FR3092333A1 - Fuel composition based on paraffinic hydrocarbons - Google Patents

Abstract

The present invention relates to a fuel composition which comprises - at least 85% by weight of one or more cuts of hydrocarbons having a distillation range included in the range from 100 to 400 ° C and having a paraffin content greater than or equal to 90% by weight; - at least a first additive consisting of a specific quaternary ammonium salt; and - at least a second additive consisting of a phenolic antioxidant. A subject of the invention is also the use of an additive composition comprising said first and second additives, for improving at least one property of a fuel composition rich in paraffins, as well as the use of such a composition. as fuel in particular for vehicles or stationary machines equipped with a diesel engine.

Description

Paraffinic hydrocarbon fuel composition

The present invention relates to a fuel composition based on one or more paraffin-rich cuts, which comprises at least one first additive consisting of a quaternary ammonium salt in combination with at least one second additive chosen from anti -phenolic oxidants.

The present invention also relates to the use of an additive composition comprising the combination of said first (s) and second (s) additives, in order to improve the properties of a fuel composition comprising a high content of paraffins .

The present invention also relates to the use of such a fuel composition for powering a diesel engine.

STATE OF THE PRIOR ART

The use of hydrocarbon cuts particularly rich in paraffins in the formulation of fuels and in particular fuels for compression ignition engines (or diesel engines) is increasingly common. Hydrotreated vegetable oils, known to those skilled in the art under the name HVO (from the English "hydrotreated vegetable oil"), constitute a classic example of cuts very rich in paraffins, which can be incorporated at more or less important in fuels intended for road vehicles (in particular motor vehicles and heavy goods vehicles such as, for example, trucks, refuse collection vehicles, buses and coaches) and non-road vehicles (in particular machinery intended for construction sites and/or public works such as buldozers, off-road trucks; handling equipment; tractors and agricultural machinery; boats; locomotives, etc.).

The trend is to increasingly increase the proportions of such hydrocarbon cuts, compared to the conventional cuts resulting from the distillation of petroleum, or even to seek to formulate fuel compositions exclusively from such cuts. In particular, for environmental reasons and/or availability of resources, the regulations of many countries encourage the introduction of increasing quantities of products of renewable origin, such as HVO-type cuts. In fact, HVOs do not have the harmful effects that ester-type biodiesels can provide, such as increased NOx emissions, formation of deposits, etc.

However, the formulation of a fuel composition comprising a very high content of paraffins poses a certain number of difficulties.

In particular, these fuels have proven to have poor corrosion resistance, very much lower than that of fuels of petroleum origin. Their use can lead to phenomena of rust and corrosion of the materials with which these fuels are in contact, in particular at the logistics stage for the distribution of these fuels (transport, storage, vehicle fuel supply systems).

In addition, such fuels lead to a phenomenon of metal extraction: they tend to extract certain metals, in particular copper and zinc, from the materials with which they are brought into contact (for example the materials of transport devices, storage, vehicle fuel supply systems, etc.).

They also have a low conductivity value, linked to their paraffinic nature. However, fuels with low conductivity pose problems during fuel transfers (in particular when filling the vehicle tank): by friction or potential difference, electric discharges can occur if the fuel is not sufficiently conductive, which which creates a fire hazard.

Finally, these fuels pose particular problems of stability during storage and use: in the event of prolonged storage or in the event of use under conditions of high pressure or temperature, the product tends to oxidize and degrade. This phenomenon is catalyzed by the metals possibly present in the fuel composition. This fuel instability can lead to clogging of filters and fuel injection systems in vehicles.

Patent application WO 2015/193463 (Shell) describes the use of a combination of detergents (i), lubricity improvers and conductivity improvers (ii), in a diesel fuel composition containing a substantial content in paraffins (in particular in n-paraffins resulting from a Fischer-Tropsch synthesis) as well as an antioxidant agent.

The antioxidant is chosen in particular from phenolic compounds and amines. The synergistic association of the antioxidant agent with components (i) and (ii) in a high n-paraffin diesel fuel is described as significantly increasing the oxidative stability of the fuel.

OBJECT OF THE INVENTION

The applicant has now discovered that the use of a particular combination of two additives, as defined below, makes it possible to remedy the aforementioned problems effectively, and to allow the formulation of fuel compositions rich in paraffins having properties improved.

Thus, the subject of the present invention is a fuel composition comprising:
- at least 85% by weight of one or more hydrocarbon cuts having a distillation range comprised in the range from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight;
- at least one first additive consisting of a quaternary ammonium salt, obtained by reaction with a quaternizing agent of a nitrogen compound comprising a tertiary amine function, this compound being the product of the reaction of an acylation agent substituted by a hydrocarbon group and by a compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols; and
- at least one second additive consisting of an antioxidant chosen from compounds comprising a phenol group.

Such a fuel composition has excellent anti-corrosion performance, and makes it possible to avoid corrosion phenomena both in the presence of fresh water and salt water.

It also makes it possible to very significantly improve the stability of the fuel in the presence of metals, and has very good conductivity.

This composition has an excellent level of stability and in particular good storage stability, good thermal stability and, more generally, good resistance to oxidation.

Finally, this composition has also proven to have good detergent performance, and its use makes it possible not only to maintain the cleanliness of the engine, in particular, by limiting or avoiding the formation of deposits (“keep-clean” effect in English) but also to reduce the deposits already present in the internal parts of the engine (“clean-up” effect in English).

It should be noted that these properties are improved without any degradation of the other intrinsic properties of the compositions based on paraffin-rich cuts, such as in particular their low level of foaming and demulsification, their density, their cetane number, their good cold behavior in the case of cuts rich in iso-paraffins (filtrability limit temperature and pour point).

Its excellent properties make this fuel suitable for use in modern motor vehicles, in particular vehicles comprising a diesel engine, including the most advanced engines such as very high pressure direct injection diesel engines.

Other objects, characteristics, aspects and advantages of the invention will appear even more clearly on reading the description and the examples which follow.

In what follows, and unless otherwise indicated, the limits of a range of values are included in this range, in particular in the expressions “included between” and “ranging from … to …”.
Furthermore, the expressions “at least one” and “at least” used in the present description are respectively equivalent to the expressions “one or more” and “greater than or equal”.
Finally, in a manner known per se, the term C _N compound or group designates a compound or a group containing N carbon atoms in its chemical structure.

