TCE abatement with a plasma-catalytic combined system using MnO2 as catalyst

A multi-pin-to-plate negative DC corona/glow discharge combined with MnO2 catalyst placed downstream of the plasma reactor was experimentally investigated for the abatement of trichloroethylene (TCE) in dry air. For the plasma alone system even at 240 J/L, the COx-selectivity did not exceed 15%, due to the formation of oxygenated intermediates (phosgene, dichloroacetylchloride). However, by combining both systems, the TCE abatement was improved and the selectivity of the process was greatly enhanced towards total oxidation. For the plasma-catalytic system, the activation energy (1.5 kcal/mol) was significantly decreased compared to pure catalytic conditions (8.7 kcal/mol), suggesting that the oxygenated intermediates produced by the plasma are more susceptible for catalytic oxidation than TCE. Furthermore, the ozone produced by the plasma is able to dissociate on the catalyst surface by a Rideal-Eley mechanism, thereby creating peroxide surface groups which greatly improve the oxidation of TCE. Based on the experimental results, a reaction pathway for the plasma-catalytic TCE abatement is suggested. (C) 2014 Elsevier B.V. All rights reserved.