US2322800A - Conversion of hydrocarbons - Google Patents

Description

F. E. FREY CONVERS ON OF HYDROCARBONS June 29 1943.

Filed Jan. 22, 1940 Patented June 29, 1943 UNITED STATES PATENT OFFICE Frederick E. Frey, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation oi' Delaware Application January 22, 1940, Serial No. 315,063

' s claims. (cl. 19e-1o) This invention relates to the catalytic production of higher boiling hydrocarbons from lower boiling hydrocarbons and more particularly-to the catalytic union ofparamn and unsaturated hydrocarbons in the presence of 4hydroiluoric acid.

Many processes have been proposed for converting low boiling hydrocarbons into higher boiling hydrocarbons, such asl the production of motor fuels and lubricants Vfrom 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 charge stock, such as in weil known thermal and 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 parailin hydrocarbons, such as thermal conversion under pressure whereby scission of the parafllns 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 oleilns so produced.

This invention relates particularly to the alkylation of paraiiin hydrocarbons to produce alkyl derivatives thereof, or in other words, higher boiling paraiiln hydrocarbons, in the presence of a new catalyst for this reaction, and it also relates to certain preferable methods and process arrangements for alkylating paramns in the presence of this catalyst to obtain high `yields of preferred paraiiin hydrocarbons, or specific parafnic hydrocarbon fractions Vof predetermined boiling ranges and characteristics. I have found that concentrated hydroiiuorlc acid, under conditions to be set forth, will act as a catalyst to effectV a union of unsaturated hydrocarbons with paraln hydrocarbons to form higher boiling `paratlin hydrocarbons. I have further found that it is preferable to use as a catalyst for this reaction substantially anhydrous hydrofluoric acid, or hydrogen iluoride, and that it can be eifectively and safely used over a wide range of temperatures. I have also found that, although metal halide catalysts such as boron triuoride have been used in the presence of appreciable quanti ties of finely divided metallic nickel and hydrogen iluoride to catalyze the reaction of paraillns and olens to form higher boiling parailins, the presence of such other materials as finely divided metals and/or metal halides Ais not necessary for my invention, and thatl I can use concentrated hydroiluoric acid as. a catalyst for the alkylation of parafiin hydrocarbons in the absence of nely divided nickel, metal halides, and the like. Thus, when reference is made hereinafter,

in the specification or in the claims, to concenhave some fortuitous promoting effect, the process has been carried out in the presence of numerous metals without appreciable differences being noted, so that such etiects of gross masses of metal are substantially negligible if at all present.

I t is an object of this invention to produce higher boiling paraffin hydrocarbons by the alkylation of lower boiling paraiiins in the presence of hydrouoric acid.

Another object of this invention is to use hydrofluoric acid as a catalyst in alkylation reactions involving only aliphatic hydrocarbons.

Stili another object of my invention is the conversion of low boiling isoparaillns to higher boill ing isoparaillns by alkylation with unsaturated hydrocarbons in the presence of concentrated hydrofluoric acid. e

A further object of this invention is to establish a process wherein synthetic conversion stocks composed of hydrocarbons of simple and controlled composition can be converted in the presence of concentrated hydrouoric acid to produce a param-nic liquid fraction having especially de` sirable 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 paramns with olens in the presence of substantially anhydrous hydrofiuoric acid to produce various simple branched paraiiins of a single species or a mixture of simple composition within a wide range of boiling points orvolatilities.

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

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

Catalysts which effect the alkylation of parailins 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 as sodium chloroaluminate, and concentrated sulfuric acid, a strong oxygen-containing, polybasic acid. However, these and similar catalysts have one or more rather distinct 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. 'I'hus aluminum chloride, boron carbon material substantially in liquid jliquid phase which may be maintained process at temperatures between about and y 300 or 400 F. For 'readily reacted paramn hydrocarbons, such as isobutane or isopentane, I may readily effect an alkylation at a temperature between about 35 and ,100 F., while for less reactive paraflins higher temperatures are necessary or more desirable. The use of hydroiiuoric acid disadvantages. While apparently it does not form l such denite intermediate compounds with olefin hydrocarbons as dovvarious metal halides, there apparentlyl is associated with its use a formation of various organic compounds, which after a time render the acid much less active, so that sulfuric acid which contains only 10 or 15 per cent of such organic material must bereplaced with fresh, uncontaminated acid. Sulfuric acid is also a powerful oxidizing agent, so that it can not be used at temperatures much above about 100 to 125 F. I without too extensive deleterious side reactions that consume both sulfuric acid and valuable organic material. 'I'he spent acid can be partly reclaimed by more or less elaborate chemical means such as hydrolysis with water, removal of the oils thereby released. and reconcentrating by distilling out the water.