Cutting paraffinic hydrocarbons

The composition according to the invention comprises one or more hydrocarbon cuts having a distillation range comprised in the range extending from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight, hereinafter referred to as " cutting of paraffinic hydrocarbons”.

The distillation range of said paraffinic hydrocarbon cut is determined in accordance with standard NF EN ISO 3405. Preferably, it is in the range going from 130 to 350°C, and more preferably from 150 to 320°C.

The paraffin content of this cut is greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, more preferably still greater than or equal to 99% by weight, better still greater than or equal to 99.5% by weight, and better still greater than or equal to 99.9% by weight, relative to the total weight of said cut.

By “paraffins” is meant, in a manner known per se, branched alkanes (also called iso-paraffins or iso-alkanes) and unbranched alkanes (also called n-paraffins or n-alkanes).

The paraffins present in the paraffin hydrocarbon cut(s) according to the invention advantageously comprise from 10 to 20 carbon atoms. Preferably, they consist of at least 60% by weight, more preferably at least 80% by weight and better still at least 90% by weight of paraffins comprising from 12 to 18 carbon atoms, preferably from 14 to 18 carbon atoms, and even more preferably from 15 to 18 carbon atoms.

According to a preferred embodiment, the paraffin hydrocarbon cut or cuts used in the composition according to the invention contain at least 50% by weight, preferably at least 70% by weight of iso-paraffins, relative to their weight total. According to a particularly preferred embodiment, they contain at least 90% by weight of iso-paraffins.

The paraffin hydrocarbon cut or cuts have a content of aromatic compounds preferably less than or equal to 10,000 ppm by weight, more preferably less than or equal to 1,500 ppm by weight, even more preferably less than or equal to 1,000 ppm by weight.

Their naphthenic compound content is preferably less than or equal to 20,000 ppm by weight, more preferably less than or equal to 10,000 ppm by weight, and better still less than or equal to 1,500 ppm by weight.

Their sulfur content is advantageously less than or equal to 10 ppm by weight, and better still less than or equal to 5 ppm by weight. Particularly preferably, this cut is completely free of sulphur.

According to a particularly preferred embodiment, the paraffin hydrocarbon cut or cuts are hydrotreated vegetable oils, also known under the name HVO (standing for “hydrotreated vegetable oils”). These are oils of vegetable origin which have undergone successive treatments including hydrotreatment and then possible isomerization.

Examples of suitable vegetable raw materials include rapeseed oil, canola oil, sunflower oil, soybean oil, hemp oil, olive oil, linseed oil , mustard oil, palm oil, castor oil, coconut oil.

Patent applications WO2016/185046 and WO2016/185047 describe hydrotreated vegetable oils and their preparation, which constitute examples of iso-paraffinic hydrocarbon cuts that are particularly suitable for the compositions that are the subject of the present invention.

The composition according to the invention comprises at least 85% by weight of one or more paraffinic hydrocarbon cuts as described above. Preferably, it contains at least 90% by weight of one or more paraffinic hydrocarbon cuts, more preferably at least 93% by weight.

According to one embodiment, the composition according to the invention contains at least 95% by weight, preferably at least 99% by weight, and better still at least 99.5% by weight of one or more paraffinic hydrocarbon cuts as described above.

The first additive (quaternary ammonium salt):

The composition according to the invention comprises a first additive consisting of a quaternary ammonium salt, obtained by reaction with a quaternizing agent of a nitrogenous compound comprising a tertiary amine function, this nitrogenous compound being the product of the reaction of an acylating agent substituted with a hydrocarbon group and a compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols.

Said nitrogenous compound is the product of the reaction of an acylating agent substituted by a hydrocarbon group and of a compound comprising both an oxygen atom or a nitrogen atom capable of condensing with said acylation and a tertiary amine group.

The acylation agent is advantageously chosen from mono- or poly-carboxylic acids and their derivatives, in particular their ester, amide or anhydride derivatives. The acylation agent is preferably chosen from succinic, phthalic and propionic acids and the corresponding anhydrides.

The acylating agent is substituted by a hydrocarbon group. The term "hydrocarbon" group means any group having a carbon atom directly attached to the rest of the molecule (ie to the acylating agent) and having mainly an aliphatic hydrocarbon character.

Hydrocarbon groups according to the invention can also contain non-hydrocarbon groups. For example, they may contain up to one non-hydrocarbon group for every ten carbon atoms provided that the non-hydrocarbon group does not significantly alter the predominantly hydrocarbon character of the group. Mention may be made, by way of example of such groups well known to those skilled in the art, of hydroxyl groups, halogens (in particular chloro- and fluoro-groups), alkoxy, alkylmercapto, alkyl sulfoxy groups.

Nevertheless, preference will be given to hydrocarbon substituents not containing such non-hydrocarbon groups and having a purely aliphatic hydrocarbon character.

The hydrocarbon substituent of the acylating agent preferably comprises at least 8, preferably at least 12 carbon atoms. Said hydrocarbon substituent may comprise up to approximately 200 carbon atoms.

The hydrocarbon substituent of the acylating agent preferably has a number-average molecular mass (Mn) of between 170 and 2800, for example between 250 and 1500, more preferably between 500 and 1500 and, even more preferably between 500 to 1100. A value range of M _n comprised between 700 and 1300 is particularly preferred, for example from 700 to 1000.

By way of example of hydrocarbon groups substituting the acylation agent, mention may be made of n-octyl, n-decyl, n-dodecyl, tetrapropenyl, n-octadecyl, oleyl, octadecyl or triacontyl groups.

The hydrocarbon substituent of the acylating agent can also be obtained from homo- or inter-polymers (e.g. copolymers, terpolymers) of mono- and di-olefins having from 2 to 10 carbon atoms, for example from ethylene, propylene, 1-butene, isobutene, butadiene, isoprene, 1-hexene or 1-octene. Preferably, these olefins are 1-mono-olefins.

The hydrocarbon substituent of the acylation agent can also be chosen from derivatives of halogenated analogues (for example chlorinated or brominated) of these homo- or inter-polymers.

Alternatively, the hydrocarbon substituent of the acylating agent may be obtained from other sources, for example from high molecular weight alkene monomers (e.g., 1-tetracontene) and their chlorinated analogues or hydrocarbons, aliphatic petroleum fractions, e.g. paraffin waxes, their cracked, chlorinated and/or hydrochlorinated analogues, white oils, synthetic alkenes, e.g. produced by the Ziegler-Natta process (e.g. polyethylene greases ) and other sources known to those skilled in the art.

