Fuel oil compositions

Abstract: Sediment and colour formation are reduced in a diesel or heating fuel by incorporating in the fuel a quaternary ammonium salt, the cation of which is the reaction product of a tertiary amine, an olefin oxide and water.

Description: This invention relates to fuel oil compositions and more especially to fuel oil compositions containing cracked components which are stabilized against sediment formation and colour development during storage. Cracked components are frequently included to give higher yields of diesel fuel and heating oil. However, when diesel and heating oils containing cracked components are stored at ambient or elevated temperatures in air they become discoloured and precipitate sludge or sediment. It is clear that the problem of discoloration and sediment formation is exacerbated by the presence of cracked components in the fuel. This is demonstrated by the results in Table 1 which show the amount of sediment formed and the colour change when various fuel blends are tested in the AMS 77.061 accelerated stability test. Published research (see, for example, Offenhauer et. al, Industrial and Engineering Chemistry, 1957, Volume 49, page 1265, and the Proceedings of the 2nd International Conference on the Long Term Stability of Liquid Fuels, San Antonio, Texas, published October 1986) suggests that discoloration and sediment result from the oxidation of sulphur and nitrogen compounds present in the fuel. The analysis of cracked components is consistent with this. The results in Table 2 show that cracked components contain significantly larger quantities of nitrogen and sulphur than straight distillates. Also, the addition of nitrogen and sulphur compounds to a stable straight distillate causes an increase in both sediment and colour in the AMS 77.061 test (Table 3) with the worst result being obtained when both nitrogen and sulphur compounds are present in the fuel. FR-A-1,301,479 describes the use of quaternary alkyl-, alkenyl- and aralkyl-substituted ammonium nitrites in combination with substituted propylene diamines in preventing discoloration and sedimentation of fuel oils during storage. U.S. Patent No. 3,419,366 is concerned with the use of alkoxylated quaternary ammonium salicylates as microbicides in hydrocarbon oils. FR-A-2,249,948 discloses epoxy adducts of quaternary ammonium salts of inorganic acids to impart dispersancy, anti-icing and rust-inhibiting properties to liquid fuels. EP-A-293,192 relates to the use of quaternary ammonium salts as fuel additives to reduce combustion chamber fouling. It has now been found that sediment and colour formation resulting from oxidation of sulphur and nitrogen compounds present in the fuels may be substantially reduced in diesel fuels or heating fuels, especially those containing cracked components, by the addition of certain quaternary ammonium compounds. According to this invention fuel compositions comprise a base fuel, which may contain cracked components, and a quaternary ammonium salt in which the cation is derivable from, and advantageously derived from, the reaction of a tertiary amine with an olefin oxide in the presence of excess water to yield a solution of a quaternary ammonium hydroxide, and the anion is derived from an organic acid, subject to the provisos that when the acid is an alkane monocarboxylic acid the alkane is a straight chain alkane, and that the anion is not derived from salicylic acid or ethosulphuric acid. The quaternary ammonium salts may be made in two stages: In the first stage a tertiary amine is reacted with an olefin oxide in the presence of excess water to yield a solution of a quaternary ammonium hydroxide, e.g. in which each R', which may be the same or different, is an organic group; and each R'', which may be the same or different, is hydrogen or an organic group. In the second stage the quaternary ammonium hydroxide is neutralized with an