The osmotic framework adsorbed solution theory: predicting mixture coadsorption in flexible nanoporous materials

Area of Science:

• Materials Science
• Chemical Engineering
• Computational Chemistry

Background:

• Predictive models are vital for designing adsorptive gas separation processes.
• Flexible nanoporous materials, like dynamic metal-organic frameworks (MOFs), exhibit unique structural transitions (e.g., gate opening, breathing) upon gas adsorption, posing challenges for existing models.
• Current predictive methods are primarily developed for rigid materials, limiting their application to flexible MOFs.

Purpose of the Study:

• To develop a predictive model for understanding and forecasting structural transitions in flexible nanoporous materials during gas mixture adsorption.
• To accurately predict the selectivity of gas separation processes involving dynamic MOFs.
• To provide a tool for the rational design of MOFs for specific gas separation applications.

Main Methods:

• Development of the Osmotic Framework Adsorbed Solution Theory (OFAST).
• Utilizing experimental pure component adsorption isotherms as the sole input data.
• Applying OFAST to predict the behavior of flexible nanoporous solids under fluid mixture adsorption conditions.

Main Results:

• OFAST successfully predicts the evolution of structural transitions in flexible nanoporous solids upon adsorption of fluid mixtures.
• The theory accurately forecasts changes in selectivity driven by adsorption-induced structural changes.
• Demonstrated the capability to use only experimental pure component isotherms for these predictions.

Conclusions:

• OFAST provides a robust theoretical framework for modeling adsorption in flexible nanoporous materials.
• This advancement enables the design and optimization of gas separation processes using dynamic MOFs.
• The model's reliance on simple experimental inputs makes it broadly applicable.