Concentrated hydrofluoric acid, when used as` an alkylating agent for the alkylation of paraiiin hydrocarbons, apparently does not possess V these deleterious characteristics. It is essentially a non-oxidizing and non-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 per cent by weight, the other material being water, and I have found that substantially 100 per cent hydroiiuoric acid, that is, substantially or completely anhydrous hydrofiuoric 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 hydrophase; efflcient 'reaction results when sufficient hydroiiuoric acid is employed to result in a substantial saturation of the liquid hydrocarbon material with hydrogen fluoride, and preferably sumcient hydrogen fluoride is used to form a separate fled or intimately mixed with the hydrocarbon while reaction takes place. In most cases the hydrouoric acid charge should be at least 10 per cent of the total charge, on a liquid volume basis, and hardly ever need exceed 50 or 60 per cent, though more can, at times, be used. In the concentrated form, hydrofluoric 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 reactionsmay produce minor amounts of inorganic iluorides but, as previously discussed, insofar as this invention is concerned hydrofluoric acid is considered to be used in the substantial absence of added metals or metal halides. The reaction temperaturemay be varied over a, wide range' for any particular reaction mixture, but appears to be most dependent upon the parafiin hydrocarbon participating in the reaction. Thus, in general, I may carry out an alkylation emulsiboiling isoparaiiin such as isobutane, isopentane,

or isohexane), concentrated hydroiluoric acid, and an olefin hydrocarbon is maintained at a reaction temperature, a union takes place between the paraiiin and the olen to form a higher boiling parafn which generally represents the 'sum-of the original parailln and olefin not only as to molecular weight but also as to molecular structure. Butanes are ordinarily too light to be included in most motor fuels in appreciable quantities, so that they will form the usual paraiiinic reactants. While pentanes are present in most motor fuels in appreciable proportions, itv will at times be desirable either to utilize excess pentanes or produce a fuel of very low volatility and pentanes, or heavier paraiiins, may be used asreactants in such cases. Highly branched isooctanes can be produced either by alkylating isobutane with butylenes or by alkylating isopentane with propylene, While highly branched isononanes will result from the alkylation of isopentane with butylenes and will have low vola as 30 to 50 mol per cent, or more, of the total mixture, is reacted in the presence of concentrated hydrofiuoric acid, the-molecular weight of the hydrocarbon-product tends to be higher than would result if the same ainount of olefin and paraffin Were reacted by adding small amounts or -portions of olefin to a predominantly paraflinic mixture in the presence of hydrouoric acid, while allowing reaction to take place between and during the addition of oleiins. While it seems that, in many instances with various particular olefin and paraflin reactants, some type of olefin-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 per cent--and is dilcult to determine experimentally as to amount, more lower `molecular weight products generally result, especially with the more reactive olens, if highmomentary concentrations of olefins 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 ofthe reaction, heat should be removed as it develops. It

is, of course, possible to produce a parainic product when the total charge stock contains more than 50 mol per cent of,olens. When there is a high initial concentration, such as first mentioned, it appears that in some cases a certainv amount of polymerization first takes place, whichy 'lhe ultimate result is somewhat similar in both cases but not always the same.

