The Degradation Of Benzene By Bipolar Nanosecond-pulsed Series Surface/Packed-bed Discharge Reactor Over Catalyst

The emission of volatile organic compounds (VOCs) to the atmosphere is detrimental to both global environment and human health. Comparing to traditional strategies of VOCs treatment, non-thermal plasma accompanies with high treatment efficiency and selectivity as well as considerable industrial application. Bipolar pulsed series surface/packed-bed discharge reactor (SSPBD) is studied to degrade VOCs in this thesis in order to avoid disadvantages of low energy efficiency and mineralization efficiency caused by single surface and packed-bed discharge plasma reactors. SSPBD reactor contains surface and packed-bed discharge configurations at the same time, which realizes the sequence degradation for contamination as well as rising its degradation efficiency. Catalyst was used to combine with plasma to increase benzene degradation efficiency, mineralization efficiency and produce less by-products. This thesis studies various aspects of the SSPBD reactor, including the advantages of it, the optimization of structural and electrical parameters of the reactor and the plasma-catalysis process. Main work and results are as follows:(1) The degradation efficiencies of benzene in the SSPBD, SD and PBD reactors were studied in this section. It was found that the benzene degradation efficiencies of the SSPBD reactor were 29% and 11% higher than the single SD, PBD reactors respectively at 10.33 W, with 17%,9% higher in CO2 selectivity and 3.1,1.0 mg/L higher in O3 generation. Also, the packed-bed discharge region in the SSPBD reactor played a more important role in active species generation and degradation of contamination from various aspects, such as benzene degradation efficiency, CO2 selectivity, O3 generation, NO2 concentration and the optical emission spectroscopy.(2) The structural and electrical parameters were optimized in this section. It can be found that higher benzene degradation efficiency was obtained with the inner diameter of the outside organic glass tube of 33.8 mm, the thickness of the inner quartz tube of 3.1 mm, screw pitch of 12 mm, diameter of the discharge electrode of 1.2 mm and the diameter of the packed-bed metarials of 2mm.50 Hz and 1 nF were the best matching results for this experimental system.(3) The catalysts of MnO2-TiO2/zeolite, TiO2/zeolite and MnO2/zeolite were combined with the SSPBD reactor. It was found that the catalystic activity of MnO2-TiO2/zeolite was better than TiO2/zeolite and MnO2/zeolite. For example, at 10.33 W, the benzene degradation efficiency, CO2 selectivity, O3 decomposition efficiency and NO2 concentration of MnO2-TiO2/zeolite were 23%,19%,72% and 48% higher than the single plasma discharge process respectively. Additionally, when the catalyst located at the end of the SSPBD reactor and the humidity is 25%, the system could achieve higher benzene degradation efficiency.