Hydrogen production from aluminum reaction with NaOH/H2O solution: Experiments and insight into reaction kinetics

Hydrogen as a clean energy carrier is a promising candidate for a shift from fossil fuels to renewable sources. Since hydrogen shall be separated from other elements, various chemical processes may be exploited to this end, including the reaction between aluminum and alkaline solutions. The chemical kinetics of the reaction between aluminum and NaOH/water solution was investigated experimentally in a setup relying on the Dietrich-Frühling method. The parametric analysis encompassed aluminum surface area available for interaction, NaOH concentration and operating temperature, including subzero conditions. Hydrogen production aligned with that predicted through stoichiometric calculations. Moreover, it was demonstrated that reaction rate increases with temperature, concentration and specific surface area of the aluminum samples, also showing how an increase in one of those parameters counterbalances the effect by decreasing another. Finally, activation energy was calculated for the involved reaction as equal to about 50 kJ mol−1, together with Arrhenius coefficient (20526 s−1).