Empirical kinetic model of sodium alanate reacting system (II). Hydrogen desorption

Simulation and design of hydrogen storage systems based on metal hydrides require appropriate quantitative kinetic description. This paper presents an empirical kinetic model for the two-step hydrogen desorption of sodium alanate material doped with aluminium-reduced TiCl4, produced in kg-scale. The model is based on kinetic data obtained by volumetric titration measurements within a range of experimental conditions varying from 0 bar to 35 bar and from 100 °C to 190 °C. It is shown that while the first desorption step is a zero-order reaction, the second desorption step follows the Johnson–Mehl–Avrami (JMA) equation with n = 1. The predictions of the model are validated by experimental results and are used to asses the pressure–temperature (p–T) performance of the desorption steps against selected hydrogen supply criteria. This paper complements a previous paper of this investigation that presented the kinetic model of the corresponding hydrogen absorption of sodium alanate material.