Fuel composition comprising a renewable base and a substituted aniline-type compound

Abstract

The present invention relates to a fuel composition comprising at least 50% by weight, relative to the total weight of the composition, of one or more paraffinic hydrocarbon fractions consisting of fatty acids and / or hydrogenated esters of fatty acids (HEFAs) and at least 0.05% by weight, relative to the total weight of the composition, of one or more compounds selected from among aromatic amines corresponding to formula (I): wherein at least one of groups R2, R3, R4, R5, and R6 denotes an alkoxy group of formula -O-Ra, where Ra denotes a hydrogen atom or a linear or branched alkyl group comprising from 1 to 16 carbon atoms. The composition is useful for powering any internal combustion engine of a land vehicle, watercraft, aircraft or spacecraft, in particular an aircraft or rocket engine.

Description

[0001] DESCRIPTION

[0002] TITLE: Fuel composition comprising a renewable base and a substituted aniline-type compound

[0003] The present invention relates to a fuel composition usable among other things in air transport, and which comprises one or more cuts made up of fatty acids and / or esters of hydrogenated fatty acids in association with at least one compound chosen from among the substituted anilines of particular formula defined below.

[0004] The present invention also relates to the use of such a composition to power a heat engine, such as, in particular but not limited to, an aircraft or rocket engine.

[0005] PREVIOUS STATE OF THE ART

[0006] Fuels used in aeronautics and space propulsion are subject to very strict regulations designed to ensure a high level of safety during their use.

[0007] Thus, the turbine engines (turbojets and turboprops) that equip the majority of airplanes and helicopters (civilian or military) use specific fuels called jet fuels, which are traditionally formulated from hydrocarbon cuts called kerosene cuts from the distillation of crude oils.

[0008] The reference and most widely used jet fuel for civil aviation is Jet A-1. Its properties are defined in the international standard ASTM D 1655. The physical characteristics of this fuel meet the efficiency and safety criteria required in the field of air transport, both for ground operations and flight phases. The main properties are:

[0009] - A high calorific value, of at least 42.8 MJ / kg. This represents the amount of energy released per unit mass of fuel during combustion. This value is very important because it gives the aircraft greater range for a constant onboard weight. - A very low freezing point, which must be below -47°C, allowing the fuel to remain in a liquid state when the aircraft is in cruise flight, in a very low-temperature environment.

[0010] - A flash point (or temperature above which fuel vapors can ignite in the presence of a flame), which must be above 38°C, in order to ensure safe handling of fuel on the ground.

[0011] Other properties such as sulfur content, acidity or fuel density are also defined in ASTM D 1655.

[0012] The fight against climate change now requires air transport to reduce its fossil fuel carbon dioxide emissions by adopting low-environmental-impact fuels, also known as sustainable aviation fuels (SAFs). A promising solution is to replace fossil-based kerosene with bio-based fuels, such as those derived from the hydrogenation of natural esters and fatty acids, known as Hydrogenated Esters and Fatty Acids (HEFAs). Indeed, fuels formulated from these bases have characteristics relatively close to Jet A1c, making HEFAs excellent candidates for the aeronautical industry.

[0013] However, these HEFA bases are essentially composed of linear and branched paraffins (alkanes). Their chemical composition, devoid of aromatic and naphthenic hydrocarbons, gives them a significantly lower auto-ignition temperature than traditional jet fuels based on fossil-derived kerosene, which leads to significant safety problems, particularly fire risks when using the fuel in the hot parts of aircraft and rocket engines.

[0014] It is therefore desirable to increase the auto-ignition temperature of this type of biofuel, particularly to enable their use in the aeronautical and aerospace industries. Auto-ignition temperature is a static property of a fuel, indicating the temperature at which an air-fuel mixture spontaneously ignites at atmospheric pressure. It cannot be correlated with other fuel combustion parameters such as:

[0015] The R-Octane ratings for research and engine (RON / MON) represent a fuel's resistance to knocking under defined and standardized controlled ignition conditions. These are empirical measurements taken from tests performed in laboratory engines known as CFR engines (Cooperative Fuel Research engines), under specific and standardized operating conditions; and

[0016] - The ignition delay of a fuel in the engine, which is a dynamic property representing the time elapsed between the end of compression and ignition in a running engine. This property depends strongly on the engine's operating conditions, particularly temperature, pressure, and fuel / air ratio.

