Synthesis of cyclic sulfites from epoxides and sulfur dioxide with silica-immobilized homogeneous catalysts

Efficient alternating copolymerization of sulfur dioxide with cyclohexene oxide and a mechanistic understanding

This work describes an efficient alternating copolymerization of sulfur dioxide with cyclohexene oxide using salenCr^IIICl as catalyst. The effect of the temperature, time, and type of catalyst on the overall activity and selectivity was investigated.

Highly efficient SO₂ absorption and its subsequent utilization by weak base/polyethylene glycol binary system

A binary system consisting of polyethylene glycol (PEG, proton donor)/PEG-functionalized base with suitable basicity was developed for efficient gas desulfurization (GDS) and can be regarded as an alternative approach to circumvent the energy penalty problem in the GDS process. High capacity for SO(2) capture up to 4.88 mol of SO(2)/mol of base was achieved even under low partial pressure of SO(2). Furthermore, SO(2) desorption runs smoothly under mild conditions (N(2), 25 °C) and no significant drop in SO(2) absorption was observed after five-successive absorption-desorption cycles. On the other hand, the absorbed SO(2) by PEG(150)MeIm/PEG(150), being considered as the activated form of SO(2), can be directly transformed into value-added chemicals under mild conditions, thus eliminating the energy penalty for SO(2) desorption and simultaneously realizing recycle of the absorbents. Thus, this SO(2) capture and utilization (SCU) process offers an alternative way for GDS and potentially enables the SO(2) conversion from flue gas to useful chemicals as a value-added process.

Highly efficient SO2 absorption/activation and subsequent utilization by polyethylene glycol-functionalized Lewis basic ionic liquids

Up to now, flue-gas desulfurization (FGD) is one of the most effective techniques to control SO(2) emission from the combustion of fossil fuels. The conventional technology for FGD poses serious inherent drawbacks such as formation of byproducts and volatilization of solvents. In this work, polyethylene glycol (PEG)-functionalized Lewis basic ionic liquids (ILs) derived from DABCO were proved to be highly efficient absorbents for FGD due to its specific features such as high thermal stability, negligible vapor pressure, high loading capacity. Notably, PEG(150)MeDABCONTf(2) gave an extremely high SO(2) capacity (4.38 mol mol(-1) IL), even under 0.1 bar SO(2) partial pressure (1.01 mol mol(-1) IL), presumably owing to the strong SO(2)-philic characterization of the PEG chain. Furthermore, the absorbed SO(2) could be easy to release by just bubbling N(2) at room temperature, greatly reducing energy requirement for SO(2) desorption. In addition, SO(2)/CO(2) selectivity (110) of PEG(150)MeDABCONTf(2) is two times larger than the non-functionalized imidazolium IL (45). On the other hand, through activation of SO(2) with the tertiary nitrogen in the cation, Lewis basic ILs such as PEG(150)MeDABCOBr proved to be efficient catalysts for the conversion of SO(2) to some value-added chemicals such as cyclic sulfites without utilization of any organic solvent or additive. Thus, this protocol would pave the way for the development of technological innovation towards efficient and low energy demanded practical process for SO(2) absorption and subsequent transformation.