Research On Dielectric Barrier Discharge Plasma Coupled With Catalysis In The Treatment Of Methyl Mercaptan

In recent years,air pollution,such as the phenomena of haze,photochemical pollution and ozone depletion,has become more and more serious,which seriously affects the ecological environment and human health.Nowadays air pollution has aroused widespread concern of the whole society.The massive emission of volatile organic compounds(VOCs),one of the inducing factors of this series of air pollution,remains to be solved.Methyl mercaptan(MSH),as one of malodorous VOCs,is widespread in nature which poses a tremendous threat to human senses and health.Some progress has been made in the research of Non-thermal plasma technology in the volatile organic compounds treatment.However,the technology still has the disadvantages like high energy consumption and generation of by-products.The current research shows that the post-plasma catalysis technology can further improve the treatment effect of the target pollutants and reduce the formation of by-products.Former research on plasma-catalytic technology focuses on decomposition of hydrocarbon organic compounds,while few studies focus on the stench of sulfur-containing organic compounds.In this paper,as a typical malodorous volatile organic compounds,methyl mercaptan was used as the research target.A post-plasma catalysis technology was used.The plasma discharge mode was dielectric barrier discharge,and the catalyst was nickel-doped activated carbon.Firstly,the degradation regularity of methyl mercaptan under different discharge parameters and gas composition was investigated.The effects of discharge voltage,discharge frequency,residence time,initial concentration of methyl mercaptan and oxygen concentration on the degradation of methyl mercaptan by plasma were investigated.Also,the degradation mechanism of methyl mercaptan is investigated.Then,nickel-doped activated carbon catalysts with different loadings were prepared.The catalysts were characterized by BET,XRD and SEM.The degradation of methyl mercaptan and its by-products were also studied.Based on the above experimental basis,the main conclusions are as follows:(1)The effects of discharge voltage,discharge frequency,residence time,initial concentration of methyl mercaptan and oxygen concentration on the degradation of methyl mercaptan by plasma were studied.With the increase of discharge voltage,residence time and oxygen concentration,the removal efficiency of methyl mercaptan increases,while the increase of initial concentration of methyl mercaptan decreases the removal rate of methyl mercaptan.The optimal discharge frequency is 8.5 kHz.(2)The study characterized different amount of nickel-doped activated carbon.The effect of the catalyst on the remaining methyl mercaptan and the ozone produced by the plasma under different nickel-doped activated carbon was investigated.