Ethylene oligomerization process comprising in situ preparation of a catalytic composition

Abstract

The present invention relates to a process for the oligomerization of ethylene, preferably the selective trimerization of ethylene to hex-1-ene, comprising simultaneously contacting ethylene with components of a chromium-based catalytic composition.

Description

[0001] Technical Field of the Invention

[0002] The present invention relates to a process for the oligomerization of ethylene, preferably the selective trimerization of ethylene to hex-1-ene, comprising simultaneously contacting ethylene with components of a chromium-based catalytic composition. Prior art

[0003] The trimerization of ethylene to hex-1-ene by homogeneous catalysts based on chromium has been studied since the 1980s. Among the catalytic systems known to bring about the selective preparation of hex-1-ene, mention may be made, for example, of the systems described in patents US5198563, US5288823, US5382738, EP608447, EP611743, EP614865. These catalysts are prepared from chromium salts and metal amides, in particular pyrrolides, which are activated in situ by aluminum alkyls or mixtures of aluminum alkyls and aluminum chloroalkyls.

[0004] During the operation of these chromium-based catalytic systems it is often observed that the activity and productivity of the catalytic system may decrease. In addition, harsh reaction conditions, such as high temperatures, may increase the productivity of the catalyst, but this usually leads to a shortened service life of the catalytic system and sometimes even to a loss of the initial selectivity of the catalyst. It is then conceivable to use additives to counteract this phenomenon and ensure good stability of the catalyst and maintenance of its performance, especially at high temperatures.

[0005] Document US2001 / 0053742 describes the effect of the order of addition of the different components of a catalytic composition comprising chromium, a pyrrole derivative and an alkylaluminum on the formation of polyethylene during the trimerization of ethylene. This document states that during the preparation of the catalytic composition, the contacting of the various ingredients must be carried out in an inert atmosphere and at a temperature of 10° C. to 40° C. in order to minimize the formation of particles and to improve the performance of the catalytic composition thus prepared.

[0006] Surprisingly, the Applicant has discovered a new process for the oligomerization of ethylene which eliminates the drawbacks previously associated with the preparation of such catalytic compositions and which allows excellent performances to be obtained in terms of selectivity and activity. In particular, said process comprises contacting the different components of the catalytic composition in situ, i.e. in a reactor at a temperature between 100° C. and 190° C. in the presence of ethylene.

[0007] Subject matter of the invention

[0008] The present invention relates to a process for the oligomerization of ethylene, comprising contacting ethylene with the following components simultaneously at a temperature between 90°C and 190°C:

[0009] - Chromium metal precursor

[0010] -Pyrrole derivatives

[0011] -General formula AlR 2 R 3 R 4 Aluminum-based compounds, where R 2 , R 3 and R 4 groups, which are the same or different, independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy and C5-C 30 aryloxy,

[0012] - at least one corresponding to the general formula Al n R 5 o Y p A halogenated aluminum compound, wherein R 5 It is C1-C 20 alkyl, Y is halogen, n is an integer from 1 to 2, o is an integer from 1 to 3 and p is an integer from 1 to 3;

[0013] - aromatic additives;

[0014] - optionally a solvent,

[0015] The components form the catalytic composition in situ.

[0016] The process according to the invention advantageously makes it possible to form the catalytic composition in situ at elevated temperature and in the presence of ethylene.

[0017] One advantage of the process according to the invention is that the stability of the catalytic preparation at high temperatures is significantly improved, while maintaining a high activity and an advantageously high selectivity for hex-1-ene.

[0018] Preferably, the aluminum-based compound and the halogenated aluminum compound are mixed prior to contacting with ethylene.

[0019] Preferably, the aluminum-based compound and the halogenated aluminum compound are mixed prior to mixing with the pyrrole derivative (before they are contacted with ethylene).

[0020] Preferably, the aluminum-based compound and the halogenated aluminum compound, the pyrrole derivative and the aromatic additive are mixed before they are contacted with ethylene.

[0021] Preferably, the metal precursor of chromium and the aromatic additive are mixed before they are contacted with ethylene.

[0022] Preferably, not all components are mixed prior to contacting with ethylene. In this embodiment, all components are mixed when they are contacted with ethylene.

[0023] Preferably, the temperature at which the components are contacted with ethylene is between 95°C and 185°C, preferably between 100°C and 160°C.

[0024] Preferably, ethylene is mixed with hydrogen.

[0025] Preferably, the pyrrole derivative corresponds to the general formula (I)

[0026]

[0027] in:

[0028] -R 1 are independently selected from halogen, C1-C 15 Alkyl, C(O)R′ group, COOR″ group, CCl3, CF3, R′ is selected from H, C1-C6 alkyl, chlorine, bromine, fluorine; R″ is selected from H, C1-C6 alkyl;

[0029] -m is an integer from 0 to 4;

[0030] -X is selected from hydrogen, lithium, sodium, potassium, cesium or aluminum atoms.

