Kinetic study of the catalytic cracking of waste motor oil using biomass-derived heterogeneous catalysts

[Display omitted] •Kinetic study of the chemical recycling of waste motor oil.•Biochar from biomass residues active towards the cracking process.•Alkali-treated rice husk biochar excels previously reported synthetic catalysts.•Diesel-like fuels, which resemble commercial diesel obtained. Herein, biochar from biomass residues is demonstrated as active materials for the catalytic cracking of waste motor oil into diesel-like fuels. Above all, alkali-treated rice husk biochar showed great activity with a 250% increase in the kinetic constant compared to the thermal cracking. It also showed better activity than synthetic materials, as previously reported. Moreover, much lower activation energy (185.77to293.48kJmol) for the cracking process was also obtained. According to materials characterization, the catalytic activity was more related to the nature of the biochar's surface than its specific surface area. Finally, liquid products complied with all the physical properties defined by international standards for diesel-like fuels, with the presence of hydrocarbons chains between C10-C27 similar to the ones obtained in commercial diesel.