Thermodynamic modeling and rational design of ionic liquids for pre-combustion carbon capture

Abstract

Although ionic liquids (ILs) have been widely explored as promising solvents for carbon capture, systematic study on the rational selection and design of ILs for carbon capture processes is still scarce. In this contribution, a comprehensive literature survey is first performed to provide an up-to-date database comprising 10,116 CO2 solubility data and 463 H2 solubility data measured in a large number of ILs at various temperatures and pressures. Using this dataset, the UNIFAC-IL model for predicting the vapor–liquid equilibrium of the CO2-H2-IL ternary system is developed, where 42 main groups and 53 subgroups are specified and 220 group interaction parameters are fitted. With this model, an optimization-based computer-aided ionic liquid design problem is finally formulated and solved to identify the best ILs for the pre-combustion carbon capture process. It is found that the hydroxyl-ammonium and hydroxyl-imidazolium bis(trifluoromethylsulfonyl)amide ILs are the most promising solvent candidates.