CATALYST COMPOSITION FOR OLIGOMERIZATION REACTIONS - Patent application

Abstract

The present disclosure provides a catalytic 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, the solvent mixture comprising decalin in an amount of less than 20 wt.% based on the total weight of the solvent mixture, and optionally comprising perhydroindan in an amount of 50 wt.% or less. Also provided is a method for forming linear alpha olefins by ethylene oligomerization, comprising contacting ethylene gas with the reaction mixture in a reactor, the reaction mixture comprising the catalytic reaction mixture of the present disclosure; and withdrawing a product stream comprising at least one linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene, from the reactor.

Description

[Technical field]

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

[0002] Linear olefins are a class of hydrocarbons useful as feedstocks in the petrochemical industry, and among these linear alpha olefins, unbranched olefins, in which the double bond is located at the end of the chain, form an important subclass. Linear alpha olefins can be converted to linear primary alcohols by hydroformylation. Hydroformylation may also be used to prepare aldehydes, which can then be oxidized to produce synthetic fatty acids, especially odd-numbered, useful in the manufacture of lubricants. Linear alpha olefins are also used in the manufacture of detergents, such as linear alkylbenzene sulfonates, which are prepared by the Friedel-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 preparation of alpha-olefins is mainly based on the oligomerization of ethylene, which has the corollary that the alpha-olefins produced have an even number of carbon atoms. Oligomerization processes utilize 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 framework, such as the catalyst composition described in US2017 / 0203288 to Al-Hazmi et al.

[0004] One of the main challenges of any oligomerization process is the formation of unwanted polymers, which leads to fouling in the reactor, which requires periodic flushing or lengthy mechanical cleaning to remove. Conventional methods for increasing the activity of the catalyst include increasing the reaction temperature or increasing the amount of cocatalyst used in the process. Both methods not only result in a larger amount of the target oligomer, but also in an increase in the amount of polymer formed during the reaction. Increasing the amount of cocatalyst also makes the process significantly more expensive, since the cost of the cocatalyst is typically high. There remains a need in the art to improve catalyst activity in oligomerization reactions without significantly increasing polymer formation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2017 / 0203288 Summary of the Invention [Means for solving the problem]

[0006] (overview) An exemplary implementation of the present disclosure is directed to a method for forming linear alpha olefins by ethylene oligomerization and a catalyst composition for use in such a method, in which the catalyst is combined with a mixture of solvents containing a relatively small amount of decalin. It has surprisingly been discovered 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.

[0007] The present disclosure includes, but is not limited to, the following embodiments.

[0008] Embodiment 1: A catalytic reaction mixture comprising a ligand having a backbone having 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. % (e.g., about 5-20 wt. %) and optionally perhydroindan in an amount of 50 wt. % or less, based on the total weight of the solvent mixture.

[0009] Embodiment 2: The catalytic reaction mixture of embodiment 1, wherein decalin is present in an amount of about 15 wt.% or less, such as about 5 to about 15 wt.%, or about 8 to about 12 wt.%, based on the total weight of the solvent mixture.

[0010] Embodiment 3: The catalytic 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 may be unsubstituted or substituted with halogen, halogenated alkanes, and combinations thereof, such as toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or combinations thereof.

[0011] Embodiment 4: The ligand has the structure PNP, PNPN, PNNP, PNPNP, or NPNPN, where each P is a substituted phosphino group and each N is a substituted amino group, e.g., the ligand has at least two nitrogen atoms in its backbone, e.g., the ligand has the structure (R 1 )(R 2 )NPR 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 and R 7are each independently hydrogen, optionally substituted amino, trialkylsilyl, or optionally substituted C1-C 20 It may be a hydrocarbyl, for example, R 4 is C1-C4 alkyl, R 3 and R 5 are selected independently. 20 aryl or a C3-C7 aliphatic group, which may be cyclic or acyclic, linear or branched, substituted or unsubstituted; R 1 , R 2 , R 6 and R 7 are selected independently. 10 The catalytic reaction mixture of any one of embodiments 1 to 3, wherein the alkyl is alkyl, for example, C1 to C5 alkyl.

