ABSTRACT
Vegetable oils are sustainable and renewable resources that can be treated chemically or enzymatically to produce bio-based materials that can often act as replacement for materials derived from petroleum [1]. Epoxidation of vegetable oils is a commercially important reaction, because the epoxides obtained from these renewable raw materials have wide applications in different areas such as for making plasticizers and polymer stabilizers [2]. Epoxidation of soybean oil for the synthesis of plasticizers and polymer stabilizers has already been successfully implemented at plant scale [3-5]. Epoxide serves as a plasticizer and as a scavenger for hydrochloric acid liberated from PVC when the PVC undergoes heat treatment. Okieimen et al. [6] have studied the epoxidation of rubber seed oil by peroxyacetic acid (PAA) generated in situ. Industrially, various peroxyacids such as peroxyformic acid, peroxyacetic acid, and peroxybenzoicacid are used for the epoxidation reaction. Out of the above mentioned peroxyacids, peroxyacetic acid is widely used due to its easy availability, lower price, high epoxidation efficiency, and reasonable stability at ordinary temperatures. Dindaet al. [7] have studied the kinetics of epoxidation of cottonseed oil by peroxyacetic acid generated in situ from hydrogen peroxide. The epoxidation of vegetable oil can be carried out with in situ formed or preformed peroxyacid in presence of an acidic catalyst. The in situ process is widely used because the preformed concentrated organic peroxyacid is unstable. The acidic catalyst may be a homogeneous or heterogeneous one. The main drawback of a homogeneous catalyst is that, it helps the oxirane cleavage reaction. The use of heterogeneous acidic catalyst for the epoxidation of vegetable oils was found to minimize the side reactions and to improve selectivity. Goudet al. [8] have studied the epoxidation reaction of karanja (pongamiaglabra) oil catalyzed by acidic ion exchange resin. The epoxidation kinetics of anchovy oil with partially preformed PAA in the presence of a resin catalyst has been reported by Wisniak and Navarrete [9]. Petrovicet al. [10] and Jankovićand Sinadinovic-Fišer [11] have studied the reaction kinetics of epoxidation of soybean oil and the extent of side reactions with in situ formed PAA and peroxyformic acid and in the presence of an ion exchange resin as catalyst.