It has, therefore, been found to be quite desirable toy supply-smalll amounts of 'olei'ins as these arc-consumed. When separatestreams of parainns angl oleiins are available, this canvbe v accomplished in a continuous process by dispersing olefins in the reacting stream as reaction progresses, as by adding ,olefins at a plurality of A reaction zone, using it to dilute the incoming charge stock. When this latter modification is used, a portion, or portions, of the charge stock may be added at various points along the course of the reacting stream, thus reducing the amount of the recycle stream necessary to maintain an initial low concentration. In these modifications opportunity should, of course, be provided for abstraction of heat as reaction proceeds, and before further olefin addition. I have found that the most desirable results are obtained when the amount of olefin added to any particular part of the reacting mixture is not greater than about mol per cent of the total hydrocarbon material present, at the immediate zone of addition. Thus, in a continuous operation, wherein an olefin-containing stream is added at a point or zone of introduction to a parafllnic stream, this is to mean that the amount of olefln in this olefincontaining stream does not exceed the specified mol per cent of this stream plus the reactant stream. A suitable time for reaction, and ab straction of heat, should be allowed before again adding olefin, and generally 50 to 75 per cent or more of the olefin previously added should be allowed to react before additional olefln is added. When reacting some parailin and .olefin mixtures, especially those containing less reactive olefins, olefin consumption reactions are not so rapid and somewhat higher olefin concentrations may be maintained in the reacting stream without resulting in too great an increase in the proportion of products of higher molecular weights. When the charge stock is especially reactive the added olefins may need to be kept as low as 1 or 2 per cent `for any particular point or zone of olefln introduction, but generally satisfactory conditions will be found when the added oleilns are between 2 and 8 per cent of the total stream. When an easily polymerizable olefln, such as isobutylene, is one of the principal olefln reactants, or when the process is carried out at elevated temperatures with somewhat less reactive paraiiins, such as temperatures between about 125 and 300 F., it will generally be desirable to add only small amounts of olens at any one point, with a substantial amount of recycle and/or many points of olefln addition.

Olefins over a wide range of molecular weights and structures are suitable to use in the alkylation of paralns in the presence of concentrated hydroiluoric acid. One of the principal cornmercial applications of my` invention at present is the production of paraiiln hydrocarbons in the motor fuel range from lower boiling hydrocarbons, and for this reason olefins of five or fewer carbon atoms per molecule are more often preferred. Of these, ethylene enters into reaction least readily, especially in the absence of olenns of imm-e 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 Cr hydrocarbons in a final product for reasons of volatility, or a high boiling fuel of low vapor pressure may bedesired. so that it will not beunusual touse pentenes. Hexenes, heptenes, octenes, and the like are more often o f greater value as they are, although they are not to be excluded in the broadest concepts of this invention. Cylcoolefins, such 'as cyclopentene, cyclohexene, and

v the like, also enter into reaction as ordinary aliphatic olenns. Ordinarily the process is 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 number of molecules, a certain amount of pressure favors the reaction. However, since the re-` actants are generally readily maintained in liquid phase with only moderate pressure at reaction temperatures in the lower part of the range indicated, only sulilcient 'pressure to insure liquid phase operation is generally adequate. When higher reaction temperatures are used, higher pressures may also be used, and pressures asv high as 1500 or 2000 pounds per square inch or more may be used, if desired. While such high pressures favor reaction, lower pressures are generally successfully used with the pronounced activity of hydroiiuoric acid to induce the alkylation reaction. Since very moderate temperatures usually suffice in the presence of hydroiluoric acid, for thermodynamic reasons the pressure can, accordingly. be moderate and can, of course. be as low as can be shown by trial to permit effective alkylation. In most instances the process `will be operated under a pressure between 20 and 500 pounds per square inch.

The reaction period, during which olefin is introduced, reacted and consumed to produce eventually an isoparamnic product, is dependent to acertain extent upon the reaction temperature and the total amount of olefins reacted. A l

limits within which others may be varied arev somewhat restricted. The more desirable ranges for ordinary applications of my invention have been indicated, and can also be ascertained f from 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.

Reference will now be made to the accompanying drawing which forms a part of this specification, and which illustrates diagrammatically by means of a flow sheet one arrangement of apparatus suitable for practicing my invennen. 1t win be described as a specme embodiment for the production ot parail'inic hydrocarbons in the boiling 'range of motor fuel from butanes and/or pentanes, and also serves as 62e example of my invention. However, it will e be vunderstood that other 'charge stocks may used and products of other boiling ranges produced, with suitable modications for any particular case as will be readily ascertained, as Just discussed.

