NOx remediation in oxygen-rich exhaust gas using atmospheric pressure non-thermal plasma generated by a pulsed nanosecond dielectric barrier discharge

Abstract

It is clearly seen that the application of non-thermal plasmas (NTP) to remove NOx from gas mixture containing a large amount of oxygen (O2) is dominated by NO to NO2 oxidation. Experiments have been conducted using a NTP generated by a nanosecond pulsed dielectric barrier discharge in synthetic exhaust gas, prepared from N2, O2, NO, H2O, and C3H6, over a large range of gas temperature (20-300\r{}C). Results show that the NOx removal rate significantly increased with increasing specific energy deposition. For example, at a temperature of 100\r{}C and an energy deposition of 27 J l-1, 92% of the NO molecules have been removed. The W values for NO is dramatically reduced to values scaling from ≈15 eV at 27 J l-1 down to ≈4 eV at 7 J l-1. NOx removal efficiency around 43% was obtained at a temperature of 260\r{}C and a space velocity of 60 000 h-1 for a specific input energy of 27 J l-1. W values for NOx were less than ≈30 eV. Such treatments in exhaust gas with and without the presence of water vapour induced reactions leading to the production of a large variety of by-products such as acetaldehyde, propylene oxide, formic acid, methyl nitrate, and nitromethane.