Process for producing fuel from a feedstock comprising light olefins, comprising an oligomerization step and a heterogeneous oligomerization step

Abstract

The present invention relates to a process for producing aviation fuel from an olefinic feedstock, said process comprising the following steps: a) a step of fractionating said feedstock and obtaining at least: - a first fraction rich in ethylene and propylene; - a second fraction rich in olefinic compounds having at least 3 carbon atoms; b) a first step of oligomerizing at least a portion of the first fraction obtained from step a) and obtaining at least a first effluent; c) a second step of oligomerizing at least: - a portion of the first effluent obtained from step b), - a portion of the second fraction obtained from step a), and obtaining a second effluent. Figure 1 to be published

Description

Title of the invention: Process for producing fuel from a feedstock comprising light olefins, comprising an oligomerization step and a heterogeneous oligomerization step. Technical field

[0001] The present invention relates to a method for manufacturing fuel, in particular aviation fuel, comprising the conversion of light olefins into heavier olefins by oligomerization technologies. Previous technique

[0002] Demand for Sustainable Aviation Fuels (SAF) is crucial for meeting aviation decarbonization commitments. To achieve the International Civil Aviation Organization's (ICAO) goal of carbon-neutral aviation growth from 2020 onwards, it is necessary to replace fossil-based kerosene with liquid fuels made from bio-based carbon. The global need for SAF production by 2050 is estimated at approximately 500 million tonnes per year.

[0003] In order to achieve this objective, it is necessary to mobilize different types of loads and therefore to develop different technological transformation solutions.

[0004] One of the known transformation routes involves, for example, Methanol; today there are several technologies for generating light olefins from Methanol (MTO route: Methanol To Olefins according to Anglo-Saxon terminology).

[0005] More generally, there are many routes for producing light olefins. Controlled oligomerization of these light olefins makes it possible to produce longer carbon chains that can then be used in the composition of naphtha, gasoline, kerosene or diesel fuel.

[0006] Document FR2620724 describes a process for producing olefin oligomers for the production of premium gasoline, jet fuel, and diesel fuel from light C2 to C8 olefins using a heterogeneous phase oligomerization step. The starting olefins can come from any suitable source. They can also be produced by the catalytic decomposition of methanol.

[0007] However, state-of-the-art aviation fuel manufacturing processes encounter the difficulty of oligomerizing ethylene with heavier olefins, and often propose recycling ethylene in the upstream step at the cost of carbon losses and additional operating costs.

[0008] The applicant has demonstrated surprisingly that separating the olefinic feedstock into a first fraction comprising ethylene mixed with propylene in a particular ratio, and sending this first fraction to a first oligomerization step, preferably in homogeneous phase, makes it possible to convert said first fraction into a stream of heavier olefins, in particular having 4 or more carbon atoms (C4+), which is then sent to a heterogeneous oligomerization step together with a second fraction comprising compounds having 3 or more carbon atoms (C3+), makes it possible to obtain very high selectivity towards a kerosene cut meeting the specifications in force and in particular the specifications of ASTM D7566 or European standard 15940 respectively, while maintaining a satisfactory, or even high, overall conversion of the starting olefinic feedstock.and for reasonable or even limited energy consumption.

[0009] Adding such a first oligomerization unit, preferably in homogeneous phase, of ethylene mixed with a portion of propylene in a particular ratio, to an aviation fuel manufacturing process comprising only a heterogeneous oligomerization section, thus makes it possible to optimally valorize, in particular in terms of energy consumption and kerosene yield, the ethylene and at least a portion of the propylene included in the olefinic feedstocks, in particular from methanol decomposition units (or MTO for Methanol To Olefins according to the Anglo-Saxon expression), by oligomerizing the mixture of ethylene and propylene independently of the other olefins so that the ethylene mixed with propylene is converted into more reactive olefins for the heterogeneous oligomerization step, while limiting the energy consumption of the aviation fuel manufacturing process.

[0010] The objective of the present invention is therefore to improve existing processes for producing aviation fuel from a feed comprising olefins, by limiting, or even reducing, energy consumption without affecting the overall efficiency of the process. Summary of the invention

[0011] The present invention relates to a method for producing fuel from a feed comprising at least 50% by weight of olefins relative to the total weight of the feed and comprising less than 80% by weight of ethylene relative to the total weight of olefins contained in the feed,

[0012] said process comprising the following steps:

[0013] a) a step of splitting said charge to obtain at least:

[0014] - a first fraction comprising ethylene and propylene in a ratio weight ratio between propylene and ethylene present in said first fraction greater than or equal to 0.15, the ethylene present in said first fraction representing at least 85% by weight of the ethylene present in the charge;

[0015] - a second fraction having a content of olefinic compounds having at least 3 carbon atoms of at least 90% by weight of the second fraction;

[0016] b) a first oligomerization step of at least a part of the first fraction from step a) to obtain at least a first effluent comprising at least 60% by weight of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in said first effluent, said first oligomerization step being carried out in the presence of an oligomerization catalyst;

[0017] c) a second oligomerization step of at least a portion of the first effluent from step b), and of at least a portion of the second fraction from step a), to obtain a second effluent comprising at least 85% by weight of olefins having between 8 and 16 carbon atoms, relative to the total weight of olefins contained in said second effluent, said second oligomerization step c) implementing an oligomerization phase carried out in the presence of a heterogeneous catalyst.

[0018] The process according to the invention optionally includes a step d) of hydrogenating at least a portion of the second effluent from step c) to obtain a third effluent comprising at least 90% by weight of paraffins relative to the total weight of hydrocarbon compounds in the third effluent.

[0019] Optionally, the process according to the invention may also include a step e) of fractionating the third effluent from the optional step d) of hydrogenation to obtain at least one aviation fuel type cut.

[0020] The present invention thus makes it possible to optimize the yield of the process in aviation fuel while limiting energy consumption.

[0021] The process according to the invention thus has the advantage, compared to prior art processes, particularly thanks to step a) of fractionation and the first step b) of oligomerization, of maximizing the overall yield of the process. Furthermore, the process of the invention makes it possible to reduce energy consumption, in particular that of step a) of fractionation. List of figures [Fig 1]

[0022] Figure 1 represents an embodiment according to the invention. More particularly, Figure 1 represents a method for producing fuel, in particular aviation fuel, from a feedstock 10 comprising olefins, according to the invention, in which the olefinic charge 10 is sent to a fractionation step a) to produce:

[0023] - a first fraction 11 comprising ethylene and propylene included in an olefinic feedstock 10, the ratio between the weight content of propylene and the weight content of ethylene being greater than or equal to 0.15, the ethylene present in said first fraction representing at least 85% by weight of the ethylene present in the olefinic feedstock 10,

[0024] - a second fraction 12 having a content of olefinic compounds having at least 3 carbon atoms of at least 90% by weight,

[0025] - a heavy fraction 13 comprising a content of at least 90% by weight of benzene and of compounds heavier than this one, present in the charge, and

[0026] - a fraction 18 comprising at least 90% by weight of dimethyl ether (DME) present in the olefinic charge 10.

[0027] According to the invention, by "compounds heavier than benzene" means compounds having a higher boiling point than that of benzene.

[0028] The first fraction 11 is sent to a first oligomerization step b) to produce an effluent comprising at least 60% by weight of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in that effluent, which is then fractionated to obtain a fraction 14 comprising a content of at least 90% by weight of compounds having between 3 and 8 carbon atoms, a fraction 15 comprising a content of at least 90% by weight of compounds having 2 carbon atoms or less relative to the total weight of the fraction, and a fraction 16 comprising a content of at least 90% by weight of compounds having 9 carbon atoms or more relative to the total weight of the fraction. Preferably, among the compounds having between 3 and 8 carbon atoms of said fraction 14, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds.Preferably, among the compounds having 2 or fewer carbon atoms of said fraction 15, at least 70% by weight, preferably at least 80% by weight, and preferably at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 9 or more carbon atoms of said fraction 16, at least 70% by weight, preferably at least 80% by weight, and preferably at least 90% by weight of these compounds are olefinic compounds. At least a portion of fraction 15 may be recycled upstream of step b) of oligomerization (recycling not shown). Fraction 14 from b) and fraction 12 from a) are mixed into a stream 20 which is sent to a heterogeneous oligomerization step c) to produce an effluent 21 comprising at least 85% by weight of olefins having between 8 and 16 carbon atoms relative to the total weight of the . olefins contained in this effluent. The effluent 21 from c) and the fraction 16 from b) are mixed into a stream 22 which is sent to an olefin hydrogenation step d) to produce an effluent 24 comprising a paraffin content of at least 90% by weight relative to the total weight of hydrocarbon compounds and a purge 23, particularly in gaseous form, comprising unreacted hydrogen and lighter gases. The effluent 24 is sent to a fractionation step e) to produce a gas stream 25 which is purged, a naphtha-type cut 26, an aviation fuel-type cut 27, and a diesel-type cut 28. [Fig 2]

[0029] Figure 2 represents another embodiment according to the invention. More particularly, Figure 2 represents a process for producing fuel, in particular aviation fuel, from an olefinic feedstock comprising olefins according to the invention, step c) of said process comprising two heterogeneous oligomerization steps c1) and c2).

