Effects of different carbon materials on MgH2 decomposition
Effects of different carbon materials on MgH2 decomposition
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DOI：
10.1016/j.carbon.2007.10.033
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发表时间：
2008-01-01
期刊：
影响因子：
10.9
通讯作者：
Linares-Solano, A.
中科院分区：
文献类型：
--
作者：
Lillo-Rodenas, M. A.;Guo, Z. X.;Linares-Solano, A.
研究了选定的 MgH2 和碳材料混合物的氢吸附特性，包括石墨、活性炭、多壁碳纳米管 (MWCNT)、碳纳米纤维 (CNF) 和活性碳纤维。这种碳材料的引入降低了MgH2的分解温度。在涉及 CNF 和 MWCNT 的混合物中取得了最佳结果，其中含有从原始合成中继承的金属杂质，特别是镍和铁。与简单研磨的 360 摄氏度相比，MgH2 分解的峰值温度分别降低至 322 摄氏度和 341 摄氏度。镁氢。 MgH2 的分解动力学得到了显着改善，特别是在添加 CNF 后。添加 5 wt.% CNF 后，在 300 摄氏度下，MgH2 分解可在 20 分钟内完成，而简单研磨的 MgH2 则需要 240 分钟。即使在几次氢化-脱氢循环之后，仍保持改进的动力学。 X射线衍射和透射电子显微镜显示，循环后发生了一些结构变化：MgH2相的粒径增大，镁相和碳相分离，表明MgH2的分解温度与其结构之间存在明确的关系。研究还表明，碳材料的存在可以防止 MgH2 颗粒的生长，从而增强其分解。 (c) 2007 Elsevier Ltd. 保留所有权利。
Hydrogen sorption properties were investigated for selected mixtures of MgH2 and carbon materials, including graphite, activated carbon, multi-walled carbon nanotubes (MWCNTs), carbon nanofibres (CNFs) and activated carbon fibres. The introduction of such carbon materials decreases the decomposition temperature of MgH2. The best results were achieved in the mixtures involving CNFs and MWCNTs, with metallic impurities, particularly nickel and iron, inherited from the original synthesis. The peak temperatures of MgH2 decomposition were reduced to 322 and 341 degrees C, respectively, compared with 360 degrees C for simply milled. MgH2. Substantial improvement in the decomposition kinetics of MgH2 was achieved, particularly with CNF additions. The MgH2 decomposition was completed within 20 min at 300 degrees C with a 5 wt.% CNF addition, compared to 240 min for simply milled MgH2. The improved kinetics was maintained even after several hydriding-dehydriding cycles. X-ray diffraction and transmission electron microscopy reveal that some structural changes occur after cycling: there is an increase in particle size of the MgH2 phase, with separation between the magnesium and carbon phases, indicating a clear relationship between the decomposition temperature of MgH2 and its structure. It has also been shown that the presence of carbon materials prevents MgH2 particle growth which, in turn, enhances its decomposition. (c) 2007 Elsevier Ltd. All rights reserved.