organic acid to form a quaternary ammonium salt, i.e. As examples of suitable tertiary amines there may be mentioned: (i) amines of the formula R¹R²R³N where R¹, R² and R³ which may be the same or different are each substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl. Each group R¹, R² and R³ preferably has 1 to 20 carbon atoms. Examples of this type of amine are trimethylamine; ethyldimethylamine; n-propyldimethylamine; triethanolamine; N,N-dimethylbenzylamine; N,N-dimethylcyclohexylamine; N,N-dimethylaniline; N,N-dimethyl-(4-methylcyclohexylamine) and N,N-dimethyl-p-toluidine. (ii) diamines of the formula R⁴R⁵N(CH₂) n NR⁶R⁷ where n is an integer of one or more, and R⁴, R⁵, R⁶ and R⁷, which may be the same or different, are as defined above for R¹. Thus, one may use N,N,N', , N'-tetramethyl ethylenediamine. (iii) fully alkylated alkylene polyamines of the formula: where m is an integer of one or more and R⁸, R⁹, R¹⁰, R¹¹, and R¹², which may be the same or different, are as defined for R¹ above. (iv) pyridine and substituted pyridines e.g., α, β and gamma- picolines, quinoline and substituted quinolines and similar heterocyclic tertiary amines. (v) N-substituted piperidines of the formula: where R¹³ is as defined for R¹ above. (vi) N-substituted pyrrolidines of the formula: where R¹⁴ is as defined for R¹ above. (vii) N-substituted morpholines of the formula: where R¹⁵ is as defined for R¹ above. (viii) amines of the formula: where n is an integer of two or more e.g. triethylene diamine. (xi) hexamethylenetetramine (CH₂)₆N₄ (hexamine). The olefin oxides are preferably of the formula: where R¹⁶, R¹⁷, R¹⁸, and R¹⁹ which may be the same or different, are each hydrogen, or substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl. Specific examples are ethylene oxide, propylene oxide, but-1-ene oxide, but-2-ene oxide, oct-1-ene oxide and styrene oxide. The organic acid which may be used in the second stage of the reaction and hence forms the anion in the quaternary ammonium salt may be, for example, a carboxylic acid, carboxylic acid anhydride, phenol, sulphurized phenol, or sulphonic acid, subject to the proviso that in the aspect of the invention which is a fuel oil composition, unlimited as to type, then when the acid is an alkane monocarboxylic acid the alkane is a straight chain alkane and, preferably, the acid is an alkane 1-carboxylic acid. The carboxylic acid may be, for example: i) An acid of the formula: R-COOH where R is hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl group. Examples of such acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, palmitic acid, stearic acid, cyclohexanecarboxylic acid, 2-methylcyclohexane carboxylic acid, 4-methylcyclohexane carboxylic acid, oleic acid, linoleic acid, linolenic acid, cyclohex-2-eneoic acid, benzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, salicylic acid, 2-hydroxy-4-methylbenzoic acid, 2-hydroxy-4-ethylsalicylic acid, p-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, o-aminobenzoic acid, p-aminobenzoic acid, o-methoxybenzoic acid and p-methoxybenzoic acid. ii) A dicarboxylic acid of the formula HOOC-(CH₂) n -COOH where n is zero or an integer, including e.g. oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid and suberic acid: Also included are acids of the formula where x is zero or an integer, y is zero or an integer and x and y may be equal or different and R is defined as in (i). Examples of such acids include the alkyl or alkenyl succinic acids, 2-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-n-dodecylbutanedioic acid, 2-n-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, and 2-(p-methylphenyl)butanedioic acid. Also included are polysubstituted alkyl dicarboxylic acids wherein other R groups as described above may be substituted on the alkyl chain. These other groups may be substituted on the same carbon atom or different atoms. Such examples include 