Produção de ésteres metílicos de ácidos graxos do óleo de polpa de macaúba em reator contínuo

Abstract

The concern about the environment has been growing during the last decades, and one of the main environmental problems causers are the petroleum based fuels, which generate some of the gases that deteriorate the atmosphere. Among the possible substitutes for petroleum there is biodiesel, which can be produced using by the reaction of esterification, transesterification or hydroesterification of short-chain alcohols, as methanol and ethanol, and vegetable oils, and one of these oils is the macaúba pulp oil, common fruit in the center regions of Brazil, as the states Mato Grosso do Sul and Minas Gerais. Due to the fact that this oil is not part of human feeding and, for its high acidity, being considered a low-quality feedstock, its price happens to be a lot more accessible than other oils, as soy oil. The present study has evaluated the biodiesel production using mixtures of macaúba oil and methanol in a fixed-bed continuous reactor, using the acid resin Amberlyst® 15 Dry as heterogeneous catalyst, and varying the temperature from 100 to 120 ºC, pumping speed from 0,5 to 1,5 mL.min-1 and the molar ratio between oil and alcohol from 1:10 to 1:20, with samples being collected every 15 minutes from time zero during one hour. The results obtained by the process had an ester content varying from 13,91% to 55,87% in the final reaction product, result that can be considered as satisfactory, considering that the macaúba oil has a high free fatty acids content and has not passed by pre-treatment stages before the experiment to reduce its acidity. The pumping speed and temperature parameters showed negative effect over the ester conversion, and the molar ratio had proportional values to the biodiesel production. The interactions between the factors also presented significant influence over the results