Novel Deep Eutectic Solvents for Highly Efficient and Reversible Absorption of SO₂ by Preorganization Strategy

Abstract

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 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. On the basis of the spectroscopic investigations and quantum chemical calculations, the reversible absorption mechanism was illustrated, in which the synergism of hydrogen bond donors and hydrogen bond acceptors facilitated the SO2 capture, and the charge-transfer and hydrogen bond interactions between DESs and SO2 could be effectively tuned by the preorganization strategy, thus endowing DESs with excellent desorption performance.

Effective absorption of SO2 by imidazole‐based protic ionic liquids with multiple active sites: Thermodynamic and mechanical studies

“…Comparing the FTIR spectra before and after absorption of SO 2 , new absorption peaks at 542, 645, 947, 1046, 1283, and 1390 cm −1 for both [TMEA][Im] and TMEA were found. Among these new peaks at 1390, 1046, and 542 cm −1 belong to the symmetric stretching vibration, symmetric stretching vibration, and bending vibration of S═O, 23,56,57 respectively. This phenomenon is mainly attributed to the physical interaction between ether oxygen atom and SO 2 54 .…”

Capture of Acidic Gases from Flue Gas by Deep Eutectic Solvents

“…With the optimal molar ratio, the absorption capacities of EmimCl:EG DES (1:2) and EmimCl:TEG DES (1:4) were 1.03 and 1.20 g SO 2 /g DES, respectively, at 293. 15 The effect of HBAs and HBDs in DESs was further investigated by Tantai et al [44]. As shown in Figure 2, the gravimetric SO 2 absorption capacities of ethylenurea (EU) and 1,3dimethylurea (DMU)-based DESs with various HBAs displayed the same trend: EmimCl > BmimCl > BmimBr > TBAC~P 4444 Cl.…”

“…Moreover, it was also noted that when the SO 2 partial pressure decreased to 2 kPa at 298. 15 [44]. Copyright (2019) American Chemical Society).…”

Investigation of Highly Efficient and Reversible Absorption of SO2 Using Ternary Functional Deep Eutectic Solvents

“…The preparation of all studied DESs in this work was similar to the reported method . All DESs with certain molar ratios were synthesized through simply mixing BmimCl (HBA), EU (primary HBD), and azole derivatives (secondary HBDs) together with stirring and heating under a nitrogen atmosphere, denoted as EU/azole derivatives/BmimCl ( a / b / c ), where a / b / c is the molar ratio of HBDs and HBA.…”

“…According to the previous reports, , though it has been proved that adjusting the HBD/HBA proportion and decreasing the basicity of HBDs or HBAs could significantly tune the interaction between DESs and SO 2 , it could also inevitably reduce the SO 2 absorption capacity. Previously, we reported that the DESs with the preorganized multi-imide ethylene urea (EU) such as HBD presented superior SO 2 absorption capacity, improved desorption performance, and outstanding physical properties . However, on the basis of the spectroscopic investigations and quantum chemical calculations, it could be concluded that the EU-based DESs interacted with SO 2 only through physical interactions, which resulted in the inferior SO 2 absorption capacity at low concentration.…”