PAH formation from the pyrolysis/gasification of PVC at different reaction conditions

Hui Zhou, Chunfei Wu, Jude A. Onwudili, Aihong Meng, Yanguo Zhang, Paul T. Williams

Research output: Chapter in Book/Published conference outputConference publication

Abstract

PVC is an abundant component in municipal solid waste (MSW). Polycyclic aromatic hydrocarbons (PAHs) are toxic compounds during the pyrolysis/gasification of MSW. In this work, the formation of 2-4-ring PAHs from the pyrolysis/gasification of PVC at different temperature, heating rate and atmosphere was investigated in a fixed bed furnace. The PAHs in tar were quantitatively tested using gas chromatography/mass spectrometry (GC/MS). The results showed that, with the increase of temperature from 500 to 900 °C, HCl yield decreased from 54.7 to 30.2 wt.%, while the yields of tar and the non-condensable gases (H2, CH4, and C2-C4) were increased. Quantitative tar analysis showed that naphthalene yield decreased when the pyrolysis temperature was increased from 500 to 600 °C, and increased from temperature was further increased from 600 to 900 °C. Methylnaphthalenes yields were increased with the increase of temperature from 500 to 700 °C, and decreased with the temperature from 700 to 800 °C due to demethylation reactions. Other PAHs yields were increased with the increase of pyrolysis temperature from 500 to 900 °C. Comparing to fast pyrolysis, slow pyrolysis generated higher HCl yield, and lower gas and tar yield. The PAHs yield obtained from slow pyrolysis was much lower than that from fast pyrolysis. Comparing to pyrolysis in N2, naphthalene yield was increased, and other PAHs, especially 4-ring PAHs yield were decreased for gasification in air. All the PAHs were decreased in CO2 atmosphere compared with that in N2. In the fast pyrolysis process, with high heating rate, the processes of dehydrochlorination and chain scission happened in a very short time. Therefore, the dehydrochlorination process might be incomplete, and some chlorine in PVC might present in the chlorinated compounds, such as chlorobenzenes (CBz). Under a high temperature environment, with the presence of O2, the interaction of HCl and aromatic hydrocarbons (benzene, PAHs and their derivatives) can produce chlorinated species, which are thought to be polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) precursors. Meanwhile, in the presence of oxidants e.g. air or CO2, PAHs or their precursors could be oxidized, thus less PAHs were generated.

Original languageEnglish
Title of host publicationAir and Waste Management Association - International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors 2014
PublisherAir and Waste Management Association
Pages161-173
Number of pages13
ISBN (Electronic)9781510800236
Publication statusPublished - 1 Jan 2014
EventInternational Conference on Thermal Treatment Technologies and Hazardous Waste Combustors 2014 - Baltimore, United States
Duration: 13 Oct 201415 Oct 2014

Publication series

NameAir and Waste Management Association - International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors 2014

Conference

ConferenceInternational Conference on Thermal Treatment Technologies and Hazardous Waste Combustors 2014
CountryUnited States
CityBaltimore
Period13/10/1415/10/14

Keywords

  • Gasification
  • PAH
  • PVC
  • Pyrolysis
  • Temperature

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