RU2804351C2 - Ligands for production of 1-octene in the chrome-catalyzed ethylene oligomerization process - Google Patents

Abstract

FIELD: catalytic compositions.

SUBSTANCE: present invention is related to a catalyst composition for the oligomerization of ethylene to 1-octene. The proposed composition contains: a chromium (III) compound, an activator or cocatalyst and a ligand having the formula:

, where each Ar¹ and Ar² independently represent a phenyl group or a substituted phenyl group, n is 0 or 1, and m = n +3. A method for producing 1-octene from ethylene using the specified catalyst composition is also proposed.

EFFECT: proposed catalytic composition makes it possible to obtain 1-octene with high selectivity and degree of purity.

17 cl, 1 dwg, 1 tbl, 2 ex

Description

Cross-reference to related applications

The present invention claims benefit from U.S. Provisional Application No. 62/758,783, filed November 12, 2018, the contents of which are incorporated herein by reference in their entirety.

Prerequisites for creating the invention

Field of technology to which the invention relates

The present invention generally relates to a catalyst for the oligomerization of ethylene to 1-octene. This catalyst includes a chromium(III) compound and a ligand that improves the selectivity of oligomerization to 1-octene but not to 1-hexene.

State of the art

Known methods for producing linear alpha olefins (LAO), including 1-butene, 1-hexene and 1-octene in comonomer purity, are based on the oligomerization of ethylene and produce a mixture of oligomers that are ethylene derivatives and have chain lengths of 4, 6, 8, etc. d. Without being bound by any theory, this is believed to be due to a chemical mechanism primarily governed by the competition of chain propagation and chain transfer steps that results in a Schultz-Flory or Poisson distribution of products. From a commercial perspective, this distribution of products creates a challenge for the manufacturer of the LAO line, since each market segment served may be of different size and growth rate, geography, fragmentation, etc. Therefore, it is difficult for the LAO manufacturer to adapt to market requirements, since part of the product range may be in high demand in a given economic context, while other fractions of the product may not be in demand at all on the market or may be niche products. For example, some grades of polyethylene materials require improved physical properties, such as superior tensile strength and crack resistance, and they require the presence of 1-octene but not other ethylene-derived oligomers.

Oligomerization of ethylene usually takes place in the presence of suitable catalysts. Several of the known ethylene oligomerization catalysts, namely dimerization, trimerization or tetramerization, have one or more disadvantages. These disadvantages may include: 1) low selectivity for the formation of target products (for example, 1-octene); 2) low selectivity for the formation of LAO isomer in the _C8 fraction (for example, isomerization, formation of branched olefins, etc.); 3) wax formation (for example, the formation of heavy, long-chain (having a high carbon number) products); 4) the formation of polymers (polyethylene, including branched and/or cross-linked PE), which can lead to a noticeable decrease in LAO yield, as well as equipment failure; 5) low values of the catalyst turnover rate/activity, leading to an increase in the price per kilogram of product; 6) high price of catalysts or ligands; 7) complex, multi-stage ligand synthesis, which leads to low catalyst availability and high catalysis costs; 8) the dependence of the catalyst’s performance, both in terms of activity and selectivity, on trace amounts of impurities (which leads, for example, to loss or poisoning of the catalyst); 9) the difficulty of working with catalyst components under technical/commercial conditions (for example, during the synthesis of the catalytic complex, pre-mixing, creating inert conditions, isolating the catalyst or ligand from the reaction mixture); 10) severe reaction conditions, such as high temperature and pressure, creating the need for special equipment (this increases the cost of investment, maintenance and energy); 11) high cost of the cocatalyst/activator or their high consumption; and/or 12) sensitivity to variations in cocatalyst quality, which often occurs when poorly defined compounds are used as activators (eg, some methylaluminoxane (MAO) species).

Attempts to synthesize LAO have been described. For example, in US patent application No. 2017/0203288 from Al-Hazmi et al. discloses the use of a catalyst composition that may include a chromium compound and a functionalized triamino diphosphine ligand (NPNPN) having the formula (R ¹ )(R ² )NP(R ³ )-N(R ⁴ )-P(R ⁵ )-N(R ⁶ )( ^R7 ), wherein ^R1 , ^R2 , ^R3 , ^R4 , ^R5 , ^R6 and ^R7 are each independently hydrogen, halogen, amino, trimethylsilyl or _C1 - _C20 hydrocarbyl, preferably linear or branched C ₁ -C ₁₀ alkyl, phenyl, C ₆ -C ₂₀ aryl or C ₆ -C ₂₀ alkyl-substituted phenyl. This catalyst has the disadvantage that it produces more than 8 wt% C ₁₀₊ and about a 50:50 wt% ratio of 1-hexene to 1-octene. When this ratio increases in favor of C ₆ relative to C ₈ , the amount of C ₁₀₊ also increases, which reduces the final amount of the target product. In another example, Peulecke (Dalton Transactions, 2016 45; 8869-8874) describes the preparation of mixtures of 1-hexene and 1-octene using an NPNPN ligand having the formula (R ¹ )(R ² )NP(Ph)-N (R ³ )-P(PH)-N(R ⁴ )(R ⁵ ). This catalyst system has the disadvantage that more than 11 wt.% C ₁₀₊ is produced, and the yield of C ₁₀₊ hydrocarbons increases as the yield of 1-octene increases relative to the yield of 1-hexene.

