about 80° ° C., or from about 20° ° C. to about 70° C., or from about 40° C. to about 65° C., and at a pressure of about 2 bar to about 40 bar, or about 5 bar to about 30 bar, or about 8 bar to about 25 bar.

A pressure drop occurs as at least a portion of the one or more olefins pass through the salt ion membrane from the retentate side to the permeate side. That is, the permeate side may have a lower olefin partial pressure than does the retentate side of the salt ion membrane. The pressure drop may range from about 0.2 to about 2 bar, or about 0.5 bar to about 1.5 bar. Alternately, the pressure drop may be at least about 1.5 bar. The olefin partial pressure on the permeate side of the salt ion membrane may range from about 1 bar to about 10 bar, and a correspondingly higher pressure may be present on the retentate side.

The olefin-rich permeate stream and the olefin-lean retentate stream may both be obtained under conditions similar to those associated with the mixed feed stream, the first aqueous salt stream, and the salt ion membrane. Thus, olefin-rich permeate stream and the olefin-lean retentate stream may be independently obtained at a temperature of about 5° C. to about 80° C., or from about 20° ° C. to about 70° C., or from about 40° ° C. to about 65° C., and at a pressure of about 2 bar to about 40 bar, or about 5 bar to about 30 bar, or about 8 bar to about 25 bar. Salt ion membrane aqueous salt phase may be obtained with at least one of the olefin-rich permeate stream or the olefin-lean retentate stream.

A concentration of olefins in the olefin-rich permeate stream may be at least about 90 wt %, or at least about 95 wt %, or at least about 99 wt %, or at least about 99.5 wt %, or at least about 99.9 wt %, based on total hydrocarbons in the olefin-rich permeate stream and excluding any water (from the salt ion membrane aqueous salt phase). Non-olefin components from the mixed feed stream may constitute the balance of total hydrocarbons in the olefin-rich permeate stream. At least about 90 wt %, or at least about 95 wt %, or at least about 99 wt %, or at least about 99.5 wt %, or at least about 99.9 wt % of the one or more olefins in the mixed feed stream may be extracted into the olefin-rich permeate stream, based on total olefins in the mixed feed stream.

A concentration of olefins in the olefin-lean retentate stream may range from about 1 wt % to about 90 wt %, or about 5 wt % to about 80 wt %, or about 10 wt % to about 70 wt %, or about 10 wt % to about 50 wt %, based on total hydrocarbons in the olefin-lean retentate stream and excluding any water (from the salt ion membrane aqueous salt phase). Non-olefin components from the mixed feed stream may constitute the balance of total hydrocarbons in the olefin-rich permeate stream.

The second aqueous salt stream may have a lower olefin concentration than does the first aqueous salt stream (unless both the first and second aqueous salt streams comprise substantially no olefins). In non-limiting examples, the first and second aqueous salt streams may both comprise substantially no olefins if both streams are supplied from a fresh aqueous salt solution, such as to provide makeup volume. More typically, at least one of, and preferably both of, the first and second aqueous salt streams comprise at least some olefins, provided that the second aqueous salt stream comprises a lower olefin concentration. The first and second aqueous salt streams may be obtained by recycling salt ion membrane aqueous salt phase, optionally with further conditioning thereof, as discussed in further detail hereinafter. Process configurations suitable for recycling the salt ion membrane aqueous salt phase are discussed in more detail hereinafter. Fresh aqueous salt solution or water may also be supplied as a makeup stream in combination with recycled salt ion membrane aqueous salt phase provided as the first and/or second aqueous salt stream, such as to increase the volume for either of these streams.

Provided that the second aqueous salt stream is obtained from the salt ion membrane aqueous salt phase, the olefin concentration in the second aqueous salt stream may range from about 0.1 mol % to about 20 mol %, provided that the first aqueous salt stream has a higher olefin concentration. In more specific examples, the olefin concentration in the second aqueous salt stream may range from about 0.5 mol % to about 10 mol %, or about 0.5 mol % to about 5 mol % or about 0.5 mol % to about 2 mol %. The olefin concentration of the second aqueous salt stream may be further adjusted to best support operation of a particular absorption device, examples of which are discussed further below, and an amount of olefins extracted within the absorption device and/or the rigor needed when performing a conditioning operation to achieve a particular olefin concentration in at least a portion of the second aqueous salt stream. It may be desirable to balance obtaining a concentration of olefins in the second aqueous salt stream that is as low as possible (to support good extraction within the absorption device) while maintaining the cost of conditioning at a reasonable level. For example, extensive heating during conditioning to achieve an olefin concentration that is as low as possible may provide unacceptable process economics, when less extensive heating may afford an acceptable (but not lowest possible) olefin concentration but at a more reasonable cost. Additional details concerning conditioning are provided further below.

Illustrative disclosure regarding extraction of olefins using a suitable metal salt and absorption device may be found in U.S. Pat. Nos. 4,174,353 and 6,395,952, each of which is incorporated herein by reference in its entirety. Suitable absorption devices may include any construct capable of contacting two liquid phases with one another to promote extraction of at least one component from a first liquid into a second liquid. Examples of suitable absorption devices may include, for example, an absorption column (tower), a rotating packed bed contactor, and a compact contacting unit. By way of non-limiting example, suitable rotating packed bed contactors are described in further detail in U.S. Pat. No. 4,283,255, which is incorporated herein by reference in its entirety. By way of further non-limiting example, suitable compact contacting units are described in U.S. Pat. No. 8,899,557, which is also incorporated herein by reference in its entirety. Unless otherwise specified, the absorption device may be operated under temperature and pressure conditions similar to those of the salt ion membrane.

An olefin-rich aqueous salt stream and an olefin-lean hydrocarbon stream may be obtained from the absorption device. Thus, the olefin-rich aqueous salt stream and the olefin-lean hydrocarbon stream may both be obtained under conditions similar to those associated with the mixed feed stream, the first aqueous salt stream, and the salt ion membrane. Accordingly, olefin-rich aqueous salt stream and the olefin-lean hydrocarbon stream may be independently obtained at a temperature of about 5° C. to about 80° C., or from about 20° C. to about 70° C., or from about 40° C. to about 65° C., and at a pressure of about 2 bar to about 40 bar, or about 5 bar to about 30 bar, or about 8 bar to about 25 bar.

The olefin-rich aqueous salt stream may comprise at least about 5 wt % of the at least one olefin present in the olefin-lean retentate stream introduced to the absorption device. In other examples, the olefin-rich aqueous salt stream may comprise at least about 20 wt %, or at least about 50 wt %, or at least about 90 wt %, or at least about 99 wt % of the at least one olefin present in the olefin-lean retentate stream. Various factors may influence the amount of olefins present in the olefin-rich aqueous salt stream obtained from the absorption device such as, for example, the concentration of the at least one olefin in the mixed feed stream, and the amount of olefins removed from the mixed feed stream as the olefin-rich permeate stream.

Once obtained from the absorption device, the olefin-rich aqueous salt stream may be returned to the salt ion membrane as at least a portion of the first aqueous salt stream to promote further separation of at least one olefin and at least one paraffin from the mixed feed stream.

Optionally, at least a portion of the mixed feed stream may be introduced directly to the absorption device. In instances where a portion of the mixed feed stream is introduced directly to the absorption device, the olefin-rich aqueous salt stream may comprise at least about 5 wt %, or at least about 20 wt %, or at least about 50 wt %, or at least about 90 wt %, or at least about 99 wt % of the at least one olefin present in the olefin-lean retentate stream and the portion of the mixed feed stream introduced directly to the absorption device.

The olefin concentration in the olefin-lean hydrocarbon stream is lower than the olefin concentration in the olefin-lean retentate stream introduced to the absorption device and/or an olefin concentration combined in the olefin-lean retentate stream and mixed feed stream introduced to the absorption device. The olefin-lean hydrocarbon stream may comprise about 20 wt % or less olefins, or about 10 wt % or less olefins, or about 5 wt % or less olefins, or about 2 wt % or less olefins, or about 1 wt % or less olefins, or about 0.5 wt % or less olefins, each based on total mass of the olefin-lean hydrocarbon stream. Preferably, the olefin-lean hydrocarbon stream may be substantially olefin-free.

Further, the olefin-lean hydrocarbon stream obtained from the absorption device may comprise at least a majority of the one or more paraffins present in the mixed feed stream. In non-limiting examples, the olefin-lean hydrocarbon stream may comprise at least about 75 wt % of the paraffins in the mixed feed stream, or at least about 80 wt %, or at least about 85 wt %, or at least about 90 wt %, or at least about 95 wt %, or at least about 99 wt %, each based upon total mass of paraffins in the mixed feed stream. Other hydrocarbons and/or impurities within the mixed feed stream may also be removed within the olefin-lean hydrocarbon stream obtained from the absorption device.

In discussing additional aspects of the foregoing in further detail, the processes of the present disclosure will be described in reference to the FIGS.

