Composite amine mixed matrix membranes for high-pressure CO₂-CH₄ separation: synthesis, characterization and...

Area of Science:

• Materials Science
• Chemical Engineering
• Membrane Technology

Background:

• Composite mixed matrix membranes (MMMs) face fabrication challenges with porous supports using dry-wet phase inversion.
• Efficient separation of carbon dioxide (CO2) from methane (CH4) is crucial for natural gas purification and carbon capture.

Purpose of the Study:

• To synthesize thin composite ternary (amine) mixed matrix membranes (MMMs) on microporous support.
• To incorporate carbon molecular sieve (CMS) and diethanolamine (DEA) into a polyethersulfone (PES) matrix for CO2/CH4 separation.
• To evaluate membrane performance under high-pressure conditions (10-30 bar).

Main Methods:

• Fabrication of PES/CMS/DEA composite MMMs via dry-wet phase inversion.
• Characterization of membrane morphology, thermal stability, mechanical strength, and functional groups.
• High-pressure CO2/CH4 gas separation performance testing.
• Theoretical prediction of membrane performance using a modified Maxwell model.

Main Results:

• Developed membranes exhibit asymmetric structures and mechanical robustness at 30 bar.
• PES/CMS/DEA composite MMMs show improved gas permeance compared to pure PES membranes.
• CO2/CH4 perm-selectivity increased from 8.15 to 16.04 with 15 wt% DEA at 30 bar.
• Theoretical predictions closely matched experimental data (AARE % < 2%, R² = 0.99).

Conclusions:

• The synthesized PES/CMS/DEA composite MMMs are suitable for high-pressure CO2/CH4 separation.
• Incorporation of CMS and DEA significantly enhances membrane separation performance.
• The modified Maxwell model accurately predicts the performance of these novel composite membranes.