Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2)

Abstract

Research for suitable hydrogen storage materials is an important ongoing subject. LiBH4–Al mixtures could be attractive; however, several issues must be solved. Here, the dehydrogenation reactions of surface-oxidized 2LiBH4 + Al mixtures plus an additive (TiF3 or CeO2) at two different pressures are presented. The mixtures were produced by mechanical milling and handled under welding-grade argon. The dehydrogenation reactions were studied by means of temperature programmed desorption (TPD) at 400 °C and at 3 or 5 bar initial hydrogen pressure. The milled and dehydrogenated materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FT-IR) The additives and the surface oxidation, promoted by the impurities in the welding-grade argon, induced a reduction in the dehydrogenation temperature and an increase in the reaction kinetics, as compared to pure (reported) LiBH4. The dehydrogenation reactions were observed to take place in two main steps, with onsets at 100 °C and 200–300 °C. The maximum released hydrogen was 9.3 wt % in the 2LiBH4 + Al/TiF3 material, and 7.9 wt % in the 2LiBH4 + Al/CeO2 material. Formation of CeB6 after dehydrogenation of 2LiBH4 + Al/CeO2 was confirmed.

Keywords

• hydrogen storage
• borohydrides
• reactive mixtures