US2403879A - Process of manufacture of aviation gasoline blending stocks - Google Patents

Description

Julyv 9, 1946; w. A. scHuLzrz E rAL 2,403,379

' PROCESS o F MANUFAGTURE oF AVIATION GAsoLINE BLENDING sTocKs Filed March 10, 1944 v Patented July 9, 1946 PROCESS F MANUFACTURE 0F AVIATION GASOLINE BLENDING STOCKS Walter A. Schulze and Carl J. Helmers, Bartlesville, Okla., assignors to Phillips Petroleum Company, a corporation of Delaware Application March 10, 1944, Serial No. 525,922

13 Claims. (Cl. 260-671) This invention relates to the production of high octane hydrocarbon fuels by the catalytic conversion of petroleum hydrocarbons. More specifically the invention relates to the production of aromatic hydrocarbon concentrates suitable for inclusion in aviation gasolines through a novel sequence of catalytic operations.

The production and recovery of aromatic hydrocarbons from petroleum sources are of particular importance in supplying large quantities of benzene, toluene, ethylbenzene, cumene and other compounds needed as solvents, gasoline blending agents and intermediates in organic chemical industries. Recently, the demand for high-quality aviation gasolines has greatly increased the demand for aromatic hydrocarbons because of the extra power in rich-mixture performance derived from aromatics-containing gasoline blends. In order to augment the supply of aromatic distillates, thermal and catalytic cracking of petroleum hydrocarbons have been employed to produce aviation blending stocks with the latter processes producing products superior to the straight thermal procedures. However, it is well known that heretofore in order to produce high-quality aromatic distillates relatively severe conditions of catalytic cracking were required, often involving multiple-pass catalytic cracking operations. Under such conditions the production of light gases may amount to 50 weight per cent or more of the original charge stock. It is obvious then that the present catalytic cracking processes are not entirely satisfactory in view of the low yields realized and the plant equipment required for multiple-pass catalytic operations.

The employment of aromatic concentrates in aviation gasolines is contingent not only upon a high aromatics concentration in the blending stocks to impart desirable performance characteristics, but also on very low proportions of undesirable hydrocarbon types which impair the blending 3-C octane values of the aromatics-rich fractions. The quality of the aromatic blending stks as measured in flight tests and by the S-C supercharged engine can often be greatly improved by the substantially complete removal of non-hydrocarbon impurities such as sulfur compounds. It is also recognized that further quality improvement can be eifected by conversion of the benzene content of blending stocks to higher homologs through alkylation with olens such as ethylene, propylene and butylenes.

It is an object of this invention to accomplish the conversion of selected hydrocarbon feed stocks to gasoline of unusually high aromatic content and relatively free of undesirable hydrocarbon and non-hydrocarbon impurities by means of an interrelated sequence of controlled catalytic operations.

Another object of this invention is to increase the yield and quality of blending stocks for aviation gasoline by means of combined catalytic alkylation and treating steps.

Still another object of this invention is the provision of an integrated process for the production of aromatic blending stocks of low sulfur and olen content through the catalytic treatment of selected fractions of the raw aromatic product.

Other objects and advantages of the invention will. be apparent from the following disclosure.

We have discovered that the production of gasoline stocks rich in aromatic hydrocarbon types may now be accomplished without recourse to multiple-pass catalytic cracking operations. Subsequent to the relatively mild operating conditions employed in the catalytic aromatization of the present process, -a substantial increase in the rich mixture rating of the aviation base stock is effected by a combination of two outstanding novel features: (l) segregation of the benzene fraction followed by alkylation with the olenic constituents from the primary catalytic reaction to produce alkyl benzenes greatly superior to benzene in rich mixture blending Value; (2) application of a catalytic treating operation to the product stream to remove deleterious impurities thereby greatly improving the rich-mixture rating of the base stock.

