Evaluation of the Antioxidant Potential of Additives for Biodiesel produced from different processes / Avaliação do potencial Antioxidante de Aditivos para o Biodiesel produzido a partir de diferentes processos

• Autor(a) principal: Gonçalves, Jussara de Araújo
• Data de Publicação: 2020
• Outros Autores: Díaz, Gisel Chenard, Cruz, Yordanka Reyes, Aranda, Donato Alexandre Gomes
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Revista Veras
• Texto Completo: https://ojs.brazilianjournals.com.br/ojs/index.php/BRJD/article/view/17089
• topic: Biodiesel; Oxidative stability; Kinetics; Molecular modeling.

Soybean oil, used widely by its availability and accessibility as the principal feedstock for biodiesel production in Brazil, presents high susceptibility to oxidation, since it has high levels of unsaturated fatty acids.1 Use of a synthetic antioxidant, actually feasible and effective, could delay the onset of oxidation or reduce its rate for esters derived from oils and fats, one of the major causes of not specified biodiesel in the Brazilian legislation. In order to collaborate with industry on the storage of biodiesel in Brazil, this study tested several additives (0 to 4000ppm) still underused or unused on the market for this purpose and compared them with an additive widely used in the food industry, the butylhydroxytoluene – BHT.2-3 The research was divided in three steps. First step was established to verify the activities of pure additives and mixed with soybean biodiesel.4 For that, it was also, three main transesterification routes used in the Brazilian biodiesel production scenario were also tested, varying the type of catalysts and washing, monitoring stability in long term storage, antioxidant kinetic study and evaluation of specification of the additivated biodiesel. Step 2 mixtures of better performance additives from the first stage were submitted to biodiesel produced by the best process and evaluated in long-term storage tests, in the third stage blends of different types of biodiesel (soy with palm or tallow) were tested in proportions different. Results from step 1 showed that process Company 1 is the less harmful to the activity of the tested additives, mainly during de first month of storage. Most of cases had Kerobit 3627, followed by Kerobit TP26, BHT and Keromet MD100. In tests comparing acid washing steps and types of raw material, the influence of these parameters on esters stability is clear. Less pure raw material (degummed oil) and less aggressive washing (Company 1 process) gave better results. In step 2, it was possible to obtain a blend of additives between Kerobit 3627 and Keromet MD100 (1: 1) capable of conserving the ester for more than 5 years when stored at 25 °C. Soybean biodiesel blends with palm or tallow, richer in saturated esters, seemed to be an interesting alternative, with a inferior effect in the stability comparing it to the additives. At low temperatures, content of saturated ester is a determinant factor in the oxidation stability. On the other hand, time of storage almost not influenced oxidation. When at highest temperatures of storage, the benefit effect of saturated esters amount is minimum, but the time of storage is crucial to guarantee the integrity of the mixture.