Produção de biodiesel por transesterificação supercrítica do óleo de gergelim em reator de fluxo contínuo

Abstract

In view of the environmental conditions in the world today, the demand for renewable energy sources has increased more and more due to the need to reduce the pollution generated to the environment when using fossil fuels. Biodiesel stands out as one of these new energy sources due to its great variety in the raw materials that can be used in its production and also because of its biodegradability. The sesame seed presents in its composition a high oil content and its cultivation is favorable due to its ability to adapt to regions with a dry climate. Initially used in the food industry, the oleaginous plant shows potential as a natural source for biodiesel production, and this process has received substantial incentive through tax benefits on the purchase of biofuel from this plant. The transesterification reaction of sesame oil under supercritical conditions appears as an alternative to the most common method of biodiesel production, the catalytic transesterification, because there is no need to use a catalyst in the reaction, resulting in a simplification and possible savings in the process. This study used sesame oil and ethyl alcohol to produce biodiesel under supercritical conditions. The sesame oil physicochemical properties were determined, such as: density, acidity index, fatty acid content, viscosity and humidity. In the assays a continuous flow reactor of 15 mL volume was used, the system pressure was kept at 100 bar, varying the reaction temperature in the range 310-390 °C, with a residence time of 15-45 min and a molar ratio oil:ethanol of 1:30-1:50. From the results obtained in the variation of the operational parameters a statistical analysis was performed in order to verify the influence on the reaction yield. The best result obtained was 87.45%, at a temperature of 390 °C, residence time of 45 min and molar ratio oil:ethanol of 1:40. The statistical analysis revealed a greater influence of temperature and residence time on the results.