Tailoring Pore Environments in Metal-Organic Frameworks for Efficient C₂H₂/CO₂ and C₂H₂/C₂H₄ Separations

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Efficient separation of acetylene (C₂H₂) from carbon dioxide (CO₂) and ethylene (C₂H₄) is crucial for industrial processes.
• Similar physicochemical properties of these gases make separation challenging.

Purpose of the Study:

• To design and synthesize novel metal-organic frameworks (MOFs) for selective acetylene capture.
• To investigate the role of pore-environment engineering in enhancing gas separation performance.

Main Methods:

• Construction of isostructural MOFs (Co₄-L) using sulfate-capped Co₄ clusters and N-rich linkers.
• Incorporation of 1,4-naphthalenedicarboxylic acid (1,4-ndc) to create the Co₄-1,4-ndc framework.
• Experimental measurement of C₂H₂ capture capacities and selectivity.
• Theoretical simulations to elucidate binding mechanisms.

Main Results:

• The Co₄-1,4-ndc framework demonstrated optimal pore confinement for C₂H₂ adsorption.
• High C₂H₂ capture capacities of 4.30 mmol g⁻¹ (C₂H₂/CO₂) and 3.40 mmol g⁻¹ (C₂H₂/C₂H₄) were achieved.
• Theoretical simulations confirmed cooperative hydrogen-bonding interactions enhance C₂H₂ selectivity.

Conclusions:

• Pore-environment engineering in MOFs is effective for selective C₂H₂ separation.
• The Co₄-1,4-ndc MOF shows promise as an advanced adsorbent for industrial gas purification.
• Cooperative hydrogen bonding plays a key role in preferential C₂H₂ binding.