In situ generated catalysts for NaBH4 hydrolysis studied by liquid-phase calorimetry: Influence of the nature of the metal Original Research Article

Several metal chloride salts have been evaluated as precursors of in situ generated catalysts for borohydride hydrolysis. The apparatus used for this study is a reaction calorimeter coupled with a hydrogen volumetric flow-meter. Successive additions of low and high concentration solutions of NaBH4 were performed within this system in order to determine the stability of the catalysts and the poisoning effect of residual metaborate. Both the kinetics of hydrogen production and the concomitant calorimetric signal were studied from this perspective. This work highlights the occurrence of two different types of behaviours among the in situ generated catalysts, and demonstrates that those metals which can be readily oxidized and form stable boride species are the best catalysts for the catalytic borohydride hydrolysis reaction, at a lower cost compared to precious metals. The performances of these catalysts are not affected by the concentration of the NaBH4 solution, and the rate of hydrogen generation remains constant during the reaction.