Electronic metal-support interactions and their promotional effect on CO2 methanation on Ru/ZrO2 catalysts

Abstract Discrimination between electronic and structural effects in metal-support interactions (MSIs) is often hampered by contributions from either one. We report results of a combined experimental/theoretical study that directly demonstrate the action of electronic MSIs (EMSIs), while structural modifications like a partial overgrowth of metal nanoparticles by a partly reduced oxide due to SMSI, can be excluded. This is demonstrated for CO 2 methanation on Ru/ZrO2 with small Ru NPs (~2nm), where a high-temperature reductive treatment results in a significantly increased methanation rate. Based on operando / in situ spectroscopies and other characterizations, SMSI induced structural modifications can be excluded; the enhanced activity results from charge transfer from O-vacancies in the ZrOx surface region to adjacent Ru nanoparticles. DFT calculations reveal that the transferred charge is localized at the interface, leading to stronger Ru-CO bonding and enhanced COad methanation. We believe that these trends are generally relevant for reactions in a reductive atmosphere.