Modification of Cu/ZSM-5 catalyst with CeO₂ for selective catalytic reduction of NO_x with ammonia

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• 作者：Xuesong LIU (刘雪松)^a ; ^b ; Xiaodong WU (吴晓东)^a ; ^b ; ^{wuxiaodong@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Duan WENG (翁 端)^a ; ^b ; ^{duanweng@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Lei SHI (石 磊)^c
• 关键词：Cu/ZSM-5 ; CeO2 modification ; NH3-SCR ; CuO clusters ; surface acid sites ; rare earths
• 刊名：Journal of Rare Earths
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：34
• 期：10
• 页码：1004-1009
• 全文大小：893 K

文摘

Cu/ZSM-5 and CeO₂-modified Cu/ZSM-5 catalysts were prepared by a wetness impregnation method. The addition of CeO₂ was found to enhance the NO_x selective catalytic reduction (SCR) activity of the catalyst at low temperatures, but the high-temperature activity was weakened. The catalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), H₂ temperature-programmed reduction (TPR) and NH₃ temperature-programmed desorption (TPD). The results showed that more CuO clusters instead of isolated Cu²⁺ species were obtained on the modified catalyst. These active CuO clusters, as well as the Cu-Ce synergistic effect, improved the redox property of the catalyst and low-temperatures SCR activity via promoting the oxidation of NO to NO₂ and fast SCR reaction. The loss in high-temperatures activity was attributed to the enhanced competitive oxidation of NH₃ by O₂ and decreased surface acidity of the catalyst.