US2396853A - Manufacture of motor fuel - Google Patents

Description

March lg, 46. 1 P JONES MANUFACTURE OF MOTOR FUEL Filed Dc'. 5, 1941 recessed niet. te, ieee A dt af, il'i il 'if @F MTQR i .lean P. llaines, Bartlesville, 0.,

Phillips Petrole Company, a co Delaware Application December 5, 19411, Serial No. 21,822

2 C i (Cl. 26o-683.4)

This invention relates to the production of parcarbons khigher boilingpara :t hydrocarbons of ain hydrocarbons in the motor fuel boiling range high octane number. and of high octane number. It relates more parc Otherobiects and advantages of my invention ticularly to the production of such paraffin hydrowill become apparent to those skilled in the art carbons by the alkylation of lower boiling parfrom the accompanying description and disaiiins, especially of low-boiling normal paramns, closure.

and theisomerization of hydrocarbon fractions of My invention 'will' now be more completely delow octane number so produced to produce parscribed in connection. with the drawing whichl ains of higher octane number. forms a -part of this application and which shows The alkylation of isoparaiiins such as isobutane diagrammatically by means of a ow diagram an and isopentane with low-boiling olens produces arrangement of apparatus in which my invention parain hydrocarbons in the motor fuel boiling `Will-he practiced together with various modicarange, which have high octane numbers and which tions thereof, said description also serving to exare suitable for use in premium motor fuels. Both emplify my invention. catalytic and noncatalytic processes have been l5 Referring now to the drawing, low-boiling parproposed to carry out such alkylatioris and are weil amns such as a fractioncontaining a substantial known to the art.v It has also been proposed to vduantity Voi normal butane is introduced through alkylate straight-chain paraiiinssuch as propane, pipe l@ controlled by valve it' to the alkylation normal butane, normal pentane', and certain parunit I2. The alkylaton in unit l2 may be either ain hydrocarbon fractions of low octane number thermal or catalytic as previously stated and parin the low part of the gasoline boiling range. The amns may be alkylated with olens or other alkyl.. alkylation of` such hydrocarbons can be carried atingy reactants such as alcohols or alkyl halides out in the absence of a catalyst at elevated preswhich may be introduced to the system through sures and moderately elevated temperatures, and pipe it controlled by a valve ifi. may also be carried out in the presence of certain A When the alkylti rain iS promoted Calacatalysts under more moderate conditions. The lytically, the choice of a suitable catalyst depends catalysts which have been .proposed for such y somewhat'upon the alkylation reactants. For exalkylations include alkylation catalysts oi the ample, when isoparaihn hydrocarbons are ai- 'metal halide type such as aluminum chloride or kylated with olefin hydrocarbons, especially gasealuminum bromide or combinations of these metal ous olefins, materials such as aluminum and zinc halides with other metal halides such as sodium chlorides and bromides, an eduimolar mixture of chloride and the like, and also concentrated hysodium and aluminum Chloride (Sodium 6111010- drofluoric acid. In the alkylation of such paraluminate), boron fluoride, zirconium'chloride, amn hydrocarbons a substantial portion ofthe and the like, concentrated sulfuric acid, and conproduct is of a relatively -low octane number. centrated hydrouoric acid maybe used as suit- However, such processes serve to convert large` able alkylation catalysts. Of these catalysts, conamounts of hydrocarbon materials which are too centrated sulfuric acid or hydrouoric acid is prevolatile for direct inclusion in motor fuels into ierred, when the concentration of isoparafn hyhydrocarbons which boil in the motor fuel range drocarbons is relatively high, as they appear to and, therefore, iind a limited use. 40 promote the union of alkylating olei-lns with iso- I have now found that low-boiling straightparans more selectivelythan other known a1- chain parain hydrocarbons can be converted to @lation catalysts, to produce highly desirable hydrocarbons of high octane vnumber and in the products, while when there is little li any concenmotor fuel boiling range by a combination of an tration of isoparailins and normal paramns are alkylation step with a step for isomerizing certain @5 to be reacted predominantly, aluminum chloride fractions separated from the effluent of the alkyla-f or bromide, sodium chloroaluminate, and other tion to produce a composite motor fuel containing similar catalysts are to be preferred, although hydrocarbons directly eiuent from the alkylation hydrouoric acid may also be used at higher` teme step blended with hydrocarbons which in addiperatures. tion t0 being formed by alkylation have been 50 When alchols comprise the reactant for a1- isomerized. kylating parafllns in the presence of sulfuric acid An object of my invention is to produce hydroor hydroiluoricacid, Water is formed as a byca'rbons in the motor fuel boiling range. product. Various reactions may occur in alkylator A further object of my invention is to produce l2 when alcohols are the alkylatins reactant. but from low-boiling straight-chain paraiiin hydrothe primary reaction is believed to be alkylation of paramns, especially parafiins having a tertiary carbon atom, which are more easily alkylated than other paraiiins. The primary alkylation product appears to'undergo secondary reactions which form lower boiling and higher boiling products;

