Determination of Absorption Rate and Capacity of CO₂ in Ionic Liquids at Atmospheric Pressure by Thermogravimetric Analysis

Abstract

Here, a cheap and fast way to measure the CO 2 absorption rate and capacity through thermogravimetric analysis (TGA) is proposed. The absorption of CO 2 in 11 ILs varying in anion, cation, alkyl chain length, and C2 methylation was then investigated. Three parameters comprehensively characterizing the absorption capacity and kinetics, including the absorption capacity (x), the initial absorption rate (r 10 ), and the degree of difficulty to reach phase equilibrium (t 0.9 ), were proposed as the standards to evaluate the potential of ILs for CO 2 capture. Results show that the correlation between absorption capacity and the degree of difficulty to reach phase equilibrium is complicated. However, ILs with higher absorption capacity usually have a higher initial absorption rate, suggesting a simple way to estimate absorption capacity just by determining initial absorption rate for less than 10 min. More importantly, ILs with the acetate ([Ac]) anions have an advantage in x, r 10 , and t 0.9 over other ILs, indicating that [Ac]-based ILs are promising candidates for CO 2 capture in practice.

Supported ionic liquids as highly efficient and low-cost material for CO2/CH4 separation process

“…This result is related to chemical absorption capacity of CO 2 by the IL [bmim][OAc]. In this case CO 2 reacts with the imidazolium ring cation forming carboxylate thus increasing CO 2 absorption capacity (Chen et al., 2011; Moya et al., 2016; Zareiekordshouli et al., 2018; Ziobrowski et al., 2016).

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Carbon dioxide adsorption by zinc-functionalized ionic liquid impregnated into bio-templated mesoporous silica beads

“…The difference in the behavior of the two bulk ILs is clear. ET has reached its equilibrium capacity of 0.5 wt% after 5 x 10 3 s, with the shape of the curve characteristic of a physisorptive-type kinetics [59]. In contrast, EZT3 reached 2.9 wt% after 2 x 10 4 s exposure to CO 2 with the shape of the curve indicative of a chemisorptive nature of absorption.…”

Investigations on the thermal stability and decomposition mechanism of an amine-functionalized ionic liquid by TGA, NMR, TG-MS experiments and DFT calculations

“…First, the heating mode was set to isothermal (60°C) in N 2 (60 mL/min). It was set to remove any possible volatile impurities in the IL or contaminates during the transfer process in the moist air [38]. The gaseous impurities were assumed to be totally removed when the mass loss rate was less than 0.0001 mg/min.…”