Insight into CO2 methanation mechanism over NiUSY zeolites: An operando IR study

Abstract Ni-impregnated USY zeolites with increasing Ni content (5, 10, 14% wt. ) were investigated by operando IR spectroscopy for both CO 2 adsorption and CO 2 methanation conditions reaction. In-situ FTIR and TPD experiments highlighted a rather weak CO 2 adsorption, which occurs namely as carbonates or CO 2 linear complexes over cations ( e . g. , Na + ). Under methanation conditions, dissociated hydrogen reacts with carbonates and/or physisorbed CO 2 , leading to monodentate formates, then carbonyls (both adsorbed onto Ni 0 particles), and finally to methane. A detailed mechanism of the pathways involved in CO 2 methanation over NiUSY catalysts is then discussed in accordance with infrared spectroscopic data.