The beneficial results realized from the above features are such that the utility of catalytic cracking oper-ations has been greatly extended. Of inestimable value is the conservation of feed stocks, since with our novel process it is now possible to produce a high quality aromatic distillate with less severe cracking conditions for a given S-C rating. The aromatics content of the finishedv blendingstock is increased by virtue of the alkylation of the benzene fraction, since freezingv point consider-ations often preclude the inclusion of the total benzene fraction as such. Another important advantage of the present process is that the range of operable feed stocks has been greatly extended in view of the quality increase that can be realized from the combined elects of the alkylation and the treating operations.

Considering only its broader aspects, the present process may be operated in the following manner to accomplish the objects and advantages previously set forth. Ordinarily a petroleum distillate having a high carbon -to hydrogen ratio is catalytically cracked under cyclization conditions with subsequent stabilization of the eliluent. The light gas is processed to prepare an oleflnic alkylation feed while the stabilized gasoline is claytreated and separated by fractionation into a 200 F. end-point benzene-containing stream and a higher-boiling 350 F. end-point aviation blending stock. The lower boiling fraction is treated catalytically under polymerizing conditions to remove sulfur and oleiinic material, both of which are undesirable in the subsequent alkylation step. A purified and refractionated benzene-concentrate is catalytically alkylated with any one or any combination of the light olens previously produced in the primary conversion. The lean benzene effluent stream from the alkylation step is recycled to the cracking step while the total alkylate is fed directly into the main unfractionated product stream where its valuable constituents are segregated in the 350 F. end-point stock. This latter material is then catalytically treated under polymerizing conditions to produce a finished product of high rich-mixture blending value. The secondary polymerization and alkylation steps of this process not only coact to exert a direct favorable effect on the volume and quality of finished product, but they also contribute valuable recycle stock of high carbon to hydrogen ratio to the primary conversion step thereby further increasing the yield of aromatics as based on fresh feed.

The accompanying simplified drawing shows one specific diagrammatic arrangement of apparatus by which the present process may be carried out. It should be understood, however, that the invention is not limited to processing as herein disclosed and that Various modifications of the process and apparatus may be made without departing from the scope of the invention as defined in the appended claims.

Referring to the drawing, a thermally or catalytically cracked naphtha having a high carbon to hydrogen ratio is transmitted from a charge tank i into a line 2 that communicates with a recycle stock line 'Il and a steam supply line 3. The resulting mixture of naphtha, recycle stock and steam constitutes a composite feed that is preferably in a vaporous state and that is passed into a heating coil il. The feed is preheated to about 1100-1150 F. in heater l prior to injection into a catalyst case 5 which is filled with a solid adsorbent-type catalyst such as bauxite and in which conditions of temperature, pressure and Contact time are selected so as to result in optimum aromatics formation. The efuent from the catalyst case is conducted through a line 6, a vheat exchanger l and a line 8 to a separator 9 where condensed steam is removed by means of a line i0. Gaseous products are separated in this i step and are conducted via a line l l, a compressor l2 and a line I3 to a high-stage accumulator i4. In this latter unit further condensation of water along with small quantities of hydrocarbon is ef fected and the condensate is drained through line I5. The gaseous products then pass via a line I6 'to a column i'! where they are contacted with absorbing liquid from a line 6I to remove C5 and heavier hydrocarbons. The rich absorbing liquid is then returned to the main product stream via lines i8 and 25. The C4 and lighter gases are conducted through a line i9 to a fractionator 20 where hydrogen and methane are the .principal components of the overhead fraction that are removed through a line 2| while the kettle product is transferred in a line 22 to a column 23 where a gas fraction comprising C2, Cs, and C4 hydrocarbons is prepared and charged to an alkylation unit 45 via a line 2e. The small quantity of Ct-- hydrocarbons comprising the kettle product of column 23 is added to the main product stream through line 25.