In this particular application of my invention..

a parailinic hydrocarbon material, such as a butane fraction from natural gas containing a substantial proportion of isobutane, enters the system under a suitable pressure, such as 20 to 200 pounds per square inch gauge, thru pipe I in alkylator I3, such as the tube coil diagrammatically shown. Concentrated hydroiluoric acid, preferably between 80 and 100 per cent hydrofluoric acid, is passed thru pipe I4 and valve I5, and is thoroughly mixed with the paramnic stream passing thru pipe I0. This stream should vbe in such amount that, when the subsequent reaction takes place in liquid phase as will most often be the case, the liquid hydrocarbon material is substantially saturated with hydrogen iuoride, and preferably about per cent or more of the total mixture is hydrouoric acid. Olefln hydrocarbons enter the system thru pipe and manifold I6 and valve I1, 'and may be accompanied by a certain amount of paraillnic material similar to that entering thru pipe I0, such as butane. Active churning action may be obtained by stirring means in an enlarged reaction I and valve II, and is passed to a reaction zone I2 asaaeoo yield. At reaction temperatures of 40 to 100 F.,

which ordinarily are suitable for the -alkylation of paraillns such as isobutavnve, a reaction timeshould preferably not be less than 5 minutes,

and with very small amounts of olefin addition, and low temperatures, may be as much as 3 hours or more. Generally a satisfactory time will be found between minutes and 2 hours for such materials.

The reaction eiiluent, comprising primarily paramns and hydroiiuoric acid, passes thru pipe and valve 3i to fractionating means 40, wherein a separation is made between the product, or

' alkylate, and lower boiling material, comprising predominantly unreacted parailins and hydroiluoric acid. The alkylate is withdrawn thru pipe 4I and valve 42, and may be subjected to such other treatment, such as fractionation,

`caustic washing,`and the like, as may be desired or necessary. Traces of the acid and of alkyl fluorides may be removed by suitable treatment,

zone, or by bailles, orifices, and the like, in a tube coil of restricted cross section, whereby hydrofluoric acid and hydrocarbons are intimately in- I termixed, and churned, as is shown in this par ticular modification.

The olefins are added to the paraffin stream 2f .at one or more points, as may be desirable, thru pipes 2U, 2l, 22, and 23, controlled by valves 25, 26, 21, and 28, respectively, which lead to various points in the reaction zone. These olefins may be produced byvdehydrogenation, cracking, depolymerization, or polymerization, or the like, and are ordinarily somewhat diluted 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 oleins are originally in more concentrated form, such as when polymers are used or an oleiln concentrate is formed by depolymerization, parailin hydro-v carbons such as butane may be deliberately added, if desired. It will be noted that pipe 2Il introduces olens into the paraflin stream irnme diately before it enters the reaction zone I2, 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 15`or 20 per cent, this material can be added thru pipes I0 or I6 as the sole charge to the process. Such a modification is preferably used in connection with a recirculation of 4a part or portion of the elu'ent of the reaction zone passing thru pipe 30. Such a :recirculation is accomplished by passing a portion of Vthe elliuent from pipe 30 thru pipe 33, valve 34,

as by contacting with hot or cold alkali. 'I'he fractionating means 40 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 43, and may be returned entirely or in part directly to the reaction zone thru valve 44 for further reaction.

More often, however, it will be desirable to subject at least a part of this material t'o further treatment, and in such an event all or a part of the stream is passed from pipe 43 thru pipe 45,

cooler and condenser 46, pipe 41 and valve 48 to separator 50. The pressure prevailing in the system at this point is appreciably above atmospheric, a-pressure of the order of 30 to 150 pounds per square inch gauge is effective, and the cooler and condenser 46 is operated so as to reduce to liquid condition both hydrocarbon and hydrofluoric acid and permit a separation of liquid hydrocarbons from the denser liquid hydrouoric acid to take place. Generally ordinary cooling water will provide suilicient cooling, and if the pressure is not suflcient at this temperature to result in a condensation, it maybe boosted by a compressor not shown in pipe 45. Hydrofluoric acid is Withdrawn through pipe 5I, and may be discharged thru valve 52. Any portion of this material may be returned to the reaction thru pipe 53, and valve 54, passing to pipe I4, and generally a substantial portion is so recycled.

