In Situ Synchrotron X-ray Diffraction Studies of Hydrogen-Desorption Properties of 2LiBH4–Mg2FeH6 Composite

Adding a secondary complex metal hydride can either kinetically or thermodynamically facilitate dehydrogenation reactions. Adding Mg2FeH6 to LiBH4 is energetically favoured, since FeB and MgB2 are formed as stable intermediate compounds during dehydrogenation reactions. Such “hydride destabilisation...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2021-08, Vol.26 (16), p.4853
Main Authors: Ghaani, Mohammad R., Catti, Michele, English, Niall J.
Format: Article
Language:English
Subjects:
Alloys
Decomposition
Decomposition reactions
dehydriding reaction
Dehydrogenation
Heat
High temperature
hydride composite
Hydrogen
hydrogen storage
Hydrogenation
Investigations
Low temperature
Magnesium
Magnesium compounds
Metal hydrides
solid–gas reactions
Synchrotron radiation
Synchrotrons
thermodynamic driving force
Vacuum
X-ray diffraction
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Summary:Adding a secondary complex metal hydride can either kinetically or thermodynamically facilitate dehydrogenation reactions. Adding Mg2FeH6 to LiBH4 is energetically favoured, since FeB and MgB2 are formed as stable intermediate compounds during dehydrogenation reactions. Such “hydride destabilisation” enhances H2-release thermodynamics from H2-storage materials. Samples of the LiBH4 and Mg2FeH6 with a 2:1 molar ratio were mixed and decomposed under three different conditions (dynamic decomposition under vacuum, dynamic decomposition under a hydrogen atmosphere, and isothermal decomposition). In situ synchrotron X-ray diffraction results revealed the influence of decomposition conditions on the selected reaction path. Dynamic decomposition of Mg2FeH6–LiBH4 under vacuum, or isothermal decomposition at low temperatures, was found to induce pure decomposition of LiBH4, whilst mixed decomposition of LiBH4 + Mg and formation of MgB2 were achieved via high-temperature isothermal dehydrogenation.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules26164853