[0017] The auto-ignition temperature of a fuel is measured according to the ASTM E659 standard, the implementation conditions of which are extremely different from those of the two previous parameters.

[0018] One solution to the problem of insufficient auto-ignition temperature in HEFA fuels is to add one or more fuel bases rich in aromatic and / or naphthenic hydrocarbons. However, available aromatic and / or naphthenic fuel bases are most often derived from fossil fuels, which are non-renewable. Furthermore, these bases are available in small quantities, are expensive, and require high blending rates to have a significant effect on the auto-ignition temperature.

[0019] Furthermore, due to their different chemical composition compared to fossil-based kerosenes, HEFA fuels also present compatibility issues with certain materials used in the components with which the fuel comes into contact. This stems from the fact that these fuels are primarily composed of paraffins. Consequently, they pose problems for use in current aircraft, particularly related to their poor compatibility with the materials used in fuel system seals. One possible solution to this problem is to add an aromatic base to the paraffinic base. (Article - Kramer S, Andac G, Heyne J, Ellsworth J, Herzig P and Lewis KC (2022) Perspectives on Fully Synthesized Sustainable Aviation Fuels: Direction and Opportunities. Front. Energy Res. 9:782823. doi: 10.3389 / fenrg.2021.)782823 - thus presents the probable production routes for so-called "100% drop-in" SAFs, by mixing paraffinic and aromatic bases. However, even if aromatic compounds improve the fuel's compatibility with aeronautical seals, they have a negative impact on combustion emissions, mainly on the formation of fine particles and the presence of trails.

[0020] The present invention aims to remedy the problems described above.

[0021] The present invention thus aims to propose new jet fuel compositions derived from renewable feedstocks, exhibiting improved combustion quality compared to existing jet fuel compositions, while preserving, or even improving at least one of their chosen properties among their auto-ignition temperature, their compatibility with materials, in particular those constituting aeronautical seals, and their environmental impact.

[0022] The present invention aims in particular to propose a fuel composition based on fatty acids and / or hydrogenated fatty acid esters (HEFA), which has an increased auto-ignition temperature without having to use bases rich in aromatic and / or naphthenic hydrocarbons in large quantities.

[0023] The Applicant has now discovered that the addition, to a fuel base consisting of fatty acids and / or esters of hydrogenated fatty acids, of one or more compounds chosen from among the substituted anilines of formula (I) defined below, in a minimum content of 0.05% by mass, made it possible to significantly increase the auto-ignition temperature of the mixture while exhibiting good compatibility with the materials used in parts in contact with jet fuels, and thus to formulate a durable fuel suitable for use in the aeronautical and aerospace industries.

[0024] The present invention thus relates to a fuel composition comprising: a) at least 50% by mass, relative to the total mass of the composition, of one or more paraffinic hydrocarbon cuts consisting of fatty acids and / or hydrogenated fatty acid esters (HEFAs); and b) at least 0.05% by mass, relative to the total mass of the composition, of one or more compounds corresponding to formula (I) below: in which

[0025] - Ri designates a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms;

[0026] - The groups R2, R3, R4, Rs, and RÔ, whether identical or different, independently designate a hydrogen atom; an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms; or an alkoxy group with the formula -OR a with R adesignating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a .

[0027] The composition according to the invention exhibits a significantly higher auto-ignition temperature, measured in accordance with ASTM E659, than a composition comprising the same bases with the exception of the compound(s) of formula (I). Thus, the compound(s) of formula (I) can be used to increase the auto-ignition temperature of a fuel composition, particularly a fuel composition for powering aircraft and rocket engines.

[0028] This increase in the auto-ignition temperature results in a reduced risk of fire when using the composition as fuel, even at high temperatures such as those found in aircraft and rocket engines. This reduced risk of fire advantageously enhances the safety of internal combustion engines, particularly aircraft and rocket engines.

[0029] While the auto-ignition temperature measured according to ASTM E659 of a fuel composition consisting solely of fatty acids and / or hydrogenated fatty acid esters (HEFAs) is sometimes less than 200°C, the auto-ignition temperature (measured according to the same standard) of the composition according to the invention is at least 200°C. Preferably, the auto-ignition temperature of the composition according to the invention is greater than or equal to 210°C and more preferably greater than or equal to 220°C.

