Hydrogen generation by hydrolysis of sodium borohydride on CoB/SiO2 catalyst

Generation of hydrogen by hydrolysis of alkali metal hydrides has attracted attention. Unsupported CoB catalyst demonstrated high activity for the catalytic hydrolysis of NaBH4 solution. However, unsupported CoB nanoparticles were easy to aggregate and difficult to reuse. To overcome these drawbacks, CoB/SiO2 was prepared and tested for this reaction. Cobalt (II) acetate precursor was loaded onto the SiO2 support by incipient-wetness impregnation method. After drying at 100 °C, Co cations were deposited on the support. The dried sample was then dispersed in methanol/water solution and then fully reduced by NaBH4 at room temperature. The catalyst was characterized by N2 sorption, XRD and XPS. The results indicated that the CoB on SiO2 possessed amorphous structure. B and Co existed both in elemental and oxidized states. SiO2 not only affected the surface compositions of CoB, but also affected the electronic states of Co and B. B0 could donate partial electron to Co0. The structure effect caused by the SiO2 support helped to prevent CoB nanocluster from aggregation and therefore the activity increased significantly on hydrolysis of alkaline NaBH4 solution. The CoB/SiO2 catalyst showed much higher activity than the unsupported CoB catalyst. At 298 K, the hydrogen generation rate on CoB/SiO2 catalyst was 4 times more than that on the unsupported CoB catalyst. The hydrogen generation rate was as high as 10,586 mL min−1 g−1 catalyst at 298 K. CoB/SiO2 is a very promising catalyst for this reaction.