Abstract: α-MnO₂-supported gold catalysts (xAu/α-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), N₂ adsorption-desorption measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and H₂ 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/ α-MnO₂ samples and increased with Au loading. XPS results showed that the mole ratios of O^2-/(O₂^2- or O^-), Mn⁴⁺/Mn³⁺ and Au³⁺/Au⁰ increased upon the addition of Au. The loading of gold over α-MnO₂ significantly modified the catalytic activities. The catalytic performance of xAu/α-MnO₂ strongly depended on the Au loading, and 3Au/α-MnO₂ gained the best activity at T₉₀=80 °C and T₉₀=20 °C for the catalytic oxidation of CO and benzene, respectively. The excellent performance of 3Au/α-MnO₂ is associated with highly dispersed Au, good low-temperature reducibility, and a synergism at the interface between theAu and MnO₂ nanodomains.

Key words: &, alpha, -MnO₂ supported gold catalyst, Low-temperature reducibility, Synergistic action, Carbon monoxide oxidation, Benzene combustion