US2306253A

US2306253A - Manufacture of motor fuel

Info

Publication number: US2306253A
Application number: US420999A
Authority: US
Inventors: Frank M Mcmillan
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1941-11-29
Filing date: 1941-11-29
Publication date: 1942-12-22
Anticipated expiration: 1959-12-22

Description

Dec. 22, 1942. F. M. McMlLLAN MANUFACTURE OF MOTOR FUEL Filed NOV. 29, 1941 L & O. C 1 5; *d'

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\nv zni"or: Frank M. McMman Patented Dec. 22, 1942 MANUFACTURE OF MOTOR FUEL Frank M. McMillan, Berkeley, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application November 29, 1941, Serial No. 420,999

13 Claims.

This invention relates to the production of high anti-knock hydrocarbon motor fuel fractions.

The invention provides a more efficient and economical method for obtaining branched-chain hydrocarbons from straight-chain hydrocarbon mixtures such as natural gasoline, low-boiling fractions of straight-run gasoline, and relatively low-boiling olefinic fractions obtained by fractionating the distillate products of thermal or catalytic hydrocarbon conversions. A method whereby these materials can be treated to obtain as substantially the sole products of the process, hydrocarbon fractions consisting essentially ofsingle branched-chain hydrocarbons or mixtures of branched-chain hydrocarbons having the same number of carbon atoms, is often greatly desired. Resort to the use of processes wherein cracking is the principal reaction is, in such cases, undesirable since the materials treated are converted to a wide range of hydrocarbons of which but a relatively small part may comprise the desired branched-chain hydrocarbons. The use of processes wherein isomerization methods available heretofore are used is often unsatisfactory, since in these processes the isomerization of higher hydrocarbons such as those having from five to ten carbon atoms to the molecule, particularly pentane, is generally unavoidably accompanied by hydrocarbon decomposition. The extent to which this hydrocarbon decomposition is encountered in these processes often renders the economical and efficient production of only the desired branched-chain hydrocarbons on a large scale difficult, if not impossible.

An object of the present invention is the provision of an improved process for the production of branched-chain hydrocarbons highly desirable as components of high anti-knock hydrocarbon motor fuels, from hydrocarbon mixtures predominating in straight-chain hydrocarbons. A more specific object of the invention is an improved process for the production of high anti-knock motor fuel fractions wherein straight-chain hydrocarbons having from four to ten carbon atoms to the molecule are converted more efficiently to higher-boiling branched-chain hydrocarbons in the absence of any substantial hydrocarbon decomposition. A still further object of the invention is the provision of an improved process for the production of higher-boiling hydrocarbon fractions predominating in branched-chain hydrocarbons having the same number of carbon atoms to the molecule from lower-boiling straightchain hydrocarbons.

In the improved process of the invention, a

mixture of substantially parailinic hydrocarbons is introduced into a fractionating zone wherein a fraction predominating in normal butane and at least one fraction predominating in a straightchain hydrocarbon having from five to ten carbon atoms to the molecule are segregated. The

butane fraction is catalytically converted to isobutane. The higher hydrocarbon fraction or fractions are admixed with efiluence of the butane conversion zone and subjected to isomerizing conditions at which the higher hydrocarbon or hydrocarbons are converted to branched-chain isomeric hydrocarbons in the absence of any substantial hydrocarbon decomposition. Isomerization products are returned to the fractionating zone, wherein fractions predominating in branched-chain hydrocarbons are segregated. At least a part of the branched-chain hydrocarbons thus obtained are admixed with an oleflnic hydrocarbon fraction, and the resulting mixture subjected to alkylating conditions. Saturated hydrocarbons originally present in the oleflnic fraction and unreacted branched-chain hydrocarbons are separated from the products of alkylation and passed to the fractionating zone, in which the paraffinic charge and isomerization products are fractionated.