[0030] The olefinic charge 10 is sent to a fractionation step a) to produce:

[0031] - a first fraction 11 comprising ethylene and propylene included in said olefinic charge 10, the ratio between the weight content of propylene and the weight content of ethylene being greater than or equal to 0.15, the ethylene present in said first fraction representing at least 85% by weight of the ethylene present in the olefinic charge 10,

[0032] - a second fraction 12 having a content of olefinic compounds having at least 3 carbon atoms of at least 90% by weight,

[0033] - a heavy fraction 13 comprising a content of at least 90% by weight of benzene and of compounds heavier than this one present in the charge, and

[0034] - a fraction 18 comprising at least 90% by weight of the DME present in the charge olefinic 10.

[0035] The first fraction 11 is sent to a first oligomerization step b) to produce an effluent comprising at least 60% by weight of olefins having 3 or more carbon atoms, relative to the total weight of olefins contained in that effluent, which is then fractionated to obtain a fraction 14 comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms, a fraction 15 comprising at least 90% by weight of compounds having 2 or fewer carbon atoms relative to the total weight of the fraction, and a fraction 16 comprising at least 90% by weight of compounds having 9 or more carbon atoms (C9+ fraction) relative to the total weight of the fraction. Preferably, among the compounds having between 3 and 8 carbon atoms in said fraction 14, at least 70% by weight, preferably at least 80% Preferably, at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 2 or fewer carbon atoms in said fraction 15, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 9 or more carbon atoms in said fraction 16, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds. At least a portion of fraction 15 can be recycled upstream of the first oligomerization step b) (recycling not shown). The fraction 14 from b) and the fraction 12 from a) are mixed into a stream 20 which is sent to a heterogeneous oligomerization step c) comprising a first heterogeneous oligomerization step cl) and a second heterogeneous oligomerization step c2).More specifically, stream 20 feeds the first heterogeneous oligomerization step (c1) to produce an oligomerization effluent that is fractionated into a fraction 30 comprising at least 85% by weight of compounds having between 3 and 8 carbon atoms, and a fraction 31 comprising at least 90% by weight of compounds having 9 or more carbon atoms. Preferably, among the compounds having between 3 and 8 carbon atoms in said fraction 30, at least 50% by weight, preferably at least 60% by weight, and preferably at least 70% by weight of these compounds are olefinic compounds. Preferably, among compounds comprising a content of at least 90% by weight of compounds having 9 or more carbon atoms of said fraction 31, at least 70% by weight, preferably at least 80% by weight and preferably at least 90% by weight of these compounds are olefinic compounds.Fraction 30 is divided into two parts: a first part of fraction 30 is recycled to the inlet of step c1), and a second part, corresponding to stream 32, which is sent to the second heterogeneous oligomerization step c2). The second heterogeneous oligomerization step c2) produces an effluent of which a first part is recycled to the inlet of step c2) and another part, stream 33, is mixed with fraction 31 from c1) to obtain a stream 21 comprising at least 85% by weight of olefins having between 8 and 16 carbon atoms relative to the total weight of olefins contained in this stream.The stream 21 is then mixed with the fraction 16 from step b) to obtain a stream 22 which is sent, possibly together with at least part of the heavy fraction 13 from step a), to an olefin hydrogenation step d) to produce an effluent 24 comprising a paraffin content of at least 90% by weight relative to the total weight of hydrocarbon compounds and a purge 23, in particular in gaseous form, comprising unreacted hydrogen and the lightest gases. The effluent 24 is sent. to a fractionation step e) to produce a gas purge 25, a naphtha-type cut 26, an aviation fuel-type cut 27 and a diesel-type cut 28. [Fig 3]

[0036] Fig. 3 represents a particular embodiment of step a) of the process of producing fuel, in particular aviation fuel, from a feed comprising olefins, according to the invention.

[0037] The olefinic feed 10 feeds a first distillation column m), implemented in step a), which allows the majority of olefinic compounds with 3 carbon atoms or less (product 101) to be recovered at the top of column m), and the majority of olefinic compounds with 4 carbon atoms or more as well as dimethyl ether (or DME for dimethyl ether according to the Anglo-Saxon term) (product 103) at the bottom of column m).

[0038] By "the majority of olefinic compounds", we mean at least 50% by weight of the olefinic compounds present in the olefinic charge relative to the total weight of the olefinic charge.

[0039] The product 101 recovered at the top of distillation column m) is compressed in a compressor, then feeds a second distillation column o). This column o) fractionates the compressed product 101 and allows the recovery of: a stream 11 at the top of column o) which comprises at least 85% by weight of the compounds with 2 carbon atoms or less, mixed with a portion of the olefins having 3 carbon atoms (or propylene), contained in the product 101; and a stream 104 at the bottom of column o) comprising more than 50% by weight of the compounds with 3 carbon atoms or more contained in the product 101 and possibly another portion of the olefins having 3 carbon atoms (or propylene). Preferably, among the compounds with 3 or more carbon atoms in the 104 stream, at least 70% by weight, preferably at least 80% by weight, preferably at least 80% by weight of these compounds are olefinic compounds.

[0040] The ratio between the weight content of propylene and the weight content of ethylene in stream 11, produced at the top of column o), is greater than or equal to 0.15. The weight content of ethylene in stream 104, produced at the bottom of column o), is less than 0.01%.

[0041] Cooling at the top of the column o) is provided by a propane refrigeration unit p) to ensure condensation at the top of the column.

[0042] The flow 11 produced at the top of the second column o) will then be directed to an oligomerization step b) (not shown in [Fig.3]).

[0043] Step a) of the particular embodiment shown in [Fig. 3] employs a third distillation column n) to fractionate the bottom product 103 from the first column m) and recover at the top of column n) a fraction containing more than 50% by weight of the DME present in the olefinic feed 10, and at the bottom of column n) a cut containing more than 50% by weight of compounds with 4 or more carbon atoms (stream 105) present in the olefinic charge 10. Preferably, among the compounds with 4 or more carbon atoms in stream 105, at least 70% by weight, preferably at least 80% by weight, preferably at least 80% by weight of these compounds are olefinic compounds.

[0044] The stream 104 produced at the bottom of the second column o) is mixed with the stream 105 produced at the bottom of the third column n) to constitute the stream 12 which will then be directed to a heterogeneous oligomerization step c) (not shown in [Fig. 3]), advantageously mixed with at least a portion of the effluent obtained at the end of the oligomerization step b) of said stream 11 (mixture not shown in [Fig. 3]). [Fig. 4]

[0045] Fig. 4 represents the evolution of the electrical consumption (in kilowatts or kW) of the refrigeration unit p) illustrated in Fig. 3, shown in solid lines in Fig. 4, and the hourly production yield (in kilograms per hour or kg / hr) of a 130°C-290°C kerosene-type cut of the process, as a function of the weight ratio between propylene and ethylene, in the flow 11 of Fig. 3, in a fuel production process according to Figures 2 and 3). Description of the implementation methods

[0046] 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 in the described range of values. If this is not the case and the limit values ​​are not included in the described range, such clarification will be provided by the present invention.

[0047] 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.

[0048] 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.

[0049] In this description, the expressions "dimethyl ether enriched cut", "dimethyl ether enriched cut" and "DME enriched cut" are used equivalently and mean that the concentration of dimethyl ether in the resulting cut is greater than that of the starting cut.

[0050] 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 IUP AC classification, and group IB according to the CAS classification corresponds to the metals in column 11 according to the new IUP AC classification.

[0051] In the following, particular embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation of combinations where technically feasible.

[0052] In this application, the term “include” is synonymous with (means the same as) “include” and “contain,” and is inclusive or open and does not exclude other unstated elements. It is understood that the term “include” includes the exclusive and closed term “consist.”

[0053] In this application, the term "t / h" means tonne per hour, the term "kg / h" means kilogram per hour and the term "kw" means kilowatt.

[0054] The invention relates to a process for producing fuel, in particular aviation fuel, from an olefinic feedstock comprising light olefins, in particular olefins having between two and eight carbon atoms (C2-C8), preferably between two and six carbon atoms (C2-C6), exhibiting a yield equivalent to or even improved upon prior art processes, and limited and possibly reduced energy consumption. In particular, the applicant has shown that the ratio between the weight content of propylene and the weight content of ethylene in the fraction sent to a first oligomerization step (b), said oligomerization preferably being homogeneous phase, can affect energy consumption, while optimizing the kerosene yield of the process.The applicant then demonstrated in a surprising manner that such a ratio greater than or equal to 0.15, preferably greater than or equal to 0.3, preferably greater than or equal to 0.4 and preferably less than or equal to 0.8, preferably less than or equal to 0.6, made it possible to reduce energy consumption while preserving or even improving the overall efficiency of the process in aviation fuel. Olefinic charge

[0055] According to the invention, the charge containing olefins, in particular light olefins, particularly having between 2 and 8 carbon atoms, preferably between 2 and 6 carbon atoms, and in particular comprising ethylene and propylene, comprises:

[0056] - a content greater than or equal to 50% by weight, preferably greater than or equal to at 65% by weight, preferably greater than or equal to 80% by weight of olefins, in particular light olefins, in particular olefins having between 2 and 8 carbon atoms, and particularly olefins having between 2 and 6 carbon atoms, the percentages being advantageously expressed in relation to the total weight of said charge;

[0057] - less than 80% by weight, preferably less than 65% by weight, preferably less than 50% by weight of ethylene relative to the total weight of olefins contained in the feed.