Thus, there remains a need in the art for catalyst systems for the oligomerization of ethylene that can produce 1-octene with high selectivity and purity.

Summary of the Invention

A discovery has been made that provides a solution to at least some of the problems associated with the oligomerization of ethylene to 1-octene. This solution is based on the use of the NPN(CH ₃ )PN ligand system, which has specific alkyl substituents at the terminal amino groups and phosphorus atoms. Namely, the substituents on the fluorine atoms are limited to aromatic groups and/or alkyl-substituted aromatic groups, and the terminal amines include linear alkyl groups, the number of carbon atoms in which differs by 3. As shown in non-limiting examples, it was unexpectedly found that when limiting the range of substituents at phosphorus atoms with an aromatic group or substituted aromatic group and limiting the length of the hydrocarbon chain at the terminal nitrogen atoms ensures at least 60 wt. % C8 hydrocarbons with a selectivity for 1-octene of more than 99%, and less than 2 wt. % of substances insoluble in the solvent (for example, polymer).

In one aspect of the present invention, catalyst compositions for the oligomerization of ethylene to 1-octene are described. The catalyst composition may include a chromium(III) compound and a ligand having the formula:

where each Ar¹ and Ar² independently represents an aromatic group or a substituted aromatic group, n is 0 or 1, and m = n + 3. In some embodiments, each Ar¹ and Ar² independently represents a phenyl group or an alkyl-substituted phenyl group, preferably both Ar are phenyl groups. In one case, n is 0 and the catalyst is (CH₃)(n-C₄H₉)NP(C₆H₅)N(CH₃)NP(C₆H₅)N(CH₃)(n-C₄H₉), represented by the following structure:

.

Alternatively, n is 1 and the catalyst is (CH ₃ CH ₂ )(n-C ₅ H ₁₁ )NP(C ₆ H ₅ )N(CH ₃ )NP(C ₆ H ₅ )N(CH ₂ CH ₃ )(n-C ₅ H ₁₁ ), represented by the following structure:

.

The catalyst composition may also include an activator or cocatalyst (eg, methyl aluminoxane compounds, preferably methyl isobutylaluminum oxide). Chromium(III) compounds may include any inorganic or organic chromium compound in which chromium has a valency of +3. Non-limiting examples of chromium(III) compounds include chromium(III) acetylacetonate, Cr(2,2,6,6,-tetramethyl-3,5-heptadionate) ₃ , chromium(III)2-ethylhexanoate, tris-tetrahydrofuran chromium trichloride, octanoate chromium(III), or chromium(III) naphthenate, or any combination thereof.

Methods for producing 1-octene using the catalyst composition of the present invention are also described. A method for producing 1-octene may include contacting a reactant stream comprising an olefin source with a solution containing a catalyst composition of the present invention to produce an oligomer composition that includes 1-octene. The catalyst composition may also include a solvent (eg, a saturated hydrocarbon or aromatic hydrocarbon, preferably n-hexane, methylcyclohexane, toluene, or mixtures thereof). The contacting step may include using a temperature from 15°C to 100°C, preferably from 40°C to 70°C and/or at a pressure of at least 2 MPa or from 2 to 20 MPa, preferably from 2 to 7 MPa. During the process, a substance insoluble in the solvent (for example, a polymer material) may be formed in an amount of less than 2 wt. %, preferably less than 1 wt. % or more preferably less than 0.5 wt. % (or it is not formed at all). In some cases, the catalyst composition may include

,

a chromium(III) compound and an activator or cocatalyst. In other cases, the catalyst composition may include

,

a chromium(III) compound and an activator or cocatalyst. In some embodiments, the product stream may include 1-hexene. In these embodiments, the 1-octene selectivity of the process may be greater than 99% and/or the weight ratio of 1-hexene to 1-octene may be less than 0.3.

In the context of the present invention, at least twenty embodiments will now be described. The first option is a catalytic composition for the oligomerization of ethylene into 1-octene. This catalyst composition includes a chromium(III) compound and a ligand having the formula:

where each Ar¹ and Ar² independently represents an aromatic group or a substituted aromatic group, n is 0 or 1, and m = n + 3. In the second embodiment, the catalyst composition is the same as embodiment 1, where each Ar¹ and Ar² independently represents a phenyl group, a substituted phenyl group, or an aromatic group containing 2 or more conjugated rings. In the third embodiment, the catalytic composition is similar to option 2, where both Ar substituents¹ and Ar² are phenyl groups. In Embodiment 4 of the catalyst composition of Embodiment 3, n is 0 and the catalyst has the structure:

.

