Speaker: Andrew D.
Sutton, C-IIAC (Inorganic, Isotope, & Actinide
Chemistry),
Winner of the Postdoc
Publication Prize in Experimentation Sciences
Regeneration of Ammonia Borane Spent Fuels by
Direct Reaction with
Hydrazine
and Liquid Ammonia
Abstract:
A critical factor in
realizing a hydrogen (H2) economy is storage of the molecule for
controlled delivery, presumably to an energy producing fuel cell.
Options for H2 storage include compressed hydrogen, metal hydrides and
porous sorbent materials. In addition to these there is also the
possibility to utilize chemical hydrides where the H2 is stored in E-H
bonds (E = C, B, N, O). In this case, hydrogen can be released
thermally or through the use of an acid, base or metal catalyst.
Ammonia borane (H3N-BH3, AB) is a particularly appealing chemical
hydrogen storage medium, due to its high gravimetric capacity of H2
(19.6 wt %), low molecular weight (30.7 g mol-1), and overall chemical
properties. AB has both hydridic and protic hydrogens, facilitating H2
release under mild conditions. Methods explored for promoting
release include acid or base treatment as well as transition metal
catalysis. At the same time, the viability of any storage system
is critically dependent on efficient recyclability. We will
present results and methods to fully regenerate AB from a variety of
spent fuel types using hydrazine (N2H4) and liquid
ammonia.