2,2-dimethylbutanedioic acid; 2,3-dimethylbutanedioic acid; 2,3,4-trimethylpentanedioic acid; 2,2,3-trimethylpentanedioic acid; and 2-ethyl-3-methylbutanedioic acid. The dicarboxylic acids also include acids of the formula: HOOC-(C r H 2r-2 )COOH where r is an integer of 2 or more. Examples include maleic acid, fumaric acid, pent-2-enedioic acid, hex-2-enedioic acid; hex-3-enedioic acid, 5-methylhex-2-enedioic acid; 2,3-di-methylpent-2-enedioic acid; 2-methylbut-2-enedioic acid; 2-dodecylbut-2-enedioic acid; and 2-polyisobutylbut-2-enedioic acid. The dicarboxylic acids also include aromatic dicarboxylic acids e.g. phthalic acid, isophthalic acid, terephthalic acid and substituted phthalic acids of the formula: where R is defined as in (i) and n = 1, 2, 3 or 4 and when n > 1 then the R groups may be the same or different. Examples of such acids include 3-methylbenzene-1,2-dicarboxylic acid; 4-phenylbenzene-1,3-dicarboxylic acid; 2-(1-propenyl)benzene-1,4-dicarboxylic acid, and 3,4-dimethylbenzene-1,2-dicarboxylic acid. The carboxylic acid anhydrides include the anhydrides that may be derived from the carboxylic acids described above. Also included are the anhydrides that may be derived from a mixture of any of the carboxylic acids described above. Specific examples include acetic anhydride, propionic anhydride, benzoic anhydride, maleic anhydride, succinic anhydride, dodecylsuccinic anhydride, dodecenylsuccinic anhydride, an optionally substituted polyisobutylenesuccinic anhydride, advantageously one having a molecular weight of between 500 and 2000 daltons, phthalic anhydride and 4-methylphthalic anhydride. The phenols from which the anion of the quaternary ammonium compound may be derived are of many different types. Examples of suitable phenols include: (i) Phenols of the formula: where n = 1, 2, 3, 4 or 5, where R²⁰ is defined below and when n > 1 then the substituents may be the same or different. R²⁰ may be hydrogen, or a substituted or unsubstituted, alkyl, cycloalkyl, alkenyl, cycloalkenyl or aryl group. The hydrocarbon group(s) may be bonded to the benzene ring by a keto or thio-keto group. Alternatively the hydrocarbon group(s) may be bonded through an oxygen, sulphur or nitrogen atom. Examples of such phenols include o-cresol; m-cresol; p-cresol; 2,3-dimethylphenol; 2,4-dimethylphenol; 2,3,4-trimethylphenol; 3-ethyl-2,4-dimethylphenol; 2,3,4,5-tetramethylphenol; 4-ethyl-2,3,5,6-tetramethylphenol; 2-ethylphenol; 3-ethylphenol; 4-ethylphenyl; 2-n-propylphenol; 2-isopropylphenol; 4-isopropylphenol; 4-n-butylphenol; 4-isobutylphenol; 4-secbutylphenol; 4-t-butylphenol; 4-nonylphenol; 2-dodecylphenol; 4-dodecylphenol; 4-octadecylphenol; 2-cyclohexylphenol; 4-cyclohexylphenol; 2-allylphenol; 4-allylphenol; 2-hydroxydiphenyl; 4-hydroxydiphenol; 4-methyl-4'-hydroxydiphenyl; o-methoxyphenol; p-methoxyphenol; p-phenoxyphenol; 2-hydroxydiphenylsulphide; 4-hydroxydiphenylsulphide; 4-hydroxyphenylmethylsulphide; and 4-hydroxyphenyldimethylamine. Also included are alkyl phenols where the alkyl group is obtained by polymerization of a low molecular weight olefin e.g. polypropylphenol or polyisobutylphenol. Also included are phenols of the formula: where R²⁰ and R²¹ which may be the same or different are as defined above for R²⁰ and m and n are integers and for each m or n greater than 1 each R²⁰ or R²¹ may be the same or different. Examples of such phenols include 2,2'-dihydroxy-5,5'-dimethyldiphenylmethane; 5,5'-dihydroxy-2,2'-dimethyldiphenylmethane; 4,4'-dihydroxy-2,2'-dimethyl-dimethyldiphenylmethane ; 2,2'-dihydroxy-5,5'-dinonyldiphenylmethane; 2,2'-dihydroxy-5,5'-didodecylphenylmethane 2,2',4,4'-tetra-t-butyl-3,3'-dihydroxy-5,5'-didodecylphenylmethane; and 2,2',4,4'-tetra-t-butyl-3,3'-dihydroxydiphenylmethane. Also included are sulphurized phenols of the formula: where R²⁰ and R²¹ which may be the same or different are as defined above, and m and n are integers, for each m and