Ammonia synthesis via catalytic and chemical-looping process mediated by sodium–nitrogen solid solution

Ammonia synthesis techniques by sodium hydride are proposed, and the properties are investigated. NaH revealed a catalytic activity for the NH₃ formation from mixed hydrogen and nitrogen gases below 1.0 MPa of pressure. The stability of NaH at each pressure and temperature condition was an essential factor for the catalysis. Furthermore, the NaH was used as a reactant for chemical looping process, where NaH reacted with N₂ and H₂ at different processes. Interestingly, NH₃ can be synthesized by the chemical looping process stably under less than 1.0 MPa of pressure during the cycles. As an intermediate phase, it was indicated that a nitrogen solid solution phase of Na (NaN_x) was formed. Although the amount of soluble nitrogen was small, about 0.02, this intermediate phase possessed an important role to generate reactive atomic nitrogen for the NH₃ synthesis by catalytic and chemical looping processes.