[0058] The olefinic filler according to the invention comprises ethylene, preferably at least 5% by weight of ethylene relative to the total weight of the filler.

[0059] Advantageously, the charge comprises between 2% and 30% by weight, preferably between 5% and 25%, preferably between 7% and 15% of ethylene relative to the total weight of olefins contained in the charge.

[0060] Advantageously, the charge comprises more than 40% by weight, preferably more than 45%, preferably more than 50% by weight of propylene, relative to the total weight of olefins contained in the charge.

[0061] Advantageously, the charge comprises at least 95% by weight, preferably at least 97% by weight, preferably at least 98% by weight of olefins having between 2 and 6 carbon atoms relative to the total weight of olefins contained in the charge.

[0062] Advantageously, the charge comprises at least 80% by weight of olefinic compounds having between 3 and 6 carbon atoms relative to the total weight of the charge.

[0063] In a particular embodiment, the charge may further comprise olefinic compounds having more than 6 carbon atoms, preferably compounds having between 7 and 8 carbon atoms.

[0064] Advantageously, the charge comprises at least 80% by weight of olefins having between 3 and 6 carbon atoms relative to the total weight of olefins contained in the charge.

[0065] Advantageously, the charge comes from a catalytic decomposition unit of alcohol, preferably from a catalytic decomposition unit of methanol or possibly ethanol.

[0066] In a particular embodiment, the charge further comprises dimethyl ether, or Dimethylether (DME) according to the Anglo-Saxon term.

[0067] In another particular embodiment, the charge may come from cracking and / or dehydration units of heavier alcohols such as, for example, propanol or butanol, or from an FCC (Fluid Catalytic Cracking) type unit, or from steam cracking.

[0068] Preferably, the feedstock does not originate from an ethanol dehydration unit (ETE route: Ethanol To Ethylene according to Anglo-Saxon terminology). Operating conditions and catalysts Step a) of fractionation

[0069] The process according to the invention comprises a step a) of fractionating said olefinic feedstock to obtain at least:

[0070] - a first fraction comprising ethylene and propylene in a ratio weight ratio between propylene and ethylene present in said first fraction greater than or equal to 0.15, preferably greater than or equal to 0.3, preferably greater than or equal to 0.4 and preferably less than or equal to 0.8, preferably less than or equal to 0.6, the ethylene present in said first fraction representing at least 85% by weight, preferably at least 90% by weight, preferably at least 95% by weight of the ethylene present in the feed entering at step a);

[0071] - a second fraction having an olefinic compound content of at least 3 carbon atoms of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of the second fraction.

[0072] In one embodiment of the invention, the propylene present in said first fraction from step a) represents at least 10% by weight, preferably at least 20% by weight, and preferably at least 30% by weight, relative to the total weight of said first fraction.

[0073] Step a) of fractionation can be carried out by any means known to those skilled in the art, for example by distillation, preferably continuous, in particular by using one or more (preferably two, three, or four) successive and / or parallel distillation columns, or by multi-cut distillations, continuously or in batches, advantageously using at least one side draw-off to extract at least one intermediate boiling cut. Columns with internal walls can also be used to carry out this fractionation (or separation), while limiting energy consumption. The use, as a complement or replacement, of solutions using molecular sieves or separation membranes is also a possibility for separating the feed into various cuts.

[0074] In a particular embodiment of the invention, step a) further enables the production of a heavy fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, and more preferably at least 98% by weight of benzene and compounds heavier than benzene. "Compounds heavier than benzene" means compounds having a boiling point higher than that of benzene, in particular a boiling point above 80°C (at atmospheric pressure, more particularly at 0.1 MPa).

[0075] In a preferred embodiment of this particular embodiment, at least a portion of the heavy fraction from step a) is sent to the hydrogenation step d). Optionally, the heavy fraction is fractionated, advantageously prior to sending all or part of said heavy fraction to step d), in order to recover a fraction comprising compounds heavier than benzene, which will be sent at least in part to the hydrogenation step d).

[0076] In another particular embodiment of the invention, step a) also makes it possible to obtain a dimethyl ether enriched cut, i.e. a fraction comprising at least 90%, preferably at least 95%, preferably at least 98% of the dimethyl ether (DME) contained in the feed supplying step a)

[0077] This fractionation step a) is advantageously designed to isolate compounds that could negatively impact subsequent reactions and oligomerization catalysts, and in particular aims to eliminate DME when the feedstock originates from an MTO unit. This step a) also allows for judicious adjustment of the weight ratio of propylene to ethylene in the first fraction.

[0078] In a very particular embodiment, said fraction containing the DME, advantageously separated in step a), is recycled in a catalytic alcohol decomposition unit upstream of step a). Step b) of first oligomerization

[0079] The process according to the invention includes a first oligomerization step of at least a part of the first fraction from step a) to obtain at least a first effluent comprising at least 60% by weight of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in said first effluent, said first oligomerization step being carried out in the presence of an oligomerization catalyst.

[0080] Advantageously, the first effluent from the first oligomerization step b) comprises less than 20% by weight, preferably less than 10% by weight, preferably less than 5% by weight of ethylene, relative to the total weight of olefins contained in said first effluent.

[0081] Advantageously, at least a part, i.e. at least 50% by weight, preferably at least 70% by weight, preferably 90% by weight, of the first fraction from step a), and preferably the whole of said fraction, is subjected to said first oligomerization step.

[0082] Advantageously, the first step b) of oligomerization leads to the production of a first effluent comprising at least 60% by weight, preferably at least 80% by weight, of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in said olefinic effluent. In particular, said first effluent is rich in olefinic hydrocarbons having a number of carbon atoms between 3 and 8 and may also include olefinic hydrocarbons having 9 or more carbon atoms (C9+). More particularly, said first effluent produced during the first oligomerization step b), advantageously comprises at least 80% by weight, preferably at least 90% by weight, of olefinic compounds having a number of carbon atoms between 3 and 8 (and particularly up to 100% by weight, very particularly up to 97% by weight, of olefinic compounds having a number of carbon atoms between 3 and 8), and advantageously less than 20% by weight and preferably less than 10% by weight, of olefinic compounds having a number of carbon atoms greater than or equal to 9, for example at least 1% by weight, preferably 0.1% by weight of olefinic compounds having a number of carbon atoms greater than or equal to 9, the weight percentages being expressed in relation to the total mass of olefins contained in said first effluent, .

[0083] The oligomerization catalyst used in step b) can be any oligomerization catalyst known to those skilled in the art. The oligomerization catalyst can be in homogeneous form, i.e., the catalyst is soluble in the liquid phase comprising in particular the introduced ethylene and propylene and their oligomerization products, or in heterogeneous, insoluble form.

[0084] In a particular embodiment, the catalyst used in the first oligomerization step b) is a heterogeneous oligomerization catalyst. The heterogeneous oligomerization catalyst advantageously comprises at least one element from Group VIII and at least one porous oxide refractory support, preferably selected from alumina, silica, silica-aluminas, zirconia, titanium dioxide, magnesia, and clays, either alone or in mixtures. The Group VIII element is preferably selected from nickel, cobalt, iron, platinum, and palladium. Preferably, said Group VIII element is nickel. The heterogeneous oligomerization catalyst may also comprise one or more additional elements, in particular selected from elements of Groups VI, IA, and IIA. For example, the Group VI element is selected from chromium, molybdenum, and tungsten. The element from group IA is chosen from lithium, sodium or potassium.The group IIA element is chosen from magnesium, calcium, and strontium. Preferably, the support is alumina or silica-alumina. The support may, in particular, be an amorphous silica-alumina comprising between 70 and 99.5% by weight of SiO2, with the remainder being alumina.

[0085] When the first oligomerization step b) is carried out with a heterogeneous oligomerization catalyst, it is advantageously carried out at a temperature between 30 and 400°C, preferably between 50 and 300°C, at an absolute pressure between 0.5 and 10 MPa, preferably between 1 and 10 MPa and preferably between 1 and 8 MPa, and at a weight hourly space velocity (WHSV according to Anglo-Saxon terminology), defined as the ratio between the total mass flow of the incoming charge and the total mass of catalyst, between 0.1 and 10 h 1 and preferably between 0.4 and 5 h 1.

