Mechanochemical synthesis and thermal decomposition of Mg(AlH4)2

Magnesium alanate Mg(AlH4)2 has been synthesized by mechanochemically activated metathesis reaction between NaAlH4 and MgCl2 without solvent, this metathesis reaction proceeded completely. The thermal decomposition behavior of solvent-free Mg(AlH4)2 has been analyzed by TG/MS and DSC. It has been confirmed that Mg(AlH4)2 decomposes in two steps: the first decomposition reaction Mg(AlH4)2 → MgH2 + 2Al + 3H2 is exothermic and starts at about 115 °C. The second one MgH2+2Al→12Al3Mg2+12Al+H2 is endothermic in total and starts at about 240 °C, although the formation reaction of Al3Mg2 (3Al + 2Mg → Al3Mg2) is exothermic.