In situ FTIR spectroscopic study of the CO2 methanation mechanism on Ni/Ce0.5Zr0.5O2

CO2 adsorption and methanation on a Ni/Ce0.5Zr0.5O2 catalyst has been investigated using in situ FTIR spectroscopy. CO2 adsorption and methanation experiments were conducted on both components of the support and the catalyst to identify the adsorption species and any intermediate species. It was proposed that CO2 prefers to adsorb on surface oxygen sites adjacent to Ce(III) compared with those adjacent to Ce(IV)/Zr or surface hydroxyl sites. Five adsorption species were revealed for CO2 adsorption on Ni/Ce0.5Zr0.5O2 and monodentate carbonates formed on Ce(III) are easier to be hydrogenated than those on Ce(IV). Formate species were found to be the main intermediate species during the reaction and Ce(III) sites were proposed to be active sites for their hydrogenation. The adsorption and hydrogenation of formic acid were also conducted to confirm the identification of the intermediate species during the reaction. -CH2OH species were detected for the first time and found to be the further intermediates in the reaction.