Jin S  Yoo J  Rhee YW  Choi H  Lim J  Lee S

Vol. 18,  No. 4, pp. 426-431, Dec.  2012

Ash-free coal Direct carbon fuel cell Catalytic coal gasification Solid oxide fuel cell K2CO3

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Carbon-rich coal can be utilized as a fuel for direct carbon fuel cell (DCFC). However, left-behind ash after the electrochemical oxidation may hinder the electrochemical reactions. In this study, we produced ash-free coal (AFC) by thermal extraction and then tested it as a fuel for DCFC. DCFC was built based on solid oxide electrolyte and the electrochemical performance of AFC mixed with K2CO3 was compared with AFC only. Significantly enhanced power density was found by catalytic steam gasification of AFC. However, an increase of the power density by catalytic pyrolysis was negligible. This result indicated that a catalyst activated the steam gasification reactions, producing much more H2 and thus increasing the power density, compared to AFC only. Results of a quantitative analysis showed much improved kinetics in AFC with K2CO3 in agreement with DCFC results. A secondary phase of potassium on yttria-stabilized zirconia (YSZ) surface was observed after the cell operation. This probably caused poor long-term behavior of AFC with K2CO3. A thin YSZ (30 μm thick) was found to be higher in the power density than 0.9 mm of YSZ.