Any unsaturation present in the hydrocarbon group of the acylating agent can optionally be reduced or eliminated by hydrogenation according to any known method.

The hydrocarbon substituent of the acylating agent is preferably substantially saturated, i.e. it contains no more than one carbon-carbon unsaturated bond for every ten carbon-carbon single bonds present.

The hydrocarbon substituent of the acylating agent advantageously contains no more than one non-aromatic carbon-carbon unsaturated bond for every 50 carbon-carbon bonds present.

According to a preferred embodiment, the hydrocarbon substituent of the acylation agent is a polyisobutene (PIB) group. The so-called highly reactive polyisobutenes (PIBs) are very particularly preferred. The term “highly reactive polyisobutenes (PIB)” means polyisobutenes (PIB) in which at least 50% by mole, preferably at least 70% by mole or more, of the terminal olefinic double bonds are of the vinylidene type as described in document EP0565285. In particular, the preferred PIBs are those having more than 80% by moles and up to 100% by moles of vinylidene terminal groups as described in document EP1344785.

According to a particularly preferred embodiment, the acylation agent substituted by a hydrocarbyl group is a polyisobutenyl-succinic anhydride (PIBSA).

The preparation of polyisobutenyl-succinic anhydrides is known per se, and widely described in the literature. Mention may be made, by way of example, of the processes comprising the reaction between polyisobutenes (PIB) and maleic anhydride described in documents US3361673 and US3018250 or the process comprising the reaction of a halogenated polyisobutene (PIB), in particular chlorinated , with maleic anhydride (US3172892).

Alternatively, polyisobutenyl succinic anhydride can be prepared by mixing a polyolefin with maleic anhydride and then passing chlorine through the mixture (GB949981).

Other hydrocarbon groups comprising an internal olefin, for example such as those described in application WO2007/015080, can also be used as substituent of the acylation agent. By internal olefin is meant any olefin containing mainly a non-alpha double bond, which is a beta or higher position olefin.

Preferably, these materials are essentially beta-olefins or higher position olefins, for example containing less than 10% by mass of alpha-olefin, advantageously less than 5% by mass or less than 2% by mass.

The internal olefins can be prepared by isomerization of alpha-olefins according to any known method.

The compound comprising both an oxygen atom or a nitrogen atom capable of condensing with the acylating agent and a tertiary amine group can, for example, be chosen from the group consisting of: N,N - dimethylaminopropylamine, N,N-diethylaminopropylamine, N,N-dimethylaminoethylamine. Said compound can also be chosen from heterocyclic compounds substituted by alkylamines such as 1-(3-aminopropyl)imidazole and 4-(3-aminopropyl)morpholine, 1-(2-aminoethyl)piperidine, 3,3 - diamino-N-methyldipropylamine, and 3'3-bisamino(N,N-dimethylpropylamine).

The compound comprising both an oxygen atom or a nitrogen atom capable of condensing with the acylating agent and a tertiary amine group can also be chosen from alkanolamines, including, but not limited to , triethanolamine, trimethanolamine, N,N-dimethylaminopropanol, N,N-dimethylaminoethanol, N,N-diethylaminopropanol, N,N-diethylaminoethanol, N,N-diethylaminobutanol, N,N,N-tris(hydroxyethyl )amine, N,N,N-tris(hydroxymethyl)amine, N,N,N tris(aminoethyl)amine, N,N-dibutylaminopropylamine and N,N,N'-trimethyl-N'-hydroxyethyl- bisaminoethyl ether, N,N-bis(3-dimethylamino-propyl)-N-isopropanolamine, N-(3-dimethylamino-propyl)-N,N-diisopropanolamine, N'-(3-(Dimethylamino)propyl)- N,N-dimethyl-1,3-propanediamine; 2-(2-dimethylaminoethoxy)ethanol and N,N,N'-trimethylaminoethylethanolamine.

According to a preferred embodiment, said compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols is chosen from the following amines of formula (I) or (II):

[Chem 2]

in which :
R6 and R7 are identical or different and represent, independently of each other, an alkyl group having from 1 to 22 carbon atoms;
X is an alkylene group having 1 to 20 carbon atoms;
m is an integer between 1 and 5;
n is an integer between 0 and 20; and
R8 is a hydrogen atom or a C1 to C22 alkyl group.

When the nitrogen compound comprises an amine of formula (I), R8 is advantageously a hydrogen atom or a C1 to C16 alkyl group _, preferably a C1 to C10 alkyl group _, even more preferably a C1 to C6 alkyl group . R8 can, for example, be selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl and their isomers. Preferably R8 is a hydrogen atom.

When the nitrogen compound comprises an amine of formula (II), m is preferably equal to 2 or 3, more preferably equal to 2; n is preferably an integer between 0 to 15, more preferably between 0 to 10, even more preferably between 0 to 5. Advantageously, n is 0.

According to a preferred embodiment, said nitrogen compound is the product of the reaction of the acylating agent substituted by a hydrocarbon group and of a diamine of formula (I).

In this embodiment:
- R6 and R7 may represent, independently of each other, a C1 to C16 alkyl group_,preferably a C1 to C10 alkyl group ;
_-R6 and R7 can represent, independently of each other, a methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl group or their isomers. Advantageously, R6 and R7 represent, independently of each other, a C1 to C4 group, preferably a methyl group;
- X represents an alkylene group having 1 to 16 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, for example 2 to 6 carbon atoms or 2 to 5 carbon atoms. carbon. X particularly preferably represents an ethylene, propylene or butylene group, in particular a propylene group.

According to a particularly preferred embodiment, the nitrogen compound is the reaction product of a succinic acid derivative substituted by a hydrocarbon group, preferably a polyisobutenyl-succinic anhydride, and an alcohol or an amine also comprising a tertiary amine group, in particular a compound of formula (I) or (II) as described above and more preferably a compound of formula (I).

According to a first variant, the succinic acid derivative substituted by a hydrocarbon group reacts with the amine also comprising a tertiary amine group under certain conditions to form a succinimide (closed form). The reaction of the succinic acid derivative and the amine can also lead under certain conditions to a succinamide, that is to say, a compound comprising an amide group and a carboxylic acid group (open form).

According to a second variant, an alcohol also comprising a tertiary amine group reacts with the succinic acid derivative to form an ester also comprising a free —CO ₂ H carboxyl group (open form). Thus, in certain embodiments, the nitrogen compound may be the reaction product of a succinic acid derivative and an amine or an alcohol which is an ester or an amide and which furthermore also comprises a carboxyl group -CO2H unreacted (open form).

