High-Temperature Epoxidation of Soybean Oil in Flow—Speeding up Elemental Reactions Wanted and Unwanted

Abstract

The soybean oil epoxidation reaction is investigated theoretically through kinetic modeling of temperature effects enabled through flow processing under superheated conditions. Different from previous studies on such processing, here a complex reaction network superimposed by multiphase transport is considered; with one elemental step-the hydrogen peroxide decomposition-which can defeat the much boosted product formation. For such a delicate reaction network, the accessibility of accurate and reliable kinetics is absolutely essential, especially when exploring this completely new temperature range. Initially, an overview of the actual kinetic models is given, this gives rise to implications for the study developed here considering high temperature flow processing, heat removal efficiency, hotspot formation, and the effect of different hydrogen peroxide decomposition kinetics. Subsequently an optimized process involving the use of microreactors at different temperatures is proposed for the process management of the reaction heat and to yield a commercial grade product under notably intensified conditions. The results are then benchmarked with quantitative, challenging process improvement criteria set by an industrial partner.

Liquid phase oxidation chemistry in continuous-flow microreactors

“…251 Kinetic modelling of soybean oil epoxidation at elevated temperatures in a microreactor demonstrated that this would lead to much shorter reaction times. 252 Increasing the temperature also led to an increased decomposition of H2O2, which eventually became the dominant reaction. Santacesaria et al employed a glass tubular reactor (1 cm ID, 22 or 38 mL) packed with stainless steel spheres (2.2 mm Ø) to carry out the soybean oil epoxidation under biphasic reaction conditions.…”

Direct valorisation of waste cocoa butter triglycerides via catalytic epoxidation, ring‐opening and polymerisation

“…In contrast, the selectivity to epoxide decreases with increase in residence time and is always higher in batch reaction. This is attributed to the degradation of hydrogen peroxide in the flow reactor system, which results in higher water concentration and the increase in concentration of ortho‐phosphoric acid, which is a catalyst for diol formation . To confirm this we measured concentration of H 2 O 2 as a function of time in the feed vessel with/without stirring and at the exit of the flow reactor.…”

“…Epoxidation of soybean oils was investigated in a series of papers . Conventional batch epoxidation with hydrogen peroxide in the presence of acetic or formic acid and mineral acid was reported with a yield of up to 75% at temperatures between 60–80°C with a typical batch time of 5 h. A decrease in reaction time and slight improvement of the overall energy efficiency was possible if the reaction temperature was increased and the reaction was performed in a microreactor with efficient heat transfer.…”

“…Epoxidation of cyclooctene using a sacrificial aldehyde reactant in the Mukaiyama epoxidation was performed in a segmented continuous flow microreactor, reporting 100% selectivity to the epoxide at a short residence time of 2 min . However, there are only two examples of epoxidation of triglycerides under flow conditions, the epoxidation of soybean oil and of sunflower oil …”

Epoxidation of methyl oleate in a TiO2 coated-wall capillary microreactor

“…This might promote the consecutive-ring opening reactions and the decomposition of H 2 O 2 [36], and might lead to thermal runaway [37]. Therefore, H 2 O 2 was slowly fed into the batch reactor while it could be simultaneously fed into microcapillary reactor.…”