Electrochemical oxidation of carbonaceous materials dispersed in molten carbonate
To enhance the electrochemical reactivity of coal slurries by operating at high temperature, a molten carbonate electrolyte (ternary eutectic of lithium, sodium and potassium carbonate) was employed. Anodic oxidation took place at an inert gold electrode, which also served as a current collector. An alumina-sheathed carbon dioxide/oxygen/gold half-cell served as the reference electrode, and a shielded graphite rod served as the counter electrode. The cell was operated at 500-900/sup 0/C. Other parameters experimentally investigated were: type and concentration of carbonaceous material, stirring rate, anode material, and purge gas composition. The open circuit potential data agreed well with theoretical values at temperatures of 700/sup 0/C and above. The current-voltage data at 700/sup 0/C showed that current densities of 100 mA/cm/sup 2/ could be achieved at overpotentials of approximately 0.5 volts. Measurement of the anode off-gas at 700/sup 0/C indicated that complete oxidation of carbon to carbon dioxide was achieved. Chemical loss of carbon by the Boudouard reaction was found to be substantial. In order for the system to be commercially attractive as a direct coal-fired fuel cell, the chemical loss of carbon would have to be reduced considerably. Passivation of the anode was sometimes encountered, and was caused by dissolved impurities originating from the coal. Fortunately, passivation was minimal in the low overpotential region (below 0.3 volts). A qualitative mechanistic analysis of the anode process concluded that the process occurred by means of both direct and indirect interactions between the anode and the carbon particles.
- Research Organization:
- Ohio State Univ., Columbus (USA)
- OSTI ID:
- 5493141
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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30 DIRECT ENERGY CONVERSION
CARBONACEOUS MATERIALS
OXIDATION
COAL
ELECTROCHEMICAL CELLS
PERFORMANCE TESTING
CARBON
CARBON DIOXIDE
CARBONATES
COAL FUEL CELLS
LOSSES
MOLTEN SALTS
SYNTHESIS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DIRECT ENERGY CONVERTERS
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUEL CELLS
FUELS
MATERIALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SALTS
TESTING
010400* - Coal
Lignite
& Peat- Processing
300505 - Fuel Cells- Electrochemistry
Mass Transfer & Thermodynamics