Plasma-enhanced NH3 synthesis over activated carbon-based catalysts: Effect of active metal phase

In this study, plasma-enhanced NH 3 synthesis over a series of M/AC (M = Ru, Co, Ni, and Fe) catalysts was investigated. The combination of the plasma and activated carbon (AC) enhanced the reaction performance compared with the reaction using plasma alone. The doping of active metal on AC further improved the reaction performance by up to 37.3%. The highest NH 3 concentration of 3,026.5 ppm was obtained over Ru/AC at a specific input energy (SIE) of 12.5 kJ/L, followed by Co/AC, Fe/AC, and Ni/AC. The highest energy efficiency of 0.72 g/kWh was achieved at an SIE of 8.0 kJ/L when using the Ru/AC catalyst. Catalyst characterizations showed that the basicity of the M/AC catalysts plays an important role in the plasma-enhanced catalytic synthesis of NH 3 . The reaction mechanism in the plasma-enhanced NH 3 synthesis was also discussed.