Abstract
The present work reports the decomposition of a model volatile organic compound (VOC), toluene, in a packed-bed dielectric barrier discharge (DBD) plasma reactor. For this purpose, 2.5 wt% MOx/gamma-Al2O3 (M = Mn and Co) catalysts prepared by the wet impregnation method were utilized for packing. The influence of varying input toluene concentration (between 50 and 200 ppm) and different packing conditions (surface modifications of gamma-Al2O3 with Mn and Co oxides) on the conversion of toluene, product selectivity of CO and CO2, and ozone formation were studied. Surface-modified gamma-Al2O3 showed improved CO2 selectivity compared to gamma-Al2O3 and bare plasma. CoOx/gamma-Al2O3 effectively decomposed 50-ppm toluene (95% at 3.8 W) with about 70% CO2 selectivity. MnOx/gamma-Al2O3 and CoOx/gamma-Al2O3 displayed the similar conversion effect at higher toluene input. Almost 98% carbon balance and suppressed ozone formation were observed using surface-modified gamma-Al2O3, signifying the necessity of integrating metal oxide to achieve effective conversion and maximum selectivity towards the desired products. The mean electron energies and electron energy distribution function were also calculated using BOLSIG+ software. The high-performance packed-bed DBD system packed with supported 2.5% MOx/gamma-Al2O3 offers a promising approach using highly active transition metal oxide-based catalysts for VOCs removal.