Investigations of surface VO_x species and their contributions to activities of VO_x/Ti_0.5Sn_0.5O₂ catalysts toward selective catalytic reduction of NO by NH₃

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• 作者：Lihui Dong^a ; Chuanzhi Sun^a ; Changjin Tang^a ; Bing Zhang^a ; Jie Zhu^a ; Bin Liu^a ; Fei Gao^b ; Yuhai Hu^a ; Lin Dong^a ; ^b ; ^{donglin@nju.edu.cn} ; Yi Chen^a
• 关键词：Vanadium oxide ; Ti0.5Sn0.5O2 ; Surface structure ; Acidic sites ; &ldquo ; NO  ; +  ; NH3  ; +  ; O2&rdquo ; reaction
• 刊名：Applied Catalysis A ; General
• 出版年：2012
• 期刊代码：4_0926860x
• 类别：ch
• 出版时间：26 July, 2012
• 卷：431-432
• 期：Complete
• 页码：126-136
• 文件大小：971 K

摘要

High surface area Ti_0.5Sn_0.5O₂ mixed oxide with rutile phase was prepared by a coprecipitation method. The surface area of Ti_0.5Sn_0.5O₂ sample is 76.7 m² g^鈭?, and VO_x/Ti_0.5Sn_0.5O₂ catalysts were prepared using the mixed oxide as support. Characterizations using XRD, FT-IR, LRS, EPR, UV-vis, and TEM demonstrated that vanadium oxide species are highly dispersed on the surface of Ti_0.5Sn_0.5O₂ support when the loading amount of vanadium oxide is 鈮?.5 mmol V/100 m² Ti_0.5Sn_0.5O₂. The dispersed vanadium oxide species form epitaxial-growth layer on the support. In situ FT-IR (NH₃ adsorption), combined with NH₃-TPD, indicate that the catalyst with vanadium loading amount of 1.5 mmol V/100 m² Ti_0.5Sn_0.5O₂, which equals to the dispersion capability, possesses a maximum amount of Br酶nsted acid sites. The 1.5V/Ti_0.5Sn_0.5O₂ catalyst exhibits the best catalytic performance and good resistance to water vapor poison for the 鈥淣O + NH₃ + O₂鈥?reaction, indicating that surface dispersed polymeric vanadium oxide species are the primary active species. A possible reaction mechanism is proposed on the basis of in situ FT-IR results.