| 摘要 |
In the isomerisation of a hydrocarbon in the presence of hydrogen and a catalyst prepared by vaporising a Friedel-Crafts metal halide onto a refractory oxide support carrying a hydrogenation catalyst and thereafter heating at above 300 DEG C. to remove unreacted Friedel-Crafts halide, the feed used contains at least one of oxygen-, sulphur-and nitrogen-containing impurities in catalyst deactivating amounts and the amount of such impurities is reduced below deactivating levels before the isomerisation step. The feed is first treated to reduce the nitrogen level below 10 p.p.m. and the sulphur level below 10 p.p.m. by contact with sodium plumbite, hypochlorite or alkali or preferably by hydrogenation in the liquid or vapour phase over a metal, or oxide or sulphide thereof, of Group VIa or VIII of the Periodic Table supported on an inorganic oxide or clay, e.g. at 40-425 DEG C. and up to 135 atmospheres. After separation of the hydrogen together with hydrogen sulphide and ammonia the water level is reduced to below 5 p.p.m. by distillation and/or treatment with liquid or solid drying agents. The Friedel-Crafts halide may be aluminium bromide or chloride, antimony pentachloride, beryllium bromide or chloride, ferric bromide or chloride, gallium trichloride, stannic bromide or chloride, titanium tetra-bromide or -chloride, zinc bromide or chloride or zirconium chloride and forms 2-25% of the refractory oxide containing the hydrogenation catalyst which may be a metal of Group VIa or VIII. Isomerisation is effected at 100-300 DEG C., a pressure of 3.5-100 atmospheres, with a hydrogen to hydrocarbon mol ratio of 0.25-10:1, an LHSV of 0.25-10 using fixed, moving or fluidised catalyst beds. Hydrogen halide may be added and also naphthenes and/or aromatics if desired. Unreacted material may be separated and recycled. Paraffins, naphthenes or alkylaromatics may be isomerised. |