[0012] Embodiment 5: The ligand has the structure:

[0013] [ka] wherein R1 and R2 are independently cyclohexyl or phenyl optionally substituted with one or more C1-C10 alkyl, such as C1-C5 alkyl, and R3 is C1-C4 alkyl.

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

[0015] Embodiment 7: The catalytic 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 catalytic reaction mixture of any one of embodiments 1-7, further comprising ethylene and at least one linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene.

[0017] Embodiment 9: A method of forming linear alpha olefins by ethylene oligomerization, comprising: contacting ethylene gas with a reaction mixture in a reactor, the reaction mixture comprising a ligand having a backbone having 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, the solvent mixture comprising decalin in an amount of less than 20 wt. % (e.g., about 5-20 wt. %) and optionally perhydroindan 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 comprising at least one linear alpha olefin, such as 1-butene, 1-hexene, or 1-octene.

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

[0019] Embodiment 11: The method of embodiment 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 may be unsubstituted or substituted with halogen, halogenated alkanes, 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 ligand has the structure PNP, PNPN, PNNP, PNPNP, or NPNPN, where each P is a substituted phosphino group and each N is a substituted amino group, e.g., the ligand has at least two nitrogen atoms in its backbone, e.g., the ligand has the structure (R 1 )(R 2 )NPR 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 and R 7 are each independently hydrogen, optionally substituted amino, trialkylsilyl, or optionally substituted C1-C 20 It may be a hydrocarbyl, for example, R 4 is C1-C4 alkyl, R 3 and R 5 are selected independently. 20 aryl or a C3-C7 aliphatic group, which may be cyclic or acyclic, linear or branched, substituted or unsubstituted; R 1 , R 2 , R 6 and R 7 are selected independently. 10The method of any one of embodiments 9 to 11, wherein the alkyl is alkyl, for example, C1 to C5 alkyl.

[0021] Embodiment 13: The ligand has the structure:

[0022] [ka] The method of any one of embodiments 9-12, wherein R1 and R2 are independently cyclohexyl or phenyl optionally substituted with one or more C1-C10 alkyl, such as C1-C5 alkyl, and R3 is C1-C4 alkyl.

[0023] 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 Cr(III) acetylacetonate, Cr(III) octanoate, Cr(III)Cl3 (tetrahydrofuran), Cr(III)-2-ethylhexanoate, Cr(III) chloride, Cr(III)-naphthenate, Cr(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate), or a combination thereof.

[0024] Embodiment 15: The method of any one of embodiments 9 to 14, 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.

[0025] Embodiment 16: The method of any one of embodiments 9-15, wherein the product stream comprises a polymer content of about 0.9 wt.% or less, based on the total weight of the product stream.

[0026] These and other features, aspects, and advantages of the present disclosure will become apparent from reading the following detailed description in conjunction with the accompanying figures, which are briefly described below. The present disclosure includes any combination of two, three, four, or more features or elements described in this disclosure, regardless of whether such features or elements are explicitly combined or otherwise recited in a specific exemplary implementation described herein. The present disclosure is intended to be read holistically, such that any separable features or elements of the present disclosure should be considered combinable in any of its aspects and exemplary implementations, unless the context of the disclosure clearly dictates otherwise.

[0027] It is therefore understood that this summary is provided only for the purpose of summarizing some exemplary implementations in order to provide a basic understanding of some aspects of the present disclosure. It is therefore understood that the exemplary implementations described above are merely examples and should not be construed in any way to narrow the scope or spirit of the present disclosure. Other exemplary implementations, aspects, and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying figures which illustrate, by way of example, the principles of some described exemplary implementations.

[0028] Having thus described aspects of the present disclosure in general terms above, reference is now made to the accompanying figures, which are not necessarily drawn to scale. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a simplified schematic diagram of an exemplary ethylene oligomerization reactor according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, some implementations of the present disclosure will be described more fully with reference to the attached figures, in which some, but not all, implementations of the present disclosure are shown. Indeed, various implementations of the present disclosure may be embodied in many different forms and should not be construed as being limited to the implementations set forth herein; rather, these exemplary implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout.

