Catalyst composition for oligomerization reaction

Abstract

The present disclosure provides a catalyst reaction mixture comprising a ligand having a backbone with at least one phosphorus atom and at least one nitrogen atom, a chromium compound, and a solvent mixture comprising decalin and at least one additional solvent, wherein the solvent mixture comprises decalin in an amount of less than 20 wt.%, and optionally, perhydroindane in an amount of 50 wt.% or less, based on the total weight of the solvent mixture. Also provided are methods of forming linear alpha olefins by ethylene oligomerization, the methods comprising: contacting ethylene gas with a reaction mixture in a reactor, the reaction mixture comprising a catalyst reaction mixture of the present disclosure; and withdrawing a product stream from the reactor, the product stream comprising at least one linear alpha-olefin, such as 1-butene, 1-hexene, or 1-octene.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to processes for forming linear alpha olefins by the oligomerization of ethylene, and catalyst compositions for use in such processes. BACKGROUND

[0002] Linear olefins are a class of hydrocarbons that can be used as feedstocks in the petrochemical industry, with linear alpha olefins, which are unbranched olefins with the double bond at the end of the chain, forming an important sub-class. Linear alpha olefins can be converted to linear primary alcohols by hydroformylation. Hydroformylation can also be used to make aldehydes, which can be oxidized to provide synthetic fatty acids, especially those with odd carbon numbers, which can be used to produce lubricants. Linear alpha olefins are also used to produce detergents, such as linear alkyl benzene sulfonates, which are made by Fiedel-Crafts reaction of benzene with linear olefins, followed by sulfonation. Another important use of linear alpha olefins involves the production of linear low density polyethylene (LLDPE) by catalytic copolymerization with ethylene.

[0003] The production of alpha olefins is largely based on the oligomerization of ethylene, which has the corollary that the resulting alpha olefins have an even number of carbon atoms. The oligomerization process uses a variety of different catalyst systems. In certain embodiments, the catalyst system comprises a chromium compound and a ligand having phosphorus and nitrogen atoms in its backbone, such as the catalyst compositions set forth in US 2017 / 0203288 to Al-Hazmi et al.

[0004] One of the major challenges of the oligomerization process is the formation of undesired polymers, which leads to fouling in the reactor, which requires periodic flushing or tedious mechanical cleaning for removal. The traditional way to increase catalyst activity is to increase the reaction temperature or to increase the amount of promoter used in the process. Both ways not only lead to a larger amount of the target oligomer, but also increase the amount of polymer formed during the reaction. Increasing the amount of promoter also significantly increases the cost of the process, since the promoter is typically expensive. There remains a need in the art to improve catalyst activity in the oligomerization reaction without significantly increasing polymer formation. SUMMARY

[0005] Exemplary embodiments of the present disclosure relate to processes for forming linear alpha olefins by the oligomerization of ethylene, and catalyst compositions for use in such processes, wherein the catalyst is combined with a solvent mixture that includes a relatively small amount of decalin. It has been unexpectedly found that the presence of a small amount of decalin can enhance catalyst activity without significantly increasing polymer formation or significantly losing selectivity to the target oligomer.

[0006] The present disclosure includes, but is not limited to, the following embodiments.

[0007] Embodiment 1 : A catalyst reaction mixture comprising a ligand having a backbone with at least one phosphorus atom and at least one nitrogen atom, a chromium compound, and a solvent mixture comprising decalin and at least one additional solvent, wherein the solvent mixture comprises decalin in an amount of less than 20 wt.%, such as about 5 to 20 wt.%, and optionally, perhydroindane in an amount of 50 wt.% or less, based on the total weight of the solvent mixture.

[0008] Embodiment 2: The catalyst reaction mixture of embodiment 1, wherein the decalin is present in an amount of about 15 wt.% or less, based on the total weight of the solvent mixture, such as about 5 to about 15 wt.%, or about 8 to about 12 wt.%.

[0009] Embodiment 3: The catalyst reaction mixture of embodiment 1 or 2, wherein the at least one additional solvent is selected from the group consisting of saturated or unsaturated, linear or branched hydrocarbons, ethers, aromatic hydrocarbons, which can be unsubstituted, or substituted with halogen, haloalkanes, and combinations thereof, such as toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

[0010] Embodiment 4: The catalyst reaction mixture of any one of embodiments 1 to 3, wherein the ligand has the structure: PNP, PNPN, PNNP, PNPNP, or NPNPN, wherein each P is a substituted phosphino group, and each N is a substituted amino group, such as wherein the ligand has at least two nitrogen atoms in its backbone, such as wherein the ligand has the structure: (R 1 )(R 2 )N—P(R 3 )—N(R 4 )—P(R 5 )—N(R 6 )(R 7 ), wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , each R 7 may each independently be hydrogen, optionally substituted amino, trialkylsilyl, or optionally substituted C1-C 20 alkyl, such as wherein R 4 is C1-C4 alkyl, R 3 and R 5 are each independently selected from C6-C20 aryl, or C3-C7 aliphatic, which can be cyclic or acyclic, linear or branched, substituted or unsubstituted, and R 1 , R 2 , R 6 , and R 7 are each independently selected from the group consisting of C1-C 10 alkyl, such as C1-C5 alkyl.

