Research On Automobile Exhaust Purification Technology Based On Non-Thermal Plasma

In recent years,with the rapid development of the economy,the rapid increase of human demand for automobiles leads to the increasingly serious problem of automobile exhaust pollution.Among them,NO_x emission in automobile exhaust is the key to environmental pollution.Therefore,scientific and efficient reduction of NO_x and other harmful pollution gas emissions in automobile exhaust is the focus of current research work.However,the traditional in-plane and out-plane purification technology will bring disadvantages to the power and economy of the automobile.At present,non-thermal plasma technology and non-thermal plasma co-catalysis technology have a good application prospect in the purification of NOx from automobile tail gas and other combustion flue gas.The non-thermal plasma technology can activate the reaction gas component and promote the chemical reaction at room temperature.However,the combination of non-thermal plasma and catalyst can bring into play the advantages of high selectivity of catalytic reaction and the characteristics of plasma activation reaction molecules at room temperature,which can effectively promote the purification of NO_x.In this paper,according to the basic theory of non-thermal plasma and determined on the basis of previous studies the experimental research method,the dielectric barrier discharge plasma reactor at low temperature was developed,has set up a platform experimental system,using dielectric barrier with low temperature plasma and non-thermal plasma co-catalytic technology to complete the simulation experimental research on the basis of NO in automobile exhaust purification and the reaction mechanism of the part.The specific experimental contents and conclusions are as follows:First,according to the basic theory of non-thermal plasma produced by dielectric barrier discharge,the physical and chemical reaction process of removing NO_x by dielectric barrier discharge is analyzed,and the experimental research method is determined.A dielectric barrier discharge reactor and an experimental system platform were built.Secondly,the non-thermal plasma method of dielectric barrier discharge was used to purify the NO in simulated automobile exhaust gas.The effects of reactor structure parameters,discharge parameters,gas parameters and temperature parameters on NO purification efficiency in simulated gas NO+N₂ were analyzed.The experimental results showed that the NO purification efficiency first increased and then decreased with the increase of discharge gap,and the optimal discharge gap was 2mm.The electrode length increases with the increase of discharge outer electrode length.The increase of input voltage is beneficial to the purification of NO.When the input voltage is 140V,the frequency with the optimal purification efficiency is 10kHz,and the purification efficiency for NO is75.6%.The increase of gas concentration and flow is not conducive to the purification of NO.The presence of O₂ and CO₂ also inhibited the purification of NO.The increase of temperature is conducive to the generation of dielectric barrier discharge phenomenon and the promotion of NO purification,and 200?is the best experimental temperature.Thirdly,5%CuO/?-Al₂O₃ catalyst was selected and prepared,and a non-thermal plasma co-catalyst was used to purify NO in simulated automobile exhaust.The effects of different synergisms between plasma and catalyst,catalyst load,catalyst particle size,NO concentration,gas flow rate and gas temperature on NO purification efficiency in simulated gas NO+N₂ were analyzed.The results showed that the one-stage coordination,the full load of catalyst and the catalyst particle size of 3mm were more favorable to the purification of NO.Compared with the dielectric barrier discharge method,the purification efficiency of NO under different input concentrations of NO is improved by 15%-59%.Under different gas input flows,the purification efficiency of NO increased by 15%-56%.The overall NO purification efficiency increased by 11%-57%at different input gas temperatures,and the temperature of the optimal purification efficiency was 200?.Finally,this paper summarizes and prospects the experimental research on the purification of NO in automobile exhaust by dielectric barrier discharge non-thermal plasma and non-thermal plasma co-catalysis.