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.