In embodiment 5 of the catalyst composition, 2 n is 1 and the catalyst has the structure:

.

In embodiment 6 of the catalyst composition according to any one of options 1 - 5, the composition further includes an activator or cocatalyst. In embodiment 7 of the catalyst composition of embodiment 6, the activator or cocatalyst is a methyl aluminoxane compound. In embodiment 8 of the catalyst composition of embodiment 6, the activator or cocatalyst is the compound methyl isobutylaluminum oxide. In embodiment 9 of the catalyst composition of embodiment 8, the chromium(III) compound is chromium(III) acetylacetonate, Cr(2,2,6,6,-tetramethyl-3,5-heptadionate) ₃ , chromium(III)2-ethylhexanoate, tris-tetrahydrofuran chromium trichloride, chromium(III) octanoate, or chromium(III) naphthenate.

Embodiment 10 is a method for producing 1-octene from ethylene. The method includes the steps of contacting a reactant stream containing an olefin source with a solution containing the catalyst composition of any one of embodiments 1 through 9 to produce an oligomeric composition containing 1-octene. Embodiment 11 is a variant of method 10 in which the solution contains a solvent. Embodiment 12 is a variant of method 11 in which the solvent is a saturated hydrocarbon or an aromatic hydrocarbon. Embodiment 13 is a variant of method 12 in which the solvent is n-hexane, methylcyclohexane, toluene, or a mixture thereof. Embodiment 14 is the process of any one of embodiments 10 to 13, wherein the product stream further contains 1-hexene, wherein the 1-octene selectivity is greater than 60 wt. %, and the weight ratio of 1-hexene to 1-octene is less than 0.3. Embodiment 15 is a method according to any one of embodiments 10 to 14, in which the substance insoluble in the solvent is formed in an amount of less than 2 wt. %. Embodiment 16 is a variant of method 15 in which the catalyst composition includes:

.

Embodiment 17 is the method of any one of embodiments 15 to 16, further comprising a chromium(III) compound, an activator, or a cocatalyst. Embodiment 18 is the process of any one of embodiments 10 through 17, wherein the catalyst composition includes a chromium(III) compound, an activator, a cocatalyst, and

.

Embodiment 19 is the method of any one of embodiments 10 to 18, wherein the contacting is carried out at a temperature of 15°C to 100°C, preferably 40°C to 70°C. Embodiment 20 is a method according to any one of embodiments 10 to 19, wherein the contacting is carried out under a pressure of at least 2 MPa or from 2 to 20 MPa, preferably from 2 to 7 MPa.

Other embodiments of the invention are discussed throughout the application. Any embodiment discussed in relation to one aspect of the invention is applicable to other aspects of the invention, and vice versa. It is intended that each embodiment described in this document is an embodiment of the invention that is applicable to other aspects of the invention. It is intended that any embodiment described herein may be practiced with any method or composition of the invention, and vice versa. Moreover, the compositions of the invention can be used to carry out the methods of the invention.

The following are definitions of various terms and expressions used herein.

The term “alkyl group” means a linear or branched saturated hydrocarbon. Non-limiting examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, etc.

An “aryl” group or “aromatic” group is an unsubstituted or substituted, mono- or polycyclic hydrocarbon with alternating single and double bonds within each ring structure. Non-limiting examples of substituents on aryl groups include alkyl, substituted alkyl groups, linear or branched alkyl groups, linear or branched unsaturated hydrocarbon substituents, halogen, hydroxyl, alkoxy group, haloalkyl, haloalkoxy group, carboxyl group, ester group, amino group, nitro group, amide group, nitrile group, acyl, alkylsilane, thiol and thioether group. Non-limiting examples of alkyl groups include linear and branched C ₁ -C ₅ hydrocarbons. Non-limiting examples of unsaturated hydrocarbons include C ₂ -C ₅ hydrocarbons containing at least one double bond (eg, vinyl). An aryl or alkyl group may be substituted with halogen, hydroxyl, alkoxy, haloalkyl, haloalkoxy, carboxyl, ester, ether, amino, nitro ( _-NO2 ), amide, nitrile ( -CN), acyl, alkylsilane, thiol and thioether group. Non-limiting examples of halogens include chlorine (-Cl), bromine (-Br) or fluorine (-F). Non-limiting examples of haloalkyl substituents include -CX ₃ , -CH ₂ X , -CH ₂ CH ₂ X , -CHXCH ₂ X , -CX ₂ CHX ₂ , -CX ₂ CX ₂ , where X is F, Cl, Br, or combinations thereof . Non-limiting examples of amine substituents include -NH ₂ , -CH ₂ NH ₂ , -CHCH ₂ NH ₂ , -C(NH ₂ )CH ₃ . Non-limiting examples of alkoxy groups include –OCH ₃ , –OCH ₂ CH ₃ and the like. Non-limiting examples of alkylsilane substituents include –Si(CH ₃ ) ₃ , –Si(CH ₂ CH ₃ ) ₃ and the like. Non-limiting examples of polycyclic groups include ring systems that contain 2 or more conjugated rings (eg, fused aromatic rings) and substituted conjugated rings, such as –C ₁₀ H ₇ and substituted 10-carbon conjugated ring systems.

