Hydrogen generation by hydrolysis of NaBH4

The hydrolysis of sodium-borohydride (SBH) to produce hydrogen has been studied at various temperatures using salts of nickel (II) or iron (III) as catalyst. Excess of water has been added to a mixture of solid SBH and catalyst to start hydrolysis reaction and the evolved hydrogen measured as a function of time. After a sudden peak a constant hydrogen flow was observed when Ni is used as catalyst. The activation energy has been evaluated from the dependence of the reaction time and of the hydrogen flow on the inverse of temperature. If Ni is substituted by a Fe based catalyst, after the initial increase, a different shape is observed in the hydrogen flow: it reaches a maximum and then monotonously decrease to zero. The different shape has been related to the different activity of the catalyst. The reaction activation energy was evaluated to be 73 KJ/mol.