[0011] Embodiment 5: The catalyst reaction mixture of any one of embodiments 1 to 4, wherein the ligand has the structure:

[0012]

[0013] wherein R1and R2are independently cyclohexyl or phenyl, optionally substituted with one or more C1-C10 alkyl, such as C1-C5 alkyl, and R3is C1-C4 alkyl.

[0014] Embodiment 6: The catalyst reaction mixture of any one of embodiments 1 to 5, wherein the chromium compound is an organometallic complex of Cr(III), such as acetylacetone Cr(III), octanoate Cr(III), Cr(III)Cl3(tetrahydrofuran)3, 2-ethylhexanoate Cr(III), Cr(III) chloride, naphthenate Cr(III), tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Cr(III), or a combination thereof.

[0015] Embodiment 7: The catalyst reaction mixture of any one of embodiments 1 to 6, further comprising a co-catalyst comprising an aluminum compound, such as: trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxane, modified methylaluminoxane, or a combination thereof.

[0016] Embodiment 8: The catalyst reaction mixture of any one of embodiments 1 to 7, further comprising ethylene and at least one linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene.

[0017] Embodiment 9: A process for forming linear alpha olefins by ethylene oligomerization, the process comprising: contacting ethylene gas with a reaction mixture in a reactor, the reaction mixture comprising a ligand having a backbone with at least one phosphorus atom and at least one nitrogen atom, a chromium compound, and a solvent mixture comprising decalin and at least one additional solvent, wherein the solvent mixture comprises decalin in an amount of less than 20 wt.%, such as about 5 to 20 wt.%, and optionally, perhydroindane in an amount of 50 wt.% or less, based on the total weight of the solvent mixture; and withdrawing a product stream from the reactor, the product stream comprising at least one linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene.

[0018] Embodiment 10: The process of embodiment 9, wherein the decalin is present in an amount of about 15 wt.% or less, based on the total weight of the solvent mixture, such as about 5 to about 15 wt.%, or about 8 to about 12 wt.%.

[0019] Embodiment 11: The process of embodiments 9 or 10, wherein the at least one additional solvent is selected from the group consisting of saturated or unsaturated, linear or branched hydrocarbons, ethers, aromatic hydrocarbons, which can be unsubstituted, or substituted with halogen, haloalkanes, and combinations thereof, such as toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

[0020] Embodiment 12: The process of any one of embodiments 9 to 11, wherein the ligand has the structure: PNP, PNPN, PNNP, PNPNP, or NPNPN, wherein each P is a substituted phosphino group, and each N is a substituted amino group, such as wherein the ligand has at least two nitrogen atoms in its backbone, such as wherein the ligand has the structure: (R 1 )(R 2 )N—P(R 3 )—N(R 4 )—P(R 5 )—N(R 6 )(R 7 ), wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , each R 7 may each independently be hydrogen, optionally substituted amino, trialkylsilyl, or optionally substituted C1-C 20 alkyl, such as wherein R 4R is C1-C4alkyl, R 3 and R 5 each independently is selected from C6-C 20 aryl, or C3-C7aliphatic, which can be cyclic or acyclic, linear or branched, substituted or unsubstituted, and R 1 , R 2 , R 6 , and R 7 each independently is selected from C1-C 10 alkyl, such as C1-C5alkyl.

[0021] Embodiment 13: The method of any one of embodiments 9 to 12, wherein the ligand has the structure:

[0022]

[0023] wherein R1and R2are independently cyclohexyl or phenyl, optionally substituted with one or more C1-C10alkyl, such as C1-C5alkyl, and R3is C1-C4alkyl.

[0024] Embodiment 14: The method of any one of embodiments 9 to 13, wherein the chromium compound is an organometallic complex of Cr(III), such as acetylacetone Cr(III), Cr(III) octoate, Cr(III) Cl3(tetrahydrofuran)3, Cr(III) 2-ethylhexanoate, Cr(III) chloride, Cr(III) naphthenate, tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Cr(III), or a combination thereof.

[0025] Embodiment 15: The method of any one of embodiments 9 to 14, the catalyst reaction mixture further comprises a co-catalyst comprising an aluminum compound, such as: trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum seschloride, ethylaluminum dichloride, methylaluminoxane, modified methylaluminoxane, or a combination thereof.

[0026] Embodiment 16: The method of any one of embodiments 9 to 15, wherein the polymer content of the product stream is about 0.9 wt% or less, based on the total weight of the product stream.

[0027] These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following detailed description when considered in connection with the accompanying drawings. The present disclosure includes any combination of two, three, four, or more of the features or elements set forth in the disclosure, whether explicitly described or not, whether in a specific example implementation or not. The present disclosure is intended to be understood in its broadest sense, such that any separable feature or element of the present disclosure, in any aspect and example implementation thereof, should be considered to be combinable with any other separable feature or element of the present disclosure, unless the context clearly dictates otherwise.

