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研究生:楊之翔
研究生(外文):Chih-hsiang Yang
論文名稱:碳化鎢/奈米碳管複合材料:製備、反應機制與觸媒特性
論文名稱(外文):Tungsten carbides and carbon nanotube composite materials:preparation, reaction mechanism and catalytic characteristics.
指導教授:陳建忠陳建忠引用關係
指導教授(外文):Chien-chong Chen
學位類別:碩士
校院名稱:國立中正大學
系所名稱:化學工程所
學門:工程學門
學類:化學工程學類
論文種類:學術論文
論文出版年:2006
畢業學年度:94
語文別:中文
論文頁數:108
中文關鍵詞:奈米碳管複合材料碳熱還原碳化鎢
外文關鍵詞:tungsten carbidecarbothermal reductioncomposite materialcarbon nanotube
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本研究是利用三氧化鎢和奈米碳管之混合物,以碳熱還原配合碳熱合成的方法製備出高產率的奈米尺寸碳化鎢之碳化鎢/奈米碳管複合材料,由實驗結果發現在固定持溫時間4小時800℃為W2C的最低生成溫度,900℃為WC的最低生成溫度,在碳化鎢的形態方面,發現從低溫下的薄膜狀轉變為過渡時的條狀,最後轉變為高溫下的球形顆粒形態,在反應物配置比例方面,在WO3:CNT=1:1時的碳化鎢總產率最高,但是就產物形態的均勻性而言,以WO3:CNT=1:3時最好,在改變持溫時間方面,隨著持溫時間增加,WC的產率有增加,而且W2C的產率有減少的趨勢。
關於反應機制的探討,在文獻上指出當碳熱還原過程中主要生成的碳源氣體會影響到反應機制,由GC測得主要生成的碳源氣體為CO2,而且從實驗產物之XRD數據所計算的相對產率做定量和定性的分析發現最終產物是WC和W2C共存,因此利用三氧化鎢和奈米碳管合成碳化鎢之反應機制推測為WO3→WO2.9→WO2→W→W2C WC。
由於碳化鎢具有類似鉑的觸媒性質,因此可以將製備的碳化鎢/奈米碳管複合材料應用在石化工業上的異構化反應,因為所製備的複合材料不具酸性,所以將材料利用鍛燒氧化成具有酸性之碳化鎢、氧化鎢/奈米碳管複合材料並且利用pyridine測酸實驗測試是否具備酸性。
This research tried to mixture of tungsten trioxide powder(WO3) and carbon nanotube(CNT). Produce high purity nanoscale tungsten carbide of tungsten carbide/CNT composite materials by carbothermal reduction and carbothermal synthesis method. The lowest temperature of formation W2C is 800℃ and formation WC is 900℃. For tungsten carbide morphology, the morphology from film shape changed to strip shape and final shape is spherical particle shape. For reaction ratio, the total yield is highest of WO3:CNT=1:1 but product morphology uniform is best of WO3:CNT=1:3. For change sustain heating time, WC yield increase and W2C yield decrease following increase temperature.
For discussion of reaction mechanism, when produced major carbon source gas can to affect reaction mechanism of carbothermal reduction. From GC measured major carbon source gas is CO2 and found final product is mixture of WC and W2C from relative yield of XRD analysis. So synthesis tungsten carbide by tungsten oxide and CNT of the reaction mechanism assume to WO3→WO2.9→WO2→W→W2C WC.
Due to tungsten carbide have similar to like Pt catalyst property, and therefore apply to isomerization reaction by tungsten carbide /CNT composite materials on petroleum industry. Because the composite materials do not have acidity but tungsten oxide have acidity. So tungsten carbide/CNT composite materials calcine oxided to tungsten carbide、tungsten oxide/CNT composite materials and measure the materials acidity by pyridine experiment.
致謝………………………………………………………………………….Ⅰ
摘要………………………………………………………………………….Ⅱ
Abstract……………………………………………………………………...Ⅲ
目錄………………………………………………………………………….Ⅳ
圖目錄……………………………………………………………………….Ⅵ
表目錄……………………………………………………………………….Ⅸ
1. 簡介……………………………………………………………………..…1
1.1 奈米碳管性質及其應用………………………………………………..1
1.2 碳化鎢性質及其應用..............................................................................2
1.3 程溫還原與程溫氧化…………………………………………………..3
2. 實驗動機…………………………………………………………………..6
3. 文獻回顧…………………………………………......................................7
3.1 碳熱還原法……………………………………………………………..7
3.2 化學氣相凝結法…………………………………………………........16
3.3 間歇式微波加熱法………………………………………………..…..17
3.4 熱回火法………………………………………………………………18
3.5 機械球磨法…………………………………………………………....19
4. 實驗設備與藥品………………………………………………………....20
4.1 儀器設備………………………………………………………………20
4.2 藥品……………………………………………………………………22
5. 實驗方法……………………………………………………………........23
5.1 實驗步驟……………………………………………………………....23
6. 結果與討論…………………………………………………………........25
6.1 反應物球磨前後之比較………………………………………............25
6.2 反應溫度之影響………………………………………………………28
6.2.1 低溫反應I (700~750℃) –中間產物………………………………..28
6.2.2 低溫反應II(800~900℃)………………………………………….....32
6.2.3 高溫反應(1000~1350℃)……………………………………………41
6.3 生成碳化鎢反應機制的探討………………………………………....63
6.4 WO3和CNT配置的比例對實驗造成的影響…………………………72
6.5 持溫時間對實驗造成的影響……………………………………........74
6.6 利用碳化鎢/CNT複合材料做為觸媒的特性………………………..84
7. 結論…………………………………………………………………..…..96
8. 未來展望…………………………………………………………………98
9. 參考文獻…………………………………………………………………99
附錄一 製備碳化鎢文獻回顧比較……………………………………….104
附錄二 持溫時間4小時之XRD相對產率………………………….........105
附錄三 持溫時間8小時之XRD相對產率……………………………….107
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