Waste lubricating oil valorization via NaOH-Catalyzed Cracking: A resource recovery approach for cleaner fuel production

Abstract

Waste lubricating oil (WLO), an environmental hazard yet a recoverable resource, was converted to diesel-like fuel using continuous catalytic cracking with 48 % (w/w) NaOH as a base catalyst, differing from conventional acid-catalyzed methods. Post-treatment with activated bentonite effectively removed residual water, polar impurities, and color. The system—involving dehydration, atmospheric distillation, catalytic cracking (300–350 °C), condensation, and separation—achieved a 71.2 % (v/v) fuel yield. Reactor thermal profiling revealed distinct heating/dehydration, minor hydrocarbon cracking, and diesel-range hydrocarbon production zones. This approach shows significant promise for sustainable WLO valorization and reduced environmental impact. However, further fuel characterization (e.g., sulfur, cetane number) and process optimization are advised. This study advances sustainable WLO management and resource recovery within a circular economy.