Molecular dynamics simulations of a dicationic ionic liquid for CO2 capture

A dicationic ionic liquid ([DBU-PEG][Tf2N](2)) was studied using classical molecular dynamics simulations to examine its structural and gas separation properties. The dication was designed in an attempt to improve CO2 solubility by means of tuning the cation-anion interactions of the ionic liquid (IL). The computational model was compared to experimentally obtained density, viscosity, and powder X-ray diffraction spectra. The structure of the IL was further investigated with radial distribution functions and free volume analysis through cavity distributions. It was found that the shape and charge distribution of the dication enhances CO2 interaction: the CO2 molecule is hugged by the dication along the PEG linker and close to one of the cationic ends. The geminal design of the dication allows for strong interaction with CO2, showing promise as a means of carbon capture. (C) 2021 Elsevier B.V. All rights reserved.