Novel chromium or titanium based supported catalyst compositions

Abstract

The present invention relates to a catalyst composition for the selective oligomerization of ethylene, in particular for the trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively. The catalyst composition comprises the following components: at least one chromium- or titanium-based metal precursor; at least one support in the form of solid methylaluminoxane (MAO); and at least one additive in the form of an aluminum-based compound. The present invention further relates to an oligomerization process, preferably for the selective trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, using the catalyst composition according to the invention.

Description

[Technical Field]

[0001] The present invention relates to new catalyst compositions based on supported chromium or titanium and their use for the selective oligomerization of ethylene, more particularly the trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively.

[0002] The present invention also relates to a process for the oligomerization of ethylene, preferably for the trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, in which the catalyst composition according to the invention is used. [Background technology]

[0003] Linear alpha-olefins (LAOs), containing 4 to more than 20 carbon atoms, are important raw materials for the production of petrochemical intermediates. Despite their wide range of applications, global demand for LAOs is essentially dominated by short-chain α-olefins, such as 1-butene, 1-hexene, and 1-octene, which are sometimes used as comonomers for the polymer industry. The global supply of LAOs is essentially covered by two types of ethylene oligomerization processes using homogeneous catalysts: "full-range" processes and selective "on-purpose" processes. "Full-range" processes produce a broad distribution of olefins (generally C4 to C30), while "on-purpose" processes produce only a single α-olefin (1-butene, 1-hexene, or 1-octene). However, as demand for short-chain LAOs from C4 to C10 has grown more rapidly than demand for the C10+ range, considerable progress has been made in recent years in controlling the product distribution in favor of the shorter α-olefin distribution, or even in selectively producing a single α-olefin. In this field, the tetramerization of ethylene to 1-octene over chromium-based homogeneous catalysts has led to numerous developments in recent years (Non-Patent Document 1). Systems known to result in the selective production of 1-octene include, for example, those described in Patent Documents 1 to 3. These catalysts utilize a Cr(III)-based metal precursor coupled to a PNP ligand (e.g., PhPN(iPr)PPh) activated in situ by an aluminoxane (e.g., MAO: methylaluminoxane; MMAO: modified methylaluminoxane). They result in the "selective" production of 1-octene (more than 65% selectivity). Further Cr-based catalytic systems have since been developed, examples of which are given in Patent Documents 4 to 6. The trimerization of ethylene to 1-hexene over titanium-based complexes is also an area that is seeing unlimited expansion. Examples include the system ([(η 5Cp-CMe2-C6H5)TiCl3] / MAO; Non-Patent Document 2) or the more recently developed system by Mitsui ((ArOImineOMe)TiCl3 / MAO; Non-Patent Document 3).

[0004] The main drawback of chromium- or titanium-based catalyst systems for ethylene oligomerization is the substantial formation of polymers in parallel with the formation of the target olefins (1-hexene and / or 1-octene). This formation of polymers may be behind the rapid deactivation of the catalyst and increased difficulties in process operation. The first approach in this field, inherited from polymer specialists (accustomed to managing large amounts of polymer in the process), involves supporting homogeneous catalysts on inorganic supports to specifically control the morphology of the formed polymer. The transfer of this strategy to ethylene oligomerization has been particularly described by R. Duchateau, who used silica-supported MAO for the selective trimerization of ethylene to 1-hexene with titanium complexes (Non-Patent Document 4). The polymers produced in this conversion take the form of non-sticky solids with controlled morphology, significantly reducing reactor fouling.

[0005] It is an object of the present invention to provide a new catalyst composition for the oligomerization of ethylene that is not hindered by the problems that affect the use of conventional prior art catalyst compositions, particularly those containing an MAO cocatalyst in a homogeneous phase or an MAO cocatalyst supported on an inorganic support.

[0006] Applicant has surprisingly demonstrated that compositions comprising a chromium or titanium based metal precursor, solid MAO as a support, and an additive in the form of an aluminum based compound result in a catalyst composition that is active and selective in the oligomerization of ethylene (trimerization and tetramerization of ethylene to 1-hexene and 1-octene, respectively), while allowing control of the morphology of the polymer by-products, thus solving the problem of reactor fouling.

[0007] Solid MAO is a polyaluminoxane with a degree of polymerization higher than that of conventional MAO. It is generally insoluble in traditional organic solvents and can be used directly as a support for catalyst formation. This type of solid MAO is sold, in particular, by Tosoh Finechem Corporation and is described, for example, in Patent Documents 7 to 9. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2004 / 056477 [Patent Document 2] International Publication No. 2004 / 056478 [Patent Document 3] International Publication No. 2004 / 056479 [Patent Document 4] International Publication No. 2010 / 034102 [Patent Document 5] International Publication No. 2011 / 156892 [Patent Document 6] International Publication No. 2011 / 108772 [Patent Document 7] US Patent Application Publication No. 2011 / 0282017 [Patent Document 8] US Patent Application Publication No. 2015 / 057418 [Patent Document 9] US Patent Application Publication No. 2018 / 355077 [Non-patent literature]

[0009] [Non-Patent Document 1] PWNM van Leeuwen et al., Coordination Chemistry Reviews, 2011, Vol. 255, pp. 1499-1517 [Non-patent document 2] Angew Chem Int Ed, 2001, Vol. 40, p. 2516-2519 [Non-patent document 3] Organometallics, 2010, Vol. 29, pp. 2394-2396 [Non-patent document 4] R. Duchateau, ACS Catalysis, 2015, Volume 5, p.5068-5076 Summary of the Invention [Means for solving the problem]

[0010] (Summary of the Invention) The present invention relates to a catalyst composition for the selective oligomerization of ethylene, more particularly the trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, comprising: - at least one metal precursor based on chromium or titanium; - at least one support in the form of solid methylaluminoxane (MAO); - at least one additive in the form of an aluminum-based compound.

