Hydrogen Desorption Properties of LiBH4/xLiAlH4 (x = 0.5, 1, 2) Composites

A detailed analysis of the dehydrogenation mechanism of LiBH4/xLiAlH4 (x = 0.5, 1, 2) composites was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD) and scanning electronic microscopy (SEM), along with kinetic i...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2019-05, Vol.24 (10), p.1861
Main Authors: He, Qing, Zhu, Dongdong, Wu, Xiaocheng, Dong, Duo, Xu, Meng, Tong, Zhaofei
Format: Article
Language:English
Subjects:
activation energy
Calorimetry
Clean technology
Composite materials
Dehydrogenation
Differential scanning calorimetry
Free surfaces
Hydrogen
hydrogen storage materials
LiBH4LiAlH4
Lithium aluminum hydrides
Raw materials
Spectral analysis
Temperature
Thermogravimetric analysis
Thermogravimetry
X ray powder diffraction
X-ray diffraction
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Summary:A detailed analysis of the dehydrogenation mechanism of LiBH4/xLiAlH4 (x = 0.5, 1, 2) composites was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD) and scanning electronic microscopy (SEM), along with kinetic investigations using a Sievert-type apparatus. The results show that the dehydrogenation pathway of LiBH4/xLiAlH4 had a four-step character. The experimental dehydrogenation amount did not reach the theoretical expectations, because the products such as AlB2 and LiAl formed a passivation layer on the surface of Al and the dehydrogenation reactions associated with Al could not be sufficiently carried out. Kinetic investigations discovered a nonlinear relationship between the activation energy (Ea) of dehydrogenation reactions associated with Al and the ratio x, indicating that the Ea was determined both by the concentration of Al produced by the decomposition of LiAlH4 and the amount of free surface of it. Therefore, the amount of effective contact surface of Al is the rate-determining factor for the overall dehydrogenation of the LiBH4/xLiAlH4 composites.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules24101861