A process for reducing atmospheric pollution

Abstract: Methods and compositions for reducing toxic compounds emissions and the maximum reactivity of exhaust products emitted by spark-ignition internal combustion engines. Gasoline having a minimum target octane number is formed by blending together base fuel blending components and at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent to up to about 0.03 gram of manganese per gallon. The manganese compound is used in lieu of an amount of one or more aromatic gasoline hydrocarbons required to achieve the same target octane number so that there is a more than proportionate decrease in toxic aromatic compounds in the tailpipe exhaust and the maximum reactivity of the tailpipe exhaust products produced by the manganese-containing gasoline is less than the maximum reactivity of the tailpipe exhaust products produced by the same base fuel blending components not containing any such manganese compound but containing in lieu thereof an amount of one or more aromatic gasoline hydrocarbons required to achieve the same target octane number. There is thus provided a way of providing and using gasolines of suitable octane values while concomitantly reducing toxic compound emissions and the potential for ground ozone formation, smog formation, and other grievous consequences of atmospheric pollution.

Description: This invention relates to a process for reducing atmospheric pollution when gasoline is formulated to a target octane number. Recent studies of EPA regulations provide guidelines for reformulated gasolines which will provide a reduction in toxic compounds, e.g. benzene, butadiene, formaldehyde, and acetaldehyde in the tailpipe exhaust gases from automobiles. EP-A-466511 discloses gasoline fuels which are said to be environmentally friendly and processes for the production, distribution and dispensation of such fuels. The fuels have a Reid vapor pressure of 58.6 kPa according to ASTM D-323 and contain up to 1/32 gram of manganese per gallon as a cyclopentadienyl manganese tricarbonyl compound. EP-A-466512 discloses a method of providing and using gasolines of suitable octane values while at the same time reducing atmospheric pollution caused by exhaust products when the gasoline is ignited. The method involves blending a base fuel with a cyclopentadienyl manganese tricarbonyl compound. W087/01384 discloses fuel compositions comprising as an antiknock compound a cyclopentadienyl manganese tricarbonyl compound in combination with a solvent selected from C 1-6 aliphatic alcohols and a non-leaded gasoline base. The fuel compositions are said to provide improvements with respect to hydrocarbon emissions. The attainment of lower toxic emissions is however not without penalty. Generally, the target octane number must be lowered and refinery capacity must be adjusted to obtain these lower toxic emissions. These solutions are not completely acceptable due to the higher octane requirement of today's automobile engines and the need to conserve crude oil resources. In addition, gasoline properties (octane quality, volatility, stability, distillation characteristics) must be provided on an economical basis and without excessively or prematurely depleting natural resources such as the world's supply of petroleum. Moreover, these key gasoline properties must be provided within the capabilities and production capacities of the petroleum refining industry. Accordingly, this invention provides a process for increasing refinery capacity and decreasing refinery emissions by providing an efficacious means for formulating gasoline with a target octane number. This invention is deemed to provide a most effective and efficient way of providing gasolines of suitable octane values while concomitantly reducing the potential for ground ozone formation, smog formation, and other grievous consequences of atmospheric pollution. In one embodiment of the present invention there is provided a process for reducing atmospheric pollution when gasoline is formulated to a target octane number which process comprises: a) reducing furnace emissions of NO x , CO, particulates, SO x and CO 2 from a refinery having a reformer and a rated crude capacity of more than about 7950m 3 (about 50,000 barrels) per stream day at least 50% of the rated capacity being utilized in the production of gasoline by operating the reformer at reduced severity when compared with the reformer severity required to achieve the target octane number for a formulated gasoline consisting of base fuel blending components and an amount of one or more aromatic gasoline hydrocarbons, to produce a gasoline base stock; and b) formulating gasoline to the target octane number by blending the gasoline base stock produced in a) with at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent up to about 33 kg of manganese per 3975 m 3 (25,000 barrels) of formulated gasoline per stream day. The gasoline-type hydrocarbon fuels used in forming the gasoline will generally comprise saturates, olefins and aromatics. Oxygenated fuel blending components, such as hydrocarbyl ethers, are also suitable for use. In other preferred embodiments of this invention, the fuels contain limitations on the content of aromatic gasoline hydrocarbons, inasmuch as aromatics are capable of providing exhaust product species of relatively high