The quaternary ammonium salt forming the second additive according to the present invention is directly obtained by reaction between the nitrogen compound described above comprising a tertiary amine function and a quaternizing agent.

According to a particular embodiment, the quaternizing agent is chosen from the group consisting of dialkyl sulphates, carboxylic acid esters; alkyl halides, benzyl halides, hydrocarbon carbonates, and hydrocarbon epoxides optionally mixed with an acid, alone or mixed.

For fuel applications, it is often desirable to reduce the content of halogen, sulfur and phosphorus-containing compounds.

Thus, if a quaternizing agent containing such an element is used, it may be advantageous to carry out a subsequent reaction to exchange the counterion. For example, a quaternary ammonium salt formed by reaction with an alkyl halide can then be reacted with sodium hydroxide and the sodium halide salt removed by filtration.

The quaternizing agent can include halides such as chloride, iodide or bromide; hydroxides; sulfonates; bisulfites; alkyl sulfates such as dimethyl sulfate; sulfones; phosphates; C1-C12 alkyl phosphates _; C1-C12 dialkyl phosphates; borates; C1-C12 alkyl borates; nitrites; nitrates; carbonates; from
bicarbonates; alkanoates; C1-C12 O,O-dialkyldithiophosphates _, alone or as a mixture.

According to a particular embodiment, the quaternizing agent can be chosen from derivatives of dialkyl sulphates such as dimethyl sulphate, of N-oxides, of sulphones such as propane- and butane-sulphone, of alkyl halides , acyl or aralkyl such as methyl and ethyl chloride, bromide, iodide or benzyl chloride, and hydrocarbon carbonates (or alkylcarbonates).

If the acyl halide is benzyl chloride, the aromatic ring is optionally substituted by one or more alkyl or alkenyl groups.

The hydrocarbon (alkyl) groups of the hydrocarbon carbonates can contain from 1 to 50, from 1 to 20, from 1 to 10 or from 1 to 5 carbon atoms per group. According to one embodiment, the hydrocarbon carbonates contain two hydrocarbon groups which may be identical or different. By way of example of hydrocarbon carbonates, mention may be made of dimethyl or diethyl carbonate.

According to a preferred embodiment, the quaternizing agent is chosen from the hydrocarbon epoxides represented by the following formula (III):
in which R9, R10, R11 and R12 may be identical or different and independently represent a hydrogen atom or a C ₁ to C ₅₀ hydrocarbon group. By way of non-limiting example, mention may be made of styrene oxide, ethylene oxide, propylene oxide, butylene oxide, stilbene oxide and C ₁ to C ₅₀ epoxies. Styrene oxide and propylene oxide are particularly preferred.

Such hydrocarbon epoxides can be used as a quaternizing agent in combination with an acid, for example with acetic acid. Hydrocarbon epoxides can also be used alone as a quaternizing agent, in particular without additional acid. Without being bound by this hypothesis, it would seem that the presence of the carboxylic acid function in the molecule favors the formation of the quaternary ammonium salt. In such an embodiment not using additional acid, a protic solvent is used for the preparation of the quaternary ammonium salt. For example, protic solvents such as water, alcohols (including polyhydric alcohols) can be used alone or in a mixture. Preferred protic solvents have a dielectric constant greater than 9.

Corresponding quaternary ammonium salts prepared from amides or esters and succinic acid derivatives are described in WO2010/132259.

According to another embodiment, the quaternization agent is chosen from the compounds of formula (IV):
wherein R13 is an optionally substituted alkyl, alkenyl, aryl and aralkyl group, and R14 is a C ₁ to C ₂₂ alkyl, aryl or alkaryl group.

The compound of formula (IV) is a carboxylic acid ester capable of reacting with a tertiary amine to form a quaternary ammonium salt. Compounds of formula (IV) are chosen, for example, from esters of carboxylic acids having a pKa of 3.5 or less. The compound of formula (IV) is preferably chosen from esters of substituted aromatic carboxylic acid, of alpha-hydroxycarboxylic acid and of polycarboxylic acid.

According to one embodiment, the ester is a substituted aromatic carboxylic acid ester of formula (IV) in which R13 is a substituted aryl group. Preferably, R13 is a substituted aryl group having 6 to 10 carbon atoms, preferably a phenyl or naphthyl group, more preferably a phenyl group. R13 is advantageously substituted by one or more groups chosen from carboalkoxy, nitro, cyano, hydroxy, SR ₁₅ and NR ₁₅ R ₁₆ radicals. Each of the R ₁₅ and R ₁₆ groups can be a hydrogen atom or an alkyl or alkenyl group. , aryl or optionally substituted carboalkoxy. Each of the R ₁₅ and R ₁₆ groups advantageously represents the hydrogen atom or an optionally substituted C1 to C22 alkyl group, preferably the hydrogen atom or a C1 to C16 alkyl group _, more preferably the hydrogen atom or a C1 to C10 alkyl group _, even more preferably the hydrogen atom or a C1 to C4 alkyl group. R ₁₅ is preferably a hydrogen atom and R ₁₆ a hydrogen atom or a C1 to C4 group. Advantageously, R ₁₅ and R ₁₆ are both a hydrogen atom.

According to one embodiment, R13 is an aryl group substituted by one or more groups chosen from hydroxyl, carboalkoxy, nitro, cyano and NH ₂ radicals. R13 can be a polysubstituted aryl group, for example trihydroxyphenyl. Advantageously, R13 is a monosubstituted aryl group, preferably ortho-substituted. R13 is, for example, substituted by a group chosen from the radicals OH, NH ₂ , NO ₂ or COOMe, preferably OH or NH ₂ . R13 is preferably a hydroxy-aryl group, in particular 2-hydroxyphenyl.

According to a particular embodiment, R14 is an alkyl or alkylaryl group. R14 can be a C1 to C16 alkyl group_,preferably C1 to C10, advantageously C1 to C8. R14 may be a C1 to C16 alkylaryl group, preferably C1 to_C10,advantageously in C1 to C8. R14 can for example be chosen from methyl, ethyl, propyl, butyl, pentyl, benzyl groups or their isomers. Preferably, R14 is a benzyl or methyl group, more preferably methyl.

A particularly preferred compound is methyl salicylate.

According to a particular embodiment, the compound of formula (IV) is an ester of an alpha-hydroxycarboxylic acid corresponding to the following formula (V):
wherein R17 and R18 are the same or different and are independently selected from the group consisting of hydrogen, alkyl, alkenyl, aryl or aralkyl groups. Such compounds are for example described in the document EP 1254889.