[0028] Accordingly, it will be appreciated that a brief summary of the disclosure is provided to convey the essence of some example implementations. It will be understood that the above-mentioned example implementations are merely examples and should not be construed as limiting the scope or spirit of the disclosure in any way. Other example implementations, aspects, and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings which illustrate, by way of example, the principles of some described example implementations. BRIEF DESCRIPTION OF DRAWINGS

[0029] Having described above in general terms the aspects of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, in which:

[0030] Figure 1 is a simplified schematic diagram of an example ethylene oligomerization reactor in accordance with the present disclosure. DETAILED DESCRIPTION

[0031] Some implementations of the present disclosure will now be described to follow, by reference to which some but not all implementations of this disclosure will be elucidated, in which:

[0032] Unless otherwise stated or clear from context, reference to first, second, etc. should not be construed as implying a particular order. A feature described as being above another feature (unless otherwise stated or clear from context) can alternatively be below the other feature, and vice versa; similarly, a feature described as being to the left of another feature can be to the right, and vice versa. Furthermore, although quantitative measurements, values, geometric relationships, etc. can be referenced herein, unless otherwise stated, any one or more of these, if not all, can be absolute or approximate, to account for acceptable variations that can occur, e.g., due to engineering tolerances, etc.

[0033] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with (e.g., the range of “up to 25 weight %, or more specifically 5 to 20 weight %,” is inclusive of the endpoints and all intermediate values of the ranges of “5 to 25 weight %,” etc.). “Combination” is inclusive of blends, mixtures, alloys, reaction products, or the like.

[0034] As used herein, unless otherwise defined or clear from context, “or” in a set of operands is an “inclusive or,” so that it is true whenever one or more of the operands is true, and an “exclusive or” is the opposite, false when all operands are true. Thus, for example, “[A] or [B]” is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Also, unless otherwise defined or clear from context, the terms “a” and “an” mean “one or more.”

[0035] The following includes definitions of various terms and phrases used throughout this specification.

[0036] The term “hydrocarbyl” refers to any monovalent radical derived from a hydrocarbon, such as any aliphatic radical (e.g., an alkyl radical such as methyl, or a cycloalkyl radical such as cyclohexyl), or any aromatic radical (e.g., phenyl).

[0037] The term “aliphatic” means an organic functional group or compound that contains carbon and hydrogen atoms connected together in a branched, branched, or non-aromatic ring structure.

[0038] The term “alkyl” refers to linear or branched saturated hydrocarbons. Non-limiting examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and the like.

[0039] The term "aryl" group or "aromatic" group is a substituted or substituted, monocyclic or polycyclic hydrocarbon in which single and double bonds alternate in each ring structure, such as a phenyl group. Non-limiting examples of aryl group substituents include: alkyl, substituted alkyl, linear or branched alkyl, linear or branched unsaturated hydrocarbon, halogen, hydroxyl, alkoxy, haloalkyl, haloalkoxy, carboxylic acid, ester, amine, nitro, amide, nitrile, acyl, alkylsilane, thiol, and thioether substituents. Non-limiting examples of alkyl groups include linear and branched C1to C5hydrocarbons. Non-limiting examples of unsaturated hydrocarbons include C2to C5hydrocarbons containing at least one double bond (e.g., vinyl). The aryl or alkyl groups can be substituted with halogen, hydroxyl, alkoxy, haloalkyl, haloalkoxy, carboxylic acid, ester, ether, amine, nitro (-NO2), amide, nitrile (-CN), acyl, alkylsilane, thiol, and thioether substituents. Non-limiting examples of polycyclic groups include ring systems comprising 2 or more conjugated rings (e.g., fused aromatic rings) and substituted conjugated rings.

[0040] A "cyclohexyl" group is a substituted or unsubstituted cyclic hydrocarbon group containing 6 carbon atoms. When completely saturated with hydrogens and having the formula C6H 11 , the cyclohexyl group is an unsubstituted cyclohexyl group. When at least one of the hydrogens is replaced with another atom or functional group, the cyclohexyl group is a substituted cyclohexyl.

[0041] Ethylene oligomerization process

[0042] Linear alpha olefins (LAOs) are olefins of the chemical formula C x H 2x that differ from other formulaically similar mono-olefins in that the hydrocarbon chain is linear, and the double bond is in the 1 -position or alpha position. Linear alpha olefins include industrially important alpha-olefin types including 1 -butene, 1 -hexene, 1 -octene, 1 -decene, 1 -dodecene, 1 -tetradecene, 1 -hexadecene, 1 -octadecene, as well as higher order blends of C 20 -C 24 , C 24 -C 30 , and C 20 -C 30 olefins. Linear alpha olefins are useful intermediates in the manufacture of detergents, synthetic lubricants, copolymers, plasticizers, and a variety of other important products.

[0043] Existing processes to produce linear alpha olefins typically rely on the oligomerization of ethylene. For example, linear alpha olefins can be prepared by catalytically oligomerizing ethylene in the presence of various catalyst systems.

[0044] The catalyst compositions disclosed herein typically include ligands, chromium compounds, and co-catalysts, wherein the ligands have a skeleton having at least one phosphorus atom and at least one nitrogen atom.

[0045] A typical ligand structure is an organophosphorus compound having two phosphino groups covalently linked by a linker. Exemplary ligands include compounds having any of the following skeleton structures: PNP, PNPN, PNNP, PNPNP, or NPNPN, wherein each P is a substituted phosphino group (typically secondary or tertiary phosphino), and each N is a substituted amino group (typically secondary or tertiary amino), wherein exemplary substituents for the phosphino and amino groups include: optionally substituted amino, trialkylsilyl, or optionally substituted C1-C20 hydrocarbon groups (e.g., optionally substituted phenyl or optionally substituted cyclohexyl), wherein the optional substituents typically include amino or C1-C20 hydrocarbon groups. In some embodiments, the ligand skeleton structure includes at least two N atoms (e.g., PNPN, PNNP, PNPNP, or NPNPN).