In order that the invention may be more readily understood, it will be described in detail with reference to the attached drawing showing one form of apparatus suitable for carrying out the process of the invention. 1 w

Referring to the drawing, a mixture o'f'sub stantially parafiinic hydrocarbonssuch as, for

example, natural gasoline or a straight-run gasoline, is drawn from an outside source and forced by means of pump I through line 2 into a fractionating zone. In the drawing, fractionators 3, 4, and 5 are shown as constituting this fractionating zone. It will be understood that in actual practice more than three fractionators will generally be used to effect the indicated fractionation. Within fractionator 3, material lower-boiling than C4 hydrocarbons is removed overhead through valved line 6. A fraction consisting essentially of butane is separated and forced through line I by means of pump 8, into fractionator 4. A fraction consisting essentially of a paraflin hydrocarbon having from 5 to 10 carbon atoms to the molecule, for example pentane, is also separated within fractionator 3 and forced through line 9 by means of pump l0 into fractionator 5. Higher-boiling hydrocarbons are eliminated from the lower part of fractionator 3 through valved line H. Within fractionator 4, isobutane is separated as avapor fraction from normal butane, and within fractionator 5 isopentane is separated as a vapor fraction from normal pentane.

other aluminous and/or silicious adsorptivema- 1 terials. Modified catalysts of this type,- such as the mixture of an aluminum halide with other metal halides in either the solid 'or molten state may be used. Particularly eflective catalysts comprise a mixture of aluminum chloride dissolved in a mixture of molten metal halides such, for instance, as molten mixtures comprising The temperature to be maintained within reaction chamber l6 may range, for example, from about 50 C. to about 300 C., and preferably from about 100 C. to about 200 C. Under these conditions, butane will be converted to isobutane in its passage through reaction chamber IS.

The isomerization reaction in the presence of these catalysts is preferably carried out in the presence of a free hydrogen halide promoter such as, for example, hydrogen chloride. Hydrogen chloride is therefore introduced into line ll through line H: Generally, concentrations of hydrogen chloride in the order of from about 2% to about 10% by weight of the charge to the butane isomerization zon are sufficient. Larger or smaller amounts may, however, be used.

Normal pentane withdrawn from the lower part of fractionator 5 is forced through line 19 and heater 20 by means of pump 2| into a second isomerizing zone such as, for example, a reaction chamber 22. Within reaction chamber 22, normal pentane is contacted with an aluminum halide isomerization catalyst, preferably selected from those described above. Although but one reaction chamber is shown in the drawing as constituting each of the isomerization zones, it is to be understood that more than one reaction chamber or reactor may be used in each of the zones.

It is well known that butane, the first member of the isomerizable hydrocarbons, is, in relation to its higher-homologues, comparatively stable. It may be treated under relatively severe conditions with even highly active isomerization catalysts with only minor amounts of decomposition. The higher hydrocarbons, such as those having from five to ten carbon atoms to the molecule, and especially pentane, however, are particularly prone to undergo decomposition in the presence of isomerization catalysts. By th term decomposition as used throughout this specification and the attached claims is meant the rupture of carbon to .carbon and/or carbon to hydrogen bonds of the hydrocarbon molecule, to result in the formation of hydrocarbons of lower molecular weight than the hydrocarbon being isomerized. When these higher hydrocarbons are isomerized in accordance with the methods utilized heretofore, an appreciable amount of isomerization can, under certain conditions, be attained. The extent to which hydrocarbon decomposition is unavoidably encountered in these methods generally acts as a serious deterrent to the practical application of these processes to the isomerization of hydrocarbons having from five to ten carbon atoms to the molecule. These decomposition reactions are detrimental not only because they occasion considerable loss of .the hydrocarbon being treated by converting it to undesirable byproducts, but because these by-products, even when formed in relatively small amounts, generally bring about rapid destruction of the activity of the isomerization catalyst. In the procass of the invention, these difficulties are avoided by catalytically isomerizing the hydrocarbons having more than four carbon atoms to the molecule in the presence of isobutane, which has been found to suppress hydrocarbon decomposition in the presence of the isomerization catalysts.

