Investigation of Chemical, Physical, and Tribological Properties of Pyrolysis Oil Derived from End-of-Life Tires (ELTs) against Conventional Engine Oil

• Published in: Lubricants 2024-06, Vol.12 (6), p.188
• Main Authors: Alazemi, Abdullah A., Alajmi, Abdullah F., Al-Salem, Sultan M.
• Format: Article
• Language: English
• Subjects: Carbon black; Chemical properties; Electron microscopes; End of life; Energy consumption; Fourier transforms; Hydrocarbons; Hydrogen; Investigations; Landfill; Low speed; Lubricants; Lubrication; Mechanical properties; oil thermal stability; Pyrolysis; pyrolysis process; Raw materials; recycled tires; Recycling; Refuse and refuse disposal; Rheological properties; Rheology; Rubber; Scanning electron microscopy; Solid wastes; Sulfur compounds; Sulfur content; Thermal stability; Tires; Tribology; Viscosity; Waste management; Wettability; Wetting
• ISSN: 2075-4442; 2075-4442
• DOI: 10.3390/lubricants12060188

Over one billion rubber tires are disposed of worldwide annually as a major component of the solid waste stream, posing a significant environmental risk. Therefore, recycling and taking advantage of the rubber component in End-of-Life Tires (ELTs) presents an advantageous opportunity to produce environmentally friendly and cost-effective products. This work studied multiple properties of oil extracted from ELTs using thermal pyrolysis (i.e., pyro-oil) as a potential candidate for industrial lubrication applications. First, pyro-oil was characterized by studying its morphological and chemical properties. Then, rheological studies were conducted to explore the oil properties at different temperatures and shear rates. A tribometer was also used to assess pyro-oil’s tribological performance at different temperatures and speeds. Finally, wettability and thermal analyses were performed to understand the wetting and thermal stability properties. The results revealed that pyro-oil has chemical properties similar to conventional engine oil with slightly higher sulfur content. Furthermore, the pyro-oil exhibited lower viscosity and lubrication performance than conventional engine oil, but this difference was smaller at higher temperatures. Thermal stability and wetting properties of pyro-oil were found to be significantly lower than those of conventional engine oil. Based on the properties found and compared with engine oil, pyro-oil presents itself as a suitable liquid lubricant for low-speed, low-load applications operating in temperatures below 61 °C. This work presents a comprehensive study of pyro-oil properties extracted from end-of-life waste tires, offering a feasible route to obtain sustainable and low-cost products.