Synthesis of ethyl esters from crude macauba oil (Acrocomia aculeata) for biodiesel production

The Macauba (Acrocomia aculeata) possesses high potential for the production of biodiesel. The species' fruits can be used for several purposes. The physical-chemical properties of the oil and ethyl esters were evaluated. During the storage period, the macauba pulp oil presented an increase of 25.4% in acid value. To obtain ethyl esters from a crude oil with high acid value without pre-treatment, the reactions were conducted in an under-pressurized Parr 4843 reactor. Moreover, an experimental delineation was conducted to study the esterification and obtain the proper concentrations of the ethanol and catalyst, as well as the correct temperature, to provide the best yield in ethyl esters. The quantified esters via gas chromatography (GC) and the response surface graphs optimized the reaction in the conditions of temperature (100-115 °C), Ethanol:Oil Molar Ratio (8-12) and catalyst (sulfuric acid) (1.0-1.5%), as specified. For all the conducted analyses, the produced biodiesel was within the Petroleum National Agency's (ANP) parameters. It was possible, via esterification, to achieve ethyl esters content close to the limit established by the ANP, for raw macauba oil with high acid values, which turned out to be suitable for biodiesel production due to a low-cost feedstock that also possesses a comprehensive vegetative disponibility.