Kinetics of nopyl acetate synthesis by homogeneously catalyzed esterification of acetic acid with nopol/Cinetica de la sintesis de acetato de nopilo mediante esterificacion de acido acetico con nopol homogeneamente catalizada

• Published in: Revista Facultad de Ingeniería no. 89; p. 16
• Main Authors: Hurtado-Burbano, Eliana Paola, Villa-Holguin, Aida Luz
• Format: Journal Article
• Language: Spanish
• Published: Universidad de Antioquia, Facultad de Ingenieria 01-12-2018
• ISSN: 0120-6230
• DOI: 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 [degrees]C), catalyst concentrations (0.0184, 0.0275, 0.0367 and 0.0480 mol[L.sup.-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[degrees]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.sup.-1] and 11126 L[mol.sup.-1][h.sup.-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.sup.-1] and the kfoact was 33860 L[mol.sup.-1][h.sup.-1]. The enthalpy (34.90 kJ[mol.sup.-1]) and the entropy (0.12 kJ[mol.sup.-1] [K.sup.-1]) of reaction were determined using van't Hoff equation. KEYWORDS: Activity coefficients, nopol, reaction rate, equilibrium constant, sulfuric acid Se estudio la esterificacion de nopol con acido acetico para producir acetato de nopilo utilizando acido sulfurico como catalizador homogeneo. Los experimentos se llevaron a cabo en un reactor por lotes variando la temperatura (50, 60, 70 y 80 [degrees]C), la concentracion del catalizador (0.0184, 0.0275, 0.0367 y 0.0480 mol[L.sup.-1]) y la relacion molar de acido acetico a nopol (1: 1, 1:2, 1:3 y 1: 4); la composicion del equilibrio quimico se midio a las condiciones de reaccion. La conversion de equilibrio fue 63, 68, 71 y 75% a 50, 60, 70 y 80[degrees]C, respectivamente. La reaccion se describio con un modelo de potencia simple con un modelo de segundo orden en ambas direcciones, usando concentraciones y actividades, las cuales se predijeron con el metodo de contribucion de grupos UNIFAC. Se determinaron las constantes de velocidad de la reaccion directa y la constante de equilibrio, las cuales aumentaron con la temperatura; se evaluo la relacion del factor pre-exponencial con la cantidad de catalizador. La energia de activacion y el factor pre-exponencial estimados para la reaccion hacia adelante usando el modelo basado en concentracion fueron respectivamente 18.08 kJ[mol.sup.-1] y 11126 L[mol.sup.-1] [h.sup.-1] con una concentracion de catalizador de 0.0275 M. Usando el modelo basado en actividades la constante de velocidad directa fue 28.56 kJ[mol.sup.-1] y el factor pre-exponencial 33860 L[mol.sup.-1] [h.sup.-1]. La entalpia (34.90 kJ[mol.sup.-1]) y la entropia (0.12 kJ[mol.sup.-1][K.sup.-1]) de reaccion se determinaron usando la ecuacion de van't Hoff. Coeficientes de actividad, nopol, velocidad de reaccion, constante de equilibrio, acido sulfurico