Adsorption of C1鈥揅4 Alcohols in Zeolitic Imidazolate Framework-8: Effects of Force Fields, Atomic Charges, and Framework Flexibility

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• 作者：Kang Zhang ; Liling Zhang ; Jianwen Jiang
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：December 5, 2013
• 年：2013
• 卷：117
• 期：48
• 页码：25628-25635
• 全文大小：403K
• 年卷期：v.117,no.48(December 5, 2013)
• ISSN：1932-7455

文摘

A molecular simulation study is reported for the adsorption of normal alcohols (methanol, ethanol, propanol, and butanol) in zeolitic imidazolate framework-8 (ZIF-8). The effects of force fields, atomic charges, and framework flexibility are systematically examined and compared with experimental data. Among three force fields (UFF, AMBER, and DREIDING), DREIDING has the best agreement with experiment. The atomic charges and framework flexibility are found to have negligible effects. The four alcohols exhibit S-shaped isotherms without hysteresis loop, as attributed to adsorption at different preferential sites. At a low pressure, cluster formation is observed near the organic linker (2-methylimidazolate) in ZIF-8; with increasing pressure, cage-filling occurs in the large sodalite cage. The interaction between alcohol and ZIF-8 framework is enhanced as the chain length of alcohol increases; thus, the isosteric heat of adsorption rises with chain length. The simulation study provides microscopic insight into alcohol adsorption in ZIF-8, which is useful for quantitative understanding of adsorption mechanism in other ZIFs and nanoporous materials.