Combination of a pulsed microwave plasma with a catalyst for acetylene oxidation

The potential of an approach combining a pulsed microwave discharge with a catalytic packed bed reactor for the oxidation of volatile organic compounds (VOC) has been studied. The ignition of the plasma has been made possible by inserting ferroelectric BaTiO3 pellets inside the microwave excitator. As a test VOC molecule, acetylene (C2H2) in an amount of 200 ppm in dry air was used. The total oxidation products CO and CO2 have been monitored downstream of the plasma region by tuneable diode laser absorption spectroscopy in the infrared region. The oxidative efficiency was found to increase linearly with the pulse repetition rate. The oxidative efficiency and the CO2/CO selectivity were considerably enhanced when the catalyst was located inside the plasma region, which shows the synergetic effect of the plasma-catalyst combination. (C) 2004 American Institute of Physics.