Degradation Mechanism Of Toluene Under Dielectric Barrier Discharge And Manganese-based Catalyst

With the consumption of fossil fuels and increasingly serious environmental problems,biomass has received extensive attention as an environmentally friendly renewable energy source in the world.Biomass gasification is one of the main biomass energy utilization technologies for obtaining high quality syngas.However,the presence of tar in the syngas has a very negative impact on the biomass gasification process and related equipment.It reduces gasification efficiency,corrodes gasification equipment,blocks gas pipelines,and affects and jeopardizes the operation and service life of subsequent gas equipment.Therefore,the optimization of tar removal has become a key issue restricting the development of biomass gasification technology.In this paper,toluene is used as a model compound,and in the absence of oxygen,Ar is used as a carrier gas.The effects of electric field strength and Mn catalyst loading on the yield of H₂ and light hydrocarbons?CH₄?C₂H₆ and C₂H₂,etc.?were studied.The synergistic degradation pathway and catalytic reforming reaction mechanism of toluene and CO₂ in the presence of non-thermal plasma?NTP?and Mn-based catalyst are revealed.The experimental results show that:Mn catalyst and CO₂ can increase the specific energy density of non-thermal plasma;Non-thermal plasma enhances the oxidization of the Mn catalyst on the one hand,dissociates a portion of the CO₂ into available CO on the other hand,and improves the quality of the synthesis gas;The addition of Mn catalyst increases the yield of H₂,light hydrocarbons and CO.As the electric field strength increases,the increase is more obvious.In the catalytic reforming experiments of CO₂ and toluene,the addition of Mn catalyst promoted the decomposition of CO₂ into CO and active oxygen O*,and improved the H2 yield.Density functional theory method B3LYP calculations have been performed to investigate the dissociation pathways of toluene in order to understand the mechanism of dissociative ionization of toluene after being attacked by high energy electrons in non-thermal plasma.Atomic charge distributions are derived for different ionization levels by Natural Bond Orbital.The simulation results demonstrate that:A total of eight major degradation pathways are found and the C1-C2 bond cleavage reaction was the easiest raw.The order of activation energy for the generation of H and CH₃reactions is C7-H<C1-C7<C4-H<C3-H<C2-H,and the activation energy for the ring opening reaction is C1-C2<C3-C4<C2-C3.C₇H₈³⁺can generate H₂,hydrocarbons?CH₄,C₂H₆,C₂H₄,etc.?and polymerization products during the degradation process,which is in accord with previous experimental results.The ionization reaction of C₇H₈non-thermal plasma has a profound influence on the physical structure of C₇H₈.Resulting from the existence of unpaired electrons,the C-C bond in the benzene ring is reduced,especially the chemical bond connected to C1.