Kinetic modeling for levulinic acid esterification in gamma-Valerolactone taking into account acid dissociation

The first goal of this work is to demonstrate that using an aprotic polar solvent, such as γ- valerolactone instead of a protic polar solvent (i.e. ethanol, water), increases the yield of the esterification reaction of levulinic acid with ethanol, in presence of an acid catalyst. In fact, it is believed that an aprotic polar solvent can improve the catalytic activity of protons. The second goal is to study the influence of the variation of some parameters on the mentioned reaction. This was done by structuring the work in two sections: experimental and modelling. In the first section, two kinetic experiments were performed: one in presence of ethanol as solvent and one in presence of γ-valerolactone solvent, in order to achieve the first goal. After, different kinetic experiments were conducted, varying the process variables (i.e., temperature, catalyst concentration, molar ratio between reactants) in turn, in order to investigate their influence on the product’s yield. All experiments were performed in a batch custom reactor under isoperibolic and isobaric conditions and using γ-valerolactone as solvent. In the second section, the experimental data obtained were used in the modelling. Since the dissociation of all acids present in the esterification system was considered, an algebraic equation for the proton concentration was obtained and solved simultaneously with the differential equations (ODE) describing the molar balances. In this way, kinetic and thermodynamic parameters have been estimated.