[0086] In a preferred embodiment of the invention, the catalyst used in the first oligomerization step b) is a homogeneous oligomerization catalyst. Advantageously, the homogeneous oligomerization catalyst used in the oligomerization step b) of the process according to the invention preferably comprises:

[0087] - at least one nickel precursor with oxidation state (+11), and

[0088] - at least one activating agent chosen from the group formed by chlorinated compounds and brominated hydrocarbylaluminium, taken alone or in mixtures.

[0089] Optionally, the homogeneous oligomerization catalyst used in step b) of oligomerization further comprises at least one Brønsted organic acid, or at least one carboxylic acid anhydride, or at least one phosphine ligand of formula PR1R2R3 in which the RI, R2 and R3 groups are identical or different from each other, linked or not to each other.

[0090] Nickel compounds with an oxidation state of (+11) (or divalent nickel compounds) are preferably compounds soluble at a concentration of more than one gram per liter in hydrocarbon medium, and more particularly in the reactants and the reaction medium. Preferably, the nickel compounds with an oxidation state of (+11) advantageously included in the homogeneous oligomerization catalyst are nickel carboxylates of the general formula (RCOO)2Ni, where R is a hydrocarbyl radical, for example, alkyl, cycloalkyl, alkenyl, aryl, aralkyl, or alkaryl, containing up to 20 carbon atoms, preferably a hydrocarbyl radical of 5 to 20 carbon atoms. The radical R may be substituted by one or more halogen atoms, by one or more hydroxyl, ketone, nitro, cyano groups, or other groups that do not interfere with the reaction. The R radical can also be made up of an alkylene radical of 6 to 18 carbon atoms.Preferably, divalent nickel compounds are advantageously chosen from the following divalent nickel salts: octoate, ethyl-2-hexanoate, decanoate, stearate, oleate, salicylate, and hydroxydecanoate, taken alone or in mixtures. Preferably, the divalent nickel compound is nickel ethyl-2-hexanoate.

[0091] The activating agent is advantageously chosen from the group formed by chlorinated and brominated hydrocarbylaluminium compounds corresponding to the formula A1RX2, in which R is a hydrocarbyl radical and X is a halogen chosen from chlorine and bromine, alone or in mixtures. The hydrocarbylaluminium halides are preferably chosen from dichloroethylaluminu. m, dichloroisobutylaluminium, dibromoethylaluminium, and mixtures thereof. These hydrocarbylaluminium dihalides can be advantageously enriched with aluminium trihalides (A1X3) such as aluminium trichloride.

[0092] The Brønsted organic acid compounds, optionally included in the homogeneous oligomerization catalyst used in step b), preferably correspond to the formula HY, where Y is an organic anion, for example carboxylic, sulfonic, or phenolic. These Brønsted organic acid compounds preferably have a pKa at 20°C of no more than 3 and are preferably selected from the group formed by halocarboxylic acids of formula RCOOH, in which R is a halogenated alkyl radical and preferably a halogenated alkyl radical containing at least one halogen atom alpha to the -COOH group, with a total of 2 to 10 carbon atoms. Preferably, an optionally used Brønsted organic acid compound in the homogeneous oligomerization catalyst of step b) is a haloacetic acid of formula CXpH(3-p)-COOH in which X is fluorine, chlorine, bromine or iodine, with p an integer from 1 to 3.Examples include trifluoroacetic, difluoroacetic, fluoroacetic, trichloroacetic, dichoroacetic, and chloroacetic acids. These examples are not exhaustive. Arylsulfonic, alkylsulfonic, fluoroalkylsulfonic acids, picric acid, and nitroacetic acid can also be used.

[0093] The homogeneous oligomerization catalyst used in the first oligomerization step (b) may also optionally contain at least one carboxylic acid anhydride of formula (RCO)2O, in which R is preferably a hydrocarbyl radical that may advantageously contain one or more halogen atoms. Preferred carboxylic acid anhydrides are advantageously chosen from octoic, 2-ethylhexanoic, decanoic, stearic, oleic, trifluoroacetic, monofluoroacetic, trichloroacetic, monochloroacetic, pentafluoropropionic, or heptafluorobutyric anhydrides, taken alone or in mixtures. Preferably, the carboxylic acid anhydride optionally included in the homogeneous oligomerization catalyst used in step (b) is trifluoroacetic acid anhydride.

[0094] Finally, the homogeneous oligomerization catalyst used in the first oligomerization step b) may also optionally contain a phosphine ligand of formula PR1R2R3 in which the RI, R2, and R3 groups are preferably hydrocarbyl groups, identical or different from each other, bonded or not. The hydrocarbyl groups RI, R2, and R3 of the phosphine ligand PR1R2R3 advantageously comprise 1 to 20 carbon atoms, preferably 2 to 15 carbon atoms, and preferably between 3 and 10 carbon atoms. Preferably, the hydrocarbyl groups RI, R2, and R3 of the phosphine ligand PR1R2R3 are chosen in the group formed by the methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, cyclopentyl, cyclohexyl, benzyl, adamantyl groups.

[0095] Most advantageously, the homogeneous oligomerization catalyst used in oligomerization step b) is in liquid form. Preferably, the homogeneous oligomerization catalyst has a molar ratio of the hydrocarbylaluminum halide to the nickel compound, expressed as the Al / Ni ratio, of 2:1 to 50:1, and preferably from 2:1 to 20:1. If the homogeneous oligomerization catalyst includes Brønsted acid, the molar ratio of Brønsted acid to the nickel compound is 0.25:1 to 10:1, and preferably from 0.25:1 to 5:1. If the homogeneous oligomerization catalyst includes carboxylic acid anhydride, the molar ratio of carboxylic acid anhydride to nickel compound is advantageously between 0.001 / 1 and 1 / 1, very advantageously between 0.01 / 1 and 0.5 / 1.If the homogeneous oligomerization catalyst comprises a phosphine-type ligand, the molar ratio of the phosphine-type ligand to the nickel compound is advantageously between 2 and 25, preferably between 5 and 20, more preferably between 5 and 15.

[0096] Preconditioning of the homogeneous oligomerization catalyst can be carried out before contacting the catalyst with the first fraction comprising ethylene and propylene. Preconditioning the homogeneous oligomerization catalyst (or the catalytic composition) consists of mixing the three components of the homogeneous oligomerization catalyst in a hydrocarbon solvent, for example, an alkane or an aromatic hydrocarbon, or a halogenated hydrocarbon, or preferably the olefins produced during the oligomerization reaction, under stirring and in an inert atmosphere, for example, nitrogen or argon, at a controlled temperature between 0 and 80 °C, preferably between 10 and 60 °C, for a period of 1 minute to 5 hours, preferably 5 minutes to 1 hour. The resulting solution is then transferred under an inert atmosphere to the oligomerization reactor.

[0097] This preconditioning of the homogeneous oligomerization catalyst makes it possible to increase the activity of the catalyst in the oligomerization in particular of ethylene.

[0098] In one embodiment, said homogeneous catalyst is the catalyst described in document WO2017017087.

[0099] Preferably, the first oligomerization step b) is carried out by homogeneous catalysis, i.e., using a homogeneous oligomerization catalyst, and is advantageously performed continuously: the catalytic solution is injected into the unit operating the first oligomerization step b) and the first fraction from step a) comprising ethylene and propylene is injected continuously. The unit operating said first oligomerization step b) by homogeneous catalysis comprises advantageously one or more perfectly stirred reactors, in particular operating in series, preferably with recycling of at least part of the reactor effluent into the reactor, this recycling being advantageously cooled before being reinjected.

[0100] In the preferred embodiment of the invention in which the first step b) of oligomerization is carried out by homogeneous catalysis, the first step b) of oligomerization can advantageously be carried out in a reactor with one or more series reaction stages, the first fraction from step a) and / or the catalytic composition, preferably pre-conditioned, being introduced continuously, either into the first stage, or into the first and any other of the stages.

[0101] According to this preferred embodiment of the invention, the operating conditions in the reactor(s) carrying out the oligomerization step by homogeneous catalysis are such that the temperature is between -20 °C and +80 °C and the pressure is sufficient to allow the existence of a liquid phase in the reactor(s). Preferably, the total absolute pressure in the reactor(s) is between 0.5 and 8.0 MPa. At the outlet of the first oligomerization step b) implemented by homogeneous catalysis, the homogeneous catalytic system is mixed with the compounds produced during step b) and the ethylene and / or propylene that did not react. Advantageously, the effluent recovered from the reaction unit implemented in step b) (i.e. from the reactor or the last reactor in the series implemented) undergoes at least one treatment / separation step of the homogeneous catalytic system of said reaction effluent.

[0102] The expression "treatment / separation step of the homogeneous catalytic system of said reaction effluent" means a step in which said catalytic system is deactivated and separated from the homogeneous reaction medium and in particular from an olefinic effluent comprising the products generated during oligomerization and possibly unconverted ethylene and / or propylene, advantageously corresponding to the first effluent from the first step b) of oligomerization and which is at least partly sent to the second oligomerization step c).

