Several alternatives to the existing process for ammonia synthesis, the Haber-Bosch Process, have been proposed in the past two decades, including the electrochemical synthesis in aqueous, molten salt or solid electrolyte cells. The present work reviews results of recent efforts (last 3 years) for the electrochemical synthesis of ammonia. An Electrochemical Haber-Bosch Process is also demonstrated. The proposed BaZrO3 – based protonic ceramic membrane reactor combines hydrogen production via the reactions of methane steam reforming and water-gas shift at the anode (Ni-composite) with ammonia synthesis from N 2 and protons (H + ) at the cathode (VN-Fe). Hydrogen extraction from the steam reforming compartment, enhances the thermodynamically limited methane conversions, whereas 5-14% of the protons pumped to the cathode, are converted to ammonia. The NH 3 synthesis reactor is combined with a protonic ceramic fuel cell to recover electricity and separate nitrogen from ambient air by exploiting by-product hydrogen.
Kyriakou V., Garagounis I., Vourros A. et al. An Electrochemical Haber-Bosch Process. Joule 4, 142-158 (2020)