itprobablyv also undergoes isomerization. Prod v ucts especially useful as motor fuels are obtained if the initial paraffin is an isoparafiin having four or flve carbon atoms'per molecule and if the alcohol has three .to ve carbon atoms'per molecule. However, the invention is not .tovbe necessarily limited to para-fllns and alcohols having these numbers of carbon atoms per molecule, for reactants with larger numbers may be used.

When alkyl halides are used to alkylate parain fkhydrocarbons it has been found that primary.

halides, especially ethyl halides, react relatively diicultly and require a catalyst more powerful than that which is adequate for nonprimary alkyl halides. Thus. when a primary 'alkyl halide. such as ethyl chloride, is used. catalysts of the aluminumY chloride type are more advantageous than catalysts of the sulfuricacid type." Alkylationof 'i paraffin-hydrocarbons and especially isoparanln hydrocarbonswith alkyl halides takes place with an elision of a hydrogen halide, When sulfuric acid or hydouoric acid is used. as the catalyst, the alkylation reaction appears to proceed most eiiiciently for isoparaiilns having four to eight carbon atoms per molecule and fornonprimary alkyl halides in`which the alkyl group has three to six carbon atoms per molecule( Of nonprimary alkyl halides, the tertiary react somewhat more.

rapidly than do the corresponding secondary al- .kyl halides, and the use of an alkyl halide with a catalyst. such as sulfuric `acid appears to give improved catalyst life as compared with theuse of the corresponding olefin.

Ordinarily a process for the reactionlof al-U kylatable paraffin hydrocarbons with an alkylating reactant in the presence of an alkylation cat- .alyst, such as sulfuric acid or hydroiiuoric acid,

is preferably operated under only moderate superatmospheric pressures, such as between about 20 and 200 pounds per square inch gauge. Since the alkylation reaction represents` a decrease in the total numberl of molecules, a certain amount of pressure favorsthe reaction. However, since the reactants are generally readily maintained in liquid phase with only moderate pressure at the reaction temperature. in the lower part of the` range indicated, only sufficient pressure toinsure l liquid phase operation is generally adequate.

When higher reaction temperatures are used, higher pressures may also be used. and pressures as high as 1500 or .2000 pounds per square inch or more may be used if desired. In most instances a catalytic alkylation process will be operated under a pressure between about and 500v pounds per-square inch gauge.

When sulfuric acid is the catalyst employed for the reaction of alkylatable paraffin hydrocarbons with an alkylating reactant as discussed, the

concentration preferably should be maintained within the range of about 90 to 102 per cent. ad-

