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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 2,403,879 UNITED STATES PATENT OFFICE 2,403,879 PROCESS 0F MANUFACTURE 0F AVIATION ‘ GASOLINE BLENDING STOCKS Walter A. Schulze and Carl J. Helmers, Bartles ville, Okla., assignors to Phillips Petroleum Company, a corporation of Delaware l Application March 10, 1944, Serial No. 525,922 13 Claims. (Cl. 260-671) This invention relates to the production of 2 the yield and quality of blending stocks for avi ation gasoline by means of combined catalytic al kylation and treating steps. Still another object of this invention is the high octane hydrocarbon fuels by the catalytic conversion of petroleum hydrocarbons. More specifically the invention relates to the produc tion of aromatic hydrocarbon concentrates suit 5 provision of an integrated process for the pro able for inclusion in aviation gasolines through duction of aromatic blending stocks of low sulfur a novel sequence of catalytic operations. and oleñn content through the catalytic treat The production and recovery of aromatic hy ment of selected fractions of the raw aromatic drocarbons from petroleum sources are of par 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 ticular 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 in creased the demand for aromatic hydrocarbons to multiple-pass catalytic cracking operations. Subsequent to the relatively mild operating con ditions employed in the catalytic aromatization because of the extra power in rich-mixture per formance derived from aromatics-containing gas of the present process, -a substantial increase in oline blends. In order to augment the supply of the rich mixture rating of the aviation base stock aromatic distillates, thermal and catalytic crack is effected by a combination of two outstanding ing of petroleum hydrocarbons have been em 20 novel features: (l) segregation of the benzene ployed to produce aviation blending stocks with fraction followed by alkylation with the oleñnic the latter processes producing products superior constituents from the primary catalytic reaction to the straight thermal procedures. However, it to produce alkyl benzenes greatly superior to ben is well known that heretofore in order to produce zene in rich mixture blending Value; (2) applica high-quality aromatic distillates relatively severe 25 tion of a catalytic treating operation to the prod conditions of catalytic cracking were required, uct stream to remove deleterious impurities there often involving multiple-pass catalytic cracking by greatly improving the rich-mixture rating of operations. Under such conditions the produc the base stock. tion of light gases may amount to 50 weight per The beneficial results realized from the above 30 cent or more of the original charge stock. It is features are such that the utility of catalytic 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 charac teristics, but also on very low proportions of un cracking oper-ations has been greatly extended. Of inestimable value is the conservation of feed stocks, since with our novel process it is now pos 35 sible to produce a high quality aromatic distil late with less severe cracking conditions for a given S-C rating. The aromatics content of the finished»v blending- stock is increased by virtue of 40 desirable hydrocarbon types which impair the blending 3-C octane values of the aromatics-rich fractions. The quality of the aromatic blending stœks as measured in flight tests and by the S-C supercharged engine can often be greatly im pp. Ul proved by the substantially complete removal of non-hydrocarbon impurities such as sulfur com pounds. It is also recognized that further quali ty improvement can be eifected by conversion of the benzene content of blending stocks to higher homologs through alkylation with oleñns 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 hydro carbon and non-hydrocarbon impurities by means of an interrelated sequence of controlled catalytic operations. the alkylation of the benzene fraction, since freez ingv point consider-ations often preclude the inclu sion of the total benzene fraction as such. An other 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 elîects of the alkylation and the treating operations. Considering only its broader aspects, the pres- ` ent process may be operated in the following man ner to accomplish the objects and advantages previously set forth. Ordinarily a petroleum dis tillate 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 al kylation feed while the stabilized gasoline is clay treated and separated by fractionation into a 200° F. end-point benzene-containing stream and a higher-boiling 350° F. end-point aviation blend ing stock. The lower boiling fraction is treated Another object of this invention is to increase 60 catalytically under polymerizing conditions to 2,403,879 3 remove sulfur and oleiinic material, both of which are undesirable in the subsequent alkylation step. A purified and refractionated benzene-concen trate is catalytically alkylated with any one or any combination of the light oleñns previously produced in the primary conversion. The lean flash vaporization tower 26. Normally liquid product hydrocarbons from the gas plant and alkylation operations are conveniently added at this point from line 25 and preheater 2S. The overhead vapors of approximately 400 E. P. are conducted through a line 30 