x-ZSM-5 catalysts for the selective catalytic reduction of NO/NO 2 with NH 3]]>

摘要

A series of MnO~(x)-CeO~(2)/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/NO~(2)with NH~(3)and NO oxidation over MnO~(x)-CeO~(2)/ZSM-5 catalysts were investigated. The result showed that the MnO~(x)dispersions, redox abilities and proportions of Mn_(4+)of catalysts were enhanced by the doping of CeO~(2). 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 NO~(x)conversion achieved 95.4% at 150?°C, and maintained higher than 95% in a wide operating temperature range (150–350?°C). MnO~(x)-CeO~(2)/ZSM-5 also exhibited considerable catalytic performance of NO oxidation, the maximum conversion of NO achieved 56.5% at 350?°C.