Hydrogen Production from Sodium Borohydride in Boric Acid-water Mixtures

Borohydride, which reacts slowly with water, is developed as hydrogen production and storage options. The reaction is significantly accelerated by the rise of temperature or by the addition of acidic substances. Boric acid (H3BO3) can be used as an alternative to water for the hydrogen production in the hydrolysis of sodium borohydride (NaBH4). The effect of H3BO3 and NaBH4–H3BO3 molar ratios was studied at 30, 40, 50, 60, and 80°C on the hydrogen production of NaBH4. All of these results show that H3BO3 is a relatively green acid compound for hydrogen generation from NaBH4 and the H3BO3-water-NaBH4 system being quite simple for single-use applications. It was found that the reaction between H3BO3 and NaBH4 complied with a second order kinetics rate with 0.5 reaction orders versus NaBH4 concentration and 1.5 orders versus H3BO3 concentration, and the activation energy for conversion was calculated as 18.01 kJ mol−1.