Catalyst system

Abstract

A catalyst system suitable for tetramerization of ethylene to form 1-octene can include a catalyst including a chromium compound coordinated with a ligand and a co-catalyst including an organoaluminum compound. The chemical structure of the ligand can be: (R1)(R2)A-X-C(R3)(R4). A and C can be phosphorus. X can be B(R5), Si(R5)2, N(R5), where R5 is aryl substituted with halogen, haloalkyl, or silyl, and where B or N or Si is bonded to A and C. R1, R2, R3, and R4 can be independently selected from hydrocarbyl or heterohydrocarbyl.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit and priority of U.S. Application Serial No. 63 / 160,067, filed March 12, 2021, entitled “Catalyst System”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of this disclosure generally relate to chemical treatments, and more specifically to catalyst systems used in such chemical treatments. Background Technology

[0004] Linear alpha-olefins (“LAO”) are typically produced through the cracking of petroleum products or the non-selective oligomerization of ethylene, resulting in a broad alpha-olefin profile. Currently, several industrial processes exist for LAO production, such as the Shell Advanced Olefins Process (SHOP), which has been in use since 1977. SHOP combines oligomerization and olefin metathesis chemistry, using nickel-based catalysts to produce a variety of LAOs. Global petrochemical manufacturer INEOS has also developed patented processes for synthesizing a wide range of LAOs, allowing for flexible changes in product profile to meet demand.

[0005] However, demand for LAO is growing in North America, Western Europe, and Asia. In particular, demand for short-chain alpha-olefins (such as 1-octene and 1-hexene) is increasing because they are important for many specific applications. For example, 1-octene can be used to improve the rheological melt and solid resin properties of polyethylene. Therefore, the main consumers of 1-octene are the industries responsible for large-volume production of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), and this number is expanding annually. The 1-octene content in HDPE can range from 1% to 2%, and in some LLDPE grades, it can be as high as 30%.

[0006] Therefore, 1-octene is an important chemical feedstock in market demand. In addition to the methods discussed above, various catalysts have been developed for the selective formation of 1-octene through ethylene tetramerization. However, these catalysts have shortcomings in several aspects, such as the selectivity for 1-octene and the tendency to foul the polymer. Therefore, there is an industrial need for improved catalysts suitable for the selective formation of 1-octene through ethylene tetramerization. Summary of the Invention

[0007] As described in the present disclosure, fouling refers to undesired polymer formation. Such polymers can form as a byproduct in the reaction of ethylene to form 1-octene when using catalyst systems that include chromium. However, as described in the present disclosure, it has been found that the use of particular ligands that can coordinate with chromium can reduce fouling. Further, in some embodiments, the use of catalysts that include the ligands can help maintain, or even enhance, the selectivity to 1-octene compared to similar catalyst systems.

[0008] According to one or more embodiments, a catalyst system suitable for tetramerization of ethylene to form 1-octene can include: a catalyst including a chromium compound coordinated with a ligand; and a co-catalyst including an organoaluminum compound. The ligand can have the chemical structure: (R1)(R2)A-X-C(R3)(R4). A and C can be phosphorus. X can be B(R5), Si(R5)2, or N(R5), where R5 is an aryl group substituted with a halogen, a haloalkyl group, or a silyl group, and where B or N or Si is bonded to A and C. R1, R2, R3, and R4 can be independently selected from a hydrocarbyl group or a heterohydrocarbyl group.

[0009] Additional features and advantages of aspects of the present disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art who practice the aspects of the present disclosure, or can be learned by practice of the aspects of the present disclosure. DETAILED DESCRIPTION

[0010] The present disclosure describes catalyst systems that can be used to produce 1-octene from ethylene via a tetramerization reaction. Methods of using such catalyst systems are also described. The presently described catalyst systems can include a catalyst and a co-catalyst, which will be described in detail. In one or more embodiments, the catalyst can include chromium and a ligand. The co-catalyst can include an organoaluminum compound.

[0011] In one or more embodiments, the catalyst systems described in the present disclosure can be used to selectively tetramerize ethylene to produce 1-octene while reducing undesired polymerization, sometimes referred to as “fouling.” Fouling can occur at least in part due to the formation of solid polyethylene-based residue, which can reduce fluid flow rates and / or completely or at least partially prevent fluid in a reactor system from flowing at a desired rate. Without being bound by any particular theory, it is believed that the incorporation of the ligands described in the present disclosure into the catalyst system reduces fouling while maintaining suitable 1-octene yields.