[0011] One advantage of the catalyst composition according to the invention is, in particular, that it allows the morphology of the polymeric by-products formed to be controlled, thus making it possible to easily remove them from the reactor while maintaining high levels of productivity and selectivity for 1-hexene and / or 1-octene. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Detailed Description of the Invention) According to the present invention, the expressions "of between A and B" and "between A and B" are synonymous and mean that both limits of the interval (A, B) are included in the range of values ​​stated. If this is not the case and if both limits are not included in the range stated, such information is to be incorporated by the present invention.

[0013] For purposes of the present invention, various ranges of parameters for a given process, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, for purposes of the present invention, a range of preferred pressure values ​​can be combined with a range of more preferred temperature values.

[0014] In the remainder of this text, specific embodiments of the present invention will be described, which can be implemented separately or in combination together, without any limitation on this combination, provided that the combination is technically feasible.

[0015] (metal precursor) A "metal precursor" is a compound comprising a central metal and at least one ligand; it may be charged or neutral, organic or inorganic, and has the capacity to interact with the support through ionic interactions to form a catalyst.

[0016] (Cr-based precursor) The composition according to the invention comprises at least one chromium-based metal precursor preferably chosen from salts of chromium(II) or chromium(III).

[0017] Preferably, the chromium-based metal precursor may comprise one or more identical or different anions selected from the group formed by halide, carboxylate, acetylacetonate, and alkoxy and aryloxy anions. The chromium compound may be a salt of chromium(II) or chromium(III), but may also be a salt with different oxidation states which may comprise one or more identical or different anions, for example, halide, carboxylate, acetylacetonate, or alkoxy or aryloxy anions.

[0018] Preferably, the halide anion is selected from chloride, bromide, fluoride or iodide.

[0019] Preferably, the carboxylate anion is C3-C 20 , preferably C3-C 15 , preferably C4-C 12 , preferably C5 to C 10 Preferably, the alkyl chain is unsubstituted or substituted by one or more fluorine, chlorine or bromine atoms.

[0020] Preferably, the alkoxy anion is C1-C 20 , preferably C2-C 15 , preferably C3-C 12 , preferably C4-C 10 and alkoxy having a straight, branched, cyclic or acyclic alkyl chain of the formula: wherein preferably said alkyl chain is unsubstituted or substituted with one or more fluorine, chlorine or bromine atoms.

[0021] Preferably, the aryloxy anion is C5-C 30 , preferably C5-C 20 , preferably C6-C 15 , preferably C6-C 12and aryloxy having an aryl group of the formula: wherein preferably said aryl group is unsubstituted or substituted with one or more fluorine, chlorine or bromine atoms.

[0022] In one embodiment, the chromium compound used in the present invention is a chromium(III) compound, although chromium(I) or chromium(II) compounds may also be suitable. Non-limiting examples include Cr(III) acetylacetate, Cr(III) trifluoroacetylacetate, Cr(III) hexafluoroacetylacetate, Cr(III) acetate, Cr(III) 2-ethylhexanoate, Cr(III) heptanoate, Cr(III) naphthenate, Cr(III) chloride, and Cr(III) bromide, utilized singly or in admixture, in high purity or diluted form. Preferred Cr precursor derivatives are Cr(III) acetylacetate, Cr(III) 2-ethylhexanoate, and Cr(III) heptanoate.

[0023] In one embodiment, when the composition according to the present invention comprises at least one chromium-based metal precursor, said composition may further comprise at least one heteroatom ligand.

[0024] Said heteroatom ligand advantageously conforms to the general formula (i):

[0025] [ka]

[0026] During the ceremony, R 1 , R 2 , R 3 , R 4 and R 5 are identical or different, bonded or not bonded to each other, and have 1 to 15 carbon atoms (C1 to C6) that may or may not contain one or more heteroatoms. 15cyclic or acyclic alkyl groups having 4 to 15 carbon atoms (C4-C 15 ) and a substituted or unsubstituted aryl group having the formula:

[0027] The heteroelements are preferably selected from iodine, bromine, chlorine, fluorine, nitrogen, sulfur and / or oxygen.

[0028] R 1 , R 2 , R 3 , R 4 and R 5 are preferably the same or different and are C1-C 10 Alkyl groups, C3-C 10 Cycloalkyl groups and C5-C 15 It is selected from aryl groups.

[0029] R 1 , R 2 , R 3 , R 4 and R 5 are preferably the same or different and are selected from the group consisting of a C1-C6 alkyl group, a C3-C6 cycloalkyl group and a C5-C 12 It is selected from aryl groups.

