Fast and slow dehydrogenation of ball milled lithium alanate (LiAlH4) catalyzed with manganese chloride (MnCl2) as compared to nanometric nickel catalyst

作者：Varin R A^*; Zbroniec L

来源：Journal of Alloys and Compounds, 2011, 509: S736-S739.

DOI：10.1016/j.jallcom.2010.09.068

• Solid state hydrogen storage
• Hydrogen storage materials
• Lithium alanate (LiAlH4)
• Manganese chloride (MnCl2)
• Ball milling
• X-ray diffraction (XRD)
• Differential scanning calorimetry (DSC)

The results of the studies on the dehydrogenation behavior of the ball milled LiAlH4 catalyzed with 5 wt.% of manganese chloride (MnCl2) are reported. During ball milling for 15 min the LiAlH4 + 5 wt.% MnCl2 nanocomposite releases a miniscule amount of similar to 0.25 wt.% H-2. However, no products of the possible reaction between LiAlH4 and MnCl2 (e.g. LiCl) are observed by X-ray diffraction (XRD). In a DSC test most of LiAlH4 decomposes exothermically to Li3AlH6 in a solid state while a small fraction of retained LiAlH4 melts and decomposes in a liquid state. During dehydrogenation at 100 degrees C under 0.1 MPa H-2 the ball milled LiAlH4 + 5 wt.% MnCl2 nanocomposite is able to desorb similar to 4.6 wt.% H-2 within similar to 30,000 s in a solid state but only in Stage I (reaction: LiAlH4 (solid) -> 1/3Li(3)AlH(6) + 2/3Al + H-2). The apparent activation energy of dehydrogenation for this solid state reaction is equal to similar to 80 kJ/mol as compared to similar to 70 kJ/mol obtained for LiAlH4 + 5 wt.% n-Ni [7]. However, during decomposition at 100 degrees C a chemical reaction occurs between LiAlH4 and MnCl2 producing LiCl and most likely an amorphous Mn metal catalyzing the reaction in Stage I. The ball milled LiAlH4 + 5 wt.% MnCl2 nanocomposite is capable of desorbing substantial quantities of H-2 during long term storage at room temperature (RT; similar to 21 degrees C), 40 and 80 degrees C.

• 出版日期2011-9