Copper–iron mixed oxide catalyst precursors prepared by glycine-nitrate combustion method for ammonia borane dehydrogenation processes

Abstract

The influence of the properties of copper ferrite, prepared by the combustion method from glycine-nitrate precursor, on the kinetics of NH3BH3 hydrolysis, thermolysis and hydrothermolysis are presented. As-prepared and annealed samples were studied by X-ray diffraction, scanning electron microscopy, differential dissolution, and attenuated total reflection infrared spectroscopy. It has been shown that in the hydrolysis and hydrothermolysis of NH3BH3, the as-prepared combustion product, which mainly consisted of a cubic spinel Cu0.67Fe2.33O4 with Fe2+ higher content, had the highest activity, as compared with oxides of copper and iron and the annealed samples. According to transmission electron microscopy and X-ray diffraction, in the reaction medium copper ferrite is reduced to nanosized Cu0 and Fe0. This allowed the average rate of H2 evolution per 1 g of the composition to be increased from 30 to 76 ml⋅min−1, as compared with non-catalytic process. The high gravimetric hydrogen capacity (7.3 wt%) was observed at 90 °C.