US2317901A - Conversion of hydrocarbons - Google Patents

Description

motor fuels and charge stock,

Patented Apr. 27, 19143 CONVERSION F HYDROCARBONS y Frederick E. Frey,

Bartlesville, Okla., assignor'to Phillips Petroleum Company, a corporation ot Delaware Application March 11, 1940, Serial No. 323,443

' olens to form higherboiling parafns, the pres# This invention relates to the catalytic production of higher boiling hydrocarbons from lower boiling hydrocarbons and more particularly to the catalytic union of parain and unsaturated hydrocarbons in the' presence of hydroi'luoric` acid.` This application is a `continuation in part of my copending application, led January 22, 1940.

Many processes have Serial No. 315,063,

been proposed for con- 'verting low boiling hydrocarbons into higher of paraflln hydrocarbons in divided nickel, metal halides, and the like. Thus,

boiling hydrocarbons, such as the production of lubricants from less viscous, more volatile, or normally gaseous hydrocarbons. Some of these processes are dependent upon having olefin hydrocarbons, or other unsaturated hydrocarbons, present in large proportions in the catalytic polymerization processes for producing motor fuel from refinery gases containing'light unsaturated hydrocarbons from cracking stills. Still other processes have been proposed to produce heavier hydrocarbons from lighter param-p hydrocarbons, such as thermal conversion under pressure whereby scission of the paraillns and polymerization proceed concurrently to produce conversion, or multistage processes employing a dehydrogenation step as a rst part of the process, followed by one or another variety of conversion polymerization involving the olelns so produced.

This invention relates particularly to the alkylation of paraffin hydrocarbons to produce alkyl amn hydrocarbons to form higher boiling parain hydrocarbons. I have further found that it is preferable to use as a catalyst for thisreaction Asubstantially anhydrous hydrouoric acid, or

hydrogen' fluoride, and that it can be eectively and safely used over a'wide range of temperatures. I have also `found that, although metal halide catalysts such as boron trifluoride have been used in the presence of appreciable quantities of finely divided metallic nickel and hydrogen fluoride to catalyze Athe reaction of parafflns and such as in well known thermal and l ence of such other' materials as finely divided metals and/or metal halides my invention, and that I can use concentrated hydrofluoric acid as a catalyst for the alkylation the absence of finely when reference'is made hereinafter, in the speciiication or in the claims, to concentrated hydrofiuoric acid or to substantially anhydrous fluorlcacid, it is tohbe understood that I regard the hydroiluoricy acid as being the sole catalytic material. Althoughthe metal walls of the reactionfchambers or vessels may at times have some fortuitous promoting eilect, the process has been` carried out in the presence of numerous metals without appreciable differences being noted, so thatsuch eiects of gross masses of metal are substantially negligible ifat all present.

The present invention relates particularly to the alkylation of normal paramns, such as normal butane and/ornormal pentane, with olens in the presence of concentrated hydrofiuoric acid. In-one modication it relates to a process wherein isoparains are more or less completely and selectively alkylated in the presence of normal paraiiins, heavier hydrocarbons so produced are removed, and unreacted paraiiin hydrocarbons are alkylated in the presence oi concentrated hydrofluoric acid under conditions adapted to react substantial portions of normal Iparafiins.

Thus, I have found that normal parafns can be alkylated by reaction with olei'lns in the presence of concentrated hydrofluoric acid at temperatures above about or 120 F. to form paraflnic products of higher molecular weight than'the original normal parailins. I have also found that' at temperatures no higher than about 100 F., and often appreciably lower than this, a mixture of i'soparaflin-s and normal paraiiins can be subjected to alkylation with olens in the presence of a suitable alkylating agent and the alkylation so controlled that substantially only isoparafns undergo reaction, leaving normal paraftlns substantially or completely unreacted, in a more concentrated state, and suitable for subsequent alkylation with olelins in the presencev oi con- 'centrated hydroiluoric acid at more elevated temperatures. Catalysts'which may be used for the alkylation of isoparafilns include Ialuminum chloride and bromide, boron chloride and fluoride. concentrated sulfuric and sulfonic acids, and concentrated hydrouoric acid. The latter is the most preferablecatalyst for'use in this iirst step,

as the first step and the second step can bemore is not necessary for hydroclosely cooperatively combined, as will be further discussed hereinafter.

It is an object of this invention to produce higher boiling paraffin hydrocarbons by the cially desirable characteristics and controlled properties, reflecting closely the identities of the reactant hydrocarbons selected.

An object of my invention is a process for the alkylation of parafns with oleilns in the presence of substantially anhydrous hydrofluoric acid to produce various simple branched paraflins or amixture of simple composition within a widev range of boiling points or volatilities.

