Pilot-scale production of gasoline and diesel-like fuel from natural rubber scrap: Fractional condensation of pyrolysis vapors and optimization of pyrolysis parameters by using response surface methodology (RSM)

This paper aims to optimize the pilot-scale pyrolysis parameters of gasoline-like fuel (GLF) and diesel-like fuel (DLF) production from natural rubber scrap (NRS). The effect of final pyrolysis temperature and heating rate on pyrolysis yield and energy consumption were investigated using the response surface method (RSM). The multi-component mixture of NRS's pyrolytic oil was separated into multiple liquid products of differing compositions and properties. The distillation tests and compositions of fuel products were studied and compared with commercial fuels. It was found that the distillation curve of the fuel product was in the range of standard fuel. The GC–MS analysis also revealed high amounts of D-Limonene, which is the primary component in both GLF and DLF. Predicted GLF of 37.21 %wt and DLF of 35.76 %wt were obtained under optimal conditions with a final pyrolysis temperature of 508 °C and a heating rate of 4.3 °C/min. The influence of final temperature had a statistically significant effect on total biofuel, char, and gas. The heating rate had a significant effect on char and gas, GLF, and DLF, but had no statistically significant effect on total biofuel. Increasing the heating rate from 1.2 °C/min to 6.8 °C/min resulted in an approximately 11.7 % increase in the yield of gasoline products. The error falls within the acceptable limits (95 % prediction interval), affirming the model's accurate prediction of experimental results in this study. The property analysis indicates positive effects in terms of heating value, viscosity, density, and cloud point. However, certain drawbacks need attention, specifically regarding the corrosiveness and stability of the fuel.