vantageously above vabout 96 per cent. because the higher strengths of acid promote the reaction of the more diflicultly alkylating reactants as well as the difiicultly alkylatable parailins. Strengths vroutside of the range given downto about 80 per cent and up to about 105 per cent may be employed; however, when an olen is thel alkylating reactantstrengths of sulfuric' acid so low as to promote excessive olefin polymerization and so high as to cause excessive consumption ofthe acid, as in oxidation of organic materiahshould be avoided. Sulfuric acidcatalyst may be used at temperatures in the range .nuoric acid or hydrogen iiuoride, is very effecof 0 to 125 F., preferably at about 30 to 70 F. The volurne ratio of hydrocarbon to sulfuric acid may bebetween about 1:3vand 5:1 and it is important that the reactants and acid be intimately admixed and emulsified. Generally, with extremely thorough intermixing, this ratio may be in the upper part of the range. It has been found' that a continuous intermixing of the reactants can vbe readily` accomplishedby lpassing them through acentrifugal pumpand then through an elongated tube of a cross sectionl sufhciently retive. As discussed. the process is generally carried out with the hydrocarbon material substantially in liquid phase; efficient reaction results when suiiicient hydrouorlo acidis employed to result in a substantial saturation of the liquid hydrocarbon material with hydrogen fluoride and preferably sufficient hydrofiuoric acid is used to form a separate liquid phase which may be maintained and emulsied or intimately mixed with' the hydrocarbon while reaction takes place'. In most cases the hydrofiuoric acid charge should be at least l0 per cent of the total charge, on a liquid volume basis, and hardly ever need exceed-50 to. 60 per cent, though more can, at'times. be used. The reaction' temperature when hydrofluoric acid is the alkylation catalyst may be varied over a wide range for any particular reaction mixtureqbut appears to be most dependent `upon'the paraffin hydrocarbon participating in the reaction. Thus, in general, I may carry out an alkylation process at temperatures between about 0 and 300 or 400 F.. For readily reacted paraffin hydrocarbons, such as isobutane or isopentane, I may readily effect an alkylatioh at a temperature between about 35 and 100 F. while for less reactive paraiins, such as normal butane and normal pentane, higher temperatures are necessary or more desirable. The use of hydro- -fluoric acidhas a distinct advantage in such cases, in that it can be used underthese more extreme conditions without promoting or enteringinto extensive undesirable side reactions as is likely to occur when concentrated sulfuric acid is the alkylation catalyst.

The moleratio of alkylatable paraffin to al@ kylating reactant when either sulfuric acid or hydrofluoric acid is the alkylation catalyst should be at least 1:1 and is preferably higher. The mostl desirable results are obtained when the mole ratio of alkylatable paraffin to alkylating reactant at the immediate zone of addition of the alkylating reactant is not less than about 9:1. However, when particularly pure hydrocarbons or a motor fuel stock of particularly high octane number, are desired the mole ratio of alkylatable paramn to alkylating reactant mayneedto be as high as 50:1 or 100:1 or even greater for any particular point at which alkylating reactant tions will be found when the mole ratio of alkylatable parain to alkylating reactant is between 12:1 and 100:1. Accordingly, multipoint addition of the alkylating reactant to the reaction zone is advantageous, as in Frey 2,002,394, without intermediate fractionation or the like. as is known to the art.

When the reaction in unit l2 is conducted in the substantial absence of a catalytic material which is active for the -promotion of an alkylation reaction, my process will be operated so that in-unit l2 a, high pressure thermal conversion of hydrocarbons is effected. My process broadly includes any such process operating under a pressure in excess of 5 00 pounds per square inch, and preferably in excess of 1000 pounds per square inch. Such pressures may run as high as 10,000 to 15,000 pounds per square inch or more depending somewhat on the strength of the apparatus, although generally pressures up to 5000 pounds per square inch will be sufcient. In general, the temperatures will be between 750 and l200 F., preferably 900 to 1000 F., and catalysts will not be used except as the materials of the apparatus used may have an inherent fortuitous catalytic activity. The charge stock to such a thermal conversion step should contain only little, if any, methane,-

and while some pentanes or pentenes may be included in normally gaseous mixtures, large amounts of such material will 'generally not be treated in this particular manner. The charge stock may be entirely paramnic, or may contain unsaturated hydrocarbons, especially oleilns, and in some cases may comprise two separate hydrocarbon streams, one parailnic and one unsaturated, as illustrated in the drawing. In those cases where only a parafilnic hydrocarbon mixture is available and it is'desired to have some unsaturated hydrocarbons present in the charge stock the dehydrogenation step as illustrated by unit 26 may be included in the process. Such a dehydrogenation step may be entirely thermal, or it may be catalytic, or it may involve a 'combination of thermal and catalytic stepsl under known conditions.

