Pd-Cu/palygorskite catalysts were prepared by a wet impregnation method using palygorskite (PC/N-Pal) and ultrasonic-treated palygorskite (PC/U-Pal) as the support. Their catalytic activities toward CO oxidation at room temperature and in humid circumstances were investigated. PC/U-Pal exhibits much higher catalytic activity and stability than PC/N-Pal under the conditions of 1.0 vol.% CO and 3.3 vol.% H2O in the feed gas. The X-ray diffraction results indicate that quartz impurities were eliminated from the Pal after the ultrasonic treatment, and more copper species exist in the form of Cu2Cl(OH)3 in PC/U-Pal. The temperature-programmed reduction results suggest that there is an enhanced reducibility of PC/U-Pal after ultrasonic treatment. Furthermore, the ultrasonic treatment can properly decrease the hydrophilicity of the support and catalyst, which may also contribute to the excellent catalytic performance.
Keywords: Pd-Cu/palygorskite; humid circumstances; hydrophilicity; room temperature CO oxidation; ultrasonic treatment.