The stabilized product stream from separator 9 is withdrawn through a line 21, preheated in heat exchanger 1 and finally discharged into a (lil flash vaporization tower 26. Normally liquid product hydrocarbons from the gas plant and alkylation operations are conveniently added at this point from line and preheater 2S. The overhead vapors of approximately 400 E. P. are conducted through a line to a clay-tower 3| While the high boiling components are discharged into a recycle line 68 through a line 29. The clay-tower eiiiuent is discharged via a line 32 into a fractionator 33 where the product stream is divided for subsequent processing.

The overhead stream from 33 is comprised of hydrocarbons boiling from C5 to 200 F. and is relatively rich in benzene and oleiins. This material is passed through a line 34 to a heater 35 where its temperature is raised to a suitable value of about 400 F. under sufcient pressure to maintain substantially liquid-phase conditions, The hot liquid is discharged directly into a catalyst case 3S which is filled with the preferred silicaalumina catalyst composition. The treated efuent is partially vaporized in line 31 as the pressure is reduced and fractionation is effected in a column 38. A fraction having an end-point of about 160 F. is taken overhead to motor fuel storage through a line 39 while the kettle product is taken Via a line 4i] to a fractionator M where a benzene concentrate boiling between M-180 F. constitutes the overhead product and the kettle product containing olen polymer is removed through a line 43 to the recycle line 68.

The benzene concentrate from column #il is utilized as feed stock for the alkylation step along with the olefins prepared in column 23. The benzene stream from line i2 is combined with the oleiin-parain gases from line 26 just ahead of heating coil 45. The alkylation charge is preheated to alkylation conditions under a pressure sufficient to maintain liquid or dense phase conditions and is discharged directly into the alkylation reactor d5. The catalyst case may be filled with a silica-alumina catalyst composition. The reactor effluent is conducted through a line lll with pressure reduction into a column 48 where the product is stabilized with the light parafns and any unreacted olefms being removed through a line to be employed as renery fuel or in other conversion operations. The kettle product is suitably preheated and is transferred through a line 50 to a fractionator 5| where the unreacted benzene along with the naphthenic and paraffinic constituents of the original benzene concentrate are conducted through a line 53 to the recycle transfer line yESB: The kettle product from 'i column 5i which contains a mixture of monoand di-alkylated benzene derivatives is passed through lines 52 and 25 into heater 26 and thence into line 2l, the main stabilized product stream from the catalytic cracking operation. In this manner alkylate boiling below about 400 F. is passed on to further treatment and the highboiling alkylate finds its way into the recycle line ES via line 29.

After removal of the 200 F. end-point fraction in column 33, the main aviation base stock material, which now includes aromatics reconstructed from the olens and benzene as well as aromatics produced in the original cracking step, is passed through a line 513 into a fractionator 55. A fraction boiling between 20G-350 F. is taken overhead in a line 51 while material distilling above 350 F. is discharged through line 5S into recycle line 6o. A portion of the overhead cut is diverted into a line 58, a condenser 59 and a reflux tank 50. The condensed material not only furnishes reflux for column 55 but also constitutes absorbing liquid which is pumped through a line El to column Il.

The product in line 5'." is heated in a coil ft2 to a temperature of about 450 F. under pressure adequate to maintain liquid-phase conditions during the subsequent treatment in a catalyst case G3. After further reduction of sulfur and unsaturation over the preferred silica-alumina catalyst, the product is transferred via a line 64 to a fractionator E5. High-boiling polymers and sulfur compounds are removed through a line 06 and an overhead 20G-350 F. fraction is taken to storage as finished base stock through a line 6l.

The recycle stock in line 63, which comprises high-boiling hydrocarbons from columns 28, lil, 55 and 85 as Well as a light overhead fraction from column 5 l, is passed through heat exchanger 7 into a tar trap 69 Where partial vaporization occurs. High boiling refractory hydrocarbons and sulfur compounds are removed through a line lil While the vapors are conducted through line 'H to fresh-feed line 2.

The preceding description has broadly outlined the mode of operation f the present invention. However, since the total C4 and lighter olefins are `produced. in a molar excess with respect to benzene, several alternative operations should be considered with respect to the most economical utilization of these by-product streams.

