A comprehensive experimental investigation of plastic waste pyrolysis oil quality and its dependence on the plastic waste composition

• Published in: Fuel processing technology 2022-03, Vol.227, p.107090, Article 107090
• Main Authors: Kusenberg, Marvin, Zayoud, Azd, Roosen, Martijn, Thi, Hang Dao, Abbas-Abadi, Mehrdad Seifali, Eschenbacher, Andreas, Kresovic, Uros, De Meester, Steven, Van Geem, Kevin M.
• Format: Article
• Language: English
• Subjects: Alkenes; Chlorine; Contaminants; Gas chromatography; Packaging; Paraffins; Plastic waste; Polyethylenes; Polyolefins; Pyrolysis; Steam cracking; Thermochemical recycling; Two dimensional analysis; Two-dimensional gas chromatography
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2021.107090

Pyrolysis of plastic packaging waste yields a liquid product that can be processed in steam crackers producing light olefins and hence closing the loop towards new virgin plastics. However, there is a lack of knowledge on how the plastic waste composition affects the pyrolysis oil quality regarding hydrocarbon composition and contaminant concentrations. The associated uncertainty is a key reason why thermochemical recycling of contaminated plastic waste is not yet industrially established. In this study, post-consumer plastic packaging waste fractions, namely mixed polyolefins (MPO), polyethylene (PE), and polypropylene (PP) were processed in a continuous pilot-scale pyrolysis unit and the pyrolysis oils subsequently characterized using advanced analytical techniques such as two-dimensional gas chromatography. Substantial amounts of branched olefins (~63 wt%) and diolefins (~20 wt%) were detected in the pyrolysis oil of PP-rich waste, while PE-rich waste produced high amounts of linear paraffins (~34 wt%) and olefins (~26 wt%). Furthermore, significant amounts of nitrogen, oxygen, chlorine, iron, sodium and silicon were detected in the pyrolysis oils exceeding feedstock specifications for industrial steam crackers by orders of magnitude. The results show that next to improved waste sorting and separation processes, pre- and post-treatment techniques are required to produce pyrolysis products suitable for chemical processing. [Display omitted] •Pyrolysis of polyolefinic post-consumer plastic packaging waste.•Comprehensive two-dimensional gas chromatography coupled to various detectors.•PP-pyrolysis yields highly branched olefins, PE-pyrolysis mostly linear compounds.•Nitrogen, oxygen, chlorine, iron, sodium and silicon most important contaminants.•Upgrading or dilution needed when using pyrolysis oils as steam cracker feedstocks.