Dehydrogenation Improvement of LiAlH4 Catalyzed by Fe2O3 and Co2O3 Nanoparticles

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• 作者：Ziliang Li ; Ping Li ; Qi Wan ; Fuqiang Zhai ; Zhiwei Liu ; Kuifei Zhao ; Ling Wang ; Shaoyuan L眉 ; Liang Zou ; Xuanhui Qu ; Alex A. Volinsky
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：September 12, 2013
• 年：2013
• 卷：117
• 期：36
• 页码：18343-18352
• 全文大小：643K
• 年卷期：v.117,no.36(September 12, 2013)
• ISSN：1932-7455

文摘

The catalytic effect of two nanoscale transition metal oxides, Fe₂O₃ and Co₂O₃, as additives on the dehydrogenation properties of LiAlH₄ after milling are investigated. The onset dehydrogenation temperature for the 5 mol % Fe₂O₃-doped and 5 mol % Co₂O₃-doped samples are 85 and 79 掳C lower for the first-stage and 60 and 45 掳C lower for the second-stage, respectively, compared with the as-received LiAlH₄. The isothermal dehydriding kinetics reveals that the 5 mol % Fe₂O₃-doped sample can release about 7.1 wt % hydrogen in 70 min at 120 掳C, whereas as-received LiAlH₄ only releases 0.3 wt % hydrogen under the same conditions. From differential scanning calorimetry (DSC) and Kissinger desorption kinetics analyses, the apparent activation energies (E_a) of the 5 mol % Fe₂O₃-doped sample are 54.2 and 86.4 kJ/mol for the first two dehydrogenation stages, resulting in decreases of 42.8 and 50% compared with those of as-received LiAlH₄, respectively, which are considerably lowered compared with LiAlH₄ doped with other reported catalysts calculated by Kissinger method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) analyses demonstrate that these finely dispersed Li₂Fe_2.4O_4.6, Fe_0.957O, and various Co oxides contribute to kinetics improvement by serving as active sites for nucleation and growth of dehydrogenated products.