[0012] It should be appreciated that the catalyst systems described in the present disclosure can not completely eliminate fouling during a reaction. However, in one or more embodiments, these catalyst systems reduce fouling as compared to catalyst systems that do not include the ligands described in the present disclosure. Additionally, it should be appreciated that while these catalyst systems can be used to catalyze the oligomerization of ethylene (e.g., ethylene tetramerization to form 1-octene), they can also be used to catalyze other chemical reactions. Thus, the use of these catalyst systems should not be considered limited to the tetramerization of ethylene to form 1-octene.

[0013] As used in the present disclosure, the term “catalyst” refers to any substance that increases the rate of a particular chemical reaction. The catalysts described in the present disclosure can be used to facilitate a variety of reactions, such as, but not limited to, the tetramerization of ethylene to form 1-octene. Catalysts are generally not consumed in the reaction, but as is understood in the art, catalyst activity can decrease over time and require replacement and / or regeneration.

[0014] As used in the present disclosure, the term “co-catalyst” (also referred to as an activator and / or scavenger) generally refers to any substance or chemical agent that, in combination with one or more catalysts, causes catalysis of a chemical reaction. In some embodiments, a catalyst can have independent catalytic functionality, while in other embodiments, a catalyst can only have significant catalytic functionality when paired with a co-catalyst. It should be appreciated that in some embodiments, a catalyst and a co-catalyst can be bonded or form a complex, but in other embodiments, are not bonded or present in a complex. Some co-catalysts can be said to “activate” a catalyst, which can increase the catalytic functionality.

[0015] As used in the present disclosure, the term “catalyst system” refers to any catalytic functionality set of chemical substances. In one or more embodiments, a catalyst system can include a catalyst and a co-catalyst. In some embodiments, a catalyst system can include additional components, such as, for example, additional co-catalysts or non-catalytic additives that can be used for other purposes.

[0016] As used in the present disclosure, the term “independently selected from” means that R groups, such as, for example, R1, R2, and R3, can be the same or different. For example, R1, R2, and R3 can all be substituted alkyl groups; or R1 and R2 can be substituted alkyl groups and R3 can be an aryl group. R groups can contain heteronuclear atoms other than C and H, such as, for example, N and O. Chemical names associated with R groups are intended to convey the chemical structure that is recognized in the art to correspond to the chemical name. Thus, the chemical names are intended to supplement and illustrate, rather than exclude, structural definitions known to those skilled in the art.

[0017] As used in the present disclosure, the term “reaction product” refers to a chemical species formed from the reaction of any two or more reactant species or reagents. The reaction product can result in a covalent or ionic bond, coordination, or other interaction between the reactant species. In one or more embodiments, two or more reaction products can result from the reaction of reactant species, and all such possible resulting chemical species are included in the reaction product.

[0018] When used to describe certain carbon atom-containing chemical groups, the parenthetical expression in the form of “(C x -C y ” means that the unsubstituted form of the chemical group has x carbon atoms to y carbon atoms, inclusive of x and y. For example, a (C1-C 50 )alkyl group is an alkyl group having from 1 to 50 carbon atoms in its unsubstituted form. In some embodiments and general structures, certain chemical groups can be substituted with one or more substituents. A substituted chemical group defined using “(C x -C y ” parentheses can contain more than y carbon atoms, depending on the identity of any substituents. For example, a “(C1-C 50 )alkyl group that is exactly substituted with one phenyl group (-C6H5) can contain from 7 to 56 carbon atoms. Thus, in general, when a chemical group defined using “(C x -C y ” parentheses is substituted with one or more carbon atom-containing substituents, the minimum and maximum total number of carbon atoms of the chemical group is determined by adding the sum of the number of carbon atoms of all carbon atom-containing substituents to x and y.

[0019] The term “substituted” means that at least one hydrogen atom (-H) bonded to a carbon atom or a heteroatom of the corresponding unsubstituted compound or functional group is replaced with a substituent. The substituent can be any suitable functional group or group that can replace the hydrogen atom bonded to the carbon atom or heteroatom of the corresponding unsubstituted compound. For example, the substituent can include, but is not limited to, a hydrocarbyl group, a cyclohydrocarbyl group, an aryl group, a halogen, and an amine.

[0020] The term “-H” means hydrogen or a hydrogen group covalently bonded to another atom. “Hydrogen” and “-H” are interchangeable and have the same meaning unless explicitly stated otherwise.

[0021] The term “hydrocarbyl group” means a monovalent group derived from a hydrocarbon (including aromatic, non-aromatic, cyclic, or acyclic, saturated or unsaturated, straight-chain or branched, heteroatom-containing or non-heteroatom-containing, and substituted or unsubstituted hydrocarbons) by removal of any hydrogen atom.

