Hydrogen generation from hydrolysis of solid sodium borohydride promoted by a cobalt-molybdenum-boron catalyst and aluminum powder

Direct use of solid sodium borohydride (NaBH4) to react with minimized amount of water provides a straightforward means for increasing the hydrogen density of the system. But meanwhile, the resulting solid-liquid reaction system always suffers from serious kinetic problem. Our study found that the cobalt-molybdenum-boron (Co-Mo-B) catalyst prepared using an ethylene glycol solution of cobalt chloride is highly effective for promoting the hydrolysis reaction of solid NaBH4. Particularly, a combined usage of small amounts of Co-Mo-B catalyst, aluminum powder and sodium hydroxide enables a rapid and high-yield hydrogen generation from the hydrolysis reaction of solid NaBH4. A systematic study has been conducted to investigate the property dependence of the system on the components. In addition, the by-products of reaction were analyzed using powder X-ray diffraction and thermogravimetry/differential scanning calorimetry/mass spectroscopy techniques. Our study demonstrates that the multi-component system with an optimized composition can fulfill over 95% fuel conversion, yielding 6.43 wt% hydrogen within 3 min. The favorable combination of high hydrogen density, fast hydrogen generation kinetics and high fuel conversion makes the newly developed solid NaBH4-based system promising for portable hydrogen source applications.