| Nitrogen oxides are a common atmospheric pollutants and cause great harm to the surrounding environment and people's health.Low-temperature SCR technology has attracted people's attention due to its low energy consumption and easy modification of existing boiler flue gas purification systems.Therefore,it is great significance to study catalysts with high activity at low temperature and good sulfur and water resistance.In this paper,a vanadium-free environment-friendly Mn-Ce/TiO2 catalyst was prepared for denitrification,and sulfur-tolerant and water-tolerant studies were performed by doping with metal elements.Finally,the synergistic denitrification effects of low temperature catalyst and plasma were investigated.Firstly,the Mn-Ce/TiO2 catalyst was prepared by impregnation method and its denitrification stability and sulfur tolerance and water resistance were evaluated.The study found that the catalyst has good low-temperature denitrification activity and can achieve 90%denitrification at 100°C;complete removal of NOX at 160°C,the denitrification efficiency at 220°C is about 94%,and remains unchanged within 72hours.The effect of water on the catalyst is small,mainly as a competitive adsorption.The sulfur-tolerant performance of the catalyst is poor.The 50 ppm SO2 can reduce the denitrification efficiency to 40%within 8 hours and the denitrification activity cannot be restored after the sulfur is stopped.The study also found that the catalyst deactivation process can be divided into two phases.The effect of SO2 on the denitrification effect in the first stage is mainly on the competitive adsorption,and the second stage makes the catalyst permanently inactive.Secondly,in order to improve the low-temperature and sulfur-resistance of Mn-Ce/TiO2 catalysts,the metal elements X?Fe,Sb,Sn?were doped and modified.Sb doping can improve the sulfur resistance.Under the conditions of aqueous and sulfur-containing conditions,the denitrification effects of Mn-Ce/TiO2 and Sb-doped catalysts were compared.It was found that the denitrification stability of the Sb-doped catalyst was significantly improved.Finally,the catalytic denitrification effect of DBD plasma was studied.The study found that the power supply discharge frequency has a great influence on the reactor voltage,discharge power and denitrification efficiency,and the process parameters of synergetic denitration are preferred.The effects of ammonia-sulfur addition on plasma denitrification were studied.Simultaneous addition of ammonia and ammonia sulfur can increase the efficiency of denitration,and sulfur alone can reduce the efficiency of denitration.The synergistic denitrification effect was better than the plasma denitrification under the four reaction systems of NO/O2/N2,NO/O2/N2/NH3,NO/O2/N2/SO2,and NO/O2/N2/NH3/SO2.The increasing synergistic effect of ammonia concentration increases,and the synergistic effect decreases with increasing sulfur concentration. |
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