Pyrolysis has been proposed as a potential technology for managing the growing volume of plastic waste generated worldwide. Co-pyrolysis of plastic waste with biomass is a promising technology for generating fuel and chemical products. However, this process generates tar as a waste product. The chemical properties of this tar have yet to be thoroughly analyzed. This contribution will present the results of gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) of oil and tar obtained from pyrolysis of pure plastics including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), and polystyrene (PS), mixtures of pure plastics, and mixtures of plastics with corn stover. GC-MS analysis reveals the presence of C7-C37 carbon-containing hydrocarbons, which include alkanes and alkenes as the dominant products. FTIR data supported the observed data from the GC-MS analysis showing IR stretch for alkanes and alkenes and also revealed the presence of a small number of various functional groups, including alcohols, aldehydes, ketones, and carboxylic acids, indicating the complexity of the pyrolysis and co-pyrolysis oil and tar obtained from waste plastics and biomass. TGA data shows that tar from all four plastics have a higher decomposition rate, suggesting the presence of heavier hydrocarbons compared with their corresponding oil which is consistent with the observed GC-MS data. Based on the analysis, the suitable tar model compounds for the plastic pyrolysis study of HDPE/LDPE/PP would be hydrocarbons containing C14 to C20, as they are the most abundant compounds seen on oil and tar from these plastics and toluene, xylene, and ethylbenzene would be suitable tar model compounds for PS plastic. These results will be beneficial in choosing a suitable plastic and plastic-biomass tar model compound for the tar mitigation study in waste plastic conversion research.
