Influence of Ce-doping on MnOx-ZSM-5 catalysts for the selective catalytic reduction of NO/NO2 with NH3

A series of MnOx-CeO2/ZSM-5 catalysts with different Ce loadings were prepared through the impregnation method and characterized by BET, XRD, SEM, H-2-TPR, and XPS. The performances of selective catalytic reduction (SCR) of NO/NO2 with NH3 and NO oxidation over MnOx-CeO2/ZSM-5 catalysts were investigated. The result showed that the MnOx dispersions, redox abilities and proportions of Mn4+ of catalysts were enhanced by the doping of CeO2. However, the excessive Ce loadings led to the accumulation of active components on the catalyst surface. The sample with Ce/Mn molar ratio of 0.39 exhibited the best SCR performance, the NOx conversion achieved 95.4% at 150 degrees C, and maintained higher than 95% in a wide operating temperature range (150-350 degrees C). MnOx-CeO2/ZSM-5 also exhibited considerable catalytic performance of NO oxidation, the maximum conversion of NO achieved 56.5% at 350 degrees C.