US2470144A - Isomerization and alkylation of normal paraffins - Google Patents

Description

Patented May 17, 1949 ISOMERIZATION ALKYLATION OF NORMAL PARAFFINS Louis A. Clarke, Fishkill, N. Y.,' assignor to The 3 Texas Company,-New York, N. ,Y., a corporation of Delaware No Drawing. Application April 10, 1942,

' Serial No. 438,418

Claims. 1

This invention relates to the manufacture of motor fuel hydrocarbons of good anti-knock and other desirable properties-and to the production of isobutane from normal paraflin and olefin hydrocarbons. More particularly, the invention relates to a process for alkylating a normal parafiin hydrocarbon with an olefin and concomitantly isomerizing the normal parafiin hydrocarbon, utilizing a mixed catalyst containing as essential constituents substantially anhydrous liquid hydrofluoric acid and boron fluoride.

A number of catalysts have heretofore been proposed for alkylating an isoparaffin, such as isobutane, with an olefin to produce motor fuel hydrocarbons or alkylate of ,a substantially saturated isoparafflnic character having high antiknock value, such as sulfuric acid, HF, BF3.H2O complex, and the like. None of the above catalysts have been found effective for alkylating a normal paraflin with an olefin, and any normal parafiln present in the hydrocarbon charge remains as a diluent which does not take part in the reaction. U. S. Patent No. 2,217,019 has proposed the use of a catalyst consisting of boron fluoride, nickel, HF and/or water, wherein the- HF is in a minor proportion by weight with respect to the BFa, as a catalyst for promoting the usual alkylation reaction of isobutane with a normally gaseous olefin. This is also described in Journal of the American Chemical Society, volume 57-2, September 1935, pages 1616-1621, wherein it is stated-that a normal paraflin does not take part in the reaction.

It has now been discovered that, by the use 01' a diiferent and critical proportion range of substantlally anhydrous liquid HF were wherein the HF is maintained in excess of the weight of the BFa, a normal paramn can be s'lkylated with an olefin to produce good yields of normally liquid substantially saturated hydrocarbons within the gasoline boiling range having good volatility and boiling point distribution characteristics and other desirable properties including relatively high octane. At the same time, this catalyst functions as an'isomerization catalyst in the presence of the alkylation reaction and a good yield of isobutane, which can be employed for the conventional isoparafiin alkylation operation, is obtained. This is all the more remarkable since the combined catalyst of the present invention is inactive at the temperatures employed herein to effect isomerization of normal parafiins in the absence of a small but effective amount of olefin and the concomitant alkylation reaction; and the constituents of the catalyst employed separately are ineffective at the temperatures employed herein for producing alkylation of a normal parafiin with an olefin.

An object of the present invention resides in producing good yields of motor fuel hydrocarbons and of isobutane from normal paraffin and olefin hydrocarbons. particularly the normally gase us hydrocarbons of the character of normal butane, ethylene and propylene, which are available in large quantities as refinery waste gases and have not found extensive utilization in alkylation, polymerization or other processes for the production of more valuable normally liquid hydrocarbons of the character of motor fuel and aviation gasoline.

Another object of the present invention is to produce from such normal paraflln and olefin hydrocarbons a high-grade blending stock for motor fuel or aviation gasoline, and also substantial quantities of isobutane which can be employed in conventional alkylation processes for the. production of increased. quantities of highgrade alkylate. Other objects and advantages of the present invention will be apparent from the following description and the appended claims.

In accordance with the present invention, a normal paraflln hydrocarbon is reacted with an olefin under alkyiating and isomerizing conditions in the presence of a mixed catalyst consisting essentially of a major proportion by weight .of substantially anhydrous liquid HF and a minor but effective proportion by weight of BF3.

The catalyst may be prepared by introducing a stream of BF: into a body of anhydrous liquid HF maintained under pressure until the desired quantity of BF: has been added. It has been determined that a proportion of BF: by weight which is less than the weight of the HF is critical in efiecting the alkylation and isomerization reactions of normal parafiins of the present invention. 0n the other hand, the presence of more than two mol percent of BF: is essential, and a proportion range of about four mol percent to twenty mol percent of BBB, quivalent to about 14-85% by weight based on the weight of the HF, or 12-46% by weight based on the weight of the mixed catalyst, is generally employed.

