Waste tire pyrolysis and desulfurization of tire pyrolytic oil (TPO) – A review

: The nature of tires makes them extremely challenging to recycle due to the available chemically cross-linked polymer and, therefore, they are neither fusible nor soluble and, consequently, cannot be remolded into other shapes without serious degradation. The presence of tire waste on open fields or households creates an ideal breeding ground for disease-carrying vermin which pose a threat to humans. Also, disposal in landfills can lead to groundwater pollution by heavy metals and cause hazardous and uncontrolled fires. Owing to the growing environmental concerns, the exploration of economically viable and environmentally friendly techniques for the management of waste tires has been intensified in the recent past. Thermochemical routes such as combustion, gasification, and pyrolysis are important in the management of waste tires, reducing the environmental impacts of tire volarization, and allowing for the recovery of products. Given the depletion of fossil fuels and to meet the ever-growing demand for fuel energy, several initiatives to find alternative fuel sources are currently being taken. Fuel oil obtained from the pyrolysis of waste tires is becoming a promising alternative source of energy given its availability and higher heating value. Pyrolysis, an eco-friendly process, is the heating of matter in the absence of oxygen and is normally practiced for the thermochemical decomposition of different types of feedstock including biomass, coal, tires, and municipal solid waste. This paper reviews the current studies for pyrolysis of waste tires and multiple desulfurization technologies used for treating TPO globally. The detailed specification on operating conditions for the pyrolysis reactor in achieving desirable products in terms of composition and ratios are discussed.