In the process of the invention, the entire effluence of reaction chamber 16 comprising isobutane, unreacted butane, and hydrogen chloride, is passed through line 23 into line I9, thereby admixing with the normal pentane prior to the entry of the pentane into reaction chamber 22. The passage of the eiiiuence of reaction chamber is directly into reaction chamber 22 not only eliminates the need of separate fractionation and recycling of the products of the separate isomerizing zones, but permits the full utilization of the heat content of this stream to aid in maintaining the desired temperature in reaction chamber 22. Since the C4 hydrocarbon decomposition suppressor and the hydrogen halide" promoter constitute the predominant part of the chargeto the pentane isomerizing zone, a considerable saving in-heating requirement is thereby attained. The temperature to be maintained within reaction chamber 22 will generally be somewhat lower than that maintained within reaction chamber 16. 1t is to be pointed out, however, that the presence of the butanes enables the pentane isomerization to be carried out at temperatures substantially in excess of those at which pentane can be isomerized at all economically in processes utilized heretofore. The temperature within reaction chamber 22 is maintained within the broad range of, for example, from about 30 C. to about 150 C. The particular type of catalyst used will determine to a substantial degree the temperatures within this broader range which are preferrcd for any one operation. Thus, when isomerizing pentan with a solid, supported aluminum halide catalyst, a temperature of from about 40 C. to about 60 C. may suitably be used. When the pentane isomerization is executed in the presence of a catalyst of the molten salt type, a higher temperature of from about C. to about C. is generally preferred. Within reaction chamber 22, normal pentane will, under these conditions, be converted to isopentane, and due to the presence of isobutane the pentane isomerization will be effected in the absence of any substantial pentane decomposition.

Isomerization products comprising isobutan'e, lsopentane, I unreacted normal butane and pentane, and hydrogen chloride are withdrawn from isomerizing zone 22 and passed through line 24 and cooler 25 into an accumulator 26. In passing through cooler 25, the reaction products are cooled to a temperature sufliciently low to effect the condensation of at least a substantial part of the C4 hydrocarbons. Additional cooling means not shown in the drawing may be utilized if desired. Condensed products comprising C4 and C5 hydrocarbons are forced by means of pump 21 from accumulator 26 through line 28, to a stripping column 29. Gaseous materials comprising hydrogen chloride and uncondensed hydrocarbons are forced from accumulator 26 by means of compressor 30 through line 3i, into stripping column 29. Within stripping column 28, a normally gaseous fraction comprising hydrogen chloride is separated from a liquid hydrocarbon fraction comprising C4 and Cs hydrocarbons. 'A high pressure, for example in excess of 350 lbs., is preferably maintained in stripping column 29 to aid in eifecting the desired separation. The liquidfraction comprising C4 and Cs hydrocarbons is recycled through valved line 32 to line 2, leading into fractionator 3. The

normally gaseous fraction comprising hydrogen chloride is eliminated from stripping column 29 through valved line 31 and passed at least in part through lines 34 and IT, into line H. Makeup hydrogen chloride is introduced into the system through valved line 85, leading into line 34, as needed.

The amount of isobutane to be maintained within reaction chamber 22 may vary considerably within the scope of the invention in accordance with the particular catalyst used. Whereas normal butane has little, if any, effect in suppressing decomposition reactions in the presence 01 supported aluminum halide catalyst, it does have a favorable eflect in the presence of aluminum halide catalysts of the molten salt type. Therefore, when utilizing the molten salt type catalysts. this a ded eflect of the normal butane present in the e uence of reaction chamber l6 permits the maintenance of lesser amounts of isobutane in reaction chamber 22 than if a supported aluminum chloride catalyst were used. Maintenance of a molecular excess of isobutane within reaction chamber 22 is, however, desirable. To aid in maintaining any desired proportion of isobutane to pentanes, controlled amounts of Cr hydrocarbons may be recycled, when needed, with the hydrogen chloride from stripping column 29 through line 34. When recycling C4 hydrocarbons with the hydrogen chloride promoter, the greater amount of the gaseous stream recycled through line 34 can be by-passed through valved line 38 into line 23, and only a suiiicient' amount of the mixture passed into line I! to provide the desired amount of promoter to reaction chamber I6, by judicious control of valves 36 and 31. Means not shown in the drawing may be used to recycle C4. hydrocarbons in a separate stream to reaction chamber 22, should this be required.