[0030] This temperature is achieved without having to add significant amounts of fuel base rich in aromatic and / or naphthenic hydrocarbons.

[0031] Thus, according to a preferred embodiment, the aromatic hydrocarbon content of the composition according to the invention is less than 5% by mass, preferably less than 2% by mass, more preferably less than 1% by mass, relative to the total mass of the composition.

[0032] Aromatic hydrocarbons are defined here as aromatic compounds consisting solely of carbon and hydrogen atoms, and devoid of heteroatoms. In particular, the compounds of formula (I) defined above do not constitute aromatic hydrocarbons within the meaning of the present invention.

[0033] According to a preferred embodiment, the naphthenic hydrocarbon content of the composition according to the invention is less than 5% by mass, relative to the total mass of the composition.

[0034] According to a particularly preferred embodiment, the total content of naphthenic hydrocarbons and aromatic hydrocarbons of the composition according to the invention is less than 5% by mass, preferably less than 4% by mass, relative to the total mass of the composition.

[0035] The composition according to the invention also exhibits excellent compatibility with the materials used in aircraft parts, and in particular with the constituent materials of sealing gaskets such as, for example, elastomers.

[0036] The paraffinic hydrocarbon fraction(s) consisting of fatty acids and / or hydrogenated fatty acid esters (HEFAs) are bases of biological origin. Thus, the composition according to the invention comprises a majority of bio-based materials. It therefore has a high eco-material content. The mass content of eco-material in the composition is defined by the following equation: Eco-material content in % = 100 - (percentage of non-bio-based, non-biodegradable, non-recycled materials).

[0037] According to an advantageous embodiment, the composition has an eco-material content of at least 70% by mass, preferably at least 80% by mass, preferably at least 90% by mass, and more preferably at least 95% by mass, relative to the total mass of the composition.

[0038] The composition according to the invention also exhibits good properties in terms of calorific value, freezing point, flash point and cetane number.

[0039] It is perfectly suited for use as fuel to power aircraft and rocket engines, but also more generally to power any internal combustion engine used in propulsion, whether on land, sea, air or space.

[0040] Thus, the present invention also relates to the use of the composition according to the invention to power an internal combustion engine of a land, sea, air or space propulsion vehicle, and preferably an aircraft or rocket engine.

[0041] Other objects, features, aspects and advantages of the invention will become even clearer upon reading the description and examples that follow.

[0042] In what follows, and unless otherwise indicated, the boundaries of a range of values ​​are included in that range, in particular in the expressions "between" and "ranging from ... to ...".

[0043] Furthermore, the expressions "at least one" and "at least" used in this description are respectively equivalent to the expressions "one or more" and "greater than or equal to".

[0044] Finally, in a manner known in itself, a compound or group in CN is designated as a compound or group containing in its chemical structure N carbon atoms.

[0045] DETAILED DESCRIPTION

[0046] The paraffinic hydrocarbon cut (a)

[0047] The composition according to the invention contains at least one cut of paraffinic hydrocarbons consisting of fatty acids and / or hydrogenated fatty acid esters (HEFA).

[0048] As is well known, these cuts commonly referred to as HEFA are mostly made up of paraffins, derived from the hydrogenation of fatty acids and fatty acid esters.

[0049] A fatty acid is defined as a carboxylic acid comprising a hydrocarbon chain having 6 to 30 carbon atoms, preferably 7 to 24 carbon atoms, and more preferably 8 to 20 carbon atoms.

[0050] Fatty acid ester refers to both monoesters and polyesters (especially di- and tri-esters) of the above fatty acids with an alcohol which can be a mono-alcohol or a polyol.

[0051] According to a preferred embodiment, the paraffinic hydrocarbon fraction(s) (a) consist of hydrotreated vegetable oils, also known as HVOs (from the English "hydrotreated vegetable oils"). These are oils of vegetable origin that have undergone successive treatments including hydrotreatment and possibly isomerization. The processes for preparing such hydrotreated vegetable oils are known per se.

[0052] Examples of suitable plant-based 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.

[0053] Patent applications WO2016 / 185046 and WO2016 / 185047 describe non-limiting examples of methods for obtaining hydrotreated vegetable oil cuts usable as fuel bases.

[0054] The paraffinic hydrocarbon cut(s) (a) have a distillation range advantageously within the range of 60 to 350°C, preferably 100 to 300°C, more preferably 120 to 290°C and better still 140 to 280°C.

