Producing a sustainable aviation fuel by oligomerisation of light olefins

Abstract

The present invention relates to an improved kerosene base. The present invention also relates to any composition comprising the kerosene base, to a process for its preparation and to its use as fuel in the field of aviation. The present invention also relates to a process for producing the kerosene base from an olefinic feedstock comprising olefinic compounds comprising at least 20% by weight of olefins having a number of carbon atoms that is greater than or equal to 4 (C4+), based on the total weight of the feedstock: a) a step of oligomerising the olefinic feedstock and obtaining an effluent, b) a step of mixing a first olefinic stream comprising at least some of the effluent resulting from step a) or a first paraffinic stream obtained after hydrogenation of at least some of the effluent resulting from step a), with a hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms.

Description

[0001] PRODUCTION OF SUSTAINABLE AVIATION FUEL BY OLIGOMERIZATION OF LIGHT OLEFINS

[0002] technical field

[0003] The present invention relates to the field of bio-based fuels and more particularly to a preferably renewable kerosene base and a process for producing such a base. This process according to the invention maximizes the production of kerosene base that meets current specifications, notably those defined in ASTM D7566 and in particular in Annex 5. This kerosene base then exhibits excellent cold-weather properties. The present invention also relates to any composition comprising such a kerosene base.

[0004] Previous technique

[0005] Airlines have committed to carbon-neutral growth, particularly in commercial aviation, starting in 2021, and US airlines have set a target of reducing CO2 emissions by 50% by 2050 compared to 2005 levels. However, improvements in aircraft and engine efficiency are not proving sufficient to achieve carbon neutrality. Sustainable aviation fuels (SAFs) are therefore critical to reaching this goal.

[0006] It therefore seems necessary to develop kerosenes that are at least partly bio-based and have cold-weather properties at least equivalent to those of fossil kerosenes.

[0007] Thus, US patent 8,373,012 proposes a method for preparing renewable fuel mixtures, including the conversion of fermentative isobutanol into synthetic paraffinic kerosene (or Synthesized Paraffinic Kerosene, SPK, according to Anglo-Saxon terminology) which meet the specifications of ASTM D7566-10a, Annex 1, and therefore have in particular a cold point of no more than -40°C.

[0008] Application WO13085980 discloses a renewable kerosene fuel derived at least in part from biomass, comprising between 5 and 20 wt% isoparaffins and between 15 and 95 wt% naphthenes. More specifically, document WO13085980 describes a renewable kerosene fuel derived from biomass with a cold point of approximately -39°C, -40°C, or -70°C, and in particular a density at 15°C (i.e., 60°F) of between 819 and 839 kg / m³. 3(between 0.8192 g / cc and 0.8393 g / cc). Said kerosene fuel is derived from a fuel composition predominantly n-paraffinic (more than 40% by weight), comprising approximately 7% by weight of C9 compounds, 12% by weight of C10 compounds, 8% by weight of C11 compounds, 9% by weight of C12 compounds and approximately 11% of C14+ compounds, which corresponds to a C9+ mixture comprising approximately 35% by weight of C9 and C12 compounds.

[0009] Application WO2018224730 discloses a renewable kerosene fuel compound, in particular obtained by a Fischer-Tropsch process, comprising predominantly isoparaffins and typically predominantly C15 to C18 paraffins, with C15- paraffins (i.e., those containing fewer than 15 carbon atoms) present at a content of less than 20% by weight, a distillation range in particular between 145°C and 280°C, and a cold point of approximately -51°C. Application WO18224730 also discloses compositions comprising such a renewable kerosene component blended with kerosene of fossil origin (i.e., derived from petroleum) and having a cold point of less than or equal to -40°C, in particular ranging between approximately -53°C and approximately -55°C.

[0010] Application WO2021 / 099343 describes a hydrocarbon composition that can be produced from a renewable source and has properties that allow it to be used as aviation fuel. In particular, this composition has the following characteristics: a high density, between 768 and 772 kg / m³ 3 , a low cold point, equal to or less than -40°C and an average number of hydrocarbon carbon atoms in this composition between 14.3 and 15.1.

[0011] Application W02022 / 008534 describes renewable fuel products composed mainly of isoparaffins (at least 86.7% by weight) and comprising between 35.4 and 69.8% by weight of paraffins (n- and iso-paraffins) in C9-C12, i.e. comprising between 9 and 12 carbon atoms, in other words in C9, C10, C11 and C12. In particular, document W02022 / 008534 describes a renewable kerosene component comprising 86.7% by weight of isoparaffins and compounds of 69.8% by weight of paraffins (n- and isoparaffins) in C9-C12 of which 33.5% by weight of paraffins in C9 and C12, 19.5% by weight of paraffins in C10, 16.8% by weight of paraffin in C11, having a cold point of -54°C and a density of 750.7 kg / m3.

[0012] Application WO2023 / 194338 discloses kerosenes with good cold-weather properties. In particular, this document describes a kerosene base, preferably renewable, comprising at least 80% by weight of isoparaffins and having a very low cold point, less than or equal to -60°C. This kerosene base comprises at least 60.0% by weight of a mixture of C3n hydrocarbons and C4n hydrocarbons, where n is a natural number chosen between 3 and 4, and meets the specifications of ASTM D7566, Annex 5.

[0013] These renewable fuels exhibit good cold-weather properties. However, improving these kerosene bases remains a significant challenge. French patent FR 2926812 discloses a process for the oligomerization of olefins, enabling the production of fuel, for example, gasoline and / or kerosene, from light olefinic feedstocks containing between 2 and 8 carbon atoms (C2-C8).

[0014] Patent EP 2 707 462 discloses a process for oligomerizing olefins comprising 4 to 6 carbon atoms (C4-C6) into a middle distillate cut having predominantly 10 to 20 carbon atoms (C10-C20).

[0015] French patent FR 2 959 750 describes a process for producing middle distillate hydrocarbon bases, preferably kerosene hydrocarbon base, from an ethanol feedstock derived from biomass, said process comprising the dehydration of ethanol into a predominantly ethylenic effluent, two successive oligomerization steps to obtain a middle distillate effluent.

[0016] Application WO 2023 / 194337 describes a process for producing middle distillates, in particular kerosene and / or diesel fuel, from light C3 to C6 olefins, especially those derived from bio-based feedstocks, with improved yields of middle distillates, particularly kerosene and / or diesel fuel, by fractionating the oligomerization effluent into a light fraction and an intermediate fraction, and then recycling said light and intermediate fractions upstream of the oligomerization. Such a process makes it possible to improve middle distillate yields while maintaining sufficiently high feedstock conversion levels.