[0031] Preferably, the molar ratio between the total number of halogen atoms provided by the components of the catalytic composition and the total number of aluminum atoms provided by the aluminum-based compound and the halogenated aluminum compound (expressed as Altot), expressed as halo / Altot, is between 0.10 and 3.0, preferably between 0.15 and 2.5, preferably between 0.20 and 2.0.

[0032] Preferably, the aromatic additive is selected from aromatic ethers and / or aromatic hydrocarbons.

[0033] Preferably, the aromatic ether corresponds to the following general formula (II):

[0034]

[0035] in:

[0036] -R 6 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0037] -R 7 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0038] -R 8 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0039] -q is an integer from 0 to 4.

[0040] -r is an integer equal to 0 or 1.

[0041] Preferably, the molar ratio between the aromatic ether and the chromium-based metal precursor, expressed as aromatic ether / Cr, is between 0.5 and 2000.0, preferably between 1.0 and 800.0, preferably between 2.0 and 600.0, preferably between 3.0 and 400.0.

[0042] Preferably, the aromatic hydrocarbon corresponds to the following general formula (III)

[0043]

[0044] in:

[0045] -R 9 Independently selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl,

[0046] -s is an integer from 0 to 6.

[0047] Preferably, the molar ratio between the aromatic hydrocarbon and the chromium-based metal precursor, expressed as aromatic hydrocarbon / Cr, is between 5.0-6000.0, preferably between 10.0 and 5500.0, preferably between 15.0 and 5000.0.

[0048] Definitions and Abbreviations

[0049] It is explicitly pointed out that throughout this description, the expressions “between ... and ...” and “between ... to ...” have to be understood as including the mentioned end values.

[0050] The expression "Cx-Cy" for a hydrocarbon group means that the group contains x to y carbon atoms.

[0051] Cx-Cy alkyl is understood to mean a hydrocarbon chain containing x to y carbon atoms, Cx-Cy alkyl, for example a hydrocarbon chain of 1 to 20 carbon atoms, represented by C1-C 20Alkyl, which is linear or branched, acyclic, cyclic or polycyclic, substituted or unsubstituted. For example, C1-C8 alkyl is understood to mean an alkyl selected from methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl and octyl.

[0052] Alkoxy is understood to mean a monovalent group consisting of an alkyl group bonded to an oxygen atom, for example a CH3O-, C2H5O-, C3H7O- group.

[0053] Aryloxy is understood to mean a monovalent group consisting of an aryl group bonded to an oxygen atom, for example a C6H5O- group.

[0054] Alkenyl is understood to mean a hydrocarbon-based radical containing at least one double bond, which is linear or branched and contains 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, for example ethenyl, vinyl, butenyl or 2-propen-1-yl (allyl).

[0055] Aralkyl is understood to mean a group comprising an alkyl group whose hydrogen atoms are replaced by aryl groups, alkyl and aryl being as defined above.

[0056] Aryl is understood to mean a substituted or unsubstituted, fused or non-fused, monocyclic or polycyclic aromatic group containing 5 to 30 carbon atoms, represented by C5-C 30 Aryl.

[0057] Cr(III) is understood to mean compounds based on chromium having an oxidation state of +III. Similarly, Cr(II) and Cr(I) are understood to mean compounds based on chromium having an oxidation state of +II and +I, respectively.

[0058] The molar ratios mentioned in the present invention, in particular relative to the chromium precursor, are understood to be expressed relative to the number of moles of chromium contained in the catalytic composition. DETAILED DESCRIPTION OF THE INVENTION

[0060] For the purposes of the present invention, the different embodiments presented can be used alone or in combination with one another, without any restrictions on the combinations.

[0061] For the purposes of the present invention, various parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, for the purposes of the present invention, a preferred pressure value range can be combined with a more preferred temperature value range.

[0062] The present invention relates to a process for the oligomerization of ethylene, comprising contacting ethylene with the following components simultaneously at a temperature between 90°C and 190°C:

[0063] - Chromium metal precursor

[0064] -Pyrrole derivatives

[0065] -General formula AlR 2 R 3 R 4 Aluminum-based compounds, where R 2 , R 3 and R 4 groups, which are the same or different, independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy and C5-C 30 aryloxy,

[0066] - at least one corresponding to the general formula Al n R 5 o Y p A halogenated aluminum compound, wherein R 5 It is C1-C 20 alkyl, Y is halogen, n is an integer from 1 to 2, o is an integer from 1 to 3 and p is an integer from 1 to 3;

[0067] - aromatic additives;

[0068] - optionally a solvent,

[0069] The components form the catalytic composition in situ.

[0070] One advantage of the process according to the invention is that it simplifies the implementation of the oligomerization process by using it "in situ", in which the different components of the composition are brought into contact at the oligomerization temperature and in the presence of ethylene, without requiring any particular precautions.

[0071] The process according to the invention thus allows simplifying the process mercaptans and thus limiting the costs associated with implementing the oligomerization process, while maintaining high activity and high selectivity.

