Bifunctional Mechanism of CO2 Methanation on Pd-MgO/SiO2 Catalyst: Independent Roles of MgO and Pd on CO2 Methanation

We scrutinized the reaction mechanism of CO2 methanation catalyzed by a Pd-MgO/SiO2 catalyst. Density functional theory studies showed that MgO and Pd nanoparticles play completely different roles. We found that MgO initiates the reaction by binding a CO2 molecule, forming a magnesium carbonate species on the surface, and that a supply of atomic H is essential for further hydrogenation of magnesium carbonate to methane. A CO(2)temperature-programmed desorption study gives credence to our findings on the role of MgO. Our results confirm the bifunctional mechanism of CO2 methanation by a Pd-MgO/SiO2 catalyst.