Ye Wenwen, Xu Xu, Zhan Mingxiu, Huang Qunxing, Li Xiaodong, Jiao Wentao, Yin Yongguang
College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Haidian District, Beijing 100085, China.
J Hazard Mater. 2022 Aug 5;435:128997. doi: 10.1016/j.jhazmat.2022.128997. Epub 2022 Apr 27.
Polycyclic aromatic hydrocarbons (PAHs) formation from the pyrolysis of waste tires is inevitable because of the complexity of tire formulations and the addition of certain chemicals. In this study, the formation behavior and distribution of PAHs in three-phases were investigated from waste tires under pyrolysis conditions. The influencing factors including the temperature, heating rate, holding time, particle size, catalyzer, and atmosphere, were systematically evaluated. The results showed that PAHs were mainly concentrated in pyrolysis oil (94.59-99.03%), followed by the gas phase (0.96-5.34%), and their content was very low in the solid phase (0.01-0.99%). A higher temperature and slower heating rate lead to partial PAHs decomposition, thus reducing their emissions. The overall formation of PAHs can be inhibited when pyrolyzing coarse-grained tire powder. Furthermore, the PAHs formation mechanisms in waste tires were determined through reaction molecular dynamics, electron paramagnetic resonance, and intermediate products. Tires were mainly decomposed into benzene series, *CH, and *CH; therefore, it was determined that PAHs were formed by the joint action of the hydrogen abstraction, and vinyl radical addition and methyl addition cyclization mechanisms. Among them, low and middle-ring PAHs were formed more easily, particularly naphthalene. The generation of PAHs can be inhibited by reducing the concentration of hydrocarbons and monocyclic benzene series. Regarding the distribution law and generation pathways of PAHs, our results provide guidance for reducing PAHs formation and emissions.
由于轮胎配方的复杂性以及某些化学物质的添加，废旧轮胎热解过程中多环芳烃（PAHs）的形成不可避免。本研究考察了热解条件下废旧轮胎中PAHs在三相中的生成行为及分布情况。系统评估了温度、升温速率、保温时间、粒径、催化剂和气氛等影响因素。结果表明，PAHs主要集中在热解油中（94.59 - 99.03%），其次是气相（0.96 - 5.34%），而在固相中的含量很低（0.01 - 0.99%）。较高的温度和较慢的升温速率会导致部分PAHs分解，从而减少其排放。热解粗颗粒轮胎粉末时，PAHs的总体生成可受到抑制。此外，通过反应分子动力学、电子顺磁共振和中间产物确定了废旧轮胎中PAHs的形成机理。轮胎主要分解为苯系物、CH和CH；因此，确定PAHs是通过氢提取、乙烯基自由基加成和甲基加成环化机制的共同作用形成的。其中，低环和中环PAHs更容易形成，尤其是萘。降低烃类和单环苯系物的浓度可抑制PAHs的生成。关于PAHs的分布规律和生成途径，我们的研究结果为减少PAHs的形成和排放提供了指导。
