NH₃ synthesis in plasma catalysis using N₂ and H₂O at atmospheric pressure

NH₃ is currently produced by the Haber-Bosch process, which is a thermal catalysis under high temperature and pressure. This process uses a lot of energy, and the production of H₂, which is a raw material of NH₃, also emits a huge amount of CO₂. For this reason, the use of H₂ produced by electrolysis of water has been considered, but there are problems with high material and energy costs.

To solve these problems, several studies have been reported on processes that use water as a hydrogen source and react it with N₂ plasma to produce NH₃. We investigated plasma catalysis that act on atmospheric pressure N₂ plasma and H₂O on a catalyst to increase the production rate and reduce energy costs. Plasma catalysis is process in which a catalyst is irradiated with non-thermal equilibrium plasma, and can reduce the activation energy compared to thermal catalysis. In this study, Ru was used as the catalyst, and the state of the catalyst surface was evaluated by X-ray photoelectron spectroscopy (XPS), and the plasma characteristics were examined by optical emission spectroscopy. NH₃ was collected in water and the yield was quantified using the indophenol method. As a result, NH₃ was produced at low temperature below 60 °C and atmospheric pressure, and the energy cost was lower than that of the Haber-Bosch process. This process also has the advantage that it does not produce CO₂ because it uses H₂O as the hydrogen source.