Nonanoic acid esterification with 2-ethylhexanol: From batch to continuous operation

Nonanoic acid is considered a feedstock of growing interest due to the promising applicability of its derivatives. It can be obtained from vegetable oils, one of the products of oleic acid oxidation. Recently, a very interesting application of the ester obtained from nonanoic acid esterification with 2-ethylhexanol was found. In fact, it showed excellent properties as solvent for varnishes. The aim of this work was the kinetic investigation of the nonanoic acid esterification with 2-ethylhexanol in batch and continuous reactors, promoted by Amberlyst-15 and Amberlite IR120 resins, and to demonstrate the technical feasibility of the mentioned technology in flow systems. A mathematical model was developed to simulate the collected experimental data taking into account all the phenomena appearing in the system: intrinsic kinetics, mass transfer and flow pattern. Experiments were also conducted in the continuous packed bed reactor to compare the catalyst performances and validate the results obtained in the batch reactor. The best nonanoic acid conversion (85%) was obtained fixing T = 363 K, Q = 4.17·10⁻⁹ m³/s with an alcohol:acid molar ratio of 5:1 using Amberlyst-15 as heterogeneous catalyst.