[0055] The distillation range of said paraffinic hydrocarbon cut is determined in accordance with standard NF EN ISO 3405.

[0056] The paraffinic hydrocarbon cut(s) (a) advantageously have a paraffin content greater than or equal to 90% by mass, preferably greater than or equal to 95% by mass, relative to the total mass of the cut(s) (a).

[0057] The term "paraffins" refers, in a way that is well known, to branched alkanes (also called iso-paraffins or iso-alkanes) and unbranched alkanes (also called n-paraffins or n-alkanes).

[0058] The paraffins present in the paraffinic hydrocarbon fraction(s) (a) according to the invention advantageously comprise from 6 to 18 carbon atoms, preferably from 8 to 18 carbon atoms. Preferably, the paraffinic hydrocarbon fraction(s) (a) are composed of at least 80% by mass, more preferably at least 90% by mass, and even better at least 95% by mass, of paraffins comprising from 8 to 18 carbon atoms.

[0059] According to a preferred embodiment, the paraffinic hydrocarbon fraction(s) (a) used in the composition according to the invention contain at least 60% by mass, preferably at least 70% by mass, of isoparaffins, relative to the total mass of the fraction(s) (a). According to a particularly preferred embodiment, they contain at least 80% by mass of isoparaffins.

[0060] The paraffinic hydrocarbon cut(s) (a) have an aromatic compound content preferably less than or equal to 10000 ppm by mass, more preferably less than or equal to 1500 ppm by mass, even more preferably less than or equal to 1000 ppm by mass.

[0061] Their naphthenic compound content is preferably less than or equal to 50000 ppm by mass.

[0062] Their sulfur content is advantageously less than or equal to 10 ppm by mass, preferably less than or equal to 5 ppm by mass. Particularly preferred, the paraffinic hydrocarbon cut(s) (a) are totally free of sulfur.

[0063] The composition according to the invention preferably comprises at least 75% by mass of one or more paraffinic hydrocarbon fractions (a) as described above. Preferably, it contains at least 85% by mass of one or more paraffinic hydrocarbon fractions (a), more preferably at least 90% by mass and even better at least 95% by mass, relative to the total mass of the composition.

[0064] According to a preferred embodiment, the composition according to the invention contains at least 95% by mass, preferably at least 98% by mass, and even better at least 99% by mass of one or more paraffin hydrocarbon cuts (a) as described above.

[0065] Compounds of formula (I)

[0066] The composition according to the invention comprises one or more compounds corresponding to the formula (I) below: in which

[0067] - Ri designates a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms;

[0068] - The groups R2, R3, R4, Rs, and RÔ, whether identical or different, independently designate a hydrogen atom; an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms; or an alkoxy group with the formula -OR a with R a designating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a .

[0069] Preferably, in formula (I) the group Ri designates an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even better an alkyl group selected from the methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl (isobutyl), 1-methylpropyl (sec-butyl) and 1,1-dimethylethyl (tert-butyl) groups; and preferably a methyl group or an ethyl group and even more preferably a methyl group.

[0070] Preferably, in formula (I) the groups R2, R3, R4, Rs, and RÔ, whether identical or different, designate independently of each other:

[0071] - a hydrogen atom; or

[0072] - an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even better an alkyl group selected from the methyl and ethyl groups, and even more preferably a methyl group; or - an alkoxy group of formula -OR a with R a designating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even better an alkyl group selected from the methyl and ethyl groups and even more preferably a methyl group, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a .

[0073] According to a preferred embodiment, at least one of the groups R3, R4 and R5 designates a group of formula -OR a .

[0074] According to a more preferred embodiment, the group R4 designates a group of formula -OR a .

[0075] Preferably, in formula (I):

[0076] - the groups R2 and RÔ designate a hydrogen atom;

[0077] - Groups R3, R4, and R5 designate independently of each other:

[0078] - a hydrogen atom; or

[0079] - an alkyl group, linear or branched, comprising from 1 to 4 carbon atoms, preferably an alkyl group selected from the methyl and ethyl groups, and even more preferably a methyl group; or

[0080] - an alkoxy group with the formula -OR a with R adesignating a hydrogen atom or an alkyl group comprising 1 to 4 carbon atoms, preferably an alkyl group chosen from the methyl and ethyl groups and more preferably a methyl group, provided that one of the groups R3, R4 and R5 designates a group of formula -OR a .

