Effect of Pd loading and precursor on the catalytic performance of Pd/WO3–ZrO2 catalysts for selective oxidation of ethylene

The structure and properties of Pd/WO3–ZrO2 (W/Zr = 0.2) catalysts with different Pd loadings and precursors were investigated. The results indicate that Pd/WO3–ZrO2 prepared from a PdCl2 precursor was optimum for high activity and selectivity. Moreover, ethylene conversion increased with the Pd loading. The structure and nature of the catalysts were characterized using X-ray diffraction, BET N2 adsorption, H2 temperature-programmed reduction and H2 pulse adsorption techniques. The results reveal that the higher catalytic performance of Pd/WO3–ZrO2 prepared from PdCl2 could be related to the formation of polytungstate species and the existence of well-dispersed Pd particles.