Highly stable and selective layered Co-Al-O catalysts for low-temperature CO2 methanation

A series of layered Co-Al-O catalysts derived from hydrotalcites for low-temperature CO2 methanation were prepared via a hydrothermal method and reduced at 500, 550, 600, 650, and 700 °C, respectively. The characterisation results from XPS and CO2-TPD revealed that the Co0 content and basic sites over these catalysts were firstly increased and then decreased with the reduction temperature increasing, which led to the efficient dissociation of H2 and CO2 adsorption. In situ DRIFTS measurements revealed that the formation of CH4 proceeded via the hydrogenation of carbonate and formate as intermediates. A superior catalytic performance of Co-Al-O-600 catalyst for CO2 methanation was achieved with a CO2 conversion of 74% and a CH4 selectivity of 99% at low temperature of 250 °C. Moreover, it exhibited excellent resistance to coking and sintering upon a 240 h time on stream operation.