NO/NO_x removal with C₂H₂ as additive via dielectric barrier discharges

Effective reduction and removal of NO_x from gas streams by dielectric barrier discharge (DBD) was studied. A laboratory-scale experimental system was designed and constructed to evaluate the removal efficiency of NO and NO_x. Particularly, C₂H₂ was added as a reducing agent in the DeNO_x plasma process via DBD. Experimental results indicated that the removal efficiency of NO/NO_x increased with increasing applied voltage, gas temperature, and H₂O_(g) content. As the oxygen content in the gas stream is increased, more CH_i radicals will be further oxidized to CO₂, thus reducing the removal efficiency of NO_x. When sufficient C₂H₂ was added to the DBD process, as high as 91.2% of NO and 68.2% of NO_x were removed at 140°C for the gas stream containing 500 ppm NO, 1,500 ppm C₂H₂, 3.2% H₂O_(g), and 5% O₂, with N₂ as the carrier gas. In addition to N₂ and H₂O, the major products found in this process included NO₂, N₂O, HNO₃, CO₂, CO, and HCOOH, depending on H₂O(g) and O₂ contents of the gas stream.