Thermal decomposition of LiAlH_4 chemically mixed with Lithium amide and transition metal chlorides

摘要

Thermogravimetric analysis of LiAlH_4 chemically mixed with different additives is reported for the application of hydrogen storage. Here, we illustrated the dehydrogenation properties of combined LiAlH_4/LiNH_2 (2:1) mixture and LiAlH_4 wet-doped with different transition metals (Sc, Ti, and V) in their chloride forms. Thermal gravimetric analysis of LiAlH_4/LiNH_2 system released ～7.9wt.% of hydrogen in three decomposition steps at temperatures between 75 and 280 ℃ under a heating ramp of 5 ℃ min~(-1). The LiAlH_4 doped with transition metals showed the decrease of decomposition temperature down to 30-40 ℃ for both 1st and 2nd dehydrogenation steps as compared to as-received LiAlH_4. The catalytic activity in lowering the dehydrogenation temperature of LiAlH_4 doped with transition metals increases in the order of pure LiAlH_4 < V < Ti < Sc. The X-ray diffraction analysis, field emission scanning electron microscopy, and Fourier transformation infrared spectroscopy techniques were carried out in support of the thermogravimetric results.