Study Of MgO Cathode Pulsed Discharge Plasma And Coupled With Catalysis For Toluene Degradation

Low temperature plasma technology is a kind of advanced oxidation technology,which has the advantages of easy control of reaction conditions,high treatment efficiency and non-selectivity to pollutants,and is widely used in the field of environmental governance.Among them,the pulsed discharge has the characteristics of high breakdown voltage,high electron energy and multi-channel discharge,which has become a hot technology in the treatment of volatile organic compounds?VOCs?.In order to solve the problems of few active materials and low energy efficiency in this method,the number and density of high energy electrons in pulse discharge plasma and discharge intensity are increased by MgO modified cathode,which provides conditions for efficient production and application performance of active substances in atmospheric pressure pulse discharge plasma.In order to solve the problems of incomplete degradation of pollutants,low mineralization rate of products and insufficient utilization of O₃produced in the discharge process,the pulse discharge plasma is further combined with post-catalyst to improve the energy efficiency of the application of pulse discharge plasma and achieve the purpose of efficient VOCs treatment.The specific research contents are as follows:?1?MgO/stainless steel?SS?cathode was prepared by electrodeposition,the photo-electric characteristics of pulsed discharge of MgO/SS cathode were studied.The results showed that the optimal thickness of the MgO layer was 8.41um,and the peak current of the cathode discharge of the MgO hammer SS cathode was 20%higher than that of the SS cathode.The peak current increased with the increase of pulse flattop width and pulse fall time,but decreased with the increase of pulse rising time.Compared with SS cathode,MgO/SS cathode discharge weakened the intensity of primary streamer,enhanced the intensity of secondary streamer,and increased the emission spectral intensity of N₂?C³?_u,???B³?_g,????and electron density.?2?The effects of reactor parameters on toluene degradation efficiency under different cathode conditions,and the effects of pulsed discharge parameters and gas phase parameters on toluene degradation efficiency and energy efficiency were investigated,and the degradation products were analyzed.The results showed that compared with SS cathode,the discharge with MgO/SS cathode effectively improved the degradation efficiency of toluene,promoted the generation of O₃ and the CO₂ selectivity in the product.When the initial concentration of toluene was 100 ppm,the gas residence time was 0.39 s,the electrode spacing was 8 mm,and the number of reactor pins was 18,the pulsed discharge of SS cathode and MgO/SS cathode has the best degradation effect on toluene.?3?The degradation of toluene by pulsed discharge with MgO/SS cathode and Mn-Ce/rGO catalyst was studied.The effects of different component ratio and space velocity of catalyst on toluene degradation were compared.Compared with the plasma alone,the introduction of Mn-Ce/rGO catalyst could effectively improve the toluene degradation efficiency and CO₂selectivity.Different Mn/Ce mass ratio affect the physical and chemical properties of the catalyst,resulting in differences in catalytic performance.The catalyst activity was the highest when Mn/Ce mass ratio was 8,under the optimum conditions,toluene degradation efficiency and CO₂ selectivity increased by 27.5%and 22.0%,respectively.The catalyst could promote the conversion of O₃ to more active oxygen-containing substances,further mineralize toluene and intermediate products into CO₂ and H₂O.