Another object is to effect the eilcient recovery by physical means of hydrouoric acid when used as a catalyst in the alkylation of paraiins with olens. y

Another object is to alkylate isoparafns selectively with olefins when in a mixture comprising isoparalns and normal parafllns to form higher boiling paraiin hydrocarbons, and subsequently to alkylate normal parailns from said mixture with olefins in the presence of concentrated hydrofluoric acid.

Further objects and advantages of my invention and process will be found in the accompanying disclosure and discussion.

Catalysts which effect the alkylation of paraffins with olefins include active metal halides such as aluminum chloride, especially in the presence of small amounts of the corresponding hydrogen halide, certain complex salts such assodium chloroaluminate, and concentrated sulfuric acid, a strong oxygen-containing. polybasic acid. However, these and similar catalysts have one or more disadvantages, chief among which are the promotion of unwanted side reactions, and more or less rapid deactivation of the catalysts accompanied by chemical reactions involving these materials. Thus aluminum chloride, boron trifluoride, and similar metal halides form addition compounds with olefin hydrocarbons which non-oxidizing and no-reducing material, so that' it can be used, and treated, at elevated temperatures without the undesirable side reactions just mentioned. While somewhat more dilute concentrations may be used, I prefer to use it in concentrations greater than 80 percent by weight, the

other material being Water, and I have found that substantially 100 percent hydroiluoric acid, that is, substantially or completely anhydrous hydroiluoric acid or hydrogen fluoride, is very effective, and is particularly adapted to the process arrangements to be hereinafter described more fully. As will be discussed, the process is generally carried out with the hydrocarbon material substantially in liquid phase; efficient reaction results when suflicient hydrofluoric acid is employed to result in a substantial saturation of the liquid hydrocarbon material with hydrogen fluoride, and perferably sumcient hydrogen fluoride is used to form a separate liquid phase which may be maintained emulsied or intimately mixed with the hydrocarbon while reaction takes place. In most cases the hydrofluoric acid charge should vbe at least 10 percent of the total charge, on a liquid volume basis, and hardly ever need exceed or 60 percent, though more can, at times, be used. In the concentrated form, hydroiluoric acid is substantially inert, or non-corrosive, toward numerous metals, such as copper, nickel` most steels, and various other alloys which can be used in the construction of plant equipment. Occasional fortuitous reactions may produce mlnor'amounts of inorganic fluorides but, as previously discussed, insofar as this invention is concerned hydrouoric acid is considered to be used in the substantial absence of added metals or metal halides. The reaction temperature may beV varied over a wide range for any particular reaction mixture, but appears to be most dependent sooner' or later degenerate into black, tar like.

masses which not vonly representa deactivation of catalytic materials, but also represent a loss of valuable hydrocarbon material and necessitate involved procedures for eliminating such materials and recovering the metal halide in a form suitable for subsequent use. sulfuric acid, which has recently found Wide commercial application as an alkylating catalyst, h as somewhat similar disadvantages. While apparently it does not -form such definite intermediate compounds with olefin hydrocarbons as do variousmetal halides, there apparently is associated with its use a formation of various organic compounds, which after a time render the acid muchless active, so that sulfuric acid which contains only 10 or 15 percent of such organic material must be replaced with fresh, uncontaminated acid. sulfuric 'acid is also a powerful oxidizing agent, so that it cannoli be upon the parailln 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.

I have found that when an intimate mixture of a normal parailin hydrocarbon, concentrated hydrofluoric acid, and an olefin hydrocarbon is maintained at a reaction temperature, a union takes place between the normal parailln and the olefin to form a higher boiling parailin which generally represents the sum of the original f parafn and olefin not only as to molecular weight but also as tomolecular structure. Butanes are' ordinarily too light to be included ingnost motor fuels in appreciable quantities, so that they wills form the usual paraflinic reactants. While pentanes are present in most motor fuels in appreciable proportions, it will at times be desirable either to utilize excess pentanes or produce a fuel of very low volatility and pentanes. or heavier parafllns, may be used as reactants in such cases. Highly branched isooctanes can be produced either by alkylating butanes with butylenes or by alkylating pentanes with propylene, while highly and during the addition of olens.

`may be caused to react with oleiins in the presence of concentrated hydroiiuoric acid at elevated temperatures which heretofore could not b`e applied to mixtures of aliphatic hydrocarbons and concentrated mineral acids because of ex-vcessive deleterious side reactions. Thu's, I conduct the reaction -of normal paraiiins with oleflns at temperatures above about 120 F., preferably within the range of 150 to 300 F., but in some instances as high as 500 or 600 F. While the alkylation of normal paramns may be carried out under only slight superatmospheric pressures, Y

it is preferable to operate under substantial. superatmospheric pressures, such as about 100 to 1,000 or 2,000 pounds per square inch or more.'

