Using Ionic Liquid Mixtures To Improve the SO2 Absorption Performance in Flue Gas

摘要

The functional ionic liquids (ILs) [NH(2)emim] [OAc] and [NH(2)emim] [BF4] were synthesized for SO2 capture. Although functional ILs have potential advantages in SO2 absorption, the high viscosity of a single IL markedly affects the SO2 absorption separation process. To improve the SO2 absorption performance, [NH(2)emim] [OAc] and [NH(2)emim] [BF4] were mixed with low-viscosity imidazolium-based ILs [bmim][OH]/[bmim][BF4]. When the mole ratio of [NH(2)einim][OAc]/ [bmim][OH] is about 1:1, the binary mixture has the best SO2 absorption capacity. The SO2 absorption performance was investigated in the simulated flue gas, where SO2 partial pressure was about 0.2 kPa. Under the low SO2 partial pressure, the absorption capacity of the [NH(2)emim] [OAc] + [bmim] [OH] mixture was more than 0.7 mol of SO2/mol of IL, which was superior to that of a single IL. The regeneration test of [NH(2)emim] [OAc] + [bmim] [OH] showed that the binary mixture had high reversibility and the SO2 absorption capacity almost kept constant after 12 recycles. The viscosity and density of the IL mixture changed slightly, which only have a 2-3% increase in each cycle.