3140.     SCHWAB, G. M., AND DRIKAS, G.  [Inhibiting Action of Methane on the Reaction of Oxygen and Hydrogen on a Copper Oxide Catalyst.]  Ztschr. Elektrochem., vol. 50, 1944, pp. 97-103; Chem. Abs., vol. 39, 1945, p. 858.

        At pressures of 1-9 mm., CH₄ in a mixture with O₂ not oxidized below 600° but is oxidized when present in H₂-O₂ mixtures at 400°.  This inhibiting action is not due to displacement of the reactants from the catalyst by the CH₄, since this hypothesis is invalidated by the conditions of concentration and temperature.  Nor can it be understood that, as a result of thermal diffusion, the CH₄, whose molecular weight lies between that of H₂ and O₂, drives the O₂ away from the H₂ and the wire; on the one hand, the reaction is much slower than the expected velocity of diffusion to the wire, and, on the other hand, the calculated speed of thermal diffusion is so low that the stationary thermal stratification of the gases appears to be virtually nonexistent because of the diffusion in concentration.  It can be explained best by picturing the oxy-hydrogen reaction as a branched-chain reaction set up by a chain carrier formed on the catalyst; CH₄ inhibition takes place then through a further chain rupture with consumption of CH₄.  The suggested chain of reactions is:  (1) Cu+O₂→CuO+O, (2) O+H₂→OH+H, (3) OH+H₂→H+H₂O, (4) H+O₂→OH+O₂.