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Patented July 23,’ 1946 2,404,436 _ UNITED » smEs .1 ‘PATENT ore-Ice ‘v V . ISOMERIZING HYDROCARBONS Chester 0. ‘Crawford, El Cerrito,:and'David Louis Yabroif, Alameda, Calif., assignors ‘to Shell De velopment Company, San Francisco, Calif., a corporation of'Delaware vNo Drawing. Application November 17, 1942, . l lSerialfNo. 465,926 4 Claims. ‘ (Cl. 260-6835)’ 2 This inventionrelates to the catalytic isomer- ‘ ization of saturated hydrocarbons ‘and relates more ,particularly'to an improved ‘process for the catalytic conversion of normal :or branched chain saturated hydrocarbons, having at least ?ve car bon atoms to the molecule, :to branched or more highly branched chain saturated hydrocarbons having the samenumber of carbon atoms to the molecule. . of isomerization, often is vso great as to occasion the loss of the greater part of the material charged- A still greater detrimental effect oc casioned by the hydrocarbon decomposition in the presence of the Friedel-Crafts type catalysts is the rapid deterioration of the catalyst brought about by the products of this reaction. Much effort has been expended in attempts to control the tendency of the Friedel-Crafts type Catalysts of the Friedel-Crafts type are known _~ 10 catalysts, and particularly the aluminum-halides, to catalyze the hydrocarbon isomerization reac tion. However, these catalysts are also effective ' in catalyzing the decomposition of hydrocarbons. In‘ the isomerization of a'more stable, hydrocar bon, it is sometimes possible to favor theisomer .15 ization’ reaction by a judicious selection of tem-' perature and pressure'conditions to such-a degree that conversion to the ‘desired isomer is attainedv 'with a minimum of hydrocarbon decomposi‘tion.~ Processes are presently in use "which enable the R20 e?icient conversion of butane to isobutane with but little undesired side reactions. ‘Many other hydrocarbons, such as, for example,ethe saturated open chain hydrocarbonslhaving five or more car bon atoms to the .moleculeare, however, :parti'cu- ‘ to catalyze the decomposition of hydrocarbons in non-destructive hydrocarbon conversion proc esses to thereby enable the desired reaction to predominate. Good results have been obtained in certain processes by the maintenance of a high partial-pressure of hydrogen in the'reaction zone. The use of this gas, particularly atthe high pres sures usually required to render it effective, in. creases initial and operating costs considerably and introduces di?ic‘ulties and hazards. of opera ’tion which often act as serious deterrents to practical operation. . _ It has vnow been found that isomerizable hy drocarbons can be catalytically isomerized in the absence of substantial hydrocarbon decomposi larly proneto undergo decomposition in the pres tion and without the need for recourse to the ence of isomerization catalysts. Even in some .of these cases, the ‘undesirable side reaction can be suppressed to some degree by the use of sum introducing into the reaction zone an aromatic ciently mild operating conditions. Such .con'di- . tions often will be so mild, however, as to make the attainment of conversions and yields indica tive of a practical operation impossible. On‘ the use of normally gaseous cracking suppressors by compound of the hydrogen-donor type. By the term “aromatic compounds of the hydrogen donor type” or “aromatic hydrogen-donor,” as used throughout this speci?cation'and the at tached claims, is meant an organic aromatic com pound capable .of liberating hydrogen under the other hand, to use temperature conditions more‘ favorable to the ‘isomerization reaction in the ,35 conditions of execution of the isomerization re action. In accordance with the present inven treatment of these hydrocarbons in the absence » tion, a hydrocarbon stream comprising an isomer of agents ‘capable of ‘suppressing hydrocarbon de izable. saturated’ hydrocarbon is contacted with composition generally results in the presence of the hydrocarbon decomposition reaction ‘to 'a- de an isomerization catalyst of the Friedel-Crafts gree precluding eilicient operation of the process. .40 type at isomerizing conditions in the presence of an added aromatic hydrogen-donor. By the term “decomposition” as used through . The invention may be applied to the isomeriza- ' out this speci?cation and the ‘attached claims is tion of any Visomerizable saturated hydrocarbon. meant the rupture'lof carbonto carbon and/or carbon to hydrogen bonds of the. hydrocarbon It is applied with particular advantage, however, molecule to result in the formation of hydrocar- . 45. bons of lower molecular weight‘ than the hydro carbon treated. ‘The detrimental effect ‘of the ,v to the isomerization of- the more readily degraded hydrocarbons, such as, for example, the open chainwpara?