Hydrophobic Functional Deep Eutectic Solvents Used for Efficient and Reversible Capture of CO₂

Abstract

CO2 emission from flue gas is an important issue threatening human survival. Deep eutectic solvents (DESs), which have many unique properties, have been studied for CO2 capture. However, water can be absorbed by DESs during the absorption of CO2, which may increase the energy cost during the desorption of CO2. In this work, a new kind of hydrophobic functional DES formed by polyamine hydrochloride and thymol was synthesized and used for CO2 capture. It had been found that these DESs could efficiently capture CO2 even at low partial pressures. The CO2 capacity of [TEPA]­Cl-thymol (n [TEPA]Cl/n thymol = 1:3) was high up to 1.355 mol CO2/mol DES at 40 °C and 101.3 kPa. Interestingly, these DESs were still hydrophobic after saturated with CO2. The CO2 absorption capacity increased with a decrease of temperature and an increase of CO2 partial pressure. Regeneration results showed that no obvious loss in the capacity could be found after five absorption/desorption cycles of these DESs. The Fourier transform infrared (FT-IR) spectra indicated that CO2 could interact with amino in the DESs by the formation of carboxylate. Moreover, the equilibrium constant and Henry’s law constant in chemical absorption and physical absorption were studied.

New Solvents for CO2 and H2S Removal from Gaseous Streams

“…A quite limited CO 2 uptake was observed: at 298 K, the CO 2 solubility reaches values up to 0.3 and 0.2 mol CO 2 /mol DES (0.048 and 0.0355 g CO 2 /g DES) at 15 bars with both oleic-capric and lauric-capric fatty acid blends. A similar study was realized by Gu et al (2020) [154], in which a new kind of hydrophobic DES formed by polyamine hydrochloride and thymol (1:3) was synthesized. The CO 2 capacity reaches a value up to 1.355 mol CO 2 /mol DES (0.353 g CO 2 /g DES) at 40 • C and 101.3 kPa; this blend is reported to be able to capture carbon dioxide both physically and chemically.…”

The Influence of Hydrogen Bond Donors on the CO2 Absorption Mechanism by the Bio-Phenol-Based Deep Eutectic Solvents

“…A lot of DESs have been prepared as CO 2 absorbents so far. Among them, amine-based DESs [ 12 , 13 , 14 , 15 , 16 ], anion-functionalized DESs [ 17 , 18 ], and superbase-based DESs [ 19 , 20 , 21 , 22 ] showed attractive CO 2 capacities through the reaction between CO 2 and active sites in the components at ambient pressure, suggesting that adjusting the structures of the components in the DESs can be an effective strategy to meet the particular demands. Moreover, the interactions between CO 2 and the functionalized DESs were also reported in the literatures.…”

Separation of Benzene-Cyclohexane Azeotropes Via Extractive Distillation Using Deep Eutectic Solvents as Entrainers

“…Thus, DESs are also called low transition temperature mixtures (LTTMs) [4,5]. DESs also have been studied in the field of gas-gas/liquid−liquid extraction [6][7][8][9][10][11][12] and extractive distillations [13][14][15][16][17][18][19][20]. Deep eutectic solvents (DESs) as novel entrainers can be used for the separation of azeo-tropic mixture, and have received much attention in recent years [21][22][23].…”