[0022] The term "heteroalkyl" refers to a hydrocarbyl group in which at least one carbon atom has been replaced by a heteroatom. Examples of heteroatoms include, but are not limited to, oxygen, nitrogen, sulfur, and phosphorus.

[0023] The term "cycloalkyl" refers to a cyclic hydrocarbyl group, aromatic or non-aromatic, having at least three carbon atoms, including monocyclic and polycyclic hydrocarbyl groups, fused polycyclic hydrocarbyl groups and non-fused polycyclic hydrocarbyl groups, as well as bicyclic hydrocarbyl groups, non-aromatic saturated cyclic hydrocarbyl groups or non-aromatic unsaturated cyclic hydrocarbyl groups, and substituted or unsubstituted hydrocarbyl groups.

[0024] The term "aryl" refers to an aromatic hydrocarbyl group, in which the carbon atoms of the aromatic system can be substituted or unsubstituted. Aryl groups include monocyclic, bicyclic and tricyclic aromatic hydrocarbyl groups. Monocyclic aromatic hydrocarbyl groups include one aromatic ring; bicyclic aromatic hydrocarbyl groups have two rings; tricyclic aromatic hydrocarbyl groups have three rings. When a bicyclic or tricyclic aromatic hydrocarbyl group is present, at least one ring of the group is an aromatic ring. Other rings or other polycyclic rings of the aromatic group can independently be fused or non-fused and aromatic or non-aromatic. Non-limiting examples of aryl groups include phenyl; fluorenyl; tetrahydrofluorenyl; indacenyl; hexahydroindacenyl; indenyl; dihydroindenyl; naphthyl; tetrahydronaphthyl; and phenanthrenyl.

[0025] The term "alkyl" refers to a saturated hydrocarbyl group, which can be straight-chain or branched. Thus, the term "(Ci-C 20 )alkyl" refers to a saturated straight-chain or branched hydrocarbyl group of from 1 to 20 carbon atoms, which is unsubstituted or substituted. Examples of unsubstituted (Ci-C 20 )alkyl groups include methyl; ethyl; 1 -propyl; 2-propyl; 1 -butyl; 2-butyl; 2-methylpropyl; 1,1 -dimethylethyl; 1 -pentyl; 1 -hexyl; 1 -heptyl; 1 -nonyl; and 1 -decyl. Examples of substituted (Ci-C 20 )alkyl groups include trifluoromethyl and trifluoroethyl.

[0026] The term "saturated" refers to the absence of carbon-carbon double bonds, carbon-carbon triple bonds, and (in heteroatom-containing groups) carbon-nitrogen double bonds, carbon-phosphorus double bonds, and carbon-silicon double bonds. When a saturated chemical group is substituted with one or more substituents, one or more double bonds and / or triple bonds optionally can be present in the substituents. The term "unsaturated" refers to the presence of one or more carbon-carbon double bonds or carbon-carbon triple bonds, or (in heteroatom-containing groups) one or more carbon-nitrogen double bonds, carbon-phosphorus double bonds, or carbon-silicon double bonds, excluding any double bonds that can be present in substituents (if any) or in aromatic or heteroaromatic rings (if any).

[0027] As previously mentioned, embodiments of the present disclosure relate to catalyst systems suitable for tetramerization of ethylene to form 1-octene. In one or more embodiments, the catalyst system includes a catalyst. In some embodiments, the catalyst includes chromium. It should be appreciated that a catalyst including chromium, as contemplated by the present disclosure, can be any compound including chromium and having catalytic functionality, for but not limited to, facilitating tetramerization of ethylene to form 1-octene.

[0028] In one or more embodiments, the catalyst includes a chromium compound and a ligand. It should be appreciated that the chromium complex described herein that can coordinate with one or more ligands is not necessarily limited to the structure, but includes chromium. In some embodiments, the chromium compound includes an organochromium salt, an inorganic chromium salt, a chromium coordination compound, a chromium organometallic complex, or a combination of these. In some embodiments, the chromium compound includes tris(tetrahydrofuran)chromium chloride complex, (benzene)tricarbonyl chromium, chromium (III) octoate, chromium (III) acetylacetonate, chromium hexacarbonyl, and chromium (III) 2-ethylhexanoate, or a combination of these.

