簡易檢索 / 詳目顯示

回結果列表
研究生： 涂宏旗
Hung-Chi Tu
論文名稱： 直接甲醇燃料電池模擬及其觸媒合成之研究
Studies of Simulation and Catalyst Preparation for Direct Methanol Fuel Cell
指導教授： 萬其超
Chi-Chao Wan
王詠雲
Yung-Yun Wang
口試委員:
學位類別： 博士
Doctor
系所名稱： 工學院 - 化學工程學系
Department of Chemical Engineering
論文出版年： 2006
畢業學年度： 94
語文別： 英文
論文頁數： 139
中文關鍵詞： 甲醇 、燃料電池 、觸媒 、數學模擬
外文關鍵詞： Methanol, Fuel cell, Catalyst, Simulation
相關次數： 點閱：3  下載：0 
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報

    • 直接甲醇燃料電池(DMFC)以其高能量密度(~ 5000 Wh L-1)以及較低操作溫度(室溫到60oC之間)的優勢，成為攜帶型能源的明日之星。目前在其商業化的過程中，主要的瓶頸來自於薄膜電極組(MEA)的低發電效率與高觸媒使用量。然而，這些問題的成因十分複雜，舉凡操作條件、材料組成、MEA結構、製造過程等均具有一定的影響性。而本論文的研究重點在於探討DMFC三個重要問題：甲醇滲漏(methanol crossover)、觸媒合成以及陰極的產物-水所造成的影響。
    首先，我們發展出一個具物理意義的DMFC放電曲線半經驗式(semi-empirical equation)，並藉由此半經驗式，個別地解析出陰極與陽極的各種過電位(overpotential)以及甲醇滲漏所造成的電位損耗。在公式驗證方面，我們設計三種實驗，再利用曲線契合(curve fitting)獲得所需的參數值，而模擬出來的放電曲線十分吻合實際實驗的測量值。最後藉由探討參數變動對放電曲線造成的影響，觀察每個參數和各種現象之間的關係，結果發現最主要的電位損耗應是來自於兩極的活化過電位(activation overpotential)。
    另外，我們也嘗試使用本實驗室所發展的疏水性觸媒合成方法，進行合成Pt-Ru雙元金屬觸媒的研究。以XRD、TEM/EDX 和SEM對此觸媒的特性進行分析，結果發現此觸媒均勻分散(粒徑約4nm)在有機相中，且具有富含Pt的面心立方(fcc)結構。然而，此觸媒無需添加Nafion即對疏水性物質具有良好的吸附性，且經適當處理後，能呈現良好的電化學活性。因此，我們認為此觸媒合成方式相當有潛力被應用在合成DMFC陽極所使用的觸媒。
    最後，本論文利用擬穩態(pseudo steady state)的概念，發展出可應用在質子交換膜型燃料電池(PEMFC)的動態模型(dynamic model)。其模擬結果顯示只有當階升電流(step-current)發生的初期才會發生動態變化，隨著時間增加，燃料電池內部與其效能將會達到新的穩態。而模擬結果也顯示電位的動態變化只與液態飽和度(liquid saturation)以及氧氣的濃度有關，幾乎不受水蒸氣濃度的影響。此外，穩態操作下突然發生的動態變化，也可以藉由此模型，在進料反應物的液態飽和度突然變化的情形下，加以預測。相信此模型，將可做為未來發展DMFC動態模型的依據。

    Direct methanol fuel cell (DMFC) is a good portable power source due to its low operating temperature (room – 60 oC) and high energy density (~ 5000 Wh L-1). At present, low power density and high catalyst loading of the membrane electrode assembly (MEA) are the major barriers that inhibit its commercialization. However, the behaviors inside the MEA are extremely complicated and are heavily dependent on the operation condition, the constituting materials, MEA structure, and the manufacture procedure etc. In this dissertation, we focus on some key issues, methanol crossover, the properties of catalyst and water management for DMFC.