A hydrocarbon fraction, still containing a minor amount of dissolved hydrouoric acid, but comprising principally unreacted butane is removed from separator 50 thru pipe 55, and may be discharged thru valve 56. 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 55 thru pipe 5l and valve il to fractionating means 60. Again, this may be a simple fractionating column, with suitable bubble trays, heating means, and cooling means, not shown, or may be a combination oftwo or more fractionators and/or separators. A paramn hydrocarbon material, such as butane, is recovered in a substantially pure state as a kettle product, which is removed thru pipe il, and may be recovered for further use or treatment thru valve 82. In most cases itwill be desirable vto recycle directly at least a substantial portion of this material, and such a portion is passed from pipe Il thru pipe i3 and valve 84, to pipe Il and on to the reaction zone. With the previous ren may often be desirable to retain at least a part moval of the major part of the hydrofluoric acid.

as a liquid thru pipe 5|, only minor amounts will -remain in the hydrocarbon stream passing thru pipe 55. In such low concentrations in the charge to fractionating means 60, it can be made to pass overhead thru pipe 65, 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 Il as discussed. 'I'he vapor fraction, which contains appreciable quantities of hydrofluoric acid, is removed thru-f pipe 85, cooler and condenser 68, pipe 61 and valve 88 to separator 10. The cooling in 68 is sumcient to cause a condensation of hydroiluoric acid and a separation of a major part of it from the hydrocarbon material as a separate heavy liquid phase, which is withdrawn thru pipe 15, and may be either returned to the system thru pipe 11 and valve 1l, and pipes 63 and I4, or removed in part, or entirely, thru valve 16. The light hydrocarbon material, which will contain only a small amount of hydrotluoric acid, is removed from separator A 'I0 thru pipe 80, and is preferably returned to fractionating means B0 thru pipes l2 and 1I, and valve l2. If desired, a part may be recirculated thru valve 83.

With this preferred arrangement, a state oi" equilibrium canbe reached whereby even relatively light hydrocarbons can be recovered from the kettle product of fractionating means 60, and

' removed thru valve 82, with substantially al1 of the hydrouoric acid being recycled thru pipes 53 and 1l, and such a mode of operation forms a modification of this invention. However, if desired a part, or all, oi.' the material passing thru pipe 80 may be removed from ythe system thru valve 8 l. If the hydrofluoric acid content renders this material diiilcult to handle or undesirable to let free, it may be treated in scrubber li by being passed thru pipe 84 and valve 85. Water,

or an alkali solution 'such as sodium hydroxide, or the like, is introduced thru pipe l1 and valve Il. and is used to wash the hydrocarbon stream entering thru pipe 8l. Puried hydrocarbons are `removed thru pipe A9|! and valve 9|, while thev l wash liquid is removed thru pipe 92 and valve 93.

If desired, a part or all of the stream passing thru pipe I5 may be sent to scrubber $6 thru pipe 1 and valve 14.

It will be understood that the flow diagram presented and described herewith is schematic only, and that many additional pieces of equipment, such as pressure gauges, valves, flow meters, pumps, heat exchangers, controllers, reilux accumulators, reflux lines, and the like, will be necessary for anyparticular installation, and can be installed by anyone skilled in the art. Howof the unreacted isoparaflin in the product. This can be accomplished, as desired, by a proper control and operation vof fractionating means 4I.

Substantially anhydrous hydroiluoric acidhas the added advantage that it boils below the usual motor fuel range, and this fact, coupled with the fact that it can be heated in the presence oi' hydrocarbons without entering into oxidizing or reducing reactions, enables it to be readily separated by distillation from the paraillnic product, l and recycled to the reaction zone along with low boiling unreacted parainns. Alkyl iiuorides, which may be formed in minor amounts, generally will accompany the alkylate product. They may be separated therefrom by any desirable means, as by solvent extraction using methyl or ethyl alcohol. While it will generally be more desirable to practice my invention as a continuous process, it'will, of course, be understoodthat at times it may be practiced as a batch process aswell.

