2919. ------.[RUHRCHEMIE, A.G.]. Hydrocarbon Synthesis. British Patent 690,432, Apr. 22, 1953. Chem. Abs., vol. 47. 1953, p. 8996.

Hydrocarbons and O-containing organic compounds are synthesized by the hydrogenation of CO at atmospheric presence of an Fe catalyst, in which the catalystis used at 170°-200°, and in such manner that in the course of the 1^st 500 hr. of operation, the catalyst is extracted 4-7 times to remove high-bioling synthesis products therefrom; the synthesis is thereafter continued at 170°-200°. Before its use, the catalyst is impregnated with an alkali metal salt of a nonvolatile acid, such as K silicate of K phosphate, and is reduced with H₂ at a high rate of flow and 200°-350°. The extractions are generally effected with hydrocarbon mixtures at the synthesis temperature in use at the time. While up to the 1^st extraction the conversion remains quite unsatisfactory at 30-40%, an improved conversion is obtained after the 1^st extraction. After 4-7 extractions of the catalyst within the 1^st 500 hr. of operation, the normal CO plus H₂conversion of 72% is attained. Thereafter the catalyst can be used generally for 2,000-4,000 operational hr. before its activity is reduced. Owing to the low synthesis temperature, the CH₄ formation remains considerably lower than in usual processes for hydrogenating CO, in spite of a high total conversion. The life of the catalyst is also considerably lengthened. In an example, an Fe catalyst containing Fe 100, Cu 5, and CaO 10 parts was precipitated with NaCO₃ from a mixed solution of the corresponding materials at pH 7. The precipitate was separated by filtration, washed, dried, and finally impregnated with K silicate. The reduction was carried out for 60 min. in H₂ at 225. The catalyst was then put on stream at 160 with 100 l. water gas per l. catalyst per hr. In 498 hr. the temperature was raised to 195 to give CO plus H₂ conversion of approximately 39%, which fell to 30% in the next 48 hr. of use, owing to the deposition of paraffin on the catalyst. The catalyst was then extracted with 4 times its volume of a diesel-oil fraction boiling 220°-300°. Immediately after the extraction the CO plus H₂ conversion rose to 48%.