Chemical looping synthesis of amines from N₂ via iron nitride as a mediator

Amines are commonly synthesized through the amination of organooxygenates using ammonia, frequently involving the use of noble metal catalysts. In this study, we present an alternative route to make amines using iron nitride (Fe_2.5N) as the nitrogen source. Without any additional catalyst, Fe_2.5N reacts with a range of alcohols at 250 °C under 1 or 10 bar H₂ to produce amines as major products. Mechanistic investigations indicate that hydrogen activates the nitrogen species within iron nitride, converting them into surface NH and NH₂ groups that then react with alcohols to form amines. Building on this foundation, we further demonstrate an iron nitride-mediated chemical looping pathway that utilizes N₂ as the nitrogen source to synthesize octylamines. In this process, N₂ first reacts with iron to form Fe_xN by a ball-milling method at ambient temperature and 6 bar N₂. The as-prepared Fe_xN subsequently reacts with alcohols to yield amines, transferring over 80% of the nitrogen to organic compounds. This looping process proves stable across four cycles.