Electroerosion dispersion-prepared nano- and submicrometre-sized aluminium and alumina powders as power-accumulating substances

Abstract

The nano- and submicrometre aluminium powders prepared by electroerosion dispersion (EED, which consists in dispersing a granulated metal by electric discharges) can be used as power-accumulating substances (PAS) able to produce hydrogen using their reaction with water in the presence of caustic alkali. The spherical shape and polydisperse composition of Al powders consisting of nano- and submicrometre particles (from 0.05 to 5 μm) allow dense packing of the PAS (1240 kg/m3) and provide the possibility to produce 1.5252 m3 (at 1 atm) of hydrogen from 10–3 m3 of PAS. The presence of a nanosized fraction ensures a short induction period of the reaction with water and a high rate of hydrogen release. The polydisperse composition of the powders is responsible for the constant reaction rate. The aluminium oxide (Al2O3) powders, which are the products of the reaction with water, can be used as polishing powder, for manufacturing ceramic materials, or can be reduced back to aluminium. EED-produced amorphous Al2O3 with grains of size 5–100 nm can be used to store hydrogen (due to occlusion of hydrogen in the alumina) and thus can also be considered as a PAS.