[0029] It should be appreciated that the ligand described herein that can coordinate with the chromium in the chromium complex is not necessarily limited to the structure. However, in one or more embodiments, the ligand can have a structure according to Formula (I):

[0030] (R1)(R2)A-X-C(R3)(R4) Formula (I)

[0031] In Formula (I), A and C are each phosphorus (P); X is a linking group between A and C; R1, R2, R3, and R4are independently selected from any hydrocarbyl or heterohydrocarbyl group. As used in the present disclosure, the term “linking group” refers to any chemical moiety that covalently bonds at least two other chemical moieties. For example, X can be a chemical moiety that covalently bonds the chemical moieties of A and C. In one or more embodiments, X can include one or more elements selected from Group IIIA, Group IVA, Group VA, and Group VIA. In one or more embodiments, X can be B(R5), Si(R5)2, or N(R5). R5may be an aryl group substituted with a halogen, a haloalkyl group, or a silyl group. In some embodiments, one or more of R1, R2, R3, and R4may include an aryl moiety. In some embodiments, R1, R2, R3, and R4may be independently selected from benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl, naphthyl, anthryl, methoxy, ethoxy, phenoxy, tolyloxy, dimethylamino, diethylamino, methylethylamino, thienyl, pyridyl, thioethyl, thienyloxy, trimethylsilyl, dimethylhydrazino, methyl, ethyl, ethenyl, propyl, butyl, propenyl, propynyl, cyclopentyl, cyclohexyl, ferrocenyl, or tetrahydrofurfuryl.

[0032] In some embodiments, R1, R2, and A can be bonded, or R3, R4, and C can be bonded, thereby forming a cyclic moiety. In such embodiments, A and C can be phosphorus, such that a cyclic moiety comprising P is formed. For example, R1, R2, and A can be bonded, thereby forming a cyclic moiety comprising P. Likewise, R3, R4, and C can be bonded, thereby forming a cyclic moiety comprising P. In one or more embodiments, R1, R2, and P can form a phospholane group. In one or more embodiments, R3, R4, and P can form a phospholane group. As described herein, a "phospholane group" refers to a cyclic organophosphorus compound comprising a five-membered ring containing phosphorus and four carbon atoms. In some embodiments, the phospholane compound can be unsubstituted or can be substituted with one or more hydrocarbyl groups. In some embodiments, the cyclic moiety that can be formed from R1, R2, and P or R3, R4, and P is depicted in formulas (II) to (IX).

[0033]

[0034]

[0035]

[0036]

[0037] In one or more embodiments, X can be an organic linking group comprising— N(R5)—, where R5 is a substituted aryl group. The substituted aryl group R5 can be substituted with a haloalkyl group or a silyl group. A haloalkyl group can be any alkyl group substituted with at least one halogen, including but not limited to fluorine, chlorine, bromine, and iodine. In one or more embodiments, the haloalkyl group can be represented by the formula C n F 2n+1 In one or more embodiments, the haloalkyl group is a trifluoromethyl group. As described herein, a "silyl group" has the general structure: SiZ3, where each Z is independently selected from a substituted or unsubstituted hydrocarbyl group or a substituted or unsubstituted heterohydrocarbyl group. In one or more embodiments, the substituted aryl group R5 can be substituted such that the substitution is located at the meta position.

[0038] Without wishing to be bound by theory, the electronic properties of the ligand, whether the moieties of the ligand are electron donors or electron acceptors, can influence the strength of ethylene binding to the catalytic metal center. In addition, the bulk of the ligand can introduce steric hindrance, which can also influence the strength of ethylene binding to the metal center. Thus, the ligand can influence the reactivity and selectivity of the catalyst for 1-octene formation.

[0039] In one or more embodiments, the ligand can be an N-aryl bisphosphane ligand. For example, in some embodiments, the ligand has a structure according to Formula (X):

[0040]

[0041] In Formula (X), each Ar is independently selected from substituted or unsubstituted aryl; R6, R7, R8, R9, and R 10 are each independently selected from hydrogen (H) or substituted or unsubstituted hydrocarbyl. In one or more embodiments, one or more of R6, R7, R8, R9, and R 10 are haloalkyl or silyl groups. In some embodiments, one or more of R6, R7, R8, R9, and R 10 are groups represented by the chemical formula C n F 2n+1 In some embodiments, one or more of R6, R7, R8, R9, and R 10 are groups represented by the chemical formula SiZ3, where each Z is independently selected from substituted or unsubstituted hydrocarbyl or substituted or unsubstituted heterohydrocarbyl. In one or more embodiments, at least one of R7or R9is haloalkyl or silyl. For example, in some embodiments, the ligand is C6H4(m-CF3)N(PPh2)2. Without wishing to be bound by theory, when the substitution is in the meta position, the electro-deficiency of the catalytic center is reduced, such that ethylene binds to form a cyclic intermediate, which favors the formation of 1-octene. The formation of 1-octene is shown in Reaction Scheme (I).

