Pyrolysis of municipal plastic waste: Chlorine distribution and formation of organic chlorinated compounds.

ABSTRACT

The release of chlorine during the pyrolysis of actual municipal plastic waste (MPW) was studied. Firstly, thermogravimetry-Fourier transform infrared (TG-FTIR) was analyzed to investigate the chlorine release behavior. Then, the effect of temperature on chlorine migrations was investigated by fast pyrolysis experiments in a fixed bed reactor. Results showed that chlorine released mainly between 241 and 353 °C in the form of HCl or chloroesters during MPW pyrolysis. After pyrolysis, chlorine was mainly distributed in the pyrolytic gas (74.34-82.89 %) and char (10.17-21.29 %). However, the release of chlorine was inhibited due to the melting behavior of MPW at <350 °C. Besides, the relative contents and types of organic chlorinated compounds in liquid products were both decreased with temperature. It was observed that polyethylene terephthalate (PET) was the greatest contributor to the formation of organic chlorinated compounds during MPW pyrolysis. Meanwhile, the pyrolysis of PET was significantly promoted by the HCl released from polyvinyl chloride (PVC). Subsequently, the pathways for the formation of organic chlorinated compounds through the co-pyrolysis of PVC and PET were proposed, including the initial degradation and subsequent chlorination of PET. These findings provided new insights into the release and regulation of chlorine-containing pollutants during actual MPW pyrolysis.