Fuel production from waste polystyrene via pyrolysis: Kinetics and products distribution

Abstract

In the present study polystyrene waste (PS) was collected from a drop off site in a local market and pyrolyzed at heating rates of 5, 10, 15 and 20 °C/min and temperature range 40–600 °C under nitrogen condition. The apparent activation energy (Ea) and pre-exponential factor (A) were determined using 6 different kinetic methods. Activation energy and pre-exponential factor were found in the range of 82.3 – 202.8 kJmol−1 and 3.5 × 106–7.6 × 1014 min−1 respectively. The results demonstrated that the calculated values of Ea and A vary with fraction of conversion, heating rates and the applied model. Moreover, pyrolysis of waste polystyrene was carried out in an indigenously manufactured furnace at temperatures ranging from 340 to 420 °C. The composition of liquid and gaseous fractions was determined using gas chromatography-mass spectrometry. Temperature and reaction time were optimized and the results revealed that temperature of 410 °C and exposure time of 70 min are the best conditions for maximum fuel oil production. Methane and ethane were found as the main products in the gas phase constituting about 82% of the gaseous fraction. The liquid products composed of broad range of C2 – C15 hydrocarbons depending on the pyrolytic parameters. A comparison of the composition of pyrolysis oil with standard parameters of diesel, gasoline and kerosene oil suggested that pyrolysis oil from polystyrene waste holds great promise for replacing fuel oil.