Low-Viscosity Triethylbutylammonium Acetate as a Task-Specific Ionic Liquid for Reversible CO₂ Absorption

Capturing and storing carbon dioxide (CO 2 ) is now of concern. This work presents a task-specific ionic liquid (TSIL), triethylbutylammonium acetate ([N 2224 ][CH 3 COO]), for the purpose of trapping CO 2 instead of the commonly used organic amine solutions. Since [N 2224 ][CH 3 COO] has a hydrophilic nature, the CO 2 dissolution behavior into [N 2224 ][CH 3 COO]− n H 2 O complexes has been investigated in detail, including the absorption rate, absorption capacity, and the ability of repeating absorption. The solubilities of CO 2 into [N 2224 ][CH 3 COO]−1H 2 O at 0 °C, 25 °C, 40 °C, and 60 °C from (0.007 up to 30) bar are presented. The results show strong evidence that [N 2224 ][CH 3 COO]−1H 2 O is an excellent reversible absorbent for CO 2, and the recovered [N 2224 ][CH 3 COO]−1H 2 O maintains the same absorption capacity and absorption rate. The CO 2 absorption into [N 2224 ][CH 3 COO]− n H 2 O mixtures at 25 °C and pressures up to 30 bar is also studied. It is elucidated that the absorption capacity decreases with the content of water and the rise of operational temperature. The equilibrium constant, Henry’s law constant, overall rate constant, and activation energy are also calculated from the experimental data. All evidence indicates that [N 2224 ][CH 3 COO]− n H 2 O with low viscosity may have potential to be used as good absorbents for CO 2 capture.