[0031] Unless otherwise specified or clear from the context, references to first, second, etc. should not be construed to imply a particular order. A feature described as being above another feature may instead be below (unless otherwise specified or clear from the context), and vice versa; similarly, a feature described as being to the left of another feature may instead be to the right, and vice versa. Also, while the present specification may refer to quantitative measurements, values, geometric relationships, and the like, unless otherwise specified, any one or more, if not all, of these may be absolute or may be approximate to account for possible acceptable variations, such as those due to engineering tolerances, etc.

[0032] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., the range "up to 25 wt.%, or, more specifically, from 5 wt.% to 20 wt.%" includes the endpoints and all intermediate values ​​of the range "from 5 wt.% to 20 wt.%, etc.). "Combinations" are inclusive of blends, mixtures, alloys, reaction products, and the like.

[0033] As used herein, unless otherwise specified or clear from the context, "or" of a set of operands is an "inclusive or" and is therefore true only if one or more of the operands are true, as opposed to an "exclusive or" which is 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. Additionally, the articles "a" and "an" mean "one or more" unless otherwise specified or clear from the context to be intended in the singular form.

[0034] The following contains definitions of various terms and phrases used throughout this specification.

[0035] The term "hydrocarbyl" refers to any monovalent group derived from a hydrocarbon, for example any aliphatic group (e.g., an alkyl group such as methyl, or a cycloalkyl group such as cyclohexyl) or any aryl group (e.g., phenyl).

[0036] The term "aliphatic" refers to organic functional groups or compounds that contain carbon and hydrogen bonded together in straight chains, branched chains, or non-aromatic rings.

[0037] The term "alkyl" refers to a straight or branched chain saturated hydrocarbon. Non-limiting examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and the like.

[0038] An "aryl" or "aromatic" group is a substituted or unsubstituted monocyclic or polycyclic hydrocarbon, such as a phenyl group, with alternating single and double bonds within each ring structure. Non-limiting examples of aryl group substituents include alkyl, substituted alkyl groups, linear or branched alkyl groups, linear or branched unsaturated hydrocarbons, 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 or branched C1-C5 hydrocarbons. Non-limiting examples of unsaturated hydrocarbons include C2-C5 hydrocarbons containing at least one double bond (e.g., vinyl). Aryl or alkyl groups may 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 that contain two or more conjugated rings (eg, fused aromatic rings) and substituted conjugated rings.

[0039] A "cyclohexyl" group is a substituted or unsubstituted cyclic hydrocarbon group containing 6 carbon atoms. It is fully saturated with hydrogen and has the formula CH 11 A cyclohexyl group is an unsubstituted cyclohexyl group when at least one of the hydrogen atoms has been replaced with another atom or functional group.

[0040] Ethylene Oligomerization Process Linear alpha olefins (LAOs) have the chemical formula C x H 2x Linear alpha olefins are olefins having the formula: C 1-(2-(2-phenylene)-1-propene, C 2-(2-phenylene)-1-propene, C 3-(2-phenylene)-1-propene, C 4-(2-phenylene)-1-propene, C 5-(2-phenylene)-1-propene, C 6-(2-phenylene)-1-propene, C 7-(2-phenylene)-1-propene, C 8-(2-phenylene)-1-propene, C 9-(2-phenylene)-1-propene, C 10-(2-phenylene)-1-propene, C 11-(2-phenylene)-1-propene, C 12-(2-phenylene)-1-propene, C 13-(2-phenylene)-1-propene, C 14-(2-phenylene)-1-propene, C 15-(2-phenylene)-1-propene, C 16-(2-phenylene)-1-propene, C 17-(2-phenylene)-1-propene, C 18-(2-phenylene)-1-propene, C 19-(2-phenylene)-1-propene, C 20-(2-phenylene)-1-propene, C 21-(2-phenylene)-1-propene, C 22-(2-phenylene)-1-propene, C 23-(2-phenylene)-1-propene, C 24-(2-phenylene)-1-propene, C 25-(2-phenylene)-1-propene, C 26-(2-phenylene)-1-propene, C 27-(2-phenylene)-1-propene, C 28-(2-phenylene)-1-propene, C 29-(2-phenylene)-1-propene, C 30-(2-phenyl 20 ~C 24 , C24 ~C 30 , and C 20 ~C 30 Linear alpha olefins, which contain higher blends of olefins, constitute one of the commercially important classes of alpha olefins. Linear alpha olefins are useful intermediates in the manufacture of detergents, synthetic lubricants, copolymers, plasticizers and many other important products.