[0017] In middle distillates, the kerosene fraction is particularly valuable. Therefore, it is advantageous to prioritize kerosene production by maximizing its yield.

[0018] The objective of the present invention is therefore to propose an improved kerosene base, in particular meeting the specifications in force, and in particular exhibiting excellent cold properties, as well as a process for producing said kerosene base from an olefinic feedstock, the yield of which in kerosene base is improved compared to the processes of the prior art.

[0019] Summary of the invention

[0020] The present invention relates to a kerosene base comprising at least 90% by weight of paraffins relative to the total weight of said kerosene base and between 4 and 15% by weight of eight-carbon paraffinic compounds relative to the total weight of paraffins contained in said kerosene base, said kerosene base having:

[0021] - a cutoff temperature T10 (°C) between 150 and 180°C and a cutoff temperature T90 (°C) between 220 and 260°C,

[0022] - a density at 15°C between 765 and 780 kg / m³ 3 , And

[0023] - a flash point greater than or equal to 38°C. The present invention also relates to a process for producing a kerosene base from an olefinic feed comprising olefinic compounds comprising at least 20% by weight of olefins having a number of carbon atoms greater than or equal to 4 (C4+), relative to the total weight of said olefinic feed, said process comprising: a) an oligomerization step of said olefinic feed and obtaining an effluent comprising compounds having a number of carbon atoms greater than or equal to C9 (C9+) and comprising at least 50% by weight of olefins relative to the total weight of said effluent, said oligomerization step implementing an oligomerization phase carried out in the presence of a heterogeneous catalyst;b) a mixing step of a first olefinic stream comprising at least a portion of the effluent from step a) or of a first paraffinic stream obtained after hydrogenation of at least a portion of the effluent from step a), with a hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms, to obtain a mixture, such that said hydrocarbon stream represents between 4 and 15% by weight relative to the total weight of said mixture.;

[0024] The kerosene base according to the invention has the advantage of meeting the specifications in force and in particular very good cold properties, namely a cold point less than or equal to -50°C, relatively low dissolution points T10 and T90, a density equivalent or even lower compared to the density of prior art kerosene bases, while maintaining a satisfactory flash point.

[0025] The present invention also has the advantage of maximizing the kerosene yield of the process of producing said kerosene base.

[0026] List of figures

[0027] Figure 1 schematically represents an implementation of a process for producing a kerosene base from an olefinic feedstock according to the prior art.

[0028] A feedstock (10) comprising olefinic compounds containing at least 20% by weight of olefins having a carbon number greater than or equal to 4 (C4+), relative to the total weight of said feedstock, is sent to a heterogeneous oligomerization step (a) to produce an effluent (11) comprising at most 40% by weight of olefins having a carbon number greater than or equal to C9 (C9+), relative to the total weight of olefins contained in said effluent. In this embodiment, the effluent is fractionated (F) to obtain a fraction (12) comprising at least 90% by weight of compounds having between 4 and 8 carbon atoms relative to the total weight of said fraction and a fraction (14) comprising at least 90% by weight of compounds having a carbon number greater than or equal to 9 (C9+) relative to the total weight of said fraction. Fraction (12) is at least partly recycled to the oligomerization phase of step (a) of oligomerization.The fraction (14) is sent to an olefin hydrogenation step (c) to produce a hydrogenated effluent (14'). This hydrogenated effluent is then fractionated (F') to produce a kerosene base (16) and diesel fuel (17).

[0029] Figure 2 schematically represents an implementation of the process for producing a kerosene base from an olefinic feedstock according to the invention.

[0030] A feed (10) comprising olefinic compounds comprising at least 20% by weight of olefins having a number of carbon atoms greater than or equal to 4 (C4+), relative to the total weight of said feed, is sent to a heterogeneous oligomerization step (a) to produce an effluent (11) comprising at most 40% by weight of olefins having a number of carbon atoms greater than or equal to C9 (C9+), relative to the total weight of olefins contained in said effluent.In this embodiment, the effluent (11) is fractionated (F) to obtain a fraction (112) comprising at least 90% by weight of compounds having between 4 and 7 carbon atoms by the total weight of said fraction, a fraction (113) comprising at least 90% by weight of compounds having 8 carbon atoms (C8) by the total weight of said fraction, and a fraction (114) comprising at least 90% by weight of olefins having 9 or more carbon atoms (C9+) by the total weight of said fraction. Fraction (112) is at least partially recycled to the oligomerization phase of the oligomerization step (a). Advantageously, at least a portion (113a) of fraction (113) is recycled to the oligomerization phase of the oligomerization step (a).

[0031] According to a first alternative (corresponding to the solid line in Figure 2), fraction (113) and fraction (114), at least in part, are sent to a mixing step (b). The mixture (115) of fraction (113) and fraction (114) is then sent to an olefin hydrogenation step (c) to produce a kerosene base (116).

[0032] According to a second alternative (corresponding to the dashed elements in Figure 2), fraction (113) and fraction (114), at least partially, are each sent to a hydrogenation step (c' and c', respectively). The hydrogenated fraction (113') and the hydrogenated fraction (114') are then sent to a mixing step (b) to produce a kerosene base (116).

[0033] In both of these alternatives, the production of a diesel fraction is negligible or even there is no production of a diesel fraction.

[0034] Description of the implementation methods

[0035] According to the present invention, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included within the described range of values. If this is not the case and the limit values ​​are not included within the described range, such clarification will be provided by the present invention. In the sense of the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the sense of the present invention, a preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0036] According to the present invention, the term "olefin" refers to hydrocarbons comprising a single double bond.

[0037] In this description, "Cx" refers to hydrocarbon compounds containing x carbon atoms. "Cx+" refers to hydrocarbon compounds containing at least x carbon atoms. "Cx-" refers to hydrocarbon compounds containing at most x carbon atoms. "Cx to Cy" refers to hydrocarbon compounds having between x and y carbon atoms.

[0038] Throughout this text, chemical element groups are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIIIB according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification, and group IB according to the CAS classification corresponds to the metals in column 11 according to the new IUPAC classification.