[0046] In some embodiments, the ligand has an NPNPN structure, such as the ligand of formula I: (R 1 (R) 2 )N—P(R 3 )—N(R 4 )—P(R 5 )—N(R 6 (R) 7 ),

[0047] Where R 1 R 2 R 3 R 4 R 5 R 6 and R 7 Each of these components can be independently hydrogen, an optionally substituted amino group, a trialkylsilyl group (e.g., trimethylsilyl or triethylsilyl), or an optionally substituted C1-C group. 20 Hydrocarbon group. C1-C 20 Examples of hydrocarbon groups include straight-chain or branched C1-C. 10 Alkyl, C3-C7 cycloalkyl (e.g., cyclohexyl), C6-C 20 Aryl (e.g., phenyl), and C6-C 20 Alkyl-substituted C6-C 20 Aryl. In some embodiments, each R 1 R 2 R 3 R 4 R 5 R 6 and R7 Independently, it is hydrogen, methyl, ethyl, isopropyl, tert-butyl, n-hexyl, cyclohexyl, or phenyl. In some embodiments, R 4 For methyl, R 3 and R 5 Each is independently selected from: C6-C 20 The aryl group (e.g., phenyl) or C3-C7 aliphatic group (e.g., cyclohexyl), which may be cyclic or acyclic, linear or branched, substituted or unsubstituted, and R 1 R 2 R 6 and R 7 Each is independently selected from C1-C 10 Alkyl groups (e.g., C1-C5 alkyl groups).

[0048] In some embodiments of the above NPNPN formula, R 3 and R 5 Each is independently: a cyclic hydrocarbon group, a substituted cyclic hydrocarbon group, a linear hydrocarbon group, or a branched hydrocarbon group having 1 to 10 carbon atoms, including isopropyl, tert-butyl, and substituted or unsubstituted cycloalkyl groups, including cyclopentyl, cyclohexyl, cycloheptyl, substituted cyclopentyl, substituted cyclohexyl, and substituted cycloheptyl. In another embodiment, R 3 and R 5 Each independently refers to an aromatic group or a substituted aromatic group, such as a phenyl group, a substituted phenyl group, or an aromatic group comprising two or more conjugated rings.

[0049] A subset of the ligands of formula I is shown below as formula Ia:

[0050]

[0051] R1 and R2 are independently cyclohexyl or phenyl, which are optionally substituted with one or more C1-C10 alkyl groups such as C1-C5 alkyl groups, and R3 is a C1-C4 alkyl group (e.g., methyl, ethyl, isopropyl, or butyl).

[0052] Table 1 below includes specific examples of ligands applicable to this disclosure:

[0053] Table 1

[0054]

[0055]

[0056] Optionally, the ligand can be a cyclic derivative in which at least one of the P or N atoms of the ligand is a constituting atom of a ring system, or any cyclic derivative thereof in which at least one of the P or N atoms of the NPNPN ligand is a constituting atom of a ring system. The ring system can be formed from one or more of the constituent compounds of the NPNPN ligand by substitution, for example by formally eliminating two complete groups R1-R7 (as defined herein) from each constituent compound, one atom from each of two groups R1-R7 (as defined herein), or one complete group R1-R7 (as defined herein) and one atom from another group R1-R7 (as defined), and each constituent compound adding to the formally so created site of valence unsaturation by one covalent bond, thereby providing the same valence as originally present at the given site.

[0057] The ligands used in the present disclosure can be prepared by synthetic methods known to those skilled in the art, for example, the synthetic methods set forth in US 2010 / 0190939 to Fritz et al.; US 2016 / 0167033 to Woehl et al.; US 2017 / 0203288 to Al-Hazmi et al.; WO 2020 / 100007 to Al-Nezari et al.; WO 2020 / 100010 to Al-Nezari et al.; Peulecke et al. Dalton Trans., 2016, 45, 8869, each of which is incorporated herein by reference.

[0058] The chromium compound is an organic salt, an inorganic salt, a coordination complex, or an organometallic complex of Cr(II) or Cr(III). In certain embodiments, the chromium compound is an organometallic complex, preferably an organometallic complex of Cr(II) or Cr(III). Examples of the chromium compound include: acetylacetone Cr(III), caprylic acid Cr(III), Cr(III) Cl3(tetrahydrofuran)3, 2-ethylhexanoic acid Cr(III), chlorinated Cr(III), naphthenic acid Cr(III), and tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Cr(III). A combination comprising at least one of the foregoing chromium compounds can be used.

[0059] The concentration of the chromium compound can vary depending on the particular compound used and the desired rate of reaction. In some embodiments, the concentration of the chromium compound is about 0.01 to about 100 millimoles per liter (mmol / 1), about 0.01 to about 10 mmol / 1, about 0.01 to about 1 mmol / 1, about 0.1 to about 100 mmol / 1, about 0.1 to about 10 mmol / 1, about 1 to about 10 mmol / 1, and about 1 to about 100 mmol / 1. In one embodiment, the concentration of the chromium compound is about 0.1 to about 1.0 mmol / 1.

