GB618455A - Improvements relating to the synthesis of hydrocarbons and other compounds from mixtures of carbon monoxide and hydrogen - Google Patents

Abstract

Hydrocarbons and small amounts of oxygen-containing compounds are synthesised from a feed gas containing carbon monoxide, hydrogen, and olefins at a pressure of 1-50 atm. in the presence of cobalt at 170-250 DEG C. or iron at 200-310 DEG C., if desired on supports or with promoters. The olefins are normally gaseous or of gasoline boiling range, and normally constitute not more than 30 per cent of the combined feed. They may be admixed with inert gases or paraffins. Synthesis may be effected in two or more stages, olefins being added in the first and an effluent gas produced of a higher CO : H2 molar ratio yielding olefinic products in the later stages. Thus, in the first stage CO : H2 is from 1 : 1.2 to 1 : 2. After 50 per cent CO conversion and separation of C4 and above, the effluent passes to a second stage with sufficient initial gas to give a CO : H2 ratio of 1.25 : 1. The ethylene-propylene content of the feed should be at least 2, preferably at least 5 moles. per cent of the CO and H2. A C2-C3 fraction of cracked petroleum is a suitable olefinic feed. Mixtures of CO and H2 may be produced by partial combustion of hydrocarbons, preferably methane. Effluent gas from the synthesis may be reacted with oxygen to yield further CO and H2. In examples, the added olefin is diisobutylene, ethylene, propylene or normal butenes, and the catalyst cobalt, thoria, magnesia, kieselguhr. Temperatures vary from 190 DEG to 250 DEG C., and pressure is atmospheric. The products comprise gasolene fractions of high olefin content and branched chain hydrocarbons.