Carbon monoxide production in silent discharge plasmas of air and air-methane mixtures

CO production in high-voltage alternating current (HVAC) silent discharge plasmas of air and air-methane mixtures at atmospheric pressure has been investigated by matrix isolation FTIR spectroscopy. In pure air, CO is produced by decomposition of CO₂. A steady-state CO/CO₂ ratio was determined by varying the flow rate. CO production was considerably enhanced when methane was added to the plasmas. CO production was observed even at very low oxygen concentrations, and did not noticeably decrease due to secondary oxidation reactions, even when methane was discharged in a pure oxygen carrier. CO production in air-methane mixtures is shown to depend on input power. CO production from CO₂ and hydrocarbons in air appears to be a significant obstacle for development of a plasma-based air purification device.