‘I. i" a ‘l " 2,819,322 United States Patent l M116 “Patented Jan. 7., “1958

.11 .2 catalysts for the process, particularly‘the group VI metal sul?des, as, for example, the sul?des of tungsten, molyb ‘2,819,322 denum and chromium, and the sul?des of metals of atomic number from 25 to 28, especially nickel sul?de. PRODUCTION OF AROMATIC COMPOUNDS l ‘Composites of a metal sul?de from each of these. groups Lloyd C. Fetterly,”El'Cerrito, Cali?, a'ssigno'r to Shell Del are especially preferred. Corresponding oxides and com velopment Company, New York, N. Y., a corporation posites thereof are also suitable catalysts for'the'present of Delaware purpose, as well'as composites of oxides and sul?des. No Drawing. Application December '21, 1953 ‘ The diaryl methane compounds which are to be cracked 10 in accordance’with the invention, in generalare prepar Serial No. 399,570 able by the “alkylation” of the corresponding aryl com 9 Claims. (Cl. 260—668) pound with formaldehyde. ‘For example, it is known to prepare diphenylmethane, ditolylmethane " (mixture of isomers) and dixylylmethane, by reacting the correspond This invention relates to’ thepro'duction of methylaro 15' ing benzene/compound with formaldehyde in- the pres matic compounds,‘ and more'particularly to the produc ence of an acidic catalyst, such as sulfuric acid. _Simi tion of such‘compounds‘which contain a further alkyl larly, other compounds can be prepared,- such as di-beta radical, such as a second methyl radical, such as para 1 naphthylmethane from naphthalene, ~di§beta-5,6,7,8-tetra xylene, 2,6-dimethylnaphthalene and 'durene. 'hydronaphthylmethane from tetralin, 'di—2,4,5-trimethyl Various methods have been proposed for the prepara .20 phenylmethane from pseudocumene, bis-(2,4-dimethyl tion of such compounds vas the methylbenzene com phenyl)methane from meta-xylene, bis-(betaaG-methyl pounds. Thus, it has been proposed to chloromethylate naphthyl)methane and bis-(beta-7-methylnaphthyl)meth toluene to chloromethyltoluene (alpha-chloro-xylene) and ane from beta-methylnaphthalene. , > then to replace the chlorine by hydrogen, to obtain the Other diarylmethane compounds to; be converted-by net result of the substitution of a methyl radical for a 25 the present invention can bemade by theindicated alkyla nuclear hydrogen atom in a substituted benzene. On the ‘ tion with formaldehyde, as will‘ be understood. In gen ‘other hand, it has been proposed to alkylate aromatic eral, the diarylmethane compound is‘ preterablyrvolatile hydrocarbons in vapor phase with methanol, in the pres ‘at the conditions of the reaction to be utilized. ence of a phosphoric acid catalyst. ‘However, none-of 'As ‘already indicated,the'diarylmethane compounds, the methods previously proposed for [the “methylation” 3.0 ~which may be represented by the iformula‘Ar-éCHz-éAr’, of aromatic compounds has proven to be entirely satis wherein the “Ar” groups are usually the’ same aryl, radi factory, for one reason or another. The methods here cals having the same'empirical formulas, although they tofore available have failed to provide a simple, effective -may be diiferent position isomers ‘and can be even dif and economic method for the methylation of a given aro~ fferent types of radicals, are cracked inthe practicelof the matic compound to form the monomethyl‘ derivative 35 invention, with hydrogenation, ‘to yield two substances, thereof. one an arylmethane (AI‘—-CH3) and the other‘ a corre It is, therefore, a principal object of the present inven "nsponding aryl compound, Ar'H. The gross reaction can tion to provide an improved process forthe production ‘be-represented by the equation =of methyl-substituted aromatic compounds. A’ further AT—CH2--AI'+H2=AI§CHs+1AI'H ‘object is to provide, an improved process for ‘the intro 40 :duction of a methyl radical in substitution for a nuclear Thus,v the‘ not