Covalent Organic Polymer Membranes with Exceptional Selectivities for Advanced High-Pressure Stable Gas Separations

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Advanced gas separation membranes face challenges in balancing pore size control and defect-free layer formation.
• Covalent Organic Polymers (COPs) offer tunable structures but require optimized fabrication for high performance.

Purpose of the Study:

• To develop a high-performance, defect-free covalent organic polymer (COP) membrane for advanced gas separations.
• To overcome the trade-off between pore size control and membrane integrity using a novel fabrication strategy.

Main Methods:

• Fabrication of a COP membrane using a modulated interfacial polymerization strategy with tetra-amine and tri-aldehyde monomers.
• Design of COP structure to enhance cross-linking density and reduce micropore size (≈0.34 nm).
• Incorporation of ionic liquid and acetic acid to control polymerization kinetics and ensure a continuous, defect-free layer.

Main Results:

• The COP membrane exhibited a narrow pore size distribution suitable for molecular sieving.
• Achieved exceptional H2/CH4 separation with an ideal selectivity of 297.6 and H2 permeance of 203.4 GPU.
• Demonstrated stable performance under high feed pressures up to 2 MPa due to robust, highly cross-linked networks.

Conclusions:

• The modulated interfacial polymerization strategy enables precise control over COP membrane fabrication.
• The developed COP membrane shows significant potential for energy-efficient gas separations, particularly H2/CH4, under demanding conditions.
• This approach provides a feasible route for designing high-pressure stable, molecular-sieving COP membranes.