Esterification and Evaluation of Palm Oil as Biolubricant Base Stock

Refined, bleached,and deodorized palm oil become one of the potential renewable resources inbiolubricantapplication. However, palm oil cannot be used directly as biolubricant because ofits low oxidative stability. It is due to the presence of oxidation active site β-hydrogen inaglycerol backbone structure. This drawback can be overcome by molecule structural redesignthrough chemical modification process such as esterification with polyhydric alcohol. Thesynthesis of biolubricant was carried out via esterification of palm oil fatty acids withtrimethylolpropane in a mole ratio of 3.5:1, 1.34% sulphuric acid asthecatalyst at 154°C for5.97 h.Gaschromatography equipped with aflame ionization detectorwasused to determinethe percentage of ester composition in palm oil trimethylolpropane (POTMP) ester. Thestructure of POTMP ester was confirmed by Fouriertransformation infra-red(FTIR), protonand carbon Nuclearmagnetic resonance(1H-NMR and13C-NMR) spectroscopy.The resultshowed that POTMP ester hadsuccessfully synthesized with 92% yield, 100% composition oftriesters and POTMP existed in liquid form at room temperature. The existence oftheesterfunctional group evidenced by FTIR at 1740 cm-1,thechemical shift of1H NMR at 2.29-2.36ppm and13C NMR at 173.53-173.57 ppm. Physicochemical properties analysis showed thatPOTMP ester hadoxidative stability at 183°C, pour point at 8°C,theflash point at 290°Cand158 of viscosity indexwhichmadePOTMP plausible to be used in many industrial lubricationapplications.