Anhydrous HF is a colorless, limpid liquid having a boiling point of 19.4 C. (66.9 F.) a melting point of 83 C. and a density of 0.9918 at 4 C. BF; is a fuming gas having a boiling point at atmospheric pressure of -10l C., a melting point of 127 C. and a density of 2.34 as compared to air which equals one. The temperature and pressure conditions of the present reaction are ordinarily such that the HF is maintained liquid, while the BF; is a gas. However, a substantial quantity of BF; passes into solution in the HF and the hydrocarbon charge of the reaction zone, so

' that the mixed catalyst comprises anhydrous liqof the catalyst may be separately recovered upon release of pressure without substantial loss. While the preferred catalyst is substantially anhydrous, a small amount of water may be introduced with the hydrocarbon charge and picked up by the catalyst without impairing its efficiency, so long as the water content does not approach an amount which will react with .the BF: to form complex and thereby reduce the available or free BE; below the critical range specified above. For purposes of the present description and claims, it is to be understood that a catalyst containing this very small amount of water is included in the expression substantially anhydrous." The catalyst of the present invention is thus distinguished from that which is prepared by adding BF: to an aqueous solution of HF or which contains an appreciable amount of water forming complex with the available BFa.

Both normally gaseous and normally liquid parafiln hydrocarbons of straight chain structure, such as normal butane, normal pentane, normal hexanes and other higher boiling paraffin hydrocarbons within the gasoline boiling range and up to about C1: paraihns, can be employed as the normal paraflin constituent of the charge. Likewise, various mixtures of these hydrocarbons, as well as mixtures of normal paraffin and isoparaflins are suitable. Normal butane is preferred since large quantities are available which are not normally required for blending purposes in motor fuels to impart volatility. A parafiinic naphtha, such as a straight run naphtha, can likewise be utilized with substantial improvement in the volatility and other characteristics of the treated product. Likewise, both normally gaseous and normally liquid oleflns are suitable. The normally gaseous oleflns, namely, ethylene, propylene and the butylenes, are preferred; but low boiling normally liquid mono-olefins and the low boiling olefin polymers, such as selective polymers of the character of di-isobutylene and tri-isobutylene, cross-polymers between isobutylene and normal butylenes, non-selective C3-C4 olefin polymers, and the like, can be employed.

The normal parafiin is utilized in at least an equal molar ratio with respect to the olefin,'and preferably in a substantial molar excess thereof. For example, molar ratios of normal paraffin to olefin of 1:1 to 50:1 and higher are contemplated: and generally a molar ratio in excess of 5:1 and preferably about :1 is used. By recycling emulsion or a portion of the hydrocarbon phase of the reaction products in accordance with conventional isoparaflln-olefln alkylation practice, an even higher ratio at the point of contact of the hydrocarbon feed with the catalyst may he maintained.

Ordinarily, mild temperatures within the range of 0 to 150 F. and above are contemplated, with temperatures of about 70-130 F. being generally preferred. The temperature employed varies with the hydrocarbon charge stocks and the ultimate or main purpose of the reaction. For example, in the alkylation of a normal paraffin with Ca and C4 or higher olefins, a temperature of about 50-90 F. is quite suitable. In the alkylation of a normal paraffin with ethylene, a temperature range of about 70-140" F. is usually employed, and good results have been obtained at as low a temperature as about 70 F. Where isomerization of normal paraflin in the presence of a relatively small amount of olefin constitutes the main reaction, temperatures in the upper portion of the range, for example, 70-150 F., are quite satisfactory. Suilicient pressure is utilized to preferably maintain at least the normal parafiin constituent of the hydrocarbon charge as well as the HF in liquid phase, and to keep the desired quantity of BFs in the reaction zone. The superimposed vapor pressure of the BF: may determine the pressure maintained in the reaction zone which will usually be about -250 pounds per square inch, although this can be varied and both higher and lower pressures employed.

