Ind. Eng. Chem. Res. 2005, 44, 3925-3934
3925
Effect of CO2 on Nonthermal-Plasma Reactions of Nitrogen Oxides in N2. 1. PPM-Level Concentrations Gui-Bing Zhao, Xudong Hu, Morris D. Argyle, and Maciej Radosz* Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, Wyoming 82071-3295
PPM-level concentrations of CO2 are added to NO/N2 mixtures to determine the effect of CO2 on plasma generation and to investigate the mechanism of CO2 reactions. Addition of 599.9 ppm CO2 does not affect the electric discharge in NOx in N2 nonthermal plasma. However, CO2 slightly dissociates, with CO2 conversion reaching a maximum of about 5.5% at the power input at which NO conversion ceases. NO(A), the first-excited electronic state of NO, is detected by coronainduced optical emission and is found to contribute to CO2 dissociation. A kinetic model including 38 reactions is required to adequately model decomposition of NOx and CO2 in the presence of CO2. About 18% of the NO(A) that is formed reacts with CO2 to form NO, CO, and O. Introduction The removal of nitrogen oxides (NOx) from combustion exhaust streams has become an important international technology issue because of the key role NOx play in many global environmental problems, such as acid rain, photochemical smog formation, and the greenhouse effect. Political pressure is increasing for the adoption of increasingly stringent emission standards. Among the emerging technologies for NOx decomposition, nonthermal plasma is one of the most promising. A pulsed corona discharge reactor (PCDR) is a nonthermal plasma reactor characterized by low gas temperature and high electron temperature, achieved by producing highenergy electrons in the gas while leaving the bulk temperature of the gas unchanged. PCDR utilizes a high-voltage short-duration (