result of the reaction ‘is-:the cleavage-pf La hydrogen atom of an aromatic compound. A more ‘spe -, C-—-C'bond between the methylene (—€Hz-—) - carbon and ci?c object of the invention is to provide an e?ectivegand . a carbon atomof one of thearomaticringsand a satura economicalmethod' for the production of’ nuclear methyl tion withv hydrogen of the‘ two .bond fragments. ‘The derivatives of benzene and naphthaleneivand of benzene ‘kinetics or methanism whereby this result; is-effeetedis compounds and naphthalene compounds. A ‘still-more not clear, although it is considered.to-involvo-more than speci?c object is to provide a method for the conversion a mere carbon-to-carbon cleavage and hydrogenation. In of aromatic compounds which contain benzene or naph any case, the invention is not to be limited by any theory as to its operation. thalene nuclei and only hydrogenlatoms and/or lower In the preparation of diarylmethanes by alkylation of hydrocarbon radicals (1 to 6 carbon atoms), attached 50 to nuclear carbon atoms of the benzene and naphthalene aromatic compounds with formaldehyde,» particularly the nuclei, into nuclearly substitutedmethyl derivativeslthere alkylation of alkylaromatics (e. g., toluene), generally of. A particular'object is to provide‘a practical method there will be produced more or less of further alkylation for the synthesis of durene. These‘objects will be better products thereof. Thus, some of‘the'diarylmethanecom pound is converted into a triarylv dimethane compoundha understood and others will become apparent from ‘the 55 detailed description of *the invention. so-called “trimer,” represented by ' ' Now, in accordance with the-present invention, ithas been ‘found that diarylmethane (Ar2CH2) compounds These diarylmethane (arylmethyldiarylmethane) .-_.com (methylenediaryls) can‘be converted ‘into corresponding pounds are also cracked in the samepmanneryand, under arylme'thane (ArCH3) compounds and aryl‘ (ArH) com 60 ‘similar conditions to yield .two;;molecu1es-».of~methy1 pounds by cracking the compounds in, admixture with hy aromatics and one molecule of _the~- original aromatic. drogen with hydrogenation at an elevated temperature and 'Evenhigher polymers are crackedgsimilarly. ~-It is con pressure-and in contact ‘with a catalyst active'foraryl .templated, in the present invention to crackthe mixture "methylene-carbon and'a‘r'yl-carbon linkage cleavage and of dimer, trimer and other polymerswhich ‘maybe .ob "having hydrogenation activity. ~'In_general the high melt~ 65 tained by ‘the alkylation, the polymer ‘preferably being ing compounds of‘thegroup-VI-VIII metalsrhaving an , .kept to a minimum. atomic number of at: leasti-24:~;jare suitable, particularly .-An examination of the equations for the-reactions for ' the variable valence metals. A particularly suitable cata '(1) the formation of the. dimer and ,(2):>the~cra_cking= o lyst‘forthispurposeis, forle'xample, a tungsten-nickel sul?de' catalyst such as is utilized commercially forv the dehydrogenation of-méthylcyclohexane 10'10111311‘3- {The 70 dehydrogenating metal sul?des are a preferred class "of _. (2). 2819,3255 shows that the overall result is the conversion of one thus giving by hydrocracking primarily durene as the mole of aromatic compound (ArH) to one mole of tetramethyl benzene compound, one molecule of pseudo corresponding methylaromatic or arylmethane (ArCH3) cumene being regenerated. A minor portion of the for each two moles of initial aromatic feed. However, Pseudocumene goes to bis-(2,3,5-trimethylphenyl)-meth one mole of the aromatic compound is produced in the ane, which on hydrocracking yields isodurene and pseu second stage, which can be recycled to the ?rst stage. documene. And a further minor portion alkylates to Thus, the theoretical net consumption of aromatics is the mixed Cm-isomer, 2,2’,3,4’,5,5’-hexamethyldiphenyl