Effects of silica additive on the NH₃-SCR activity and thermal stability of a V₂O₅/WO₃-TiO₂ catalyst

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• 作者：Xuesong Liu^a ; ^b ; Xiaodong Wu^a ; ^b ; ^{wuxiaodong@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Tengfei Xu^a ; Duan Weng^a ; ^b ; ^{duanweng@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Zhichun Si^b ; Rui Ran^a
• 关键词：V2O5/WO3-TiO2 ; Silica ; NH3-SCR ; Hydrothermal stability ; Polymeric vanadia ; De-NOx
• 刊名：Chinese Journal of Catalysis
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：37
• 期：8
• 页码：1340-1346
• 全文大小：699 K

文摘

V₂O₅/WO₃-TiO₂ and V₂O₅/WO₃-TiO₂-SiO₂ catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750 °C in 10 vol% H₂O/air for 24 h. The catalysts were evaluated for NO_x conversion using NH₃ as the reductant. Hydrothermal ageing decreased the NO_x conversion of V₂O₅/WO₃-TiO₂ catalyst severely over the entire measured temperature range. Interestingly, the NH₃-SCR activity of the silica-modified catalyst at 220–480 °C is enhanced after ageing. The catalysts were characterized by X-ray diffraction, nitrogen adsorption, X-ray fluorescence, Raman spectroscopy, H₂ temperature-programmed reduction, and NH₃ temperature-programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO₂ crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V₂O₅/WO₃-TiO₂ catalyst was significantly improved.