Study On Degradation Of Dimethyl Sulfide By Fin Rod-rod Dielectric Barrier Discharge Assisted Catalyst

With the rapid development of industry in China,volatile organic sulfur compounds（VOSC_S）from living standards,the foul-smelling VOSC_S are emitted from paper mills,acetate textile mills,pesticide plants,waste composting plants are increasing,which are harmful to the environment.It can lead to global warming,acid deposition and photochemical smog,and it has certain effects on the human respiratory system,digestive system,nervous system and endocrine system.Therefore,it is urgent to carry out the management of VOSC_S.VOSC_S can be efficiently treated by non-thermal plasma technology because of its abundance of active substances.However,this technology also has problems such as low mineralization rate,high concentration of by-products（such as O₃）and unstable operation of the plasma reactor by the deposition of organic by-products on the electrodes.Based on this,two shapes fin rod-rod dielectric barrier discharge plasma reactors are designed and manufactured to separate the discharge area from the organic by-product deposition area.At the same time,the Ce-Mn catalysts are placed on the post of plasma reactor to increase mineralization treatment effect of dimethyl sulfide and reduction of ozone concentration.We studied the electrode shape of dielectric barrier discharge plasma reactor.We carried out the study of physicochemical properties of two fin rod-rod dielectric barrier discharge（DBD）with two electrode shapes.The results show that under the same voltage,the type A fin rod-rod plasma electrode structure has higher discharge intensity,higher power,stronger charge transfer,and produces more active particles and ozone.And when the discharge voltage at 10 k V,the removal rate of dimethyl sulfide and selectivity of carbon dioxide are increased by 12.55%and 8.02%,respectively.Therefore,the type A fin rod-rod electrode structure is more suitable for processing VOSC_S.We studied the performance of type A fin rod-rod DBD plasma for degradation of dimethyl sulfide.Under the same conditions,the removal rate of dimethyl sulfide and the energy input density increase with the decrease of the discharge distance.When the discharge distance with 1 mm,dimethyl sulfide removal efficiency,specific input energy and energy efficiency at 10 k V are reached 73.84%,1.09 k J/L and 2.70 g/k Wh.Under the same power condition,as the initial concentration of dimethyl sulfide increases,the efficiency of DBD plasma degradation of dimethyl sulfide and CO₂selectivity decrease,but the energy utilization efficiency increases.The degradation efficiency of dimethyl sulfide decreases and the energy utilization efficiency increases with the gas flow increases.We prepare catalysts and synergize DBD plasma to degrade dimethyl sulfide.The physicochemical properties of Ce O₂,MnO_x,Ce O₂-MnO_x（1:0.5）,Ce O₂-MnO_x（1:1）and Ce O₂-MnO_x（1:3）catalysts are characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）,the catalytic degradation of dimethyl sulfide at different calcination temperature,space velocity and Ce/Mn molar ratio are investigated.The results show that the catalytic activity of Ce O₂-MnO_x is higher than that of Ce O₂ and MnO_x.Ce O₂-MnO_x（1:1）catalyst has larger specific surface area,better redox characteristics and oxygen mobility.When the calcination temperature at 500°C,the Ce O₂-MnO_x catalyst has highest activity.The removal rate of dimethyl sulfide increases with the decrease of space velocity of the catalyst.The Ce O₂-MnO_x（1:1）has the best catalytic effect.When the power of 34.37W,the removal rate of dimethyl sulfide and the CO₂selectivity can reach 87.26%and59.77%,respectively.The degradation mechanism of single plasma and plasma catalytic degradation dimethyl sulfide are studied by gas chromatography-mass spectrometry（GC-MS）and Fourier Infrared spectrometry（FTIR）.The results show that the removal of dimethyl sulfide by plasma may be the reaction of high-energy electron and other active species with dimethyl sulfide,and produce intermediates such as acetaldehyde,methanol,acetic acid,dimethyl methane,dimethyl disulfide and ethane.The way of plasma catalytic degradation may be that the ozone produced by the discharge is decomposed into atomic oxygen which can fill the oxygen vacancy on the catalyst,thus promoting the oxidation cycle reaction of Ce/Mn.It is beneficial to the degradation of dimethyl sulfide and intermediates,and eventually decomposes into CO_x,SO₂,and H₂O.