Tailoring metal-support interactions via tuning CeO2 particle size for enhancing CO2 methanation activity over Ni/CeO2 catalysts

Interfaces derived from metal-support interaction (MSI) and related oxygen vacancies are generally recognized as main factors affecting on CO2 methanation performance, but the interaction between these two factors is not yet very clear. To better understand the role of complicated MSI and associated oxygen vacancy for CO2 metha-nation, we designed the CeO2 nanocubes with different sizes as support and prepared supported Ni catalysts to study the relationship between MSI and catalytic performance. HRTEM, XRD, BET, Raman and XPS character-ization results confirmed that the MSI and related oxygen vacancy concentration could be modulated by CeO2 size. The impact of oxygen vacancy and phase interface on activating reactant molecules (CO2/H2) was evi-denced by HRTEM and CO2/H2-TPD results. The CO2 conversion rate on the Ni/CeO2-6M at 548 K is about three times that on the Ni/CeO2-12M, which is attributed to its lower activation energy. Furthermore, in-situ FT-IR results for CO2 hydrogenation on the Ni/CeO2-6M proved that CO2 methanation followed the formate pathway and the methoxy/carbonyls are key intermediates to produce CH4. The structure-effect relationship was further explored to show the size effect on Ni-CeO2 interaction interfaces and enhanced methanation performance.

Automated summary

Interfaces derived from metal-support interaction and oxygen vacancies are key factors affecting CO2 methanation performance. By designing CeO2 nanocubes of different sizes, the modulation of metal-support interaction and oxygen vacancy concentration was achieved. The impact of oxygen vacancy and phase interface on activating CO2 molecules was demonstrated, and smaller CeO2 nanocubes exhibited superior performance in CO2 methanation.