Study On Synergistic Treatment Of VOCs In Printing And Dyeing Industry By Dielectric Barrier Plasma And Catalysis Technology

Through field investigation of printing and dyeing enterprises,it shows that volatile organic compounds?VOCs?accounted for the major part in waste gas.The problems of photochemical smog and haze caused by VOCs have an increasingly serious impact on the atmospheric environment and human health.Therefore,the development of efficient,energy-saving and environment-friendly treatment technology is of great significance.Non-thermal plasma?NTP?technology is considered as a environmentally friendly waste gas treatment technology.In this work,a dielectric barrier discharge?DBD?reactor is built for exploring the feasibility of plasma and catalyst coupling technique to remove toluene with maintaining a high removal rate and energy utilization rate while reducing the generation of NO_x and other by-products.Firstly,the discharge system,the reactor parameters and the experimental conditions of DBD reactor are optimized.Then,compared the removal effect of plasma driven catalyst?PDC?with plasma technology,the removal rate,removal amount,energy density,energy efficiency,by-product production and other factors are explored in toluene removal experiment.The results show that catalysts have obviously synergistic effect with plasma and can significantly improve the energy efficiency.Finally,the optimization scheme which can remove printing and dyeing waste gas integrally is proposed.Under the effect of plasma alone,filling with?-Al₂O₃ can make the Lissajous pattern more stable and promote the micro discharge effect.The optimal frequency range of the power supply is 8.891⁹.086 kHz.When keeping conditions fixed,increasing the discharge gap would inhibit the degradation effect of toluene.But increasing the discharge length of effective area will lead to increase of toluene residence time,absolute removal amount and energy density.Moreover,energy efficiency increases firstly and then decreases.With the increase of toluene gas flow rate and initial concentration,its removal rate and energy density reduce,yet the absolute removal amount and energy efficiency increase.The main by-products of DBD plasma degradation of toluene are NO_x,alcohols,long-chain alkanes,amines and anhydrides.CO₂ concentration represents the complete oxidation degree of toluene,and its concentration increases with voltage rise.Under the synergism between catalyst and plasma,compared with?-Al₂O₃,TiO₂/?-Al₂O₃ and MnO_x-CeO₂-TiO₂/?-Al₂O₃ catalysts have obviously promoted the effect on oxidation of toluene,which significantly improve the removal rate and energy efficiency,and the order of catalyst efficiency is MnO_x-CeO₂-TiO₂/?-Al₂O₃>TiO₂/?-Al₂O₃>?-Al₂O₃.Meanwhile,Mn/Ce doped catalyst can effectively inhibit the generation of NO_x and promote the complete oxidation degree of toluene.Catalyst synthesized by impregnation method shows more microporous structure and oxidation activity than sol-gel method,which can significantly promote the synergistic effect of plasma with catalyst.