637.    CRAXFORD, S. R.  Reactions of the Fischer-Tropsch Process.  Fischer-Tropsch Synthesis of Hydrocarbons and Some Related Reactions.  Trans. Faraday Soc., vol. 35, 1939, pp. 946-958, 966-967; Brennstoff-Chem., vol. 20, 1939, pp. 263-270; British Chem. Abs., 1939, B, p. 1097; Chem. Abs., vol. 33, 1939, p. 9606.

     At the temperature of the Fischer synthesis (~200°) CO reacts slowly with the catalyst to form Co₂C, but this reaction is always slower than the reduction of the Co₂C by H₂ at the same temperature.  With CO and H₂ the catalyst forms Co₂C+H₂O and this reaction is faster than the reduction of the carbide by H₂ under the synthesis conditions. When oils are produced by the Fischer synthesis, the o-p-H₂ conversion is inhibited; when CH₄ is the product of the synthesis, the o-p-conversion occurs freely.  This shows the presence of chemisorbed H on the catalyst surface in the latter case but not in the former.  The water-gas reaction runs parallel to the o-p-H₂ conversion.  It is inhibited during oil formation as is also the hydrogenation-cracking of paraffin hydrocarbons on the catalyst.  Theoretical deductions are made starting with the assumption that the first step in the synthesis is the alternate formation and reduction of Co₂C to give CH₂ groups.  Subsequent presence of chemisorbed H₂ yields CH₄, while the lack of chemisorbed H₂ allows the CH₂ groups to link up to give long chains.