Synthesis of palm oil based trimethylolpropane esters with improved pour points

Palm oil based trimethylolpropane (TMP) esters are potential biodegradable base stocks for environmentally friendly lubricants. To improve the low-temperature properties of palm oil based TMP esters, which are well below the requirements set by the lubricants' manufacturers, the high oleic content palm oil based TMP ester with a pour point between -10 and -32 degrees C was synthesized. The synthesis of palm oil polyol esters was performed by transesterification of fractionated palm oil methyl esters with TMP using sodium methoxide as a catalyst. Nearly complete conversion to palm TMP triesters (98% w/w) was obtained. The palm oil methyl esters were fractionated at 150-180 degrees C and 0.1 mbar prior to the synthesis to reduce the saturated fatty acid content. The fractionation and reaction took place using the same experimental setup. The effects of composition on pour points, viscosity, and viscosity index of the high oleic content palm oil based TMP esters were also evaluated. The concentration of C-16:0 methyl ester in the starting material should be below 10% w/w to ensure that the pour points of high oleic content palm oil based TMP esters are below -30 degrees C. In addition, the reaction conversion to triester must also be maintained above 90% w/w to produce TMP esters with excellent pour points. Operating temperature had a negligible effect on the reaction yield so long as the temperature was kept above 120 degrees C. There were small variations in the viscosities and viscosity index values of high oleic content palm oil based TMP, in the region of 50 cSt and 199, respectively.