The Impact of Surface Species Migration on Low-Temperature Co2 Methanation Over Cezrox/Ni Catalysts

Abstract

The performance of Ni-based catalysts for low-temperature methanation depends significantly on the surface nature. We report the influence of surface restore on low-temperature methanation performance over inverse Ni-based catalysts by modulating the migration of metal particles. The CeZrOx/Ni-400 demonstrated high CO2 conversion of up to 91.6% and CH4 selectivity of 100% at 225 oC, which was attributed to that the high dispersion and small size of metal particles facilitated the formation of active Ni-O-M interfaces. However, despite the decreased dispersion and metal particles size, the catalytic activity exhibited an initial decline followed by a subsequent increased as the calcination temperature increased. Characterization results revealed Ni and Ce species gradually migrated from the surface to the bulk phase, while Zr species became enriched on the surface. In-situ DRIFTS results demonstrated that the methanation reaction predominantly followed the formate pathway, with formate species generated at Ni-O-Zr and Zr-O-Zr interfaces exhibiting a preferential hydrogenation tendency.

Keywords: low-temperature CO2 methanation, surface restore, inverse catalyst, metal-support interaction, mechanism