35,231,633 United States Patent 0 ” IC€ Patented Jan. 25, 1966

1 2 the stable 1:1 ole?n-paraffin adduct, e.g. octane. These 3,231,633 side reactions lead to the formation of C12+ products ALKYLATION PROMOTER which then undergo cracking reactions to form undesirable George M. Kramer, Berkeley Heights, N.J., assignor to Esso Research and Engineering Company, a c0rpora~ lighter hydrocarbons such as, for example, C5, C6 and CY] tion of Delaware light alkylate ‘components. The result, of course, is to N0 Drawing. Filed Nov. 27, 1963, Ser. No. 326,368 minimize the production of the desired C8 products and to 10 Claims. (Cl. 260—683.51) lower the octane number of the products obtained. This predominance of the undesirable formation of greater The present invention relates to an improved alkylation than 1:1 adducts generally continues for a period of time, process. In particular, this invention concerns the produc 10 at the end of which period there is a marked, rather abrupt tion of a product containing C8 hydrocarbons by the change in the selectivity of the alkylation reaction to the alkylation of paraffin hydrocarbons with ole?ns. More formation of the 1:1 adduct. The transitional period particularly, the invention relates to an acid catalyzed during which the undesirable side reaction is selectively ibutane-butylene alkylation process having a high selectivity predominating over the desirable formation of this 1:1 for the production of trimethylpentanes, i.e. (2,2,4-tri adduct is generally referred to as the “induction period.” methylpentane) . While the reason for this induction period effect is The acid catalyzed addition of an alkane to an alkene not known for certain, it is believed that during the in to form a desired product is well-known. The reactants duction period, material is forming which is surface active' are generally contacted in the liquid phase at temperatures and the change in selectivity which is observed accom usually below about 100 °F., although on occasion, higher panies a change in the nature of the acid surface. That is, temperatures may be utilized and at pressures varying at this time, the surface-active material comes to the sur from ambient to superatmospheric. face of the acid and serves to control thereacti'on. As a Of particular importance within the realm of alkyla rule, this induction period will vary with the nature of tion is the reaction of butylenes and isobutane to form the feed and the catalyst used, but generally lasts about octane and, in particular, isooctane. The butylenes, gen 25 200 hours in straight fluorosulfonic acid and approxi— erally a mixture of normal and iso, are reacted in the liquid mately 1%; of that with a catalyst consisting of sulfuric phase in the presence of a strong acid such as, for example, acid. ?uorosulfonic acid or sulfuric acid, at a temperature of 0 Where ?uorosulfonic acid is to be used as a catalyst, to 100° F. and at a pressure of 10 to 150 psig. The the induction period may be reduced by using ?uorosul reaction can be postulated as proceeding as follows: 30 fonic acid in combination with up to about 50 wt. per cent H2SO4 and, preferably, up to about 25 wt. percent H2504. While the combined acids result in a reduced in-' duction period, the period is still consideraby'longer than that found with the use of H2504 alone. 35 It has ‘been unexpectedly found, according to this in; vention, that improved selectivity and decreased induction period can be achieved in strong acid catalyzed alkylation reactions if the hydrocarbon reaction mixture is con tacted at alkylation reaction ‘conditions in the presence 40 of a modi?ed acid catalyst, said catalyst comprising a strong acid in combination with a large, stable, surface‘; active cation. A particularly useful cation is the tertiary carbonium ion. For purposes of de?nition, the term “ca tion” refers to a positively charged atom, radical or group 45 of atoms which will pass to the cathode during electrolysis.’ By a large cation is meant one which has a radius of 3.47 A. to 9.67 A. Surface-active compounds are those which alfect interfacial tension between two liquids. A cation is considered stable if the strength of H2504 in which the ion 50 is half formed is 85%, preferably 50% or less. A wide variety of surfactants can be protonated or dissociated to form a carbonium, allylic carbonium, tetra; alkyl ammonium, tetraaryl ammonium, phosphoniu'm, oxonium, ammonium, sulfonium or similar cations which The most important rate determining factor in this re may be readily utilized within the scope of this invention. action is the hydride extraction step. The hydride extrac Examples of the above are: tion step refers to the removal of an H— from the iC4H10 and the subsequent or simultaneous addition of the H— to C8+~ to form