one mole for each mole of desired methylaromatic pro methane, some of which on hydrocracking yields durene, duced. Therefore, a preferred method of practicing the in addition to “regenerated” Pseudocumene, while the invention comprises: (1) alkylating the aromatic com 10 other yields isodurene, depending on which aromatic pound, such as toluene, with formaldehyde to produce ring is cleaved from the methylene carbon atom. The the diarylmethane (ditolylmethane), which will normal mesitylene alkylates essentially to only one dimer, bis~ ly be a mixture of isomers (p-p’, o-p, m-p) predominat (2,4,5-trimethylphenyl)methane, which hydrocracks to ing in the p-p' isomer; (2) cracking the diarylmethane isodurene and mesitylene. The hemimellitine present product, either the total alkylate, or the portion from 15 alkylates to three dimers, which hydrocrack to “regen which the higher polymers have been removed, as by erate” hemimellitine and a mixture of isodurene and distillation, to yield a mixture of isomeric methylaromatic prehnitene. The “regenerated” trimethylbenzenes are compounds (xylenes, predominantly the para-isomer) and readily separated by distillation and recycled to the of corresponding aromatic compound (toluene); (3) sepa alkylation, where desired. The durene (M. P. 79-80" rating the produced methylaromatics from “regenerated” 20 C.) is readily crystallized in good yield from the isodurene aromatic as by distillation whereby the “regenerated” (M. P. —24° C.) and prehnitene (M. P. ——4° C.) in aromatic (toluene) is recovered as overhead distillate; the separated fraction. (4) and recycling the “regenerated” aromatic to the The cracking-hydrogenation of the diarylmethanes is alkylation step. When the alkylation results in an ap readily effected by passing a suitable mixture of the feed preciable proportion of polymer, for example, tetramer 25 alkylate and hydrogen over the heated catalyst at a suf and higher, it is preferable to separate the polymer as ?ciently elevated temperature and under a suitable super by distillation, and to crack the fractions separately un atmospheric pressure. A broad range of mole ratios of der somewhat different conditions, because of the greater hydrogen to alkylate can be utilized, in general a ratio tendency of the higher boiling materials to deactivate the of from about 1 to about 20 being suitable, with a ratio catalyst under the same conditions. The cracked streams 30 of from about 2 to 10, and particularly about 4 or 5, are then combined and processed together. giving especially satisfactory results. The temperature In the preparation of xylenes, the separated xylene in the reaction zone is advantageously maintained at isomer mixture can then be de-orthoized, as by distilla about 400-450“ C. with a pressure of about 250°-275 tion, and the para-xylene readily recovered in high yield p. s. i. g., although higher and lower temperatures such and substantially pure. 35. as 500° C. and 350°., respectively, are effective with pres The invention is of particular utility for the production sures which may be from about 100 p. s. i. g. to about of durene, wherein pesudocumene is alkylated and the 500 p. s. i. g., or even lower or higher. A contact time dipseudocumylmethane is hydrocracked to durene and corresponding to a liquid hourly space velocity (LHSV) pseudocumene. The Pseudocumene can be prepared of about 5 has been found to be particularly effective ale from meta-xylene by alkylation with formaldehyde and 40 though the space velocity may range suitably from a hydrocracking the alkylate, di-meta-xylylmethane (di-(2,4 ,value as low as about l-LHSV to as high as about 20 dimethylphenyl) methane), by the process of this inven LHSV. It will be understood that the optimum set of tion. Pseudocumene is also readily available in certain conditions will depend on a number of variable