[0072] Another advantage of the process according to the invention is that it limits the formation of polymers corresponding to compounds having a carbon number greater than or equal to 12 (C12+), such as polyethylene.

[0073] Another advantage of the process according to the invention is that it allows to dispense with the constraints related to the preparation and possible storage of the catalytic composition.

[0074] Advantageously according to the following embodiments, the components of the catalytic composition are preferably contacted with ethylene, alone or in combination.

[0075] In a preferred embodiment, the aluminium-based compound and the halogenated aluminium compound are mixed before they are contacted with ethylene, preferably when they are introduced into the reactor in which the oligomerisation process according to the invention is carried out.

[0076] In a preferred embodiment, the pyrrole derivative and the aluminum-based compound and / or the halogenated aluminum compound are mixed before contacting with ethylene, preferably when they are introduced into the reactor.

[0077] In a preferred embodiment, the aluminum-based compound and the halogenated aluminum compound are mixed before mixing with the pyrrole derivative, preferably in the presence of a solvent, and before they are contacted with ethylene, preferably when they are introduced into the reactor.

[0078] In a preferred embodiment, the aluminum-based compound and the halogenated aluminum compound, the pyrrole derivative and the aromatic additive are mixed, preferably in the presence of a solvent, before they are contacted with ethylene, preferably when they are introduced into the reactor.

[0079] In a preferred embodiment, the metal precursor of chromium and the aromatic additive are mixed before they are contacted with ethylene, preferably when they are introduced into the reactor.

[0080] Preferably, the aluminum-based compound and the halogenated aluminum compound are introduced separately from the chromium metal precursor so that they are contacted with ethylene simultaneously. In other words, the aluminum-based compound and / or the halogenated aluminum compound are not mixed with the chromium metal precursor before contacting with ethylene.

[0081] Advantageously, not all components of the catalytic composition are mixed before contacting with ethylene, that is to say all components are mixed when they are contacted with ethylene.

[0082] Preferably, the process is carried out at a pressure of 0.5 to 15 MPa, preferably 1.0 to 10.0 MPa, preferably 1.5 to 8.0 MPa and very preferably 2.0 to 7.0 MPa.

[0083] Preferably, the temperature at which the components of the catalytic composition are contacted with ethylene is between 95°C and 185°C, preferably between 100°C and 160°C, preferably between 105°C and 155°C, preferably between 110°C and 150°C, preferably between 125°C and 145°C.

[0084] Advantageously, the oligomerization process is carried out at a temperature between 95°C and 185°C, preferably 100°C to 160°C, preferably 105°C to 155°C, preferably 110°C to 150°C, preferably 125°C to 145°C.

[0085] In a preferred embodiment, the temperature at which the catalytic composition is contacted in the reactor is the same as the temperature of the oligomerization process.

[0086] Advantageously, the concentration of Cr used in the oligomerization process (relative to the total volume of liquid used in the oligomerization reactor) is between 10 -12and 1 mol / L, and preferably between 10 -9 and between 0.4mol / L.

[0087] Advantageously, the ethylene used in the oligomerization process is a mixture with hydrogen. Preferably, hydrogen is introduced in a proportion of 0.1 to 5.0 wt%, preferably 0.2 to 4.0 wt%, preferably 0.4 to 3.0 wt%, very preferably 0.5 to 2.0 wt% relative to the ethylene introduced. Advantageously, the use of hydrogen mixed with ethylene can increase productivity and limit the molecular weight of the (C12+) polymer.

[0088] Advantageously, the oligomerization process is an ethylene trimerization process, preferably for the preparation of hex-1-ene.

[0089] Advantageously, the oligomerization reaction is carried out continuously.

[0090] The heat generated by the reaction may be removed by any means known to those skilled in the art.

[0091] The catalytic composition may be neutralized downstream of the reactor by any means known to those skilled in the art.

[0092] Preferably, the catalytic composition whose components are contacted with ethylene in the oligomerization process comprises and preferably consists of:

[0093] - chromium-based metal precursors,

[0094] - Pyrrole derivatives corresponding to general formula (I)

[0095]

[0096] in:

[0097] *R 1 are independently selected from halogen, C1-C 15 Alkyl, C(O)R′ group, COOR″ group, CCl3, CF3, R′ is selected from H, C1-C6 alkyl, chlorine, bromine, fluorine; R″ is selected from H, C1-C6 alkyl;

[0098] *m is an integer from 0 to 4;

[0099] *X is selected from hydrogen, lithium, sodium, potassium, cesium or aluminum atoms,

[0100] -General formula AlR 2 R 3 R 4 Aluminum-based compounds, where R 2 , R 3 and R 4 groups, which are the same or different, independently selected from hydrogen, C1-C 20 Alkyl, C1-C20 Alkoxy and C5-C 30 aryloxy,

[0101] - corresponds to the general formula Al n R 5 o Y p A halogenated aluminum compound, wherein R 5 It is C1-C 20 alkyl, Y is halogen, n is an integer from 1 to 2, o is an integer from 1 to 3 and p is an integer from 1 to 3;

[0102] - aromatic additives;

[0103] -Optional solvent.