trimethylpentane from the appropriate ion. Alkylation reactions, as exempli?ed by the strong acid 60 (ctr-1930+, H2 H2 , (enema (cinema [(CHshPHP' catalyzed reaction of butylenes and isobutane to form octane, have been plagued'with several difficulties in the past. While these di?iculties will be discussed hereinafter III with respect to the formation of octane, it is to be under (EH3 CH3 CH2 stood that they are equally applicable to any alkylation re cna-dwnr-o-om, 113c- —-s-on3 action. The basic problem concerns the fact that the | E | + ‘ formation of the 1:1 ole?n-para?in adduct, e.g. octane, at H the start of the reaction does not proceed as rapidly as These are only illustrations of cations which may be would be desired. Thus, the adduct ions, e.g. C8+ ions, utilized and a great variety of compounds of varying during the initial period of the reaction participate in un 70 molecular weights and carbon chains may be utilized. desirable side reactions at a much faster rate than the A cation, and by way of example a large tertiary car-V desirable but slower hydride extraction reaction to form bonium ion, may be obtained by dissolving a compound 3,231,633 3 4 such as triphenylmethyl chloride in an acid thereby ob stable, surface-active cations and, in particular, triphenyl taining HCl and the ion. The required cation may also methyl carbonium ions to catalyst systems involving the be obtained by dissolving triphenylmethyl alcohol in sul strong Lewis acids such as AlBr3, A1013, BFa, SbF3, SbCl5, furic acid thereby obtaining water and the ion. This gen SbBr3, SbF5, GaCl3 and AsF5 will result in improved eral method is known as solvolysis. Alternatively, the paraffin-ole?n, naphthene-ole?n and aromatic-ole?n alkyl ion may be obtained by a hydride transfer such as from ation and also in better selectivity in the isomerization of triphenylmethane to a carbonium ion present in the acid. light paraf?ns, e.g. nC4 to nCm hydrocarbons, to highly A carbonium ion is a group of atoms that contains a branched isomers desirable as motor fuels. carbon atom bearing only six electrons. A tertiary car The Lewis acid systems mentioned are normally used bonium ion is a carbon atom bearing only six electrons 10 in conjunction with cocatalysts or promoters such as wa~ andji-s also joined to three other carbon atoms. For an ter, ethers, alcohols, ole?ns, HBr, etc., or on supports such extensive discussion of carbonium ions and their forma as A1203, SiO2, B203 and other equivalent mechanisms. tion and reactions see Morrison and Boyd, Organic Chem In fact, this is implied within the very term “catalytic istry, Allyn and Bacon, Inc. (1959),‘p‘a'g’es 116-121, 138 systems." Most of the systems are heterogeneous. The 139, 142-143, 256—259 and 375-376. ’ 15 systems, therefore, involve the formation of carbonium The large, stable and surface-active tertiary carbonium ion intermediates at an acid-hydrocarbon interface and a ion, triphenylmethyl ion, which was used for illustration method of controlling the reaction of any one system may above, is particularly effective in this invention. This ion presumably be extended to all others. I is more than half formed in 50% H2SO4, is surface active In general, any of the conventional catalytic alkyla and has a radius of 5.77 A. However, the other large, tion reactions can be carried out by the process of the stable and surface-active cations named above would be present invention. Thus, the alkylation reaction can com equally as elfective in this invention. Another alterna prise reaction of an isoparaf?n with an ole?n, or reac tive in the carbonium ion family would be the tricyclo tion of an aromatic hydrocarbon with an ole?n or other proplmethyl ion. Of course, any large, stable, surface alkylating agent, the reaction in each instance being car active compound forming divalent 'or trivalent cations ri-ed out in the presence of a suitable alkylation catalyst. would be equally as effective. ‘ In place of an ole?n as an'alkylating agent, various al Quantities of large cations to be employed for most cohols and ethers, such as isopropyl alcohol, tert-butyl satisfactory results as a constituent of the modi?ed catalyst alcohol, secondary butyl alcohol, isopropyl ether, and the will vary between 0.01 and 10 mole percent of the catalyst like, can be carried out in the presence of a suitable alkyla~ and preferred results may be obtained generally with 0.1 30 tion catalyst. Likewise, the corresponding akyl esters, to 3 mole percent of the catalyst when using the triphenyl such as the alkyl halides, sulfates, phosphates, ?uorides of methyl carbonium ion in particulan.v Excellent results the ole?ns, may be used as the alkylation agent with an with the hereinbefore described cations, particularly terti appropriate or compatible alkylation