Selective catalytic oxidation of NO with O 2 over Ce-doped MnO x/TiO 2 catalysts

Abstract

A series of Ce-doped MnO x /TiO 2 catalysts were prepared by impregnation method and used for catalytic oxidation of NO in the presence of excess O2. The sample with the Ce doping concentration of Ce/Mn=1/3 and calcined at 300°C shows a superior activity for NO oxidation to NO 2. On Ce(1)Mn(3)Ti catalyst, 58% NO conversion was obtained at 200°C and 85% NO conversion at 250°C with a GHSV of 41000 h −1, which was much higher than that over MnO x /TiO 2 catalyst (48% at 250°C). Characterization results implied that the higher activity of Ce(1)Mn(3)Ti could be attributed to the enrichment of well-dispersed MnO x on the surface and the abundance of Mn 3+ and Ti 3+ species. The addition of Ce into MnO x /TiO 2 could improve oxygen storage capacity and facilitate oxygen mobility of the catalyst as shown by PL and ESR, so that its activity for NO oxidation could be enhanced. The effect of H 2O and SO 2 on the catalyst activity was also investigated.