factors, re?nery streams, such as bottoms by-product streams including the particular catalyst employed, the particular from the production of aromatics, including xylenes, by alkylate feed and whether it is a single compound or a various hydroforming operations. Thus, an illustrative mixture of polymers, the particular apparatus employed, re?nery xylene bottoms by-product having a precision and the like. boiling range of about 150° C. to 205° C., has the com The cracking-hydrogenation of the diarylmethanes is position as shown in Table I, with the boiling points slightly exothermic in character (AH-=ca. 18,000 B. t. u./ being given for the individual components. 50 lb. mol H2 reacted) although usually of such a small amount that no particular problem of heat removal is TABLE I presented. The feed mixture of alkylate and hydrogen Composition of xylene bottoms is normally preheated to about the reaction temperature prior to contacting it with the catalyst. Component Percent 65 The reaction can be suitably carried out by passing v. at 1 atm. the alkylate and hydrogen over or through a ?xed bed or mass of the catalyst in particulate form, such as a 53 ‘ 169. 3 19 164. 8 bed of pellets or a packed section thereof in a con?ned 9 176.1 reaction zone. On the other hand, the reaction can be Propsylbenzene: 152 o ______60 readily carried out by passing the preheated mixture of N ______. } 7 l 159 alkylate and hydrogen through a ?uidized catalyst mass, Methyl Ethyl Benzenes ..... -_ 5 160464 Ow-Arnmatins 182-204 and the temperature of the catalyst mass can be readily controlled by any suitable means, such as by providing heat transfer tubes disposed in the catalyst zone or by By fractional distillation, the three trimethylbenzenes are 65 cycling a portion of the catalyst to an external heat ex easily concentrated further in a heart cut. By making changer and back to the reaction zone. the fractionation su?iciently sharp, a large proportion of The following detailed description of illustrative exam the hemimellitine is also readily rejected from the pseu ples of the practice of the invention are given for the documene concentrate, so that the concentrate is com purpose of a better understanding thereof and are not prised essentially of pseudocumene and mesitylene with to be considered as limitative thereon. a very small proportion of hemimellitine and only a small 70 proportion, not over about 1~2% , of methyl ethyl benzene. EXAMPLE I This pesudocumene concentrate is then alkylated and (A) Alkylation of toluene-Toluene was alkylated the resulting alkylate is hydrocracked in accordance with with aqueous 37% formaldehyde (formalin) using aque the invention to yield durene. The pseudocumene alkyl ous 60-70% sulfuric acid as catalyst at 80° C.-100° C. ates primarily to the bis-(2,4,5-trimethylphenyl)methane, and 10-30 minutes contact time. The recovered alkylate amazes‘ a -1 . . 6 in this case consisted of ditolylmethane (DTM), tritolyl recrystallized hadjthe following properties: melting'point, d-imeth'ane (dimer), and heavier polytolylpolymethane 70—72° (2.; mol; wt.=ca. '250; molecular formula-4 in a weight ratio‘ of 62:12:26,- respectively. The yield of CmH‘zg. From analyses, including the fact that the tetra; mixed alkylate was 99-100%, based on toluene converted methylbenzene product obtained by cracking it by the and 95,-100%,- based upon the, formaldehyde. Since process of this invention ‘was predominately durene, this the sulfuric acid is relatively dilute,‘ little if any sulfonaa product was considered to be predominately bis-(2,4,5 tion of toluene or product occurred and acid consumption trime‘thylphe‘nybmet‘hane. About 8% by weight of isoa‘ was negligible. , v meric material was obtained, an approximately equal‘ The dimer, trimer and higher polymer are readily sep mixture of the \isomers, bis‘-(2,3,5-trimethylphenyl)-’ arable by distillation. The dimer (DTM) fraction con 10 methane and 2,2’,3',4’,~5,5'-hexamethyldiphenylmethane. tained an isomer distribution of approximately 60% pp’, 35% o-p' and 5% mp’, as determined'by infrared anal EXAMPLE II yses and- from analyses» of the products from subsequent (A)' Ditolylmethane was hydr'ocracked in admixture cracking in accordance with the invention. With hydrogen by passing it over a tungsten-nickelesull (B), Alkylation of toluene.