Example I A liquid mixtureof isobutane and substantially l anhydrous hydrofiuoric acid in a volume ratio of 1.2:1 was maintained in a steel bomb at atemperature of about 60 to 70 F. While the liquid mixture was vigorously stirred, a mixture of isobutylene and isobutane, containing 68 per cent isobutylene, was slowly added, the total addition time being 15 minutes, after which agitation of the mixture was continued for about 50 minutes. A suilicient amount of isobutylene and isobutane wasadded to make the total mol ratio of isobutane to isobutylene about 3:1, although at no time did the actual concentration of unreacted isobutylene approach this ligure. After the reaction, most of the unreacted light hydrocarbons and some unreacted hydroiluoric acid were removed from the ei'iluent by distillation, and the normally liquid residue was washed with water and a sodium hydroxide solution. The combined From this distillation it can `be seen that a large portion of the productconsists of isooctanes, this simple product being formed in large amounts with a relatively large amount of butane in the charge stock, according to the equation It is also readily seen that the product is aliphatic and saturated, and that the entire product is well suited for use in an internal combustion, spark ignition, engine.

Example Il I claimi Aj= 1. A process for the production of fa normally Vliquid parailinic hydrocarbon material, which comprises reacting a low boiling isoparailn with an oleiin in the presence of substantially anhy drous hydrofiuoric acid as the effective alkylation catalyst to form normally liquid paraflln hydrocarbons, passing at least aA portion of the eilluent volume ratio of 1.421, was vigorously stirred in v an iron reaction chamber, which was not attacked by the hydrofluoric acid. To this mixture was added propylene over a period of about 30 minutes. The reaction temperature during this period was between about '70 and 80 F., and the pressure was allowed to be the vapor pressure of the reacting mixture, which never exceeded 50 pounds per square inch gauge. The mol ratio of total isobutane to total proplene added was 2.2zl, but was always appreciably greater than this during the reaction period. After addition of propylene the mixture was maintained in the chamber with continuous agitation for 45 minutes more, during which the temperature fell to 65 F. and the pressure decreased to about 40 pounds per square inch gauge. The high residual pressure was presumably due to some propane, which was present in the propylene and which was not appreciably reacted under these conditions. 'Ihe total yield of liquid product was about 150 per cent based on the propylene lreacted, and was' separated by fractional distillation into fractions which had the following properties:

Fraction Biggs? Density 112@ Urggg Volume F. Percent Percent Total product. 0. 7026l l. 3970 30 100 0 HF 041110+03115 C1Hie and that 12.4 per cent consisted of isodecanes to fractionating means, separating as a liquid .from said fractionating means liquid parains so produced, separating as a gas from said fractionating means a mixture comprising unreacted hydrocarbons fand hydroiiuoric acid, cooling and condensing at least a portion of said gas mixture tocondense and separate as liquids hydrocarbons and hydroiluoric acid, separating said hydroiiuoric acid as a heavy liquid from a lighter hydrocarbon liquid land returning said hydroiiuoric acid to the aforesaid reaction, subjecting said lighter hydrocarbon. liquid to a fractional dis'- tillation to separate a hydrocarbon material substantially uncontaminated withhydrouoric acid as a liquid kettle product and removing at least a portion thereof from the system, passing as a gas from said fractional distillation a mixture comprising hydrocarbons and hydrofluoric acid, cooling and condensing said gas mixture to condense and separate as liquids hydrocarbons and hydrofluoric acid,` separating said hydrouoric 4acid as a heavy liquid from a lighter hydrocarbon fluid and returning said hydroiluoric acid to the aforesaid reaction, and returning at least a portion of said hydrocarbon fluid to said fractional distillation.

2. A process for producing parain hydrocarbons in the motor fuel boiling range from lower boiling isoparaiins and oleflns, which comprises subjecting a mixture comprising such a low boiling isoparafiin and an oleiin of three to ve carbon atoms per molecule in a reaction zone to the action of concentrated hydrofluoric acid as the eiective alkylation catalyst to alkylate said isoparailin with said olefin to produce normally which were presumably formedby the reaction f The presence of other products is probably due to secondary reactions which are not clearly understood at this time, but which also appear to produce parainic products. Over 90 per cent of the total product was in the present day 4gasoline boiling range, and possessed good motor fuel properties.

- liquid parains in the motor fuel boiling range,

passing the eiiluent to fractional distillation means and separating and recovering said normally liquid hydrocarbons so produced as a liquid from 'a vaporized mixture of unreacted hydrocarbons and hydrofluoric acid, cooling and .condensing at least a portion of said vaporized mixture to condense as. liquids hydrocarbons and hydroiluoric acid, passing the condensed mixture to separating means, removing from said separating means a heavy liquid comprising hydroiiuoric acid and returning at least a portion of the same to said reaction zone, and removing also from said separating means a light liquid comprising unreacted hydrocarbons.

