Enhanced ethylene/ethane selectivity of PI membrane with functionalized zeolite addition

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Mixed-matrix membranes (MMMs) are crucial for gas separation, but their use in ethylene/ethane separation is limited.
• Polyimide membranes often struggle to achieve high selectivity for C₂H₄/C₂H₆ separation.

Purpose of the Study:

• To investigate the effect of incorporating functionalized zeolite fillers into 6FDA-DAM polyimide membranes for improved ethylene/ethane separation.
• To evaluate the performance of 4-methoxybenzene-functionalized MOR (f-MOR) zeolite as a filler for enhancing C₂H₄/C₂H₆ separation.

Main Methods:

• Fabrication of mixed-matrix membranes (MMMs) using a 6FDA-DAM polyimide matrix and zeolite fillers (f-MOR and neat MOR).
• Characterization of MMMs' gas separation performance for ethylene/ethane mixtures.
• Analysis of the influence of filler type and concentration (20 wt%) on permeability and selectivity.

Main Results:

• Incorporating 20 wt% f-MOR significantly increased C₂H₄ permeability (by 63%) and ideal selectivity (by 11%) to 22.7 Barrer and 5.2, respectively.
• Neat MOR filler increased C₂H₄ permeability but decreased selectivity to 3.1.
• Enhanced selectivity in f-MOR MMMs is attributed to increased ethylene solubility, not diffusion.

Conclusions:

• Functionalized zeolite fillers, specifically f-MOR, can enhance ethylene/ethane separation performance in polyimide-based MMMs.
• The study demonstrates the potential of integrating adsorbent functionalities into membranes for C₂ hydrocarbon separations.
• Further strategies are needed to overcome challenges like low-pressure plasticization-like behavior for practical applications.