Simultaneously Enhanced Permeability and Selectivity of Pebax-1074-Based Mixed-Matrix Membrane for CO₂ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Membrane technology offers a low-carbon footprint solution for carbon dioxide (CO2) separation.
• A significant challenge in membrane applications is the inherent trade-off between gas permeability and selectivity.
• Existing membranes often struggle to achieve high performance in CO2 capture.

Purpose of the Study:

• To develop an advanced membrane material for efficient CO2 separation.
• To overcome the permeability-selectivity trade-off in CO2 capture membranes.
• To investigate the synergistic effects of incorporating a modified metal-organic framework (MOF) into a polymer matrix.

Main Methods:

• Grafting branched polyethyleneimine (BPEI) onto the AIFFIVE-1-Ni (KAUST-8) MOF via coordination chemistry.
• Fabricating mixed-matrix membranes (MMMs) using the modified MOF (KAUST-8@BPEI) within a Pebax-1074 polymer matrix.
• Evaluating the CO2 separation performance of the fabricated MMMs, including CO2 permeability and CO2/N2 selectivity.

Main Results:

• The KAUST-8@BPEI/Pebax-1074 MMM demonstrated significantly enhanced CO2 separation performance compared to MOF-only MMMs.
• At 5 wt.% loading, the KAUST-8@BPEI MMM achieved a CO2 permeability of 156.5 Barrer and a CO2/N2 selectivity of 16.1.
• The enhanced performance is attributed to increased CO2 solubility from BPEI's amino groups and improved CO2 diffusivity via KAUST-8's channels.

Conclusions:

• The coordination grafting of BPEI onto KAUST-8 effectively creates a high-performance filler for CO2 separation membranes.
• The developed KAUST-8@BPEI/Pebax-1074 MMM surpasses the performance of many reported Pebax-1074-based MMMs.
• This coordination strategy presents a promising approach for designing advanced MOF-based membranes for effective carbon capture.