[0104] Chromium-based metal precursors

[0105] One of the components of the catalytic composition contacted with ethylene in the process according to the invention is a chromium-based metal precursor, preferably chosen from chromium(II) salts or chromium(III) salts.

[0106] Preferably, the chromium-based metal precursor may contain one or more identical or different anions, preferably selected from halide, carboxylate, acetylacetonate, alkoxy or aryloxy anions. The chromium compound may be a chromium(II) or chromium(III) salt, but may also be a salt with a different oxidation state, which may contain one or more identical or different anions, such as halide, carboxylate, acetylacetonate, alkoxy or aryloxy anions.

[0107] Preferably, the halogen anion is selected from chloride, bromide, fluoride or iodide.

[0108] Preferably, the carboxylate anion is selected from 20 , preferably C3-C 15 , preferably C4-C 12 , preferably C5-C 10 The carboxylates are linear or branched alkyl chains, preferably the alkyl chains are unsubstituted or substituted by one or more fluorine, chlorine or bromine atoms.

[0109] Preferably, the alkoxy anion is selected from 20 , preferably C2-C 15 , preferably C3-C 12 , preferably C4-C 10 Alkoxy groups are linear, branched, cyclic or acyclic alkyl chains, preferably unsubstituted or substituted by one or more fluorine, chlorine or bromine atoms.

[0110] Preferably, the aryloxy anion is selected from 30 , preferably C5-C20 , preferably C6-C 15 , preferably C6-C 12 The aryloxy group of an aryl group is preferably unsubstituted or substituted by one or more fluorine, chlorine or bromine atoms.

[0111] Preferably, the chromium-based metal precursor may be a chromium (III) compound, but chromium (I) or chromium (II) compounds may also be suitable. As non-limiting examples, mention may be made of chromium (III) acetylacetonate, chromium (III) trifluoroacetylacetonate, chromium (III) hexafluoroacetylacetonate, chromium (III) acetate, chromium (III) 2-ethylhexanoate, chromium (III) heptanoate, Cr (III) naphthenate, chromium (III) chloride and chromium (III) bromide, alone or as a mixture, pure or diluted. Preferred chromium-based metal precursors are chromium (III) acetylacetonate, chromium (III) 2-ethylhexanoate and chromium (III) heptanoate.

[0112] Pyrrole derivatives

[0113] One of the components of the catalytic composition contacted with ethylene in the process according to the invention is a pyrrole derivative which preferably corresponds to the general formula (I)

[0114]

[0115] in:

[0116] -R 1 are independently selected from halogen, C1-C 15 Alkyl, C(O)R′ group, COOR″ group, CCl3, CF3, R′ is selected from H, C1-C6 alkyl, chlorine, bromine, fluorine; R″ is selected from H, C1-C6 alkyl;

[0117] -m is an integer from 0 to 4;

[0118] -X is selected from hydrogen, lithium, sodium, potassium, cesium or aluminum atoms.

[0119] Advantageously, R 1 independently selected from fluorine, chlorine, C1-C 10 alkyl, C(O)R′ group, COOR″ group, CCl3, CF3, R′ is selected from H, methyl, ethyl, propyl, butyl, pentyl, cyclohexyl, chlorine, fluorine. Preferably, R 1 Independently selected from fluorine, chlorine, C1-C6 alkyl, C(O)R′ group, COOR″ group, CCl3, CF3, R′ is selected from H, methyl, ethyl, propyl, butyl, and R″ is selected from H, methyl, ethyl, propyl, butyl.

[0120] Preferably, m is an integer equal to 0, 1, 2, 3 or 4, preferably m is equal to 0 or 2.

[0121] Preferably, the pyrrole derivative is selected from tetrahydroindole, 2,5-dimethylpyrrole, 3,4-dimethylpyrrole, 3,4-dichloropyrrole, 2,3,4,5-tetrachloropyrrole, 2,4-dimethyl-3-ethylpyrrole, pyrrole-2-carboxylic acid, 2-acetylpyrrole, pyrrole-2-carboxaldehyde, 3-acetyl-2,4-dimethylpyrrole, 2,4-dimethyl-5-(ethoxycarbonyl)-3-pyrrole propionic acid ethyl ester, 3,5-dimethyl-2-pyrrole carboxylic acid ethyl ester, alone or as a mixture. Preferably, the pyrrole derivative is selected from pyrrole (C4H5N) and 2,5-dimethylpyrrole.

[0122] Preferably, the molar ratio of the compound derived from pyrrole to the chromium-based metal precursor, expressed as DMP / Cr, is between 0.5 and 40.0, preferably between 1.0 and 10.0, preferably between 1.5 and 8.0, preferably between 2.0 and 5.0 and very preferably between 2.5 and 4.5.

[0123] Aluminum-based compounds

[0124] One of the components of the catalytic composition which is contacted with ethylene in the process according to the invention is a compound of the general formula AlR 2 R 3 R 4 Aluminum-based compounds, where R 2 , R 3 and R 4 groups, which are the same or different, are independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy and C5-C 30 Aryloxy.

