Catalyst characterization and in situ FTIR studies of carbon dioxide methanation over ruthenium supported on titania

Partially-reduced ruthenium dioxide on titania is an active and selective catalyst for methane formation from carbon dioxide, already at temperatures below 100 C. Results from catalytic screening together with characterization by electron microscopy indicate that the TiO 2 support (Degussa P25 in particular) plays a major role in stabilizing metallic ruthenium in highly-dispersed form (d 10-30 A), provided care is taken in the RuO 2 deposition step. Chemisorption of H 2 and CO 2 has revealed a strong g coadsorption synergy together with extensive hydrogen spillover. Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy in situ has provided confirmatory evidence of the latter, and shown that CO, believed to arise from the reverse water-gas shift reaction accumulates on the metal causing catalyst deactivation. Heating above 100 facilitates the Boudouard disproportionation reaction and the activity is regenerated. Implications for the mechanism of CO 2 hydrogenation are briefly discussed.