FIGS.1A and1Bare block diagrams showing an olefin separation process of the present disclosure, in which a second aqueous salt stream is externally supplied. As shown inFIG.1A, process100provides a mixed feed stream comprising at least one olefin and at least one paraffin in line102and a first aqueous salt stream in line104, each of which are introduced to and contact salt ion membrane106. Within salt ion membrane106there resides feed-receiving zone108that appropriately distributes the mixed feed stream and the first aqueous salt stream in multi-phase flow over a feed-side surface of membrane material112. Multi-phase flow may be established with appropriate consideration of the composition and conditions of the mixed feed stream in line102and the first aqueous salt stream in line104when mixed, either within salt ion membrane106as shown inFIG.1A, or optionally prior to entering salt ion membrane106. The multiple phases may comprise at least a hydrocarbon phase containing olefins and an aqueous salt phase. The hydrocarbon phase may be a vapor, or a liquid that is at least partially immiscible in the aqueous salt phase. Alternately, there may be both a vapor hydrocarbon phase and a liquid hydrocarbon phase, each containing olefins and that is at least partially immiscible in the aqueous salt phase. In some embodiments, there may be multiple liquid hydrocarbon phase that are at least partially immiscible in each other and in the aqueous salt phase, optionally in further combination with a vapor hydrocarbon phase containing olefins.

At least a portion of the olefins in the mixed feed stream, along with a small fraction of paraffins within feed-receiving zone108, move through membrane material112to permeate-receiving zone110. The olefins passing through membrane material112are then removed from salt ion membrane106as an olefin-rich permeate stream in line114. The olefin-rich permeate stream may be further purified (not shown), if desired. The olefin-rich permeate stream obtained from permeate-receiving zone110and removed in line114may comprise at least a hydrocarbon-rich phase containing at least a portion of the one or more olefins from the mixed feed stream. The hydrocarbon-rich phase within the olefin-rich permeate stream may be vapor, liquid, or any combination thereof.

Optionally, the olefin-rich permeate stream may further comprise at least a portion of a salt ion membrane liquid aqueous salt phase contacted with salt ion membrane106. The location where the salt ion membrane aqueous salt phase is obtained may depend upon the specific type of salt ion membrane employed, the specific components, phases and the conditions that are present within permeate-receiving zone110, particularly the pressure within permeate-receiving zone110. For example, certain types of salt ion membrane106may allow co-permeation of some aqueous salt phase through membrane material112. In various embodiments, the olefin-rich permeate stream within permeate-receiving zone110and removed in line114may be a hydrocarbon-rich vapor phase containing olefins and a salt ion membrane aqueous salt phase, or the olefin-rich permeate stream may be a hydrocarbon-rich liquid phase containing olefins and a salt ion membrane aqueous salt phase in which the hydrocarbon-liquid rich liquid phase is at least partially immiscible. In another embodiment, the olefin-rich permeate stream may include a hydrocarbon-rich vapor phase containing olefins, a hydrocarbon-rich liquid phase containing olefins, and a salt ion membrane aqueous salt phase in which the hydrocarbon-rich liquid phase containing olefins is at least partially immiscible with the other phases. More specific examples of processes in which the olefin-rich permeate stream also contains salt ion membrane aqueous salt phase are discussed in reference to the further FIGS. below.

In accordance with the foregoing, the quantity of olefins in the mixed feed stream is decreased. The residual mixed feed stream and the first aqueous salt stream remaining in feed-receiving zone108may still contain at least a portion of the one or more olefins originally provided with the mixed feed stream, and a mixture of the residual mixed feed stream and the first aqueous salt stream may exit salt ion membrane106as an olefin-lean retentate stream in line116. The olefin-lean retentate stream in line116may comprise at least a hydrocarbon-lean phase containing at least some olefins that may be vapor, liquid, or any combination thereof, or may contain two immiscible hydrocarbon liquid phases, optionally in combination with a vapor phase. In process100, the olefin-lean retentate stream in line116further includes at least a portion of a salt ion membrane liquid aqueous salt phase contacted with salt ion membrane106, which may represent at least a majority of the salt ion membrane aqueous salt phase or substantially all of the salt ion membrane aqueous salt phase.

The olefin-lean retentate stream in line116is the further directed to absorption device122via line120. Optionally, before entering line120, the olefin-lean retentate stream may be split into two portions, with a first portion of the olefin-lean retentate stream being provided to absorption device122via line120and a second portion of the olefin-lean retentate stream being diverted away from absorption device122as a purge stream or product stream in line118. Components within the purge stream or product stream obtained from line118may be further processed, if desired.

A second aqueous salt stream in line124is also provided to absorption device122along with the portion of the olefin-lean retentate stream in line120. The second aqueous salt stream may have a lower olefin concentration than does the first aqueous salt stream. As shown, the second aqueous salt stream is provided in line124without being recycled from another source, such as from a separate reservoir of aqueous salt solution. In other embodiments, the second aqueous salt stream may comprise at least a portion of the salt ion membrane aqueous salt phase, as discussed hereinbelow in reference to subsequent FIGS. That is, the salt ion membrane aqueous salt phase may be recycled and provided to line124as at least a portion of the second aqueous salt stream, either from olefin-rich permeate stream (further recycling details shown inFIGS.2-5) or olefin-lean retentate stream (further recycling details shown inFIGS.7-9). Optionally, recycled salt ion membrane aqueous salt phase provided as the second aqueous salt stream may be further supplemented by an aqueous salt solution or water provided from an external source, such as within a makeup stream, if a larger volume of second aqueous salt solution is needed to promote effective contacting within absorption device122.

Within absorption device122, the portion of the olefin-lean retentate stream is contacted with the second aqueous salt stream under conditions effective to produce an olefin-rich aqueous salt stream containing at least a portion of the one or more olefins from the olefin-lean retentate stream. The olefin-rich aqueous salt stream exits absorption device122in line104, and an olefin-lean hydrocarbon product stream comprising at least a portion of the one or more paraffins from the olefin-lean retentate stream is removed from absorption device122via line126. Establishing suitable conditions in absorption device122for producing the olefin-rich aqueous salt stream may include correlating the composition, flowrate, pressure and temperature of the second liquid aqueous salt stream in line124with those same properties of the portion of the olefin-lean retentate stream in line120. Additional conditions that may be considered include, for example, the geometry of absorption device122and the temperature and pressure within absorption device122. Operation of absorption device122may be conducted in vapor-liquid, liquid-liquid or vapor-liquid-liquid mode as dictated by application-specific requirements, primarily based on the phase characteristics of the portion of the olefin-lean retentate stream provided in line120.

After exiting absorption device122, the olefin-rich aqueous salt stream in line104may be returned to salt ion membrane106for further olefin separation to take place therefrom. The olefin-rich aqueous salt stream also provides a source for the first aqueous salt stream provided to salt ion membrane106. Although not shown inFIG.1A, it is to be appreciated that additional first aqueous salt stream may be provided from an external source of aqueous salt solution or water added as a makeup stream. As shown inFIG.1A, the olefin-rich aqueous salt stream is returned to salt ion membrane106separately from the mixed feed stream in line102. It is to be appreciated, however, that the olefin-rich aqueous salt stream and the mixed feed stream may be combined with one another, if desired, prior to being returned to salt ion membrane106. Such process configurations are provided herein and discussed further below.

Processes of the present disclosure may further comprise introducing at least a second portion of the mixed feed stream to the absorption device. Such diversion of a mixed feed stream to an absorption device is shown inFIG.1B. Process101ofFIG.1Bis substantially similar to process100ofFIG.1A, except a portion of the mixed feed stream in line102may be diverted to absorption device122via bypass line130. Olefins within the mixed feed stream introduced to absorption device122may similarly be extracted into an olefin-rich aqueous salt stream that is subsequently removed via line104and provided to salt ion membrane106in accordance with the disclosure above. It may become advantageous to divert at least a portion of the mixed feed stream to absorption device122as the olefin concentration therein decreases, such as about 50 wt % or below, or about 35 wt % or below, or about 20 wt % or below, based on total mass of the mixed feed stream. Other elements ofFIG.1Bare substantially similar to those described above in reference toFIG.1Aand are not described again in detail in the interest of brevity. Even if not expressly depicted in subsequent FIGS., it is to be appreciated that a bypass line similar to bypass line130may be incorporated in any of the process configurations described or depicted herein.

In some embodiments, the olefin-rich permeate stream may further comprise at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream may be obtained from the salt ion membrane aqueous salt phase comprising the olefin-rich permeate stream. The salt ion membrane aqueous salt phase provided as at least a portion of the second aqueous salt stream may be conditioned in various manners before being provided as at least a portion of the second aqueous salt stream, as discussed hereinbelow in reference toFIGS.2-5. That is,FIGS.2-5are block diagrams showing various configurations of olefin separation processes of the present disclosure, in which at least a portion of the second aqueous salt stream is provided from a permeate side of the salt ion membrane.

In some embodiments, the olefin-lean retentate stream may further comprise at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream may be obtained from the salt ion membrane aqueous salt phase comprising the olefin-lean retentate stream. The salt ion membrane aqueous salt phase provided as at least a portion of the second aqueous salt stream may be conditioned in various manners before being provided as at least a portion of the second aqueous salt stream, as discussed hereinbelow with reference toFIGS.6A-9. That is,FIGS.6A-9are block diagrams showing various process configurations of olefin separation processes of the present disclosure, in which at least a portion of the second aqueous salt stream is provided from a retentate side of the salt ion membrane.

