Metal-Organic Framework UiO-66 Layer: A Highly Oriented Membrane with Good Selectivity and Hydrogen Permeance

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable porosity for gas separation.
• UiO-66, a robust MOF with triangular pores, is a promising candidate for membrane applications.
• Developing oriented MOF membranes on scalable supports is crucial for industrial gas separation.

Purpose of the Study:

• To synthesize and characterize a highly oriented UiO-66 membrane on α-Al2O3 ceramic supports.
• To investigate the adhesion properties of the UiO-66 layer under various conditions.
• To evaluate the gas separation performance of neat and composite membranes for hydrogen recovery.

Main Methods:

• Fabrication of thin-film UiO-66 membranes with high crystallographic orientation on α-Al2O3.
• Characterization of MOF-support adhesion under demanding conditions.
• Preparation of a multilayer composite membrane by coating UiO-66 with polyimide (Matrimid).
• Gas permeation studies at room temperature using binary gas mixtures.

Main Results:

• Successful preparation of oriented UiO-66 membranes on ceramic supports.
• UiO-66 membranes demonstrated preferential hydrogen (H2) permeation due to its small kinetic diameter.
• Achieved separation factors for H2/CO2, H2/N2, H2/CH4, H2/C2H6, and H2/C3H8 were 5.1, 4.7, 12.9, 22.4, and 28.5, respectively.
• The Matrimid coating enhanced separation performance by introducing a sharp cutoff for larger gas molecules (>3.7 Å).

Conclusions:

• Oriented UiO-66 membranes on ceramic supports are effective for hydrogen separation.
• Composite membranes with a polyimide top layer show improved separation efficiency.
• These advanced membranes hold potential for efficient industrial hydrogen recovery and purification.