Performance evaluation of hybrid systems comprising silent discharge plasma and catalysts for VOC control

A hybrid system comprising silent discharge plasma (SDP) and manganese oxide (MnO₂) catalyst was used for the decomposition of benzene in air, The efficiency for the benzene decomposition was greatly enhanced by combining MnO₂ with the SDP reactor in the latter part. The MnO₂ catalyst decomposed benzene by using ozone, which was formed in SDP as the oxidant precursor. With increase in the amount of water vapor in air, the efficiency for the benzene decomposition was decreased, partly due to the diminished formation of O₃ in the SDP reactor. Only CO₂ and CO were obtained as the products. The carbon mass balance was not perfect due to the formation of intermediates on MnO₂ during the reaction. The intermediates were subsequently decomposed to CO₂ and CO by MnO₂ in the presence of O₃. In dry air, the selectivities to CO₂ and CO were 70% and 30%, respectively, and were almost independent of SED. The CO₂ selectivity was improved to 90% by humidifying the reaction gas.