The effectiveness of isobutane in suppressing pentane decomposition in the presence of an aluminum chloride catalyst is shown in the following examples:

. Example I A mixture of normal pentane and isobutane in equal molar proportions was treated at 90 C. under a hydrogen chloride pressure of 50 lbs. per sq. in. with a molten salt catalyst having the following composition in weight per cent: Alma-75%, ZllCl2-10%, NaCl-7.5%, KCl7.5%. Analysis of the products showed an 85% conversion of pentane to isopentane in mol per cent. Only a negligible amount of pentane decomposition was observed. The remainder of the pentane charged was unchanged.

Example II A mixture of pentane and isobutane consisting of 33% mol per cent pentane and 66% mol per cent isobutane was passed over activated alumina impregnated with aluminum chloride at a temperature 50 C. and a pressure of 60 lbs. per sq. in. Hydrogen chloride in the amount of 1 mol per cent of the hydrocarbon charge was added. At the end of thirty hours of continuous operation, a conversion of normal pentane to isopentane of 50 mol per cent was obtained with only a negligible amounLot-pentane decomposition. The remainderbi the pentane charged was unchanged.

It is to be pointed out that the unusual effectiveness in suppressing hydrocarbon decomposition in the presence of the aluminum halide isomerization catalysts is apparently restricted to the C4 paraflin hydrocarbons and is not possessed by propane, ethane, or methane.

The isomerization reactions within chambers l6 and 22 may be executed in either the liquid or the vapor phase. When effecting the isomerization in the liquid phase, it is preferred to use a catalyst of the molten salt type described above. Since normal butane aids in suppressing the hydrocarbon decomposition reaction in the presence of the molten salt type catalyst, a highly advantageous method of carrying out the process of the invention comprises the execution of the butane isomerization in chamber Ii in the presence of a supported aluminum halide catalyst, and the isomerization of the higher hydrocarbon in chamber 22 in the presence of a catalyst of the molten salt type. When executing the process of the invention in-this wise, the eilluent chamber l6 will generally suffice to eflect the complete suppression of any substantial hydrocarbon decomposition within chamber 22. The pressure to be maintained within the isomerization zones may vary widely within the scope of the invention. Pressures in the order of from about 50 to about 300 pounds have been found highly suitable. When operating in the liquid phase, a pressure sufllciently high to maintain the hydrocarbon in the liquid phase is maintained.

Isobutane is eliminated overhead from fractionator 40 through line 39. A substantially olefinic hydrocarbon fraction predominating in hydrocarbons having the saine number of carbon atoms to the molecule is drawn from an outside source by means of pump 40 and forced through line H into line 38, wherein it is admixed with the isobutane. The olefinic hydrocarbon fraction may be obtained from any suitable source such as, for example, by fractionation of the distillate products of a thermal or catalytic hydrocarbon conversion operation. These fractions, as they are generally more readily obtained, comprise the oleflne in admixture with the paraflin hydrocarbon'having the same number of carbon atoms tothe molecule as the olefine. Thus, a suitable fraction comprises a butane-butylene fraction. The resulting mixture of isobutane, butylene, and butane is passed into an alkylating zone. The alkylating zone may comprise an alkylation unit comprising one or several stages provided with means for contacting the hydrocarbon stream therein with a suitable alkylation catalyst such as sulfuric acid or the like, and for separating the product from the catalyst For the sake of simplicity, the alkylating zone is depicted in the drawing by reactor 42. Within reactor 42, condltions are maintained to bring about the alkylation of branched-chain saturated hydrocarbons with olefines. Thus, the reaction maybe carried out at a temperature in the range of, for exampie, from about 5 C. to about C. at a pressure sufficiently high to maintain the reactants in the liquid phase. A cooler or refrigerating means 43 is positioned before reactor 42 to aid in maintaining the desired temperature. The rate at which the olefine fraction is introduction into the system is controlled to maintain an excess of the less reactive isoparafiin molecule relative to the olefinic hydrocarbon within the alkylating zone. It is to be understood that the manner in which the reaction is effected as well as the operating conditions employed, may be varied to produce the results particularly desired.

