Synthesis of ammonia borane for hydrogen storage applications

A new synthetic procedure to make the condensed phase hydrogen storage material, ammonia borane (NH(3)BH(3), abbreviated as AB), is described and compared with previous literature procedures. Ammonia borane with a gravimetric density ca. 194 gm H(2) kg(-1) and a volumetric density ca. 146 H(2) litre(-1), is a promising chemical hydrogen storage material for fuel cell powered applications. The work shows that ammonium borohydride, NH(4)BH(4), formed in situ by the metathesis of NH(4)X and MBH(4) salts (M = Na, Li; X = Cl, F) in liquid NH(3), can be induced to decompose in an organic ether to yield AB in near quantitative yield. The purity of the AB prepared by this one-pot synthetic strategy is sufficient to meet the thermal stability requirements for on-board hydrogen storage.