Mechanism of Alcohol鈥揥ater Separation in Metal鈥揙rganic Frameworks

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• 作者：Guilherme F. de Lima ; Andreas Mavrandonakis ; Heitor A. de Abreu ; H茅lio A. Duarte ; Thomas Heine
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 28, 2013
• 年：2013
• 卷：117
• 期：8
• 页码：4124-4130
• 全文大小：325K
• 年卷期：v.117,no.8(February 28, 2013)
• ISSN：1932-7455

文摘

The metal鈥搊rganic framework Zn₂(BDC)₂(TED) (1) has been reported to be water-stable and highly selective toward the adsorption of water and alcohols, suggesting the application of this material as a separation membrane for the production of bioethanol. We have studied the adsorption mechanism of water, methanol, ethanol, and dimethylether in this framework by means of density-functional theory with corrections for London dispersion. We show that the combination of the hydrogen bond between the hydroxyl group in ethanol with the oxy group in 1 and the van der Waals interaction between the ethanol alkyl chain with the phenyl ring in 1 is responsible for the preferential adsorption of ethanol over water in the framework. The calculated enthalpy of adsorption for the four compounds in 1 is in excellent agreement with experimental results. We further note that the computational approach has to be chosen with care: It is essential to account for London dispersion interactions, as well as the use of large models, preferably the full periodic structure, to obtain correct adsorption geometries and energies.