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Title: Thermodynamics of methane adsorption on copper HKUST-1 at low pressure

Metal–organic 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 °C at low pressures (below 1 bar). In this pressure region, the CH₄–CH₄ intermolecular interactions are minimized and the energetics solely reflects the CH₄–MOF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of -21.1 ± 1.1 kJ/mol CH₄ independent of coverage. The 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–HKUST-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.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of California, Davis, CA (United States)
  2. Univ. of California, Davis, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. East China Univ. of Science and Technology, Shanghai (China)
Publication Date:
OSTI Identifier:
1221609
Report Number(s):
LA-UR--15-24040
Journal ID: ISSN 1948-7185
Grant/Contract Number:
201308310077; 21201063; 20110074120020; FG02-05ER15667; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 6; Journal Issue: 13; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY natural gas storage; direct gas adsorption calorimetry; thermodynamics; zero coverage enthalpy of adsorption