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C. Froschauer, H.K. Weber, H. Sixta, G. Laus, B. Lendl, H. Schottenberger:
"No Matter of Course: Ionic Liquids as SO2-Selective Gas Absorbers";
Lenzinger Berichte, 91 (2013), 30 - 43.

Under the perspective of potential tech. off-gas recovery and recycling, a series of ionic liqs. (ILs) was compared and screened for their applicability as environmentally benign solvents for absorbing sulfur dioxide (SO2). New molten salts based on imidazolium cations, combined with the 2-formylbenzene-sulfonate anion were developed and identified as unique, regenerative scrubbing agents for SO2. In particular, the room temp. ILs 1-butyl-3-methylimidazolium 2-formylbenzenesulfonate (BMIM OFBS) and 1-allyl-3-methylimidazolium 2-formylbenzenesulfonate (AMIM OFBS) were compared to already known SO2-absorbing systems. In their entirety of required properties for absorb-ing and desorbing SO2, the newly introduced systems are superior to all IL-based scrubbing media described so far: These innovative task-specific ILs exhibit low hygroscopicity, good recyclability and, most notably, a remarkable selectivity between the sour gases SO2 and CO2, even in the state of ambient moisture satn. As such, the compds. are providing a high application potential for pressure or temp. swing absorption cycles. The presented primary results substantiate the advantage of the sheer no. of compositional possibilities in developing ionic liqs. for special purposes.