Thermal Pyrolysis of Waste Polyolefins to Generate Alternative Liquid Fuel

Abstract

Waste plastics are the cause of great environmental issues because they are non-biodegradable. In this work, waste polyolefins plastics of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and Polypropylene (PP) were separately subjected to pyrolysis in a fixed bed batch reactor within the temperature range of approximately 300 – 510 °C and heating rate of 12 ℃/min. The result of the pyrolytic oil obtained was characterized and all yields above 50 % in terms of the liquid oil. PP with 58.6 % has the highest oil yields slightly above LDPE with 54.3 % and HDPE with 51.5 %. The gaseous effluents calculated by the difference between the oil collected and char residue were higher for HDPE at 43.4 %, followed by LDPE at 39.2 % and PP at 36.8 %. The analysis of pyrolytic oil and Liquid fuel shows that the specific gravity, pour point, and flashpoint are 0.775, -4.5 °C, 23 °C respectively. Specific gravities were slightly lower than the lower limit of the Department of petroleum resources (DPR) approved a range of 0.820 but approximately equal to that of virgin gasoline. However, the kinematic viscosity @ 40 (mm2/sec) and the flashpoints were within the approved range. The investigation revealed that the GC-MS analysis of the oils to contain aliphatic and cyclic hydrocarbons in the range of Diesel and kerosene fuel. Hence waste plastic can serve as an alternative source of energy.