Valorization of waste tire by pyrolysis and hydrothermal liquefaction: a mini-review

An amount of 1.5 billion waste tires has been generated every year, resulting in serious environmental problems and damaging human health caused by landfilling and direct burning. One of the most effective valorization processes for the waste tire is to convert it into energy. To achieve this objective, pyrolysis and hydrothermal liquefaction (HTL) as two major thermochemical conversion technologies have been widely applied for producing liquid fuel from waste tire. This produced tire oil can be either used for energy purposes but also as the precursor to synthesize valuable chemicals such as benzene, xylene, toluene, and limonene. Within this framework, this review extensively summarized the recent studies focusing on the tire oil production by pyrolysis and HTL, along with the current applications of waste tire-derived oil. In addition, the available research regarding the use of solid product obtained from pyrolysis and HTL as an alternative to activated carbon for wastewater treatment and reinforcing filler is discussed. Furthermore, future directions and the main conclusions are provided.