Pulling the Weight: Base Metal-Catalyzed Dehydrogenation of Amine-Borane Fuel Blends

With both protic N-H and hydridic B-H bonds as well as three hydrogen atoms per main group element, ammonia-borane (AB, H3NBH3) is a promising material for chemical hydrogen storage applications. Selected metal complexes and supported metals have been shown to be effective catalysts for dehydrogenation of AB and substituted amine-boranes to afford oligomeric aminoborane (RHNBH2)n and iminoborane (RNBH)n products (R = H, alkyl). While AB has the highest storage capacity, preference for a ‘drop-in’ liquid fuel has led to development of amine-borane fuel blends. For R = sec-Bu, for example, the amine-borane and its dehydrogenation products are liquids at operating temperatures and readily dissolve AB and its dehydrogenation products. Suitable catalysts, reaction conditions and performance will be discussed