(685g) N2 Cold DBD Plasma Activation and Low Pressure Large Scale NH3 Synthesis Process Design

Engineering sustainable NH3 synthesis methods is of utmost importance and a lot of focus has been on fundamental catalyst and the corresponding reactor development. Lacking is the rational process design of any plasma based NH3 process that would answer engineering questions whether any catalytic plasma NH3 synthesis process, is still economically viable. In this work, NH3 synthesis using DBD plasma reactor followed by the the substitution of the conventional NH₃ reactor operating at 160 bar with a dielectric discharge barrier (DBD) plasma reactor operating at atmospheric pressure was performed using the overall process design approach and the corresponding environmental impact assessment was calculated using Life Cycle Analysis. In particular, a plasma DBD NH₃ reactor was modeled to operate at near atmospheric pressure and 150 °C using a forming gas obtained in the conventional methane reforming unit to obtain ∼1600 tonnes/day of liquid NH₃ for large-scale fertilizer production. The resulting gaseous effluent was compressed to 25 bar and expanded to cool down and condense gaseous NH₃ product resulting in a significant pressure decrease across the process. However, state-of-the-art reported N₂ per pass conversion of 5–10% used in the current model results in large recycle and high compressor work. The single limiting factor preventing the favorable process economics was very high-energy consumption to generate plasma requiring ∼1758 MWe at the reported 37.9 g/kWh, which is the highest NH₃ yield reported in the literature for DBD plasma reactors. The model obtained suggested that $0.007/kWh electricity cost could result in a breakeven for such a process.