High-Efficiency Removal of NOx Using a Combined Adsorption-Discharge Plasma Catalytic Process

A combined adsorption-discharge plasma catalytic process was used for the removal of NOx using zeolites as catalysts without external heating. It was found that the types of plasma carrier gases exert great effect on the conversion of adsorbed NOx. The conversion of adsorbed NOx is much lower in N-2 plasma than in Ar plasma, which is attributed to the reverse reaction, NOx formation reaction. The momentary increase of oxygen species derived from the decomposition of adsorbed NOx is considered to be the main cause as their collisions with nitrogen species can generate NOx again. Thus, solid carbon was added to the catalyst to act as a scavenger for active oxygen species to improve the conversion of adsorbed NOx in N-2 plasma. A NOx removal rate of 97.8% was obtained on 8.5wt.% carbon mixed H-ZSM-5 at an energy efficiency of 0.758 mmol NOx/W.h.