[0060] The activator (also known in the art as a co-catalyst) is typically an aluminum compound, such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxane, or modified methylaluminoxane. Combinations of different aluminum compounds can be used.

[0061] In some embodiments, the activator is a modified methylaluminoxane ("MMAO"), which refers to a methylaluminoxane containing an alkyl substituent derived from a C2or higher alkyl ligand in addition to the methyl ligands, which is typically the result of, for example, the reaction of a tetraalkyldialuminoxane and / or a polyalkylaluminoxane reagent with trimethylaluminum during the preparation of the MMAO. One exemplary MMAO is MMAO-3A (CAS No. 146905-79-5), which is a 3A-type modified methylaluminoxane, available from Akzo Nobel as a toluene solution containing 7% aluminum, corresponding to a concentration of about 18% MMAO-3A.

[0062] The ligand / Cr molar ratio can be about 0.5 to 50, about 0.5 to 5, about 0.8 to about 2.0, about 1.0 to 5.0, or about 1.0 to about 1.5.

[0063] The Al / Cr molar ratio can be about 1 to about 1000, about 10 to about 1000, about 1 to 500, about 10 to 500, about 10 to about 300, about 20 to about 300, or 50 to about 300.

[0064] The catalyst compositions disclosed herein can be used in a process for the oligomerization of ethylene. In one embodiment, the process comprises contacting ethylene with the catalyst composition under ethylene oligomerization conditions effective to produce a target linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene. It will be appreciated that other olefins, including branched olefins, can be produced as byproducts in this reaction.

[0065] The ethylene oligomerization can be conducted at a pressure of from about 1 to about 200 bar, from about 10 to about 200 bar, from about 10 to about 100 bar, from about 20 to about 70 bar, and from about 10 to 50 bar. In certain embodiments, the oligomerization is conducted at a pressure of from about 20 to about 70 bar.

[0066] The ethylene oligomerization can also be conducted at a temperature of from about 10 to about 200 °C, from about 20 to about 100 °C, from about 30 to about 100 °C, from about 40 to about 100 °C, from about 40 to about 80 °C, or from about 40 to about 70 °C.

[0067] The oligomerization process can be conducted in a continuous manner, a semi-continuous manner, or a batch manner. In one embodiment, the process can be continuous, and the average residence time can be from 10 minutes to 20 hours, such as from 30 minutes to 4 hours, or from 1 to 2 hours. The residence time can be selected so that the desired conversion is achieved with high selectivity.

[0068] The process can be conducted in solution using an inert solvent mixture, which advantageously is not reactive with the catalyst composition. The solvent mixture includes decalin and at least one additional solvent. Decalin (i.e., decahydronaphthalene, also known as bicyclo[4.4.0]decane) is a bicyclic organic compound, the structure of which is shown below:

[0069]

[0070] The additional solvent used with decalin can include, but is not limited to, saturated or unsaturated linear or branched hydrocarbons, ethers, aromatic hydrocarbons, which can be unsubstituted or substituted with halogen, haloalkanes, and combinations thereof. Specific examples include toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

[0071] It has been unexpectedly found that the use of decalin as a minor component of the solvent mixture, in combination with the catalyst system of the present disclosure, results in an enhancement of catalyst activity without a significant loss of oligomer selectivity or a significant increase in polymer formation. In particular, it is advantageous to use decalin in an amount of less than 20 wt% based on the total weight of the solvent mixture. In one embodiment, the content of decalin is about 5 to 20 wt% based on the total weight of the solvent mixture. In certain embodiments, the content of the decalin is about 15 wt% or less, based on the total weight of the solvent mixture, such as about 5 to about 15 wt%, or about 8 to about 12 wt%. The remainder of the solvent mixture can include one or more additional solvents, such as those set forth above. Since decalin has a high boiling point, there is no additional difficulty in isolating the target product by distillation using decalin.

[0072] In certain embodiments, the solvent mixture is substantially free of or completely free of perhydroindan or contains a relatively small amount of perhydroindan. For example, the solvent mixture can be characterized as containing about 50 wt% or less of perhydroindan, such as about 40 wt% or less, or about 30 wt% or less, or about 20% or less. In certain embodiments, the content of perhydroindan is about 10 wt% or less, or about 5 wt% or less, or about 2.5 wt% or less, or about 1 wt% or less. An exemplary range of perhydroindan is 0.0 wt% to about 50 wt%, or about 0.0 wt% to about 25 wt%. In certain embodiments, the solvent mixture does not contain detectable perhydroindan.

[0073] In certain embodiments, the use of the solvent mixture of the present disclosure can improve catalyst activity, as determined by the consumption of ethylene per unit weight of chromium compound during a reaction time of 1 hour, using the unit of kg ethylene / g Cr. In some embodiments, the catalyst activity can be greater than 128 kg / g Cr, such as greater than 130 kg / g Cr, greater than 132 kg / g Cr, greater than 134 kg / g Cr, greater than 136 kg / g Cr, greater than 138 kg / g Cr, greater than 140 kg / g Cr, greater than 142 kg / g Cr, greater than 144 kg / g Cr, greater than 146 kg / g Cr, greater than 148 kg / g Cr, or greater than 150 kg / g Cr. Cr *h. In some embodiments, the catalyst activity can be greater than 128 kg / g Cr *h, such as greater than 130 kg / g Cr *h, greater than 132 kg / g Cr *h, greater than 134 kg / g Cr *h, greater than 136 kg / g Cr *h, greater than 138 kg / g Cr *h, or greater than 140 kg / g Cr *h (e.g., about 128 to about 150 kg / g Cr *h, or about 130 to about 145 kg / g Cr *h).

