Pyrolysis of bottle‐grade polyethylene terephthalate: Effect of carrier gases on carriage of pyrolysis products

The production of widely‐used bottle‐grade polyethylene terephthalate (PET) is now considered an environmental problem on a global scale. The urgent need for renewable energy reveals the necessity of employing thermochemical recycling methods. The use of a carrier gas is among the parameters affecti...

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Bibliographic Details
Published in:Polymer engineering and science 2022-08, Vol.62 (8), p.2524-2531
Main Authors: Atashi, Farid, Gholizadeh, Mortaza, Ataei, Farshad
Format: Article
Language:English
Subjects:
biofuel
carrier gas
Carrier gases
Environmental aspects
Gases
Hydrogen production
Methods
Molecular weight
Nitrogen
PET
Plastic scrap
plastic waste
Polyethylene terephthalate
Process parameters
Production processes
Pyrolysis
Reforming
renewable
Stability analysis
Thermal stability
thermochemical
Waxes
Weight loss
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Summary:The production of widely‐used bottle‐grade polyethylene terephthalate (PET) is now considered an environmental problem on a global scale. The urgent need for renewable energy reveals the necessity of employing thermochemical recycling methods. The use of a carrier gas is among the parameters affecting the pyrolysis process, for it is responsible for carrying pyrolysis products to separate condensable products. In this study, PET granules were pyrolyzed at 500°C with three carrier gases: N2, He, and Ar. According to the results, using a gas with lower molecular weights increased the production of gaseous products (30.94%). However, using a gas with higher molecular weights led to the production of further char (20.2%) associated with the increased reforming reaction rate and hydrogen production in the gaseous phase. The presence of different carrier gases changed tar composition and aromatics; therefore, the highest acid benzoic level was detected in the nitrogen atmosphere. Evaluating the thermal stability of wax and char indicated that the weight loss of char was larger in nitrogen (44.8 wt%) than in the other two carrier gases. However, there were further heavy oxygenated components in wax under the helium and nitrogen atmospheres. Those components degraded more difficultly. PET granules were pyrolyzed in N2, He and Ar to evaluate the effect of carrier gas on the products. The molecular weight of the carrier gas was found a key parameter influencing the yields and specifications of the products from the pyrolysis of PET.
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.26025