Structures and Catalytic Performance of Highly Dispersed Cu-Based Catalysts Supported on Modified Mesoporous Al2O3

The Cu-based catalysts Supported on mesoporous gamma-Al2O3 modified by LaCeZr or YCeZr were prepared by impregnation. The structures of the catalysts were carefully characterized by XRD, BET, XAFS, XPS and H-2-TPR techniques. The state of copper species and their reducibility were investigated and correlated with the CO oxidation performance of the catalysts. N-2 adsorption and desorption isotherms reveal that the catalysts possess high specific surface areas and uniform pore size distributions in mesoporous range. The XRD results indicate that after calcination at 800 degrees C the copper species supported on pure gamma-Al2O3 without modification exist as CuAl2O4 spinel, while the EXAFS results show that the copper species supported on gamma-Al2O3 modified by LaCeZr or YCeZr exist as highly dispersed CuO crystallites, which facilitates the CO oxidation. H-2-TPR results show that for the same series of the catalysts the reduction peaks Of CuO species shift to higher temperatures with the calcination temperature increasing, implying the decrease of the mobility of lattice oxygen, and resulting in the decrease of oxidation activity. The copper catalyst supported on gamma-Al2O3 modified by LaCeZr exhibits strong sulfur and water-resistance performance after calcination at 650 degrees C.