Production of alkyl esters from high free fatty acid sources

Abstract

The invention provides a novel system for the conversion of fats, oils, and greases (FOG) from processed food sources, including but not limited to trap greases, FOG separated from prepared foods, waste streams from glycerin separation processes, “black grease” collected from the scum-layer of waste water treatment facilities, and other sources having high free fatty acid content, to their alkyl esters.

We claim: 
     
         1 . A method for converting high FFA source material into alkyl esters, comprising the step of:
 (a) reacting in a reactor vessel a mixture of the source material with an esterification reagent comprising an acid catalyst and an alcohol for a sufficient time to produce alkyl esters.   
     
     
         2 . The method of  claim 1 , further comprising the step of:
 (b) recovering the alkyl esters.   
     
     
         3 . The method of  claim 1 , wherein the source material is at least one member selected from the group consisting of fats, oils, and greases (FOG) from processed food sources, including but not limited to trap greases, FOG separated from prepared foods, “black grease” collected from the scum-layer of waste water treatment facilities, and waste streams from glycerin separation processes. 
     
     
         4 . The method of  claim 1 , wherein the acid catalyst is selected from the group consisting of sulfuric acid and phosphoric acid. 
     
     
         5 . The method of  claim 1 , wherein the alcohol is an alkyl alcohol. 
     
     
         6 . The method of  claim 5 , wherein the alcohol is methanol. 
     
     
         7 . The method of  claim 5 , wherein the alcohol is ethanol. 
     
     
         8 . The method of  claim 1 , wherein the alkyl esters are methyl esters. 
     
     
         9 . The method of  claim 1 , further comprising the step of washing and recovering at least one of the group consisting of salts of the acid catalyst, glycerin, and water. 
     
     
         10 . The method of  claim 1 , wherein step (a) is performed at at least the boiling point of the alcohol. 
     
     
         11 . The method of  claim 1 , wherein step (a) is performed at ambient temperature. 
     
     
         12 . The method of  claim 11 , wherein the temperature is between 5-65° C. 
     
     
         13 . The method of  claim 1 , wherein step (a) is performed at ambient pressure. 
     
     
         14 . The method of  claim 1 , wherein step (a) is performed at a pressure between 15-60 psi. 
     
     
         15 . The method of  claim 1 , wherein the FFA content of the source material is greater than 50%. 
     
     
         16 . The method of  claim 15 , wherein the FFA content of the source material is greater than about 75%. 
     
     
         17 . The method of  claim 15 , wherein the FFA content of the source material is greater than about 90%. 
     
     
         18 . The method of  claim 1 , wherein greater than 90% of the FFAs are esterified to alkyl esters. 
     
     
         19 . The method of  claim 1 , wherein greater than 95% of the FFAs are esterified to alkyl esters. 
     
     
         20 . The method of  claim 1 , wherein greater than 97% of the FFAs are esterified to alkyl esters. 
     
     
         21 . The method of  claim 1 , wherein greater than 99% of the FFAs are esterified to alkyl esters. 
     
     
         22 . The method of  claim 1 , wherein a preliminary feedstock having lower FFA content is first converted to the high FFA source material.