臺灣博碩士論文加值系統

甲苯(toluene)是許多石油化工工廠所產生的副產物，由於其產量不少，但價格又不高，因此希望能把甲苯變成其他較有價值的化合物，例如苯甲醛(benzaldehyde)。傳統上製造苯甲醛的方法是使用空氣當氧化劑氧化甲苯，不過由於會產生過多的深層氧化物以及要處理大量的inert gas，因此嘗試以V/TiO2金屬氧化物中之晶格氧進行甲苯的氧化反應。
反應在一連續式管狀固定床中（內裝置觸媒）進行，觸媒為沉浸法製備的V/TiO2觸媒(doped K)。實驗中探討了反應機制、氧氣量，添加pyridine，壓力及循環操作等的影響，以及以奈米TiO2及一般TiO2粉末作為support的影響。實驗結果顯示由於V/TiO2觸媒在無氣相氧環境下，觸媒活性會很快的下降，無法維持長時間的操作；而使用兩步驟循環操作則觀察到奈米TiO2為support的觸媒，由於氧化觸媒速率較快，因此循環操作時可用較短的時間來補充觸媒中的晶格氧。若不欲反應和再生循環操作，必須要通入氣相氧，一方面進行反應，另一方面進行觸媒的再生。當氣相氧濃度越大時，對深層氧化物苯甲酸及COx的產生有直接的影響，會使兩者的產量大幅上升。要避免苯甲醛選擇率過低，可以加入carrier gas如氬氣或CO2，降低氧氣濃度。而加入pyridine當競爭吸附劑時，可以明顯使苯甲醛產率上升。當使用奈米TiO2為support時，可以使觸媒比表面積上升，因而大幅增進和釩類的反應，因此反應性很好，使轉化率上升，在相同條件下，苯甲醛產率可較一般TiO2當support之觸媒大一倍，但苯甲醛的選擇率仍然很低。另外壓力越大，由於反應物易吸附及產物較不易脫附的影響，因此甲苯轉化率上升，苯甲醛產率上升，但苯甲醛有機選擇率下降。

摘要 Ⅰ
目錄 Ⅲ
表目錄 Ⅴ
圖目錄 Ⅵ
第一章 緒論…………………………………………………………..1
第二章 文獻回顧
2-1 厭氧氧化反應相關文獻………….……...…..….……...4
2-2 氧化觸媒相關文獻…………………………………………..5
2-2.1 氧化觸媒………………………………………………5
2-2.2 釩類觸媒的分類………………………………………6
2-3 甲苯選擇性氧化之相關文獻………………………………..7
第三章 實驗部分
3-1 實驗裝置…………………………………………………….21
3-1.1 進料區………………………………………………...21
3-1.2 反應區……………………………………………...…21
3-1.3 產物收集區…………………………………...………22
3-2 實驗步驟………………………………………………….…25
3-2.1 觸媒製備……………………………………………...25
3-2.2 觸媒前處理………………………………….…….…..26
3-2.3 甲苯氧化反應………………………………....………27
3-2.4 產物分析………………………………………....……28
3-2.5 操作變數……………………………………….….…..32
3-3 實驗藥品…………………………………………….…….…33
3-4 實驗儀器…………………………………………….…….…34
第四章 實驗結果與討論…………………………………...….….….37
4-1 再現性實驗………………………………………….….……39
4-2 無氣相氧的實驗…………………………………….……….41
4-3 兩步驟循環操作…………………………………………..…45
4-4 沒有carrier gas時氧氣量的影響………………...…………48
4-5 加入氬氣當carrier gas的影響…………………….…….….60
4-6 catalyst【1】和catalyst【2-1】的比較…………….…..……..62
4-7 進料中加入pyridine的影響…………………….……….….64
4-8 壓力的影響…………………………………………………..67
第五章 結論……………………………………………….……....….69
第六章 參考文獻…………………………………………….……….71

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