Examples of compounds of formula (IV) in which R13COO is the residue of an alpha-hydroxycarboxylic acid include methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, phenyl-, benzyl- or allyl- 2-hydroxy-isobutyric acid esters; the methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl-esters of 2-hydroxy-2-methylbutyric acid; the methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl-esters of 2-hydroxy-2-ethylbutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl- or allyl-esters of lactic acid and methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl -, allyl-, benzyl- or phenyl-esters of glycolic acid. Of the above, the preferred compound is methyl-2-hydroxyisobutyrate.

According to a particular embodiment, the compound of formula (IV) is an ester of a polycarboxylic acid chosen from dicarboxylic acids and carboxylic acids having more than two acid functions. The carboxylic functions are preferably all in esterified form. Preferred esters are C1 to C4 alkyl esters.

The compound of formula (IV) can be chosen from oxalic acid diesters, phthalic acid diesters, maleic acid diesters, malonic acid diesters or citric acid diesters. Preferably, the compound of formula (IV) is dimethyl oxalate.

According to a preferred variant, the compound of formula (IV) is a carboxylic acid ester having a pKa of less than 3.5. For cases where the compound comprises more than one acid group, reference will be made to the first dissociation constant.

The compound of formula (IV) can be chosen from one or more carboxylic acid esters chosen from oxalic acid, phthalic acid, salicylic acid, maleic acid, malonic acid, citric acid , nitrobenzoic acid, aminobenzoic acid and 2,4,6-trihydroxybenzoic acid. Preferred compounds of formula (IV) are dimethyl oxalate, methyl 2-nitrobenzoate and methyl salicylate.

According to a particularly preferred embodiment, the quaternary ammonium salt used in the invention is formed by reaction of a hydrocarbon epoxide, preferably chosen from those of formula (III) above and more preferably propylene oxide , with the reaction product of a polyisobutenyl succinic anhydride whose polyisobutylene (PIB) group has a number-average molecular weight (Mn) of between 700 and 1000 and dimethyl-aminopropylamine.

The composition according to the invention comprises the first additive(s) as described above at a preferential content ranging from 5 to 1000 ppm, preferably from 10 to 500 ppm, and more preferentially from 50 to 200 ppm by weight, relative to the total weight of the composition.

The second additive (phenolic antioxidant):

The composition according to the invention comprises a second additive consisting of an antioxidant chosen from compounds comprising a phenol group in their structure.

Suitable antioxidants are selected from 2,6-di-t-butyl 4-methylphenol (BHT), t-butyl hydroquinone (TBHQ), 2,6 and 2,4-di-t-butyl phenol, 2,4-dimethyl-6-t-butyl phenol, pyrogallol, tocopherol, 4,4'- methylene bis (2,6-di-t-butyl phenol) (CAS No. 1 18-82 -1), alone or in a mixture.

The particularly preferred antioxidants are chosen from alkyl phenols such as in particular 2,6-di-t-butyl-4-methylphenol (BHT).

The composition according to the invention comprises the second additive(s) as described above at a preferential content ranging from 2 to 500 ppm, preferably from 5 to 250 ppm, and more preferentially from 10 to 150 ppm by weight, relative to the total weight of the composition.

Other additives:

The composition according to the invention may also comprise one or more additional additives, different from the first and second additives as described above.

According to a preferred embodiment, the composition also comprises one or more amine antioxidant agents, which can be chosen in particular from aliphatic, cycloaliphatic and aromatic amines. Dicyclohexylamine is particularly preferred.

The amine antioxidant(s) may be present in a content ranging from 0.2 to 50 ppm, preferably from 0.5 to 25 ppm, and more preferably from 1 to 20 ppm by weight, relative to the total weight of the composition.

According to another preferred embodiment, the composition also comprises one or more metal passivating agents, chosen from triazole derivatives, alone or as a mixture.

The term “triazole derivatives” means all the compounds comprising a triazole unit, that is to say a 5-membered aromatic cyclic unit comprising two double bonds and 3 nitrogen atoms. Depending on the position of the nitrogen atoms, a distinction is made between 1,2,3-triazole units (called V-triazoles) and 1,2,4-triazole units (called S-triazoles). By way of example of triazole units, mention may be made of benzotriazole or tolyltriazole.

The metal passivating agent(s) are preferably chosen from amines substituted with triazole groups, alone or as a mixture. The term "triazole group" means any substituent containing a triazole unit as defined above.

The metal passivating agent(s) are more preferably chosen from N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine (CAS 91273-04-0) and N,N′-bis-(2-ethylhexyl)-4-methyl-1H-benzotriazole amine (CAS 80584-90-3), alone or as a mixture.

Mention may also be made of the passivating agents described on page 5 of application US2006/0272597.

The metal passivating agent(s) may be present in a content ranging from 0.2 to 50 ppm, preferably from 0.5 to 25 ppm, and more preferably from 1 to 15 ppm by weight, relative to the total weight of the composition.

According to another preferred embodiment, the composition also comprises one or more chelating agents (or metal sequestering agents), which can be chosen in particular from amines substituted by Ν,Ν'-disalicylidene groups, such as Ν, Ν'-disalicylidene 1,2-diaminopropane (DMD).

The chelating agent(s) may be present in a content ranging from 0.1 to 100 ppm, preferably from 0.2 to 50 ppm, and more preferably from 0.5 to 20 ppm by weight, even more preferably from 0.5 at 10 ppm by weight, relative to the total weight of the composition.

The composition according to the invention may also comprise one or more other additives commonly used in fuels, different from the additives described above.

The composition may typically comprise one or more other additives chosen from detergents, anti-corrosion agents, dispersants, demulsifiers, tracers, biocides, reodorants, procetane additives, friction modifiers, additives of lubricity or lubricity additives, combustion aids (catalytic soot combustion promoters), anti-wear agents and/or conductivity modifiers.

Among these additives, mention may be made in particular of:
a) procetane additives, in particular (but not limited to) chosen from alkyl nitrates, preferably 2-ethyl hexyl nitrate, aryl peroxides, preferably benzyl peroxide, and alkyl peroxides, preferably tert-butyl peroxide;
b) lubricity additives or anti-wear agents, in particular (but not limited to) chosen from the group consisting of fatty acids and their ester or amide derivatives, in particular glycerol monooleate, and derivatives of mono- and polycyclic. Examples of such additives are given in the following documents: EP680506, EP860494, WO98/04656, EP915944, FR2772783, FR2772784,
c) demulsifying additives, for example (but not limited to) chosen from oxyalkylated alkyl phenolic resins (for example the compound CAS63428-92-2)
d) detergents.