The expression “solvent insoluble” refers to a hydrocarbon substance with a molecular weight of 400 g/mol or higher (more than 30 carbon atoms) that does not form a homogeneous solution with the reaction solvent under process conditions. For example, this substance precipitates or forms a second phase during the process. The specified substance is present in an amount of less than 2 wt. %, preferably < 1 wt. %, more preferably <0.5 wt. % according to gravimetric study.

The terms “about” or “about” have a similar meaning as would be understood by one of ordinary skill in the art. In one non-limiting embodiment, these terms mean a range within ±10%, preferably ±5%, more preferably ±1%, and most preferably ±0.5%.

The terms “wt%,” “vol%,” or “mol%” mean the weight percent of a component, the volume percent of a component, or the mole percent of a component, respectively, relative to the total weight, total volume of material, or total number of moles including the component. In a non-limiting example, 10 grams of component in 100 grams of material corresponds to 10 wt.% component.

The term “substantially as” and its variations include ranges of deviations within 10%, within 5%, within 1%, or within 0.5%.

The terms “inhibition” or “reduction” or “prevention” or “avoidance” or any variations of these terms when used in the claims and/or description include any measurable reduction or complete inhibition to achieve the desired result.

The term “effective” when used in the claims and/or description means adequate to achieve the desired, expected or intended result.

The use of the singular in conjunction with any of the terms “comprising,” “comprising,” or “having” in a claim or description may mean “one,” but may also include “one or more,” “at least one,” and "one or more than one."

The words “comprising” (and any forms thereof, such as “contain” and “contains”), “having” (and any forms thereof, such as “have” and “has”), “including” (and any forms thereof, such as “includes” and “include”) are non-limiting and do not exclude the presence of additional, not expressly stated, elements or steps.

The catalyst compositions of the present invention may “comprise”, “consist primarily of,” or “consist of” certain ingredients, components, compositions, etc., disclosed herein. With respect to the transitional expression “consisting primarily of,” in one non-limiting aspect, a primary and innovative feature of the catalyst compositions of the present invention is their ability to catalyze the oligomerization of ethylene to 1-octene with a selectivity greater than 60% to produce a minimal amount of solvent insoluble material (e.g. , < 2 wt.%), producing 1-octene having a purity of at least 99%.

Other objects, features and advantages of the present invention will become apparent from the following drawings, detailed description and examples. However, it should be understood that the drawings, detailed description and examples describing specific embodiments of the present invention are provided for illustrative purposes only and are not limiting. Moreover, those skilled in the art will recognize from the following description possible changes and modifications that are within the spirit and scope of the present invention. In other embodiments, features from particular embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any other embodiments. In other embodiments, additional features may be added to the particular embodiments described herein.

Brief description of drawings

The advantages of the present invention will become apparent to those skilled in the art from the following detailed description and reference to the accompanying drawings.

Fig. 1 illustrates a setup for the production of 1-octene by ethylene oligomerization.

The present invention is susceptible to various modifications and alternative embodiments, and particular embodiments thereof are shown in the drawings by way of example only. Drawings may not be to scale.

Detailed Description of the Invention

A discovery has been made that opens the way to a process for producing 1-octene in acceptable yield, with high selectivity, and without the formation of significant amounts of solvent-insoluble substances, by oligomerization of ethylene. The basis of the invention is the use of the NPNPN ligand system. Namely, as demonstrated in non-limiting examples, the oligomerization product stream may contain at least 60 wt. % 1-octene, less than 25 wt. % 1-hexene and less than 2 wt. % of a substance insoluble in a solvent (for example, polymeric materials). This is in contrast to prior art ligands where more than 2 wt is formed. % polymer materials. Critical parameters include the choice of substituents on the phosphorus and nitrogen atoms. Substituents on the phosphorus atoms include an aromatic group or an alkyl-substituted aromatic group, the substituent on the central nitrogen atom includes a methyl substituent, and substituents on the terminal nitrogen atoms include various linear alkyl hydrocarbon groups, the number of carbon atoms of which varies by 3. This combination of substituents provides an elegant and simple ligand system to produce 1-octene with high purity and selectivity above 60 wt. %.

These and other non-limiting aspects of the present invention are described in more detail in the following sections.

