Advanced reactor concept for complex hydrides: Hydrogen absorption from room temperature

Abstract

Complex hydride materials (CxH) are potential candidates for hydrogen storage in automotive applications due to their high hydrogen storage capacities. However, the reaction rates of these materials are rather low at temperatures below 100 °C implying negative effects on absorption performance e.g. at a fuelling station. In this paper simulated and experimental results of a new reactor concept that can improve the dynamic reactor performance are presented. This concept is based on the combination of a metal hydride (MeH) and a CxH in one reactor, separated by a gas permeable layer. The storage capacity of available MeH materials is just ∼1 wt.%, however, they show very high reaction rates even at room temperature. Thus, the idea of this concept is to combine both: the high storage capacity of the CxH material and the high reaction rate of the MeH material. The two reference materials for this study are 2LiNH2–1.1MgH2–0.1LiBH4–3 wt.%ZrCoH3 (Li–Mg–N–H) and LaNi4.3Al0.4Mn0.3 (MeH). In the first part, 2D simulation results are presented showing the development of a reaction front from the core to the annulus of the tubular reactor caused by the fast exothermal absorption reaction of the MeH material. In the second part, experimental results of a 50 g lab-scale reactor and simulated scenarios are presented and used for model validation. In the present scenario it has been possible to reduce the time to initiate the absorption reaction from room temperature by approximately 500 s.