Clean hydrogen production by the hydrolysis of magnesium-based material: Effect of the hydrolysis solution

Autonomous low-pressure hydrogen on demand system was found promising to supply fuel cell technology for light or short distance mobility applications. Among the various hydrogen production technologies, the hydrolysis reaction method of magnesium-based materials is one of the most suitable. Magnesium (Mg) powder ball milled with the simultaneous addition of graphite and nickel under Ar was used as the hydrolysis reagent for hydrogen production. The effects of the solution composition (i.e. NaCl, NH4Cl and HCl) and the temperature (i.e. from 0 °C to 60 °C) of the solution on the hydrolysis performances were discussed. The hydrolysis reaction was complete (i.e. yield = 100%) in less than 5 minutes, except that performed at 0 °C, regardless the hydrolysis solution. The activation energy of the reaction decreases with lowering the pH of the hydrolysis solution. Semi-quantitative analysis was performed to evaluate the variation of CH4, CO, CO2 and moisture contents in the hydrogen produced by the hydrolysis. The exothermicity of the reaction and the composition of the hydrolysis solution showed a major impact on the purity of hydrogen. Under standard pressure and ambient temperature conditions, the hydrolysis of magnesium-based materials is considered as a clean hydrogen production technique. Our results should be taken as the starting point to evaluate the purity of the hydrogen produced by the hydrolysis of Mg-based materials according to the ISO standard 14687:2019