Understanding the CO2 capture potential of tetrapropylammonium-based multifunctional deep eutectic solvent via molecular simulation

A multiscale theoretical study on the suitability of the bifunctional hydrophobic Deep Eutectic Solvent based on tetrapropylammonium chloride and acetic acid with ethanolamine is reported. Density Functional Theory quantum calculations along with classical Molecular Dynamics simulations provide a nanoscopic characteriza-tion of the properties of the studied sorbent in terms of intermolecular forces and liquid phase structuring and the characterization of the mechanism of CO2 absorption considering gas - liquid phase interfaces for neat CO2 and a realistic flue gas mixture. Results in this paper characterize the evolution of CO2 into liquid phases as well as the changes produced in the fluid upon gas capture through hydrogen bonding, void occupation and molecular clustering. The possible effect of having two different types of functionalities in the sorbent, amine and hydroxyl groups, which may lead to possible chemical and/or physical sorption is analyzed, considering their possible competing in CO2 capture. The reported study provides the first characterization of multifunctional Deep Eutectic Solvents for carbon capture from complex realistic gas mixtures.