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Permanent link (DOI): https://doi.org/10.7939/R3J99B
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VOx /TiO2 anode catalyst for oxidation of CH4 containing 5000 ppm H2S in SOFC Open Access
- Other title
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Garcia Rojas, Alfonso Andres
- Supervisor and department
- Examining committee member and department
Jingli Luo (Chemical and Materials Engineering)
Vinay Prasad (Chemical and Materials Engineering)
Stojan Djiokic (Chemical and Materials Engineering)
Department of Chemical and Materials Engineering
- Date accepted
- Graduation date
Master of Science
- Degree level
In this research, LSB10T/YSZ composite anode with VOx/TiO2 is used to improve the electrochemical performance, coking resistance and sulfur tolerance of high temperature SOFC fed by 5000 ppm H2S containing methane.
The ionic and electronic conductivities of La0.4Sr0.5Ba0.1TiO3 were studied with blocking electrodes. Sintering at reducing conditions leads to an increment of the total and electronic conductivity due to reduction of the oxidation state of Ti. On the other hand, sintering at oxidizing conditions increases the ionic conductivity due to the effect of barium on the enlargement of the free volume of the perovskite. Nonetheless, despite of this increment, the electronic conductivity prevails. When LSB10T was impregnated inside a porous YSZ matrix, an electronic conducting layer made of LSB10T covers the matrix, impeding the normal migration of oxide ions.
SOFC using hydrocarbon fuels suffer from carbon deposition on the surface of the anode and poisoning of the catalyst. Eventually, this deposition accelerates the degradation of the anode and decreases the overall electrochemical performance of the cell. For this reason, catalysts with high oxidizing activities are needed to avoid the formation of free carbon and further deposition.
In attempt to improve the activity of the composite anode, LSB10T /YSZ, small concentration of VOx/TiO2 was infiltrated. VOx/ TiO2 exhibits good activity for oxidation of sour gas and methane without detectable sulfur deposition or sulphidation. Furthermore, the TiO2 enhances thermal stability of the active phase VOx, ascribed to the relative electronegativity and affinity between the active phase and the support. Radiographic characterization shows that the active phase, VOx comprises mainly vanadate entities. The enhancement on the catalytic oxidation of hydrocarbons conducts to high power density and low polarization. Finally, the presence of VOx/TiO2 inside the composite anode LSB10T /YSZ enhances the electrochemical performance of the SOFC, the coking resistance of the anode, keeping the good sulfur tolerant of the composite.
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