Understanding Gas Solubility of Pure Component and Binary Mixtures within Multivalent Ionic Liquids from Molecular Simulations.

Understanding the molecular-level solubility of CO2 and its mixtures is essential to the progress of gas-treating technologies. Herein, we use grand canonical Monte Carlo simulations to study the single-component gas absorption of SO2, N2, CH4, and H2 and binary mixtures of CO2/SO2, CO2/N2, CO2/CH4, and CO2/H2 of varying mole fractions within multivalent ionic liquids (ILs). Our results highlight the importance of the free volume effect and the anion effect when interpreting the absorption behavior of these mixtures, similar to the behavior of CO2 found in our previous study (Phys. Chem. Chem. Phys. 2020, 22, 20618-20633). The deviation of gas solubility between the pure component absorption versus the binary absorption, as well as the solubility selectivity, highlights the importance of the relative affinity of gas species within a mixture to the different anions. The absorption selectivity within a specific IL system can be predicted based on the relative gas affinity to the anion.