The alkylation effluent passes through pipe i5 controlled by a valve I6 to'separating means Il which will comprise various fractionating columns, selective solvent extraction units, and associated equipment as may be found convenient in any particular instance to effect the separation of various fractions to be hereinafter discussed. ,In most instances the desired separations can be conveniently carried out by a series of fractional distillation operations which will separate the alkylation product into a number of fractions, each of a relatively narrow boiling range. Undesired low-boiling lmaterial will be discharged from lthe system through a pipe 20 controlled by valve 2i. Low-boiling paraln hydrocarbons suitable for recycle to the system may be removed from the system by a pipe 22 controlled by a valve 23 and can be recycled to the system by being passed to pipe l0 by means not shown. If desired a portion of this material, or a particular fraction of low-boiling paramn hydro-- carbons, may be passed from pipe 22 through a pipe 26 controlled by a valve 25 to the dehydrogenation unit 26 wherein dehydrogenation takes place to produce oleiins suitable for use as alkylating reactants in the alkylation step. Low-boilingv parafns to be dehydrogenated may be introduced to the system through a pipe 2l controlled-by a valve 28 leading into pipe 2d. VDehydrogenation of high octane number from a mixture containing hydrocarbons having the same number of carbon atoms per molecule but having a lower octane number, simple fractional distillation means will not always accomplish the desired results in an' eflicient manner. In such instances an entraining agent canbe empoyed in the separating means Il and so selected that it will form a, constant boiling mixture or azeotrope-with at least one component of the hydrocarbon mixture and when it is capable of forming an azeotrope with more vthan one component it preferably does so only with those components having either a high or low octane number. By employing fractional distillation of such a-hydrocarbon mixture in the presence o f such an entraining agent, hydrocarbons of high octane number can ultimately be readily separated from hydrocarbons having the same number of carbon atoms per molecule but having a lower octane' number. Entraining agents which are capable of promoting such separations comprise alcohols, esters, and organic acids having an appreciable vapor pressure in the boiling range of the hydrocarbons to be separated. Specic examples of these agents include methyl alcohol, ethyl alcohol, furfural, glycol acetate, methyl formate, methyl acetate, ethyl acetate, and levulinic acid. Similar compounds will also produce similar results and'those specified are only to be considered illustrative. Such entraining agents are especially useful when it is desirable to separate cyclic hydrocarbons from chain hydrocarbons-when both types have similar boiling points or boiling ranges but are not limited to use with only such types.

One or more hydrocarbon fractions of high octane number are isolated in separating means Il, in a suitable manner, such as discussed, and may be recovered as through pipes 40, 4l, and 42 controlled by valves 03, 44 and t5, respectively. Any of these fractions may be recovered as an individual fraction as shown or may be blended together to form a composite motor fuel stock of high octane number. When this is desirable, the fraction passing through pipe 40 may be removed therefrom through a pipe 46 controlled by a valve 59, and to it may be added a fraction fromv pipe 4I passing through pipe 49 controlled by a valve 48 and/or a fraction passing y through pipe d2 which may be removed therefrom through a pipe 50 controlled by a valve 5I, each of pipes 49 and 50 passing to pipe il.

In a similar manner one or more fractions of low octane number may be recovered in separating means I1, in a suitable manner such as discussed, and passed to the isomerization step. Thus, a fraction may be removed through a pipe 52 controlled by a Valve 53, and may bepassed directly to an isomerization unit ll for an isomerization treatment to be described. However, it is generally desirable to ensure that the hydrocarbon material passed to the is'omerization unit Jl is essentially free of reactive material, which bons, and I prefer to pass the fractions of low octane number through a treatment to remove such nonparainic reactive material. This is conveniently done by means of a nondestructive hydrogenation. When such a treatmentis to be included as a step in my process, the -material passing through pipe 52 ispassedtherefrom through a pipe controlled by a valve 55 to a nondestructive hydrcgenation unit 56. Hydrogen is used in such a unit and may be introduced into the system by a pipe 51 controlled by a valveI te. When thehydrogenation unit 58 is a part of my process, hydrogen recovered through pipe 33 may be introduced through pipe 51 for Y use in this step of the process. One or more fractionsof low octane number recovered in separating means l1 may be removed therefrom through one or more pipes represented by pipes tu and Si controlled by valves S2 and 63, respectively, and introduced into pipe 54. When any of these fractions may be introduced directly intol .the isomerizaiton step without treatment to revtraction, polymerization or the like, as may be best suited in any particular case. The concentration of such reactive material will generally not be very high, and when nondestructive hy-l drogenation is used, this may be carried out under a. slight superatmospheric pressure in the presence of any non'destructive hydrogenation catalyst such as active nickel supported on an inert support. The effluent of the hydrogenation is passed through a pipe controlled by a valve ous material is removed through apipe 13 controlled by a valve 14, and an essentially parainic material is recovered through a pipe 15 and Y passed to an isomerization unit 11 through valve I* The material entering isomerization unit 11 through pipe 15 may be joined by any material which is passed directly to the Visomerization unit through 52. Such material may be supplemented by a paraiiinie fraction of low octane number in the motor fuel boiling range from any suitable source not shown and passed to the system through a pipe 18 controlled by a valve 19 leading to pipes 52 and 15. Any undesired portion of the material passing from separating means 12 through pipe 15 may be removed from the system through pipe 80 controlled by a valve 8i.