FIG.2is a block diagram showing an olefin separation process of the present disclosure, in which a salt ion membrane aqueous salt phase associated with the olefin-rich permeate stream is conditioned and supplied as at least a portion of the second aqueous salt stream. In process200ofFIG.2, a mixed feed stream in line202and a first aqueous salt stream in line204are introduced to salt ion membrane206, which may be similar in structure and function to salt ion membrane106(FIG.1), under conditions effective to form at least two phases within salt ion membrane206. Salt ion membrane206produces an olefin-rich permeate stream in line214and an olefin-lean retentate stream in line216. The olefin-rich permeate stream in line214may comprise both a hydrocarbon-rich phase containing one or more olefins from the mixed feed stream and salt ion membrane aqueous salt phase, and the olefin-lean retentate stream in line216may comprise both a hydrocarbon-lean phase containing one or more olefins from the mixed feed stream and salt ion membrane aqueous salt phase. One or both of the olefin-rich permeate stream and the olefin-lean retentate stream may comprise a vapor phase in particular process configurations.

The olefin-rich permeate stream in line214is subjected to conditioning operation228comprising at least one of changing pressure, changing temperature, and separating phases to produce conditioned salt ion membrane aqueous salt phase in line232, which is olefin-lean relative to the salt ion membrane aqueous salt phase in the olefin-rich permeate stream. Conditioning operation228may be conducted such that a lower olefin concentration in the salt ion membrane aqueous salt phase at least temporarily results. The conditioned salt ion membrane aqueous salt phase in line232is supplied as at least a portion of the second aqueous salt solution provided to absorption device222, as discussed further below, and has a lower olefin concentration than that of the first aqueous salt stream in line204. Conditioning operation228also produces a conditioned hydrocarbon-rich stream in line230that may be withdrawn as product. The conditioned hydrocarbon-rich stream may be olefin-rich relative to the mixed feed stream. Conditioning operation228thus may produce at least two phases, typically at least a hydrocarbon phase containing olefins and a liquid phase that is a conditioned salt ion membrane aqueous salt phase. In one embodiment, the hydrocarbon phase containing olefins may be a vapor, or the hydrocarbon phase containing olefins may be a liquid that is at least partially immiscible in the conditioned salt ion membrane aqueous salt phase. In another embodiment, there may be both a vapor hydrocarbon phase containing olefins and a liquid hydrocarbon phase containing olefins that is at least partially immiscible in the conditioned salt ion membrane aqueous salt phase. In other embodiments, there may be multiple liquid hydrocarbon phases containing olefins that are at least partially immiscible in each other and in the conditioned salt ion membrane aqueous salt phase, potentially in further combination with a vapor hydrocarbon phase containing olefins.

The olefin-lean retentate stream in line216is optionally split into two streams, with a portion of both a hydrocarbon-lean phase containing olefins, preferably a vapor phase, and the salt ion membrane aqueous salt phase in line220being directed to absorption device222. The balance of the olefin-lean retentate stream in line216is removed from process200in line218, either as a purge stream or as product stream for further processing, for example.

A second aqueous salt stream in line224is also provided to absorption device222. The second aqueous salt stream in line224may comprise the conditioned salt ion membrane aqueous salt phase in line232and optionally further include a makeup stream comprising an aqueous salt solution or water supplied in line234. Any ratio of conditioned salt ion membrane aqueous salt phase and makeup stream may be introduced to absorption device222. The makeup stream in line234serves to replace water and salt removed from process200, for example, purposefully with the balance of the olefin-lean retentate stream exiting process200in line218, and residual water that is removed with the conditioned hydrocarbon-rich stream comprising one or more olefins in line230and an olefin-lean hydrocarbon stream comprising one or more paraffins removed from process200in line226.

Within absorption device222, the introduced portion of the olefin-lean retentate stream is contacted with the second aqueous salt stream under conditions effective to promote olefin extraction into the second aqueous salt stream, thereby producing an olefin-rich aqueous salt stream that contains at least a portion of at least one olefin from the olefin-lean retentate stream. The olefin-rich aqueous salt stream exits absorption device222and becomes the first aqueous salt stream that is provided to salt ion membrane206via line204. Also obtained from absorption device222is an olefin-lean hydrocarbon stream comprising at least a portion of the one or more paraffins from the olefin-lean product stream, which is removed from process200via line226.

FIG.3is a block diagram showing an olefin separation process of the present disclosure, in which a salt ion membrane aqueous salt phase associated with the olefin-rich permeate stream is conditioned through phase separation and then supplied as at least a portion of the second aqueous salt stream. In process300ofFIG.3, a mixed feed stream in line302and a first aqueous salt stream in line350are mixed under conditions effective to form at least two phases in line304, and the at least two phases are provided as a multi-phase flow to salt ion membrane306. Although shown as being mixed in line304, the mixed feed stream and the first aqueous salt stream may be introduced separately to salt ion membrane306under conditions to establish multi-phase flow as well. As previously described, salt ion membrane306may provide an olefin-rich permeate stream in line316and an olefin-lean retentate stream in line314. In process300, the olefin-rich permeate stream in line316may comprise both a hydrocarbon-rich phase containing at least a portion of the one or more olefins from the mixed feed stream and a salt ion membrane aqueous salt phase. The hydrocarbon-rich phase within the olefin-rich permeate stream may be vapor, liquid, or any combination thereof, preferably a vapor phase containing at least one olefin, in combination with the salt ion membrane aqueous salt phase. The olefin-lean retentate stream in line314may comprise at least a hydrocarbon-lean phase containing at least some olefins that may be vapor, liquid, or any combination thereof, or may contain two immiscible hydrocarbon liquid phases, optionally in combination with a vapor phase. Preferably, the olefin-lean retentate stream in line314comprises both a hydrocarbon-lean vapor phase containing olefins and a salt ion membrane aqueous salt phase.

The olefin-rich permeate stream in line316is provided to conditioning operation317, which includes a phase separation with flash drum318and a pressure increase with first liquid pump324. More specifically, the olefin-rich permeate stream in line316is provided to flash drum318to promote phase separation and create a conditioned hydrocarbon-rich stream comprising one or more olefins in line320that is removed from process300as a product stream, and a conditioned salt ion membrane aqueous salt phase that is olefin-lean in line322. The conditioned salt ion membrane aqueous salt phase in line322has a lower concentration of olefins than the first aqueous salt stream in line350. The lower concentration of olefins in the conditioned salt ion membrane aqueous salt phase may be obtained in view of the phase equilibrium of this system with an appropriate reduction of the olefin partial pressure of the olefin-rich permeate stream in line316.

The conditioned salt ion membrane aqueous salt phase in line322is further provided to first liquid pump324to produce a pressurized, conditioned salt ion membrane aqueous salt phase in line326. The applied pressure is sufficient to move the pressurized conditioned salt ion membrane aqueous salt phase to absorption device336.

Before reaching absorption device336, the pressurized, conditioned salt ion membrane aqueous salt phase in line326is optionally split into two streams. A small portion of the pressurized, conditioned salt ion membrane aqueous salt phase may be removed from process300as an aqueous salt purge stream in line328. The aqueous salt purge stream may facilitate removal of one or more contaminants that may be introduced to process300with the mixed feed stream. Contaminants may react with a metal salt comprising the first or second aqueous salt streams, typically the salt's cation constituent, to form one or more species that is ineffective for absorbing olefins, thus reducing the efficacy of the first and second aqueous salt streams circulating in process300. For example, acetylene, methylacetylene or hydrogen sulfide contaminants present in the mixed feed stream in line302may react with silver ions to form silver acetylides or silver sulfate that are ineffective for absorbing olefins. Such unwanted species may be removed with the aqueous salt purge stream in line328. The aqueous salt purge stream may be discarded or, for example, be sent to a separate facility to reclaim the metal salt or a contaminant-reacted form thereof.

The balance of the pressurized, conditioned salt ion membrane aqueous salt phase in line326is taken into line330, and introduced to absorption device336as a portion of the second aqueous salt stream in line334. A makeup stream comprising an aqueous salt solution or water in line332may further introduce at least a portion of the second aqueous salt stream via line334, wherein the makeup stream is mixed in line334with the balance of the pressurized, conditioned salt ion membrane aqueous salt phase from line330. The makeup stream in line332serves to replace the water and salt removed from process300purposefully in the aqueous salt purge stream in line328, and the water that is removed within the conditioned hydrocarbon-rich stream comprising one or more olefins in line320and olefin-lean hydrocarbon stream comprising at least a portion of the one or more paraffins from the mixed feed stream due to the phase equilibrium of these systems. In alternative embodiments, water and salt may be replaced by introducing such a makeup stream to other locations within process300, and further may be introduced separately to convenient locations as distinct aqueous salt or water streams.