—Toluene was valkylated 15 ?de pelleted catalyst at 400° C., 260 p. s. i. g. pressure, with‘ formaldehyde in the’ presence of a sulfuric acid,» LHSV of 5 and a hydrogen to ditolylmethane mole methanol, water mixtureeand- summarized in the follow ratio of 4. The feed was, 50 to 75% converted to other ing. tabulation: products with 100% yield. The hydrocracking was car ried out by vaporizing the ditolylmethane, mixing it with Temperature ____~_-__;_~__-._ 90-100“ C. 20 the hydrogen, preheating the mixture to about the re; Pressure ____ _..'___-__~__.__t_ Atmospheric. action‘ temperature, and passing the mixture over the Catalyst composition, per catalyst packed vin a steel reaction tube, while maintain= cent W ______..._‘___'.._' CH3OH°—-20. ing the temperature at the selected value. The product was‘. fractionated by distillation with the recovery of Product distribution, percent 25 61% w. low boiling fraction'which contained 53% xylene w. __'__' ______»_____‘____> Dimer-81. and 46% toluene and 39% w. higher boiling components Trimer-—14.4; comprising predominantly dimer and trimer (88: 12 ratio) .' Higher mol wt. 4.6. The? xylene product isomer distribution was about 75 % Yield based on toluene___.. 96.9% m. p-xylene, 22% ortho-xylene and 3% m-xylene. Yield based on formaldea 30 (B) A portion of the total alkylate of Example I-A hyde _> ______Y.._ 96.4% m. was hydrocracked under the same conditions as in IL-A. Methanol recovery ______-__; 57+percent m. as"CH3OH.1 In this case the total yield of low boiling productwas 41% m. as CH3OH—~H2"SO4 32% by weight, containing 63% w. xylene and 37% _w. reaction‘ product. toluene, and 68% higher boiling material. The fact that Sulfuric acid recovery____._ 66.7% w. as titratable acid. 35 the xylene content was greater than the toluene content 33.3% w. as CH3OH—'-‘ is the result of cracking of alkylates higher than “dimer.” H2804. Thus, a “trimer” yields two mols of xylene per mol of Reaction‘ time ______.‘__~ 20 minutes.’ toluene. . Conversion of toluene____.. 45% w. EXAMPLE III (C) Alkylation‘ of t0luene.—When toluene was" al The recrystallized bis-(2,4,5-trimethylphenyl)methane kylated with formalin to a‘ 23.5% alkylate level (con: product from Example l-E, and having a melting point of version) in toluene with a reaction time of'30 minutesv 70-72° C. was hydrocracked over a W/Ni/S ‘catalyst at and using a 1:1 volume mixture of 96% H'2SO4 and meth about 450° C., a pressure of about 600 p. s. i. g. and a anol as catalyst, the distribution ratio of 85:15':0 for mole ratio of hydrogen to alkylate of 10 to 1, respectively. di'rn'erztrimerzhigher, respectively, was obtained. The 45 Durene was recovered from the product in a yield of yield of product, based upon'toluene and formaldehyde above 95% based on the pseudocumene alkylate con converted, was above 96%‘. I ' p verted, at a conversion level of about 91%. The other A product having a distribution ratio 90:7:3 of product was essentially all pseudocumene, with a very dimer‘itr'irnerzpolymer was obtained at a 41% alkylate‘ small proportion of isodurene and prehnitene being level‘ and a- reaction; time of 15' minutes when‘ using a’ 50 present. 1’~' .ll'volunie'» ratio of 96% HQSO; and methanol as'cat EXAMPLE IV '‘ yet") (D) Alkylation of xylenes.