A Transferable Model for Adsorption in MOFs with Unsaturated Metal Sites

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• 作者：Christopher Campbell ; Carlos A. Ferreiro-Rangel ; Michael Fischer ; José R. B. Gomes ; Miguel Jorge
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：441-458
• 全文大小：1048K
• ISSN：1932-7455

文摘

The number of newly discovered metal–organic frameworks is growing exponentially. Molecular simulation is becoming increasingly important to screen large databases of structures and identify potential candidates for challenging gas separations, but such efforts rely on the availability of accurate molecular models that can predict adsorption in a wide range of different MOFs. MOFs with coordinatively unsaturated sites (CUS) pose particular problems because standard force fields are unable to describe their specific interactions with certain adsorbates. In this Article, we demonstrate that our previous approach to describe adsorption in open metal sites, based on a combination of classical Monte Carlo simulations and quantum-mechanical Density Functional Theory calculations, is transferable to several Cu-containing MOFs. By fitting the parameters of our model to match adsorption energies of ethylene on HKUST-1 and transferring them to the Cu-paddlewheel units of other MOFs, we obtain predictions in good agreement with experimental adsorption measurements. Where agreement is not as satisfactory, we show that this can be explained by limited accessibility or diffusion through the pore network. For one particular MOF, UMCM-150, we show that separate parameters need to be used for the Cu-trimer unit, for which the interaction energies with ethylene are much lower than those in the Cu-paddlewheel. Overall, our approach demonstrates that the specific CUS interactions in MOFs can be parametrized separately from other interaction types, such as van der Waals, thus opening the way for the development of an accurate and fully transferable force field for this class of materials.