Correlation-Based Predictions of Gas Solute Diffusivity in Ionic Liquid Solvents Based on Solvent-Accessible Surface...

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Predicting gas diffusion in ionic liquids (ILs) is crucial for chemical processes.
• Previous work established a scaling relationship for CO2 and SO2 diffusion in multivalent ILs.

Purpose of the Study:

• Extend the predictive scaling relationship for gas solute diffusion to a wider range of solutes and ILs.
• Elucidate the molecular mechanisms governing gas diffusion in ILs.

Main Methods:

• Computational simulations of various gas solutes (N2, CH4, C2H6, C3H8, C3H8O, H2O) in diverse ionic liquids.
• Analysis of solute diffusion, solvent accessible surface area (SA), solute lifetime distributions, void space dynamics, and Voronoi tessellation.

Main Results:

• A robust logarithmic correlation was found between gas solute diffusion and solvent accessible surface area across 20 systems.
• Direct link established between solvent accessible SA and void domain size.
• Molecular dynamics analyses provided mechanistic understanding of diffusion behavior.

Conclusions:

• The developed scaling approach efficiently and reliably predicts gas diffusion in ILs.
• Findings support using short simulations at higher temperatures for diffusion predictions.
• Understanding the interplay between solvent accessible surface area and void dynamics is key for IL-based separations and reactions.