GB710339A - Improvements in or relating to the synthesis of hydrocarbons and catalysts therefor - Google Patents

Abstract

Olefinic hydrocarbons are produced from a synthesis gas containing CO and H2 and substantial amounts of N2 by contacting at 450-650 DEG , preferably 550-650 DEG F., and 50-100, preferably 55-75 p.s.i.g., with a dense turbulent fluidized catalyst comprising iron on active carbon and promoted with an alkali metal compound. Such catalysts give H2/CO consumption ratios greater than the ratio in the feed whereby a once-through operation can be used with synthesis gas obtained by partial oxidation of natural gas and having a H2/CO ratio of 2 : 1. In view of the low pressure required, the synthesis gas may be produced by oxidation of coal or natural gas with air at similar low pressures. The synthesis may be effected with a gas throughput of 2-20 c.ft./lb. of catalyst/hr. at a linear velocity of 0.1-3 ft./sec. The preferred catalysts comprise 10-20 per cent reduced iron and 0.4-1 per cent promoter, e.g. potassium carbonate. The iron is distributed over the active carbon as by impregnation or by thermal decomposition of iron carbonyl. Natural gas is oxidized with air at 2000-2500 DEG F., the lower part of the reactor containing a reforming catalyst such as nickel or copper on alumina to convert any CO2 and H2O formed back to methane. The synthesis gas passes to a reactor containing powdered catalyst which is fluidized by the upward flow of gas. Liquid products are separated while the gaseous hydrocarbons may be recovered by adsorption in active carbon also in fluidized form. Where synthesis gas is obtained from coal, a further conversion to increase the H2/CO ratio from 1/1 to 2/1 may be effected. Examples illustrate the effect of varying the promoter (K2CO3) content. Other promoters may be used, e.g. potassium hydroxide, acetate or fluoride. Specification 649,464, [Group III], is referred to.ALSO:A catalyst for the synthesis of hydrocarbons from CO and H2 comprises iron or active carbon promoted with an alkaline metal compound, and in finely divided form, for example 100-400, preferably 150-200 mesh, suitable for fluidization. The preferred catalyst contains 10-20, especially 15 per cent. reduced iron, and 0.4-1, especially 0.4-0.6 per cent. potassium carbonate, the iron being distributed over the carbon carrier as by impregnation or decomposition of the carbonyl. Other promoters include potassium hydroxide, acetate, and fluoride. The promoter content depends upon the iron surface area and examples illustrate the variation in product quality with contents below and above an optimum 0.5 per cent. Specification 649,464 is referred to.