-—The three isomeric xye The remainder of the pseudocumene alkylate from Ex lenes, 0-, m- and p-, were separately alkylated with form ample I-E was hydrocracked similar to Example III. The aldehyde, using/sulfuric acid‘ as‘catalys't in aqueous meth~ product from the cracking was predominantly durene with anol solvent. The-product distributions in the alkylates of 55 minor proportions of isodurene and prehnitene, but larger the'three cases are tabulated in Table H. proportions than in Example III, in addition to pseudocu mene. I TABLE II EXAMPLE V When a 162° C. to 173° C.distillate fraction from a‘ re; Methyl Posi- ' 60 Xylene Alkylated tions on Percent, ?nery xylene bottoms product, as described in Table I,‘ mol and containing about 90% pseudocumene‘ is alkylated with formaldehyde in the presence of sulfuric acid— aqueous methanol as catalyst, an alkylate product com 65 prising essentially “dimers” is readily obtained. The hy IOCF08 drocracking of this “alkylate” over a W/Ni/ S catalyst un m-xylene _ _ _ { der a pressure of about 600 p. s. i. g. and at a temperature p-xylen e NNNNN 10 GHQ of about 450° C., with a mole ratio hydrogen/alkylate of about 5, yields a mixture composed essentially of tri (E) Alkylation of pseud0cumene.—-Pseudocumene 70 and tetra-methylbenzene compounds. The trimethylben (1,2,4-trimethylbenzene) was alkylated with formalde zenes are readily separated by distillation as distillate for hyde in the presence of aqueous methanolic sulfuric acid recycle to alkylation, to give a residual mixture composed as catalyst, at a temperature of 50-80° C. and a reaction essentially of durene, isodurene and prehnitene. The time of 20 minutes. A yield of 99%, based on converted durene is readily recovered in a yield of about 83 mol pse'udocumene, was obtained, of a product which, when 76 percent, based on trimethylbenzenes consumed. 3,819,822 7 About 17 mol percent of a mixture of isodurene and polymethylbenzene is pseudocumene and the diarylmeth: prehnitene are recovered, being about 10% isodurene and ane is di-(2,4,-dimethylphenyl)methane. 7% prehnitene. The prehnitene (M. P.=-4° C.) and, 4. A process for the preparation of durene which com isodurene (M. P.=-24° C.) are separable by fractional prises hydrocracking bis-(2,4,5-trimethylphenyl)methane crystallization. at an elevated temperature and a pressure from about 100 EXAMPLE VI to about 600 lbs./sq. in., gauge, in the presence of from about one to about twenty moles of hydrogen per mole When the mixture of isodurene, prehnitene and unsep of bis-(2,4,5-trimethylphenyl)methane and a high melt arated durene from Example V is alkylated with formal dehyde and alkylate, bis-(2,3,4,6-tetramethylphenyl)meth ing inorganic compound selected from the group consist 10 ing of oxides, sul?des and composites thereof of group ane is obtained which has a melting point above 150° C. VI and VIII metals having atomic numbers of at least 24, and is slightly soluble in toluene. When this alkylate is as catalyst. hydrocracked similar to the process of Example V, penta 5. A process for the preparation of a polymethylben methylbenzene is obtained as product admixed with a zene having from three to ?ve methyl groups which com mixture of isodurene, prehnitene and durene. The penta prises hydrocracking a diarylmethane in which each aryl methylbenzene (M. P. 53'’ C.) is readily recovered by group is a methyl substituted phenyl group having from crystallization and ?ltration or centrifugation. two to four methyl group substituents at a temperature EXAMPLE VII of from about 350° to about 500° C. and at a pressure from about 100 to about 600 lbs/sq. in., gauge in the Hydrocracking of bis-(6( or 7)methylnaphth-2-yl)meth 20 presence of from one to twenty moles of hydrogen per ane. When beta-methylnaphthalene is methylated with form mole of diarylmethane and a tungsten-nickel-sul?de cata aldehyde, utilizing methanolic sulfuric acid as catalyst, a lyst. mixture is obtained composed essentially of.bis-(6(and 7)~ 6. A