纳米负载型选择性催化还原反应催化剂的制备和性能研究

Study of Preparation and Activity of Selective Catalytic Reduction Nano-loading Catalysts

采用溶胶凝胶法和浸渍法制备了以陶瓷颗粒为骨架的纳米级V2O5-WO3/TiO2(C)催化剂,并用X射线衍射(X-ray diffraction,XRD)和扫描电子透镜(transmission electron microscopy,TEM)表征了催化剂的晶型和形貌。研究了TiO2凝胶热处理温度和WO3负载量等重要参数对催化剂在以NH3为还原剂的选择性催化还原(selectivecatalytic reduc-tion,SCR)系统中的反应温度窗口、抗硫性的影响。最后考察了催化剂在不同NH3/NO比、O2含量、空速等因素下的性能指标。结果表明,在260～420℃的温度范围内,以陶瓷为骨架的负载型纳米V2O5-WO3/TiO2催化剂具有较高的SCR催化活性,且性能稳定;TiO2以锐钛形式存在的催化剂表现出高的抗硫性能,而TiO2以锐钛和金红石混晶形式存在时,抗硫性能比较差,但硫的中毒是可逆的,可再生;WO3负载量的增加提高了催化剂的活性。

Nano-TiO2/ceramic supported V2O5-WO3 catalyst （V2O5-WO3/TiO2（C）） was prepared by sol-gel method and impregnation method. The V2O5-WO3/TiO2（C） catalyst was characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. It was studied the influences Of heat treatment temperature of TiO2 gel and WO3 loadings on reaction temperature windowand catalyst resistance to SO2 poisoning in NH3-SCR system. The effects of NH3/NO ratio, O2 concentration and gas hourly space velocity （GHSV） on the activity of the catalysts were also evaluated. The results show that V2O5-WO3/TiO2（C） catalyst has high and steady activity over the temperature range 260-420℃. The V2O5-WO3/TiO2（C） （anatase） catalyst shows high resistance to SO2 poisoning. To the contrary, The V2O5-WO3/TiO2（C） （mixture of anatase and rutile） catalyst is easily poisoned by SO2. SO2 poisoning is reversible and regeneration is feasible. The results also show that increasing of WO3 loadings can improve the activity of the catalyst.