US2461153A - Method of manufacturing high antiknock synthesis gasoline - Google Patents

Description

' A. R. GOLDSBY METHOD OF MANUFACTURING HIGH ANTIKNOCK SYNTHESIS GASOLINE Filed April 14, 1945 Feb. 8, 1.949.

Patented Feb. 8, k1949 METHOD OF MANUFACTURING HIGH ANTI- KNOCK SYNTHESIS GASOLINE Arthur R. Goldsby, Beacon, N. Y., assignor to Texaco Development Corporation', New York, N. Y., a corporation of Delaware Application April 14, 1945, Serial No. 588,309

8 Claims.

This invention relates to the manufacture of high antiknock gasoline hydrocarbons from carbon oxides and hydrogen.

The catalytic synthesis reaction of a carbon oxide and hydrogen to form higher molecular weight hydrocarbons, both normally gaseous yand normally liquid, is well-known. However, the gasoline produced by this known process is of nferior character, being of lower antiknock value than cracked gasolinas or straight-run gasolines from petroleum. Also, there is an appreciable loss in yield of the desired gasoline hydrocarbons, since the synthesis products are of wide boiling range including a substantial proportion of normally gaseous hydrocarbons from C2 to C4 inclusive, and also a substantial proportion of normally liquid hydrocarbons of lower boiling range than Diesel fuel but of higher boiling range than desired for aviation gasoline.

One of the principal objects of this invention is to produce high antiknock gasoline hydrocarbons suitable for aviation gasoline base stock and high quality motor fuel in good yields from carbon oxides and hydrogen.

A further object is to provide a combination process including hydrocarbon synthesis, alkylation, isomerization and catalytic conversion for producing a high yield of unusuallsr high octane gasoline within the aviation fuel boiling range from car-bon oxides and hydrogen.

Another object of the invention is to provide a unitary or self-contained process for accomplishing the foregoing objects, wherein any substantial amounts of extraneous hydrocarbons other than those produced in the system are not required, so that the plant can be located near the source of supply of the carbon oxide and hydrogen and is not dependent on an outside supply of petroleum hydrocarbons.

Other objects and advantages of the invention will be apparent from the following description when taken in conjunction with the appended claims and the accompanying drawing.

In my prior Reissue No. 22,205 of Patent No. 2,257,074, a process is disclosed wherein carbon oxide `and hydrogen are catalytically reacted, the resulting synthesis products are separated into a normally gaseous fraction and a, normally liquidv l naptha fraction,l and the said fractions are separately subjected to catalytic :alkylation with an isoparaiiln, such as isobutane. While this process increasestheyield and antiknock value of the gasoline hydrocarbons so-produced, the alkylation step on the normallyliquid fraction is not as effective as desired since 4the resulting alkylate is diluted with a large proportion of unconverted normal parafn hydrocarbons originally present in the synthesis products.

In accordance with the present invention, the carbon oxide and hydrogen synthesis products are fractionated to separate a C4 fraction, a, light naphtha fraction `boiling below C9, a heavy naphtha fraction from about Cs up to 40G-450 F. end point, a Diesel fuel fraction and wax. The C4 fraction is subjected to catalytic alkylation to produce gasoline alkylate, and unreacted normal butane of the C4 fraction is catalytically isomerized to form isobutane to supply isobutane for the said alkylatlon step. The light naphtha fraction is subjected Ato absorption with an acid to convert the normally liquid oleflns to the corresponding esters of said acid. The acid-olefin extract is separated from the unabsorbed paraiin raillnate, and the absorbed olefins are then subjected to catalytic alkylation separately from the parafns, utilizing isobutane produced in the above-mentioned isomerization step, thereby forming additional gasoline alkylate of high quality. The parain allnate is in turn subjected to catalytic isomerization, preferably in the presence of anv added butane obtained from the synthesis products, under conditions toform a gasoline isomate of paraftns of increased -branched chain structure and of substantially improved antiknock quality, while concomitantly producing isobutane. The net production of isobutane in this latter step further makes up'any deficiency of isobutane charge for the mentioned catalytic alkylation steps.

The heavy naphtha fraction is in turn subjected to catalytic conversion, such as hydroforming, cyclization, or reforming, under conditions to lower the boiling distribution range and increase the antiknock value of said 'naphtha and concomitantly produce additional C4 hydrocarbons including butanes. The said C4 hydrocarbons Aproduced in the catalytic conversion are separated and returned to the system, whereby normal butane is supplied to the normal butane isomer- 'ization step, and isobutane is utilized in the charge to the catalytic alkylation steps. In this manner, suirlcient butanes are produced'in the system to supply the isobutane requirements of the alkylatlon steps `and the butane requirement of the paraiiin raffinate isomerization step. Aviation gasoline fractions from the resulting alkylates, isomate and hydroformate or other catalytic `conversion product may be blended to thereby obtain a high yield ofaviation gasoline of high antiknock value; while heavier fractions of said quality, while avoiding thenecessity of securing extraneous supplies of petroleum hydrocarbons for the system.