process for the preparation of pseudocumene methylnaphth-Z-yl)methane and the mixed isomer thereof, which comprises hydrocracking di-(2,4-dimethylphenyl) namely, 6,7'-dimethyl-naphth-2-yl methane. Hydrocrack 25 methane at an elevated temperature and a pressure from ing of this product under the conditions of Example V about 100 to about 600 lbs/sq. in., gauge, in the pres ence of from about one to about twenty moles of hydro yields predominantly a mixture of 2,6 and 2,7-dimethyl gen per, mole of the methane compound and a trungsten~ naphthalene, in addition to the “regenerated” beta-methyl nickel-sul?de catalyst. naphthalene. 30 7. A process for the preparation of durene which com EXAMPLE VIII prises hydrocracking bis-(2,4,5-trimethylphenyl)methane When di-p-tolylmethane is hydrocracked under condi at an elevated temperature and a pressure from about 100 tions similar to those of Example II, but the catalyst is to about 600 lbs/sq. in., gauge, in the presence of from pelleted molybdenum disul?de instead of the tungsten about one to about twenty moles of hydrogen per mole nickel-sul?de catalyst, similar results are obtained but at 35 of the methane compound and a tungsten-nickel-sul?de a slightly different conversion. catalyst. EXAMPLE 1X 8. A process for the preparation of pentamethylben zene which comprises hydrocracking bis-(2,3,4,5-tetra When Example II is repeated except that the catalyst methylphenyl)methane at an elevated temperature and charged to the reactor is a mixture of nickel and tungsten a pressure from about 100 to about 600 lbs./ sq. in., gauge, oxides (nickel tungstate) and a small amount of hydro in the presence of from about one to about twenty moles gen sul?de is incorporated in the feed stream (about 1 of hydrogen per mole of the methane compound and a mol percent), the ditolylmethane is hydrocracked in essen tungstenanickel-sul?de catalyst. tially the same manner as in Example II. 9. A process for the preparation of a polymethylben EXAMPLE X zene having from three to ?ve methyl groups which com When Example II is repeated except that the catalyst prises hydrocracking a diarylmethane in which each aryl employed is a composited cobalt oxide-molybdenum ox group is a methyl substituted phenyl group having from ide (Co/Mo/O) catalyst, the di-p-tolylmethane is readily two to four methyl group substituents at a temperature of from about 350° to about 500° C. and at a pressure converted in similar proportions to paraxylene and toluene. 50 The invention claimed is: from about 100 to about 600 lbs/sq. in., gauge in the l. A process for the preparation of a polymethylbenzene presence of from one to twenty moles of hydrogen per having from three to ?ve methyl groups which comprises mole of diarylmethane and a cobalt-molybdenum-oxide hydrocracking a diarylmethane in which each aryl group catalyst. is a methyl substituted phenyl group having from two to ' References Cited in the ?le of this patent four methyl group substituents at an elevated tempera ture and a pressure from about 100 to about 600 lbs/sq. UNITED STATES PATENTS in., gauge, in the presence of from about one to about 2,338,973 Schmerling ______Ian. 11, 1944 twenty moles of hydrogen per mole of diarylmethane and 2,394,751 Cole ______.._ Feb. 12, 1946 a high melting inorganic compound selected from the (it) 2,414,620 Trimble ______.._ Jan. 21, 1947 group consisting of oxides, sul?des and composites there 2,660,572 Feasley ______.._ Nov. 24, 1953 of of group VI and VIII metals having atomic numbers of at least 24, as catalyst. OTHER REFERENCES 2. A process in accordance with claim 1, wherein the Globus et aL: Journal of Applied Chemistry (U. S. temperature is from about 350° to about 500° C. 65 S. R.), vol. 17, pages 623-628 (1944). (Abstracted in 3. A process in accordance with claim 1, wherein the Chemical Abstracts, vol. 40 (1946), column 21333-5.)