2607.     PERRIN, M.  [Evolution of Activity of Fischer-Tropsch Catalysts.]  Compt. rend., vol. 224, 1947, pp. 342-343; Chem. Abs., vol. 41, 1947, p. 3739.

        Fischer and Meyer (abs. 988) observed that CO was completely hydrogenated to CH₄ in the presence of a fresh catalyst.  Craxford (abs. 637) attributed the hydrogenation to metallic Co, and the synthesis of higher hydrocarbons to Co carbide.  Earlier it was observed that where the CO and H₂ were diluted with CH₄, condensable hydrocarbons were formed at once.  Now it has been found that N₂ produces the same effect and, in general, lowering the partial pressure of CO and H₂ inhibits the formation of CH₄ almost completely.  Lowering of the synthesis temperature from 190° to 175°, as well as a reduction in the flow of the reactants, also reduces the necessary delay in the starting of the synthesis reaction.  These observations indicate that the initial production of CH₄ is due to overheating the catalyst bed and that any method of preventing this temperature rise starts the hydrocarbon synthesis without the formation of excessive CH₄.