[0030] Preferably, the group R 1 , R 2 , R 3 , R 4 and R 5are the same or different, bonded or not bonded to each other, and are selected from substituted or unsubstituted methyl, ethyl, n-propyl, i-propyl (isopropyl), n-butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, and adamantyl groups; and / or phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropylphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-di-tert-butyl-4-methoxyphenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 3,5-di(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, furanyl, and thiophenyl groups.

[0031] The heteroatom ligand is preferably selected from the following: (phenyl)PN(methyl)P(phenyl)2, (phenyl)PN(i-propyl)P(phenyl)2, (phenyl)PN(phenyl)P(phenyl)2, (2-methoxyphenyl)PN(i-propyl)P(phenyl)2, (2-methoxyphenyl)PN(i-propyl)P(2-methoxyphenyl)2, (4-methoxyphenyl)PN(i-propyl)P(4-methoxyphenyl)2, (2-fluorophenyl)PN(i-propyl)P(2-fluorophenyl)2, (2-fluorophenyl)(phenyl)PN(i-propyl)P(2-fluorophenyl)2, (2-fluorophenyl)(phenyl)PN(i-propyl)P(2-fluorophenyl)(phenyl), (2-fluorophenyl)(phenyl)PN(i-propyl)P(phenyl)2.

[0032] The heteroatom ligand is highly preferably selected from (phenyl)2PN(i-propyl)P(phenyl)2 and (2-fluorophenyl)2PN(i-propyl)P(2-fluorophenyl)2.

[0033] Preferably, the molar ratio of heteroatom ligand to chromium-based metal precursor, expressed as HL / Cr, is from 0.5 to 10, preferably from 0.8 to 6, more preferably from 1.0 to 4.0, and highly preferably from 1.2 to 2.0.

[0034] (Ti-based precursor) The composition according to the invention comprises at least one titanium-based metal precursor, preferably selected from Ti(IV) coordination complexes conforming to formula (ii):

[0035] [ka]

[0036] During the ceremony, R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 are the same or different, bonded or not bonded to each other, and have 1 to 15 carbon atoms (C1-C2) with or without a hydride group, a fluoride group, a chloride group, a bromide group, one or more heteroatoms; 15 ) having cyclic or acyclic alkyl groups and / or 4 to 15 carbon atoms (C4-C 15 ) or 4 to 15 carbon atoms (C4-C 15 ) and a substituted or unsubstituted aryl group having the formula:

[0037] R 7 , R 9 , R 10 , R11 , R 12 , R 13 , R 14 , R 15 , R 16 and R 17 are preferably the same and are selected from hydride, methyl, ethyl or fluoride. 7 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 and R 17 are highly preferably the same and are selected from hydrides.

[0038] Preferably, R 18 is a C1-C6 alkyl group, a C3-C6 cycloalkyl group, or a substituted or unsubstituted C4-C alkyl group with or without one or more heteroatoms. 15 aryl. Preferably, R 18 is selected from substituted or unsubstituted methyl, ethyl, n-propyl, i-propyl, n-butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, and adamantyl groups; or, in one embodiment, phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropylphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-di-tert-butyl-4-methoxyphenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 3,5-di(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, furanyl, and thiophenyl groups. Highly preferably, R 18 is selected from methyl groups.

[0039] Preferably, R 6 and R8 are the same or different, C1-C 10 Alkyl groups, C3-C 10 Cycloalkyl groups or substituted or unsubstituted C4-C 15 aryl groups, which may or may not contain one or more heteroatoms. Preferably, R 6 and R 8 are the same or different and are C1-C6 alkyl groups, C6-C 10 It is selected from a cycloalkyl group or a substituted or unsubstituted C4-C6 aryl group, which may or may not contain one or more heteroatoms. More preferably, R 6 and R 8 are the same or different, bonded or unbonded to each other, and are selected from the group consisting of substituted or unsubstituted methyl, ethyl, n-propyl, i-propyl, n-butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, adamantyl, phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropylphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-di-tert-butyl-4-methoxyphenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 3,5-di(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, furanyl, and thiophenyl. Highly preferably, R 6 and R 8 are the same or different, bonded or not bonded to each other, and are selected from tert-butyl or adamantyl groups.

[0040] Three groups X 1are the same or different and are selected from anionic groups. Non-limiting examples include fluoride, chloride, bromide, iodide, hydroxide, methyl, n-ethyl, n-propyl, i-propyl, n-butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, methoxy, ethoxy, propoxy, formate, acetate, propionate or carbonate. More preferably, the group X 1 are identical and are selected from chloride, bromide or iodide groups. Highly preferably, the group X 1 is chloride.

[0041] Group X 2 is defined by the coordinating heteroatom. The heteroatom is selected from nitrogen, phosphorus, sulfur or oxygen. More preferably, the group X 2 is selected from oxygen.

[0042] (Carrier in the form of solid MAO) The support allows the catalyst to be formed upon use of the catalyst composition through ionic interactions between the metal precursor and the support; this type of catalyst structure is sometimes called a suspended cation. The catalytic reaction occurs at the surface or in the pores of the formed catalyst.

