Method of increasing the oxidation stability of biodiesel

Abstract

The invention relates to a process for increasing the oxidation stability of biodiesel, in which at least one aging stabilizer of the structure I where: R=hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group A=R 5 (AI) or —NR 1 R 2 (AII) and B=R 6 (BI), where R 1 , R 2 , R 3 , R 4 , R 5 and R 6 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cyclo-alkyl, hydroxyl or aryl group, are the same or different, and the phenyl or naphthyl structural unit in structure I, BII and BIII has one, two or three substituents of the R 3 , R 4 and/or R 5 type, is added to the biodiesel to be stabilized in an amount of from 5 to 20 000 ppm (w/w), to the use of these aging stabilizers to increase the oxidation stability of biodiesel, and to the correspondingly oxidation-stabilized biodiesel.

1 . A process for increasing the oxidation stability of biodiesel, wherein at least one aging stabilizer of the structure 
     
       
         
         
             
             
         
       
       where: 
       R=hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group 
       A=R 5  (AI) or —NR 1 R 2  (AII) and 
     
     
       
         
         
             
             
         
       
       B=R 6  (BI), 
       where R 1 , R 2 , R 4 , R 5  and R 6 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, whereby 
     
     R 3 =alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AI, or R 3 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AII, R 1 , R 2 , R 3 , R 4 , R 5  and R 6  are the same or different, and the phenyl or naphthyl structural unit in structure I, BII and BIII has one, two or three substituents of the R 3 , R 4  and/or R 5  type,
 is added to the biodiesel to be stabilized in an amount of from 5 to 20 000 ppm (w/w). 
 
   
   
       2 . A process according to  claim 1 , wherein the substituent of the A type=AII and that of the B type=BI. 
   
   
       3 . A process according to  claim 1 , wherein the substituent of the A type=AI and that of the B type=BII or BIII. 
   
   
       4 . A process according to  claim 2 , wherein at least one aging stabilizer of the structure 
     
       
         
         
             
             
         
       
       where: 
       R, R 1 , R 2  and R 6 =hydrogen, alkyl, cycloalkyl and/or aryl group, whereby the substituents of the R, R 1 , R 2  and R 6  type are the same or different is used. 
     
   
   
       5 . A process according to  claim 4 , wherein at least one aging stabilizer of the structure 
     
       
         
         
             
             
         
       
       where: 
       R, R 1 , R 2  and R 6 =hydrogen, alkyl, cycloalkyl and/or aryl group, whereby the substituents of the R, R 1 , R 2  and R 6  type are the same or different is used. 
     
   
   
       6 . A process according to  claim 1 , wherein the aging stabilizer used is a mixture of different compounds of structures I to III. 
   
   
       7 . The use of compounds of the structure 
     
       
         
         
             
             
         
       
       where: 
       R=hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group 
       A=R 5  (AI) or —NR 1 R 2  (AII) and 
     
     
       
         
         
             
             
         
       
       B=R 6  (BI), 
       where R 1 , R 2 , R 4 , R 5  and R 6 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, whereby 
     
     R 3 =alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AI, or R 3 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AII, R 1 , R 2 , R 3 , R 4 , R 5  and R 6  are the same or different, and the phenyl or naphthyl structural unit in structure I, BII and BIII has one, two or three substituents of the R 3 , R 4  and/or R 5  type,
 as aging stabilizers for increasing the oxidation stability of biodiesel. 
 
   
   
       8 . An oxidation-stabilized biodiesel, wherein the biodiesel comprises from 5 to 20 000 ppm (w/w) of at least one aging stabilizer of the structure: 
     
       
         
         
             
             
         
       
       where: 
       R=hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group 
       A=R 5  (AI) or —NR 1 R 2  (AII) and 
     
     
       
         
         
             
             
         
       
       B=R 6  (BI), 
       where R 1 , R 2 , R 4 , R 5  and R 6 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, whereby 
     
     R 3 =alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AI, or R 3 =hydrogen, alkyl, alkenyl, alkynyl, alkoxy, alkylaryl, arylalkyl, cycloalkyl, hydroxyl or aryl group, if A=AII, R 1 , R 2 , R 3 , R 4 , R 5  and R 6  are the same or different, and the phenyl or naphthyl structural unit in structure I, BII and Bill has one, two or three substituents of the R 3 , R 4  and/or R 5  type.