A ratio of catalyst to total hydrocarbons maintained in the reaction zone of about 0.1:1 up-to 2:1 by liquid volume may be employed, with a ratio of about 1:1 by liquid volume usually preferred. A contact time of about 20-120 minutes may be used with about 60-90 minutes generally preferred. The reaction is preferably carried out with eihcient agitation, as by high-speed mechanical stirrer, circulating pump or mixer, and the like, to provide intimate contact between the hydrocarbons undergoing reaction and the catalyst.

The reaction may be carried out either in batch or continuously. In a typical batch procedure, a steel reaction bomb equipped with a mechanically-driven stirrer has been employed. The reactor was charged with the required amount of anhydrous liquid HF and the liquefied normal parafiin. BF; was then introduced as a gas and the stirring mechanism started. The olefin was then charged at a regular rate over the required time interval, usually about sixty minutes, and then the stirring was continued an additional thirty minutes. The contents of the reactor were passed through a caustic scrubber to remove the HF, and then into a stabilizer where the bulk of the gases were fractionated off and collected. The stabilized alkylate was fractionated to note the hydrocarbon boiling range distribution, and generally a 311 F. end point fraction of debutanized alkylate was collected and tested to obtain octane and other pertinent data. The oflgases were generally analyzed by low temperature fractional distillation.

The following are results of typical batch runs carried out in the above described manner with normal butane as the paraflin constituent of the charge and with ethylene, propylene and isobutylene as the olefin constituent:

Table I Run No. l 2 3 4 6 Catalyst:

HF Wt. in g 245 2%) 210 215 m5 BF| Wt. in g 60 50 70 50 65 HO Charge:

520 620 520 500 140 104 104 104 Operation:

Temp., "F -l 100 80 30 74 Olcfln addition time, min 55 55 60 55 143 Additional stirring time, min... 30 30 30 30 30 Stabilized Alkylate:

Volume cc... 465 355 230 294 300 Wt. in g 300 2&0 185 190 Wt. (per cent yield of debutani1e alkylate based on olefin charged 209 145 110 177 C. F. R. M. Mime 79.8 79.6 Oilgas, Wt. in g 300 370 450 420 Per cent less than C4 9.1 22.1 1.0 0.4 Per cent l-Ca 66. 6 44.0 30. 8 42. 6 Per cent 11-04 22. 7 32.0 66.8 54.9 Per cent greater than C 1.7 1.9 1.4 2.1 Per cent lsobutane formed based on olefin- 171 121 n-Butane. I Ethylene. Propylene. Isobutyleue.

The stabilized alkylate obtained in each of the above runs consisted largely of pentanes and hexanes with considerable isopentane. The results show that alkylation is accompanied by fragmentation reactions, resulting in the formation of large percentages of isopentane and hexanes regardless of the olefin charged. At least about 95% of the stabilized total alkylate boiled below 300 F. in all instances, this product having a bromine number of less than 1 showing substantial saturation. As representative of the character and boiling point distribution of the alkylate produced, the following is an analysis of the alkylate obtained in run No. 4:

Pentanes, 37% by volume of which 25% on the volume of the total alkylate was isopentane Hexanes, 27%

Heptanes. 13%

Octanes, 13%

Above octanes,

In all of the runs, with the exception of No. 3, it will be noted that the ofigas contained more than 40% by weight of isobutane; and in run No. 1, with ethylene as the olefin constituent, the isobutane content of the oflgas was 66.5% equivalent to 171% on the basis of the olefin charged. Run No. 3 indicates that the temperature of 30 F. employed was too low for the isomerization reaction to secure high yields of isobutane, although a fair yield of.alkylate resulted. Runs Nos. 3, 4 and 5 give a comparison of operations with normal butane and isobutylene at temperatures of 30 F., 74 F. and 115 F. respectively, and show improved results at the higher temperatures.

The following series of batch runs indicate the eifect of the ratio of HF to BF; in the mixed catalyst. These runs were all carried out in thebatch reactor described above with a normal butane to isobutylene molar ratio of 5:1 and a reactor temperature of 7075 F.t

Run No. 1 shows that HF alone does not promote the alkylation of normal butane with isobutylene. Runs Nos. 2 and 3 show that the minimum efiective concentration of BF; lies between about two mol percent and four mol percent, beneath which neither alkylation to any appreciable extent nor isomerization takes place. The above runs show that the best yield Jf liquid alkylate was secured with about 4-14 mol percent concentration of BF: in the catalyst, while the maximum yield of isobutane was obtained with about 6-19 mol percent concentration of BFa. There was a sharp decline in both the alkylation and isomerization reactions between a BF: concentration of 19 and 30 mol percent.

