Diesel NOx Reduction on Surfaces in Plasma 982511

Recent work has shown that energy efficiencies as well as yields and selectivities of the NO_x reduction reaction can be enhanced by combining a plasma discharge with select catalysts. While analysis of gas phase species with a chemiluminescent NO_x meter and mass spectrometer show that significant removal of NO_x is achieved, high background concentrations of nitrogen preclude the measurement of nitrogen produced from NO_x reduction. Results presented in this paper show that N₂ from NO_x reduction can be measured if background N₂ is replaced with helium. Nitrogen production results are presented for a catalyst system where the catalyst is in the plasma region and where the catalyst is downstream from the plasma. The amount of N₂ produced is compared with the amount of NO_x removed as measured by the chemiluminescent NO_x meter. The measured nitrogen from NO_x reduction accounts for at least 40% of the total NO_x removed for both reactor configurations. FTIR analysis for by-product species including N₂O, HONO, HNO₃, NO₂, and CH₃ONO₂ does not account for the “missing” NO_x.