According to a preferred embodiment, the composition comprises at least one detergent additive chosen from the triazole derivatives of formula (VI) below:
in which
- R14 is chosen from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group C1 to C8, preferably C1 to C4, more preferably C1 to C2, linear or branched and a carboxyl group (-CO2H). Preferably R14 is hydrogen;
- R16 and R17 are identical or different and represent, independently of each other, a group chosen from the group consisting of a hydrogen atom and an aliphatic hydrocarbon group, linear or branched, saturated or unsaturated, cyclic or acyclic having from 2 to 200 carbon atoms, preferably from 14 and 200 carbon atoms, more preferably from 50 to 170 carbon atoms, even more preferably between 60 and 120 carbon atoms.

It should be noted that we apply the conventional rules of representation (dotted bond and loose bond) to indicate that the position of the hydrogen atom and the double bond in the triazole ring can change, said formula thus covering both possible positions.

According to a particular embodiment, the triazole derivative has the formula (VI) in which R16 and R17 are identical or different and represent, independently of each other, a group chosen from the group consisting of an atom of hydrogen and an aliphatic hydrocarbon group having a number-average molecular weight (Mn) of between 200 and 3000, preferably between 400 and 3000, more preferably between 400 and 2500, even more preferably between 400 and 1500 or between 500 and 1500. aliphatic hydrocarbon group is preferably a polyisobutylene group (or also called polyisobutene noted GDP) having a number-average molecular weight (Mn) of between 200 and 3000, preferably between preferably between 5400 to 3000, more preferably between 400 to 2500 , even more preferably between 400 and 1500 or between 500 and 1500. According to a particularly preferred embodiment, R16 and R17 respectively represent an atom me of hydrogen and a PIB group as described above or vice versa.

According to a preferred embodiment, the composition of the invention does not contain any antifoam additive. Indeed, the good intrinsic properties of the composition according to the invention make the addition of such an additive unnecessary. For the record, examples of anti-foam additives are in particular (but not limited to) polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides derived from vegetable or animal oils. Examples of such additives are given in EP861882, EP663000, EP736590.

Uses:

The present invention also relates to the use of an additive composition comprising at least one first additive and at least one second additive as described above, to improve at least one property of a fuel composition comprising at least 85 % by weight of one or more hydrocarbon cuts having a distillation range comprised in the range extending from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight.

The improved property or properties are advantageously chosen from the following: conductivity, corrosion resistance, oxidation stability, and detergency.

Said first and second additives are as described above. Such a composition of additives may also further comprise one or more additional additives, as described above, and in particular:
- one or more amino antioxidants as described above;
- one or more metal passivating agents, chosen from the triazole derivatives as described above;
- one or more chelating agents as described above.

A particularly preferred additive composition includes the following compounds:
- a quaternary ammonium salt formed by reaction of propylene oxide with the reaction product of a polyisobutenyl-succinic anhydride whose polyisobutylene group (PIB) has a number-average molecular mass (Mn) of between 700 and 1000 and dimethyl-aminopropylamine;
- di-t-butyl-2,6-methyl-4-phenol;
- dicyclohexylamine;
- N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine; and
- Ν,Ν'-disalicylidene 1,2-diaminopropane.

The present invention finally relates to the use of a composition as described above as fuel supplying a diesel engine, particularly in a stationary machine or a vehicle equipped with a diesel engine, and more particularly as fuel in a vehicle diesel automobile. The composition according to the invention can be used in particular in the following different vehicles: light vehicles, heavy goods vehicles (trucks with different loads called “medium duty” and “heavy duty”, refuse collection vehicles, buses, coaches, etc.) and non-road vehicles (construction or public works machinery, tractors, trains, boats).

The examples below are given by way of illustration of the invention, and cannot be interpreted in such a way as to limit its scope.

The examples below were made from a paraffinic hydrocarbon cut (hereinafter cut C1) consisting of a hydrotreated vegetable oil (HVO) whose characteristics are detailed in Table I below: Characteristic Method Value Density at 15°C ISO 12185 779.9 kg/ ^m3 Viscosity at 40°C ISO 3104 2.9 mm ² /s Cloud point (PTR)° ASTM D7346 -36°C Filterability limit temperature (TLF) EN 116 -39°C Distillation profile ISO 3405 Starting point 216.0°C Dot at 5% vol. 252.4°C Dot at 10% vol. 262.1°C Dot at 20% vol. 269.8°C Dot at 30% vol. 273.4°C Dot at 40% vol. 275.7°C Dot at 50% vol. 277.8°C Dot at 60% vol. 279.7°C Dot at 70% vol. 282.1°C Dot at 80% vol. 285.0°C Point at 90% vol. 289.2°C Point at 95% vol. 293.0°C Period 304.3°C volume distilled 98.6ml Residue 1.3ml Losses 0.1ml Aromatic content EN12916 0% by weight

This hydrocarbon cut consists of 99.9% by weight of paraffins, including 92.6% of iso-paraffins (hereinafter i-paraffins) and 7.3% by weight of n-paraffins.

Its exact composition is detailed in Table II below: Number of atoms of C n-paraffins i-paraffins naphthenes i-naphthenes 7 2.35 0.39 8 0.09 0.20 0.01 9 0.16 0.43 0.01 10 0.17 0.80 0.01 11 0.14 0.84 12 0.13 0.99 13 0.15 1.02 14 0.86 1.54 0.01 0.01 15 9.55 0.01 0.05 16 2.43 31.15 0.01 17 14.22 18 0.80 30.71 0.02 19 0.23 0.01 20 0.01 0.31 21 0.03 22 0.06 23 0.02 24 0.01 27 0.08 Total 7.29 92.56 0.03 0.12

1. formé par réaction de l’oxyde de propylène avec le produit de la réaction d'un anhydride polyisobutényl-succinique dont le groupement polyisobutylène (PIB) a une masse moléculaire moyenne en nombre (Mn) de 1000 g/mol et de la diméthyl-aminopropylamine.
2. composition d’additif constituée de di-t-butyl-2,6 méthyl-4 phénol ; dicyclohexylamine ; N,N-bis(2-éthylhexyl)-[(1,2,4-triazol-1-yl)méthyl]amine ; et Ν,Ν'-disalicylidène 1,2-diaminopropane.
3. acide (tétrapropenyl) succinique.