reactivity. Likewise, it is desirable to form or utilize in gasolines containing at most relatively small quantities of olefinic hydrocarbons (e.g. less than 10%, and more preferably less than 5% by volume), as these substances tend to produce exhaust product species of high reactivity. At the present time the most widely used method of increasing the octane quality of pool gasoline is to utilize aromatic gasoline hydrocarbons in the base blends. This results from the fact that existing refinery capacity is biased toward production of highly aromatic gasolines in order to satisfy the octane demands imposed upon them by the higher performance vehicles desired and used by the motoring public. A benefit associated with this invention is the ability of a refiner to decrease the severity of reformer operations in the production of gasoline. The reduction in reformer severity is due in part to the obtainment of the target octane numbers by using an amount of at least one cyclopentadienyl manganese tricarbonyl compound in lieu of an amount of one or more aromatic gasoline hydrocarbons required to achieve the same target octane number. By reducing the severity of the reformer operation, a refiner is able to decrease the amount of fuel oil required for reformer operation - which in turn results in a decrease in the amount of emissions of NO x , CO, particulates, SO x , and CO 2 from the reformer furnace stack. In turn, the use of at least one cyclopentadienyl manganese tricarbonyl compound in lieu of an amount of aromatic gasoline hydrocarbons to achieve the same target octane number thus provides reduced refinery emissions (as well as a reduction in automobile toxic emissions). To achieve the same target octane number in refinery formulated gasoline, a refinery having a rated crude capacity of about 50,000 barrels per stream day (MBPSD), wherein about 50% of the rated capacity is utilized in the production of gasoline, will use at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent up to about 33 kg, for example from 10 to 33 kg, of manganese per stream day, preferably from 15 to 33 kg of manganese per stream day, and most preferably from 25 to 33 kg of manganese per 25,000 barrels of formulated gasoline per stream day. The gasolines produced using the process of the invention are lead-free in the sense that no organolead antiknock agent is blended into the fuel. If any trace amounts of lead are present, such amounts are due exclusively to contamination in the system in which the fuels are formed, blended, stored, transported or dispensed. The hydrocarbonaceous gasoline base stocks that can be used in forming the gasoline blends include straight run stocks, light naphtha fractions, cracked gasoline stocks obtained from thermal or catalytic cracking, hydrocracking, or similar methods, reformate obtained by catalytic reformation or like processes, polymer gasolines formed via polymerization of olefins, alkylates obtained by addition of olefins to isobutane or other hydrocarbons by alkylation processes, isomerates formed by isomerization of lower straight chain paraffins such as a n-hexane, n-heptane, and the like, and other hydrocarbons of the gasoline boiling range formed by suitable refinery processing operations. Suitable amounts of appropriate hydrocarbons formed by other methods such as production from coal, shale or tar sands can be included, if desired. For example reformates based on liquid fuels formed by the Fischer-Tropsch process can be included in the blends. In all cases however, the resultant gasoline must satisfy the reduced total toxic compounds and the maximum reactivity tailpipe hydrocarbon emission requirements of this invention and additionally will possess the distillation characteristics typical of conventional regular, midgrade, premium, or super-premium unleaded gasolines. For example, the motor gasolines are generally within the parameters of ASTM D 4814 and typically have initial boiling points in the range of about 20 to about 46°C and final boiling points in the range of about 185 to about 225°C as measured by the standard ASTM distillation procedure (ASTM D 86). The hydrocarbon composition of gasolines according to volume percentages of saturates, olefins, and aromatics is typically determined by ASTM test procedure D 1319. Generally, the base gasoline will be a blend of stocks obtained from several refinery processes. The final blend may also contain hydrocarbons made by other procedures such as alkylates made by the reaction of C 4 olefins and butanes using an acid catalyst such as sulfuric acid or hydrofluoric acid, and aromatics made from a reformer. The saturated gasoline components comprise paraffins and naphthenates. These saturates are generally obtained from: (1) virgin crude oil by distillation (straight run gasoline), (2) alkylation processes (alkylates), and (3) isomerization procedures (conversion of normal paraffins to branched chain paraffins of greater octane quality). Saturated gasoline components also occur in so-called natural gasolines. In addition to the foregoing, thermally cracked stocks, catalytically cracked stocks and catalytic reformates contain some quantities of saturated components. In accordance with preferred embodiments of this invention, the base gasoline blend contains a major proportion of saturated gasoline components. Generally speaking, the