The process is preferably conducted with at least u an appreciable portion of the reactant material in liquid phase, although this is not necessary for all reactants. When the process is conducted with a substantial portion of the reactants in liquid phase, the reaction temperature should not be above the critical temperature of the highestboiling reactant, and the pressure should be at least noless than the vapor pressure of this reactant, and preferably should be at least 500. poundsper square inch. Since the alkylation temperatures., even in the upper part of the range indicated, are still rather moderate, the pressures ordinarily need not be excessively above thevapor pressure of the reacting mixture and can, of course, be as low as can be shown by trial to pera, mann mit effective alkylation. In many instances normal parafl'lns can bealkylated in the presence of hydrofluoric acid at pressures between 50 sand 500 pounds per square inch. With some of the lower boiling and less reactive of the parafns, it may be desirable to conduct the alkylation at a temperature in the upperpart vof the range indicated.

It appears that if a mixture of paraftlns and olens containing a large portion of oleilns,` such as 30 to 50 mol percent, or more, cf.the total mixture, is reacted in the presence of concentrated hydrotluoric acid, j the molecular weight of the hydrocarbon product tends tobe higher than f would result if the same amount of oleiln and paraiiin were'reacted by adding -small amounts or portions of olefin to'a'predominantly parainic mixture in the presence of hydroiiuoric acid, While 'allowing reaction to take While it seems that, in many instances with various particularolen and paran reactants, some type of olefinplace betweent consumption reaction occurs very rapidly, so that immediately after olefin-containing material is introduced to the reaction zone the concentration of free olefin rapidly approaches a low value-often less than one percent-and is difii` cult to determine experimentally a`s to amount, more lower molecular weight products generally result, especially with the more reactive oleflns, if high momentary concentrations of oleiins in the reacting mixture are not'obtained or permitted to result. Any olefin-consumption reaction which takes place under these conditions is exothermic, and for a close control of the reaction, heat should be removed as it develops. It is, of course, possible to produce a parainic product whenthe total is one of the principal olefin reactant the process is carried out at elevate tureswith somewhat lessreactive'pa' Icharge stock contains more than -50 mol per- 1s may be added at o it willgenerally be desirable to ad n both cases but not always been found 'to be quite de- When separate streams of are available, this can be ontinuous process by disreacting stream as reaction adding olens at a plurality of lcourse of the reacting stream in er designed to effect rapid dispersal within the reactingvmedium. When the oleflns and paraiins to be ,reacted are in the same mixture, with oleins in a rath suitable low c'oncentr and maintained by r'e eiiiuent of the reacti reaction zone.. using it to dilu charge stock. When thi used, a. portion,

ation may be established circulating a portion of the or portions, ofthe charge stock various points along the course ream, thus reducing the amount of the recycle stream necessary to mantain an initial low concentration. In these modifications opportunity should, of course, be provided for abstraction of heat as reaction proceeds,- and beforefurther olefin addition. I have found that the most'desirable results are obtained when the amount of oleiin adde the reacting mixture is not greater than about 10 mol percent of the total hydrocarbon material present, at the immediate zone of addition. Thus, in La, continuous operation, wherein an olencontaining stream is added at a point or zone of introduction to aparailinic stream, this is to mean that the amount of olefin in this olefin-containing stream does not exceed the specified mol'percent of this stream plus the reactantstream. A

of the reacting st suitable time for reaction, andabstraction of -those containing less reactive oleiins, olein con-` sumption reactions are not so rapid and somewhat higher olen concentrations may be maintained in the reacting stream without resulting inA too great'an increase in the proportion of products, of higher molecular Weights'. When the charge stock is especially reactive the added oleflns may need to bev kept as'low as 1 o for any particular point or zone of oleiln in'troduction, but generally satisfactory con be found when the added olens are and `8 percent of the total'stream.

easily polym'eriz'able olen, such as is between 2 When an obutylene,

d temperarafllns, such as temperatures between about 125 and 300 F..

amounts of oleiins at any one point, 'with a substantial amount ol. re

cycle and/or manypoints' of-oienn addition.

vcent olens. When there is high initial concen- I gain is alkylated'V ultimate result is mall amounts of' oleiins aser high concentration, a

on zone back through this te the incoming. s latter modification is d to any particular part of r 2 percent ditions will` S., or when d only small -Y Olefns over a wide rangeof'molecular weights tion of parains in the presence of concentrated hydrofluoric acid. One of the principal commercial applications of my invention at present is the production of paraffin hydrocarbons in the .5 motor fuel range from lower boiling hydrocarbons, 'and for this reason olens of ve or fewer carbon atoms per molecule are more often pre- 'ferred. Of these, ethylene enters into reaction least readily, especially in the absence of oleflns of more carbon atoms per molecule. While pentenes are generally considered to be in the motor fuel boiling range, it will often be desirable to decrease the amount of C5 hydrocarbons in a final product for reasons of volatility, or a high boiling fuel of low vapor pressure may be desired, so that it will not be unusual to use pentenes. Hexenes, heptenes, octenes, and the like are more often cf greater value as they are, although they are not to be excluded in the broadest concepts of this invention. Cycloolens, such as cyclopentene, cyclohexene, and the like, also enter into reaction as ordinary aliphatic oleflns.

