Method for separating saturated and unsaturated fatty acid esters and use of separated fatty acid esters

Abstract

The present invention provides a composition comprising methyl esters derived from vegetable oils having less than about 3% by weight of saturated fatty acid methyl esters and a cloud point of less than about −30° C. A method for making the lowered cloud point composition is also disclosed in which vegetable derived methyl esters, urea and alcohol are mixed under sufficient heat to form a homogenous mixture. The mixture is then cooled to a temperature where a solid phase and a liquid phase are formed. The solid phase is enriched in saturated fatty acid methyl esters and the liquid phase is enriched in unsaturated fatty acid methyl esters. The solid phase is separated from the liquid phase. Finally, unused urea and methanol are removed from the liquid phase to form a liquid composition having a cloud point of less than about −30° C. and less than about 3% by weight saturated fatty acid methyl esters.

1 . A composition, comprising:
 methyl esters derived from vegetable oils, the methyl esters comprising less than about 3% by weight of saturated fatty acid methyl esters; and   the composition having a cloud point of less than about −30° C.   
   
   
       2 . The composition of  claim 1 , wherein the methyl esters consist essentially of methyl oleate, methyl linoleate and methyl linolenate. 
   
   
       3 . The composition of  claim 2 , wherein the methyl linolenate comprises less than about 10% by weight of the methyl esters. 
   
   
       4 . The composition of  claim 3 , wherein the methyl stearate comprises less than about 0.1% by weight of the methyl esters. 
   
   
       5 . The composition of  claim 3 , wherein the methyl linoleate comprises at least about 50% by weight of the methyl esters. 
   
   
       6 . The composition of  claim 4 , wherein the methyl linoleate comprises at least about 60% by weight of the methyl esters. 
   
   
       7 . The composition of  claim 1 , wherein the cloud point is less than about −35° C. 
   
   
       8 . The composition of  claim 1 , wherein the cloud point is less than about −40° C. 
   
   
       9 . The composition of  claim 1 , wherein the cloud point is less than about −45° C. 
   
   
       10 . The composition of  claim 1 , wherein the cloud point is less than about −50° C. 
   
   
       11 . The composition of  claim 1 , wherein the cloud point is less than about −55° C. 
   
   
       12 . The composition of  claim 1 , wherein the methyl esters comprise less than about 2% saturated methyl esters. 
   
   
       13 . The composition of  claim 1 , wherein the methyl esters comprise less than about 1.5% saturated methyl esters. 
   
   
       14 . The composition of  claim 1 , wherein the methyl esters comprise less than about 0.5% saturated methyl esters. 
   
   
       15 . The composition of  claim 1 , wherein the vegetable oils from which the methyl esters are derived comprise soy oil. 
   
   
       16 . The composition of  claim 1 , further comprising a petroleum based component. 
   
   
       17 . The composition of  claim 16 , wherein the petroleum based component comprises fossil fuel derived diesel fuel. 
   
   
       18 . The composition of  claim 1 , comprising less than about 1% methyl stearate. 
   
   
       19 . The composition of  claim 1 , comprising less than about 0.5% methyl stearate. 
   
   
       20 . The composition of  claim 1 , comprising less than about 0.1% methyl stearate. 
   
   
       21 . The composition of  claim 1 , further comprising animal fat derived methyl esters. 
   
   
       22 . A method of lowering the cloud point of methyl esters derived from vegetable oil, comprising:
 mixing vegetable derived methyl esters, urea and alcohol with sufficient heat to form a homogenous mixture;   cooling the homogeneous mixture to a temperature where a solid phase and a liquid phase are formed, the solid phase being enriched in saturated fatty acid methyl esters and the liquid phase being enriched in unsaturated fatty acid methyl esters;   separating the solid phase from the liquid phase; and   removing alcohol and unused urea from the liquid phase to form a liquid composition having a cloud point of less than about −30° C. and less than about 3% by weight saturated fatty acid methyl esters.   
   
   
       23 . The method of  claim 22 , wherein the alcohol comprises methanol. 
   
   
       24 . The method of  claim 23 , further comprising, before the step of forming the homogeneous mixture, mixing vegetable derived oil, sodium hydroxide and methanol to form the vegetable derived methyl esters. 
   
   
       25 . The method of  claim 24 , wherein the homogeneous mixture contains methanol in an amount of about 3 to 10 times by weight of the amount of the fatty acid methyl ester. 
   
   
       26 . The method of  claim 25 , wherein excess methanol is provided in the step of mixing the vegetable derived oil, sodium hydroxide and methanol to form the vegetable derived methyl esters, whereby adding methanol during the step of forming the homogeneous mixture is unnecessary. 
   
   
       27 . The method of  claim 23 , further comprising separating glycerin from the vegetable derived methyl esters before the step of forming the homogeneous mixture. 
   
   
       28 . The method of  claim 22 , wherein the ratio of urea to methyl esters in the homogeneous mixture is from about 0.9:1 to about 1:1. 
   
   
       29 . The method of  claim 22 , wherein the solid phase is separated from the liquid phase by filtration, centrifugation, sedimentation, or decantation of the liquid phase. 
   
   
       30 . The method of  claim 22 , wherein the liquid composition comprises less than about 2 percent by weight of saturated fatty acid methyl esters. 
   
   
       31 . The method of  claim 22 , wherein the liquid composition comprises less than about 1.5 percent by weight of saturated fatty acid methyl esters. 
   
   
       32 . The method of  claim 22 , wherein the removal of the alcohol is by evaporation. 
   
   
       33 . The method of  claim 22 , wherein the removal of the alcohol is by applying vacuum. 
   
   
       34 . The method of  claim 22 , wherein the removal of unused urea is by washing with acidified water, wherein the washed unused urea is separated by a liquid-liquid centrifugal extractor or by a gravity separation. 
   
   
       35 . The method of  claim 22 , wherein the yield of the liquid composition is at least 43% by weight of the vegetable-derived methyl esters used to form the homogeneous mixture. 
   
   
       36 . The method claim of  35 , wherein cloud point of the liquid composition is less than −34° C. 
   
   
       37 . The method claim of  35 , wherein cloud point of the liquid composition is less than −40° C. 
   
   
       38 . The method claim of  35 , wherein cloud point of the liquid composition is less than −50° C.