[0039] The term "bio-based" means that the product / compound it describes is an organic product / compound whose carbon comes from CO2 present in the atmosphere, recently fixed (on a human timescale) through solar energy (photosynthesis). On land, this CO2 is captured or fixed by plant life (for example, agricultural crops or forest materials). In the oceans, CO2 is captured or fixed by photosynthetic bacteria or phytoplankton. For example, a bio-based material has an isotopic ratio 14 C / 12 C greater than 0. Conversely, a material of fossil origin has an isotopic ratio 14 C / 12C of approximately 0. The terms "renewable" or "derived from renewables" can also be used. To determine whether a product / compound is bio-based or derived from renewables, its modern carbon content (or percent modern carbon, pMC) is measured according to ASTM D 6866-21 ("Determination of Bio-based Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis"). The method in this standard measures the isotope ratio. 14 C / 12 C in a sample and compares it to the isotopic ratio 14 C / 12The bio-based content of a standard bio-based reference material is used to determine the percentage of bio-based content in the sample. This reference material provides a radiocarbon content approximately equivalent to the atmospheric radiocarbon fraction in 1950. The calculation of bio-based carbon content based on the bio-based reference material (pMC) is given in ASTM 6866-24 ("Determination of Bio-based Content of Solid, Liquid, and Gaseous Samples by Radiocarbon Analysis"). Thus, the bio-based carbon content of the standard bio-based reference material is 100%. The bio-based carbon content of a fossil-based material is approximately 0%. The bio-based carbon content of a bio-based material is strictly greater than 0%, for example, greater than or equal to 1%. A current bio-based material may therefore potentially have a bio-based carbon content of 100%.

[0040] In this description, the terms "T90" or "T90 temperature" are interchangeable and refer to the temperature at which 90% by weight of the product in question has evaporated. It is determined according to the ASTM D86 standard method. Similarly, "T10" or "T10 temperature" is the temperature at which 10% by weight of the product in question has evaporated, determined according to the same ASTM D86 standard method.

[0041] The freezing point of a substance defines a temperature at which the liquid and solid states of the substance can coexist in equilibrium (ASTM D5972 and / or D7153).

[0042] The flash point of a substance defines a temperature at which the vapors emitted by the substance ignite in the presence of a flame from a standardized device (ASTM D56 and / or D3828).

[0043] In this application, the term "include" is synonymous with (means the same as) "include" and "contain," and is inclusive or open-ended and does not exclude other unstated elements. It is understood that the term "include" includes the exclusive and closed term "consist."

[0044] In the context of the present invention, the expression "upstream of..." means being before the process step under consideration.

[0045] In the following, specific embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation as to the number of combinations where technically feasible.

[0046] The invention relates to a process for producing a kerosene base from an olefinic feedstock, said process comprising an oligomerization step a) of the olefinic feedstock and a mixing step b) of an olefinic stream comprising at least a portion of said effluent from step a) or of a paraffinic stream obtained after hydrogenation of at least a portion of said effluent from step a), with a hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms. The incorporation of said hydrocarbon stream at a content of between 4 and 15% by weight relative to the total weight of said mixture makes it possible to maintain a satisfactory flash point and a density of the mixture conforming to the specified requirements.This mixing step b) thus makes it possible to obtain a kerosene base with excellent cold properties and to maximize kerosene yield compared to prior art processes, with diesel production being greatly reduced compared to prior art processes or even with no diesel production.

[0047] Charge

[0048] According to the invention, the olefinic feed implemented in the process of the invention comprises olefinic compounds comprising at least 20%, preferably at least 60%, preferably at least 70% and preferably at least 80% by weight of olefins having a number of carbon atoms greater than or equal to 4 (C4+), relative to the total weight of said olefinic feed.

[0049] Advantageously, the olefinic charge comprises olefins having between 3 and 12 carbon atoms. Preferably, the olefinic charge comprises at least 80% by weight, preferably at least 90% by weight, preferably at least 95%, preferably at least 98% by weight, and in particular at least 99% by weight, of olefins containing between 3 and 12 carbon atoms, relative to the total weight of the olefinic charge.

[0050] The olefinic filler may optionally include paraffins, that is, fully hydrogenated hydrocarbon compounds, preferably aliphatic and preferably having between 3 and 8 carbon atoms. Advantageously, the olefinic filler may comprise up to 80% by weight, preferably up to 50% by weight, preferably up to 10% by weight, preferably up to 5% by weight, in particular up to 2% or even up to 1% by weight of paraffins, relative to the total weight of said olefinic filler.

[0051] Treating an olefinic feed containing a low paraffin content, or even an olefinic feed devoid of paraffins, allows the oligomerization step a) to be carried out at low pressure, in particular lower than that classically used for conventional (or fossil) feeds which generally include paraffin contents greater than 10% by weight and often between 40 and 80% by weight of paraffins.

[0052] An olefinic feed implemented in the process of the invention advantageously comprises between 50 and 80%, preferably between 60 and 70%, of olefins having 4 carbon atoms (C4), relative to the total weight of said olefinic feed.

[0053] An olefinic feed implemented in the process of the invention advantageously comprises between 10 and 40%, preferably between 20 and 30%, of olefins having 6 carbon atoms (C6), relative to the total weight of said olefinic feed.

[0054] An olefinic feed implemented in the process of the invention advantageously comprises between 40 and 75% by weight, preferably between 55 and 65% by weight of olefins having 4 carbon atoms (C4) and advantageously between 15 and 50% by weight, preferably between 20 and 35% by weight of olefins having 6 carbon atoms (C6), the contents being given as a percentage by weight of the olefins considered in relation to the total weight of said olefinic feed.

[0055] The olefinic charge used in the process of the invention preferably comprises between 1 and 30%, preferably between 1 and 20% of olefins having a number of carbon atoms greater than or equal to 8 (C8+).

[0056] Preferably, the olefinic feedstock is at least partly, very advantageously entirely, bio-based, in order to produce valuable bio-based products.

[0057] In a particular embodiment, the olefinic charge may originate, directly or indirectly, from a catalytic alcohol decomposition unit and / or from the dehydration of alcohols such as methanol, ethanol, propanol or butanol, in particular from biomass, for example from sugar fermentation.

[0058] The catalytic decomposition unit of alcohol is preferably a catalytic decomposition unit of methanol or ethanol.

[0059] According to a preferred embodiment, the olefinic charge comes from an ethanol dehydration unit (ETE route: Ethanol To Ethylene according to Anglo-Saxon terminology).

[0060] The olefin feedstock can also come from a Fischer-Tropsch unit or a conventional refining unit. In the case of a conventional refining unit, it is preferably implemented in a blend with bio-based feedstocks, preferably in weight proportions between a conventional olefinic feedstock and a bio-based olefinic feedstock of between 90:10 and 10:90, preferably between 80:20 and 20:80. Preferably, a conventional olefinic feedstock comes from a steam cracking unit, an FCC catalytic cracking unit (FCC for Fluid Catalytic Cracking according to Anglo-Saxon terminology), a selective hydrogenation unit of diolefins (known as a SHU unit), or a dehydrogenation unit of paraffins, pure or in blends and / or any other unit leading to the production of light olefins.

