Modeling the behavior of Celtis mildbraedii sawdust and polyethylene terephthalate co-pyrolysis for syngas production

Abstract

The co-pyrolysis behavior of Celtis mildbraedii sawdust (CMS) and polyethylene terephthalate (PET) waste for syngas production was investigated using a response surface methodology (RSM) based on Box-Behnken design (BBD). The production parameters were examined at a temperature, feedstock concentration (CMS/PET ratio), and nitrogen (N2) gas flow rate range of 600–800 °C, 50/50–80/20%, and 2–10 normal liters per minute (NL/min), respectively. A second-order regression model was used to predict the response with the outcomes analyzed using Minitab statistical software (version 19) at a 95% confidence interval. Results showed that CMS can be used solely and/or in a mixture with PET for pyrolysis. The syngas yield was influenced by the interactive effects of temperature and N2 gas flow rate with a significant p-value of less than 0.05. It was observed that temperature was the most influencing factor due to its high F-value of 355.06. The optimum yield of syngas was attained at a temperature of 800 °C, N2 gas flow rate of 6 NL/min, and feedstock concentration of a mixture of 50 wt.% of sawdust and 50 wt.% of plastic. At these conditions, the obtained syngas yield was 68.1 wt.%. In conclusion, the current study proves that co-pyrolysis has the potential to convert biomass and plastics to fuels and other green chemicals.