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

Abstract

CO₂ adsorption and methanation on a Ni/Ce_0.5Zr_0.5O₂ 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/Ce_0.5Zr_0.5O₂ 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.