Study of cerium species in molten Li2CO3–Na2CO3 in the conditions used in molten carbonate fuel cells. Part I: Thermodynamic, chemical and surface properties

Author: Chauvaut V.   Albin V.   Schneider H.   Cassir M.   Ardéléan H.   Galtayries A.  

Publisher: Springer Publishing Company

ISSN: 0021-891X

Source: Journal of Applied Electrochemistry, Vol.30, Iss.12, 2000-12, pp. : 1405-1413

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Abstract

The chemical and surface behaviour of cerium oxide, a candidate material for MCFC applications is analysed in Li_2CO_3–Na_2CO_3 carbonate eutectic in reducing (H_2:CO_2:H_2O:CO) and oxidizing (O_2:CO_2) atmospheres. The electrochemical stability domains of cerium species are established at different temperature on the basis of thermochemical calculations. CeO_2 is the stable species whatever the acidity level in both the anode and cathode conditions; nevertheless, a partial solubility of Ce_2O_3 in CeO_2 can be predicted. The solubility of cerium and cerium oxide samples, determined by absorption spectrophotometry, is about 5 × 10^−4 mol kg^−1 in cathodic conditions and 3 × 10^−4 mol kg^−1 in anodic conditions. X-ray diffraction (XRD) confirmed the presence of CeO_2 at the surface of the samples. Incorporation of sodium species in the CeO_2 lattice is likely; the presence of Ce(III) in long endurance tests was detected by X-ray photoelectron spectroscopy (XPS).

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