Appealing sheath-core spun high-performance composite carbon molecular sieve membranes

Area of Science:

• Materials Science
• Chemical Engineering
• Membrane Technology

Background:

• Carbon molecular sieve (CMS) membranes are promising for gas separations due to their intrinsic properties.
• Achieving desired performance in asymmetric membranes, especially for CO2 removal from natural gas, remains a challenge.
• Existing rigid glassy polymers often lack the necessary mechanical properties for high-pressure applications.

Purpose of the Study:

• To develop a novel asymmetric CMS membrane with a unique "Pseudo Wheel+Hub & Spoke" structure.
• To enhance CO2/CH4 selectivity and permeance for efficient natural gas sweetening.
• To create a cost-effective membrane by reducing the use of expensive precursor materials.

Main Methods:

• Fabrication of asymmetric hollow fiber precursors using sheath-core spinning with 6FDA-DAM and Matrimid®.
• Optimized pyrolysis of precursors to form defect-free CMS membranes.
• Testing of the composite CMS membrane using a 50:50 CO2/CH4 mixed gas feed.

Main Results:

• The developed CMS membrane exhibited a high CO2/CH4 selectivity of 64.3.
• Achieved a CO2 permeance of 232 GPU at 35°C under mixed gas conditions.
• Demonstrated a defect-free structure and effective support for the selective layer, enabling low flow resistance.

Conclusions:

• The "Pseudo Wheel+Hub & Spoke" asymmetric CMS membrane offers a viable solution for efficient CO2 removal from natural gas.
• The composite structure provides mechanical support and low flow resistance, even at high pressures.
• This approach reduces the reliance on costly high-performance polymers, offering economic advantages.