Modeling the kinetic behavior of the Li-RHC system for energy-hydrogen storage: (I) absorption

• Published in: International journal of hydrogen energy Vol. 46; no. 63; pp. 32110 - 32125
• Main Authors: Neves, A.M., Puszkiel, J., Capurso, G., Bellosta von Colbe, J.M., Milanese, C., Dornheim, M., Klassen, T., Jepsen, J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 13.09.2021
• Subjects: Borohydrides; Hydrogen storage; Kinetic modeling; Metal hydride; Reactive hydride composite; Hydrogen storage; Metal hydride; Kinetic modeling; Borohydrides; Reactive hydride composite
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.06.227

The Lithium–Boron Reactive Hydride Composite System (Li-RHC) (2 LiH + MgB2/2 LiBH4 + MgH2) is a high-temperature hydrogen storage material suitable for energy storage applications. Herein, a comprehensive gas-solid kinetic model for hydrogenation is developed. Based on thermodynamic measurements under absorption conditions, the system's enthalpy ΔH and entropy ΔS are determined to amount to −34 ± 2 kJ∙mol H2−1 and −70 ± 3 J∙K−1∙mol H2−1, respectively. Based on the thermodynamic behavior assessment, the kinetic measurements' conditions are set in the range between 325 °C and 412 °C, as well as between 15 bar and 50 bar. The kinetic analysis shows that the hydrogenation rate-limiting-step is related to a one-dimensional interface-controlled reaction with a driving-force-corrected apparent activation energy of 146 ± 3 kJ∙mol H2−1. Applying the kinetic model, the dependence of the reaction rate constant as a function of pressure and temperature is calculated, allowing the design of optimized hydrogen/energy storage vessels via finite element method (FEM) simulations. [Display omitted] •Experimental determination of hydrogenation thermodynamic parameters.•Critical analysis of the reported hydrogenation thermodynamic data.•Development of a comprehensive semi-empirical absorption kinetic model.•One-dimensional interface-controlled reaction upon hydrogenation.