Thus, where it is desired to realize maximum conversion of light olefins to aromatic derivatives, the employment of benzene from some external source is necessary. Make-upbenzene in sufficient quantity to equal or exceed the molar quantity of light olens may be withdrawn from storage through line id and mixed with the 1GO-18()0 F. fraction in line di?. Subsequent to alkylation in 4S and fractionation in column 48, the excess benzene and inert parafns and naphthenes are taken overhead in line 53 from column 5l. In cases where benzene-olefin mol ratios of 2:1 to 4:1' have been employed, it is undesirable t0 recycle this material to the cracking reaction as previously described. Instead a major portion lof this stream is diverted from line 53 into 53a and thence into line 52 from which it is returned to the main product stream. In this Way the excess benzene is recovered along With benzene derived from the cracking reaction Without adversely affecting the equilibrium in the cracking step. However, a minor portion of the overhead from column 5i must be recycled via lines 53, E58, heat exchanger tar trap 69 and line 'Il in order to prevent pyramiding of the parafns and naphthenes in the benzene concentrate. This mode of operation permits the inclusion of appreciable quantities of high quality benzene homologs in the G-350Q F. product fraction.

In those instances where employment of excess b-enzene is not practical, it is usually desirable to convert the available benzene to the most valuabie benzene homolog, cumene. Fractionator 20 in the gas recovery system is operated so as to remove hydrogen, methane and ethylene. Column 23 is then employed to prepare a Ca fraction for the alkylation reactor While the C4 fraction is removed via line 25a for use as feed to codimer operation or isobutane alkylation. In the benzene-propylene alkylation, maximum conversion of benzene is sought, hence the overhead from fractionator El may be recycled to the catalytic cracking step via lines 53 and 68 as originally described. The cumene and di-isopropyl benzene is transferred via lines 52, 25 and heater 26 to the main product stream in line 21. The richmixture blending value of the final 20D-350 F. fraction is greatly increased by the inclusion of this cumene derived exclusively from the by- 1products of the original catalytic cracking operaion.

Similar variations in the gas recovery system may be effected in order to produce ethylbenzene or mixed ethylene and propylene derivatives of benzene.

The process of this invention can utilize a variety of feed stocks including: straight run and cracked gasoline, virgin and cracked naphthas and gas oil. However, Where cracking and aromatization are combined in one operation. a's in the case of virgin naphtha feed, severe temperature conditions are required resulting in considerable formation of dry gas. The preferred feed is a thermally or catalytically cracked gasoline of high carbon to hydrogen ratio and having an ASTM boiling range of about to 400 F.

The catalytic steps of the present process in the order of o-ccurrence are: (1) aromatization, (2) polymerization and (3) alkylation.

The catalyst for the primary conversion to aromatics is preferably an alumina base material which may be of natural or synthetic origin. A preferred catalyst is the naturally occurring mineral bauxite although other catalysts of suitable activity and properties may be used such as synthetic alumina promoted with minor proportions of other metal oxides.

The process operations involving treatment of selected product streams under polymerizing and alkylating conditions are carried out over silicaalumina type catalysts. In general these catalysts are prepared by first forming a hydrous silica gel from an alkali silicate and an acid, extracting soluble material With water, activating the gel with an aqueous solution of a suitable metal salt, and subsequently washing and drying the treated material. In this manner, a part of the metal presumably in the form of a hydrous oxide, is selectively adsorbed by the hydrous silica and is not removed by subsequent washing.

