Effect of Gas Components and Particulate Matter on the Conversion of Nitric Oxide by Dielectric Barrier Discharge

Abstract

The conversion of nitric oxide by dielectric barrier discharge (DBD) in different reaction gases (O2, H2O, Ar, and N2) was studied. In the N2/O2 system, N and O could react to form NO; consecutively, extra O would oxidize NO to form NO2. Increase of oxygen content would promote the generation of NO, and the highest concentration of NO2 could be obtained with different oxygen contents at specific energy inputs (SEIs) of 1200 or 1440 J/L. In the N2/O2/NO system, the oxidation and reduction of NO took place simultaneously to form NO2 and N2, and NO was mainly removed by reduction when the oxygen content was lower than 6 vol %. In comparison, in the Ar/O2/NO system, NO was mainly oxidized to NO2. However, when the oxygen content exceeded 12 vol %, the increase of the SEI between 960 and 1440 J/L will increase the temperature of the DBD reactor, resulting in the restrain of the NO oxidation rate. In the SO2/N2/O2/NO system, SO2 could be oxidized by O radicals in the discharge region, leading to the restrain of NOx generation. In the H2O/N2/O2/NO system, H2O could promote the oxidation of NO so that NO conversion could reach 100% at 18 vol % O2 content. In the system of particulate matter/N2/O2/NO, particles would change the parameters in the discharge region and promote the production of N and O radicals, leading to the concentrations of NO2 and NOx being higher than those in the N2/O2/NO system. When the oxygen content was lower than 6 vol %, the conversion of NO reached 100% at 960 J/L. N2O formed in all systems as a byproduct of NO conversion by DBD. With the increase of the SEI, part of N was oxidized, resulting in the increase of NOx in all the systems containing N2.