WO1991007477A1

WO1991007477A1 - Gasoline composition

Info

Publication number: WO1991007477A1
Application number: PCT/GB1990/001709
Authority: WO
Inventors: Ursula Henzi
Original assignee: Rechem Ag; Eder, Ephry
Priority date: 1989-11-11
Filing date: 1990-11-07
Publication date: 1991-05-30
Also published as: GB8925535D0; AU7041991A

Abstract

For use as an additive to gasoline for a spark-ignition internal combustion engine, an akali or alkaline earth metal salt of a mono or diester of sulphosuccinic acid characterised in that the aliphatic hydrocarbyl group or groups of the ester contain from 4 to 20 carbon atoms and in that, for the diester, the aliphatic hydrocarbyl groups are the same or different.

Description

- 1 -

GASOLINE COMPOSITION

This invention relates to a gasoline composition, particularly but not exclusively an unleaded or low leaded gasoline composition, comprising a major amount of a gasoline suitable for use in spark . ignition internal combustion engines and a minor amount of at least one additive.

It is known that certain additives can improve the performance of spark plugs and the ignition of lean gasoline/air mixtures. Use of alkali metal or alkaline earth metal compounds, either organic or inorganic, in gasoline improves the development of ar> early flame and tne flame speed in the cylinder and thereby improves combustion of lean gasoline/air mixtures without impairing the functioning of the engine or the driveability of the vehicle.

It is known that alkali metals and alkaline earth metal compounds may be added to gasoline. British Patent- Specification No. 785,196 describes fuels including gasoline, containing mono-valent me :al salts of alkyl salicylic or napthenic acids to prevent corrosion. British Patent Speci ication No. 818,323 describes the addition Of alkaline earth metal compounds to light hydrocarbon mixtures such as gasoline. United States Patent No. 4,659,338 describes a fuel composition containing at least one hydrocarbon soluble alkali metal or alkaline earth metal containing composition and ashless dispersant used toreduce valve seat recession in internal co buszion engines.

Materials previously proposed for incorporation into gasoline for the purpose of improving the performance of spark plugs and the flame speed A the cylinder are described in European Patent Publication No. 0 207 560

SUBSTITUTE SHEET (Application No. 86201081.6). This publication describes a gasoline composition said to improve the flame speed in the cylinder without giving rise to any fouling in the engine. This composition comprises a major amount of a gasoline suitable for use in spark ignition engines and a minor amount of an alkali metal or alkaline earth metal salt of a succinic acid derivative having as a substituent on at least one of its alpha carbon atoms an unsubstituted or substituted aliphatic hydrocarbon group having from 20 to 200 carbon atoms, or of a succinic acid derivative having as a substituent on one of its alpha carbon atoms an unsubstituted or substituted hydrocarbon group having from 20 to 200 carbon atoms which is connected to the other alpha carbon atom by means of a hydrocarbon moiety having from 1 to 6 carbon atoms, forming a ring structure. The preferred metal suggested is potassium.

According to the present invention there is provided a gasoline composition containing a minor amount of an alkali metal or alkaline earth metal salt of a mono or diester of sulphosuccinic acid where the the aliphatic hydrocarbyl group or groups of the ester contain from 4 to 20 carbon atoms.

Experiments with such compositions have exhibited improvements in the performance of spark plugs and the flame speed in the cylinder.

The aliphatic hydrocarbyl group or groups of the ester may be saturated or unsaturated. The aliphatic hydrocarbyl group or groups of the ester may contain substituents. In the diester, the aliphatic hydrocarbyl group may be the same or different.

One or more hydrogen atoms may be replaced by another atom or by a non alphatic organic group e.g. hydroxy, ether-

SUBSTITUTE SHEET - 3-

ketone, phenyl or ester. The hydrocarbyl group may also be cyclic, e.g. cyclohexyl.

The metal salts of mono and diesters of sulphosuccinic acid can be represented by the following formulae:

and

and for the diester:

in which M is an alkali metal or alkaline earth metal and where n is the valency of M. R and R' are aliphatic hydrocarbyl groups containing from 4 to 20 carbon atoms aε described above.

The alkali metal or alkaline earth metal salts of the diesters of sulphosuccinic acid are preferred because they have been found to be soluble in gasoline to an extent which will permit the desired level of addition of alkali metal or alkaline earth metal to the gasoline. For similar reasons the chain length of the aliphatic hydrocarbyl group or groups has 4 to 20 carbon atoms. It is considered that when chains less than 4 carbon atoms are used the resulting molecule is too polar for gasoline solubility. A carbon chain length of more than 20 is considered unnecessary. The preferred carbon chain length for the or each aliphatic hydrocarbyl group is 6 to 13 and a carbon chain length of 8 being particularly preferred. Providing such unexpectedly short carbon chain lengths for the aliphatic hydrocarbyl

SUBSTITUTE SHEET - 4-

group or groups of the ester results in a particularly efficient introduction of alkali or alkaline earth metals into the fuel in a completely soluble form.

Many alkali and alkaline earth metal salts, even though soluble in gasoline, are unsuitable for use as a gasoline additive because they have a strong tendency to emulsify water into gasoline. It has been found that this tendency to form emulsions is minimised when the chain length of the aliphatic hydrocarbyl group is 6 to 12 carbon atoms, and preferably 8 carbon atoms, and particularly so where these groups are isooctyl or 2-ethylhaxyl. The preferred metal 13 potassium.

Techniques for the preparation of metal salts of mono or diesters of sulphosuccinic acid are well known in the art and described in British Patents No. 446,568; No. 760,121 ; and No. 1 ,050,578.

