Pore Geometry-Driven Capture of Trace Aromatic Volatile Organic Compounds in Al-Based MOFs.

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Aromatic volatile organic compounds (VOCs) are toxic air pollutants posing health risks.
• Adsorbing nonpolar VOCs is challenging due to reliance on weak dispersion forces.
• Efficient sorbent design requires understanding structure-property relationships.

Purpose of the Study:

• To identify structural descriptors for designing metal-organic frameworks (MOFs) for efficient trace aromatic VOC capture.
• To screen MOFs for high affinity towards aromatic molecules based on pore geometry.
• To discover sustainable and scalable MOFs for air purification applications.

Main Methods:

• Computational screening of diverse MOFs based on pore geometry.
• Synthesis and characterization of promising MOF candidates (e.g., MIP-211(Al)).
• Gas adsorption measurements, synchrotron powder X-ray diffraction (SPXRD), density functional theory (DFT), and ATR-FTIR spectroscopy.

Main Results:

• One-dimensional channels with rhombic or square cross sections enhance aromatic VOC adsorption.
• MIP-211(Al) exhibits high toluene uptake (4.7 mmol g⁻¹) at trace concentrations (0.0008 P/P₀).
• MIP-211(Al) shows excellent cycling stability, vacuum regeneration, and retains performance up to 15% relative humidity.

Conclusions:

• Pore geometry is a critical nanoscale parameter for efficient trace aromatic VOC adsorption in MOFs.
• MIP-211(Al) is a highly effective and sustainably synthesized MOF for toluene capture.
• This work provides a design principle for developing advanced sorbents for air quality control.