貴重金屬(釕、銠、鈀)修飾銅鋅基質觸媒於室溫啟動催化氧化性蒸氣甲醇重組製氫反應之研究

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研究生：	何建德 Chien-Te Ho
論文名稱：	貴重金屬(釕、銠、鈀)修飾銅鋅基質觸媒於室溫啟動催化氧化性蒸氣甲醇重組製氫反應之研究 The Study of Initiation of Oxidative Steam Reforming of Methanol for Hydrogen Production at Room Temperature over CuZn-based Catalysis Modified by Noble Metals(Ru, Rh and Pd)
指導教授：	黃鈺軫 Yuh-Jeen Huang
口試委員:
學位類別：	碩士 Master
系所名稱：	原子科學院 - 生醫工程與環境科學系 Department of Biomedical Engineering and Environmental Sciences
論文出版年：	2008
畢業學年度：	96
語文別：	英文
論文頁數：	122
中文關鍵詞：	室溫啟動、銅基質催化劑、甲醇蒸氣氧化重組
相關次數：	點閱：88 下載：0
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本研究使用共沉澱法製備支撐性Cu/ZnO觸媒、貴重金屬X/ZnO(X = Ru, Rh and Pd)觸媒和CuX/ZnO 觸媒，並以固定床觸媒測試四種不同甲醇重組為氫氣的反應 : 包含甲醇直接分解 (DM)，甲醇蒸氣重組 (SRM)，甲醇部分氧化 (POM) 和甲醇氧化性蒸氣重組反應 (OSRM)。測試結果發現，Cu/ZnO觸媒在POM與OSRM反應中顯示出此貴重金屬觸媒(X/ZnO)優異的活性；然而在POM和OSRM程序中，結合貴金屬的CuX/ZnO觸媒比Cu/ZnO觸媒在較低的反應溫度下啟動。CuRh/ZnO對於POM反應來說為最佳觸媒，且其可在423 K下展現高甲醇轉化率(CMeOH = 94.9%)、高氫氣選擇率(SH2 = 88.6%)和高一氧化碳選擇率(SCO > 10%)。此外，DM反應圖譜顯示CuX/ZnO觸媒比Cu/ZnO觸媒有更高的甲醇轉化傾向。這說明了在貴重金屬Ru、Rh和Pd加入之銅基質觸媒其POM反應中會引起甲醇直接分解而產生一氧化碳。
自發性氫氣產生過程已在本研究中被討論，其中CuX/ZnO觸媒可在室溫下啟動POM反應而CuRh/ZnO與CuPd/ZnO觸媒也可在室溫下啟動OSRM反應。在OSRM反應下的最佳觸媒為結合2%鈀金屬的銅基質觸媒 (Cu30Pd2/ZnO),且Cu30Pd1/ZnO與Cu30Pd2/ZnO觸媒皆可在室溫下啟動OSRM反應。對於Cu30Pd2/ZnO觸媒來說，OSRM反應的最佳條件為水醇比 = 1.3、氧醇比 = 0.5、溫度 = 483 K且GHSV = 60000 h-1。對於Cu30Pd2/ZnO觸媒來說，PdZn合金與SZC粒子的出現可改良反應穩定度與氫氣選擇率。
值得注意的是，在CuX/ZnO觸媒的同時監測X-ray吸收光譜中可顯示觸媒結構與反應活性的關係。同時監測X-ray吸收實驗清楚顯示出在POM與OSRM反應活性中，Cu(Ⅰ)物種為主要的活性位置。觸媒型態與表面特質可經由程溫技術與X-ray繞射實驗而鑑定。