    First, a semi-empirical equation was proposed to simulate the discharging behavior of direct methanol fuel cell (DMFC). The individual voltage losses in DMFC due to methanol crossover and overpotentials of both cathode and anode can be distinguished as well. Three sets of experiments were designed and carried out to account for the three voltage losses. Values of each parameter in the model were then calculated and the computation showed the fitted result and the experimental data were well matched. The relation between each significant phenomenon and each parameter was also discussed. The model quantitatively identified the major voltage losses to be both the sluggish reaction of methanol oxidation on the anode and the slow oxygen reduction on the cathode. Impact on cell performance by manipulating individual parameter was also issued.
    Then, a new process to synthesize unsupported Pt-Ru colloid was introduced. The characteristics of synthesized nanoparticles were identified by XRD, TEM/EDX and SEM and it shows that Ru atoms are incorporated into Pt fcc structure and the well-dispersed particles (diameter approx. 4 nm) possess Pt-rich feature. This catalyst shows hydrophobic characteristic which can adsorb very well on the hydrophobic-treated carbon paper or carbon cloth without the need of Nafion. Accordingly, this method can avoid particle agglomeration and the synthesized catalyst demonstrates strong adsorption with carbon paper. In addition, this colloid-type Nafion-free catalyst was measured via linear sweep voltammetry (LSV) and exhibited electrochemical activity for methanol oxidation comparable to the commercial one with Nafion binding. It shows high potential to be applied in the DMFC anodic catalyst layer.
    Finally, a dynamic model for PEMFC was established on macroscopic scale. This model combines a pseudo steady state model with a time-dependent calculation procedure. To describe the relation between water vapor and liquid water, the evaporation was taken into account and a useful equation for the evaporation rate coefficient was derived. The simulation results successfully demonstrate the dynamic response of cell voltage when a current-step change occurs. The dynamic changes only happen at the initial stage of current-step change and the results also indicate that the dynamic response of cell voltage deeply depends on the liquid saturation and oxygen concentration. Moreover, the sudden variation of cell voltage under steady-state operation was simulated by the present model with a pulse change of inlet liquid saturation.

    誌謝辭 I Abstract II 摘要 IV Content VI List of Figures -IX List of Tables -XIII Chapter 1 Introduction of Fuel Cells 1 1-1 Development Background of Fuel Cells 3 1-2 Fuel Cells Nowadays 9 Chapter 2 Literature Review 15 2-1 Polymer Electrolyte Membrane Fuel Cells (PEMFC) 15 2-1.1 Flow Field and GDLs 15 2-1.2 Polymer electrolyte membrane (PEM) 16 2-1.3 Catalyst of PEMFC 19 2-2 Direct Methanol Fuel Cell (DMFC) 20 2-2.1 Catalysts of DMFC 21 2-2.2 Membrane of DMFC 25 2-3 Model Review 27 2-3.1 Semi-empirical models 28 2-3.2 The mathematical models 31 2-4 Review of Synthesis methods of Pt-Ru Catalyst 41 2-5 Motivation 44 Chapter 3 Semi-empirical Model to Elucidate the Effect of Methanol Crossover on Direct Methanol Fuel Cell 47 3-1 Theoretical Derivation 47 3-2 Experimental