Hydrogen desorption kinetics of CeCl3-doped sodium aluminum hydride compacts measured by parallel in situ FTIR-ATR-spectroscopy and gravimetry

In this work, in situ FTIR-ATR-spectroscopy and gravimetry were used in parallel to determine the dehydrogenation reaction kinetics of 2 mol% CeCl3-doped NaAlH4 compacts. Dehydrogenation measurements were performed under isothermal and isobaric conditions at different temperatures. Subsequently spectroscopic and gravimetric data were fitted by Johnson-Mehl-Avrami and Arrhenius equation to obtain the rate conkants of the dehydrogenation and activation energy of the NaAlH4-Na3AlH6 phase change. On the one hand the measurements showed that cycling of the powder compacts enhances the dehydrogenation reaction kinetics of the NaAlH4 phase, whereby a decrease of the activation energy by 3.4 kJ/mol was measured. On the other hand an influence on the calibration of the spectroscopic signal to the mass of desorbed hydrogen was observed. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.