[0041] Existing methods for the production of linear alpha olefins typically rely on the oligomerization of ethylene. For example, linear alpha olefins can be prepared by the catalytic oligomerization of ethylene in the presence of various catalyst systems.

[0042] The catalyst compositions of the present disclosure typically include a ligand having a framework having at least one phosphorus atom and at least one nitrogen atom, a chromium compound, and a cocatalyst.

[0043] A typical ligand structure is an organophosphorus compound with two phosphino groups covalently linked via a bond. Exemplary ligands include compounds with any of the following backbone structures: PNP, PNPN, PNNP, PNPNP, or NPNPN, where each P is a substituted phosphino group (typically a secondary or tertiary phosphino group), and each N is a substituted amino group (typically a secondary or tertiary amino group), and exemplary substituents on both the phosphino and amino groups include optionally substituted amino, trialkylsilyl, or optionally substituted C1-C20 hydrocarbyl (e.g., optionally substituted phenyl or optionally substituted cyclohexyl), with the optional substituents typically including amino or C1-C20 hydrocarbyl. In certain embodiments, the ligand backbone structure includes at least two N atoms (e.g., PNPN, PNNP, PNPNP, or NPNPN).

[0044] In certain embodiments, the ligand has the formula I: 1 )(R 2 )NPR 3 )-N(R 4 )-P(R5 )-N(R 6 )(R 7 ) The ligand has the structure NPNPN, where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently hydrogen, optionally substituted amino, trialkylsilyl (e.g., trimethylsilyl or triethylsilyl), or optionally substituted C1-C 20 It may be hydrocarbyl. C1-C 20 Examples of hydrocarbyl groups are linear 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 In certain embodiments, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 Each of R is independently hydrogen, methyl, ethyl, isopropyl, tert-butyl, n-hexyl, cyclohexyl, or phenyl. 4 is methyl, R 3 and R 5 are independently selected C6 to C 20 aryl (e.g., phenyl) or a C3-C7 aliphatic group (e.g., cyclohexyl), which may be cyclic or acyclic, linear or branched, substituted or unsubstituted; R 1 , R 2 , R 6 and R 7 are independently selected C1 to C 10 It is alkyl (for example, C1 to C5 alkyl).

[0045] In certain embodiments of the above NPNPN formula, R3 and R 5 are each independently a cyclic, substituted, linear or 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. 3 and R 5 are each independently an aromatic group or a substituted aromatic group, such as a phenyl group, a substituted phenyl group, or an aromatic group containing two or more conjugated rings.

[0046] A subset of ligands of formula I is shown below as formula Ia:

[0047] [ka] (wherein R1 and R2 are independently cyclohexyl or phenyl optionally substituted with one or more C1-C10 alkyl, e.g., C1-C5 alkyl, and R3 is C1-C4 alkyl (e.g., methyl, ethyl, isopropyl, or butyl).

[0048] Table 1 below contains specific examples of ligands suitable for use in the present disclosure.

[0049] [Table 1]

[0050] Optionally, the ligand may be a cyclic derivative in which at least one P or N atom of the ligand is a member of a ring system, or any cyclic derivative thereof in which at least one P or N atom of the NPNPN ligand is a member of a ring system. The ring system may be formed from one or more of the component compounds of the NPNPN ligand by substitution, i.e., by formally removing, per component compound, either the entire two groups R1-R7 (as defined), one atom from each of the two groups R1-R7 (as defined), or the entire one group R1-R7 (as defined) and one atom from another group R1-R7 (as defined), and linking the sites of valence unsaturation thus formally created by one covalent bond per component compound to give the same valence as originally present at the given site.

[0051] The ligands used in this disclosure can be made by synthetic methods known to those of skill in the art, such as those described 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.; and Peulecke et al., Dalton Trans., 2016, 45, 8869, each of which is incorporated herein by reference.

