Carbon dioxide capture by new DBU‐based DES: The relationship between ionicity and absorptive capacity

Abstract

1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU)/imine, DBU/imide DESs were designed and synthesized as CO2 trapping agents. Toward this end, the optimal absorption temperature and the maximum absorption capacity were determined. It was found that ionicity is a key factor to affect the absorption capacity of CO2. Combined with the ionicity calculation, a new CO2 capture mechanism has been proposed. HBD in DES can be divided into two parts. One can undergo proton transfer, obeying anion 2:1 absorption, whereas the other, without proton transfer, is amine 1:1 absorption. The degree of proton transfer in DES determines the ionicity and affects the absorption performance. The DFT calculation results confirmed this mechanism by micro perspective. DBU/2‐Pyrrolidinone and DBU/Oxazolidinone were proved to be good CO2 trapping agents with high absorption capacity, being 1.064 mol CO2/mol DES and 0.827 mol CO2/mol DES, respectively, and excellent recyclability when the mole ratio of HBA:HBD is 2:1.

Reviewing and screening ionic liquids and deep eutectic solvents for effective CO2 capture

“…Nine studies have been focused on chemical-based DESs since 2021, as summarized in Table 4 . Among them, three DESs are newly synthesized ( Fu et al, 2021a ; Ahmad et al, 2021 ; Qian et al, 2022 ), while others are the previously synthesized ones for various purposes, including the discussion about the water content ( Liu et al, 2022 ) and estimating the effects of HBA:HBD molar ration, type of anion, and the alkyl chain ( Cichowska-Kopczyńska et al, 2021 ).…”

Thermodynamic and molecular insights into natural gas dehydration using choline chloride‐based deep eutectic solvents

“…[39][40][41] All the geometries were preoptimized at B3LYP/6-31G (d, p) theoretical level, and then fully optimized at B3LYP/6-311+G (2d, 2p) theoretical level. 42 The frequency calculation was also performed to confirm the true minimum.…”

“…A series of complexes of ChCl, Urea, EG, TEG, H 2 O, and CH 4 were optimized using Gaussian 09 software package with the DFT‐D3 dispersion corrections to obtain the geometric configuration at the lowest energy state 39–41 . All the geometries were preoptimized at B3LYP/6‐31G (d, p) theoretical level, and then fully optimized at B3LYP/6‐311+G (2d, 2p) theoretical level 42 . The frequency calculation was also performed to confirm the true minimum.…”

Deep eutectic solvents for efficient capture of cyclohexane in volatile organic compounds: Thermodynamic and molecular mechanism

“…53 All the geometries were pre-optimized at the B3LYP / 6-31G (d, p) theoretical level, and then fully optimized at the B3LYP/6-311 + G (2d, 2p) theoretical level. 54,55 A frequency calculation was also performed to confirm the true minimum. For the Reline + cyclohexane and Ethaline + cyclohexane systems, geometric structures with different combination modes were optimized to determine the most stable structures.…”

“…All the geometries were optimized by Gaussian 09 with the DFT‐D3 dispersion corrections 53 . All the geometries were pre‐optimized at the B3LYP / 6‐31G (d, p) theoretical level, and then fully optimized at the B3LYP/6‐311 + G (2d, 2p) theoretical level 54,55 . A frequency calculation was also performed to confirm the true minimum.…”