PET和关中麦秆共热解特性及其动力学研究

Co-pyrolysis Characteristics and Kinetics of PET and Wheat Straw

利用TG-FTIR技术研究陕西关中地区小麦秸秆(麦秆)、聚对苯二甲酸乙二醇酯(PET)及其两者混合物麦秆-PET(质量比1∶1)在20 K/min的升温速率下的热解行为、主要热解产物、协同效应和动力学。研究结果表明:PET热解初始温度为375℃,最大热失重速率处的温度为454.9℃,失重率为62.87%,其热解残余质量为19.42%;麦秆-PET的热解DTG曲线表现为麦秆和PET主失重峰(339.9和444℃)的叠加,且混合试样在两个强峰处的失重率分别为22.9%和73.9%,最终热解残余质量为23.52%;PET和麦秆共热解过程中会出现两个协同效应(339.9和444℃),这使得共热解产物中的CO、CH_(4)以及芳香族、酸类、酮类、醛类、醇类、烷烃、酚类和醚类等轻质焦油组分含量高于麦秆和PET单独热解,共热解提高了热解产物的热值,改善了热解产物组成,提升了热解产物的稳定性和燃料品质;采用Coats-Redfern积分法计算得到PET在主热解区的表观活化能为355.48 kJ/mol,远高于麦秆的表观活化能(86.5 kJ/mol),麦秆-PET在低温区(258~363℃)的表观活化能为53.6 kJ/mol,在高温区(393~463℃)的表观活化能为81.6 kJ/mol。

Pyrolytic behaviors,main pyrolytic products,synergistic effect and kinetics of Guanzhong wheat straw,polyethylene Terephthalate(PET)sample and its blends(mass ratio 1∶1)were investigated by TG-FTIR system at heating rate of 20 K/min.The results demonstrated that the initial pyrolysis temperature of PET sample was 375℃and the maximum weight loss rate(62.87%)occured at the temperature of 454.9℃and the residual amount was about 19.42%.The weight loss rates of the mixture were 22.9%and 73.9%at the two weight loss peak(339.9 and 444℃),respectively.At that time,the final prolysis residual amount was about 23.52%.There were two synergistic effects(339.9 and 444℃)in the process of co-pyrolysis which enhanced the amount of pyrolysis products of CO,CH_(4),aromatics,acids,ketones,aldehydes,alcohols,alkanes,phenols and ethers.The heating value and fuel quality of the raw material were enhanced a lot by the co-pyrolysis process.The apparent activation energy of PET in higher than that of wheat straw(86.5 kJ/mol).And the apparent activation energies of the mixture calculated by Coats-Redfern method were 53.6 kJ/mol at low pyrolysis temperature region(258-363℃)and 81.6 kJ/mol at the high pyrolysis temperature region(393-463℃).