[0061] The olefin feed treated in the process according to the invention may advantageously undergo a pretreatment step before being sent to step a) of oligomerization. Such a pretreatment step makes it possible to remove any compound that could cause poisoning of the oligomerization catalysts, in particular basic nitrogen compounds, water, sulfur derivatives, and oxygenated derivatives. Preferably, the olefin feed comprises a sulfur or sulfur compound content of 20 ppm by weight or less, preferably 12 ppm by weight or less, and preferably 10 ppm by weight or less of sulfur relative to the weight of the olefin feed, thus preventing or at least limiting poisoning of the oligomerization catalyst in step a).If the olefinic feed contains more than 20 ppm by weight of sulfur, the process advantageously includes a pretreatment step of the olefinic feed, located upstream of step a) of oligomerization, preferably implementing an adsorption section and / or a water washing section and / or a dedicated hydrotreating section, thus allowing the oligomerization catalyst of step a to be protected.

[0062] Preferably, the olefinic feed of the process according to the invention comprises a nitrogen or nitrogen compounds content of less than or equal to 0.1 ppm by weight of nitrogen element relative to the total weight of the olefinic feed, making it possible to avoid or at least limit the poisoning of the oligomerization catalyst of step a). If the olefinic feed contains more than 0.1 ppm by weight of nitrogen, the process advantageously includes a pretreatment step of the olefinic feed, located upstream of the oligomerization step a), preferably implementing an adsorption and / or water washing and / or hydrotreating section, thus making it possible to protect the oligomerization catalyst of step a).

[0063] Preferably, the olefin feedstock treated by the process according to the invention comprises a butadiene content, in particular 1,3-butadiene, less than or equal to 0.1 ppm by weight, preferably less than or equal to 500 ppm by weight of butadiene, in particular 1,3-butadiene, relative to the total weight of the olefin feedstock, which protects the oligomerization catalyst. If the olefin feedstock contains more than 0.1 ppm by weight of butadiene, in particular 1,3-butadiene, the process advantageously includes a pretreatment step of the olefin feedstock, located upstream of the oligomerization step (a), preferably employing a selective hydrogenation section.

[0064] Characteristics of the kerosene base

[0065] The present invention relates to a kerosene base comprising at least 90% by weight of paraffins relative to the total weight of said kerosene base and between 4 and 15% by weight of eight-carbon paraffinic compounds relative to the total weight of paraffins contained in said kerosene base, said kerosene base having:

[0066] - a cutoff temperature T10 (°C) between 150 and 180°C and a cutoff temperature T90 (°C) between 220 and 260°C,

[0067] - a density at 15°C between 765 and 780 kg / m3, and

[0068] - a flash point greater than or equal to 38°C. Advantageously, the kerosene base comprises predominantly (i.e., at least 90% by weight) aliphatic hydrocarbon compounds, preferably predominantly (i.e., at least 90% by weight) non-cyclic and non-aromatic hydrocarbon compounds. Preferably, the kerosene base comprises at least 90% by weight, preferably at least 95% by weight, and preferably at least 99% by weight of aliphatic hydrocarbons, preferably linear and / or branched, and preferably non-cyclic, relative to the total weight of the kerosene base. Preferably, the kerosene base comprises 10% by weight or less, preferably 5% by weight or less, preferably 1.0% by weight or less, and very preferably 0.5% by weight or less, of cyclic and / or aromatic hydrocarbon compounds, such as naphthenic, benzene and / or naphthalene compounds, relative to the total weight of the kerosene base.Preferably, the kerosene base comprises strictly less than 10% by weight of naphthenic compounds (also called cycloparaffins), preferably less than 5% by weight, preferably less than 1.0% by weight, most preferably less than 0.5% by weight relative to the total weight of the kerosene base, and most preferably is free of naphthenic compounds. This is because naphthenic compounds increase the density of the kerosene produced and have a higher carbon-to-hydrogen ratio (C / H) than paraffins.

[0069] The kerosene base may optionally include olefins, preferably at a weight content of less than or equal to 5% by weight, preferably less than or equal to 1.0% by weight, most preferably less than or equal to 0.5% by weight relative to the total weight of the kerosene base.

[0070] Preferably, the kerosene base comprises predominantly (i.e., at least 90% by weight) hydrogenated aliphatic hydrocarbons, called alkanes or paraffins. Preferably, the kerosene base comprises at least 90% by weight, preferably at least 95% by weight, and most preferably at least 99% by weight of paraffins, preferably linear (or n-paraffins) and branched (or iso-paraffins), relative to the total weight of the kerosene base.

[0071] Advantageously, the kerosene base according to the invention comprises at least 90%, preferably at least 95% by weight, preferably at least 97% by weight, and preferably at least 99% by weight of branched paraffins, relative to the total weight of paraffins in said kerosene base.

[0072] Branched paraffins are paraffins comprising at least one side chain, such as a methyl, ethyl, or propyl substituent.

[0073] Advantageously, branched paraffins, also called isoparaffins, are multi-branched. Preferably, the kerosene base comprises at least 40% by weight, preferably at least 50% by weight, and preferably at least 70% by weight, of multi-branched paraffins relative to the total weight of said kerosene base. The term "multi-branched paraffins" means that said paraffins have a branching index greater than or equal to 2, preferably less than or equal to 9, and most preferably less than or equal to 6.

[0074] Advantageously, the kerosene base comprises at most 10% by weight of linear paraffins, also called n-paraffins, preferably at most 5% by weight of linear paraffins, preferably at most 3% by weight of linear paraffins, and preferably at most 1% by weight of linear paraffins, relative to the total weight of said kerosene base.

[0075] Advantageously, the kerosene base comprises between 4 and 15% by weight, and preferably between 7 and 10% of 8-carbon paraffinic compounds relative to the total weight of paraffins contained in said kerosene base.

[0076] Advantageously, the kerosene base according to the invention, comprising between 4 and 15%, and preferably between 7 and 10% by weight, of 8-carbon (C8) paraffinic compounds relative to the total weight of paraffins contained in said kerosene base, has a relatively low density while having a flash point conforming to the specifications of ASTM D7566-24 Annex 5. The overall carbon yield of the resulting kerosene base is better than that of prior art kerosene bases. In particular, when using the kerosene base according to the invention as aviation fuel, less CO2 is produced than when using prior art kerosene bases.