and Numerical Fitting Procedure 54 3-2.1 Experimental design 54 3-2.2 Calculation Procedure 56 3-3 Results and Discussions 58 3-3.1 Model validations 58 3-3.2 Cathodic and anodic polarization curve 62 3-3.3 Cell voltage loss due to individual overpotentials 63 3-3.4 Impact of individual parameter on the cell performance 65 3-4 Conclusions 70 Nomenclatures 72 Chapter 4 The Synthesis of Hydrophobic Pt-Ru Nanoparticles and Its Application to Preparing Nafion-free Anode for DMFC 74 4-1 Experiments 74 4-1.1 Catalyst preparation and identification 74 4-1.2 Electrochemical characterization 75 4-2 Results and Discussions 77 4-2.1 Characterization of Pt-Ru nanoparticles 77 4-2.2 Electrochemical properties of hydrophobic Pt-Ru catalysts 81 4-2.3 The effects of acetone immersion with different immersing period 86 4-2.4 The potential of this present catalyst for the anode of DMFC 88 4-3 Conclusions 91 Chapter 5 Dynamic Model for Current-Step Change in Polymer Electrolyte Membrane Fuel Cell 92 5-1 Theoretical Derivation 93 5-1.1 The Pre-assumptions under the Pseudo Steady-State 93 5-1.2 The Conservation of Water 94 5-1.3 The Evaporation Coefficient of Water 96 5-1.4 The Conservation of Oxygen 99 5-1.5 The Electrochemical Kinetics 99 5-1.5 The Time-dependent Changes of Average Liquid Saturation and Oxygen Concentration 100 5-2 Calculation Procedure 103 5-3 Results and Discussions 107 5-3.1 The responses for indexes in current-step simulation 107 5-3.2 The effects of parameters, RH, T, □c and □ 115 5-3.3 The simulation of the discontinuous response 122 5-4 Conclusions 125 Nomenclatures 126 Chapter 6 Conclusions 128 References 130 Appendix 138 About the Author 140

    1. M. L. Perry, T. F. Fuller, J. Electrochem. Soc., 149, S59-S67 (2002).
    2. R. Seymour, J. Matthey, Fuel Cell Today (2004).
    3. F. Preli, Fuel Cells, 1, 5-9 (2002)
    4. P. Hoffmann, The Hydrogen & Fuel Cell Letter, May 2004 issue (2004).
    5. K. A. Adamson, G. Crawley, D. Jollie, Fuel Cell Today (2006).
    6. L. Carrette, K. A. Friedrich, U. Stimming, CHEMPHYSCHEM, 1, 162-193 (2000).
    7. L. Carrette, K. A. Friedrich, U. Stimming, Fuel Cells, 1, 5-39 (2001).
    8. P. Costamagna, S. Srinivasan, J. Power Sources, 102, 242-252 (2001).
    9. S. Wasmus, A. Küver, J. Electroanal. Chem., 461, 14-31 (1999).
    10. M. Neergat, D. Leveratto, U. Stimming, Fuel Cells, 1, 25-30 (2002).
    11. P. Hoffmann, The Hydrogen & Fuel Cell Letter, November 2003 issue, 1-5 (2003).
    12. C. C. Chan, 2003 Taipei Power Forum & Exhibition, Section A-6 (2003).
    13. K. A. Adamson, G. Grawley, Fuel Cell Toady (2006).
    14. http://www.toyota.com
    15. D. L. Reichert, 2003 Taipei Power Forum & Exhibition, Section F-1 (2003).
    16. A. Baker, D. Jollie, K. A. Adamson, Fuel Cell Toady (2005).
    17. Y. M. Peng, 2004 Taipei Power Forum & Exhibition, Section F-2 (2004).
    18. M. Arita, Fuel Cells, 1, 10-14 (2002).
    19. K. A. Adamson, Fuel Cell Toady (2005).
    20. P. Costamagna, S. Srinivasan, J. Power Sources, 102, 253-269 (2001).
    21. J. L. Cohen, D. A. Westly, A. Pechenik, H. D. Abruña, J. Power Sources, 139, 96-105 (2005).
    22. J. L. Cohen, D. J. Volpe, D. A. Westly, A. Pechenik, H. D. Abruña, Langmuir, 21, 3544-3550 (2005).
    23. C. H. Hsu, “Study of MEA process and simulation for PEM fuel cells”, Ph. D thesis, National Tsing Hua University (2003).
