Hydrogen evolution performance of magnesium alanate prepared by a mechanochemical metathesis reaction method

Solvent-free magnesium alanates were prepared by a mechanochemical metathesis reaction method (ball milling method) with a variation of milling time. For the purpose of comparison, magnesium alanate was also prepared by metathesis reaction method in the presence of diethyl ether. The formation of magnesium alanate (Mg(AlH 4 ) 2 ) and magnesium alanate-diethyl ether (Mg(AlH 4 ) 2 ·Et 2 O) adduct was confirmed by XRD measurements. In both magnesium alanates, hydrogen evolution occurred in the first step decomposition. The starting temperature for hydrogen evolution of the solvent-free magnesium alanates decreased with increasing milling time, whereas the amount of hydrogen evolution of the solvent-free magnesium alanates increased with increasing milling time. The maximum amount of hydrogen evolution of the Mg(AlH 4 ) 2 ·Et 2 O adduct was slightly larger than that of the solvent-free Mg(AlH 4 ) 2 , but the starting temperature for hydrogen evolution of the Mg(AlH 4 ) 2 ·Et 2 O adduct was much higher than that of the solvent-free Mg(AlH 4 ) 2 . The addition of a small amount of titanium to the solvent-free Mg(AlH 4 ) 2 greatly reduced the hydrogen evolution temperature of titanium-doped Mg(AlH 4 ) 2 . However, the maximum amount of hydrogen evolution of the titanium-doped Mg(AlH 4 ) 2 was smaller than that of the solvent-free Mg(AlH 4 ) 2 .