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

• Published in: Journal of catalysis 2021-08, Vol.400, p.407-420
• Main Authors: Chen, Shilong, Abdel-Mageed, Ali M., Li, Mengru, Cisneros, Sebastian, Bansmann, Joachim, Rabeah, Jabor, Brückner, Angelika, Groß, Axel, Behm, R. Jürgen
• Format: Article
• Language: English
• Subjects: CO2 methanation; DFT calculation; Electronic metal-support interactions. in situ / operando spectroscopy; Ru/ZrO2
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2021.06.028

[Display omitted] •Electronic metal-support interactions (EMSIs) promote CO2 methanation on Ru/ZrO2.•Structural effects (SMSI) can be excluded.•EMSIs result from O-vacancy formation at ZrO2 surface and charge transfer to Ru.•Charge transferred to Ru nanoparticles is localized at adjacent interface Ru atoms.•Negatively charged Ru sites stabilize CO adsorption, promoting CO methanation. 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 CO2 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.