Contents

Abstract in Chinese
Contents                                                 Ⅰ
List of Tables                                        Ⅳ
List of Figures                                        Ⅴ
Chapter 1 Background and Introduction        1
    1-1 Use of the energy                 1
    1-2 Fuel cells                          2
    1-3 Advantages and applications of fuel cells                                                      3
    1-4 Proton exchange membrane fuel cell                                                      7
    1-5 Methanol reforming reactions        14
    1-6 Paper review                          15
    1-7 Motivation and approaches        18
    1-8 References                          19
Chapter 2 Experimental Section                 23
    2-1 Chemicals and solutions                 23
    2-2 Inductively coupled plasma-Mass spectrometer (ICP-MS)                                            23
    2-3 X-ray powder diffractometer (XRPD)       26
    2-4 Transmission electron microscopy (TEM)   27
    2-5 Vacuum system and nitrogen physical adsorption                                            28
    2-6 Temperature programmed reduction (TPR)   31
    2-7 Temperature programmed oxidation (TPO)   33
    2-8 X-ray Absorption Spectroscopy (XAS)      33
    2-9 Catalyst preparation                 35
    2-10 Catalytic activity                 36
    2-11 References                          41
Chapter 3 Hydrogen production from methanol reforming on CuX/ZnO (X = Ru, Rh and Pd) Catalysts        42
  3-1     Physical characteristics of catalysts    42
3-2    Temperature programmed reduction (TPR) characterization of fresh         catalysts        43
    3-3    X-ray diffraction (XRD) characterization of fresh catalysts                                   45
    3-4    In-situ XANES spectra of CuX/ZnO catalysts                                            47
    3-5    POM process over prepared catalysts                                                     58
    3-6    OSRM process over prepared catalysts                                                      61
    3-7    Cu K edge EXAFS analyze        67
    3-8    Conclusions                          71
  3-9    References                           71
Chapter 4 Effect of Pd Loading of CuZn-based Catalysts in the Oxidative Steam Reforming of Methanol        75
    4-1    Characterization of prepared catalysts                                             76
    4-2    Catalytic performances of CuPdx/ZnO at OSRM reaction                                    83
    4-3    Catalytic performances of CuPd2/ZnO at various x and w in OSRM reaction            90
    4-4    Conclusions                 94
4-5    References                          94
Chapter 5 Characterization of Redox Behaviors of Copper on CuZn-based Catalysts Promoted by Palladium        97
5-1    Physical properties of CuPdx/ZnO catalysts                                                      98
    5-2    Effect of palladium incorporation on reducibility of freshly calcined CuPd/ZnO catalyst        102
5-3    Effect of palladium incorporation on oxidation of reduced CuPd/ZnO catalysts        103
    5-4    Determination of Cu dispersion on CuPd/ZnO catalyst        108
    5-5    Durability of CuPd/ZnO catalyst for OSRM        116
    5-6    Conclusions        118
5-7    References        119
Chapter 6   Conclusions        121


Lists of Tables

Table 1-1 Summary of major differences of the fuel cell types     5
Table 1-2 Potential hydrogen storage materials    12
Table 1-3 Literature review for reforming methanol over Cu catalysts    17
Table 2-1 The chemicals used for this study    24
Table 2-2 Physical properties of copper, palladium, Ruthenium, Rhodium and Zinc oxide    25
Table 2-3 Experimental conditions of four reforming reactions over reduced CuX/ZnO catalysts    40
Table 3-1 Chemical composition and physical characteristics of prepared catalysts      44
Table 3-2 Speciation parameters (studied by in-situ EXAFS) of copper in CuRh/ZnO catalyst.                                                               68
Table 4-1 Chemical composition and physical characteristics of prepared catalysts
                                                                  78
Table 4-2 OSRM results of prepared catalysts of Pd/ZnO, Cu/ZnO and CuPd/ZnO and references    86
Table 4-3 The ignition temperature of OSRM of prepared CuPdx/ZnO catalysts    89
Table 5-1 Chemical composition and physical characteristics of prepared catalysts
    99
Table 5-2 TPR results of CuPdx/ZnO catalysts     107
Table 5-3 TPO results of CuPdx/ZnO catalysts     109