[0125] When R 2 , R 3 and R 4 When at least one of the radicals is selected from alkyl and alkoxy radicals, the alkyl and alkoxy radicals preferably contain 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, very preferably 1 to 4 carbon atoms.

[0126] When R 2 , R 3 and R 4 When at least one of the radicals is selected from aryloxy, the aryloxy preferably contains 5 to 20 carbon atoms, preferably 5 to 15 carbon atoms, preferably 5 to 10 carbon atoms.

[0127] Preferably, R 2 , R 3 and R 4 One of the groups is hydrogen.

[0128] Preferably, R2 , R 3 and R 4 The groups are the same.

[0129] Preferably, R 2 , R 3 and R 4 At least one of the groups is independently selected from alkyl and alkoxy. Preferably, the alkyl and alkoxy are selected from methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, and the corresponding alkoxy.

[0130] Preferably, R 2 , R 3 and R 4 At least one of the groups is independently selected from aryloxy. Very preferably, the aryloxy is phenoxy (C6H5O-).

[0131] Advantageously, the one or more general formula AlR 2 R 3 R 4 The aluminum-based compound is selected from trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, trihexylaluminum, trioctylaluminum, diethylethoxyaluminum and dimethylethoxyaluminum. Preferably, the aluminum-based compound is triethylaluminum or triisobutylaluminum.

[0132] Preferably, the general formula AlR 2 R 3 R 4 The molar ratio Al / Cr of the aluminum-based compound to the chromium-based metal precursor is 1.0-100.0, preferably 2.0-90.0, preferably 3.0-80.0, preferably 4.0-60.0, preferably 5.0-50.0, preferably 6.0-40.0, preferably 7.0-30.0, very preferably 8.0-20.0, and still more preferably 9.0-15.0.

[0133] Halogenated aluminum compounds

[0134] One of the components of the catalytic composition which is contacted with ethylene in the process according to the invention is a compound corresponding to the general formula Al n R 5 o Y p A halogenated aluminum compound, wherein

[0135] -R 5 It is C1-C 20 alkyl,

[0136] -Y is a halogen,

[0137] -n is an integer from 1 to 2,

[0138] -o is an integer from 1 to 3, and

[0139] -p is an integer from 1 to 3.

[0140] Preferably, R 5 It is C1-C 15 , preferably C1-C 10 , preferably C1-C6 alkyl. Preferably, R 5 Selected from methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl.

[0141] Preferably, Y is selected from fluorine, chlorine or bromine. Preferably, Y is chlorine or bromine.

[0142] Advantageously, the halogenated aluminum compound is selected from methylaluminum dichloride (MeAlCl2), ethylaluminum dichloride (EtAlCl2), ethylaluminum sesquichloride (Et3Al2Cl3), diethylaluminum chloride (Et2AlCl), diisobutylaluminum chloride (iBu2AlCl) and isobutylaluminum dichloride (iBuAlCl2), used alone or in combination. Very preferably, the halogenated aluminum compound is ethylaluminum dichloride (EtAlCl2) and diethylaluminum chloride (Et2AlCl).

[0143] Preferably, the general formula Al n R 5 o Y p The molar ratio of the halogenated aluminum compound to the chromium-based metal precursor, expressed as AlY / Cr, is 1.0-100.0, preferably 1.5-80.0, preferably 2.0-60.0, preferably 2.5-50.0, preferably 3.0-40.0, preferably 3.5-30.0, preferably 4.0-20.0, very preferably 4.5-15.0, and still more preferably 5.0-12.0.

[0144] In a preferred embodiment, the molar ratio between the total number of halogen atoms, preferably chlorine or bromine, provided by the components of the catalytic composition, and the total number of aluminum atoms provided by the aluminum-based compound (Al) and the halogenated aluminum compound (AlY), expressed as Altotal or Altot, in particular as Cl / Altot when the halogen is chlorine and as Br / Altot when the halogen is bromine, is from 0.10 to 3.0, preferably from 0.15 to 2.5, preferably from 0.20 to 2.0, preferably from 0.25 to 1.5, and very preferably from 0.30 to 1.0.

[0145] Advantageously, when the catalytic composition has a Halo / Al molar ratio within the range defined above, said composition has better activity and 1-hexene selectivity for the trimerization of ethylene.

[0146] Aromatic Additives

[0147] One of the components of the catalytic composition contacted with ethylene in the process according to the invention is at least one aromatic additive. Advantageously, the aromatic additive is an aromatic ether and / or an aromatic hydrocarbon. Preferably, the aromatic additive is selected from compounds corresponding to the following general formula (II) and / or (III).

[0148] The aromatic additive may be an aromatic ether corresponding to the following general formula (II):

[0149]

[0150] in:

[0151] -R 6 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0152] -R 7 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0153] -R 8 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl or aralkyl;

[0154] -q is an integer from 0 to 4,

[0155] -r is an integer equal to 0 or 1.

