Studies on Gas Purification by a Pulsed Microwave Discharge at 2.46 GHz in Mixtures of N2/NO/O2 at Atmospheric Pressure

Pulsed microwave discharges operated at atmospheric pressure in gas mixtures containing N2, O2, and NO are investigated experimentally and theoretically for various gas mixture constituents and operating conditions with respect to the ability of exhaust gas purification. The rotational gas temperature and the vibrational temperature of N2 are derived from CARS measurements. The composition of the exhaust gas after treatment is monitored using FTIR spectroscopy. The processes of the chemical, electronic, and vibrational kinetics are described by a model that has been developed to calculate the species densities. The results obtained show that in N2/NO gas mixtures an overall reduction of NOx takes place. In the case of N2/O2/NO gas mixtures, no net reduction of NOx is achieved for a pulsed microwave power below 3600 W, a pulse length of 50 μs, and a typical repetition frequency of 2 kHz.