(637a) Effect of MnO2 Catalyst and Electrode Geometry on Nonthermal Plasma Reactor Combined with Ceramic Filter for Trichloroethylene Decomposition

Volatile organic compounds (VOCs) emissions have been controlled by Air Pollution Control Act in Japan. There are two major types of VOC processing methods: incineration and adsorption. However, these methods are suitable for treating VOCs with high concentration levels and flow rates. On the other hand, a third method—nonthermal plasma decomposition—can effectively eliminate VOCs with low concentration levels and flow rates. Therefore, the nonthermal plasma decomposition method has been drawing more attention these days as an alternative approach because of its advantages over conventional methods. In our previous work, we developed a new type electrode system for gas treatment in which nonthermal plasma and a ceramic filter were integrated and applied it for VOCs treatment. In this study, to improve the energy efficiency and to reduce by-products of the reactor system, the effect of electrode geometry and the addition of MnO2 catalyst in the system were investigated in the application for trichloroethylene (TCE) decomposition. In the experiments, three electrodes such as rod, bolt, and plate geometries were employed and two locations of setting the MnO2 catalyst as “inside the reactor” and “downstream of the reactor” were tried. The results demonstrated that energy efficiency to decompose TCE was improved by combining with the MnO2 catalyst for both location conditions of “inside” and “downstream” of the reactor. As to by-product reduction, catalyst location of “inside” the reactor showed significant effect. Although small amount of phosgene, dichloroacetylchloride (DCAC), pentachloroethane (PCE) and tetrachloroethane generation was observed for the case of the reactor system without catalyst, phosgene, DCAC, tetrachloroethane were under the detection limit for the case of “inside” the reactor. Among three different electrode geometries, the plate electrode demonstrated highest energy efficiency for TCE decomposition regardless of catalyst location.