Catalytic composition

The catalyst composition may include the ligands of the present invention, chromium(III) compounds, and an activator or cocatalyst. The ligands of the present invention can be prepared as described herein and in the Examples. The catalyst composition may be in the form of a solution in an aliphatic or aromatic hydrocarbon solvent. The aliphatic hydrocarbon solvent may include hexane, methylcyclohexane, cyclohexane, n-heptane, toluene, and the like.

The ligands of the present invention may be represented by the following formula:

… (1)

in which each Ar¹ and Ar² independently represents an aromatic group or a substituted aromatic group, n is 0 or 1 and m = n+3. Aromatic groups or substituted aromatic groups include phenyl (Ph), C₆-C_eleven aryl or C₆-C₂₀ substituted aryl. Non-limiting Examples C₆-C_eleven aryl groups include methylbenzyl, dimethylbenzyl (ortho-, meta-, and para-substituted), ethylbenzyl, propylbenzyl, and the like. Non-limiting examples of substituents for substitution C₆-C₂₀ aryl groups include alkyl, substituted alkyl groups, linear or branched alkyl groups, 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 C hydrocarbons₁ - C₅. Non-limiting examples of unsaturated hydrocarbons include C₂ - C₅ hydrocarbons containing at least one double bond (for example, vinyl). Aryl or alkyl groups may be replaced by 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 halogen substituents include chlorine (-Cl), bromine (-Br) or fluorine (-F). Non-limiting examples of haloalkyl substituents include –CX₃, -CH₂X, -CH₂CH₂X, -CHXCH₂X, -CX₂CHX₂, -CX₂CX₂, where X means F, Cl, Br or combinations thereof. Non-limiting examples of amine substituents include -NH₂, -CH₂N.H.₂, -CHCH₂N.H.₂, -C(NH₂)CH₃. Non-limiting examples of alkoxy- include -OCH₃, -OCH₂CH₃, and the like. Non-limiting examples of alkylsilane substituents include –Si(CH₃)₃, -Si(CH₂CH₃)₃, and the like. Non-limiting examples of polycyclic groups include fused aromatic rings and substituted fused aromatic rings such as -C₁₀H₇ and substituted fused aromatic ring systems with ten carbon atoms. In some embodiments, C₆-C₂₀ aryl group is chlorobenzene, bromobenzene, trifluorotoluene, phenylamine, nitrobenzene, dichlorotoluene, benzonitrile, trimethylbenzylsilane, benzyl methyl ether, or a fused aromatic ring (C₁₀H₇). Ligands can be (CH₃)(n-C₄H₉)NP(Ar¹)N(CH₃)NP(Ar²)N(CH₃)(n-C₄H₉), and (CH₃CH₂)(n-C₅H_eleven)NP(Ar¹)N(CH₃)NP(Ar²)N(CH₂CH₃)(n-C₅H_eleven), (CH₃)(n-C₄H₉)NP(C₆H₅)N(CH₃)NP(C₆H₅)N(CH₃)(n-C₄H₉), and (CH₃CH₂)(n-C₅H_eleven)NP(C₆H₅)N(CH₃)NP(C₆H₅)N(CH₂CH₃)(n-C₅H_eleven). The structure of the ligands can be represented as follows:

… (2)

… (3)

… (4)

… (5)

where R ₁ and R ₂ represent alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, and pentyl, and the like.

The NPNPN ligand system can be prepared synthetically using approaches known to those skilled in the art. In some embodiments, ligand (1) is accessible using the reaction routes shown in Scheme I:

… (I)

where Ar ¹ and Ar ² are as defined above, R ₃ is methyl or ethyl and R ₄ is butyl when R ₃ is methyl and pentyl when R ₃ is ethyl.

The chromium compounds may be an organic salt, an inorganic salt, a coordination complex, or a Cr(III) organometallic complex. In one embodiment, the chromium compounds are organometallic Cr(III) complexes. Non-limiting examples of chromium compounds include Cr(III) acetylacetonate, Cr(III) octanoate, CrCl ₃ (tetrahydrofuran) ₃ , Cr(III)-2-ethylhexanoate, Cr(III) chloride, or any combination thereof. The ligand/Cr molar ratio may be from about 0.5 to 50, about 0.5 to 5, about 0.8 to 2.0, about 1.0 to 5.0, or preferably about 1.0 up to 1.5.

The activator (also known in the art as a cocatalyst) may be an aluminum compound. Non-limiting examples of aluminum compounds include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, methylaluminoxanes, or mixtures thereof. In some embodiments, the activator may be a modified methylaluminoxane, more preferably MMAO-3A (CAS No. 146905-79-5), which is a modified methylaluminoxane, type 3A, available from Akzo Nobel in a toluene solution containing 7% aluminum, corresponding to MMAO-3A concentration is about 18%. The Al/Cr molar ratio may be from about 1 to 1000, about 10 to 1000, about 1 to 500, about 10 to 500, about 10 to 300, about 20 to 300, or preferably from about 50 to 300 .

