Biolubricant Production of 2-Ethylhexyl Palmitate by Transesterification Over Unsupported Potassium Carbonate

Owing to the decrease of global oil price, development of downstream value-added products is important to biodiesel industry. In this study, we used palmitic acid methyl ester (PAME) as a starting material to produce 2-ethylhexyl palmitate (2-EHP), an environmentally friendly biolubricant product, which was derived from the transesterification of fatty acid methyl esters and long chain fatty alcohols. Conventional synthetic routes of 2-EHP have disadvantages, including high catalyst price, low conversion efficiency, and pollution issues. To solve these problems, in situ transesterification of PAME with 2-ethylhexanol (2-EH) was conducted over unsupported potassium carbonate as heterogeneous catalyst. The optimal reaction temperature, 2-EH to PAME molar ratio, and catalyst to PAME mass ratio were 180 °C, 3:1, and 3.0 wt%, respectively. The PAME conversion reached up to 100% within 1 hour under the optimal conditions. In addition, a kinetic model describing the experimental data over a temperature range of 160–180 °C was developed. The dependence of kinetic rate constant ( k ) on temperature was evaluated, and the activation energy ( E a ) for the transesterification of PAME with 2-EH was calculated to be 57.04 kJ mol −1 .