[0043] The catalytic composition according to the invention comprises at least one support in the form of solid methylaluminoxane (MAO).

[0044] A description of the solid MAO that can be used in the catalyst composition according to the invention and methods for producing it can be found in documents US20110282017, US2015057418 or US2018355077 in the name of Tosoh Finechem Corporation, or US6518445 in the name of Albemarle Corporation.

[0045] The terms "solid MAO" or "solid methylaluminoxane" will be used equivalently. Solid MAO is, by definition, a specific compound that is in the form of a solid suspension in a hydrocarbon (aromatic or paraffinic) solvent, such as toluene, cyclohexane, pentane, heptane, etc., at ambient temperature (below 30°C). Any solid MAO that is insoluble in a hydrocarbon solvent may act as a carrier according to the present invention.

[0046] The solid MAO advantageously comprises a polymer chain (PMAO) formed by atoms of Al, O and methyl groups (-Me or -CH) defined by the following formula (iii):

[0047] [ka]

[0048] where n may advantageously take a value of 1 to 60, preferably 10 to 50. Solid MAO essentially comprises PMAO chains according to formula (iii), but its structure may also include associated trimethylaluminum, which may be free or interact with the PMAO chain. PMAO may have a linear, cyclic or branched structure, as long as the polymer chain satisfies formula (iii).

[0049] The solid MAO used in the present invention may contain PMAOs with linear and / or branched structures, but may also contain cyclic fragments and residual molecules of the solvent that interact with the TMA.

[0050] The aluminum mass content of the solid MAO is advantageously 36% to 52% by mass, which ensures that the solid MAO has good properties during various synthesis steps, such as optimal size and fragmentation resistance.

[0051] The solid MAO is preferably defined by an aluminum content of 38% to 43% by mass. The aluminum content of the solid MAO is more preferably 40% to 42% by mass. The aluminum content of the solid MAO is highly preferably 40.5% to 41.5% by mass.

[0052] The solid MAO is advantageously in the form of particles defined by a mean diameter of 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and highly preferably 50 μm or less.

[0053] In one preferred embodiment, the solid MAO is in the form of particles defined by an average diameter of 1 to 50 μm, preferably 5 to 40 μm, preferably 10 to 30 μm, preferably 15 to 25 μm.

[0054] Advantageously, the molar ratio of solid MAO to chromium or titanium based metal precursor, expressed as Al / Cr or Al / Ti, is between 1 and 10,000, preferably between 25 and 5000, more preferably between 50 and 2500, and highly preferably between 100 and 1500. The molar ratio of solid MAO to chromium or titanium based metal precursor is calculated as the ratio between the number of moles of Al contained in the solid and the number of moles of metal contained in the precursor.

[0055] These characteristics of solid MAO can provide favorable properties for the polymeric by-products formed during the oligomerization reaction, such as an apparent density of polymer molecules that can prevent reactor fouling.

[0056] (additives in the form of aluminum-based compounds) The composition according to the invention comprises at least one additive in the form of an aluminium-based compound.

[0057] In one embodiment, the aluminum-based compound has the formula Al(R 19 ) 3, wherein R 19 is C1-C12 Alkyl, C1-C 12 alkoxy and halogen. Preferably, R 19 is C1-C 10 Alkyl, C1-C 10 alkoxy, preferably C1-C6 alkyl, C1-C6 alkoxy and independently selected from chlorine or bromine atoms. Preferably, R 19 is an alkyl and / or alkoxy group selected from methyl, ethyl, n-propyl, i-propyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl and octyl and the corresponding alkyloxy groups. 19 is an alkyl and / or alkoxy group selected from ethyl, propyl, i-propyl / isopropyl, n-butyl and tert-butyl and the corresponding alkyloxy groups.

[0058] More preferably, the aluminum-based compound is selected from trimethylaluminum (TMA), triethylaluminum (TEA), triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, trihexylaluminum, trioctylaluminum, diethylethoxyaluminum and dimethylethoxyaluminum, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, ethylaluminum sesquichloride, and aluminoxanes such as methylaluminoxane (MAO), modified methylaluminoxane (MMAO), or ethylaluminoxane (EAO), either alone or in mixtures.

[0059] More preferably, the aluminum-based compound is selected from trimethyl aluminum (TMA), triethyl aluminum (TEA), triisobutyl aluminum, methyl aluminoxane (MAO) and modified methyl aluminoxane (MMAO), either alone or in mixtures.

[0060] Highly preferred are the aluminum-based compounds trimethylaluminum (TMA), triethylaluminum (TEA), and triisobutylaluminum, either alone or in mixtures.

[0061] Preferably, the molar ratio of the aluminum-based compound to the chromium- or titanium-based metal precursor, expressed as Al / Cr or Al / Ti, is between 1 and 1500, preferably between 10 and 1000, more preferably between 20 and 500, and highly preferably between 50 and 300.

[0062] Without wishing to be bound by any particular theory, the presence of an additive in the form of an aluminum-based compound is essential to activate the metal precursor and generate the active species involved in the catalytic reaction. Solid MAO has a significantly lower amount of associated TMA than the amount of MAO in solution. In this context, the presence of the additive helps to alkylate the metal complex and initiate the catalytic reaction.

