臺灣博碩士論文加值系統

甲烷裂解被視為在全面使用綠氫前之過渡產氫方式，產製之氫被稱為藍綠氫。為降低反應活化能，本研究進行催化甲烷裂解產製藍綠氫，嘗試三種型態之催化劑，尋找能夠穩定產氫之催化劑。
在以Al2O3為載體之金屬催化劑中，反應溫度由室溫升至預定反應溫度時，甲烷轉化率逐漸上升至最高值，之後因積碳使催化劑失活甲烷轉化率隨反應時間增加而降低。在反應溫度為900℃時，最高甲烷轉化率約為90%，相對應之氫產率為1.8 mol H2/mol CH4。實驗發現，鎳鐵合金具有優於單獨鎳或鐵催化劑之抗積碳能力，而甲烷裂解之副產物碳，經SEM檢視，主要形式為碳絲。實驗數據顯示，鎳鐵比例及鍛燒溫度亦為影響催化劑催化及抗積碳能力之因素。本研究發現，10%wtNiO-10wtwt%Fe2O3/Al2O3催化劑在鍛燒溫度為600℃時具有最佳之催化及抗積碳能力。
在以生物碳為催化劑之實驗結果顯示，其催化能力較金屬催化劑為低，在反應溫度為900℃時，最高甲烷轉化率約為40%，積碳亦造成其催化能力下降。而將生物碳經活化處理改質後，其催化能力可明顯提高，900℃時最高甲烷轉化率約為70%。實驗結果顯示，市售活性炭具有較佳之抗積碳能力，因此未來研究可進行較深入之改質生物碳催化劑之探討。以市售活性碳為載體之金屬催化劑，其催化裂解隨反應時間變化趨勢與市售活性碳相似，雖可提高甲烷轉化率但無法達到以Al2O3為載體之金屬催化劑之催化能力，因此載體型態亦為影響催化劑催化效能之因素。
本研究以市售發泡鎳為結構型催化劑，探討其催化催化甲烷裂解之性能。結果顯示，在低孔隙密度之發泡鎳之結果，其催化能力與金屬及生物碳催化劑相當，亦即積碳造成其催化能力下降。而使用高孔隙密度之市售發泡鎳時，由於積碳速率、反應速率、以及反應物傳輸速率間平衡之結果，造成催化性能隨反應時間增長而達到一穩定狀態，因而可穩定產製純氫。在24小時長時間測試下，發現孔隙密度為110之發泡鎳，仍可維持穩定產氫。

Methane decomposition is recognized as a transition H2 production technology before the green H2 is completely available. The H2 produced from methane decomposition is known as turquoise H2. To reduce the activation energy, catalytic methane decomposition (CMD) using various kinds of catalysts was examined in this study. It was aimed to find the catalyst that is capable of producing H2 stably and carbon-free.
By using metal-based catalysts supported by Al2O3 and starting the reaction temperature from room temperature increased to the designated reaction temperature, it was found that CH4 conversion increases, reaches a maximum value, and then decreases as the CH4 was continuously supplied. For a reaction temperature of 900℃, the maximum CH4 conversion was found to be 90%. The corresponding maximum H2 yield is 1.8 mol H2/mol CH4. The CH4 conversion decrease is mainly due to the catalyst activity loss caused by carbon deposition. Based on the SEM picture, carbon filament was formed during the CMD. The experimental results also indicated that the bi-metallic Ni-Fe catalyst has better anti-carbon deposition ability as compared with single Ni or Fe catalyst. The results also showed that the Ni-Fe ratio and calcination temperature also played important roles in catalytic ability. The 10wt%NiO-10wt%Fe2O3/Al2O3 catalyst calcined at 600℃ was found the have the best catalytic activity among the be-metallic catalysts studied.
For the CMD, the results showed that the biochar catalyst is less active as compared with the metal catalysts. With a reaction temperature of 900℃ and using biochar as the catalyst, the maximum CH4 conversion is only 40% and the catalyst activity loss can be found due to carbon deposition. However, the biochar activity can be enhanced after being modified using KOH etching and close to the commercially available active carbon. At the reaction of 900℃, the maximum CH4 conversion of 70% can be obtained from the modified biochar and active carbon. The experimental results also indicated metal catalyst supported by active carbon is less active than that supported by Al2O3. This leads to the conclusion that the support material of the catalyst is also one of the factors that affect the catalyst activity.
Finally, the catalytic ability of commercially available nickel foam on CMD was tested. The nickel foam catalyst can be regarded as one of the structured catalysts as compared with that prepared by impregnation methods. The results indicated that the CMD performance is greatly dependent on the pore per inch (PPI) of the foam. The CMD performance was similar to the catalyst supported by active carbon or Al2O3 using nickel foam with lower PPI as the catalyst. With higher PPI, stable CMD can be found due to the equilibrium interaction between reactant feed rate, chemical reaction rate, and carbon deposition rate. For the nickel foam PPI with 110, stable CMD can be obtained for 24 hours test.

摘要 i
Abstract ii
目錄 v
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 2
第二章 文獻回顧 3
2.1 CMD積碳生長 3
2.2 金屬基催化劑 5
2.3 碳基催化劑 9
2.4 結構型催化劑 10
第三章 實驗方法與設備 12
3.1 實驗架構圖 12
3.2 實驗流程 13
3.3 催化劑來源及製備方法 14
3.3.1 金屬基催化劑 14
3.3.2 碳基催化劑 15
3.3.3 碳載體之合金催化劑 15
3.3.4 結構型催化劑 16
3.4 效能指標 17
3.5 催化劑分析儀器與方法 17
3.5.1 SEM 17
3.5.2 EDS 17
3.5.3 元素分析儀 18
3.5.4 TGA 18
3.5.5 XRF 18
3.5.6 XRD 18
3.5.7 BET 19
第四章 結果與討論 20
4.1 金屬基催化劑之 CMD 20
4.1.1 反應實驗參數對 CMD之影響 20
4.1.2 鐵催化裂解之效能 34
4.1.3 鎳鐵合金催化裂解之效能 38
4.1.4 鍛燒條件對合金催化劑之影響 42
4.1.5 金屬 催化劑 BET及實驗前後 XRD分析 46
4.2 碳基催化劑之 CMD 48
4.2.1 碳基催化劑元素分析及 XRF 49
4.2.2 碳基 催化劑之效能 51
4.2.3 碳載體結合鎳鐵金屬對 CMD之效能 58
4.3 結構型催化劑之 CMD 61
4.3.1 發泡鎳EDS 62
4.3.2 孔隙度對 CMD之影響 63
第五章結論與未來研究 67
5.1 結論 67
5.2 未來研究 67
參考資料 68
附錄 A : 實驗設備及規格 72
附錄 B : 氣相層析儀 GC6850檢量線 76
附錄 C : 催化 劑製備計算 78
附錄 D :發泡鎳之 EDS 79

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