In addition, the catalyst composition may include a solvent. Non-limiting examples of solvents include straight and cyclic aliphatic hydrocarbons, straight olefins, ethers, aromatic hydrocarbons, and the like. A combination containing at least one of the above solvents can be used. The preferred solvent is toluene, n-heptane, or methylcyclohexane or any mixtures thereof.

The concentration of chromium compound in the solvent varies depending on the specific compound used and the desired process speed. In some embodiments, the concentration of the chromium compound is from about 0.01 to 100 millimoles per liter (mmol/L), from about 0.01 to 10 mmol/L, from about 0.01 to 1 mmol/L, from about 0. 1 to 100 mmol/L, about 0.1 to 10 mmol/L, about 0.1 to 10 mmol/L, about 1 to 10 mmol/L, and about 1 to 100 mmol/L. Preferably, the concentration of the chromium compound is from about 0.1 to 1.0 mmol/L.

In some embodiments, the catalyst composition includes Cr(III) acetylacetonate as the chromium compound, ethyl(n-pentyl)N-P(phenyl)-N(methyl)-P(phenyl)-N(n-pentyl)ethyl as the NPNPN ligand, and MMAO-3A as an activator. In another embodiment, the catalyst composition includes Cr(III) acetylacetonate as the chromium compound, methyl(n-butyl)N-P(phenyl)-N(methyl)-P(phenyl)-N(n-butyl)methyl as the NPNPN ligand, and MMAO-3A as an activator.

Installation for oligomerization of 1-octene

The catalyst composition of the present invention can be used in a process for oligomerizing ethylene to 1-octene. In one embodiment, the method includes contacting ethylene with a catalyst composition under ethylene oligomerization conditions effective to produce 1-octene. Those skilled in the art will appreciate that the oligomerization of ethylene to form 1-octene can be accomplished by tetramerization of ethylene.

In fig. 1 schematically shows a setup for the production of 1-octene. The installation 100 may include an inlet 102 for supplying reactants, which include ethylene, to a reaction zone 104 that is in fluid communication with the inlet, and an outlet 106 that is in fluid communication with the reaction zone 104 and through which a product stream is diverted. from the reaction zone. Reaction zone 104 may include a catalyst composition of the present invention. A reactant stream containing ethylene may enter reaction zone 104 through inlet 102. In some embodiments, the reactant stream containing ethylene may be used to maintain pressure in reaction zone 104. In some embodiments, the reactant stream includes an inert gas (e.g., nitrogen or argon). After sufficient time has elapsed, the product stream can be removed from reaction zone 104 through product outlet 106. The product stream can be supplied to other processing units, stored and/or transported.

The unit 100 may include one or more heating and/or cooling devices (e.g., insulation, electric heaters, jacketed heat exchangers) or controllers (e.g., computers, flow controllers, automatic valves, etc.) that are needed to control the process temperature and pressure of the reaction mixture. Although only one reactor is shown, it should be understood that multiple reactors may be located in a single unit or multiple reactors may be housed in a single heat exchanger.

As discussed above, the process and catalyst composition of the present invention produce 1-octene with high selectivity, with the LAO product distribution being limited to 1-hexene and 1-octene. High selectivity for 1-octene is advantageous as it results in higher product purity, eliminating the need for additional purification steps in the separation step. Other advantages of the catalytic composition and process of the invention include suppression of ethylene polymerization leading to undesirable polymer formation, milder reaction conditions and, as a result, reduced equipment investment and lower operating and energy costs. In addition, a relatively simple and reliable production process can be built. The selectivity for 1-octene is more than 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, 80 wt. %, 85 wt. %, 90 wt. %, 95 wt. % or about 100 wt. % or is in any range or has any value within the specified values. The purity of 1-octene may be at least about 99%, or 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99 .8%, or 99.9%. A purity of at least 99.1% is preferred. In one embodiment, when 1-hexene is formed, the weight ratio of 1-hexene to 1-octene may be less than 0.3, or from 0 to 0.3, or 0.1, 0.15, 0.2, 0. 25 or 0.3 or it is in any range or has any value within the specified values.

Examples

The present invention will be described in more detail using specific examples. The following examples are provided for illustrative purposes only and are not intended to limit the invention in any way. Those skilled in the art can readily identify a variety of non-critical parameters that can be changed or modified to achieve substantially the same results.

Example 1 Synthesis of Ligands 2 and 3 and Comparative Ligand

Two methodologies can be used to prepare ligands having structures (2) and (3) above. The reference ligand has the following structure, wherein the amino functional groups include methyl groups and ethyl groups (ie, n value less than 3).

