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 Li3AlH6, Al and H2 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≫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.