Comparison of Pyrolysis Products from Sorted and Mixed Plastic Waste

Background. Pyrolysis-based processing of plastic waste is a promising direction. However, its outcomes are strongly dependent on feedstock composition. Studies systematically comparing the pyrolysis products of sorted and unsorted plastics are scarce, making clarification of these differences practically important for industrial applications.

Objective. To compare the yield and quality of solid, liquid, and gaseous pyrolysis products from sorted and mixed plastic waste based on scientific literature sources.

Materials and Methods. This review article is based on official data, peer-reviewed publications, and scientific literature. A search using the keywords: plastic pyrolysis, char, solid residue, sorted and unsorted plastic waste, fast pyrolysis yielded. The article selected 30 sources.

Results. The solid product yield from sorted PE/PP is approximately 1-10% by mass, while in mixed waste this figure reaches 10-25%. The carbon content of the solid product from sorted plastic waste is 75-90%, with ash content below 3%. For mixed plastic waste, these values correspond to 50-75% and 5-20%, respectively. Liquid product yield remains stable at 66-69% with no significant difference. However, chlorine content exceeds 150 ppm even after pre-treatment washing aimed at chlorine removal. Gas product yield in mixed waste is approximately twice as high - around 14% versus 8% - with 80% of chlorine converting to HCl in the gas phase, accelerating equipment corrosion.

Conclusion. Pyrolysis of mixed plastic produces predictable products, but chemical contamination renders all three product fractions unsuitable for industrial use. For practical application, pre-sorting of feedstock, hydrotreatment of the liquid fraction, and neutralization of HCl in the gas phase are recommended.