DE69004692T2 - Hydrocarbon compositions and additives therefor. - Google Patents

Description

This invention relates to liquid fuel compositions having improved performance characteristics, particularly with regard to combustion characteristics.

Certain organometallic compounds have been found to be effective as combustion improvers for distillate fuels such as domestic heating oils and the like. For example, U.S. Patent No. 3,112,789 describes the use of cyclopentadienyl manganese tricarbonyls for this purpose and the compound methylcyclopentadienyl manganese tricarbonyl (MMT) has been sold as a solution in a hydrocarbon diluent as a combustion improver for distillate fuels of this type. Bis(cyclopentadienyl) iron has also been introduced and sold as a combustion improver for use in such fuels.

Keszthelyi et al. in Period. Polytech., Chem. Eng., Vol. 21(1), pp. 79-97 (1977) report that during combustion of light fuel oils in vaporizing burners, 0.025% cyclopentadienyl manganese tricarbonyl was effective in reducing soot formation. In Margantsevye Antidetonatory, edited by A.N. Nesmeyanov, Nauka, Moscow, 1971, pp. 192-199, Makhov et al. report a test run showing that the addition of cyclopentadienyl manganese tricarbonyl to diesel fuel reduces the amount of exhaust smoke.

Zubarev et al. in Rybn. Khoz. (Moscow), Vol. 9, pp. 52-54, (1977), report test results on the addition of cyclopentadienyl manganese tricarbonyl (CMT) alone or in a mixture containing "a scavenger and a solvent" to a fuel mixture of diesel fuel and residual marine fuel. It is shown that CMT alone reduces carbon deposits on the intake valves, but not on other surfaces of the engine, and that it reduces smoke The CMT mixture ("Ts8") is reported to be more effective in reducing carbon deposits, particularly on the intake valves, cylinder head and piston head.

Canadian Patent No. 1,188,891 describes an additive for fuel oils, diesel fuels and other liquid fuels and motor fuels designed to improve combustion, reduce soot formation and improve storage stability. Such an additive is composed of at least one oil-soluble or oil-dispersible organic compound of a transition metal or an alkaline earth metal, and at least one hydrocarbon oxidation and polymerization inhibitor stable at temperatures of at least 300 ºC. According to the patentee, the presence of transition metal compounds in such fuels, such as copper, manganese, cobalt, nickel and iron, accelerates the deterioration of fuels in accelerated stability tests conducted at 149 ºC in the presence of air. Such compounds as MMT, ferrocene, copper naphthenate, iron naphthenate and manganese naphthenate are indicated to cause such deterioration in the absence of high temperature (e.g. 300 ºC) stabilizers such as heat stable alkylphenols, amines, aminophenols, dithiophosphates, dithiocarbamates and imidazoles, as well as inorganic inhibitors in the form of oxides or hydroxides of aluminum, magnesium or silicon. EP 0 078 249 BI deals with the same general effect and shows that the additive can be a combination of a transition metal compound and an alkaline earth metal compound, as well as each of these compounds separately.

British Patent No. 1 413 323 describes a multi-component additive for diesel fuels to prevent or reduce the formation of deposits on internal parts. The additive comprises, inter alia, an ester of oleic or naphthenic acid having an acid number of less than 200; a naphthenic acid ester of cresol; an alkoxyalkyl ester of an aliphatic carboxylic acid; an organometallic tricarbonyl cyclopentadiene compound, such as cyclopentadienyl manganese tricarbonyl; an amide derivative of a polyolefin obtained by reacting a polyolefin-substituted succinic acid or succinic anhydride with a polyamine; a copolymer of ethylene and a vinyl ester (or hydrocarbon-substituted vinyl ester) of a carboxylic acid, the copolymer having a number average molecular weight of more than 3,000; an odorant composed of a mixture of natural and synthetic alcohols, ketones and ethers; kerosene and a petroleum distillate.

U.S. Patent No. 4,505,718 describes compositions comprising the combination of a transition metal, such as a manganese carboxylate, and an ashless, hydrocarbon-soluble dispersant. An optimal balance between beneficial and deleterious effects is said to have been achieved in oils of lubricating viscosity and hydrocarbon fuels.

U.S. Patent No. 3,883,320 discloses an additive for improving the combustion of a jet fuel composition comprising an oil-soluble compound of magnesium, calcium or barium and an oil-soluble ammonium salt.

A need has arisen for a fuel-soluble additive composition for hydrocarbon fuels which can not only reduce the amount of soot, smoke and/or carbonaceous products produced during combustion of the fuel, but also reduce the acidity of the carbonaceous products resulting from such combustion. In meeting this need, it is also important to provide an additive which prevents or at least inhibits the deposition of sludge on critical engine or combustor parts or surfaces and which provides fuel compositions with satisfactory physical properties such as thermal stability and storage stability. Likewise, it is highly desirable to provide an additive composition which reduces the amount of harmful emissions (e.g., carbon monoxide, unburned hydrocarbons, polyaromatic hydrocarbons and/or suspended particles) produced when fuels are used in an engine, combustor or similar combustion devices. The provision of additive compositions that can reduce fuel consumption is also a highly desirable objective.

In accordance with one of its embodiments, this invention provides an additive composition for hydrocarbon fuels. Such additive composition comprises

a> one or more fuel-soluble manganese carbonyl compounds;

b) one or more fuel-soluble detergents containing alkali or alkaline earth metals - e.g. one or more neutral or basic alkali or alkaline earth metal salts of at least one sulphonic acid and/or at least one carboxylic acid and/or at least one salicylic acid and/or at least one alkylphenol and/or at least one sulphurised alkylphenol and/or at least one organic phosphoric acid containing at least one carbon-phosphorus bond; and

(c) one or more fuel-soluble, ashless dispersants.

Consequently, the additive compositions are composed of three different types of essential or indispensable ingredients, namely components a), b) and c).

In another of its embodiments, this invention provides a fuel composition containing a major amount of a liquid hydrocarbon fuel containing a minor combustion enhancing amount of the just described components a), b) and c).

According to preferred embodiments of this invention, the additive compositions and fuel compositions are essentially halogen-free, that is, they contain no more than 10 ppm halogens, if any.

Preferred manganese carbonyl compounds - in the above component a) - are cyclopentadienyl manganese tricarbonyl compounds. The preferred salts of component b) are the sodium, potassium, calcium and magnesium salts of sulfonic acids, of alkylphenols, of sulfurized alkylphenols and of carboxylic acids, in particular of aromatic carboxylic acids. Preferred ashless dispersants for use as component c) are basic, nitrogen-containing, ashless dispersants, in particular polyolefin-substituted succinimides of polyethylene polyamines, such as polyethylene tetramines, polyethylene pentamines or polyethylene hexamines.

Particularly preferred compositions for use in heating gas oils or similar burner fuels contain, in addition to the above components a), b) and c), one or more of the following components:

(d) at least one fuel-soluble demulsifier;

e) at least one aliphatic or cycloaliphatic amine; and

f) at least one metal deactivator.

Particularly preferred compositions for use in diesel fuel for road transport and similar middle distillate fuels contain, in addition to the above components a), b) and c), the components d), namely at least one fuel-soluble demulsifier.

The above and other embodiments of the invention will become apparent from the following description and the appended claims.

As used herein, the term "fuel soluble" means that the compound or component discussed has sufficient solubility in the hydrocarbon fuel in which it is to be used at ordinary ambient temperature to provide a homogeneous solution containing the compound or component in at least the lowest concentration of the concentration range listed herein for such compound or component.

Manganese carbonyl compounds.

The manganese compounds - component a) - of the compositions according to the invention are characterized in that they are soluble in fuel and have at least one carbonyl group which is bonded to a manganese atom.

