In-Situ DRIFTS for Reaction Mechanism and SO2 Poisoning Mechanism of NO Oxidation Over γ-MnO2 with Good Low-Temperature Activity

In this study, the γ-MnO 2 catalyst modified with PEG exhibits outstanding low-temperature performances for NO oxidation, and in-situ DRIFTS experiments were used to systematically investigate the low-temperature NO oxidation mechanisms over γ-MnO 2 . These results demonstrated that NO was first adsorbed on the surface of γ-MnO 2 to form the nitrosyls, which could be further oxidized to nitrates under the action of the chemisorbed oxygen or lattice oxygen, and afterwards the formed nitrates were decomposed into nitrogen dioxide. Moreover, the inhibitory mechanism of SO 2 on γ-MnO 2 was also studied, and SO 2 severely inhibit the NO oxidation performance of γ-MnO 2 through forming stable sulfates that could easily consume the active sites of the catalyst to hinder the formation of nitrates, resulting in the termination of oxidation of NO to NO 2 . Clarifying the mechanisms of NO oxidation and SO 2 poison is very essential for developing better NO oxidation catalysts. Graphical Abstract