[0074] In certain embodiments, the use of the solvent mixture of the present disclosure significantly improves catalyst activity while at the same time maintaining olefin selectivity without increasing undesirable polymer formation. For example, the polymer content in the product stream can be about 0.9 wt% or less, about 0.8 wt% or less, about 0.7 wt% or less, about 0.6 wt% or less, about 0.5 wt% or less, or about 0.4 wt% or less (e.g., about 0.3 wt% to about 0.9 wt%, or about 0.3 wt% to about 0.7 wt%, or about 0.3 wt% to about 0.5 wt%) based on the total weight of the product stream. Undesirable polymer species is defined as polymer species having a molecular weight of at least 650 Da, and typically includes species that are not soluble in the reactor medium and need to be removed by filtration or otherwise.

[0075] The process can be carried out in any reactor, such as a loop reactor, a plug-flow reactor, or a bubble column reactor. The oligomerization of ethylene is an exothermic reaction, which can be cooled by excess ethylene flow. The gas leaving the top section of the reactor can be cooled using a series of external coolers and condensers. After further cooling, the gas phase can be recycled.

[0076] The bottoms stream leaving the oligomerization reactor from the bottom section can contain active catalyst and unreacted ethylene. The reaction can be terminated by removing the catalyst components from the organic phase by extraction with a caustic water phase in order to avoid undesirable side reactions. Contact with the caustic water phase can result in the formation of non-reactive minerals corresponding to the catalyst components.

[0077] After passing through the catalyst removal system, the organic phase can pass through a molecular sieve adsorption bed, and can then be fed to a distillation column in order to recover the dissolved ethylene. The recovered ethylene can be recycled via an ethylene recycle loop, while the product is fed to an intermediate vessel, after which the product can be fed to a separation train. In certain embodiments, the linear alpha olefins produced by the reactor can be directed to a separation train.

[0078] Bubble column reactor

[0079] In one embodiment, the oligomerization process can be carried out in a bubble column reactor. Figure 1An exemplary bubble column reactor 24 used in the present disclosure is depicted. Ethylene can be introduced to the reactor 24 via a gas distribution system attached to the bottom portion of the bubble column reactor, typically comprising one or both of a gas sparging tray 30 and spargers 32, using a feed stream 26. The gas distribution system disperses gaseous ethylene uniformly throughout the reactor 24. The gaseous ethylene rises through a liquid composition 40 within the reactor 24, which typically comprises linear alpha olefins and reaction byproducts, the solvent mixture described herein, and a catalyst composition. For example, the catalyst can enter the reactor 24 through a catalyst injection stream 42. The solvent can enter the reactor 24 through a solvent injection stream 44. As the gaseous ethylene interacts with the liquid composition, oligomerization reactions can occur, producing reaction products that can include polymer droplets and linear alpha olefin droplets.

[0080] Liquid heavy linear alpha olefins, as well as solvent and catalyst, can be withdrawn from the bottom portion of the reactor 24 via a bottom effluent stream 34. A portion of the linear alpha olefins formed, which are gaseous under the reaction conditions, can be cooled at the top of the reactor using an internal condenser 36 and can serve as reflux for cooling purposes using the respective heat of vaporization. Gaseous ethylene and light linear alpha olefins can be removed at the top of the bubble column reactor via a top effluent stream 38. One or both of the effluent streams can be further processed using additional downstream processing units, such as condensers, heat exchangers, distillation columns, and the like.

[0081] Experiment

[0082] Catalyst performance in the presence of various different solvent compositions was evaluated by ethylene oligomerization reactions performed in a stainless steel pressure reactor at 45°C. In each solvent set, anhydrous n-heptane and decalin were used, MMAO-3A was used as cocatalyst, and acetylacetone Cr(III) was used as chromium compound. The ligand of formula la was used, wherein R1and R2are phenyl, and R3is methyl.

[0083] The results are summarized in Table 2 below. The product distribution was evaluated by GC-MS analysis, while the activity of the catalyst activity was calculated based on the ethylene consumption during 1 hour reaction time. The table provides the yield of 1-hexene (out of all C6) as well as the weight% of 1-hexene out of all isolated C6 olefins. For 1-octene, the same information is provided. Also provided is the amount of polymer formed.

[0084] Table 2

[0085]

[0086]

[0087] As shown in Table 2, use of solvent mixtures containing small amounts (such as 5-20 wt%) of decalin can improve catalyst activity compared to the use of n-heptane alone. Alternatively, the above data show that the addition of decalin allows for a reduction in the catalyst to promoter ratio while retaining the same catalyst performance characteristics. The presence of small amounts of decalin does not adversely affect the reaction selectivity to the desired oligomers (such as C6 or C8 oligomers) and does not significantly increase polymer formation. In fact, polymer formation is reduced with 5-15 wt% decalin compared to the case of n-heptane alone. The use of decalin as the only solvent results in significantly reduced catalyst activity and increased polymer formation compared to the use of n-heptane alone.