Comparative ligand (6)

Path A, general procedure (see diagram 1). All manipulations are carried out in an inert atmosphere. Dissolve bis(chlorophosphino)amine (phenylP(Cl)N(CH ₃ )P(Cl)phenyl, 4.42 g, 14 mmol) in 20 ml of anhydrous toluene. The appropriate secondary amine (29.4 mmol) and triethylamine (35 mmol) are mixed with 30 ml of anhydrous toluene and cooled to -10°C. A toluene solution of bis(chlorophosphino)amine is added dropwise to the reaction mixture under an inert atmosphere with vigorous stirring. Addition of the reagent results in the precipitation of a white gel-like substance. With continuous stirring, the solution is allowed to warm to 25°C over 3 hours, then the mixture is heated to 75°C and further stirred at this temperature for 12 hours. After all volatile compounds have been evaporated in vacuo, the residue is dissolved in anhydrous hot n-heptane, and insoluble material is separated by filtration. Evaporation of the solvent results in a white oil. The purity of the product was confirmed using ¹ H, ¹³ C and ³¹ P NMR spectroscopy. If it is desired to increase the purity of the product, it can be recrystallized from n-hexane, cyclohexane, n-heptane or n-pentane.

Path B, general procedure (see diagram 1). All manipulations are carried out in an inert atmosphere. The appropriate secondary amine (10 mmol) is dissolved in 20 ml of anhydrous n-heptane, cooled to -10°C and treated with 5 mol%. excess n-butyllithium in n-hexane. The solution is then stirred for 3 hours, allowing the temperature to rise to 25°C and the formation of a white precipitate. The solid is separated from the solution, washed with n-hexane and transferred to a flask with 30 ml of anhydrous diethyl ether. The resulting suspension is cooled to -10°C, and a solution of bis(chlorophosphino)amine (phenylP(Cl)N(CH ₃ )P(Cl)phenyl, 1.55 g, 4.9 mmol) in 30 ml of anhydrous ether with vigorous stirring. After addition, the reaction mixture was stirred continuously for 12 hours, allowing the mixture to warm to 25°C. During this process, a white solid is formed. Insoluble material is isolated by filtration, washed with ether and discarded. The solution and washings are combined and the solvent is removed in vacuo to leave a white viscous oil. The purity of the product was confirmed using ¹ H, ¹³ C and ³¹ P NMR spectroscopy. If it is desired to increase the purity of the product, it can be recrystallized from n-hexane, cyclohexane, n-heptane or n-pentane.

The precursor phenylP(Cl)N(methyl)P(Cl)phenyl is prepared according to the method of Jefferson et al. (J. Chem. Soc. Dalton Trans. 1973, 1414-1419).

Example 2. Preparation of a catalytic composition and oligomerization of ethylene

The reactor, equipped with a dip tube, thermocouple, mechanical paddle stirrer, cooling coil, temperature, pressure and stirring control panel (all connected to the data acquisition system), creates an inert atmosphere by heating to 130°C in vacuum and cooling to 30°C with purging with a stream of dried nitrogen. The supply of ethylene at constant pressure is maintained using a gas dosing control unit connected to the data acquisition system. Ethylene consumption is measured by the pressure drop in the supply cylinder over time using a computerized data acquisition system.

Suitable amounts of toluene stock solutions of ligands (ligand (2) of the present invention or a reference ligand) and Cr(III) acetylacetonate as a chromium precursor are measured, with a ligand/Cr ratio of 1.20, and charged into a Schlenk flask under an inert atmosphere. Add 30 ml of anhydrous n-heptane to a pressurized stainless steel reactor and heat to reaction temperature. After the reactor temperature has stabilized, ethylene is introduced into the reactor under a pressure of 30 bar (3 MPa) and maintained for 0.5 hours with continuous mechanical stirring. The pressure is then reduced to 0.2 bar (0.02 MPa) and an appropriate amount of 0.3 M stock solution of MMAO-3A in anhydrous n-heptane is introduced into the reactor through the loading hatch, providing an Al/Cr ratio of 300. Stirring continues. within 10 minutes. After this, a mixture of Cr and ligand solutions is introduced into the reactor through the loading hatch.

Immediately after introducing the catalyst into the reactor, the pressure is increased to 30 bar (3 MPa). Standard process conditions are: ethylene pressure 30 bar (3 MPa), temperature 45°C, stirring speed 450 rpm. After 1 hour of the catalytic cycle, the supply of ethylene is stopped and the reactor temperature is reduced to 5°C. Reduce the ethylene pressure in the reactor to 0.2 bar (0.02 MPa). The process is stopped by quenching with a mixture of 0.3 M HC1/isopropanol. Liquid products are analyzed using a gas chromatograph and a known amount of toluene as an internal standard. Any insoluble by-products (ie, waxes, polyethylene) are filtered, dried and weighed. The subsequent catalytic experiment is carried out without reactor cleaning using the same components and quantities as described above. Table 1 shows the results for the ligand having structure 2 (first and second rings) and for the comparative ligand.