[0156] Preferably, R 6 Selected from C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C5-C 15 Preferably, R 6 Selected from C1-C6 alkyl, C3-C6 cycloalkyl, C2-C8 alkenyl, C5-C 12 Preferably, R 6is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, pentyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl. Very preferably, R 6 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl.

[0157] Preferably, R 7 Selected from C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C5-C 15 Preferably, R 7 Selected from C1-C6 alkyl, C3-C6 cycloalkyl, C2-C8 alkenyl, C5-C 12 Preferably, R 7 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, pentyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl. Very preferably, R 7 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl.

[0158] Preferably, R 8 Selected from C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C2-C 10 Alkenyl, C5-C 15 Preferably, R 8 Selected from C1-C6 alkyl, C3-C6 cycloalkyl, C2-C8 alkenyl, C5-C 12 Preferably, R 8 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, pentyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl. Very preferably, R 8 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl or 2,4,6-trimethylphenyl.

[0159] Preferably, q is equal to 0, 1 or 2.

[0160] Advantageously, r is equal to 0 or 1. Preferably, r is equal to 0.

[0161] When r is equal to 1, OR 7Group relative to OR 6 The group is in the ortho, meta or para position. Preferably, OR 7 The group is in the ortho position.

[0162] When q is equal to 1 or 2, OR 8 The groups may be the same or different relative to OR 6 The group is in the ortho, meta or para position. Preferably, R 8 The group is in the ortho position.

[0163] Preferably, the ether aromatic additive is selected from methoxybenzene (or anisole), 2-methylanisole, 3-methylanisole, 4-methylanisole, 2-chloroanisole, 3-chloroanisole, 4-chloroanisole, 3,5-dichloroanisole, 2,6-dichloroanisole, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 2,3-dimethylanisole, ethoxybenzene, diphenyl ether, 1-methoxynaphthalene, 2-methoxynaphthalene, 2,7-dimethoxynaphthalene, 1,3-dimethoxynaphthalene. Preferably, the ether aromatic additive is methoxybenzene, 1,2-dimethoxybenzene or 2,3-dimethylanisole.

[0164] Preferably, the molar ratio between the ether aromatic additive and the chromium-based metal precursor, expressed as aromatic ether / Cr, is between 0.5 and 2000.0, preferably between 1.0 and 800.0, preferably between 2.0 and 600.0, preferably between 3.0 and 400.0, preferably between 5.0 and 300.0, preferably between 7.0 and 200.0, preferably between 10.0 and 150.0, preferably between 12.0 and 100.0, preferably between 15.0 and 90.0, more preferably between 20.0 and 80.0, and still more preferably between 30.0 and 70.0.

[0165] The aromatic additive may be an aromatic hydrocarbon corresponding to the following general formula (III):

[0166]

[0167] in:

[0168] -R 9 Independently selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl,

[0169] -s is an integer between 0 and 6.

[0170] Preferably, R 9 Selected from C1-C 10 Alkyl, preferably C1-C6 alkyl, C3-C 10Preferably, R 9 Selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, pentyl, cyclohexyl.

[0171] Preferably, s is equal to 0, 1, 2, 3, 4, 5 or 6. Preferably, s is 1-4 and more preferably s is equal to 1, 2 or 3.

[0172] Preferably, the aromatic hydrocarbon additive is selected from benzene, toluene, ethylbenzene, diethylbenzene, o-xylene, m-xylene, p-xylene, styrene, cumene, alone or in mixture. Preferably, the aromatic hydrocarbon additive is selected from toluene, ethylbenzene and o-xylene.

[0173] In a particular embodiment, the catalytic composition used in the process according to the invention may comprise, as additives, at least one aromatic ether of formula (II) and at least one aromatic hydrocarbon of formula (III).

[0174] Preferably, the molar ratio between the aromatic additive and the chromium-based metal precursor, expressed as aromatic / Cr, is between 5.0 and 6000.0, preferably between 10.0 and 5500.0, preferably between 15.0 and 5000.0, preferably between 20.0 and 4500.0, preferably from 25.0 to 4000.0, preferably from 30.0 to 3500.0, preferably from 35.0 to 3000.0, preferably from 40.0 to 2500.0, preferably from 45.0 to 2000.0, preferably from 50.0 to 1700.0, preferably from 55 to 1500.0, preferably from 60.0 to 1200.0, preferably from 70.0 to 1000.0, preferably from 80.0 to 900.0, preferably from 90.0 to 800, preferably from 100 to 700, preferably from 150 to 600, very preferably from 200 to 500.

[0175] Optional solvent

[0176] One of the components of the catalytic composition contacted with ethylene in the process according to the invention may also be at least one solvent. Preferably, the solvent is chosen from organic solvents and in particular from saturated, unsaturated, cyclic or acyclic hydrocarbons.

[0177] The solvent or solvents are advantageously chosen from halogenated solvents and saturated or unsaturated, cyclic or acyclic hydrocarbons comprising from 1 to 20 carbon atoms, preferably from 1 to 15 carbon atoms, preferably from 4 to 15 carbon atoms.