[0052] 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 chromium compounds include Cr(III) acetylacetonate, Cr(III) octanoate, Cr(III)Cl3 (tetrahydrofuran)3, Cr(III)-2-ethylhexanoate, Cr(III) chloride, Cr(III)-naphthenate, and Cr(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate). Combinations comprising at least one of the foregoing chromium compounds may be used.

[0053] The concentration of the chromium compound can vary depending on the particular compound used and the desired reaction rate. In some embodiments, the concentration of the chromium compound is about 0.01 to about 100 millimoles per liter (mmol / l), about 0.01 to about 10 mmol / l, about 0.01 to about 1 mmol / l, about 0.1 to about 100 mmol / l, about 0.1 to about 10 mmol / l, about 1 to about 10 mmol / l, or about 1 to about 100 mmol / l. In one exemplary embodiment, the concentration of the chromium compound is about 0.1 to about 1.0 mmol / l.

[0054] The activator (also known in the art as a cocatalyst) 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 may be used.

[0055] In some embodiments, the activator is a modified methylaluminoxane ("MMAO"), which refers to a methylaluminoxane that includes alkyl substituents derived from C2 or higher alkyl ligands in addition to methyl ligands, typically resulting from, for example, the reaction of a tetraalkyldialuminoxane and / or polyalkylaluminoxane reagent with trimethylaluminum during preparation of the MMAO. One exemplary MMAO is MMAO-3A (CAS No. 146905-79-5), which is a modified methylaluminoxane, type 3A, available from Akzo Nobel as a toluene solution containing 7% aluminum, which corresponds to a concentration of about 18% MMAO-3A.

[0056] The molar ratio of ligand / Cr can be about 0.5 to 50, about 0.5 to 5, about 0.8 to about 2.0, about 1.0 to about 5.0, or about 1.0 to about 1.5.

[0057] The molar ratio of Al / Cr 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 about 50 to about 300.

[0058] The catalyst composition disclosed herein can be used in a process for the oligomerization of ethylene. In an embodiment, the process includes 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 is understood that other olefins, including branched olefins, can be produced as by-products in this reaction.

[0059] The oligomerization of ethylene can be carried out at a pressure of about 1 to about 200 bar, about 10 to about 200 bar, about 10 to about 100 bar, about 20 to about 70 bar, and about 10 to 50 bar. In certain embodiments, the oligomerization is carried out at a pressure of about 20 to about 70 bar.

[0060] The oligomerization of ethylene can also be carried out at a temperature of about 10 to about 200°C, about 20 to about 100°C, about 30 to about 100°C, about 40 to about 100°C, about 40 to about 80°C, or about 40 to about 70°C.

[0061] The oligomerization reaction can be carried out continuously, semi-continuously or discontinuously. In one embodiment, the process can be continuous and the average residence time can be from 10 minutes to 20 hours, for example, from 30 minutes to 4 hours or from 1 to 2 hours. The residence time can be selected to achieve the desired conversion with high selectivity.

[0062] The process may be carried out in solution using an inert solvent mixture that is advantageously non-reactive with the catalyst composition. The solvent mixture comprises 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.

[0063] [ka]

[0064] Additional solvents utilized with decalin can include, but are not limited to, saturated or unsaturated, linear or branched hydrocarbons, ethers, aromatic hydrocarbons which may be unsubstituted or substituted with halogens, halogenated alkanes, 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.

[0065] It has been surprisingly discovered that the use of decalin as a minor component of the solvent mixture in combination with the catalyst system of this disclosure enhances catalytic activity without significant loss of oligomer selectivity or 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, decalin is present in an amount of about 5 to 20 wt.%, based on the total weight of the solvent mixture. In certain embodiments, decalin is present in an amount of about 15 wt.% or less, for example, about 5 to about 15 wt.%, or about 8 to about 12 wt.%, based on the total weight of the solvent mixture. The remainder of the solvent mixture can include one or more additional solvents, such as those described above. Due to its high boiling point, the use of decalin does not cause any additional difficulties in the separation of the target product by distillation.

