Resumo

HURTADO-BURBANO, Eliana Paola  e  VILLA-HOLGUIN, Aída Luz. Kinetics of nopyl acetate synthesis by homogeneously catalyzed esterification of acetic acid with nopol. Rev.fac.ing.univ. Antioquia [online]. 2018, n.89, pp.16-25. ISSN 0120-6230.  https://doi.org/10.17533/udea.redin.n89a03.

The esterification of nopol with acetic acid to produce nopyl acetate using sulfuric acid as homogeneous catalyst was studied. The reactions were carried out in a batch reactor, at different temperatures (50, 60, 70 and 80 °C), catalyst concentrations (0.0184, 0.0275, 0.0367 and 0.0480 mol L-1) and molar ratio of acetic acid to nopol (1: 1, 1:2, 1:3 and 1: 4); the chemical equilibrium composition was measured at those reaction conditions. It was found that the equilibrium composition is a weak function of temperature, equilibrium conversion was 63, 68, 71 and 75% at 50, 60, 70 and 80°C, respectively. The reaction was described with a simple power-law model with a second-order kinetic model for both the forward and the backward reaction, using concentration and activities which were predicted by the Universal Functional group Contribution (UNIFAC) method for considering non-ideal behavior of the liquid phase. The forward reaction rate and the equilibrium constants increased with temperature; the relation of the pre-exponential factor with the catalyst amount was evaluated. The activation energy and pre-exponential factor estimated for the forward reaction using the kinetic model based on concentration, were respectively, 28.08 kJ mol-1 and 11126 L mol-1 h-1 with a concentration of catalyst of 0.0275 M. Using the kinetic model based on activities, the forward reaction rate constant was 28.56 kJ·mol-1 and the k fo,act was 33860 L mol-1 h-1. The enthalpy (34.90 kJ mol-1) and the entropy (0.12 kJ mol-1 K-1) of reaction were determined using van’t Hoff equation.

Palavras-chave : Activity coefficients; nopol; reaction rate; equilibrium constant; sulfuric acid.

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