Reaction Mechanisms in the Li3AlH6/LiBH4 and Al/LiBH4 Systems for Reversible Hydrogen Storage. Part 2: Solid-State NMR Studies

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• 作者：Young Joon Choi ; Jun Lu ; Hong Yong Sohn ; Zhigang Zak Fang ; Chul Kim ; Robert C. Bowman ; Jr. ; Son-Jong Hwang
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 7, 2011
• 年：2011
• 卷：115
• 期：13
• 页码：6048-6056
• 全文大小：986K
• 年卷期：v.115,no.13(April 7, 2011)
• ISSN：1932-7455

文摘

In Part 1, the promising hydrogen storage properties of the combined systems of Li₃AlH₆/LiBH₄ and Al/LiBH₄, exhibiting the favorable formation of AlB₂ during dehydrogenation, were presented based on TGA and XRD analyses. The present Part 2 describes the characterization of the intermediate and final products of the dehydrogenation and rehydrogenation of the above systems by multinuclear solid-state NMR characterization. This work has also verified that the presence of Al resulted in the re-formation of LiBH₄ occurring at a much lower temperature and H₂ pressure, under which conditions the dehydrogenation product from LiBH₄ alone does not show any degree of rehydrogenation. NMR studies mainly identified various reaction intermediates for LiBH₄ dehydrogenation/rehydrogenation reactions. Unlike the XRD studies, the AlB₂ formation, in particular, could not be unambiguously confirmed by NMR. ²⁷Al NMR showed that aluminum was mainly involved in various Li鈥擜l alloy formations. The catalytic role of Al in the LiBH₄ hydrogen storage reactivity could be achieved by a reversible cycle of the Al + LiH 鈫?LiAl + 1/2H₂ reaction.