At least a portion of, and preferably the entirety of, the olefin-lean retentate stream in line314comprising a hydrocarbon-lean phase containing at least one olefin, preferably a vapor phase, and a salt ion membrane aqueous salt phase is directed to absorption device336along with the second aqueous salt stream in line334. In process300, absorption device336is shown as a conventional absorption column, within which the hydrocarbon-lean phase containing the at least one olefin and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon product stream comprising one or more paraffins in line344, and an olefin-rich aqueous salt stream in line346that contains at least a portion of the one or more olefins from the mixed feed stream. In the absorption column, the force of gravity enables countercurrent contacting of the lower density hydrocarbon phase(s), as vapor and/or liquid, as the hydrocarbon phase(s) rise up the absorption column and the higher density aqueous salt stream falls down the absorption column. Hence, the higher density second aqueous salt stream in line334is shown as entering near or proximal to the top of the absorption column, such as within absorber top settling zone338, and the lower density olefin-lean retentate stream in line314is shown as entering near or proximal to the bottom of the absorption column, such as within absorber bottom settling zone342. Any location at which the olefin-lean retentate stream enters an absorption column below the second aqueous salt stream may be satisfactory, however. Absorber top settling zone338may be an open volume that serves to substantially reduce an amount of the higher density aqueous salt solution that may be entrained in the lower density hydrocarbon phase(s) as it exits the absorption column as the olefin-lean hydrocarbon product stream in line344. To that end, particularly when the lower density hydrocarbon phase is a vapor, certain internals known to the skilled practitioner may be placed in absorber top settling zone338to minimize the amount of higher density second aqueous salt stream in the olefin-lean hydrocarbon product stream in line344, such as a de-mister screen. Similarly, absorber bottom settling zone342may be an open volume that serves to substantially reduce the amount of the lower density hydrocarbon phase(s) that may be entrained in the olefin-rich aqueous salt stream as it exits the absorption column via line346. The mass transfer efficiency and stagewise absorption performance of such contacting may be enhanced by including column mixing internals zone340within the absorption column, such as perforated trays or packing elements familiar to persons having ordinary skill in the art. Internals zone340is located in between absorber top settling zone338and absorber bottom settling zone342.

At least a portion of, and preferably all of, the olefin-rich aqueous salt stream that contains at least a portion of the one or more olefins is provided to second liquid pump348via line346. Second liquid pump348increases the pressure of the olefin-rich aqueous salt stream in line346, such pressure being sufficient to provide the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream in line350that is provided to salt ion membrane306.

FIG.4is a block diagram showing an olefin separation process of the present disclosure, in which a salt ion membrane aqueous salt phase associated with the olefin-rich permeate stream is conditioned through both phase separation and a temperature change and then supplied as at least a portion of the second aqueous salt stream. In process400ofFIG.4, a mixed feed stream in line402and a first aqueous salt stream in line452are mixed under conditions effective to form at least two phases in line404, and the at least two phases are provided as a multi-phase flow to salt ion membrane406. Although shown as being mixed in line404, the mixed feed stream and the first aqueous salt stream may be introduced separately to salt ion membrane406under conditions to establish multi-phase flow as well. As previously described, salt ion membrane406may provide an olefin-rich permeate stream in line416and an olefin-lean retentate stream in line414. In process400, the olefin-rich permeate stream in line416may comprise both a hydrocarbon-rich phase containing at least a portion of the one or more olefins from the mixed feed stream and a salt ion membrane aqueous salt phase. The hydrocarbon-rich phase within the olefin-rich permeate stream may be vapor, liquid, or any combination thereof, preferably a vapor phase containing at least one olefin in combination with the salt ion membrane aqueous salt phase. The olefin-lean retentate stream in line414may comprise at least a hydrocarbon-lean phase containing at least some olefins that may be vapor, liquid, or any combination thereof, or may contain two immiscible hydrocarbon liquid phases, optionally in combination with a vapor phase. Preferably, the olefin-lean retentate stream in line414comprises both a hydrocarbon-lean vapor phase containing olefins and a salt ion membrane aqueous salt phase.

The olefin-rich permeate stream in line416is provided to conditioning operation417, which includes a temperature increase with first heat exchanger418, a phase separation with flash drum422, a pressure increase with first liquid pump428, and a temperature decrease with second heat exchanger432. More specifically, the olefin-rich permeate stream in line416is provided to first heat exchanger418to increase the temperature of the olefin-rich permeate stream and provide a heated olefin-rich permeate stream in line420. The heated olefin-rich permeate stream is then provided to flash drum422to promote phase separation and create a conditioned hydrocarbon-rich stream comprising one or more olefins in line424that is removed from process400as a product stream, and a conditioned salt ion membrane aqueous salt phase that is olefin-lean in line426. The conditioned salt ion membrane aqueous salt phase in line426has a lower concentration of olefins than the first aqueous salt stream in line452. The lower concentration of olefins in the conditioned salt ion membrane aqueous salt phase may be obtained in view of the phase equilibrium of this system. As a result of heating and flashing, one or more olefins are transferred from the salt ion membrane aqueous salt phase into the conditioned hydrocarbon-rich stream exiting process400in line426.

The conditioned salt ion membrane aqueous salt phase in line426is further provided to first liquid pump428to produce a pressurized, conditioned salt ion membrane aqueous salt phase in line430. The applied pressure is sufficient to move the pressurized conditioned salt ion membrane aqueous salt phase to absorption device444after passing through second heat exchanger432. Second heat exchanger432decreases the temperature of the conditioned salt ion membrane aqueous salt phase and provides a further conditioned salt ion membrane aqueous salt phase in line434. The cooling operation, by virtue of the phase equilibrium of the system, increases the capacity of the further conditioned salt ion membrane aqueous salt phase to absorb one or more olefins upon being introduced to absorption device444.

Before reaching absorption device444, the further conditioned salt ion membrane aqueous salt phase in line434is optionally split into two streams. A small portion of the further conditioned salt ion membrane aqueous salt phase may be removed from process400as an aqueous salt purge stream in line436. The aqueous salt purge stream may facilitate removal of one or more contaminants, as previously described above for process300. The balance of the further conditioned salt ion membrane aqueous salt phase in line434is taken into line438, and introduced to absorption device444as a portion of the second aqueous salt stream in line442. A makeup stream in line440may further introduce at least a portion of the second aqueous salt stream via line442, wherein the makeup stream is mixed in line442with the balance of the further conditioned salt ion membrane aqueous salt phase in line438. The makeup stream may be introduced at alternative locations and for the purposes discussed above in reference to process300.

At least a portion of, and preferably the entirety of, the olefin-lean retentate stream in line414comprising a hydrocarbon-lean phase containing olefins, preferably a vapor phase, and a salt ion membrane aqueous salt phase is directed to absorption device444along with the second aqueous salt stream in line442. In process400, absorption device444is shown as a conventional absorption column, within which the hydrocarbon-lean phase containing olefins and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon product stream comprising one or more paraffins in line446, and an olefin-rich aqueous salt stream in line448that contains at least a portion of the one or more olefins from the mixed feed stream. The absorption column comprising absorption device444may have similar features to that described above for process300.

At least a portion of, and preferably all of, the olefin-rich aqueous salt stream that contains at least a portion of the one or more olefins is provided to second liquid pump450via line448. Second liquid pump450increases the pressure of the olefin-rich aqueous salt stream in line448, such pressure being sufficient to provide the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream in line452that is provided to salt ion membrane406.

FIG.5is a block diagram showing an olefin separation process of the present disclosure, in which a salt ion membrane aqueous salt phase associated with the olefin-rich permeate stream is conditioned through two phase separations and a temperature change and then supplied as at least a portion of the second aqueous salt stream. In process500ofFIG.5, a mixed feed stream in line502and a first aqueous salt stream in line560are combined in line504and are subsequently transferred to line508, wherein there are conditions effective to form at least two phases. The at least two phases in line508are provided as a multi-phase flow to salt ion membrane510. A conditioned hydrocarbon-rich stream comprising one or more olefins is further introduced to line508via line506, as discussed further hereinafter, for reintroduction to salt ion membrane510. Although shown as being combined in line504and forming phases in line508, the mixed feed stream, the first aqueous salt stream, and the conditioned hydrocarbon-rich stream comprising one or more olefins may be introduced separately to salt ion membrane510under alternative conditions to establish multi-phase flow as well. As previously described, salt ion membrane510may provide an olefin-rich permeate stream in line516and an olefin-lean retentate stream in line514. In process500, the olefin-rich permeate stream in line516may comprise both a hydrocarbon-rich phase containing at least a portion of the one or more olefins from the mixed feed stream and a salt ion membrane aqueous salt phase. The hydrocarbon-rich phase within the olefin-rich permeate stream may be vapor, liquid, or any combination thereof, preferably a vapor phase containing at least one olefin in combination with the salt ion membrane aqueous salt phase. The olefin-lean retentate stream in line514may comprise at least a hydrocarbon-lean phase containing at least some olefins that may be vapor, liquid, or any combination thereof, or may contain two immiscible hydrocarbon liquid phases, optionally in combination with a vapor phase. Preferably, the olefin-lean retentate stream in line514comprises both a hydrocarbon-lean vapor phase containing olefins and a salt ion membrane aqueous salt phase.

