Building high-performance mixed matrix membranes from stable COF colloids for CO₂/N₂ separation

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) show promise for gas separation.
• Developing stable COF colloids for membrane applications remains challenging.
• Pebax-1657 membranes offer good gas separation but have limitations.

Purpose of the Study:

• To synthesize stable β-ketoenamine-linked COF colloids using a novel strategy.
• To fabricate mixed matrix membranes (MMMs) incorporating these COF colloids.
• To evaluate the gas separation performance of the developed MMMs.

Main Methods:

• A "retardation & solvation" strategy was employed for COF colloid synthesis.
• COF colloids were incorporated into a Pebax-1657 polymer matrix.
• Gas separation performance (CO2 permeability and CO2/N2 selectivity) was measured.

Main Results:

• Stable β-ketoenamine-linked COF colloids were successfully synthesized.
• The MMMs exhibited high CO2 permeability (up to 322 Barrer).
• Exceptional CO2/N2 selectivity (over 72.1) was achieved, approaching the 2019 Robeson upper boundary.

Conclusions:

• The "retardation & solvation" strategy is effective for creating stable COF colloids.
• The developed MMMs demonstrate superior gas separation performance compared to pristine membranes.
• These findings offer a promising pathway for advanced CO2 capture technologies.