Insights into P-doping effect of the activity and anti-SO2/H2O poisoning of V2O5-MoO3/TiO2 catalysts for NH3-SCR

Abstract

With the increasingly stringent flue gas emission standards, water-sulfur poisoning has become one of the most pressing problems in the SCR process of coal-fired power plants.SO₂ not only deactivates the catalyst, but also reacts with water and NH₃ to form NH₄HSO₄, which then corrodes the equipment. Catalysts with water-sulfur tolerance urgently need to be developed. NH₄H₂PO₄-modified V₂O₅-MoO₃/TiO₂ SCR catalysts is prepared by an improved wet impregnation method. The effect of P element modification on the denitration performance of the V₂O₅-MoO₃/TiO₂ SCR catalyst was studied, and the catalyst was characterized by XRD, BET, SEM, TEM, XPS, TPR, TPD and Raman. When the phosphorus doping amount was 0.6 % (wt%), the P_0.6-SCR catalyst could achieve a NOx conversion rate of 95 %, and its optimal reaction temperature was 350 ℃. The characterization results show that the P element made the active components on the catalyst surface further dispersed, delayed the sintering of the catalyst at the calcination stage, and promoted the generation of B-acidic sites, enhances the surface acidity of the catalyst, and promotes the transition of VOx from a monomer state to a polymer state. Meanwhile, the P_0.6-SCR catalyst exhibits outstanding sulfur resistance while ensuring high denitration efficiency.