五种甘蔗渣分离木质素热解特性及动力学

发布时间：2018-10-29 21:13

【摘要】：木质素是自然界中最丰富的芳香类化合物,也是制浆造纸和木质纤维素生物炼制过程的主要副产物。热解是将木质素资源化、能源化利用的一个有效途径。但由于分离方法不同,所得的木质素产品具有不同的热解特性。本文通过有机酸处理、碱处理和氧化处理从甘蔗渣中分离得到5种木质素,即乙酸木质素(AAL)、Acetosolv木质素(As L)、Milox木质素(ML)、过氧乙酸木质素(PAAL)和碱木质素(AL)。采用差示扫描量热(DSC)和热重分析(TGA)对5种木质素的热解性质进行了研究。发现5种木质素的热解过程均可分为水分脱除、玻璃化转变、热解和缓慢结焦4个阶段。采用非等温的Coats-Redfern积分法对热重数据进行动力学拟合。结果表明,PAAL在200~700℃范围内的热解为二级动力学反应,另外4种木质素则在250~700℃范围内为二级动力学反应。5种木质素的热解表观活化能分别为AAL 33.33kJ/mol、As L 36.36kJ/mol、ML 31.10kJ/mol、PAAL24.74kJ/mol以及AL 36.93 kJ/mol。
[Abstract]:Lignin is one of the most abundant aromatic compounds in nature, and it is also the main by-product of pulping, papermaking and lignocellulosic biological refining process. Pyrolysis is an effective way to utilize lignin as resource and energy. However, due to the different separation methods, the lignin product has different pyrolysis properties. In this paper, five kinds of lignin were isolated from bagasse by organic acid treatment, alkali treatment and oxidation treatment, that is, acetic acid lignin, (AAL), Acetosolv lignin, (As L), Milox lignin (ML),. Peroxyacetate lignin (PAAL) and Alkali lignin (AL). The pyrolysis properties of lignin were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the pyrolysis process of lignin could be divided into four stages: water removal, glass transition, pyrolysis and slow coking. The thermogravimetric data were fitted by non isothermal Coats-Redfern integration method. The results show that the pyrolysis of PAAL at 200 鈩，

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