|Institution:||Washington State University|
|Keywords:||Chemical engineering; alternative anode material; coking formation; molybdenum dioxide; n-dodecane; solid oxide fuel cell; sulfur tolerance|
|Full text PDF:||http://hdl.handle.net/2376/5194|
This work is focused on the study of the molybdenum dioxide (MoO2) as an alternative anode material for liquid hydrocarbon-fueled solid oxide fuel cells (SOFCs). The starting point for this investigation was to improve the long-term stability of conventional Ni-based anode for dodecane fueled SOFC by introducing a novel microstructured MoO2 internal reformer. The previous work in our lab demonstrated that MoO2 was evaluated as an excellent catalytic material for reforming of gasoline and n-dodecane as a surrogate jet-A fuel. Our previous results indicated that the MoO2-based reformer had a high coking resistance and sulfur tolerance. Hence, the present work demonstrates that the Ni-based SOFC with an integrated MoO2 micro-reformer can effectively operate under the n-dodecane-fueled SOFC operating mode showing both high initial performance and outstanding tolerance to coking. However, the manufacturing process for Ni-based anodes with microstructured MoO2 reformer is currently too complicated and requires a high O2/C ratio to effectively operate. Using such high O2/C ratio is disadvantageous for the fuel cell because it lowers the fuel efficiency. Thus, researchers have studied alternative anode materials, which can overcome the limitation of Ni-based anodes when liquid fuels are used directly. The hypothesis in this work is that the mixed conductivities of molybdenum dioxide leads to a novel anode with high catalytic activity toward liquid fuel with high coke resistance and high sulfur tolerance. To test this hypothesis, MoO2 was tested as an alternative anode material and our experimental results exhibited that MoO2 can be used as a novel anode material with much higher initial cell performance, improved long-term stability and the enhanced coking resistance than that of the conventional Ni-based anode. Our results were in correspondence with this hypothesis and demonstrated that MoO2-based anodes showed better cell performances for n-dodecane-fueled SOFC at 750oC. In addition, the MoO2-based anode was tested for its sulfur tolerance and found that it shows a high sulfur tolerance against 500 ppm benzothiophene (i.e., a model sulfur compound) without affecting its overall cell performance.