[0077] The kerosene base is advantageously at least partially, preferably entirely, bio-based. Preferably, the kerosene base according to the invention has a bio-based carbon content greater than or equal to 1%, preferably greater than or equal to 50%, preferably greater than or equal to 75%, in particular greater than or equal to 90%, or even equal to 100%. Preferably, the pMC is greater than or equal to 1, preferably greater than or equal to 50, preferably greater than or equal to 75, preferably greater than or equal to 90, or even equal to 100.

[0078] Preferably, the kerosene base according to the present invention is obtained by the process described above.

[0079] Most advantageously, the kerosene base according to the invention meets the specifications in force for kerosenes in particular for aviation, and more particularly the specifications of the ASTM D7566 standard and in particular those defined in Annex 5 of the ASTM D7566 standard.

[0080] In particular, the kerosene base has a cut-off temperature T10 (°C) between 150 and 180°C, preferably between 155 and 175°C, and preferably between 156 and 165°C and a cut-off temperature T90 (°C) between 220 and 260°C, preferably between 230 and 250°C, preferably between 235 and 245°C.

[0081] Advantageously, the kerosene base according to the invention has an initial boiling point greater than or equal to 134°C.

[0082] The kerosene base has a final boiling point below 300°C.

[0083] Furthermore, the kerosene base according to the invention has a cold point of -50°C or less, preferably -60°C or less, preferably -70°C or less, and preferably -80°C or less. The cold point is very advantageously -80°C or less.

[0084] Furthermore, the kerosene base has a density at 15°C of between 765 and 780 kg / m³, preferably between 765 and 775 kg / m³, and most preferably between 765 and 770 kg / m³. The density of the kerosene base can be measured by any standardized method known to those skilled in the art, such as ASTM D4052.

[0085] Furthermore, the kerosene base according to the invention has a flash point advantageously greater than or equal to 38°C, preferably greater than or equal to 40°C and preferably greater than or equal to 42°C and therefore meets the specifications of the ASTM D7566 standard.

[0086] Furthermore, the kerosene base has an average number of carbon atoms between 10.0 and 14.0, preferably between 11.0 and 13.0, and more preferably between 11.0 and 12.5. The average number of carbon atoms in the kerosene base can be measured by any method known to those skilled in the art, such as gas chromatography. This average number of carbon atoms in the kerosene base is low, thus improving the overall carbon yield of said kerosene base. A higher average number of carbon atoms, for example, above 14, means that the carbon yield is low, with longer carbon chains and a lower volumetric yield.

[0087] There is a relationship between overall carbon efficiency and the carbon chain length of the kerosene base. A low average number of carbon atoms indicates a high overall carbon efficiency. A high overall carbon efficiency of a kerosene base indicates that, when using that base, carbon is used efficiently and CO2 and co-product emissions are minimized.

[0088] The average number of carbon atoms in the kerosene base can be measured by any method known to those skilled in the art, such as gas chromatography (for example, flame ionization detection gas chromatography, the conditions of which are listed in Table 1, in which the PONA-type column used has a length of 50 m, an internal diameter of 0.20 mm, a film thickness of 0.5 pm, and the stationary phase contains 100% dimethyl polysiloxane (OV-1)). A mass-weighted average of the number of carbon atoms in each compound identified by gas chromatography is then calculated to determine the average number of carbon atoms.

[0089] Table 1: Characteristics of the gas chromatography method with flame ionization detection

[0090] The kerosene base according to the invention thus has the advantage of meeting current specifications and, in particular, exhibits very good cold-weather properties. It also has a lower average number of carbon atoms than prior art kerosene bases, thereby improving the overall carbon yield of said kerosene base. Indeed, a higher average number of carbon atoms, for example, above 14, means that the overall carbon yield is low, with longer carbon chains and a lower volumetric yield. The advantage of the present invention also lies in maximizing the kerosene yield of the process used to produce said kerosene base.

[0091] The present invention also relates to any composition comprising the kerosene base described above, preferably a composition comprising at least 5% by weight of said kerosene base, preferably at least 10% by weight of the kerosene base, preferably at least 30% by weight of the kerosene base, most preferably at least 50% by weight of the kerosene base, and preferably less than 90% by weight, preferably less than 60% by weight of the kerosene base, the contents being given as a percentage by weight relative to the total weight of said composition. The said composition comprises, in addition to the kerosene base, one or more bio-based kerosene products different from the kerosene base according to the invention and / or one or more kerosene products of fossil origin (also called fossil kerosene product(s) or non-renewable kerosene product(s)), for example aromatic kerosene products.

[0092] The present invention also relates to a method for preparing such a composition, comprising mixing the kerosene base according to the invention with at least one kerosene product other than said kerosene base, in particular with a bio-based and / or fossil kerosene product, preferably in a proportion of the kerosene base of at least 5% by weight, preferably at least 10% by weight, most preferably at least 30% by weight, and most preferably at least 50% by weight, relative to the total weight of the composition. Advantageously, said method for preparing the composition also comprises all the steps for preparing the kerosene base according to the invention as described above, prior to mixing said kerosene base with said at least one kerosene product other than said kerosene base.

[0093] The present invention also relates to the use of a composition such as described above, as fuel for aircraft engines.

[0094] Operating conditions of the kerosene base production process

[0095] Advantageously, the kerosene base according to the invention is obtained by the production process of said base, as described below.

[0096] Step a) of oligomerization

[0097] The process according to the invention comprises a step a) of oligomerizing an olefinic feed comprising olefinic compounds comprising at least 20% by weight of olefins having a number of carbon atoms greater than or equal to 4 (C4+), relative to the total weight of said feed and obtaining an effluent comprising compounds having at least 50% by weight, preferably at least 70% by weight, preferably at least 90% by weight of olefins having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said effluent, said oligomerization step being carried out in the presence of a heterogeneous catalyst.

[0098] According to a first embodiment of the invention, the heterogeneous catalyst used in the oligomerization step a) is a catalyst comprising an amorphous support. Advantageously, said amorphous support of the catalyst comprises, and preferably is made of, an amorphous mineral material selected from silica-aluminas and silicified aluminas.

