Meso- and macro-porous Pd/CexZr1−xO2 as novel oxidation catalysts

Abstract

A new class of high-efficiency oxidation catalysts has been prepared using a combined surfactant and colloidal crystal templating method. The Pd/Ce_xZr_1−xO₂ products possess mesoporous structures and macrochannels. XRD and EXD analyses confirmed the formation of a 0.8 wt.% Pd/Ce_0.6Zr_0.4O₂ with a cubic phase at temperatures above 700 °C. With increasing calcination temperature, better crystallization of the cubic phase and incorporation of more zirconium into the ceria lattice were observed. The extent of surface Ce³⁺ and oxygen vacancies on the samples were studied by the XPS measurements. The T₅₀ and T₉₀ for CO oxidation over Pd supported catalysts were 65 °C and 75 °C respectively. These values were better than those obtained from catalysts without macrochannel structures and the one prepared by the co-precipitation method. Such high catalytic efficiency can be explained by the high crystal phase homogeneity, availability of more oxygen vacancies and an enlarged surface area.