The invention is more particularly illustrated 'in the attached drawing wherein the single ngure is a now diagram of a preferred form of the invention. I

Referring to the drawing, the numeral I0, indicates the hydrocarbon synthesis reactor, wherein hydrogen and a carbon oxide, preferably carbon monoxide. are reacted in the ratio of two mois of hydrogen to one of carbon monoxide in the presence of a suitable synthesis catalyst in well-known manner. The usual catalyst, comprising a metal of the eighth group of the periodic system, particularly cobalt, nickel and iron, together with activating constituents such as oxides of magnesium, thorium, aluminum and combinations thereof, may be employed, either alone or preferably in conjunction with a contact mass of the character of filter cel, in a vapor phase fixed bed operation. 4The carbon monoxide and;

hydrogen gases are passed 'through the catalyst bed at temperatures of S25-550 F., preferably about S60-400 F., and under a pressure from atmospheric up to 100 atmospheres but preferably near or not substantially above atmospheric pressure for preferential production of hydrocarbons of motor fuel boiling range, utilizing a space velocity of about -150 and preferably around 100. It will be understood that the catalyst beds may be prepared, reduced. and conditioned in the usual manner, and may/be employed in a cyclic process in which unreacted carbon monoxide and hydrogen are recycled.

With catalysts such as cobalt, nickel or iron, synthesis products are formed in which normal paraffin and: olen hydrocarbons predominate from C2 ,up to and including heavy paraffin waxes. However, it is known that under certain special conditions, rthe resulting synthesis products may contain both normal and lsoparafflns, normal and isoolens, and even-naphthenes and aromatics. The present invention is particularly applicable to the upgrading of the usual synthesis products consisting essentially of normal parafiins and oleins. However, it will be understood that the incomprise mainly high cetane Diesel fuel and parailln wax.

'Ihe synthesis products pass to a fractionating system indicated t II from which the unreacted gases together wi h C3 and lighter may be removed from a stabilizer and passed by line I2 to a suitable absorption oil recovery system for the recovery of C2 and Ca hydrocarbons, and separation of unreacted carbon monoxide and hydrogen for recycling in the system in the manner set forth above. A stream of C4 hydrocarbons, or C4 containing a light cut of Cs so as to eliminate most of the normal pentane, is removed by line I3 and passed to the catalytic alkylation step I4.

A light naphtha cut boiling below Ca, which is preferably Cs-Cr although it may be Cs-Ca or even Cs-Cs, is removed by line I5 and passed to the absorption step I6. A heavy naphtha fraction, which includes the balance of the naphtha up to about 40G-450 end point or up to the initial boiling point of the Diesel fuel fraction, is removed by line I1 to the catalytic conversion step I8. The remaining bottoms of the synthesis products are t passed by line I9 to fractionator 20,where Diesel l thence into a settler, where the acid-olefin extract separates as a lower layer from the upperhydrocarbon rafnate containing' unabsorbed paraflin hydrocarbons. Where the synthesis products are prepared with cobalt, nickel or iron catalyst, and

40 consist mainly of paraffin and olen hydrocarvention can be applied with advantage to syn` thesis products containing other constituents inproducts may be C4 with an olen content of 2,383,056 dated August 21, 1945, to selectively absorb the olens in the presence of aromatics and without any substantial absorption of the latter. As set forth therein, this is accomplished by contacting the naphtha with strong sulfuric acid of 96-100% strength at a temperature of about lil-30 F., employing a time of contact of about {t0-60 seconds. This serves to extract the bulk of the oleflns without any substantial absorption,

of aromatics, particularly where a large excess around 50-55% by volume. The naphtha frace employed in the usual manner, the balance will of strong acid to naphtha is employed in the cold acid contacting step.

The resulting acid-olefin extract is removed fromI the lower layer of -the settler, or from the outer layer where centrifuge separation is employed, and passed by line 25 to either of branch lines 26 and 2 leading to the ester extraction' zone 28 and the catalytic alkylation zone 29 respectively. In the ester extraction zone 28, the acid-olefin extract is contacted with a lov;1 boiling isoparamn, such as isobutane, introduced by line 30, which serves to dissolve ester from the acid. Preferably a large excess of isobutane to acidolefin extract is employed at temperatures of about 30-60 F., and'the mixture then allowed to stratify into an upper isoparafiln or isobutane layer containing the dissolved olefin ester, and a lower acid layer which is removed by line 3i. The isoparailln layer is then passed by line 32 to the catalytic alkylation step, where fresh alkylation catalyst is introduced by line 33. Where the three-stage operation of absorption, ester extraction and alkylation is employed, the absorption step is prefei'ably carried out with a lower ratio of acid to naphtha which is conducive to the for-- mation of the diester. The acid esters of the lower molecular weight oleflns are less soluble in isobutane than the corresponding diesters. Consequently, by coordinating the absorption step to produce mainly the diester, a lower ratio of isobutane to extract may be employed in 28 with satisfactory ester extraction. While diester formation is particularly important in connection with absorbed C4 olens, it is not so vital in the case of C5 and higher oleflns, and the absorption step may be carried out under conditions to produce largely the acid esters of the light naphtha oleflns, even Where the three-stage operation is employed. Where sulfuric acid is employed as the alkylation catalyst, it is generally preferred to use two-stage operation wherein the acid olefin extract is passed directly by line ,2l to the catalytic alkylation zone 29. In such case, the absorption step is preferably carried out with the use of a large excess of acid to olen, such as about 20l00:1, thereby producing mainly the acid ester.

