Synergistic Effect and Chlorine-Release Behaviors During Co-pyrolysis of LLDPE, PP, and PVC

Zhilong Yuan; Jing Zhang; Peitao Zhao; Zheng Wang; Xin Cui; Lihui Gao; Qingjie Guo; Hongjing Tian

doi:10.1021/acsomega.9b04116

Synergistic Effect and Chlorine-Release Behaviors During Co-pyrolysis of LLDPE, PP, and PVC

ACS Omega. 2020 May 15;5(20):11291-11298. doi: 10.1021/acsomega.9b04116. eCollection 2020 May 26.

Authors

Zhilong Yuan¹, Jing Zhang¹, Peitao Zhao¹, Zheng Wang¹, Xin Cui¹, Lihui Gao², Qingjie Guo³, Hongjing Tian⁴

Affiliations

¹ School of Electrical and Power Engineering, China University of Mining and Technology, Xuzhou 221116, PR China.
² School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, PR China.
³ State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, PR China.
⁴ State Key Laboratory Base of Eco-chemical Engineering, College of Chemical Engineering, Qingdao University of Science & Technology, Qingdao 266042, PR China.

Abstract

Plastic wastes are environmentally problematic and costly to treat, but they also represent a vast untapped resource for the renewable chemical and fuel production. Pyrolysis has received extensive attention in the treatment of plastic wastes because of its technical maturity. A sole polymer in the waste plastic is easy to recycle by any means of physical or chemical techniques. However, the majority of plastic in life are mixtures and they are hard to separate, which make pyrolysis of plastic complicated compared with pure plastic because of its difference in physical/chemical properties. This work focuses on the synergistic effect and its impact on chlorine removal from the pyrolysis of chlorinated plastic mixtures. The pyrolysis behavior of plastic mixtures was investigated in terms of thermogravimetric analysis, and the corresponding kinetics were analyzed according to the distributed activation energy model (DAEM). The results show that the synergistic effect existed in the pyrolysis of a plastic mixture of LLDPE, PP, and PVC, and the DAEM could well predict the kinetics behavior. The decomposition of LLDPE/PP mixtures occurred earlier than that of calculated ones. However, the synergistic effect weakened with the increase of LLDPE in the mixtures. As for the chlorine removal, the LLDPE and PP hindered the chlorine removal from PVC during the plastic mixture pyrolysis. A noticeable negative effect on dechlorination was observed after the introduction of LLDPE or PP. Besides, the chlorine-releasing temperature became higher during the pyrolysis of plastic mixtures ([LLDPE/PVC (1:1), PP/PVC (1:1), and LLDPE/PP/PVC (1:1:1)]. These results imply that the treatment of chlorinated plastic wastes was more difficult than that of PVC in thermal conversion. In other words, more attention should be paid to both the high-temperature chlorine corrosion and high-efficient chlorine removal in practical. These data are helpful for the treatment and thermal utilization of the yearly increased plastic wastes.