关键词: 选择催化还原, 烟气脱硝, 催化剂, 碱土金属中毒, 失活

Abstract:

Fresh V-W and V-Mo based SCR catalysts were prepared, and then poisoned by alkaline earth metals through three methods, i.e., impregnation, solid phase diffusion and dry mixing. Experiments were performed to investigate the denitrification activity of the catalysts affected by the poisoning method, alkaline earth metal type, catalyst promoter type and other factors. In addition, the catalysts were characterized by temperature programmed desorption (NH₃-TPD), temperature programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The results showed that among the three poisoning methods, impregnation exhibited the most significant poisoning effect on the catalysts. Ca was more toxic to the catalyst than Mg. V-Mo based catalyst possessed better anti-poisoning performance than V-W based catalyst. The presence of alkaline earth metal had many significant effects on the catalysts, including reducing the total acid sites and the acidity intensity on the catalyst surface, increasing the catalyst reduction temperature, altering the valence of the active component, and decreasing the proportion of surface active oxygen.

Key words: selective catalytic reduction（SCR）, flue gas denitration, catalyst, alkaline earth metal poisoning, deactivation