基于TG-FT-IR的关中麦秆热解特性及动力学研究

利用TG-FT-IR技术分别以5、10、20℃/min 3种不同的升温速率,在室温至1000℃下对陕西关中地区麦秸秆(麦秆)的热解行为、特性及动力学进行了研究。研究结果表明,关中麦秆的热解过程可分为4个阶段:失水(室温到150℃)、半纤维素热解(150~300℃)、纤维素热解(300~380℃)及木质素热解(380~1000℃);升温速率的升高使关中麦秆的起始热解温度提高,较低的升温速率可克服热解过程中的传热滞后现象,更有利于关中麦秆的热解。关中麦秆升温速率20℃/min下最大失重速率处的的热解产物主要为H₂O、CH₄、CO₂、CO及一些芳香族、酸类、酮类、醛类、醇类、烷烃、酚类和醚类等有机物。通过无模式函数法中的FWO和KAS法对关中麦秆的热解表观活化能在转化率(α)0.1~0.8内进行了计算,所得活化能均约为202 kJ/mol。此外,Kissinger法估算所得表观活化能约为171.12 kJ/mol,略低于FWO法和KAS法热解表观活化能。

Pyrolysis Characteristics and Kinetics of Guanzhong Wheat Straw Using TG-FT-IR

The pyrolysis behavior, characteristics and kinetics of Guanzhong wheat straw were investigated with a TG-FT-IR system at heating rates of 5, 10 and 20℃/min from ambient temperature to 1000℃. The results showed that the pyrolysis process of Guanzhong wheat straw could be divided into 4 stages:dehydration(room temperature-150℃), the pyrolysis processes of hemicellulose(150-300℃), cellulose(300-380℃) and lignin(380-1000℃). The main pyrolysis products at maximum pyrolysis rate under heating rate of 20℃/min identified by FT-IR included H₂O, CH₄, CO₂ and CO as well as aromatics, acids, alcohols, alkanes, phenols, ethers, ketones and aldehydes. The apparent activation energies determined by using model-free methods of FWO and KAS were determined with the appaoximate average value of 202 kJ/mol at conversion rates of 0.1-0.8. The activation energy estimated by the Kissinger method was 171.12 kJ/mol and lower than those obtained by FWO and KAS method.