Fatty acid epoxidation on enzymes: Experimental study and modeling of batch and semibatch operation

“Biolubricants, plasticizers, bio-based rigid foams, and non-isocyanate polyurethanes can be made in a green way from epoxidized fatty acids. The classical technology for fatty acid epoxidation requires a reaction carrier, which acts as the real epoxidation agent. The process is complicated and involves a safety risk because of the appearance of percarboxylic acids. Therefore, the direct epoxidation of fatty acids in the presence of an immobilized enzyme is an attractive pathway to epoxidized fatty acids. Oleic acid was used as the model compound is this work, and commercial immobilized lipase Novozym 435 was used as the catalyst and hydrogen peroxide as the epoxidation agent. Batch and semibatch operation modes were tested in a laboratory-scale stirred tank reactor. The experimental results showed that almost complete conversions of the double bonds in oleic acid were achievable under isothermal batch and semibatch operation, with low concentrations of ring-opening byproducts. Semibatch operation gave an improvement of the product yield. Mathematical modeling of the experimental data was based on the reaction stoichiometry OA + HP → POA + W and OA + POA → EOA + OA, where OA = oleic acid, HP = hydrogen peroxide, POA = peroleic acid, W = water, and EOA = epoxized OA. Rate equations for the formation of peroleic acid and epoxide were derived, and the numerical values of the kinetic and adsorption parameters were estimated with nonlinear regression analysis. The reactor models consisted of ordinary differential equations, which were solved numerically during the parameter estimation until the optimal parameter values were reached. The model gave a very good description of the experimental data.”

Highlights:

• “In liquid–liquid systems, the mass transfer between the phases is of great importance. The SpinChem rotating bed reactor (RBR) can be implemented to minimize external mass transfer limitations by forced centrifugal flow through the hollow stirrer, where the catalyst is immobilized.”
• “Further benefits of the RBR technology are the protection of the catalyst from shear forces and grinding as well as simple separation and recycling of the catalyst from the reaction medium.”
• “Process intensification is a concept where novel technologies are applied to develop cleaner, safer, more compact, and more economical chemical processes. […] In the case of epoxidation, rotating bed reactors, microwave irradiation, and ultrasound irradiation are methods of process intensification with promising results.”