Bicontinuous zeolitic imidazolate framework ZIF-8@GO membrane with enhanced hydrogen selectivity

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) like ZIF-8 offer tunable porosity for gas separation.
• Graphene oxide (GO) is known for its barrier properties and potential in membrane technology.
• Effective combination of MOFs and 2D materials is crucial for advanced membrane performance.

Purpose of the Study:

• To develop a novel bicontinuous ZIF-8@GO membrane for enhanced gas separation.
• To investigate the gas transport mechanism and selectivity of the ZIF-8@GO membrane.
• To evaluate the performance of the membrane for hydrogen purification applications.

Main Methods:

• Layer-by-layer (LBL) deposition of graphene oxide (GO) suspension onto a semicontinuous ZIF-8 layer.
• Fabrication of a bicontinuous ZIF-8@GO membrane structure.
• Gas permeation and separation experiments at elevated temperatures (250 °C) and pressure (1 bar).

Main Results:

• The ZIF-8@GO membrane effectively seals gaps between ZIF-8 crystals with GO, directing gas flow through ZIF-8 micropores (0.34 nm).
• High hydrogen selectivity was achieved, with mixture separation factors for H2/CO2, H2/N2, H2/CH4, and H2/C3H8 reaching 14.9, 90.5, 139.1, and 3816.6, respectively.
• The membrane exhibited a hydrogen permeance of approximately 1.3 × 10⁻⁷ mol·m⁻²·s⁻¹·Pa⁻¹.

Conclusions:

• The developed ZIF-8@GO membrane shows significant potential for efficient hydrogen separation and purification.
• The LBL deposition method provides a viable route for creating advanced composite membranes with tailored properties.
• The unique bicontinuous structure facilitates molecular sieving based on the intrinsic microporosity of ZIF-8.