Synthesis of sodium amidoborane (NaNH2BH3) for hydrogen production

The prospect of building a future energy system on hydrogen has stimulated much research effort in developing hydrogen storage technologies. One of the potential materials newly developed is sodium amidoborane (NaNH2BH3) which evolves ∼7.5 wt% hydrogen at temperatures as low as 91 °C. In this paper, two methods of synthesizing pure NaNH2BH3 were reported. One method is by reacting NaH and ammonia borane in THF at low temperatures, and the other is by reacting NaNH2 and ammonia borane in THF at ambient temperature. Non-isothermal testing on the thermolysis of solid NaNH2BH3 showed that hydrogen evolution was composed of two exothermic steps. More than 1 equiv. H2 was evolved rapidly at temperatures below 87 °C. After evolving 2 equiv. H2, NaH was identified in solid products and coexisted with amorphous BN.