[0063] (Optional Solvent) The catalyst composition according to the invention may further comprise a solvent. The solvents that may be used are selected from organic solvents, more particularly saturated, unsaturated, cyclic or acyclic hydrocarbons.

[0064] The solvent(s) are advantageously chosen from halogenated solvents and saturated or unsaturated, cyclic or acyclic hydrocarbons containing from 1 to 20 carbon atoms, preferably from 1 to 15 carbon atoms, preferably from 4 to 15 carbon atoms.

[0065] Preferably, the solvent is selected from isobutane, pentane, hexane, heptane, cyclohexane, methylcyclohexane, butane or isobutane, dichloromethane, toluene, xylene, dichloroethane, chlorobenzene, dichlorobenzene in high purity or as a mixture, more preferably the solvent is selected from hexane, heptane, cyclohexane, methylcyclohexane, toluene and xylene.

[0066] In one preferred embodiment, the solvent may advantageously be selected from the products of the oligomerization reaction.

[0067] (Formulation of catalyst composition) The catalyst composition according to the present invention may be formulated by preparing a mixture containing a chromium or titanium based metal precursor, optionally a heteroatom ligand, solid MAO used as a support, and an aluminum based compound used as an additive.

[0068] Preferably, for the tetramerization of ethylene, the catalyst composition is formulated by preparing a mixture containing, on the one hand, a chromium-based metal precursor, optionally a heteroatom ligand, and solid MAO, and, on the other hand, one or more aluminum-based compounds.

[0069] Preferably, for ethylene trimerization, the catalyst composition is formulated by preparing a pre-catalyst mixture containing, on the one hand, a Ti-based metal precursor and solid MAO, and, on the other hand, one or more aluminum-based compounds.

[0070] More preferably, each component or mixture of components of the catalyst composition may be used in a solvent as defined above. In the case where the solvent is an unsaturated hydrocarbon, it may advantageously be selected from the products of the oligomerization reaction.

[0071] Use of the composition in a process for the oligomerization of olefins A further subject of the present invention relates to a process for the oligomerization, preferably the selective trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, using the catalyst composition according to the invention.

[0072] The feedstock used in the oligomerization process is preferably gaseous ethylene.

[0073] Advantageously, the concentration of the metal precursor (Cr or Ti) used in the oligomerization process is between 0.01 and 10,000 μmol / L, more preferably between 0.1 and 1000 μmol / L, highly preferably between 1 and 100 μmol / L.

[0074] The process may advantageously be carried out in the presence of a solvent as defined above.

[0075] Advantageously, the oligomerization process is carried out at a total pressure of 0.1 to 20.0 MPa, preferably 0.1 to 15.0 MPa, more preferably 0.5 to 8.0 MPa, and at a temperature of 15 to 200°C, preferably 20 to 100°C, and highly preferably 25 to 80°C.

[0076] The heat generated by the reaction may be removed via any means known to one skilled in the art.

[0077] Advantageously, the process for oligomerization, more particularly trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, may be carried out continuously. In one case, the components of the catalyst composition according to the invention are injected into a reactor stirred by conventional mechanical means or external recirculation, in which ethylene reacts, preferably with temperature control. In another case, solutions containing a mixture of a chromium- or titanium-based metal precursor supported on solid MAO, on the one hand, and one or more aluminum-based compounds, on the other hand, are injected separately into a reactor stirred by conventional mechanical means or external recirculation, in which ethylene reacts, preferably with temperature control.

[0078] The catalyst composition may be neutralized downstream of the reactor via any means known to those skilled in the art.

[0079] The following examples illustrate the present invention but do not limit the scope of the invention.

[0080] DESCRIPTION OF THE DRAWINGS 1 shows an image of the reactor agitator blade after an ethylene oligomerization process utilizing a catalyst composition containing MAO in the homogeneous phase, as described in Examples 1 or 7. "Sticky" polymeric by-products are observed on the agitator, which are difficult to remove and cause reactor fouling.

[0081] Figure 2 shows a scanning electron microscope image of the morphology of the polymeric by-product from Figure 1. "Filamentary" structures are observed, which are characteristic of polymers with uncontrolled morphology.

[0082] 3 shows an image of the reactor agitator blade after an ethylene oligomerization process utilizing a catalyst composition containing solid MAO as described in Examples 3, 4, 5, 6, 9, or 10. Particulate polymeric by-products are observed on the agitator, which are easy to remove and do not cause reactor fouling.

[0083] Figure 4 shows a scanning electron microscope image of the morphology of the polymeric by-product from Figure 3. A "fine grain" structure is observed, which is characteristic of polymers with controlled morphology.

[0084] (Example) Example 1 (Comparative): Process for the Trimerization of Ethylene Using a Solution of MAO in a Homogeneous Phase in Toluene (500 Equivalents of Al Relative to Ti) as a Cocatalyst In a glove box, 11.4 mg (20.0 mmol) of trichloridoaryloxyimino titanium(IV) complex as shown in structure (iv) below is weighed into a Schlenk flask, and then 10 mL of dry toluene is added under argon (the concentration of the solution is 2.0 mM).