n greater than 1 each R²⁰ and R²¹ may be the same or different, and x is 1,2,3 or 4. Examples of such phenols include: 2,2'-dihydroxy-5,5'-dimethyldiphenylsulphide; 5,5'-dihydroxy-2,2'-di-t-butyldiphenyldisulphide; 4,4'-dihydroxy-3,3'-di-t-butyldiphenylsulphide; 2,2'-dihydroxy-5,5'-dinonyldiphenyldisulphide; 2,2'-dihydroxy-5,5'-didodecyldiphenyldisulphide; 2,2'-dihydroxy-5,5'didodecyldiphenyltrisulphide; and 2,2'-dihydroxy-5,5'-didodecyldiphenyltetrasulphide. The sulphonic acids from which the anion of the quaternary ammonium salt can be derived include alkyl and aryl sulphonic acids which have a total of 1 to 200 carbon atoms per molecule although the preferred range is 10-80 atoms per molecule. Included in this description are aryl sulphonic acids of the formula: where p = 1, 2, 3, 4, 5 and when p > 1 the substituents may be the same or different, and R²² may represent R²⁰ as defined above. The hydrocarbon group(s) may be bonded to the benzene ring through a carbonyl group or a thio-keto group. Alternatively the hydrocarbon group(s) may be bonded to the benzene ring through a sulphur, oxygen or nitrogen atom. Thus examples of sulphonic acids that may be used include: benzene sulphonic acid; o-toluenesulphonic acid, m-toluenesulphonic acid; p-toluenesulphonic acid; 2,3-dimethylbenzenesulphonic acid; 2,4-dimethylbenzenesulphonic acid; 2,3,4-trimethylbenzenesulphonic acid; 4-ethyl-2,3-dimethylbenzenesulphonic acid; 4-ethylbenzenesulphonic acid; 4-n-propylbenzenesulphonic acid; 4-n-butylbenzenesulphonic acid; 4-isobutylbenzenesulphonic acid; 4-sec-butylbenzenesulphonic acid; 4-t-butylbenzenesulphonic acid; 4-nonylbenzenesulphonic acid; 2-dodecylbenzenesulphonic acid; 4-dodecylbenzenesulphonic acid; 4-cyclohexylbenzenesulphonic acid; 2-cyclohexylbenzenesulphonic acid; 2-allylbenzenesulphonic acid; 2-phenylbenzenesulphonic acid; 4(4'-methylphenyl)benzenesulphonic acid; 4-methylmercaptobenzenesulphonic acid; 2-methoxybenzene sulphonic acid; 4-phenoxybenzenesulphonic acid; 4-methylaminobenzenesulphonic acid; 2-dimethylaminobenzenesulphonic acid; and 2-phenylaminobenzenesulphonic acid. Also included are sulphonic acids of the type listed above where R²² is derived from the polymerization of a low molecular weight olefin e.g. polypropylbenzenesulphonic acid and polyisobutylenebenzenesulphonic acid. Also included are sulphonic acids of the formula: R²³-SO₃H where R²³ is substituted or unsubstituted alkyl, cycloalkyl, alkenyl or cycloalkenyl. Examples of such sulphonic acids that may be used include methylsulphonic acid; ethylsulphonic acid; n-propylsulphonic acid; n-butylsulphonic acid; isobutylsulphonic acid; sec-butylsulphonic acid; t-butylsulphonic; nonylsulphonic acid; dodecylsulphonic acid; polypropylsulphonic acid; polyisobutylsulphonic acid; cyclohexylsulphonic acid; and 4-methylcyclohexylsulphonic acid. The quaternary ammonium salts may be made in two stages, the first stage of which comprises the reaction of a tertiary amine with an olefin oxide. Generally 1 mole of the tertiary amine is treated with A moles of the olefin oxide (where A is the number of tertiary nitrogens in the amine molecule) in the presence of an excess of water over that required by the stoichiometry of the reaction. Thus pyridine (1 mole) is treated with an olefin oxide (1 mole) in water (>1 mole). Triethylenediamine (1 mole) is treated with an olefin oxide (2 moles) in water (>2 mole). Hexamine (1 mole) is treated with an olefin oxide (4 moles) in water (>4 moles). However, the olefin oxide may be used in excess if required, or desired, the excess olefin oxide then reacting with the quaternary ammonium hydroxide. One possible mechanism for this further reaction with olefin oxide is illustrated by the equations: As indicated above any quantity of water may be used as long as it represents an excess over that required by the stoichiometry of the reaction. The reaction may be carried out in the following