Production, characterization and fuel properties of alternative diesel fuel from pyrolysis of waste plastic grocery bags

• High-density polyethylene grocery bags were pyrolyzed to alternative diesel fuel.
• Saturated aliphatic paraffins comprised most of the fuel composition (96.8%).
• Nearly all fuel properties were within ASTM D975 and EN 590 diesel specifications.
• Derived cetane number and lubricity were superior to conventional diesel fuel.
• Plastic derived diesel is suitable as a blend component for petroleum diesel fuel.

Pyrolysis of HDPE waste grocery bags followed by distillation resulted in a liquid hydrocarbon mixture with average structure consisting of saturated aliphatic paraffinic hydrogens (96.8%), aliphatic olefinic hydrogens (2.6%) and aromatic hydrogens (0.6%) that corresponded to the boiling range of conventional petroleum diesel fuel (#1 diesel 190–290 °C and #2 diesel 290–340 °C). Characterization of the liquid hydrocarbon mixture was accomplished with gas chromatography–mass spectroscopy, infrared and nuclear magnetic resonance spectroscopies, size exclusion chromatography, and simulated distillation. No oxygenated species such as carboxylic acids, aldehydes, ethers, ketones, or alcohols were detected. Comparison of the fuel properties to the petrodiesel fuel standards ASTM D975 and EN 590 revealed that the synthetic product was within all specifications after addition of antioxidants with the exception of density (802 kg/m3). Notably, the derived cetane number (73.4) and lubricity (198 μm, 60 °C, ASTM D6890) represented significant enhancements over those of conventional petroleum diesel fuel. Other fuel properties included a kinematic viscosity (40 °C) of 2.96 mm2/s, cloud point of 4.7 °C, flash point of 81.5 °C, and energy content of 46.16 MJ/kg. In summary, liquid hydrocarbons with appropriate boiling range produced from pyrolysis of waste plastic appear suitable as blend components for conventional petroleum diesel fuel.

Figure optionsDownload as PowerPoint slide