3. .A process for the production of higher boil-lv ing hydrocarbonsl from lower boiling paraffin hydrocarbons, which comprises passing a stream of predominantly alkylatable parafnic hydrocarbon material in which olefinic material is dispersed at an alkylation pressure and temperature and in admixture with an alkylation promoting amount of concentrated hydrouorlc acid v yat a point of oleiln dispersal does not exceed the equivalent of aboutv 2 mol per cent of the hydrocarbons present, removing heat from said reaction zone during said reaction time by means of said heat absorbing medium to maintain a v relatively constant alkylation temperature, passing a liquid mixture eiliuent from said reaction zone and containing a hydrofluoric acid phase and a hydrocarbon phase to separating means, separating said hydrofluoric acid phase and returning atleast a portion thereof to said reactionl zone, separating also said hydrocarbon phase containing'dissolved hydrofluoric acid, passing charged and in such a manner that the concensaid hydrocarbon phase to a fractional distilla- A tion means, separating from said means a vaporous fraction comprising all said dissolved hydrofiuoric acid and a low-boiling paraflinic hydrocarbon, cooling and condensing said vaporo'us fraction to form a liquid hydrocarbon phase and a liquid hydroiluoric acid phase, separating and returning said hydrocarbon phase to said distillation means, and recovering also from said distillation means a liquid hydrocarbon fraction essentially free of hydrofluoric acid and containing higher boiling paraffin hydrocarbons sov produced.

4. A processfor separating a hydrocarbon fraction substantially free -of hydrogen uoride from a mixture containing low-boiling hydrocarbons and hydrogen fluoride, which comprises subjecting said mixture to fractional distillation, separating from said fractional distillation a low-boiling fraction comprising essentially all said `hydrogen fluoride together with only sufficient lowboiling hydrocarbon material to form a minimum boiling azeotropic mixture with said hydrogen fluoride, and separating also from said fractional tion which is essentially free of hydrogen fluoride and ycontaining all of said initial low-boiling 'hydrocarbons in excess of those contained' in said azeotropic mixture.

5. In the process of claim 4, cooling and condensing said low-boiling fraction to form a hydrogen fluoride 'phase and a hydrocarbon phase, recovering said hydrogen fluoride phase, and returning said hydrocarbon phase to said fracdistillationl a higher-boiling hydrocarbon fracthe alkylation catalyst, the improvement which comprises a mixture effluent from said alkylation and containing a liquid hydrogen fluoride phase and a hydrocarbon phase to a phase separating means, separating said hydrogen fluoride phase, passing said hydrocarbon phase to a fractional distillation means, separating from said means a vaporous fraction comprising a mixture of a low-boiling parafilnic hydrocarbon and hydroiluoric acid, cooling and condensing said vaporous fraction to form a liquid hydrofluoric acid phase and a hydrocarbon phase, recovering said hydrofluorlc acid phase, returning said hydrocarbon phase tovsaid fractional distillation, and separating also from said means a liquid fraction comprising a low-boiling Y alkylatable parai'iinic hydrocarbon fraction substantially free from hydrouoric acid.

1. A process for separating a hydrocarbon fraction substantially free of hydrogen iluorlde from a mixture containing low-boilingrhydrocarbons and hydrogen fluoride, which comprises subjecting said mixture to fractional distillation, separating from said fractional distillation a low-boiling fraction comprising essentially all said hydrogen fluoride together with at least sufficient lowboiling hydrocarbon material to form a minimumboiling azeotropic mixture with said hydrogen fluoride, cooling and condensing said low-boiling fraction to form a hydrogen fluoride phase and a hydrocarbon phase, recovering said hydrogen fluoride phase, and returning said hydrocarbon phase to said fractional distillation, and separating also from said fractional distillation a highboiling hydrocarbon fraction which is essentially ing said hydrocarbon phase to said fractional Y distillation, and separating also from said fractional distillation a higher boiling hydrocarbon fraction which is essentially free of hydrogen fiuoridef FREDERICK E. IIF'RE'Y.v

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