US3785956A - Selective olefin disproportionation and the use thereof to produce high octane gasolines - Google Patents

Abstract

THE DISPROPORTIONATION OF MIXTURES OF BRANCHED AND UNBRANCHED DISPROPORTIONATABLE OLEFINS IN THE PRESENCE OR ABSENCE OF ETHYLENE IS IMPROVED BY ADJUSTING THE CONVERSION TO A SPECIFIED LEVEL THEREBY INCREASING THE SELECTIVELY OF THE REACTION TO THE CONVERSION OF THE UNBRANCHED OLEFINS. THE PROCESS HAS PARTICULAR UTILITY IN INCREASING OF THE QUALITY OF OLEFINIC GASOLINE STREAMS IN THAT THE LOWER OCTANE-RATED UNBRANCHED OLEFINS CAN BE SELECTIVELY REMOVED FROM THE GASOLINE BY CONVERSION TO OTHER OLEFINS WHILE SUBSTANTIALLY RETAINING THE HIGHER OCTANE-RATED BRANCHED OLEFINS. IN THIS ASPECT, A PROCESS FOR INCREASING THE OCTANCE VALUE OF OLEFINIC GASOLINE STREAMS IS PROVIDED WHICH COMPRISES THE STEPS OF SEPARATING A C5 FRACTION FROM AN OLEFINIC GASOLINE STREAM, THE C5 FRACTION CONTAINING BOTH PENTENES AND ISOPENTENES, SELECTIVELY DISPROPORTIONATING THE C5 STREAM, WITH OR WITHOUT THE PRESENCE OF ADDED ETHYLENE, TO CONVERT MORE OF THE NORMAL PENTENES THAN THE ISOPENTENES, ALKYLATING THE RESULTING BUTENES AND LIGHTER OLEFINS WITH ISOBUTANE, AND COMBINING THE ALKYLATE AND REMAINING GASOLINE TO PROVIDE A HIGH OCTANE GASOLINE HAVING A REDUCED LIGHT OLEFINS CONTENT. IN A MODIFICATION OF THE ABOVE DESCRIBED MULTISTEP PROCESS PRODUCED PROPYLENE IS DISPROPORTIONATED IN A SECOND OLEFIN DISPROPORTIONATION ZONE, TO PROVIDE ADDITIONAL BUTENES FOR ALKYLATION AND ETHYLENE OR REACTION WITH N-PENTENES IN THE FIRST STEP OF THE PROCESS.

Description

Jan. l5, 1974 R. L.. BANKS 3,785,955 SELECTVE OLEFIN DISPROPORTTONATION AND THE USE THEREOF TO PRODUCE HTGH OC''ANE GASLINES Filed Dec; 10, 1.971 2 srmrsshen 1 C5 CUT OF- m |GH TER oLEFlNs '2 CATCRACKED Z ,4 To Ax- KYLATION GASOLINE o Z `L1. n. (Z) 3 D N 2 Z L S 9 CE LLI D.. LLI

u) c5 GASOUNE S La S 2 4| l 42 24 Q '8 LC4 t C3 Q Z l 35 S- Dv 26 x l 1 c5 CUT 0F CAT-CRACKED GASOLINE `C 27 DP"`L` Q 7 Lu H 4 Z S` O 2O Lu m N Z 2| z z Z 9 Si 'Q1 Q u1 f- Z Z Z 1: O CL D. (1f K N O D LLI I a S E; 23 lf3? ALKYLATE'WMES c5`+ GASOLINE BSL 2,5 .INVENTOR R. 1 BANKS Mm.. l5, WM n.1.. BANKS 3,785,955

SELECTIVE OLEFIN DISPROPORTIONATION AND THE USE THEREOF T0 PRODUCE HIGH OCTANE GASOLINES Filed Dec. lO, 1971 2 SheetsSheet 2 O OO c3 LLI cr Ld 2 O u LLI z LLJ 1 n o if L1. Lu F Q 1 o L5 Lk n f- U Z 0 a Z O o L| n. i O N z O n: O [L o CK CL (l) o O O o o o o D 1' N GS LHEIANOD ENBTWVOSI .-iO LNBJ i3d INVENTOR. Rl., BANKS ATTORNEYS United States Patent Ofr1 SELECTIVE OLEFIN DISPROPORTIONATION AND USE THEREOF T PRODUCE HIGH 0C- TANE GASOLINES Robert L. Banks, Bartlesville, Okla., assignor to Phillips Petroleum Company Filed Dec. 10, 1971, Ser. No. 206,734

