Asymmetric Pore Windows in Pillar-Layered Metal-Organic Framework Membranes for H₂/CO₂ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Developing advanced membranes for gas separation is crucial for industrial processes.
• Metal-organic frameworks (MOFs) offer tunable pore structures for selective molecular sieving.
• Pillar-layered MOFs present unique architectures for membrane applications.

Purpose of the Study:

• To fabricate a novel ultramicroporous pillar-layered MOF membrane (Ni-LAP-NH2) for high-performance gas separation.
• To investigate the effect of incorporating amino functional groups on membrane separation properties.
• To evaluate the potential of the fabricated membrane for industrial hydrogen purification.

Main Methods:

• Fabrication of Ni-LAP-NH2 membranes on porous α-Al2O3 tubes using isostructural Ni-LAP crystals as seeds.
• Modification of the pillar-layered ligand from pyrazine (Pz) to aminopyrazine (Pz-NH2) to introduce amino side groups.
• Characterization of membrane performance using H2/CO2 separation tests under optimal conditions.

Main Results:

• The Ni-LAP-NH2 membrane exhibited excellent H2/CO2 separation performance, with a separation factor of 41.7.
• High H2 permeance of 9.08 × 10-8 mol·m-2·s-1·Pa-1 was achieved, indicating efficient gas transport.
• The amino side group induced steric hindrance and adsorption affinity, synergistically enhancing CO2 delay.

Conclusions:

• The developed Ni-LAP-NH2 MOF membranes demonstrate significant potential for industrial H2 purification due to their tunable pore structure and stability.
• The strategy of introducing functional groups into pillar-layered MOFs is effective for tailoring molecular sieving abilities.
• This work provides an effective approach for designing advanced MOF membranes for targeted gas separations.