Alkylation products, which, when treating isobutane with a butylene-butane fraction, comprise branched-chain hydrocarbons having eight carbon atoms to the molecule, unconverted isobutane, and normal butane originally present in the olefinic fraction, after having been neutralized, are passed through line 44 into a stripping column 45. Within stripping column 45, unreacted isobutane and the normal butane which was originally present in the olefinic hydrocarbon fraction charged to the system is separated as a vapor fraction from a liquid hydrocarbon fraction comprising the alkylate. The vapor fraction is removed overhead from stripping column 45 through valved line 46, and forced in part or in its entirety by means of pump 49 through

valved lines

41 and 48 into line I, passing into fractionator 4. It is seen that in the process of the invention both the paraflinic and olefinic constituents of fractions such as the butylenebutane fractions which are usually available in abundance in many refinery operations are utilized efficiently in the production of desired branched-chain hydrocarbons without prelimi nary separation of the olefinic and paraffinic constituents. The alkylate, consisting essentially of branched-chain hydrocarbons having eight carbon atoms to the molecule, is withdrawn from stripping column 45 through valved line 50.

Isopentane withdrawn from the upper part of fractionator 5 through valved line 5| may be removed in part or in its entirety from the system through valved line 52 as a final product. A part or all of the isopentane, which is itself a highly desirable motor fuel component, may be passed through valved line 53 and combined with the alkylate withdrawn from fractionator 45 through line 50. All, or a part of the isopentane, may be passed through lines 5! and 39 to reactor 42 to be alkylated with the olefine therein. A valved line 54 is provided for the elimination of any part or all of the isobutane from the system when isopentane is passed to the alkylating zone.

The invention is not limited to the use of butane-butylene as the olefinic fraction, and other olefinic fractions such as, for example, a propylene, butylene, amylene, cyclopentene, cyclohexene, or higher olefinic fraction, may be used. When such fractions are used, the saturated con stituents thereof are passed from stripping column 45, through line 4'! to line 2, leading to iractionator 3. If a hydrocarbon fraction comprising hydrocarbons of the same number of carbon atoms as those passed through line 41 is being fractionated in fractionator 5, the hydrocar on stream flowing through line 41 is by-passed through valved line 55 into line 9.

Although the above-detailed description has been limited for the sake of simplicity to the iso merization oi the butane and pentane content of the parafiinic hydrocarbonmixture charged, it is to be understood that a straight-ohain parai'nnic hydrocarbon having from six to ten carbon atoms may be separated and isomerized instead of the pentane. The invention, furthermore, contemplates the separate isomerization, in the presence of efiluence of the butane isomerization zone, of more than one straight-chain hydrocarbon having from five to ten carbon atoms to the molecule. Though the invention is directed primarily to the production of branched-chain hydrocarbons from mixtures predominating in straightchain hydrocarbons, it is not beyond the scope of the process to separate a higher branched-chain saturated hydrocarbon within the charge fractionating zone and subject it to separate catalytic isomerization in the presence of elfluence of the first isomerizing zone to a more highly-branched isomer. The more highly-branched hydrocarbon thus obtained may, if desired, be passed to the alkylation zone. The additional isomerization and fractionating means which may be required for the execution of these various modifications of the invention have been omitted from the drawing for the purpose of avoiding undue complexity. When a plurality of hydrocarbons having from five to ten carbon atoms are isomerized, any single, several, or all of the resulting branched-chain 'paraflin hydrocarbons produced in the isomerization steps may be passed'to the alkylating zone. Although but one alkylating unit is shown in the drawing, additional alkylating units may be provided to effect the alkylation in separate units of isobutane and one or more branched-chain saturated hydrocarbbns having from five to ten carbon atoms to the molecule. The process of the invention thus enables the production oi a wide variety of branched-chain hydrocarbon fractions optionally predominating in branched-chain hydrocarbons of the same number of carbon atoms, with a minimum of operative steps and in the absence of any hydrocarbon decomposition.

