Electrochemical synthesis of ammonia based on doped-ceria-carbonate composite electrolyte and perovskite cathode

Electrochemical synthesis of ammonia was investigated using a cobalt-free La(0.6)Sr(0.4)Fe(0.8)Cu(0.2)O(3-delta)-Ce(0.8)-sm(0.2)O(2-delta) (LSFCu-SDC) composite cathode and SDC-ternary carbonate composite electrolyte. La(0.6)Sr(0.4)Fe(0.8)-Cu(0.2)O(3-delta) and Ce(0.8)Sm(0.2)O(2-delta) were prepared via combined EDTA-citrate complexing sol gel and glycine nitrate processes, respectively, and characterised by X-ray diffraction (XRD). Ammonia was successfully synthesised from wet hydrogen and dry nitrogen under atmospheric pressure using Ni-SDC, SDC-carbonate and LSFCu-SDC composites as anode, electrolyte and cathode respectively. Ammonia formation was observed at 400, 425, 450 and 475 degrees C and the maximum rate of ammonia production was found to be 5.39 x 10(-9) mol s(-1) cm(-2) at 450 degrees C and 0.8 V. The AC impedance measurements were recorded before and after the ammonia synthesis in the range of temperature 400-475 degrees C. The formation of ammonia at the N(2) side together with stable current at 450 degrees C under constant voltage demonstrates that SDC-(Li/Na/K)(2)CO(3) composite electrolyte exhibits significant proton conduction at a temperature around 450 degrees C. (C) 2011 Elsevier BM. All rights reserved.