Asymmetric pore windows in MOF membranes for natural gas valorization

• Published in: Nature (London) Vol. 606; no. 7915; pp. 706 - 712
• Main Authors: Zhou, Sheng, Shekhah, Osama, Ramírez, Adrian, Lyu, Pengbo, Abou-Hamad, Edy, Jia, Jiangtao, Li, Jiantang, Bhatt, Prashant M., Huang, Zhiyuan, Jiang, Hao, Jin, Tian, Maurin, Guillaume, Gascon, Jorge, Eddaoudi, Mohamed
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.06.2022; Nature Publishing Group
• Subjects: 639/301/299/1013; 639/638/298/921; Apertures; Asymmetry; Atoms & subatomic particles; Boiling points; Calorific value; Carbon dioxide; Carbon dioxide removal; Carbon sequestration; Chemical Sciences; Distillation; Economic analysis; Editing; Energy efficiency; Humanities and Social Sciences; Ligands; Membranes; Metal-organic frameworks; Methane; multidisciplinary; Natural gas; Natural gas reserves; Nitrogen; Nitrogen removal; NMR; Nuclear magnetic resonance; Polarizability; Science; Science (multidisciplinary); Selectivity; Zirconium
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-022-04763-5

To use natural gas as a feedstock alternative to coal and oil, its main constituent, methane, needs to be isolated with high purity 1 . In particular, nitrogen dilutes the heating value of natural gas and is, therefore, of prime importance for removal 2 . However, the inertness of nitrogen and its similarities to methane in terms of kinetic size, polarizability and boiling point pose particular challenges for the development of energy-efficient nitrogen-removing processes 3 . Here we report a mixed-linker metal–organic framework (MOF) membrane based on fumarate ( fum ) and mesaconate ( mes ) linkers, Zr- fum 67 - mes 33 - fcu -MOF, with a pore aperture shape specific for effective nitrogen removal from natural gas. The deliberate introduction of asymmetry in the parent trefoil-shaped pore aperture induces a shape irregularity, blocking the transport of tetrahedral methane while allowing linear nitrogen to permeate. Zr- fum 67 - mes 33 - fcu -MOF membranes exhibit record-high nitrogen/methane selectivity and nitrogen permeance under practical pressures up to 50 bar, removing both carbon dioxide and nitrogen from natural gas. Techno-economic analysis shows that our membranes offer the potential to reduce methane purification costs by about 66% for nitrogen rejection and about 73% for simultaneous removal of carbon dioxide and nitrogen, relative to cryogenic distillation and amine-based carbon dioxide capture. A metal–organic framework membrane based on fumarate and mesaconate linkers is shown to have a pore aperture shape that enables efficient and cost-effective removal of nitrogen and carbon dioxide from methane.