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.