For the first time, ammonia has been directly synthesised from wet air at intermediate temperature. Ce0.8Gd0.2O2-δ (CGO)-(Li,Na,K)2CO3 electrolyte together with a new perovskite oxide Pr0.6Ba0.4Fe0.8Cu0.2O3-δ were used for electrochemical synthesis of ammonia. An ammonia formation rate of 1.07×10-6mols-1m-2 was obtained at 400°C when applied a voltage of 1.4V, while wet air was introduced to the single chamber reactor. This is just slightly lower than the value of 1.83×10-6mols-1m-2 when wet N2 was fed under the same experimental conditions. These values are two to three orders of magnitude higher than the reported ammonia formation rates when synthesised from N2 and H2O at ~600°C. The perovskite catalysts are also low cost compared to the Ru/MgO and Pt/C catalysts in previous reports
Electrochemical synthesis of ammonia from water vapour and nitrogen was investigated using an electrolytic cell based on CoFe2O4-Ce0.8Gd0.18Ca0.02O2-δ (CFO-CGDC), CGDC-ternary carbonate composite and Sm0.5Sr0.5CoO3-δ-Ce0.8Gd0.18Ca0.02O2-δ (SSCo-CGDC) as cathode, electrolyte and anode respectively. CoFe2O4, CGDC and SCCo were prepared via a combined EDTA-citrate complexing sol-gel and characterised by X-ray diffraction (XRD). The AC ionic conductivities of the CGDC-carbonate composite were investigated under three different atmospheres (air, dry O2 and wet 5% H2-Ar). A tri-layer electrolytic cell was fabricated by a cost-effective one-step dry-pressing and co-firing process. Ammonia was successfully synthesised from water vapour and nitrogen under atmospheric pressure and the maximum rate of ammonia production was found to be 6.5 ×10-11 mol s-1 cm-2 at 400 ºC and 1.6 V which is two orders of magnitude higher than that of previous report when ammonia was synthesised from N2 and H2O at 650 °C.
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