In-Depth Kinetic Modeling and Chemical Analysis for the Epoxidation of Vegetable Oils in a Liquid–Liquid–Solid System

Abstract

A heterogeneous catalyst for producing epoxidized vegetable oils, an important intermediate in the production of non-isocyanate polyurethanes, is essential for product separation and for decreasing the side-reaction, i.e., ring-opening reaction, via the Prileschajew method. The development of reliable kinetic models considering key variables for both phases and the mass transfer phenomena is missing in the literature. The reaction pathway for the ring-opening reaction is also under debate. Therefore, we studied the kinetics of epoxidation of cottonseed oil by perpropionic acid over the solid acid catalyst amberlite IR-120. An in-depth kinetic model was developed by using Bayesian inference. The reaction pathway for the ring opening was investigated. Propionic acid, a weak acid, allows for a decrease in the oxirane ring-opening side reaction.

Epoxidation of Vegetable Oils via the Prilezhaev Reaction Method: A Review of the Transition from Batch to Continuous Processes

“…Conversely, the selectivity was strongly affected and decreased along the molar ratio increment. Similarly, Cai et al, 120,121 Dinda et al 52 and Mungroo et al 122 have found that an excessive hydrogen peroxide-to-double bond molar ratio leads to an increasing formation of byproducts, thus impairing the oxirane yield, independently from the acid catalyst. Conversely, the carboxylic acid is required in a lower quantity, as it acts as the oxygen carrier between the oil and aqueous phases, and after the epoxidation reaction, it is regenerated and migrated back in the aqueous phase where it can react with hydrogen peroxide again.…”

“…Herein the approach could be the same as for the cases in the presence of either a homogeneous catalyst or an autocatalytic mode, where a pseudo-homogeneous kinetic model can be considered. 119,121,145,146,154,182,198 The different approaches applied in the modeling of such a system are briefly discussed below.…”

“…It should be pointed out that when the epoxidation via the Prilezhaev method is carried out in the presence of a heterogeneous catalyst, i.e., ionic-exchange resins, the description of the system is no longer possible through the two-phase modeling, because a third phase, the solid catalyst phase, is present in the reaction system and modeling becomes more demanding. Herein the approach could be the same as for the cases in the presence of either a homogeneous catalyst or an autocatalytic mode, where a pseudo-homogeneous kinetic model can be considered. ,,,,,, The different approaches applied in the modeling of such a system are briefly discussed below.…”

“…For performic acid, due to its higher solubility, its partition coefficient was considered 3 times higher compared to that of formic acid. This approximation is generally adopted by different authors ,,, with different carboxylic-percarboxylic systems, because of the higher preference of the percarboxylic acid for the organic phase compared to the corresponding carboxylic acid.…”

Reactivity and structure: epoxidation of cottonseed oil and the corresponding fatty acid methyl ester

“…After the epoxidation, GPC chromatograms of ECSO and ECSO-FAME show a shift of the main peak to a higher molecular weight region, implying that the ring-opening/elimination side-products are in a low extent. A secondary peak that can also be observed in both ECSO and ECSO-FAME are ascribed to oligomers resulting from ring-opening/cationic polymerization reactions [35]. The oligomer production from ECSO and ECSO-FAME is similar, but the three-armed star structure of ECSO could allow a higher availability of access to the unsaturated groups.…”