[0081] More preferably, in formula (I):

[0082] - the groups R2 and RÔ designate a hydrogen atom;

[0083] - Groups R3 and R5 designate independently of each other:

[0084] - a hydrogen atom; or

[0085] - an alkyl group, linear or branched, comprising from 1 to 4 carbon atoms, preferably an alkyl group chosen from the methyl and ethyl groups and even more preferably a methyl group. ;

[0086] - Group R4 designates an alkoxy group with the formula -OR a with R adesignating a hydrogen atom or an alkyl group comprising 1 to 4 carbon atoms, preferably chosen from the methyl and ethyl groups and even more preferably a methyl group.

[0087] More preferably, in formula (I):

[0088] - the groups R2, R3, R5 RÔ designate a hydrogen atom;

[0089] - Group R4 designates an alkoxy group with the formula -OR a with R a designating a hydrogen atom or an alkyl group comprising 1 to 4 carbon atoms, preferably chosen from the methyl and ethyl groups and even more preferably a methyl group.

[0090] A particularly preferred compound of formula (I) is 4-methoxy-N-methylaniline, also known as N-methyl-para-anisidine, whose structural formula is as follows:

[0091] The compounds of formula (I) may be of natural origin. Advantageously, the eco-material content of the composition is further increased when the compound of formula (I) is obtained from compounds of natural origin.

[0092] Thus, compounds of formula (I) can be used to increase the eco-material content of a fuel composition, in particular a fuel composition intended to power aircraft and rocket engines.

[0093] The composition according to the invention advantageously comprises the compound(s) of formula (I) in a total content of 0.05 to 10% by mass, preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, better 0.5 to 2% by mass and better still 1 to 2% by mass, relative to the total mass of the composition.

[0094] According to a preferred embodiment, the composition according to the invention comprises N-methyl-para-anisidine in a content ranging from 0.05 to 10% by mass, preferably from 0.1 to 5% by mass, more preferably from 0.3 to 3% by mass, better from 0.5 to 2% by mass and better still from 1 to 2% by mass, relative to the total mass of the composition.

[0095] Any possible additives

[0096] The composition according to the invention may further comprise one or more additives, different from the compounds of formula (I) described above.

[0097] This additive or these additives can be chosen, for example, but not limited to, antioxidants, antifreeze, antistatic, corrosion inhibitors, lubricants, cold-weather additives, detergents, and tracer additives. Antioxidant additives are particularly preferred.

[0098] These additives can be incorporated at levels, for each one, ranging from a few ppm to 1000 ppm by mass.

[0099] The use of the composition

[0100] The composition according to the invention is useful as fuel to power any internal combustion engine of a propulsion machine, in particular for land, sea, air or space propulsion.

[0101] The composition according to the invention can in particular be used to power any internal combustion engine in one of the following vehicles: road vehicles including light vehicles (in particular automobiles) and heavy goods vehicles (trucks of different loads known as "medium duty" and "heavy duty", garbage trucks, buses, coaches ...) and non-road vehicles (construction or public works equipment, tractors, trains, boats).

[0102] According to a preferred embodiment, the composition according to the invention is used to power an aircraft or rocket engine.

[0103] According to a particularly preferred embodiment, the composition according to the invention is used to power a turbojet or turboprop in an aircraft, preferably chosen from an airplane and a helicopter (civilian or military), and more preferably an airplane.

[0104] The composition according to the invention can also be used to improve the eco-performance of an internal combustion engine of a land, marine, air or space propulsion vehicle, in particular an aircraft engine or a rocket engine.

[0105] For example, the eco-performance of the internal combustion engine can be the reduction of the environmental impact of the internal combustion engine.

[0106] Indeed, the quantity of compounds of biological origin in the composition according to the invention is significant. As explained above, the quantity of fuel bases rich in aromatic and / or naphthenic hydrocarbons of fossil origin and the quantity of compound formula (I) in the composition according to the invention can be low. Thus, the environmental impact of the composition according to the invention is lower than the environmental impact of a fuel composition of fossil origin. The environmental impact of the internal combustion engine powered by the composition according to the invention is therefore reduced.

