Diffuse-reflectance FTIR spectroscopy for kinetic and mechanistic studies of carbon dioxide hydrogenation in a continuous recycle reactor

CO2 methanation over Ru/TiO2 was studied by using a diffuse-reflectance IR cell coupled with a continuous-feed recycle reactor. Metal-adsorbed CO is a major reaction intermediate and at 120 Deg occupies approx. 40% of the available Cu surface, while CH4 formation proceeds at a turnover frequency of 2.8 * 10-3/s. In contrast, CO methanation is totally hindered under the same conditions. A simple kinetic model is proposed to account for the main trends obsd. For CO2 methanation, the temp. insensitivity of adsorbed CO coverage is interpreted on the basis of a generalized (2-stage) intermediate supply/consumption mechanism involving the reverse water-gas shift reaction. [on SciFinder (R)]