Enhanced Low-Temperature Activity of CO2 Methanation Over Ni/CeO2 Catalyst

CeO2 nanorods (CeO2-nrs), CeO2 nanocubes (CeO2-ncs) and CeO2 nanopolyhedrons (CeO2-nps) were prepared by hydrothermal method and then NiO crystallites were deposited on these supports by precipitation-deposition, respectively. The physicchemical properties of Ni/CeO2 catalysts were characterized and performances for carbon dioxide methanation reaction were tested. The Ni/CeO2-nrs sample shows well metal dispersion and high concentration of oxygen vacancy, which leads to the high catalytic activity for CO2 methanation. Especially at 300 degrees C, the CO2 conversion could reach 60%. Further analysis reveals that the content of oxygen vacancy has a positive correlation with the surface area of catalyst. The largest surface area results in the most of oxygen vacancy on the Ni/CeO2-nrs catalyst, and then a large amount of CO2 could be activated at low temperatures. Meanwhile, large surface area facilitates the dispersion of active metals, and improves the degree of H-2 activation. The combined effect results in the promotion of catalytic activity for CO2 methanation at low temperatures. [GRAPHICS]