The most desirable general type of manganese carbonyl compounds used in accordance with this invention comprises organomanganese polycarbonyl compounds. For best results, a cyclopentadienyl manganese tricarbonyl compound of the type described in U.S. Patent Nos. 2,818,417 and 3,127,351 should be used.

Thus, compounds such as cyclopentadienyl-manganesetricarbonyl, methylcyclopentadienyl-manganesetricarbonyl, ethylcyclopentadienyl-manganesetricarbonyl, dimethylcyclopentadienyl-manganesetricarbonyl, trimethylcyclopentadienyl-manganesetricarbonyl, propylcyclopentadienyl-manganesetricarbonyl, isopropylcyclopentadienyl-manganesetricarbonyl, butylcyclopentadienyl-manganesetricarbonyl, pentylcyclopentadienyl-manganesetricarbonyl, hexylcyclopentadienyl-manganesetricarbonyl, ethylmethyl-cyclopentadienyl-manganesetricarbonyl, dimethyloctylcyclopentadienyl-manganesetricarbonyl, dodecyl-cyclopentadienyl-manganesetricarbonyl, indenyl-manganesetricarbonyl and similar compounds in which the cyclopentadienyl moiety has up to about 18 carbon atoms contains.

A preferred organomanganese compound is cyclopentadienyl manganese tricarbonyl. Particularly preferred for use in the practice of this invention is methylcyclopentadienyl manganese tricarbonyl.

Methods for the preparation of cyclopentadienyl manganese tricarbonyls are well documented in the literature. For example, in addition to the above-listed U.S. Patents Nos. 2,818,417 and 3,127,351, among others, U.S. Patents Nos. 2,868,816, 2,898,354, 2,960,514, and 2,987,529.

Other less preferred organometallic compounds that may be used include the nonionic diamine manganese tricarbonyl halide compounds such as bromomanganese dianiline tricarbonyl and bromomanganese dipyridine tricarbonyl described in U.S. Patent 2,902,489; the acyl manganese tricarbonyls such as methylacetyl cyclopentadienyl manganese tricarbonyl and benzoylmethyl cyclopentadienyl manganese tricarbonyl described in U.S. Patent 2,959,604; the aryl manganese pentacarbonyls such as phenyl manganese pentacarbonyl described in U.S. Patent 3,007,953; and the aromatic cyanomanganese dicarbonyls such as mesitylene cyanomanganese Dicarbonyl, which is described in U.S. Patent 3,042,693. Cyclopentadienyl manganese dicarbonyl compounds of the formula RMn(CO)2L, where R represents a substituted or unsubstituted cyclopentadienyl group having 5 to 18 carbon atoms, and L represents a ligand such as an olefin, an amine, a phosphine, tetrahydrofuran or the like, may also be used. Such compounds are referred to, for example, in Herberhold, M., Metal π-Complexes, Vol 11, Amsterdam, Elsevier, 1967 or in Giordano, PJ and Weighton, MS, Inorg. Chem., 1977, 16, 160. If desired, the dimer of manganese pentacarbonyl (dimanganese decacarbonyl) may also be used.

Metal-containing detergents.

Examples of the metal-containing detergents are oil-soluble neutral and basic salts of alkali or alkaline earth metals with one or more of the following acidic substances (or mixtures thereof): (1) sulfonic acids, (2) carboxylic acids, (3) salicylic acids, (4) alkylphenols, (5) sulfurized alkylphenols, (6) organic phosphoric acids characterized by having at least one direct carbon-phosphorus bond. Such organic phosphoric acids include those prepared by treating an olefin polymer (e.g., polyisobutylene having a molecular weight of 1000) with a phosphorylating agent, such as phosphorus trichloride, phosphorus heptasulfide, phosphorus pentasulfide, phosphorus trichloride and sulfur, white phosphorus and a sulfur halide, or thiophosphoryl chloride. The most commonly used salts of such acids are sodium, potassium, lithium, calcium, magnesium, strontium and barium salts.

The term "basic salt" is used to designate metal salts in which the metal is present in larger stoichiometric amounts than the organic acid residue. The processes commonly used to prepare the basic salts comprise heating a mineral oil solution of an acid with a stoichiometric excess of a metal neutralizing agent, such as the metal oxides, hydroxides, carbonates, bicarbonates or sulfides, at a temperature above 50 ºC and filtering the resulting Mass. The use of a "promoter" in the neutralization step to assist in the incorporation of a large excess of metal is also known. Examples of substances suitable as a promoter include phenolic substances such as phenol, naphthol, alkylphenol, thiophenol, sulfurized alkylphenol and condensation products of formaldehyde with a phenolic substance; alcohols such as methanol, 2-propanol, octyl alcohol, cellosolve, carbitol, ethylene glycol, stearyl alcohol and cyclohexyl alcohol; and amines such as aniline, phenylenediamine, phenothiazine, phenyl-beta-naphthylamine and dodecylamine. A particularly effective method for preparing the basic salts comprises mixing an acid with an excess of a basic alkaline earth metal neutralizing agent and at least one alcohol promoter and carbonating the mixture at an elevated temperature, such as 60-200°C.

Examples of suitable metal-containing detergents include, but are not limited to, substances such as lithium phenolates, sodium phenolates, potassium phenolates, calcium phenolates, magnesium phenolates, sulfurized lithium phenolates, sulfurized sodium phenolates, sulfurized potassium phenolates, sulfurized calcium phenolates, and sulfurized magnesium phenolates, in which each aromatic group has one or more aliphatic groups to provide solubility in hydrocarbons; the basic salts of any of the foregoing phenols or sulfurized phenols (often referred to as "overbased phenols" or "overbased sulfurized phenols"); lithium sulfonates, sodium sulfonates, potassium sulfonates, calcium sulfonates, and magnesium sulfonates, in which each sulfonic acid moiety is attached to an aromatic nucleus which in turn usually contains one or more aliphatic substituents to provide solubility in hydrocarbons; the basic salts of any of the foregoing sulfonates (often referred to as "overbased sulfonates"); lithium salicylates, sodium salicylates, potassium salicylates, calcium salicylates and magnesium salicylates in which the aromatic moiety is normally substituted with one or more aliphatic substituents to provide solubility in hydrocarbons to ensure the effectiveness of the carboxylic acid; the basic salts of any of the foregoing salicylates (often referred to as "overbased salicylates"); the lithium, sodium, potassium, calcium and magnesium salts of hydrolyzed, phosphosulfurized olefins having 10 to 2000 carbon atoms or hydrolyzed, phosphosulfurized alcohols and/or aliphatic-substituted phenolic compounds having 10 to 2000 carbon atoms; lithium, sodium, potassium, calcium and magnesium salts of aliphatic carboxylic acids and aliphatic-substituted cycloaliphatic carboxylic acids; the basic salts of the foregoing carboxylic acids (often referred to as "overbased carboxylates") and many other similar alkali or alkaline earth metal salts of oil-soluble organic compounds. Salt mixtures of two or more different alkali and/or alkaline earth metals may be used. Mixtures of salts of two or more different acids or two or more different types of acids may also be used (e.g. one or more calcium phenolates with one or more calcium sulfonates). Although rubidium, cesium and strontium salts are suitable, their cost makes them unsuitable for most applications. Likewise, from a toxicological point of view, the status of barium as a heavy metal means that the barium salts, although effective, are not preferred for current use.

Ashless dispersants Ashless dispersants have been described in numerous patent applications, mainly as additives for use in lubricating compositions, but their use in hydrocarbon fuels has also been described. Ashless dispersants leave little or no metal-containing residues when combusted. They generally contain only carbon, hydrogen, oxygen and, in most cases, nitrogen, but in some cases they also contain other non-metallic elements, such as phosphorus, sulfur or boron.

