Kinetics study of hydration reaction between aluminum powder and water based on an improved multi-stage shrinking core model

Hydrogen evolution and hydration kinetics of aluminum-particle-water reaction are investigated by a series of isothermal experiments. Morphology development of the Al particle during the hydration reaction process is characterized by SEM and XRD. An improved multistage analytical model has been developed and validated with the experimental data. The pre-exponential factor and activation energy for the alumina hydrolysis, Al-water reaction, and diffusion in the product layer are estimated based on the proposed model. The effects of growing particle size, formation and breakage of initial porous boehmite (AlOOH) layer, multi-stage reaction kinetics on the overall reaction rate are incorporated in the model. The study results show that the overall reaction rate is jointly controlled by simultaneous action of individual driving force, including mass transfer, chemical reaction and diffusion. The improved model enables the predictions of induction period and the evolution rate of hydrogen as a function of time, temperature and particle size. (c) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.