Where isomerization or the production of isobutane is the primary purpose of the reaction, only a small proportion of olefin on the basis of the normal paraffin charge is used with the HF-BFs catalyst. The following series of runs 6 were made employing normal butane and the olefin polymer di-isobutylene with HF-BFa in mol ratio of 13:1:

The above runs indicate that the highest conversion of normal butane to isobutane is secured with a molar ratio of normal butane to olefin of about 10:1 to 20:1, although substantial yields of isobutane are secured at ratios as high as 43:1. However, it has been found that the HF-BF: catalyst is not effective in isomerizing or producing isobutane from either normal butane or normal pentane in the absence of olefin. About 1-2% of olefin based on the normal parafii'n charge appears to be about the minimum which will produce efiective reaction. This is contrary to previous practice in the isomerization art, where freedom from olefin in the normal paraffin charge was considered a desideratum to avoid catalyst deterioration and provide other advantages. Moreover, it will be noted that the isomerization or production of isobutane occurs in highly effective amount at comparatively low temperatures of the order of about 70-150 F. under the conditions specified with the HF-BF; catalyst, whereas prior practices in the isomerization art generally utilized temperatures of the order of 200 F. and above to secure effective conversion.

As illustrating the effectiveness of the catalyst of this invention on other normal paraflins, the following three runs on normal pentane, normal heptane and a North Texas straight-run naphtha are listed:

Table IV naraflin charge 0 efln charge E Paraffin/olefin ratio, w Temperature, F"..- Contact time min Wt. per cent Yield liquid alkylate based on total HG charge n-parafiin Yield oi oi! total B ne Yield 3? charge Wt. per cent based on isobutane, Wt. per cent based on olefin charged--. n-pfl. c

Composition of oflgas, Wt. per cent: per cent less than 04 per cent isobutaneper cent n-butane per cent greater than 04 U cm 00 1 n-Pentane.

n-He time.

Next Texas SR Naphtha Boiling range 96-348 F., Original CFRM octane 63 2 4 isobutylene.

In each of these runs, it will be noted that the oflgas consisted of more than 70% by weight of isobutane, and ran as high as about in the run on normal heptane. In the normal pentane run, thealkylate contained a large percentage of isopentane, the balance being mainly hexanes, heptanes and octanes, with the major proportion boiling below the octane range and providing a similar high volatility for blending stock as obtained in the normal butane runs. In the case of normal heptane, the major proportion was converted to both lower and higher boiling hydrocarbons with a resultant C.,F. R. M. octane crease from to 72 for the converted alkylate, End a substantial proportion agaln'bolling in the lower range providing high volatility. In the case of the straight run naphtha, the boiling range distribution of the alkylate was advantageously lowered with the concomitant production of a substantial amount of isobutane.

A series of continuous runs was also made in a rotary copper-lined reactor fitted with a steel shaft and impeller driven 'by an electric motor at about 1750 R. P. M. In starting up a continuous run, the required amount of anhydrous liquid HF was charged to the reactor, and then the system was filled with normal paraflin, such as normal butane, and gaseous BF: then added until the pressure in the system reached about 200 pounds per square inch. Then a mixture of the normal paramn and olefin was added continuously while the contents of the reactor were agi= tated. The reacted mix overflowed at a corresponding rate to a long inclined settler where most of the HF and probably some of the BF: separated from the hydrocarbon phase and was continuously recycled to the reactor. The hydrocarbon phase containing some dissolved HF and a substantial amount of the BF: passed through a control valve to a caustic scrubber, and thence to the product receivers and stabilizers, where the oflfgases and BF: were removed from the stabilized al ylate. This alkylate was then distilled to separate into the desired fractions, such as a 311 F. end point fraction and any higher boiling residue. 7

In an alternative procedure, BF: was added continuously with the hydrocarbon charge to provide a portion of the required amount of BF: in

the reaction zone and to make up for that which was removed with the reacted mix. In other runs, the parafiln charge was saturated with both HF and BF: at room temperature and about 150 pounds per square inch. In either case, the hydrocarbon charge was divided into two parts, one part being a mixture of normal butane with the olefin in the desired molar ratio of about :1 to :1, and the second part being the normal paraffln or normal butane saturated with HF and/or Blb. These two streams were charged continuously into the reactor which had been previously filled with catalyst and normal paramn as described above, so that both HF and BF: were continuously replenished to make up for losses.