The preferred ashless dispersant is an alkenyl succinic acid of an amine containing at least one primary amino group capable of forming an imide group. Typical examples are given in U.S. Patent Nos. 3,172,892, 3,202,678, 3,216,936, 3,219,666, 3,254,025, 3,272,746 and 4,234,435. The alkenyl succinimides can be prepared by conventional methods such as by heating an alkenyl succinic anhydride, succinic acid, succinic ester, succinic halide or lower alkyl ester with an amine containing at least one primary amino group. The alkenyl succinic anhydride can be readily prepared by heating a mixture of olefin and maleic anhydride to 180-220°C. The olefin is preferably a polymer or copolymer of a lower monoolefin such as ethylene, propylene and isobutene. The more preferred source of an alkenyl group is polyisobutene having a molecular weight of up to 10,000 or more. In an even more preferred embodiment, the alkenyl group is a polyisobutene group having a molecular weight of 500-5000, preferably 900-2000 and especially 900-1200.

Amines that can be used in the formation of ashless dispersants include any that have at least one primary amino group that can react to form an imide group. Some typical examples are: methylamine, 2-ethylhexylamine, n-dodecylamine, stearylamine, N,N-dimethylpropanediamine, N-(3-aminopropyl)morpholine, n-dodecylpropanediamine, N-aminopropylpiperazine, ethanolamine and N-ethanolethylenediamine.

The preferred amines are the alkylenepolyamines, such as propylenediamine, dipropylenetriamine, di-(1,2-butylene)triamine and tetra-(1,2-propylene)pentamine.

The most preferred amines are the ethylenepolyamines, which are represented by the formula

H₂N(CH₂CH₂NH)nH

where n is an integer from one to ten. These include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine, including mixtures thereof, in which case n is the average value of the mixture. These ethylenepolyamines have each end and can thus form monoalkenylsuccinimides and bisalkenylsuccinimides. Commercially available ethylenepolyamines normally contain minor amounts of branched and cyclic amines such as N-aminoethylpiperazine, N,N'-bis(aminoethyl)piperazine and N,N'-bis(piperazyl)ethane. The preferred commercial mixtures have total compositions approximately in the range of diethylenetriamine to tetraethylenepentamine, mixtures generally corresponding in total composition to tetraethylenepentamine being most preferred.

Thus, the most preferred ashless dispersants for use in the present invention are the products of the reaction of a polyethylene polyamine, e.g. triethylenetetramine or tetraethylenepentamine, with a hydrocarbon-substituted carboxylic acid or anhydride obtained by reacting a polyolefin, preferably polyisobutene having a number average molecular weight of 500-5000, preferably 900-2000 and especially 900-1200, with an unsaturated polycarboxylic acid or anhydride, e.g. maleic anhydride, maleic anhydride and fumaric anhydride, including mixtures of two or more such substances.

Another class of suitable ashless dispergants includes alkenyl succinic acid esters and diesters of alcohols containing 1-20 carbon atoms and 1-6 hydroxyl groups. Typical examples are described in U.S. Patent Nos. 3,331,776, 3,381,022 and 3,522,179. The alkenyl succinic acid portion of these esters corresponds to the alkenyl succinic acid portion of the succinimides described above, including the same preferred and most preferred subgroups, e.g., polyisobutenyl succinic acids in which the polyisobutenyl group has a number average molecular weight of 500-5000, preferably 900-2000 and especially 900-1200.

Alcohols suitable for the production of esters include methanol, ethanol, isobutanol, octadecanol, eicosanol, ethylene glycol, diethylene glycol, tetraethylene glycol, diethylene glycol monoethyl ester, propylene glycol, tripropylene glycol, Glycerin, sorbitol, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, pentaerythritol and dipentaerythritol.

The succinic esters are prepared simply by simply heating a mixture of alkenyl succinic acids, anhydrides or lower alkyl (e.g. C1-C4) esters with the alcohol while distilling off the water or lower alcohol. In the case of acid esters, less alcohol is used. In fact, no water is evolved in acid esters prepared from alkenyl succinic anhydrides. In another method, the alkenyl succinic acid or anhydride may simply be reacted with a suitable alkylene oxide such as ethylene oxide, propylene oxide and the like, including mixtures thereof.

In another embodiment, the ashless dispersant is an alkenyl succinic ester-amide mixture. This can be prepared by heating the above-described alkenyl succinic acids, anhydrides or lower alkyl esters with an alcohol and an amine, either sequentially or in a mixture. The alcohols and amines described above are also suitable for this embodiment. Alternatively, amino alcohols can be used alone or together with the alcohol and/or amine to produce the ester-amide mixture. The amino alcohol can contain 1-20 carbon atoms, 1-6 hydroxy groups and 1-4 amine nitrogen atoms. Examples are ethanolamine, diethanolamine, N-ethanoldiethylenetriamine and trimethylolaminomethane.

Typical examples of suitable ester-amide mixtures are described in US Patent Nos. 3,184,474, 3,576,743, 3,632,511, 3,804,763, 3,836,471, 3,862,981, 3,936,480, 3,948,800, 3,950,341, 3,957,854, 3,957,855, 3,991,098, 4,071,548 and 4,173,540.

Such ash-free dispersants containing alkenylsuccinic acid residues can, as is widely known, be subsequently reacted with boron compounds, phosphorus derivatives and/or carboxylic acid acylating agents, e.g. maleic anhydride.

Another suitable class of ashless dispersants includes the Mannich condensates of hydrocarbon-substituted Phenols, formaldehyde or formaldehyde precursors (e.g. paraformaldehyde) and an amine containing at least one primary amine group, 1-10 amine groups and 1-20 carbon atoms. Mannich condensates suitable for this invention are described in U.S. Patent Nos. 3,442,808, 3,448,047, 3,539,633, 3,591,598, 3,600,372, 3,634,515, 3,697,574, 3,703,536, 3,704,308, 3,725,480, 3,726,882, 3,736,357, 3,751,365, 3,756,953, 3,793,202, 3,798,165, 3,798,247, 3,803,039, and 3,413,347.

More preferred Mannich condensates are prepared by condensing polyisobutylene phenol having an average molecular weight of the polyisobutylene group of about 800-3000 with formaldehyde or a formaldehyde precursor and an ethylene polyamine of the formula

H₂N(CH₂CH₂NH)nH

where n is an integer from one to ten, or mixtures thereof, in particular the mixtures with an average value for n of 3-5.

Typical post-treated ashless dispersants, such as succinimides and Mannich condensates, are described in U.S. Patent Nos. 3,036,003, 3,087,936, 3,200,017, 3,216,936, 3,254,025, 3,256,185; 3 278 550, 3 280 234, 3 281 428, 3 282 955, 3 312 619, 3 366 569, 3 367 943, 3 373 111, 3 403 102, 3 442 808, 3 455 831, 3 455 832, 3 493 520, 3 502 677, 3 513 093, 3 533 945, 3 539 633, 3 573 010, 3 579 450, 3 591 598, 3 600 372, 3 639 242, 3 649 229, 3 649 659, 3 658 846, 3 697 574, 3 702 575, 3 703 536, 3 704 308, 3 708 422 and 4 857 214.

Another type of ashless dispersants that can be used include interpolymers of oil-soluble monomers such as methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar groups, e.g., aminoalkyl acrylates or acrylamides and poly(oxyethylene) substituted acrylates. These can be characterized as "polymeric dispersants" and examples of these are disclosed in the following U.S. Patents: Nos. 3,329,658, 3,449,250, 3,519,565, ?565, 3,666,730, 3,687,849 and 3,702,300.