[0103] In a very particular embodiment of the invention, the first effluent from the first oligomerization step b) undergoes a fractionation step to obtain at least one fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, and preferably at least 98% by weight, of compounds having between 3 and 8 carbon atoms, which is sent to the second oligomerization step c), and a fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, and preferably at least 98% by weight, of compounds having 9 or more carbon atoms (C9+), also called the fraction C9+, which is sent to step d) of hydrogenation. Preferably, among the compounds having between 3 and 8 carbon atoms in said fraction, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 9 or more carbon atoms (C9+) in said fraction, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds.

[0104] In another embodiment of the invention, the first effluent from the first oligomerization step b) undergoes a fractionation step to obtain a fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of compounds having between 3 and 8 carbon atoms, which is sent to the second oligomerization step c), and a fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of compounds having 2 carbon atoms or less, which is advantageously purged, and optionally a fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of compounds having 9 or more carbon atoms (C9+), which is sent to the hydrogenation step d).At least a portion of the fraction comprising at least 90% by weight, preferably at least 95% by weight, and preferably at least 98% by weight of compounds having 2 or fewer carbon atoms, may be recycled upstream of oligomerization step b). Preferably, among the compounds having between 3 and 8 carbon atoms in said fraction, at least 70% by weight, preferably at least 80% by weight, and preferably at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 2 or fewer carbon atoms in said fraction, at least 70% by weight, preferably at least 80% by weight, and preferably at least 90% by weight of these compounds are olefinic compounds. Preferably, among the compounds having 9 or more carbon atoms (C9+) of said fraction, at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight of these compounds are olefinic compounds.

[0105] An example of a first oligomerization step b) is the DimEne-B® process marketed by Axens. Another example of a first oligomerization step b) is the Dimersol-E® process marketed by Axens. Step c) of second oligomerization

[0106] The process according to the invention comprises a second step (c) of oligomerizing at least a portion of the first effluent from step (b), and at least a portion of the second fraction from step (a), to obtain a second effluent comprising at least 85% by weight, preferably at least 90% by weight, preferably in a manner less than 95% by weight of olefins having between 8 and 16 carbon atoms, relative to the total weight of olefins contained in said second effluent, said second oligomerization step c) being carried out in the presence of a heterogeneous catalyst comprising an amorphous support or a support comprising at least one zeolite.

[0107] According to a first embodiment of the invention, the heterogeneous catalyst used in the second oligomerization step c) is a catalyst comprising an amorphous support. Advantageously, said amorphous catalyst comprises, and preferably is made of, an amorphous mineral material selected from silica-aluminas and silicified aluminas.

[0108] According to a very particular embodiment in which a silica-alumina is used as a catalyst for the second oligomerization step c), said silica-alumina makes it possible to carry out said oligomerization, in particular of at least a portion of the first effluent from step b) and a portion of the second fraction from step a), with better control of the reactivity of the olefins, making it possible in particular to operate at a low-pass conversion level and, very advantageously, to optimize the selectivity towards the desired olefins having 7 or more carbon atoms, in particular having between 10 and 12 carbon atoms, compared to oligomerization in the presence of other catalysts, for example zeolites. Furthermore, coke formation appears to be less significant and less rapid in the presence of silica-alumina than in the presence of zeolites. Thus, silica-alumina requires regeneration at a lower frequency than zeolites.

[0109] According to a second embodiment of the invention, the heterogeneous catalyst used in the second oligomerization step (c) is a catalyst comprising a support including at least one zeolite. Advantageously, said zeolite 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 catalyst preferably comprises a zeolite selected from structural zeolites of type MFI, MTW, MOR, TON, MEL, MFS, MTT, taken alone or in mixtures.Preferably, the zeolite catalyst used in the second oligomerization step c) 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 structurer triethylenetetramine.

[0110] According to the second embodiment of the invention, the zeolite used in the catalyst in step c) 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.

[0111] Said heterogeneous catalyst used in step c) of the process according to the invention, in particular said zeolitic catalyst, also advantageously comprises at least one oxide-type matrix, also called a binder. A matrix according to the invention is understood to be an amorphous or poorly crystallized material. Said 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 oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, and carbon. Preferably, said matrix is ​​selected from the group consisting of aluminas, clays, and silicas; more preferably, said matrix is ​​selected from aluminas; and even more preferably, said matrix is ​​gamma alumina.

[0112] Advantageously, the catalysts used in step c) 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.

[0113] Advantageously, the second oligomerization step (c) is carried out in at least one reactor, in particular a fixed-bed reactor. Preferably, the second oligomerization step (c) is carried out in one, two, or three reactors, in particular a fixed-bed reactor.

[0114] Advantageously, the second oligomerization step c) of the process according to the invention operates at a temperature between 20 and 500°C, preferably between 100 and 350°C and preferably between 100 and 300°C, at a pressure between 1.0 and 10 MPa, preferably between 2 and 8 MPa and preferably between 3 and 7 MPa and with a WH preferably between 0.1 and 0.5 h1, preferably between 0.2 and 0.3 h1.

[0115] 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).

[0116] Preferably, the second effluent from the second oligomerization step c) comprises less than 20% by weight, preferably less than 10% by weight, of unreacted C4 olefins, the weight percentages being expressed in relation to the total mass of olefins contained in said second effluent.

[0117] According to one embodiment, the effluent recovered from the reaction unit implemented in step c) (i.e., from the reactor or the last reactor in the series implemented) undergoes a fractionation step into at least:

[0118] - a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably at least 98% by weight of compounds having between 3 and 4 carbon atoms, which is advantageously partly purged and / or partly recycled upstream of step c),

[0119] - and a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably less than 98% by weight of compounds having between 8 and 16 carbon atoms, constituting said second effluent of step c), which is sent to step d) of hydrogenation.

[0120] Preferably, among the compounds having between 3 and 4 carbon atoms of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0121] Preferably, among compounds having between 8 and 16 carbon atoms of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0122] In a particular embodiment, the effluent recovered from the reaction unit implemented in step c) (i.e., from the reactor or the last reactor in the series implemented) undergoes a fractionation step into at least:

[0123] - a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably at least 98% by weight of compounds having between 3 and 8 carbon atoms,

[0124] - a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably at least 98% by weight, of compounds having 9 or more carbon atoms (C9+) and constituting said second effluent of step c).

[0125] Preferably, among compounds having between 3 and 8 carbon atoms of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0126] Preferably, among compounds having 9 or more carbon atoms (C9+) of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0127] According to this particular embodiment, the fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of compounds having 9 or more carbon atoms (C9+) is advantageously sent to the hydrogenation step d). Advantageously, at least a portion of the fraction comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of compounds having between 3 and 8 carbon atoms, from the fractionation phase of c), is recycled to the oligomerization phase of the second oligomerization step c).

[0128] Advantageously, the second effluent from the second oligomerization step c) comprises less than 20% by weight and preferably less than 10% by weight of C4-C8 olefinic compounds, the weight percentages being expressed in relation to the total mass of olefins contained in said second effluent.

[0129] An example of a second oligomerization step c) is the Polynaphta® process marketed by the company Axens.

[0130] Advantageously, the second effluent from the heterogeneous oligomerization step c), which comprises a content of at least 85% by weight, preferably at least 90% by weight, preferably at least 95% by weight of olefins having between 8 and 16 carbon atoms, is then sent, in whole or in part, to the hydrogenation step d).

[0131] In a specific embodiment of the invention, the second oligomerization step c) implements two phases (or steps) of heterogeneous oligomerization, in particular a first heterogeneous oligomerization step cl) and a second heterogeneous oligomerization step c2).The first step cl) is at least fed by the second fraction from the fractionation of step a) and the fraction comprising a content of at least 90% by weight of compounds having between 3 and 8 carbon atoms from the fractionation of the first effluent obtained in step b) of oligomerization, and is carried out in the presence of a heterogeneous oligomerization catalyst, as described above, at a temperature between 20 and 500°C, preferably between 100 and 350°C and preferably between 100 and 300°C, at a pressure between 1.0 and 10 MPa, preferably between 2 and 8 MPa and preferably between 3 and 7 MPa and with a WH preferably between 0.1 and 0.5 h1, preferably between 0.2 and 0.3 h*. Preferably, among the compounds having between 3 and 8 carbon atoms of said fraction, at least 50% by weight, preferably at least 60% by weight and preferably at least 70% by weight of these compounds are olefinic compounds.

[0132] The effluent obtained at the end of the first step cl) is partly or totally sent to the second step c2).

[0133] Preferably, the effluent from the reactor of the heterogeneous oligomerization step cl) undergoes fractionation into at least two fractions: - A fraction comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% of C3-C8 compounds. - A fraction comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of compounds having 9 or more carbon atoms (C9+), which is partly or totally sent to the second heterogeneous oligomerization step c2)

[0134] Preferably, among the C3-C8 compounds of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0135] Preferably, among compounds having 9 or more carbon atoms (C9+) of said fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0136] According to one embodiment, at least a portion of the fraction comprising at least 90%, preferably at least 95% by weight, preferably at least 98% of compounds having between 3 and 8 carbon atoms from the fractionation phase of c) is recycled into the first step c1) of heterogeneous oligomerization and at least another portion comprising at least 90%, preferably at least 95% by weight, preferably at least 98% of compounds having between 3 and 8 carbon atoms from the fractionation phase of c) is sent to the second step c2) of heterogeneous oligomerization, to obtain an oligomerization effluent from the second step c2) of heterogeneous oligomerization.

