Separate two-step and continuous two-stage pyrolysis of a waste plastic mixture to produce a chlorine-depleted oil

In this study, a separate two-step pyrolysis (using auger and fixed-bed reactors) and a continuous two stage pyrolysis (using auger and fluidized bed reactors) were conducted. This two-step pyrolysis was conducted to understand the effect of a 300 & nbsp; C & nbsp;thermal pretreatment with the auger reactor before main pyrolysis on the chlorine removal. The fixed-bed pyrolysis of a solid product obtained after the pretreatment produced an oil with 464 ppm chlorine. An oil with only 14 ppm of organic chlorine could be obtained when a solid containing CaO was pyrolyzed in the fixed-bed reactor. Thermal pretreatment also caused changes in the yield and product composition; pretreatment led to an increase in gas yield and aromatic content of the oil. In the continuous two-stage pyrolysis of a waste plastic mixture having 3 wt% polyvinyl chloride at 730 C, chlorinated gases were removed in parallel from the outlet of the auger reactor line and through a CaO hot filter; this produced an oil with 6.3 ppm organic chlorine. In the two stage pyrolysis, an aromatic-rich oil (80 wt%) was obtained. The two-stage pyrolysis successfully converted the waste plastic mixture into an oil which could be acceptable as a feedstock for petrochemical industries. (C)& nbsp;2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, two different pyrolysis methods were used to investigate the pyrolysis of waste plastics and analyze the effect of thermal pretreatment on chlorine removal and product composition. The results showed that the two-step pyrolysis could effectively remove organic chlorine and obtain an oil rich in aromatics.