Active manganese oxide on MnO_x-CeO₂ catalysts for low-temperature NO oxidation:Characterization and kinetics study

Lingkun Meng¹，Jun Wang¹，Zhihui Sun¹，Jinxin Zhu¹，Hang Li¹，Jianqiang Wang¹，Meiqing Shen^1,2,3

1. Key Laboratory for Green Chemical Technology of State Education Ministry,School of Chemical Engineering & Technology,Tianjin University3. State Key Laboratory of Engines,Tianjin University

摘 要：MnO_x-CeO₂ catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO₂ and amorphous MnO_x existed in MnO_x-CeO₂ catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn₂O₃, H₂-TPR and XPS results suggested the valence of Mn in MnO_x-CeO₂ was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency（TOF） was calculated based on the initial reducibility according to H₂-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.

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