Thermochemical Conversion of Plant Oils and Derivatives to Lubricants

Abstract

Abstract In the last few years, rising environmental concerns because of the increase in accidental spillage of lubricants have encouraged further development in plant oil–based lubricants. In some areas, tighter legislative controls have been introduced for the use of petroleum-based products. Biolubricants derived from plant oils offer promising solutions to these environmental issues. These bio-based products have been studied extensively and the differences in performances are mainly because of the different fatty acid composition of plant oils. Like most bio-based products, shortcomings of plant oils are attributable to their natural characteristics. Notably, the oils lack thermal and oxidative stabilities, thus requiring modification via thermochemical conversions to improve their properties. Five thermochemical methods have been explored in lubricant synthesis, namely esterification, transesterification, epoxidation, selective hydrogenation, and estolides formation. However, these thermochemical processes are complicated and usually require multiple lengthy steps such as epoxidation, followed by ring opening and finally acetylation or esterification of hydroxyl groups, and thus are economically not viable. Finally, the properties of the products obtained from these synthesis methods were characterized and compared. This chapter provides an overview of the development in the thermochemical conversion methods of plant oils to biolubricants, enabling an accurate evaluation of cost-effective technology, which is crucial for the future of the plant oil–based lubricants.