More specifically, the preferred type of silicaalumina catalyst is prepared by treating a Wet or partially dried hydrous silica gel with an aluminum salt solution, such as a solution of aluminum chloride or sulfate, and finally washing and drying the treated material. However, catalysts of a very similar nature but differing among themselves as to one or more specific properties may be prepared by using a hydrolyzable salt of a metal selected from group IIIB or from group IVA of the periodic system, and may be referred to in general as silica-alumina type catalysts. More particularly, salts of indium and thallium in addition to aluminum in group IIIB may be used, and salts of titanium, zirconium and thorium in group IVA may be u'sedto treat silica gel and to prepare catalysts of this general type. Whether prepared by this method or by some modification thereof, the catalysts will contain a major portion of silica anda minor portion of metal oxide. This minor portion of metal oxide, such as alumina, will generally not be in excess of 10 per cent by Weight, and will more often be between about 0.1 and 1.5 to 2 per cent by weight.

The primary catalytic conversion or aromatization stage 0f this proces-s is carried out over the preferred bauxitecatalyst at temperatures ranging from about 1050 to about 1250 F. Moder- ".7 ately superatmospheric pressures are recommended for this reaction such as those extending from atmospheric to about 200 pounds per square inch gage. In many instances it may be desirable to employ a diluent such as steam to aid in temperature control.

One of the features of the present invention is the second stage catalytic treatment of the product stream under polymerizing conditions over the silica-alumina catalyst to elect an ultimate reduction of olen and sulfur content. This operation is preferably conducted as a liquid-phase operation. Pressure in the reactor may vary from about 500 to 2000 pounds gage with a preferred range of about 800 to 1500 pounds.

Operating temperatures for the polymerizing treatment may extend from atmospheric to about 700 F. depending on the characteristics of the original feed 'stock and the extent of purification required. Ordinarily it is preferred to carry out this operation at temperatures of from 200 to 600F.

Hydrocarbon iiow rates through the polymerization reactor under the conditions of this disclosure range from 0.5 to liquid volumes per volume of catalyst per hour although the preferred rates are ordinarily those of 1 to 4 volumes per hour.

A third stage catalytic alkylation treatment of the benzene-containing product stream is another novel feature of the present process. The feed to the alkylation reactor is comprised of the 160-180 F. fraction which has previously been treated for sulfur and olefin removal and a light parain-olefm cut derived from the gaseous products produced in the aromatization operation. A silica-alumina catalyst is employed at temperatures of from about 200 to 700 F. with the preferred temperature being about 450 F. Operating pressures are chosen in accordance with reaction requirements and may vary from about 100 to 1000 pounds. The aromatics-olen feed is adjusted 'so that the benzene to olefin mol ratio lies between about l and 4. v

In order to further illustrate the specific uses and advantages of the present invention, the following exemplary operation will be described. However, since numerous other process modifications will be obvious in the light of the foregoing disclosure, no undue limitations are intended.

Eample The operation as described herein was carried out substantially as indicated in the drawing to prepare an aviation base stock boiling between 200-350 F. and containing the products derived from the alkylation of the benzene stream with a Cz-C4 olefin-parain cut.

The charge to the rst stage catalytic aromatization reaction was a polyform gasoline of 405 F. end-point and 50.1 A. P. I. gravity. i The average temperature of the bauxite catalyst bed was maintained between 1100-l200 F. under a pressure of 85 p. s. i. and at a feed ow-rate of about 6 barrels per ton of catalyst per hour. After stabilization, the yield of butane-free gasoline` amounted to 65 weight per cent based on the charge. This stabilized material was clay-treated and further fractionated into cuts having boiling ranges of 80-200 F. and 200-350 F., respectively.

The lower boiling fraction represented 18.6 weight per cent of the charge and was found to contain 21.5 per cent benzene, about 12 per cent olefin and 0.270 weight per cent sulfur. In order 160-180 F. fraction Composition, Wt. percent Untreated Treated Benzene 60 68 Olen 17 6 Paraln 13 l5 Naphthene 10 l1 Sulfur 0. 275 0.127

