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

Abstract

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.