[0099] According to a second embodiment of the invention, the heterogeneous catalyst used in the oligomerization step a) is a catalyst comprising a support including at least one zeolite. Advantageously, said zeolite support of the catalyst comprises, and preferably consists of, a zeolite, preferably having at least pore openings containing 10 or 12 oxygen atoms (10MR or 12MR), and preferably selected from aluminosilicate zeolites having an overall Si / Al ratio greater than 10. According to this second embodiment, the zeolite support preferably comprises a zeolite selected from structural zeolites of the MFI, MTW, MOR, TON, MEL, MFS, and MTT types, used alone or in mixtures.Preferably, the zeolite support of the catalyst used in the oligomerization step a) comprises a zeolite selected from the zeolites ZSM-5, ZSM-12, NU-86, Mordenite, ZSM-22, NU-10, ZBM-30, ZSM-48, ZSM-11, ZSM-57, IZM-2, ITQ-6 and IM-5, taken alone or in mixture, preferably from the zeolites ZSM-5, NU-10 and ZBM-30, taken alone or in mixture, most preferably the zeolite is ZBM-30, and even more preferably the zeolite is ZBM-30 advantageously synthesized in the presence of the triethylenetetramine structuring agent.

[0100] According to the second embodiment of the invention, the zeolite used in the catalyst in step a) of the process according to the invention can advantageously undergo several post-treatments known to those skilled in the art. For example, it can be modified by desalumination or desilication using any desalumination, external surface passivation, or desilication method known to those skilled in the art, in order to improve its activity and / or stability.

[0101] According to a very specific embodiment in which silica-alumina is used as a catalyst in the oligomerization step a), said silica-alumina enables the oligomerization of the olefin feedstock, with better control of olefin reactivity. This allows operation at a low-pass conversion level and, very advantageously, optimizes selectivity towards the desired olefins, compared to oligomerization in the presence of other catalysts, such as zeolites. Furthermore, coke formation is less significant and less rapid in the presence of silica-alumina than in the presence of zeolites. Therefore, silica-alumina requires regeneration at a lower frequency than zeolites.

[0102] The heterogeneous catalyst used in step a) of the process according to the invention, in particular the zeolite catalyst, advantageously also comprises at least one oxide-type matrix, also called a binder. The term "matrix" according to the invention means an amorphous or poorly crystallized material. The matrix is ​​advantageously selected from the group consisting of clays (such as, for example, natural clays like kaolin or bentonite), magnesia, aluminas, silicas, silica-aluminas, aluminates, titanium dioxide, boron dioxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, and carbon. Preferably, the matrix is ​​selected from the group consisting of aluminas, clays, and silicas; more preferably, the matrix is ​​selected from aluminas; and even more preferably, the matrix is ​​gamma-alumina.

[0103] Advantageously, the catalysts used in step a) of the process according to the invention are shaped into grains, particularly of various shapes and sizes. They are advantageously used in the form of cylindrical or multilobed extrudates such as bilobed, trilobed, or multilobed, with a straight or twisted shape, but can optionally be manufactured and used in the form of crushed powder, tablets, rings, balls, wheels, or spheres. Preferably, said catalysts are in the form of extrudates with a size between 1 and 10 mm.

[0104] Advantageously, the oligomerization phase of step a) of oligomerization is carried out in at least one reactor, in particular a fixed-bed reactor. Preferably, step a) of oligomerization is carried out in one, two or three reactor(s), in particular a fixed-bed reactor(s).

[0105] Advantageously, the oligomerization phase (a) of the process according to the invention operates at a temperature between 50 and 400°C, preferably between 100 and 350°C and preferably between 100 and 300°C, and at a pressure between 2 and 15 MPa, preferably between 2 and 8 MPa and preferably between 3 and 8 MPa, and with a WH preferably between 0.1 and 10 h -1 preferably between 0.4 and 5 hours -1 .

[0106] The WH (or hourly volumetric velocity) is, according to the invention, defined by the ratio between the volumetric flow rate of fresh olefinic charge in particular at 15°C and 1 atmosphere and the volume of oligomerization catalyst in particular in operation (also called in operation).

[0107] Preferably, the effluent from the reaction unit (i.e., the oligomerization phase) implemented at the oligomerization step a) comprises at most 40% by weight, preferably at most 30% by weight, of compounds having a number of carbon atoms greater than or equal to 9 (C9+), the weight percentages being expressed in relation to the weight of said effluent.

[0108] According to one embodiment of the invention, step a) of oligomerization comprises a fractionation phase of the oligomerization effluent from the oligomerization phase, the oligomerization effluent from the oligomerization phase being advantageously recovered at the end of the reaction unit implemented in step a) (i.e. at the end of the reactor or the last reactor in the series implemented) to obtain at least: - a fraction comprising at least 90% by weight, preferably at least 95% and preferably at least 98% by weight of olefins having between 4 and 7 carbon atoms (C4-C7), relative to the total weight of said fraction,

[0109] - a fraction comprising at least 90% by weight, preferably at least 95% and preferably at least 98% by weight of olefinic compounds having a number of carbon atoms greater than or equal to 9, relative to the total weight of said fraction, and constituting at least part of the effluent from step a),

[0110] - a fraction comprising at least 90% by weight, preferably at least 95% by weight and preferably at least 98% by weight of olefins having 8 carbon atoms (C8), relative to the total weight of said fraction, and constituting at least a part of said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms, and incorporated during mixing step b) into the first olefinic stream comprising at least a part of the effluent from oligomerization step a).

[0111] Advantageously, part or all of said fraction comprising at least 90%, preferably at least 95% and preferably at least 98% by weight of olefins having between 4 and 7 carbon atoms (C4-C7), relative to the total weight of said fraction is recycled, at least in part, to the oligomerization phase of oligomerization step a).

[0112] Advantageously, a portion of said fraction comprising at least 90%, preferably at least 95% by weight and preferably at least 98% by weight of olefins having 8 carbon atoms, relative to the total weight of said fraction may be recycled to the oligomerization phase of oligomerization step a).

[0113] An example of an oligomerization step a) is the Polynaphtha™ process marketed by the company Axens.

[0114] Step b) of mixing

[0115] The process according to the invention includes a step of mixing a first olefinic stream comprising at least a part of the effluent from step a) or a first paraffinic stream obtained after hydrogenation of at least a part of the effluent from step a), with a hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms, to obtain a mixture, said hydrocarbon stream representing between 4 and 15% by weight relative to the total weight of said mixture.

[0116] In a first embodiment, said hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms is a second olefinic stream and is mixed, in said mixing step b), with said first olefinic stream comprising at least a portion of the effluent from step a). In a second embodiment, said hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms is a second paraffinic stream and is mixed, in said mixing step b), with said first paraffinic stream obtained after hydrogenation of at least a portion of the effluent from step a).

[0117] Advantageously, said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms comes from a fraction from a fractionation of the oligomerization effluent from the oligomerization phase, which is recovered at the end of the reaction unit implemented in step a).

[0118] Advantageously, said second paraffinic stream comprising hydrocarbon compounds having 8 carbon atoms comes from a fraction from a fractionation of the oligomerization effluent from the oligomerization phase, which is recovered at the end of the reaction unit implemented in step a) which is then hydrogenated.

