No abstract

Emission of SO2 in flue gas from the combustion of fossil fuels leads to severe environmental problems. Exploration of green and efficient methods to capture SO2 is an interesting topic, especially at lower SO2 partial pressures. In this work, ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Et2 NEMim][Tf2 N]) and 1-(2-diethylaminoethyl)-3-methylimidazolium tetrazolate ([Et2 NEMim][Tetz]) were synthesized. The performances of the two ILs to capture SO2 were studied under different conditions. It was demonstrated that the ILs were very efficient for SO2 absorption. The [Et2 NEMim][Tetz] IL designed in this work could absorb 0.47 g(SO2)g(IL)(-1) at 0.0101 MPa SO2 partial pressure, which is the highest capacity reported to date under the same conditions. The main reason for the large capacity was that both the cation and the anion could capture SO2 chemically. In addition, the IL could easily be regenerated, and the very high absorption capacity and rapid absorption/desorption rates were not changed over five repeated cycles.

In this work, we investigated SO2 absorption by deep eutectic solvents (DESs) formed by 1-ethyl-3-methylimidazolium chloride (EmimCl) and ethylene glycol (EG) under different conditions. DESs with different molar ratios of EmimCl and EG (from 2:1 to 1:2) were prepared. The results showed that all the EmimCl-EG solvents were very efficient for SO2 capture. It was demonstrated that the SO2 solubility increased with increasing concentrations of EmimCl in DESs. The effects of temperature and SO2 partial pressure were also investigated. The Emim-EG (2:1) solvent could absorb 1.15 (53 wt %) g SO2/g solvent at 20 °C and 1.0 atm, a much higher capacity than that of other DESs reported to date under the same conditions. Moreover, the SO2 desorption temperature of the solvents could be tuned by changing the composition of the solvents, and all the EmimCl-EG solvents showed excellent reversibility. Nuclear magnetic resonance and Fourier transform infrared spectra showed the interactions of the solvents and SO2.

Azolide-based deep eutectic solvents exhibit a high CO2 absorption capacity by forming carbonate species.

Deep eutectic solvents (DESs) based on 1-ethyl-3-methylimidazolium chloride (EmimCl) and triethylene glycol (TEG) with different molar ratios (from 6 : 1 to 1 : 1) were prepared. FTIR and theoretical calculation indicated that the C2-H on the imidazolium ring form hydrogen bonds with the hydroxyl group rather than the ether O atom of the TEG. The EmimCl-TEG DESs can efficiently capture SO2; in particular, EmimCl-TEG (6 : 1) can capture 0.54 g SO2 per gram of solvent at 0.10 atm and 20 °C, the highest absorption amount for DESs under the same conditions. Theoretical calculation showed that the high SO2 absorption capacity was mainly due to the strong charge-transfer interaction between SO2 and the anion Cl-. Moreover, SO2 desorption in the DESs can be controlled by tuning the interaction between EmimCl and TEG, and the DESs can be cycled many times.

We discovered that the synthesis of quinazoline-2,4(1H,3H)diones from CO 2 and 2-aminobenzonitriles could proceed efficiently in water without any catalyst and excellent yields were obtained, while the reaction did not occur in organic solvents.This green and simple route to synthesize quinazoline-2,4(1H,3H)diones has great potential for application.Scheme 1 Conversion of CO 2 and 2-aminobenzonitrile to quinazoline-2,4-(1H,3H)-dione.

No abstract

We report that deep eutectic solvents can be formed by biobased aprotic organic compound succinonitrile (SN) functionalized as the hydrogen bond donor with solid ionic liquid 1-ethyl-3-methylimidazolium chloride ([Emim]­[Cl]) or 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim]­[PF6]). The results suggested the formation of intermolecular hydrogen bonds between the anions of imidazolium salts and the C–H hydrogen of SN. Moreover, the deep eutectic solvent [Emim]­[Cl]-SN(1:1) exhibited an attractive SO2 absorption capacity (0.120 g SO2/g solvent) at low SO2 partial pressure (2000 ppm), which was more than two times the amount captured by [Emim]­[Cl]-ethylene glycol (EG)(1:1) (0.047 g SO2/g solvent) at the same conditions, although the concentration of [Emim]­[Cl] in [Emim]­[Cl]-SN(1:1) (64.7 wt %) was lower than that in [Emim]­[Cl]-EG(1:1) (70.3 wt %). The high SO2 absorption capacity of [Emim]­[Cl]-SN(1:1) was mainly because of the strong charge-transfer interaction between S of SO2 and Cl–, which was investigated by using Fourier transform infrared spectroscopy and theoretical calculations.