Computational Identification and Experimental Evaluation of Metal–Organic Frameworks for Xylene Enrichment

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• 作者：Jason A. Gee ; Ke Zhang ; Souryadeep Bhattacharyya ; Jason Bentley ; Meha Rungta ; Jeevan S. Abichandani ; David S. Sholl ; Sankar Nair
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：June 9, 2016
• 年：2016
• 卷：120
• 期：22
• 页码：12075-12082
• 全文大小：429K
• 年卷期：0
• ISSN：1932-7455

文摘

We report the computational discovery and experimental evaluation of nanoporous materials targeted at the adsorptive separation of p-xylene from a C₈ aromatics mixture. We first introduce a computational method that is capable of efficiently predicting the p-xylene selectivities and capacities for a large database of porous materials. We then demonstrate the application of this method to screen a database of several thousand metal–organic framework (MOF) structures. Our computational screening methodology predicted that two MOFs with good solvothermal stability and commercially available linkers give comparable performance to the state-of-the-art zeolite BaX currently used in industrial p-xylene separations. The best-performing MOFs are then synthesized, and their xylene separation characteristics are evaluated in detail through breakthrough adsorption experiments and modeling. We find that the selectivities obtained in these materials are higher than that of any MOF previously reported in the literature and in some cases exceed the measured performance of zeolite BaX. In the case of the p-xylene selective material MOF-48, we use calculated free energy profiles to show how the presence of methyl substituents on the linkers allows the inversion of selectivity from the equivalent MOF with no methyl substituents (MIL-47, which is o-xylene selective). This combined computational and experimental methodology is a useful step in the development of MOFs for separation of aromatic hydrocarbons and can also be applied to other chemical separations and other classes of porous materials as long as the appropriate intermolecular force fields are available.