ways: (i) The amine is stirred with the olefin oxide in the reactor and the water added to the reaction mixture. The rate of addition of the water does not affect the quality of the final product but slow addition of water may be used to control an exothermic reaction. (ii) The amine is mixed with the water in the reactor and the olefin oxide is added to the stirred reaction mixture. The olefin oxide may be added as: (a) a gas either pure or diluted with an inert carrier (e.g., nitrogen) (b) a liquid (c) a solution in water (d) a solution in a water miscible organic solvent (e.g., methyl or ethyl alcohol). The rate of addition of the olefin oxide is not critical for the quality of the final product but a slow addition rate may be used to control an exothermic reaction. (iii) The olefin oxide is mixed with the water in the reactor and the amine is added to the reaction mixture. The amine may be added as: (a) a pure gas, liquid or solid (b) a solution in water (c) a solution in a water soluble organic solvent. As with the olefin oxide and water addition, slow addition of the amine may be used to control an exothermic reaction. To facilitate the reaction, the mixed reactants may be heated together at a given temperature while the third reactant is added at a rate sufficient to maintain a steady reaction. Alternatively the reactants may be heated in a pressure vessel but, when heating the reactants to promote the reaction, a temperature greater than 100°C should be avoided to prevent decomposition of the quaternary ammonium hydroxide. The second stage of the reaction comprises neutralization of the quaternary ammonium hydroxide formed in the first stage with the organic acid. Generally, sufficient acid is mixed with the solution obtained from the first stage to neutralize the quaternary ammonium hydroxide. However, an excess of acid may be used if required, as for example when only one carboxylic acid group of a polybasic acid is to be neutralized. The neutralization reaction may be carried out: (i) In the absence of any solvent. (ii) In the presence of an alcohol, e.g., methanol, ethanol, isopropanol, ethyl Cellosolve (a trademark), or ethylene glycol. (iii) In the presence of any other polar organic solvent, e.g., acetone, methyl ethyl ketone, chloroform, carbon tetrachloride, or symtetrachloroethane. (iv) In the presence of a hydrocarbon solvent, e.g., hexane, heptane, white spirit, benzene, toluene or xylene. (v) In the presence of a mixture of any of the above solvents. The neutralization reaction may be carried out at ambient temperature but generally an elevated temperature is used. When the reaction is completed the water and any solvents used may be removed by heating under vacuum. The product is generally diluted with mineral oil, diesel fuel, kerosene, or an inert hydrocarbon solvent to prevent the product being too viscous. The fuel composition advantageously comprises a minor proportion by weight of the quaternary ammonium compound, preferably less than 1% by weight, more preferably from 0.000001 to 0.1%, especially 2 to 200 ppm. The cracked component in the fuel oil which leads to the undesirable colour formation and sediment is generally obtained by cracking of heavy oil and may be fuel oil in which the main constituent is a fraction otained from a residual oil. Typical methods available for the thermal cracking are visbreaking and delayed coking. Alternatively the fuels may be obtained by catalytic cracking, the principal methods being moving-bed cracking and fluidized-bed cracking. After cracking, the distillate oil is extracted by normal or vacuum distillation, the boiling point of the distillate oil obtained usually being 60-500°C, and is a fraction called light-cycle oil, preferably corresponding to the boiling point range of light oil of 150-400°C. Compositions composed entirely of this fuel or fuels which are mixtures of the cracked fraction and normal