[0137] In a particular embodiment, the effluent exiting the reactor of the heterogeneous oligomerization step cl) undergoes fractionation into at least three fractions: - A first fraction comprising at least 85% by weight, preferably at least 90% by weight, preferably at least 95% of C3-C8 compounds, at least part of which will be recycled to step cl). - A second fraction comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% of C3-C8 compounds, at least a portion of which will be sent to step c2) - A third fraction comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of compounds having 9 or more carbon atoms (C9+), which is advantageously sent at least partly to a step d).

[0138] Preferably, among the C3-C8 compounds of said first fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0139] Preferably, among the C3-C8 compounds of said second fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0140] Preferably, among the compounds having 9 or more carbon atoms (C9+) of said third fraction, at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0141] Optionally the first and second fractions are of identical composition.

[0142] The second heterogeneous oligomerization step c2) operates in the presence of a heterogeneous oligomerization catalyst, advantageously with the same catalyst as step cl), at a temperature between 50 and 500°C, preferably between 100 and 350°C and preferably between 130 and 300°C, at a pressure between 2.0 and 12 MPa, preferably between 2 and 10 MPa and preferably between 4 and 7 MPa and with a WH preferably between 0.1 and 1.0 h-1, preferably between 0.3 and 0.6 h-1.

[0143] Advantageously, an oligomerization effluent is obtained at the end of the second heterogeneous oligomerization step c2); it is at least partially sent to the hydrogenation step d). Preferably, a first part of the oligomerization effluent from the second heterogeneous oligomerization step c2 is recycled to the inlet of this second step c2), the second part being advantageously sent to the hydrogenation step d). Step d) of optional hydrogenation.

[0144] The process according to the invention may include a step d) of hydrogenating at least a portion of the second effluent from step c) and to obtain a third effluent comprising a content of at least 90% by weight of paraffins, the percentages being advantageously given by weight relative to the total weight of hydrocarbon compounds of the third effluent.

[0145] Advantageously, said third effluent comprises at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of paraffins, the percentages being advantageously given in weight relative to the total weight of hydrocarbon compounds in the third effluent.

[0146] In a preferred embodiment of the invention, the hydrogenation step d) is also fed by at least a part of the C9+ fraction from a fractionation downstream of the first oligomerization step b).

[0147] Optionally, hydrogenation step d) can also be fed with at least a portion of the heavy fraction possibly from fractionation step a) and comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of benzene and compounds heavier than benzene.

[0148] Advantageously, step d) of hydrogenation is carried out by contacting, advantageously, the olefinic stream(s) and possibly the aromatic stream, supplying step d) with a hydrogen-rich gas, in the presence of a hydrogenation catalyst.

[0149] The hydrogenation catalyst used in step d) can be any hydrogenation catalyst known to those skilled in the art. Preferably, it comprises at least one metal from Group VIII, preferably chosen from palladium and nickel alone or in a mixture, and a support preferably chosen from alumina, silica, or silica-alumina. Preferably, the hydrogenation catalyst used in hydrogenation step d) 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 hydrogenation catalyst.

[0150] The hydrogenation step d) is advantageously carried out at a temperature between 100 and 250°C at the reactor inlet, at a pressure between 2 and 5 MPa and at an hourly weight rate between 0.05 and 8 h1.

[0151] The performance of the hydrogenation in step d) is advantageously controlled by a measurement of the bromine number which is advantageously at most 5 g Br / 100g according to ASTM DI 159, in the case where all the unsaturated compounds present in the cut to be hydrogenated are saturated.

[0152] Preferably, the third effluent comprising at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight of paraffins, obtained at the end of step d) of hydrogenation can be sent to a step e) of fractionation.

[0153] Advantageously, the method according to the invention comprises:

[0154] a) a step of splitting said charge to obtain at least:

[0155] - a first fraction comprising ethylene and propylene in a ratio weight ratio between propylene and ethylene present in said first fraction greater than or equal to 0.3, the ethylene present in said first fraction representing at least 85% by weight of the ethylene present in the charge;

[0156] - a second fraction having an olefinic compound content of at least 3 carbon atoms comprising at least 90% by weight of the second fraction,

[0157] - a heavy fraction comprising a content of at least 90% by weight of benzene and of compounds heavier than this one,

[0158] - a dimethyl ether enriched cut;

[0159] b) a first oligomerization step of at least a part of the first fraction from step a) to obtain at least a first effluent comprising at least 60% by weight of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in said first effluent, said first oligomerization step being carried out in the presence of an oligomerization catalyst,

[0160] c) a second oligomerization step of at least a portion of the first effluent from step b) and at least a portion of the second fraction from step a), said step c) implementing a first heterogeneous oligomerization step c1) and a second heterogeneous oligomerization step c2), to obtain a second effluent comprising at least 85% by weight of olefins having between 8 and 16 carbon atoms, relative to the total weight of olefins contained in said second effluent, said second oligomerization step being carried out in the presence of a heterogeneous catalyst comprising an amorphous or zeolitic support, the second effluent from step c) undergoing a fractionation step to obtain at least:

[0161] - a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably at least 98% by weight of compounds having between 3 and 8 carbon atoms, a first part of said fraction being recycled to the inlet of the second oligomerization step c) and the second part of said fraction being sent to another heterogeneous oligomerization step c2) and obtaining an effluent from the second heterogeneous oligomerization step c2),

[0162] - a fraction comprising a content of at least 90% by weight, preferably in less than 95% by weight, preferably at least 98% by weight of compounds having 9 or more carbon atoms;

[0163] d) a hydrogenation step of at least part of the effluent from the second step c2) of heterogeneous oligomerization and of at least part of the heavy fraction from step a), to obtain a third effluent comprising at least 90% by weight of paraffins relative to the total weight of hydrocarbon compounds of the third effluent.

[0164] Preferably, among the C3-C8 compounds of the first fraction obtained at the end of the fractionation in step c), at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds.

[0165] Preferably, among the compounds having 9 or more carbon atoms of the second fraction obtained at the end of the fractionation of step c), at least 50% by weight, preferably at least 60% by weight, preferably at least 70% by weight of these compounds are olefinic compounds. Optional splitting step e)

[0166] The process according to the present invention may include a step e) of fractionating the third effluent from step d) to obtain at least one aviation fuel type cut.

[0167] When carried out, step e) of fractionation advantageously uses at least one distillation column, so as to separate said third effluent into at least 3 cuts:

[0168] - A naphtha-type cup,

[0169] - An aviation fuel-type cup,

[0170] - A diesel-type cut.

[0171] In a particular embodiment, step e) of splitting allows also to separate in addition a gas cut which is advantageously purged.

[0172] The term "naphtha" cut means the cut comprising hydrocarbon compounds whose boiling point is between ambient temperature and 220°C.

[0173] The term "aviation fuel cut" means the cut comprising hydrocarbon compounds with a boiling point between 130°C and 300°C. This cut may also be called the "kerosene" cut.

[0174] The term "diesel cut" means the cut comprising hydrocarbon compounds whose boiling point is between 220 and 360°C. Examples

[0175] Example 1: Method for producing (aviation) fuel according to an embodiment of the invention.

[0176] Because there is an overlap in the boiling temperatures of the compounds present in the kerosene and diesel cuts, and for the sake of simplification, a cut point between kerosene and diesel was chosen at 290°C.

[0177] In this example, "Cup 130-290" refers to all hydrocarbon compounds with a boiling point between 130°C and 290°C; this cup is of the kerosene type. "Cup 290-360" refers to all hydrocarbon compounds with a boiling point between 290°C and 360°C; this cup is of the diesel type.

[0178] The flow numbers are those shown in Figures 2 and 3.

[0179] The charge 10 considered is an olefinic cut resulting from the decomposition of methanol having the following composition (values ​​in weight percentage):

[0180] [Tables 1] % by weight Flux 10 Methane 0.53 Ethane 0.34 Ethylene 10.20 C3-C5 Paraffins 3.69 C3 Olefins 57.36 C4 olefins 20.29 C5 olefins 5.38 C6-C8 paraffins 0.00 C6 olefins 2.07 C7 and C8 olefins 0.00 130-290 cut 0.00 290-360 cut 0.00 MED 0.16 Step a) of splitting

[0181] Step a) of Example 1 is shown schematically in [Fig. 3]. It consists of a series of distillation columns:

[0182] A first column m), is fed by the charge 10 with a flow rate of 10 t / h. It is operated at 2.0 MPa and allows recovery at the top (flow 101) of the majority of compounds with 3 carbon atoms or less and at the bottom (flow 103) of the majority of compounds with 4 carbon atoms or more as well as dimethyl ether.

