Tuning MOF/polymer interfacial pore geometry in mixed matrix membrane for upgrading CO₂ separation performance.

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Mixed-matrix membranes (MMMOFs) are crucial for gas separation.
• Controlling the metal-organic framework (MOF)/polymer interface is key for MMMOF fabrication.
• Current strategies focus on compatibility, overlooking interfacial nanostructure's role in transport.

Purpose of the Study:

• To investigate the impact of interfacial pore shape nanostructure on molecular transport in MMMOFs.
• To design and fabricate a novel MMMOF with tailored interfacial properties.
• To evaluate the gas separation performance of the developed MMMOF.

Main Methods:

• Assembled ultrasmall pore AlFFIVE-1-Ni MOF with PIM-1 polymer.
• Designed a composite with gradually expanding pore from MOF entrance to interface.
• Utilized concentration gradient-driven molecular dynamics simulations.
• Fabricated a [001]-oriented nanosheets AlFFIVE-1-Ni/PIM-1 MMMOF membrane.

Main Results:

• Demonstrated that interfacial pore nanostructuring creates an optimum guided path for gas molecules.
• Showcased accelerated molecular transport across the MMMOF membrane.
• Achieved excellent CO2 permeability, surpassing many existing MMMs.
• Observed high CO2/CH4 selectivity, suitable for natural gas purification.

Conclusions:

• Interfacial pore shape nanostructure is critical for optimizing molecular transport in MMMOFs.
• The designed AlFFIVE-1-Ni/PIM-1 MMMOF exhibits superior gas separation performance.
• This approach holds significant promise for natural gas and biogas purification applications.