Experimental Studies Of Removing VOCs Pollution In Air By The Synergistic Effect Of Silent Discharges And Catalysts

The pollution control of volatile organic compounds (VOCs) is receiving more and more attention. Recently, non-thermal plasma technology is regarded as a more promising new technology in VOCs control all over the world. In normal temperature and pressure, different VOCs at various concentrates can be decomposed by this technology in a short time. In plasma chemistry reaction, plasma catalysis is the significant way to reduce the energy cost and improve the decomposition rate.In this study, the improvement of removing VOCs in air was investigated by combining silent discharges driven by different power-supplies with catalysts (pulse-power was used on silent discharges for the first time). On elementary theory of non-thermal plasma catalysis, a set of equipment for experiment has been set up. On this equipment, the experiment was carried out to study the effect of the destruction of toluene and chlorobenzene. The influences of the removal efficiency of toluene and chlorobenzene by the parameters of power supplies (AC high voltage, monopole pulse high voltage, bipolar pulse high voltage) and engineering mainly are researched. Furthermore, the effect of multi-combinations of dielectric barrier discharges and catalysts, the influence of energy efficiency by bipolar pulse-power, and the mechanisms of different plasma promoted catalysis processes were discussed.The results indicated:1) VOCs decomposition rate can be directly affected by specific input energy (energy density) . In the same power parameters, VOCs decomposition rate goes lower as VOCs concentrate goes higher or gas flow rate goes faster or the gap of electrodes is longer.2) The silent discharge reactor induced bipolar pulse power-supply can combine advantages of short pulse corona discharge and dielectric barrier discharge as well. The results present that bipolar pulse high voltage has advantages over 50Hz AC high voltage and monopole pulse high voltage, and the highest removal efficiency of VOCs is gained: at 36kV and 0.56L/min, the decomposition rates of toluene and chlorobenzene were 97% and 67%, respectively, with energy efficiency 12.7g/kWh and 10.7g/kWh.3) Pulse high voltage enhance the intensity of electric field, and produce strong instant discharge and energized particles responsible for effective fission ofchemical bonds of VOCs. This energy can activated effectively catalysts of MS-4A and MnCVALP located in the afterglow area to achieve the synergistic effects of effective fission of chemical bonds of VOCs? It was considered that the gas-chlorobenzene and the chlorobenzene adsorbed on the catalysts were decomposed simultaneously by silent discharges and driven catalysts. When Mn-La catalyst was used in afterglow of reactor, the VOCs decomposition rate of 425ppm chlorobenzene was 85.5% with energy efficiency 12.1g/kWh at 0.70L/min.4) The energy efficiency were enhanced despite the different plasma promoted catalysis processes of MS-4A and transition metal oxides.