Thermodynamics of Methane Adsorption on Copper HKUST-1 at Low Pressure
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- 作者：Di Wu ; Xiaofeng Guo ; Hui Sun ; Alexandra Navrotsky
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2015
- 出版时间：July 2, 2015
- 年：2015
- 卷：6
- 期：13
- 页码：2439-2443
- 全文大小：272K
- ISSN：1948-7185
文摘
Metal鈥搊rganic frameworks (MOFs) can be engineered as natural gas storage materials by tuning the pore structures and surface properties. Here we report the direct measurement of CH4 adsorption enthalpy on a paddlewheel MOF (Cu HKUST-1) using gas adsorption calorimetry at 25 掳C at low pressures (below 1 bar). In this pressure region, the CH4鈥揅H4 intermolecular interactions are minimized and the energetics solely reflects the CH4鈥揗OF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of 鈭?1.1 卤 1.1 kJ/mol CH4 independent of coverage. This calorimetric investigation complements previous computational and crystallographic studies by providing zero coverage enthalpies of CH4 adsorption. The analysis of the new and literature data suggests that in initial stages of adsorption the CH4鈥揌KUST-1 interaction tends to be more sensitive to the pore dimension than to the guest polarizability, suggesting a less specific chemical binding role for the open Cu site.