Pyrolysis products from various types of plastics using TG-FTIR at different reaction temperatures

Pyrolysis products of low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and municipal plastic waste at different reaction temperatures were predicted in the current study using a newly developed thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) method. The experiments revealed that pyrolysis products of LDPE and PP at 500 degrees C were almost wax. Above 600 degrees C, wax formed from LDPE and PP almost disappeared, while the production of light hydrocarbons was enhanced. In the cases of LDPE and PP, the benzene and toluene formations were clearly observed above 800 and 700 degrees C, respectively. For PS, styrene was observed as the major component at 500-800 degrees C. With increasing temperature, the formations of alkenes, benzene, and toluene were enhanced at the expense of styrene. Different from other plastics, PET produced a pyrolysis vapor containing mainly CO2 and CO. FT-IR spectra of PET were almost unchanged despite increasing temperature above 600 degrees C. In the case of municipal plastic waste, the product distribution was similar to those of LDPE and PP. The new TG-FTIR method turned out to be an effective tool to predict pyrolysis products, especially gases products having low molecular weights.

Automated summary

In this study, a new TG-FTIR method was used to predict the pyrolysis products of LDPE, PP, PS, PET, and municipal plastic waste at different temperatures. The results showed that the pyrolysis products of LDPE and PP were primarily wax at 500°C. As the temperature increased, the production of light hydrocarbons increased, while the wax content decreased. Benzene and toluene formations were observed at temperatures above 800°C and 700°C for LDPE and PP, respectively. PS produced primarily styrene as the major component at 500-800°C, but with increasing temperature, the formations of alkenes, benzene, and toluene increased. PET produced mainly CO2 and CO as pyrolysis vapors, and the FT-IR spectra remained almost unchanged above 600°C. The product distribution of municipal plastic waste was similar to that of LDPE and PP. The new TG-FTIR method proved to be an effective tool for predicting pyrolysis products, especially gases with low molecular weights.