[0042]

[0043] In one or more embodiments, the catalyst can include an amount of ligand such that the molar ratio of ligand to chromium in the catalyst is 0.1 to 10.0.

[0044] The chromium compound and the ligand can be produced using processes and methods known in the art. For example, processes and methods for producing chromium compounds are described in U.S. Patent No. 7,297,832, which is incorporated by reference in its entirety to the present application.

[0045] In one or more embodiments, the catalyst system further includes a co-catalyst. In some embodiments, the co-catalyst can include an organoaluminum compound. As described in the present disclosure, the term “organoaluminum compound” refers to any compound that includes at least one aluminum atom and any organic moiety. It should be understood that the organoaluminum compound can include several chemical species, or can be a single chemical species. In some embodiments, the organoaluminum compound can be an alkylaluminum compound. The alkylaluminum compound may, for example, have a structure according to Formula (XI):

[0046]

[0047] In Formula (XI), R 11 , R 12 , and R 13 are each independently selected from a hydrogen atom or a (C1-C 20 )hydrocarbyl group or a (C1-C 20 )heterohydrocarbyl group. In embodiments, the (C1-C 20 )hydrocarbyl group can be a substituted or unsubstituted (C1-C 20 )straight chain or branched hydrocarbyl group. In one or more embodiments, R 11 , R 12 , and R 13 may each be a hydrogen or a straight chain or branched (C1-C 20 )alkyl group. In some embodiments, the alkylaluminum compound can be an aluminoxane structure (a partial hydrolysis product of a trialkylaluminum compound). For example, suitable alkylaluminum compounds can include trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, trihexylaluminum, tri-n-octylaluminum, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, isopropylaluminum, ethylaluminum sesquichloride, methylaluminum sesquichloride, methylaluminoxane (MAO), ethylaluminoxane (EAO), and modified alkylaluminoxanes, such as modified methylaluminoxane (MMAO). As described in the present disclosure, the term “modified alkylaluminoxane” refers to an alkylaluminoxane that includes one or more modifying groups (such as isobutyl or n-octyl) in addition to the alkyl groups. In one or more embodiments, the organoaluminum compound of the catalyst system can include, consist essentially of, or consist of any of these compounds.

[0048] Without wishing to be bound by theory, the alkylaluminum compound can be used to remove impurities or poisons that can have a negative effect on the catalyst. Additionally, the alkylaluminum compound can be used to alkylate the chromium compound. Further, the alkylaluminum compound can be used to activate the chromium compound to allow ethylene to coordinate with the catalyst.

[0049] In one or more embodiments, the catalyst system can include an amount of cocatalyst such that the molar ratio of aluminum to chromium in the catalyst system is 1 to 5000.

[0050] In one or more embodiments, ethylene can be contacted with the catalyst system to form a reaction product including 1-octene. Contacting can generally include any mixing and / or combining of the reactant ethylene with the catalyst system. In some embodiments, the catalyst and cocatalyst can be separately prepared as solutions and then combined prior to contacting the catalyst system with ethylene. In some embodiments, the catalyst system can be contacted with ethylene in the presence of one or more reaction media. Suitable reaction media can include, for example, cyclohexane and chlorobenzene. In some embodiments, ethylene can be contacted with the catalyst system in the presence of hydrogen.

[0051] In one or more embodiments, the reaction can be conducted as a batch reaction or as a continuous process reaction (e.g., a continuous stirred tank reactor process). In some embodiments, the reactor can have a pressure of 2 bar to 120 bar (e.g., 10 bar to 50 bar), and a reactor temperature of 30 °C to 120 °C (e.g., 30 °C to 75 °C). However, process conditions outside of these ranges are contemplated, particularly the specific design of the reactor system and the concentration of the reactants and catalyst system.

[0052] It will be appreciated that, in one or more embodiments, a similar catalyst system not including the ligand of the present application can exhibit increased fouling as compared to the catalyst system of the present application. In one or more embodiments, the inclusion of the ligand in the catalyst system can inhibit polymer formation while not greatly reducing the yield of 1-octene. In one or more embodiments, polymer formation (fouling) can be reduced by at least 5% or more by using the ligand. For example, a reaction product of ethylene tetramerization using the catalyst system can include less than 99 wt% to less than 3 wt% polymer.

[0053] In one or more embodiments, the production of 1-octene can be increased, remain the same, or can be reduced by less than or equal to 100% to 5% by including the ligand. For example, a reaction product of ethylene tetramerization using the catalyst system can include greater than 5 wt% to 100 wt% 1-octene.