[0183] The top product 101 of this column, with a flow rate of 6,970 kg / h, feeds column o). Its composition is as follows:

[0184] [Tables2] % by weight Flux 101 Methane 0.8 Ethane 0.5 Ethylene 14.6 C3-C5 Paraffins 2.1 C3 Olefins 82.0

[0185] The second column o) is operated at 2.8 MPa. It fractionates the top product 101 from the first column, and allows the majority of compounds with 2 or less carbon atoms to be recovered at the top (flow 11) and the majority of compounds with 3 or more carbon atoms to be recovered at the bottom (flow 104).

[0186] The weight content of ethylene in the bottom product 104 is less than 0.01%. The propylene / ethylene ratio in the top product 11 of column o) is 0.4 by weight.

[0187] This column o) consists of 45 theoretical trays. The temperature at the top of the column is 8°C. The estimated power of a propane-fired refrigeration unit p) to ensure condensation at the top of the column is estimated at 160 kW. The energy consumed at the reboiler of column o) is 750 kW.

[0188] The head product 11 of the second column o) is directed to the homogeneous oligomerization step b).

[0189] A third column n) is operated at 1.2 MPa, and fractionates the bottom product 103 from the first column m) and allows the majority of the dimethyl ether to be recovered at the top, and the majority of the compounds with 4 or more carbon atoms at the bottom (fluxl05).

[0190] The bottom product 104 from the second column o) is mixed with the bottom product 105 from the third column n) and constitutes the stream 12 which is directed to the heterogeneous oligomerization step c).

[0191] Flows 11 and 12 have the following compositions:

[0192] [Tables3] % weight Flux 11 Flux 12 Methane 3.5 0.0 Ethane 2.2 0.0 Ethylene 67.3 0.0 C3-C5 Paraffins 0.2 4.3 C3 Olefins 26.9 62.9 C4 Olefins 0.0 24.0 C5 Olefins 0.0 6.4 C6-C8 Paraffins 0.0 0.0 C6 Olefins 0.0 2.5 C7 and C8 Olefins 0.0 0.0 C9+ Compounds 0.0 0.0 DME 0.0 0.0

[0193] Step b) of homogeneous oligomerization (first oligomerization step)

[0194] The reactor in step b) is operated at 4.5 MPa and 50°C. The catalyst is the nickel-based catalyst marketed by Axens under the name LC 1251. The cocatalyst is dichloroethylaluminum (EADC). It is used in solution in n-hexane. The molar ratio between the catalyst and the cocatalyst is fixed to obtain an Al / Ni molar ratio of 15.

[0195] The catalyst concentration is adjusted to obtain 97.5% ethylene conversion in the reactor of step b).

[0196] The effluent from the oligomerization reactor is fractionated via a succession of 2 distillation columns: - A first column operated at 2.8 MPa allows the recovery at the top of the column of the majority of compounds with 2 carbon atoms or less (flux 15), and at the bottom of the majority of compounds with 3 carbon atoms or more, - The second column operated at 0.8 MPa fractionates the bottom product of the first column and allows recovery at the top of a stream 14 which includes the majority of compounds having between 3 and 8 carbon atoms and which has a content of at least 90% by weight of olefinic compounds having between 3 and 8 carbon atoms, and at the bottom the majority of compounds with 9 carbon atoms or more (stream 16).

[0197] The leading product 14 from this second column is sent to the heterogeneous oligomerization step c). The trailing product 16 from the second column is directed to a hydrogenation step d). The streams 14 and 16 have the following compositions:

[0198] [Tables4] % weight Flux 14 Flux 16 Methane 0.0 0.0 Ethane 0.0 0.0 Ethylene 0.0 0.0 C3-C5 Paraffins 0.3 0.0 C3 Olefins 13.4 0.0 C4 Olefins 23.6 0.0 C5 Olefins 6.8 0.0 C6-C8 Paraffins 0.0 0.0 C6 Olefins 32.3 0.0 C7 and C8 Olefins 23.6 0.0 C9+ Compounds 0.0 100.0 DME 0.0 0.0

[0199] Step c) of heterogeneous oligomerization (second oligomerization step)

[0200] The effluent 12 from the fractionation step a) and the effluent 14 from the homogeneous oligomerization step b) are mixed to form a stream 20 which feeds the heterogeneous oligomerization step c). The stream 20 has the following composition:

[0201] [Tables5] % weight Flux 20 Methane 0.0 Ethane 0.0 Ethylene 0.0 C3-C5 Paraffins 3.8 C3 Olefins 56.6 C4 Olefins 24.0 C5 Olefins 6.4 C6-C8 Paraffins 0.0 C6 Olefins 6.2 C7 and C8 Olefins 3.0 C9+ Compounds 0.0 DME 0.0

[0202] Heterogeneous oligomerization is carried out in two steps cl) and c2).

[0203] Step cl)

[0204] The first step cl) of the heterogeneous oligomerization is carried out in the presence of the silica alumina catalyst marketed under the name IP811 by Axens, at a temperature of 110°C, an inlet pressure of 4.5 MPa and an hourly volumetric velocity of 0.2 h 1 (hourly volumetric velocity here meaning the volume of product feeding cl) excluding recycle, i.e. the volume of the stream 20, relative to the total volume of silica alumina catalyst present in cl)).

[0205] The reaction effluent obtained at the end of this first step cl) of heterogeneous oligomerization is separated by distillation into two cuts: - a 30 cut comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms; - a cut 31 comprising C9+ compounds and which is directed towards the hydrogenation step d).

[0206] The cut 30 comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms is divided into two parts: - 95% by weight of said cut 30 comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms is recycled to the first heterogeneous oligomerization step (cl), and - 5% by weight of the cut 30 comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms (flux 32) are directed towards a second heterogeneous oligomerization step c2).

[0207] The compositions of sections 30 and 31 are given in the table below:

[0208] [Tables] % weight Flux 30 Flux 31 Methane 0.0 0.0 Ethane 0.1 0.0 Ethylene 0.1 0.0 C3-C5 Paraffins 28.8 0.0 C3 Olefins 17.0 0.0 C4 Olefins 8.9 0.0 C5 Olefins 4.7 0.0 C6-C8 Paraffins 0.0 0.0 C6 Olefins 19.3 0.0 C7 and C8 Olefins 21.0 0.1 C9+ Compounds 0.0 99.9

[0209] Step c2)

[0210] The second step c2) of the heterogeneous oligomerization is carried out in the presence of the same silica alumina catalyst as cl), the catalyst marketed under the name IP811 by Axens, at a temperature of 150°C, an inlet pressure of 7.0 MPa and a total hourly volumetric velocity of 0.5 h 1 (hourly volumetric velocity here meaning the volume of product feeding c2) excluding recycle, i.e. the volume of the stream 32, relative to the total volume of silica alumina catalyst present in c2).

[0211] 50% by weight of the reaction effluent obtained at the end of the second step c2) The heterogeneous oligomerization effluent is recycled at the inlet. The remaining 50% by weight 33 is mixed with the cut 31 comprising C9+ compounds and obtained from the distillation of the effluent from the first step c1) of heterogeneous oligomerization, to compose a mixture 21. The mixture 21 obtained is directed to the olefin hydrogenation step d).

[0212] The compositions of sections 32 and 33 are given in the table below:

[0213] [Tables?] % weight Flux 32 Flux 33 Methane 0.0 0.0 Ethane 0.1 0.1 Ethylene 0.1 0.1 C3-C5 Paraffins 28.8 29.2 C3 Olefins 17.0 0.8 C4 olefins 8.9 1.2 C5 olefins 4.7 0.5 C6-C8 paraffins 0.0 0.1 C6 olefins 19.3 5.8 C7 and C8 olefins 21.0 14.9 C9+ compounds 0.0 47.4 Step d) of olefin hydrogenation

[0214] - The product 16 from step b) and in particular from the bottom of the second The distillation column from step b) is mixed with mixture 21 from c) to form a stream 22 which feeds the olefin hydrogenation step d). The composition of stream 22 is as follows:

[0215] [Tables8] % weight Flux 22 Methane 0.0 Ethane 0.0 Ethylene 0.0 C3-C5 Paraffins 4.0 C3 Olefins 0.1 C4 Olefins 0.2 C5 Olefins 0.1 C6-C8 Paraffins 0.0 C6 Olefins 0.8 C7 and C8 Olefins 2.1 C9+ Compounds 92.8 DME 0.0

[0216] Step d) of olefin hydrogenation operates with a nickel-based catalyst marketed under the name LD746 by Axens, at a temperature of 160°C and an inlet pressure of 2.5 MPa. The hourly volumetric rate in the reaction section is 3 h₁ (hourly volumetric rate here meaning the volume of product feeding step d), i.e., the volume of stream 22, relative to the total volume of nickel-based catalyst present in d)), and the H₂ / HC (hydrocarbons) ratio is equal to 100.

