Low temperature high activity of M (M = Ce, Fe, Co, Ni) doped M-Mn/TiO2 catalysts for NH3-SCR and in situ DRIFTS for investigating the reaction mechanism

The loading of Mn on TiO2 for NH3-SCR has good low temperature catalytic activity and has been extensively studied. In this experiment, a series of second metals (Ce, Fe, Co, Ni) were added to modify the Mn/TiO2 mixed oxide. The experimental results show that NiMn/TiO2 has excellent catalytic activity, but the addition of Co element did not increase the catalytic activity. The excellent catalytic activity of NiMn/TiO2 is mainly due to its the strong interaction, which enhances the reducibility, increases the total acid amount, Ti3+ ratio, Mn4+ ratio, and the proportion of adsorbed oxygen. These factors facilitate the adsorption and activation of reactant molecules. In addition, in situ DRIFTS results indicate that both the B acid site and the L acid site function at 200 °C, bidentate nitrate not participate in the catalytic reaction and the Langmuir-Hinshelwood (L-H) mechanism dominates at 200 °C.