[0054] In one or more embodiments, the catalyst system can reduce polymer formation by 5% to 99.9% and increase, not affect, or reduce the 1-octene productivity by less than or equal to 100% to 5%. The reduction in polymer formation rate and catalytic activity on a percentage basis is based on a catalyst system including the ligand of the present disclosure as compared to a catalyst system not including the ligand of the present disclosure.

[0055] In one or more embodiments, the catalyst system of the present disclosure can have increased activity compared to a similar catalyst system that does not comprise the ligand of the present disclosure. As used in the present disclosure, the term "activity" refers to the amount of reaction product produced per hour per amount of chromium metal used (in grams) (kg.g Cr -1 .h -1 ) in some embodiments, the catalyst system can have an activity greater than 10 kg.g Cr -1 .h -1 , or greater than 100 kg.g Cr -1 .h -1 to 5,000 kg.g Cr -1 .h -1 .

[0056] Examples

[0057] Various aspects of the present disclosure will be further clarified by the following examples. These examples are illustrative in nature and are not to be construed as limiting the subject matter of the present disclosure.

[0058] Preparation of C6H4(m-CF3)N(PPh2)2

[0059]

[0060] First, Ph2PCl (4.00 g; 18.30 mmol) was slowly added to a solution of C6H4(m-CF3)NH2(1.46 g, 9.10 mmol) and (C2H5)3N (2.54 g, 25.11 mmol) in CH2Cl2(20 mL) at 0 degrees Celsius (°C). The resulting mixture was then stirred at 0 °C for 1 hour, then warmed to room temperature and stirred for an additional 14 hours. The volatiles were then removed under reduced pressure and the remaining residue was extracted with anhydrous tetrahydrofuran (THF). The THF was then removed and the resulting solid residue was triturated with dry CH3CN and vacuum dried at 50 °C for 6 hours to yield C6H4(m-CF3)N(PPh2)2(yield 63%). It should be noted that the entire preparation was carried out under a dry argon inert atmosphere using standard Schlenk techniques.

[0061] 1 H NMR (C6D6): δ 8.03 - 6.50 (m, aromatic H) ppm; 31 P NMR (C6D6): δ 67.47 ppm (s).

[0062] Elemental microanalysis: C 31H 24 Calculated for F3NP2(%): H 4.57, C 70.32, N 2.65; Found (%): H 3.65, C 70.75, N 2.73.

[0063] Ethylene tetramerization

[0064] Multiple ethylene tetramerization reactions were performed in a stainless steel reactor system (250 ml; commercially available from Buchi) equipped with a propeller stirrer and syringes for charging solvents and reagents under magnetic stirring (1000 revolutions per minute (rpm)). The reactor system was first heated to 110 °C, purged several times with argon and ethylene to remove air and moisture, and then cooled to the desired temperature. A solution of the co-catalyst (methylaluminoxane (MAO), modified methylaluminoxane (MMAO), triisobutylaluminum (TiBA), or a combination of these) was then prepared by dilution to a total volume of 95 ml with the appropriate solvent. Next, a catalyst solution was prepared when Cr(acac)3and C6H4(m-CF3)N(PPh2)2were dissolved separately in the solvent (1 ml each) and then combined and diluted to a total volume of 5 ml. In examples where the reaction medium was cyclohexane (CyH), the solvent of the catalyst solution was toluene or chlorobenzene. The co-catalyst and catalyst solution were transferred to the reactor system, which was then pressurized to 45 bar using ethylene to initiate ethylene tetramerization. The temperature of the reactor system was kept constant during ethylene tetramerization by circulating a relatively warm oil through the jacket of the reactor system and a relatively colder liquid through the cooling coil of the reactor system as needed.

[0065] After 10 minutes, methanol (1.0 ml) was added to quench the ethylene tetramerization. The reactor system was then cooled to about 15 °C and depressurized slowly using a needle valve. Next, an aliquot of the liquid within the reaction system was collected and analyzed by gas chromatography (GC) for quantification. The remaining liquid in the reaction system was collected, added to acidic methanol (50 ml, 5% HC1), and stirred at room temperature for 2 hours. The polymer was then filtered from the mixture, washed with distilled water, and stirred in water (200 ml) for 1 hour. This process was repeated four times. Finally, the polymer was filtered and dried in a vacuum oven at 60 °C overnight.

[0066] The conditions and results for each run are shown in Table 1.

