Transient Methods to Intensify the Synthesis of Ethyl Levulinate

Levulinic acid, 4-oxopentanoic acid, is considered an attractive building block with widespread applications in various fields together with its derivatives. They can be used as lubricants, printing inks, corrosion inhibitors, products for personal care, and for drug delivery. In the present paper, attention was focused on the esterification of levulinic acid with ethanol promoted by a heterogeneous acid catalyst, in particular, an ion-exchange resin, namely, Amberlite IR120. The reaction was conducted in a continuous device by applying transient methods. This approach led to very attractive outcomes when compared to the traditional fixed bed reactor as water is removed continuously and the equilibrium is shifted, obtaining full conversion. A significant difference in performance is evident between the two operational modes. With a classical packed bed reactor, the maximum levulinic acid conversion was 31% at 363 K and a flow rate of 3.33 × 10–8 m3/s, while by applying the transient method under the same conditions, the levulinic acid conversion rose to 94%. Kinetic tests were performed at different temperatures, varying the volumetric flow rate during the tests. Nearly complete conversion of levulinic acid was achieved in experiments conducted at temperatures of 313, 323, 343, and 363 K. Furthermore, high conversion, reaching 90%, was also attained at a lower temperature of 293 K. The experimental data were successfully interpreted with a mathematical model to retrieve kinetic and thermodynamic parameters. Finally, the fluid-dynamic characterization of the system demonstrated that the reactor worked with plug-flow behavior.