Effect of Ni Loading on Physicochemical Properties of NiOx/CeO2 Catalysts and Catalytic Activity for NO Reduction by CO
Transition metal oxide catalysts has been investigated extensively because of their relatively low costs and high activities in many chemical reactions. In this work, a series of NiOx/CeO2 catalysts (0.5~30wt% Ni) were prepared using incipient wetness impregnation method. These catalysts were tested with various characterizations techniques, including Brunauer-Emmett-Teller (BET) theory, Raman spectroscopy, X-ray powder diffraction (XRD), Hydrogen Temperature-programmed reduction (H2-TPR) as well as Gas Chromatography (GC) for their physicochemical properties, surface properties, reduction properties and catalytic activities in the NO reduction by CO reaction. The increase in Ni loading of the catalyst (up to 5% NiOx/CeO2) led to decrease in specific surface area, formation of NiOx crystalline structures on CeO2 surface, easier reduction of the catalyst comparing to bulk NiOx and bulk CeO2, as well as increase in catalytic activity in NO reduction by CO reaction. From these results, surface dispersion of NiOx and the formation of monolayer NiOx coverage of the catalysts were believed to affect the catalytic activities greatly. The results provided insights on the structure-activity relationship of NiOx/CeO2 catalysts for NO reduction by CO reaction.