Highly Robust MOF Polymeric Beads with a Controllable Size for Molecular Separations

Area of Science:

• Materials Science
• Chemical Engineering
• Adsorption Science

Background:

• Shaping metal-organic frameworks (MOFs) into robust, size-controlled particles is crucial for adsorption applications.
• Existing methods may compromise the adsorption properties of the MOF material.

Purpose of the Study:

• To develop a method for producing robust MOF beads with controllable sizes.
• To ensure the formulated MOF particles retain their intrinsic adsorption capabilities.
• To evaluate the suitability of these particles for adsorptive separation processes.

Main Methods:

• A flexible method using zeolitic imidazolate framework-8 (ZIF-8)/polyvinyl formal composite material was employed.
• Characterization included microscopy (SEM), spectroscopy (EDX, ICP-MS), XRD, porosimetry, thermal analysis (TGA/DSC), and crush strength tests.
• Adsorption properties were assessed via static and dynamic experiments in vapor and liquid phases.

Main Results:

• Robust MOF beads (250 μm to millimeters) with high MOF loading (up to 85 wt%) were successfully produced.
• Particles exhibited preserved ZIF-8 crystalline structure, microporosity, and a narrow macropore distribution (1.27 μm).
• High mechanical strength (3.09 N/Pc) and stability up to 200°C and in most solvents were confirmed.
• Adsorption capacity was minimally affected by binder content, indicating no pore intrusion.

Conclusions:

• The developed method yields resistant MOF particles suitable for adsorptive separations.
• The composite material demonstrates excellent mechanical and thermal stability.
• Effective vapor-phase separation performance was observed, with limitations noted in liquid-phase mass transfer at higher flow rates.