GB730055A - Improvements in or relating to the isomerisation and/or dehydrogenation of hydrocarbons - Google Patents

Abstract

Hydrocarbons are isomerized and/or dehydrogenated by contacting in vapour phase under reaction conditions, in the presence of hydrogen and steam, with a catalyst consisting of platinum on a support consisting of or containing a component having cracking activity, said catalyst containing less than 0.1 per cent by weight of chlorine. The isomerization of butane, pentane, decane, paraffin wax, synthetic hydrocarbon lubricating oil, ethyl benzene, and dimethyl-cyclopentane, the dehydrogenation of naphthenes to aromatics, and the conversion of C6 and C7 fractions to gasoline and aromatics are referred to. The support is preferably a clay-type catalyst, e.g. acid-treated montmorillonite, silica-alumina, silica-zirconia, silica-boria or alumina. Steam equivalent to 5 mol. per cent of the hydrocarbon feed is generally sufficient but amounts from 2-100 mol. per cent may be used. The amount of hydrogen is generally at least 1, e.g. 4-10, and may be up to 100 or more mols. per mol. of feed. Isomerization temperatures are generally about 250-475 DEG C. Where dehydrogenation is also desired, 455-595 DEG C. is generally used but, with a large excess of steam, up to 650 DEG C. is feasible. Pressure may vary up to about 100 atmos. A higher conversion may be obtained by increasing the cracking activity of the catalyst, e.g. by using a cracking catalyst of larger avaliable surface or incorporating a higher content of cracking promoter which may be alumina, silica, boria or fluorine. Thus, a catalyst containing 0.15-0.6 per cent Pt, 0.2-0.7 per cent Cl2, and 0.1-2 per cent F, balance Al2O3, is prepared by treating alumina with a fluoriding agent, e.g. aqueous fluoboric acid, and impregnating with a solution of chloroplatinic acid saturated with H2S. Alternatively, a similar catalyst but containing 8-25 per cent alumina, balance silica, is prepared by steaming a silica-alumina catalyst to reduce the surface to 100 s.m./g. and impregnating as above. In either case chlorine may then be removed and, if required, the catalyst subsequently fluorided. Alternatively a fluoriding agent may be added to the feed or carrier gas. Chlorine removal may be effected with aqueous nitric acid. Examples illustrate the conversion to benzene of methylcyclopentane or a fraction containing it with cyclohexane and benzene, and the isomerization of n-hexane, comparative figures being given using platinum-alumina catalysts containing above and below 0.1 per cent chlorine, together with fluorine, and with or without steam.ALSO:Catalysts for isomerizing and/or dehydrogenating hydrocarbons in vapour phase, in the presence of hydrogen and steam, consist of platinum on a support consisting of or containing a component having cracking activity, said catalyst containing less than 0.1 per cent by weight of chlorine. The support is preferably a clay-type catalyst, e.g. acid-treated montmorillonite, silica-alumina, silica-zirconia, silica-boria or alumina. Steam equivalent to 5 mol. per cent of the hydrocarbon feed is generally sufficient but amounts from 2-100 mol. per cent may be used. The amount of hydrogen is generally at least 1, e.g. 4-10, and may be up to 100 or more mols. per mol. of feed. Isomerization temperatures are generally about 250-475 DEG C. Where dehydrogenation is also desired, 455-595 DEG C. is generally used, p but with a large excess of steam, up to 650 DEG C. is feasible. Pressure may vary up to about 100 atmos. A higher conversion may be obtained by increasing the cracking activity of the catalyst, e.g. by using a cracking catalyst of larger available surface or incorporating a higher content of cracking promoter which may be alumina, silica, boria or fluorine. Thus, a catalyst containing 0.15-0.6 per cent Pt, 0.2-0.7 per cent Cl2, and 0.1-2 per cent F, balance Al2O3 is prepared by treating alumina with a fluoriding agent, e.g. aqueous fluoboric acid, and impregnating with a solution of chloroplatinic acid saturated with H2S. Alternatively, a similar catalyst but containing 8-25 per cent alumina, balance silica is prepared by steaming a silica-alumina catalyst to reduce the surface to 100 m/g. and impregnating as above. In either case chlorine may then be removed and, if required, the catalyst subsequently fluorided. Alternatively a fluoriding agent may be added to the feed or carrier gas. Chlorine removal may be effected with aqueous nitric acid.