The following are typical results of two continuous runs with normal butane and isobutylene, showing the etlect of varying the molar ratio of normal butane to isobutylene from 5:1 to 10:1.

Table V N-butane/isobutylene mol ratio 5 10 Temperature "F. 70 '70 Contact time, mm 6d 60 Yield stabilized alkylate, weight percent on olefin (aver.) 105 151 Vol. percent 311 F. E. P 70.4 93.1 Bromine No. 1 1 Octane No. C. F. R. M. clear 81.3 80.2 Octane No. C. F. R. M. +3 cc.

TEL/gal 95.0 Yield of isobutane, mol per cent on olefin, aver 37.2 190 Pounds of alkylate per pound of catalyst, approx 2.5 1 Pounds of isobutane per pound of catalyst. approx. 5

The above runs were carried out with continuous recirculation oi catalyst to obtain a measure of catalyst life. During the course of the runs, it was noticed that the catalyst tends to form a small amount of hydrocarbon complex; but this is quite small in comparison to the amount for-med with aluminum chloride, for example. The emciency of the catalyst was eventually lowered; and when the yield of alkylate and/or isobutane has dropped to a predetermined point. as determined by direct measurement or by extrapolation of the curve for the run, the latter was terminated. It will be noted from the above that a 10:1 molar ratio or normal butane to isobutylene is superior to a lower molar ratio from the standpoint of yield of total stabilized of the oleflns, ethylene, propylene and isobutylene, in this process:

Table VI Ethyl- Propyl- Isobutylolefin used one 9118 one n-butane/olefln mol ratio lO/l 10/1 10/1 Reaction temp., 3F 70 70 70 Contact time, min 60 c0 60 Yield debutanized alkylate, wt.

percent on oleiin 277. 5 1.85. 8 151 Percent of theoretical 90. 4 18. 0 74. 0 Vol. percent 311 F. E. P 97.2 95. 7 93. 1 Br. No 1 1 1 Octane No. CFBM clear. 80. 8 78. 8 80. 2 Yield of isobutane:

Moi percent basis olefin. 300 250 Mo] percent basis n-butane 30 25 19 Pounds alkylate per pound catalyst ed 5. 5 5. 3 4. 0 Pounds iso utane per pound cata lyst charged 12. 0 8. 3 10. 0

Contrary to previous experience in the alkylation of an isoparaflln with an olefin in the presence of conventional catalysts such as H2804 and HF wherein the C4 oleilns have been found superior and ethylene reacts only with dimculty if at all, the eflectiveness of the oleflns in the present process of alkylating normal parafllns is found to. vary inversely with the molecular weight of the olefin. Thus, ethylene has been found to give the best results followed by propylene and isobutylene in that order.

In continuous operation, a portion of the catalyst may be continuously withdrawn from the system and the remaining catalyst fortified by the addition of either HF or BF: or both, such as by being introduced with the hydrocarbon charge. It will be also understood that the reaction products can be fractionated to separate any unreacted normal paraflln and the latter recycled to the system to increase the yield on the basis of the normal paraffin charge.

It has been further found that the presence of a small amount of iron, such as in the form of the metal or metal alloy, has a distinct promoting efl'ect upon the reaction. To illustrate this efiect. continuous runs were carried out in a steel reactor in one case and in a copper-lined reactor free from exposed iron or steel surfaces in the other case. The following are data and results of these runs employing normal butane with propylene:

It is also contemplated that salts or compounds of iron, such as ferric and ferrous fluorides, iron salts of boric and fiuoboricacids, etc., may be employed for this purpose. Likewise, it is contemplated that other metals above hydrogen in the electrochemical series, such as cobalt, nickel, manganese, etc., as well as alloys and compounds thereof may be used for this promotional effect.

