A Novel Catalytic Process for Generating Hydrogen Gas from Aqueous Borohydride Solutions

Abstract

A safe, simple, lightweight, and compact process generates high-purity hydrogen gas on demand from base-stabilized, aqueous solutions of sodium borohydride, NaBH₄, by using a ruthenium catalyst. NaBH₄ solutions can generate the equivalent of >2,500 Wh/L and >7% H₂ by weight can be recovered. These inherently stable solutions do not generate significant amounts of H₂ gas under ambient conditions. However, when in contact with heterogeneous Ru catalyst, NaBH₄ solutions rapidly hydrolyze to form H₂ gas and sodium borate, a water-soluble, inert salt. H₂ generation only occurs when NaBH₄ solutions are in contact with Ru catalyst. When Ru catalyst is removed from NaBH₄ solution (or NaBH₄ solution is separated from Ru catalyst), H₂ generation stops. This H₂ generator promises to be safer, have quicker response to H₂ demand, have a greater H₂ storage efficiency, and be more easily controllable than current H₂ storage devices/generators. It can be easily incorporated into any system where H₂ gas is required, such as powering internal combustion engines or fuel cells.