The reaction period, during which olefin is in-` troduced, reacted and consumed to produce eventually a parafflnic product, is dependent to a certain extent upon the reaction temperature and the total amount of olefins reacted. A period between minutes and 2 hours has been found satisfactory in most cases, but at higher tempera- 30 tures a reaction period as low as about 5 minutesy or somewhat less, will often be suiiicient. At lower temperatures and low olefin concentration, which is preferred at times when preparing certain especially pure products, periods as high as 4 or 5 hours may be found. most desirable.

It will be understood, of course, that all these reaction variables are more \or less interdependent. and that when one is arbitrarily fixed the limits within which others may be varied are somewhat restricted. The more desirable ranges for ordinary applications of my invention have been indicated, and can also be ascertained lfrom the specific examples presented hereinafter. However, for any particular application of my invention, the most desirable conditions can be readily determined by trial by one skilled in the art, such a determination being facilitated by the discussion of trends of these variables presented herewith.

As previously mentioned, when the modification of my invention is practiced which includes a preliminary selective alkylation of isoparafllns any one of a number of catalysts may be used, although not under completely equivalent condi'- tions nor with completely equivalent results.

VSome of these catalysts, such 'as concentrated sulfuric acid, appear to be adapted to eiect the Y alkylation only of the isoparafiins in a paraflin mixture. When more active catalysts are used, the temperature and reaction times can be so correlated, and adjusted by trial for specific instances, that substantially no normal parafiins enter into the alkylating conditions. In some instances, as with aluminum chloride, the reaction temperature for this selective alkylation step may be well below ordinary atmospheric temperatures. In'any case, the isoparaiilns in the initial .charge stock are generally not completely reacted, 'but are substantially the only parafiinic 70 reactant and are markedly reduced in concen/ tration, atleast to less than 10 percent of the total unreacted paraffin hydrocarbon material. Isoparaffins should be present in the initial charge stock in substantial amounts, preferably 75 and structures are suitable to use in the a1ky1a- 4 more than 25 percent and generally not less than about 15 percent. Adequate concentration steps, such as fractional distillation, may be used to obtain a satisfactory composition for the charge stock.

AfterI the selective alkylation of isoparains, the heavier hydrocarbon material, or alkylate, so produced is readily separated by fractional condensation or distillation, and unreacted parafns are subjected to alkylation in the presence of vhydroiiuoric acid.- When catalysts other than hydrofluoric acid are used in this first step, they should also be separated from the eiliuent, by suitable means adapted to the catalysts used. I prefer to use concentrated hydrouoric acid in this first step, in which case the total eluent of this first alkylation step may be subjected to a single fractional distillation to separate, as a kettle product, the heavier hydrocarbons, and as a lighter overhead product a mixture of unreacted hydrocarbons and hydrofluoric acid, which, if desired, can be passed directly to the second alkylation step.

Reference will now be made to the accompanying drawing which forms a part of this specication, and which illustrates ydiagrammatically pentan'es, and also serves as one example of my invention. However, it will be understood that other charge stocks may be used and products of other boiling ranges produced, with suitable modifications for any particular case as will be readily ascertained, as just discussed.

A parafllnic hydrocarbon fraction, such as a butane fraction from natural gas containing about.30 percent isobutane, enters the system under a suitable pressure such as 20 to 200 pounds per square inch gauge, thru pipe I0 and valve I I, andv is passed to a reaction zone I2 in alkylator I3, such as the tube coil diagrarnmatically shown which is satisfactory for use with a fluid or mobile alkylation catalyst. Such a catalyst, as sulfuric acid, hydrouoric acid, or the like, is passed through pipe I4 and valve l5, and can be thoroughly mixed with the parafflnic stream passing through pipe I0. Olefln'hydrocarbons enter the system thru pipe and manifold I6 and valve I'l, and may be accompanied by Aa certain amount of paraflinic material similar to that passing thru pipe Iii, such as butane. Active churning action with fluid or mobile solid catalysts may be obtained by stirring means in an enlarged reaction zone, or by baiiies, orifices, and the like, in a tube coil of restricted'cross section, whereby the alkylating catalyst and hydrocarbons are intimately intermixed, and churned, as shown in this particular modification, preferably to a sufficient extent to effect emulsification.

^ When a solid granular catalyst'is used, such as sodium chloroaluminate deposited on a solid granular support, it may be used in anelongated catalyst chamber, or in a series of small chambers, as may be desired.

