Dehydrogenation Pressure Drop in NaBH_4 Solution in Ru-Catalyzed 300 μm Microchannel Chemical Reactor

摘要

Sodium borohydride (NaBH_4) is considered to be a secure metal hydride for hydrogen storage and supply. In this study, the two-phase pressure drop in the dehydrogenation of aqueous NaBH_4 solution in a microchannel with a hydraulic diameter of 300 μm is investigated for the purpose of designing a dehydrogenation chemical reactor. Because hydrogen gas was generated by the hydrolysis of NaBH_4 in the presence of a ruthenium catalyst, two different phases of flow (aqueous NaBH_4 solution and hydrogen gas) exist in the microchannel reactor. For experimental studies, a microchannel was fabricated on a silicon wafer substrate with a 100 nm ruthenium catalyst deposited on three sides of the channel surface. Based on the experimental result, it is found that the two-phase multiplier linearly increases with the void fraction, which depends on the initial NaBH_4 concentration, the NaBH_4 reaction rate, and the flow residential time.