Another class of ashless dispersants which can be advantageously used in fuel compositions according to the invention are imidazoline dispersants represented by the formula

where R₁ is a hydrocarbon group having 1 to 30 carbon atoms, e.g. an alkyl or alkenyl group having 7 to 22 carbon atoms, and R₂ is a hydrogen atom, a hydrocarbon radical having 1 to 22 carbon atoms, or an aminoalkyl, acylaminoalkyl or hydroxyalkyl radical having 2 to 50 carbon atoms. Such long-chain alkyl (or long-chain alkenyl) imidazoline compounds can be prepared by reacting a corresponding long-chain fatty acid (of the formula R₁-COOH), for example oleic acid, with a suitable polyamine. The imidazoline produced is then usually called, for example, oleyl imidazoline, where the radical R₁ is the oleyl radical of oleic acid. Other suitable substituents in the 2-position of these imidazolines include undecyl, heptadecyl, lauryl and erucyl radicals. Suitable N-substituents of these imidazolines (e.g. radicals R₂) include hydrocarbon groups, hydroxyalkyl groups, aminoalkyl groups and acylaminealkyl groups. Examples of the above groups are methyl, butyl, decyl, cyclohexyl, phenyl, benzyl, toluoyl, hydroxyethyl, aminoethyl, oleyl-aminoethyl and stearylaminoethyl groups.

Other suitable ashless dispersants that can be added to the fuel compositions of the invention include the condensation products of a cyclic anhydride with a straight-chain N-alkylpolyamine of the formula

R-(NH-R'-)n-NH2

where n is an integer at least equal to 1, normally 3 to 5, R is a saturated or unsaturated, linear hydrocarbon radical having 10 to 22 carbon atoms and R' is a divalent alkylene or alkylidene radical having 1 to 6 carbon atoms. Examples of such polyamines are N-oleyl-1,3-propanediamine, N-stearyl-1,3-propanediamine, N-oleyl-1,3-butanediamine, N-oleyl-2-methyl-1,3-propanediamine, N-oleyl-1,3-pentanediamine, N-oleyl-2-ethyl-1,3-propanediamine, N-stearyl-1,3-butanediamine, N-stearyl-2-methyl-1,3-propanediamine, N-stearyl-1,3-pentanediamine, N-stearyl-2-ethyl-1,3-propanediamine, N-oleyldipropylenetriamine and N-stearyldipropylenetriamine. Such linear N-alkylpolyamines are condensed with, for example, a succinic, maleic, phthalic or hexahydrophthalic anhydride, which can be substituted by one or more radicals each containing up to 5 carbon atoms.

Another class of ashless dispersants that can be added to the compositions of the present invention are the reaction products of an ethoxylated amine, prepared by reacting ammonia with ethylene oxide, and a carboxylic acid having 8 to 30 carbon atoms. The ethoxylated amine can be, for example, mono-, di- or triethanolamine or a polyethoxylated derivative thereof and the carboxylic acid can be, for example, a straight or branched chain fatty acid having 10 to 22 carbon atoms, a naphthenic acid, a resin acid or an alkylarylcarboxylic acid.

Yet another type of ashless dispersants which may be used in the practice of the invention are the olefin-maleimide copolymers, such as those described in U.S. Patent No. 3,909,215. Such copolymers are alternating copolymers of N-substituted maleimides and aliphatic alpha-olefins having from 8 to 30 carbon atoms. The copolymers have an average of from 4 to 20 maleimide groups per molecule. The substituents on the nitrogen atom of the maleimide may be the same or different and are organic radicals composed essentially of carbon, hydrogen and nitrogen and consisting of from 3 to 60 carbon atoms in total. A commercially available material which is highly suitable for use in this invention is Chevron OFA 42 SB. This material is believed to be an α-olefin maleimide of the type described in U.S. Patent No. 3,909,215 or Whatever its composition, it works quite well.

All of the above types of ashless dispersants are described in the literature and many are commercially available. Mixtures of different types of ashless dispersants can of course be used.

Due to environmental concerns, it is desirable to use ashless dispersants that contain few, if any, halogen atoms, such as chlorine. Thus, to meet such concerns, it is desirable (although not required from a performance standpoint) to select ashless dispersants (as well as the other components used in the compositions of the invention) so that the total halogen content of the fuel composition does not exceed 10 ppm overall. In fact, the less the better. It is most desirable that the additive composition contain no detectable amounts of halogens.

Typical halogen (chlorine)-free, ashless dispersants suitable for use in the compositions of the present invention include, in addition to the various types described above, those described in the recently published applications WO 9003359 and EP 365288.

Demulsifiers.

A number of materials are available for use in these preferred embodiments of this invention in which at least one demulsifier is used as component d) together with components a), b) and c). The demulsifier improves the water tolerance level of the fuel composition by minimizing or preventing excessive emulsion formation.

Exemplary demulsifiers that can be used in the practice of this invention include poly(alkylphenol)formaldehyde condensates and the polyalkyleneoxy modified reaction products thereof. These compounds are prepared by reacting an alkylphenol with formaldehyde and then reacting the above reaction product with a C₂ to C₆-alkylene oxide, such as ethylene oxide and propylene oxide. The demulsifiers have the generalized structural formula

in which U represents an alkylene group having 2 to 6 carbon atoms, y is an integer having an average value between 4 and 10; x is an integer having an average value between 4 and 10; and R₅ represents an alkyl group having 4 to 15 carbon atoms.

Preferred demulsifiers described by the above formula are methylene-bridged polyethyleneoxy-modified poly(alkylphenol) polymers having a polyethyleneoxy chain of 8 to 20 carbon atoms, preferably 6 to 12 carbon atoms, and having at least 75% of the polyethyleneoxy chains within the range listed. The methylene-bridged poly(alkylphenol) portion of the polymer has 4 to 10, preferably 5 to 8, repeating methylene-bridged alkylphenol units of 4 to 15, preferably 6 to 12 carbon atoms in the alkyl group. In preferred embodiments, the alkyl groups are present as a mixture of alkyl groups of between 4 and 12 carbon atoms.

Illustrative alkylphenols include p-isobutylphenol, p-diisobutylphenol, p-hexylphenol, p-heptylphenol, p-octylphenol, p-tripropylenephenol, and p-dipropylenephenol.

Another type of demulsifier component is a sulfonated alkylphenol neutralized with ammonia. These compounds have the general structure:

wherein R₁ represents a hydrocarbon group having 4 to 15, preferably 6 to 12 carbon atoms.

These compounds are prepared by sulfonation of an alkylated phenol and subsequent neutralization of the sulfonated product with ammonia.

Another type of demulsifier is an oxyalkylated glycol. These compounds are made by reacting a polyhydroxy alcohol, such as ethylene glycol, trimethylene glycol, etc., with ethylene or propylene oxide. Many of the products are commercially available from BASF-Wyandotte Chemical Corporation under the trade name PLURONIC. These are polyethers terminated in hydroxy groups and are made by block copolymerization of ethylene oxide and propylene oxide. The ethylene oxide blocks serve as hydrophilic blocks and the propylene oxide blocks serve as hydrophobic blocks. They are available in a wide molecular weight range and with different ratios of ethylene oxide to propylene oxide.

