- 學位論文
纖維素衍生物於H-ZSM-5行觸媒快速裂解製備綠色燃料
Catalytic fast pyrolysis of cellulosic derivatives over H-ZSM-5 to green gasoline
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摘要
本論文著眼於呋喃與呋喃甲醛，皆為纖維素衍生物，於H-ZSM-5觸媒行快速裂解之反應。透過溫度、滯留時間及Zn金屬離子等參數之操控，促進綠色燃料(苯、甲苯及對二甲苯)之生成。研究顯示呋喃甲醛與H-ZSM-5觸媒行脫碳反應生成呋喃及一氧化碳。而呋喃在觸媒孔洞中進行一系列複雜反應，轉化成中間物(環己烯及二甲基苯醛)、芳香族、積碳及氣體產物(烯類、烷類及碳氧化物)。研究顯示在反應溫度為500oC及滯留時間為1.5秒之反應條件下能生成最高的芳香族含量。並以苯及甲苯等芳香族產物之選擇率最為突出且產生最少的積碳。Zn金屬離子促進劑可影響H-ZSM-5觸媒本質酸性活性基組成與形成新的路易士酸，進而促進呋喃轉化。此暗示著Zn金屬離子促進劑可提升觸媒質子傳導與芳香族化之能力，更進一步提高芳香族產物之生成。 第二部分研究顯示，呋喃於Na/H-ZSM-5及Na/Zn-H-ZSM-5觸媒反應後，轉化率皆為略低。布朗士酸於芳香族化反應中是必須的。孔洞效應有助於將呋喃轉化為芳香族。Zn金屬離子促進劑不僅提供脫氫環化及甲烷化反應之能力。
並列摘要
Furfural, a cellulose model species, was converted into gasoline-range fuels through catalytic fast pyrolysis. H-ZSM-5 based catalysts were employed in a continuous fixed bed system. The reaction temperature, contact time of reactant, and catalytic promoter are the key to manipulate product distribution. The onset of furfural conversion is decarbonylation to furan, followed by furan conversion to intermediates (e.g., diacetone alcohol, cyclohexene, and dimethylenzaldehyde) in the ZSM-5 cages. These intermediates can then be transformed into aromatics, coke, light olefins, and carbon oxides. At 500 oC, the highest yield of aromatics and the lowest amount of coke could be generated. A long contact time (~ 1.5 s) also provided the highest aromatic selectivity. The promoter, zinc oxide, plays an important role in hydrogen atom transfer. This is attributed to the change of acid site concentration and newly formed Lewis acid site by anchored Zn ions. The second part of study shows that furan react over Na/H-ZSM-5and Na/Zn-H-ZSM-5 catalyst, the conversions are slightly lower. In aromatization process, the Bronsted acid site is necessary. Cage effect can contribute to furan covered aromatic products. Zn metal ion provides not only dehydrogenation cyclization ability and methanation.
參考文獻
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