Kinetics of Hydrolysis of Sodium Borohydride with Water Vapor

Hydrolysis of sodium borohydride is one route for solid state hydrogen storage and release. Compared with the aqueous phase reaction, the hydrolysis of sodium borohydride with water vapor gives a faster reaction for hydrogen production. Prior studies on the water vapor hydrolysis from our group have revealed the physical mechanism for the release of hydrogen by water vapor. However, there are presently no data on the kinetics of the hydrogen evolution. We have developed a semi-batch tube reactor to study the hydrolysis of sodium borohydride with water vapor. The water vapor deliquesces to form a concentrated liquid phase that reacts to evolve hydrogen. It is found that CoCl₂, a solid catalyst, can significantly improve the hydrogen generation rate. The impact of this metal salt catalyst on the deliquescence and hydrolysis kinetics has been investigated. This presentation will be the first to report a quantitative study on the hydrogen generation kinetics of the steam phase hydrolysis. The hydrogen delivery rate for NaBH₄ reacting with water vapor has also been optimized.