Catalytic Degradation Of Ethyl Acetate By Dielectric Barrier Discharge Combined With The Modified Natural Hematite

In order to optimize the treatment of volatile organic compounds?VOCs?by DBD dielectric barrier discharge?DBD?,a self-made DBD reactor combined with catalysts was applied to remove ethyl acetate.The Bi₂WO₆/?-Fe₂O₃,TiO₂/?-Fe₂O₃ were prepared by sol-gel methods and the CeO₂/?-Fe₂O₃ was prepared by a impregnation method,which were characterized by X-ray diffraction?XRD?,specific surface area and pore size analyzer?BET?,scanning electron microscope?SEM?and X-ray photoelectron spectroscope?XPS?.And the effects of calcined temperature and mass ratio of active component and natural hematite on the performance of catalysts were investigated.On this basis,the comparison of ethyl acetate removal efficiency and energy yield in DBD and DBD combined with catalysts systems were analyzed contrastively by function of ethyl acetate initial concentration,gas residence time and relative humidity.The effects of catalysts on the removal of ozone and mineralization rate in the plasma-catalytic oxidation process were investigated as a function of input power.In addition,the ethyl acetate degradation products were analyzed and the possible reaction pathways were primary proposed.The results showed that:?1?The Bi₂WO₆/?-Fe₂O₃ composite was prepared by a sol-gel method,which showed the highest catalytic activity with mass ratio of 0.25:1 and calcination temperature of450 ^oC.Both ethyl acetate removal efficiency and energy yield followed this rule in different process parameters:DBD/Bi₂WO₆/?-Fe₂O₃>DBD/?-Fe₂O₃>DBD/Bi₂WO₆>DBD.As the initial concentration ranged from 200–1000 mg/m³,the ethyl acetate removal efficiency in DBD/Bi₂WO₆/?-Fe₂O₃ system decreased from 95.15%to66.21%,however,its energy yield increased from 2.27 g/kWh to 7.88 g/kWh.The ethyl acetate removal efficiency in DBD/Bi₂WO₆/?-Fe₂O₃ system reached 100%with gas residence time of 1.53 s.Ethyl acetate removal efficiency increased as the relative humidity increased to about 65%,and then decreased when the humidity was>65%.The combination of DBD and catalysts significantly increased the mineralization rate and reduced the O₃ concentration in tail gas,compared with DBD system,the removal efficiency and mineralization rate of ethyl acetate in DBD/Bi₂WO₆/?-Fe₂O₃ system increased about 19.16%and 14.44%,respectively,and the ozone concentration reduced about 74.47%with input power of 84 W.The study showed that DBD combined with Bi₂WO₆/NH composite could effectively remove ethyl acetate,the final degradation products were mainly CO₂,H₂O.Combined with FT-IR and GC-MS spectra,the degradation products also contained a small amount of CO and a trace amount of small molecule organic compounds,such as CH₄,CH₃CH₂OH and CH₃COOH.?2?The TiO₂/?-Fe₂O₃ composite was prepared by a sol-gel method,which showed the highest catalytic activity with mass ratio of 0.5:1 and calcination temperature of 400 ^oC.Both ethyl acetate removal efficiency and energy yield followed this rule in different process parameters:DBD/TiO₂/?-Fe₂O₃>DBD/TiO₂>DBD/?-Fe₂O₃>DBD.Compared with DBD system,the removal efficiency and energy yield of ethyl acetate in DBD/TiO₂/?-Fe₂O₃ system increased by 24.25%and 1.15 g/kWh,respectively,with initial concentration of 400 mg/m³.As the gas residence time ranged from 0.38–1.53 s,the ethyl acetate removal efficiency in DBD/TiO₂/?-Fe₂O₃ system increased from 65.07%to 100%,however,its energy yield decreased from 4.96 g/kWh to 1.90 g/kWh.And the ethyl acetate removal efficiency reached a maximum at a relative humidity of 65%.Compared with bare DBD system,the ozone concentration in DBD/TiO₂/?-Fe₂O₃system reduced about 77.07%and mineralization rate increased about 15.76%with input power of 84 W.?3?The CeO₂/?-Fe₂O₃ composite was prepared by a impregnation method,which showed the highest catalytic activity with mass ratio of 0.4:1 and calcination temperature of 400 ^oC.Both ethyl acetate removal efficiency and energy yield followed this rule in different process parameters:DBD/CeO₂/?-Fe₂O₃>DBD/CeO₂>DBD/?-Fe₂O₃>DBD.As input power of 84 W,ethyl acetate initial concentration of400 mg/m³,gas flow rate of 1 m³/h and relative humidity of 65%,compared with DBD system,the removal efficiency,energy yield and mineralization rate of ethyl acetate in DBD/Bi₂WO₆/?-Fe₂O₃ system increased by 21.26%,1.01 g/kWh and 14.76%,respectively,and the ozone concentration reduced by 75.86%.