‘inic hydrocarbons having at least ?ve hydrocarbon decomposition reaction upon the isomerization process manifests itself in many carbon atoms to the Fmolecule of normal and charge by converting it to materials ‘other than may comprise not merely one isomerizable hydro branched structure. The invention isnot limited ways, any one of which is generally su?icient to .50 . to the treatment of materials consisting essen render the process impractical. This reaction tially of a single hydrocarbon. It may be applied causes the loss of substantial amounts of ‘the to the treatment of hydrocarbon mixtures which an isomeric form of the material treated possess carbon but in addition one :or more other satu ing the same number of; carbon ‘atoms to the 55 rated hydrocarbons which may or may not be molecule. This loss in the treatment of the more capable of isomerization under the conditions of readily degraded hydrocarbons such aspentane, execution of theprocess. While the invention is methyl pentane, and the like, in many of the processes utilized heretofore, at temperatures en ization of saturated open. chain or para?lnic hy applied withparticular advantage to the isomer- ’ abling the attainment of even amoderate-rate so drocarbons; it'may be applied tothe treatment of 2,404,436 3 , 4" more readily-degradedSaturatedEhYdrOcarbOns in isomerizable naphthenic. hydrocarbonsrsuch as, ‘the .liquid'fph'aseis usuallyv 'e?ected at. somewhat for example‘, methylv cyclopentane, dimethyl cy clopentane, methyl cyclohexane, or hydrocarbon I = _ mixtures comprising them, The invention may" ' also be applied to the treatment under isomeriza; ing conditions of hydrocarbon fractions‘compris ing substantial amounts ofisomerizable hydro-. carbons, such ‘as, for example, fractions] of straight run gasoline, casinghead'gasoline;lfractions Vof the distillate products obtained in the lower temperatures. Suitable temperatures com prise, for example, about 0° C. to about 150° C. .Itis to he pointed out that operating tempera tures have been largely limited by the scope of l’ ,the'accompanying' decomposition reaction and "thatconsequently the present invention enables 'ffefflicientuoperation at somewhat higher tempera 107.."tures "than ‘possible heretofore in the absence of . The suppressors 11 isomerization reaction may be executed at sub a hydrocarbon .decomposition thermal or catalytic conversion-pf hydrocarbons, atmospheric, atmospheric, or superatmospheric etc. The hydrocarbons or hydrocarbon , mixtures », ' pressures. In the caseof liquid phase operation “ treated are preferablysubstantially free of mate' rials, the presence of which adversely a?ects the a su?iciently high superatmospheric pressure is, , 15 of‘cours'e, maintained to keep at least a substan activity of the catalyst." Ole?ns, diole?ns, .aro tial part of the reactants in'the'liquid'phase. matic hydrocarbons, or other detrimental impuri ties in the hydrocarbon- or hydrocarbon mixture to be treated are preferably removed prior to " vThe hydrogenedonor introduced into ‘the/reac comprise one or more of such steps as mineral , acid re?ning, hydrogenation, -alkylation,"contact I of liberating hydrogen-under the'iscmerization condition'semployed. - Suitable hydrogen-donors tion zone'in‘ accordance withthe invention may isomerization by a ‘suitable treatment which may 20 comprise broadly an aromatic compound capable ‘comprise v"organic compounds containing an'aro matic radical having attached directlyto the with clay or with part of the spent catalyst, sol vent extraction, etc. ‘_ I ' I ‘ _ aromatic‘ nucleus, ‘more than one hydroxy= or The is'omerization process may be carriedv out with any of the known Iisomerization' catalysts. amino groups, or a hydroxyl and an amino group. Other hydrogen‘ atoms in the aromatic nucleus Suitable isomerization'ca'talystsare, for example, those of the Friedel-Craftsltype, such in par may be replaced by suitable organicconstituents. There is a markedidifference,‘ however,‘ in the ease yvith 'whichth'e side ‘chains are ‘cleaved from an aromatic nucleus in' the presence o‘fFriedel Crafts type catalysts, larger 'alkyl 'ch'ains'being 'ticular as aluminum chloride and aluminum bro; mide; The catalysts maybe used as such or de posited upon or mixed with various carrier sub stances such vas¥activated alumina,‘ "activated separated far more ' readily than the- ‘shorter vside bauxite, activated carbon, or other suitable ad chainsm ‘Even though'thefhydrogenédonors need sorptive support materials;'' also modi?ed cata lystsrof' this type such as the mixtures‘ of alumie be introducedinto the reaction‘ zone in suchv rela tively small-amounts that any products resulting num halides with other metal'halides either in the solid or molten state, or the me. Particularly , from their decomposition would'have only a minor in?uence on'catalyst‘ activity, the'use ‘of