' The oleiins are'addecl to the paraffin stream at one or .more points, as may be desirable, through pipes 20, 2|, 22, and 23, controlled by valves 25, 2B, 21, and 2 8, respectively, which lead to various points in the reaction zone. These olefins may .be produced by dehydrogenation,

` cracking, depolymerization, or polymerization, or

the like, and are ordinarily somewhat diluted I0 at the inlet of the reaction zone.

with saturated material. Thus, when' butenes are reacted with butanes to produce octanes, the butenes may previously be produced by dehydrogenation of butane, and may be accompanied by unreacted butane. At other times, when the oleilns are originally in more concentrated form, such as Vwhen polymers are used or an oleiln concentrate is formed by depolymerization, parafn hydrocarbons such as butane may be deliberately added, if desired. It will be noted that pipe 20 introduces oleiins into the parailin stream immediately before it enters the reaction zonev l2, and at times this may be the only point of addition. Also, when a hydrocarbon material containing a relatively low amount of oleflns is available, such as less than about or 20 percent, this material can be added thru accomplished by passing a portionlpibthe eliluent from pipe 3U thru pipe 33; valve-34, pump 35 and pipe 36 controlled by valve 3l back tov pipe v In any method of oleiln addition it is well to keep the amount of oleiin added low at any one point of olen addition, such as below 10 mol percent of theA total hydrocarbons present, and the oleiin concentration-maintained may sometimes be very low, below l percent, as previously discussed. However, by the practice of my process a large amount of reaction can be secured by continuously adding oleiin to the reacting stream as previously added olefin is consumed, as by a plurality Yof points of addition represented by pipes to 23, inclusive. With such controlled addiwashing, and the like, as may be desired or necessary. Traces of acid, acidic materials, and the like may be removed by suitable treatment, as by contacting with' hotor cold alkali. When a fluid or mobile solid catalyst accompanies the eilluent into separating means 40, it may be removed by suitable means such as filtration, fractionation, centrifuging or the like, dependent `upon the characteristics of the catalyst. A low boiling catalyst may be removed by fractionation thru pipe 43 and valve 44. Unreacted, low boiling paraiins may then be separated thru pipe 41, and are preferably passed tothe second step ofthe process thru pipe 45 and valve 49 to pipe 50, or may be discharged, at least in part, thru valve 48.

It is to be understood that the representation of separating means 4B is diagrammatic, and

will in practice comprise various pieces of fractionating and separating equipment, according to the eflluent material to `be treated. -When solid, stationary alkylation catalysts'are used in the reaction zone I2, the eilluent material will be metal chlorides, is used ltration or similar sep'- arating steps may beincluded. sulfuric acid` .may be readily separated from hydrocarbons by essentially normal paraffin suchvas normal bi1- tane, is passed thru pipe 50 to a reaction zone 52 in alkylator 53, such as the tube coil diagrammatically shown. It may consist of unref acted paraffins from the preceding step, as just described, or when this is not a part. of the process, the paraiiins are added from any suitable source thru pipe 18 and valve 19, passing thru pipes 83 and 'I6 to pipe 50. Concentrated hydroiluoric acid, preferably between 80 and 100 percent hydrofluoric acid, is added as needed thru pipe 54 andvalve 55, to be thoroughly mixed with the parain-ic stream passing thru pipe 50. The total amount ofv,hydrofluoric acid present in the reaction zone 52 should be such that, when the subsequent reaction takes place in liquidphase as will most often be the case,

. the liquid hydrocarbon material is substantially saturated with hydrogen iluoride, and preferably aboutA 10 percent or more of the total mixture is hydrouoric acid. Olen hydrocarbons enter the system thru pipe and manifold 56 and valve 5l,

v other treatment, such as fractionation, caustic principally a hydrocarbon mixture easily separated by fractional distillation. mobile catalyst, such as certain nely divided and maybe accompanied by a certain amount of paranc material similar to that entering thru pipe 50,.su-ch as butane. Active churning action may beobtained by stirring means in an enlarged reaction zone, or by baies, orices, and the like, in a tube coil of restricted cross section, whereby hydrouoric acid and hydrocarbons' are intimately: intermixed, 'and churned, as is shown in this particular modication.

'I'he alkylation of normal parailns in reaction zone 52 may be carried out in a much similar manner to that just described in connection with the reaction zone l2, especially when hydrofiuoric acid is used as the alkylation catalyst in zone I2. Thus olefins may be added to the reacting stream at one or more points, as matr be desirable, through pipes 60, 6I, 62, and 63, controlled by valves 65, 66, 67, and 68, respectively. which lead to various points in the reaction zone. Theseolens may be produced by dehydrogenation, or the like, as previously set forth. Thus, when butenes are reacted with y addition. Also, when a hydrocarbon material containingk a relatively low amount of olens is available, such as-less than about 15 or 20 percent, this material can be addedthru pipes 5U or 56 as the sole charge to the process. Such a. modification is preferably used in connection with a recirculation of a part or portion of the eiliuent of the reaction zone passing thru pipe 10. Such a recirculation is accomplished by passing a portionof ythe efiiuent from pipe 10 thru pipe 13, valve 14, pump 15 and pipe 16 controlled byvalve 11 back to pipe 50 at the inlet of the reaction zone. In any method of olen addition it is well to keep the amount of oleiin added low at any one point of oleiin addition, such as below 10 mol percent of the total hydrocarbons present, and the olefin concentration maintained may sometimes be very low, below 1 percent, as previously discussed. However, by the practice of my process a large amount of reaction can be secured by continuously .adding olen to the reacting stream as previously added olefin is consumed, as by a plurality of points of addition represented by pipes 60 to 63, inclusive. With such controlled addition of olefins, the reaction time may be somewhat extended to produce a substantial total yield.

