奈米複合鐵基金屬沸石觸媒鑑定及其應用於一氧化氮選擇性催化還原反應之效能

Characterization and Performances of Nanosized Bi-metallic Fe-based Zeolite Catalysts during Selective Catalytic Reduction (SCR) of NO by NH3

莎亞達(Sayeda Halima Begum)

指導教授 ： 劉尚斌

共同指導教授 ： 陳逸聰(Yit-Tsong Chen)

國立臺灣大學/理學院/化學研究所/博士(2013年)

https://doi.org/10.6342/NTU.2013.02617

摘要

因應日益嚴重的一氧化氮汙染與更嚴謹之法律規範，相關於一氧化氮(DeNOx)去除技術的研發頗受重視，本研究論文即針對鐵基(Fe-based) ZSM-5沸石觸媒在選擇性催化還原(Selective Catalytic Reduction; SCR)反應之應用效能進行系列性探討，包括觸媒合成方法，物理化學特性鑑定及其在SCR反應之效能與機理等做深入比較與討論。論文內容主要由五個主要章節目次所構成。首章概略敘述現行所使用去除一氧化氮製程工序之相關策略、反應機理、觸媒種類及其相關特性以及本研究之目的等；第二章主要描述本研究論文之研究架構與實驗流程，並詳述觸媒合成程序，物理性質與化學性質之鑑定技術以及去除一氧化氮反應效能測試之設備與實驗步驟等；隨後第三、四、五章之內容則為本研究論文之結果與討論部分。第三章的主題在於比較並討論單金屬與雙金屬鐵基沸石觸媒之合成方式對SCR反應效能之影響。第四章則著重於探討鑭系金屬元素(Ce, Pr, Nd, Sm)摻雜之鐵基沸石觸媒之物化特性比較及其應用於一氧化氮去除的效能差異。第五章則針對觸媒擔體(即ZSM-5沸石)中矽鋁組成比例對SCR反應活性之影響進行討論。第六章為本研究論文之總結及未來研究展望。本研究論文所合成之觸媒皆經過系統性的鑑定，所使用的物化分析研究包含ICP-MS、XRF、XRD、BET、FE-TEM、H2-TPR、XPS、EPR、NH3-TPD、pyridine-FTIR以及固態27Al/31P MAS NMR等。研究發現雙金屬鐵基(CeFe-ZSM-5)沸石觸媒去除一氧化氮效能上普遍優於單金屬鐵基(Fe-ZSM-5)沸石，反應在350-500 oC下，去除率可達94%以上。吾人將雙金屬鐵基沸石觸媒優異的SCR反應活性歸因於由沸石擔體本身具備的強布朗斯特酸(Bronsted acidity)以及該單體在摻雜Fe、Ce等金屬後所引發之超強路易士酸(Lewis acidity)兩者的協同效應所致。

關鍵字

選擇性催化還原反應 ； 反應機理 ； 除硝 ； 沸石 ； 31P核磁共振

並列摘要

In view of the stringent global regulation and increasing R&D demands in NOx removal (DeNOx), this thesis focuses on synthesis, characterization, and applications of Fe-based H-ZSM-5 zeolite catalysts for selective catalytic reduction (SCR) of NO by NH3. This thesis mainly consists of five chapters: Chapter 1 provides an overview and the chemistry, strategy, mechanism, and solid acid catalysts involved in a DeNOx process. Chapter 2 contains experimental details, including catalyst preparation methods, characterization techniques, and experimental procedures invoked during this study. Chapter 3 compares the SCR performances of mono- and bi-metallic Fe-based ZSM-5 catalysts prepared by different methods. Chapter 4 describes the syntheses and SCR performances of Lanthanide metal (Ce, Pr, Nd, and Sm)-incorporated Fe-based ZSM-5 catalysts prepared by reflux method. Chapter 5 summarizes the effect of Si/Al ratio of zeolite support on SCR performances of CeFe-ZSM-5 catalysts prepared by impregnation method. The catalysts so prepared were characterized by a variety of analytical and spectroscopic techniques, such as ICP-MS, XRF, XRD, BET, FE-TEM, H2-TPR, XPS, EPR, NH3-TPD, Pyridine-FTIR, and solid-state 27Al and 31P MAS NMR. It is conclusive that bimetallic catalysts (such as CeFe-ZSM-5) normally exhibit higher NH3-SCR activity (> 94%) over the temperature range of 350-500 oCthan mono-metal catalysts (such as Fe-ZSM-5). The superior SCR activity observed for the bimetallic catalysts has been attributed, for the first time, to the synergistic effect of Bronsted acidity originated from the zeolite support and strong Lewis acidity induced by the incorporated metals.

並列關鍵字

Selective catalytic reduction ； Mechanism ； DeNOx ； Zeolite ； 31P MAS NMR.

參考文獻

[39] D.E.W. Vaughan, Chem. Eng. Progress 84(1988) 25-31.

[11] F. Heinrich, C. Schmidt, E. Loffler, M. Menzel, W. Grunert, J. Catal. 212 (2002) 157-172.

[49] H. Y. Huang, R. Q. Long, R.T. Yang. Appl. Catal. A 235 (2002) 241-251.

V.I. Pavulescu, P. Grange, B. Delmon, Catal. Today 46 (1998) 233-316.

[3] A.Y. Watson, R.R. Bates, D. Kennedy, in Air Pollution: The Automobile and Public Health, National Academic Press, Washington, 1988.