Hydrogen generation through sodium borohydride hydrolysis over supported cobalt catalysts and the effect of total dissolved solids in water

A series of xCoCl2/SiO2 (x = 5, 10, 20, 30, 40 and 50 wt%) catalysts were synthesized by two steps impregnation-reduction method. The catalysts were also prepared using other supports (SiO2, Al2O3, and MgO) and Co2B (bulk). The hydrogen generation was monitored using the synthesized catalysts. The prepared catalysts were characterized by using surface area measurement, X-ray diffraction (XRD), SEM images, and Raman spectroscopy analysis. The surface area of the catalyst 50CoCl2/SiO2 gradually increased with increasing calcination temperature. The calcination temperature found to be optimum was 573 K. All the calcined samples were highly amorphous, even after calcining at 773 K. A highly dispersed Co3O4 species formed in all the catalysts during the synthesis. The Co3O4 species did not significantly affect the rate of hydrogen generation. The most active catalyst was the 50CoCl2/SiO2 when the catalyst was prepared by the calcined temperature at 573 K, followed by reduction. The order of catalytic activity for the generation of hydrogen was as follows: 50CoCl2/SiO2 > 50CoCl2/Al2O3 > CoCl2 (Co2B) > 50CoCl2/MgO. The hydrogen generation rate (HGR) was observed with the most active catalyst ~ 4500 ml/min/gcat. Moreover, the TDS (total dissolved solids) of the water used for sodium borohydride solution also affected the hydrogen generation rate. The water possessing the lowest TDS generated the highest amount of hydrogen.