Assessment of commercial acidic ion-exchange resin for ethyl esters synthesis from Acrocomia aculeata (Macaúba) crude oil

Abstract This study aimed to obtain ethyl esters (EEs) from macauba pulp crude oil, using heterogeneous-acid catalyst, varying the temperature of (trans)esterification, ethanol-to-oil molar ratio (MR) and catalyst content. Catalyst Amberlyst 15 characterization showed high concentrations of active sites of 3400 μmol g−1 and a surface area of 31.3 m2 g−1, which associated with the resin macroporous structure. A Central composite rotational design (CCRD) 2³ design and response surface methodology (RSM) were used to analyze the studied variables effects on the EEs production: temperature (80–180 °C), ethanol-to-oil MR (4–14) and catalyst Amberlyst 15 content (1–20 wt%). EEs formed were quantified by gas chromatography, and the RSM showed that the reaction presented EEs yields greater than 85% with a high index selectivity (817.4). The desirability procedure showed, that for both Free fatty acids (FFAs) conversion and EEs yield, the optimum conditions were the same, being 130 °C, ethanol-to-oil MR 9 and 16 wt% of catalyst. The biodiesel obtained was characterized and all the analyzed parameters agreed with the national biofuel-monitoring agency. The process conditions and the characterization of produced EEs showed that macauba crude pulp oil has good potential for biodiesel production using heterogeneous acid-catalyst.