In the catalytic alkylation step 219, the extract containing absorbed light naphtha olens in the form of esters is agitated with a large excess of isbutane introduced by line 34, together with alkylation catalyst introduced by line 33. A mola'.y ratio of isobutane to olen equivalent of the order of 3:1 to 6:1 is preferably employed, and emulsion or hydrocarbon recycle may also be used to mateo -rially increase the itnernal ratio to above about 100:1 as is well understood. Where sulfuric acid is employed as the catalyst, the makeup acid to this step is at least about 88% and preferably about 90% concentration or higher, whereby the strength of the acid in the system is maintained above about 85% with a water content below 4%, the balance being mainly organic matter. The operation is carried out at a temperature of about 30-60 F. and under sulcient pressure to maintain the reactants in liquid phase, employing a volume ratio of acid to hydrocarbons in the reaction zone of about 0.8:1 up to about 2:1 andi preferably about 1:1. Efficient agitation is employed, whereby isobutane is alkylated with the absorbed olens to produce a high yield of alkylate consisting of highly branched or isoparafflnic hydrocarbons within the gasoline boiling range and of high antiknock value. The resulting alkylation products are passed to a settler where the hydrocarbon phase separates from a lower acid phase, the latter being removed and recycled byline 35 to the absorption step.

While sulfuric acid has been particularly described as the alkylation catalyst, it will be understood that this is merely preferred and that other conventional alkylation catalysts may be employed, such as HF, BF3.H2O complex, aluminum chloride or aluminum choloride-hydrocarbon complex, chlorosulfonic acid, etc. Moreover, other acids than sulfuric acid can be ultilized in the'absorption step, such as phosphoric acid, the various halogen acids .including vIv-Ilil, andeven the Cialkylation step I4 strong organic acids, to produce the corresponding olenesters. Where a dierent acid or cata.- lyst isdemployed in the alkylation step than isused in the absorption step, it will be understood lthat the three-stage process is utilized to extract `stabilized aviation fraction of the alkylate is passed by line 39 to tank 40. The higher is passed by line 4I tank 42.

The C4, or C4 the aviation fuel blending boiling or heavy alkylate to the motor fuel 'blending plus light Cs fraction, of the synthesis products may be alkylated directly in the alkylation zone I4, and this operation is illustrated. However, where the said fraction contains too high a proportion of normal-butane, it can be subjected to two-stage or three-stage operation, as described above for the light n aphtha fraction, to absorb the olefins and separate themr from the diluting parailins prior to alkylation. 'As shown, this C4 alkylation step is carried out in conventional manner with isobutane introduced by line 45 and sulfuric acid catalyst added by line 46. Here again, various alkylation catalysts, such as hydroiluoric acid, IBF3.H2O complex, etc. can be employed in place of sulfuric acid, althoughv the latter is preferred. The conditions of this operation are essentially those described for the catalytic alkylation step 29. While the C4 fraction from line I3 can be supplied to the ester alkylation 29, it is preferred to conduct these alkylation steps separately with independent control, thereby enabling better quality alkylates to be produced. Fresh acid, such as 98-100% H2SO4 is introduced into the system by line 46 to provide makeup acid for the alkylation zone I4, and maintain thesystem acidity above about 88% and preferably about 90-93%. A portion of the acid separated from the hydrocarbon phase of the settler may be recycled by line 41, and the balanceis passed by line alytic alkylation step 29. In this manner, the acid requirements for the system may be minimibed and the most efficient utilization of the catalyst obtained. For optimum results a higher system acidity is employed for theA C4 alkylation than is required for the C5 and higher olefin alkylation. Consequently, acid discharged from atan acidity of about 88% or higher is quite satisfactory as makeup for the light-naphtha. olefin alkylation step 29, where the acid is further spent to a system acidity of about 85%.

The resulting hydrocarbon alkylation products, after conventional neutralization and washing, are passed by line 50 to stabilizer 5| where C4 and lighter are removed byline 52 to a butane fractionator 53. Here, isobutane and lighter is removed overhead by line 54 to a depropanizer 55, while normal butane is separated as bottoms o tion which is recycled by line 59 to line 45 to serve as the charge for alkylation step I4, and

48 to serve as makeup catalyst for the catstep 29 and ester extraction 28. In isomerization step 51, the normal butane feed is preferably contacted in liquid phase with a suitable isomerization catalyst, such as aluminum halide together with hydrogen halide. An

aluminum chloride-hydrocarbon com-plex liquid fortified by the addition of aluminum chloride so as to have a heat of hydrolysis of about B20-350 calories per gram constitutes an excellent catalyst for this purpose. The isomerization reaction may be carried out in conventional manner at a temperature of about i90-250 F. and preferably 210-230" F. and under suidcient pressure to maintain the norma-l butane in liquid phase, and in the presence of about 13% of HC1 based on the hydrocarbon charge. This operation is preferably conducted in a tower reactor in known manner, wherein the normal butane is dispersed in the form of small droplets into the base of the tower containing a deep body of the complex liquid catalyst, the droplets rising through the maintained catalyst layer and coalescing upon reaching the upper surface to form a snperpos drocarbon layer. During passage through the catalyst liquid, a. substantial conversion of normal ibutane to isobutane on the order of about t0-55% or somewhat higher is obtained. The hydrocarbon isomerization products, consisting essentially of isobutane and normal butane, are returned in major part by line 60' to the butane fractionator 53, where the isobutane is separated from unconverted normal butane in the manner, previously described. In this manner, high conversion of the normal butane content of the synthesis products to isobutane is ultimately obtained, whereby the produced isobutane supplies a substantial proportion of the charge to the catalytic valkylation operations I4 and 29.

