Gold Catalysts Supported on Crystalline Fe2O3 and CeO2/Fe2O3 for Low-temperature CO Oxidation

High active and stable gold catalysts supported on crystalline Fe2O3 and CeO2/Fe2O3 were prepared via the deposition-precipitation method. The catalyst with a Au load of 1.0% calcined at 180 C showed a CO conversion of 100% at -8.9 degrees C, while Au/CeO2/Fe2O3 converted CO completely at -16.1 degrees C. Even having been calcined at 500 degrees C, Au/Fe2O3 still exhibited significant catalytic activity, achieving full conversion of CO at 61.6 degrees C. The catalyst with a low Au load of 0.5% could convert CO completely at room temperature and kept the activity unchanged for at least 150 h. N-2 adsorption-desorption measurements show that the crystalline supports possessed a high specific surface area of about 200 m(2)/g. Characterizations of X-ray diffraction and transmission electron microscopy indicate that gold species were highly dispersed as nano or sub-nano particles on the supports. Even after the catalyst was calcined at 500 degrees C, the Au particles remained in a nano-size of about 6-10 nm. X-ray photoelectron spectra reveal that the supported Au existed in metallic state Au-0. The modification of Au/Fe2O3 by CeO2 proved to be beneficial to the inhibition of crystallization of Fe2O3 and the stabilization of gold particles in dispersed state, consequently promoting catalytic activity.