Fuel additives and compositions

Abstract

A salt formed by the reaction of a carboxylic acid with a hydrocarbyl derivative of pyridine. The salts are effective lubricity enhancers when added to low sulphur content fuels and are soluble at low temperatures.

1 . A salt formed by the reaction of a carboxylic acid with a hydrocarbyl derivative of pyridine.  
   
   
       2 . A salt according to  claim 1 , wherein the hydrocarbyl derivative of pyridine is represented by the formula:  
     
       
         
         
             
             
         
       
     
     wherein n is an integer between 1 and 5; and wherein each R independently represents a hydrocarbyl group having between 1 and 30 carbon atoms.  
   
   
       3 . A salt according to  claim 2 , wherein n is at least 2.  
   
   
       4 . A salt according to  claim 2 , wherein at least one group R represents an alkyl or alkenyl group.  
   
   
       5 . A salt according to  claim 3 , wherein at least one group R represents an alkyl or alkenyl group.  
   
   
       6 . A salt according to  claim 1 , wherein the carboxylic acid comprises a fatty acid or a mixture of fatty acids.  
   
   
       7 . A salt according to  claim 6 , wherein the carboxylic acid comprises tall oil fatty acid (TOFA).  
   
   
       8 . An additive composition comprising a salt according to  claim 1 .  
   
   
       9 . A fuel oil composition comprising a major amount of a fuel oil and a minor amount of a salt according to  claim 1 .  
   
   
       10 . A fuel oil composition comprising a major amount of a fuel oil and a minor amount of an additive composition according to  claim 8 .  
   
   
       11 . A fuel oil composition according to  claim 9 , wherein the fuel oil has a sulphur content of less than 0.05% by weight.  
   
   
       12 . A fuel oil composition according to  claim 10 , wherein the fuel oil has a sulphur content of less than 0.05% by weight.  
   
   
       13 . A method of improving the lubricity of a fuel oil having a sulphur content of less than 0.05% by weight, which method comprises the addition to said fuel oil of a salt according to  claim 1 .  
   
   
       14 . A method of improving the lubricity of a fuel oil having a sulphur content of less than 0.05% by weight, which method comprises the addition to said fuel oil of an additive composition according to  claim 8.