Kinetic characteristics of sodium borohydride formation when sodium meta-borate reacts with magnesium and hydrogen

Sodium borohydride is attracting considerable interests as a hydrogen storage medium. In this paper, we investigated the effects of hydrogen pressure, reaction temperature and transition metal addition on sodium borohydride synthesis by the reaction of sodium meta-borate with Mg and H 2 . It was found that higher H 2 pressure was beneficial to NaBH 4 formation. The increase in reaction temperature first improved NaBH 4 formation kinetics but then impeded it when the temperature was raised to near the melting point of Mg. It was also found that some additions of transition metals such as Ni, Fe and Co in the NaBO 2 + Mg + H 2 system promoted the NaBH 4 formation, but Cu addition showed little effect. The activation energy of the NaBH 4 formation from Mg, NaBO 2 and H 2 was estimated to be 156.3 kJ/mol NaBH 4 according to Ozawa analysis method.