A series of titania and modified titania (TiO2-MOx; M= Ce, Si, Zr) supported manganese oxide catalysts are prepared by wet impregnation method. Titania based mixed oxide supports (1:1 mole ratio) are prepared by co-precipitation method using ultra high dilute solutions of TiCl4 and corresponding nitrate precursors. The obtained materials were employed for SCR of NO using ammonia and CO as reductants at low temperatures. All mixed oxide supported MnO2 catalysts showed complete NO conversion with 100% N2 selectivity when ammonia is used as reductant, even at industrially relevant conditions (GHSV= 50,000 h-1, 2 vol.% O2 in feed, temperature175 °C). Where as decrease in NO conversion was observed when CO is used as reductant at same reaction conditions. We attempted to elucidate the reaction mechanism for NO-CO reaction on titania supported manganese oxide catalysts using in-situ FT-IR experiments. Monodentate and bidentate nitrates were observed in the in-situ FT-IR experiments of NO adsorbed on catalyst in the frequency region 1625-1100 cm-1. All characterization and experimental results suggests that surface oxygen vacancies and redox nature of the catalyst are important for NO-CO reaction. The proposed mechanism based on our findings will be discussed.

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