Wax Recovery from the Pyrolysis of Virgin and Waste Plastics

Abstract

Thermochemical conversion is an effective technique for the treatment of polyolefin plastics to produce value-added products, including oils and chemical waxes. The recovery of wax from the pyrolysis of virgin high-density polyethylene (HDPE), low-density polyethylene (LDPE), and plastic solid waste (PSW) in a patented fixed-bed reactor has been investigated in this study. The highest wax yield (64.5 wt %) was obtained from LDPE at 500 °C. Results show that the average densities of the waxes recovered from PSW, HDPE, and LDPE are 851.7 ± 1.0, 849.4 ± 5.3, and 879.5 ± 2.2 kg m-3, respectively. These values are similar to that of commercial wax and slightly higher than that of commercial paraffin wax. Considering their energy content, the waxes studied can be used as sources of fuel. The calorific values of the recovered waxes are estimated to be in the range of 45.61-46.22 kJ g-1, which is in the acceptable range of commercial kerosene, gas oil, and light fuel oil. Furthermore, the waxes obtained have flash points that are above the specifications of diesel fuel, indicating that they fall within the acceptable flammability range.