A Review of the Desulfurization Processes Used for Waste Tire Pyrolysis Oil

Abstract

The increasing global population and the rapid industrial development associated therewith have increased the demand for fossil-derived fuel oils. The sources of fossil fuels are limited, and many studies have been being conducted to find alternative fuel sources. Waste tire pyrolysis oil (WTPO) attracts considerable attention as an alternative fuel because its properties are similar to those of diesel oil. However, WTPO has a high sulfur content of >1.0 wt%, which is above the environmental standard limit of 0.1 wt%; therefore, it cannot be used in engines directly. It is thus highly necessary to remove sulfur compounds from tire-derived oils. However, finding an appropriate and environmentally friendly process is proving difficult. This review article presents the various desulfurization methods used to removal sulfur from WTPO, such as hydrodesulfurization (HDS), oxidative desulfurization (ODS), ultrasound-assisted oxidative desulfurization (UAOD), and acid treatment. Of these, HDS is the most expensive as it involves high consumption of hydrogen, high temperature (~450 °C), and high pressure (~200 bar), whereas UAOD is an efficient and economic method of reducing the sulfur content of WTPO.