Electrocatalytic synthesis of ammonia from steam and nitrogen at atmospheric pressure

The electrocatalytic synthesis of ammonia from steam and nitrogen was studied in oxygen ion (O2-) and proton (H+) conducting solid electrolyte cells at 450-700 degrees C and at atmospheric total pressure. A Ru-based industrial catalyst was used as the working electrode. In the H+ cell, steam was electrolyzed at the anode to produce protons and oxygen. Protons, transported to the cathode, reacted with nitrogen to produce ammonia. In the O2- cell, H2O and N-2 were fed in together at the cathode. Steam was electrolyzed and the produced hydrogen reacted with nitrogen. Ammonia formation was observed at temperatures between 500 and 700 degrees C. The conversions with respect to nitrogen or steam were low, primarily because of the poor conductivity of the working electrode. Both cells, however, exhibit promising features that make this alternative approach of NH3 synthesis worthy of further investigation. (C) 2009 Elsevier B.V. All rights reserved.