[0088] While not wishing to be bound by theory, these experimental results can be explained as follows: the increased ethylene solubility in the reaction solvent allows ethylene to be more readily available to the activated catalyst. Activation of the chromium species by the alkyl aluminum promoter results in the formation of a species with very high reactivity. If ethylene is not readily available in solution, such a species will decompose, forming different chromium compounds. Such compounds improve the polymerization rather than the oligomerization activity.

[0089] However, the addition of larger amounts of decalin to the reaction mixture appears to adversely affect catalyst performance, reducing the overall catalyst activity. This can be explained in the following way: when the decalin concentration exceeds a certain percentage, the solubility of the active catalytic species in the reaction solvent decreases. The increased solvent viscosity with increasing amounts of decalin addition also results in limited ethylene mass transfer, leading to reduced catalytic activity.

[0090] In general, the present application can alternatively comprise, consist of, or consist essentially of, any appropriate components disclosed herein. The present disclosure can additionally, or alternatively, be formulated so as to be devoid of, or substantially free of, any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise unnecessary.

[0091] Many modifications and other embodiments of the present disclosure set forth herein will come to mind. Therefore, it is to be understood that the disclosure is not limited to the specific embodiments disclosed herein and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A catalyst reaction mixture comprising a ligand, a chromium compound, and a solvent mixture, wherein the ligand has a skeleton having at least one phosphorus atom and at least one nitrogen atom, and the solvent mixture comprises decahydronaphthalene and at least one other solvent, wherein the solvent mixture contains decahydronaphthalene in an amount of 5 to 20% by weight, based on the total weight of the solvent mixture.

2. The catalyst reaction mixture of claim 1, wherein the content of decahydronaphthalene is 15% by weight or less, based on the total weight of the solvent mixture.

3. The catalyst reaction mixture of claim 2, wherein the content of decahydronaphthalene is 5 to 15% by weight, based on the total weight of the solvent mixture.

4. The catalyst reaction mixture of claim 3, wherein the content of decahydronaphthalene is 8 to 12% by weight, based on the total weight of the solvent mixture.

5. The catalyst reaction mixture of claim 1, wherein the at least one additional solvent is selected from: saturated or unsaturated, linear or branched hydrocarbons, ethers, aromatic hydrocarbons, wherein the hydrocarbons, ethers, aromatic hydrocarbons may be unsubstituted or substituted by halogens, haloalkanes, or combinations thereof.

6. The catalyst reaction mixture of claim 5, wherein the at least one additional solvent is selected from: toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

7. The catalyst reaction mixture of any one of claims 1 to 6, wherein the solvent mixture contains 50% by weight or less of perhydroindene, based on the total weight of the solvent mixture.

8. The catalyst reaction mixture of claim 7, wherein the solvent mixture does not contain detectable perhydroindene.

9. The catalyst reaction mixture according to any one of claims 1 to 8, wherein the ligand has the following structure: PNP, PNPN, PNNP, PNPNP, or NPNPN, wherein each P is a substituted phosphine group and each N is a substituted amino group.

10. The catalyst reaction mixture of claim 9, wherein the ligand has at least two nitrogen atoms in its framework.

11. The catalyst reaction mixture of claim 9, wherein the ligand has the following structure: (R 1 (R) 2 )N—P(R 3 )—N(R 4 )—P(R 5 )—N(R 6 (R) 7 ), where R 1 R 2 R 3 R 4 R 5 R 6 Each R 7 Each can be independently hydrogen, unsubstituted or substituted amino, trialkylsilyl, or unsubstituted or substituted C1-C. 20 Hydrocarbon group, wherein the substituted amino group or the substituted C1-C group 20 Substituents on the hydrocarbon group include amino or C1-C. 20 Hydrocarbon group.

12. The catalyst reaction mixture of claim 11, wherein R 4 It is a C1-C4 alkyl group, R 3 and R 5 Each is independently selected from C6-C 20 Aryl or C3-C7 aliphatic group, which may be cyclic or acyclic, linear or branched, and R 1 R 2 R 6 and R 7 Each is independently selected from C1-C 10 alkyl.

13. The catalyst reaction mixture of claim 12, wherein R 1 R 2 R 6 and R 7 Each is independently selected from C1-C5 alkyl groups.

14. The catalyst reaction mixture according to any one of claims 1 to 8, wherein the ligand has the following structure: R1 and R2 are independently cyclohexyl or phenyl, which are unsubstituted or converted by one or more C1-C2 groups. 10 Alkyl substitution, and R3 is a C1-C4 alkyl group.

15. The catalyst reaction mixture of claim 14, wherein R1 and R2 are independently cyclohexyl or phenyl, which are unsubstituted or substituted by one or more C1-C5 alkyl groups.

16. The catalyst reaction mixture according to any one of claims 1 to 8, wherein the chromium compound is an organometallic complex of Cr(III).

17. The catalyst reaction mixture of claim 16, wherein the chromium compound is selected from: acetylacetone Cr(III), octanoic acid Cr(III), Cr(III)Cl3 (tetrahydrofuran)3, 2-ethylhexanoic acid Cr(III), chlorinated Cr(III), naphthenic acid Cr(III), tris(2,2,6,6-tetramethyl-3,5-heptadecanoic acid) Cr(III), or combinations thereof.