    24. A. S. Arico, S. Srinivasan, V. Antonucci, Fuel Cells, 1, 133-161 (2001).
    25. C. Yang, P. Costamagna, S. Srinivasan, J. Benziger, A. B. Bocarsly, J. Power Sources, 103, 1-9 (2001).
    26. I. D. Raistrick, US Patent No. 4,876,115 (1989).
    27. K. Sundmacher, T. Schultz, S. Zhou, K. Scott, M. Ginkel, E. D. Gilles, Chemical Engineering Science, 56, 333-341 (2001).
    28. P. S. Kauranen, E. Skou, J. Munk, J. Electroanal. Chem., 404, 1-13 (1996).
    29. P. S. Kauranen, E. Skou, J. Electroanal. Chem., 408, 189-198 (1996).
    30. A. V. Tripković, K. Dj. Popović, J. D. Mončilović, D. M. Dražić, J. Electroanal. Chem., 448, 173-181 (1998).
    31. J. Munk, P. A. Christensen, A. Hamnett, E. Skou, J. Electroanal. Chem., 401, 215-222 (1996).
    32. C. Pu, W. Huang, K. L. Ley, E. S. Smotkin, J. Electrochem. Soc., 142, L119-L120 (1995).
    33. S. Srinivasan, E. A. Ticianelli, C.R. Derouin and A. Redondo, J. Power Sources, 22, 359-375 (1988).
    34. J. Kim, S. M. Lee, S. Srinivasan, C. E. Chamberlin, J. Electrochem. Soc. 142, 2670-2674 (1995).
    35. G. Squadrito, G. Maggio, E. Passalacqua, F. Lufrano, A. Patti, J. Appl. Electrochem. 29, 1449-1455 (1999).
    36. D. Chu, R. Jiang, J. Power Sources 80, 226-234 (1999).
    37. K. Scott, P. Argyropoulos, K. Sundmacher, J. Electroanal. Chem. 477, 97-110 (1999).
    38. P. Argyropoulos, K. Scott, A. K. Shukla, C. Jackson, Fuel Cells, 2, 78-82 (2002).
    39. P. Argyropoulos, K. Scott, A. K. Shukla, C. Jackson, J. Power Sources, 123, 190-199 (2003).
    40. N. P. Siegel, “Development and Validation of a Computational Model for a Proton Exchange Membrane Fuel Cell”, Ph. D thesis, Virginia Polytechnic and State Institute (2003).
