Process for separating saturated and unsaturated fatty acids

Abstract

A process for separating a blend of saturated and unsaturated fatty acids or saturated and unsaturated fatty acid alky esters into a first fraction enriched with the saturated fatty acids or saturated fatty acid alkyl esters and a second fraction enriched with unsaturated fatty acids or unsaturated fatty acid alkyl esters. When separating fatty acids, the process includes the steps of (a) saponifying a blend of long chain saturated and unsaturated fatty acids to form free fatty acids, (b) complexing the free fatty acids with urea, and (c) separating the urea complexed free fatty acids into a first fraction enriched with saturated free fatty acids and a second fraction enriched with unsaturated free fatty acids. When separating fatty acid alkyl esters, the process includes the steps of (i) complexing the fatty acid alkyl esters with urea, and (ii) separating the urea-complexed fatty acid alkly esters into a first fraction enriched with saturated fatty acid alkyl esters and a second fraction enriched with unsaturated fatty acid alkyl esters.

1 . A process, comprising the steps:
 (a) saponifying a blend of long chain saturated and unsaturated fatty acids to form free fatty acids;   (b) complexing the free fatty acids with urea,   (c) removing the saturated free fatty acids from the urea-complexed blend of free fatty acids, leaving a fraction containing the unsaturated free fatty acids; and   (d) transesterifying the fraction containing the unsaturated free fatty acids to form long chain unsaturated fatty acid alkyl esters.   
     
     
         2 . The process of  claim 1 , wherein the blend of long chain saturated and unsaturated fatty acids is an oil selected from plant oils, animal oils, fish oils, marine mammal oils, waste cooking oils, and microbial oils. 
     
     
         3 . The process of  claim 2 , wherein the blend of long chain saturated and unsaturated fatty acids is a plant oil selected from black currant seed oil, borage oil, camelina oil, canola oil, castor oil, chia oil, corn oil, cotton seed oil, cuphea oil, flax oil, hemp oil, jojoba oil, mustard oil, olive oil, palm oil, peanut oil, primrose oil, rapeseed oil, safflower oil, sesame oil, soy oil, sunflower oil and tree nut oils. 
     
     
         4 . The process of  claim 2 , wherein the blend of long chain saturated and unsaturated fatty acids oil is saponified by admixing the oil with a C 1-3  alcohol or a combination of a C 1-3  alcohol and water at an elevated temperature of 60 to 65° C. in the presence of an alkali catalyst to form a first admixture. 
     
     
         5 . The process of  claim 4 , wherein the C 1-3  alcohol is ethanol and a majority of the ethanol is recycled ethanol recovered from the process. 
     
     
         6 . The process of  claim 5 , further comprising the steps of (i) adjusting the pH of the first admixture below 6 by the addition of an acid after saponification of the oil, and (ii) recovering a free fatty acid enriched fraction and a glycerine enriched fraction from the pH adjusted first admixture wherein the recovered free fatty acid enriched fraction is the source of free fatty acids complexed with urea in step (b). 
     
     
         7 . The process of  claim 3 , wherein the blend of long chain saturated and unsaturated fatty acids oil is saponified by admixing the oil with a C 1-3  alcohol or a combination of a C 1-3  alcohol and water at an elevated temperature of 60 to 65° C. in the presence of an alkali catalyst to form a first admixture. 
     
     
         8 . The process of  claim 7 , wherein the C 1-3  alcohol is ethanol and a majority of the ethanol is recycled ethanol recovered from the process. 
     
     
         9 . The process of  claim 8 , further comprising the steps of (i) adjusting the pH of the first admixture below 6 by the addition of an acid after saponification of the oil, and (ii) recovering a free fatty acid enriched fraction and a glycerine enriched fraction from the pH adjusted first admixture wherein the recovered free fatty acid enriched fraction is the source of free fatty acids complexed with urea in step (b).