Evaluation of Long‐Term Storage Stability of Palm Biodiesel Using Rancimat and PetroOXY Methods

Oxidative stability is a crucial parameter that determines the stability of a fuel during transport and storage. It is a measurement of fuel resistance to deterioration upon exposure to air, moisture, heat, and microorganisms that are present in real life environment. Fuel with poor oxidative stability is prone to oxidation and degradation, leading to the formation of undesired free fatty acids and polymer deposits that may cause failure at fuel pump and clogging of fuel injectors. In this study, the suitability of the PetroOXY method as a rapid alternative to the conventional Rancimat test for oxidative stability assessment was evaluated. Palm biodiesel and commercial biodiesel blends (B7, B10, and B20) were analyzed using both methods. A strong linear correlation was established for biodiesel samples ( R 2 = 0.9569), indicating that PetroOXY is a reliable tool for rapid screening of biodiesel oxidative stability. In contrast, only a moderate correlation was observed for the commercial biodiesel blends, likely due to the compositional complexity of fossil diesel hydrocarbons and variations in additive formulations. Antioxidant butylated hydroxytoluene (BHT) was found to be effective in retarding the biodiesel autoxidation upon prolonged storage. Palm biodiesel treated with a low dosage of BHT, that is, 50 mg/kg, was able to maintain the Rancimat induction period above 15 h even after 18 months of storage in typical laboratory conditions.