distillates may be used in the present invention. The proportion by weight of direct-distillation fraction and cracked fraction in a fuel oil composition which is a mixture can vary considerably, but is usually 1:0.03 - 1:2 and preferably 1:0.05 - 1:1. Typically the content of cracked fraction is usually 5-97%, and preferably 10-50%, based on the weight of the composition. The present invention accordingly also provides a fuel oil composition comprising a distillate fraction and a cracked fraction and a quaternary ammonium compound the cation of which is the reaction product of a tertiary amine, an olefin oxide, and water, the anion being derived from an organic acid. The invention also provides the use of such a compound in inhibiting sediment and colour formation in a fuel oil composition, especially one containing a component obtained by the cracking of heavy oil. The fuel oil compositions of the present invention may contain other additives such as antioxidants, anticorrosion agents, fluidity improvers, agents absorbing ultraviolet radiation, detergents, dispersants and cetane improvers in small amounts (for example, usually less than 2% based on the weight of the composition). Details and examples of the synthesis of the quaternary ammonium compounds have been given in British Specification No. 1,445,993, the disclosure of which is incorporated by reference herein. The products were tested in a fuel that was a blend of a stable distillate (Fuel A), containing 50 ppm nitrogen and 0.24% sulphur, and an unhydrofined catalytically cracked gas oil (Fuel B) with 695 ppm nitrogen and 1.11% sulphur. The present invention is illustrated by the following examples. Table 1 shows the effect on sediment and colour in the AMS 77.061 test of blending different amounts of the straight distillate fuel with the unhydrofined catalytically cracked gas oil. Table 2 shows the nitrogen and sulphur contents of various fuels. Table 3 shows the effect on colour and sediment of doping the stable fuel (A) with compounds containing nitrogen and sulphur. Table 4 shows the effect on sediment and colour in the AMS 77.061 test of adding 100 ppm of quaternary ammonium compounds to a fuel containing 20% of cracked components. Comparison of the results for the fuels treated with quaternary ammonium compounds with the results for the untreated fuel show that the compounds of this invention control sediment and colour. Table 5 shows the long term storage characteristics of fuel to which has been added 100 ppm of quaternary ammonium compound. It can be seen that the sediment and colour of the treated fuel are much better in the long term than that of the untreated fuel. The Effect of Fuel Composition on Sediment and Colour in the AMS 77.061 Accelerated Stability Test Fuel A wt.% Fuel B wt.% Sediment mg/100 ml Colour 100 0 0.14 ± 0.09 ≈0.5,<0.5,<0.5 80 20 0.61 ± 0.13 ≈1.0, 1.0, 1.0 60 40 1.12 ± 0.10 ≈1.0,≈1.0,≈1.0,≈1.0 40 60 1.80 + 0.04 ≈2.0, ≈2.0 20 80 2.10 ± 0.10 ≈2.0, ≈2.0 0 100 2.90 6.0 The Nitrogen and Sulphur Contents of Various Fuels Type of Fuel Nitrogen (ppm) Sulphur (%) Unhydrofined CCGO 695 1.11 Unhydrofined CCGO 650 1.70 Straight distillate 50 0.24 Straight distillate 70 0.25 Straight distillate 97 0.23 Straight distillate 128 0.24 Straight distillate 179 1.44 Effect of doping with dimethyl pyrrole (DMP) and a sulphonic acid (SA) on the stability of a straight distillate fuel in the AMS 77.061 test DMP ppm SA ppm Sediment (mg/100 ml) Colour C Before After Nil Nil 0.06,0.10 <0.5 <1.0 0.5 Nil 50 0.02,0.00 <0.5 <1.5 1.0 <0.5 <1.5 1.0 50 Nil 0.76,0.59 <0.5 <1.0 0.5 <0.5 <1.0 0.5 50 50 1.06,1.01 <1.5 <3.0 1.5 <1.5 <3.0 1.5

