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柴油机以低油耗、 高效率、 动力强的优点,近年来得到了广泛的应用,但其尾气对城市环境的污染日益严重.NH3-SCR是目前处理柴油机尾气NOx最成熟的技术,V2 O5/WO3-TiO2催化剂因具有良好的NOx净化效率和优异的抗硫性能已得到商业应用,但低温活性和高温稳定性还有待提高.本文研究了SiO2改性对V2 O5/WO3-TiO2催化剂(V2 O5负载量为3％(质量分数))NH3-SCR反应性能的影响.评价结果表明,SiO2改性催化剂在空速为60000 h-1的条件下,低温区SCR反应性能有所下降,但是高温区SCR反应性能显著提高,催化剂表现出较宽的操作温度窗口,即NOx转化率在205～520℃之间达80％以上.与V2 O5/WO3-TiO2催化剂相比,温度窗口向高温拓宽了约50℃,并且经550℃老化50 h后其活性基本保持不变.表征结果表明,SiO2改性显著增大了催化剂的比表面积,抑制了TiO2颗粒的增大,可稳定钨钛载体的结构,有利于钒和钨物种的分散;同时SiO2改性还增加了催化剂表面酸位点的数量和强度,并抑制NH3在高温氧化生成副产物.“,”The diesel engine has been widely used in recent years due to its high fuel economy and strong power .However, the diesel exhaust seriously pollutes the urban air .The selective catalytic reduction of NO x by ammonia ( NH3-SCR) was proved to be the most ef-ficient method to remove NOx in the diesel exhaust.Commercial V2O5/WO3-TiO2 catalyst was utilized commercially due to its high effi-ciency and excellent anti-sulfur performance , but its high temperature thermal stability and light-off activity still need to be improved . The effects of SiO2 on the catalytic activity of V2O5/WO3-TiO2 with 3％V2O5 for NH3-SCR were investigated.The results showed that the doping of SiO2 slightly decreased the light-off activity, but increased the high-temperatures activity of V2O5/WO3-TiO2 significant-ly, and more than 80％NOx conversion was achieved in the temperature range of 205～520 ℃ at a GHSV of 60000 h-1 .Compared with V2 O5/WO3-TiO2 , the operation temperature window of SiO 2 doped V2 O5/WO3-TiO2 was broaden to higher temperature about 50℃.In addition, the NH3-SCR activity of SiO2 doped V2 O5/WO3-TiO2 could be maintained after calcinated at 550 ℃ for 50 h.The characterization results showed the doping SiO 2 increased the surface area , inhibited the growth of TiO 2 particles and stabilized WO 3-TiO2 support, which resulted in a good dispersion of vanadium and tungsten species .Moreover, the presence of SiO2 improved the a-mount of acid sites and acid strength , which were available for the NH 3 adsorption and inhibited the oxidation of NH 3 at high tempera-ture.