[0119] In a particular embodiment of the invention, said hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms is a second olefinic stream or a second paraffinic stream not originating from the fractionation phase of the oligomerization effluent from the oligomerization phase in step a) of oligomerization.

[0120] Step b) of mixing advantageously operates at a temperature between 20 and 150°C, preferably between 30 and 100°C and preferably between 25 and 45°C and at a pressure between 0.25 and 2.0, preferably between 0.3 and 1.0 MPa.

[0121] Hydrogenation stage

[0122] Advantageously, the process according to the invention may further comprise, after step b) of mixing, a step of hydrogenation c) of the mixture of said first olefinic stream comprising at least a part of the effluent from step a) with said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms.

[0123] According to one embodiment, the process according to the invention, wherein step a) comprises a fractionation phase of the oligomerization effluent from the oligomerization phase, to obtain at least:

[0124] - a fraction comprising at least 90% by weight of olefins having between 4 and 7 carbon atoms (C4-C7), relative to the total weight of said fraction,

[0125] - a fraction comprising at least 90% by weight of olefins having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said fraction and constituting at least a part of said effluent from step a),

[0126] - a fraction comprising at least 90% by weight of olefins having 8 carbon atoms (C8) relative to the total weight of said fraction and constituting at least a part of said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms, incorporated during mixing step b) into the first olefinic stream comprising at least a part of said effluent from oligomerization step a), said process may further comprise at the end of mixing step b), a hydrogenation step (c) of the mixture of said first olefinic stream comprising at least a part of said effluent from step a) with said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms.

[0127] According to another embodiment of the invention, the process according to the invention, wherein step a) comprises a fractionation phase of the oligomerization effluent from the oligomerization phase, to obtain at least:

[0128] - a fraction comprising at least 90% by weight of olefins having between 4 and 7 carbon atoms (C4-C7), relative to the total weight of said fraction,

[0129] - a fraction comprising at least 90% by weight of olefins having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said fraction and constituting at least a part of said effluent from step a),

[0130] - a fraction comprising at least 90% by weight of olefins having 8 carbon atoms (C8) relative to the total weight of said fraction, at least a part of said fraction comprising at least 90%, preferably at least 95% by weight, preferably at least 98% by weight of olefins having 8 carbon atoms relative to the total weight of said fraction is hydrogenated and constitutes at least a part of said second paraffinic stream incorporated during mixing step b), to the first paraffinic stream obtained after hydrogenation of at least a part of said effluent from oligomerization step a).

[0131] According to a particular embodiment of the invention, at least a part, preferably all of the effluent obtained in the oligomerization step a), and in particular at least a part of the fraction comprising at least 90% by weight of olefins having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said fraction, undergoes a hydrogenation step of the olefins to obtain a paraffinic stream which in particular constitutes said first paraffinic stream mixed with said second paraffinic stream in step b).

[0132] Advantageously, the second olefinic stream, comprising hydrocarbon compounds having 8 carbon atoms from a fraction obtained by fractionating the oligomerization effluent from the oligomerization phase of oligomerization step a), also undergoes an olefin hydrogenation step to obtain a second paraffinic stream. This second paraffinic stream, comprising compounds having 8 carbon atoms, is then mixed with the first paraffinic stream obtained after hydrogenation of at least a portion of the effluent from step a).

[0133] According to another particular embodiment of the invention, at least a portion, preferably all, of the mixture obtained in step b) undergoes an olefin hydrogenation step, the mixture obtained in step b) comprising at least a portion of the effluent from the oligomerization step a) and a second olefin stream comprising hydrocarbon compounds having 8 carbon atoms. Preferably, said second olefin stream comprising hydrocarbon compounds having 8 carbon atoms is derived from a fraction resulting from a fractionation of the oligomerization effluent from the oligomerization phase of the oligomerization step a).

[0134] Advantageously, the hydrogenation step is carried out by contacting a hydrogen-rich gas in the presence of a catalyst comprising at least one metal from group VIII, preferably chosen from palladium and nickel taken alone or in mixture, and a support preferably chosen from alumina, silica or silica-alumina.

[0135] The catalyst used in the optional hydrogenation step preferably comprises a palladium content advantageously between 0.1 and 10 wt% and / or a nickel content advantageously between 1 and 60 wt% relative to the total mass of the catalyst.

[0136] The hydrogenation stage operates advantageously at a temperature between 100 and 250°C at the reactor inlet, at a pressure between 2.0 and 5.0 MPa, and at an hourly weight rate between 0.05 and 8.0 h -1 .

[0137] The performance of hydrogenation is validated by a measurement of the number of bromine which is advantageously at most 5 g Br / 100g, in the case where it is desired to saturate all the unsaturated compounds present in the cut to be hydrogenated.

[0138] Following this hydrogenation step, the process according to the invention makes it possible to obtain a kerosene base, preferably with a significantly reduced diesel fuel production compared to prior art processes, or even with no diesel fuel production at all. The process according to the invention thus avoids an additional fractionation step, such as that found in prior art processes.

[0139] The following examples illustrate the invention, in particular specific embodiments of the invention, without limiting its scope.

[0140] Examples

[0141] Example 1 (not in accordance with the invention) An olefinic feedstock 10 comprising 62 wt% butene, 26 wt% C6 olefins and 12 wt% C8+ olefins is oligomerized according to the embodiment of the process described in Figure 1, in the presence of a silica-alumina catalyst (commercial catalyst IP 811 from Axens), at a temperature between 140 and 190°C, a pressure of 3.5 MPa and a WH of 0.3 h -1 .

[0142] The effluent 11 from the oligomerization phase of the oligomerization step (a) is separated by distillation (F) into two fractions: a fraction (12) comprising 99% by weight of compounds having between 4 and 8 carbon atoms (C4-C8), said fraction 12 being recycled to the oligomerization phase of the oligomerization step (a), and a fraction 14 comprising 99% by weight of compounds having a number of carbon atoms greater than or equal to 9 (C9+).

[0143] The recycling rate of fraction 12 relative to the olefinic load (10) which enters the oligomerization step (a) is 4.3.

[0144] Fraction 14 is sent to an olefin hydrogenation step (c) to produce a hydrogenated effluent 14'. Said hydrogenated effluent is then fractionated (F') to produce a kerosene cut 16) and a diesel cut 17. This fractionation makes it possible to comply with the density specification (less than 770.0 kg / m3) of ASTM D7566 Annex 5.