The treated benzene concentrate was subjected to alkylation with a typical C2-C4 fraction of light gas produced in the aromatization operation. The gas contained approximately equimolecular proportions of ethylene, propylene and butylenes admixed with the corresponding paraffins such that about volume per cent of the gas was olefinic. The alkylation was carried out at a pressure of 1000 p. s. i. at a temperature of about 500 F. and with a feed rate of 2 volumes per hour per volume of catalyst. The mol ratio of benzene to olen was maintained at 1:1 in order to obtain maximum conversion of benzene. The effluent hydrocarbon was stabilized and fractionated to yield the following data:

Wt. per cent benzene reacted '71 Wt. per cent alkylate overhead at 350 F 73 The weight of 350 F. end-point alkylate realized is approximately the same as the weight of benzene charged. However, the rich-mixture blending value of the alkylate is about twice that of f the benzene, hence the alkylation procedure has resulted in a blending stock equal to about twice the weight of benzene originally produced. In addition, 29 weight per cent of the benzene is now available for recycle as such, while the kettle product will contribute valuable aromatics on further cracking treatment as recycle stock.

The crude aviation blending stock of 200-350 F. boiling range was treated over the silica-alumina catalyst under conditions identical with those employed in treating the light fraction and the eiiluent was rerun to give a finished 200-350 F. blending stock. The improvement in quality as a result of the polymerizing treatment is shown in the following tabulation:

2004350o F. Stock Untreated Treated Sulfur, wt. per cent 0. 279 0. 160 Broniine number 10 4. 0 37. 1 36. 8

The yield of the nished blending stock was 46.4 weight per cent based on the original charge to the aromatization step. Since the original benzene yield was 4.0 per centon the same basis and since the amount of alkylate produced was approximately equal to the original benzene, the

9 overall yield of G-350 F. stock on addition of the alkylate amounted to 50.4 per cent.

The addition of the high-quality alkylate which amounts to about 8 per cent of the nal 20D-350 F. stock increased the rich rating from 2.91 to 4.0 m1. of TEL in S-reference fuel, thus eiective- 1y transforming a moderately good blending stock into a high quality product.

We claim:

1. In a hydrocarbon conversion process of the class described, the steps comprising subjecting a stream of a hydrocarbon feed stock comprising a petroleum distillate having a relatively high carbon to hydrogen ratio to cracking under cyclization conditions in the presence of an aromatizing catalyst at a temperature of between 1050-1250o F.; separating eiiluent from the preceding step into a first fraction comprising normally gaseous olenic material, a, normally liquid about 200 F. end-point second fraction, and a third fraction boiling between about 20G-350 F.; polymerizing a stream of the second fraction the presence of a polymerization catalyst to effect substantial reduction in olen and sulfur content; recovering a benzene-concentrate from effluent from the polymerization step; alkylating a stream oi the benzene-concentrate with at least Dart of said first fraction; recycling at least part of the unreacted eiiluent from the alkylation step to the stream of feed stock; and transmitting reacted efuent from the alkylation step to effluent from the cracking step.

2. The process in accordance with claim l wherein a stream of the third fraction is treated under polymerizing conditions and the so treated third fraction is then fractionated to recover a fraction boiling between about 20G-350 F. and substantially free of sulfur compounds.

3. The process in accordance with claim l. wherein the indiivdual cracking and polymerizing steps are each carried out in the presence of a corresponding suitable catalyst material.

4. The process in accordance with claim l wherein the cracking step is carried out in the presence of a bauxite catalyst and the polymerizing steps are each carried out in the presence of a silica-alumina catalyst.

5. In a process for the manufacture of aviation gasoline blending stock having a high concentration of aromatic hydrocarbons, the steps comprising aromatizing a stream of a feed stock comprising hydrocarbons of relatively high carbon to hydrogen ratio and boiling between about 150- 400 F. in the presence of an aromatizing catalyst at a temperature between 1050-l250 F.; recovering from efliuent from the preceding step a first fraction comprising normally gaseous olennic material, a normally liquid about 200 F. enolpoint second fraction. and a third fraction boiling between about 200-350o F.; polymerizing a stream of the second fraction in the presence of a catalyst to effect substantial reduction of olefin and sulfur content; fractionating a stream of eliluent from the last named step to obtain a benzene fraction boiling between about 160-180 F.; alkylating said benzene fraction with said first fraction in the presence of a catalyst; recycling unreacted effluent from the alkylation step to the stream of feed stock; transmitting total alkylate from the eiiluent from the alkylation step to eli'luent from the aromatization step at such a point that said total alkylate may be further treated along with reacted products of said aromatizing step; and polymerizing the final third fraction in the presence of a 10 catalyst to elect removal of olefin and sulfur content.

