Modification Of Supported CuSO₄ Catalyst And Its Catalytic Performance For NH₃-SCR

Nitrogen oxides(NOx)are one of the main air pollutants,which can cause great harm to the ecological environment and human health,and seriously restrict the sustainable development of the economy.At present,ammonia selective catalytic reduction(NH3-SCR)technology is widely used to remove NOx from stationary sources.Catalysts are at the heart of the technology.However,the currently used commercial vanadium-tungsten-titanium(V2O5-WO3(MoO3)/TiO2)catalysts have disadvantages such as narrow operating temperature range and biotoxicity of V2O5.Therefore,the development of environmentally friendly catalytic materials with a wide temperature window has been a hotspot in NH3-SCR research.CuSO4/TiO2 catalysts have received more and more attention due to their excellent high-temperature denitration activity and good sulfur tolerance.However,due to the weak redox properties of this catalyst,its low temperature(<300℃)activity is poor.In this study,the CuSO4/TiO2 catalyst was modified by doping MnOx and Pt to improve the redox performance of the catalyst and thus enhance its low temperature activity.The effects of MnOx and CuSO4 doping concentrations on the denitration efficiency of the modified catalysts were systematically explored,and the binding effect and structure-activity relationship of the two-component active phase were revealed.Influence.The main conclusions obtained are as follows:(1)MnOx-CuSO4/TiO2 composite catalysts with different MnOx contents were prepared by impregnation method.The doping of MnOx significantly improves the low-temperature activity of the catalyst.When the doping amount of MnOx is 10 wt%,the catalyst has the best denitration activity.The analysis found that the doping of Mn helps to increase the ratio of Cu2+/Cu2+ on the catalyst and increase the content of Mn4+.The characterization results show that the presence of Mn enhances the redox properties of the catalyst,and the NH3-SCR reaction on the catalyst proceeds according to both Eley-Rideal(E-R)and LangmuirHinshelwood(L-H)mechanisms.(2)Pt-CuSO4/TiO2 composite catalysts with different CuSO4 contents were prepared by stepwise impregnation.When the doping amount of Pt is 0.5 wt%and the content of CuSO4 is 10 wt%,the catalyst can achieve a NOx conversion rate of 99.5%at 170℃.The analysis found that the doping of Pt increased the pore volume and average pore size of the catalyst,and formed more platinum oxides.The results show that the presence of Pt greatly enhances the redox properties of the catalyst,forms more redox sites,increases the adsorbed NO2 on the catalyst,and greatly improves the low-temperature activity of the catalyst.The NH3-SCR reaction on the Pt-CuSO4/TiO2 catalyst also followed both the E-R mechanism and the L-H mechanism.