Optimization of response surface methodology by D-optimal design for synthesis of food-grade palm kernel based biolubricant

Abstract This paper outlines the production of biolubricant base stock trimethylolpropane triester (TMPTE), which was derived from crude palm kernel fatty acids (CPKFAs). The effects of production variables including crude palm kernel fatty acids-to-trimethylolpropane molar ratio, reaction temperature, reaction time and the amount of H2SO4 catalyst on reaction performance were examined using Response Surface Methodology (RSM). The optimum operating conditions occurred with a crude palm kernel fatty acids-to-trimethylolpropane molar ratio of 3.05:1, a reaction time of 5.98 h, a reaction temperature of 150 °C, and a catalyst amount of 1.01 wt%. Under the optimal conditions, a high yield percentage of 86.13 ± 0.7% trimethylolpropane triester was obtained with 99.13 ± 0.4% of trimethylolpropane triester composition. TMPTE showed a high viscosity index, a low pour point, a high flash point of 154.8, −10 °C, and 320 °C, respectively, coupled with a good oxidative stability at 245 °C. The synthesized product was categorized as ISO VG 46. TMPTE is possible to be used as a hydraulic fluid in food processing machinery based on compatible lubrication properties with the same grade commercial lubricants.