Enhanced Benzene Adsorption in Chloro-Functionalized Metal-Organic Frameworks

Area of Science:

• Materials Science
• Chemistry
• Environmental Science

Background:

• Adsorbing trace benzene using porous materials is crucial for environmental monitoring and purification.
• Functionalizing metal-organic frameworks (MOFs) offers potential for enhanced selective adsorption.
• Zirconium-based MOFs present tunable structures for gas adsorption applications.

Purpose of the Study:

• To investigate the enhanced adsorption of trace benzene using functionalized zirconium-based MOFs.
• To explore the role of chloro-functionalization in improving benzene uptake capacity.
• To elucidate the adsorption mechanism at a molecular level.

Main Methods:

• Synthesis and characterization of a series of chloro-functionalized zirconium-based MOFs.
• Gas adsorption measurements at trace benzene levels.
• In situ synchrotron X-ray diffraction, Fourier transform infrared microspectroscopy, inelastic neutron scattering, and density functional theory (DFT) modeling.

Main Results:

• MFM-68-Cl2, a zirconium-based MOF with chloro-functionalized anthracene linkers, demonstrated remarkable benzene uptake (4.62 mmol g-1 at 298 K and 0.12 mbar).
• The material significantly outperformed existing benchmark adsorbents for trace benzene.
• Mechanistic studies revealed cooperative effects between chloro-groups, pore size, aromaticity, and linker flexibility driving benzene adsorption.

Conclusions:

• Chloro-functionalization of MOFs, specifically MFM-68-Cl2, effectively enhances trace benzene adsorption.
• The study highlights the significance of -CH···Cl and Cl···π interactions in promoting adsorption in porous materials.
• This work establishes a new strategy for designing advanced MOFs for selective capture of volatile organic compounds.