Green synthesis and property analysis of biolubricants based on structural variations

Authors: Sarker, Majher; Sharma, Brajendra - Bk; Ngo, Helen; Muir, Zerlina; Jones, Kerby

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2023
Publication Date: 7/20/2023
Citation: Sarker, M.I., Sharma, B.K., Lew, H.N., Muir, Z.E., Jones, K.C. 2023. Green synthesis and property analysis of biolubricants based on structural variations. ACS Sustainable Chemistry & Engineering. https://doi.org/10.1021/acssuschemeng.3c02996.
DOI: https://doi.org/10.1021/acssuschemeng.3c02996

Interpretive Summary: In this study, a green process has been developed to synthesize five triesters using a naturally derived renewable bioingredient, i.e., oleic acid. These triesters have been characterized for their potential use as bioproducts such as bio-lubricants. The synthesis process can use reusable catalyst and generate very little/no waste. This eco-friendly and cost-effective synthesis of bio-lubricants will help to replace the fossil-based products which raise concerns regarding biodegradability and toxicity being harmful to the environment. Lubricant property analysis of the synthesized triesters shows comparable/better characteristics to that of petroleum-based products which are readily available in the market. This study also provides valuable information for the corresponding industries regarding how the differences in molecular structure can influence the application properties of triesters.

Technical Abstract: Chemical structure of a biolubricant plays an important role to determine its physicochemical and tribological properties. In this study, five triesters, trimethylolpropane-triisostearate (T-IS), trimethylolpropane-triisooleate (T-IO), trimethylolpropane-trioleate (T-OA), glycerol-triisooleate (G-IO) and glycerol-trioleate (G-OA), have been synthesized via esterification of glycerol/trimethylolpropane with the respective free fatty acids (FFA). FFA such as methyl-branched isostearic and isooleic acids were used for these T-IS, T-IO and G-IO triester’s synthesis have been previously made via skeletal-isomerization of naturally derived oleic acid using a reusable zeolite catalyst. The chemical structures of the synthesized triesters have been determined with NMR, LC-MS, FTIR and GC-MS. Physicochemical and tribological properties of these triesters have been compared to each other and with that of high-oleic sunflower oil and polyalphaolefin, common lubricant base oils to demonstrate how the differences in molecular structure can influence their properties. Lubricant property analysis reveals that all five synthesized triesters have potentiality to be used as biolubricants.