Processing of LiBH 4 from its elements by ball milling method

Abstract

Investigations of alternative renewable energy resources continue, with many studies concentrating on hydrogen storage. However, there are a few problems such as storage, transportation, delivery to the user and usage safely, to be addressed to facilitate commercialization and wide usage of the hydrogen. The absorbed form within the metal hydrides seems to be the best solution of this problem. Since Li is the lightest metal, it has the advantage as the stored amount of hydrogen mass ratio. LiBH 4 production process was investigated using elemental Li, B and H 2. Spex type ball milling with tungsten carbide, stainless steel and zirconia type vessels, was used to mix the different amount of Li and B under argon atmosphere. X-ray diffraction pattern demonstrated that the LiB was obtained. A system was designed to provide a hydrogen atmosphere of 60 bars to force hydrogen into the LiB structure. FTIR analysis strongly indicated the LiBH 4 compound when the mol ratio of B/Li is 0.214. Thermal decomposition and heat flow experiments performed simultaneously with DSC and TGA techniques also indicate hydrogen-rich structure showing greater mass loss. One gram of lithium borohydride sample released 1423 ml of hydrogen with Ni catalyst while NiO caused 1972.94 ml of hydrogen gas desorption, equaling to 90% of the theoretical yield of commercial LiBH 4. Indicating that, hydrogen of water can be obtained by either Ni or NiO catalysts.