Enhancing the CO2 methanation activity of Ni/CeO2 via activation treatment-determined metal-support interaction

Abstract

The metal-support interaction is of critical importance to enhance the catalytic activity and selectivity. However, it is still challenging to construct an appropriate interaction starting from the catalyst fabrication and/or activation. We herein established low-temperature treatment of Ni2+ ions impregnated on ceria in reductive atmosphere and reduction–oxidation cycles as effective approachs to regulate the metal-support interaction and raise the catalytic performance in the CO2 methanation. The proposed construction approach yielded Ni/CeO2 that displayed highly dispersed Ni nanoparticles in contact with CeO2 (111) and (100) facet, higher density of surface oxygen vacancies and larger amounts of weak basic sites relative to the reference samples, which increased the capacity for H2 and CO2 adsorption/activation. The interaction resulted in appreciably (2–3 fold) higher activity in the CO2 methanation with maintaining almost full selectivity to CH4 and high stability. Coverage of Ni surface by CeO2−x thin layer as a typical structure of strong metal-support interaction resulting from high-temperature reduction, can be alleviated via reduction–oxidation cycles. We also demonstrate the activation treatment-determined metal-support interaction effect can generally extend to (TiO2 and ZrO2) supported Ni catalysts.