Highly Active Au/Alpha-Mno2 Catalysts For The Low-Temperature Oxidation Of Carbon Monoxide And Benzene

alpha-MnO2-supported gold catalysts (xAu/alpha-MnO2, x=0-7 (corresponding to the Au loading (mass fraction) of 0-7%) were prepared by a deposition- precipitation method using urea as a precipitation agent and characterized by different techniques such as X-ray diffraction (XRD), N-2 adsorption-desorption measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and H-2 temperature-programmed reduction (TPR). The catalytic activities of the materials were evaluated for the oxidation of CO and benzene. The Au particle size was found to be related to the Au loading of the xAu/alpha-MnO2 samples and increased with Au loading. XPS results showed that the mole ratios of O2-/(O-2(2-) or O-), Mn4+/Mn3+ and Au3+/Au-0 increased upon the addition of Au. The loading of gold over alpha-MnO2 significantly modified the catalytic activities. The catalytic performance of xAu/alpha-MnO2 strongly depended on the Au loading, and 3Au/alpha-MnO2 gained the best activity at T(90=)80 degrees C and T-90=20 degrees C for the catalytic oxidation of CO and benzene, respectively. The excellent performance of 3Au/alpha-MnO2 is associated with highly dispersed Au, good low-temperature reducibility, and a synergism at the interface between the Au and MnO2 nanodomains.