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The internal reforming of iso-octane is examined in a solid oxide fuel cell of the type Cu-CeO2/YSZ/Pt. The results show that i-C8H18 is efficiently reformed by H2O to syngas over Cu/CeO2 composites, free of carbon deposits. Apart from iso-octane reforming, the products distribution at open circuit conditions is also influenced by the associated i-C8H18 thermal cracking and catalytic decomposition reactions as well as by the reverse water gas shift and methanation reactions. At closed circuit operation, the prevailing reactions are related to the electro-oxidation of H2 and CO and the co-electrolysis of H2O and CO2, at anodic and cathodic polarization conditions, respectively. AC impedance spectroscopy studies revealed that the cell and electrode resistances are substantially decreased with increasing temperature leading consequently to higher maximum power densities (12.6 mW/cm2, 850oC). The diffusion of charged and/or neutral species at the electrode surface is possibly the rate limiting step during fuel cell operation.

In the present work the cell performance of an i-C8H18 internal steam reforming solid oxide fuel cell (SOFC) with Co/CeO2 as anodic electrode is presented. Initially, the catalytic activity of bi-metallic Cu-Co ceria-supported catalysts for i-C8H18 steam reforming was examined. In all cases, gas mixtures rich in Η2, CO, CO2 and CH4 were produced. Among all samples tested, the 20wt%Co/CeO2 catalyst exhibited the optimum catalytic performance achieving Η2 yields well exceeding 75% at 700 oC. In addition, the excellent durability of this catalyst was proven by long-term (23 h) stability experiments. To this end, the mono-metallic Co/CeO2 catalyst was selected to serve as the anodic electrode in the electro-catalytic and fuel cell tests. During the fuel cell measurements, the power output was found similar to that obtained when 10% H2/Ar mixtures were fed to the cell, indicating that Co/CeO2 can be considered as a promising anodic composite for direct hydrocarbon fed SOFCs.

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