Hybrid Computational Strategy for Predicting CO2 Solubilities in Reactive Ionic Liquids

A combination of ab initio calculations and classical molecular dynamics simulations was used to calculate the free energy of reacting an aprotic heterocyclic anion ionic liquid with CO2. The overall reaction was broken into a series of steps using a thermodynamic cycle to calculate the free energy of the gas phase reaction and the free energy contributions of solvation environment effects, which make comparable contributions to the total free energy of reaction. CO2 absorption isotherms that agree reasonably well with experimental data were calculated using a derived expression for the free energy of reaction as a function of temperature, pressure, and the extent of reaction.