Absorption of SO 2 at high temperatures by ionic liquids and the absorption mechanism

Abstract

The capture of SO 2 at or close to the temperatures of real flue gas is much more attractive in application. In this work, two kinds of ionic liquids (ILs) based on lactate anion were used to absorb SO 2 at high temperatures from 100 to 120°C. The ILs show high absorption capacities of over one mol SO 2 per mol IL at 110°C. The absorption of SO 2 by the ILs based on lactate anion is reversible and the ILs can be reused for the capture of SO 2 at high temperatures with high absorption capacity and thermal stability. Furthermore, the absorption mechanism of SO 2 by the ILs was studied by FT-IR, 1 H NMR and 13 C NMR spectra. It has been found that there are strong chemical interactions between the ILs and SO 2. Also the absorption mechanism is different when there is water present in ILs compared to when there is not.