A comprehensive study on scaling up ethylene abatement via intermittent plasma-catalytic discharge process in a novel reactor configuration comprising multiple honeycomb monoliths

Abstract

Dilute ethylene (C2H4) was removed in a novel plasma reactor comprising multiple honeycomb monoliths consisting of up to four PdO/ZSM-5/monolith catalysts. These monoliths were packed in a tubular reactor separated by mesh electrodes alternatively grounded or connected to a high voltage (HV) power source. The effect of the number of monoliths on the discharge power, adsorption, and removal of C2H4 was investigated. Additionally, the influence of the energy input, C2H4 inlet concentration, and gas flow rate on the C2H4 abatement was examined. The adsorption capacity, C2H4 conversion, and energy efficiency were observed to increase as the number of monoliths increased. The effect of the palladium (Pd) loading technique, namely ion exchange (IE), incipient wetness impregnation (IM), and combined IE-IM, IE followed by IM, on the C2H4 adsorption was also studied. The combined IE-IM method presented an exceptional adsorption capacity of ∼136 µmol/gcatalyst under humid conditions despite nonpolar nature of C2H4. C2H4 removal was performed via both continuous and cycled storage-discharge (CSD) plasma-catalytic oxidation processes. The CSD process was conducted in two ways: with intermittent C2H4 feed (CSD-IEF) and with maintained C2H4 feed (CSD-MEF), both comprising intermittent plasma discharge. Intriguingly, the performance of the CSD-MEF process was superior (56 J/L, 1.61 g/kWh) to that of the CSD-IEF (119 J/L, 0.98 g/kWh), and continuous process (∼228 J/L, 0.53 g/kWh) in terms of energy efficiency as well as the overall simplicity of the system.