Reducing nitric oxide into nitrogen via a radio-frequency discharge.

NO/N(2)/O(2)/H(2)O mixtures are usually converted into HNO(3) and/or NO(2) using different discharge approaches. In this study, a radio-frequency discharge was successfully used to reduce NO mainly into N(2) at a low pressure (4kPa). The influences of experimental parameters, including carrier gas, inlet concentration of NO, O(2), steam, and applied power, are discussed. At least 95.7% of the total N atoms converted from NO into N(2). Other traces of byproducts were N(2)O and HNO(2), but neither HNO(3) nor NO(2) were detected. In addition, conversion of NO apparently increased with elevated applied power or decreased inlet concentration of O(2), reaching 92.8% and 74.2% for the NO/N(2)/O(2) (2%) and NO/N(2)/O(2) (6%)/H(2)O (10%) mixtures, respectively, at 120W. In addition, from the optical emission spectra, a large amount of N(2) (first positive band and second positive band) and NO (gamma system) were observed, and the important reactions for NO removal and N(2) formation are proposed.