Kinetic model for the pyrolysis and combustion of poly-(ethylene terephthalate) (PET)

The kinetics of the global primary thermal decomposition of poly-(ethylene terephthalate) (PET) waste was studied in strict pyrolysis conditions and with different proportions of oxygen by TGA, between temperatures of 25 and 800 degreesC. Prior to the decomposition, the polymer first melts at around 250 degreesC. The pyrolysis of PET, which starts at 400 degreesC, is modeled assuming that it is formed by two different parts which decompose by two independent reactions. The introduction of oxygen produces the appearance of a new process, which does not start until the pyrolysis finishes. This fact is interpreted as the combustion reaction of the char formed in the pyrolysis, and was modeled kinetically with a common combustion reaction to the solid char residues obtained from each initial fraction. One pyrolysis run and one combustion run at 850 degreesC, at fuel-rich conditions were carried out to analyze the different gas compositions evolved, where an appreciable amount of poly aromatic hydrocarbons (PAH) was detected. (C) 2001 Elsevier Science B.V. All rights reserved.