Effect of antimony doped vanadium-titanium catalyst on low-temperature NH₃-SCR activity

Sb-V₂O₅-TiO₂ catalysts were prepared by wet impregnation method. The effect of antimony loadings and calcination temperatures on the activity of catalysts were investigated on the basis of 3%V₂O₅-TiO₂. The results indicate that the catalyst with 11% Sb loading, calcined at 500℃, has the best activity of SCR. The NO_x conversion could reach 92% at 170℃ with the inlet NO_x concentration of 0.07%, the O₂ volume fraction of 5%, and the space velocity of 27 000 h^-1. The H₂-TPR data reveal that the increase of activity can be attributed to the promotion of the catalyst oxidation ability by the modifying of antimony. Sb is mainly in the pentavalent antimony form on the surface of the catalyst, and the increase in surface acidity of the catalyst is identified by means of XPS and NH₃-TPD. The effects of SO₂ and H₂O on the catalyst is also studied, showing that the Sb-V₂O₅-TiO₂ has an excellent catalytic activity in the presence of H₂O and SO₂. FT-IR, TG and pore structure test results suggest that the addition of Sb can effectively inhibit the aggregation of ammonium sulfate on the catalyst surface, thereby improving the service life of the catalyst.