Heat-driven molecule gatekeepers in MOF membrane for record-high H₂ selectivity

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• High-temperature hydrogen/carbon dioxide (H₂/CO₂) separation is crucial for sustainable energy technologies.
• Conventional molecular sieve membranes suffer from reduced selectivity at high temperatures due to CO₂ diffusion activation.

Purpose of the Study:

• To develop a robust membrane for high-temperature H₂/CO₂ separation.
• To overcome the selectivity limitations of traditional molecular sieve membranes at elevated temperatures.

Main Methods:

• Incorporation of molecule gatekeepers within the cavities of a metal-organic framework membrane.
• Utilizing ab initio calculations and in situ characterizations to analyze membrane behavior.
• Investigating the dynamic reshaping of sieving apertures under varying temperatures.

Main Results:

• Molecule gatekeepers dynamically adjust membrane apertures at high temperatures, becoming tighter for CO₂.
• The H₂/CO₂ selectivity was improved by an order of magnitude at 513 K compared to ambient conditions.
• Gatekeeper-modified membranes demonstrated temperature-dependent aperture regulation.

Conclusions:

• Molecule gatekeepers offer a viable strategy to enhance the high-temperature performance of molecular sieve membranes.
• This approach addresses the challenge of CO₂ diffusion activation, enabling reliable H₂/CO₂ separation.
• The dynamic aperture control mechanism provides a pathway for designing advanced separation membranes for sustainable energy applications.