[0107] The use of compounds of formula (I)

[0108] The present invention also relates to the use of one or more compounds corresponding to the formula (I) below: in which

[0109] - Ri designates a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms;

[0110] - The groups R2, R3, R4, Rs, and RÔ, whether identical or different, independently designate a hydrogen atom; an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms; or an alkoxy group with the formula -OR a with R a designating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a to increase the auto-ignition temperature of a fuel composition comprising at least 50% by mass, relative to the total mass of the composition, of one or more paraffinic hydrocarbon cuts consisting of fatty acids and / or hydrogenated fatty acid esters (HEFA).

[0111] The auto-ignition temperature is measured in accordance with the method defined in ASTM E659.

[0112] The present invention also relates to the use of one or more compounds corresponding to formula (I) to increase the compatibility with elastomers of a fuel composition comprising at least 50% by mass, relative to the total mass of the composition, of one or more paraffinic hydrocarbon cuts consisting of fatty acids and / or hydrogenated fatty acid esters (HEFA).

[0113] The fuel composition is as described above.

[0114] The compound(s) of formula (I) are advantageously used in a content ranging from 0.05 to 10% by mass, preferably from 0.1 to 5% by mass, more preferably from 0.3 to 3% by mass, better from 0.5 to 2% by mass and better still from 1 to 2% by mass, relative to the total mass of the composition.

[0115] The methods

[0116] The present invention also relates to a method of propulsion of a land, sea, air or space vehicle equipped with at least one internal combustion engine, consisting of supplying said engine with a fuel composition as described above.

[0117] Preferably, said engine is an aircraft or rocket engine, more preferably a turbojet or turboprop engine equipping an airplane or helicopter, and more preferably an airplane.

[0118] The present invention also relates to a method for increasing the auto-ignition temperature (measured in accordance with ASTM E659) of a fuel composition comprising at least 50% by mass of one or more paraffinic hydrocarbon cuts consisting of fatty acids and / or hydrogenated fatty acid esters (HEFA), consisting of adding to said fuel composition one or more compounds corresponding to formula (I) as described above.

[0119] The compound(s) of formula (I) are advantageously added in a content ranging from 0.05 to 10% by mass, preferably from 0.1 to 5% by mass, more preferably from 0.3 to 3% by mass, better from 0.5 to 2% by mass and better still from 1 to 2% by mass, relative to the total mass of the composition.

[0120] The examples below are given as an illustration of the invention, and should not be interpreted in such a way as to limit its scope.

[0121] EXAMPLES

[0122] The following examples were prepared using a paraffinic hydrocarbon fraction designated fraction A, consisting of esters and hydrogenated fatty acids (HELA). More specifically, fraction A consists of a hydrotreated vegetable oil (HVO) whose characteristics are detailed in Table I below:

[0123] [Table I]

[0124] 1. Comparative examples

[0125] Fuel compositions were prepared by adding an aromatic compound (mesitylene) or a naphthenic compound (methylcyclohexane) to cut A, in the contents detailed in Table II below.

[0126] The auto-ignition temperature (hereinafter referred to as AIT) of each of these compositions was measured, in accordance with the method defined in ASTM E659. The parameter A AIT corresponds to the difference between the auto-ignition temperature of each composition and that of the reference composition ECO.

[0127] The results obtained are also detailed in Table II below.

[0128] [Table II]

[0129] These results show that to significantly increase the auto-ignition temperature of cup A, the aromatic compound and the naphthenic compound must be added in high quantities, as is the case in comparative compositions EC 1 and EC2. In contrast, the addition of 0.5% naphthenic compound (composition EC3) provides only a very moderate increase in the auto-ignition temperature.

[0130] 2. Examples according to the invention

[0131] Fuel compositions were prepared by adding N-methyl-para-anisidine (hereafter referred to as NMPA) to cut A, in the amounts detailed in Table III below.

[0132] The auto-ignition temperature of each of these compositions was measured, in accordance with the method defined in ASTM E659. The results obtained are also detailed in Table III.

[0133] [Table III]

[0134] Composition ECO is comparative (consisting entirely of cut A), while compositions C1 to C5 conform to the invention.

[0135] These results show that adding the compound according to the invention to section A in very small quantities increases the auto-ignition temperature. The auto-ignition temperature increases significantly with the N-methyl-para-anisidine content, and excellent results are obtained at concentrations of 0.32 to 1.29% by mass (compositions C3 to C5).

