Study On The Reduction Of NOx By NH₃ Catalyzed By Low Temperature Plasma And Manganese Based Oxides

The terminal elimination method is an important means to control the emission of nitrogen oxide pollutants.The low temperature plasma can activate the reaction components,and can promote the reduction reaction after being combined with the catalyst,and can effectively remove NOx below?150?.This method simultaneously reflects the activation performance of the plasma and the catalytic reaction performance of the catalyst,and has great prospects in NOx removal.In this paper,by comparing the plasma-activated N2/O2/NH3 reaction without catalyst and the room temperature plasma coordinated ?-MnO2 catalyzed NH3 reduction of NO reaction,through the product analysis method,we explored the plasma combined NH3-selective catalytic reduction of NOx,Catalyst performance,and its influencing factors.(1)The dielectric barrier plasma discharge of N2/O2,N2/O2/NO and N2/O2/NH3/NO gas components was studied under the condition of no catalyst.The study found that without catalyst,N2 can be oxidized by plasma to NO2,producing a small amount of NO;O2 is an important source of O3 and O radicals,and N and NO are oxidized to NO and NO2 through the oxidation of O3.When there is NO in the reaction gas,NO is preferentially oxidized;when NH3 is present,NH3 and N2 will not be oxidized to NOx.(2)The mechanism of denitrification of six gas components N2,N2/NO,N2/NO/O2,N2/NH3,N2/NH3/NO and N2/NH3/O2/NO was investigated by using y-MnO2 as catalyst for plasma cocatalyst.The results show that when there is no O2,MnO2 is ionized out of O,reacting with N to form NO and NO2,and MnO2 can decompose O3;In the absence of NH3,the catalytic reaction is mainly based on O3 oxidation,and NO is oxidized to NO2 through O3,resulting in an increase in NO2 content in the system;in the absence of NH3,the catalytic reaction is mainly based on O3 oxidation,and NO is oxidized to NO2 through O3,resulting in an increase in NO2 content in the system;after the addition of NH3,the catalytic reaction is mainly the reduction of NH3,which can suppress the generation of NO2,and can inhibit the oxidation of N2,and increase the removal rate of NO.(3)y-MnO2 showed the best catalytic activity.At room temperature,500 ppm NO intake,space velocity 47110 h-1,?-MnO2 removal rate at 308 J/L NOx is 88.8%.(4)The carrier has an effect on the catalytic activity.At room temperature,when the mechanical load ratio is 1:3,MnO2/5A reaches 96.6%NOx removal rate at 514 J/L;MnO2/Al2O3 reaches 76.5%NOx removal rate at 460 J/L.(5)Due to the presence of a reduced field strength,the reaction temperature promotes the denitrification of MnO2 and MnO2/5A,but the production of NO2 will increase on MnO2/Al2O3,resulting in a decrease in the NOx removal rate.Water and SO2 have an adverse effect on the denitration performance of the catalyst,because both can seize the energy and high-energy electrons of the catalytic reaction.In addition,SO2 will produce salt deposits on the surface of the catalyst,blocking active sites and pores,deactivating the catalyst,NOx can not react on the surface of the catalyst;long-term discharge will not affect the denitration performance of the catalyst.