    41. T. E. Springer, T. A. Zawodzinski, S. Gottesfeld, J. Electrochem. Soc., 138, 2334-2342 (1991).
    42. A. J. Bard and L. R. Faulkner, “Electrochemical Methods: Fundamentals and Applications”, 2nd edition (2001).
    43. P. H. Rieger, “Electrochemistry”, 2nd edition (1994).
    44. R. B. Bird, W. E. Stewart, E. N. Lightfoot, “Transport Phenomena”, 1st edition (1960).
    45. M. C. Kimble, R. E. White, J. Electrochem. Soc., 138, 3370-3382 (1991).
    46. M. C. Kimble, R. E. White, J. Electrochem. Soc., 139, 478-484 (1992).
    47. T. V. Nguyen, R. E. White, J. Electrochem. Soc., 140, 2178-2186 (1993).
    48. S. F. Baxter, V. S. Battaglia, R. E. White, J. Electrochem. Soc., 146, 437-447 (1999).
    49. C. Marr, X. Li, J. Power Sources, 77, 17-27 (1999).
    50. J. J. Baschuk, X. Li, J. Power Sources, 86, 181-196 (2000).
    51. C. Y. Wang, P. Cheng, Int. J. Heat Mass Transfer, 39, 3607-3618 (1996).
    52. P. Cheng, C. Y. Wang, Int. J. Heat Mass Transfer, 39, 3619-3632 (1996).
    53. C. Y. Wang, W. B. Gu, J. Electrochem. Soc., 145, 3407-3417 (1998).
    54. W. B. Gu, C. Y. Wang, J. Electrochem. Soc., 145, 3418-3427 (1998).
    55. J. C. Slattery, AIChE J., 13, 1066-1071 (1967).
    56. J. C. Slattery, AIChE J., 15, 866-872 (1967).
    57. S. Whitaker, Transport in Porous Media, 1, 105-125 (1986).
    58. Z. H. Wang, C. Y. Wang, K. S. Chen, J. Power Sources, 94, 40-50 (2001).
    59. U. Pasaogullari, C. Y. Wang, J. Electrochem. Soc., 151, A399-A406 (2004).
    60. Z. H. Wang, C. Y. Wang, J. Electrochem. Soc., 150, A508-A519 (2003).
    61. J. Cruickshank, K. Scott, J. Power Sources, 70, 40-47 (1998).
    62. K. Sundmacher, K. Scott, Chemical Engineering Science, 54, 2927-2936 (1999).
    63. G. Murgia, L. Pisani, A. K. Shukla, K. Scott, J. Electrochem. Soc., 150, A1231-A1245 (2003).
    64. P. Argyropoulos, K. Scott, W. M. Taama, J. Power Sources, 79, 169-183 (1999).
    65. P. Argyropoulos, K. Scott, W. M. Taama, J. Power Sources, 79, 184-198 (1999).
    66. A. Simoglou, P. Argyropoulos, E. B. Martin, K. Scott, A. J. Morris, W. M. Taama, Chemical Engineering Science, 56, 6761-6722 (2001)
    67. J. Meyers, J. Newman, J. Electrochem. Soc., 149, A710-A717 (2002).
    68. J. Meyers, J. Newman, J. Electrochem. Soc., 149, A718-A728 (2002).
    69. J. Meyers, J. Newman, J. Electrochem. Soc., 149, A729-A735 (2002).
    70. A. Z. Weber, J. Newman, J. Electrochem. Soc., 150, A1008-A1015 (2003).
    71. A. Z. Weber, J. Newman, J. Electrochem. Soc., 151, A311-A325 (2004).
    72. A. Z. Weber, J. Newman, J. Electrochem. Soc., 151, A326-A339 (2004).
    73. P. Choi, R. Datta, J. Electrochem. Soc., 150, E601-E607 (2003).
    74. J. Fimrite, H. Struchtrup, N. Djilali, J. Electrochem. Soc., 152, A1804-A1814 (2005).
    75. A. A. Kulikovsky, J. Divisek, A. A. Kornyshev, J. Electrochem. Soc., 147,953-959 (2000).
    76. H. Dohle, A. A. Kornyshev, A. A. Kulikovsky, J. Mergel, D. Stolten, Electrochem. Comm., 3, 73-80 (2001).
    77. A. A. Kulikovsky, Electrochem. Comm., 3, 572-579 (2001).
    78. A. A. Kulikovsky, Electrochem. Comm., 4, 318-323 (2002).
    79. A. A. Kulikovsky, Electrochem. Comm., 4, 845-852 (2002).
    80. A. A. Kulikovsky, Electrochem. Comm., 4, 939-946 (2002).
    81. A. A. Kulikovsky, Electrochem. Comm., 5, 530-538 (2003).
    82. A. A. Kulikovsky, J. Electrochem. Soc., 150, A1432-A1439 (2003).
    83. A. A. Kulikovsky, Electrochem. Comm., 5, 1030-1036 (2003).
    84. T. Page, R. Johnson, J. Hormes, S. Noding, B. Rambabu, J. Electroanal. Chem., 485, 34-41 (2000).
    85. Z. Jusys, T. J. Schmidt, L. Dubau, K. Lasch, L. Jörissen, J. Garche, R. J. Behm, J. Power Sources, 105, 297-304 (2002).
