Thermodynamics of Hydrogen Adsorption on Metal-Organic Frameworks

✍ Scribed by Prof. Carlos O. Areán; Dr. Sachin Chavan; Carlos P. Cabello; Prof. Edoardo Garrone; Dr. Gemma T. Palomino

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 202 KB
• Volume: 11
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.201000523

✦ Synopsis

Abstract

Interaction between adsorbed hydrogen and the coordinatively unsaturated Mg^2+^ and Co^2+^ cationic centres in Mg‐MOF‐74 and Co‐MOF‐74, respectively, was studied by means of variable‐temperature infrared (VTIR) spectroscopy. Perturbation of the H~2~ 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 Δ__H^0^=−9.4 kJ mol^−1^ and Δ__S__^0^=−120 J mol^−1^ K^−1^, whereas for Co‐MOF‐74 the corresponding values of Δ__H__^0^=−11.2 kJ mol^−1^ and Δ__S__^0^=−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.__