Hydrogen storage properties of nano-CoB/CNTs catalyzed MgH2
Hydrogen storage properties of nano-CoB/CNTs catalyzed MgH2
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纳米CoB/CNTs催化MgH2的储氢性能
DOI：
10.1016/j.jallcom.2017.11.047
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发表时间：
2018-02-25
影响因子：
6.2
通讯作者：
Yan, Mi
中科院分区：
文献类型：
--
作者：
Gao, Shichao;Liu, Haizhen;Yan, Mi
以CoCl 2、NaBH 4和CNTs为原料，成功制备了CoB/CNTs纳米复合材料，并将其作为催化剂用于提高MgH 2的储氢性能。采用BET、SEM、XRD等手段对CoB/CNTs催化剂进行了表征。结果表明，CoB/CNTs具有较高的比表面积。掺杂有10wt%CoB/CNT的MgH 2（MgH 2 + 10wt%CoB/CNT）在约214 ℃开始释放氢，并且在约271 ℃达到脱氢峰。这些温度分别比商用MgH 2低166 ℃和135 ℃。添加CoB/CNTs后，MgH 2的放氢/还原动力学也得到了显著改善。MgH 2 +10 wt% CoB/CNTs在300 ℃下表现出优异的等温氢脱附动力学。它可以在大约19分钟内释放约5.5wt%的H-2，并可以在1小时内完全脱氢。最大放氢速率达到22.9wt%H-2/h，是商品MgH 2的572倍。通过Kissinger图测量的MgH 2 + 10wt%CoB/CNTs的氢脱附活化能估计为89.1 kJ/mol，与商业MgH 2相比降低了119.4 kJ/mol。此外，MgH 2 + 10wt%CoB/CNTs的吸氢性能也非常优异，在300 ℃、5 MPa H2下，20 s内吸氢量可达90%。并对催化机理进行了讨论。(C)2017 Elsevier B. V.版权所有。
With CoCl2, NaBH4 and CNTs as the starting materials, the CoB/CNTs nanocomposites were successfully prepared and used as catalysts to improve the hydrogen storage properties of MgH2. CoB/CNTs catalysts were characterized by BET, SEM, and XRD. The results show that CoB/CNTs possesses high specific surface area. MgH2 doped with 10 wt% CoB/CNTs (MgH2+10 wt% CoB/CNTs) starts to release hydrogen at about 214 degrees C, and reaches a dehydrogenation peak at about 271 degrees C. These temperatures are 166 degrees C and 135 degrees C lower than that of commercial MgH2. The dehydriding/rehydriding kinetics of MgH2 are also remarkably improved by addition of CoB/CNTs. MgH2+10 wt% CoB/CNTs exhibits excellent isothermal hydrogen desorption kinetics at 300 degrees C. It can release around 5.5 wt% H-2 within approximately 19 min, and can fully dehydride within 1 h. The maximum dehydridng rate reaches 22.9 wt% H-2/h, which is 572 times faster than that of commercial MgH2. The activation energy of hydrogen desorption measured by Kis-singer plot is estimated to be 89.1 kJ/mol for MgH2+10 wt% CoB/CNTs, which is reduced by 119.4 kJ/mol as compared to commercial MgH2. Moreover, The fully dehydrided MgH2+10 wt% CoB/CNTs product also shows excellent rehydriding properties, it can absorb up to 90% of hydrogen capacity within 20 s at 300 degrees C and 5 MPa H-2. The catalytic mechanism is discussed. (C) 2017 Elsevier B.V. All rights reserved.