In either batch or continuous operation, the promotional effect may be obtained by immersing a strip of cold rolled steel or other promoter metal in the reactor, which latter together with the impeller and shaft are preferably constructed of a suitable resistant metal or lining, such as with a copper lining or of stainless steel or Monel metal, to resist corrosion. The reactor may be fitted with a readily replaceable plug or pipe of the promoter metal, so that this is maintained in fixed position within the reactor and does not interfere with the rotation of the impeller and agitation of the contents of the reactor. It is thought that the promoter metal may function as a suppressor of complex formation, giving longer catalyst life. For purposes of easy description, it will be understood that the expression metal promoter as used in the specification and claims signifies any of the above mentioned metals, alloys or metal compounds having this promotional effect.

From the above description, it will be apparent that the present invention provides a method of alkylating a normal paraflin with an olefin with concomitant isomerization or production of isobutane, wherein a yield of alkylate of at least about 75-90% of the theoretical on the basis of the olefin charged, and an accompanying yield of isobutane amounting to at least about 20-30% on the basis of the normal paraffln charged, are obtained. The alkylate consists largely of isopentane and hexanes regardless of the olefinic component of the charge, boils almost entirely below 300 F., is substantially completely saturated, has high lead susceptibility, and is an excellent blending stock from the standpoint of volatility and octane blending value, particularly for leaded fuels. The present invention is thought particularly valuable in providing a means for utilizing available refinery supplies of normal butane, ethylene, and propylene, thus providing a one-step process for simultaneously eflecting alkylation with the production of alkylate blending stock, and the concomitant production of substantial quantities of isobutane for use in conventional isoparafiin-olefin alkylation processes.

While the invention has been described above in connection with the use of an olefin for reacting with the normal paraiiin, it is to be understood that other alkylating agents which function similarly to olefins in the alkylation reaction can be employed. For example, alkyl esters, such as alkyl fluorides, may be used. These alkyl esters may be produced by absorbing an olefin in a suitable mineral acid, which may be the same as the catalyst employed in the subsequent alkylation step. The acid solution of the olefin absorption product maybe passed directly to the alkylation zone; or the alkyl ester may be separated from the absorption acid by the use of a a suitable solvent, such as normal butane or other normal paraflin, and the purified ester then transferred to the alkylation reaction zone. Also, various aliphatic alcohols and ethers, such as tertiary or secondary butyl alcohol, isopropyl alcohol, butyl ether, etc., may be used as the alkylating agent, although the latter are not generally preferred for the present process since water is liberated in t reaction requiring frequent replacement of catalyst.

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

I claim:

1. The method of treating a normally liquid parafiinic naphtha fraction to improve the volatility and other properties thereof and to concomitantly produce isobutane, which comprises contacting the naphtha in liquid phase in the presence of a minor but effective amount of an added olefin at ordinary temperatures below about 150 F. with a mixed catalyst consisting essentially of a major proportion by weight of substantially anhydrous liquid HF and a minor but eflective proportion by weight of BF.) of the order of about 4-20 mol per cent on the basis of the mixed catalyst, and separately recovering the resultant normally liquid hydrocarbons and the produced isobutane from the reaction products.

2. The method which comprises introducing a normal paraflin hydrocarbon essentially free from isobutane and an aliphatic alkylating agent selected from the group consisting of olefins, alkyl esters, alcohols and ethers, with the normal paraflin in substantial molar excess of the alkylating agent, into a'reaction zone, and reacting the mixture therein in the substantial absence of added isobutane and in the presence of a mixed catalyst consisting essentially of a major proportion by weight of substantially anhydrous liquid HF and a minor but efiective proportion of the order of 2-20 mol percent of BF3 on the basis of the mixed catalyst under conditions including a temperature of about 0-150 F. and sufiicient pressure to maintain at least the normal paraflln in liquid phase, such that normal paraffin is alkylated by the aliphatic alkylating agent to produce substantially saturated motor fuel hydrocarbons with the concomitant production of a substantial amount of isobutane, and separately recovering the motor fuel hydrocarbons and the isobutane from the reaction prodnets.

3. The method according to claim 2, wherein the normal paramn is normal butane, and the aliphatic alkylating agent is a normally gaseous olefin.

