Cr-Ce/TiO_2低温催化还原NO性能研究

用浸渍法制备了Cr-Ce/TiO2催化剂,考察了焙烧温度、活性组分配比和负载量对催化剂低温NH3选择性催化还原NO活性的影响,并对催化剂进行了XRD和BET表征,得到了催化剂的最佳制备条件;探讨了H2O和SO2对Cr-Ce/TiO2催化剂活性的影响,通过FTIR表征分析了催化剂的中毒机理。实验结果表明,n(Cr)∶n(Ce)=2.0、Cr2O3和CeO2负载量(质量分数)为30%、350℃焙烧的Cr-Ce/TiO2催化剂具有良好的分散性,在气态空速10 000h-1、气体体积组成为NO0.080%,O26.000%,NH30.088%的条件下,反应温度为180℃时NO转化率高达99.6%。体积分数10%的H2O对该催化剂的活性影响很小;反应气中存在体积分数0.03%SO2的情况下,催化剂被毒化,表面生成(NH4)2SO4、NH4HSO4、金属硫酸盐和亚硫酸盐,致使催化活性降低。该催化剂有望应用于基本不含SO2的燃气锅炉烟气和不含SO2的硝酸尾气等NOx工业废气的低温脱硝。

Low-Temperature Catalytic Reduction of NO over Cr-Ce/TiO2 Catalyst

Cr_2O_3-CeO_2/TiO_2 catalysts were prepared through impregnation method and used in selective catalytic reduction of NO with NH_(3) at low-temperature.Effects of calcination temperature,(n(Cr)∶n(Ce)) and loading of active component(Cr_2O_(3) and CeO_2) on the catalyst activity were investigated.The catalysts were characterized by means of XRD and BET to obtain the optimal preparation condition.Effects of H_2O and SO_2 on the catalyst activity in the reduction were analyzed by means of FTIR.The catalyst calcined at 350 ℃ with total loading 30%(mass fraction) and(n(Cr)∶n(Ce)) 2.0 showed favorable dispersity of the active components on the support.A high NO conversion of 99.6% over the catalyst was observed under the conditions of temperature 180 ℃,GHSV 10 000 h～(-1) and feed gas composition φ(NO) 0.080%,φ(O_2) 6.000%,φ(NH_3) 0.088%.Effect of 10%(φ) H_2O on the catalyst activity was little but negative effect of 0.03%(φ)SO_2 in the feed gas on the catalyst was evident due to formation of sulfates and sulfites on the catalyst.The catalyst could be applied to removal of NO_(x) from exhaust gas without SO_2 at low temperature.