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MOLYBDENUM DIOXIDE (Moo2)-BASED ANODE for LIQUID HYDROCARBON

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MOLYBDENUM DIOXIDE (Moo2)-BASED ANODE for LIQUID HYDROCARBON MOLYBDENUM DIOXIDE (MoO2)-BASED ANODE FOR LIQUID HYDROCARBON- FUELED SOFC APPLICATIONS By BYEONG WAN KWON A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY WASHINGTON STATE UNIVERSITY The Gene and Linda Voiland School of Chemical Engineering and Bioengineering AUGUST 2014 © Copyright by BYEONG WAN KWON, 2014 All Rights Reserved © Copyright by BYEONG WAN KWON, 2014 All Rights Reserved i To the Faculty of Washington State University: The members of the Committee appointed to examine the dissertation of BYEONG WAN KWON find it satisfactory and recommend that it be accepted. __________________________ Su Ha, Ph.D., Chair _________________________ M. Grant Norton, Ph.D. _________________________ Bernard Van Wie, Ph.D. ii Acknowledgement First and foremost, I would like to acknowledge my advisor and committee chair, Dr. Su Ha, who has encouraged, motivated, and inspired me in various ways during my Ph. D. studies. I would like to acknowledge Dr. M. Grant Norton, a member of the Boeing team and committee member, for his support and contributions to achieve the goal of this work. I would like to express my deepest appreciation to my committee members, Dr. Richard Zollars and Dr. Bernard Van Wie, for their willingness to serve in my committee and provide feedback in my research. I am also grateful to principal assistant, Diana Thornton, finance/budget coordinator, Jo Ann McCabe, and program coordinator, James Pogue, in The Gene and Linda Voiland School of Chemical Engineering and Bioengineering Department. They answered all my questions about the graduate program and supported my research efforts. I acknowledge my lab mates, Dr. Oscar G. Marin, Assistant Research Professor, graduate students, Shouzhen Hu, Christy Hou, Qian He, Kale Harrison, Christian Cuba Torres, Shyreya Shah, and Thai Grarcia Perez, good friends and colleagues with whom I spent time discussing not only research but also daily life. Finally, I would like to sincerely thank my parents, Ho Chun Kwon and Sung Bun Anh, younger brother and his wife, Byeong Chun Kwon and Soo Yuong Han, and younger sister, Dong Ki Kwon. It seems to me that everything is possible with your devoted support. iii MOLYBDENUM DIOXIDE (MoO2)-BASED ANODE FOR LIQUID HYDROCARBON- FUELED SOFC APPLICATIONS Abstract by Byeong Wan Kwon, Ph.D. Washington State University August 2014 Chair: Su Ha 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 iv 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 o performances for n-dodecane-fueled SOFC at 750 C. 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. v Table of Contents Acknowledgement ........................................................................................................................ iii Abstract ......................................................................................................................................... iv Nomenclature ............................................................................................................................... ix List of Tables .................................................................................................................................. x List of Figures ............................................................................................................................... xi Objective and Contribution ...................................................................................................... xix Chapter 1 Introduction ................................................................................................................. 1 References ........................................................................................................................ 12 Chapter 2 Background ............................................................................................................... 15 2.1 Solid oxide fuel cells (SOFCs) .................................................................................. 16 2.2 Direct liquid fuel SOFCs .......................................................................................... 24 2.3. Internal reforming-based SOFCs ........................................................................... 28 2.4 Molybdenum dioxide-based anode and its SOFC .................................................. 31 References ........................................................................................................................ 34 Chapter 3 Nickel-Based Anode with Microstructured MoO2 Reformer for Liquid Hydrocarbon-Fueled SOFCs ..................................................................................................... 39 3.1 Abstract ...................................................................................................................... 40 vi 3.2 Introduction ............................................................................................................... 42 3.3 Experimental ............................................................................................................. 43 3.4 Results and discussion .............................................................................................. 46 3.5 Conclusions ................................................................................................................ 57 References ........................................................................................................................ 68 Chapter 4 Molybdenum Dioxide-Based Anode for Solid Oxide Fuel Cell Applications ...... 70 4.1 Abstract ...................................................................................................................... 71 4.2 Introduction ............................................................................................................... 72 4.3 Experimental ............................................................................................................. 75 4.4 Results and Discussion .............................................................................................. 78 4.5 Conclusions ................................................................................................................ 88 References ...................................................................................................................... 102 Chapter 5 High-Performance Molybdenum Dioxide-Based Anode for Dodecane-Fueled Solid-Oxide Fuel cells (SOFCs)................................................................................................ 106 5.1 Abstract .................................................................................................................... 107 5.2 Introduction ............................................................................................................. 107 5.3 Experimenatal .......................................................................................................... 110 5.4 Results and Disscusion ............................................................................................. 113 vii 5.5 Conclusions .............................................................................................................. 120 References ...................................................................................................................... 131 Chapter 6 Sulfur Tolerance Studies of Molybdenum Dioxide-Based Anode for Liquid Hydrocarbon-Fueled SOFCs ..................................................................................................
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