Abstract
Mixed-matrix membranes (MMMs) with high chain packing density by incorporating soluble macrocycle compounds represent a promising class of materials for gas separation. However, achieving the ultra-high selectivity (He/CH4 > 1000) for helium extraction from natural gas with ultra-low helium content remains a formidable challenge, especially for Matrimid membranes, which are commercially available but exhibit relatively low permeability and moderate selectivity. Herein, the cyclic Cyclen with specific intra-ring dimensions was incorporated into Matrimid as a pore-structure modifier to enhance the He/CH4 selectivity. The strong hydrogen bonding interactions between Cyclen and Matrimid chains induced a denser chain stacking and modulation of the interchain gap structures, which enables rapid mass transfer of small He gas molecules while hindering the diffusion of large CH4 gas molecules across the membrane, thereby significantly enhanced He/CH4 molecular sieving capacity. Molecular dynamics simulations indicate that the MMMs prepared using Cyclen as a filler exhibited tunable microporous and more efficient He transport channels. Notably, the He/CH4 selectivity reached up to an impressive value of 6788 after physical aging for 110 days, which outperformed almost all reported polymer-based membranes and was even comparable to that of some advanced carbon molecular sieve membranes.
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The authors declare that all the data supporting the findings of this study are available within the article (and Supplementary Information files). Additional data are available from the corresponding author upon request. Source data are provided with this paper.
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Acknowledgements
The authors sincerely acknowledge the financial support provided by the National Key Research and Development Program of China (2025YFF0522700 [J.L.]), the National Natural Science Foundation of China (22478371 [J.L.]), and the Students’ Innovation and Entrepreneurship Foundation of USTC (XY2024C008 [W.H.], CY2025C002B [W.H.]). This work was partially carried out at the Instrument Center for Physical Science, University of Science and Technology of China.
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Wen He: Designed the research and conceived the idea, carried out laboratory research, wrote draft of manuscript. Xiangzeng Wang: Contributed to writing of theory section of manuscript. Jian Guan: Conducted the XPS measurements. Quansheng Liang: Helped with the graph drawing. Ji Ma: Conducted the SEM measurements. Ying Liu: Commented on the manuscript. Hongjun Zhang: Discussed the results and commented on the manuscript. Chunwei Zhang: Discussed the results. Jiangtao Liu: Optimized the research and conceived the idea, led the analysis, discussed the results and commented on the manuscript. All authors analyzed and discussed the results.
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He, W., Wang, X., Guan, J. et al. Mixed-matrix membranes with molecular recognition windows for selective helium extraction from natural gas. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69768-4
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DOI: https://doi.org/10.1038/s41467-026-69768-4
