Titanium catalyzed solid-state transformations in LiAlH4 during high-energy ball-milling

Mechanical processing of polycrystalline LiAlH4 in the presence of titanium- and iron-based catalysts induces the transformation of LiAlH4 into Li(3)AIH(6), Al and H-2 at room temperature. Several catalysts were tested and it was established that their activity gradually decreases from TiCl4 to Fe in the series TiCl4 > Al3Ti much greater than Al22Fe3Ti8 > Al3Fe > Fe. The high catalytic activity of TiCl4 has been attributed to microcrystalline intermetallic Al3Ti, which rapidly forms in situ from TiCl4 and LiAlH4 during mechanical processing and then acts as a heterogeneous dehydrogenation catalyst. (C) 2001 Elsevier Science BY All rights reserved.