One type of commercially available demulsifier comprises a mixture of alkylaryl sulfonates, polyoxyalkylene glycols and oxyalkylated alkylphenol resins. Such products are supplied by Petrolite Corporation under the trade name TOLAD. One such proprietary product, identified as TOLAD 286K, is said to be a mixture of these components dissolved in a solvent composed of alkylbenzenes. This product has been found to be effective for use in the compositions of the invention. A related product, TOLAD 286, is also suitable. In this case, the product apparently contains the same type of active ingredients found in a solvent composed of aromatic naphtha and isopropanol. However, other known demulsifiers can be used.

Aliphatic or cycloaliphatic amines.

A wide range of suitable amines are available for the embodiments of this invention in which component e) is used. This component contributes to the stability of the systems in which it is used. Typically component e> is a monoamine, but polyamines can also be used if desired. The vast array of suitable amines includes the amines referred to in US Patent No. 3,909,215, such as primary amines containing tertiary alkyl radicals, including Primene 81R, as well as amines referred to in EP 188 042, namely alkyldimethylamines in which the alkyl group contains 8 to 14 carbon atoms, or mixtures thereof. Likewise suitable are the mixed alkyl-cycloalkylamines, such as N-cyclohexyl-N-butylamine and N-methylcyclohexyl-N-octylamine, as well as the di- and tricycloalkylamines, such as N,N-dicyclohexylamine, N,N-di-(ethylcyclohexyl)amine and N,N,N-tricyclohexylamine. Preferred amines include N-cycloalkyl-N,N-dialkylamines and N-cycloalkenyl-N,N-dialkylamines, such as N-cyclohexyl-N,N-diethylamine, N-cyclohexyl-N,N-dibutylamine, N-cycloheptyl-N,N-dimethylamine, N-cyclooctyl-N,N-dilaurylamine and N-cyclohexenyl-N,N-dipropylamine. N-cyclohexyl-N,N-dimethylamine is particularly preferred. Mixtures of different amines, such as those listed above, are also suitable for use according to the invention.

Metal deactivators.

Generally, metal deactivators are divided into two major classes. One class includes the passivators, which are believed to react with the metal surface and thereby passivate the surface. The other class includes the chelators, ie substances that react or complex with dissolved metals and/or metal ions. An example of the passivator type are the thiadiazoles, such as the HITEC 314 additive (Ethyl Petroleum Additives, Ltd., Ethyl Petroleum Additives, Inc.). Examples of the chelator type of metal deactivators include 8-hydroxyquinoline, ethylenediaminetetracarboxylic acid, and β-diketones such as acetylacetone, β-ketoesters such as octylacetoacetate (?octyl acetoacetate). The preferred metal deactivators generally considered to be chelators are Schiff bases such as N,N'-disalicylidene-1,2-ethanediamine, N,N'-disalicylidene-1,2-propanediamine, N,N'-disalicylidene-1,2-cyclohexanediamine and N,N"-disalicylidene-N'-methyl-dipropyltriamine. Thus, a whole range of known metal deactivators are available for use as component f) in the embodiments of the invention involving the use of metal deactivators.

A particular advantage associated with the use of the metal deactivators, particularly the Schiff bases as a chelator type, is their ability to overcome instability caused in certain hydrocarbon-based fuels by the presence of typical manganese carbonyl compounds, such as the cyclopentadienyl manganese tricarbonyls, in combination with typical metal detergents. The most preferred metal deactivators of this type are N,N'-disalicylidene-1,2-alkanediamines and N,N'-D-salicylidene-1,2-cycloalkanediamines, particularly N,N'-disalicylidene-1,2-propanediamine. Metal deactivator mixtures can be used.

Hydrocarbon fuels.

As such, the advantages of this invention can be achieved in any liquid hydrocarbon fuel derived from petroleum, coal, shale and/or tar sands. In most cases, at least under the present circumstances, the fuel base will be primarily, though not exclusively, petroleum.

The invention is therefore applicable to such fuels as kerosene, jet fuel, aviation fuel, diesel fuel, domestic heating oil, light circulating oil, heavy circulating oil, light diesel oil, heavy diesel oil, bunker oils, residual heating oils, ultra-heavy heating oils and generally to liquid (or flowable) hydrocarbon products suitable for combustion in either an engine (e.g. diesel fuel and gas turbine fuels) and in a burner apparatus (e.g. gas oils, heavy fuel oils for land systems, residual fuel oils, viscometer fuel oils and domestic fuel oils). Other suitable fuels may include liquid fuels derived from biomass such as vegetable oils (e.g. rapeseed oil, jojoba oil and cottonseed oil), liquid fuels derived from waste such as fuels derived from municipal and/or industrial waste products, waste oils and/or liquid biomass waste and their derivatives or mixtures of any of the foregoing.

In many cases there are different specifications for different hydrocarbon fuels or their classes and in any case the nature and character of such fuels is widely known and reported in the literature.

Additional compositions comprising components a), b), c) and at least one of components d), e) and f) - preferably two of components d), e) and f), and most preferably all three components d), e) and f) - are particularly suitable for heating gas oils, similar burner fuels and fuel oils for agricultural and industrial machinery. Typical specifications for such fuel oils can be found, for example, in BS 2869, Part 2, 1988 of the British Standards Institution. Typical specifications for automotive diesel fuels or road diesel fuels in which the composition is composed of components a), b), c) and d) are particularly suitable and appear in BS 2869, Part 1, 1988 of the British Standards Institution. Of course, a huge number of such specifications exist in every country.

Concentrations and proportions.

In general, the components of the additive compositions are used in fuels in small quantities, sufficient to maintain the combustion characteristics and to improve the properties of the hydrocarbon fuel base in which they are used. Thus, the amounts vary according to such factors as the type of fuel base and the operating conditions for which the finished fuel is intended. In general, however, the following table illustrates the concentrations (ppm) of the components (active ingredients) in the base fuels: general area preferred area more preferred area particularly preferred area component

In case the fuels additionally contain one or more components d), e) and f), the following concentrations are typical: general area preferred area particularly preferred area component

It is understood that the individual components a), b) and c) as well as d), e) and/or f) (if used) can be mixed into the fuel separately or, if desired, in various sub-combinations. Usually, the particular sequence of such mixing steps is not critical. In addition, such components can be mixed in the form of a solution in a diluent. However, it is preferable to mix the components used in the form of an additional concentrate according to the invention, since this simplifies the mixing operations, reduces the likelihood of mixing errors and utilizes the characteristic compatibility and solubility properties offered by the total concentrate.

The additive concentrates according to the invention contain the components a), b) and c) and optionally, but preferably, one or more of the components d), e) and f) in amounts that are adjusted to give fuel mixtures that correspond to the concentrations listed in the above tables. In most cases, the additive concentrate contains one or more diluents, such as light mineral oils, to simplify handling and mixing of the concentrate. Thus, concentrates containing up to 90% by weight of one or more diluents or solvents are often used.

Other components.

If desired or deemed helpful in given situations, one or more other components may be added to the compositions of the invention. For example, the additive compositions and fuel compositions of the invention may also contain antioxidants, e.g., one or more phenolic antioxidants, aromatic amine antioxidants, sulfurized phenolic antioxidants, and organic phosphites. Examples include 2,6-di-tert-butylphenol, liquid mixtures of tertiary butylated phenols, 2,6- di-tert-butyl-4-methylphenol, 4,4'-methylene-bis-2,6-di-tert-butylphenol, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), mixed methylene-bridged polyalkylphenols, 4,4'-thiobis-(2-methyl-6-tert-butylphenol), N,N'-di-sec-butyl-p-phenylenediamine, 4-isopropylamino-diphenylamine, phenyl-α-naphthylamine and phenylnaphthylamine.