-When any material of low octane numbenwhioh is to be charged to the isomerization stepV from an outside source,lcontains small amounts of .nonparailnic reactive material, such as unsatuated under continuous conditions and either in liquid, mixed, or vapor-phase as may be desirable or expedient in view of the particular hydrocarbon or hydrocarbon mixture. undergoing treatment and dependent on the particular isomerization catalyst employed. The isomerization in unit 11 can-be carried out on any of the normal paraiiin hydrocarbons having four or more car- -bon atoms per molecule and preferably those which boil at a temperature not greater than about 320 F. Suitable paramn hydrocarbons are normal butane. normal pentane, normal hexane, normal heptane, and particularly those hydrocarbons in the motor fuel boiling range and having a low octane number. In someinstances naphthas may be treated in the lisomerizatioiu zone and especially virgin naphthas containing large amounts oi' normal paramn hydrocarbons. Such naphthas will be passed to the Aisomeriza tion unit 11 by means of conduit 18 controlled by valve 19.

Isomerization unit 11 can be operated to isomerize a substantially pure normal paramn hydrocarbon or a mixture comprising a plurality of such hydrocarbons. In some instances it will be desirable for unit 11 to comprise several separate isomrization elements, the charge stock t0 each element comprising a Asubstantially pure isomerizable paraiiinl hydrocarbon and each element operated under such conditions as to promote the isomerization of said isomerizable paraiiin hydrocarbon to an optimum degree. The isomerization in unit 11 is preferably carried out in the presence of an isomerization catalyst of the aluminum halide type although the halides of arsenic, tungsten, molybdenum, zinc, iron, cadmium, beryllium, antimony, tin, zirconium, or. boron. either alone or in admixture, may rind application in some instances. In general, however, I

4 have found that the aluminum halide type of rated hydrocarbons or sulfur compounds, and

pure material is purified by hydrogenation it may be charged directly to the hydrogenation unit 5B, as by being passed through pipe 51 along with l the free hydrogen.

The isomerization'unit 11 is preferably operl catalyst is most desirable in my process. How- 1l to a separating means 12. Low-boiling gaseever, in the broadest aspects of the case I am not specifically limited to operate solely in the presence of such a catalyst.

Practically suitable catalysts are .aluminum chloride and aluminum bromide and I will describe the operation of my process when operl atingin the presence of such a catalyst; The aluminum halide may beused by itself or in association with other catalytic or promoting agents. such as ferrie chloride or bromide, halo` in somewhat greater quantity, for example from two to live per cent by weight. Also one ormore such suitable aluminum halide catalysts may be-l mixed with or deposited on filler or supporting materials such as activated charcoal, silica ygel, or bauxite, or other materials such as pumice. kaolinites, vmeerschaum. kieserite. or the like.

When operation in the liquid phase is desired. the hydrocarbon'material to be treated and the aluminum halide catalyst may be charged to a suitable reaction vessel in isomerizationunit 11 in the desired relative .amounts and the mixture maintained atthe desired temperature for a time .necessary to eilect the desired extent of isomerization. The relative proportions of the' catalyst andthe hydrocarbon material to be treated may vary over a comparatively wide rangeyand will, in general, depend upon the particular catalyst used. upon the particular hydrocarbon material to be treated, and upon the speclc temperature and contact time employed. An aluminum halide catalyst may be advantageously employed in an amount equal to from about one per cent to about fteen per cent by weight of the hydrocarbon material treated at any one time. At low temperatures and long contact times, as discussed herein, the amount of aluminum halide present in the isomerization zone 'may vary between about per cent and 150 per cent, or even greater, by weight of the totalI hydrocarbon in the isomerization chamber at any one time. In such instances the preferred aluminum halide concentration is generally between about 100 per cent and about 150 per cent by weight. In general, however, the

hydrocarbon to be treated is present in relatively great excess over the catalyst. When desirable, a gaseous' hydrocarbon or hydrocarbon mixture may be contacted with the catalyst.- This may be done in a variety of suitable manners.

