Tailored Polymer-Zeolite Imidazolate Framework Membranes for Aperture-Matched C4 Hydrocarbon Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Metal-organic frameworks (MOFs) integration with polymers for C4 hydrocarbon separation is hindered by phase incompatibility.
• Zeolitic-imidazolate frameworks (ZIFs) offer tunable porosity but integrating them into polymers remains challenging.

Purpose of the Study:

• To develop an in-situ synthesis strategy for polymer-ZIF composites (polyZIF) for enhanced C4 hydrocarbon separation.
• To overcome phase incompatibility issues in MOF-polymer membranes.
• To create scalable, defect-free membranes with molecular-sieving capabilities.

Main Methods:

• In-situ synthesis of polyZIF using polymer-metal-ligand coordination bonds and structural directing agents.
• Fabrication of polyZIF membranes.
• Characterization of surface area, porosity, and separation performance using mixed gas conditions.

Main Results:

• Achieved a polyZIF membrane with a BET surface area of 261 m² g⁻¹ and permanent porosity of 4.42 Å.
• Demonstrated high butadiene permeance (∼332 GPU) and selectivity over various C4 hydrocarbons.
• Successfully fabricated large-area (up to 80 cm²) defect-free membranes with robust separation performance.

Conclusions:

• The in-situ polyZIF synthesis strategy effectively integrates ZIFs with polymers, overcoming phase incompatibility.
• The resulting polyZIF membranes exhibit excellent C4 hydrocarbon molecular-sieving capabilities.
• This approach offers a promising pathway for the industrial application of ZIF-based polymer membranes in gas separation.