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 tionated product stream where its valuable con 10 is divided for subsequent processing. stituents are segregated in the 350° F. end-point The overhead stream from 33 is comprised of stock. This latter material is then catalytically hydrocarbons boiling from C5 to 200° F. and is treated under polymerizing conditions to produce relatively rich in benzene and oleiins. This ma a finished product of high rich-mixture blending terial is passed through a line 34 to a heater 35 value. The secondary polymerization and alkyla 15 where its temperature is raised to a suitable value tion steps of this process not only coact to exert of about 400° F. under sufñcient pressure to main benzene effluent stream from the alkylation step is recycled to the cracking step while the total alkylate is fed directly into the main unfrac a direct favorable effect on the volume and qual tain substantially liquid-phase conditions, The ity of finished product, but they also contribute hot liquid is discharged directly into a catalyst valuable recycle stock of high carbon to hydro case 3S which is filled with the preferred silica 20 gen ratio to the primary conversion step thereby alumina catalyst composition. The treated ef further increasing the yield of aromatics as based ñuent is partially vaporized in line 31 as the pres on fresh feed. sure is reduced and fractionation is effected in The accompanying simplified drawing shows a column 38. A fraction having an end-point of one specific diagrammatic arrangement of appa about 160° F. is taken overhead to motor fuel ratus by which the present process may be car storage through a line 39 while the kettle product ried out. It should be understood, however, that is taken Via a line 4i] -to a fractionator M where >the invention is not limited to processing as here in disclosed and that Various modifications of the process and apparatus may be made without de parting from the scope of the invention as de fined in the appended claims. Referring to the drawing, a thermally or cata lytically 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 opti mum aromatics formation. The efñuent 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 a benzene concentrate boiling between M50-180° F. constitutes the overhead product and the ket tle product containing oleñn 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-parañin gases from line 26 just ahead of heating coil 45. The alkylation charge is pre heated to alkylation conditions under a pressure sufficient to maintain liquid or dense phase con ditions and is discharged directly into the alkyla tion 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 parafûns and any unreacted olefms being removed through a lineêâ to be employed as reñnery 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 paraf finic constituents of the original benzene concen trate are conducted through a line 53 to the re cycle transfer line yESB: The kettle product from 'i column 5i which contains a mixture of mono and 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 heavier hydrocarbons. The rich absorbing liquid manner alkylate boiling below about 400° F. is is >then returned to the main product stream via (lil passed on to further treatment and the high lines i8 and 25. The C4 and lighter gases are boiling alkylate finds its way into the recycle conducted through a line i9 to a fractionator 20 line ES via line 29. where hydrogen and methane are the .principal After removal of the 200° F. end-point fraction components of the overhead fraction that are re in column 33, the main aviation base stock ma moved through a line 2| while the kettle product terial, which now includes aromatics recon is transferred in a line 22 to a column 23 where structed from the oleñns and benzene as well as a gas fraction comprising C2, Cs, and C4 hydro aromatics produced in the original cracking step, carbons is prepared and charged to an alkylation is passed through a line 513 into a fractionator 55. unit 45 via a line 2e. The small quantity of Ct-ì fraction boiling between 20G-350° F. is taken hydrocarbons comprising the kettle product of 70 A overhead in a line 51 while material distilling , column 23 is added to the main product stream above 350° F. is discharged through line 5S into _through line 25. recycle line 6o. A portion of the overhead cut is The stabilized product stream from separator 9 is withdrawn through a line 21, preheated in diverted into a line 58, a condenser 59 and a re heat exchanger 1 and finally discharged into a 75 flux tank _50. The condensed material not only 2,403,879 5 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, 6 is transferred via lines 52, 25 and heater 26 to the main product stream in line 21. The rich mixture 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 opera ion. 