Corrosion inhibitors constitute another type of optional additive for use in this invention. For example, dimer and trimer acids such as those prepared from tall oil acids, oleic acid and linoleic acid may be used. Products of this type are currently commercially available from various sources, such as the dimer and trimer acids sold under the trade name HYSTRENE by the Humco Chemical Division of Witco Chemical Corporation and under the trade name EMPOL by Emery Chemicals. Another type of suitable corrosion inhibitor in practice of this invention are the alkenylsuccinic acid and alkenylsuccinic anhydride corrosion inhibitors, such as tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid, tetradecenylsuccinic anhydride, hexadecenylsuccinic acid and hexadecenylsuccinic anhydride. Also suitable are the half esters of alkenylsuccinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as polyglycols. Preferred materials are the aminosuccinic acids or derivatives thereof represented by the formula

in which each radical R¹, R², R⁵, R⁶ and R3 independently represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms and in which each radical R³ and R⁵ independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms or an acyl group having 1 to 30 carbon atoms.

When the groups R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are in the form of a hydrocarbon group, they may, for example, be groups containing alkyl, cycloalkyl or aromatic radicals. Preferably, R¹ and R⁵ are the same or different, straight-chain or branched hydrocarbon radicals having 1-20 carbon atoms. Most preferably, R¹ and R⁵ are saturated hydrocarbon radicals having 3-6 carbon atoms. When R², either R³ or R⁴, R⁵ and R⁷ are in the form of a hydrocarbon group, they are preferably the same or different, straight-chain or branched, saturated hydrocarbon radicals. Preferably, a dialkyl ester of an aminosuccinic acid is used in which R¹ and R⁵ are represent the same or different alkyl groups having 3-6 carbon atoms, R² represents a hydrogen atom and either R³ or R⁴ represents an alkyl group having 15-20 carbon atoms or an acyl group, which is derived from a saturated or unsaturated carboxylic acid having 2-20 carbon atoms.

Most preferred is a dialkyl ester of an aminosuccinic acid of the above formula, in which R¹ and R⁵ are isobutyl radicals, R² is a hydrogen atom, R³ is an octadecyl and/or octadecenyl radical and R3 is a 3-carboxy-1-oxo-2-propenyl radical. Most preferably in such esters the R⁶ and R⁵ radicals are hydrogen atoms.

The heavier fuels of this invention may contain cold flow improvers and pour point depressants, e.g., olefin/vinyl acetate copolymers such as ethylene/vinyl acetate copolymers and polymethacrylates. Antifoams such as silicones and dyes may also be used in the compositions of the invention. The diesel fuels may contain cetane improvers such as peroxy compounds and organic nitrates (e.g., amyl nitrates, hexyl nitrates, heptyl nitrates, octyl nitrates and other alkyl nitrates having 4 to 10 carbon atoms, including mixtures thereof). Some specific examples of such alkyl nitrates are cyclohexyl nitrate, methoxypropyl nitrate, mixed nitrate esters prepared by nitration of fusel oil, 2-ethylhexyl nitrate, n-octyl nitrate and n-decyl nitrate. Typical peroxy compounds include acetyl peroxide, benzoyl peroxide, tert-butyl peroxyacetate and cumene hydroperoxide.

All of the foregoing optional other components are well known in the art and are used in conventional proportions. In selecting such optional component(s), care should be taken to ensure that the material or combination of materials selected is compatible with the components of the overall composition in which they are to be used.

The following non-limiting examples, in which all parts and percentages are by weight, illustrate the invention.

EXAMPLE 1

An additional composition is created by mixing the following components together in the amounts listed:

4.0% Methylcyclopentadienyl manganese tricarbonyl (MMT) in the form of a mixture containing 62% MMr and 38% diluent (mainly aromatic solvents);

6.0% overbased calcium sulfonate in the form of a blend with 44% 100 solvent neutral oil and a typical TBN of 295;

6.9% Chevron OFA 425B, an ashless dispersant, believed to be a C13/C16 alpha-olefin-maleic anhydride copolymer aminated with an N-alkylpropylene diamine, in the form of a 50% solution in oil;

5.2% N-cyclohexyl-N,N-dimethylamine;

1.6% N,N'-disalicylidene-1,2-propanediamine as an 80% solution in xylene; and 76.3% aromatic naphtha.

This composition is well suited for use in fuel gas oils, for example at treatment rates of 250 to 37,000 ppm, typically 500 ppm.

EXAMPLE 2

An additive composition according to the invention is prepared using the following:

4% MMT in the form of the 62% solution in diluent listed in Example 1;

6.0% overbased calcium sulfonate in the form of the mixture listed in Example 1 in 100 solvent neutral oil;

5.5% polyisobutylene succinimide from tetraethylene pentamine (prepared from polybutenes with Mn of about 950) in the form of a 25% solution in oil;

1.4% Akzo Armogard D5021 demulsifier, which is believed to be a mixture of base demulsifiers and surfactants in an aromatic solvent;

5.2% N-cyclohexyl-N,N-dimethylamine;

1.6% N,N'-disalicylidene-1,2-propanediamine as an 80% solution in aromatic naphtha; and

76.3% aromatic heavy gasoline.

This composition is suitable for heating gas oils, for example at treatment rates of 250 to 37,000 ppm, usually 500 ppm.

EXAMPLE 3

Using the procedure of Example 1, the following components are mixed together:

4.5% MMT mixture as listed in Example 1;

33.0% overbased calcium sulfonate mixture as listed in Example 1;

22.7% polyisobutylene succinimide from tetraethylene pentamine (prepared from polybutenes with Mn of about 950) in the form of a 23% solution in a solvent oil;

6.8% demulsifier (Tolad 286K); and

33.0% aromatic heavy petrol diluent.

For example, when used in a concentration in the range of 200 to 26,500 ppm, usually 400 ppm, this concentrate is particularly suitable for improving the combustion of diesel fuels for road transport.

EXAMPLE 4

An additional concentrate is produced using the following components:

2.8% MMT;

14.5% overbased calcium sulfonate mixture;

17.1% polyisobutylene succinimide from an equivalent mixture of diethylene triamine, triethylene tetramine and tetraethylene pentamine (made from polybutenes with Mn of about 1000); and

65.6% inert diluents (primarily 100% solvent neutral mineral oil).

EXAMPLE 5

The following additional concentrate is produced

5.0% cyclopentadienyl manganese tricarbonyl in a mixture containing 40% aromatic hydrocarbon solvent;

30.5% overbased magnesium sulfonate;

24.5% product of the Mannich condensation of p-(polyisobutenyl)phenol (produced from polybutenes with Mn of about 750), formaldehyde and triethylenetetramine;

5.6% Akzo Armogard D5021 demulsifier; and

34.4% aromatic heavy petrol diluent

EXAMPLE 6

Examples 4 and 5 are repeated, using in one case overbased potassium sulfonate and in the other case overbased calcium phenolate instead of the sulfonates of Examples 4 and 5.

EXAMPLE 7

The procedures of Examples 1 to 3 are repeated, except that the overbased calcium sulfonate is replaced in one case by an equivalent amount of overbased magnesium sulfonate, in another case by an equivalent amount of overbased sodium sulfonate, and in a third case by an equivalent amount of overbased potassium sulfonate.

EXAMPLE 8

The respective compositions of Examples 1 to 3 are produced, with the exception that the methylcyclopentadienyl-manganesetricarbonyl is replaced, in one case by an equivalent amount of cyclopentadienyl-manganesetricarbonyl, in another case by an equivalent amount of cyclopentadienyl-manganesedicarboxyl-triphenylphosphine, in a third case by an equivalent amount of indenyl-manganesetricarbonyl, in a fourth case by an equivalent amount of dimanganese-decacarbonyl and in yet another case by an equivalent amount of a mixture consisting of 90% methylcyclopentadienyl-manganesetricarbonyl and 10% cyclopentadienyl manganese tricarbonyl.