[0178] Preferably, the solvent is selected from pentane, hexane, cyclohexane, methylcyclohexane, heptane, butane or isobutane, cycloocta-1,5-diene, methylene chloride, ethylene dichloride, chlorobenzene, dichlorobenzene, methanol, ethanol, pure or as a mixture. Preferably, the solvent is selected from hexane, cyclohexane and methylcyclohexane.

[0179] In the case where the solvent is an unsaturated hydrocarbon, it may advantageously be selected from the products of the oligomerization reaction.

[0180] The following examples illustrate the invention without limiting its scope. Example

[0181] The solvent content is the weight ratio of the total flow of solvent injected to the total flow of ethylene injected in the process.

[0182] The distribution of olefins obtained by this process is given as percentages of butenes (% C4), hexenes (% C6), octenes (% C8), decenes (% C10) and olefins having a carbon number equal to or greater than 12.

[0183] The % 1-C6 corresponds to the selectivity for hex-1-ene in the hexene fraction.

[0184] Examples 1 to 5: Use of the catalytic system in continuous mode

[0185] Preparation of catalytic system:

[0186] Solution 1: In a prepared test tube, add triethylaluminum (final concentration = 0.00825 mol / L), then add diethylaluminum chloride (final concentration = 0.006 mol / L) and 2,5-dimethylpyrrole ligand (final concentration = 0.00225 mol / L) under stirring. The total volume of the solution is 1.5L.

[0187] Solution 2: In a prepared test tube, chromium precursor Cr(2-EH)3 (xxg, final concentration = 0.0075 mol / L) and anisole (50eq, 0.03750 mol / L) were diluted in cyclohexane under stirring. The total volume of the solution was 1.5L.

[0188] Use of catalytic system

[0189] A solution of a ligand (2,5-dimethylpyrrole) combined with a cocatalyst (triethylaluminum and diethylaluminum chloride) (solution 1) and a solution of a chromium precursor (Cr(2-EH)3) with an aromatic compound (anisole and / or o-xylene) (solution 2) are diluted in cyclohexane (less than 10 ppm measured in water) and introduced into the reactor by a pump system under flow rate control. The two lines for introducing the solutions are independent of each other. The injection point of the two solutions into the reactor is directly located in the liquid phase.

[0190] Ethylene (optionally mixed with 0.5 wt% of hydrogen) is introduced into the reactor under pressure control. The reaction is carried out in a 250 ml gas / liquid CSTR reactor. It is equipped with a 5-point temperature measuring tube, which allows the liquid level to be adjusted at different levels, with oil bath heating (controlled at the liquidus temperature) and mechanical stirring (0-1500 rpm).

[0191] The liquid phase containing dissolved ethylene, optionally dissolved hydrogen and the products formed is discharged from the reactor via a dip tube and a drain valve, said phase being neutralized and separated.

[0192] The gas phase was quantitatively and qualitatively analyzed by gas chromatography (GC), and the liquid phase was weighed, neutralized and qualitatively analyzed by GC. The results obtained are listed in the following table, and the amounts of the reactants are expressed as equivalents (expressed as eq) relative to the amount of chromium used.

[0193]

[0194]

[0195] Examples 1 to 5 clearly show that the "in situ" process according to the invention using a catalytic composition comprising an aromatic additive makes it possible to obtain very good productivity and excellent selectivity in favour of hex-1-ene.

[0196] Examples 6 to 8: Use of the catalytic system in semi-open batch mode

[0197] Examples 6 to 8 were carried out in a stainless steel autoclave with a working volume of 250 ml, equipped with a jacket capable of regulating the temperature by oil circulation.

[0198] The reactor was predried under vacuum and placed under an ethylene atmosphere.

[0199] Solution 1: In a Schlenk flask placed under an inert atmosphere and stirred, while observing the desired ratio, a solution of triethylaluminum in cyclohexane (0.0365 mol / l) is introduced, followed by a solution of diethylaluminum chloride in cyclohexane (0.0243 mol / l) and a solution of 2,5-dimethylpyrrole in cyclohexane (0.0301 mol / l). The mixture thus obtained is stirred under argon for 15 minutes.

[0200] Solution 2: The chromium precursor Cr(2-EH)3 (20 μmol) and anisole (50 eq) were diluted in cyclohexane. The total volume of the solution was 18 ml.

[0201] Reactor is pre-dried under vacuum and placed under ethylene atmosphere. Under ethylene atmosphere, cyclohexane is introduced into reactor, then solution 1 comprising Et3Al (9-13eq / Cr), Et2AlCl (6-10eq / Cr) and 2,5-DMP (3-4eq / Cr) is added. Solution 2 is introduced into injection airlock. The total volume of liquid is 75 milliliters. Once the temperature of reactor has reached the test temperature, the solution contained in the injection airlock is injected into the reactor under ethylene pressure. Pressure is adjusted to the test pressure. Monitor ethylene consumption until 35g ethylene is introduced. Then cut off the supply of ethylene and the reactor is cooled and degassed. The gas phase adopts gas chromatography (GC) quantitative and qualitative, and the liquid phase is weighed, neutralized and qualitatively analyzed by GC.