For example, when the catalyst is in the form of When using an aluminum halide-type catalyst, or similar catalyst, there should also be present a substantial amount of a hydrogen halide, preferably one corresponding tothe aluminum halide beingused. Such a. hydrogen halide, or mixture of hydrogen halides, may be added to the reaction vmixture in the desired amount in any convenient manner.

The reactions in isomerization unit 11 are generally carried out under a pressure suiciently high to ensure the presence of a liquid phase in the unit and in the presence of such an amount of a hydrogen halide that the partial pressure of the hydrogen halide in the unit i's equal to at least about ve pounds per square inch.I Total pressures of from about 10 to about 100 pounds per square inch are preferred and they may be as high as 300 atmospheres or higher. Higher presmotor fuel: boiling range can be converted to higher octane number hydrocarbons at a` lower temperature than lower boiling isomerizable paraflin hydrocarbons can be converted. i

- Although as has been stated, the isomerization' reaction will generally take place in the liquid phase there are instances where vapor phase operation is preferable. For the isomerization of normal butane, operation in the vapor phase is sonietimes preferred while with the The catalyst may be either in the form of a slurry or adsorbed VYon a support. Higher temperatures are usually unnecessary and are Aundesirable 'in liquid phase operation due to the higher operating pressures and more expensive equipment necessitated.

The isomerization step, in either the liquid or vapor phase, may be conducted over a wide range of contact times of the material to be treated with the catalyst under the reaction conditions. The most suitable contact time will depend upon the particular catalyst, the particular reaction conditions such as temperature and pressure and sures appear to favor isomerization reactions, but

also result in the necessity for handling large amounts of nonhydrocarbon material, thereby necessitating larger equipment. If desired, relatively inert diluent gases such as hydrogen, nitrogen, carbon dioxide, methane, ethane, and the like may be introduced into the isomerization unit l1.

Ihe isomerization step is conducted at a temperature not greater than about 400 F. and preferably at temperatures below about 320 F. At temperatures greater than about 400 F. losses of material due to undesirable cracking reactions are prohibitive. The lower limit of the temperature range is set'by the temperature at which the desired isomerization will take place at apractical rate. Temperatures as low as 20 F. may in some cases be used, but only a very slow reaction rate can generally be obtained. A suitable practicable operating range is from about 120 F. to about 320 F. Generally, the higher temperatures are employed for the isomerization of normal parain hydrocarbons of lower molecular weight. That is, for example, all other conditions being equal, normal pentane can be isomerized at a lower temperature than normal butane and low octane number hydrocarbons in the upon the nature and composition of the material to be isomerlzed. 1n any case, the contact time is so chosen with respect to other factors that the decomposition and/or cracking of the resultant product is substantially obviated.. Higher temperatures of operation usually require lower contact times than lower temperatures of operation. Also, Vapor phase operation may require a lower contact time than liquid phase operation. This is duein part, to the fact that vapor phase operation is usually conducted at a higher teinperature range than liquid phase operation. Vapor phase isomerization of normal butano to isobutane, for example, at temperatures of from 120 F. to about 320 F. inthe presence of aluminum chloride catalyst requires contact times of from about 10 to about 200 seconds. 'For liquid phase operation in` the presence of aluminum chloride catalyst the time of contact will vary considerably ,for converting normal butane to isobutane and will range from about 1 to 150 minutes and may range as high as from 30 minutes to 30 hours in the temperature range between 30 and250," F. Furthermore, isomerization of higher molecular weight hydrocarbons, such as the conversion of low octane number hydrocarbons in the motor fuel boiling range to higher octane number motor fuel hydrocarbons, generally requires a lower contact time, other condil conditions discussed may be regenerated in any conventional manner well known to the art after vwhich the regenerated catalyst can again be em- 6 ever, it is not desirable to regenerate such a spent isomerization catalyst such a spent catalyst may be advantageously employed in a catalytic alkylation step, such as is conducted, in unit i2 of my process. oftentimes material, such as a spent aluminum halide, which will be obtained in an oily lform combined in a complex compound with hydrocarbon material and which is no longer active for promoting isomerization reactions can be used as a catalyst for the union of amlatable hydrocarbons with an alkylating reactant and .I contemplate so operating when it is desirable The eiiiuent of the isomerization unit 'il is passed therefrom through a pipe 82 controlled by a valve 83 to separating meanssfl which will in clude suitable fractionating columns. scrub .unitsl filters, and the like, together with associated equipment to effect the desired separation and purication of one or more hydrocarbon fractions of high octane number boiling in the motor fuel range. Light gases may be discharged from. the system through a pipe 85 controlled by a valve 8B. Tars, catalyst sludge, and the like, may be discharged from the system through pipe 8l controlled by a valve 88. A hydrocarbon fraction of high octane number suitable for use as a motor fuel stock 4is separated throughfa pipe 8@ 'con-f trolled by valve 9|., and may be passed directly tol pipe 4'! and recovered as a product of the process. In some instances especially with a ilmited extent of isomerizatlon one or more fractions of low octane number may be passed from separating means 84 through pipe 82 and 'valve 93 to pipe .15 for retreatment in the isomerization step. A portion of such a recycle stock may be removed from the system by being passed from pipe,92 through pipe 94 controlled by a valve 9S.

