Basic Properties and Safety Features for Handling Ammonia Borane as Hydrogen Source: Toxicity, Corrosivity, Flammability, and Preservability

To ensure the safe transportation and handling of ammonia borane (AB) as a hydrogen source, its fundamental safety-related properties, which include toxicity, corrosivity, flammability, and storage stability, were evaluated in both aqueous solution and powder. Toxicity tests on an AB aqueous solution indicated carcinogenicity, highlighting the need for precautions to avoid ingestion, penetration into the skin, and contact with the eyes. Immersion tests with AB aqueous solution showed corrosion and surface deposition on several metal plates. The flash and ignition points of an 8 mol/L AB aqueous solution were 56.5 and 129 °C, respectively, while the flash point of the AB powder was 84.0 °C. AB powder retained its purity after four years of storage at room temperature with air exposure. AB powder absorbed moisture at >80 RH% at 25 °C and did not degrade when the absolute humidity was ≤4.4 g/m3 at temperatures below 50 °C. AB powder in the container with low humidity maintained its purity for one week outdoors during summer (below 50 °C). These findings provide a comprehensive dataset to support safety design, risk management, and regulatory guidelines for the practical use of AB in hydrogen systems.