Optimized Compounding Of Steel Slag-based Catalysts And Its Application In DC-SOFCs

Solid oxide fuel cells?SOFCs?are the power generation devices that can directly convert the chemical energy in fuels into electrical energy without combustion.They have got wide attention due to the advantages including high efficiency,low emissions and fuel diversity.Gas fuels such as hydrogen,carbon monoxide and natural gas,liquid fuels such as methanol and gasoline,and solid fuels such as activated carbon and biomass char,all can be used directly in SOFCs for power generation.Compared to other fuels,solid carbon fuels have great advantages,such as high volume energy density,high safety,easy for transportation and storage.And only carbon dioxide,which is easy to capture,is emitted as exhaust gas during the power generation process.Therefore,as the new generation of efficient and clean power generation technologies,SOFCs are of great significance for solving the problems of energy shortage and environmental pollution in China.The reaction of carbon with CO₂?C+CO₂=2CO?,i.e.the reverse Boudouard reaction,is one of the key reactions in DC-SOFCs.Steel slag is one type of industrial wastes containing a variety of metal elements that can catalyze the Boudouard reaction.In this paper,we use steel slag as the major raw material to prepare a composite catalyst with optimized molar ratio of potassium,iron and calcium of 2:6:4 for catalyzing the Boudouard reaction.The graphite loaded with the catalyst of 10 wt % was used as fuel in this paper.The electrochemical performance tests of the SOFCs were carried out.The results showed that the peak power density of the cell increased from 50 m W cm^-2to 170 m W cm^-2at 900 ?.At 850 ?,the constant current discharge time of the cell was extended from 6600 s to 18000 s.The utilization of the solid fuels increased from 2.68 % to 7.30 %.Subsequently,the four stages of DC-SOFCs constant current discharge were put forward,and the experiments were carried out to regulate the discharge current and discharge temperature of the cells,which proved the correctness of this conjecture.The walnut shell and its carbonized products were used as fuel to prove that the conjecture has broad applicability to carbon fuels.