NH₃-induced removal of NO_x from a flue gas stream by silent discharge ozone generation in a double reactor system

NO_x, a generic term for the nitrogen oxides generated from combustion in the presence of nitrogen, is a serious threat to human health. This study examined the removal of NO_x using ammonia (NH₃) and ozone produced using a silent discharge method. The effects of temperature and residence time on NO_x removal with NH₃ injection in a double reactor system were investigated. An increase in temperature resulted in higher levels of O₃ decomposition, whereas the maximum particle formation in the form of ammonium nitrate (NH₄NO₃) was achieved when both reactors were kept at 180 ^oC. NH₃ and O₃ injection in large quantities and NO in smaller amounts with a residence time of 10.2 s resulted in the maximum particulate formation. In contrast, when an excess of NH₃ was supplied, it resulted in N₂O formation due to the formation of NH₂ radicals generated from a reaction of NO₂ with NH₃. In addition, 100% NO removal was achieved regardless of the residence time. Kinetic simulations indicated the possibility of moisture being the limiting reactant.