Tuning the basicity of cyano-containing ionic liquids to improve SO2 capture through cyano-sulfur interactions.

A new approach has been developed to improve SO2 sorption by cyano-containing ionic liquids (ILs) through tuning the basicity of ILs and cyano-sulfur interaction. Several kinds of cyano-containing ILs with different basicity were designed, prepared, and used for SO2 capture. The interaction between these cyano-containing ILs and SO2 was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO2 capacity originate from the basicity of the ILs and enhanced cyano-sulfur interaction. Furthermore, the captured SO2 was easy to release by heating or bubbling N2 through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO2 capture.