Hydrogen generation from solvolysis of sodium borohydride in ethylene glycol–water mixtures over a wide range of temperature

Abstract

A high-performance hydrogen generation system with fast kinetics and a wide range of operational temperature is highly desirable for promoting the implementation of hydrogen fuel cell technology. In the present study, we report a comparative study of the hydrogen generation properties from the reactions between sodium borohydride (NaBH₄) and ethylene glycol (EG), water (H₂O) or their mixture. Our study found that the glycolysis kinetics of NaBH₄ is faster than the hydrolysis kinetics at moderate temperatures, but gets sluggish at low temperatures. As a solution, the combined usage of EG–water mixture as solvent and cobalt chloride (CoCl₂) as a promoting additive enables the system to rapidly deliver H₂ at low temperatures. A series of control experiments have been conducted to evaluate the hydrogen generation property dependence on EG concentration, CoCl₂ amount and ratio of EG–H₂O mixture to NaBH₄. The reaction byproducts were characterized by powder X-ray diffraction and Fourier transform infrared spectroscopy techniques. Our study demonstrated a high-performance hydrogen generation system with a wide range of operational temperature, which may lay the foundation for developing practical hydrogen source for mobile/portable applications.