Mechanism and Kinetics of CO₂ Absorption into an Aqueous Solution of a Triamino-Functionalized Ionic Liquid

Abstract

A novel ionic liquid (1-aminoethyl-3-methylimidazolium lysinate, [C 2 NH 2 MIm][Lys]) functionalized with three amino groups had been developed for carbon dioxide (CO 2 ) capture in this work. The CO 2 absorption loading of [C 2 NH 2 MIm][Lys] solution was found to be 1.59 mol CO 2 /mol IL with a concentration of 0.5 mol/L at 313.15 K, which was much higher than that of the most existing dual functionalized ILs. Besides, [C 2 NH 2 MIm][Lys] also owned a good regenerability even after 6 regeneration cycles. According to the results of 13 C nuclear magnetic resonance ( 13 C NMR), CO 2 absorption into [C 2 NH 2 MIm][Lys] solution could be divided into two stages, which began with the formation of carbamate, and followed by the hydration of CO 2 to form carbonate/bicarbonate. Meanwhile, the desorption of the saturated [C 2 NH 2 MIm][Lys] was proven to be a reverse process of the adsorption. Based on the mechanism results, the kinetics of CO 2 capture into [C 2 NH 2 MIm][Lys] solution was investigated by using a double stirred-cell absorber at temperatures ranging from 303 to 333 K. Under the pseudofirst-order regime, the overall reaction rate constants (k ov ) and the forward second-order rate constants (k 2 ) under different concentrations and temperature were obtained, which were both increased considerably as temperature increased. Moreover, the values of enhancement factor (E) were linear with C RNH2 and temperature. The Arrhenius equation of CO 2 absorption was also estimated, and the activation energy was calculated to be 25.5 kJ•mol −1 .

Highly Efficient Absorption of CO2 by Protic Ionic Liquids-Amine Blends at High Temperatures

“…Concretely, new peaks at 1384 and 1044 cm –1 can be attributed to the C–O stretching vibration in carbamate. 41 The peaks at 1178 and 1429 cm –1 can be attributed to the deformation vibration of C–N and −NH 3 + , 42 , 43 respectively. The new peak at 1623 cm –1 is due to the stretching vibration of the C=O bond in the formation of carbamate after the absorption of CO 2 , and the results suggested that carbamate is formed between the basic nitrogen atom of DMAPA and CO 2 .…”

Novel biphasic amino-functionalized ionic liquid solvent for CO2 capture: kinetics and regeneration heat duty

“…The gas-and liquid-phase mass transfer coefficients (k L ) and (k G ) were measured (Zhou et al 2017b), which are presented in the supporting information (Table S2). The CO 2 mass transfer rate could be simplified as follows:…”

CO2 removal from anaesthesia circuits using gas-ionic liquid membrane contactors

“…For these reasons, cholinium-based ILs combined with amino acid anions are emerging as alternative absorption media for CO 2 capture. Additionally, the strategy of using aqueous solutions of functionalised ILs along with biocompatible and biodegradable compounds is gaining projection in the CO 2 capture field, due to all the well-known environmental impact problems.Many authors have investigated CO 2 absorption in IL solutions with increased content of functional amino groups with promising results[133,144,[149][150][151]. Zhou et al[149] developed a novel triamino-functionalized IL and measured the CO 2 absorption capacity in a 0.5 M IL aqueous solution, reporting a very reasonable loading value of 1.59 moles of CO 2 per mole of IL.Yuan et al[144] investigated CO 2 absorption in aqueous solutions with 5-30 wt% of three cholinium-based amino acid ILs.…”

“…Additionally, the strategy of using aqueous solutions of functionalised ILs along with biocompatible and biodegradable compounds is gaining projection in the CO 2 capture field, due to all the well-known environmental impact problems.Many authors have investigated CO 2 absorption in IL solutions with increased content of functional amino groups with promising results[133,144,[149][150][151]. Zhou et al[149] developed a novel triamino-functionalized IL and measured the CO 2 absorption capacity in a 0.5 M IL aqueous solution, reporting a very reasonable loading value of 1.59 moles of CO 2 per mole of IL.Yuan et al[144] investigated CO 2 absorption in aqueous solutions with 5-30 wt% of three cholinium-based amino acid ILs. These authors observed an increase of the apparent absorption rate constant, a decrease of the solution viscosity, and reduction of the CO 2 absorption loading with the increase in water content.Additionally, the replacement of some of the IL by water reduces the cost of the aqueous IL solution.…”

“…[Lys − ] anion is an amphoteric compound that acts as a Lewis acid when combined with the [Cho + ] cation due to the presence of the ammonium group in the latter. However, in the presence of water and CO 2 the [Lys − ] anion acts as a base, leading to CO 2 chemisorption via a mechanism involving the direct There are reported evidences that carbamates can be formed with the carboxylic acid functional group of [Lys − ], due to an intramolecular proton transfer from the α-ammonium ion to the carboxylate group[149,156]. Nevertheless, the carboxylic acid protonation occurs at acidic pH, where stable carbamates can be formed.…”