Chemical Feedstock Recovery from Hard-to-Recycle Plastics through Pyrolysis-Based Approaches and Pyrolysis-Gas Chromatography

Abstract

The entire world is moving toward carbon neutrality, and Japan is aiming to achieve a carbon neutral society by 2050. Generation of waste plastic is annually increasing, and the demand for waste plastic recycling is rapidly and globally growing to allow sustainable plastic use. Therefore, rapid and substantial promotion of plastic recycling technology is a global preferential task. The authors believe that pyrolysis is a promising strategy for recovering chemical feedstock from waste plastics, which improves global recycling capacity. Herein, global trends in waste plastic recycling were summarized in the first chapter, and feedstock recycling through pyrolysis-based approaches for hard-to-recycle plastic wastes such as polyethylene terephthalate (PET) and polyurethanes (PUs) were reviewed in the second chapter. Finally, the applicability of pyrolysis-gas chromatography (Py-GC) was verified by the investigation of the pyrolysis reaction mechanism, in situ pyrolyzate monitoring, and rapid screening of pyrolysis and catalytic reaction conditions.

Recycling of Plastic Waste: A Systematic Review Using Bibliometric Analysis

“…One of the most prominent research trends in pyrolysis worldwide is the production of fuel from plastic waste, with many commercialized plants already utilizing this method [34]. Considerable research has been conducted to optimize reaction conditions (e.g., temperature, residence time, pressure, equipment, process) and appropriate catalysts (e.g., cobalt, platinum, zeolite, aluminum chloride, organic matter) for producing fuel, depending on the type of plastic such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and PET [3,12,[35][36][37][38]. There is also research on recycling oils such as lubricants as products other than fuel [32].…”

Technological Advances in Mechanical Recycling Innovations and Corresponding Impacts on the Circular Economy of Plastics

“…Some experts view advanced plastic recycling as a failure. In some regions, mechanical recycling accounts for 22% of recycled plastic, chemical (feedstock) recycling for 3%, and energy recovery (combustion) for 60% [6]. This data has been used to create the illustration in Figure 2.…”

“…Pyrolysis is gaining attention as an optimal approach for recovering chemical feedstock from end-of-life plastics [6]. Several advantages of pyrolysis make it a desirable approach.…”

“…Nevertheless, some plastics cause corrosion and produce undesirable compounds when subjected to pyrolysis [20]. Polyvinyl chloride-and bromine-coated plastics corrode the recycling vessel and generate halogenated compounds [6]. Incinerating PVC releases a heavyduty pollutant, dioxin [21].…”

Application of Pyrolysis-Gas Chromatography for the Development of Chemical Recycling Process for Plastics

“…Fig 13. Aromatics composition and IPP conversion data obtained from the catalytic conversion of IPP using 0.3Ni/Y over 10 subsequent runs…”