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 vari ety of feed stocks including: straight run and cracked gasoline, virgin and cracked naphthas and gas oil. However, Where cracking and aro matization are combined in one operation. a's in the case of virgin naphtha feed, severe tempera 55 and 85 as Well as a light overhead fraction ture conditions are required resulting in consid from column 5 l, is passed through heat exchanger erable formation of dry gas. The preferred feed 7 into a tar trap 69 Where partial vaporization 20 is a thermally or catalytically cracked gasoline of occurs. High boiling refractory hydrocarbons high carbon to hydrogen ratio and having an and sulfur compounds are removed through a line ASTM boiling range of about 150 to 400° F. ‘lil While the vapors are conducted through line The catalytic steps of the present process in 'H to fresh-feed line 2. the order of o-ccurrence are: (1) aromatization, The preceding description has broadly outlined (2) polymerization and (3) alkylation. the mode of operation 0f the present invention. The catalyst for the primary conversion to aro However, since the total C4 and lighter olefins are matics is preferably an alumina base material `produced. in a molar excess with respect to ben which may be of natural or synthetic origin. A zene, several alternative operations should be con preferred catalyst is the naturally occurring sidered with respect to the most economical uti 20 mineral bauxite although other catalysts of suit lization of these by-product streams. able activity and properties may be used such as Thus, where it is desired to realize maximum synthetic alumina promoted with minor propor conversion of light olefins to aromatic derivatives, tions of other metal oxides. the employment of benzene from some external The process operations involving treatment of source is necessary. Make-up- benzene in suffi selected product streams under polymerizing and cient quantity to equal or exceed the molar quan alkylating conditions are carried out over silica tity of light oleñns may be withdrawn from stor alumina type catalysts. In general these cata age through line ¿id and mixed with the 1GO-18()0 lysts are prepared by first forming a hydrous F. fraction in line di?. Subsequent to alkylation in 4S and fractionation in column 48, the excess 40 silica gel from an alkali silicate and an acid, ex tracting soluble material With water, activating benzene and inert parafñns and naphthenes are the gel with an aqueous solution of a suitable 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 re metal salt, and subsequently washing and drying the treated material. In this manner, a part of cycle this material to the cracking reaction as 45 the metal presumably in the form of a hydrous oxide, is selectively adsorbed by the hydrous silica previously described. Instead a major portion and is not removed by subsequent washing. lof this stream is diverted from line 53 into 53a More specifically, the preferred type of silica and thence into line 52 from which it is returned alumina catalyst is prepared by treating a Wet or to the main product stream. In this Way the excess benzene is recovered along With benzene 50 partially dried hydrous silica gel with an alu minum salt solution, such as a solution of alu derived from the cracking reaction Without ad versely affecting the equilibrium in the cracking step. However, a minor portion of the over head from column 5i must be recycled via lines minum chloride or sulfate, and finally washing and drying the treated material. However, cata lysts of a very similar nature but differing among 53, E58, heat exchanger ï, tar trap 69 and line 'Il 55 themselves as to one or more specific properties may be prepared by using a hydrolyzable salt of in order to prevent pyramiding of the parafûns a metal selected from group IIIB or from group and naphthenes in the benzene concentrate. This IVA of the periodic system, and may be referred mode of operation permits the inclusion of appre to in general as “silica-alumina type” catalysts. ciable quantities of high quality benzene homo 60 More particularly, salts of indium and thallium logs in the 20G-350Q F. product fraction. in addition to aluminum in group IIIB may be used, and salts of titanium, zirconium and tho rium in group IVA may be u'sedto treat silica gel and to prepare catalysts of this general type. valuabie benzene homolog, cumene. Fractiona tor 20 in the gas recovery system is operated so as 65 Whether prepared by this method or by some modification thereof, the catalysts will contain to remove hydrogen, methane and ethylene. Col a major portion of silica anda minor portion of umn 23 is then employed to prepare a Ca fraction metal oxide. This minor portion of metal oxide, for the alkylation reactor While the C4 fraction is such as alumina, will generally not be in excess removed via line 25a for use as feed to codimer of 10 per cent by Weight, and will more often be operation or isobutane alkylation. In the ben between about 0.1 and 1.5 to 2 per cent by weight. zene-propylene alkylation, maximum conversion The primary catalytic conversion or aromatiza of benzene is sought, hence the overhead from fractionator El may be recycled to the catalytic tion stage 0f this proces-s is carried out over the preferred bauxitecatalyst at temperatures rang~ cracking step via lines 53 and 68 as originally de scribed. The cumene and di-isopropyl benzene 75 ing from about 1050 to about 1250° F. Moder In those instances where employment of ex cess b-enzene is not practical, it is usually desirable to convert the available benzene to the most 2,403,879 ".7 8 ately superatmospheric pressures are recom mended for this reaction such as those extending from atmospheric to about 200 pounds per square inch gage. In many instances it may be desir to reduce unsaturation and sulfur this material was processed over a silica-alumina catalyst un der a pressure of 1000 p. s. i. and at `an average catalyst case temperature of 375° F., with a flow rate of 