Int. Cl. @07e 3/62; C10g 37/06 U.S. Cl. 208-93 12 Claims STRACT 0F THE DISCLOSURE The disproportionation of mixtures of branched and unbranched disproportionatable olefins in the presence or absence of ethylene is improved by adjusting the conversion to a specified level thereby increasing the selectivity of the reaction to the conversion of the unbranched oleins. The process has particular utility in increasing of the quality of olefinic gasoline streams in that the lower octane-rated unbranched olefins can be selectively removed from the gasoline by conversion to other olefins while substantially retaining the higher octane-rated branched olefins. In this aspect, a process for increasing the octane value of oleiinic gasoline streams is provided which comprises the steps of separating a C fraction from an olefinic gasoline stream, the C5 fraction containing both pentenes and isopentenes, selectively disproportionating the C5 stream, with or without the presence of added ethylene, to convert more of the normal pentenes than the isopentenes, allrylating the resulting butenes and lighter olefins with isobutane, and combining the alkylate and remaining gasoline to provide a high octane gasoline having a reduced light olefins content. In a modification of the above described multistep process produced propylene is disproportionated in a second olefin disproportionation zone, to provide additional butenes for alkylation and ethylene for reaction with n-pentenes in the first step of the process.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to olefin disproportionation. In a further aspect this invention relates to a method of increasing the octane value of olefinic gasoline streams using olefin disproportionation and alkylation steps.

Description of the prior art The reaction of olelinic materials to produce other ole- -finic materials wherein the reaction can be visualized as the breaking of two existing doublel bonds between first and second carbon atoms, and between third and fourth carbon atoms, respectively, and the formation of two new double bonds, such as between the first and third carbon atoms and the second and fourth carbon atoms, respectively, and wherein the two new double bonds can be on the same or different molecules, has been called the olefin reaction. The breaking and formation of these bonds can be visualized by using a mechanistic scheme involving a cyclobutane transition state. Thus, two unsaturated pairs of carbon atoms combine to form a 4-center (cyclobutane) transition state which then disassociates by breaking either set of opposing bonds. This reaction can be illustrated by the following formulas:

als S (Ija...}4 ga (litl I l l Other terms have been utilized to describe the reactions of olefinic materials which are within the scope of the olefin reaction as defined above. These include such terms as ICC olefin disproportionation, olefin disrnutation, transalkylidenation, and olefin metathesis. Throughout the specification and claims the term olefin disproportionation is used as a matter of choice and is deemed to be equivalent to the above-mentioned terms, including the olefin reaction terminology. Numerous catalyst systems have been reported which etect this reaction, including the catalyst of U.S. Pats. 3,261,879, Banks (1966), and 3,365,- 513, Heckelsberg (1968).

One important embodiment of the olefin disproportionation reaction is the process wherein propylene is smoothly and efficiency converted to approximately equimolar amounts of ethylene and n-butenes. Similarly, other olefins such as pentenes, hexenes, and hcptenes can also be disproportionated, either singly or in mixtures to produce other olefins of both higher and lower molecular weight. The disproportionation of n-pentenes to produce other olelfins such as octenes, heptenes, hexenes, butenes, propylene, and ethylene is also a reaction which has been reported in the prior art.

Still another important aspect of the olefin disproportionation reaction is the embodiment wherein a mixture of ethylene and a suitable higher olefin is disproportionated. The presence of ethylene in the reaction mixture changes the nature of the olefinic products such that the higher olefin is converted into a lower olefin. Such a result has been term ethylene cleavage or etheneolysis Thus, olefins such as n-pentenes can be converted to a lower olefin such as propylene. This result is often promoted by the presence of some double bond isomerization activity within the reaction zone.

Today, the oil industry faces the problem of upgrading the octane values of gasoline produced in refinery operations. This problem had its genesis in the heavily industrialized countries of the world because of pollution of the atmosphere by automobile exhaust emissions. Technological development to abate such pollution has resulted in the use of catalytic exhaust gas treators. These catalytic mufers employ conversion catalysts which are sensitive t0 lead compounds in the exhaust. Thus the use of lead in gasolines has been greatly curtailed. Therefore, the producers of gasolines have been requested to upgrade the octane value of their refinery gasolines to meet the high performance requirement of the modern internal combustion engine without the assistance of added alkyl lead compounds.

