V_2O_5/TiO_2-SiO_2表面酸性对选择性催化还原NO及抗碱金属性能的影响  

Effect of Surface Acidity on NO Reduction and Resistance Towards Alkali Poisoning over V_2O_5/TiO_2-SiO_2

作　　者：胡石磊[1] 叶代启[1] 付名利[1] 

机构地区：[1]华南理工大学环境科学与工程学院,广州510006

出　　处：《无机化学学报》2008年第7期1113-1118,共6页Chinese Journal of Inorganic Chemistry

基　　金：东省重大科技项目(No.2KB066IS)资助

摘　　要：采用溶胶-凝胶法制备出不同配比的V2O5/TiO2-SiO2催化剂,运用低温氮吸附-脱附、XRD、FTIR对催化剂进行表征,对NH3法选择性催化还原氮氧化物(SCR)的行为及抗碱金属性能进行了研究。结果显示复合催化剂比表面积达125～413 m2.g-1,表面酸强和酸量不同程度增加,其中载体中含50%SiO2的催化剂(V5ST)表面酸量最大,在典型SCR反应温度350℃下Lewis酸很稳定,Brnsted酸稍有减少。V5ST相比传统催化剂V2O5/TiO2表现出更佳SCR活性和抗中毒性能,其原因可能是部分钾优先与催化剂表面酸结合,从而降低了对钒活性物种的毒害。不同温度下失活程度的对比表明:低温条件下SCR活性主要依赖于B酸,随反应温度升高,稳定的L酸逐渐开始发挥主导作用,失活程度相应较低。TiO2-SiO2 with various compositions prepared by a Sol-gel method.Vanadia loaded on TiO2-SiO2 were characterized with N2 adsorption-desorption,XRD and FTIR.The catalytic behavior in selective catalytic reduction（SCR） of NO by NH3 and resistance towards alkali poisoning were also investigated.The results showed that composite catalysts were with high surface area of 125～413 m^2·g^-1.A significant increase of surface acid number and strength were also observed.Catalyst with 50% SiO2（V5ST）showed the highest amounts of surface acidcentars.The Lewis acid sites remained stable and Bronsted ones decreasd slightly in typical SCR temperature of 350 ℃.V5ST presents superior catalytic performance and resistance towards alkali poisoning in comparison with a traditional catalyst V2O5 /TiO2.The reason might be that part of potassium on the surface of the catalyst preferentially interacted with acidic sites on the support,preventing vanadium species from being poisoned.The comparison of the deactivation degrees of the SCR catalysts at different temperatures indicated that SCR reactivity mainly depended on Bronsted acid at low temperature.As temperature rose up,the steady Lewis acid sites played the dominant role,which resulted in lower degree of deactivation.

关 键 词：钛硅复合载体 表面酸 选择性催化还原 钾中毒 

分 类 号：O613.72[理学—无机化学] O614.411[理学—化学]