catalyst. ary carbonium ions, have been obtained at concentrations The alkylation reaction is carried out with the hydro between about 0.5 .and 1.5 mole percent of the catalyst carbon reactants in the liquid phase; however, the reac while the quaternary ammonium’salts appear to work best tants need not be normally liquid hydrocarbons. The at concentrations of about 0.6 mole percent of the catalyst. reaction conditions can vary in temperature from sub-zero While not wishing to be bound by any particular mecha temperatures to temperatures as high as‘2-00° F. and can nis'm, it is presently believed that the hydride transfer is 3 be carried out at pressures varying from atmospheric to considered to be the rate determining step in alkylation. 40 as high as 1,000 p.s.i. and higher, and space velocities That is to say, in the formation of'octane for example, ranging from about 0.01 to about 20. A variety of alkyla the transfer of negative hydride ions from isobutane to an tion catalysts can be employed in the alkylation reaction. intermediate positively charged isooctyl ion controls the However, hydro?uoric and sulfuric acid are preferred. reaction speed and with it the product quality obtained. (I; As hereinbefore noted, sulfuric acid and ?uorosulfonic Too little hydridetransfer leads to poor quality alkylate 45 acid are prime examples of strong acids which have been containing pentanes, hexanes and heptane. Furthermore, used as catalyst in the alkylation reactions. Once again, poor hydride transfer ability gives rise to low quality octyl it should be noted that other strong acids such as HF may isomers. Large, stable, surface-activecations such as the be utilized and what is said about sulfuric and ?uorosul triphenylmethyl carbonium ion which has been referred fonic acids would also true of a variety of strong acids. to above, condition the turface to enhance the hydride In particular, ?uorosulfonic acid is a very effective cata transfer reaction and also slow processes that normally lyst for the reaction of isobutylene and isobutane to form lead to unwanted side reactions such as polymerization octanes, especially the very desirable 2,2,4-trimethylpen and cracking. This same result would, as is naturally to tane which is commonly referred to as isooctane. The be expected, be achieved by all the other large, stable, most desired temperatures for the use of sulfuric acid surface-active cation which have been previously enumer 55 would be between 30 and 75 ° F. and pressures of 10 to ated. - 150 p.s.i.g. When using ?uorosulfonic acid, most de The use of large, stable, surface-active cations to speed sired temperatures are between 0 and 75° F. and pres hydride'transfer reactions is particularly applicable to sures of 10 to 150 p.s.i.g. Both ?uorosulfonic and sul those alkylation reactions catalyzed by the strong Brdn furic acid are characterized by the previously mentioned sted acids. The strong Bronsted acids are those substances 60 extended induction periods, although the induction period which readily give up a proton. Large numbers of these for ?uorosulfonic acid is considerably longer than that for acids are well-known to one skilled in the art. They sulfuric acid. would include all of thehalogen ,acids, HF, HCl, HI and ‘ The following speci?c examples are offered to illus HBr as well as H2504, ?uorosulfonic acid, chlorosulfonic trate the improvement of the instant invention. and HB (H5094. These are the acids used in the (C4 65 to C10) parat?n7(C2 to C10) ole?n, naphthene ole?n and EXAMPLE 1 aromatic ole?n alkylation. All of these‘ reactions would A microalkyl-ation ‘reactor was operated at 50° F., be improved by the faster hydride transfer rates, less a pressure ofv 100 p.s.i.g. and an ole?n space velocity polymerization and cracking and better selectivity which of 0.035 to 0.065 v./hr./v. the ratio of ole?n, that is to would result from the addition of a large, stable, surface 70 say, C4, ole?n to C4 isopara?in in the feed to the reactor active cation. Traditional alkylation conditions, i.e., pres-. was 1 to 20.‘ ' The actual feed employed was cis-2-butene sure, temperature may be utilized. These conditions will and isobutane. The cation utilized was the triphenyl be discussed subsequently. methyl carbonium ion (TPMC). The source of large In the same manner, the Lewis acids or electron pair triphenylmethyl carbonium ions was triphenylmethyl acceptors are utilized as catalysts. The addition of large, 75 chloride. The ‘paraffin and ole?nin liquid form were 3,231,633 .5 '6 admixed with one another and added to the H2504. EXAMPLE 3 They were then stirred vigorously. To illustrate the im In this example, conditions are identical to those provement of this invention, three diiferent concentra of Example 2 except that about 1 mole