| 摘要 |
The acid-catalysed conversion of hydrocarbons, e.g isomerization, alkylation, disproportionation or polymerization, is effected in the presence, as catalyst, of hexafluoroantimonic acid (HSbF6) or a hydrocarbon derivative thereof (RSbF6) which catalyst may optionally contain, per volume, not more than 6 volumes of a diluent. The catalyst is prepared from antimony pentafluoride or pentachloride and hydrogen fluoride, if the chloride is used the product should contain at least 38% by weight fluorine, and hydrocarbon derivatives may be prepared by reaction of the acid and hydrocarbon. Preferably a naphthene such as methylcyclopentane, in situ if desired. Preferred diluent which should be free from water, is hydrogen fluoride, fluorohydrocarbons may also be used. Reactions are preferably effected at below 100 DEG C. and is low as -20 DEG C. with the catalyst in the liquid phase, using batch or continuous operation with mixing the hydrocarbons being the continuous or dispersed phase. In continuous operations one or more reactors are used with cocurrent, countercurrent or cross-current flow, and with a temperature gradient if desired. The reactors should be made of or lined with materials not corroded by hydrogen fluoride. Isomerization reactions referred to are of paraffins, e.g. normal paraffins to iso-paraffins and light naphthas or straight run tops to high octane fuel blending components of naphthenes, e.g. methylcyclopentane to cyclohexane and of ethylcyclohexane to a product which on dehydrogenation contains a high proportion of m- and p-xylenes, and of polyalkyl aromatic hydrocarbons, particularly xylenes. In the isomerization of paraffins, unsaturated compounds, sulphur, benzene and water are preferably removed, e.g. with spent catalyst, and isobutane is preferably added in an amount of 5-25% by weight of hydrocarbon feed. Hydrogen, e.g. 1-3% mol. may be added to reduce disproportionation provided reduction of the catalyst does not occur. The disproportionation of toluene to benzene and xylenes may be effected. The alkylation of paraffins with olefins, e.g. of isobutane with ethylene can be effected at below 0 DEG C. thereby reducing isomerization of the product. |
