Kinetic Study of Polyvinyl Chloride Pyrolysis with Characterization of Dehydrochlorinated PVC

Jiayang Wu, Konstantinos Papanikolaou, Feng Cheng, Bennett Addison, Amy Cuthbertson, Manos Mavrikakis, George Huber

Research output: Contribution to journalArticlepeer-review

Abstract

In this paper, we study the kinetics of polyvinyl chloride (PVC) decomposition using a combination of experimental and computational approaches. We develop a simplified kinetic model that contains only two steps: dehydrochlorination of PVC and further decomposition of the PVC residue. The model is consistent with density functional theory (DFT) calculations and experimental data. Dehydrochlorination is an autocatalytic reaction that starts with a tertiary chloride (Cl) and generates hydrogen chloride (HCl) and benzene as the main products. Benzene and HCl formation rates showed similar trends, indicating that HCl likely catalyzes a homolytic carbon-carbon (C-C) bond cleavage, which gives rise to benzene and an aliphatic fragment. We characterized the structure of dehydrochlorinated PVC (PVC residue) by using thermal gravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). FTIR and NMR results indicate that the PVC residue contains 20% quaternary carbon content, indicating a high concentration of cross-linked molecules. We predict that the most probable structure in the cross-linked centers of the PVC residue is cyclohexadiene, which is supported by DFT calculations, FTIR, and NMR.
Original languageAmerican English
Pages (from-to)7402-7413
Number of pages12
JournalACS Sustainable Chemistry and Engineering
Volume12
Issue number19
DOIs
StatePublished - 2024

NREL Publication Number

  • NREL/JA-2800-89924

Keywords

  • DFT calculations
  • kinetic model
  • plastic pyrolysis
  • PVC dehydrochlorination

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