Theoretical study on the gas-phase reaction mechanism of ammonia with nitrous oxide

Applications of nitrous oxide (N₂O) as an oxidant in green propellants and propulsion systems have attracted a lot of attention. In this study, the reaction pathways for the oxidation of ammonia (NH₃) with N₂O were studied using the B3LYP/6-31++G** method of density functional theory (DFT). The results reveal that the reaction between N₂O and NH₃ proceeds through a chain reaction mechanism. N₂O reacts with NH₃ to form N₂ and NH₃O first and then NH₃O decomposes into NH₃ and O. This process corresponds to the apparent reaction N₂O+M=N₂+O+M (M=NH₃), but the energy barrier of the process (183.49 kJ/mol) is much lower than the direct decomposition reaction of N₂O=N₂+O (279.05 kJ/mol). The O radical produced in this process reacts subsequently with NH₃ and N₂O to produce more radicals such as NH₂, OH, and NO, which will take part in further reactions like NH₃+OH=NH₂+H₂O and NH₂+NO=N₂+H₂O until the reactants are consumed.