Compositions and methods and uses relating thereto
A fuel composition comprising as an additive the reaction product of a polycarboxylic acid having no more than 5 carbon atoms per carboxylic acid group, or an anhydride thereof and an alcohol having at least 5 carbon atoms.
1 . A diesel fuel composition comprising as an additive the reaction product of a polycarboxylic acid or an anhydride thereof and an alcohol, wherein the polycarboxylic acid or anhydride thereof is selected from, itaconic acid, citraconic acid, 2-methylene glutaric acid, 2-methylene adipic acid, isocitric acid, 2-hydroxycitric acid, malic acid, tartaric acid, 2-hydroxyadipic acid, 2-hydroxyglutaric acid, aconitic acid, and anhydrides and/or isomers thereof, and the alcohol is selected from cetyl alcohol, stearyl alcohol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol, and oleyl alcohol;
wherein the polycarboxylic acid compound and the alcohol are reacted in a molar ratio of from 2:1 to 1:2;
wherein the additive is present in the diesel fuel composition in an amount of 5 to 1,000 ppm by weight; and
wherein the diesel fuel composition comprises less than 50 ppm sulphur by weight.
2 . A method of improving the performance of a modern diesel engine having a high pressure fuel system by combating deposits in the engine, the method comprising combusting in the diesel engine a diesel fuel composition comprising as an additive the reaction product of a polycarboxylic acid or an anhydride thereof and an alcohol, wherein the polycarboxylic acid or anhydride thereof is selected from citric acid, itaconic acid, citraconic acid, 2-methylene glutaric acid, 2-methylene adipic acid, isocitric acid, 2-hydroxycitric acid, malic acid, tartaric acid, 2-hydroxyadipic acid, 2-hydroxyglutaric acid, aconitic acid, and anhydrides and/or isomers thereof and the alcohol is selected from cetyl alcohol, stearyl alcohol, 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol, and oleyl alcohol;
wherein the polycarboxylic acid compound and the alcohol are reacted in a molar ratio of from 2:1 to 1:2;
wherein the additive is present in the diesel fuel composition in an amount of 5 to 1,000 ppm by weight; and
wherein the diesel fuel composition comprises less than 50 ppm sulphur by weight.
3 . The diesel fuel composition according to claim 1 wherein the polycarboxylic acid or anhydride thereof is selected from, itaconic acid and itaconic anhydride.
4 . The diesel fuel composition according to claim 1 wherein the alcohol is selected from 2-hexyl-1-decanol, 2-octyl-1-decanol, 2-hexyl-1-dodecanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol or oleyl alcohol.
5 . The diesel fuel composition according to claim 1 wherein the alcohol is selected from cetyl alcohol or stearyl alcohol.
6 . The diesel fuel composition according to claim 1 wherein the additive has an acid value of from 0.6 to 9.7 mmol H + /g.
7 . The diesel fuel composition according to claim 1 wherein the diesel fuel composition comprises one or more further additives selected from:
(i) a quaternary ammonium salt additive;
(ii) the product of a Mannich reaction between an aldehyde, an amine and an optionally substituted phenol,
(iii) the reaction product of a carboxylic acid-derived acylating agent and an amine;
(iv) the reaction product of a carboxylic acid-derived acylating agent and hydrazine;
(v) a salt formed by the reaction of a carboxylic acid with di-n-butylamine or tri-n-butylamine;
(vi) the reaction product of a hydrocarbyl-substituted dicarboxylic acid or anhydride and an amine compound or salt which product comprises at least one amino triazole group;
(vii) a substituted polyaromatic detergent additive; and
(viii) partial esters of substituted succinic acids.
8 . The diesel fuel composition according to claim 7 wherein the diesel fuel composition further comprises a quaternary ammonium salt additive; wherein the quaternary ammonium salt additive is the reaction product of a nitrogen-containing species having at least one tertiary amine group and a quaternising agent wherein the nitrogen containing species is the reaction product of a hydrocarbyl-substituted acylating agent and a compound comprising at least one tertiary amine group and a primary amine, secondary amine or alcohol group; wherein the quaternising agent is an ester quaternising agent.
9 . The method according to claim 2 , wherein the modern diesel engine is characterised by a fuel injection system which provides a fuel pressure of more than 1350 bar.
10 . The method according to claim 9 wherein the improvement in performance is selected from one or more of:
a reduction in power loss of the engine;
a reduction in external diesel injector deposits;
a reduction in internal diesel injector deposits;
an improvement in fuel economy;
a reduction in fuel filter deposits;
a reduction in emissions; and
an increase in maintenance intervals.
11 . The method according to claim 2 which combats internal diesel injector deposits.
12 . The method according to claim 2 which achieves a maximum exhaust temperature deviation of less than 30° C. in the DW10C test.
13 . The method according to claim 2 which achieves keep clean performance characterised by reducing or preventing the formation of deposits.
14 . The method according to claim 2 which achieves clean up performance characterised by reducing or removing existing deposits.