[0066] In certain embodiments, the solvent mixture is substantially or completely free of perhydroindan or contains relatively small amounts of perhydroindan. For example, the solvent mixture may be characterized as containing about 50% or less by weight of perhydroindan, such as about 40% or less by weight, or about 30% or less by weight, or about 20% or less by weight. In certain embodiments, the perhydroindan content is about 10% or less by weight, or about 5% or less by weight, or about 2.5% or less by weight, or about 1% or less by weight. Exemplary ranges of perhydroindan content include 0.0% to about 50% by weight, or about 0.0% to about 25% by weight. In certain embodiments, the solvent mixture contains no detectable perhydroindan.

[0067] In certain embodiments, the use of the solvent mixtures of the present disclosure provides a solvent composition in the range of kg ethylene / g Cr *h can be used to increase the catalytic activity, as determined by ethylene consumption per weight of chromium compound during one hour of reaction time. In some embodiments, the catalytic activity is 128 kg / g Cr *Over h, e.g. 130kg / g Cr *Super h, 132kg / g Cr *Super h, 134kg / g Cr *Super h, 136kg / g Cr *Super h, 138kg / g Cr *Over 140kg / g Cr *h or more (for example, about 128 to about 150 kg / g Cr *h or about 130 to about 145 kg / g Cr *h).

[0068] In certain embodiments, the use of the solvent mixtures of the present disclosure increases catalyst activity while preserving olefin selectivity without increasing unwanted 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. Unwanted polymer species are defined as polymer species having a molecular weight of at least 650 Da and typically include species that are insoluble in the reactor medium and need to be filtered or otherwise removed.

[0069] The process can be carried out in any reactor, for example a loop reactor, a plug flow reactor or a bubble column reactor. The oligomerization of ethylene is an exothermic reaction that can be cooled by an excess stream of ethylene. The gases leaving the top of the reactor can be cooled using a series of external coolers and condensers. The gas phase can be recycled after further cooling.

[0070] The bottom stream leaving the oligomerization reactor at the bottom may contain active catalyst and unreacted ethylene. The reaction may be terminated by removing the catalyst components from the organic phase by extraction with a caustic aqueous phase to avoid undesired side reactions. Contact with the caustic aqueous phase may result in the formation of non-reactive inorganics corresponding to the catalyst components.

[0071] The organic phase, after passing through a catalyst removal system, can be passed through a molecular sieve absorption bed and then fed to a distillation column to recover dissolved ethylene. The recovered ethylene can be recycled through an ethylene recycle loop while the product is fed to an intermediate vessel, and then the product can be fed to a separation section. In certain embodiments, the linear alpha olefins produced from the reactor can be directed to a separation procedure.

[0072] Bubble Column Reactor In an embodiment, the oligomerization reaction may be carried out in a bubble column reactor. FIG. 1 shows an exemplary bubble column reactor 24 for use in the present disclosure. Ethylene may be introduced into reactor 24 using feed stream 26 through a gas distribution system attached to the bottom of the bubble column reactor, which typically includes one or both of a gas sparger plate 30 and a gas bubbler 32. The gas distribution system distributes the gaseous ethylene evenly throughout reactor 24. The gaseous ethylene rises through a liquid composition 40 in reactor 24, which typically includes linear alpha olefins and reaction by-products, a solvent mixture, and a catalyst composition as described herein. For example, the catalyst may enter reactor 24 via catalyst inlet stream 42. The solvent may enter reactor 24 via solvent inlet stream 44. Oligomerization reactions can occur when gaseous ethylene interacts with the liquid composition to produce reaction products that can include polymer droplets and linear alpha-olefin droplets.

[0073] Liquid heavy linear alpha-olefins, together with the solvent and catalyst, may be withdrawn from the bottom of the reactor 24 via bottom effluent stream 34. A portion of the formed linear alpha-olefins, which are gaseous under the reaction conditions, may be condensed in the top of the reactor using internal condenser 36 and may utilize their respective heats of vaporization to serve as reflux for cooling purposes. Gaseous ethylene and light linear alpha-olefins may be removed at the top of the bubble column reactor via top effluent stream 38. Either or both effluent streams may be further processed using additional downstream processing equipment, such as condensers, heat exchangers, distillation columns, and the like.

