Physicochemical properties of pyrolytic char and oil from mixed tyre using batch pyrolysis process

• End-of-life tyres can be converted to energy products through pyrolysis process. • Pyrolysis of mixed tires produces 55% oil and 40% char. • Mixed tyre pyrolysis oil has high calorific value but lacks other properties for use an engine fuel. • Mixed tyre pyrolysis char contains 70% carbon but lacks sufficient surface area for use an absorbent. End-of-life tyres (EOLT) has several adverse impacts to the environment, so it’s disposal to landfill is not wise. Rather, it can be converted to energy products through thermo-chemical conversion processes. One of the thermo-chemical conversion processes is called pyrolysis. A batch pyrolysis experiment was conducted for EOLT using a 20L pyrolysis reactor at 540 °C temperature with atmospheric pressure for 3 h to produce char, oil and syngas. Feedstock was mixed tyres, which is a mixture of light, medium and heavy tyre at 1:1:1 ratio. The focus of the study was to investigate the physicochemical properties of oil and char produced from pyrolysis. Thermogravimetric and FTIR analysis was performed to characterise oil. The study found that pyrolysis reactions started at 280 °C and completed at 515 °C with about 40 % char/residue. The properties of the mixed tyre pyrolytic oil (MixTPO), such as higher heating value (HHV), density, flash point, etc, were analysed and compared with petroleum fuel such as diesel and kerosene. Although MixTPO had a high calorific value of 42.00 MJ/kg, other properties such as viscosity, flash point, water content do not allow its direct use as an engine fuel. Physical properties (Surface area) and chemical properties (elemental analysis, ash content and composition) of the pyrolytic char were examined. It was found from the Mmcroanalytical tests that tyre pyrolytic char (TPC) contains 70 %–90 % pure carbon with some impurities like oxygen, zinc, and sulphur. It’s BET surface area is low (15.89 m 2 /kg) which makes it unsuitable to use as an absorbent, requiring further microstructural improvement. The findings signify that though waste tyre can be converted into various valuable energy products (oil, char and syngas) through pyrolysis which has high commercial value, liquid oil needs further treatment to use as an automobile fuel and char needs microstructural improvement to use as an absorbent. Further study is recommended.