2 to 3 liquid volumes per volume of cata lyst per hour. The treated eiiiuent was frac able to employ a diluent such as steam to aid in temperature control. tionally distilled to prepare a benzene concen trate boiling from 160 to 180° F. To show the value of the polymerizing treatment the same One of the features of the present invention is the second stage catalytic treatment of the prod uct stream under polymerizing conditions over the silica-alumina catalyst to elîect an ultimate re duction of oleñn and sulfur content. This oper ation is preferably conducted as a liquid-phase operation. Pressure in the reactor may vary from about 500 to 2000 pounds gage with a pre ferred range of about 800 to 1500 pounds. concentrate was prepared from a sample of un treated stock. ` 160-180° F. fraction Composition, Wt. percent Untreated Treated 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 Benzene ___________________________________ _. Oleûn _____________________________________ _. Parañln ___________________________________ ._ Naphthene _______________________________ _ _ Sulfur _____________________________________ ._ 60 17 13 68 6 10 l5 l1 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 opera ization reactor under the conditions of this dis closure range from 0.5 to 10 liquid volumes per 25 tion. The gas contained approximately equi molecular proportions of ethylene, propylene and volume of catalyst per hour although the pre butylenes admixed with the corresponding paraf ferred rates are ordinarily those of 1 to 4 volumes fins such that about 50 volume per cent of the per hour. gas was olefinic. The alkylation was carried out A third stage catalytic alkylation treatment of at a pressure of 1000 p. s. i. at a temperature of the benzene-containing product stream is another about 500° F. and with a feed rate of 2 volumes novel feature of the present process. The feed per hour per volume of catalyst. The mol ratio to the alkylation reactor is comprised of the of benzene to oleñn was maintained at 1:1 in or 160-180° F. fraction which has previously been der to obtain maximum conversion of benzene. treated for sulfur and olefin removal and a light paraiñn-olefm cut derived from the gaseous pro 35 The effluent hydrocarbon was stabilized and 600°F. . Hydrocarbon iiow rates through the polymer ducts produced in the aromatization operation. A silica-alumina catalyst is employed at tempera fractionated to yield the following data: tures of from about 200 to 700° F. with the pre Wt. per cent alkylate overhead at 350° F____ 73 ferred temperature being about 450° F. Wt. per cent benzene reacted _____________ __ '71 Oper ating pressures are chosen in accordance with 40 The weight of 350° F. end-point alkylate realized is approximately the same as the weight of ben reaction requirements and may vary from about zene charged. However, the rich-mixture blend ing value of the alkylate is about twice that of 100 to 1000 pounds. The aromatics-oleñn feed is adjusted 'so that the benzene to olefin mol ratio v f the benzene, hence the alkylation procedure has In order to further illustrate the specific uses and advantages of the present invention, the fol 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° lies between about l and 4. . lowing exemplary operation will be described. However, since numerous other process modifica tions will be obvious in the light of the foregoing disclosure, no undue limitations are intended. Eœample F. boiling range was treated over the silica-alu The operation as described herein was carried out substantially as indicated in the drawing to prepare an aviation base stock boiling between mina catalyst under conditions identical with those employed in treating the light fraction and 200-350° F. and containing the products derived from the alkylation of the benzene stream with F. blending stock. The improvement _in quality a Cz-C4 olefin-parañin cut. in the following tabulation: ' the eiiluent was rerun to give a finished 200-350° as a result of the polymerizing treatment is shown The charge to the ñrst stage catalytic aromati zation reaction was a polyform gasoline of 405° F. 60 2004350o F. Stock end-point and 50.1° A. P. I. gravity. i The aver age temperature of the bauxite catalyst bed was maintained between 1100-l200° F. under a pres sure of 85 p. s. i. and at a feed ñow-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 Untreated Sulfur, wt. per cent _______________________ ._ Broniine number __________________________ ._ 0. 279 10 Treated 0. 160 4. 0 37. 1 0. 95 36. 8 0.85 1. 20 2. 91 weight per cent of the charge and was found to contain 21.5 per cent benzene, about 12 per cent The yield of the ñnished 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 olefin and 0.270 weight per cent sulfur. In order approximately equal to the original benzene, the ranges of 80-200° F. and 200-350° F., respec tively. The lower boiling fraction represented 18.6 9 2,403,879 overall yield of 20G-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 ñnal 20D-350° F. stock increased the rich rating from 2.91 to 4.0 m1. of TEL in S-reference fuel, thus eiîective 1y transforming a moderately good blending stock into a high quality product. We claim: 10 catalyst to elîect removal of olefin and sulfur content. 6. 