The possibility of removing toxic impurities from gaseous streams by electrical gas discharges has been investigated for almost a decade. Cold discharges, i.e. plasmas in which the electrons are not in thermal equilibrium with ions and molecules, seem to be a potential method for the conversion of (, ) in exhaust gases of cars or in flue gases of incineration plants. In this work we present a model for the temporal evolution of the plasma chemical processes in a dielectric barrier discharge in a mixture containing , , O and small amounts of NO, and optionally H (ethene). The results of the calculations are compared with our experimental data. Quantitative analysis of the reaction turnovers allows the identification of the main chemical pathways. Most of the conversion of is due to oxidation and only a small fraction is caused by chemical reduction. The complete removal of NO can be achieved at an energy expense of 5 to 10 eV per NO molecule if 2000 ppmv H are present in the gas stream. If H is not present 60 eV/NO are needed.

Experimental results on pulsed corona and dielectric-barrier discharge processing of very dilute concentrations of NO in N2 are presented. These NO reduction experiments measure the G value for electron-impact dissociation of N2 and are used to infer the effective electron mean energy in an N2 discharge plasma at atmospheric pressure. The data have been obtained from three different laboratories using widely differing electrode structures, voltage wave forms, power measurements, and chemical analyses. The NO reduction yields from the discharge reactors tested are all similar, corresponding to an electron mean energy of 4.0±0.5 eV.