[0067] Table 1

[0068]

[0069] In a first aspect of the disclosure, a catalyst system suitable for tetramerization of ethylene to form 1-octene can include a catalyst including a chromium compound coordinated with a ligand and a co-catalyst including an organoaluminum compound. The ligand has a chemical structure of (R1)(R2)A-X-C(R3)(R4). A and C are phosphorus. X is B(R5), Si(R5)2, or N(R5), where R5 is an aryl group substituted with a halogen, a haloalkyl group, or a silyl group, and where B or N or Si is bonded to A and C. R1, R2, R3, and R4 are independently selected from a hydrocarbyl group or a heterohydrocarbyl group.

[0070] A second aspect of the disclosure can include the first aspect, where one or more of R1, R2, R3, and R4 is a substituted or unsubstituted aryl moiety.

[0071] A third aspect of the disclosure can include the first aspect or the second aspect, where the ligand has a chemical structure according to Formula (X). In Formula (X), each Ar is independently selected from a substituted or unsubstituted aryl group; R6, R7, R8, R9, and R 10 are each independently selected from hydrogen or a substituted or unsubstituted hydrocarbyl group; R6, R7, R8, R9, and R 10 one or more of R6, R7, R8, R9, and R n F 2n+1 or SiZ3, where each Z is independently selected from a substituted or unsubstituted hydrocarbyl group or a substituted or unsubstituted heterohydrocarbyl group.

[0072] A fourth aspect of the disclosure can include the third aspect, where one or more of R6, R7, R8, R9, and R 10 is a group represented by the chemical formula C n F 2n+1 .

[0073] A fifth aspect of the disclosure can include the third aspect, where one or more of R6, R7, R8, R9, and R 10 is a group represented by the chemical formula SiZ3, where each Z is independently selected from a substituted or unsubstituted hydrocarbyl group.

[0074] A sixth aspect of the disclosure can include the third aspect, where one or more of R7 and R9 is a group represented by the chemical formula C n F 2n+1 or SiZ3, where each Z is independently selected from a substituted or unsubstituted hydrocarbyl group.

[0075] A seventh aspect of the disclosure can include any one of the first aspect through the sixth aspect, where the catalyst includes the ligand in an amount such that the molar ratio of the ligand to chromium is 0.1 to 10.0.

[0076] The eighth aspect of this disclosure may include any one of the first to seventh aspects, wherein the chromium compound includes one or more of organochromium salts, inorganic chromium salts, chromium coordination compounds and chromium organometallic complexes.

[0077] The ninth aspect of this disclosure may include any one of the first to eighth aspects, wherein the chromium compound includes one or more of trichlorotris(tetrahydrofuran)chromium complex, (benzene)tricarbonylchromium, chromium octanoate (III), chromium acetylacetonate (III), hexacarbonylchromium and 2-ethylhexanoate (III).

[0078] The tenth aspect of this disclosure may include any one of the first to ninth aspects, wherein the organoaluminum compound has the structure of formula (XI). In formula (XI), R 11 R 12 and R 13 Each is selected from hydrogen atoms and (C1-C) 20 ) hydrocarbon group or (C1-C 20 ) heterohydrocarbon group.

[0079] The eleventh aspect of this disclosure may include any one of the first to tenth aspects, wherein the organoaluminum compound includes one or more of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, trihexylaluminum, tri-n-octylaluminum, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, aluminum isopropoxide, ethyl sesquichloride, methyl sesquichloride, methylaluminoxane, ethylaluminoxane, and modified methylaluminoxane.

[0080] The twelfth aspect of this disclosure may include any one of the first to eleventh aspects, wherein the amount of the co-catalyst included in the catalyst system is such that the molar ratio of aluminum to chromium is 1 to 5000.

[0081] According to the thirteenth aspect of this disclosure, a method for tetramerizing ethylene to form 1-octene may include contacting ethylene with a catalyst system of any one of the first to twelfth aspects to form a product comprising 1-octene.

[0082] The fourteenth aspect of this disclosure may include the thirteenth aspect, wherein 1-octene is formed under conditions of a reactor pressure of 5 bar to 120 bar and a reactor temperature of 25°C to 180°C.

[0083] The subject matter of this disclosure has been described in detail with reference to specific embodiments. It should be understood that any detailed description of a component or feature of an embodiment does not necessarily imply that such component or feature is necessary for a particular embodiment or any other embodiment. Furthermore, it will be apparent to those skilled in the art that various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0084] For the purposes of describing and defining the present disclosure, it is to be noted that the terms “about” or “approximately” are used herein to describe and define the inherent degree of uncertainty that can be attributed to any quantitative comparison, value, measurement, or other representation that can be subject to human and / or machine error, as well as other factors that can affect the end result. The terms “about” and / or “approximately” are also used herein when describing the degree of similarity, difference, or other relationship between two quantitative representations, as can be understood by those skilled in the art.

