Fuel compositions, methods and uses relating to quaternary ammonium salt additives for fuel used in spark ignition engines

Abstract

A gasoline fuel composition comprising as an additive an ester compound which is the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and an alcohol or formula H—(OR).sub.n—OR.sup.1, wherein R is an optionally substituted alkylene group; R.sup.1 is hydrogen or an optionally substituted hydrocarbyl group, and n is 0 or a positive integer; wherein n is not O when R.sup.1 is hydrogen.

Claims

1. A gasoline fuel composition comprising as an additive an ester compound which is the reaction product of a succinic acid or anhydride thereof having a polyisobutenyl substituent having a number average molecular weight of 700 to 1300 and an alcohol of formula H—(OR).sub.n—OR.sup.1, wherein R is an optionally substituted alkylene group; R.sup.1 is hydrogen or an optionally substituted hydrocarbyl group, and n is 0 or a positive integer; wherein n is not 0 when R.sup.1 is hydrogen; wherein the polyisobutenyl substituted succinic acid or anhydride and alcohol of formula H—(OR).sub.n—OR.sup.1 are reacted in a molar ratio of from 1.5:1 to 1:1.5.

2. A method of combatting deposits in a direct injection spark ignition engine, the method comprising combusting in the engine a gasoline composition comprising as an additive the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and a polyhydric alcohol of formula H—(OR).sub.nOR.sup.1, wherein R is an optionally substituted alkylene group; R.sup.1 is hydrogen or an optionally substituted hydrocarbyl group, and n is 0 or a positive integer, wherein n is not 0 when R.sup.1 is hydrogen.

3. The composition according to claim 1 wherein the optionally substituted polycarboxylic acid or anhydride thereof is a hydrocarbyl substituted succinic acid or a hydrocarbyl substituted succinic anhydride.

4. The composition according to claim 1 wherein each R is ethylene or propylene.

5. The composition according to claim 1 wherein the polycarboxylic acid or anhydride thereof includes an optionally substituted alkyl or alkenyl group having 6 to 100 carbon atoms.

6. The composition according to claim 1 wherein the polycarboxylic acid or anhydride is a succinic acid or anhydride thereof having a polyisobutenyl substituent having a number average molecular weight of 100 to 5000.

7. The composition according to claim 1 wherein the polyisobutenyl substituted succinic acid or anhydride and alcohol of formula H—(OR).sub.n—OR.sup.1 are reacted in a ratio of from 2.5:1 to 1.5:1 and R.sup.1 is hydrogen.

8. The composition according to claim 1 wherein n is 0 and R.sup.1 is a C.sub.6 to C.sub.30 alkyl group.

9. The composition according to claim 1 wherein R.sup.1 is hydrogen.

10. The composition according to claim 1 wherein n is 1 or more and R.sup.1 is a C.sub.4 to C.sub.30 alkyl group.

11. The composition according to claim 1 wherein the additive is the reaction product of a succinic acid or anhydride of formula (A3) or (A4): ##STR00011## and an alcohol of formula H—(OR).sub.n—OR.sup.1; wherein R.sup.2 is an alkyl or alkenyl group having 6 to 36 carbon atoms or a polyisobutenyl group having a number average molecular weight of from 200 to 1300; wherein the alcohol of formula H—(OR).sub.n—OR.sup.1 is selected from the group consisting of: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, trehalose, sorbitol, glycerol, pentaerythritol, trimethylol propane, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and a polyethylene or polypropylene glycol having a number average molecular weight of 300 to 1200; or a C6 to C24 ether thereof; and benzyl alcohol, tetradecanol, butanol, 2-butanol, isobutanol, octanol, 2-ethylhexanol, hexanol, cyclohexanol, cyclooctanol, 2-propylheptanol, 2-ethyl-1-butanol and isopropanol.

12. The composition according to claim 1 wherein the additive is the reaction product of a succinic acid or anhydride of formula (A3) or (A4) and an alcohol of formula H—(OR).sub.n—OR.sup.1; wherein R.sup.2 is a polyisobutenyl group having a number average molecular weight of from 700 to 1300; wherein the alcohol of formula H-(OR).sub.n—OR.sup.1 is selected from the group consisting of: butanediols, tripropylene glycol and polypropylene glycols having a number average molecular weight of from 300 to 600; and tetradecanol, butanol and 2-ethylhexanol.

13. The method according to claim 2 which achieves “keep clean” performance.

14. The method according to claim 2 which achieves “clean up” performance.

15. The method according to claim 2 wherein the deposits are injector deposits.

16. The method according to claim 15 wherein the deposits are internal injector deposits.

17. The method according to claim 2 which combats intake valve deposits.

18. The composition according to claim 1 wherein the gasoline fuel composition comprises one or more further additives selected from the group consisting of: a) carrier oils; b) acylated nitrogen compounds which are the reaction product of a carboxylic acid-derived acylating agent and an amine; c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms; d) mannich base additives comprising nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine; e) aromatic esters of a polyalkylphenoxyalkanol; and f) quaternary ammonium salts.

19. The composition according to claim 1 wherein the gasoline composition comprises a mixture of two or more ester additives.

20. The method according to claim 2 which achieves an improvement in performance of one or more of: improved fuel economy; reduced maintenance; less frequent overhaul or replacement of injectors; improved driveability; improved power; or improved acceleration.

Description

EXAMPLE 1

(1) Additive A1, an ester additive of the invention was prepared as follows:

(2) A mixture of alkenes having 20 to 24 carbon atoms was heated with 1.2 molar equivalents of maleic anhydride. On completion of the reaction excess maleic anhydride was removed by distillation. The anhydride value of the substituted succinic anhydride product was measured as 2.591 mmolg.sup.−1.

(3) This product was then heated with one molar equivalent of polypropylene glycol having a number average molecular weight of 425, and the reaction was monitored by FTIR.

(4) Additive A2 was prepared by a method analogous to that used to prepare additive A1 except that a polyisobutene having a number average molecular weight of 1000 was used in place of the mixture of alkenes.