xAu/α-MnO_2 Catalysts:Structure and Catalytic Oxidation of Benzene and Toluene

α-MnO2-supported gold catalysts(xAu/α-MnO2,x=1.0%—7.0%,mass fraction) were prepared by deposition-precipitation method using NaOH as precipitation agent and characterized by X-ray diffraction(XRD),N2 adsorption-desorption measurement,H2 temperature-programmed reduction(TPR),Transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS).Catalytic activities of the materials were evaluated for the oxidation of benzene and toluene.The sizes of Au particle and α-MnO2 support were related with the Au loading over xAu/α-MnO2 samples and increased with Au loading.The result of XPS showed that the molar ratios of O2-/O-2,Mn4+/Mn3+ and Au3+/Au0 increase with adding of Au.It was shown that the loading of gold on α-MnO2 could significantly modify the catalytic activities.The catalytic performance of xAu/α-MnO2 strongly depended upon the Au loading,among which 3% Au/α-MnO2 performed the best activity,T100=280,250 ℃ for the catalytic oxidation of benzene and toluene,respectively.The excellent performance of 3% Au/α-MnO2 was associated with the highly dispersed Au,good low-temperature reducibility,and synergism at the interface of Au and MnO2 nanodomains.