Experimental study of NO2 reduction in N2/Ar and O2/Ar mixtures by pulsed corona discharge

Non-thermal plasma technology has been regarded as a promising alternative technology for NOx removal. The understanding of NO2 reduction characteristics is extremely important since NO2 reduction could lower the total NO oxidation rate in the plasma atmosphere. In this study, NO2 reduction was experimentally investigated using a non-thermal plasma reactor driven by a pulsed power supply for different simulated gas compositions and operating parameters. The NO2 reduction was promoted by increasing the specific energy density (SED), and the highest conversion rates were 33.7%, 42.1% and 25.7% for Ar, N-2/Ar and O-2/Ar, respectively. For a given SED, the NO2 conversion rate had the order N-2/Ar > Ar > O-2/Ar. The highest energy yield of 3.31 g/kWh was obtained in N-2/Ar plasma and decreased with increasing SED; the same trends were also found in the other two gas compositions. The conversion rate decreased with increasing initial NO2 concentration. Furthermore, the presence of N-2 or O-2 led to different reaction pathways for NO2 conversion due to the formation of different dominating reactive radicals. (C) 2014 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.