制备方法对V2O5/WO3-TiO2催化剂脱除柴油车尾气中NOx的影响

摘要

V2O5/WO3‐TiO2 catalysts were prepared by conventional impregnation (VWTi‐con) and ultras‐ound‐assisted impregnation methods (VWTi‐HUST). Their catalytic performance was tested for the selective catalytic reduction (SCR) of NO with NH3. The effects of the preparation methods on the catalyst properties were studied. The catalysts were characterized by X‐ray diffraction, scanning electron microscopy, Raman and X‐ray photoelectron spectroscopy. Both structural investigation and NH3‐SCR activity showed that the preparation method had a strong effect on the thermal be‐havior of the V2O5/WO3‐TiO2 catalysts. After a hydrothermal treatment, a significant loss of NO re‐duction activity was observed for the VWTi‐con catalyst, which suffered severe sintering and even formed a rutile VxTi1‐xO2 solid solution, while the VWTi‐HUST catalyst had the same good hydro‐thermal stability as a commercial catalyst, indicating that the VWTi‐HUST catalyst can be used in a commercial diesel after‐treatment system. The ultrasound‐assisted impregnation method produced a stronger interaction between the vanadium species and WTi support, which stabilized the vana‐dium species in the reduced state.%分别采用普通浸渍法(VWTi-con)和超声辅助浸渍法(VWTi-HUST)制备了V2O5/WO3-TiO2催化剂，并用X射线衍射、扫描电镜、拉曼光谱和X射线光电子能谱等技术对催化剂进行了表征，评价了水热老化前后两种催化剂的NH3-SCR脱除模拟柴油车尾气中NOx的反应活性，并与国外成熟商品催化剂进行了比较。结果表明，制备方法可影响V2O5/WO3-TiO2催化剂的水热稳定性， VWTi-con催化剂老化后几乎完全失活，而VWTi-HUST具有优异的水热稳定性，与国外成熟商品催化剂性能相当。与传统浸渍法相比，超声辅助浸渍法增强了活性物种和载体的相互作用，提高了活性组分的分散性等。采用该法制备的VWTi-HUST催化剂将具有较强的商业应用性；台架试验正在进行中，以期满足柴油车国IV排放标准的要求。