Expanding Pore Size of Al-BDC Metal鈥揙rganic Frameworks as a Way to Achieve High Adsorption Selectivity for CO2/CH4 Separation

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• 作者：Tianjun Sun ; Xinyu Ren ; Jiangliang Hu ; Shudong Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 24, 2014
• 年：2014
• 卷：118
• 期：29
• 页码：15630-15639
• 全文大小：481K
• ISSN：1932-7455

文摘

The mesostructured Al-BDC metal鈥搊rganic frameworks (MOFs) with an average pore size of 2.58 nm were prepared via a simplified washing and drying process and applied to the separation of CO₂/CH₄ mixtures. The adsorption equilibrium and thermodynamics of CH₄ and CO₂ were studied in the dynamic processes by the volumetric鈥揷hromatographic and inverse gas chromatographic (IGC) methods. The experiments represent that the Al-BDC MOF with large pore size has a much higher CO₂/CH₄ selectivity of ca. 24 at 303 K in the pressure range 0鈥?.0 MPa and therefore appears to be a good candidate for the separation of CH₄ from CO₂. The initial heats of adsorption of CH₄ and CO₂ on the mesostructured Al-BDC MOFs were determined to be 11.5 and 25.2 kJ mol^鈥? by the IGC method, respectively, which are significantly reduced by ca. 25% compared with that on the microporous Al-BDC MOFs. The results indicate that the expanded pore size not only greatly increases the selectivity of CO₂ adsorption over CH₄ but also reduces the adsorption heat, revealing that it should be the desired method to obtain a satisfactory absorbent for CO₂/CH₄ separation.