A step forward to the dehydrogenation reversibility of amine-borane adducts by coupling sodium and hydrocarbon groups

• Reactive milling of BH3NH2CH2CH2NH2BH3 (EDAB) and NaH yields a novel amine-borane adduct.
• This adduct releases 8 wt.% of pure hydrogen below 400 °C without producing foaming.
• Sodium addition to EDAB significantly modifies hydrogen desorption enthalpies.
• This result opens promising perspectives towards a reversible hydrogenation behavior.

Mechanochemistry has played an important role in the synthesis of many novel compounds, in particular within the field of materials for solid state hydrogen storage applications. This work investigates reactive milling of ethane 1,2-di-amineborane (EDAB) and sodium hydride which yields the evolution of one equivalent of hydrogen and the formation of a novel compound (named NaEDAB) as evidenced by X-ray diffraction analyses. We postulate for this compound the chemical formula NaB2C2N2H13. The thermolysis of NaEDAB below 400 °C releases about 8 wt.% pure hydrogen, without producing foaming. Moreover, sodium addition significantly modifies hydrogen desorption enthalpies, giving rise to milder exothermic H2 release at moderate temperatures with respect to neat EDAB, as well as an endothermic desorption process at higher temperature. This result opens novel and promising perspectives towards the reversible hydrogenation of these compounds.

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