Oxidation of NO to NO

To reduce nitrogen oxides emissions (NOx) from flue gas, selective catalytic reduction (SCR) or adsorption using various solution are efficient methods. However, nitric oxide (NO) needs to be oxidised into nitrogen dioxide (NO2) to enhance NOx removal performance. This paper presents the effects of operating parameter of a dielectric barrier discharge (DBD) reactor on ozone (O3) generation which ozone was utilised to oxidise NO into NO2 in the real flue gas from diesel oil burner. A cylindrical DBD configuration with 1.5 mm electrode gap and effective discharge volume ranged from 13.8 cm3 were chosen to produce O3-rich air for oxidising NO. Using concentrated O2 instead of air as O3 source could enhance O3 formation (8.57 g/kWh vs. 44.08 g/kWh). NO conversion to NO2 by O3 was strongly dependent on O3/NO ratio. Additionally, thermal O3 decomposition by heat energy in flue gas also substantially reduced O3 which must be compensated by using excess O3/NO ratio. At flue gas temperature of 407°C, O3/NO ratio of 6.37 was required to complete oxidise NO into NO2. The optimal NO conversion efficiency of 2.93 g/kWh was realised at flue gas resident time of 313 ms and flue gas temperature of 483°C.