Empirical kinetic model of sodium alanate reacting system (I). Hydrogen absorption

Hydrogen storage systems based on metal hydrides require appropriate quantitative kinetic description for simulations and designs, in particular for the crucial absorption process. This investigation proposes an empirical kinetic model for the hydrogen absorption 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 performed on each of the two absorption steps of sodium alanate, within a range of experimental conditions varying from 10 bar to 110 bar and from 100 °C to 180 °C. It is shown that each step is best described by the JMA model with n = 1.33. The kinetic equations are implemented in a mass balance and used to predict the reaction rate of the two steps of hydrogen absorption. Even when they proceed simultaneously, the predictions agree well with experimental results. The second paper of this investigation presents the results for the kinetic model of the corresponding hydrogen desorption.