Diesel fuel compositions

Abstract

A diesel fuel composition comprising a first additive (i) comprising a quaternary ammonium salt and a second additive (ii) comprising a Mannich reaction product; wherein the quaternary ammonium salt additive (i) is formed by the reaction a quaternising agent which is not an ester and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): wherein R 2 and R 3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from 1 to 5; and R 4 is hydrogen or a C 1 to C 22 alkyl group; and wherein the Mannich reaction product additive (ii) is the product of a Mannich reaction between: (d) an aldehyde; (e) an amine; and (f) a substituted phenol; wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.

The invention claimed is: 
     
         1 - 19 . (canceled) 
     
     
         20 . A method of inhibiting the formation of an emulsion in a diesel fuel composition, the method comprising adding to the diesel fuel a first additive (i) comprising a quaternary ammonium salt and a second additive (ii) comprising a Mannich reaction product; wherein the quaternary ammonium salt additive (i) is formed by the reaction a quaternising agent which is not an ester and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): 
       
         
           
           
               
               
           
         
       
       wherein R 2  and R 3  are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from 1 to 5; and R 4  is hydrogen or a C 1  to C22 alkyl group; and wherein the Mannich reaction product additive (ii) is the product of a Mannich reaction between:
 (a) an aldehyde; 
 (b) an amine; and 
 (c) a substituted phenol; 
 
       wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000. 
     
     
         21 . The method according to  claim 20  wherein the quaternising agent is selected from selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl substituted epoxides in combination with an acid, alkyl halides, alkyl sulfonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, alkyl nitrites, alkyl nitrates, N-oxides or mixtures thereof. 
     
     
         22 . The method according to  claim 20  wherein the quaternising agent is selected from selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates and hydrocarbyl substituted epoxides in combination with an acid. 
     
     
         23 . The method according to  claim 20  wherein the hydrocarbyl substituted acylating agent is reacted with a diamine compound of formula (B 1). 
     
     
         24 . The method according to  claim 20  wherein additive (i) is a salt of tertiary amine prepared from dimethylaminopropylamine and a polyisobutylene-substituted succinic anhydride. 
     
     
         25 . The method according to  claim 20  wherein component (a) used to prepare additive (ii) is formaldehyde. 
     
     
         26 . The method according to  claim 20  wherein component (b) used to prepare additive (ii) is a (poly)ethylene polyamine. 
     
     
         27 . The method according to  claim 20  wherein component (c) used to prepare additive (ii) is a polyisobutylene-substituted phenol. 
     
     
         28 . The method according to  claim 20  wherein in the Mannich reaction used to form additive (ii) the molar ratio of component (a) to component (b) is 2.2-1.01:1; the molar ratio of component (a) to component (c) is 1.99-1.01:1 and the molar ratio of component (b) to component (c) is 1:1.01-1.99. 
     
     
         29 . The method according to  claim 20  wherein in the reaction used to make the Mannich additive the molar ratio of component (a) to component (b) is 2-1.4:1, the molar ratio of component (a) to component (c) is 1.7-1.1:1 and the molar ratio of component (b) to component (c) is 1:1.1-1.7. 
     
     
         30 . The method according to  claim 20  wherein the diesel fuel comprises a non-renewable Fischer Tropsch fuel and/or biodiesel. 
     
     
         31 . The method according to  claim 20  wherein the diesel fuel further comprises a fuel-borne catalyst which includes a metal selected from iron, cerium, group I and group II metals, platinum, manganese and mixtures thereof. 
     
     
         32 . The method according to  claim 20  wherein the emulsion forming tendency is measured according to ASTM D7451-Water Separation Properties of Light and Middle Distillate, and Compression and Spark Ignition Fuels—or a version thereof modified as described herein.