Nascent tar formation during polyvinylchloride (PVC) pyrolysis
Nascent tar formation during polyvinylchloride (PVC) pyrolysis
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聚氯乙烯 (PVC) 热解过程中初生焦油的形成
DOI：
10.1016/j.proci.2012.08.013
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发表时间：
2013-01-01
影响因子：
3.4
通讯作者：
Xu, Minghou
中科院分区：
文献类型：
--
作者：
Gui, Ben;Qiao, Yu;Xu, Minghou
以聚氯乙烯（PVC）为原料，进行了热解实验，研究了峰值温度、保温时间和升温速率对初生焦油生成的影响。使用丝网反应器收集初生焦油样品，其中所产生的挥发物的二次反应被最小化。丝网反应器中未检测到苯和烷烃等小分子化合物，其组成与管式反应器和真空反应器中的其它焦油有很大不同。在1000 K/s的升温速率下，初生态焦油中主要为准三环和三环族芳烃，而二环族芳烃含量随升温速率的增加而增加，从500 ℃增加到800 ℃时，含量由7.02%增加到31.75%。在300 s的较长保温时间下，对于500 ℃下的新生焦油，也观察到2环基团芳烃从7.02%增加到50.33%，表明焦油组成在PVC热解的不同阶段显著变化。在PVC热解过程中，前期有3-4环化合物生成，后期有2环化合物释放。根据实验结果，提出了PVC焦油生成的四阶段机理：（1）脱氯并内环化，（2）芳香链断裂，（3）准三环或三环基团释放，（4）二环基团释放。(C)2012燃烧研究所爱思唯尔公司出版All rights reserved.
Pyrolysis experiments of polyvinylchloride (PVC) were performed to investigate the effects of peak temperature, holding time, and heating rate on the formation of nascent tar. The nascent tar samples were collected using a wire-mesh reactor where the secondary reactions of the evolved volatiles were minimized. The small compounds, such as benzenes and alkanes, were not detected in nascent tar in wire-mesh reactor, whose components are quite different from those of other tars in tube type reactor and vacuum reactor. At a heating rate of 1000 K/s, the quasi-3 rings and 3 rings group aromatics were the major components in nascent tar; while the content of 2 rings group aromatics increased from 7.02% to 31.75% with increasing peak temperature from 500 to 800 degrees C. At a longer holding time of 300 s, an increase of 2 rings group aromatics from 7.02% to 50.33% was also observed for the nascent tar at 500 degrees C, indicating that the tar composition significantly changed at different stages of PVC pyrolysis. It seems that 3-4 rings compounds form in the early stage and then 2 rings compounds release in the later stage of PVC pyrolysis. Based on the experimental results in this work, a new four-stage mechanism, including (1) dechlorination accompanied with inner cyclization, (2) aromatic chain scission, (3) release of quasi-3 rings or 3 rings group, and (4) release of 2 rings group, of the PVC tar formation was proposed. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.