OBJECTS OF THE INVENTION It is an object of this invention to modify the products obtained from the disproportionation of mixtures of branched and linear olefins. It is a further object of this invention to upgrade olefinic gasolines to gasolines having higher octane values. Other objects and advantages of the present invention will be apparent to those skilled in the art from the following summary of the invention, detailed description of the invention and the claims.

SUMMARY OF THE INVENTION I have discovered that the olefin disproportionation reaction, when converting a mixture of branched and linear disproportionation olefins, either in the presence or absence of added ethylene, can be made selective for the linear olefins in the reactant mixture by adjusting the level of conversion in the olefin ydisproportionation reaction zone. By adjusting the level of conversion to a range of from about 30 to about 50 percent of the unbranched olefins in the mixture, a relatively small amount of the branched olefins are converted. Accordingly, the process of my invention comprising passing a mixture of linear and branched acylic olefins over an olefin disproportionation catalyst under reaction conditions such that the level of conversion of the linear olefins is in the range of from about 30 to about 50 percent.

In a further aspect of my invention, the octane value of an olefinic gasoline is increased by first subjecting the gasoline to separation to provide a stream rich in C5 olefins, subjecting the C5 rich olefin stream to olefin disproportionation in the absence of added ethylene as mentioned above to selectively convert a substantial amount of the lower octane-rated linear C5 olefins to heavier and lighter acyclic olefins, while substantially retaining the higher octane-rated branched olefins, and then separating the lighter olefins from the effluent of the reaction to provide a stream comprising the lighter olefins and stream comprising C5+ olefins. Additionally, the lighter olens stream, e.g., propylene and butenes, can be alkylated with isobutane to provide high octane alkylates which can then be blended with C5+ olefins. Additionally, the lighter olefin stream, e.g., propylene and butenes, can be alkylated with isobutane to provide high octane alkylates which can then be blended with the C5+ olefin stream and with the remaining portion of the original olefinic gasoline.

In a further aspect of my invention, the octane value of an olefin containing gasoline stock is increased by first subjecting the gasoline to a separation step to provide a C5 cut rich in olefins. The C5 stream is then contacted with an olefin disproportionation catalyst, preferably in the presence of ethylene, under selective reaction conditions, to convert a substantial amount of the lower octane-rated linear C5 olefins to olefins, while substantially retaining the higher octane-rated branched olefins, lighter olefins of ethylene, propylene and butenes. The olefin disproportionation reactor efliuent is separated to provide an ethylene stream, a butenes stream, and an isoolefin-enriched C5 gasoline stream. The ethylene stream is passed to an alkylation unit wherein the ethylene and isobutane are converted to `diisopropyl (DIP). Alternatively, a portion of the ethylene stream is returned to the disproportionation zone as a recycle. The butenes stream is passed to an alkylation zone wherein the butenes and isobutenes are converted ot a high octane C8 alkylate. The high octane C8 alkylate stream, the diisopropyl stream and the C5 gasoline stream can be combined with the original olefin gasoline stock to provide a high octane gasoline as a product of the process.

In still a further aspect of my invention, the separation of the olefin disproportionation effluent as discussed above also provides a propylene stream. This propylene stream is passed to a second olefin disproportionation unit to provide additional ethylene and butenes for increased production of diisopropyl and C8 alkylate.

BRIEF DESCRIPTION OF DRAWING The three figures of the drawing illustrate certain aspects of my invention. FIG. l is a simplified flow diagram of my process showing the selective olefin disproportionation of a C5 cut from an olefinic cat-cracked gasoline. FIG. 2 is a simplified flow diagram of my process showing the steps of selective olefin disproportionation, a second olefin disproportionation step, and ethylene-isobutane alkylation and butene-isobutane alkylation steps. FIG. 3 is a graph of data showing the conversion of isoamylenes versus the conversion of n-amylenes when a mixed amylene stream is passed over an olefin disproportionation catalyst. The data were obtained over a variety of reaction conditions.

DETAILED DESCRIPTION OF THE INVENTION A starting material for the process of my invention is an olenic gasoline having at least about 10 weight percent of olefin hydrocarbons. The gasoline will preferably have a boiling end point which does not exceed 450 F. The olefin content is advantageously from about 20 to about 70 weight percent. Such streams are readily available in refinery operations and are generally available as a product from a catalytic cracker unit. Preferably, the

feed is a full range cat-cracked gasoline. However, a full range cat-cracked gasoline can be fractionated to provide suitable gasoline fractions for my process which are high in olefin and low in aromatics.

