奈米金觸媒在對氯硝基苯氫化反應的研究; noun

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题名:	奈米金觸媒在對氯硝基苯氫化反應的研究;noun
作者:	褚雅婷;Chu,Ya-ting
贡献者:	化學工程與材料工程學系
关键词:	奈米金觸媒;二氧化鈦;液相氫化反應;對氯硝基苯;Nanoalloy gold catalyst;titanium-oxide;hydrogenation;chloronitrobenzene
日期:	2013-06-26
上传时间:	2013-07-10 11:51:18 (UTC+8)
出版者:	國立中央大學
摘要:	奈米金觸媒於對-氯硝基苯氫化反應上有極佳的反應活性及選擇性。本研究中，首先探討奈米金擔載於不同擔體上在對-氯硝基苯氫化反應上活性的差異。再來比較金與不同金屬形成雙金屬擔載於二氧化鈦後，用於對-氯硝基苯氫化反應上活性的差異。最後比較不同比例之金鈀形成雙金屬擔載於二氧化鈦上，探討其在對-氯硝基苯氫化反應上活性的影響。不同擔體方面，以沉積沉澱法將金擔載於擔體上。而雙金屬觸媒部分，先以沉積沉澱法分別加入金與不同金屬，最後以硼氫化鈉還原之。製作不同金屬與不同比例之金鈀觸媒，探討最佳比例的反應觸媒。以X光繞射儀、穿透式電子顯微鏡、高解析度穿透式電子顯微鏡、X光能譜散佈分析儀、X光光電子能譜儀和程式升溫還原分析法等儀器鑑定觸媒之物理、化學特性和表面性質；利用液相選擇性對-氯硝基苯氫化反應來測試觸媒的活性與選擇性，反應條件設定為：反應器為半批式反應器(Parr Reactor 4842)；反應溫度為373 K與室溫；壓力為1.1 MPa與0.55 MPa；攪拌速率300 rpm；反應溶劑為甲醇；反應時間180分鐘；反應起始之p-CNB濃度為0.2M (2.54 g p-CNB溶於80 ml甲醇)；反應觸媒為0.5 g。結果顯示，不同擔體中以二氧化鈦反應活性最佳，雙金屬中則以加入鈀的觸媒反應活性與選擇性為最好，且加入少量的鈀，可以提升反應活性與選擇性。在金與鈀不同比例的觸媒比較中，相同反應條件下p-CNB轉化率都能在短時間內達到100%，甚至可降低反應環境條件，達到低壓且常溫下發生反應。根據鑑定結果分析，可看出加入鈀金屬之後可降低金觸媒的氧化態、增加反應活性基點且硼的氧化物可保護金顆粒避免氧化。因此，利用金觸媒的良好選擇性與鈀觸媒提高轉化率可使觸媒應用更將廣泛。 Nano-gold catalyst has been reported to have high activity and selectivity for liquid phase hydrogenation reaction. In this study, gold was loaded on different supports. The gold-containing bimetals were loaded on titanium-oxide. The catalyst was then optimize the molar ratio of Pd to Au on TiO2 for p-CNB hydrogenation reaction to have high activity.The monometallic Au catalysts were made by deposition-precipitation method. For bimetallic catalysts, gold and different metal solutions were added by the deposition-precipitation method, using NaBH4 to reduce them. Different metals and different molar ratios of Pd/Au were tested to find the high activity for p-CNB hydrogenation reaction. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy(XPS) and temperature programmed reduction (TPR). The catalytic properties of these catalysts were studied for hydrogenation of p-chloronitrobenzene (p-CNB). The conditions for hydrogenation reaction were 1.1 MPa and 0.55 MPa as H2 pressure, 373 K and room temperature as reaction temperature and 300 rpm stirring speed. Methanol was used as the solvent, the concentration of p-CNB was 0.2 M (2.54 g p-CNB in 80 ml methanol) and the amount of gold based catalyst was 0.5g. As results, titanium-oxide had a higher reaction activity than others, and adding palladium into gold base catalysts showed the high activity and selectivity. Comparing with different metals, adding palladium showed obviously a higher activity and selectivity. All of Pd/Au catalysts could reach 100% conversion of p-CNB on the same reaction conditions in short times. The reaction even It also could take place at room temperature and low hydrogen pressure. Only very small amount of palladium could improve the reaction activity and selectivity. According to the characteristics of the catalysts, adding palladium could reduce gold-valence state, increase reaction active sites. Therefore, gold and palladium catalysts could promote conversion and selectivity for hydrogenation reaction.
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