Study On Denitrification Of Flue Gas By Catalytic Reduction With Dielectric Barrier Discharge

Nitrogen oxides（NO_x）,as the main pollutants of industrial flue gas,is not only the main precursor of acid rain and photochemical smog,which will cause serious harm to the environment,but also cause great harm to human health.In this paper,low temperature plasma co-catalytic reduction（NTP-SCR）was used to remove NO_x.α-Mn O₂ catalyst was prepared and Ce metal was doped to improve the NOx removal rate.The effects of different gas components and discharge reactor structure parameters on the removal of NO and the effects of different loading methods and carriers on the removal of NO_x by low temperature plasma co-catalytic reduction were discussed.（1）The discharge conditions of N₂/O₂,N₂/O₂/NO,N₂/O₂/NH₃ and N₂/O₂/SO₂ under empty tube,V₂O₅-WO₃/Ti O₂ and Mn-based catalysts were compared.The presence of a time-space tube in O₂ and the discharge of vanadium-tungsten-titanium catalysts can generate O₃ oxide N₂ or NO to generate NO_x,while the filling of Mn-based catalysts will decompose O₃ on the catalyst surface and enhance the REDOX capacity of the catalysts.When the catalyst is filled,NO_x can be removed by adding NH₃.（2）In N₂/NH₃/O₂/NO atmosphere,the denitrification effect of catalysts with different Mn/Ce ratios is stronger than that ofα-Mn O₂ catalyst,and the best effect is achieved when Mn/Ce ratio is 1,which can maintain the above 95%NOx removal rate in the range of 200～400J/L.XRD and BET results show that the specific surface area of Mn-Ce catalyst is 6.3 times that ofα-Mn O₂ after doping Ce,and the crystal type of the catalyst is amorphous.H₂-TPR results show that the reduction temperature is reduced,which provides favorable conditions for low temperature plasma co-catalytic reduction and denitrification.（3）The effects of reactor parameters and gas component content on NTP-SCR were studied.With the increase of discharge length,the NO_x removal rate decreased and the discharge mode changed.With the increase of discharge gap,NOx removal increases first and then decreases;The addition of O₂ can improve the denitration effect,but with the increase of O₂ content will produce a certain inhibitory effect;The best denitration effect can be obtained when the ammonia-nitrogen ratio is 1.（4）Ce metal doping can effectively improve the water and sulfur resistance of Mn-based catalyst.The addition of SO₂ will be oxidized by plasma and first consume NH₃,thus hindering the occurrence of SCR reaction.The doping of Ce can reduce the formation of sulfate,change the crystal shape and microstructure of catalyst,increase the number of active sites,and thus improve the water and sulfur resistance（5）The preparation method of supported catalyst and its influence on the catalyst,the Mn-Ce catalyst prepared by hydrothermal deposition method,coprecipitate method and impregnation method reached the maximum NO_xremoval rate at 189J/L,216J/L and 313J/L,respectively.Ti O₂ and Al₂O₃supported catalysts can improve the sulfur resistance of Mn O₂.The tolerance degree of Mn O₂/Al₂O₃ to SO₂ is slightly lower than that of Mn O₂/Ti O₂.Compared with the catalyst prepared by impregnation method,the denitrification and sulfur resistance of MN-based catalyst prepared by hydrothermal deposition method are better,and the performance of Ti O₂supported catalyst is better than that of Al₂O₃ supported catalyst.