Analysis of Products Obtained from Slow Pyrolysis of Poly(ethylene terephthalate) by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Coupled to Electrospray Ionization (ESI) and Laser Desorption Ionization (LDI)

Abstract

The detailed composition description of poly­(ethylene terephthalate) (PET) pyrolysis products still remains a challenge due to the complexity of the obtained mixture. In this context, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses by negative ion electrospray ionization (−) ESI and positive ion laser desorption ionization (+) LDI were performed for characterizing waxy products and solid residues, respectively. (−) ESI FT-ICR MS revealed that the DBE of waxy compounds ranges from 5 to 20 and the carbon number from 7 to 30. Terephthalic acid was the dominant peak in the low m/z range, and 1,4-benzenedicarboxylic acid, 1,2-ethanediyl ester was evidence at higher m/z value. Based on the oxygen atom number, the waxy products displayed seven class compounds. The most significant contributions were observed for O4 and O8 species. van Krevelen plots revealed that the most abundant aromatic species followed a monotonous behavior (alignment according to a straight line), highlighting the presence of homologous series. The analysis of the solid residue by (+) LDI FT-ICR MS showed that three classes of compounds were observed: oxygenated compounds, carbonaceous materials, and hydrocarbons. As the temperature increased, the solid residue tended to be associated to a homogeneous structure consisting of fullerene clusters C n (with n ranging from 30 to 96 at 410 °C and from 50 to 106 at 480 °C). C60 was systematically the most abundant fullerene.

Upcycling poly(ethylene terephthalate) wastes by solvent extraction: Thermal stability and kinetics studies of the recovered PET

“…Aimed at the use of PET‐R as a chemical product for recycling or down‐cycling under an inert atmosphere 11,12 information on thermal properties are the essential part of the decision making 13 . It is known that the thermal decomposition of polymeric materials involves a large number of different reactions due to the conditions at high temperatures and the chemical complexity of the reactants before the observation of any weight losses.…”

“…This complexity has, in general, led researchers to study each polymer separately 14,15 . The kinetics and mechanism of the thermal decomposition of various resins, especially pure PET, have been studied at varying levels of detail by numerous investigators 1–20 …”

Catalytic pyrolysis of polyethylene terephthalate over zeolite catalyst: Characteristics of coke and the products

“…Very similar peaks with a slight different intensities were observed. At 3400 cm −1 , OH functional group 6,14 with a slightly higher intensity for the wax obtained from the non‐catalytic process appeared. At 3050 and 2950 cm −1 , ═CH and CH functionalities, which were assigned to alkenes and alkanes, were recorded 14 .…”

“…However, the plastics like polyethylene terephthalate (PET) are frequently used for making beverage bottles, packaging, electronics, etc 1‐5 . It was reported that in 2017 the production amount of PET was 30.3 million tons 6 . PET is non‐degradable and can pile up in the environment for a long time 1‐3 .…”

Photoconverting polyethylene terephthalate into exclusive carbon dioxide by heterostructured NiO/Fe2O3 nanosheets under mild conditions

“…To date, in addition to the traditional incineration and landfills, pyrolysis of PET has been largely reported and even applied in practice [6]. However, this process is often proceeded under high temperature and pressure, and the obtained products always encounter poor selectivity [7][8][9]. Also, the eco-friendly biodegradation of PET is deemed to be a potential strategy for converting PET into dimethyl terephthalate and ethylene glycol [10], whereas the bioenzymes are usually expensive.…”