CO₂/N₂ Separation Properties of Polyimide-Based Mixed-Matrix Membranes Comprising UiO-66 with Various Functionalities

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Mixed-matrix membranes (MMMs) are crucial for gas separation.
• Polyimide membranes offer good processability but require performance enhancement for CO2/N2 separation.

Purpose of the Study:

• To develop advanced MMMs for efficient CO2/N2 separation.
• To investigate the impact of functionalized UiO-66 nanocrystals on membrane performance.

Main Methods:

• Synthesis of nanocrystalline UiO-66 and its functionalized derivatives (-NH2, -Br, -(OH)2).
• Incorporation of UiO-66 nanocrystals into a polyimide matrix to form MMMs.
• Evaluation of CO2/N2 separation performance using permeability and selectivity measurements.
• Solubility-diffusivity analysis to elucidate separation mechanisms.

Main Results:

• Non-functionalized UiO-66 improved CO2 permeability but slightly decreased selectivity.
• Functionalized UiO-66 derivatives (UiO-66-NH2, UiO-66-Br, UiO-66-(OH)2) enhanced CO2/N2 selectivity by 12%, 4%, and 17%, respectively.
• Functionalized UiO-66 increased CO2 diffusivity and suppressed N2 sorption in the MMMs.

Conclusions:

• Structural tuning of UiO-66 via functionalization is an effective strategy for enhancing CO2 separation in MMMs.
• The developed MMMs show significant potential for industrial CO2/N2 separation applications.