CO₂/N₂ Gas Separation Using Pebax/ZIF-7-PSf Composite Membranes

Area of Science:

• Materials Science
• Chemical Engineering
• Membrane Technology

Background:

• Composite membranes are crucial for gas separation.
• Zeolitic imidazolate framework-7 (ZIF-7) exhibits high CO2 adsorption selectivity.
• Pebax-2533 is a promising polymer for membrane applications.

Purpose of the Study:

• To develop a composite membrane incorporating ZIF-7 into a Pebax-2533 selective layer.
• To investigate the gas permeation properties (CO2/N2) of the fabricated composite membrane.
• To evaluate the effect of ZIF-7 content on membrane performance for CO2 separation.

Main Methods:

• Synthesis and characterization of ZIF-7, including BET surface area and adsorption selectivity.
• Fabrication of a composite membrane using polysulfone (PSf) substrate, polyethylene glycol (PEG) for pore size adjustment, and polydimethylsiloxane (PDMS).
• Gas permeation testing of single gases (N2, CO2) through pure and ZIF-7/Pebax-2533 composite membranes.

Main Results:

• ZIF-7 exhibited a BET surface area of 303 m²/g and a CO2/N2 adsorption selectivity of approximately 50.
• Incorporating ZIF-7 into Pebax-2533 significantly reduced N2 permeation and increased CO2 permeation.
• The CO2/N2 ideal selectivity of the composite membrane increased from 6.88 to 50.43 (at 25 wt% ZIF-7).

Conclusions:

• The Pebax-2533/ZIF-7 composite membrane demonstrates superior gas separation performance, particularly for CO2/N2 mixtures.
• The 25 wt% ZIF-7 loading in Pebax-2533 yielded the highest permeation properties and selectivity.
• ZIF-7 is a highly effective additive for enhancing the CO2 separation capabilities of Pebax-2533 based membranes.