Evaluation of the stability during storage of a diesel-like fuel obtained by the pyrolysis of soybean oil

In this work, we investigated the stability of a diesel-like fuel (DLF) produced by the pyrolysis of soybean oil. The soybean DLF was stored at room temperature over a period of six months in three different tanks. The tanks were made of high-density polyethylene (HDPE) and stainless steel 304, with and without an epoxy resin protection. Samples were collected at various times, and their physical–chemical parameters (viscosity, density, distillation curve, etc.) were obtained according to ASTM methods, as recommended for diesel fuel evaluation. Increases in the viscosity and density during storage were attributed to polymerisation reactions, which often lead to the formation of more viscous and dense materials. Additionally, gas chromatographic analyses showed a decrease in the content of light fractions during storage. The Rancimat method could not be applied to evaluate the oxidation stabilities for the samples. Instead, oxidation stabilities were evaluated by the consumption of O2 at high pressures at 100 °C in comparison to a soybean biodiesel sample. Although changes in the physical–chemical parameters occurred during storage, the majority of the results remained within the limits specified by the Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP) for diesel fuel. Overall, the results showed that the differences in the materials for the tanks used for DLF storage did not interfere with the biofuel parameters.