higher the content of saturates consistent with producing a fuel of requisite octane quality and distillation characteristics, the better. Olefinic gasoline components are usually formed by use of such procedures as thermal cracking, and catalytic cracking. Dehydrogenation of paraffins to olefins can supplement the gaseous olefins occurring in the refinery to produce feed material for either polymerization or alkylation processes. In order to achieve the greatest octane response to the addition of the cyclopentadienyl manganese tricarbonyl antiknock compound, the olefins, if used in the fuel blends, should be substantially straight chain 1-olefins such as 1-heptene, 1-octene, 1-nonene, 1-decene, and the like. Olefins of this type are known to exhibit excellent antiknock response to cyclopentadienyl manganese tricarbonyls -- see Brown and Lovell, Industrial and Engineering Chemistry, Volume 50, No. 10, October 1958, pages 1547-50. The gasoline base stock blends with which the cyclopentadienyl manganese tricarbonyl additive is blended pursuant to this invention will generally contain 40 to 90 volume % of saturates, up to 30 (and preferably less than 10 and more preferably less than 5) volume % olefins, and up to about 45 volume % aromatics. Preferred gasoline base stock blends for use in the practice of this invention are those containing no more than 40% by volume of aromatics, more preferably no more than 30% by volume of aromatics, still more preferably no more than 28% by volume of aromatics, and most preferably no more than 25% by volume of aromatics. Preferably, the overall fuel blend will contain no more than 1% by volume and most preferably no more than 0.8% by volume of benzene. Particularly preferred unleaded gasolines produced in the practice of this invention not only meet the emission reactivity criteria of this invention, but in addition, are characterized by having (1) a maximum sulfur content of 300 ppm, (2) a maximum bromine number of 20, (3) a maximum aromatic content of 20% by volume, (4) a maximum content of benzene of 1% by volume, and (5) a minimum content of contained oxygen of 2% by weight in the form of at least one monoether or polyether, such gasoline having dissolved therein up to about 0.03 gram of manganese per gallon as methylcyclopentadienyl manganese tricarbonyl. Gasolines of this type not containing the manganese additive are sometimes referred to as reformulated gasolines. See for example Oil & Gas Journal, April 9, 1990, pages 43-48. From the standpoint of octane quality, the preferred gasoline base stock blends are those having an octane rating of (R + M)/2 ranging from 78-95. Any of a variety of cyclopentadienyl manganese tricarbonyl compounds can be used in the practice of this invention. Reference may be had, for example, to U.S.P. 2,818,417 for a description of suitable cyclopentadienyl manganese tricarbonyl compounds and their preparation. Illustrative examples of the manganese compounds which can be utilized in accordance with this invention include cyclopentadienyl manganese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, dimethylcyclopentadienyl manganese tricarbonyl, trimethylcyclopentadienyl manganese tricarbonyl, tetramethylcyclopentadienyl manganese tricarbonyl, pentamethylcyclopentadienyl manganese tricarbonyl, ethylcyclopentadienyl manganese tricarbonyl, diethylcyclopentadienyl manganese tricarbonyl, propylcyclopentadienyl manganese tricarbonyl, isopropylcyclopentadienyl manganese tricarbonyl, tert-butylcyclopentadienyl manganese tricarbonyl, octylcyclopentadienyl manganese tricarbonyl, dodecylcyclo-pentadienyl manganese tricarbonyl, ethylmethylcyclopentadienyl manganese tricarbonyl and indenyl manganese tricarbonyl, including mixtures of two or more such compounds. Generally speaking, the preferred compounds or mixtures of compounds are those which are in the liquid state of aggregation at ordinary ambient temperatures, such as methylcyclopentadienyl manganese tricarbonyl, ethylcyclopentadienyl manganese tricarbonyl, liquid mixtures of cyclopentadienyl manganese tricarbonyl and methylcyclopentadienyl manganese tricarbonyl, mixtures of methylcyclopentadienyl manganese tricarbonyl and ethylcyclopentadienyl manganese tricarbonyl. The most preferred compound because of its commercial availability and its excellent combination of properties and effectiveness is methylcyclopentadienyl manganese tricarbonyl. In another embodiment, the invention provides a process for increasing refinery capacity which comprises : a) reducing furnace emissions of NO x , CO, particulates, SO x and CO 2 from a refinery having a reformer and a rated crude capacity of more than about 7950m 3 (about 50,000 barrels) per stream day at least 50% of the rated capacity being utilized in the production of gasoline by operating the reformer at reduced severity when compared with the reformer severity required to achieve the target octane number for a formulated gasoline consisting of base fuel blending components and an amount of one or more aromatic gasoline hydrocarbons, to produce a gasoline base stock; and b) formulating gasoline to the target octane number by blending the gasoline base stock produced in (a) with at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent up to about 33 kg of manganese per 3975 m 3 (25,000 barrels) of formulated gasoline per stream day.