[0136] Compared to the addition of aromatic and naphthenic compounds according to comparative examples EC 1 and EC2, the addition of the compound according to the invention makes it possible to obtain better results or equivalent results at much lower levels.

[0137] Compared to the addition of the naphthenic compound according to comparative example EC3, said compound in the same concentrations allows for a significantly greater increase in the auto-ignition temperature of the fuel composition.

Claims

DEMANDS 1. Fuel composition comprising: (a) at least 50% by mass, relative to the total mass of the composition, of one or more cuts of fatty acids and / or hydrogenated fatty acid esters (HEFAs); and (b) at least 0.05% by mass, relative to the total mass of the composition, of one or more compounds selected from the aromatic amines corresponding to formula (I) below: in which: - Ri designates a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms; - The groups R2, R3, R4, Rs, and RÔ, whether identical or different, independently designate a hydrogen atom; an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms; or an alkoxy group with the formula -OR a with R adesignating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 16 carbon atoms, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a .

2. Composition according to the preceding claim, characterized in that the HEFA cut(a) is hydrotreated vegetable oil (HVO).

3. Composition according to any one of the preceding claims, characterized in that the HEFA cut(s) (a) have a paraffin content greater than or equal to 90% by mass, preferably greater than or equal to 95% by mass, relative to the total mass of the cut(s) (a).

4. Composition according to the preceding claim, characterized in that the paraffins present in the HEFA cut(a) comprise from 6 to 18 carbon atoms, preferably from 8 to 18 carbon atoms.

5. Composition according to any one of the preceding claims, characterized in that it comprises at least 75% by mass of one or more HEFA(a) cuts, preferably at least 85% by mass, more preferably at least 90% by mass and even better at least 95% by mass, relative to the total mass of the composition.

6. Composition according to any one of the preceding claims, characterized in that in formula (I), the group Ri designates an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even more preferably an alkyl group selected from the methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl (isobutyl), 1-methylpropyl (sec-butyl) and 1,1-dimethylethyl (tert-butyl) groups; preferably a methyl group or an ethyl group; and even more preferably a methyl group.

7. Composition according to any one of the preceding claims, characterized in that in formula (I), the groups R2, R3, R4, Rs, and RÔ, whether identical or different, represent independently of each other: - a hydrogen atom; or - an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even better an alkyl group selected from the methyl and ethyl groups, and even more preferably a methyl group; or - an alkoxy group with the formula -OR a with R a designating a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbon atoms, and even better an alkyl group selected from the methyl and ethyl groups and more preferably still a methyl group, provided that at least one of the groups R2, R3, R4, Rs, and RÔ designates a group of formula -OR a Preferably, at least one of the groups R3, R4, and R5 designates a group with the formula -OR a and more preferably the group R4 designates a group of formula -OR a .

8. Composition according to any one of the preceding claims, characterized in that the compound of formula (I) is 4-methoxy-N-methylaniline.

9. Composition according to any one of the preceding claims, characterized in that it comprises the compound(s) of formula (I) in a total content of 0.05 to 10% by mass, preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, better 0.5 to 2% by mass and better still 1 to 2% by mass, relative to the total mass of the composition.

10. Composition according to any one of the preceding claims, characterized in that its aromatic hydrocarbon content is less than 5% by mass, preferably less than 2% by mass, more preferably less than 1% by mass, relative to the total mass of the composition. 1 1. Use of the composition as defined in any of the preceding claims to power an internal combustion engine of a land, marine, air or space propulsion vehicle.

12. Use according to the preceding claim, to power an aircraft or rocket engine, preferably a turbojet or turboprop in an aircraft selected from an airplane and a helicopter and more preferably an airplane.

13. Method of propelling a land, sea, air or space vehicle equipped with at least one internal combustion engine, consisting of supplying said engine with a fuel composition as defined in any one of claims 1 to 10.

14. A method according to the preceding claim, characterized in that said engine is an aircraft or rocket engine, plus preferably a turbojet or turboprop engine equipping an airplane or helicopter and more preferably an airplane.

15. Use of one or more compounds of formula (I) as defined in any one of claims 1 and 6 to 8 to increase the auto-ignition temperature of a fuel composition comprising at least 50% by mass, relative to the total mass of the composition, of one or more cuts of fatty acids and / or hydrogenated fatty acid esters (HEFA).

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