[0085] [ka]

[0086] 91 mL of cyclohexane is introduced into a 250 mL reactor. The reactor's internal temperature is previously adjusted to 25 °C, and the ethylene pressure is 0.5 bar. 5 bar of gaseous ethylene is then introduced, and the solvent is saturated with ethylene while stirring at 1500 rpm for 1 minute. The reactor pressure is again reduced to 0.5 bar, and the stirring is stopped. Next, 5 mL of nonane (3.6 g, internal standard) dried over molecular sieves, 2.0 mL (4 μmol) of a 2.0 mM titanium complex solution, and 1.25 mL of MAO solution (solution % Al: 4.90%, density: 0.880 g / mL), or approximately 54 mg (2.0 mmol) of Al, are introduced. The ethylene inlet valve is then opened (30 bar pressure), stirring is started, and the reactor heating set point is increased to 28 °C.

[0087] At the end of the test, the ethylene supply is shut off, the mixture is cooled to 20°C, and the gas phase is then discharged to a vent. The reactor is then opened. The liquid is transferred to a bottle containing 1.00 mL of a 10% H2SO4 solution. A sample amount of the organic phase is removed for analysis and filtered. The results are listed in Table 1.

[0088] Example 2 (Comparative): Process for the Additive-Free Trimerization of Ethylene Using a Solid MAO Cocatalyst (1000 Equivalents of Al Relative to Ti) Introduced into a Schlenk flask under argon is 2.70 mL of solid MAO (11.24 wt%, Al mass content of MAO: 41.2%, density: 0.868 g / mL, average particle size: 20 μm) supplied by Tosoh, or approximately 109 mg (4.0 mmol) of Al. 2.00 mL (4 μmol) of a 2.0 mM titanium(IV) complex solution is added to the Schlenk flask containing the solid MAO. An orange gel forms at the bottom of the Schlenk flask. The mixture is heated at 50° C. for 1 h with manual stirring every 15 min.

[0089] The heating setpoint of the thermostatic bath of the reactor is adjusted to 25°C. 91.0 mL of cyclohexane are then introduced into the reactor, which has been preconditioned by the introduction of an atmosphere of 0.5 bar of ethylene. After the introduction of 5 bar of gaseous ethylene, the solvent is then saturated with ethylene while stirring at 1500 rpm for 1 minute. The pressure of the reactor is reduced to 0.5 bar and the stirring is stopped. 5 mL of nonane (3.6 g) dried over molecular sieves are introduced. Finally, the entire oligomerization catalyst prepared previously is introduced, suspending the catalyst in toluene. The ethylene inlet valve is opened (30 bar pressure), the stirring is started, and the heating setpoint of the reactor is then increased to 28°C.

[0090] At the end of the test, the ethylene supply is shut off, the mixture is cooled to 20°C, and the gas phase is then discharged to a vent. The reactor is then opened. The liquid is transferred to a bottle containing 1.00 mL of a 10% H2SO4 solution. A sample amount of the organic phase is removed for analysis and filtered. The results are listed in Table 1.

[0091] Example 3 (In Accordance with the Invention): Process for Ethylene Trimerization Using Solid MAO Cocatalyst (1000 Equivalents of Al Relative to Ti) and TEA as Additive The test is carried out under the same conditions as in Example 2, except that 1.00 mL (0.2 mmol) of a 0.20 M solution of TEA in cyclohexane is introduced into the reactor. The solution of TEA is introduced after the nonane. The results are listed in Table 1.

[0092] Example 4 (In Accordance with the Invention): Process for Ethylene Trimerization Using Solid MAO Cocatalyst (521 Equivalents of Al Relative to Ti) and TEA as Additive This test is carried out under the same conditions as in Example 3, but with 1.40 mL of Tosoh solid MAO (11.24 wt%, Al mass content of MAO: 41.2%, density: 0.868 g / mL, average particle size: 20 μm), or approximately 56 mg (2.1 mmol) of Al. The results are listed in Table 1.

[0093] Example 5 (In Accordance with the Invention): Process for Ethylene Trimerization Using Solid MAO Cocatalyst (1000 Equivalents of Al Relative to Ti) and TMA as Additive The test is carried out under the same conditions as in Example 3, but with 1.00 mL (0.2 mmol) of a 0.20 M solution of TMA introduced into the reactor. The solution of TMA is introduced after the nonane. The results are given in Table 1.

[0094] Example 6 (In Accordance with the Invention): Process for Ethylene Trimerization Using Solid MAO Cocatalyst (521 Equivalents of Al Relative to Ti) and TMA as Additive This test is carried out under the same conditions as in Example 4, but with 1.00 mL (0.2 mmol) of a 0.20 M solution of TMA introduced into the reactor. The solution of TMA is introduced after the nonane.

[0095] The results of Examples 1 to 6 are shown in Table 1.

[0096] [Table 1]

[0097] Example 7 (Comparative) - Process for the Tetramerization of Ethylene in Solution Using a Conventional Solution of MMAO-3A in Homogeneous Phase in Cyclohexane (1340 Equivalents of Al Relative to Cr) as a Cocatalyst Trial tests of ethylene tetramerization were carried out with C2H4 containing 0.5 mol% H2.

