Estudo cinético da reação de saponificação do acetato de etila em reator batelada

Abstract

The use of practical methodologies as a teaching tool allows students to have contact with physical-chemical phenomena, enabling theoretical limits to be confronted and promoting the development of analytical skills to solve problems. The traditional teaching of chemical reaction engineering is based on the exposition of concepts, theories, and equations without sufficient contact with practical methodologies capable of promoting critical thinking among students. Given this, the present study aimed to experimentally determine the kinetic parameters of the saponification reaction of ethyl acetate in the presence of sodium hydroxide, using the batch reactor of a chemical reactor unit made available by the chemical engineering laboratory of the Universidade do Estado do Amazonas. Additionally, the objective was to develop a practical lesson plan so that other chemical engineering students can benefit from it during chemical kinetics and homogeneous chemical reactors classes. The kinetic parameters determined were partial and global orders, activation energy, and frequency factor. The physical-chemical property used to monitor the reaction was conductivity. Both the differential and integral methods were used to acquire kinetic data. Three experiments were carried out with the concentration of ethyl acetate at 0.3 mol/L, three times higher than that of sodium hydroxide: 0.1 mol/L. Then, three other experiments were performed under the inverse conditions: ethyl acetate at 0.1 mol/L and sodium hydroxide at 0.3 mol/L. It was experimentally proven that the saponification reaction of ethyl acetate in the presence of sodium hydroxide is of global order 2, with a partial order of 1 for each of the reactants, as suggested by the literature. To obtain the temperature-dependent kinetic parameters, the reaction was carried out with stoichiometrically fed reactants, both at 0.1 mol/L, at four temperature ranges: 26.7 °C, 32.4 °C, 35 °C, and 41.6 °C. Three experiments were conducted for each range. The obtained value for the activation energy was 31.0562 kJ.mol-1 , reasonably close to the values reported in the literature. However, the obtained value for the frequency factor was 6.0415 x 104 L.mol-1 .s-1 , differing from the values reported in the literature. Nevertheless, the chemical reactor unit and the batch reactor used proved to be useful for evaluating the kinetics of homogeneous chemical reactions and, consequently, for the practical teaching of chemical reaction engineering.