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In Situ Converted High-Loading Membranes With Molecularly Dispersed Porous Organic Cages for Superior CO2/N2
Liting Yu1, Jia Pang1, Yanxi Wu1
1Shandong Key Laboratory of Intelligent Energy Materials, School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, China.
Angewandte Chemie (International Ed. in English)
|May 22, 2026
Summary
A novel in situ cage conversion strategy creates solid-solution membranes using porous organic cages (POCs). This method enhances CO2/N2 separation performance, exceeding previous benchmarks for POC-based membranes.
Area of Science:
- Materials Science
- Chemical Engineering
- Membrane Technology
Background:
- Porous organic cages (POCs) show promise for gas separation membranes due to their tunable pores.
- Challenges remain in achieving high POC loading and uniform dispersion within membranes.
- Existing methods struggle to balance high loading with molecular-level distribution.
Purpose of the Study:
- To develop a new strategy for creating highly dispersed POCs within polymer matrices.
- To enhance the gas separation performance of mixed-matrix membranes.
- To overcome limitations of current POC-based membrane fabrication.
Main Methods:
- Synthesis of a soluble, nonporous cage (RCC3) via reduction.
- Homogeneous dispersion of RCC3 in a PIM-1 polymer matrix to form a membrane.
- In situ conversion of RCC3 to a rigid, porous cage (FT-RCC3) using paraformaldehyde within the membrane.
- Gas permeation testing for CO2/N2 separation.
Main Results:
- A solid-solution membrane with molecularly dispersed, rigid porous FT-RCC3 cages was successfully fabricated.
- The highest reported loading (26.6 wt%) of POCs in a mixed-matrix membrane was achieved.
- The FT-RCC3 membrane exhibited exceptional CO2 permeability (9321 Barrer) and CO2/N2 selectivity (68.9).
- Performance significantly surpassed the 2019 upper bound for membranes and improved upon pristine PIM-1 and non-converted RCC3/PIM-1 membranes.
Conclusions:
- The in situ cage conversion strategy is effective for creating high-performance POC-based gas separation membranes.
- This approach enables high loading and molecular dispersion, overcoming previous limitations.
- The developed FT-RCC3/PIM-1 membrane represents a significant advancement in CO2/N2 separation technology.
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