Experimental study on reaction characteristics of NO in (NH4)2SO3 solution

Abstract The effects of various factors on the NO removal activity in the (NH 4 ) 2 SO 3 solution were investigated to explore more details and characteristics of the related reactions using full infrared sensor flue gas analyzer (FISFGA). It was found that the conversion yield of NO (9.0%–29.0%) was obviously improved with the increase of gas–liquid contact area, NO residence time and (NH 4 ) 2 SO 3 concentration as well as the adding of CuSO 4 . However, it was mainly limited by gas–liquid mass transfer rate and slightly inhibited by the gas velocity. Moreover, the FISFGA analysis revealed that two nitric oxide (NO) conversion route with different reduction product of N 2 O and N 2 existed simultaneously upon the existence form of SO 3 2− . It was confirmed by the calculations and the experiments of pH factor that the NO reduction steps were based on the following equation: (1) NO + HSO 3 −  ⇋ N 2 O + SO 4 2−  + H + ; (2) NO + SO 3 2−  ⇋ N 2  + SO 4 2− . In this system, Eq. (1) with N 2 O product was the major pathway, but the ratio of Eqs. (2) to (1) was intensified in the presence of CuSO 4 . It is believed that the suitable additives could promote the NO reduction to N 2 furtherly.