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標題: | Au/CeO2觸媒在水氣轉移反應上的應用 Application of Au/CeO2 over Water-Gas Shift Reaction |
作者: | Yan-Ru Lin 林延儒 |
指導教授: | 萬本儒(Bez-Zu Wan) |
關鍵字: | 低溫水氣轉移反應,金觸媒,二氧化鈰,金溶液酸鹼度,金顆粒粒徑大小,前處理,儲存溫度, low temperature water-gas-shift reaction(WGSR),gold catalysts,CeO2,pH of gold solution,particle size of gold particles,pretreatment,storage effect, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 本研究以沉澱沉積法製備Au/CeO2,期望製備在低溫(200℃)水氣轉移反應中,具有高CO轉化率之觸媒。嘗試研究如下變因:(1) 鹼液中處理CeO2表面的影響;(2)金溶液酸鹼度的影響;(3) Au/CeO2前處理的影響;(4)保存Au/CeO2的方式。研究中並對觸媒的活性變化作鑑定和探討,鑑定方式包括:AA、UV-Vis、HRTEM、XRD。
研究結果顯示以表面修飾至pH值為6到8的CeO2最為適合,未經表面修飾或是修飾至pH值為10的CeO2所製成的觸媒會造成轉化率些微的下降;金溶液則以調至pH值為9所製成的Au/CeO2效果最佳,因為此時可使氯化金酸中的氯離子完全被OH-取代;Au/CeO2若在200oC下經一氧化碳前處理,因能維持小的金顆粒而有較高的催化活性;最後,製備好的Au/CeO2需儲存於冰箱的冷凍庫中,以免發生活性衰退的情形。 應用較佳的Au/CeO2,在總體積流速33.33ml/min(298K),反應溫度200℃,及以下兩種進料莫耳比例:(1) CO/H2O/N2 = 2.65/41.17/56.18;(2) CO/H2O/H2/CO2= 2.65/41.17 /44.94/11.24,分別測試催化活性。在(1)條件中,CO轉化率達98%,已接近理論平衡轉化率;但在(2)條件中,轉化率僅約73%,顯示觸媒的催化活性在未來仍具改善的空間。 The purpose of this research is to investigate Au/CeO2 which is prepared by deposition-precipitation method (DP method) with high CO conversion under low temperature water-gas-shift reaction (WGSR). Preparation factors listed below are studied: (1) CeO2 surface modification by NaOH(aq); (2) pH value of gold solution for deposition; (3) pretreatment of Au/CeO2 before water-gas-shift reaction; (4) Au/CeO2 storage effect. Additionally, the properties of the catalysts are characterized by AA, UV-Vis, HRTEM, XRD. The experimental results indicate that CeO2 with surface modification to pH=6 ~ 8 possesse the better performance; however, the CO conversion would decrease when the CeO2 with surface modification to pH=10 or without surface modification. The better pH value for the gold solution for deposition is 9, because the four Cl- in the solution could be ideally replaced by OH-. Au/CeO2 pretreated before reaction by CO at 200oC has the best CO conversion, because of the smallest particle size of gold particles. Finally, Au/CeO2 needs to store under low temperature without light (i.e., in a refrigerator) to protect against decay. For the tests of water-gas-shift reaction, the total flow rate and reaction temperature were carried out at 33.33ml/min and 200℃. Two mole flow rate ratios at reactor inlet : (1)CO/H2O/N2 = 2.65/41.17/56.18;(2) CO/H2O/H2/CO2=2.65/41.17/ 44.94/11.24 were used. For the best performance Au/CeO2 catalyst prepared in this research, CO conversion of condition (1) was 98%, which is approaching the equilibrium conversion obtained from thermodynamics simulation; however, CO conversion of condition (2) could only reach 73%. This implies there is still much room to improve the performance of the catalyst in the future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/26795 |
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顯示於系所單位: | 化學工程學系 |
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