Metal borohydrides as hydrogen storage materials: The study of the thermal decomposition of Al(BH4)3

INOR 86

Douglas A Knight, knightda@ornl.gov, Gilbert M. Brown, browngm1@ornl.gov, Robert Smithwick III, and Ralph Ilgner. Chemical Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6119
Aluminum tris(tetrahydroborane), Al(BH4)3, is being studied to determine if this compound can be used as reversible hydrogen storage material. The temperature dependent product distribution of the thermal decomposition of Al(BH4)3 indicates that the release of diborane from this material is a crucial first step in this process. The diborane appears to undergo further thermal decomposition leading to the release of the molecular hydrogen. An equilibrium was observed to be established between Al(BH4)3 and the hydrogen-bridged Al2H2(BH4)4 dimer at lower temperatures, suggesting one possible route for reversibility in this material's hydrogen storage capabilities. The pyrolysis of the Al(BH4)3 is studied at temperatures up to 400º C with the material and products characterized by powder XRD, FT-IR, NMR, and mass spectroscopy; and elemental analysis of select products by ICP atomic emission.