Simultaneous Removal of NO and SO 2 from Flue Gas Using [Bmim] 2 FeCl 4 /Sulfolane Binary Mixtures.

NO and SO ₂ are the major pollutants of coal combustion. As superior absorbents, ionic liquids are environmentally friendly, are reusable, and can clean flue gases, such as CO ₂ , SO ₂ , and NO _x . However, NO and SO ₂ absorption with low concentration in flue gases under normal conditions is rarely studied. In this work, [Bmim] ₂ FeCl ₄ was synthesized and mixed with sulfolane for NO and SO ₂ removal from flue gas. The investigated concentrations of NO and SO ₂ were 1100 and 2500 ppm, respectively, which are close to real fuel gas conditions. Results showed that 30 wt % [Bmim] ₂ FeCl ₄ /sulfolane mixture performed the best absorption behavior. The presence of SO ₂ could promote NO absorption by [Bmim] ₂ FeCl ₄ /sulfolane mixture. The 30 wt % [Bmim] ₂ FeCl ₄ /sulfolane mixture had removal efficiencies of 93.6 and 76.2% for NO and SO ₂ , respectively. This mixture also showed great reusability for NO and SO ₂ after six cycles of absorption. Fourier transform infrared (FTIR) spectrum indicated that SO ₂ and NO removal by [Bmim] ₂ FeCl ₄ /sulfolane binary mixture was due to the chemical reaction between NO and [Bmim] ₂ FeCl ₄ and the physical absorption between SO ₂ and sulfolane.
Competing Interests: The authors declare no competing financial interest.
(© 2020 American Chemical Society.)