Reaction Mechanism and Catalytic Impact of Ni/CeO2-x Catalyst for Low-Temperature CO2 Methanation

Ni supported on calcined ceria nitrate catalyst is highly active and stable for low-temperature CO2 methanation reaction (CO2 conversion: 70% at 180 degrees C, 0.05 bar, and gas hourly space velocity (GHSV) of 14 400 L kg(-1) h(-1)). We investigated CO2 adsorption and CO2 + H-2 reaction on the surface of Ni/CeO2 and Ni/CeO2-x catalysts to examine the structure and strength of adsorbed species using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). At temperature of 180 degrees C, weakly adsorbed bridged carbonate was generated on the surface of CeO2-x support by new active sites of oxygen vacancies created by addition of H-2. High reducibility of Ni/CeO2 catalyst played an important role in increasing low-temperature CO2 methanation catalytic activity.