    86. E. Antolini, F. Cardellini, J. Alloys and Compounds, 315, 118-122 (2001).
    87. K. Lasch, L. Jörissen, J. Garche, J. of Power Sources, 84, 225-230 (1999).
    88. Z. Jusys, J. Kaiser, R. J. Behm, Electrochimica Acta, 47, 3693-3706 (2002).
    89. X. Zhang, K. Y. Chan, Chem. Mater., 15, 451-459 (2003).
    90. L. S. Sarma, T. D. Lin, Y. W. Tsai, J. M. Chen, B. J. Hwang, J. of Power Sources, 139, 44-54 (2005).
    91. Z. Liu, J. Y. Lee, W. Chen, M. Han, L. M. Gan, Langmuir, 20, 181-187 (2004).
    92. W. L. Wang, Y. Y. Wang, C. C. Wan, C. L. Lee, Colloid and Surfaces, A: Physicochemical and Engineering Aspects, 275, 11-16 (2006).
    93. C. L. Lee, C. C. Wan, Y. Y. Wang, Adv. Funct. Mater., 11, 344-347 (2001).
    94. C. L. Hui, X. G. Li, I.-M. Hsing, Electrochimica Acta, 51, 711-719 (2005).
    95. L. Xiong, A. Manthiram, Solid State Ionics, 176, 385-392 (2005).
    96. S. Rojas, F. J. García-García, S. Järas, M. V. Martínez-Huerta, J. L. García Fierro, M. Boutonnet, Appl. Catal. A: Gen., 285, 24-35 (2005).
    97. A. A. Kulikovsky, H. Scharmann, K. Wippermann, Electrochem. Comm., 6, 75-82 (2004).
    98. U. Krewer, K. Sundmacher., J. Power Sources, 154, 153-170 (2005).
    99. .K. T. Jeng, C. W. Chen, J. Power Sources, 112, 367-375 (2002).
    100. R. Jiang, D. Chu, J. Electrochem. Soc., 151, A69-A76 (2004).
    101. R. Jiang, D. Chu, Electrochem. Solid-State Lett., 5, A156-A159 (2002).
    102. A. A. Kulikovsky, Fuel Cells, 2, 162-169 (2001).
    103. T. J. Schmidt, H. A. Gasteiger, R. J. Behm, Electrochem. Comm., 1, 1-4 (1999).
    104. S. Lj. Gojković, T. R. Vidaković, Electrochimica Acta, 47, 633-642 (2001).
    105. S. Mukerjee, R. C. Urian, Electrochimica Acta, 47, 3219-3231 (2002).
    106. M. Umeda, M. Kokubo, M. Mohamedi, I. Uchida, Electrochimica Acta, 48, 1367-1374 (2003).
    107. A.S. Arico, P. Creti, H. Kim, R. Mantegna, N. Giordano, V. Antonucci, J. Electrochem. Soc., 143, 3950-3959 (1996).
    108. M.-S. Löffler, H. Natter, R. Hempelmann, K. Wippermann, Electrochimica Atca, 48, 3047-3051 (2003).
    109. Q. Lu, B. Yang, L. Zhuang, J. Lu, J. Phys. Chem. B, 109, 8873-8879 (2005).
    110. F. Bensebaa, A. A. Farah, D. Wang, C. Bock, X. Du, J. Kung, Y. L. Page, J. Phys. Chem. B, 109 (2005) 15339-15344.
    111. B. C. Chan, R. Liu, K. Jambunathan, H. Zhang, G. Chen, T. E. Mallouk, E. S. Smotkin, J. Electrochem. Soc., 152, A594-A600 (2005).
    112. P. Choi, N. H. Jalani, R. Datta, J. Electrochem. Soc., 152, E123-E130 (2005).
    113. K. Scott, W. M. Taama, P. Argyropoulos, J. Appl. Electrochem., 28, 1389-1397 (1998).
    114. S. Middleman, “An Introduction to Fluid Dynamics: Principles of Analysis and Design”, 1st edition (1998).
    115. S. Middleman, “An Introduction to Mass and Heat Transfer: Principles of Analysis and Design”, 1st edition (1998).

    無法下載圖示 全文公開日期 本全文未授權公開 (校內網路)
    全文公開日期 本全文未授權公開 (校外網路)

    QR CODE