Biolubricant production via esterification and transesterification processes: Current updates and perspectives

Abstract

The growing concern and limitations for existing lubricants have driven the need for biolubricants, extensively proposed as the most suitable and sustainable lubricating oils. Biolubricants are generally synthesized from various bio-based sources, including vegetable oils, microbially derived oils, waste cooking oil, etc. They are promising commodities and advantageous to mineral-based analogues due to their exceptional properties like their lubricity, biodegradability, reduced toxicity, and reduced volatility. Yet, their utilization as lubricants is constrained due to their relatively poor cold-flow and thermo-oxidative stability uncertainties even after being chemically modified. Hence, many chemical modification pathways have been reported to overcome this limitation, with the most exploited approaches being esterification and transesterification. This modification pathway enhanced the thermo-oxidative stability and the cold-flow properties of these bio-based oils, increased the yield, and enhanced the quality of the lubricants. With this in mind, this paper reviews up-to-date works conducted in this area and critically report the advancement in esterification and transesterification production of biolubricants. The study further reviews the latest published literature, current updates, and future perspectives related to the synthesis of biolubricants. Also, the review highlights the significant factors that govern the entire reaction process, selection criteria of renewable feedstocks, and the tribological performance of biolubricants.