Kinetics of CO2 methanation over Ru/γ-Al2O3 and implications for renewable energy storage applications

• CO2 methanation on 10% Ru/γ-Al2O3 follows Eley–Rideal kinetics.
• Rate is strongly dependent on H2 (0.88 order) and weakly dependent on CO2 (0.34).
• Product inhibition on reaction rate is negligible.

Kinetics of CO2 hydrogenation over a 10% Ru/γ-Al2O3 catalyst were investigated using thermogravimetric analysis and a differential reactor approach at atmospheric pressure and 230–245 °C. The data is consistent with an Eley–Rideal mechanism where H2 gas reacts with adsorbed CO2 species. Activation energy, pre-exponential factor and reaction orders with respect to CO2, H2, CH4, and H2O were determined to develop an empirical rate equation. Methane was the only hydrocarbon product observed during CO2 hydrogenation. The activation energy was found to be 66.1 kJ/g-mole CH4. The reaction order for H2 was 0.88 and for CO2 0.34. Product reaction orders were essentially zero. This work is part of a larger study related to capture and conversion of CO2 to synthetic natural gas.