Recent advances in the field of selective epoxidation of vegetable oils and their derivatives: a review and perspective

Abstract

The present critical review reports the recent progress of the last 15 years in the selective epoxidation of vegetable oils and their derivatives, in particular unsaturated fatty acids (UFAs) and fatty acid methyl esters (FAMEs). Epoxidized vegetable oils (EVOs) have drawn much attention in recent years in the chemical industry since they are environmentally friendly, biodegradable, renewable, highly available and non-toxic. Four major types of catalysts are used to produce epoxidized fatty acid compounds: homogeneous, heterogeneous, polyoxometalates and lipases. EVOs are currently produced in industry by a homogeneous catalytic conventional epoxidation process, in which the unsaturated oils are converted with percarboxylic acids, such as peracetic or performic acid. However, this method suffers from several drawbacks such as (1) relatively low selectivity for epoxides due to oxirane ring opening, (2) corrosion problems caused by the strong acids in an oxidizing environment, etc. Thus, in view of the principles of green chemistry, the development of new catalytic systems for the selective epoxidation of vegetable oils and their derivatives is an actual task. Furthermore, in our opinion, epoxidized fatty acids and epoxidized fatty acid methyl esters can be a promising substitute for EVOs because the starting materials for their production have a lower viscosity and higher reactivity, which will significantly increase the productivity of the epoxidation process. In this work, we tried to determine the prospects of using the main catalytic methods in industry to obtain epoxidized fatty acid compounds.