Investigation on kinetics mechanism of hydrogen absorption in the La2Mg17-based composites
Investigation on kinetics mechanism of hydrogen absorption in the La2Mg17-based composites
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DOI：
10.1016/j.ijhydene.2008.12.040
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发表时间：
2009-02-01
影响因子：
7.2
通讯作者：
Xu, Kuang-Di
中科院分区：
文献类型：
--
作者：
Liu, Jing;Zhang, Xu;Xu, Kuang-Di
采用一种新的吸氢动力学模型研究了La_2Mg_（17）基复合材料的吸氢动力学机理。结果表明，不同的制备条件导致吸氢过程中不同的速率控制步骤。对于熔融法合成的La_2Mg_（17）-LaNi_（5）复合材料，氢原子的表面穿透是速率控制步骤，添加剂（LaNi_（5））不改变氢原子的表面穿透速率。机械球磨可以改变La 2 Mg 17-LaNi 5复合材料中氢化反应的速率限制步骤，使氢化反应的速率限制步骤由表面渗透转变为氢在氢化物层中的扩散。随着球磨强度的提高，La1.8Ca0.2Mg14Ni3合金中的速率控制步骤由表面穿透转变为扩散。此外，还利用该模型计算了La_2Mg_（17 - 20wt%LaNi_5）和La_（1.8）Ca_（0.2）Mg_（14）Ni_3的吸氢活化能。(c)2008年国际氢能协会。由爱思唯尔有限公司出版。保留所有权利。
A new model has been successfully used to investigate the hydrogen absorption kinetics mechanism of La2Mg17-based composites. The results indicate that different preparation conditions lead to different rate-controlling steps during hydrogen absorption process. For La2Mg17-LaNi5 composite synthesized by the method of melting, the rate-controlling step is the surface penetration of hydrogen atoms, which does not change by addition agent (LaNi5). However, mechanical milling can change the rate-limiting steps of hydriding reaction in the La2Mg17-LaNi5 composite from surface penetration to diffusion of hydrogen in the hydride layer. With the enhancement of milling intensity, the rate-controlling step in La1.8Ca0.2Mg14Ni3 alloy changes from surface penetration to diffusion. in addition, the activation energies of hydrogen absorption for La2Mg17-20wt%LaNi5 and La1.8Ca0.2Mg14Ni3 are obtained by this model. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.