Preprint Article Version 1 This version is not peer-reviewed

The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al* Derived from AlH3

Version 1 : Received: 10 April 2019 / Approved: 15 April 2019 / Online: 15 April 2019 (10:53:00 CEST)

A peer-reviewed article of this Preprint also exists.

He, Q.; Zhu, D.; Wu, X.; Dong, D.; Jiang, X.; Xu, M. The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al Derived from AlH3. Metals 2019, 9, 559. He, Q.; Zhu, D.; Wu, X.; Dong, D.; Jiang, X.; Xu, M. The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al Derived from AlH3. Metals 2019, 9, 559.

Journal reference: Metals 2019, 9, 559
DOI: 10.3390/met9050559

Abstract

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by active Al* derived from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H” + B2H6 + H2; (2) the decomposition of "Li-Al-B-H" compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; (5) LiH + Al → LiAl + 1/2H2. And the reversibility of LiBH4/Al* composite is based on equation as follows: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2 and LiAl, etc.) on the surface of Al*. A passivation shell of Al* formed by these products is the kinetic barrier to the dehydrogenation of LiBH4/Al* composite.

Subject Areas

LiBH4; Al; dehydrogenation mechanism; kinetic properties; reversibility

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