Oxidation of ash-free coal from sub-bituminous and bituminous coals in a direct carbon fuel cell

The present study proposes the production of ash-free coal (AFC) and its oxidation as a primary fuel in direct carbon fuel cells (DCFCs). The AFC was produced by the extraction of Arutmin sub-bituminous coal (AFC1) and Berau bituminous coal (AFC2) using polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). It was carried out at a temperature of around 202 A degrees C under atmospheric conditions and using a microwave irradiation method. Using NMP as the solvent showed the highest extraction yield, and the values of 23.53% for Arutmin coal and 33.80% for Berau coal were obtained. When NMP was added to DMSO, DMA and DMF, the extraction yield in the solvents was greatly increased. The yield of AFC from a sub-bituminous coal was slightly lower than that from a bituminous coal. The AFC was evaluated in a coin-type DCFC with a mixture of AFC and carbonate electrolyte (3 g/3 g) at 850 A degrees C. The AFC and gaseous H-2 fuels were compared using the electrochemical methods of steady-state polarisation and step chronopotentiometry. The DCFC ran successfully with the AFCs at 850 A degrees C. The open-circuit voltages were about 1.35 V (AFC1) and 1.27 V (AFC2), and the voltages at 150 mA cm(-2) were 0.61 V (AFC1) and 0.74 V (AFC2).