Designing optimal core-shell MOFs for direct air capture

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Metal-organic frameworks (MOFs) are promising for selective carbon dioxide (CO2) adsorption in carbon capture.
• Strong CO2 adsorbents often exhibit high affinity for water (H2O), hindering performance in humid industrial streams.
• Water competition for binding sites is a major challenge in existing CO2 capture technologies.

Purpose of the Study:

• To introduce and evaluate a novel core-shell MOF design strategy for selective CO2 capture.
• To overcome the challenge of water competition in CO2 adsorption processes.
• To identify optimal core-shell MOF pairs for enhanced carbon capture performance.

Main Methods:

• Utilized a core-shell MOF design where a CO2-adsorbing core is shielded by a water-impermeable shell.
• Employed high-frequency adsorption/desorption cycles to regenerate adsorbents before water diffusion.
• Combined experimental measurements, computational modeling, and multiphysics modeling to screen MOF pairs.
• Generated a library of 1740 core-shell MOF pairs from UiO-66 and UiO-67 with functional variations.

Main Results:

• Identified 10 core-shell MOF candidates with significantly enhanced performance over individual MOFs.
• Demonstrated the effectiveness of the core-shell design in preventing water interference with CO2 adsorption.
• Established a performance score for ranking and selecting optimal MOF pairs for carbon capture.

Conclusions:

• Core-shell MOF architecture is a viable strategy to enhance selective CO2 adsorption in the presence of water.
• The proposed design circumvents water competition, leading to improved efficiency in carbon capture processes.
• This research provides a pathway for developing advanced materials for effective and selective CO2 removal.