percent (based tion levels of cations were employed, i.e. '1/2, 1.0 and 3.0 on acid catalyst) of triphenylmethylchlloride is added to mole percent TP‘MC in 98% sulfuric acid. It was found the pure H2304 and HSO3F catalyst. The product ob that at a butene space velocity of 0.035 v./hr./v. with 1.0 tained is about 98% C8 which is substantial improve mole percent TPMC, an exceptionally high quality alkyl ment and the induction’period is essentially eliminated. ate was obtained. This alkylate was about 98% selec With I-ISO3F, the induction period is reduced to less tive to total octanes. In addition, the major octane in than 5 hours or the time necessary to line out the re the C8 fraction was the high octane isomer 2,2,4-trimethyl 10 actor. Thus, the addition of a large, surface-active car pentane (42%). These results may [be compared with 'bonium ion to an acid strong enough to induce alkyla alkylate C8 selectivity of 82 to 89% and about 33% 2,2,4-trimethylpen-tane in the C8 fraction using uncondi tion, immediately conditions the acid and substantially tioned sulfuric acid. eliminates the induction period. 15 EXAMPLE 4 ‘Table I In this example, conditions are identical to those of Example 2 except that 1 mole percent of an allylic car a b c at bonium ion is added ‘to both the H2SO4 and the ?uoro sulfonic acid catalyst. The allylic carboniumis added Mole percent 'I‘PMC » in msoiuh or % 1 3 20 in the form of Ole?n Space Velocity, v./hr./v_ ____ 0. 035 0. 035+ 0. 035 0. 065 Selectivity, percent 03 in 05+ _ _ _ __ 89-82 96 . 97. 5 93-87

*1 TP-MC =triphenylmcthylch1oride. Estimated motor octane numbers indicate that the acid containing 1% TPMC produces an alkylate of about 0 l 98 MON (US-350° FVT). This octane number com H pares to one of about 94—95 whichwas obtained with The product obtained is about 98% CB and the induc unmodi?ed sulfuric acid showing a gain of at least 3—4 tion period ‘is substantially eliminated for ‘both the sul octane number when practicing the process of the present furic acid and the ?uorosulfonic acid catalyst. invention. In Table I we see that Run a which was conducted with no TPMC added to the acid, produced EXAMPLE, 5 the lowest selectivity. Runs vb, _c and d produced much In this example,~conditions are identical to those of higher selectivity. The selectivity obtained in Run 0 Example 2 except that 1 mole percent of a tetramethyl was the vhighest, 97.5%. However, both Runs b and cl ammonium ion is added to ‘both the H2SO4 and the also vproduced considerably more of the desired product ?uorosulfonic acid catalyst. The tetrarnethyl ammoni than Run a. This clearly indicates the advantage to um ion is added in the form of tetramethyl ammonium ‘be gained from the addition of large cations to sulfonic chloride. The product obtained is about 98% C8 and acid in the alkylation reaction. 40 the induction period is substantially eliminated for both the sulfuric acid and the ?uorosulfonic acid catalyst. I EXAMPLE 2 This example illustrates the induction period which EXAMPLE 6 is associated with the use of sulfuric and ?uorosul'fonic In this example, conditions are identical to those of acids as catalysts for alkylation and, in particular, the Example 2 except that 1 mole percent of a tetraphenyl alkylation of butylene and isobutane to form isooctane. ammonium ion is added to both the H2SO4 and the ?uoro The hydrocarbons were added to the acids and then sulfonic acid catalyst. The tetraphenyl ammonium ion agitated for good mixing. The temperature was 50° F. is added in the form of tetraphenyl ammonium chloride. and the pressure was 100 p.s.i.g. in all cases. The product obtained is about 98% C8 and the induction 50 period is substantially eliminated for both the sulfuric Table II acid and the ?uorosulfonic acid catalyst. EXAMPLE 7 Catalyst ______H2804 25% BS0314‘ H2804 1'1 2304, +1% In this example, conditions are identical to those of 75% TPMC Example 2 except that 1 mole percent of a trimethyl HSOaF phosphonium ion is added to both the H2804 and the ?uorosulfonic acid catalyst. The trimethyl phosphonium Feed t. Percent: iJCVYIIiL ______.- 94. 15 94, 15 94, 15 95 ion is added in the form of trimethyl phosphonium chlo 4'-.a_-___ __ 5.85 5.85 5.85 5 ride. The product obtained is about 98% C3 and the in O.S.V., v./l1r./v ______0, 04 0. 04 0.04 0.035 Induction Period, Hrs _____ .t 40 125 210 None 60 duction period is substantially eliminated vfor both the Production Distribution, Sulfuric acid and the ?uorcsulfonic acid catalyst. Wt. Perce t‘ C5-C1“ ______1 10. 1 1-2 1-2 2, 5 Cu“... ___ I89. 9 ‘HS-99 98419 97. 5 EXAMPLE 8 224 "I‘MIJ in Ca ______36. 0 50—60 50:60 40-55 In this example, conditions are identical to those of 1 Analysis of best product. 