Mechanism of the Catalytic Hydrogenation of Oxides of Carbon to Methane

The present review examines the mechanisms of the formation of methane from carbon monoxide and dioxide and hydrogen in the presence of contact catalysts based on metals of the iron group (chiefly nickel). The experimental results obtained by various methods are examined, the reactive forms of the adsorbed molecules and the signs of their charges are considered, and particular attention is paid to the determination of the reactive complexes under the conditions preceding the start of the catalytic reaction, and the results of kinetic studies. It is shown that there is a significant difference in the mechanisms of the hydrogenation of carbon monoxide and dioxide to methane. This difference is attributed to the poisoning effect of carbon monoxide on the processes involved in the hydrogenation of CO₂. Attention is drawn to a number of results which are of considerable importance for the solution of the problems of the catalytic purification of hydrogen from oxides of carbon. The bibliography contains 129 references.