The stabilized alkylate is removed as bottoms from stabilizer 5l and passed by line 6| to alkylate fraictionator 62, where separation is made of aviation alkylatc passed by line 63 -to blending tank 40, and heavy alkylate passed by line 6l to blending tank 42,

The paraffin railinat from absorption step l5 is passed by line 66 to treater 51. In the event that the light naphtha fraction of the synthesis products is substantially free from aromatics, the parailln 'ramna-te from line 65 is given av mild treat with strong sulfuric acid in treater 61 to remove any residual olefin content. The resulting acid-olefin extract is passed by line 58 to the absorption step t5 for recovery of the olefin content. It will be understood that a portion of the acid-olefin extract from line 25 can also head by line 1I for recycling to the treater 51.

Bottoms from still 10 consisting of the aromatic concentrate may be supplied by line 12 to blending tank 40 toserve as a constituent of the aviation fuel, or can be used for toluene recovery, paint solvent or other purpose as desireds `The solvent extraction may be operated to leavea residual aromatic content of about AOfi-1.0%, which functions as a cracking inhibitor in the subsequent isomerization step.

The paraffin railinate from treater 61, which is substantially free from olefins and aromatics. or contains the controlled amount of residual aromatics as specified above, is passed by line 14 to isomerization zone 15. Here the normally liquid paramns, or paramns plus naphthenes, are subjected to catalytic isomerization under mild cracking conditions to convert the said railinate into a gasoline isomate of paraflins o1' increased branched chain structure, and concomitantly produce a substantial yield of isobutane. This operation may be carried out in well-known manner by the use of an aluminum halide cataralnate of .the order of about 0.5:1 to 6:1 and be recycled to the absorption step I6, although once-through operation with 'short contact time of the order of about 1-10 minutes is preferred for absorption step l5.

When the synthesis products contain a substantial proportion of aromatics, and the light naphtha fraction` supplied by line l5 includes naphtha within the boiling range of the aromatics, then the absorption step I5 is carried out to selectively remove olefins and leave the aromatics in the parailln raffinate as described above. In such case, the parain railinate from line 66 is preferably treated with a selective solvent for aromatics, such as liquid sulfur dioxide. This removes not only the residual olen content but also the aromatics in the solvent extract from treater 51. This extract is passed by line 89 to stillV 10 where the solvent is removed overcatalyst for the isomerization step 15.

preferably about 1:1 to 3:1. The presence of the butanes inhibits severe or objectionable cracking and side reactions which result in rapid catalyst deterioration. In this isomerization step 15, a substantially saturated paraiiinic naphtha of increased branched chain structure and greatly improved antiknock value is produced in good yield. Also there is a net production of isobutane over and above that added in the feed, although there is little breakdown to C3 and lighter. It is preferred to carry out this isomerization step in a tower reactor of the character described above for the normal butane isomerization step 51, wherein the parailn rafilnate charge from line 14, together with the butanes from line 1G and the HCl from line 11, are dispersed into the lower portion of a main-- tained body of the fortified complex liquid of 'substantial height, the dispersed bubbles then thereof. To effect further economy in the cata lyst requirements of the system, the complex liquid discharged from isomerization step 51 is preferably supplied by line 18 to serve as the This liquid may be fortified, if required, by aluminum chloride added by line 19.

The resulting hydrocarbon isomerization products are passed by line to fractionating system 8l where a C'. and lighter fraction is removed by line A82. A substantial proportion of this fraction is recycled by line 83 to supply the major proportion of the butanes in the feed to the isomerization step. In order to prevent buildup of propane and any lighter in the system and also to recover the net production of isobutane resulting from isomerization step 15, a minor proportion ofthe C4 and lighter fraction y hydroforming in known from liei is supplied by-line 84 to the butane fractionator 53. Here, the isobutane and lighter fraction is separated by line 54 andlpassed to depropanizer 55 for eventual recovery of the isobutane rich fraction in line 59with elimination of propane and lighter from the system byline 58. In this manner substantial additional isobutane is recovered from the system to further supply the requirements of the alkylation steps I4 and 29. Also, normal butane of the C4 fraction from line 84 is recovered inthe butane fractionator 53 and'passed by line 56 tothe isomerization step 51 as previously described.

