Removal of NO sub(x) from exhaust gas by N sub(2) arc plasma injection

The purpose of this study was to develop a method for removing the NO sub(x) contained in combustion exhaust gases by nitrogen plasma injection. Simulated exhaust gas (N sub(2) + O sub(2) + CO sub(2) + NO) was mixed with nitrogen atoms produced by N sub(2) plasma, and the Zeldovich reactions for excited N atoms with NO and O sub(2) took place. The effects of O sub(2), CO sub(2), and H sub(2)O on the reduction of NO sub(x) were studied experimentally. An NO sub(x) removal ratio of 40-50% is observed for O sub(2) concentrations of 3-5% and plasma power of 600 W; CO concentration generated in the exhaust gas was > 300 ppm. The NO sub(x) removal ratio was reduced considerably by the addition of H sub(2)O and was highest for reaction temperatures below 500 K. When argon gas was added to improve the N sub(2) plasma stability, the NO sub(x) removal became possible under low electric power conditions of about 500 W.