Claims: A fuel oil composition comprising a diesel fuel oil or heating fuel oil and a quaternary ammonium salt the cation of which is the reaction product of a tertiary amine, an olefin oxide and water and the anion is derived from an organic acid, subject to the provisos that when the acid is an alkane monocarboxylic acid the alkane is a straight chain alkane, and that the anion is not derived from salicylic acid or ethosulphuric acid. A composition according to claim 1 containing a cracked component derived from a heavy oil, the cracked component advantageously comprising 5 to 97%, preferably 5 to 50%, by weight of the composition. A composition according to claim 1 or claim 2, wherein the tertiary amine has the formula R¹R²R³N where R¹, R² and R³, which may be the same or different, are each independently a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl group, each group advantageously having at most 20 carbon atoms. A composition according to claim 1 or claim 2, wherein the tertiary amine is a diamine of the formula R⁴R⁵N(CH₂) n NR⁶R⁷ where n is an integer of one or more and R⁴, R⁵, R⁶ and R⁷, which may be the same or different, are each independently an unsubstituted or substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl or aryl group. A composition according to any one of claims 1 to 4 wherein the tertiary amine is an alkylated alkylene polyamine of the formula: where m is an integer of one or more and R⁸, R⁹, R¹⁰, R¹¹ and R¹², which may be the same or different, are each independently a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl group. A composition according to claim 1 or claim 2, wherein the tertiary amine is pyridine or a substitued pyridine; an amine of the formula: where n is an integer of two or more, or is hexamethylene tetramine. A composition according to any one of the preceding claims wherein the olefin oxide has the formula: where R¹⁶, R¹⁷, R¹⁸ and R¹⁹, which may be the same or different, are each hydrogen or an unsubstituted or substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl or aryl group. A composition according to any one of the preceding claims wherein the anion of the salt is derived from a carboxylic acid or a carboxylic acid anhydride, advantageously an alkyl or alkenyl succinic acid or an anhydride thereof. A composition according to any one of claims 1 to 7, wherein the anion of the quaternary ammonium salt is derived from a phenol, advantageously a monoalkylphenol. A composition according to any one of claims 1 to 7, wherein the anion of the salt is derived from a methylene bis-phenol of the formula: or a sulphurized phenol of the formula: or where R²⁰ and R²¹ which may be the same or different are hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl group, m and n which may be the same or different are each zero or an integer from 1 to 4 and for each m or n greater than 1 each R²⁰ or R²¹ may be the same or different, and x is 1, 2, 3 or 4. A composition according to any one of claims 1 to 7, wherein the anion of the quaternary ammonium salt is derived from a sulphonic acid, advantageously one of the formula: where R²² is hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, or aryl group, p is an integer of 1 to 5 and when p is greater than 1 each R²² may be the same or different. A composition according to any one of the preceding claims which comprises a major proportion by weight of the diesel or heating fuel oil and a minor proportion by weight of the quaternary ammonium salt. A composition according to claim 12 which comprises 0.001 to 5.0% by weight of the quaternary ammonium salt. Use of a quaternary ammonium salt the cation of which is the reaction product of a tertiary amine, an olefin oxide, and water, the anion being derived from an organic acid, to inhibit colour and sediment formation caused by chemical oxidation of a sulphur or nitrogen compound in a fuel oil. The use as claimed in claim 14, wherein the fuel oil comprises a distillate fraction and a cracked fraction.

Inventors: SEXTON MICHAEL DAVID, SEXTON, MICHAEL DAVID
Applicants: EXXON CHEMICAL PATENTS INC, EXXON CHEMICAL PATENTS INC.
Application year: 1990
Main classification: C10L1
IPC codes: F02B3, C10L1