A minor proportion of the normal butanefrom 'line 56 can be diverted by line 85 to the feed line 86 to supply the butane makeup required for the isomerization step 15. If any additional butanes 'are needed, they can conveniently be obtained in most instances from natural gasoline and shipped by tank car to the plant, if distantly located from the source of such supply, and introduced by line 86. It will be understood that, while the butane makeupv for isomerization step 151s primarily normal butane, the gases recycled by line 83 will generally consist of about equal proportions of isobutane and normal butane, due to the reactions taking place in zone 15. Since the recycle gases lforming step I8. A

being returned together with hydrogen enrichment, if required, as the recycle gas to the hydro- C4 fraction is, removed from fractionator 9| by line 93 and may be passed to comprise by far the greater proportion of the butane feed to this step, the isomerization of the liquid paralnns takes place in the presence of a substantial excess of isobutane. Under these conditions, the resulting product from step 15 is substantially saturated. The liquid fractionator 8| is substantially all within the aviation boiling range, and is supplied by line 81 to blending tank 40.

In the special cases Where the synthesis products contain a substantial proportion of isoparaifms, and/or aromatics and naphthenes, the raiinate from absorption step I6 may have a CFRM octane of the order of 65 and above. In

isomate from1 such case, the raffinate may be blended directly,

in aviation or motor fuel, without being subjectedto isomerization. It will be understood that a branch line from line 66 may be provided for this purpose, leading directly to tank 40 or tank 42, or both.

The heavy naphtha fraction of the synthesis products from line |1 is preferably subjected to manner in zone I8. This is carried out by mixing the preheated naphtha with heated recycle gas having a hydrogen content of about 60-85 in the proportion of around 150G-2500 cubic feet of recycle gas per barrel of naphtha, and passing the resulting mixture at a temperature of about 900-1050 F., and preferably 9501000 F., and under a pressure of about 150- *250 pounds per square inch through catalyst beds of hydroforming catalyst, such as molybdenaalumina, at a space velocity of 0.2-0.7 volumes of feed per volume of catalyst per hour, and preferably` about 0.4-0.5. As is well-known, a catalyst bed may be kept on stream for about 10-16 hours, and the charge is then diverted to a regenerated catalyst bed, while the previously used catalyst bed is then regenerated by burning out 'carbon with ilue gas and air in well-known manner. Under the conditions set forth above, a yield of about 'T0-80% by weight, on the basis of the heavy naphtha debutanized gasoline line of greatly improved antiknock value, and which is nearly saturated, is obtained. Also, there is a substantial yield of around 6-8% by weight based on the. naphtha charge of C4 charged, of a broad boiling range hydrocarbons consisting largely of ization step 15,' ,andl the initial production of butanes in the synthesis products, are generally sufficient tosupply the isobutane requirements for the system. Moreover, the plant can readily be balanced by increasing or decreasing the end boiling point of the light naphtha fraction of line I5, to thereby regulate the amount of normally liquid voleiins supplied to the catalytic alkylation step 29 in accordance with the isobutane available.

An aviation hydroformate separated in the fractionating system 9| is passed by line 95 to blending tank 40. Heavier naphtha hydroformate is passed by line 96 to blending tank 42. It will be understood that the hydroformates can be treated to recover toluene or other aromatics,

if desired, and the residual naphtha then su y.;

plied to aviation or motor octane number thereof. It is thus seen that a grade aviation fuel is fuel depending on the substantial yield of high produced in this process by blending aviation fractions of the alkylates, the isomate and the hydroformate. It will be understood that any two or more of these various fractions can be blended in tank 40, the balance being supplied to motor fuel or other purposes as may bedesired. Also, it will be that isopentane, 2,3-dimethylbutane, ethylene alkylate consisting largely of 2,3-dimethylbutane, as well as /various aromatics, amines, or other blending constituents may be added to the aviation fuel in tank 40 in conventional manner, together with the required amount of antiknock additive of the character of tetraethyl lead. The resulting `aviation gasoline is passed from tank 40 by line 91 to suitable storage. Likewise, it is seen that an appreciable yield of high grade motor fuel blending stock is also obtained in tank 42 by the Iblending of two vor more of the heavier fractions, or the heavier and lighter fractions specified above. It will be understood that various cracked or straight `run naphthas can also be added in tank 42,- together with other usual constituents, to produce a balanced motor fuel which is discharged by line 98 to suitable storage.

While isobutane has been specliically described above as the isoparainn employed in the catalytic alkylation steps |4 and 29, and the ester extraction step 28it will be understood that other low-boiling isoparailns, such as isopentane, can =be used for this purpose. For exam-ple, the parafn raflinate from line 66 or line 14 can be fractionated to separate a normal pentane fraction, and the latterlseparately isomerizecl to produce isobutaneunderstood 1I isopentane'to form a part of the isoparailin charge to either or both of the catalytic alkylation steps. Also, while the aviation fractions from the various steps can be blended to form a composite aviation fuel in the manner shown, it will be understood that certain of the fractions can be separately utilized to produce various grades of aviation fuel, depending on the antiknock characteristics.