6. 1n a. process for the manufacture of aviation gasoline blending stock having a high concentration of aromatic hydrocarbons, the steps comprising aroinatizing a stream of a feed stock comprising hydrocarbons of relatively high carbon to hydrogen ratio and boiling between about 150- 400 F. in the presence of a catalyst; separating eiiuent from the preceding step to obtain a normally gaseous fraction comprising Cl and lighter cleins and a normally liquid fraction comprising about 350 F. end-point reacted eliluent, fractionating said liquid fraction to obtain a 200 F. endpoint fraction and a fraction boiling between 20G-350 F.; polymerizing a stream of the 200 F. end-point fraction in the presence of a catalyst to effect substantial reduction of olefin and sulfur content; fracticnating stream of eiluent from the last named step to obtain a benzene fraction boiling between about i60-180 F.; alkylating said benzene fraction with said normali gaseous fraction in the presence of a catalyst; recycling unreacted eiiiuent from the alkylation step to the stream of feed stock; recycling total alkylate from the eiiluent 0f the alkylation step to the 350 F. end-point liquid fraction; polymerizing the final 20G-350 F. boiling fraction in the presence of a catalyst; and separating a substantially olen and sulfur free product boiling between 20o-350 F. from eiiuent from the last mentioned step.

'7. The process in accordance with claim 6 wherein the aromatizing step is carried out in the presence of an aiumina base catalyst and the alkylatinT and polymerizing steps are each carried out in the presence of a corresponding silicaalumina catalyst.

8. The process in accordance with claim 6 wherein the aromatizing step is carried out at temperatures within the range of 1050-l250 F. and at pressures within the range of atmospheric to 200 pounds per square inch gauge; wherein the polyrnerizing steps are each carried out at temperatures within the range of 200-600 F. and at pressures within the range of G-1500 pounds per square inch gauge; and wherein the alkylating stepl is carried out at temperatures within the range of 20G-700 F, and at pressures within the range of 1004.000 pounds per square inch gauge.

9. The process in accordance with claim 6 wherein the aromatizing step is carried out at temperatures within the range of 1050-1250 F. and at pressures within the range of atmospheric to 200 pounds per square inch gauge in the presence of an alumina base catalyst; wherein the polymerizing steps are each carried out at temperatures within the range of 20D-600 F. and at pressures within the range of 80G-1500 pounds per square inch gauge in the presence of a corresponding silica-alumina catalyst; and wherein the alkylating step is carried out at temperatures within the range of 20G-'700 F. and at pressures within the range of 10G-1000 pounds per square inch gauge in the presence of a silica-alumina catalyst.

10. The process as in claim 6 characterized by the alkylation of the benzene fraction with ethylene segregated from the normally gaseous fraction.

l1. The process as in claim 6 characterized by the alkylation of the benzene fraction with propylene segregated from the normally gaseous fraction.

12. The process as in claim 6 characterized by the alkylation of the benzene fraction with butyl- 1l 12 ene segregated from the normally gaseous frac- 350 F. and a higher-boiling fraction containing tion. polymers and sulfur compounds, and said higher- 13. The process in accordance with claim 6 boiling fraction is recycled to the feed stock wherein effluent from the second polymerzng stream,

step is separated into a substantially olefin and WALTER A. SCHULZE. sulfur free product fraction boiling between 2.00- 5 CARL J. HELMERS.

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