My processes have the unique advantages of producing generally increased octane values and a reduced lower olefin content while substantially increasing the volume of gasoline which is available for motor fuel when compared to the volume and octane value of the cat-cracked gasoline starting material.

This advantage is obtained by adjusting the reaction conditions of the olefin disproportionation reaction zone to provide a conversion of the normal feed olefins within the range of from 30 to 50 percent. At this level, the conversion of n-amylenes is much greater than the conversion of isoamylenes. This relationship is true both in the presence and absence of added ethylene. Thus, the effluent from the disproportionation zone retains the higher 0ctane-rated branched olefins, while the newly formed ethylene, propylene and butenes result primarily from the conversion of the lower octane-rated linear amylenes.

Although the use of selected conditions in the olefin disproportionation reaction is especially suitable for the preparation of high octane gasolines, this aspect of my invention has much broader applicability. Thus, a mixture of branched and unbranched olefins having from 4-20 carbon atoms, preferably 4-8 carbon atoms, per molecule can be subjected to disproportionation conditions such that a substantial quantity of the unbranched olefins are converted while substantially retaining the branched olefins. Suitable olefins include the butenes, pentenes, hexenes, heptenes, octenes, and the like. It is not necessary that the mixed feed stream contain branched and unbranched isomers of only one carbon number. Thus, a stream comprising linear pentenes, and isohexenes can be selectively disproportionated such that substantial amounts of the linear olefins (eg. n-pentenes) are converted while relatively small amounts of the branched olefins (e.g. isohexenes) are converted, thus enriching the mixture in branched olefins.

Those skilled in the olefin disproportionation art are aware that the extent of conversion is largely dependent upon the reaction conditions such as temperature, the catalyst selected, and reaction time or space velocity. Accordingly, the exact conditions employed within the reaction zone will be dependent, for example, on the particular catlyst chosen and on the temperature range at which it exhibits optimum activity and selectivity. Preferably, however, the particular olefin disproportionation catalyst is employed at a temperature which is optimum for that catalyst. The space rate is then adjusted to bring the conversion level within the above specified range, preferably about 40 percent.

In view of the above, it is readily apparent that the use of any specific olefin disproportionation catalyst is not critical to my invention. As a matter of fact any catalyst which has the ability to disproportionate propylene to ethylene and butenes can be employed. Those solid catalysts which exhibit disproportionation activity at a temperature in excess of 400 F. are particularly suitable because they are characteristically more resistant to catalyst poisons sometimes associated with the feed.

Accordingly, I prefer to use catalysts such as molybdenum oxide on alumina, on silica or on aluminum phosphate; a tungsten oxide on silica, on alumina, or on aluminum phosphate; or rhenium oxide on alumina or on aluminum phosphate. The preparation, activation, maintenance and use of these catalysts have been reported in the prior art.

Of course, these catalysts can also be modified by various treatments also reported in the prior art. For example, treatment with alkali metals or alkaline earth metals, or admixtures with suitable double bond isomerization catalysts, or treatment with reducing gases such as H2 or other gases including CO, all have been reported.

Temperature, F.

Disproportionation catalyst Broad Preferred WOS/Si O 2 400-1, 100 GOO-900 M003/ S102 40G-1, 100 800-1 000 Moos/A120: 15G-500 250-400 WOS/A120 10D-750 551%650 RezOy/AlgO; -60-1, 000 10U-500 800-1, 000 50-250 SUO-1, 000

Because of its high activity and high durability, the WC3/S102 catalyst is the presently preferred olefin disproportionation catalyst.

Of particular importance to my process is the admixture of a disproportionation catalyst with a suitable solid double bond isomerization catalyst because these combination catalysts generally provide increased conversions particularly when ethylene is in the feed olefin mixture. Some suitable double bond isomerization catalysts are MgO, ZnO, and alumina. Thus, my most preferred catalyst is a combination of magnesium oxide and tungsten oxide on silica where the amount of double bond isomerization catalyst is from about 2:1 to 10:1 parts by weight per part of the olen disproportionation catalyst.

