Catalytic cracking of wax pyrolysis oil derived from municipal plastic waste over aluminosilicate-based catalysts

Abstract

The formation of wax during the pyrolysis of municipal plastic waste has made it challenging to handle and valorize the resulting pyrolysis oil. This study evaluated the catalytic cracking process of wax pyrolysis oil produced from the pyrolysis of municipal plastic waste using three types of aluminosilicate-based catalysts, namely HZSM-5, bentonite, and spent FCC catalyst. The catalytic cracking was performed at 250 °C and 300 °C in a fixed-bed reactor to investigate the effect of catalyst type and temperature on yield, carbon distribution, and the physical-chemical properties of the liquid product. The results showed that the wax pyrolysis oil had a high heavy carbon content (>C₂₀) of 58.56 %. The use of HZSM-5 at 300 °C produced the highest oil yield of 78.8 wt%, while at lower temperature (250 °C) produced highest light fraction (≤C10) of 59.35 % with HHV of 47.90 MJ/kg. Spent FCC catalyst still showed competent potential at 300 °C, although its effectiveness is lower than that of HZSM-5. Oil products from the distillation showed that catalytic cracking using HZSM-5 was able to produce up to 80 wt% of the combined kerosene and diesel fractions at a temperature of 300 °C. The selection of catalyst and operating temperature is crucial for converting wax into high-value fuels, thus improving the effectiveness and sustainability of plastic waste pyrolysis.