Novel deep eutectic solvents for highly efficient and reversible absorption of SO2 by preorganization strategy

Deep eutectic solvents (DESs) have emerged as promising substitutes for SO2 capture. In this work, an effective preorganization strategy was implemented to design DESs, aiming at improving the SO2 desorption property while ensuring the SO2 absorption capacity in DESs. Several novel DESs with the preorganized multi-imides as hydrogen bond donors were synthesized and evaluated for SO2 capture. The results showed that the studied DESs exhibited high SO2 absorption capacities. In particular, the ethylenurea (EU)/1-butyl-3-methylimidazolium chloride (BmimCl) (1:2) could achieve up to 1.18 and 0.25 gSO2/gDESs at 293.15 K under 1 atm and 0.02 atm, respectively. Moreover, the DESs absorbent could be regenerated easily under mild conditions and the absorption capacity remained almost unchanged after several consecutive absorption-desorption cycles. Based on the spectroscopic investigations and quantum chemical calculations, the reversible absorption mechanism was illustrated, in which the synergism of hydrogen bon...