4. The method of manufacturing substantially saturated hydrocarbons boiling within the gasoline range which comprises introducing essentially a low boiling normal paraflln and an olefin, with the normal paraffin in substantial molar excess of the olefin, into a reaction zone, and reacting the mixture therein in the substantial absence the reaction products said produced normally liquid hydrocarbons and unconverted normal paraflln substantially free from isoparamn of corresponding molecular weight, and recycling recovered unconverted normal paraflin substantially free from isoparailin of corresponding molecular weight to said reaction zone.

5. The method according to claim 4, wherein the normal paraflin is normal butane, and the olefin is a normally gaseous olefin.

6. The method of producing isobutane which comprises introducing a normal parafiin essentially free from isobutane together with a minor but effective amount of an olefin, providing a molar ratio of normal paraflin to olefin in excess of :1, into a reaction zone, and reacting the same therein in the presence of a mixed catalyst consisting essentially of a major proportion by weight of substantially anhydrous liquid HF and a minor but eflective proportion of the order of about 6-20 mol per cent of BF: on the. basis of the mixed catalyst under conditions including a temperature of about 70-150 F. and sufllcient 1 pressure to maintain at least the normal parafiln in liquid phase, such that a substantial amount of isobutane is produced in the resulting reaction, and recovering the isobutane from the reaction products.

7. The method according to claim 6, wherein the normal paraflin is normal butane, and the olefin is a normally gaseous olefin.

8. The method of isomerizing a normal paraiiin hydrocarbon which comprises introducing a normal parafiin hydrocarbon substantially free from isoparafiln of corresponding molecular weight and a small but eiiective amount of an olefin, providing a normal paraiiin to olefin molar ratio in excess of about 10:1, and reacting the mixture therein in the presence of a mixed catalyst consisting essentially of a ma] or proportion by weight of substantially anhydrous liquid HF and a minor but effective proportion of the order of 6-20 mol per cent of BF: on the basis of the mixed catalyst under conditions including a temperature of about 70-150 F. and suiiicient pressure to maintain at least the normal paraflln in liquid phase, such that a substantial amount of isoparaflin of corresponding molecular weight is produced in the reaction, and recovering said isoparaffin from the reaction products.

9. A method of making substantially saturated branched-chain hydrocarbons which comprises charging a normal paramn hydrocarbon to a reaction zone, adding a minor mol proportion, based on the normal paraifin, of an olefin hydrocarbon to the reaction zone, reacting the hydrocarbons in the presence of a catalyst comprising essentially substantially anhydrous HF and a minor mol proportion based on the total catalyst, of BFs, under reaction conditions wherein the pressure is such as to maintain the hydrocarbons and the HF in liquid phase, wherein the temperature is substantially room temperature and wherein sufficient time is given for the reaction to form substantially saturated branched-chain hydrocarbons.

10. 'A method of making substantially saturated branched-chain hydrocarbons which comprises charging a normal parafiln hydrocarbon to a reaction zone, adding a minor mol proportion, based on the normal paraflin, of an olefin hydrocarbon to the reaction zone, reacting the hydrocarbons in the presence of a catalyst comprising essentially substantially anhydrous HF and a minor mol proportion based on the total catalyst, of BFs, under reaction conditions wherein the pressure is such as to maintain the hydrocarbons and the HF in liquid phase, wherein the temperature is within the range of about 50 F. to about F. and wherein sufllcient time is given for the reaction to form substantially saturated branched-chain hydrocarbons.

LOUIS A. CLARKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,240,134 Eglofi Apr. 29, 1941 2,283,142 Ipatiefi et al. May 12, 1942 2,285,785 Seguy June 9, 1942 2,296,370 Slotterbeck Sept. 22, 1942 2,307,773 Eglofl Jan. 12, 1943 2,315,078 Pines et al. Mar. 30, 1943 2,317,901 Frey Apr. 27, 1943 2,325,122 Ipatiefi et al. July 27, 1943 2,333,648 Grosse et al Nov. 9, 1943 FOREIGN PATENTS Number Country Date 516,780 Great Britain Jan. 11, 1940 OTHER REFERENCES Ipatieif, Catalytic Reactions, pages 618, 682, 684, 686-693.