Synthesis of Biolubricant Trimethylolpropane Trioleate and Its Lubricant Base Oil Properties

Trimethylolpropane trioleate (TMPTO) could significantly reduce environmental pollution compared to mineral oils. In this study, oleic acid (OA) and trimethylolpropane (TMP) were used to synthesize TMPTO, and the synthesis process was optimized by single-factor experiments to obtain the highest yield. First, two kinds of operating conditions (vacuum distillation and atmospheric reflux) were compared, and then four kinds of catalysts were investigated to select the most efficient catalyst in esterification. Afterward, five reaction parameters were investigated, and the optimal conditions obtained were as follows: catalyst/TMP, 3.2:1 (molar ratio) 2% (w/w) OA/TMP; temperature, 180 degrees C; reaction time, 3 h; and vacuum degree, 0.095 MPa. Under the optimized conditions, the TMP conversion rate reached up to 92.8%. Furthermore, TMPTO was confirmed by Fourier transform infrared spectroscopy (FTIR). Finally, the typical properties of the product were evaluated, including the kinematic viscosity at 40 and 100 degrees C, viscosity index, solidifying point, and thermal oxidation stability of TMPTO.