Abstract: MnOx-SnO2 composite oxides prepared by a redox coprecipitation route were tested in selective catalytic reduction of NO by NH3 at low temperature. The results showed that the MnOx-SnO2 catalyst with a Mn/(Mn+Sn) molar ratio of 75% exhibted the best performance, on which NO conversion of 100% could be achieved at temperatures of 120-200 ℃. The characterization results of N2 adsorption-desorption,X-raydiffraction, andX-rayphotoelectron spectroscopy indicated that the higher surface area, the formation of solid solution between manganese and tin oxides, and the high oxidation state manganese species were responsible for the high catalytic activity of the MnOx-SnO2 catalyst.

Key words: manganese oxide, tin oxide, composite oxide, ammonia, selective catalytic reduction, nitric oxide, low temperature, redox coprecipitaition