不同加热速率下亚麻纤维的热解机理

Pyrolysis Mechanism of Flax Fiber Under Different Heating Rates

为了研究亚麻纤维在高温下的热解机理,首先对纯亚麻纤维在非等温条件下的热解动力学行为进行了分析.完成了4种加热速率下的热重实验,研究了亚麻纤维的热解特性,采用6种无模型法和2种模型拟合法计算了亚麻纤维热解反应活化能随转化率的分布,判断了不同热解反应阶段的反应模型类别.结合动力学补偿效应分析,重建了亚麻纤维主要热解阶段的反应机理函数.通过模型独立性分析,对各重建函数的准确性进行了评估.通过质谱对亚麻纤维的热解生成物进行了归纳.结果表明,亚麻纤维热解的主要反应阶段可视为一个独立的子反应,其温度区间位于半纤维素、纤维素等主要成分的热解温度范围内.该阶段的反应机理与F类模型比较接近.重建的反应模型函数表现出较高的拟合度且具有较好的准确性.亚麻纤维的主要热解生成物包含烯烃和醛等11种有机化合物.

In order to study the pyrolytic mechanism of flax fiber at high temperature,the thermal kinetic analysis of pure flax fiber pyrolysis was firstly conducted under non-isothermal conditions in this paper.Initially,the pyrolytic properties of flax fiber were explored by thermogravimetric experiments at four heating rates.Then,the distribution of activation energy with conversion was calculated through six model-free methods,and the reaction model categories corresponding to different reaction stages were determined by two model-fitting methods.After combining the kinetic compensation effect analysis,the reaction model function of flax fiber pyrolysis was optimized and reconstructed.After that,the accuracy of the function was evaluated by model independence analysis.Finally,the pyrolytic products of flax fiber were summarized through mass spectrometry.The results indicated that the main reaction stage of flax fiber could be regarded as one independent sub-reaction,whose temperature interval was located in the pyrolysis temperature range of hemicellulose,cellulose,lignin and other components.The reaction mechanism of the main reaction stage was closer to F-series model.The reconstructed function demonstrated high fitting degree and reasonable accuracy.The pyrolysis products of flax fiber mainly contained 11 kinds of organic compounds,including aldehydes and olefin,etc.