Controlling the Dehydrogenation Reaction toward Reversibility of the LiBH4鈥揅a(BH4)2 Eutectic System

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• 作者：Yigang Yan ; Arndt Remhof ; Philippe Mauron ; Daniel Rentsch ; Zbigniew 艁odziana ; Young-Su Lee ; Hyun-Sook Lee ; Young Whan Cho ; Andreas Z眉ttel
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：May 2, 2013
• 年：2013
• 卷：117
• 期：17
• 页码：8878-8886
• 全文大小：429K
• 年卷期：v.117,no.17(May 2, 2013)
• ISSN：1932-7455

文摘

Controlling the dehydrogenation process in a suitable reaction route by choosing the appropriate reaction conditions is crucial for a hydrogen storage system. The dehydrogenation process of the eutectic 0.68LiBH<sub>4sub>鈥?.32Ca(BH<sub>4sub>)<sub>2sub> mixture was investigated by dynamic pressure鈥揷omposition isotherms, X-ray diffraction, and solid-state nuclear magnetic resonance in order to determine the optimal reaction route for the dehydrogenation and to improve the hydrogen absorption reaction. In a temperature range from 330 to 450 掳C, the LiBH<sub>4sub>鈥揅a(BH<sub>4sub>)<sub>2sub> mixture decomposes in two major steps. First, Ca(BH<sub>4sub>)<sub>2sub> decomposes into CaH<sub>2sub>, CaB<sub>6sub>, CaB<sub>12sub>H<sub>12sub>, H<sub>2sub>, and probably amorphous boron. Second, CaH<sub>2sub> reacts with LiBH<sub>4sub> to CaB<sub>6sub>, LiH, and H<sub>2sub>. Li<sub>2sub>B<sub>12sub>H<sub>12sub> has been identified as a byproduct. It was observed that the lower dehydrogenation temperature, the more CaB<sub>6sub> and the less [B<sub>12sub>H<sub>12sub>]<sup>2鈥?/sup> containing phases are present in the final dehydrogenation products, resulting in improved absorption performance. The temperature dependence is discussed, providing instructions to improve reversibility for potential applications and new insights into the hydrogen sorption mechanism of metal borohydrides.