Numerical analysis on a catalytic pyrolysis reactor design for plastic waste upcycling using CFD modelling

Catalytic pyrolysis technologies are a current trend to address plastic waste upcycling, offering lower energy consumption and higher value products when compared to conventional thermal pyrolysis. In this study, catalytic pyrolysis of HDPE was simulated using computational fluid dynamics (CFD) in order to analyze the physical behaviour of a designed fluidized bed reactor unit on a pilot scale. Dimensionless numbers were used for heat and mass transfer assessment to provide useful insights for the scale-up of this technology. A fluidized bed reactor configuration was selected for its effective heat/mass transfer and compatibility with ZSM-5 catalyst. Calculations were performed on a set of temperatures (300-500 °C) and feed rates (0.5-1 kg m^-2 s^-1) to determine the best performing conditions. Tradeoffs between conversion, production rate and heat consumption were discussed. The key results of this study indicate that a feed rate of 1 kg m^-2 s^-1 at 500 °C yields the best gasoline production while consuming the lowest amount of energy per kilogram of product.