I claim as my invention:

1. In a process for the production of branchedchain hydrocarbons in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantially parafiinic hydrocarbon mixture comprising C4 and C5 hydrocarbons in a fractionating zone to separate fractions respectively rich in normal butane and normal pentane therefrom, contacting the normal butane fraction at a temperature in the range of from about C. to about 200 C. with an aluminum halide catalyst in a first isomerizing zone, contacting the pentane fraction in admixture with the eiiluence of the first isomerizing zone at a temperature in the range of from about 40 C. to about C. with an alu minum halide catalyst in a second isomerizing zone, separating isobutane and isopentane from the eflluence of the second isomerizing zone, contacting said isobutane and isopentane in admixture with a hydrocarbon fraction predominating in butylene and butane at alkylating conditions with an alkylation catalyst, thereby reacting isobutane and isopentane with butylene, separating butane, isobutane, and isopentane as a vapor fraction from the products of alkylation, and passing said vapor fraction to said fractionating zone.

In a process for the production of branchedchain hydrocarbon fractions in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantially parafilnic hydrocarbon mixture comprising hydrocarbons having from four to ten carbon atoms to the molecule in a fractionating zone to separate fractions respectively rich in normal butane and a higher saturated hydrocarbon having from five to ten carbon atoms to the molecule therefrom, contacting the normal butane fraction at a temperature in the range of from about 50 C. to about 300 C., with an aluminum halide catalyst in a first isomerizing zone, contacting the higher hydrocarbon fraction in admixture with the eiiluence of the first isomerizing zone at a temperature in the range of from about 30 C. to about 150 C. with an aluminum halide catalyst in a second isomerizing zone, separating branched-chain hydrocarbons from the efiiuence of the second isomerizing zone, contacting the branched-chain hydrocarbons in admixture with a hydrocarbon fraction predominating in butylene and butane at alkylating conditions with an alkylation catalyst, thereby reacting branched-chain hydrocarbons with butylene, separating butane and unreacted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing said vapor fraction to said fractionating zone.

3. In a process for the production of branchedchain hydrocarbon fractions in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantiallyparaffinic hydrocarbon mixture comprising hydrocarbons having from four to ten carbon atoms to the molecule in a fractionating zone to separate fractions respectively rich in normal butane and a higher saturated hydrocarbon having from five to ten carbon atoms to the molecule therefrom, contacting the normal butane fraction at a temperature in the range of from about 100 C. to about 200 C., with an aluminum halide catalyst in a first isomerizing zone, contacting'the higher hydrocarbon fraction in admixture with the efliuence of the first isomerizing zone at a temperature in the range of from about 40 C. to about 50 C. with a catalyst comprising an aluminum halide and an adsorbent support material in a second isomerizing zone, separating the branched-chain hydrocarbons from the eiiiuence of the second isomerizing about 80 C. to about 110 C. with a molten salt mixture comprising an aluminum halide in a second isomerizing zone, separating branchedchain hydrocarbons from the eflluence of the second isomerizing zone, contacting the branched-chain hydrocarbons in admixture with a hydrocarbon fraction predominating in butylone and butane at alkylating conditions with an alkylation catalyst, thereby reacting branchedchain hydrocarbons and butylene, separating butane and unconverted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing said vapor fraction to said fractionating zone.

5. In a process for the production of branchedchain hydrocarbons in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantially paraiiinic hydrocarbon mixture comprising C4. and C5 hydrocarbons in a fractionating zone to separate fractions respectively rich in normal butane and normal pentane therefrom, contacting the normal butane fraction under isomerizing conditions with an aluminum halide catalyst in a first isomerizing zone, contacting said pentane fraction in admixture with the efiiu'ence of the first isomerizing zone under isomerizing conditions with an aluminum halide catalyst in a second isomerizing zone, separating isobutane and isopentane from the eiiluence of the second isomerizing zone, contacting said isobutane and zone, contacting the branched-chain hydrocarbons in admixture with a hydrocarbon fraction predominating in straight-chain olefine and paraflin hydrocarbons of the same number of carbon atoms at alkylating conditions with an alkylation catalyst, thereby reacting branchedchain hydrocarbons with the olefine, separating the straight-chain paraffin and unreacted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing the vapor fraction to said fractionating zone.

