Thermodynamics of Hydrogen Adsorption on Metal‐Organic Frameworks |
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| Authors: | Prof Carlos O Areán Dr Sachin Chavan Carlos P Cabello Prof Edoardo Garrone Dr Gemma T Palomino |
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| Institution: | 1. Department of Inorganic, Physical and Material Chemistry, NIS Center of Excellence and INSTM Unità di Torino, University of Torino, 10135 Torino (Italy);2. On leave from Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca (Spain);3. Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca (Spain), Fax: (34)?971‐173426;4. Department of Materials Science and Chemical Engineering;5. INSTM Unità di Torino Politecnico, Politecnico di Torino, 10129 Turin (Italy) |
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| Abstract: | Interaction between adsorbed hydrogen and the coordinatively unsaturated Mg2+ and Co2+ cationic centres in Mg‐MOF‐74 and Co‐MOF‐74, respectively, was studied by means of variable‐temperature infrared (VTIR) spectroscopy. Perturbation of the H2 molecule by the cationic adsorbing centre renders the H? H stretching mode IR‐active at 4088 and 4043 cm?1 for Mg‐MOF‐74 and Co‐MOF‐74, respectively. Simultaneous measurement of integrated IR absorbance and hydrogen equilibrium pressure for spectra taken over the temperature range of 79–95 K allowed standard adsorption enthalpy and entropy to be determined. Mg‐MOF‐74 showed ΔH0=?9.4 kJ mol?1 and ΔS0=?120 J mol?1 K?1, whereas for Co‐MOF‐74 the corresponding values of ΔH0=?11.2 kJ mol?1 and ΔS0=?130 J mol?1 K?1 were obtained. The observed positive correlation between standard adsorption enthalpy and entropy is discussed in the broader context of corresponding data for hydrogen adsorption on cation‐exchanged zeolites, with a focus on the resulting implications for hydrogen storage and delivering. |
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| Keywords: | adsorption hydrogen ir spectroscopy metal‐organic frameworks thermodynamics |
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