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Regeneration of LiAlH4 at sub-ambient temperatures studied by multinuclear NMR spectroscopy

2017; Elsevier BV; Volume: 723; Linguagem: Inglês

10.1016/j.jallcom.2017.06.300

1873-4669

Terry D. Humphries, Derek Birkmire, G. Sean McGrady, Bjørn C. Hauback, Craig M. Jensen,

Hybrid Renewable Energy Systems

Lithium aluminium hydride (LiAlH4) has long been identified as a viable hydrogen storage material, due to its high attainable theoretical gravimetric hydrogen capacity of 7.9 wt%. The main impediment to its viability for technical application is its limitation for regeneration. Recently, solvent-mediated regeneration has been achieved at room temperature using dimethyl-ether, Me2O, although the reaction pathway has not been determined. This in situ multinuclear NMR spectroscopy study (27Al and 7Li) has confirmed that the Me2O-mediated, direct synthesis of LiAlH4 occurs by a one-step process in which LiAlH4·xMe2O is formed, and does not involve Li3AlH6 or any other intermediates. Hydrogenation has been shown to occur below ambient temperatures (at 0 °C) for the first time, and the importance of solvate adducts formed during the process is demonstrated.