Borohydride-induced destabilization of hydrazine borane

We investigated the destabilization of 4 mol of hydrazine borane N2H4BH3 in the presence of 1 mol of an alkaline borohydride (LiBH4 or NaBH4) and, in a second step, of 1 mol of NH3BH3 in addition. The destabilization was followed by TGA, DSC and mu GC. The solid residues were analyzed by solid-state B-11 NMR, IR and XRD. The presence of the borohydride effectively destabilizes N2H4BH3 which is thus able to liberate H-2 from 50 degrees C. Seeing the results from the other side, one could consider that the alkaline borohydrides are destabilized by N2H4BH3. Such destabilization approach is attractive as it involves boron-based materials only. The best decomposition results were obtained with the sample containing 4 mol of N2H4BH3 and 1 mol of LiBH4 (containing 16 equiv. H-2). Upon heating up to 300 degrees C at 5 degrees C min(-1), this sample releases 12.1 mol of H-2 (dehydrogenation extent of 76%) and 1.1 mol of N2H4. A solid residue of empirical formulae LiB5N5.8H3.4 is formed. It is composed of polyborazylene- and/or boron nitride-like materials. This is an attractive feature as it implies recyclability of the polymer and elaboration of inorganic ceramics at relatively low temperatures. Our main results are reported herein. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.