Effects of CH₄ and CO on the reduction of nitric oxide to nitrogen in a discharge reactor

Additives are often added to enhance the efficiency of NO removal. This study uses a radio frequency (rf) discharge to consider the effect of added CH₄ and CO to simulated NO/N₂/O₂/H₂O mixtures on the elevation of NO conversion and the reduction of NO into N₂. The enhancement levels of NO conversion when using various additives were found to be in this order: +CH₄ > CO > no additive. NO conversion reached 99.3%, 86.2%, and 77.6% when adding CH₄, CO, and without additive, respectively, at inlet additive/NO molar ratio (R) = 5 and at 120 W. Moreover, the fraction of total N atoms converted from NO into N₂ (F_N2) was very high, reaching 99.4% and 99.5% when adding CH₄ and CO, respectively, at R = 1 and at 120 W. The better operating conditions are using CH₄ as the additive at R ≥ 1 and a power of >60 W to reach a higher NO conversion with a higher F_N2. How ever, it should be noted that this rf plasma approach is not practical at this stage because of its relative low pressure.