Process For The Preparation of Fatty Acid Alkyl Esters

Abstract

The present invention broadly relates to a process for preparing fatty acid alkyl esters from fat-containing feedstocks using sulfonated fatty acid catalysts.

1 . A process for preparing fatty acid alkyl esters comprising:
 i) forming a mixture comprising a fat-containing feedstock, an alcohol and a sulfonated fatty acid derivative of the formula (I) or a salt thereof:   
       
         
           
           
               
               
           
         
         wherein: 
         n is an integer between 0 and 7, 
         m is an integer between 0 and 17, 
         R is hydrogen or methyl, 
         R 1  is hydrogen or C 1 -C 6  alkyl, 
         ii) allowing the mixture in step i) to react so as to produce a mixture comprising fatty acid alkyl esters; 
         iii) isolating the fatty acid alkyl esters obtained in step ii). 
       
     
     
         2 . The process of  claim 1 , wherein the fat-containing feedstock comprises at least 20%, at least 40%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%, by weight of free fatty acids. 
     
     
         3 . The process of  claim 1  or  claim 2 , wherein the fat-containing feedstock is a triglyceride-containing feedstock. 
     
     
         4 . The process of any one of  claims 1  to  3 , wherein the alcohol is present in the mixture in an amount between about 10% and about 60% by weight. 
     
     
         5 . The process of  claim 4 , wherein the alcohol is present in the mixture in an amount between about 15% and about 40% by weight. 
     
     
         6 . The process of any one of  claims 1  to  5 , wherein the sulfonated fatty acid derivative is present in the mixture in an amount between about 0.05% and about 5% by weight. 
     
     
         7 . The process of  claim 6 , wherein the sulfonated fatty acid derivative is present in the mixture in an amount between about 0.5% and about 2.5% by weight. 
     
     
         8 . The process of any one of  claims 1  to  7 , wherein the mixture further comprises an acid. 
     
     
         9 . The process of  claim 8 , wherein the acid is present in the mixture in an amount between about 0.5% and about 5% by weight. 
     
     
         10 . The process of  claim 8  or  claim 9 , wherein the acid is sulfuric acid. 
     
     
         11 . The process of any one of  claims 1  to  10 , wherein the mixture further comprises water. 
     
     
         12 . The process of  claim 11 , wherein the water is present in the mixture in an amount of up to about 10%, or in an amount of up to about 5%, or in an amount of up to about 2%, or in an amount of up to about 1%, by weight. 
     
     
         13 . The process of any one of  claims 1  to  12 , wherein the alcohol is a C 1 -C 12  alcohol, or a mixture thereof. 
     
     
         14 . The process of  claim 13 , wherein the alcohol is methanol, ethanol, propanol, isopropanol, fusel alcohol, or a mixture thereof. 
     
     
         15 . The process of any one of  claims 1  to  14 , wherein step ii) comprises heating the mixture. 
     
     
         16 . The process of any one of  claims 1  to  15 , wherein in the sulfonated fatty acid derivative, m is an integer between 6 and 17, or an integer between 8 and 17, or an integer between 10 and 17, or an integer between 11 and 15. 
     
     
         17 . The process of any one of  claims 1  to  16 , wherein in the sulfonated fatty acid derivative n is an integer between 0 and 6, 0 and 4, or 0 and 3. 
     
     
         18 . The process of  claim 17 , wherein n is 0. 
     
     
         19 . The process of any one of  claims 1  to  18 , wherein in the sulfonated fatty acid derivative R 1  is methyl. 
     
     
         20 . The process of any one of  claims 1  to  19 , wherein in the sulfonated fatty acid derivative R is methyl. 
     
     
         21 . The process of any one of  claims 1  to  15 , wherein in the sulfonated fatty acid derivative m is an integer between 8 and 17, n is 0, 1 or 2 and R and R 1  are methyl. 
     
     
         22 . The process of any one of  claims 1  to  15 , wherein m is an integer between 8 and 15, n is 0 and R and R 1  are methyl. 
     
     
         23 . The process of any one of  claims 1  to  15 , wherein m is an integer between 11 and 15, n is 0 and R and R 1  are methyl. 
     
     
         24 . The process of any one of  claims 1  to  23 , wherein the mixture comprises a plurality of sulfonated fatty acid derivatives. 
     
     
         25 . The process of  claim 24 , wherein the plurality of sulfonated fatty acid derivatives are C 14 -C 18  α-sulfonated fatty acid methyl esters, or salts thereof. 
     
     
         26 . The process of  claim 24 , wherein the plurality of sulfonated fatty acid derivatives are C 16 -C 18  α-sulfonated fatty acid methyl esters, or salts thereof. 
     
     
         27 . The process of any one of  claims 1  to  26 , further comprising bleaching and/or degumming the fat-containing feedstock prior to use in step i). 
     
     
         28 . The process of any one of  claims 1  to  27 , wherein fatty acid alkyl esters isolated in step iii) have a purity of at least about 70%, at least about 80%, or at least about 85%, or at least about 90%, or at least about 95%. 
     
     
         29 . The process of any one of  claims 1  to  28 , further comprising:
 iv) forming a mixture comprising the fatty acid alkyl esters obtained following step iii), unreacted triglycerides or unreacted free fatty acids, an alcohol and a sulfonated fatty acid derivative of the formula (I) as defined above; 
 v) allowing the mixture in step iv) to react such that at least some of the triglycerides or at least some of the free fatty acids are converted into fatty acid alkyl esters; 
 vi) isolating the fatty acid alkyl esters from the mixture following step v). 
 
     
     
         30 . The process of  claim 29 , wherein the mixture in step iv) further comprises an acid. 
     
     
         31 . The process of  claim 30 , wherein the acid is sulfuric acid. 
     
     
         32 . The process of any one of  claims 29  to  31 , wherein the alcohol is an anhydrous alcohol. 
     
     
         33 . The process of any one of  claims 29  to  32 , wherein fatty acid alkyl esters isolated in step vi) have a purity of at least about 70%, at least about 80%, or at least about 85%, or at least about 90%, or at least about 95%. 
     
     
         34 . The process of any one of  claims 1  to  33 , further comprising:
 vii) treating the fatty acid alkyl esters obtained following step iii) or vi) with a base so as to neutralise residual acid. 
 
     
     
         35 . The process of any one of  claims 1  to  34 , further comprising:
 viii) base-catalysed transesterification following steps iii), vi) or vii) so as to convert at least some unreacted triglycerides present with the fatty acid alkyl esters into fatty acid alkyl esters. ix) isolating the fatty acid alkyl esters following step viii). 
 
     
     
         36 . The process of any one of  claims 1  to  28 , wherein fatty acid alkyl esters isolated in step iii) are not subjected to further purification. 
     
     
         37 . Fatty acid alkyl esters whenever prepared by the process of any one of  claims 1  to  36 . 
     
     
         38 . Use of fatty acid alkyl esters according to  claim 37  as biodiesel.