Ionic liquid screening for CO2 capture and H2S removal from gases: The syngas purification case

Abstract

A systematic ionic liquid (IL) screening approach for acid gas removal processes was developed by taking into account a wide range of process performance-determining factors. Selective and non-selective absorption of CO2 and H2S from syngas in conceptual low- and high-temperature processes was investigated to explore the optimal solvents, among 5980 ILs, for each process. Making use of the COSMO-RS and other suitable IL-systems predictive models, the process thermal efficiency (absorption enthalpy and sensible heat) and absorption–desorption working capacity were addressed in the selection of IL candidates along with the primary factors such as solubilities and selectivities. Meanwhile, the COSMO-RS predicted results were validated, and σ-profile and σ-potential of CO2, H2S, H2, CO and the featured ILs were analyzed to provide theoretical insights into intermolecular interactions between gas and IL. The same IL screening method can be extended to CO2 capture and H2S removal from natural gas, biogas, and other sources.