Preparation of magnetic cobalt-based catalyst for hydrogen generation from alkaline NaBH4 solution

摘要

A fast and simple fabrication process, viz. a wet-chemical reduction process, was utilized for preparation of a cobalt-based catalyst to be used for hydrogen generation from alkaline NaBH4 solution. Characteristics of this cobalt-based catalyst were carried out by using various instruments, such as SEM/EDS, XPS, 1CP, VSM, BET and TGA. The surface chemistry of the obtained catalyst is mainly cobalt oxides, not cobalt borides. Ferromagnetic property of the cobalt-based catalyst makes it convenient for being recycled from spent NaBH4 solution. The rate of hydrogen generation from catalyzed hydrolysis of alkaline NaBH4 solution was determined as a function of temperature, NaBH4 concentration, and NaOH concentration in the presence of prepared catalysts. In general, stable generation rate of highly pure hydrogen near 200 mL mm~(-1) g~(~1) was achieved in 100 mL of 5 wt% NaBH4 solution containing 5 wt% NaOH solution and 200 mg of Co/IR-120 catalyst, in which no temperature runoff was observed during the course of hydrogen production. The activation energy of NaBH4 hydrolysis reaction was found at 66.67 kJ mol~(-1) which was comparable with others reported in the open literatures.