Production of Biodiesel and Glycerin from High Free Fatty Acid Feedstocks

Abstract

A system and method for the conversion of free fatty acids to glycerides and the subsequent conversion of glycerides to glycerin and biodiesel includes the transesterification of a glyceride stream with an alcohol. The fatty acid alkyl esters are separated from the glycerin to produce a first liquid phase containing a fatty acid alkyl ester rich (concentrated) stream and a second liquid phase containing a glycerin rich (concentrated) stream. The fatty acid alkyl ester rich stream is then subjected to distillation, preferably reactive distillation, wherein the stream undergoes both physical separation and chemical reaction. The fatty acid alkyl ester rich stream is then purified to produce a purified biodiesel product and a glyceride rich residue stream. Neutralization of the alkaline stream, formed during the alkali-catalyzed transesterfication process, may proceed by the addition of a mineral or an organic acid.

What is claimed is as follows: 
     
         1 . A process for the production of purified biodiesel from a feedstock comprising:
 a. reacting glycerides with at least one alcohol to produce a fatty acid alkyl ester stream;   b. purifying the fatty acid alkyl ester stream by distillation, wherein the distillation involves separating the fatty acid alkyl ester stream into a purified fatty acid alkyl ester stream and at least a second stream; and   c. recovering fatty acid alkyl esters from the purified fatty acid alkyl ester stream.   
     
     
         2 . The process of  claim 1 , wherein said feedstock comprises at least one of impurities, unsaponifiable materials, monoglycerides, diglycerides, triglycerides, and free fatty acids. 
     
     
         3 . The process of  claim 1 , wherein said feedstock comprises free fatty acids between 0-100 wt %. 
     
     
         4 . The process of  claim 1 , wherein said fatty acid alkyl ester stream contains at least one of impurities, unsaponifiable materials, glycerin, monoglycerides, diglycerides, triglycerides, free fatty acids, and fatty acid alkyl esters. 
     
     
         5 . The process of  claim 1 , wherein said second stream is a bottoms fraction which comprises at least one of impurities, unsaponifiable materials, glycerin, monoglycerides, diglycerides, triglycerides, free fatty acids, and fatty acid alkyl esters. 
     
     
         6 . The process of  claim 1  wherein the second stream is an overhead fraction comprising primarily alcohol. 
     
     
         7 . A product produced by the process of  claim 1 . 
     
     
         8 . The process of  claim 1 , wherein said purified fatty acid alkyl ester stream has reduced levels of at least one of impurities, unsaponifiable materials, glycerin, monoglycerides, diglycerides, triglycerides, and free fatty acids relative to said fatty acid alkyl ester stream. 
     
     
         9 . The process of  claim 1 , wherein said purifying step is accomplished by one of reduced pressure distillation and reactive distillation. 
     
     
         10 . The process of  claim 1 , wherein said purifying step is accomplished using at least one of distillation vessels and distillation columns. 
     
     
         11 . The process of  claim 1 , wherein said purifying step is conducted between about 180° C.-280° C. 
     
     
         12 . The process of  claim 1  wherein said purifying step is conducted at a pressure of less than about 2 psia. 
     
     
         13 . A process for the production of purified biodiesel from a feedstock comprising:
 a. reacting glycerides with at least one alcohol to produce a first fatty acid alkyl ester stream;   b. separating the first fatty acid alkyl ester stream from high-boiling point impurities according to differences in vapor pressure to create at least a second fatty acid alkyl ester stream; and   c. recovering fatty acid alkyl esters from the second fatty acid alkyl ester stream.   
     
     
         14 . The process of  claim 13 , wherein said separation is accomplished by evaporation or distillation. 
     
     
         15 . The process of  claim 13  wherein said second fatty acid alkyl ester stream has reduced levels of at least one of impurities, unsaponifiable materials, glycerin, monoglycerides, diglycerides, triglycerides, and free fatty acids relative to said first fatty acid alkyl ester stream. 
     
     
         16 . The process of  claim 13 , wherein said separation step is accomplished by one of reduced pressure distillation and reactive distillation. 
     
     
         17 . The process of  claim 13 , wherein said separation step is accomplished using at least one of distillation vessels and distillation columns. 
     
     
         18 . A product produced by the process of  claim 13 . 
     
     
         19 . A process for the production of purified biodiesel from a feedstock comprising:
 a. reacting glycerides with at least one alcohol to produce a first fatty acid alkyl ester stream;   b. purifying the first fatty acid alkyl ester stream by distillation, wherein the distillation involves separating an overhead fraction from the first fatty acid alkyl ester stream to recover a second fatty acid alkyl ester stream;   c. purifying the second fatty acid alkyl ester stream by distillation, wherein the distillation involves separating said second fatty acid alkyl esters from a bottoms fraction; and   d. recovering purified fatty acid alkyl esters.   
     
     
         20 . The process of  claim 19 , wherein said overhead fraction comprises primarily alcohol. 
     
     
         21 . The process of  claim 19  wherein the purification in step (b) occurs at the same time as the purification in step (c). 
     
     
         22 . The process of  claim 19  wherein the purification in step (b) occurs in the same vessel as the purification in step (c). 
     
     
         23 . The process of  claim 19  wherein the purification in step (b) occurs before the purification in step (c). 
     
     
         24 . The process of  claim 19  wherein the purification in step (b) occurs after the purification in step (c). 
     
     
         25 . A product produced by the process of  claim 19 . 
     
     
         26 . A process for producing purified biodiesel comprising:
 a. conditioning of a fatty acid containing feedstock by heating, mixing and filtering to create a conditioned feedstock;   b. reacting said conditioned feedstock with alcohol to produce fatty acid alkyl esters and glycerin;   c. separating said fatty acid alkyl esters from said glycerin to yield a fatty acid alkyl ester rich stream and a glycerin rich stream;   d. purifying the fatty acid alkyl ester rich stream by distillation; and   e. recovering purified fatty acid alkyl esters.   
     
     
         27 . The process of  claim 26  wherein said purified fatty acid alkyl esters have reduced levels of at least one of impurities, unsaponifiable materials, glycerin, monoglycerides, diglycerides, triglycerides, and free fatty acids relative to said fatty acid alkyl ester rich stream prior to distillation. 
     
     
         28 . The process of  claim 26 , wherein said purification step is accomplished by one of reduced pressure distillation and reactive distillation. 
     
     
         29 . The process of  claim 26 , wherein said purification step is accomplished using at least one of distillation vessels and distillation columns. 
     
     
         30 . A product produced by the process of  claim 26 .