The olefin-rich permeate stream in line516is provided to conditioning operation517, which includes a first phase separation with first flash drum518, a pressure increase with first liquid pump524, a temperature increase with first heat exchanger528, a second phase separation with second flash drum532, and a temperature decrease with second heat exchanger540. More specifically, the olefin-rich permeate stream in line516is provided to first flash drum518to promote phase separation and create a conditioned hydrocarbon-rich stream comprising one or more olefins in line520that is removed from process500as a product stream, and a conditioned salt ion membrane aqueous salt phase that is olefin-lean in line522. The conditioned salt ion membrane aqueous salt phase in line522is further provided to first liquid pump524to produce a pressurized, conditioned salt ion membrane aqueous salt phase in line526. The applied pressure is sufficient to move the pressurized, conditioned salt ion membrane aqueous salt phase elsewhere in process500, including to at least absorption device552. The pressurized, conditioned salt ion membrane aqueous salt phase in line526is passed through first heat exchanger528to increase the temperature of the pressurized, conditioned salt ion membrane aqueous salt phase, which then enters line530as heated and pressurized, conditioned salt ion membrane aqueous salt phase. The heated and pressurized, conditioned salt ion membrane aqueous salt phase is then provided to second flash drum532to form a conditioned hydrocarbon-rich stream comprising one or more olefins in line506, and a heated, conditioned salt ion membrane aqueous salt phase in line534. The conditioned hydrocarbon-rich stream in line506constitutes a majority of the remaining olefins that are not removed from the olefin-rich permeate stream in first flash drum518. The olefins in the conditioned hydrocarbon-rich stream in line506are recycled to salt ion membrane510after forming two or more phases in line508. For reasons similar to those discussed above, the heated, conditioned salt ion membrane aqueous salt phase in line534has a lower concentration of olefins than does the first aqueous salt stream in line560. The heated, conditioned salt ion membrane aqueous salt phase in line534is then provided to second heat exchanger540to form a further conditioned salt ion membrane aqueous salt phase, which promotes a temperature decrease of the salt ion membrane aqueous salt phase within line542to increase its olefin absorption capacity once introduced to absorption device552.

Before reaching absorption device552, the further conditioned salt ion membrane aqueous salt phase in line542is optionally split into two streams. A small portion of the further conditioned salt ion membrane aqueous salt phase may be removed from process500as an aqueous salt purge stream in line544. The aqueous salt purge stream may facilitate removal of one or more contaminants, as previously described above for process300. The balance of the further conditioned salt ion membrane aqueous salt phase in line542is taken into line546, and introduced to absorption device552as a portion of the second aqueous salt stream in line550. A makeup stream in line548may further introduce at least a portion of the second aqueous salt stream via line550, wherein the makeup stream is mixed in line550with the balance of the conditioned salt ion membrane aqueous salt phase in line546. The makeup stream may be introduced at alternative locations and for the purposes discussed above in reference to process300.

At least a portion of, and preferably the entirety of, the olefin-lean retentate stream in line514comprising a hydrocarbon-lean phase containing olefins, preferably a vapor phase, and a salt ion membrane aqueous salt phase is directed to absorption device552along with the second aqueous salt stream in line550. In process500, absorption device552is shown as a conventional absorption column, within which the hydrocarbon-lean phase containing olefins and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon stream comprising one or more paraffins in line554, and an olefin-rich aqueous salt stream in line556that contains at least a portion of the one or more olefins from the mixed feed. The absorption column comprising absorption device552may have similar features to that described above for process300.

At least a portion of, and preferably all of, the olefin-rich aqueous salt stream that contains at least a portion of the one or more olefins is provided to second liquid pump558via line556. Second liquid pump558increases the pressure of the olefin-rich aqueous salt stream in line556, such pressure being sufficient to provide the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream in line560that is provided to salt ion membrane510.

FIGS.6A and6Bare block diagrams showing an olefin separation process of the present disclosure, in which a second aqueous salt stream is at least partially supplied from an olefin-lean retentate stream. In process600ofFIG.6A, a mixed feed stream comprising at least one olefin and at least one paraffin is supplied in line602and a first aqueous salt stream in line606are provided to salt ion membrane612under conditions effective to form at least two phases therein. Although shown as being introduced to salt ion membrane612separately, it is to be appreciated that the mixed feed stream and the first aqueous salt stream may be premixed in a line before entering salt ion membrane612, including forming at least two phases therein. In addition to the one or more olefins in the mixed feed stream, a conditioned hydrocarbon-rich stream comprising one or more olefins is obtained via recycling and supplied to salt ion membrane612via line604, as discussed hereinafter. Salt ion membrane612produces an olefin-rich permeate stream in line614and an olefin-lean retentate stream in line616. The olefin-rich permeate stream in line614comprises a hydrocarbon-rich phase containing olefins and may optionally further comprise a salt ion membrane aqueous salt phase, and the olefin-lean retentate stream in line616comprises both a hydrocarbon-lean phase, which may be a vapor phase containing olefins, and a salt ion membrane aqueous salt phase. In this case, the olefin-rich permeate stream in line614is withdrawn as a product stream from process600, optionally with further purification thereafter (not shown), if desired.

At least a portion of, and preferably the entirety of the olefin-lean retentate stream in line616is directed to absorption device618, along with a second aqueous salt stream in line634. Makeup stream in line620comprising water or an aqueous salt may be supplied to absorption device618for the reasons discussed above in reference to process300. Within absorption device618, the olefin-lean retentate stream is contacted with the second aqueous salt stream and optionally the makeup stream under conditions effective to produce an olefin-rich aqueous salt stream in line624that contains at least a portion of the one or more olefins from the mixed feed stream, and an olefin-lean hydrocarbon product stream comprising one or more paraffins in line622that is removed from process600.

At least a portion of the olefin-rich aqueous salt stream in line624may be returned to salt ion membrane612via line606as at least a portion of the first aqueous salt stream. The balance of the olefin-rich aqueous salt stream in line624is provided to conditioning operation628. Conditioning operation628produces a conditioned salt ion membrane aqueous salt phase in, which has a lower olefin concentration than that of the first aqueous salt stream in line606. The conditioned salt ion membrane aqueous salt phase may be split into two streams, with a small portion being removed from process600as an aqueous salt solution purge stream in line632for the reasons discussed above in reference to process300. The balance of the conditioned salt ion membrane aqueous salt phase in line630is taken into line634and introduced to absorption device618as at least a portion of the second aqueous salt stream. Conditioning operation628also produces a conditioned hydrocarbon-rich stream comprising one or more olefins that is provided to salt ion membrane612by line604.

Process601ofFIG.6Bis substantially similar to process600ofFIG.6A, except a portion of the mixed feed stream in line602may be diverted to absorption device618via bypass line650. Olefins within the mixed feed stream introduced to absorption device618via bypass line650may similarly be extracted into an olefin-rich aqueous salt stream that is subsequently removed via line624and provided to salt ion membrane612and/or conditioning operation628in accordance with the disclosure above. It may become advantageous to divert at least a portion of the mixed feed stream as the olefin concentration therein decreases, such as about 50 wt % or below, or about 35 wt % or below, or about 20 wt % or below, based on total mass of the mixed feed stream. Other elements ofFIG.6Bare substantially similar to those described above in reference toFIG.6Aand are not described again in detail in the interest of brevity. Again, it is to be emphasized that even if not expressly depicted in subsequent FIGS., it is to be appreciated that a bypass line similar to bypass line650may be incorporated in any of the process configurations described or depicted herein.

FIG.7is a block diagram showing an olefin separation process of the present disclosure, in which a salt ion membrane aqueous salt phase associated with the olefin-lean retentate stream is conditioned through phase separation and two temperature changes and then supplied as at least a portion of the second aqueous salt stream. In process700ofFIG.7, a mixed feed stream in line702and a first aqueous salt stream in line708are provided to salt ion membrane712under conditions effective to form at least two phases therein after being combined as a mixture in line710. Although shown as being introduced to salt ion membrane712as a mixture in line710, it is to be appreciated that the mixed feed stream and the first aqueous salt stream may be introduced to salt ion membrane712separately under conditions effective to form at least two phases therein under multi-phase flow conditions. In addition, a conditioned hydrocarbon-rich stream comprising one or more olefins is obtained via conditioning and supplied to salt ion membrane712via lines704,706, and710, as discussed hereinafter. It is likewise to be appreciated that the conditioned hydrocarbon-rich stream comprising one or more olefins may be introduced directly to salt ion membrane712without first being mixed with other phases in the manner discussed hereinbelow. Salt ion membrane712produces an olefin-rich permeate stream in line714and an olefin-lean retentate stream in line716. The olefin-rich permeate stream in line714comprises a hydrocarbon-rich phase containing olefins and may optionally further comprise a salt ion membrane aqueous salt phase, and the olefin-lean retentate stream in line716comprises both a hydrocarbon-lean phase, which may be a vapor phase containing olefins, and a salt ion membrane aqueous salt phase. In this case, the olefin-rich permeate stream in line714is withdrawn as a product stream from process700, optionally with further purification thereafter (not shown), if desired.

At least a portion of, and preferably the entirety of the olefin-lean retentate stream in line716is directed to absorption device718, along with a second aqueous salt stream in line720. In process700, absorption device718is shown as a conventional absorption column, within which the olefin-lean retentate stream containing olefins and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon stream comprising one or more paraffins in line728, and an olefin-rich aqueous salt stream in line730that contains at least a portion of the one or more olefins from the mixed feed stream. The olefin-rich aqueous salt stream in line730comprises at least a portion of the salt ion membrane aqueous salt phase obtained from the olefin-lean retentate stream provided to absorption device718.