Fuel compositions were prepared by adding to cut C1 above the mixtures of additives detailed in Table III below, in which the content of each additive is indicated in ppm by weight relative to the total weight of the final composition. Additive Mixture 1 (MEL1) Blend 2 (MEL2) Quaternary ammonium salt 1 100 137 Membership 2 150 164 Anti-corrosion additive 3 0 5

1. formed by reaction of propylene oxide with the reaction product of a polyisobutenyl-succinic anhydride whose polyisobutylene group (PIB) has a number-average molecular mass (Mn) of 1000 g/mol and dimethyl-aminopropylamine .
2. additive composition consisting of 2,6-di-t-butyl-4-methylphenol; dicyclohexylamine; N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine; and Ν,Ν'-disalicylidene 1,2-diaminopropane.
3. (tetrapropenyl) succinic acid.

The properties of the C1 hydrocarbon cut, before and after addition of each of the above additive mixtures, were evaluated.

Corrosion resistance :

The method used to evaluate the resistance to corrosion is that described in standard ASTM D665A (standard described in relation to lubricants but applicable to fuels). The principle is as follows: a steel test piece is immersed in a beaker filled to 90% volume with the fuel to be evaluated and 10% volume of fresh water. The solution is stirred continuously, and the beaker is heated to 60°C. After 24 hours, the specimen is observed in order to assess the corrosion present on the surface of the specimen.

The corrosion rating is made by assigning a note in the form of a letter ranging from A to E, A meaning absence of corrosion, and E corresponding to the maximum degree of oxidation.

The results obtained are detailed in Table IV below: Composition C1 C1 + MEL1 C1+MEL2 Freshwater CorrosionASTM D665A E AT AT

These results show that the C1 cut has a very poor resistance to corrosion, and that the compositions in accordance with the invention (C1 + MEL 1 and C1 + MEL2) make it possible to improve this property very significantly, including in the absence of any anti-corrosion additive (C1 + MEL1)

Conductivity :

The conductivity tests were carried out in accordance with the method described in standard ISO 6297. The results obtained are detailed in table V below: Composition C1 C1 + MEL1 C1+MEL2 Conductivity in pS.m ^-1 ISO 6297 40 351 459

These results show that the C1 cut has a very mediocre conductivity, and that the compositions in accordance with the invention (C1 + MEL 1 and C1 + MEL2) make it possible to improve this property very significantly.

Oxidation stability:

The method used to assess oxidation stability is the so-called Rancimat method, as described in standard EN 15751.

The test consists of accelerating the aging process of the sample by exposing it to heat and the passage of large quantities of air. It measures the time required for the oxidation of the product and defines the oxidation stability time. The result obtained is expressed in hours. The longer the time, the more stable the fuel to oxidation.

The results obtained are detailed in Table VI below: Composition C1 C1 + MEL1 C1+MEL2 RancimatEN 15751 12 p.m. >80h >80h

These results show that the C1 cut has very poor stability (it oxidizes rapidly), and that the compositions in accordance with the invention (C1 + MEL 1 and C1 + MEL2) make it possible to improve this property very significantly.

Detergency:

Performance in terms of detergency was evaluated using the XUD9 engine test, consisting in determining the loss of flow defined as corresponding to the restriction of the flow of a diesel fuel emitted by the injector of a diesel engine with a prechamber during its operation, according to the CEC F-23-1-01 standardized engine test method. The objective of this test is to assess the ability of the composition of additives tested to reduce deposits on the injectors of a Peugeot XUD9 A/L four-cylinder engine with diesel pre-chamber injection.

The tests were carried out with a four-cylinder Peugeot XUD9 A/L diesel pre-chamber injection engine equipped with clean injectors whose flow rate was determined beforehand.

The engine follows the test cycle detailed in the following table VII repeated 134 times for a total duration of 10 hours and 3 minutes: Stage Duration(s) Speed (rpm) Torque(Nm) 1 30 1200±30 10 ± 2 2 60 3000±30 50 ±2 3 60 1300±30 35 ± 2 4 120 1850±30 50 ± 2

The test conditions are as follows:
Coolant flow (stage 2 only): 85 ± 5 l/min
Temperatures:
- Coolant outlet: 95 ± 2°C
- Oil: 100 ± 5°C
- Air inlet: 32 ± 2°C
- Fuel (at the pump): 31 ± 2°C
Pressures:
- At the fuel pump inlet: -50 to + 100 mbar
- At the fuel pump outlet: -100 to + 100 mbar
- Exhaust discharge pressure (stage 2 only): 50 ± 10 mbar
- air inlet: 950 ± 10 mbar.

The following two consecutive phases were carried out, with the same test method for each phase:
- Phase 1 of clogging (or "dirty up") with a conventional type B7 diesel fuel, in accordance with the EN 590 standard. The loss of flow evaluated after this first phase is 80%.
- Phase 2 of cleaning (or "clean up") with the candidate fuel.

At the end of the test, the flow rate of the injectors is evaluated again. The loss of flow is measured on the four injectors. The results are expressed as percentage loss of flow for different needle lifts. Usually we compare the fouling values at 0.1 mm of needle lift because they are more discriminating and more precise and repeatable (repeatability < 5%). The evolution of the loss of flow before / after the test makes it possible to deduce the loss of flow as a percentage. Given the repeatability of the test, a significant detergent effect can be confirmed for a reduction in flow loss, ie a gain in flow greater than 10 points (>10%).

The results obtained are detailed in Table VIII below: Composition C1 C1+MEL2 Flow loss (%) 59 0

The above results show that the composition according to the invention leads to very good detergency results, in terms of cleaning clogged injectors (“clean-up” effect).