List of Figures

Figure 1-1    Chart to summarize the applications and main advantages of fuel cells of different types, and in different applications.        6
Figure 1-2     A chart of MEA consist of two electrodes, anode and cathode, and the polymer electrolyte.        8
Figure 1-3     A chart of MEA consist of two electrodes, anode and cathode, and the polymer electrolyte.        9
Figure 2-1     A chart of volumetric system.        30
Figure 2-2     A schematic diagram for the temperature programmed reduction system used in this study.        32
Figure 2-3     A schematic diagram for the reforming methanol system used in this study.        38
Figure 2-4     Schematic of in-situ X-ray absorption instrument.        39
Figure 3-1     TPR spectra of fresh catalysts of (a) Pd/ZnO (b) Ru/ZnO, and (c)
           Rh/ZnO.    48
Figure 3-2    TPR spectra of fresh catalysts of (a) Cu/ZnO, (b) CuPd/ZnO, (c) CuRu/ZnO and (d) CuRh/ZnO.        49
Figure 3-3    XRD patterns of fresh X/ZnO catalysts.        50
Figure 3-4     XRD patterns of fresh CuX/ZnO catalysts.        51
Figure 3-5     The XANES spectra of reduction of (a) CuRh/ZnO, (b) CuRu/ZnO and (c) CuPd/ZnO at 523 K.        53
Figure 3-6     The compound fits of in-situ XANES spectra of (a) CuRh/ZnO, (b) CuRu/ZnO and (c) CuPd/ZnO during catalytic POM reaction at 298 K. The dotted line denotes the best fits of XANES spectra.        54
Figure 3-7     The compound fits of in-situ XANES spectra of (a) CuRh/ZnO, (b) CuPd/ZnO and (c) CuRu/ZnO during catalytic POM reaction at 473 K. The dotted line denotes the best fits of XANES spectra.        55
Figure 3-8             The compound fits of in-situ XANES spectra of (a) CuRh/ZnO, (b) CuRu/ZnO and (c) CuPd/ZnO during catalytic OSRM reaction at 403 K. The dotted line denotes the best fits of XANES spectra.    56
Figure 3-9             The compound fits of in-situ XANES spectra of (a) CuRh/ZnO, (b) CuRu/ZnO and (c) CuPd/ZnO during catalytic OSRM reaction at 503K. The dotted line denotes the best fits of XANES spectra.    57
Figure 3-10         The temperature profile of catalytic activity in the partial oxidation of methanol over Cu/ZnO (□), CuRh/ZnO (●), CuRu/ZnO (▲) and CuPd/ZnO (◆) catalysts.    59
Figure 3-11     The temperature profile of catalytic activity in the decomposition of methanol over Cu/ZnO (□), CuRh/ZnO (●), CuRu/ZnO (▲) and CuPd/ZnO (◆) catalysts.    62
Figure 3-12         The temperature profile of catalytic activity in the oxidative steam reforming of methanol over Rh/ZnO (●), Ru/ZnO (▲) and Pd/ZnO (◆) catalysts.    64
Figure 3-13         The temperature profile of catalytic activity in the oxidative steam reforming of methanol over Cu/ZnO (□), CuRh/ZnO (●), CuRu/ZnO (▲) and CuPd/ZnO (◆) catalysts.    65
Figure 3-14         XRD patterns of fresh catalysts after reduced by 10% H2/N2, 30 ml/min at 523 K for 1 hr ; (a) CuRh/ZnO, (b) CuPd/ZnO and (c) CuRu/ZnO.
                66
Figure 4-1   XRD patterns of fresh CuPdx/ZnO catalysts.    79
Figure 4-2             The detailed XRD patterns of fresh CuPdx/ZnO catalysts at 2□ dispersed at 380 ~ 580.    80
Figure 4-3     TPR spectra of fresh catalysts of (a) CuPd1/ZnO, (b) CuPd2/ZnO and (c) CuPd4/ZnO.    82
Figure 4-4     Comparison of OSRM for Cu/ZnO (□), Pd/ZnO (▲) and Cu30Pd2/ZnO (●) as a function of temperature (w = 1.3, x = 0.25, GHSV = 60000 h-1).    85
Figure 4-5         A temperature profile of CMeOH, SCO and RH2 from OSRM reaction over CuPd1/ZnO (□), CuPd2/ZnO (●) and CuPd4/ZnO (▲) catalysts.    87
Figure 4-6     Effect of temperature on methanol conversion，CO selectivity and hydrogen yield at various steam to methanol molar ratio for CuPd2/ZnO catalyst (OSRM reaction, O/M = 0.25, P = 1 atm).    91
Figure 4-7     Effect of temperature on methanol conversion, CO selectivity and hydrogen yield at various oxygen to methanol molar ratio for CuPd2/ZnO catalyst (a) Methanol conversion (b) CO selectivity and (c) RH2 ( OSRM reaction, S/M = 1.3, P = 1 atm ).    93
Figure 5-1     The detailed XRD patterns of fresh CuPd1/ZnO and CuPd4/ZnO catalysts at 2□ dispersed at 200 ~ 400.    101
Figure 5-2     TPR spectra of freshly calcined Pd/ZnO and CuX/ZnO catalysts.    104
Figure 5-3     TPO spectra of reduced (a) Cu/ZnO and (b) CuPd2/ZnO.      105
Figure 5-4     TPR reduction spectra of samples oxidized at T0 = 150 K.     106
Figure 5-5     Schematic models for reduction phenomena observed from TPR of CuPdx/ZnO catalysts. (A) Reduction of a CuO crystallite on freshly calcined CuPdx/ZnO: (a) a CuO crystallite; (b) CuiO was reduced to Cui at Tr = 380 ~ 440 K; and (c) a complete reduction of CuO at Tr = 440 ~ 495 K. (B) Reduction of a Cus2O layer formed by oxygen chemisorption. (a) A Cus2O crystallite; (b) Cup2O was reduced at Tr = 360 ~ 420 K; (c) A complete reduction of Cus2O at Tr = 420 ~ 490 K.    110
Figure 5-6     Schematic model for oxidation of Cu to CuO crystallites dispersed on CuPdx/ZnO catalysts upon increasing To of oxidation treatment. (a) A dispersed Cu crystallite; (b) Oxidation of Cus at To = 123 ~ 223 K; (c) Oxidation of Cui at To = 223 ~ 323 K; (d) A complete oxidation of Cu crystallite at To = 323 ~ 623 K.    111
Figure 5-7     TPR spectra of reduced the Cu/ZnO with oxidation treatment at T0 = (a) 298 K, (b) 163 K and (c) 148 K.    113
Figure 5-8     TPR spectra of reduced the CuPd/ZnO with oxidation treatment at T0 = (a) 178 K, (b) 158 K, (c) 148 K, (d) 128 K and (e) 108 K.    114
Figure 5-9     Time-on-stream stability test of CuPd/ZnO catalyst (T = 473 K, GHSV = 60000 h-1, x = 0.25 and w = 1.3).    117

                                

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