添加Cl离子对V_2O_5-WO_3/TiO_2催化剂低温NO转化率的影响

考察添加不同含量Cl离子对浸渍法制备的Cl-V_2O_5-WO_3/TiO_2催化剂低温NO转化率的影响。随着Cl离子质量添加量从0增加到2.5%,Cl-V_2O_5-WO_3/TiO_2催化剂NO转化率先升高后降低,结合在含有SO_2和H2O的SCR实验结果,确定1.5%Cl-V_2O_5-WO_3/TiO_2为性能最优催化剂。在反应温度为149-362℃,NO转化率大于95%;在145-385℃,NO转化率大于90%。采用XRF、BET、XRD、TG、FT-IR和H2-TPR等方法表征了催化剂的物理化学性能和结构。结果表明,在反应气氛中加入SO_2和H2O后,催化剂比表面积和孔容均减小,副反应产物含有NH+4和SO_2-4。适量Cl离子可以抑制硫物种沉积,减少副反应产物生成,增强催化剂抗中毒能力。

Effects of Cl ions on low-temperature NO conversion by NH3 over V2O5-WO3/TiO2 catalysts

The Cl-V₂O₅-WO₃/TiO₂ catalysts were prepared by impregnation methods. With the Cl ions content increased from 0 to 2.5%, the NO conversion of Cl-V₂O₅-WO₃/TiO₂ catalysts increased at first and then decreased. Combined with the experimental results, 1.5% Cl-V₂O₅-WO₃/TiO₂ catalyst was the optimal catalyst, NO conversion was higher than 95% in the range of 149-362℃, and NO conversion was higher than 90% in the temperature range of 145-385℃. The catalysts were characterized by XRF, BET, XRD, TG, FT-IR and H₂-TPR. The specific surface area and pore volume of the catalysts decreased in different degrees after adding SO₂ and H₂O in reactant gas. The poisoned catalysts deposited sulfur species and contained NH₄⁺ and SO₄^2-. Adding appropriate amount of Cl ions inhibited the formation of side byproducts and enhanced the poisoning resistance of V₂O₅-WO₃/TiO₂ catalyst.