Claims (26)

Fuel composition comprising:
- at least 85% by weight of one or more paraffinic hydrocarbon cuts having a distillation range comprised in the range extending from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight;
- at least one first additive consisting of a quaternary ammonium salt, obtained by reaction with a quaternizing agent of a nitrogen compound comprising a tertiary amine function, this compound being the product of the reaction of an acylation agent substituted by a hydrocarbon group and by a compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols; and
- at least one second additive consisting of an antioxidant chosen from compounds comprising a phenol group. Composition according to the preceding claim, characterized in that the distillation range of the said paraffinic hydrocarbon cut is comprised in the range going from 130 to 350°C, preferably from 150 to 320°C. Composition according to any one of the preceding claims, characterized in that the paraffin content of the said paraffinic hydrocarbon cut is greater than or equal to 95% by weight, preferably greater than or equal to 99% by weight, more preferably greater than or equal to equal to 99.5% by weight, better still greater than or equal to 99.9% by weight, relative to the total weight of said cut. Composition according to any one of the preceding claims, characterized in that the paraffins present in the said cut of paraffinic hydrocarbons consist of at least 60% by weight, preferably of at least 80% by weight and even better of at least 90 % by weight of paraffins comprising from 12 to 18 carbon atoms, preferably from 14 to 18 carbon atoms, and even better from 15 to 18 carbon atoms. Composition according to any one of the preceding claims, characterized in that of the said paraffinic hydrocarbon cut contains at least 50% by weight of iso-paraffins, preferably at least 70% by weight, and better still at least 90% by weight of iso-paraffins, relative to the weight of said cut. Composition according to any one of the preceding claims, characterized in that the paraffin hydrocarbon cut or cuts are hydrotreated vegetable oils. Composition according to any one of the preceding claims, characterized in that it comprises at least 90% by weight of the paraffinic hydrocarbon cut or cuts, preferably at least 93% by weight. Composition according to the preceding claim, characterized in that it comprises at least 95% by weight of the paraffinic hydrocarbon cut or cuts, preferably at least 99% by weight, and better still at least 99.5% by weight. Composition according to any one of the preceding claims, characterized in that the acylating agent of the said first additive is chosen from mono- or poly-carboxylic acids and their derivatives, in particular their ester, amide or anhydride derivatives, and preferably the acylating agent is chosen from succinic, phthalic and propionic acids and the corresponding anhydrides. Composition according to any one of the preceding claims, characterized in that the hydrocarbon substituent of the acylation agent comprises from 8 to 200 carbon atoms. Composition according to any one of the preceding claims, characterized in that the acylation agent substituted by a hydrocarbyl group is a polyisobutenyl-succinic anhydride. Composition according to any one of the preceding claims, characterized in that the said compound comprising at least one tertiary amine group and at least one group chosen from primary amines, secondary amines and alcohols is chosen from the amines of formula (I) or (II) following:
(I)
(II)
in which :
R6 and R7 are identical or different and represent, independently of each other, an alkyl group having from 1 to 22 carbon atoms;
X is an alkylene group having 1 to 20 carbon atoms;
m is an integer between 1 and 5;
n is an integer between 0 and 20; and
R8 is a hydrogen atom or a C1 to C22 alkyl group;
and preferably from the amines of formula (I). Composition according to any one of the preceding claims, characterized in that the quaternizing agent is chosen from the group consisting of dialkyl sulphates, carboxylic acid esters; alkyl halides, benzyl halides, hydrocarbon carbonates, and hydrocarbon epoxides optionally mixed with an acid, alone or as a mixture, preferably from hydrocarbon epoxides, more preferably from styrene oxide and oxide propylene and better still the quaternizing agent is propylene oxide. Composition according to any one of the preceding claims, characterized in that it comprises the first additive or additives at a content ranging from 5 to 1000 ppm, preferably from 10 to 500 ppm, and more preferably from 50 to 200 ppm by weight , relative to the total weight of the composition. Composition according to any one of the preceding claims, characterized in that the second additive is chosen from alkyl phenols, and preferably the second additive is 2,6-di-t-butyl-4-methylphenol. Composition according to any one of the preceding claims, characterized in that it comprises the second additive(s) at a content ranging from 2 to 500 ppm, preferably from 5 to 250 ppm, and more preferably from 10 to 150 ppm by weight , relative to the total weight of the composition. Composition according to any one of the preceding claims, characterized in that it additionally comprises one or more amino antioxidants chosen from aliphatic, cycloaliphatic and aromatic amines, and preferably dicyclohexylamine. Composition according to the preceding claim, characterized in that the amino antioxidant(s) are present in a content ranging from 0.2 to 50 ppm, preferably from 0.5 to 25 ppm, and more preferably from 1 to 20 ppm by weight, relative to the total weight of the composition. Composition according to any one of the preceding claims, characterized in that it additionally comprises one or more metal passivating agents chosen from amines substituted with triazole groups, and more preferably from N,N-bis(2-ethylhexyl )-[(1,2,4-triazol-1-yl)methyl]amine and N,N'-bis-(2-ethylhexyl)-4-methyl-1H-benzotriazoleamine, alone or as a mixture. Composition according to the preceding claim, characterized in that the metal passivating agent(s) are present in a content ranging from 0.2 to 50 ppm, preferably from 0.5 to 25 ppm, and more preferably from 1 to 15 ppm in weight, relative to the total weight of the composition. Composition according to any one of the preceding claims, characterized in that it additionally comprises one or more chelating agents, preferably chosen from amines substituted by Ν,Ν'-disalicylidene groups, and more preferably Ν,Ν' -disalicylidene 1,2-diaminopropane. Composition according to the preceding claim, characterized in that the chelating agent or agents are present in a content ranging from 0.1 to 100 ppm, preferably from 0.2 to 50 ppm, and more preferably from 0.5 to 20 ppm in weight, and even more preferably from 0.5 to 10 ppm by weight, relative to the total weight of the composition Use of an additive composition comprising at least one first additive and at least one second additive as defined in any one of Claims 1, 9 to 13 and 15 for improving at least one property of a fuel composition comprising at least 85% by weight of one or more hydrocarbon cuts having a distillation range comprised in the range extending from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight. Use according to the preceding claim, characterized in that the composition of additives additionally comprises:
- one or more amino antioxidants chosen from aliphatic, cycloaliphatic and aromatic amines, and preferably dicyclohexylamine;
- one or more metal passivating agents chosen from amines substituted with triazole groups, and more preferably from N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl] amine and N,N′-bis-(2-ethylhexyl)-4-methyl-1H-benzotriazole amine, alone or as a mixture; and
- one or more chelating agents, preferably chosen from amines substituted with Ν,Ν′-disalicylidene groups, and more preferably Ν,Ν′-disalicylidene 1,2-diaminopropane. Use of a composition of additives according to either of Claims 23 and 24, to improve at least one of the following properties: conductivity, resistance to corrosion, stability to oxidation, and detergency. Use of a composition as defined in any one of claims 1 to 22 as fuel supplying a diesel engine, particularly in a stationary machine or a vehicle fitted with a diesel engine, and more particularly as fuel in a diesel motor vehicle .