[0098] 188 mL of cyclohexane is introduced into a 500 mL reactor. The internal temperature of the reactor is previously adjusted to 25 °C, and the ethylene pressure is 0.5 bar. After the introduction of 5 bar of the gas, the solvent is then saturated with ethylene while stirring at 1500 rpm for 1 minute. The pressure in the reactor is again evacuated to 0.5 bar, and stirring is discontinued. 4.0 mL of a solution of de MMAO-3A (solution % Al: 0.6%, density: 0.723 g / mL), or approximately 18 mg (0.67 mmol) of Al, is introduced. In parallel, a Schlenk flask is charged under Ar with 4.0 mL (0.5 μmol) of a 0.125 mM solution of the complex Cr(acac)3 and 4.0 mL (0.6 μmol) of a 0.15 mM solution of the ligand N,N-bis(bis(2-fluorophenyl)phosphino)isopropylamine. 8 mL of the Cr / ligand solution is then injected into the reactor. The ethylene inlet valve is opened (40 bar pressure), stirring is started, and the reactor heating set point is then increased to 45°C.

[0099] After 1 hour of reaction, the ethylene supply is shut off, the mixture is cooled to 20°C, and the gas phase is then gently discharged into the vent. The reactor is then opened. The liquid is transferred to a bottle containing 1.00 mL of a 10% H2SO4 solution. A sample amount of the organic phase is removed for analysis and filtered.

[0100] Example 8 (Comparative) - Process for the Tetramerization of Ethylene in Solution Using Solid MAO (1360 Equivalents of Al Relative to Cr) as a Cocatalyst Solid MAO, sold by Tosoh, is supplied in the form of a suspension in toluene (11.24 wt%, Al mass content of MAO: 41.2%, density: 0.868 g / mL, average particle size: 20 μm). To prevent the presence of toluene, which could poison the catalyst, a suspension of solid MAO in cyclohexane is prepared. A Schlenk flask is charged with 10 mL of solid MAO (402 mg of Al, 14.9 mmol). The suspension is filtered and the powder is washed with cyclohexane (2 × 5 mL). Finally, 119 mL of cyclohexane is added to give a 0.125 M suspension of solid MAO.

[0101] 188 mL of cyclohexane is introduced into a 500 mL reactor. The internal temperature of the reactor is previously adjusted to 25 °C, and the ethylene pressure is 0.5 bar. After the introduction of 5 bar of the gas, the solvent is then saturated with ethylene while stirring at 1500 rpm for 1 minute. The reactor pressure is again evacuated to 0.5 bar, and the stirring is stopped. 5.4 mL of a suspension of solid MAO in cyclohexane, or approximately 18 mg (0.68 mmol) of Al, is introduced. In parallel, a Schlenk flask is charged under Ar with 4.0 mL (0.5 μmol) of a 0.125 mM solution of the complex Cr(acac)3 and 4.0 mL (0.6 μmol) of a 0.15 mM solution of the ligand N,N-bis(bis(2-fluorophenyl)phosphino)isopropylamine. 8 mL of the Cr / ligand solution is then injected into the reactor. The ethylene inlet valve is opened (40 bar pressure), the agitator is started and the reactor heating set point is then increased to 45°C.

[0102] After 1 hour of reaction, the ethylene supply is shut off, the mixture is cooled to 20°C, and the gas phase is then gently discharged into the vent. The reactor is then opened. The liquid is transferred to a bottle containing 1.00 mL of a 10% H2SO4 solution. A sample amount of the organic phase is removed for analysis and filtered.

[0103] Example 9 (In Accordance with the Invention) - Method for the Tetramerization of Ethylene in Solution Using Solid MAO (1360 Equivalents of Al Relative to Cr) and TEA as Cocatalysts Trial tests of ethylene tetramerization were carried out with C2H4 containing 0.5 mol% H2.

[0104] This test is carried out under the same conditions as in Example 8, but with 0.4 mL (0.05 mmol) of a 0.125 M TEA solution introduced into the reactor as an additive. The solution of TEA is introduced after the solid MAO.

[0105] Example 10 (In Accordance with the Invention) - Method for the Tetramerization of Ethylene in Solution Using Solid MAO (1360 Equivalents of Al Relative to Cr) and TEA as Cocatalysts Trial tests of ethylene tetramerization were carried out with C2H4 containing 0.5 mol% H2.

[0106] This test is carried out under the same conditions as in Example 8, but with 2.00 mL (0.25 mmol) of a 0.125 M TEA solution introduced into the reactor as an additive. The solution of TEA is introduced after the solid MAO.

[0107] The results of Examples 7 to 10 are shown in Table 2.

[0108] [Table 2]

[0109] These examples demonstrate that the catalyst composition according to the invention is functional with the presence of an additive in the form of an aluminum-based compound, allowing high selectivity for the selected molecule (currently 1-hexene or 1-octene) close to that of the homogeneous MAO-based prior art catalyst compositions, and providing access to polymer by-products (here PE) with controlled morphology, which, unlike "sticky" filaments of PE, do not foul the oligomerization reactor and can be easily removed from the reactor.

[0110] 1 shows an image of the reactor agitator blade after an ethylene oligomerization process utilizing a catalyst composition containing MAO in the homogeneous phase, as described in Examples 1 or 7. "Sticky" polymeric by-products are observed on the agitator, which are difficult to remove and cause reactor fouling.

