Diesel NOx Reduction on Surfaces in Plasma

Abstract

<div class="htmlview paragraph">Recent work has shown that energy efficiencies as well as yields and selectivities of the NO<sub>x</sub> reduction reaction can be enhanced by combining a plasma discharge with select catalysts. While analysis of gas phase species with a chemiluminescent NO<sub>x</sub> meter and mass spectrometer show that significant removal of NO<sub>x</sub> is achieved, high background concentrations of nitrogen preclude the measurement of nitrogen produced from NO<sub>x</sub> reduction. Results presented in this paper show that N<sub>2</sub> from NO<sub>x</sub> reduction can be measured if background N<sub>2</sub> 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 N<sub>2</sub> produced is compared with the amount of NO<sub>x</sub> removed as measured by the chemiluminescent NO<sub>x</sub> meter. The measured nitrogen from NO<sub>x</sub> reduction accounts for at least 40% of the total NO<sub>x</sub> removed for both reactor configurations. FTIR analysis for by-product species including N<sub>2</sub>O, HONO, HNO<sub>3</sub>, NO<sub>2</sub>, and CH<sub>3</sub>ONO<sub>2</sub> does not account for the “missing” NO<sub>x</sub>.</div>