以稀酸溶液及微波加熱進行甘蔗渣水解之研究

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以稀酸溶液及微波加熱進行甘蔗渣水解之研究
著者: 葉松青; Ye, Song-ching
陳維新; Wei-hsin Chen; 綠色能源科技研究所碩士班
主題: 濕焙燒; 產率與選擇率; 呋喃醛與糠醛; 木糖與葡萄糖; 微波加熱; 甘蔗渣; 生質酒精; 木質纖維素; 水熱碳化; 能量密度; Wet torrefaction; Yield and selectivity; Furfural and 5-hydroxymethylfurfural (HMF); Xylose and glucose; Microwave heating; Sugarcane bagasse; Bioethanol; Lignocellulose; Hydrothermal carbonization; Energy enhancement factor
描述: 以替代能源的角度來看，木質纖維素為一種豐富且低成本之原料。然而，由於木質纖維素具有高度結晶性且複雜的結構，不易直接利用，因此木質纖維素前處理是必要的。前處理目的是破壞木質纖維素結晶結構，以去除木質素並溶解半纖維素，提升纖維素之相對比例，增加纖維分解酵素之反應面積，以增進後續水解或發酵之反應速率。因此前處理技術被視為以木質纖維素為原料製備生質酒精程序中相當關鍵的步驟。本文第一部分，為了瞭解原料蔗渣於微波加熱環境下水解特性，將生質物放置於稀硫酸溶液中升溫至180°C持溫30分鐘。其中，稀硫酸溶液濃度範圍為0至0.02M。為了進一步瞭解殘餘固體與回收液體之物理及化學性質，因此進行各項分析，包括纖維分析、熱重分析、晶體結構分析、官能基分析及液體濃度分析。隨著稀硫酸溶液濃度提升，有助於破壞木質纖維素結構；然而，於前處理反應發現生質物具有緩衝能力，抵抗酸性溶液腐蝕破壞。實驗結果發現，經稀硫酸前處理過後，原料蔗渣被降解40~44%，其中將近80~98%之半纖維素被水解。相較之下，稀硫酸溶液對纖維素結晶區與木質素影響不大。由液態分析可知，木糖與葡萄糖之最佳產率及最低呋喃醛選擇率均出現於使用0.005M稀硫酸溶液。因此，原料蔗渣之前處理與備製生質酒精之最佳操作條件為使用0.005M稀硫酸溶液、反應溫度為180°C持溫30分鐘。本文第二部分，為了研究原料蔗渣經濕焙燒前處理之水熱碳化特性。生質物依不同比例與中性溶液或酸性溶液進行混合，利用微波加熱至180°C進行濕焙燒前處理。其中，固液比為0.1及0.2 gmL-1，硫酸濃度為0及0.1M，持溫時間為5至30分鐘，藉由觀察原料蔗渣經濕焙燒前處理之影響。結果發現，隨著稀硫酸溶液濃度及持溫時間增加，有助於生質物之碳化反應。經濕焙燒前處理後，固態產物熱值最高可提升20.3%，相較於乾焙燒前處理，其操作溫度低約100°C。利用各項分析之經驗式預測固體產物之熱值，結果發現使用纖維分析經驗式預測熱值較準確。由此可知，木質素含量增加對固態生質燃料熱值提升有著相當重要的貢獻。
In order to produce bioethanol from lignocelluloses, it is essential to obtain fermentable sugar from hemicellulose and cellulose, especially for the latter. However, by virtue of lignocelluloses featured by recalcitrance in nature, the process of biomass pretreatment is required. The purposes of pretreatment are to remove hemicellulose and lignin, decrease crystalline cellulose and increase the surface area of the materials, thereby facilitating the subsequent enzymatic hydrolysis. As a matter of fact, studies have suggested that pretreatment is the most important step for bioethanol production from lignocelluloses in that it defines the extent to and cost at which the carbohydrates of hemicellulose and cellulose can be converted to bioethanol.First, pretreatment of lignocellulosic biomass is of the utmost importance for the development of bioethanol because of the abundance and low cost of lignocelluloses. To figure out the hydrolysis characteristics of sugarcane bagasse in a microwave irradiation environment, the biomass is pretreated by a dilute sulfuric acid solution at 180°C for 30 min, with the concentration ranging from 0 to 0.02M. A variety of analyses, including fiber analysis, TGA, XRD, FTIR and HPLC, are employed to aid in understanding the physical and chemical characteristics of residual solid particles and solutions. A higher concentration is conducive to destroying bagasse; however, the buffering capacity possessed by the biomass is also observed in the pretreatment. The experimental results indicate that around 40-44 wt% of bagasse is degraded from the pretreatment in which around 80-98% of hemicellulose is hydrolyzed. In contrast, crystalline cellulose and lignin are hardly affected by the pretreatment. The maximum yields of xylose and glucose as well as the minimum furfural selectivity occur at the acid concentration of 0.005M. Consequently, the aforementioned concentration is recommended for bagasse pretreatment and bioethanol production.Second, the behavior of hydrothermal carbonization of sugarcane bagasse is studied using wet torrefaction. The biomass is torrefied in water or dilute sulfuric acid solution. Microwaves are employed to heat the solutions and the reaction temperature is fixed at 180°C. The effects of the acid concentration, heating time and solid-to-liquid ratio on the performance of wet torrefaction are considered. It is found that the addition of sulfuric acid and increasing heating time are conducive to carbonizing bagasse. The higher heating value of bagasse can be increased up to 20.3% from wet torrefaction. With the same improvement in calorific value, the temperature of wet torrefaction is lower than that of dry torrefaction around 100°C. The calorific value of torrefied biomass can be appropriately predicted based on proximate, elemental or fiber analysis, and the last one gives the best estimation, suggesting that lignin plays an important role in contributing heating value in lignocelluloses.
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建立日期: 2012
格式: 121 bytes
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語言: 中文
識別號: http://nutnr.lib.nutn.edu.tw/handle/987654321/1170
資源來源: NUTN IR

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以稀酸溶液及微波加熱進行甘蔗渣水解之研究

葉松青; Ye, Song-ching 陳維新; Wei-hsin Chen; 綠色能源科技研究所碩士班 2012

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