Hydrolysis of solid ammonia borane

Ammonia borane NH3BH3 is a promising hydrogen storage material by virtue of a theoretical gravimetric hydrogen storage capacity (GHSC) of 19.5 wt%. However, stored hydrogen has to be effectively released, one way of recovering this hydrogen being the metal-catalyzed hydrolysis. The present study focuses on CoCl2-catalyzed hydrolysis of NH3BH3 with the concern of improving the effective GHSC of the system NH3BH3–H2O. For that, NH3BH3 is stored as a solid and H2O is provided in stoichiometric amount. By this way, an effective GHSC of 7.8 wt% has been reached at 25 °C. To our knowledge, it is the highest value ever reported. Besides, one of the highest hydrogen generation rates (HGRs, 21 ml(H2) min−1) has been found. In parallel, the increases of the water amount and temperature have been studied and the reaction kinetics has been determined. Finally, it has been observed that some NH3 release, what is detrimental for a fuel cell. To summarize, high performances in terms of GHSCs and HGRs can be reached with NH3BH3 and since research devoted to this boron hydride is at the beginning we may be confident in making it viable in a near future.