Application of Heteropolyacid-Based Heterogeneous Catalysts for Conversion of Oleochemicals into Renewable Fuels and other Value-Added Products

Abstract

Oleochemicals offer viable choices to replace petrochemicals in a wide range of applications such as fuels, lubricants and surfactants. Many of the conversions require the use of suitable solid acids as the catalysts. The chemical and physical properties of the feedstock in oleochemical processes often result in difficulties and challenges that limit the success. Large amount of free fatty acids and high water content create barriers towards the successful use of broad range of oleochemicals as raw materials. To overcome this problem, efforts have been dedicated to the development of new technologies involving new types of catalyst. Solid acid catalysts based on heteropolyacids (HPAs) for various oleochemical conversions especially esterification reaction of fatty acids and transesterification of vegetable oils have been successfully developed. This type of catalyst already secured a tangible success in solving some problems associated with the earlier types of catalyst leading to higher productivity in the process while satisfying the needs of sustainable and environmental friendly industrial processes. Incorporation of HPAs active component into mesoporous supports can produce heterogeneous catalysts with high acid sites dispersion, stability to high temperature, recyclable and they usually demonstrate low leaching of active components in the reaction medium. This article reviews common oleochemical processes where various HPA catalysts already found successful application with some insight into the specific characteristics of the catalysts. Their advantages and drawbacks as well as specific process behaviors in few important oleochemical conversions of industrial importance will be discussed.