Synthesis of di-trimethylolpropane tetraester-based biolubricant from Elaeis guineensis kernel oil via homogeneous acid-catalyzed transesterification

Abstract Bio-based lubricant is crucial to be developed considering the toxicity risk, climate change, energy security, and green-environmental approach. This work presents a conversion of crude palm kernel seed oil to produce biolubricant product, CPKO-di-TMPTE via homogeneous acid-catalyzed transesterification reaction between crude palm kernel oil (CPKO) and di-trimethylolpropane (di-TMP). The optimization reaction process was performed using response surface methodology by D-optimal design based on four reaction parameters; the ratio of reactants, reaction time, reaction temperature, and catalyst loading. The optimum yield was about 79 % with 91 % selectivity of tetraester. The chemical structure of the biolubricant was characterized using infrared (FTIR), proton (1H-) and carbon (13C-) nuclear magnetic resonance NMR spectroscopy analysis techniques. Biolubricant product recorded its kinematic viscosity (40 oC and 100 oC) of 111.6 cSt and 18.1 cSt, a viscosity index of 140.1, pour point of - 6 oC, flashpoint > 365 oC, and oxidative stability of 200 °C. The product is classified as ISO VG 100 lubricant grade suitable for a food-grade hydraulic fluid.