While xed bed hydroforming has been specically described for step I8, itwill be understood that any other type of operation can' be employed, 'such-as iluid catalyst operation. Also, any other suitable hydroforming catalyst may be used, such as chromic oxide-alumina. Moreover, while hydroforming constitutes the preferred treatment for the heavy naphtha fraction, any other suitable type of catalytic conversion may be employed which results in some breakdown or cracking to produce a C4 yield and also lower the boiling distribution range and increase the antilmock value of the naphtha. Thus, catalytic cyclization or catalytic reforming may be used, both steps being conducted in conventional manner. For example, catalytic cyclization may be carried out by passing the' heavy naphtha in vapor form through catalyst beds of chromic oxide-alumina at temperatures of about 900- 1100 F. and under relatively low pressures of several atmospheres, thereby producing a naphtha of substantially increased aromatic content and which is more unsaturated, with the concomi-tant production of a substantial yield of C4 and lighter. Catalytic reforming may be conducted with a silica-alumina catalyst, either with or without fixed gas or Ci-Cz hydrocarbon recycle, at temperatures of the order of 900-1100 F. and at pressures from slightly above atmospheric up to about 250 POunds per square inch, therebyresulting in considerable cracking and production of C4 and lighter, and the formation of a more highly unsaturated naphtha of broad boiling range. In all of these processes the heavy naphtha is substantially reduced in boiling range distribution and concomitantly upgraded in antiknock value, while at the same time there is a net production of C4 hydrocarbons which augment the charge to the C4 alkylation step and increase the production of this high grade alkylate.

The following speciiic example is listed by Way of illustration. A mixture of one part'by volume of carbon monoxide and two parts by volume of hydrogen, heated to a temperature of about 370 F., was passedcontinuously through a contact mass of catalyst having a composition of approximately 32% cobalt, 64% lter cel and 4% thorium and magnesium oxides. The catalyst mass was .maintained within a temperature range of 374 to 385 F., and a feed gas space velocity of about 100 was employed. An average yield of liquid condensate from C4 to about 750 F. end point of about 0.85 gallon per 1,000 cubic feet of feed gas was obtained. Separation of the condensate into fractions provides about 8% by volume of C4 hydrocarbons, about 25% by volume of alight CCz naphtha fraction having a clear CFRM octane of about 25, about 35% by volume of a C400 F. end point heavy naphtha fraction having a clear CFRM octane of about 35, and

about 20% by volume of a Diesel fuel having a. cetane value of around 90 with the balance being essentially paraflln wax.

The light naphtha fraction is contacted at 25 F. with ten volumes of 90% H2804 (having a water content'of about 2%, the balance being mainly organic matter) per volume of naphtha with a contact time of about Ktwo minutes, with about 97%- removal of the oleflns. The acidolen extract is alkylated with isobutane in a -molar ratio of 5:1 on the equivalent olen content, at a temperature of 50 F., utilizing an acid to hydrocarbon ratio in the reactor of 1:1 and a contact time of twenty minutes. An aviation alkylate of 350 F. end point having a clear CFRM octane of about 84 is produced in a yield equivalent to about by volume on the basis of the light naphtha charged to the absorption step, or about 190% by Weight of the equivalent olen content converted to C4.

The remaining paramn rafllnate is given a mild acid treatment With 98% H2SO4 at 60 F. in a -proportion of l0 pounds of acid .per barrel, providing a parain rainate of substantially zero bromine number. This is subjected to isomerization in the presence of a fortified aluminumchloride-kerosene complex liquid having a heat of hydrolysis of 340 calories per gram, and with 2% HC1 on the weight of the paramn railinate, together with one volume of mixed butanes per Ivolume of rainate, at a temperature of 235 F. A net production of 9% by weight of is'obutane on the Weight of the ratlinate charge is obtained, together with a yield of about 88% of a 11G-297 gasoline isomate having a clear CFRM of about 73.

The heavy naphtha fraction of about 198-397" F. end point was subjected to hydroforming with a molybdena-a'luxnina catalyst, employing a recycle gas containing about 70% hydrogen content at a recycle gas rate of around 2,300 cubic feet per barrel of naphtha feed, at a temperature of about 975 F. and a pressure of around 200 pounds per square inch, utilizing a space velocity ofabout 0.5. A yield of about 78% by weight based on the naphtha charged of debutanized aviation hydroformate having an end boiling point of 364 F. and a clear CFRM octane of about 74 was obtained, said hydroformate naphtha being nearly saturated with a bromine number of 8. In addition, 8% by weight of C4 hydrocarbons, consisting mainly of normal butane and isobutane, Was produced.

In the alkylation of the C4 fraction of the synthesis products with isobutane, charging 99% H2504 to maintain a titratable acidity within the system of E30-93%, employing a 5:1 molar ratio of isobutane to butylenes, at a temperature of 40 F. With a 1:1 volume ratio of acid to hydrocarbons in the reaction zone, a yield of about 190% by weight based on the oleilns charged of aviation alkylate of 350 F. end point is obtained, said alkylate having a clear CFRM octane of about 92.