[0217]

[0218]

[0219]

[0220]

[0221] Step d) of olefin hydrogenation allows at least 90% by weight of olefins to be hydrogenated to produce paraffins while minimizing the production of light hydrocarbon molecules. The olefin content of the effluent 24 at the hydrogenation outlet is less than 1% by weight relative to the total weight of hydrocarbon compounds in the effluent 24. Step e) of splitting The effluent 24 from step d) of hydrogenation is sent to step e) of fractionation which is carried out in a succession of 3 fractionation columns: - A first column is run at 0.7 MPa to obtain a head product 25 consisting of at least 85% by weight of compounds with 5 carbon atoms or less (in particular about 90% by weight of C3-C5 paraffins), and a background product, - A second column is fed with the bottom product from the first column and is operated at 0.15 MPa to obtain a top product 26 consisting of at least 80% by weight of compounds between 5 and 8 carbon atoms (in particular about 84% by weight of C6-C8 paraffins), and a bottom product, - A third column is fed with the bottom product from the second column and is operated at 0.05 MPa to obtain at the top a product 27 which is a 130-290 cut (in particular includes about 99% by weight of a 130-290 cut), and at the bottom a product 28 which corresponds predominantly to a 290-360 cut (in particular includes about 90% by weight of a 290-360 cut). The composition of flow 24 which feeds step e) and that of flows 25, 26, 27 and 28 obtained are presented in the following table: [Tables 9] % weight Flux 24 Flux 25 Flux 26 Flux 27 Flux 28 Methane 0.1 3.5 0.0 0.0 0.0 Ethane 0.0 0.2 0.0 0.0 0.0 Ethylene 0.0 0.0 0.0 0.0 0.0 C3-C5 Paraffins 3.2 89.6 1.0 0.0 0.0 C3 Olefins 0.0 0.0 0.0 0.0 0.0 C4 Olefins 0.0 0.0 0.0 0.0 0.0 C5 Olefins 0.0 0.0 0.0 0.0 0.0 C6-C8 Paraffins 2.8 5.7 83.5 0.4 0.0 C6 Olefins 0.0 0.1 0.2 0.0 0.0 C7 and C8 olefins 0.0 0.0 0.6 0.0 0.0 Cut 130-290 91.6 0.0 14.6 99.3 9.7 Cut 290-360 2.2 0.0 0.0 0.2 90.3 MED 0.0 0.0 0.0 0.0 0.0

[0222] The flow rate of stream 27 is 9016 kg / h, and the flow rate of stream 28 is 215 kg / h. The production of the 130-290 cut (kerosene type) for 1 t / h of olefin feedstock 10 is therefore 902 kg / h. The combined production of the 130-290 cut and the 290-360 cut (kerosene + diesel type) is thus 923 kg / h.

[0223] The invention makes it possible to maximize the production of kerosene-type cuts compared to a process where ethylene is not or only minimally converted in a first oligomerization step to form C4-C8 olefins. Indeed, such kerosene-type cut production would not be achievable without the conversion of ethylene, which alone represents more than 10% by weight of the olefinic feedstock.

[0224] Furthermore, the column head temperature of 8°C is not a very low temperature for a column that allows the recovery of a majority of light compounds at the top, and in particular ethylene. This minimizes the energy consumption of the refrigeration unit. Indeed, the energy consumption of a refrigeration unit increases as the required temperatures decrease.

[0225] Example 2: Energy consumption of an aviation fuel production process as a function of the weight ratio between propylene and ethylene of the first fraction obtained after step a) of fractionation.

[0226] In Example 2, the fuel production process implemented follows the same scheme as that described in Example 1 and the operating conditions of steps a) to e) are the same as those of Example 1, except for the relative quantities of ethylene and propylene of stream 11 (stream 11 being obtained at the top of column o) and sent to the first oligomerization step b)) with a propylene / ethylene ratio that varies between 0 and 0.6.

[0227] The electrical consumption of the refrigeration unit allowing the regulation of the top temperature of column o) as well as the production yield of the 130°C-290°C kerosene type cut are monitored as a function of the propylene / ethylene ratio at the inlet of step b) (i.e. of flow 11).

[0228] The curves in [Fig.4] show the evolution of the electrical consumption of the refrigeration unit and the efficiency of the process as a function of the propylene / ethylene ratio in the overhead product of column o).

[0229] Fig. 4 shows that when the propylene / ethylene ratio increases up to 0.6, the consumption of the refrigeration unit decreases, and this without a significant decrease in the production yield of the 130°C-290°C kerosene-type cut.

Claims

Demands

1. A process for producing fuel from a feed comprising at least 50% by weight of olefins relative to the total weight of the feed and comprising less than 80% by weight of ethylene relative to the total weight of olefins contained in the feed, said process comprising the following steps: a) a step of fractionating said feed to obtain at least: - a first fraction comprising ethylene and propylene in a weight ratio of propylene to ethylene present in said first fraction greater than or equal to 0.15, the ethylene present in said first fraction representing at least 85% by weight of the ethylene present in the feed; - a second fraction, having an olefinic compound content having at least 3 carbon atoms of at least 90% by weight of the second fraction;b) a first oligomerization step of at least a part of the first fraction from step a) to obtain at least a first effluent comprising at least 60% by weight of olefins having a number of carbon atoms greater than or equal to 3, relative to the total weight of olefins contained in said first effluent, said first oligomerization step being carried out in the presence of an oligomerization catalyst; (c) a second oligomerization step of at least a part of the first effluent from step (b) and of at least a part of the second fraction from step (a), to obtain a second effluent comprising at least 85% by weight of olefins having between 8 and 16 carbon atoms, relative to the total weight of olefins contained in said second effluent, said second oligomerization step (c) employing an oligomerization phase carried out in the presence of a heterogeneous catalyst.

2. A process according to claim 1, wherein the weight ratio of propylene to ethylene present in said first fraction from step a) is greater than or equal to 0.3 and preferably less than or equal to 0.

8.

3. A process according to claim 1 or claim 2, wherein the ethylene present in said first fraction from step a) represents at least 90% by weight of the ethylene present in the feed entering at step a).

4. A process according to any one of the preceding claims, further comprising a step d) of hydrogenating at least a portion of the second effluent from step c) to obtain a third effluent comprising at least 90% by weight of paraffins relative to the total weight of hydrocarbon compounds in the third effluent.

5. A process according to claim 4, further comprising a step e) of fractionating the third effluent from step d) to obtain at least one aviation fuel type cut.

6. A method according to any one of the preceding claims, wherein the feed comprises at least 50% by weight of olefins having between 2 and 8 carbon atoms relative to the total weight of the feed.

7. A process according to any one of the preceding claims, wherein a heavy fraction comprising a content of at least 90% by weight of benzene and compounds heavier than benzene is further obtained at the end of step a).

8. A process according to any one of the preceding claims, wherein a dimethyl ether enriched cut is further obtained at the end of step a).

9. A process according to any one of the preceding claims, wherein the oligomerization catalyst used in the first oligomerization step b) is a homogeneous catalyst, preferably said homogeneous catalyst comprising: - at least one nickel precursor of oxidation state (+11), - and at least one activating agent selected from the group formed by chlorinated and brominated hydrocarbylaluminium compounds, taken alone or in mixture.

10. A process according to any one of the preceding claims, wherein the first effluent from the first oligomerization step b) comprises less than 20% by weight of ethylene relative to the total weight of olefins contained in said first effluent.

11. A process according to any one of claims 4 to 10, wherein the first effluent from the first oligomerization step (b) undergoes a fractionation step to obtain at least one fraction comprising a content of at least 90% by weight of compounds having between 3 and 8 carbon atoms, which is sent to the second oligomerization step c), and a fraction comprising a content of at least 90% by weight of compounds having 9 or more carbon atoms which is sent to the hydrogenation step d).

12. A process according to any one of the preceding claims, wherein the second oligomerization step c) operates in the presence of a heterogeneous catalyst comprising an amorphous support or a zeolitic support preferably comprising at least one zeolite having at least pore openings containing 10 or 12 oxygen atoms.

13. A process according to any one of the preceding claims, wherein step c) comprises a fractionation phase of the oligomerization effluent from the oligomerization phase, to obtain at least: - a fraction comprising a content of at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, of compounds having between 3 and 8 carbon atoms, - a fraction comprising a content of at least 90% by weight of compounds having 9 or more carbon atoms, and constituting said second effluent of step c).

14. A process according to claim 13, wherein at least a part of the fraction comprising a content of at least 90% by weight of compounds having between 3 and 8 carbon atoms, from the fractionation phase of c), is recycled to the oligomerization phase of the second oligomerization step c).

15. A process according to claim 13, wherein the second oligomerization step c) implements an oligomerization phase comprising a first heterogeneous oligomerization step c1) and a second heterogeneous oligomerization step c2, and wherein at least a part of the fraction comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms from the fractionation phase of c) is recycled into the first heterogeneous oligomerization step c1 and at least another part of the fraction comprising at least 90% by weight of compounds having between 3 and 8 carbon atoms is sent to the second heterogeneous oligomerization step c2, to obtain an oligomerization effluent from the second heterogeneous oligomerization step c2.

Images