Oxidation and reduction processes during NOx removal with corona-induced nonthermal plasma

In this paper, the NO-to-NO2 conversion in various gaseous mixtures is expe rimentally investigated. Streamer coronas are produced with a dc-superimpos ed high-frequency ac power supply (10-60 kHz). According to NOx removal exp eriments in N-2 + NOx and N-2 + O-2 + NOx gaseous mixtures, it is supposed that the reverse reaction NO2 + O --> NO + O-2 may not only limit NO(2)Z pr oduction in N-2 + NOx mixtures, but also increase the energy cost for NO re moval. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N + NO --> N-2 + O, i nduce negligible NO removal provided the O-2 concentration is larger than 3 .6%. With adding H2O into the reactor, the produced NO2 per unit removed NO can be significantly reduced due to NO2 oxidation. NH3 injection could als o significantly decrease the produced NO2 via NH and NH2- related reduction reactions Almost 100% of NO2 can be removed in gaseous mixtures of N-2 + O -2 + H2O + NO2 with negligible NO production.