A blend of the aviation alkylates, isomate and hydroformate in the ratio of production provides Va composite aviation gasoline having a clear CFRM of about 80. The gasoline has good lead susceptibility, such that about 4.5 cc. of tetraethyl lead per gallon produces 100 octane aviation gasoline. y

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process for the manufacture of high antiknock gasoline from carbon oxides and hydrogen,

13 which comprises reacting a carbon oxide and hydrogen in the presence of a synthesis catalyst under conditions effective to produce normally gaseous and normally liquid paraiiln and olefin hydrocarbons containing a substantial proportion of normally liquid hydrocarbons within the gasoline boiling range, separating from the resulting synthesis products a light naphtha fraction containing normally liquid olefin and parain hydrocarbons vfrom C5 up to and including at least C1 but below Cs and also a heavy naphtha fraction above C7, extracting oleflns from said light naphtha fraction by contacting the same lwith an acid alkylation catalyst under conditions to absorb the oleiins, separating the acid-olefin ex-' tract from the remaining unabsorbed paraiiin hydrocarbons,'alkylating a low-boiling isoparamn with said absorbed normally liquid olefins in the presence of an alkylation catalyst under conditions to produce alkylate within the gasoline boiling range, subjecting said heavy naphtha fraction to catalytic conversionunder conditions including an elevated temperature of about 900-1100" F. effective to lower the boiling points f a substantial proportion thereof and produce a broad boiling range gasoline of substantially improved antiknock value, and combining a gasoline fraction from said conversion step with said gasoline alkylate.

2. A process for the manufacture of high antiknock gasoline from` carbon monoxide and hydrogen which comprises reacting the carbon monoxide and hydrogen in the presence of a synthesis catalyst under conditions effective to produce normally gaseous and normally liquid parain and olen hydrocarbons containing a substantial proportion of C4 and C12 hydrocarbons, separating from the resulting synthesis products a fraction consisting essentially of C4 hydrocarbons containing a substantial proportion of butylenes with not more than the lighter portion of the C5 hydrocarbons, and also a fraction containing remaining Cs through at least C1 hydrocarbons but boiling below C9 hydrocarbons having a substantial proportion of normally liquid olens, catalytically alkylating isobutane with sion products as a butylenes of said C4 containing fraction to produce normally liquid gasoline 'alkylate,vsubjecting said Cs and heavier fraction to contact with an acid alkylation catalyst to absorb the normally liquid olefins therefrom, separating the resulting acid-olen extract from remaining unabsorbed paraffin hydrocarbons, catalytically alkylating isobutane with absorbed normally liquid oleiins of said extract to produce additional gasoline alkylate, combining said alkylates, also separating from said synthesis productsv a heavy naphtha fraction above C7, subjecting said heavy naphtha fraction to catalytic conversion under conditions including an elevated temperature of about 900-1100 F. e'iective to lower the boiling points of a substantial proportion thereof and produce a broad boiling range gasoline of substantially improved anti-knock value, as Well as additional C4 olefin containing hydrocarbons, separating said C4 olefin containing hydrocarbons and supplying them to said C4 catalytic alkylation step, combining a gasoline fraction from said heavy naphtha conversion vstep with` said gasoline alkylates, and supplying catalyst discharged from said C4 alkylation step to furnish makeup catalyst for said extract alkylation step.

3. A unitary process for the manufacture of high antiknock gasoline from carbon monoxide and hydrogen, which comprises reacting carbon about o-1100 monoxide and hydrogen in the presence of a synthesis catalyst under conditions eilective to produce normally gaseous and liquid paramn and olefin hydrocarbons including a substantial proportion of butanes and butylenes and also normally liquid paraflin and olefin hydrocarbons within thegasoline boiling range, recovering normal butane from said synthesis products, subjecting at least a part of said recovered normal butane to catalytic isomerization to produce isobutane, recovering an isobutane-rich fraction from said isomerization products, also separating from said synthesis products a light naphtha fraction containing normally liquid paraln and olen hydrocarbons, absorbing normally liquid olens from said light naphtha fraction by contact with an acid alkylation catalyst, separating the resulting acid-olefin extractl from the unabsorbed paraffin rafnate, utilizing at least a portion of said isobutane-rich fraction for alkylating said absorbed olefins in the presence of an alkylation catalyst to produce gasoline alkylate, subjecting said parailin raffinate to catalytic isomerization in the presence of added butane, utilizing another part of said recovered normal butane as the butane charged to said last-mentioned isomerization step, and blending resulting gasoline isomate from said last-mentioned isomerization step with said gasoline alkylate,

4. The method according to claim 3, wherein a heavy naphtha fraction is also separated from said synthesis products, said heavy naphtha fraction is subjected to catalytic conversion under conditions including an elevated temperature of F., effective to lower the boiling points of a substantial proportion 'thereof and produce a broad boiling range gasoline of improved antiknock value and also additional C4 hydrocarbons including a substantial proportion of normal butane 'and isobutane, utilizing normal butane from said conversion products as a portion of the charge to said normal butane isomerization step, utilizing isobutane from said converportion of the charge to said catalytic alkylation step, and blending a gasoline fraction from said conversion step with said gasoline isomate and said gasoline alkylate.