-At reaction temperatures of about 150 to 300 F., which ordinarily are suitable for the alkylation of normal paraiiins such as normal butane and normal pentane, -the reaction time should preferably not be less than about 5 minutes, and with very small amounts of olefin addition, and reaction temperature in the lower` part of the range indicated, they may be as much as 3 hours or more. Generally, a` satisfactory time will be found between 15 minutes and 2 hours for such materials.

The reaction eiiiuent, comprising primarily paraiiins and hydrofluoric acid, passes thru pipe and valve 1| to fractionating means 80,- wherein a separation is made between the product, or alkylate, and lower boiling material, comprising predominantly unreacted parans and hydrouoric acid. The alkylate is withdrawn thru pipe 8| and valve 82, and may be subjected to such other treatment, such. as fractionation, caustic washing, and the like, as may be 'desired ,or necessary. 'Iraces of the acid and of alkyl fluorides may be removed by suitable treatment, as by contacting with hot or cold alkali. The fractionating means 80 is diagrammatically represented as a single fractionating column, which is to be supplied with suitable bubble trays or the like, heating means for the bottom and cooling means for the top, as is well known in the art, but which are not shown. However, if necessary or desirable, the fractionating means may comprise two or more fractionators and their auxiliary equipment, as will be readily understood. Lower boiling material is removed thru pipe 83, and may be returned entirely or in part directlylto the reaction zone thru valve 84 for further reaction.

More often, however, it will be desirable to sub- :lect at least a part of this material to further treatment, and in such an event all or part o! the stream is passed frompipe 88 thru pipe 85, cooler and condenser 86, pipe 81 and valve 88 to separator 60. 'I'he pressure prevailing in the system at this point is appreciably above atmosuoric acid to 4take place.v Generally, ordinary 75 cooling water will provide sunicient cooling, and if the pressure is not suilicient at this temperature to result in a condensation, it maybe boosted by a compressor, not shown, in pipe 85. .Hydroi'luoricacid is withdrawn through pipe 9|, and may be discharged thru valve 92. Any portion of this material may be returned to the reaction thru pipe 93, and valve 94, passing to pipe 54, and generally a substantial portion is so recycled.

A hydrocarbon fraction, still containing a minor amount of dissolved hydroiiuoric acid, but comprising principally unreacted butane is removed from separator 90 thru pipe 95, and may be discharged thru valve 96. However, it will generally be desirable to subject this material to further treatment, and any part or all of it is then passed from pipe thru pipe 91 vand valve 98 to fractionating means |00. Again, this may be a simple fractionating column, with suitable bubble trays, heating means, and cooling means, not shown, or may be a combination of two or more fractionators and/or separators. A paraiiin hydrocarbon material, such as butane, is recovered in a substantially pure state as a kettle` product, which is removed thru pipe |0|,- and may be recovered for further use or treatment thru valve Y |02. In most-cases it will be desirable to recycle `directly at least a substantial portion of this material, and such a portion is passed from pipe I0| thru pipe |03 and valve |04, to pipe 50 and on to the reaction zone. .Wth the previous removal of the majorpart of the hydroiiuoric acid as a liquid thru pipe 9|, only minor amounts will remain in the hydrocarbon stream passing thru pipe 95. In such low concentrations in the charge Vto fractionating means |00,'it can be made to pass overhead thru pipe |05, even in the presence of some lower boiling hydrocarbons, as a part of an azeotropic mixture, leaving substantially pure hydrocarbons in the kettle to be Withdrawn thru |0| as discussed. The vapor fraction, which contains appreciable quantities of hydroiiuoric acid, is removed thru pipe 05, cooler and condenser' |06, pipe |01 and'valve |08 to separator I0. The cooling in.,|06 is suiilcient to cause a condensation of hydrouoricv acid and a separation of a major part of it from the hydrocarbon material as a separate heavy liquid phase, which iswithdrawn thru pipe H5, and may be either returned to the system thru pipe ||1 and valve ||8, and pipe 54, or removed in part, or entirely, thru valve H6. The light hydrocarbon material, which will contain only a small amount of hydrouoric acid, is removed from separator ||0 thru pipel20, and is preferably returned to fractionating meansl |00 thru pipes and 91, and valve ||2. It desired, a part may be recirculated thru valve |23.,

