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題 名 | 硫氫化鈉對木質素模式化合物脫甲基動力學之研究=Studies on the NaSH Demethylation Kinetics of Lignin Model Compounds |
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作 者 | 汪淮; 黃國峰; | 書刊名 | 國立臺灣大學農學院實驗林研究報告 |
卷 期 | 15:1=231 2001.03[民90.03] |
頁 次 | 頁35-46 |
分類號 | 476.21 |
關鍵詞 | 硫氫化鈉; 木質素模式物; 製漿; 反應速率; 活化能; 反應動力學; Sodium hydrosulfide; Lignin model compounds; Pulping; Relative reaction rate; Activation energy; Kinetics; |
語 文 | 中文(Chinese) |
中文摘要 | 本文乃在探討重要之硫酸鹽製漿法在蒸煮時,木質素之脫甲基動力學,以硫氫化鈉(6%)為蒸煮液,利用六種木質素模式化合物,研究160、170及180℃三種溫度蒸煮下之反應速率及其活化能。結果顯示:影響脫甲基反應之因子有蒸煮液之pH值、不同結構之官能基、官能基對甲氧基之位置、反應時間和反應溫度皆對反應速率有影響。其中反應時間愈長、反應溫度愈高則反應之效應愈好。提高溫度會促進反應物之反應速率,在對位之官能基為羧基和鄰位含有羥基時,反應速率增加最快,官能基之位置及種類皆會影響反應速率,當對位之官能基為醛基時,其反應最快;而在中性狀態時,活化能最低。在pH值之效應方面,除了對甲氧基苯甲醛會隨著pH值升高,而反應速率降低外,其他五種則隨著pH值升高而增加,顯示當升高pH值會增加脫甲氧基之效率,但若木質素之結構含有醛基時則會影響脫甲氧基之速率。當比較不同木質素模式物之活化能時,發現在中性和鹼性時其活化能之變化較大。 |
英文摘要 | The kinetics of lignin demethylation in sulfate pulping was the main purpose of this study. Six lignin mdoel compounds were cooked with NaSH(6%) cooking liquor at three different temperatures 160、170 and 180℃. After cooking, HPLC was used to analyze their changes in chemical compositions in order to calculate their relative reaction rate and activation energy. The factors affecting demethylation reaction were the pH value of cooking liquor, different functional groups, the relative position of functional groups to methoxyl groups, cooking time and cooking temperature. All of which affected the relative reaction rate. The longer the reaction time and higher the reaction temperature would result higher relative reaction rate. Increasing in temperature would accelerate the relative reaction rate of the reactant, especially when the carboxy1 group was in the para-position and hydroxy1 groups in the ortho-position. Both different position and functional groups would affect the relative reaction rate. The para-functional group of aldehyde would result the best relative reaction rate, which had the lowest activation energy under neutral condition. On terms of the effect of pH value, except p-anisaldehyde would decrease the relative reaction rate when the pH increased, the other five model compounds would increase the relative reaction rate as the pH increased, which indicated that increasing in pH value would increase the efficiency of demethylation. However, when the lignin contained aldehyde group would affect the efficiency of demeythylation. Comparing with the activation energy of different lignin model compounds, the great variation in activation energy occurred in the neutral to alkali pH range. |
本系統中英文摘要資訊取自各篇刊載內容。