Oxidation of ethylene by a multistage corona discharge system in the absence and presence of Pt/TiO2

The main objective of this work was to investigate a combined plasma and catalytic reactor system for ethylene removal. A four-stage plasma system with wire and plate electrodes was employed to oxidize ethylene as a model pollutant under excess oxygen conditions. The effects of commercial TiO2, sol–gel TiO2, and 1% Pt/sol–gel TiO2 loaded on glass wool used as catalysts packed in the plasma reactors were studied. For the plasma system without a catalyst, both the ethylene conversion and the CO2 selectivity were found to increase with increasing applied voltage and the stage number of the plasma system; but increasing the frequency and feed flow rate gave the opposite effects. The presence of all studied catalysts in the plasma system was found to increase both C2H4 and O2 conversions. The CO2 selectivity increased under the presence of the catalysts in the following order: 1% Pt/sol–gel TiO2 > sol–gel TiO2 = commercial TiO2. When the TiO2 was present in the plasma reactor system, it enhanced the ethylene oxidation reaction because its reducible property provides both the reaction sites and oxygen for the reaction. The presence of 1% Pt on the sol–gel TiO2 was found experimentally to promote the CO oxidation, leading to a higher CO2 selectivity.