Comparative study on the catalytic CO oxidation properties of CuO/CeO2 catalysts prepared by solid state and wet impregnation

Abstract

A series of CuO/CeO2 catalysts were prepared by solid state impregnation (SSI) and wet impregnation (WI) methods and characterized by X-ray diffraction, H2 temperature-programmed reduction (H2-TPR), laser Raman spectroscopy (LRS), in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), and X-ray photoelectron spectroscopy (XPS). XPS and H2-TPR results showed that SSI increased the dispersion of the copper species on the catalyst surface, which benefited the reduction of CuO species. LRS results indicated that a higher concentration of oxygen vacancies was obtained by the SSI method unlike the WI method. CO oxidation results showed that at a given CuO loading, the activity of the catalysts prepared by SSI was higher than that of their counterparts prepared by WI. Based on the combined characterization results, it was suggested that the enhanced activity was closely related to the higher concentrations of oxygen vacancies and Cu+-CO species on the catalysts. Last, a possible synergetic mechanism was proposed for CO oxidation over the CuO/CeO2 catalysts.