The alkylation steps employed in my process are equally well known in the prior art. Thus the diisopropyl alkylation step and the butene-isobutane alkylation step can employ any suitable catalyst reported in the prior art to convert isobutane and ethylene (in the presence or absence of propylene) and butenes to high octane alkylate. Suitable catalysts include sulfuric acid, AlCl3, BF3, HF, and the like, and mixtures thereof. For example, in a typical HF-alkylation process, a typical temperature is 80-100" F., with a 1 1() minute contact time and with an isobutane to olefin ratio of 6-15.

My invention can best be understood by reference to the drawing. FIG. 1 of the drawing illustrates one embodiment of my invention wherein a C5 cut from a full range cat-cracked gasoline is used as feed in line 1 to the olefin disproportionation zone 13. Therein, the Imixed amylene stream is contacted under reaction conditions which result in a relatively high conversion of n-amylenes, and in a relatively low conversion of isoarnylenes. The effluent from zone 13 is passed to separation zone 14 by way of line 2. The effluent includes ethylene, propylene, and butenes, unconverted amylenes and a C5+ material which boils in the gasoline range. Separation zone 14, removes the ethylene, propylene and butenes in line 3, while the C5+ gasoline material is removed in line 4. The C5+ gasoline can then be blended with depentanized cat-cracked gasoline to provide a gasoline having a greatly reduced light olefin content and the remaining olefins being enriched in isoolef'ins.

Another embodiment of my invention is illustrated in FIG. 2 of the drawing. A debutanized full range catcracked gasoline is subjected to fractionation (not shown) to provide a C5 cut rich in olefins. The C5 cut is passed via line 21 to disproportionation zone 16 wherein it is converted under the selective disproportionation conditions discussed previously. The ellluent is withdrawn from zone 16 and passed in line 22 to separation zone 18, In zone 18, ethylene (and optionally propylene) is separated and removed via line 24, butenes are separated and removed via line 23, and a C5+ gasoline material is removed from line 25.

Diisopropyl unit 19 receives ethylene (and optionally propylene) from line 24 and isobutane from line 26. In the presence of a suitable :alkylation catalyst and reaction conditions in zone 19 these materials are converted to diisopropyl alkylate which is removed by line 29. Alkylation zone 20 receives isobutane from line 27 and butenes from line 23. In zone 20, the feed materials are catalytically converted to high octane C8 alkylate which is removed from zone 20 by line 28. The diisopropyl and C8 alkylate are combined in line 28 and passed to line 24 for admixture with the C5+ gasoline in line 24. A high octane gasoline having increased octane and incr-eased volume is produced when the hydrocarbon mixture in line 31 is combined (not shown) with the depentanized cat-cracked gasoline used as the starting material to my process.

In another modification of my process, two additional steps are employed in the process as discussed above for FIG. 2 of the drawing. In the first step, propylene is removed from separation zone 18 via line 36 and passed to a second disproportionation zone 17. This zone employs a suitable olefin disproportionation catalyst of the same type discussed above in this disclosure. However, the use of a double Abond isomerization catalyst is optional, and preferably not employed to reduce catalyst expense. In zone 17, the propylene feed is converted to ethylene and butenes and the efliuent of this reaction zone is returned to separation zone 18 via lines 37 and 22. This additional disproportionation unit greatly increases the amounts of ethylene and butenes available for alkylation and therefore, increases the quality of alkylate in line 31.

The second modification feeds ethylene into the first olefin disproportionation zone 16 by way of line 41 and/or 42. The amount of ethylene employed will be on the order of about 1 to about 20, preferably 2-10, moles of ethylene per mole of C5 olefin feed. The ethylene cleavage of the mixed isoamylene and n-amylene stream under selective conditions provides still greater quantities of the light olefins for alkylation. If desired, a certain amount of the ethylene in line 24 can be returned to zone 16, via line 42, thus reducing the make-up ethylene requirements.

One additional advantage of my process resides in the fact that alkylation units require high purity feedstocks to operate at peak efficiency. The olefin disproportionation reaction is uniquely compatible with these units as the products from the reaction zones of the olefin disproportionation steps are free from contaminants often encountered in refinery streams using direct separation techniques which adversely affect the alkylation reaction.

Those skilled in the art will understand that the simplified flow diagrams of my process have omitted many items which are actually needed to operate the process. Thus, the use of pumps, fractionators, controls, and the like, have been omitted to simplify the discussion of my invention. The use of these apparatus and other steps is well within those skilled in the art. Thus, for example, it may be advantageous to hydrotreat the cat-cracked gasoline under very mild conditions to prevent contamination of the disproportionation catalyst. Similarly, it may be advisable to treat the feed by percolation through activated beds of materials such as alumina, mole sieves, magnesia, and the like, at low temperatures to purify contaminants of the feed to the first disproportionation zone.

My invention can be further understood by the following examples which are presented to illustrate the process of my invention. They should not be construed to limit the disclosure of my invention as provided above.

7 EXAMPLE I A series of runs were performed on the C5 cuts of different cat-cracker gasolines. Numerous variables were studied in these runs including different levels of feed purification, different process conditions including reaction temperature, pressure, and flow rates, and different combinations of olefin disproportionation catalysts and double bond isomerization catalysts (MgO). The results of these runs were then plotted on a graph as set forth in FIG. 3 of the drawing. That is, in FIG. 3, the points plotted thereon each represent the results of analysis of a sample taken during these runs calculated to percent conversion of isoamylenes versus percent conversion of n-amylenes.

The test reported below is representative of the runs used to provide the data reported in FIG. 3 of the drawing.

A C5 cut of a cat-cracker gasoline was prepared and found to contain 23.3 percent n-pentene and 28.2 percent isopentene by analysis. The catalyst was S percent W03. 92 percent SiOz olefin disproportionation catalyst operated at a temperature of 750 F., 300 p.s.i.g., and 75 weight hourly space velicity. The catalyst was initially activated in air at 1100 F. for 2 hours, flushed with N2, and then treated with carbon monoxide at ll F. for 15 minutes. The reactor was cooled to reaction temperature by ushing with N2. The same activation procedure was subsequently used to regenerate the catalyst.

The system was operated for about 2 hours, the catalyst was then regenerated, and operated for 6 hours. Samples for each of the hours of operation during the 6 hour run were taken and analyzed by gas-chromatography.

A bed of activated MgO was then placed in the feed line to the reactor to further purify and dry the feed, the catalyst was again regenerated, and an additional 6 hour run was made taking sample each hour of the second 6 hour run (samples 7-12). The conversions of namylenes and isoamylenes are given below in Table I. 40

TABLE I Percent conversion n-Amylenes Isoamylenes percent conversion and the lower dashed line shows the expected results for the equal quantity converted with respect to the above-described C5 stream. That the curve obtained by actual runs is far removed from the dashed lines signifying the expected results is strong testimony for the unexpected nature of the present invention.

In addition, these data enable one to calculate that the ratio of rate of reaction of namylenes (kn) to the rate of isoamylenes (k1) is about 5. This is also shown in FIG. 3 of the drawing as the lowest dashed line.

EXAMPLE II A full range debutanized cat-cracked gasoline is used as the starting material for rny process as illustrated in FIG. 1. The debutanized cat-cracked gasoline is fractionated to yield a C5 cut having the composition given in the table below. The feed is passed over a catalyst of 1000 pounds of 8 percent tungsten oxide and 92 percent silica activated in flowing air prior to use at a temperature of from 1000 to 1l00 F. Conditions in the disproportionation reactor 13 are a temperature of 720 F., a pressure of 350 p.s.i.g. and a space velocity of 125 pounds of feed per hour per pound of catalyst. Under these conditions, the conversion of C5 olens is about 27 percent, the conversion of isoamylenes is about 7 percent, and the conversion of n-amylenes is about 50 percent.

The material balance of Table II below illustrates the results achieved with my invention.

TABLE II Pounds per hour Stream number 1 2 3 4 Hydrocarbon:

Ethylene 188 188 Propylene. 1, 937 1, 937 Butenes. 4, 750 10,125 9, 587 538 Butanes. 1,375 1, 375 1, 325 50 Isopentane 39, 625 39, 625 1, 128 38, 437 n-Pentane 7, 625 7, 625 75 7, 550 Isopentenes-.. 32, 250 29,963 588 29 375 n-Pentenos 27, 875 13, 037 275 13, 662 8,500 20,225 20,225

Total 125, 000 125, 000 15, 164 109, 837

The above example illustrates how the present olen disproportionation process can selectively convert a substantial amount of n-pentenes while retaining a substantial amount of the isopentenes from a mixture containing approximately equal amounts of each.

EXAMPLE III A full range cat-cracked gasoline containing 67 percent olen content is used as a feed to my process as illustrated in FIG. 2 of the drawing. In this example, ethylene is not used as additional feed. The cat-cracked gasoline is subjected to fractionation in the same manner as Example II to provide a C5 cut. Reactor 16 uses the same catalyst and same conditions as reported above in Example II. Reactor 17 uses 160 pounds of 8 percent tungsten oxide and 92 percent silica catalyst activated in the same manner as the catalyst in Example II. The conditions in reactor 17 are a temperature of 725 F., a pressure of 325 p.s.i.g. and a space rate of 30 pounds of feed per hour per pound of catalyst. The material balance for the process is presented below in Table III.

TABLE III Pounds per hour Sllemllt11l1111`b0l.:'...:.'.^..'...` 21 22 25 36 37 23 24 Hydrocarbon:

Ethylene 188 35 648 801 Propylene-- 1,937 4,587 2,727 7 Butenes-- 4,750 ,125 538 117 1,327 10,797 Butanes 1,375 1,375 50 30 30 1,325 Isopentan 39, 625 39, 625 188 n-Pentane-- 7, 625 7,625 Isopentenes--. 35,250 29, 963 588 n-Pentenes.-. 27,875 13,937 312 Total 125,000 125,000 109,837 4,769 4,769 14,355 808 9 Stream 23 is the feed to the HF alkylation 20 unit along with isobutane. The alkylate produced in zone 20 and removed by line 28 is produced in the following yields and has the following properties:

Yield, barrels/ barrel of butenes l.75 Research octane number (RON)-clear 96.8 Motor octane number (MON)-clear 94.0

Stream 24 is the feed to the diisopropyl unit 19. Alkylation with isobutane produces a diisopropyl eiliuent in line 29. Streams 29, 28, and 25 are combined in line 31. The line 31 effluent is then combined with the full range catcracked gasoline feed.

This process results in an increase in the MON value of 3-4 units, and the volume of gasoline range material is increased about 25 percent. RON value of the feed full range cat-cracked gasoline as compared to the processed gasoline blend are about the same.

EXAMPLE IV A full range cat-cracked gasoline containing 65 percent olen content is once again tractionated to provide a C5 cut and processed as depicted in FIG. 2 of the drawing. In this example, ethylene is also provided to the disproportonation reactor 16 via line 41. In this case all of the ethylene is placed on recycle through line 42. That is, zone 19 is not included in the process.

The catalyst in reactor 16 is 15,000 pounds of 8 percent tungsten oxide and 92 percent silica disproportionation catalyst. It is intimately mixed with 75,000 pounds of MgO double bond isomerization catalyst. Reaction conditions in reactor 16 include a temperature of 750 F., a pressure of 350 p.s.i.g. and a weight hourly space velocity of 26. The catalyst in reactor 17 is 2,400 pounds of the same catalyst as used in reactor 16. Reaction conditions in reactor 17 include a temperature of 725 F., a pressure of 325 p.s.i.g. and WHSV of 30. Each catalyst is activated in owing air at a temperature of 1000-1100 F. prior to use.

silica, or aluminum phosphate; or rhenium oxide on alumina, silica, or aluminum phosphate, the improvement comprising selectively converting the linear olefin by maintaining the conversion of the linear olefin over the catalyst within a range of from about 30 to about 50 percent.

2. The process of claim 1 wherein the feed stream is a C5 cut from fractionating a full range cat-cracked gasoline.

3. The process of claim 1 wherein the feed stream comprises a mixture of normal and isoamylenes.

4. The process of claim 1 wherein the oleiin disproportionation catalyst is tungsten oxide on silica.

5. The process of producing a high octane gasoline stock by the steps of (1) separating from a gasoline stream containing at least 10 weight percent olen hydrocarbons a stream comprising isoamylenes and normal amylenes, and a C5+ gasoline stream;

(2) passing the stream comprising isoamylenes and normal amylenes over an olefin disproportionation cat alyst, wherein the olefin disproportionation catalyst is tungsten oxide on silica, alumina, or aluminum phosphate; molybdenum oxide on alumina, silica, or aluminum phosphate; or rhenium oxide on alumina, silica, or aluminum phosphate, under reaction conditions which are adjusted to maintain the conversion of the normal amylenes in the range from about 30 to about 50 percent whereby the conversion is made selective for the conversion of normal amylenes, and to provide an efuent stream comprising ethylene, butenes, and a C5+ gasoline;

(3) separating the eluent from step (2) to provide a stream comprising the C5+ gasoline blending stock;

(4) combining the C5 gasoline with the C5+ gasoline stream of step (1).

6. The process of claim 5 wherein the olen disproportionation catalyst is tungsten oxide on silica.

7. A process for the preparation of a high octane gaso- The material balance for this process is given in Table line by the SCPS 0f:

IV Ibelow.

TABLE IV (1) separating a gasoline stream containing at least 10 Pounds per hour Stream number Hydrocarbon:

Ethylene Propylene Butenes 05+ isoolefins Ci* n-oleflns C5 saturates 1 Total 203, 760 10, 997 176, 203 390, 960

1 Includes aromatics.

Stream 23 is the feed to HF alkylation unit 20. The results of this step are shown above in Example III. When the alkylate in line 28, the C5+ gasoline in line 25 and the remaining depentanized cat-cracked gasoline used to provide the C5 feed to the process are combined, the following results are achieved. (1) Gasoline volume is increased 27 percent, (2) The clear motor octane rating is 84.3 compared to 79.1 of the original cat-cracked gasoline; clear research octane rating of both are about 94, (3) The olen content of the combined gasoline is 39 percent compared to 65 percent for the original gasoline.

Reasonable variations and modifications of my process will be readily apparent to those skilled in the art without departing from the spirit or scope of my invention.

I claim:

1. In a process of disproportionating a feed stream comprising ethylene and a mixture of branched and linear disproportionable olens in the presence of an olen disproportionation catalyst, wherein the olefin disproportionation catalyst is tungsten oxide on silica, alumina, or aluminum phosphate; molybdenum oxide on alumina,

weight percent olen hydrocarbons to provide a stream comprising normal amylenes and isoamylenes and a stream comprising a C5+ gasoline;

(2) passing the C5 stream of step 1) over an olefin disproportionation catalyst, wherein the olen disproportionation catalyst is tungsten, oxide on silica, alumina, or aluminum phosphate; molybdenum oxide on alumina, silica, or aluminum phosphate; or rhenium oxide on alumina, silica, or aluminum phosphate, under reaction conditions which are adjusted to maintain the conversion of the normal isoamylenes in the range of from about 30 to 50 percent whereby the conversion is made selective for the conversion of normal amylenes, and to provide an eluent stream comprising ethylene, propylene, butenes and a C5+ gasoline;

(3) separating the effluent stream of step (2) to provide a stream of ethylene, a stream of propylene, a stream of butenes, and a C5+ gasoline stream;

(4) passing the stream of butenes from step (3) in admixture with isobutane to an alkylation zone con- 11 taining an alkylation catalyst to provide an etfluent stream comprising a high octane alkylate;

() combining the C6+ gasoline stream of step (1),

the C54 gasoline stream of step (3) and the high octane alkylate stream of step (4) to provide a high octane gasoline having a motor octane value greater than the initial gasoline stream having at least 20 Weight percent olens.

8. The process of claim 7 further including the steps of:

(6) passing the stream of propylene from step (3) to an olen disproportionation zone wherein the stream is catalytically converted to an euent stream comprising ethylene and propylene, and

(7) returning the eiuent stream to separation step (3) to provide increased quantities of ethylene and butenes.

9. The process of claim 7 further including the steps (8) passing the stream comprising ethylene in admixture with isobutane to an alkylation zone to provide an eftiuent stream comprising diisopropyl alkylate, and

(9) combining the diisopropyl alkylate with the cornlbined streams of step (5) 10. The process of claim 7 wherein step (2) is accomplished in the presence of added ethylene.

12 11. The process of claim 8 wherein step (2) is accomplished in the presence of ethylene, and the stream comprising ethylene of (3) is returned to step (2).

12. The process of claim 11 wherein the olefin disproportionation catalyst is tungsten oxide on silica.

References Cited UNITED STATES PATENTS DELBERT E. GANTZ, Primary Examiner C. E. SPRESSER, J R., Assistant Examiner U.S. C1. X.R.

UNITED STATES PATENT OFFICE t CERTIFICATE 0F CORRECTION PATENT No. 3,785,956 DATED January 15, 197i INVENTOR(S) Robert L. Banks it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column l0, line 65, delete "soamylenes and :insert mylenes Ergncd and Sealcd this srxrenfh Da)l of December1975 [SEAL] Attest:

RUTH C. MRMSON C. MARSHALL DANN Alteslmg Ufjltef Commissinner oj'Patents and Trademarks

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