5. A process for the manufacture of high antiknock gasoline from carbon oxides and hydrogen, which comprises reacting a carbon oxide and hydrogen in the presence of a synthesis catalyst under conditions eiective to produce normally gaseous and normally liquid paraffin and olefin hydrocarbons containing a substantial proportion of normally liquid hydrocarbons within the gasoline boiling range, separating from the resulting synthesis products the following three fractions, namely, (1) a normally gaseous fraction containing butylenes and butanes, (2) a light naphtha; fraction containing normally liquid olefin and parain hydrocarbons including at least C5 and Cs but below C9, and (3) a heavy naphtha fraction above C1, alkylating oleflns including the butylenes of fraction (1) above with a low-boiling isoparafn in the presence loi an alkylation catalyst to produce gasoline alkylate, subjecting fraction (2) above to absorption with a mineral acid to produce an acid extract of absorbed normally liquid oleflns, separating the acid extract from the resulting unabsorbed paraln raffinate, alkylating the absorbed oleflns ofthe said extract with a low-boiling isoparaiiin in the presence of an alkylation catalyst to produce additional gasoline alkylate, subjecting the said parafiin rail'inate to catalytic isomerization to convert the normally liquid parailin hydrocarbons to a gasoline isomate of parafflns of increased branched chain structure,

`subjecting said heavy naphtha fraction to catalytic conversion under conditions including an elevated temperature of the order of 900- 1100 F. effective to reduce the boiling points of a substantial proportion thereof and produce a broad boiling range gasoline of substantially improved antiknock value, and combining a gasoline fraction from said conversion step with said gasoline isomate and said gasoline alkylates.

6. The method according to claim 5, wherein said catalytic conversion step also produces a substantial yield of butanes and butylenes which are combined with said fraction (l) normal butane is recovered from the alkylation products resulting from the alkylation of said fraction (1), at least a portion of said normal butane is subjected to catalytic isomerization to produce isobutane, and resulting isobutane is utilized as at least a portion of the low-boiling isoparailin charge to both vof said alkylation steps.

7. The method according to claim 5, wherein said catalytic conversion step also produces a substantial yield of butylenes and butanes, the lastmentioned butylenes are combined with the butylenes from said fraction (1) and the combined butylenes subjected to said catalytic alkylation, normal butane is recovered from both said products of conversion of fraction (3) and from said fraction (1), a portion of said normal butane is supplied to said parain raiiinate isomerization step, another portion of said normal butane is 16 ence of an aikylation catalyst under conditions effective to alkylate isobutane with said butylenes to produce gasoline alkylate, separating from the resulting alkylation products a gasoline alkylate fraction and also a f-raction consisting essentially of normal butane, subjecting said normal butane fraction to catalytic isomerization to convert a substantial proportion thereof to` isobutane,

subjected to catalytic isomerization to produce isobutane, and resulting isobutane is utilized as the low-boiling isoparain charge to both of said alkylation steps.

8. A unitary process for the manufacture of high anti-knock gasoline from carbon monoxide and hydrogen, which comprises reacting carbon monoxide and hydrogen in the presence of a synthesis catalyst under conditions effective to produce normally gaseous and liquid paraln and olefin hydrocarbons including a substantial proportion of C4 hydrocarbons containing normal butane and butylenes, and also normally liquid hydrocarbons within the gasoline boiling range, separating from said synthesis products a C4 fraction containing butylenes and normal butane, and also a light naphtha fraction containing normally liquid parain and oleiln hydrocarbons from C5 up to and including Cv, but below C, agitating isobutane obtained from a source hereinafter defined with said C4 fraction in the presseparating an isobutane-rich fraction from the resulting isomerization products, supplying a portion of isobutane-rich fraction to said C4 alkylation step to serve as the isobutane charge thereto, absorbing normally liquid olens from said light naphtha fraction by contact with an acid alkylation catalyst, separating the resulting acid-olefin extract from the unabsorbed hydrocarbon paraiiin rafiinate, mixing another portion of said isobutane-rich fraction with absorbed olefins recovered from said light napht'ha fraction and agitating the mixture in the presence of an alkylation catalyst under conditions to alkylate isobutane with said absorbed olens to produce additional gasoline alkylate, combining said gasoline alkylates, subjecting said parain railinate to catalytic isomerization to form gasoline isomate of parains of increased branched chain structure 'with` the concomitant production of isobutane, separating from the isomerization products the gasoline isomate and also the produced isobutane, utilizing said produced4 isobutane as a portion of the isobutane charge to the alkylation steps, passing catalyst discharged from said normal butane isomerization step to said paraffin raillnate isomerization step, and blending said gasoline isomate with said gasoline alkylates.

ARTHUR R.. GOLDSBY.

REFERENCES CITED The following references are o f record in the le of this patent:

UNITED STATES PATENTS Nurnber Name Date Re. 22,205 Goldsby Oct. 20, 1942 2,286,314 Kemp June 16, 1942 2,293,705 Bloch Aug. 25, 1942 2,303,735 Goldsby Dec. 1, 1942 2,311,498 Voorhies, Jr. Feb. 16, 1943 2,361,611 DOuville et al Oct. 31, 1944 2,371,355 Ross et al Mar. 13, 1945 2,371,408 Parker" Mar. 13, 1945 2,376,077 Oberfelle et al May l5, 1945 2,381,041 De Jong Aug. 7, 1945 2,403,869 Marschner July 9, 1946

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