With this preferred arrangement, a state of equilibrium can be reached whereby even relatively light hydrocarbons can be recovered from the kettle product ofi'ractionating means |00, and removed thru valve |02, with substantially all of the hydroiluoricacid being recycled thru pipes 83 and ||1, and such a mode of operation forms a modication oi' this invention. However, if desired a part, or all, of the material passing thru pipe |20 may be removed from the system thru valve |2|. If the hydrouoric acid content renderstthis material diiiicult to handle or undeslrable to let free, it may be treated m scrubber |26 by being passed thru pipe |24 and valve |25. Water, or an alkali solution such as sodium hydroxide, or the like, is introduced thru pipe |21 and valve |28, and is used to wash the hydrocarbon stream entering thru pipe |24. Purified hydrocarbons are removed thru pipe |30 and valve' |3|, while the wash liquid is removed thru pipe |32 and valve |33. If desired, a part or all of the stream passing thru pipes 95 and 91 may be sent to scrubber |26 thru pipe ||3 and valve I4.

It will be understood that the ow diagram presented and described herewith is schematic only,

' and that many additional pieces of equipment,

such as pressure gauges, valves, -ow meters, pumps, heat exchangers, controllers, reflux accumulators, reux lines, and the like, will be necessary for any particular installation, and can be installed by anyone skilled in the art. However; the essential equipment and material iiow have been described in suiiicient detail to serve as an eilicient guide. Alkyl fluorides, which may be found 'in minor amounts, generally will accompany the alkylate product. They may be sepay 7 dominant fraction consist oi heptanes formed by the reaction and over 80 percent of the reaction product was in the present daygasoline boiling range. was over 98 percent saturated, and had a well balanced distillation range.

Est-'ample II As an example of the 'operation of a modification of my process using two differentcatalysts,

a butane fraction from a natural gasoline plant,

rated therefrom by any desirable means, as by .I

caustic alkali treatment, solvent extraction using an alcohol, or other suitable means. While itpwill generally be more desirable to conduct my invention in a continuous manner, some part or all of it may, of course, be conducted by batches.

Example I As an example of the practice of my invention,

a mixture of substantially anhydrous hydrouoric acid and normal butane was charged to a reaction chamber which was maintained at a temperature between 215 and 225 F., and under a pressure between 400 .and 500 pounds per square inch'. The initial ratio of the volume ofv liquid normal butane and liquid hydrouoric acid was about 2:1. To this mixture in the reaction zone was added a mixture of normal butane and propylene over a period of about 80 minutes while the entire mixture in the reaction zonewas continuously agitated to eiect an intimate mixing and emulsification of the liquid hydrouoric acid with the liquid hydrocarbon reactants. In order to insure reaction, the reactants were maintained under the reaction conditions for an additional period of-about 4 hours, although it laterA appeared that, such an extended reaction period was not necessary. 'I'he mol ratio of total normal butane to total propylene added was about 2.7:11 The reaction products were cooled, the 'major part of the hydrouoric acid was Vseparated as a heavy liquid, unreacted light hydrocarbons were separatedby vaporlzation, and .the

liquid hydrocarbon product was subjected to Although the'extended reaction period induced` somewhat extensive secondary reactions, the precontaining about 35 percent by volume of isobutane, may be reacted with a butane-butylene fraction, produced by dehydrogenation over black unglowed chromium' oxide deposited on bauxite, of a similar butane fraction. The rst alkylation reaction is carried out', in the presence of an equal volume of 98 percent sulfuric acid at a temperature of about F. and a pressure of 50 pounds v per square inch gauge with vigorous agitation to produce`a saturated product of which over 80 A percent boilsbelow 400 F. From the. eilluent of the reaction zone is separated the sulfuric acid, a part of which is returned for further reaction. The hydrocarbon fraction of the eiiiuent is separated" by simple fractionation into a pentane and heavier fraction, which consists principally of isooctanes and 'which is removed for' further treatment. The butane andlighter fraction, which contains only about 7 percent isobu'tane with the rest being vpredominantly normal butane, is-admixed with an equal volume of hydrouoric acid of a concentration greater than percent. The mixture is passed thru a long tube coil of restricted-cross-sectional area at a lhigh Velocity to insure intimate mixing and emulsiiication of liquid hydroiiuoric acid with.