18. The catalyst reaction mixture according to any one of claims 1 to 8, wherein the catalyst reaction mixture further comprises a co-catalyst comprising an aluminum compound.

19. The catalyst reaction mixture of claim 18, wherein the aluminum compound is selected from: trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, sesquichlorinated ethylaluminum, ethyl dichloride, methylaluminoxane, modified methylaluminoxane, or combinations thereof.

20. The catalyst reaction mixture according to any one of claims 1 to 8, wherein the catalyst reaction mixture further comprises ethylene and at least one linear α-olefin.

21. The catalyst reaction mixture of claim 20, wherein the at least one linear α-olefin is selected from: 1-butene, 1-hexene, or 1-octene.

22. A method for forming linear α-olefins by ethylene oligomerization, the method comprising: i) Contacting ethylene gas with a reaction mixture in a reactor, the reaction mixture comprising a ligand, a chromium compound, and a solvent mixture, the ligand having a skeleton having at least one phosphorus atom and at least one nitrogen atom, the solvent mixture comprising decahydronaphthalene and at least one additional solvent, wherein the solvent mixture comprises decahydronaphthalene in an amount of 5 to 20% by weight, based on the total weight of the solvent mixture; and ii) Remove the product stream from the reactor, the product stream comprising at least one linear α-olefin.

23. The method of claim 22, wherein the at least one linear α-olefin is selected from: 1-butene, 1-hexene, or 1-octene.

24. The method of claim 22, wherein the content of the decahydronaphthalene is 15% by weight or less, based on the total weight of the solvent mixture.

25. The method of claim 24, wherein the content of decahydronaphthalene is 5 to 15% by weight, based on the total weight of the solvent mixture.

26. The method of claim 25, wherein the content of decahydronaphthalene is 8 to 12% by weight, based on the total weight of the solvent mixture.

27. The method of claim 22, wherein the at least one additional solvent is selected from: saturated or unsaturated, linear or branched hydrocarbons, ethers, aromatic hydrocarbons, wherein the hydrocarbons, ethers, aromatic hydrocarbons may be unsubstituted or substituted with halogens, haloalkanes, or combinations thereof.

28. The method of claim 27, wherein the at least one additional solvent is selected from toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

29. The method of any one of claims 22 to 28, wherein the solvent mixture contains 50% by weight or less of perhydroindene, based on the total weight of the solvent mixture.

30. The method of claim 29, wherein the solvent mixture does not contain detectable perhydroindene.

31. The method of any one of claims 22 to 30, wherein the ligand has the following structure: PNP, PNPN, PNNP, PNPNP, or NPNPN, wherein each P is a substituted phosphine group and each N is a substituted amino group.

32. The method of claim 31, wherein the ligand has at least two nitrogen atoms in its backbone.

33. The method of claim 31, wherein the ligand has the following structure: (R 1 (R) 2 )N—P(R 3 )—N(R 4 )—P(R 5 )—N(R 6 (R) 7 ), where R 1 R 2 R 3 R 4 R 5 R 6 Each R 7 Each can be independently hydrogen, unsubstituted or substituted amino, trialkylsilyl, or unsubstituted or substituted C1-C. 20 Hydrocarbon group, wherein the substituted amino group or the substituted C1-C group 20 Substituents on the hydrocarbon group include amino or C1-C. 20 Hydrocarbon group.

34. The method of claim 33, wherein R 4 It is a C1-C4 alkyl group, R 3 and R 5 Each is independently selected from C6-C 20 Aryl or C3-C7 aliphatic group, which may be cyclic or acyclic, linear or branched, substituted or unsubstituted, and R 1 R 2 R 6 and R 7 Each is independently selected from C1-C 10 alkyl.

35. The method of claim 34, wherein R 1 R 2 R 6 and R 7 Each is independently selected from C1-C5 alkyl groups.

36. The method of any one of claims 22 to 30, wherein the ligand has the following structure: Wherein R1 and R2 are independently cyclohexyl or phenyl, wherein the cyclohexyl or phenyl is unsubstituted or converted by one or more C1-C1 groups. 10 Alkyl substitution, and R3 is a C1-C4 alkyl group.

37. The method of claim 36, wherein R1 and R2 are independently cyclohexyl or phenyl, which are substituted with one or more C1-C5 alkyl groups.

38. The method of any one of claims 22 to 30, wherein the chromium compound is an organometallic complex of Cr(III).

39. The method of claim 38, wherein the chromium compound is selected from: acetylacetone Cr(III), octanoic acid Cr(III), Cr(III)Cl3 (tetrahydrofuran)3, 2-ethylhexanoic acid Cr(III), chlorinated Cr(III), cycloalkanoic acid Cr(III), tris(2,2,6,6-tetramethyl-3,5-heptadecanoic acid) Cr(III), or combinations thereof.

40. The method of any one of claims 22 to 30, wherein the catalyst reaction mixture further comprises a co-catalyst comprising an aluminum compound.

41. The method of claim 40, wherein the aluminum compound is selected from: trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxane, modified methylaluminoxane, or combinations thereof.

42. The method according to any one of claims 22 to 30, wherein the polymer content of the product stream is 0.9% by weight or less, based on the total weight of the product stream.

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