Designing and Screening of Multi-Amino-Functionalized Ionic Liquid Solution for CO2 Capture by Quantum Chemical Simulation

The structure and group combination of amino-functionalized ionic liquids (AFILs), such as chain length, number of amino groups, interaction energy, and activation barrier, were the important factors affecting their performance of CO2 capture. As a forecasting tool, quantum chemical calculation can be used to screen and design the AFILs. In the present work, some different types of multi-AFILs (e.g., [DETAH][Lys], [TETAH][Lys], [DDAH][Lys], and [BTAH][Lys]) were first designed, and their performance was forecasted under the DFT method, B3LYP 6-311++G(d,p) basis set. On the basis of the results of the quantum chemical comparing and excluding, [TETAH][Lys] and [DETAH][Lys] were chosen as the efficient absorbents for CO2 capture, which were expected to achieve a high CO2 loading more than 2.0 mol CO2/mol AFILs with a high regeneration efficiency. Then, the experimental results confirmed the predictions of the quantum chemical calculation. The experimental results showed that the absorption capacities of [TETAH][Lys] and [DETAH][Lys] were 2.59 and 2.13 mol CO2/mol AFILs, and the regeneration efficiencies were 98.96% and 98.00%, respectively. Finally, the reaction mechanism of CO2 capture into these AFILs was explored by using 13C NMR. The present work proved that it was feasible to use quantum chemical calculation to design ILs, which could be an efficient way for further AFIL research.