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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/3842


    Title: 氧化鋁擔載奈米金觸媒之製備與應用研究;Preparation and application of alumina-supported gold catalysts
    Authors: 廖建達;Chien-Ta Liao
    Contributors: 化學工程與材料工程研究所
    Keywords: 甲醇部份氧化;氧化鋁;金觸媒;partial oxidation of methanol;hydrogen;alumina;particle size effect;gold catalyst
    Date: 2004-06-30
    Issue Date: 2009-09-21 12:24:01 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本研究以氧化鋁為擔體,利用沈澱固著法製備成奈米氧化鋁擔體金觸媒(簡稱為Au/γ- Al2O3觸媒),同時利用感應耦合電漿原子放射光譜儀(ICP-AES)、氮吸附法、熱重分析(TGA)、X射線繞射分析儀(XRD)、掃描式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)、X-射線光電子分析儀(XPS)等各項儀器與分析技術,分別對擔體及觸媒進行鑑定,並利用甲醇部份氧化反應為為催化活性的測試,藉以評估奈米氧化鋁擔體金觸媒應用於質子交換膜燃料電池(PEMFC)的可行性。由ICP-AES 分析結果,顯示Au/γ- Al2O3觸媒的金載量取決於pH值及製備時氯化金溶液的濃度,在低於等電位點金可達到60 %;氮吸附分析指出,以沈澱固著法製備的Au/γ- Al2O3觸媒,BET比表面積幾乎不會受煅燒溫度及載量的影響。從XRD圖譜中,可發現不同沈澱劑所形成不同大小的金晶粒。從TEM分析結果,發現Au/γ- Al2O3觸媒製備時pH值若超過等電位點時,可形成金晶粒大小約4 nm,且均勻分散在擔體表面上。而XPS分析結果可發現,以沈澱固著法所製備的Au/γ- Al2O3觸媒,表面會形成氫氧化金沈澱,且隨著煅燒溫度的增加,會逐漸熱解成金屬態的金。經過反應活性的測試,我們找出最佳的操作變數為金載量需小於1 wt%、製備pH值為9、沈澱劑為Na2CO3、煅燒溫度為573 K。若以此條件所製備出的觸媒,於523 K下進行甲醇部份氧化反應,能得到最佳的甲醇轉化率與氫氣選擇率。與文獻上銅觸媒、鈀觸媒的催化結果做比較,Au/γ- Al2O3觸媒不僅催化活性高,且幾乎沒有CO氣體的產生。由此結果可看出奈米金觸媒對於催化甲醇部份氧化反應,能夠選擇性的抑制CO的產生,相信可應用在燃料電池的氫氣源供應。 In this work, γ-Al2O3 was used as a catalyst support. Nanosized Au/γ-Al2O3 catalysts were prepared by the deposition-precipitation method. The supported Au catalysts were characterized by inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray diffraction (XRD), thermogravimetric analyzer(TGA), nitrogen adsorption method , scanning electron microcopy (SEM), transmission elecron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The ICP-AES analysis indicates that gold loading is significantly affected by the preparation pH value. When the pH value is below isoelectric point of support precipitates reach 60% loading. The nitrogen adsorption analysis shows that the catalyst preparation procedure does not affect the surface area of the support. Furthermore , the TEM analysis demonstrates that the mean size of gold crystallites decreases with increasing pH value. Au/γ-Al2O3 catalysts was tested by the partial oxidation of methanol at 503-563K. The results indicate that the optimal preparations and operating conditions for best methanol conversion and hydrogen selectivity are 0.15 wt% in gold loading, 673 K in calcinations temperature, Na2CO3 in precipitation reagent, pH value 9 in prepared condition and 563K in reaction temperature. Moreover, compare to copper and palladium catalysts in POM reaction, Au/γ-Al2O3catalysts display good activity and highly CO selectivity. Nanosized Au/γ-Al2O3 catalysts may have an opportunity to apply in proton exchange membrane fuel cell.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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