Choline chloride/levulinic acid-based deep eutectic solvents : characterisation and carbon capture performance

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Aboshatta, Mohaned Ahmed Elbasheer and Magueijo, V. (2022) Choline chloride/levulinic acid-based deep eutectic solvents : characterisation and carbon capture performance. In: ChemEngDayUK 2022, 2022-04-07 - 2022-04-08, University College London.

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Abstract

The concentration of CO2 in the atmosphere has increased dramatically over the last six decades, reaching a value of 419 ppm in February 2022. Amine absorption is currently the most used and established method for CO2 capture; however, it has environmental drawbacks and is energy intensive. Deep eutectic solvents (DESs) are alternatives to substitute conventional amines for CO2 capture. DESs are greener and more benign solvents for CO2 capture than ionic liquids due to their biodegradability, nontoxicity and low prices. Choline chloride/levulinic acid-based deep eutectic solvents (ChCl:LvAc DESs) were studied in this work. DESs were prepared with different ChCl:LvAc molar ratios and with different water contents. The DESs were characterised in terms of density, viscosity, thermal stability and FTIR spectrophotometry. Furthermore, the corrosivity of ChCl:LvAc DESs was investigated experimentally at different conditions (stagnant versus stirred system and in the presence and absence of CO2). The results clearly show that these DESs are much less corrosive than MEA solutions, with the maximum corrosion penetration rate (CPR) observed being 92% smaller than the one exhibited by a MEA 30 wt.% aqueous solution. The CO2 absorption capacity of choline chloride/levulinic acid-based DESs was measured at different temperatures, pressures and stirring speeds using the vapour-liquid equilibrium rig. DES regeneration (CO2 desorption) was performed using the heat treatment method. FTIR was employed to verify the absorption and desorption of CO2 at different temperatures. Thermodynamic properties for CO2 absorption were calculated from the experimental data. Henry’s constants for the dissolution of CO2 in the DESs were calculated with values ranging between 4.6 to 14.2 MPa under the studied conditions. The statistical analysis of the experimental results showed that the CO2 absorption capacity of the DESs is strongly affected by the operating pressure and stirring speed, moderately affected by the temperature and negligibly affected by the HBA/HBD molar ratio and water content. DES regeneration was performed at different temperatures with the optimal regeneration temperature of these compositions estimated as being 80 ºC. In this work, DESs exhibited good recyclability as samples lost less than 0.5% of their initial weight after five consecutive cycles of CO2 absorption at 25 ºC and desorption at 80 ºC. Finally, ChCl:LvAc DESs showed high selectivity towards CO2 over N2 with selectivity values up to 5.63 obtained for equimolar CO2/N2 gas mixtures at 25 ºC.

ORCID iDs

Aboshatta, Mohaned Ahmed Elbasheer and Magueijo, V. ORCID logoORCID: https://orcid.org/0000-0002-8029-1367;
CORE (COnnecting REpositories)