Claims: A process for reducing atmospheric pollution when gasoline is formulated to a target octane number which process comprises: a) reducing furnace emissions of NO x , CO, particulates, SO x and CO 2 from a refinery having a reformer and a rated crude capacity of more than about 7950m 3 (about 50,000 barrels) per stream day at least 50% of the rated capacity being utilized in the production of gasoline by operating the reformer at reduced severity when compared with the reformer severity required to achieve the target octane number for a formulated gasoline consisting of base fuel blending components and an amount of one or more aromatic gasoline hydrocarbons, to produce a gasoline base stock; and b) formulating gasoline to the target octane number by blending the gasoline base stock produced in a) with at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent up to about 33 kg of manganese per 3975 m 3 (25,000 barrels) of formulated gasoline per stream day. A process according to claim 1, wherein the gasoline base stock contains 40 to 90 volume % of saturates, up to 30 volume % olefins and up to about 45% aromatics. A process according to claim 2, wherein the gasoline base stock contains up to about 30 volume % aromatics. A process according to claim 3, wherein the gasoline base stock contains up to about 25 volume % aromatics. A process according to any one of claims 1 to 4, wherein the formulated gasoline contains no more than 1 volume % benzene. A process according to claim 5, wherein the formulated gasoline contains no more than 0.8 volume % benzene. A process according to any one of claims 1 to 6, wherein the gasoline base stock has an octane rating of from 78 to 95. A process according to any one of claims 1 to 7, wherein the cyclopentadienyl manganese tricarbonyl compound is methylcyclopentadienyl manganese tricarbonyl. A process for increasing the capacity of a refinery when gasoline is formulated to a target octane number, which comprises: a) reducing furnace emissions of NO x , CO, particulates, SO x and CO 2 from a refinery having a reformer and a rated crude capacity of more than about 7950m 3 (about 50,000 barrels) per stream day at least 50% of the rated capacity being utilized in the production of gasoline by operating the reformer at reduced severity when compared with the reformer severity required to achieve the target octane number for a formulated gasoline consisting of base fuel blending components and an amount of one or more aromatic gasoline hydrocarbons, to produce a gasoline base stock; and b) formulating gasoline to the target octane number by blending the gasoline base stock produced in (a) with at least one cyclopentadienyl manganese tricarbonyl compound in an amount equivalent up to about 33 kg of manganese per 3975 m 3 (25,000 barrels) of formulated gasoline per stream day. A process according to claim 9 wherein the gasoline base stock is as defined in claim 2, 3, 4 or 7. A process according to claim 9 or 10, wherein the formulated gasoline is as defined in claim 5 or 6. A process according to claim 9, 10 or 11, wherein the cyclopentadienyl manganese tricarbonyl compound is methylcyclopentadienyl manganese tricarbonyl.

Inventors: LEEPER THOMAS ALBERT, LEEPER, THOMAS ALBERT
Applicants: ETHYL CORP, ETHYL CORPORATION
Application year: 1992
Main classification: C10L1
IPC codes: C10L10, C10L1