[0074] experiment The catalytic performance in the presence of various solvent compositions was evaluated by ethylene oligomerization reactions carried out in a stainless steel pressure reactor at 45° C. Dry n-heptane and decalin were used in various solvent combinations, MMAO-3A was used as the cocatalyst, and Cr(III) acetylacetonate was used as the chromium compound. The ligand of formula Ia was used, where R1 and R2 are phenyl, and R3 is methyl.

[0075] A summary of the results is shown in Table 2 below. The product distribution was assessed by GC-MS analysis and the catalyst activity was calculated based on ethylene consumption during 1 hour of reaction time. The table provides the yield of 1-hexene (C6 total) and the weight % of 1-hexene in all C6 olefins separated. The same information is provided for 1-octene. The amount of polymer formed is also provided.

[0076] [Table 2]

[0077] As shown in Table 2, the use of solvent mixtures containing small amounts of decalin, e.g., 5-20 wt.%, can increase the catalytic activity compared to the use of n-heptane alone. Alternatively, the above data show that the addition of decalin allows the catalyst to cocatalyst ratio to be reduced while maintaining the same catalytic performance characteristics. The presence of small amounts of decalin does not adversely affect the selectivity of the reaction for the desired oligomers, e.g., C6 or C8 oligomers, and does not significantly increase polymer formation. In fact, at 5-15 wt.% decalin, polymer formation is suppressed compared to n-heptane alone. The use of decalin as the sole solvent greatly reduced the catalytic activity and increased polymer formation compared to the use of n-heptane alone.

[0078] Without wishing to be bound by a theory of operation, these experimental results can be explained by the increased solubility of ethylene in the reaction solvent, making it more readily available to the activated catalyst. Activation of chromium species by aluminum alkyl cocatalysts results in the formation of highly reactive species. If ethylene is not readily available in solution, such species undergo decomposition and different chromium compounds are formed. Such compounds promote polymerization instead of oligomerization activity.

[0079] However, adding large amounts of decalin to the reaction mixture appears to have a detrimental effect on catalyst performance and reduces the overall catalyst activity. This can be explained by the decrease in solubility of the active catalytic species in the reaction solvent when the decalin concentration exceeds a certain percentage. The increase in the viscosity of the solvent due to the addition of more decalin may also cause mass transfer limitations of ethylene, resulting in a decrease in catalyst activity.

[0080] In general, the present invention may alternatively comprise, consist of, or consist essentially of any suitable components disclosed herein. The present invention may additionally, or alternatively, be formulated to be free or substantially free of any components, materials, ingredients, adjuvants, or species used in prior art compositions or that are otherwise not essential to the function and / or achievement of the purpose of the present invention.

[0081] Many modifications and other implementations of the present disclosure will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the present disclosure is not limited to the specific implementations disclosed herein, and that modifications and other implementations 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 catalytic reaction mixture comprising a ligand having a skeleton having 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 5 to 20 wt % based on the total weight of the solvent mixture, and is free of perhydroindan or comprises perhydroindan in an amount of 50 wt % or less.

2. 10. The catalytic reaction mixture of claim 1, wherein the decalin is present in an amount of 15% by weight or less, based on the total weight of the solvent mixture.

3. 2. The catalytic reaction mixture of claim 1, 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 may be unsubstituted or substituted with halogens, halogenated alkanes, and combinations thereof.

4. The catalytic reaction mixture of claim 1, wherein the at least one additional solvent is selected from the group consisting of toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or a combination thereof.

5. 4. The catalytic reaction mixture of any one of claims 1 to 3, wherein the ligand has the structure PNP, PNPN, PNNP, PNPNP, or NPNPN, where each P is a substituted phosphino group and each N is a substituted amino group.

6. The catalytic reaction mixture of claim 5, 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 ), where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently hydrogen, optionally substituted amino, trialkylsilyl or optionally substituted C 1 to C 20 hydrocarbyl.

