Catalytic Oxidation of CO over Ag-Doped Manganese Oxide Catalysts: Preparation and Catalytic Activity

Abstract

The manganese oxide (MnO2) sample was synthesized by the reaction of KMnO4 with Mn (Ac)2 using the HNO3 solution as pH regulator. The Ag-doped manganese oxide, Ag/MnO2-Q and Ag/MnO2-H, were synthesized by incorporation method and typical wet impregnation method, respectively. The structure of catalysts was characterized by N2 adsorption/desorption and X-ray diffraction. The influences of preparation methods on the catalytic activity of CO oxidation were studied. The doping of Ag to MnO2 decreased the specific surface area of Ag/MnO2 catalysts, especially for Ag/MnO2-H samples prepared by traditional wet-impregnation method. The Ag/MnO2 catalysts showed higher catalytic activity for CO oxidation than that of MnO2. The catalytic activities of Ag/MnO2 samples strongly depended upon the preparing methods, among which 3Ag/MnO2-Q catalyst, prepared by the incorporation method, was the most efficient catalyst towards the addressed reactions. The excellent performance of 3Ag/MnO2-Q was mainly associated with the good low-temperature reducibility, abundant surface oxygen and broadly dispersed silver oxides species.