Thermodynamics of hydrogen storage: Equilibrium study of the LOHC system indole/octahydroindole

Sergey V. Vostrikov*, Maria E. Konnova, Vladimir V. Turovtzev, Karsten Müller, Sergey P. Verevkin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Reversible hydrogenation of indole or its derivatives could be an attractive hydrogen storage technology. Particularly for hydrogen release, the reaction equilibrium is a crucial factor determining the conditions in the respective process. This study is supposed to provide inside into this reaction equilibrium. An experimental study of the chemical equilibrium of hydrogenation/dehydrogenation reactions was performed in a stirred autoclave with n–hexane as a solvent by varying the temperature, pressure, and hydrogen:feedstock ratio. Based on the compositions in stationary state, equilibrium constants have been derived. Furthermore, thermodynamic properties of chemical reactions were derived from the equilibrium constant temperature dependence. This temperature dependence reveals that the enthalpy of reaction for the dehydrogenation of the six-membered ring is significantly larger than in the nitrogen containing five-membered ring. To get deeper insides, the molar enthalpies of formation of intermediates have been calculated using high-level quantum chemical methods. This analysis supports the observations from the equilibrium reactions. Additionally, it show that the heat of reaction for the endothermal dehydrogenation is about 2 kJ mol (H2)–1 smaller in the liquid phase than in case of a gas phase reaction.

Original languageEnglish
Article number127025
Number of pages12
JournalFuel
Volume335
DOIs
Publication statusPublished - 1 Mar 2023
Externally publishedYes

Keywords

  • Chemical equilibrium
  • Enthalpy of reaction
  • Entropy change of reaction
  • Quantum-chemical calculations

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