Combination of non-thermal plasma and Pd/LaMnO3 for dilute trichloroethylene abatement

In this study, the oxidative abatement of dilute trichloroethylene (TCE) in humid air (RH = 18%) was studied with combined use of a negative DC corona multi-pin-to-plate discharge and Pd/LaMnO3 catalyst downstream of the discharge. For this post-plasma catalytic (PPC) system the catalyst temperature was varied and the outcome on the TCE abatement and by-product distribution was investigated. The poor COx selectivity for the plasma system is attributed to the formation of unwanted polychlorinated by-products such as phosgene, dichloroacetylchloride (DCAC) and trichloroacetaldehyde (TCAD). At an energy density (ED) of 460 J/L, the TCE abatement decreased as follows: PPC-150 degrees C (96.2%) > PPC-200 degrees C (91.7%) > PPC-100 degrees C (89.1%) > NTP (82.3%). When the temperature of Pd/LaMnO3 was increased to 200 degrees C the formation of DCAC was suppressed while the formation of phosgene was decreased in the order of 50% compared to the plasma alone system. For each PPC experiment, no ozone was detected in the outlet stream which proves that Pd/LaMnO3 is effective for ozone decomposition and substantially enhances the mineralization of TCE compared to the plasma alone system. Finally, XPS and ToF-SIMS studies have been performed after PPC experiments in order to investigate the possible surface modifications of the catalyst in the course of the reaction. (C) 2015 Elsevier B.V. All rights reserved.