Investigation of the selective catalytic reduction of nitric oxide with ammonia over Mn/TiO2 catalysts through transient isotopic labeling and in situ FT-IR studies

► No formation of NO2 was observed for Mn/TiO2 catalyst at reaction temperature. ► Mars-van-Krevelen type low-temperature NH3 oxidation. ► Rate of SCR reaction is very small in absence of oxygen. ► Occurrence of unusual low-temperature NH3 oxidation over Mn/TiO2. ► Oxygen exchange between NO and catalyst lattice oxygen takes place over Mn/TiO2.