V2O5@CeO2核壳微球结构的脱硝催化剂制备及其抗硫性能

Preparation and SO_2-resistance of V_2O_5@CeO_2 core-shell microspheres for SCR de NO_x

利用静电自组装法制备了V_2O_5@CeO_2核壳微球结构,并负载在TiO_2上。考察了分散剂六偏磷酸钠(SHP)对表面zeta电位的影响,采用扫描电镜(SEM)、投射电镜(TEM)观察了核壳结构的形貌,并在固定床上进行了脱硝性能测试,并通过比表面积(BET)、氨气吸附漫反射(in situ DRIFTS)等进行表征。结果表明:SHP使纳米颗粒表面带负电,且一定范围内SHP浓度越高,zeta电位越大;含质量分数1%V_2O_5、5%CeO_2的催化剂,在260~400℃间具有80%以上的脱硝效率,对比了该核壳结构与传统浸渍法制备催化剂的抗硫抗水性,烟气中含15%(体积分数)H_2O,SO_2含量较低时,脱硝性能优于传统浸渍法制备的催化剂。

V2O5@CeO2 core-shell microspheres are prepared by electrostatic self-assembly technique and supported on TiO2. Influences of dispersant（SHP） on zeta potential are investigated. Morphology of obtained microspheres are observed by TEM and FESEM and the catalytic performance for the selective catalytic reduction of NOx with NH3（NH3-SCR） was investigated in a fixed-bed stainless steel reactor. The catalysts are characterized by BET and in situ DRIFTS analysis of NH3 adsorption. The results show that the nanoparticle surface is negatively charged by dispersant（SHP） and within a certain range, the higher the concentration of SHP is, the greater the zeta potential are. Catalysts with mass fraction of 1% V2O5 and 5% CeO2 show high activity with the NOx conversion over 80% from 260 to 400℃. Compared with catalysts prepared by the traditional impregnation method, the core-shell catalysts present higher SO2 and H2O resistance at low SO2 concentration. When the flue gas contains 571 mg·m^-3 SO2 and 15%（vol） H2O, the NOx conversion can be maintained at a high level of 80% after 7 hours.