[0085] It is noted that one or more of the claims use the term “wherein” as a transitional phrase. For the purposes of the present technology, it is noted that this term is introduced in the claims as an open transition phrase not immediately abutted by a comma, to introduce a recitation of a series of features to be implemented or a series of steps to be performed. It is to be understood that this term is not to be interpreted as introducing a limitation, as that term is more commonly interpreted as a limitation in the art.

[0086] It is to be understood that when a first component is described as “including” a second component, it can be anticipated that, in some embodiments, the first component “consists of’ or “consists essentially of’ the second component. It is also to be understood that when a first component is described as “including” a second component, it is contemplated that, in some embodiments, the first component includes at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even at least 99% of the second component (wherein the % can be by weight or by mole) in some embodiments.

[0087] Additionally, the term “consisting essentially of’ is used in the present disclosure to refer to quantitative amounts of a specified chemical constituent or group of chemical constituents that do not materially affect the basic and novel characteristics of the present disclosure. For example, a chemical composition “consisting essentially of’ a particular chemical constituent or group of chemical constituents should be understood to mean that the composition includes at least about 99.5% of that particular chemical constituent or group of chemical constituents.

[0088] It is to be understood that any two quantitative values assigned to an attribute can constitute a range of that attribute, and the present disclosure encompasses all combinations of ranges formed by all of the specified quantitative values of a given attribute. It is to be understood that, in some embodiments, a range of composition of a chemical constituent in a composition is to be understood to encompass a mixture of isomers of that constituent. In further embodiments, a compound can exist in alternative forms, such as derivatives, salts, hydroxides, etc.

Claims

1. A catalyst system suitable for tetramerization of ethylene to form 1-octene, the catalyst system comprising: a catalyst comprising a chromium compound complexed with a ligand; and a co-catalyst comprising an organoaluminum compound, wherein: the ligand has the chemical structure: (R1)(R2)A-X-C(R3)(R4); A and C are phosphorus; X is N(R5), wherein R5 is aryl substituted at the meta position with a haloalkyl group, and wherein N is bonded to A and C; and R1, R2, R3, and R4 are independently selected from hydrocarbyl or heterohydrocarbyl.

2. The catalyst system of claim 1, wherein one or more of R1, R2, R3, and R4 is a substituted or unsubstituted aryl moiety.

3. The catalyst system of claim 1, wherein the ligand has the chemical structure: wherein: each Ar is independently selected from substituted or unsubstituted aryl; 4. The catalyst system of claim 1 or claim 3, wherein the catalyst comprises the ligand in an amount such that the molar ratio of the ligand to chromium is 0.1 to 10.

0. R6, R7, R8, R9, and R 10 each independently is selected from hydrogen or substituted or unsubstituted hydrocarbyl; and one or more of R7and R9is a group of the formula n F 2n+1 C 5. The catalyst system of claim 1 or claim 3, wherein the chromium compound comprises an organochromium salt, an inorganic chromium salt, a chromium complexing compound, a chromium organometallic complex, or a combination of these.

6. The catalyst system of claim 1 or claim 3, wherein the chromium compound comprises one or more of trichlorotri(tetrahydrofuran)chromium complex, (benzene)tricarbonylchromium, chromium (III) octoate, chromium (III) acetylacetonate, chromium hexacarbonyl, and chromium (III) 2-ethylhexanoate.

7. The catalyst system of claim 1 or claim 3, wherein the organoaluminum compound has the structure:

8. The catalyst system of claim 1 or claim 3, wherein the organoaluminum compound comprises one or more of trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, trihexylaluminum, tri-n-octylaluminum, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, aluminum isopropoxide, ethylaluminum sesquichloride, methylaluminum sesquichloride, methylaluminoxane, ethylaluminoxane, and modified methylaluminoxane. wherein R 11 , R 12 and R 13 are each selected from a hydrogen atom and a C1-C 20 hydrocarbon group or a C1-C 20 heterohydrocarbon group.

9. The catalyst system of claim 1 or claim 3, wherein the catalyst system comprises the co-catalyst in an amount such that the molar ratio of aluminum to chromium is 1 to 5000.

10. A method for tetramerization of ethylene to form 1-octene, the method comprising contacting ethylene with the catalyst system of any one of claims 1-9 to form a product comprising 1-octene.

11. The method of claim 10, wherein the 1-octene is formed under the following conditions: a reactor pressure of 5 bar to 120 bar; and a reactor temperature of 25 °C to 180 °C. ​

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