Kinetics and modelling of levulinic acid esterification in batch and continuous reactors

The ethyl ester of levulinic acid, ethyl levulinate is a completely bio-based chemical made from levulinic acid, which is a hydrolysis product of cellulose and bio-ethanol. The very precise kinetics of levulinic acid esterification with ethanol was studied in an isothermal batch reactor in the presence of homogeneous (H₂SO₄) and heterogeneous catalysts (cation exchange resin Smopex-101). The temperature interval of the experiments was 50–70 °C. A kinetic model was proposed for both kinds of catalysts, adopting equilibrium rate expressions in any case. The different role of the catalyst used was considered separately, while a unique equilibrium constant was assumed for each system. The kinetic parameters were successfully determined by non-linear regression analysis. The model gave a very good description to the experimental data. The heterogeneous catalyst was used to demonstrate the feasibility of continuous operation in isothermal fixed bed reactors. The catalyst showed a good stability and high conversions of levulinic acid were obtained in the laboratory-scale fixed bed reactor. The model was able to predict both dynamic and steady-state experimental data.