[0111] Figure 2 shows a scanning electron microscope image of the morphology of the polymeric by-product from Figure 1. "Filamentary" structures are observed, which are characteristic of polymers with uncontrolled morphology.

[0112] 3 shows an image of the reactor agitator blade after an ethylene oligomerization process utilizing a catalyst composition containing solid MAO as described in Examples 3, 4, 5, 6, 9, or 10. Particulate polymeric by-products are observed on the agitator, which are easy to remove and do not cause reactor fouling.

[0113] Figure 4 shows a scanning electron microscope image of the morphology of the polymeric by-product from Figure 3. A "fine grain" structure is observed, which is characteristic of polymers with controlled morphology. [Brief explanation of the drawings]

[0114] [Figure 1] 1 depicts an image of a reactor impeller following an ethylene oligomerization process utilizing a catalyst composition comprising MAO in a homogeneous phase, as described in Examples 1 or 7. [Figure 2] 2 depicts a scanning electron microscope image of the morphology of the polymeric by-product from FIG. 1. [Figure 3] 1 depicts an image of a reactor impeller following an ethylene oligomerization process utilizing a catalyst composition comprising solid MAO as described in Examples 3, 4, 5, 6, 9, or 10. [Figure 4] 4 depicts a scanning electron microscope image of the morphology of the polymeric by-product from FIG. 3.

Claims

1. 1. A catalyst composition for the selective oligomerization of ethylene, more particularly the trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, comprising: at least one metal precursor based on chromium or titanium; at least one support in the form of solid methylaluminoxane (MAO); at least one additive in the form of an aluminium-based compound.

2. 10. The catalyst composition of claim 1, wherein the chromium precursor is selected from salts of chromium (II) or chromium (III).

3. 3. The catalyst composition of claim 1 or 2, further comprising at least one heteroatom ligand.

4. 10. The catalyst composition of claim 1, wherein the titanium precursor is selected from Ti(IV) coordination complexes conforming to formula (ii): 【Chemistry 1】 During the ceremony, R ６ , R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ , R １４ , R １５ , R １６ , R １７ and R １８ are the same or different, bonded or not bonded to each other, and have 1 to 15 carbon atoms (C １ -C １５ ) having cyclic or acyclic alkyl groups and / or 4 to 15 carbon atoms (C ４ -C １５ aryl groups having one or more substituted or unsubstituted aryl groups, or aryl groups having 4 to 15 carbon atoms (C ４ -C １５ ) and a substituted or unsubstituted aryl group.

5. 5. The catalyst composition according to any one of claims 1 to 4, wherein the molar ratio of solid MAO to chromium or titanium based metal precursor, expressed as Al / Cr or Al / Ti, is from 1 to 10,000, preferably from 25 to 5000, more preferably from 50 to 2500, and highly preferably from 100 to 1500.

6. 6. The catalytic composition according to claim 1, wherein the aluminum mass content of the solid MAO is 36% to 52% by mass.

7. 7. The catalytic composition according to any one of claims 1 to 6, wherein the solid MAO is in the form of particles defined by an average diameter of 1 to 50 μm, preferably 5 to 40 μm, preferably 10 to 30 μm, preferably 15 to 25 μm.

8. Aluminum-based compounds have the formula Al(R １９ ) ３ wherein R １９ are independently １ -C １２ Alkyl, C １ -C １２ 8. The catalyst composition according to any one of claims 1 to 7, wherein the alkoxy group is selected from alkoxy and halogen.

9. 9. The catalyst composition of claim 8, wherein the aluminum-based compounds are trimethylaluminum (TMA), triethylaluminum (TEA), and triisobutylaluminum, either alone or in mixture.

10. 10. The catalyst composition according to any one of claims 1 to 9, wherein the molar ratio of the aluminium-based compound to the chromium or titanium-based metal precursor, expressed as Al / Cr or Al / Ti, is between 1 and 1500, preferably between 10 and 1000, more preferably between 20 and 500, and highly preferably between 50 and 300.

11. The catalyst composition of any one of claims 1 to 10, further comprising a solvent.

12. 12. Catalytic composition according to claim 11, wherein the solvent is advantageously chosen from halogenated solvents and saturated or unsaturated, cyclic or acyclic hydrocarbons containing from 1 to 20 carbon atoms, preferably from 1 to 15 carbon atoms, preferably from 4 to 15 carbon atoms.

13. 13. A process for the oligomerization of ethylene, preferably the selective trimerization and / or tetramerization of ethylene to 1-hexene and / or 1-octene, respectively, using a catalyst composition according to any one of claims 1 to 12.

14. 14. The process for oligomerization according to claim 13, wherein the concentration of the metal precursor supported on the solid MAO is 0.01 to 10,000 μmol / L, preferably 0.1 to 1000 μmol / L, highly preferably 1 to 100 μmol / L.

15. 15. The process for oligomerization according to claim 13 or 14, wherein the process is carried out at a total pressure of 0.1 to 20.0 MPa, preferably 0.1 to 15.0 MPa, more preferably 0.5 to 8.0 MPa, and at a temperature of 15 to 200°C, preferably 20°C to 100°C, and highly preferably 25°C to 80°C.

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