Dissociation and hydrolysis of ammonia-borane with solid acids and carbon dioxide: An efficient hydrogen generation system

Pure hydrogen generation under mild conditions in a controllable way is important for portable devices. Recently, we have found that an aq. ammonia-borane (NH3BH3) solution is a potential hydrogen source with noble metal catalysts. For practical use, the development of a low-cost, efficient and safe system is desired. In this study, we found that solid acids such as cation exchange resins and zeolites, which are low-cost and safe, also exhibit high activities for the dissociation and hydrolysis of NH3BH3 to generate hydrogen with an H2 to NH3BH3 ratio up to 3.0 at room temperature. The reaction rate depends on the type of solid acid. Especially, Dowex and Amberlyst, the two low-cost solid acids often used as catalysts in a variety of reactions, exhibit reaction kinetics higher than the noble metal catalysts. Carbon dioxide is also active as an acid for this reaction. The reaction products in solution have been identified by 11B NMR, and the evolved gases have been analyzed by mass spectrometry which indicates high purity hydrogen. This new system may have a high potential for application in fuel cells.