Regeneration of Ammonia-Borane Complex for Hydrogen Storage

Abstract

AbstractAt the Florida Solar Energy Center (FSEC), a research program is underway for developing a high-density hydrogen storage system based on amine-borane (AB) complexes. Due to their high hydrogen capacity, these hydrides have been employed, in the past, as disposable hydrogen sources for fuel cell applications. However, to meet the requirements for hydrogen storage onboard vehicles, it is essential that cost effective and energy efficient methods for the regeneration (i.e. hydrogenation) of the spent (dehydrogenated) AB complexes can be found that utilize only hydrogen and/or electricity (i.e. the only plausible hydrogen economy energy carriers).We are studying two ammoniaborane (NH3BH3)-based systems with high hydrogen storage capacity. The first system employs a borazine-cyclotriborazane cycle. Borazine is a product of NH3BH3 thermolysis. Cyclotriborazane is the inorganic analog of cyclohexane. The second system employs polymeric AB complexes such as poly-(aminoborane) and polyborazylene. Poly-(aminoborane), an inorganic analog of polyethylene, is also a product of amoniaborane thermolysis whilepolyborazylene is the product of borazine thermolysis.For the two systems above, we are developing regeneration (i.e. reduction of borazine, poly-(aminoborane) and polyborazylene) schemes based on: 1) catalytic hydrogenation and 2) indirect (multi-step) synthesis techniques.