7. The catalytic reaction mixture of claim 6, wherein R 4 is C1 to C4 alkyl, R 3 and R 5 are each independently selected C 6 to C 20 aryl or C3 to C7 aliphatic groups, and R 1 , R 2 , R 6 and R 7 are each independently selected C 1 to C 10 alkyl.

8. The ligand has the structure: 【Chemistry 1】 (In the formula, R １ and R ２ is independently cyclohexyl or phenyl optionally substituted with one or more C1-C10 alkyl; R ３ is a C1-C4 alkyl.

9. 4. The catalytic reaction mixture of claim 1, wherein the chromium compound is an organometallic complex of Cr(III).

10. The catalytic reaction mixture of claim 9, wherein the organometallic complex of Cr(III) is Cr(III) acetylacetonate, Cr(III) octanoate, Cr(III)Cl 3 (tetrahydrofuran) 3 , Cr(III)-2-ethylhexanoate, Cr(III) chloride, Cr(III)-naphthenate, Cr(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate), or a combination thereof.

11. The catalytic reaction mixture of any one of claims 1 to 3, further comprising a co-catalyst comprising an aluminum compound.

12. The catalytic reaction mixture of claim 11, wherein the aluminum compound is trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxane, modified methylaluminoxane, or a combination thereof.

13. 4. The catalytic reaction mixture of any one of claims 1 to 3, further comprising ethylene and at least one linear alpha olefin.

14. The catalytic reaction mixture of claim 13, wherein the at least one linear alpha olefin is 1-butene, 1-hexene, or 1-octene.

15. 1. A process for forming linear alpha olefins by ethylene oligomerization, comprising: i) contacting ethylene gas with a reaction mixture in a reactor, the reaction mixture comprising a ligand having a skeleton 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, the solvent mixture comprising decalin in an amount of 5 to 20 wt % and no perhydroindan or comprising perhydroindan in an amount of 50 wt % or less, based on the total weight of the solvent mixture; ii) withdrawing a product stream comprising at least one linear alpha olefin from said reactor; A method comprising:

16. 16. The method of claim 15, wherein the decalin is present in an amount of 15% by weight or less, based on the total weight of the solvent mixture.

17. 16. The method of claim 15, 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 may be unsubstituted or substituted with halogens, halogenated alkanes, and combinations thereof.

18. The method of claim 15, wherein the at least one additional solvent is selected from the group consisting of toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, methylcyclohexane, dichloroethane, dichlorobutane, or a combination thereof.

19. 19. The method of any one of claims 15 to 18, wherein the ligand has the structure PNP, PNPN, PNNP, PNPNP, or NPNPN, where each P is a substituted phosphino group and each N is a substituted amino group.

20. The method of claim 19, 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 and R 7 are each independently hydrogen, optionally substituted amino, trialkylsilyl or optionally substituted C 1 to C 20 hydrocarbyl.

21. The method of claim 20, wherein R 4 is C1 to C4 alkyl, R 3 and R 5 are each independently selected C 6 to C 20 aryl or C3 to C7 aliphatic groups, and R 1 , R 2 , R 6 and R 7 are each independently selected C 1 to C 10 alkyl.

22. The ligand has the structure: 【Chemistry 2】 (In the formula, R １ and R ２ is independently cyclohexyl or phenyl optionally substituted with one or more C1-C10 alkyl; R ３ is a C1-C4 alkyl.

23. 19. The method according to any one of claims 15 to 18, wherein the chromium compound is an organometallic complex of Cr(III).

24. The method of claim 23, wherein the organometallic complex of Cr(III) is Cr(III) acetylacetonate, Cr(III) octanoate, Cr(III)Cl 3 (tetrahydrofuran) 3 , Cr(III)-2-ethylhexanoate, Cr(III) chloride, Cr(III)-naphthenate, Cr(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate), or a combination thereof.

25. The method of any one of claims 15 to 18, further comprising a co-catalyst comprising an aluminum compound.

26. The method of claim 25, wherein the aluminum compound is trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxane, modified methylaluminoxane, or a combination thereof.

27. 19. The method of any one of claims 15 to 18, wherein the product stream comprises a polymer content of 0.9 wt% or less, based on the total weight of the product stream.

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