EXAMPLE 9

The respective compositions of Examples 1 and 2 are mixed in concentrations of 300, 500 and 1000 ppm in a heating gas oil with a specific gravity at 15 ºC (DIN 51 757) of 0.845 g/ml, a kinematic viscosity at 20 ºC (DIN 51 562) of 5.3 mm² per second, a pour point (DIN 150 3016) at -9 ºC, a sulfur content (DIN 51 400) of 0.19% and a distillation profile (DIN 51 751) of 27 vol.% boiling up to 250 ºC and 92 vol.% boiling up to 350 ºC.

EXAMPLE 10

Example 9 is repeated except that equal amounts of the respective components of the respective compositions from Examples 1 and 2 are mixed individually or in sub-combinations into the gas oil.

EXAMPLE 11

The composition of Example 3 is mixed in concentrations of 300, 500, 1000 and 1500 ppm into a diesel fuel that meets the requirements of DIN 51 601-DK (February 1986).

EXAMPLE 12

Example 11 is repeated except that equal amounts of the respective components of the composition of Example 3 are mixed individually or in subcombinations into the diesel fuel.

EXAMPLE 13

The procedures of Examples 11 and 12 are repeated using commercially available diesel fuels suitable for use as railroad diesel fuel, tractor diesel fuel, off-road vehicle fuel and inland waterway fuel.

EXAMPLE 14

Examples 9 and 10 are repeated using as fuels the commercially available heavy fuel oils and residual oils (e.g. industrial and refinery fuel oils), such as heavy fuel oils for inland transport, as well as hydrocarbon-containing fuels for marine use. The concentrations for treatment with the additive are 500, 800 and 1500 ppm.

EXAMPLE 15

An additional composition is created by mixing the following components together in the amounts listed:

4.0% Methylcyclopentadienyl manganese tricarbonyl (MMT) in the form of a mixture containing 62% MMT and 38% diluent (mainly aromatic solvents);

6.0% overbased calcium sulfonate in the form of a blend with 44% 100 solvent neutral oil and a typical TBN of 295;

9.2% Chevron OFA 425B, an ashless dispersant, believed to be a C₁₃/C₁₆ α-olefin-maleic anhydride copolymer aminated with an N-alkylpropylene diamine, in the form of a 50% solution in oil;

9.2% N-cyclohexyl-N,N-dimethylamine;

1.6% N,N'-disalicylidene-1,2-propanediamine as an 80% solution in xylene; and

70.0% aromatic heavy gasoline.

This composition is well suited for use in fuel gas oils, for example at treatment rates of 250 to 37,000 ppm, typically 500 ppm.

EXAMPLE 16

The procedure of Example 15 is repeated using the additional components in the following ratios:

4.0% MMT in the form of the mixture from Example 15;

6.0% overbased calcium sulfonate in the form of the mixture from Example 15;

6.9% Chevron OFA 425B in the form of the solution from Example 15,

6.9% N-cyclohexyl-N,N-dimethylamine;

1.2% N,N'-disalicylidene-1,2-propanediamine in the form of the solution from Example 15; and

75.0% aromatic heavy gasoline.

EXAMPLE 17

The procedure of Example 15 is repeated using the additional components in the following ratios:

4.0% MMT in the form of the mixture from Example 15;

6.0% overbased calcium sulfonate in the form of the mixture from Example 15;

6.9% Chevron OFA 425B in the form of the solution from Example 15,

5.2%N-cyclohexyl-N,N-dimethylamine;

1.2% N,N'-disalicylidene-1,2-propanediamine in the form of the solution from Example 15; and

76.7% aromatic heavy gasoline.

The effectiveness and advantageous characteristics of the compositions of the invention are illustrated by the results of a number of standardized tests. For example, an 81 kW gas oil fired hot water boiler was operated with a flue gas temperature of 207 ºC, a flue gas carbon dioxide content of 12.1% and a flue gas carbon monoxide content above 100 ppm. The base heating gas oil was as listed in Example 9. Operation of the boiler with the additive-free gas oil gave a Bacharach soot number of 4.60, while the same gas oil containing 500 ppm of the additive composition of Example 1 gave a Bacharach soot number of 2.70, a 41% reduction. Measurements of the acidity of the soot (an average of 4 measurements) showed that the clear base gas oil produced soot with an average pH of 4.05. In contrast, the average pH of the soot from the inventive fuel was 7.06.

Standard CFR engine tests (ASTM D613) were conducted using two different diesel fuels with cetane values of 52.7 (Fuel A) and 52.5 (Fuel B), respectively. The addition of 500 ppm of the composition of Example 1 to fuel A did not cause any change in the cetane rating. For fuel B, the addition of 500 ppm of the composition from example 1 resulted in only a slight loss in the cetane value (from 52.5 to 51.6).

The same pair of diesel fuels were subjected to standard corrosion tests (ASTM 665A), both with and without 500 ppm of the additive composition of Example 1. The results of these tests were as follows: Evaluation according to ASTM 665A Fuel A without additives Fuel B without additives

The same fuels were subjected to thermal stability tests in which the sample was heated to 150 ºC for 90 minutes and filtered through a filter. The reflectivity of the deposit on the filter is measured. The rating scale ranges from 0 (clear) to 20 (black). A rating of 7 or below is considered good. Thermal oxidative stability tests according to ASTM D 2274 were also conducted on these fuels. Performance in these tests is expressed in terms of milligrams of deposit per 100 ml of fuel. The results were as follows: Thermal stability (filter tests) Thermal oxidative stability (ASTM D2274) Fuel A without additivesa Fuel A with additivesb Fuel A with additivesc Fuel B without additives Fuel B with additivesb Fuel B with additivesd Fuel B without additivesa Fuel B with additivese Fuel B with additivesac a Average of two tests b Additive composition from Example 1 c Additive composition from Example 15 d Additive composition from Example 17 e Additive composition from Example 16.

Diesel fuels both with and without the additive composition of the invention as disclosed in Example 2 were subjected to standard corrosion tests (ASTM 665A) and (ASTM 665B). The results were as follows: Rating according to ASTM 665A Rating according to ASTM 665b Fuel A without additives Fuel A with additives Fuel B without additives Fuel B with additives

The same compositions were subjected to thermal stability tests in which the sample was heated to 150 ºC for 90 minutes, filtered through a filter and the reflectivity of the deposit on the filter was measured. The rating scale ranges from 0 (clear) to 20 (black).