the liquid lndrocarbon reactants, and olens, predominantly butanes, are added. along the length of the coil, at about 12 points. The temperature is maintained at about 275 F., and the coil is of such a length that the total reaction time is about 25 minutes. The eiiiuent is cooled to about 80 F., the hydrouoric acid separated by settling and returned to the inlet end of the tube coil, and the hydrocarbon iraction is passed thru a sodium hydroxide washer to a fractionating column. The unreacted butanel fraction is separated and is suitable for catalytic dehydrogenation to produce olefins for further alkylation. The product boiling in the motor fuel range is over 96 percent saturated, and has a predominant portion of octanes along .with appreciable portions of lower boiling paraiiins which have been formed by secondary reactions and which give the product a balanced distillation range. 1

Many modications and variations of this invention may obviously be used, and can 'be` adapted by one *skilledv in the art without departing from the spirit of the disclosure. The 're-l strictions used in the-examples, and in connection with the drawing, need not necessarily be used as limits for any particular operation or set of conditions, as they are presented illustrative examples,

I claim:v

1. A process for' synthesizing hydrocarbons, which comprises reacting in liquid phase at a temperature of at least F. a low boiling normal parain liqueable at said temperature and anoleiin in the presence of an alkylatlng catalyst consisting essentially ot liquid concentrated primarily as hydroiluorlc acid under superatmospheric pressure and suitable alkylating conditions of temperature and time. n

2. A process for producing a parainic material from lighter normal paraffin and olen hydrocarbons, which comprises simultaneously contacting such a normal paraiiln hydrocarbon and an olefin hydrocarbon with concentrated hydrofiuoric acid as the sole alkylation catalyst at a controlled reaction temperature, and correlating the amount of hydrofluoric acid, the reaction temperature, pressure, and time, and the ing "parain hydrocarbons from lower boiling proportion of olen to paraiiln to eect .alkylation of the normal parafn as the principal reaction of the process, with minimum oleflnf.

polymerization, to produce a heavier parafnic hydrocarbon material.

3. A process for the production of higher boiling parafin hydrocarbons from lower boiling parafn hydrocarbons, which comprises adding to a stream of predominantly low boiling normal paraillns heavier thanethane, maintained at a Asuitable temperature and pressure to effect a1- kylation of said low-boiling normal paraillns, in

the presenceot concentrated hydrofluoric acid, successive small quantities of a monoolen in' ,such amounts that the amount of oleiin added to the mixture at no time exceeds the equivalent of 10 mol percent of the total hydrocarbons present.

4. A process lfor synthesizing hydrocarbons, which comprises reacting under a superatmospheric pressure and in liquid phase at an alkylating temperature of at least 120 F. a low boiling normal' paraffin liqueflable'at said alkylating temperature and an olen in the presence of liquid concentrated hydrouoric acid as the sole i alkylating catalyst, and dispersing said olen in the reaction mixture during said reaction in such a manner that the'content of olens added to the mixture at no time exceeds the equivalent of l0 mol percent of the total hydrocarbons present.

which comprises reacting normal butane with an olefln under alkylating conditions and in the Apresence oran alkylating catalyst consisting essentially of concentrated hydroiluoric acid.

6. A process for synthesizing hydrocarbons which comprises reacting normal pentane with an olen under alkylating conditions and in the presence of an alkylating catalyst consisting essentially o! concentrated hydroiluoric acid.

5. A process for synthesizing hydrocarbons 7. A process for the production of higher boilparafdn hydrocarbons, which comprises adding to a stream consisting predominantly of low-boiling normal paraiilns heavier than ethane maintained at a suitable alkylating temperature in excess of about F. and not greater than 500 -F. under.a superatmospheric pressure and in the presence of concentrated hydrofluoric acid as the sole alkylating catalyst successive small quantilties of at least one olen of not more than ve carbon atoms per molecule in such amounts that the content of loleins added to the mixture at no time exceeds the equivalent of 10 mol percent of the total hydrocarbons present.

8. A process for synthesizing hydrocarbons,

which comprises reacting a normal paraffin heavier than ethane with an olefin under alkylating conditions and in the presence of an alkylating catalyst consisting essentially of concentrated aqueous hydroiuoric acid to produce a parailln hydrocarbon of higher molecular weight.

9. A process for synthesizing hydrocarbons from lower boiling parailln hydrocarbons, under a superatmospheric pressure and in .liquid phase at an alkylating temperature of at least 120 F. which comprises reacting a low boiling normal paraflln liqueable at said alkylating temperature and an oleiln in the presence of liquid concentrated aqueous hydroiluoric acid as the sole alkylating catalyst.

v 10. A process for the synthesis of normally liquid hydrocarbons from normally gaseous hydrocarbons, which comprises adding to a stream containing predominantly normal butane maintained at a superatmospheric pressure of about 400 to 500 pounds per square inch and at an-alkylating temperature between and 300 F. and in the presence of concentrated hydroiluoric acid in an amount between l0 and 50% by weight of the reactants successive small quantities of propylene -ln such amounts that the content of olefin in the mixture at no time exceeds the equivalent of 10 mol per cent of the total hydrocarbons present. 45

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