Catalytic CO2 valorization into CH4 on Ni-based ceria-zirconia. Reaction mechanism by operando IR spectroscopy

Despite several studies, the use of CO2 as a chemical reactant is currently limited to a few processes. With the aim to formulate an efficient catalyst for CO2 conversion into methane, nickel was selected, being well known to be active for the catalytic COx methanation. Ceria-zirconia mixed oxide was chosen as a support because of its properties to activate CO2. Yields close to those predicted by thermodynamic were obtained with weak deactivation even after 90 h on stream. Interactions between Ni and the ceria-zirconia support seem to be a key parameter for the methanation reaction. The use of IR operando spectroscopy revealed that the main mechanism for CO2 methanation does not require CO as reaction intermediate. The better activity observed compared to Ni-silica can be explained by the importance of weak basic sites the adsorption of CO2.