[0145] The overall yield of the prior art process is 91% for kerosene production and 7% for diesel production.

[0146] The characteristics of the kerosene base obtained are presented in Table 2.

[0147]

[0148] Example 2 (according to the invention)

[0149] An oligomerization unit is implemented in the same way as in Example 1, except that the effluent 11 from the oligomerization phase of the oligomerization step (a) is separated (F) by distillation into three fractions (Figure 2, solid lines): a fraction 112 comprising 99% by weight of compounds having between 4 and 7 carbon atoms (C4-C7) relative to the total weight of said fraction, said fraction 112 being recycled to the oligomerization phase of the oligomerization step (a), - a fraction 113 comprising at least 90% by weight of olefins having 8 carbon atoms relative to the total weight of said fraction. Part 113a of said fraction 113 is recycled to the oligomerization phase of the oligomerization step (a), and a fraction 114 comprising at least 90% by weight of compounds having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said fraction.

[0150] The recycling rate of fraction 112 relative to the olefinic load entering the oligomerization step (a) is 2.5 by weight.

[0151] The recycling rate of fraction 113a relative to the olefin feedstock entering the oligomerization step (a) is 1.8 by weight. The unrecycled portion of fraction 113 and fraction 114 are sent to a blending step (b), with the unrecycled portion of fraction (113) representing 8% by weight of said blend. The blend 115 obtained at the end of (b) is then sent to an olefin hydrogenation step (c) to produce a kerosene base 116. The overall yield of the kerosene production process according to the invention is 98% in kerosene base. Thus, the process according to the invention makes it possible to obtain an improved overall kerosene yield compared to the prior art process, by eliminating the production of diesel fuel.

[0152] The characteristics of the kerosene base obtained are presented in Table 3.

[0153] The kerosene base according to the invention has very good cold-weather properties, as it has a cold point of -80°C. The kerosene base according to the invention also has a relatively low density (770 kg / m³ at 15°C), while having a flash point and boiling points that meet the specifications of ASTM D7566-24 Annex 5. This kerosene base also has a lower average number of carbon atoms than the kerosene base according to the prior art, thus improving its overall carbon yield.

Claims

Demands 1. Kerosene base comprising at least 90% by weight of paraffins relative to the total weight of said kerosene base and between 4 and 15% by weight of eight-carbon paraffinic compounds relative to the total weight of paraffins contained in said kerosene base, said kerosene base having: a cut-off temperature T10 (°C) between 150 and 180°C and a cut-off temperature T90 (°C) between 220 and 260°C, a density at 15°C between 765 and 780 kg / m3, and a flash point greater than or equal to 38°C.

2. Kerosene base according to claim 1, comprising at least 95% by weight, preferably at least 97% by weight, and preferably at least 99% by weight of branched paraffins, relative to the total weight of paraffins of said kerosene base.

3. Kerosene base according to claim 1 or claim 2, having a bio-based carbon content greater than or equal to 1%, preferably greater than or equal to 50%, preferably greater than or equal to 75%, preferably greater than or equal to 90%.

4. Composition comprising a kerosene base according to any one of claims 1 to 3, preferably comprising at least 5% by weight of a kerosene base according to any one of claims 1 to 3, relative to the total weight of said composition.

5. A method for preparing a composition according to claim 4, comprising mixing a kerosene base according to any one of claims 1 to 3, with at least one kerosene product other than said kerosene base.

6. Use of a composition according to claim 4 as fuel for aviation engines.

7. A process for producing a kerosene base according to any one of claims 1 to 3, from an olefinic feedstock comprising olefinic compounds comprising at least 20% by weight of olefins having a carbon number greater than or equal to 4 (C4+), relative to the total weight of said olefinic feedstock, said process comprising: a) an oligomerization step of said olefinic feedstock and obtaining an effluent comprising compounds having a carbon number greater than or equal to C9 (C9+) and comprising at least 50% by weight of olefins relative to the total weight of said effluent, said oligomerization step implementing an oligomerization phase carried out in the presence of a heterogeneous catalyst; b) a mixing step of a first olefinic stream comprising at least a portion of the effluent from step a) or of a first paraffinic stream obtained after hydrogenation of at least a portion of the effluent from step a), with a hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms, to obtain a mixture, such that said hydrocarbon stream represents between 4 and 15% by weight relative to the total weight of said mixture.

8. A process for producing a kerosene base according to claim 7, wherein said hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms is a second olefinic stream and is mixed, in said mixing step b), with said first olefinic stream comprising at least a portion of the effluent from step a).

9. A process for producing a kerosene base according to claim 7, wherein said hydrocarbon stream comprising hydrocarbon compounds having 8 carbon atoms is a second paraffinic stream and is mixed, in said mixing step b), with said first paraffinic stream obtained after hydrogenation of at least a portion of the effluent from step a).

10. A process for producing a kerosene base according to claim 8, further comprising, after step b) of mixing, a step of hydrogenation (c) of the mixture of said first olefinic stream comprising at least a part of the effluent from step a) with said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms.

11. A process for producing a kerosene base according to claim 8 or claim 10, wherein step a) comprises a fractionation phase of the oligomerization effluent from the oligomerization phase, to obtain at least: - a fraction comprising at least 90% by weight of olefins having between 4 and 7 carbon atoms (C4-C7), relative to the total weight of said fraction, - a fraction comprising at least 90% by weight of olefins having a number of carbon atoms greater than or equal to 9 (C9+) relative to the total weight of said fraction and constituting at least part of the effluent from the oligomerization step a), - a fraction comprising at least 90% by weight of olefins having 8 carbon atoms (C8) relative to the total weight of said fraction and constituting at least a part of said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms incorporated during mixing step b), with the first olefinic stream comprising at least a part of the effluent from oligomerization step a).

12. A process for producing a kerosene base according to the preceding claim, further comprising, after the mixing step b), a hydrogenation step (c) of the mixture of said first olefinic stream comprising at least a part of said effluent from step a) with said second olefinic stream comprising hydrocarbon compounds having 8 carbon atoms.

13. A process according to claim 11, wherein at least a portion of said fraction comprising at least 90% by weight of olefins having 8 carbon atoms relative to the total weight of said fraction is hydrogenated and constitutes at least a portion of said second paraffinic stream incorporated during mixing step b), with the first paraffinic stream obtained after hydrogenation of at least a portion of said effluent from oligomerization step a).

14. A process according to any one of claims 7 to 13, wherein the heterogeneous catalyst used in the oligomerization step a) comprises an amorphous support or a support comprising at least one zeolite having at least pore openings containing 10 or 12 oxygen atoms.

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