[0202]

[0203] Operating conditions : Cr(2-EH)3 (20 μmol); 2,5-DMP (3 eq); anisole (50 eq); cyclohexane (75 ml); 135 °C, 50 bar

[0204] As can be clearly seen from Examples 6 to 8, the process according to the invention, which uses in the oligomerization process a catalytic composition having a precise ratio between the total number of chlorine atoms and the total number of aluminum atoms (Cl / Al) provided by the components of the catalytic composition, advantageously makes it possible to adjust the performance of the composition, in particular in terms of selectivity and productivity.

Claims

1. A process for the oligomerization of ethylene comprising contacting ethylene with the following components simultaneously at a temperature between 90°C and 190°C: - Chromium metal precursor - pyrrole derivatives; the pyrrole derivatives correspond to the general formula (I) in: -R 1 Independently selected from C1-C 15 Alkyl, C(O)R' group, COOR" group, CCl3, CF3, R' is selected from H, C1-C6 alkyl, chlorine, bromine, fluorine; R" is selected from H, C1-C6 alkyl; -m is an integer from 0 to 4; -X is selected from hydrogen, lithium, sodium, potassium, cesium or aluminum atoms; -General formula AlR 2 R 3 R 4 Aluminum-based compounds, where R 2 , R 3 and R 4 groups, which are the same or different, independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy and C5-C 30 aryloxy, - at least one corresponding to the general formula Al n R 5 o Y p A halogenated aluminum compound, wherein R 5 It is C1-C 20 alkyl, Y is halogen, n is an integer from 1 to 2, o is an integer from 1 to 3 and p is an integer from 1 to 3; - aromatic additives; wherein the components form a catalytic composition in situ; and wherein the molar ratio between the total number of halogen atoms provided by the components of the catalytic composition and the total number of aluminum atoms provided by the aluminum-based compound and the halogenated aluminum compound, expressed as halo / Altot, is between 0.10 and 3.0, wherein the total number of aluminum atoms is expressed as Altot.

2. The process according to claim 1, wherein the aluminum-based compound and the halogenated aluminum compound are mixed before they are contacted with ethylene.

3. The process according to any one of claims 1 to 2, wherein the aluminum-based compound and the halogenated aluminum compound are mixed before being mixed with the pyrrole derivative and then they are contacted with ethylene.

4. The process according to any one of claims 1 to 2, wherein the aluminum-based compound and the halogenated aluminum compound, the pyrrole derivative and the aromatic additive are mixed before they are contacted with ethylene.

5. The method according to any one of claims 1 to 2, wherein the metal precursor of chromium and the aromatic additive are mixed before they are contacted with ethylene.

6. The process of claim 1 wherein all components are mixed as they contact ethylene.

7. The process according to any one of claims 1-2, wherein the temperature at which the components are contacted with ethylene is between 95°C and 185°C.

8. The process according to any one of claims 1-2, wherein ethylene is mixed with hydrogen.

9. The process according to any one of claims 1 to 2, wherein the molar ratio between the total number of halogen atoms provided by the components of the catalytic composition and the total number of aluminum atoms provided by the aluminum-based compound and the halogenated aluminum compound, expressed as halo / Altot, is between 0.15 and 2.5, wherein the total number of aluminum atoms is expressed as Altot.

10. The method according to any one of claims 1-2, wherein the aromatic additive is selected from aromatic ethers and / or aromatic hydrocarbons.

11. The method according to claim 10, wherein the aromatic ether corresponds to the following general formula (II): in: -R 6 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl, or aralkyl; -R 7 Selected from hydrogen, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl, or aralkyl; -R 8 Selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C2-C 20 alkenyl, C5-C6 alkyl optionally substituted 20 Aryl, or aralkyl; -q is an integer from 0 to 4, -r is an integer equal to 0 or 1.

12. The method according to claim 10, wherein the molar ratio between the aromatic ether and the chromium-based metal precursor, expressed as aromatic ether / Cr, is between 0.5 and 2000.

0.

13. The method according to claim 10, wherein the aromatic hydrocarbon corresponds to the following general formula (III) in: -R 9 Independently selected from C1-C 20 Alkyl, C3-C 20 Cycloalkyl, -s is an integer from 0 to 6.

14. The method of claim 10, wherein the molar ratio between the aromatic hydrocarbon and the chromium-based metal precursor, expressed as aromatic hydrocarbon / Cr, is 5.0 to 6000.

0.

15. The method according to claim 10, wherein the molar ratio between the aromatic ether and the chromium-based metal precursor, expressed as aromatic ether / Cr, is between 3.0 and 400.0, and the molar ratio between the aromatic hydrocarbon and the chromium-based metal precursor, expressed as aromatic hydrocarbon / Cr, is between 15.0 and 5000.0.

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