Influence of selected coal contaminants on graphitic carbon electro-oxidation for application to the direct carbon fuel cell

Abstract

A novel method examining the fundamental electrochemical behaviour of carbon is outlined here involving the use of a half cell set-up and solid sacrificial anode. Using this method, electrochemical oxidation of graphite is assessed using selective contamination of a graphite electrode with major coal contaminants identified in selected Australian black coals using X-ray diffraction. Contaminants identified include anatase, alumina, pyrite, quartz, kaolin and montmorillonite. From the systematic introduction of these contaminants it is shown that clay materials, such as kaolin and montmorillonite, act catalytically to increase the rate of graphite oxidation. Metal oxides and sulfides such as anatase, alumina and pyrite give a limited increase in the normalised current, whereas quartz gives a significant decrease in performance. This demonstrates a clear effect of the solid phase interaction of these contaminants on the electrochemical oxidation of graphite since the same effect is not observed when the contaminants are added instead to the molten carbonate electrolyte.