Production of high-end bio-lubricant products via epoxidation of canola oil trimethylolpropane (COTMP) esters

This study addresses the pressing need for sustainable bio-lubricants derived from renewable resources by exploring the epoxidation of trimethylolpropane esters of free fatty acids sourced from canola oil. A heterogeneous catalyst was synthesized through the direct functionalization of ethanolamine with montmorillonite K10 clay, followed by immobilization with a molybdenum compound. The catalyst was characterized using various techniques, including X-ray diffractometry (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). Epoxidation reactions were conducted using tert-butyl hydroperoxide (TBHP) as the oxidizing agent. Optimal reaction conditions were determined as 85 °C, 50 h, and a molar ratio of canola oil trimethylolpropane ester to TBHP of 1:1.5, yielding a conversion rate of 95.2 % with a selectivity of 98.62 %. The resulting epoxidized canola oil trimethylolpropane (ECOTMP) ester was characterized using FTIR and nuclear magnetic resonance (NMR) spectroscopies. Through titration methods, epoxy value, iodine value, oxygen oxirane content, conversion, and selectivity were determined, with the process achieving 95.7 % conversion of oxirane (RCO), resulting in a final product with 4.12 % oxygen oxirane content (OOC) and 3.4 mg I₂/g iodine value (IV). These findings demonstrate the potential of ECOTMP ester as an intermediate compound for further chemical modification, showcasing its promise as a biobased complex ester suitable for high-end bio-lubricant products with desirable properties such as recyclability and low wear scar diameter. © 2024 Elsevier B.V.