Surface Science Letters Catalytic Methanation over Single Crystal Nickel and Ruthenium: Reaction Kinetics on Different Crystal Planes and the Correlation of Surface Carbide Concentration with Reaction Rate

The kinetics of the reaction of H, and CO over single crystals of nickel ((100) and (111)) and ruthenium ((110) and (001)) have been studied as a function of pressure and Hz/CO ratio. A striking correlation has been observed between the measured surface carbide concentration and the rate of methane production while varying the Ha/CO ratio and the total pressure. This correlation is shown to be a necessary consequence of the reaction mechanism previously proposed [I] for the catalytic methanation reaction over nickel.