Prediction of the Solubility of Acid Gas Hydrogen Sulfide in Green Solvent Ionic Liquids via Quantitative Structure–Property Relationship Models Based on the Molecular Structure

Ionic liquids (ILs) can be used as capturing acidic gases that damage the environment. By establishing a quantitative structure–property relationship (QSPR) model of the IL structure, temperature, pressure, and H2S solubility, it can be used to screen ILs with excellent properties. In this study, molecular descriptors (MD), molecular identifiers (MI), and combinations of MD and MI (MD_MI) are used to represent the structure of ILs, combining pressure and temperature as the input of the model; the QSPR model is built by coupling the two models of the deep neural network (DNN) and random forest (RF). We find that the model constructed by using MI to represent ILs and DNN has the best performance. The Shapley additive explanation (SHAP) method is used to analyze features to obtain the most valuable molecular structure information for prediction. The results show that the contribution degree and direction of different MD and MI in the prediction of H2S solubility are different and correctly identify the impact of environmental factors (temperature and pressure). Finally, the electrostatic potential (ESP) between H2S and ILs was calculated to study the influence of different carbon chain lengths on the solubility of H2S.