Screening 928 ionic liquids with AMS for more energy-efficient separation processes

Separating benzene and methanol is challenging because the two compounds form an azeotrope, making conventional distillation ineffective. Ionic liquids offer a promising alternative as selective entrainers, but identifying suitable candidates requires balancing separation performance, miscibility, thermal stability, and process efficiency.

In a recent Industrial & Engineering Chemistry Research study, Liu and co-workers combined molecular modeling, experiments, and process optimization to develop a more efficient separation strategy. Using the Amsterdam Modeling Suite (AMS) and COSMO-SAC, the researchers screened 928 ionic liquids based on their predicted selectivity toward methanol and benzene. Three promising candidates were subsequently investigated experimentally, revealing that the ionic liquid [C₄C₁im][DBP] offered the best balance between separation selectivity and complete miscibility with both components.

Further quantum-chemical calculations and molecular dynamics simulations revealed that hydrogen bonding between ionic-liquid anions and methanol plays a key role in disrupting the azeotrope. Building on these molecular insights, the researchers optimized several extractive distillation processes, including a heat-pump-assisted configuration that reduced energy consumption by 27.45%, annual costs by 13.70%, and gas emissions by 27.00% compared with the conventional ionic-liquid process.

The study demonstrates how molecular-level thermodynamic predictions with AMS can support solvent screening and guide the development of more efficient industrial separation processes, connecting molecular interactions with practical process design.