aromatic effective catalysts‘ comprise aluminum chloride dissolved in 'a mixture of V'molten metal halides such- as, for instance, molten mixtures compris ing AiCls—NaCl—-.KC1, AlClse-SbCléf, VAlC13—- '40 matic nuclei‘fof which contain’ side ‘chains, the use of those containing not more than three and Other: suitable catalysts comprise a halide salt of preferably not more than two carbon atoms in thelongest unbroken side chain‘ is generally more aluminum in admixture with, a halide salt of a cyclic nitrogen base such as, for exam_ple,alu minum chloride in admixture with pyridine 'hy drogenfchlo'ride. _ ' ' i compounds, the 'aromaticnucleus of which'con tains long ‘side ‘chains, is'ge'nerally not" preferred. Thus of the-suitablehydrogen-donora'thé arc“ desirable. ' " ' ‘I e ‘ While no attempt is made to enumerate or ‘clas sify-zall of the aromatic ‘hydrogen-donors which may suitablybe used within the scope of the in ' fThe isomerization is preferably executed in the presence of a hydrogenjhalildepromoter, such as, for example, hydrogen chloride, The amount of 50 vention, the following are cited ‘as speci?c ex amples. Suitable phenolic-type hydrogen-donors hydrogen chloride used may vary widely in ac comprise, hydroquinone, pyrogallol, phloroglu cordance with operating conditions‘, In. general cinol; catechol, resorcinol, and the like, as well an amount of hydrogen chloride/equal to from as their homologues and analogues and suitable ‘ about'0.3%’ to about 40%‘ of the hydrocarbon charge is found to be su?icient. Higher propor +55 substitution "products vas " chlorhydroquinone, 'di chlorhydroquinon'efetc.1‘Suitable aromatic hy tions of the hydrogen chloride may, however, be drogen-‘donors comprising the amino group in-, used. The isomerization reaction may be exe cuted in either thervapor or liquid phase.’ Isom- ‘ clude'amino ‘phenol, 2-4 'diam'iriophenolQ para methyl aminophenol, 2-aniino-5-hydroxy toluene, erization of the more stable hydrocarbons such as, for example, the'conversion of butanev to isobu tane is generally preferably carried out in the vapor phase in the presence of a supported cata to lyst. ‘ Isomerization of the more readily degraded benzyl-para-aminophenol,aniline; ' ' ' " The amounts in which'the hydrogen-donor is to be introduced into the ‘reaction zonemay vary considerably-within the scope ‘of the invention, depending upon the nature "or the material’ treat hydrocarbons having at least ?ve carbon atoms to 65 ed, the speci?cvcatalyst used,‘ and ‘the ‘operating hydrocarbons‘ such as the open chain para?inic , . pentane ‘ and the "conditions. ' A signal'a’dvantage of the invention branched chain hydrocarbons is generally exe ‘cuted'inthe liquid phase. The temperature of materials which generally need- be ‘used to‘e'ffect the molecule, ' particularly operation is generally dependent upon the par ticular catalyst used and the nature of the hydro carbon, treated. When isomerizing' more stable hydrocarbons in the vapor phase, temperatures in the range of from about 50° 'CLto about 200° ‘C. / resides, however, in the- small amount of these substantial reduction of'hydrocarbon‘ decomposii tion-‘under the ‘prevailing 'vi'someriza'tion condi 'ftions; Addition of the“hydrogen-donor' in an amount equivalent toy from‘ about'0.001% to about 1% is'gene'rally found to ‘be suitable. "1 It is to'be understood, - however,""atliat'”the invention‘ is '_not and'preferably from about 80° C.‘ to‘ about l50f‘1C. are-generally’ employed. Isomerization ‘of the 75 necessarily‘limited to the‘intro'duction of any par 2,404,436 5 . ticular proportion of the hydrogen-donor to the reaction zone and substantially larger propor tions than those speci?ed above may be used. The hydrogen-donor may be added directly to the charge or may be introduced'separately into the reaction zone. the preparation‘ of aviation fuels from methyl pentane. The ability of the aromatic compounds within the above-de?ned class to inhibit hydrocarbon decomposition in the presence of aluminum hal ide catalysts has been attributed to the liberation of nascent hydrogen under the condition of exe cution of the isomerization reaction. Though a uniformly identifying characteristic of the aro matic compounds suitable as hydrogen-donors in the process of the invention is their ability to liberate hydrogen under isomerization conditions in the presence of Friedel-Crafts type catalysts, the invention is in no wise to be limited by any 15 theory advanced herein for the purpose of set ting forth more clearly and more fully the nature It may be added as such or in any other form comprising, for example, its solution or suspension in, or its admixture with a suitable medium. The addition may be made continuously or intermittently during the course of the operation. 