1n a. process for the manufacture of aviation gasoline blending stock having a high concentra tion of aromatic hydrocarbons, the steps compris ing aroinatizing a stream of a feed stock compris ing hydrocarbons of relatively high carbon to hydrogen ratio and boiling between about 150 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 aro matizing catalyst at a temperature of between 1050-1250o F.; separating eiiluent from the pre ceding step into a first fraction comprising nor mally gaseous oleñnic material, a, normally liquid about 200° F. end-point second fraction, and a 400° F. in the presence of a catalyst; separating e?iiuent from the preceding step to obtain a nor mally gaseous fraction comprising Cl and lighter cleîins and a normally liquid fraction comprising about 350° F. end-point reacted eliluent, fraction ating said liquid fraction to obtain a 200° F. end point 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 eiîluent from the last named step to obtain a benzene fraction third fraction boiling between about 20G-350° F.; boiling between about i60-180° F.; alkylating said the polymerizing presence of a stream a polymerization of the second catalyst fraction to ef benzene fraction with said normali- gaseous frac tion in the presence of a catalyst; recycling un fect substantial reduction in oleñn and sulfur content; recovering a benzene-concentrate from effluent from the polymerization step; alkylating reacted 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. a stream oi’ the benzene-concentrate with at least end-point liquid fraction; polymerizing the final 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 re acted efñuent from the alkylation step to effluent 20G-350° F. boiling fraction in the presence of a catalyst; and separating a substantially oleñn and sulfur free product boiling between 20o-350° F. from eiîiuent from the last mentioned step. from the cracking step. '7. The process in accordance with claim 6 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 wherein the aromatizing step is carried out in the presence of an aiumina base catalyst and the al kylatin‘T and polymerizing steps are each carried out in the presence of a corresponding silica alumina catalyst. substantially free of sulfur compounds. 8. The process in accordance with claim 6 wherein the aromatizing step is carried out at wherein the indiivdual cracking and polymeriz 40 temperatures within the range of 1050--l250° F. ing steps are each carried out in the presence of and at pressures within the range of atmospheric a corresponding suitable catalyst material. to 200 pounds per square inch gauge; wherein 4. The process in accordance with claim l the polyrnerizing steps are each carried out at wherein the cracking step is carried out in the temperatures within the range of 200-600° F. and presence of a bauxite catalyst and the polymer 45 at pressures within the range of 80G-1500 pounds izing steps are each carried out in the presence per square inch gauge; and wherein the alkylating of a silica-alumina catalyst. stepl is carried out at temperatures within the 3. The process in accordance with claim l. 5. In a process for the manufacture of aviation gasoline blending stock having a high concentra tion of aromatic hydrocarbons, the steps compris ing aromatizing a stream of a feed stock compris ing 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.; recov ering from efliuent from the preceding step a first 50 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 pres ence of an alumina base catalyst; wherein the polymerizing steps are each carried out at tem peratures within the range of 20D-600° F. and at pressures within the range of 80G-1500 pounds per fraction comprising normally gaseous olennic material, a normally liquid about 200° F. enol square inch gauge in the presence of a corre point second fraction. and a third fraction boiling between about 200-350o F.; polymerizing a stream 60 sponding silica-alumina catalyst; and wherein the alkylating step is carried out at temperatures of the second fraction in the presence of a catalyst within the range of 20G-'700° F. and at pressures to effect substantial reduction of olefin and sulfur within the range of 10G-1000 pounds per square content; fractionating a stream of eli‘luent from inch gauge in the presence of a silica-alumina the last named step to obtain a benzene fraction boiling between about 160-180° F.; alkylating said 65 catalyst. benzene fraction with said first fraction in the presence of a catalyst; recycling unreacted effluent from the alkylation step to the stream of feed 10. The process as in claim 6 characterized by the alkylation of the benzene fraction with eth ylene segregated from the normally gaseous frac tion. stock; transmitting total alkylate from the eii‘lu l1. The process as in claim 6 characterized by ent from the alkylation step to eli'luent from the 70 the alkylation of the benzene fraction with pro aromatization step at such a point that said total pylene segregated from the normally gaseous alkylate may be further treated along with reacted fraction. products of said aromatizing step; and polymeriz 12. The process as in claim 6 characterized by ing the final third fraction in the presence of a 75 the alkylation of the benzene fraction with butyl 2,403,879 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 wherein effluent from the second polymerízìng step is separated into a substantially olefin and sulfur free product fraction boiling between 2.00- 5 boiling fraction is recycled to the feed stock stream,? ‘ WALTER A. SCHULZE. CARL J. HELMERS.