Effect of Ca2Fe2O5 catalyst on the performance of DC-SOFC with semi-coke fuel
Semi-coke is an excellent candidate fuel for direct carbon-solid oxide fuel cell(DC-SOFC),and its gasification reaction rate with CO2 is the key factor that effects the performance of DC-SOFC fueled semi-coke.In order to improve the gasification reactivity of semi-coke with CO2,the Ca2Fe2O5 catalyst with perovskite structure has been prepared using citric acid sol-gel method.The morphology and structure of the Ca2Fe2O5 catalyst has been investigated using SEM,XRD,XPS,low-temperature nitrogen adsorption-desorption methods.The catalytic activity of Ca2Fe2O5 catalyst in the gasifica-tion reaction of semi-coke with CO2 has been studied by thermogravimetric measurements.The effect mechanism of the semi-coke fuel added Ca2Fe2O5 catalyst on the output performance of DC-SOFC has been investigated using Ag-GDC|YSZ|GDC-Ag electrolyte supported DC-SOFC.The results indicate that as the calcination temperature of the cata-lyst increases,the grain size of Ca2Fe2O5 catalyst gradually increases and the specific surface area decreases.The catalyst calcined at 750 ℃ has good dispersibility and a particle size of approximately 0.1 μm exhibits the best catalytic activity in the gasification reaction of semi-coke and CO2.Compared to the CaO and Fe2O3,the Ca2Fe2O5 catalyst structure has a higher concentration of adsorbed oxygen,which is more conducive to its catalytic effect.In the gasification reaction of semi-coke and CO2,the cyclic stability of Ca2Fe2O5 catalyst depends on the thermal stability of the catalyst structure.Dur-ing the cyclic use of the catalyst,the decrease in catalytic activity is mainly attributed to the encapsulation of inorganic ash in the semi-coke fuel.Research on the performance of DC-SOFC shows that when 10％Ca2Fe2O5 catalyst has been added to the semi-coke,the peak power density of the cell increases from 15.3 mW/cm2 to 23.7 mW/cm2.The EIS analysis shows that the anode mass transfer resistance is the main factor affecting the output performance and fuel utilization of DC-SOFC.Reducing the mass transfer resistance caused by the accumulation of ash and catalyst can effectively improve the DC-SOFC life and fuel utilization.
direct carbon-solid oxide fuel cellperovskitecatalystC-CO2 gasification reactivity
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