Table 1

Catalyst Activity,
kg/(g _Cr * h) weight. % C6
(1-hexene, %) weight. % C8
(1-octene, %) Substance insoluble in solvent, wt. % 2 (first cycle) 179.15 21.55 (79.20) 76.86 (99.41) 0.32 2 (second cycle) 251.84 22.29 (75.37) 75.88 (99.40) 0.57 6 Comparative 95.45 40.10 (76.78) 58.11 (96.13) 1.09

Table 1 summarizes the results of experimental ethylene oligomerization runs carried out under the indicated standard conditions using catalyst systems prepared with a catalyst having a ligand shown by structure (2) and a comparative catalyst having a ligand shown by structure (6). Table 1 shows the relative selectivity for hexene (C6), octene (C8) and solvent insolubles, by weight. % in the liquid phase. The numbers in parentheses indicate selectivities for the corresponding linear alpha-olefins in the total C6/C8 fraction. In general, the LAO purities reported were predominantly high. Comparative catalyst (6) differs from catalyst (2) in that the ligands of comparative catalyst have carbon chains at two fewer carbon atoms of nitrogen (i.e., ethyl) than the carbon chains in the ligands of catalyst 2 (i.e., butyl). For catalyst S2, two cycles are shown. It is found that the second sequential cycle generally exhibits better performance than the first cycle. As can be seen, in the second sequential cycle the catalytic activity was higher than in the first catalytic cycle. The authors, without being bound by theory, believe that this typical process can probably be explained by the fact that during the first cycle the reactor is dried and cleaned.

Although embodiments of the present invention and their advantages have been described in detail herein, it should be understood that various changes, substitutions and modifications may be made without departing from the spirit and scope of the embodiments covered by the claims. Moreover, the scope of the present invention is not limited to the specific variations of the method, equipment, production, composition, means, methods and steps described herein. As will be appreciated by one skilled in the art from the above description, methods, equipment, manufacture, compositions, means, methods or steps may be used that are now known or will be developed in the future and which perform substantially the same function or provide essentially the same result as the corresponding embodiments described herein. Accordingly, the claims include within their scope such methods, equipment, manufacture, compositions, means, methods or steps.

Claims (25)

1. Catalytic composition for the oligomerization of ethylene into 1-octene, which contains: chromium(III) compound; activator or cocatalyst and ligand having the formula: where each Ar¹ and Ar² independently represents a phenyl group or a substituted phenyl group, n is 0 or 1, and m = n +3. 2. Catalytic composition according to claim 1, in which both Ar¹ and Ar² are phenyl groups. 3. The catalytic composition according to claim 1, in which n is 0 and the ligand has the structure: . 4. The catalytic composition according to claim 1, in which n is 1 and the ligand has the structure: . 5. Catalytic composition according to claim 1, in which the activator or cocatalyst is a methyl aluminoxane compound. 6. Catalytic composition according to claim 1, in which the activator or cocatalyst is methyl iso-butylaluminum oxide. 7. The catalytic composition according to claim 6, in which the chromium (III) compound is chromium (III) acetylacetonate, Cr(2,2,6,6,-tetramethyl-3,5-heptadionate) ₃ , 2-ethylhexanoate chromium ( III), tris-tetrahydrofuran chromium trichloride, chromium(III) octanoate, or chromium(III) naphthenate. 8. A method for producing 1-octene from ethylene, comprising contacting a reagent stream containing a source of olefin with a solution containing a catalyst composition according to any one of claims. 1-7, to obtain an oligomer composition comprising 1-octene. 9. The method according to claim 8, where the solution contains a solvent. 10. The method of claim 9, wherein the solvent is a saturated hydrocarbon or an aromatic hydrocarbon. 11. The method according to claim 10, where the solvent is n-hexane, methylcyclohexane, toluene or a mixture thereof. 12. Method according to any one of paragraphs. 8-11, where the product stream additionally contains 1-hexene, the selectivity for 1-octene is higher than 60 wt. % and the weight ratio of 1-hexene to 1-octene is less than 0.3. 13. Method according to any one of paragraphs. 8-12, in which a substance insoluble in the solvent is formed in an amount of less than 2 wt. %. 14. The method according to claim 13, where the catalyst composition contains a ligand having the structure: . 15. Method according to any one of paragraphs. 8-14, in which the catalyst composition contains a chromium (III) compound, an activator, a cocatalyst and a ligand having the structure: . 16. Method according to any one of paragraphs. 8-15, where contacting occurs at a temperature from 15 to 100°C, preferably from 40 to 70°C. 17. Method according to any one of paragraphs. 8-16, where contacting involves applying a pressure of at least 2 MPa or from 2 to 20 MPa, preferably from 2 to 7 MPa.

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