' Low-boiling hydrocarbons, which may include isobutane and/or isopentane, may be passed from separating means 84 to the alkylation unit i2 through pipe 96 controlled by a valve 9i.

It will be appreciated thatl in connection with the actual operation of any modification of my process much conventional equipment not shown in theflow diagram of the drawing may need to be used and may be readily supplied by one skilled in the art. Such equipment will include pumps. heaters, coolers, catalyst chambers, fractionating columns, reflux lines, temperature controllers, and the like. Such equipment may be adapted in any particular case by one skilled in the art with the benefit of the discussion and .disclosure of l,the operating conditions and material ows asoaess oi 500 pounds per square inch and in the absence j of a catalyst to form a mixture of alkymers comprising high octane number and low octane number paraiiln hydrocarbons boiling in the motor fuel range and formed by said alkylation, separating from said mixture a first fraction comprising so-formed high octane number alkymers boiling in the motor i'uel range, separating also from said mixture a' second fraction comprising so'- formed alkymers having the same number of carbon atoms per molecule as those of said first fraction but having a lower octane number, subjecting saidv second fraction to non-destructive hydrogenation to produce a low octane number ailnvlner fraction essentially free of non-paraffinic material, subjecting the resulting saturated fraction to isomerization in the presence of an isomerization catalyst of the metal halide type under conditions avoiding cracking to form high octane'number isomers of said alkymers 'solely by isomerization of said low octane number alkymers, separating from the eiiiuentlof said isomerization a high octane number fraction comprising said isomerlzed alkymers, and blendingthe last said fraction with the aforesaid first fraction to form as a product of the process a composite paraiiinic motor fuel stock of high ocnormally gaseous alkylatable straight-chain par- -arnns with said lower-boiling normally Vgaseous oleiins at a temperature between 750 and 1200"' F. and a pressure in-excessof 500 pounds per square inch and in the absence of a catalyst to form a mixture of alkymers comprising high octane number and low octane'number paranln hy- Y drocarbons boiling 'in the motor fuel range and .fraction to non-destructive hydrogenatlon to.

formed by said alkylation, separating from said mixture a iirst fraction comprising so-lormed v high octane numb'er alkymers boilingin the mo-"y tor fuel range, separating also from said mixture a second fraction comprising so-formed alkymers having the same number of carbon atoms per v molecule as those of said iirst fraction but having' a lower octane number, subjecting said second produce a low octane number -alkymer fraction between '150 and 1200 F. and a pressure in excess vessentially free of non-paraffinic material, subjecting the resulting saturated fraction to isomerization in the presence of 'an isomerization catalyst of the metalhalide type under conditions avoiding cracking to form high octane number isomers of said alkymers solely by isomerization of said low octane number allgvmers, separating from the eiiluent of said isomerization a high octane number fraction comprising said isomerizjed alkymers, and blending the last said fraction with the aforesaid first fraction to form as a product v of the process a composite paraiiinic motor fuel stock of high octane number. Y

` JEAN P. JONES.

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