At least a portion of, and preferably the entirety of the olefin-rich aqueous salt stream in line730is provided to conditioning operation737, which includes a pressure increase with liquid pump732, a temperature increase with first heat exchanger738, a phase separation in flash drum742, and a temperature decrease in second heat exchanger746. More specifically, the olefin-rich aqueous salt stream in line730is provided to liquid pump732to increase the pressure and form a pressurized, olefin-rich aqueous salt stream in line734. The applied pressure is sufficient to move the pressurized, olefin-rich aqueous salt phase elsewhere in process700, including to at least absorption device718. A portion of the pressurized, olefin-rich aqueous salt stream in line734is provided as the first aqueous salt stream in line708, and the balance of the pressurized, olefin-rich aqueous salt stream in line734is taken in line736and sent to first heat exchanger738. First heat exchanger738increases the temperature of the pressurized, olefin-rich aqueous salt stream in line736to create a pressurized and heated olefin-rich aqueous salt stream in line740. The pressurized and heated olefin-rich aqueous salt stream in line740is sent to flash drum742to produce a conditioned olefin-rich hydrocarbon phase in line704that may be combined with the mixed feed stream in line706and subsequently supplied to salt ion membrane712. Flash drum742also produces a conditioned salt ion membrane aqueous salt phase that is olefin-lean in line744. The conditioned salt ion membrane aqueous salt phase in line744has a lower concentration of olefins than does the first aqueous salt stream in line708by virtue of the heating and flashing operation, which transfers olefins from the pressurized and heated olefin-rich aqueous salt stream in line740to the conditioned olefin-rich hydrocarbon phase that is recycled in line704.

The conditioned salt ion membrane aqueous salt phase in line744is directed to second heat exchanger746to reduce the temperature of the conditioned salt ion membrane aqueous salt phase and generate a cooled, conditioned salt ion membrane aqueous salt phase that is olefin-lean in line748. Cooling, by virtue of the phase equilibria of these systems, increases the efficacy of the cooled, conditioned salt ion membrane aqueous salt phase in line748to absorb one or more olefins upon its eventual introduction to absorption device718. The cooled, conditioned salt ion membrane aqueous salt phase in line748is optionally split into two streams, with a small portion being removed from process700as an aqueous salt purge stream in line750for the purposes discussed above in reference to process300. The balance of the cooled, conditioned salt ion membrane aqueous salt phase in line748is taken into line752and introduced to absorption device718as at least a portion of the second aqueous salt stream in line720. The second aqueous salt stream in line720may further includes a makeup stream from line754, again for the purposes considered above in regard to process300.

FIG.8is a block diagram showing an olefin separation process of the present disclosure, in which the olefin-lean retentate stream is conditioned through phase separation before being supplied to the absorption device. In process800ofFIG.8, a mixed feed stream in line802and a first aqueous salt stream in line808are provided to salt ion membrane812under conditions effective to form at least two phases therein after being combined as a mixture in line810. Although shown as being introduced to salt ion membrane812as a mixture in line810, it is to be appreciated that the mixed feed stream and the first aqueous salt stream may be introduced to salt ion membrane812separately under conditions effective to form at least two phases therein under multi-phase flow conditions. A conditioned olefin-rich hydrocarbon phase comprising at least one olefin in line804is further provided to salt ion membrane812after being combined with the mixed feed stream in line806. Salt ion membrane812produces an olefin-rich permeate stream in line814and an olefin-lean retentate stream in line816. The olefin-rich permeate stream in line814comprises a hydrocarbon-rich phase containing olefins and may optionally further comprise a salt ion membrane aqueous salt phase, and the olefin-lean retentate stream in line816comprises both a hydrocarbon-lean phase, which may be a vapor phase containing olefins, and a salt ion membrane aqueous salt phase. In this case, the olefin-rich permeate stream in line814is withdrawn as a product stream from process800, optionally with further purification thereafter (not shown), if desired.

At least a portion of, and preferably the entirety of the olefin-lean retentate stream in line816is directed to conditioning operation837, which includes phase separation in first flash drum818, a pressure increase with liquid pump834, a temperature increase with first heat exchanger838, phase separation in second flash drum842, and a temperature decrease in second heat exchanger846. More specifically, the olefin-lean retentate stream in line816is provided to first flash drum818to promote phase separation into an olefin-lean hydrocarbon-rich stream in line822, which may be a vapor stream, and a conditioned salt ion membrane aqueous salt phase in line820. The conditioned salt ion membrane aqueous salt phase in line820is provided to liquid pump834and pressurized to produce a pressurized, conditioned salt ion membrane aqueous salt phase in line836. The applied pressure is sufficient to move the pressurized, olefin-rich aqueous salt phase elsewhere in process800, including to at least absorption device824. At least a portion of, and preferably all of the pressurized, salt ion membrane aqueous salt phase in line836is sent to first heat exchanger838. First heat exchanger838increases the temperature of the pressurized, salt ion membrane aqueous salt phase in line836to create a pressurized and heated salt ion membrane aqueous salt phase in line840. The pressurized and heated salt ion membrane aqueous salt phase in line840is sent to second flash drum842to produce a conditioned olefin-rich hydrocarbon phase in line804that may be combined with the mixed feed stream in line806and subsequently supplied to salt ion membrane812. Second flash drum842also produces a conditioned salt ion membrane aqueous salt phase that is olefin-lean in line844. The conditioned salt ion membrane aqueous salt phase in line844has a lower concentration of olefins than does the first aqueous salt stream in line808by virtue of the heating and flashing operation, which transfers olefins to the conditioned olefin-rich hydrocarbon phase that is recycled in line804.

The conditioned salt ion membrane aqueous salt phase in line844is directed to second heat exchanger846to reduce the temperature of the conditioned salt ion membrane aqueous salt phase and generate a cooled, conditioned salt ion membrane aqueous salt phase that is olefin-lean in line848. Cooling, by virtue of the phase equilibria of these systems, increases the efficacy of the cooled, conditioned salt ion membrane aqueous salt phase in line848to absorb one or more olefins upon its eventual introduction to absorption device824. The cooled, conditioned salt ion membrane aqueous salt phase in line848is optionally split into two streams, with a small portion being removed from process800as an aqueous salt purge stream in line850for the purposes discussed above in reference to process300. The balance of the cooled, conditioned salt ion membrane aqueous salt phase in line848is taken into line852and introduced to absorption device824as at least a portion of the second aqueous salt stream provided via line826. The second aqueous salt stream in line826may further include a makeup stream from line854, again for the purposes considered above in regard to process300.

The second aqueous salt stream in line826and the olefin-lean hydrocarbon rich stream in line822are provided to absorption device824. In process800, absorption device824is shown as a conventional absorption column, within which the olefin-lean hydrocarbon rich stream containing olefins and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon product stream comprising one or more paraffins in line828, and an olefin-rich aqueous salt stream in line830that contains at least a portion of the one or more olefins from the mixed feed stream. The olefin-rich aqueous salt stream in line830comprises at least a portion of the salt ion membrane aqueous salt phase obtained from the olefin-lean retentate stream provided to absorption device824. At least a portion of, or preferably all of the olefin-rich aqueous salt stream in line830is provided to second liquid pump832to increase the pressure sufficiently to move the olefin-rich aqueous salt stream to salt ion membrane812.

FIG.9is a block diagram showing an olefin separation process of the present disclosure, in which the olefin-rich permeate stream is conditioned before being supplied to the absorption device. In process900ofFIG.9, a mixed feed stream in line902and a first aqueous salt stream in line908are provided to salt ion membrane912under conditions effective to form at least two phases therein after being combined as a mixture in line910. Although shown as being introduced to salt ion membrane912as a mixture in line910, it is to be appreciated that the mixed feed stream and the first aqueous salt stream may be introduced to salt ion membrane912separately under conditions effective to form at least two phases therein under multi-phase flow conditions. A conditioned olefin-rich hydrocarbon phase comprising at least one olefin in line904is further provided to salt ion membrane912after being combined with the mixed feed stream in line906. Salt ion membrane912produces an olefin-rich permeate stream in line914and an olefin-lean retentate stream in line916. The olefin-rich permeate stream in line914comprises a hydrocarbon-rich phase containing olefins, preferably a vapor phase, and a salt ion membrane aqueous salt phase, and the olefin-lean retentate stream in line916comprises both a hydrocarbon-lean phase, which may be a vapor phase containing olefins, and a salt ion membrane aqueous salt phase.

At least a portion of, and preferably the entirety of the olefin-lean retentate stream in line916is directed to absorption device918, along with second aqueous salt stream supplied in line920. In process900, absorption device918is shown as a conventional absorption column, within which the olefin-lean retentate stream containing olefins and the second aqueous salt stream are contacted under conditions effective to produce an olefin-lean hydrocarbon product stream comprising one or more paraffins in line928, and an olefin-rich aqueous salt stream in line930that contains at least a portion of the one or more olefins from the mixed feed stream. The olefin-rich aqueous salt stream in line930comprises at least a portion of the salt ion membrane aqueous salt phase obtained from the olefin-lean retentate stream provided to absorption device918.

