Paper EN+SE+NS+SS-MoA9
Microwave Irradiation for the Reversible Desorption of Hydrogen from Sodium Aluminum Hydride

Monday, October 20, 2008, 4:40 pm, Room 203

Materials such as complex metal hydrides and hydrogen adsorbents have been the primary focus of the on-board hydrogen storage research program. Complex metal hydrides offer great potential in making it into the transportation industry due their reliable on-board reversibility. These materials can perform very well even after multiple dehydrogenation-hydrogenation cycles. Conventional heating mechanisms have been used to desorb hydrogen from complex metal hydrides. However, conventional heating processes involve high energy penalties (because the energy invested to heat the complex metal hydride is equal to or greater than the energy generated by a fuel cell using the desorbed hydrogen). This research is aimed at establishing the use of microwave irradiation to desorb hydrogen from sodium aluminum hydride (NaAlH4). Microwave heating is known to be more energy efficient than conventional heating. However, microwave fields are also known to drive order to disorder reactions in the hydrides, thus resulting in amorphous desorption products. This work reports a method to use microwave irradiation to desorb hydrogen from NaAlH4 via the reversible desorption pathway. This is the first report of using microwaves to drive a dehydrogenation reaction with the same pathway as driven by conventional heating processes. The method established in this research makes use of the energy efficiency of microwave irradiation and can be extended to other hydride systems for future research.

Funding for this project was provided by the Department of Energy, Office of Basic Energy Sciences (Contract No.: DE-FG02-05ER46246).