Plasma catalytic removal of VOCs using cycled storage-discharge (CSD) mode: An assessment methodology based on toluene for reaction kinetics and intermediates

The cycled storage-discharge (CSD) mode features significant energy saving and negligible amount of secondary pollutants, boosting immediate application of plasma catalytic removal of VOCs. We report here a novel evaluation methodology for reaction kinetics and intermediates studies on plasma oxidation of adsorbed toluene in the CSD mode. Experiments were performed using toluene as a model VOC adsorbed on HZSM-5 in a storage stage and O2 plasma powered by pulsed high voltage in a discharge stage. Discharge time-dependent conversions of adsorbed toluene were obtained, and thus the apparent kinetic order of adsorbed toluene and apparent rate constant were determined. The intermediates identification was implemented, being mainly formic acid and oxalic acid. Discharge time-dependent selectivity of intermediates shows an inverse variation to that of CO2, which indicates conversion of the intermediates into CO2. CO is an insignificant product. The carbon balance verifies the reliability of this evaluation approach.