Dynamic Response of a High Pressure Hydrogen Generator

Abstract

Hydrogen generation from catalyzed solutions of sodium borohydride has been demonstrated experimentally up to 10 MPa. Sodium borohydride solutions are nonflammable, stable in basic solution, and offer a volumetric hydrogen density of 63.2 gH2/l. In the presented work, the reaction rate data for catalyzed hydrolysis of sodium borohydride solutions as a function of hydrogen static pressure are coupled with a polymer electrolyte membrane fuel cells model. It has been shown that the elevated hydrogen pressure can bring the solution to equilibrium and tends to return to equilibrium upon pressure decrease. The model considers hydrogen demand from a fuel cell and the response of the high pressure hydrogen generator in terms of a mass balance. It is shown that 2–4 g of Co3B is adequate to hydrolyze 60 l of 30 wt %NaBH4 solution.

Chemical compression and transport of hydrogen using sodium borohydride

“…12 Sodium borohydride can be used to generate hydrogen above atmospheric pressure through hydrolysis as a form of chemical hydrogen compression. 38,39 Thus, it should be considered that NaBH 4 could directly generate high hydrogen pressure suitable for use at refuelling stations by simply adding water, avoiding the use of mechanical compression. The thermodynamics for hydrolysis and methanolysis of NaBH 4 suggest that extreme hydrogen pressure is possible, 40 but to date it has not been shown that hydrogen can be generated at pressures comparable to mechanical compression technology.…”