7 Of the hydrogen-donors mentioned above the phenols, containing more than one hydroxyl group attached to the aromatic nuclei, such'as, for ex ample, hydroquinone, are somewhat preferred. The extent to which the ei’?ciency of the isomer ization process is improved by the presence of the aromatic hydrogen-donors is exempli?ed by the of the invention. following example: ~ ‘ We claim as our invention: 1. A process for isomerizing methyl pentane to 20 dimethyl butane ‘ which comprises contacting Example methyl pentane in admixture with hydrogen hal 2-methy1 pentane was treated with a molten ide at isomerizing conditions with a molten mix ture of halide salts containing an uncombined aluminum halide in the absence of any added mixture comprising 88.1% SbCls, 10.8% AlCla, and 1.1% NaCl at a temperature of 65° C. with a con tact time of 15 minutes and a ratio of catalyst to hydrocarbon of 1 to 5 by volume. Hydrogen 25 free metal in a reaction zone and avoiding sub stantial hydrocarbon decomposition by introduc ing into said reaction zone small proportions, not substantially in excess of about 1% by weight of the hydrocarbon feed, of uncombined hydro ‘ chloride in the amount of 36.5% by weight of the hydrocarbon charge was introduced into the re action zone. Analysis of the product obtained is shown in table A. The experiment was repeated ' -' under substantially identical conditions with the 30 quinone. 2. A process for isomerizing methyl pentane to exception that a trace of hydroquinone (substan~ dimethyl butane which comprises contacting tially less than 0.1%) was added to the 2-methyl methyl pentane in admixture with hydrogen hal pentane charged. Analysis of the product ob ide at isomerizing conditions with a catalyst com tained in the latter experiment is shown in 35 prising uncombined aluminum halide in the ab table B. sence of any added free metal in a reaction zone - Per cent isopentanc.-. A 28 sition by introducing into said reaction zone small proportions, not substantially in excess of about 3 25 Per cent neohexane____ l0 ' Per cent hexanes and heavier ____________________________ .. 37 and avoiding substantial hydrocarbon decompo B 1 40 42 54 1% by weight of the hydrocarbon charge, of an uncombined hydroquinone. - 3. In a process for isomerizing saturatedhydro carbons wherein an isomerizable saturated hydro 47% of the material shown as hexanes and heavier in table B consisted of unconverted 45 carbon having at least ?ve carbon atoms to the molecule is contacted at isomerizing conditions methyl pentane. ' ' in admixture with a promoting amount of hydro It is apparent from the foregoing example that genchloride with uncombined aluminum chloride the introduction of only traces of the aromatic in the absence of any added free metal in a hydrogen-donors into the reaction zone wherein the readily degraded methyl pentane was being 50 .reaction zone, the improvement which comprises introducing into said reaction zone small propor converted to dimethyl butane reduced the amount tions, not substantially in excess of about 1% by of hydrocarbon decomposition products from weight of the hydrocarbon charge, of uncombined about 53 per cent to about 4 per cent. It is fur hydroquinone, thereby avoiding any substantial ther to be noticed that the amount of the highly hydrocarbon decomposition. desirable neo-hexane (2-2-dimethyl butane) in 55 4. In a process for isomerizing normal and the product obtained was more than quadrupled. branched chain saturated hydrocarbons having To obtain anywhere near such a reductionin at least ?ve carbon atoms to the molecule to hydrocarbon decomposition with the aid of added branched and more highly branched chain sat hydrogen requires the use of a partial pressure of urated hydrocarbons respectively wherein said this gas of at least 300 pounds. This necessi- ~ tates the use of expensive high-pressure appa ratus and entails the increased cost and di?i 60 hydrocarbons are contacted at isomerizing con culties involved in maintaining and recirculating this gas within the system. It is thus readily apparent that the use of the hydrocarbon de ditions in admixture with a promoting amount of a hydrogen halide with a catalyst comprising an uncombined aluminum halide in the/absence of any added free metal in a reaction zone, the 65 improvement. which comprises introducing into invention permits the realization of substantial‘ savings in the cost of apparatus and operation. The particular advantages inherent in the inven tion are amply displayed in the ability to produce 70 more e?iciently and cheaply than heretofore d1 stantially in excess of about 1% by weight of the hydrocarbon charge, of uncombined hydro "composition ‘inhibitors in accordance with the , methyl butane (neohexane) ‘so highly desired in said reaction zone a controlled amount, not sub quinone, thereby avoiding any substantial hydro carbon decomposition. CHESTER C. CRAWFORD. DAVID LOUIS 'YABROFF.