MnOx/TiO2 composite nanoxides synthesized by deposition-precipitation method as a superior catalyst for NO oxidation

A series of MnOx/TiO2 composite nanoxides were prepared by deposition-precipitation (DP) method, and the sample with the Mn/Ti ratio of 0.3 showed a superior activity for NO catalytic oxidation to NO2. The maximum NO conversion over MnOx(0.3)/TiO2(DP) could reach 89% at 250 degrees C with a GHSV of 25,000 h(-1) which was much higher than that over the catalyst prepared by conventional wet-impregnation (WI) method (69% at 330 degrees C). Characterization results including XRD, HRTEM, FTIR, XPS, H-2-TPR, NO-TPD and Nitrogen adsorption-desorption implied that the higher activity of MnOx(0.3)/TiO2(DP) could be attributed to the enrichment of well-dispersed MnOx on the surface and the abundance of Mn3+ species. Furthermore, DRIFT investigations and long-time running test indicated that NO2 came from the decomposition of adsorbed nitrogen-containing species. (C) 2010 Elsevier Inc. All rights reserved.