At least a portion of, or preferably all of the olefin-rich aqueous salt stream in line930is provided to conditioning operation931. Conditioning operation931includes a pressure increase with first liquid pump932, a temperature increase with first heat exchanger950, a phase separation with first flash drum954, and a temperature decrease with second heat exchanger958. The olefin-rich permeate stream in line914is also further conditioned in conditioning operation931, wherein conditioning operation931further includes a phase separation with second flash drum936and a pressure increase with second liquid pump942. More specifically, the olefin-rich aqueous salt stream in line930is provided to first liquid pump932to increase the pressure of the olefin-rich aqueous salt stream to create a pressurized olefin-rich aqueous salt stream in line934. The pressure is sufficient to move the pressurized olefin-rich aqueous salt stream elsewhere in process900, including to absorption device918. The olefin-rich permeate stream in line914is also provided to second flash drum936to form an olefin-rich hydrocarbon product stream, preferably a vapor stream, comprising one or more olefins in line938that is removed from process900, and a conditioned salt ion membrane aqueous salt phase in line940. The conditioned salt ion membrane aqueous salt phase in line940is pressurized with second liquid pump942, and the pressurized salt ion membrane aqueous salt phase in line940is combined in line946with the pressurized olefin-rich aqueous salt stream from line934, thereby providing a mixed conditioned aqueous salt stream in line946.

A portion of the mixed conditioned aqueous salt stream in line946, which is olefin-lean, is introduced via line908as the first aqueous salt stream provided to salt ion membrane912. The balance of the mixed conditioned aqueous salt stream in line946is taken in line948and provided to first heat exchanger950to create a heated, mixed conditioned aqueous salt stream in line952. The heated, mixed conditioned aqueous salt stream in line952is subjected to phase separation in first flash drum954to produce a conditioned hydrocarbon-rich stream in line904, which is provided to salt ion membrane912as described above, and a conditioned salt ion membrane aqueous salt phase in line956. The conditioned salt ion membrane aqueous salt phase in line956has a lower concentration of olefins than does the first aqueous salt stream in line908by virtue of the heating and flashing operation, which transfers olefins to the conditioned hydrocarbon-rich stream that is recycled in line904.

The conditioned salt ion membrane aqueous salt phase in line956is sent to second heat exchanger958to reduce its temperature and generate a cooled, conditioned salt ion membrane aqueous salt phase in line960. Cooling, by virtue of the phase equilibria of these systems, increases the efficacy of the cooled, conditioned salt ion membrane aqueous salt phase in line960to absorb one or more olefins upon its eventual introduction to absorption device918.

The cooled, conditioned salt ion membrane aqueous salt phase in line960is optionally split into two streams, with a small portion being removed from process900as an aqueous salt purge stream in line962for the purposes discussed above in reference to process300. The balance of the cooled, conditioned salt ion membrane aqueous salt phase in line960is taken into line964and introduced to absorption device918as at least a portion of the second aqueous salt stream provided via line920. The second aqueous salt stream in line920may further includes a makeup stream from line966, again for the purposes considered above in regard to process300.

It is to be appreciated that any embodiment herein employing an absorption column may alternately employ an alternative absorption device suitable for contacting a second aqueous salt stream and an olefin-lean retentate stream with one another. Process alternations commensurate with replacement of an absorption column with an alternative absorption device will be within the capabilities of one having ordinary skill in the art.

Embodiments disclosed herein include:A. Processes for separating at least one olefin from at least one paraffin. The processes comprise: providing a mixed feed stream comprising at least one olefin and at least one paraffin; introducing at least a first portion of the mixed feed stream and a first aqueous salt stream to a salt ion membrane under conditions effective to form at least two phases while contacting the salt ion membrane; wherein the salt ion membrane is more permeable to olefins than to paraffins; obtaining an olefin-rich permeate stream and an olefin-lean retentate stream from the salt ion membrane, the olefin-lean retentate stream comprising at least a portion of the at least one olefin from the mixed feed stream; wherein at least one of the olefin-rich permeate stream and the olefin-lean retentate stream further comprises a salt ion membrane aqueous salt phase; introducing at least a portion of the olefin-lean retentate stream and a second aqueous salt stream to an absorption device under conditions effective to promote olefin extraction into the second aqueous salt stream; obtaining from the absorption device an olefin-rich aqueous salt stream comprising at least a portion of the at least one olefin from the olefin-lean retentate stream, and an olefin-lean hydrocarbon stream comprising at least a portion of the at least one paraffin from the mixed feed stream; and providing at least a portion of the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream.

Embodiment A may have one or more of the following additional elements in any combination:

Element 1: wherein the second aqueous salt stream comprises at least a portion of the salt ion membrane aqueous salt phase, the salt ion membrane aqueous salt phase being separated from the olefin-rich permeate stream and/or the olefin-lean retentate stream before being provided as the at least a portion of the second aqueous salt stream.

Element 2: wherein a makeup stream comprising an aqueous salt solution or water is supplied as at least a portion of the second aqueous salt stream.

Element 3: wherein the olefin-rich permeate stream further comprises at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream is obtained from the salt ion membrane aqueous salt phase comprising the olefin-rich permeate stream.

Element 4: wherein the olefin-lean retentate stream comprises at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream is obtained from the salt ion membrane aqueous salt phase comprising the olefin-lean retentate stream.

Element 5: wherein a first portion of the salt ion membrane aqueous salt phase is diverted away from a second portion of the salt ion membrane aqueous salt phase being provided to the absorption device.

Element 6: wherein the second aqueous salt stream has a lower olefin concentration than does the first aqueous salt stream.

Element 7: wherein the second aqueous salt stream comprises at least a portion of the salt ion membrane aqueous salt phase, the salt ion membrane aqueous salt phase being separated from the olefin-rich permeate stream and/or the olefin-lean retentate stream before being provided as the at least a portion of the second aqueous salt stream, and wherein the process further comprises: performing a conditioning operation upon at least a portion of the salt ion membrane aqueous salt phase to produce the lower olefin concentration.

Element 8: wherein the conditioning operation comprises at least one action performed on the salt ion membrane aqueous salt phase selected from the group consisting of a temperature change, a pressure change, a phase separation, and any combination thereof.

Element 9: wherein the conditioning operation comprises at least phase separation of the salt ion membrane aqueous salt phase from a conditioned hydrocarbon-rich stream comprising one or more olefins.

Element 10: wherein the process further comprises introducing at least a portion of the conditioned hydrocarbon-rich stream to the salt ion membrane.

Element 11: wherein the salt ion membrane aqueous salt phase is separated from the conditioned hydrocarbon-rich stream as a hydrocarbon-lean stream, and at least a portion of the hydrocarbon-lean stream is provided to the absorption device as at least a portion of the second aqueous salt stream.

Element 12: wherein at least a portion of the hydrocarbon-lean stream is diverted away from the absorption device as a purge stream or a product stream.

Element 13: wherein the conditioning operation comprises changing a temperature of the salt ion membrane aqueous salt phase at least once.

Element 14: wherein changing the temperature of the salt ion membrane aqueous salt phase at least once comprises: raising the temperature of the salt ion membrane aqueous salt phase from a first temperature to a second temperature to lower an olefin absorption capacity thereof; after raising the temperature of the salt ion membrane aqueous salt phase to the second temperature, performing phase separation to separate the conditioned hydrocarbon-rich stream from the salt ion membrane aqueous salt phase; and after separating the conditioned hydrocarbon-rich stream from the salt ion membrane aqueous salt phase, lowering the temperature of the salt ion membrane aqueous salt phase from the second temperature to a third temperature to at least partially restore the olefin absorption capacity.

Element 15: wherein the first temperature and the third temperature are about equal.

Element 16: wherein the process further comprises performing a first phase separation prior to raising the temperature and separating a first conditioned hydrocarbon-rich stream comprising one or more olefins from the salt ion membrane aqueous salt phase.

Element 17: wherein the process further comprises performing phase separation upon the olefin-lean retentate stream and separating an olefin-lean hydrocarbon-rich stream from the salt ion membrane aqueous salt phase prior to raising the temperature of the salt ion membrane aqueous salt phase; and introducing at least a portion of the olefin-lean hydrocarbon rich stream to the absorption device.

Element 18: wherein the process further comprises raising pressure of the salt ion membrane aqueous salt phase prior to providing the salt ion membrane aqueous salt phase as at least a portion of the second aqueous salt stream.

Element 19: wherein at least a portion of the salt ion membrane aqueous salt phase is diverted away from the absorption device as a purge stream or a product stream.

Element 20: wherein the process further comprises introducing at least a second portion of the mixed feed stream to the absorption device.

Element 21: wherein the first and second aqueous salt streams comprise a silver (I) salt, a copper (I) salt, or any combination thereof.

Element 22: wherein the first and second aqueous salt streams comprise silver nitrate.

Element 23: wherein the salt ion membrane and the first and second aqueous salt streams each comprise one or more metal salts that are the same.

Element 24: wherein one or more olefins are obtained from the olefin-rich permeate stream at a purity of at least about 95 wt %, based on total hydrocarbons in the olefin-rich permeate stream.

Element 25: wherein the olefin-rich permeate stream contains at least about 95 wt % of the one or more olefins in the mixed feed stream, based on total olefins in the mixed feed stream.

Element 26: wherein an equal number of the salt ion membrane and the absorption device are present.

Element 27: wherein the olefin-rich permeate stream is obtained at a pressure of at least about 1.5 bar.

Element 28: wherein the absorption device is selected from the group consisting of an absorption column, a rotating packed bed, and a compact contacting unit.

