Pyrolysis of used lubricating oil using industrial waste-based catalyst for energy efficient fuel generation: A comprehensive review

The petroleum sector has proliferated since it was established and developed into an essential part of society, particularly in urban areas. Used lubricating oil (ULO), a leftover product of heavy petroleum hydrocarbon distillate, is responsible for rigorous environment pollution, and causes severe health hazards. Pyrolysis is considered as one of the efficient processes, which can efficiently manage ULO effectively diminishing its major adverse impact on the environment. If it is not managed, disposed of, or treated correctly, it can cause detrimental effect towards humans and the environment. The key objective of this review is to investigate catalysts, all the different parameters, and the reactor configurations that can impact the sustainability of ULO pyrolysis in liquid fuels. A comprehensive analysis of ULO pyrolysis is provided in this paper, which covers the following topics: (i) conventional methods, (ii) reactor layout, and (iii) benefits of catalytic pyrolysis. Considering costeffectiveness, better mixing, and a large surface area to perform the reaction, a fixed bed was found to be more suitable. However, with respect to combustion efficiency and emission features, electric pyrolysis performed as a better alternative. Although there exists a quality research scope in the future towards performing a comparative evaluation of oil quality on motor vehicle engine oils to introspect the emission properties, efficiency, and combustion process of pyro oil created in both non-catalytic and catalytic pyrolysis methods.