A Robust Squarate-Based Metal-Organic Framework Demonstrates Record-High Affinity and Selectivity for Xenon over...

Area of Science:

• Materials Science
• Chemical Engineering
• Adsorption Science

Background:

• Efficient separation of xenon (Xe) and krypton (Kr) is critical for industrial applications.
• Developing highly selective adsorbents for Xe/Kr separation remains a significant challenge.
• Adsorptive separation is an energy-efficient alternative to traditional methods.

Purpose of the Study:

• To develop a novel metal-organic framework (MOF) for highly selective Xe/Kr separation.
• To investigate the adsorption properties and separation performance of the MOF.
• To elucidate the mechanism behind the enhanced Xe/Kr selectivity.

Main Methods:

• Synthesis of a rigid squarate-based metal-organic framework (MOF).
• Characterization of pore size and surface chemistry (polar hydroxyl groups).
• Gas adsorption isotherms, breakthrough experiments, and density functional theory (DFT) calculations.

Main Results:

• The MOF features a pore size of 4.1 Å × 4.3 Å, ideal for Xe discrimination.
• Record-high Xe/Kr selectivity (60.6) and Xe uptake (58.4 cm³/cm³) achieved at 0.2 bar and ambient temperature.
• Highest reported Xe Henry coefficient (192.1 mmol/g/bar) and Xe/Kr Henry selectivity (54.1).
• DFT calculations confirmed strong Xe-framework interaction due to optimal pore size and polar surface.

Conclusions:

• The squarate-based MOF demonstrates superior performance for Xe/Kr separation.
• The synergy between pore size and polar functionalization drives the high selectivity.
• This MOF represents a significant advancement in adsorbent materials for noble gas separation.