Element 29: wherein the absorption device comprises an absorption column, the second aqueous salt stream is introduced to an upper portion of the absorption column and the at least a portion of the olefin-lean retentate stream is introduced to the absorption column below the second aqueous salt stream.

Element 30: wherein the absorption column comprises at least an absorber top settling zone, an absorber bottom settling zone, and an internals zone between the absorber top settling zone and the absorber bottom settling zone.

Element 31: wherein the at least a portion of the olefin-lean retentate stream is introduced to a lower portion of the absorption column below the upper portion

Element 32: wherein a retentate-side pressure of the salt ion membrane is at least about 1.5 bar greater than a permeate-side pressure of the salt ion membrane.

Element 33: wherein a single salt ion membrane is used to promote separation of the mixed feed stream.

Element 34: wherein a single absorption device is used to promote olefin extraction into the second aqueous salt stream.

Element 35: wherein the salt ion membrane comprises at least a feed-receiving zone, a membrane material, and a permeate-receiving zone.

The present disclosure further relates to the following non-limiting embodiments:A1: A process comprising: A process comprising:providing a mixed feed stream comprising at least one olefin and at least one paraffin;introducing at least a first portion of the mixed feed stream and a first aqueous salt stream to a salt ion membrane under conditions effective to form at least two phases while contacting the salt ion membrane;wherein the salt ion membrane is more permeable to olefins than to paraffins;obtaining an olefin-rich permeate stream and an olefin-lean retentate stream from the salt ion membrane, the olefin-lean retentate stream comprising at least a portion of the at least one olefin from the mixed feed stream;wherein at least one of the olefin-rich permeate stream and the olefin-lean retentate stream further comprises a salt ion membrane aqueous salt phase;introducing at least a portion of the olefin-lean retentate stream and a second aqueous salt stream to an absorption device under conditions effective to promote olefin extraction into the second aqueous salt stream;obtaining from the absorption device an olefin-rich aqueous salt stream comprising at least a portion of the at least one olefin from the olefin-lean retentate stream, and an olefin-lean hydrocarbon stream comprising at least a portion of the at least one paraffin from the mixed feed stream; andproviding at least a portion of the olefin-rich aqueous salt stream as at least a portion of the first aqueous salt stream.A2: The process of A1, wherein the second aqueous salt stream comprises at least a portion of the salt ion membrane aqueous salt phase, the salt ion membrane aqueous salt phase being separated from the olefin-rich permeate stream and/or the olefin-lean retentate stream before being provided as the at least a portion of the second aqueous salt stream.A3: The process of A2, wherein a makeup stream comprising an aqueous salt solution or water is supplied as at least a portion of the second aqueous salt stream.A4: The process of A2 or A3, wherein the olefin-rich permeate stream further comprises at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream is obtained from the salt ion membrane aqueous salt phase comprising the olefin-rich permeate stream.A5: The process of any of A2 to A4, wherein the olefin-lean retentate stream comprises at least a portion of the salt ion membrane aqueous salt phase, and at least a portion of the second aqueous salt stream is obtained from the salt ion membrane aqueous salt phase comprising the olefin-lean retentate stream.A6: The process of any of A2 to A5, wherein a first portion of the salt ion membrane aqueous salt phase is diverted away from a second portion of the salt ion membrane aqueous salt phase being provided to the absorption device.A7: The process of any of A1 to A6, wherein the second aqueous salt stream has a lower olefin concentration than does the first aqueous salt stream.A8: The process of A7, wherein the second aqueous salt stream comprises at least a portion of the salt ion membrane aqueous salt phase, the salt ion membrane aqueous salt phase being separated from the olefin-rich permeate stream and/or the olefin-lean retentate stream before being provided as the at least a portion of the second aqueous salt stream, and the process further comprising:performing a conditioning operation upon at least a portion of the salt ion membrane aqueous salt phase to produce the lower olefin concentration.A9: The process of A8, wherein the conditioning operation comprises at least one action performed on the salt ion membrane aqueous salt phase selected from the group consisting of a temperature change, a pressure change, a phase separation, and any combination thereof.A10: The process of A8 or A9, wherein the conditioning operation comprises at least phase separation of the salt ion membrane aqueous salt phase from a conditioned hydrocarbon-rich stream comprising one or more olefins.A11: The process of A10, further comprising:introducing at least a portion of the conditioned hydrocarbon-rich stream to the salt ion membrane.A12: The process of A10 or A11, wherein the salt ion membrane aqueous salt phase is separated from the conditioned hydrocarbon-rich stream as a hydrocarbon-lean stream, and at least a portion of the hydrocarbon-lean stream is provided to the absorption device as at least a portion of the second aqueous salt stream.A13: The process of A12, wherein at least a portion of the hydrocarbon-lean stream is diverted away from the absorption device as a purge stream or a product stream.A14: The process of any of A10 to A13, wherein the conditioning operation comprises changing a temperature of the salt ion membrane aqueous salt phase at least once.A15: The process of A14, wherein changing the temperature of the salt ion membrane aqueous salt phase at least once comprises:raising the temperature of the salt ion membrane aqueous salt phase from a first temperature to a second temperature to lower an olefin absorption capacity thereof;after raising the temperature of the salt ion membrane aqueous salt phase to the second temperature, performing phase separation to separate the conditioned hydrocarbon-rich stream from the salt ion membrane aqueous salt phase; andafter separating the conditioned hydrocarbon-rich stream from the salt ion membrane aqueous salt phase, lowering the temperature of the salt ion membrane aqueous salt phase from the second temperature to a third temperature to at least partially restore the olefin absorption capacity.A16: The process of A15, wherein the first temperature and the third temperature are about equal.A17: The process of A15 or A16, further comprising:performing a first phase separation prior to raising the temperature and separating a first conditioned hydrocarbon-rich stream comprising one or more olefins from the salt ion membrane aqueous salt phase.A18: The process of any of A15 to A17, further comprising:performing phase separation upon the olefin-lean retentate stream and separating an olefin-lean hydrocarbon-rich stream from the salt ion membrane aqueous salt phase prior to raising the temperature of the salt ion membrane aqueous salt phase; andintroducing at least a portion of the olefin-lean hydrocarbon rich stream to the absorption device.A19: The process of any of A9 to A18, further comprising:raising pressure of the salt ion membrane aqueous salt phase prior to providing the salt ion membrane aqueous salt phase as at least a portion of the second aqueous salt stream.A20: The process of any of A9 to A19, wherein at least a portion of the salt ion membrane aqueous salt phase is diverted away from the absorption device as a purge stream or a product stream.A21: The process of any of A1 to A20, further comprising:introducing at least a second portion of the mixed feed stream to the absorption device.A22: The process of any of A1 to A21, wherein the first and second aqueous salt streams comprise a silver (I) salt, a copper (I) salt, or any combination thereof.A23: The process of any of A1 to A22, wherein the first and second aqueous salt streams comprise silver nitrate.A24: The process of any of A1 to A23, wherein the salt ion membrane and the first and second aqueous salt streams each comprise one or more metal salts that are the same.A25: The process of any of A1 to A24, wherein one or more olefins are obtained from the olefin-rich permeate stream at a purity of at least about 95 wt %, based on total hydrocarbons in the olefin-rich permeate stream.A26: The process of any of A1 to A25, wherein the olefin-rich permeate stream contains at least about 95 wt % of the one or more olefins in the mixed feed stream, based on total olefins in the mixed feed stream.A27: The process of any of A1 to A26, wherein an equal number of the salt ion membrane and the absorption device are present.A28: The process of any of A1 to A27, wherein the olefin-rich permeate stream is obtained at a pressure of at least about 1.5 bar.A29: The process of any of A1 to A28, wherein the absorption device is selected from the group consisting of an absorption column, a rotating packed bed, and a compact contacting unit.A30: The process of any of A1 to A29, wherein the absorption device comprises an absorption column, the second aqueous salt stream is introduced to an upper portion of the absorption column and the at least a portion of the olefin-lean retentate stream is introduced to the absorption column below the second aqueous salt stream.A31: The process of A30, wherein the absorption column comprises at least an absorber top settling zone, an absorber bottom settling zone, and an internals zone between the absorber top settling zone and the absorber bottom settling zone.A32: The process of A30 or A31, wherein the at least a portion of the olefin-lean retentate stream is introduced to a lower portion of the absorption column below the upper portionA33: The process of any of A1 to A32, wherein a retentate-side pressure of the salt ion membrane is at least about 1.5 bar greater than a permeate-side pressure of the salt ion membrane.A34: The process of any of A1 to A33, wherein a single salt ion membrane is used to promote separation of the mixed feed stream.A35: The process of any of A1 to A34, wherein a single absorption device is used to promote olefin extraction into the second aqueous salt stream.A36: The process of any of A1 to A35, wherein the salt ion membrane comprises at least a feed-receiving zone, a membrane material, and a permeate-receiving zone.

Many alterations, modifications, and variations will be apparent to one having ordinary skill in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure and that when numerical limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated.

All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allowed, including any priority documents and/or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited thereby. For example, the compositions described herein may be free of any component, or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein. Likewise, the term “comprising” is considered synonymous with the term “including.” Whenever a method, composition, element or group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed, including the lower limit and upper limit. 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. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to one having ordinary skill in the art and 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 illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein.