V2O5-MoO3TiO2催化剂脱硝性能的研究

RESEARCH OF DENITRATION PERFORMANCE OF V2O5-MoO3/TiO2 CATALYST

通过挤压成型法制备了一系列蜂窝状V2O5-MoO3/TiO2催化剂,研究了钒、钼负载量对催化剂脱硝活性的影响,测试了催化剂抗硫和抗碱金属钠中毒的性能。采用X射线衍射、N2吸附-脱附、扫描电子显微镜等表征手段,对新鲜催化剂和钠中毒催化剂的物理和化学性质进行分析。结果表明:当钒负载量(w)为1.5%~2.5%时,催化剂的脱硝性能随钒负载量的增加而提高;当钒负载量(w)为1.5%、钼负载量(w)为4.0%时,催化剂的脱硝性能最优;SO2对V2O5-MoO3/TiO2催化剂的中毒作用是可逆的,可以通过热处理来恢复;当Na2O负载量(w)为2.0%时,催化剂失活严重,主要是由于钠盐在催化剂表面附聚而形成不规则的白色颗粒,覆盖了活性位点,导致催化剂的表面积减小,氧化还原性变差。同时,Na掺杂会影响催化剂中元素的化学状态和表面组成,降低V5+与化学吸附的Oα的比例。

A series of honeycomb V2O5-MoO3/TiO2 catalysts was prepared by extrusion molding.The effects of vanadium loading and molybdenum loading on the denitration activity of the catalysts and the performance of the catalysts against sulfur and alkali metal poisoning were tested.The physicochemical properties of fresh catalyst and sodium poisoned catalyst were analyzed by means of XRD,BET,SEM,H 2-TPR and XPS techniques.The results showed that when the vanadium loading(w)was in the range of 1.5%-2.5%,the denitration activity of the catalyst increased with the increase of vanadium loading.When the vanadium loading(w)was 1.5%and the molybdenum loading(w)was 4.0%,the catalyst had the best denitration performance.The poisoning effect of SO 2 on the V2O5-MoO3/TiO2 catalyst was reversible and could be recovered by heat treatment.When the Na 2O loading(w)was 2.0%,the catalyst was severely deactivated because the sodium salt agglomerated on the surface of the catalyst to form irregular white particles,covering the active site,resulting in a reduction of the catalyst surface area and poor redox performance.In addition,Na doping would affect the chemical state and surface composition of the active elements on the catalyst,reducing the ratio of V 5+and chemically adsorbed oxygen(Oα).