Experimental and Kinetics Modelling Studies of NOx, N2O, and O3 in Plasma Discharges

Abstract

Recently, it has been a rise in the plasma application in the NOx remediation processes. This promising technology is in its infancy yet, and there are several knowledge gaps in the fundamental of NOx chemical reactions in the plasma discharge. Plasma technology has also been utilized for the N2O abatement; however, its detailed chemical kinetics is not well studied. In contrast to the new emerged plasma applications in the NOx and N2O removal, ozone has been generated by plasma since 19th century. However, the efficiency of ozone generation has remained low (<30%), indicating the need of research to improve it. The objective of this thesis is to achieve insight into the fundamental chemical kinetics of NOx, N2O, and O3 in the plasma discharge. This thesis presents the results of experimental and gas phase chemical kinetics modelling studies of NOx and N2O removal, and also ozone generation under different studied condition. NO is fully removed in the N2 discharge into N2 and O2 with the selectivity of >99.4 %. Addition of H2O to the NO/N2 discharge results in decrease of NO conversion. Similar to the effect of H2O, addition of oxygen also results in decrease of NO removal efficiency. In the dielectric barrier O2 discharge, N2O is mainly converted through the reaction with O(1D) with 67% selectivity to NOx. In contrast to the traditional catalytic N2O removal, in the presence of ozone, N2O reacts with the adsorbed atomic oxygen released from ozone dissociation and form N2 and NO. In the gliding arc O2 discharge, N2O is mainly removed through the reaction with O (N2O+O=N2+O2). The addition of H2O to the feed results in decrease of N2O conversion. In the ozone formation process, with addition of argon to the pure oxygen, the concentration of formed O3 decreases while the O3/O2 ratio increases. In contrast to the effect of argon, addition of nitrogen up to 2% results in increase of both O3/O2 ratio and concentration of formed ozone.