Epoxidation of Tall Oil Catalyzed by an Ion Exchange Resin under Conventional Heating and Microwave Irradiation

Adriana Freites Aguilera,Tapio Salmi,Jani Rahkila,Maristiina Nurmi,Jarl Hemming,Sébastien Leveneur,Pasi Tolvanen,Gaetan Torres,Kari Eränen,Théophile Razat

doi:10.1021/acs.iecr.0c01288

Adriana Freites Aguilera, Tapio Salmi + Show 8 more

Open Access

https://doi.org/10.1021/acs.iecr.0c01288

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Abstract

Tall oil fatty acids (TOFA) are a byproduct from the Kraft pulping process, and they represent a renewable and inexpensive alternative with high potential as a renewable feedstock. Epoxidized TOFA have great potential as chemical intermediates. Epoxidation of oleic acid, TOFA, and distilled tall oil (DTO) was conducted in an isothermal batch reactor with in situ-formed peracetic acid using hydrogen peroxide as the reactant and acetic acid as the reaction carrier. Amberlite IR-120 was used as the solid heterogeneous catalyst. The catalyst loading effect, the reactant ratios, the reaction temperature (40–70 °C), and the influence of microwave irradiation on epoxidation and ring opening were studied. The application of microwave irradiation resulted in an improvement of the epoxidation rate in the absence of the catalyst. Lower product yields were obtained for the epoxidation of DTO than for TOFA because of the higher viscosity and high content of rosin acids which presumably promoted ring opening reactions. At higher temperatures, the selectivity to oxirane decayed due to ring opening. Titration analysis and NMR analysis confirmed that microwave irradiation induces the ring opening reactions for TOFA epoxidation, and it accelerates this process for DTO. The rapid nature of the microwave heating might have unchained a series of ring opening reactions between neighboring oxirane groups and with the nucleophilic agents in the reaction mixture.

Highlights

Epoxidation of fatty acids and vegetable oils has been widely studied in the past years, and it represents a green pathway for environmentally friendly replacements for oil and gas as the main building blocks in the chemical industry
The epoxidation process has been studied for many different kinds of oils and fatty acids, such as canola, soybean, sunflower, rapeseed, castor, and cottonseed oils.[1−5] not many registered studies on the epoxidation of tall oil fatty acids (TOFA) have been published.[6−9] Tall oil is a renewable byproduct originating from the black liquor of the Kraft pulping process, and it represents a renewable, inexpensive, and domestically sourced alternative with a high potential as a renewable feedstock
Epoxidation of tall oil was studied under several operating conditions, and it was proven that oleic acid is an effective model compound in the epoxidation of TOFA

Summary

■ INTRODUCTION

Epoxidation of fatty acids and vegetable oils has been widely studied in the past years, and it represents a green pathway for environmentally friendly replacements for oil and gas as the main building blocks in the chemical industry. The results show that despite the differences on the mixtures, the reaction kinetics are rather similar, which proves that oleic acid is a very suitable model molecule for TOFA mixtures In this case, the presence of several double bonds in one fatty acid chain does not seem to promote the ring opening of the epoxide. This could be attributed to the rapid nature of the microwave heating which might have unchained a series of ring opening reactions between neighboring oxirane groups and with the present nucleophilic agents in the mixture This tendency has not been observed for the studies previously mentioned with oleic acid because there is only one unsaturation per a fatty acid chain.

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

Findings

■ REFERENCES