Thermodynamics of Methane Adsorption on Copper HKUST-1 at Low Pressure

Di Wu, Xiaofeng Guo, Hui Sun, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

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. 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-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.

Original languageEnglish (US)
Pages (from-to)2439-2443
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume6
Issue number13
DOIs
StatePublished - Jun 11 2015
Externally publishedYes

Keywords

  • direct gas adsorption calorimetry
  • natural gas storage
  • thermodynamics
  • zero coverage enthalpy of adsorption

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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