Refinement of pore size at sub-angstrom precision in robust metal-organic frameworks for separation of xylenes

• Published in: Nature communications Vol. 11; no. 1; p. 4280
• Main Authors: Li, Xiaolin, Wang, Juehua, Bai, Nannan, Zhang, Xinran, Han, Xue, da Silva, Ivan, Morris, Christopher G, Xu, Shaojun, Wilary, Damian M, Sun, Yinyong, Cheng, Yongqiang, Murray, Claire A, Tang, Chiu C, Frogley, Mark D, Cinque, Gianfelice, Lowe, Tristan, Zhang, Haifei, Ramirez-Cuesta, Anibal J, Thomas, K Mark, Bolton, Leslie W, Yang, Sihai, Schröder, Martin
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 27.08.2020; Nature Publishing Group UK; Nature Portfolio
• Subjects: Crystallization; Isomers; Metal-organic frameworks; p-Xylene; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Polymers; Pore size; Porosity; Room temperature; Selectivity; Separation; Spectroscopy; Synchrotron radiation; X-ray diffraction; Xylene
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-17640-4

The demand for xylenes is projected to increase over the coming decades. The separation of xylene isomers, particularly p- and m-xylenes, is vital for the production of numerous polymers and materials. However, current state-of-the-art separation is based upon fractional crystallisation at 220 K which is highly energy intensive. Here, we report the discrimination of xylene isomers via refinement of the pore size in a series of porous metal-organic frameworks, MFM-300, at sub-angstrom precision leading to the optimal kinetic separation of all three xylene isomers at room temperature. The exceptional performance of MFM-300 for xylene separation is confirmed by dynamic ternary breakthrough experiments. In-depth structural and vibrational investigations using synchrotron X-ray diffraction and terahertz spectroscopy define the underlying host-guest interactions that give rise to the observed selectivity (p-xylene < o-xylene < m-xylene) and separation factors of 4.6-18 for p- and m-xylenes.