Intermetallic based materials for Sabatier reaction: Surface understanding, performance assessment and comparison with commercial catalyst

Abstract

Ni-based intermetallics and commercial CO2 hydrogenation catalysts have been compared in Sabatier’s reaction. For RENi5 intermetallics (RE = La, Ce), the analysis of the chemical bonding shows a charge transfer from the RE to the Ni species and the formation of polar two- and four-atomic RE-Ni and four-atomic Ni bonds. Surface simulations and chemical understanding based on the ELI-D mapping approach indicate that dangling bonds originate from the multi-atomic ones and they are the preferred adsorption sites for H2 molecules. This leads to H2 dissociation, its reduction to hydrides, Ni QTAIM-anion oxidation to the metallic state, and diffusion toward the surface. LaNi5 is active toward rWGS while the best catalytic activity is obtained over CeNi5 (49% methane yield) at 723 K; the exhaust catalyst is composed of Ni particles supported over CeO2 with a mean size of 10 nm and thus, promising material could be developed on intermetallic based compounds.