Rapid Identification of Optimized Process Parameters Via RSM for the Production of Valuable Aromatic Hydrocarbons Using Multiphase Catalytic Pyrolysis of Mixed Waste Plastics

Abstract

This research work demonstrates the optimization of effective process parameters by response surface methodology (RSM) and experimental validation of M-type/multiphase catalytic pyrolysis of equally mixed waste expanded polystyrene and waste high-density polyethylene. The M-type/multiphase catalytic pyrolysis process of mixed feed was performed over ZSM-5 ammonium powder as catalyst (surface area = 400 m2/g, SiO2/Al2O3 = 200–400:1, Alfa Asear, USA) in a semi-batch reactor for the production of valuable target aromatic hydrocarbons benzene, toluene and ethylbenzene (BTE). The RSM predicted that maximum liquid yield of 73.86 wt. % was obtained at the optimum temperature of 553.28 °C, heating rate of 14.94 °C/min and feed-to-catalyst ratio of 22.48:1, whereas the actual maximum liquid yield of 73.72 wt.% was obtained using the optimized process parameters predicted by RSM. The negligible deviation of only 0.19% was found between actual/experimental liquid yield (73.72 wt.%) and predicted liquid yield (73.86 wt.%). The pyrolysis oil was obtained at the optimum condition having total BTE content of 31.83 wt.% and styrene content of 51.99 wt.%. The Fischer test value (< 0.0001) and probability value (1768.37) obtained by the analysis of variance indicate that the model is significant. The fuel oil obtained at the optimum a condition comes up with very high gross calorific value of 12,889 Cal/g, which indicates the presence of low molecular weight valuable hydrocarbons in the oil. © 2023, King Fahd University of Petroleum & Minerals.