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A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions
Published on: August 17, 2016
Novel sodium aluminium borohydride containing the complex anion [Al(BH4,Cl)4]-
Inge Lindemann1, Roger Domènech Ferrer, Lothar Dunsch
1Functional Materials and Hydrides Group (Dept. 21), IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany.
Abstract:
The synthesis of a novel alkali-metal aluminium borohydride NaAl(BH4)xCl4-x from NaBH4 and AlCl3 using a solid state metathesis reaction is described. Structure determination was carried out using synchrotron powder diffraction data and vibrational spectroscopy. An orthorhombic structure (space group Pmn2(1)) is formed which contains Na+ cations and complex [Al(BH4,Cl)4]- anions. Due to the high chlorine content (1 < or = x < or = 1.43) the hydrogen density of the borohydride is only between 2.3 and 3.5 wt.% H2 in contrast to the expected 14.6 wt.% for chlorine free NaAl(BH4)4. The decomposition of NaAl(BH4)xCl4-x is observed in the target range for desorption at about 90 degrees C by differential scanning calorimetry (DSC), in situ Raman spectroscopy and synchrotron powder X-ray diffraction. Thermogravimetric analysis (TG) shows extensive mass loss indicating the loss of H2 and B2H6 at about 90 degrees C followed by extensive weight loss in the form of chloride evaporation.
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