The alkali and alkaline earth metal salts of the mono and diesters of sulphosuccinic acid have been found to improve the flame speed in the cylinder even whuch such salts are included in the gasoline in very small quantities. Preferably the amount of the alkali or alkaline earth metal salt included in the fuel composition is an amount sufficient to provide from about 1 to about 100 parts per million by weight of the metal in the fuel composition according to the present invention.

The gasolines contemplated for use in the gasoline composition of the present invention, include hydrocarbon base fuels, having a boiling range from 30°C - 230°C. These fuels may be straight run distillate fractions, catalytically or thermally cracked, catalytically reformed or hydrocracked fractions or mixtures thereof. The gasolines may contain substantial amounts of alcohols,

SUBSTITUTE SHEET - 5-

ethers, ketones or esters. The gasolines preferaAy utilized include those designated as motor gasoline?, suitable for use in spark ignition internal combustion engines.

The present invention applies particularly to unleaded or low leaded gasolines, containing less than about 0.5gm of lead per litre of fuel, generally added as tetraethyl lead. The gasoline co postion can also contain antioxidants such as 2,6, ditertiary butylphenol or phenylenediamines.

Additionally the gasoline may contain hydrocarbon solub." ^••^•■ detergents or dispersants designed to reduce depoA formation on carburettors, fuel injectors, inlet valves an-¹ in the combustion chamber. Typically such detergents or dispersants may be fatty acid imidazolines, hydrocarbyl substituted amines, polyalkene succinimides, esters of substituted carboxylic acids, nitrogen containing condensates of phenols, alkoxylated phenols and various polymers, preferably used at between 50 and 1000 parts per million by weight.

An important effect arising from the use of the alkali or. alkaline earth metal salt of a mono or diester of sulphosuccinic acid in a gasoline containing a detergent cr dispersant is that the metal salt itself imparts detergency in respect of inlet valve deposits, that is to say it reduces deposit formation on inlet valves thereby enhancing the performance of the gasoline in this respect.

The alkali or alkaline earth metal salts of the above mentioned esters of sulphosuccinic acid may be added separately to the gasoline or may be blended with other additives and added together. Preferably the alkali or alkaline earth metal salt of the invention is in the form oi a solution in a gasoline-compatible diluent - advantageously

SUBSTITUTE SHEET such that the alkali or alkaline earth metal salt comprise_;; from 30 to 85^% of the weight of additive solution. Suitable gasoline-compatible diluents include alcohols, ethers and aromatic hydrocarbons.

SUBSTITUTE SHEET

Claims

1. A gasoline composition comprising a major amount of b gasoline suitable for use in a spark ignition internal combustion engine and a minor amount of an alkali or alkaline earth metal salt o_^ ^r a mono or diester of sulphosuccinic acid CHARACTERISED IN THAT the aliphatic hydrocarbyl group or groups of the ester contain from 4 to 20 carbon atoms.

2. A gasoline composition according to Claim 1 CHARACTERISED IN THAT the aliphatic hydrocarbyl groups oϊ the diester are the same.

3. A gasoline composition according to Claim 1 CHARACTERISED IN THAT the aliphatic hydrocarbyl groups of the diester are different.

4. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT the metal is an alkali metal.

5. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT the aliphatic hydrocarbyl group or groups of the mono or diester of sulphosuccinic acio contain 6 to 13 carbon atoms.

6. A gasoline composition according to any preceding Claim CHARACTERISED IN- THAT the aliphatic hydrocarbyl group or groups of the mono or diester of sulphosuccinic acid contain 8 carbon atoms.

7. A gasoline composition accor»3ing to any preceding Claim CHARACTERISED IN THAT it contains 1 to 100 parts per million by weight of the said alkali or alkaline earth metal.

SUBSTITUTE SHEET

8. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT the said hydrocarbyl group is cyclic.

9. A gasoline composition according to any preceding Claiπ CHARACTERISED IN THAT the said hydrocarbyl . group is cyclohexyl.

10. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT the said group is an isoctyl or is a 2-ethylhexyl.

11. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT it contains less than 0.5g of lead per litre of gasoline.

12. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT it contains one or more antioxidants and/or one or more hydrocarbon soluble detergents and/or dispersants.

13. A gasoline composition according to any preceding Claim CHARACTERISED IN THAT it contains one or more hydrocarbon soluble detergents and/or dispersants of between 50 to 1000 parts per million by weight.

14. A solution, suitable for addition to gasoline, of the alkali or alkaline earth metal salt of a mono or diester of sulphosuccinic acid CHARACTERISED IN THAT the aliphatic hydrocarbyl group or groups of the ester contain from 4 to 20 carbon atoms and in a suitable gasoline-compatible solvent such that the alkali or alkaline earth metal salt comprises 30 - 85% of the weigh- of the additive solution.

15. A solution according to Claim ^',4 CHARACTERISED IN THAT, for the diester, the aliphatic hydrocarbyl groups

SUBSTITUTE SHEET - ci -

are either the same or are different.

16. A solution according to Claiml4 or Claim 15, CHARACTERISED IN THAT the weight of the salt comprises fron. 30 to 85% of the weight of the solution.

17. A method for operating a spark-ignition internal combustion engine, CHARACTERISED IN THAT a gasoline composition according to any of Claims 1 to 13 is introduαA into the engine.

18. A method for operating a spark-ignition internal combustion engine, said method being CHARACTERISED BY the step of adding to the fuel to be used in the engine a solution according to any one of Claims 14 to 17.

19. For use as an additive"to gasoline for a spark-ignition internal combustion engine, an akali or alkaline earth metal salt of a mono or diester of sulphosuccinic acid CHARACTERISED IN THAT the aliphatic hydrocarbyl group -•. groups of the ester contain from 4 to 20 carbon atoms <Α IN THAT, for the diester, the aliphatic hydrocarby. groups are the same or different.

SUBSTITUTE SHEET