Solubility of greenhouse and acid gases on the [C₄mim][MeSO₄] ionic liquid for gas separation and CO₂ conversion

Ionic liquids (ILs) are an exciting class of compounds of high interest from a technological point of view. One of the applications that is raising more interest is their possible use as solvents to carry out the conversion of CO₂ into more valuable compounds. Theoretical approaches provide an attractive option to screen ILs properties and give quick answers to guide the experiments, becoming a crucial tool for process design. This work illustrates a practical example based on the solubility of greenhouse and acid gases on the butylmethylimidazolium methylsulfate [C₄mim][MeSO₄] IL, in order to study its feasibility for gas separation and conversion. A simple but reliable molecular model is presented for the ionic liquid based on structural information and molecular simulations, and coarse-grained models are used to model the different gases. The absorption of relevant gases for the separation/conversion process (CO₂, CH₄, CO, H₂, SO₂, H₂S) in [C₄mim][MeSO₄] is modeled and compared with experimental data using a minimum amount of binary data. From this information, the ternary diagrams of [C₄mim][MeSO₄] with CO₂ and the acid gases SO₂ and H₂S are predicted, and the selectivity of CO₂ by respect all the gases is evaluated, with particular attention to the contaminants above mentioned.