4. In a process for the production of branchedchain hydrocarbon fractions in the absence of any substantial hydrocarbon decomposition, the

steps which comprise fractionating a substantially paraflinic hydrocarbon mixture comprising hydrocarbons having from four to ten carbon atoms to the molecule in a fractionating zone to separate fractions respectively rich in normal butane and a higher saturated hydrocarbon having from five to ten carbon atoms to the molecule therefrom, contacting the normal butane fraction at a temperature in the range of from about 50 C. to about 300 C. with an aluminum halide catalyst in a first isomerizing zone, contacting the higher hydrocarbon fraction in admixture with the effluence of the first isomerizing zone at a temperature in the range of from isopentane in admixture with a hydrocarbon fraction predominating in butylene and butane at alkylating conditions with an alkylation catalyst, thereby reacting isobutane and isopentane with butylene, separating butane, isobutane, and isopentane as a vapor fraction from the products of alkylation, and passing the vapor fraction to said fractionating zone.

6. In a process for the production of branchedchain hydrocarbons in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantially paramnic hydrocarbon mixture comprising C4 and C5 hydrocarbons in a fractionating zone to separate fractions respectively rich in normal butane and normal pentane therefrom, contacting the normal butane fraction under isomerizing conditions with an aluminum halide catalyst in a first isomerizing zone, contacting the pentane fraction in admixture with the efiiuence of the first isomerizing zone under isomerizing conditions with an aluminum halide catalyst in a second isomerizing zone, separating isobutane and isopentane from, the effluence of the second isomerizing zone, contacting said isobutane and isopentane in admixture with a hydrocarbon fraction predominating in straight-chain olefine and paraffin hydrocarbons having the same number of carbon atoms at alkylating conditions with an alkylation catalyst, thereby reacting isobutane and isopentane with said olefine, separating the straight-chain paraffin and unreacted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing the vapor fraction to said fractionating zone.

7. In a process for the production of branchedchain hydrocarbons in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractlonating a substantially paraffinic hydrocarbon mixture comprising hydrocarbons having from four to ten carbon atoms to the molecule in a iractionating zone to separate fractions respectively rich in normal butane and a higher saturated hydrocarbon having from admixture with a hydrocarbon fraction predominating in butylene and butane at alkyiating condltions with an alkylation catalyst, thereby reacting branched-chain hydrocarbons with butylene, separating normal butane and unreacted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing the vapor fraction to said iractionating zone.

13. In a process for the production of branched chain hydrocarbons in the absence of any substantial hydrocarbon decomposition, the steps which comprise fractionating a substantially parafiinic hydrocarbon mixture comprising hydrocarbons having from four to ten carbon atoms to the molecule in a fractionating zone to separate fractions respectively rich in normal butane and a higher saturated hydrocarbon having from five to ten carbon atoms to the molecule therefrom, contacting the normal butane fraction in admixture with a hydrogen halide promoter at isomerizing conditions with an aluminum halide isomerization catalyst in a first isomerizing zone, contacting the higher hydrocarbon fraction in admixture with the efliuence of the first isomerizing zone under isomerizing conditions with an aluminum halide catalyst in a second isomerizing zone, separating hydrogen halide, isobutane, and a higher branched-chain hydrocarbon from the eiiiuence of the second isomerizing zone, recycling a part of said isobutane to the second isomerizing zone, contacting the remaining isobutane and higher branched-chain hydrocarbon in admixture with a hydrocarbon fraction predominating in butylene and butane at alkylating conditions with an alkylation catalyst, thereby reacting branchedchain hydrocarbons with butylene, separating normal butane and unreacted branched-chain hydrocarbons as a vapor fraction from the alkylation products, and passing the vapor fraction to said fractionating zone.

FRANK M. McMILLAN.