A rating of 7 or below is considered good. Thermal oxidative stability tests were also conducted on these fuel compositions according to ASTM D 2274. Performance in these tests is expressed in milligrams of deposit per 100 ml of fuel. The results were as follows: thermal stability (filter tests) thermal oxidative stability (ASTM D2274) Fuel A without additives Fuel A with additives Fuel B without additives Fuel B with additives

Demulsification tests (ASTM D 1094) on the same four fuels gave the following results: Evaluation of the interface Evaluation of the separation Volume of the aqueous phase, ml Fuel A without additives Fuel A with additives Fuel B without additives Fuel B with additives

Using a commercially available domestic heating gas oil, additional tests were conducted to determine the performance of two different burners. One was a modern burner, while the other was manufactured fifteen years ago. In both cases, the burners were adjusted according to the manufacturer's specifications. In these tests, the additive compositions of Examples 1 and 2 were used with a simultaneous baseline determination using the clear base fuel. Measurements were made of the smoke number and carbon monoxide content of the flue gases. The flue gas determinations include a scale ranging from 0 to 10, whose ratings refer to a filter through which the flue gases pass during operation. A rating of 10 means black, so the smaller the number, the better. Carbon monoxide ratings are expressed in terms of parts per million present in the flue gas. The following table summarises this data. old burner new burner smoke number base fuel without additives base fuel with additivesa base fuel with additiveb base fuel with additivec base fuel with additived a additive composition from example 1 at 500 ppm b additive composition from example 1 at 1000 ppn c additive composition from example 2 at 500 ppm d additive composition from example 2 at 1000 ppm

Engine tests were carried out by operating a Mercedes Benz OM 364A, 4 litre, 4 cylinder turbocharged diesel engine at full load and various speeds. Fuel consumption was determined using a conventional diesel fuel without additives and the same base fuel containing the additive composition of Example 3 at a concentration of 400 ppm. The data are summarized in the following table. Fuel consumption, g/kW h Engine speed Fuel without additives Fuel with additives

During operation of the above Mercedes Benz diesel engine, the exhaust emissions generated by the same pair of fuel compositions were also determined. It was found that hydrocarbon emissions were reduced from 0.627 g per horsepower hour to 0.527 g per horsepower hour by the presence of the 400 ppm additive composition of Example 3. In addition, the total particulate matter emitted by the clear fuel was 0.3574 g per horsepower hour, while the total particulate matter emitted by the fuel containing 400 ppm of the additive composition of Example 3 was only 0.3063 g per horsepower hour. The reductions were achieved without any appreciable change in NOx and carbon monoxide emissions.

The emission of polyaromatic hydrocarbons (expressed in terms of nanograms of polyaromatic hydrocarbons per milligram of particulate emission) was also determined on the Mercedes Benz diesel engine using the same pair of fuel compositions. The mean values of the results from two tests with each fuel at two dynamometer load levels with the engine running at 1560 rpm were as follows: Engine load Fuel without additives Fuel with additives

The foregoing and other test results have shown that the fuels of this invention generally have improved combustion characteristics (e.g., less smoke, lower acidity of soot) and better thermal stability than the corresponding untreated fuels. In addition, use of the fuels of this invention results in lower levels of sludge deposits being produced on critical engine or burner parts or surfaces. Furthermore, such fuels tend to emit lower levels of harmful emissions than the corresponding untreated base fuels. Also, this invention enables the provision of fuel compositions having improved demulsification properties and reduced corrosion susceptibility with minimal impact on other desired fuel properties. The results of the above tests also demonstrate that the additive compositions of the invention can result in reduced fuel consumption in diesel engines. The data also demonstrate that not all fuels respond equally to treatment with the additive systems of the invention. Nevertheless, the fuels of this invention generally are claimed to have significantly improved properties.

From the foregoing, it will be apparent that this invention in its embodiments includes methods for improving the combustion properties of a liquid fuel containing at least mainly hydrocarbons, comprising mixing this fuel with a minor, combustion-enhancing amount of

(a) at least one fuel-soluble manganese carbonyl compound;

(b) at least one fuel-soluble detergent containing alkali or alkaline earth metals, and

(c) at least one fuel-soluble ashless dispersant

Such compositions preferably contain, as described above, one or more of components d), e) and f).

Likewise, the embodiments of the invention include methods for improving the combustion properties of an at least predominantly hydrocarbon-containing liquid fuel during combustion in an engine, burner or other combustion device, comprising operating said engine, burner or other combustion device with an at least predominantly hydrocarbon-containing liquid fuel which contains a smaller combustion-improving amount of

(a) at least one fuel-soluble manganese carbonyl compound;

(b) at least one fuel-soluble detergent containing alkali or alkaline earth metals, and

(c) contains at least one fuel-soluble ashless dispersant. Here, the fuel compositions again, as described above, preferably contain one or more of the components d), e) and f).

Claims (23)

1. Fuel composition containing a major amount of a liquid hydrocarbon fuel containing a minor amount of a combustion-enhancing (a) at least one fuel-soluble manganese carbonyl compound; (b) at least one fuel-soluble detergent containing an alkali or alkaline earth metal; (c) at least one fuel-soluble ashless dispersant; d) optionally at least one fuel-soluble demulsifier; e) optionally at least one fuel-soluble aliphatic or cycloaliphatic amine and f) optionally at least one fuel-soluble metal deactivator contains. 2. Composition according to claim 1, in which the component a) contains at least one cyclopentadienyl manganese tricarbonyl compound. 3. Composition according to claim 1, in which the component a) contains methylcyclopentadienyl manganese tricarbonyl. 4. Composition according to one of claims 1 to 3, in which component b) comprises at least one overbased alkali or alkaline earth metal-containing detergent. 5. Composition according to one of claims 1 to 3, in which component b) comprises at least one overbased alkaline earth metal-containing detergent. 6. A composition according to any one of claims 1 to 3, in which component b) comprises at least one overbased calcium-containing detergent. 7. A composition according to claim 6, wherein component b> comprises at least one overbased detergent selected from calcium sulphonate, phenolate or sulphurised phenolate. 8. Composition according to one of the preceding claims, in which component c) comprises at least one basic nitrogen-containing ashless dispersant. 9. A composition according to claim 8, wherein component c) comprises at least one ashless succinimide dispersant. 10. A composition according to claim 9, wherein component c) is a polyolefin-substituted succinimide of at least one polyethylene polyamine having an average total composition ranging from triethylenetetramine to pentaethylenehexamine such as a polyisobutenylsuccinimide from a mixture of acyclic and cyclic polyethylenepolyamine species, the mixture having a composition approximately corresponding to tetraethylene. 11. The composition of claim 10, wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight of 900 - 2,000. 12. Composition according to one of the preceding claims, which e) contains at least one fuel-soluble N-cycloalkyl-N,N-dialkylamine such as N-cyclohexyl-N,N-dimethylamine. 13. Composition according to one of the preceding claims, which f) contains at least one fuel-soluble metal deactivator of the chelator type, preferably an N,N'-disalicylidene-1,2-alkanediamine or N,N'-disalicylidene-1,2-cycloalkanediamine such as N,N'-disalicylidene-1,2-propanediamine. 14. Composition according to one of the preceding claims, in which the proportions (ppm) of components a) b) and c) in the base fuel are 1.5 - 10,000 : 4 - 10,000 or : 5 - 15,000. 15. Composition according to claim 14, in which the proportions (ppm) of components a), b) and c) in the base fuel are 2.5 - 1,500 : 5 - 6,000 or : 7 - 10,000. 16. Composition according to claim 16, in which the proportions (ppm) of components a), b) and c) are 3 - 100 6 - 300 and 8 - 5,000 respectively. 17. Composition according to claim 16, in which the proportions (ppm) of components a), b) and c) are 3 - 25 6 - 100 and 10 - 200 respectively. 18. A composition according to any preceding claim, which contains 0 to 10 ppm of occluded halogen, and is preferably free from detectable amounts of occluded halogen. 19. A fuel additive composition containing the components a), b) and c) and optionally d), e) and f) as defined in any one of claims 1 to 17. 20. A method for improving the combustion properties of a liquid fuel containing at least predominantly hydrocarbons, for example during combustion in an engine, burner or other combustion device, in which a small, combustion-improving amount of the ingredients a), b) and c) and optionally d), e) and f) according to one of claims 1 to 17 are mixed with this fuel. 21. A fuel composition according to any one of claims 1 to 17, in which the fuel is a diesel fuel containing a cetane improver selected from peroxy compounds and organic nitrates. 22. A fuel composition according to claim 21, in which the cetane improver is an alkyl nitrate having 4 to 10 carbon atoms. 23. A fuel composition according to claim 22, in which the cetane improver is 2-ethylhexyl nitrate.