Fuel additives

Abstract

An additive composition comprises at least one colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: (i) at least one aldehyde or ketone or reactive equivalent thereof, and (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1 or COR 1 , wherein R 1 represents hydrogen or a hydrocarbyl group. The composition may further include at least one lubricity enhancer. Compositions of the invention tend to resist haziness, cloudiness and phase separation at relatively low and relatively high temperatures, and in the presence of lubricity enhancers and fatty acid methyl esters (FAME).

1 . An additive composition, the composition comprising at least one colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: 
 (i) at least one aldehyde or ketone or reactive equivalent thereof, and    (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1  or COR 1 , wherein R 1  represents hydrogen or a hydrocarbyl group.    
     
     
         2 . The additive composition of  claim 1 , wherein the stabilising component comprises an alkylphenol formaldehyde condensate or a hydroxybenzoate formaldehyde condensate.  
     
     
         3 . The additive composition of  claim 1 , wherein the colloidal metal compound comprises at least one metal oxide.  
     
     
         4 . The additive composition of  claim 3 , wherein the metal oxide is chosen from iron oxide, cerium oxide or cerium-doped iron oxide.  
     
     
         5 . The additive composition of  claim 1  further comprising at least one lubricity enhancer.  
     
     
         6 . The additive composition of  claim 5 , wherein the at least one lubricity enhancer is a carboxylic acid or ester thereof.  
     
     
         7 . The additive composition of  claim 1  which is substantially free from sulphur-containing compounds.  
     
     
         8 . A fuel composition, the composition comprising a major amount of a fuel and a minor amount of an additive composition comprising at least one colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: 
 (i) at least one aldehyde or ketone or reactive equivalent thereof, and    (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1  or COR 1 , wherein R 1  represents hydrogen or a hydrocarbyl group.    
     
     
         9 . The fuel composition of  claim 8 , wherein the fuel comprises a middle distillate fuel oil.  
     
     
         10 . A process for stabilising an additive composition, which comprises blending a colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: 
 (i) at least one aldehyde or ketone or reactive equivalent thereof, and    (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1  or COR 1 , wherein R 1  represents hydrogen or a hydrocarbyl group.    
     
     
         11 . The process of  claim 10 , wherein the additive composition further comprises at least one lubricity enhancer.  
     
     
         12 . A process for stabilising a fuel composition, which comprises blending a colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: 
 (i) at least one aldehyde or ketone or reactive equivalent thereof, and    (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1  or COR 1 , wherein R 1  represents hydrogen or a hydrocarbyl group.    
     
     
         13 . The process of  claim 12 , wherein the fuel composition further comprises at least one lubricity enhancer.  
     
     
         14 . A method for improving the stability of a fuel additive composition or of a fuel composition, wherein the fuel additive composition or the fuel composition comprises a colloidal metal compound or metallic species and optionally, at least one lubricity enhancer; the method comprising blending the fuel additive composition or the fuel composition and a stabilising component which comprises the product obtainable by the condensation reaction between: 
 (i) at least one aldehyde or ketone or reactive equivalent thereof, and    (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR 1  or COR 1 , wherein R 1  represents hydrogen or a hydrocarbyl group.