The reaction of methane and deuterium on evaporated nickel catalysts

Abstract The production of all four deuteromethanes from the reaction of methane and deuterium on evaporated nickel films in the temperature range 206 to 255° C was followed by means of a mass spectrometer. The compound CD4 was the most abundant product in the initial reaction, and there was other evidence that the adsorption of deuterium was stronger than the adsorption of methane. The surface areas of the films were found by the adsorption of deuterium at 0° C which was instantaneous and the films were shown by electron diffraction to be unorientated. An activation energy of about 11 kcal./mole was required for the adsorption of methane. Two types of reaction were distinguished: the first produced CH3D with an energy of activa­tion of 24 kcal./mole and the initial rate varied as PCH4P-1D2 ; the second having an energy of activation of 32 kcal./mole, a greater entropy of activation and a rate dependent on PCH4P-1D2 gave the other three compounds CH2D2, CHD3 and CD4. Mechanisms for these reactions are formulated. The equilibrium constants for the interconversion of the five methanes were determined at 466° C and compared with calculated values.