Hydrogen cycle with sodium borohydride

In this paper, we review production of NaBH4 as hydrogen storage material. Linking this with other processes, we create a system to recycle hydrogen. Difficulties and advantages of NaBH4 synthesis by natural available boron source colemanite and borax minerals were discussed. We show that basic chemicals suffice for NaBH4 production in a procedure designed to work below 275 degrees C. This procedure may be used to compensate for the loss of materials during the recycle. in this procedure, hydrogen including substances have been used to remove oxygen and bond remaining hydrogen to the by-product NaBO2 of dehydrogenation reaction. The wet and dry applications of producing NaBH4 have been also discussed. Moreover, a shorter procedure can be proposed to directly obtain NaBH4 from borax mineral. Among these processes, dehydrogenation is critical but it requires plenty of water. Hence, new types of catalyst are important to reduce the amount of water required during dehydrogenation. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.