Study on pyrolysis-derived oil from plastic waste using recycled additives under semi-pilot scale processes

• Three industrial waste additives were co-pyrolyzed with waste plastic from the real world. • The evaluation of pyrolysis oil products was carried out under a 1kg Semi-Pilot Scale process. • Pyrolysis process with spent FCC increased the 6.3% light cycled oil content than the control group. • Red mud resulted in the largest proportion of alkanes and the highest aromatization among the three. • Spent FCC has the potential to increase the economic value by around 10% at Semi-Pilot Scale. Plastic pollution has become one of the worldwide environmental challenges. In this study, the pyrolysis process of plastic waste, using three different recycled additives (spent fluid catalytic cracking, red mud, and fly ash), was evaluated at a semi-pilot scale, which could be a comprehensive method of using waste to deal with waste. Pyrolysis of 1 kg feedstock level at a semi-pilot scale was carried out in an independently developed rotary kiln reactor, and the characteristics of pyrolysis and oil products were comparatively analyzed. The results showed that even under low activity, the spent FCC additives (at 1:20 ratio) produced the highest quality, with a 6.3 % gasoline content increase over the sample without additives under stepwise heating to 500°C and 1:20 mass ratios for additives. Techno-economic analysis in this study indicated that the specific low-cost additives had the potential to increase the economic value by around 10 % at semi-pilot scale. Furthermore, the spent FCC shortened the overall pyrolysis process and increased the rate, with the weight loss rate being 30 % higher than with red mud or fly ash. The spent FCC increased the liquid product yield slightly and reduced the residual rate of the kiln by 5.5%, while both red mud and fly ash decreased the liquid product yield. Moreover, the oil product was subjected to Gas chromatography - Mass spectroscopy and simulated distillation to determine the distillation range and compound distribution. The pyrolysis process with red mud resulted in the largest proportion of alkanes and the highest aromatization degree of oil production among the three additives discussed in this study. This study provides a promising approach for the collaborative treatment of municipal waste and industrial waste, using plastic waste controlled by industrial recycled additives.