65 Example 2 except that 1 mole percent of a methyl isobutyl oxonium ion is added to both the H2804 and the ?uorc— In this table the large production of octane and, in sulfonic acid catalyst. The methyl iso‘outyl oxon-ium particular, isooctane, which results from a ?uorosulfonic ion is added in the form of methyl isobutyl oxoniu-rn acid catalyst used ‘alone or in admixture with sulfuric chloride. The product obtained is about 98% C8 and the acid, was considerably better than that obtained with 70 induction period is substantially eliminated for both the a pure sulfuric acid catalyst. However, the induction sulfuric acid and the ?uorcsulfcuic acid catalyst. period 0t 210 hours for a pure ?uorcsultonic acid catalyst and 125 hours for the mixed catalyst was considerably 9 worse than the 40-hour period which resulted from In this example, conditions are identical to those of the use of pure sulfuric acid as the catalyst. Example 2 except that 1 mole percent of a dimethyl iso 3,231,633 7 8 propyl sulfonium ion is added to both the H2804 and the comprises contacting a hydrocarbon mixture containing ?uorosulfonic acid catalyst. The dimethyl isopropyl sul an alkylatable hydrocarbon and an alkylating agent at fonium ion is added in the form of dimethyl isopropyl alkylation conditions with a catalyst composition com sulfonium chloride. The product obtained is about 98% prising a strong acid selected from the group consisting Ca and the induction period is substantially eliminated for of sulfuric acid, hydro?uoric acid and ?uorosulfonic acid both the sulfuric acid and the ?uorosulfonic acid catalyst. and a catalyst promoteruselected from the group consist EXAMPLE 10 ing of an ionizable triphenylmethyl salt and an ionizable tricyclopropylmethyl salt. ' In this example, conditions are identical to those of 6. An improved process for the alkylation of an ole?n Example 2 except that 1 mole percent of a tricyclopropyl 10 with a paraffin while minimizing cracking and the induc methyl ion is added to both the H2804 and the ?uoro tion period which comprises contacting said paraf?n and sulfonic acid catalyst. The tricyclopropyl methyl ion is said ole?n at reaction conditions vwith a catalyst com added in the form of tricyclopropyl methyl chloride. The prising sulfuric acid and an ionizable triphenylmethyl salt. product obtained is about 98% C8 and the induction 7. An improved process for the alkylation of an ole?n period is substantially eliminated for both the suluric 15 with a para?’in while minimizing cracking which com acid and the ?uorosulfonic acid catalyst. prises contacting said ole?n and said paraf?n at reaction What is claimed is: conditions with a catalyst comprising an acid selected 1. An improved process for the alkylation of butylenes from the group consisting of sulfuric acid, hydro?uoric with isobutane to form a maximum amount of isooctane acid and ?uorosulfonic acid; and 0.01 to 10 mole per while minimizing cracking which comprises contacting 20 cent of an ionizable :triphenylrnethyl salt. said butylenes and said isobutane at a temperature of 30 8. The process of claim 7 wherein said contacting takes to 75° F. and a pressure of 10 to 150 p.s.i.g. with a cata place at a temperature of 30 to 75° F. and a pressure lyst com-prising sulfuric acid and 0.01 to 10 mole per of 10 to 150 p.s.i.g. cent of an ionizable triphenylmethyl salt. 9. The process of claim 7 wherein‘ said acid is sul 2. An improved process for the alkylation of butylenes 25 furic acid. with isobutane to form a maximum amount of isooctane 10. The process of claim 7 wherein said acid is HF. while minimizing crackingwhich comprises contacting of said butylenes and said isobutane at a temperature References Cited by the Examiner of 10 to 75° F. and a pressure of 10 to 150 p.s.i.g. with .a catalyst comprising ?uorosulfonic acid and 0.01 to 10 30 UNITED STATES PATENTS mole percent of an ionizable .triphenylmethyl salt. , 3. An improved process for the alkylation of butylenes 2,435,028 l/1948 Bradley ______260—683.63 X rwith isobutane to form a maximum amount of octanes 2,437,544 3/1948 Marisic ______260——683.63 X while minimizing the iduction period which comprises 2,441,102 5/1948 Meadow ______260—683.51 contacting the ‘said butylenes and the said isobutane with OTHER REFERENCES a catalyst, the said catalyst consisting of a mixture of ?uorosulfonic acid, sulfurioacid and an ionizable tri Kobe, K. A. and McKetta, J. 1., Advances in Petroleum phenylmethyl salt. ‘ Chemistry and Re?ning, vol. 1, Interscience, N.Y., 1958-, 4. The process of claim 3 where the said ionizable p. 347-363. > triphenylmethyl salt is present in an amount of 0.01 to 10 DELBERT E. GANTZ, Primary Examiner. mole percent. - _ 1 5. A process for carrying out an alkylation reaction ALPHONSO D. SULLIVAN, PAUL M. COUGHLAN, while minimizing cracking and the induction period which ‘ Examiners.