Ammonia suppression during decomposition of sodium amide by the addition of metal hydride
Ammonia suppression during decomposition of sodium amide by the addition of metal hydride
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DOI：
10.1016/j.ijhydene.2017.02.049
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发表时间：
2017-08-31
影响因子：
7.2
通讯作者：
Kojima, Yoshitsugu
中科院分区：
文献类型：
--
作者：
Jain, Ankur;Kumar, Sanjay;Kojima, Yoshitsugu
NaNH2的分解已有报道，主要分解为NaH、N-2和H-2。除N-2和H-2外，还生产氨。就我们所知，关于碱氢化物对NaNH2影响的零星报告在文献中很少。因此，我们选择NaNH_2-MH(M=Li，Na，K，Mg，Ca)体系作为研究对象。由于NaNH2 NaH是由于相同的阳离子而形成的最简单的组合，因此用透射电子显微镜(TEM)对其反应机理进行了测试。观察到整个反应过程遵循与LiNH2 LiH体系相似的NH3催化反应。氨化钠首先分解成金属钠和NH3，然后生成NH3，与添加的NaH反应生成NaNH2，释放出H-2。这一过程一直持续到NaH的消耗，从而在很大程度上抑制了NH3的析出。研究进一步扩展到其他金属氢化物，发现其他金属氢化物如LiH、KH、MgH和CaH_2的加入也有效地抑制了NH3的析出。对所有的酰胺氢化物体系的详细反应机理进行了解释。观察到，分解是通过形成双阳离子酰胺的中间步骤进行的。(C)2017年氢能源出版有限责任公司。爱思唯尔有限公司出版。保留所有权利。
The decomposition of NaNH2 has been reported, mainly decomposing into NaH, N-2 and H-2. Ammonia is also produced in addition to N-2 and H-2. To the best of our knowledge, very few scattered reports on the effect of alkali hydrides on NaNH2 exist in literature. Thus, we choose NaNH2 MH (M = Li, Na, K, Mg, Ca) system to be investigated in detail. Since NaNH2 NaH is the simplest combination due to same cation, it was tested for the establishment of reaction mechanism using transmission electron microscopy (TEM). It is observed that the entire process follows NH3 mediated reaction similar to LiNH2 LiH system. Sodium amide first decompose into Na metal and NH3, then generated NH3 reacted with added NaH to form NaNH2 and release H-2. This process continues until the consumption of NaH, thus suppresses NH3 evolution to a great extent. The investigation has been extended further to the other metal hydrides and it is found that the addition of other metal hydride i.e. LiH, KH, MgH2, and CaH2 have also effectively suppressed the NH3 evolution. The detailed reaction mechanism has been elucidated for all the amide hydride systems. It is observed that the decomposition takes place through an intermediate step of double-cation amide formation. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.