奈米金觸媒在對氯硝基苯氫化反應之研究

奈米金觸媒於對-氯硝基苯氫化反應上有很好的催化活性和選擇性，此研究中，主要為利用添加劑(氧化鐵、氧化鋁、氧化鈰、氧化鎂、氧化錳和氧化鋯)對金觸媒於二氧化鈦在對-氯硝基苯氫化反應活性的影響。以氧化鐵為例，先以硝酸鐵含浸於二氧化鈦，之後以沉積沉澱法將金擔載於擔體上，製備一系列不同添加劑觸媒，以感應耦合電漿質譜儀、X光繞射儀、穿透式電子顯微鏡、X光能譜散佈分析儀、程式升溫還原分析法和X光光電子能譜儀等儀器鑑定其物理、化學特性和表面性質，並探討其物理與化學特性於對-氯硝基苯氫化反應上的影響，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，反應條件設定在：反應器為半批式反應器；反應溫度為353 K；壓力為1.2 MPa；攪拌速率500 rpm；反應溶劑為甲醇。結果顯示適量的添加劑加入，能強化觸媒的熱穩定度、活性位置的分散性，提升反應的活性和選擇率，改質後的金觸媒，其中以添加鐵之觸媒活性最好、選擇性最佳。而後製備一系列部不同鐵/鈦莫耳比的Au/FeOx-TiO2觸媒進行探討，在相同的反應條件下，結果顯示當鐵/鈦擔體煅燒300℃且Fe/Ti 原子比為4比6時達最高的活性及選擇性。添加鐵於Au/TiO2觸媒可避免金燒結，且降低金的氧化態，增加反應活性基點，表示利用金觸媒的良好選擇性與添加氧化鐵，可以有效提高觸媒活性。

關鍵字

奈米金觸媒；液相氫化反應；對氯苯胺；對氯硝基苯

並列摘要

Nanosized gold catalyst has been reported to be a good catalyst for the liquid phase hydrogenation reactions due to their excellent activity and selectivity. In this study, various additives (FeOx, AlOx, CeO2, MgO, MnOx, ZrO) were added into Au/TiO2 catalyst.. The modified-TiO2 support was prepared by incipient-wetness impregnation0. Gold catalysts were prepared by deposition-precipitation method with 4wt. % Au loading. The activity of the modified catalyst was tested for the hydrogenation of p-chloronitrobenzene. These catalysts were characterized by inductively-coupled-plasma-mass spectrometry, X–ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and temperature programmed reduction. The catalytic properties of gold based catalysts were studied on hydrogenation of p–chloronitrobenzene(p-CNB). The conditions for hydrogenation reaction were 1.2 MPa H2 pressure, 353 K reaction temperature and 500 rpm stirring speed. Methanol was used as the solvent, the concentration of p-CNB was 0.2 M (2.54g p–CNB in 80 ml methanol) and the amount of gold based catalyst was 0.5g. For modified gold catalysts, Fe-doped ones were better than the other catalysts, and it had the highest activity and selectivity. A series of Au catalysts supported on FeOx-TiO2 with various Fe contents were prepared. The iron oxide in Au/FeOx-TiO2 played the role of a textural promoter, prevents from sintering of gold particles. The results showed that the additive of Fe could prevent Au0 from being oxidized, increased the active sites and enhanced catalytic activity. Au/ FeOx-TiO2 with Fe/Ti atomic ratio of 4/6 exhibited the highest activity among the series of Au/ FeOx-TiO2. It could be concluded that adding suitable iron amount showed the best performance, and could promote the activity of Au catalyst effectively.

並列關鍵字

Nanoalloy gold catalyst ； hydrogenation ； p-chloronitrobenzene ； p-chloroaniline

參考文獻

Akita, Tomoki, Lu, Ping, Ichikawa, Satoshi, Tanaka, Koji, Haruta Masatake, “Analytical TEM study on the dispersion of Au nanoparticles in Au/TiO2 catalyst prepared under various temperatures”, Surf. Interface Anal. 31 (2001) 73–75.

Aronniemi, M., Sainio, J., Lahtinen, J., “XPS study on the correlation between chemical state and oxygen-sensing properties of an iron oxide thin film”, Applied Surface Science 253 (2007) 9478–9479.

Bailie, J.J. and . Hutchings, G.J, “Promotion by sulfur of Ag/ZnO catalysts for the hydrogenation of but-2-enal”, C atal. Commun. 2 (2001) 291.

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奈米金觸媒在對氯硝基苯氫化反應之研究

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