Study on the catalytic thermal decomposition of metal-hydride (NaH) to enhance the hydrogen desorption characteristics

Abstract

BackgroundSodium hydride (NaH) is considered a potential hydrogen storage material to generate hydrogen for fuel cell applications. The thermal decomposition required higher temperature, and a significant portion of NaH remains undecomposed. Thus, a suitable catalyst is required to lower the decomposition temperature and increase the hydrogen generation rate. ResultA series of catalyst/NaH hydrogen storage materials were systematically investigated. The facile solution method was used to synthesize the composite material with CaO, CaF2, and CaCl2 as catalysts. The hydrogen generation via thermolysis from the composite material was studied using in-situ flow reactors. The generated hydrogen was quantified using a gas chromatograph (GC). Adding CaO (catalyst) was beneficial to lower the thermolysis temperature of NaH, and the hydrogen generation increased from ∼0.31 wt% to ∼1.94 wt% at 100 °C. The CaO assisted in the dispersion of NaH and lowered the activation energy to decompose and generate more hydrogen by thermolysis at low temperatures. The synthesized composite materials were characterized by X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Raman spectroscopy, and Fourier Transform Infrared spectroscopy (FT-IR) studies. ConclusionThe generation of hydrogen was ∼1.94 wt% with 10CaO/NaH >1.68 wt% with 5CaO/NaH >1.61 wt% with 15CaO/NaH >1.41 wt% with 20CaO/NaH >0.31 wt% with pure NaH at 100 °C.