Diesel fuel emulsion

1. A fuel emulsion comprises a water-in-diesel emulsion containing an emulsifier composition in an amount effective to form a stable emulsion, the emulsifier composition comprising:

(i) a polyester non-ionic surfactant having hydrophilic repeating units comprising polyoxyalkylene and hydrophobic repeating units comprising long chain hydrocarbon residues; and

(ii) at least one component selected from:

a) fatty acid esters or partial esters of polyhydric alcohols;

b) alkoxylated fatty acid esters or partial esters of polyhydric alcohols; and

c) alkoxylated primary alcohols;

wherein:

1) the polyester non-ionic surfactant has a hydrophile/lipophile balance value of between 4 and 8, and

2) the emulsifier composition has an hydrophile/lipophile balance value of at least 4 and not more than 8;

3) the fuel emulsion is stable for at least 10,000 minutes.

2. A fuel emulsion according to claim 1 which contains at least 70% by weight diesel and up to 25% by weight of water, the weight percentages being based on the total weight of the emulsion.

3. A fuel emulsion according to claim 1 comprising an amount of emulsifier composition in the range 0.1% to 4% by weight of the total weight of the composition.

4. A fuel emulsion according to claim 1 in which the emulsifier composition has an hydrophile/lipophile balance value of at least 5 and not more than 8.

5. A fuel emulsion according to claim 1 which comprises not more than 50% by weight, based on the total weight of the emulsifier composition, of the polyester non-ionic surfactant in combination with at least one of components a), b) and c).

6. A fuel emulsion according to claim 1 which comprises the polyester non-ionic surfactant in combination with at least two of components a), b) and c).

7. A fuel emulsion according to claim 1 which comprises the polyester non-ionic surfactant in combination with components a) and b).

8. A fuel emulsion according to claim 1 in which component a) is a reaction product of one or more polyhydric alcohols and one or more fatty acids.

9. A fuel emulsion according to claim 8 in which the polyhydric alcohol comprises alcohols having at least three hydroxyl groups.

10. A fuel emulsion according to claim 8 in which the polyhydric alcohol is selected from glycerol and sorbitol.

11. A fuel emulsion according to claim 8 in which the fatty acid comprises a C 12 to C 24 , straight or branched chain, saturated or unsaturated acid.

12. A fuel emulsion according to claim 8 in which the fatty acid comprises a C 16 to C 20 straight chain acid.

13. A fuel emulsion according to claim 8 in which the fatty acid is selected from stearic acid or oleic acid.

14. A fuel emulsion according to claim 1 in which component b) is a reaction product of at least one component a) with an alkylene oxide.

15. A fuel emulsion according to claim 1 in which component b) is a reaction product of at least one component a) with not more than 50 moles of an alkylene oxide.

16. A fuel emulsion according to claim 1 in which component c) is a reaction product of C 7 -C 20 primary alcohols or mixtures thereof with an alkylene oxide.

17. A fuel emulsion according to claim 1 in which component c) is a reaction product of C 7 -C 20 primary alcohols or mixtures thereof with not more than 50 moles of an alkylene oxide.

18. A fuel emulsion according to claim 1 comprising a primary alcohol.

19. A fuel emulsion according to claim 18 comprising a primary alcohol selected from C 5 to C 15 primary alcohols.

20. A fuel emulsion according to claim 18 in which the primary alcohol comprises up to 5% by weight of the emulsifier composition.

21. An emulsifier composition for use in fuel emulsions, which composition comprises:

(i) a polyester non-ionic surfactant having hydrophilic repeating units comprising polyoxyalkylene and hydrophobic repeating units comprising long chain hydrocarbon residues; and

(ii) at least one component selected from:

a) fatty acid esters or partial esters of polyhydric alcohols;

b) alkoxylated fatty acid esters or partial esters of polyhydric alcohols; and

c) alkoxylated primary alcohols;

wherein:

1) the polyester non-ionic surfactant has a hydrophile/lipophile balance value of between 4 and 8, and

2) the emulsifier composition has an hydrophile/lipophile balance value of at least 4 and not more than 8;

3) the fuel emulsion is stable for at least 10,000 minutes.

22. An emulsifier composition according to claim 21 having an hydrophile/lipophile balance value of at least 5 and not more than 8.

23. An emulsifier composition according to claim 21 which comprises not more than 50% by weight, based on the total weight of the emulsifier composition of the polyester non-ionic surfactant in combination with at least one of components a), b) and c).

24. An emulsifier composition according to claim 21 which comprises the polyester non-ionic surfactant in combination with at least two of components a), b) and c).

25. An emulsifier composition according to claim 21 which comprises the polyester non-ionic surfactant in combination with components a) and b).

26. An emulsifier composition according to claim 21 in which component a) is a reaction product of one or more polyhydric alcohols and one or more fatty acids.

27. An emulsifier composition according to claim 26 in which the polyhydric alcohol comprises alcohols having at least three hydroxyl groups.

28. An emulsifier composition according to claim 26 in which the polyhydric alcohol is selected from glycerol and sorbitol.

29. An emulsifier composition according to claim 26 in which the fatty acid comprises a C 12 to C 24 , straight or branched chain, saturated or unsaturated acid.

30. An emulsifier composition according to claim 26 in which the fatty acid comprises a C 16 to C 20 straight chain acid.

31. An emulsifier composition according to claim 26 in which the fatty acid is selected from stearic acid or oleic acid.

32. An emulsifier composition according to claim 21 in which component b) is a reaction product of at least one component a) with an alkylene oxide.

33. An emulsifier composition according to claim 32 in which component b) is a reaction product of at least one component a) with not more than 50 moles of an alkylene oxide.

34. An emulsifier composition according to claim 21 in which component c) is a reaction product of C 7 -C 20 primary alcohols or mixtures thereof with an alkylene oxide.

35. An emulsifier composition according to claim 34 in which component c) is a reaction product of C 7 -C 20 primary alcohols or mixtures thereof with not more than 50 moles of an alkylene oxide.

36. An emulsifier composition according to claim 21 comprising a primary alcohol.

37. An emulsifier composition according to claim 36 comprising a primary alcohol selected from C 7 -C 20 primary alcohols.

38. An emulsifier composition according to claim 36 in which the primary alcohol comprises up to 5% by weight of the emulsifier composition.

39. A method of making a fuel emulsion which comprises a water-in-diesel emulsion containing an emulsifier composition in an amount effective to form a stable emulsion, the emulsifier composition comprising:

(i) a polyester non-ionic surfactant having hydrophilic repeating units comprising polyoxyalkylene and hydrophobic repeating units comprising long chain hydrocarbon residues; and

(ii) at least one component selected from:

a) fatty acid esters or partial esters of polyhydric alcohols;

b) alkoxylated fatty acid esters or partial esters of polyhydric alcohols; and

c) alkoxylated primary alcohols;

wherein:

1) the polyester non-ionic surfactant has a hydrophile/lipophile balance value of between 4 and 8, and the emulsifier composition has an hydrophile/lipophile balance value of at least 4 and not more than 8;

2) said method comprises, in a single mixing operation, introducing diesel and the emulsifier composition and then water into a mixing vessel whilst subjecting the mixture to high shear mixing at a speed and for a period sufficient to create the emulsion; and

3) the fuel emulsion is stable for at least 10,000 minutes.