Incineration remains Europe’s main practice for plastic packaging waste treatment, primarily due to the limitations of mechanical recycling technology. Consequently, research and development of more sustainable and flexible approaches are of high importance. Thermochemical conversion of polypropylene, polystyrene, and municipal plastic packaging mix via high-temperature flash pyrolysis (1000 °C/s) is studied in this research, focusing on the kinetics and yields of the devolatilisation stage. The primary stage results in the formation of volatile organic compounds considered intermediate products for carbon black production. The experiments were conducted in a pressurised wire mesh reactor, investigating the influence of temperature (600–1200 °C), residence time (0.5–10 s), and pressure (1–25 bar). The positive effect of temperature on the volatile yield was observed up to 2–5 s. The devolatilisation stage was completed within a maximum of 5 s at temperatures ranging from 800 to 1200 °C. The pressure was determined to be a kinetically limiting factor of the process to up to 800 °C, and the effect was not present at ≥1000 °C. Raman spectroscopy measurements revealed that pyrolytic carbon deposited on the post-experimental meshes is structurally similar to the industrially produced carbon black. The kinetic data and developed model can be further applied in the upscale reactor design.

This study investigated the influence of hydrocarbon feedstock composition evolved from slow pyrolysis of polypropylene (PP) and polystyrene (PS) and plasma gas flow rate on the carbon black and hydrogen production yields and quality. The temperature distribution and feedstock flow within the carbon black formation zone with plasma were supplementarily modeled using computational fluid dynamics. TG-FTIR-GC/MS was employed to analyze thermal degradation patterns of plastics and to estimate the composition of volatile intermediates of plastics’ slow pyrolysis. Produced CB was characterized, encompassing physical, structural, and compositional properties using thermogravimetric analysis, CHNS analysis, scanning electron microscopy–energy dispersive spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and Raman spectroscopy. The results revealed that both feedstocks yield CB with comparable structural characteristics; however, PS-derived (aromatic-rich) volatiles produce significantly higher CB yields, whereas PP-derived (aliphatic) volatiles favor hydrogen formation. Differences in carbon structure were also observed, with PP-derived CB exhibiting a higher degree of graphitic ordering compared to the more disordered CB obtained from PS. The optimal flow rate of plasma gas was identified as 6.1 L/min. Increasing the flow rate to 7.2 L/min led to reduced conversion efficiency for PP-derived long-chain hydrocarbons. Overall, the findings demonstrate the potential of this approach for the co-production of high-quality carbon black and hydrogen from plastic waste.