Selective CO₂ Adsorption in Ultrahydrophobic Molecular Pyrene Frameworks by Computational Design.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Humidity in industrial flue gas hinders effective carbon dioxide (CO2) separation by most porous sorbents.
• Water competes with CO2 for adsorption sites, reducing CO2 capture capacity and increasing regeneration costs.

Purpose of the Study:

• To develop novel porous materials capable of selective CO2 separation under humid conditions.
• To identify and synthesize pyrene-based hydrogen bonded organic frameworks (HOFs) with high CO2 affinity and low water adsorption.

Main Methods:

• High-throughput density functional theory (DFT) screening and crystal structure prediction (CSP) to design hydrophobic frameworks.
• Gas sorption experiments to evaluate CO2 and water adsorption.
• Dynamic column breakthrough measurements under simulated flue gas conditions.
• Stability testing including boiling in aqueous acids.

Main Results:

• Two pyrene-based HOFs demonstrated selective CO2 adsorption with minimal water uptake.
• CO2 working capacity remained unaffected by up to 75% relative humidity.
• One HOF, diMeTBAP-α, was predicted to be thermodynamically stable via CSP.
• A scalable analogue, MeTBAP-α, maintained porosity and crystallinity after harsh stability tests.

Conclusions:

• Pyrene-based HOFs offer a promising solution for CO2 capture from humid industrial flue gas.
• The developed materials exhibit high CO2 selectivity, working capacity, and chemical stability, crucial for carbon capture applications.