Compressed hydrogen production via reaction between liquid ammonia and alkali metal hydride

Ammonia NH₃ is recognized as one of the attractive hydrogen H₂ carriers because it has a high hydrogen content of 18 mass% and it is easily liquefied under about 1 MPa of pressure at a room temperature. NH₃ can react with alkali metal hydrides and generate H₂ even at room temperature, resulting that metal amides are formed as reaction products. The H₂ generation is exothermic reaction, and it is not effectively prevented by H₂ partial pressure in a closed system as thermodynamic properties. In this work, we demonstrated the production of compressed H₂ by the reaction between liquid NH₃ and lithium hydride LiH in a closed pressure vessel, where liquid NH₃ would realize better kinetic properties for the reaction with metal hydride than gaseous NH₃. Actually, more than 12 MPa H₂ was obtained within several hours.