基于热重红外联用和分布活化能模型的樟子松热解机理研究

Determination of Pyrolysis Characteristics and Kinetics of Pinus sylvestris var. mongolica Using TGA-FTIR and Distributed Activation Energy Model

利用热重红外联用技术(TGA-FTIR)和分布活化能模型(DAEM),通过不同升温速率(5、10、20、30℃/min),对樟子松的热解特性和热解动力学进行研究,并对其热解机理进行探讨。TG/DTG曲线表明,樟子松的热解过程分为干燥、快速热解和炭化3个阶段。FTIR图表明,热解挥发份气体相对含量最多的3类物质是CO2,醛、酮、酸类以及烷烃、醇类和酚类等有机物。随着转化率增加,通过DAEM计算得到的活化能数值波动明显,证明樟子松热解过程发生复杂的化学反应。0.1<转化率(α)<0.3,主要是半纤维素降解,其支链首先降解,然后主链发生断裂;0.3<α<0.7,主要是纤维素降解,首先转化为中间产物活性纤维素,活性纤维素再次降解;0.7<α<0.8,主要是木质素降解,苯丙烷分子相互结合形成网状立体结构以及低反应活性的焦炭的不断生成造成此阶段活化能迅速增加。

In order to get a fundamental understanding of pyrolysis behavior and kinetics of Pinus sylvestris var. mongolica,the TGA -FTIR instrument and distributed activation energy model （DAEM）via different heating rates （5,10,20,30 ℃/min）was taken for the study.The TG and DTG curves demonstrated that the pyrolysis process of PS consisted of the drying stage,degradation stage and carbonization stage.According to the FTIR analysis,the prominent volatile components generated by the pyrolysis of PS were CO2 ,aldehydes,ketones,organic acids,and alkanes,phenols etc.The fluctuation of activation energy can be interpreted as a result complex reaction occurred in pyrolysis process.For 0.1 〈conversion rate（α）〈0.3,this could be mainly attributed to the hemicellulose deg-radation.For 0.3 〈α〈0.7,cellulose initially pyrolyzed to active cellulose,then degradation of active cellulose occurred.For 0.7 〈α〈0.8,highest activation energy was observed due to the degradation of lignin.