Avaliação de processos de obtenção de biolubrificantes derivados do óleo de carnaúba

Abstract

In this work, carnauba oil was obtained by solvent extraction, and its use to obtain a biolubricant occurred through hydrolysis and esterification reactions via homogeneous and heterogeneous catalysis. Two catalysts (Amberlyst-15 and p-toluenesulfonic acid) were evaluated. For studies with heterogeneous catalyst, 2-ethylhexanol was used, and for the evaluation by homogeneous catalysis, trimethylolpropane was used. Both reactions took place for 6 hours, under reflux, magnetic stirring and inert atmosphere with nitrogen. In the heterogeneous catalysis the reaction temperature was 90 °C and in the homogeneous one, 107 °C, occurring in this reaction, the need to wash the material obtained to remove the catalyst with a 10% sodium bicarbonate solution. In heterogeneous catalysis, the catalyst was removed by vacuum filtration, and the alcohol by vacuum distillation. The characterizations of the oil and the synthesized biolubricants were obtained through physical-chemical analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). The low acidity value (0.14 mg KOH/g) and the high viscosity index (174) compete with the oil, its use in metallic systems, in addition to maintaining lubricity even with varying temperatures. Oxidation stability can be improved through the use of additives. For the biolubricant made with 2-ethylhexanol (B2ET), the viscosity, pour point and specific mass were close to the values presented by biolubricants from oils already studied, such as castor and macauba oil. And the biolubricant made with trimethylolpropane (BTMP) had a higher pour point, and additives can be used to reduce the pour point, good pour values suggest the use of biolubricants in countries with a cold climate. The high acidity values of 10 mg KOH/g (B2ET) and 6.65 mg KOH/g (BTMP) indicate the need for treatment of these products. The preference for using heterogeneous catalysts and carrying out sample treatment would reduce these acidity values. In Rancimat, the results obtained were not satisfactory, 6.81 hours for B2ET and 3.78 for BTMP. It is concluded that carnauba almond oil can be used as raw material for the synthesis of biolubricants through esterification reactions with the aforementioned alcohols and catalysts, requiring further studies as there is a need for process optimization.