Improved Dehydrogenation Properties of Calcium Borohydride Combined with Alkaline-Earth Metal Amides
详细信息 查看全文
- 作者：Hailiang Chu ; Guotao Wu ; Yao Zhang ; Zhitao Xiong ; Jianping Guo ; Teng He ; Ping Chen
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：September 15, 2011
- 年：2011
- 卷：115
- 期：36
- 页码：18035-18041
- 全文大小：943K
- 年卷期：v.115,no.36(September 15, 2011)
- ISSN：1932-7455
文摘
Promotion of dehydrogenation based on the interaction of [BH4]鈭?/sup> and [NH2]鈭?/sup> sources has been demonstrated to be one of the most effective approaches in developing an advanced borohydride/amide hydrogen storage combined system. The Ca(BH4)2鈥?Mg(NH2)2 and Ca(BH4)2鈥?Ca(NH2)2 composites are thereby synthesized in the present work. It is found that the binary combined systems exhibit an onset dehydrogenation temperature of 220 掳C, which is 100 掳C lower than that of pristine Ca(BH4)2. The hydrogen release measurements for Ca(BH4)2鈥?Mg(NH2)2 and Ca(BH4)2鈥?Ca(NH2)2 samples below 480 掳C show desorption amounts of 8.3 and 6.8 wt % hydrogen, respectively. The dehydrogenation of both samples is accompanied by an ammonia emission of <1.4 mol %. The characterizations such as X-ray diffraction and nuclear magnetic resonance on the postdehydrogenated samples indicate that the dehydrogenation reactions are in the pathways of Ca(BH4)2 + 2 Mg(NH2)2 鈫?1/3 [Ca3Mg6(BN2)6] + 8 H2 and Ca(BH4)2 + 2 Ca(NH2)2 鈫?1/3 Ca9(BN2)6 + 8 H2, respectively. Compared with pristine Ca(BH4)2 sample, both possess lower activation energy for dehydrogenation. Further investigation reveals that the interaction of B鈥揌 and N鈥揌 may be one of main driving forces for dehydrogenation of borohydride/amide combined system.