1953. KREBS, R. W. (Standard Oil Development Co.). Hydrocarbon Synthesis. United States Patent 2,614,114, Oct. 14, 1952. Chem. Abs., vol. 47, 1953, p. 1374.

Hydrocarbons and oxygenated hydrocarbons are synthesized from CO and H₂ in the presence of a fluidized, powdered Fe catalyst contained in a reactor with a portion of the fluidized catalyst maintained in a reducing atmosphere with respect to Fe. The ratio of the reducing to the oxidizing zones may vary, but should not exceed 20% of the total catalyst volume, and a 10% ratio is preferred. When Fe of low O content is charged to the reactor after a day’s continuous operation, the Fe will contain 20-22%, by weight, combined O. This process permits the O content to be reduced to 10-15%, for example, so that the catalyst will be maintained in a high state of activity during an increased life period.