JP7811458B2 - Porous material for olefin polymerization catalyst, olefin polymerization catalyst, and method for producing olefin polymer - Google Patents

Description

The present invention relates to porous materials for use in olefin polymerization catalysts, and more specifically to porous coordination polymers for use in olefin polymerization catalysts and their uses.

Porous coordination polymers (PCPs) are materials with porous structures formed using coordination bonds between metal ions and organic materials, and are being considered for use in fields such as adsorbents and catalysts.

For example, there have been reports of porous coordination polymers being used as catalysts for olefin polymerization. Patent Document 1 describes a reaction product between an MOF using a Group 4 metal such as hafnium and a single-site zirconium-benzyl derivative, and a method of polymerizing an alkene by contacting this reaction product with the alkene.

International Publication No. 2016/25624

However, conventional olefin polymerization methods using porous coordination polymers as catalysts have room for further improvement in terms of polymerization activity.
In view of the above-mentioned conventional techniques, an object of the present invention is to provide a novel porous coordination polymer for use as an olefin polymerization catalyst, which can produce an olefin polymer with high polymerization activity when used as an olefin polymerization catalyst.

The present invention relates to, for example, the following [1] to [8].
[1]
A porous material (A) for use as an olefin polymerization catalyst is a porous coordination polymer composed of a Group 4 transition metal ion cluster and an organic ligand (L), and satisfies the following requirements (α-1) and (α-2):
(α-1) The specific surface area measured by the BET multipoint method is 500 m ² /g or more and 4000 m ² /g or less.
(α-2) The molar ratio of halogen atoms to Group 4 transition metal atoms of the periodic table (halogen atoms/Group 4 transition metal atoms of the periodic table) measured by X-ray photoelectron spectroscopy (XPS) is 0.20 or more and 1.0 or less, and the halogen atoms are chlorine atoms and/or bromine atoms.

[2]
The porous material (A) for an olefin polymerization catalyst according to [1], wherein at least one of the organic ligands (L) is a ligand having two or more carboxy groups in one molecule.

[3]
The porous material (A) for an olefin polymerization catalyst according to the above [1] or [2] further satisfies the following requirement (α-3):
(α-3) The molar ratio of oxygen atoms to transition metal atoms of Group 4 of the periodic table (oxygen atoms/transition metal atoms of Group 4 of the periodic table) measured by X-ray photoelectron spectroscopy (XPS) is 2.5 or more and 4.5 or less.

[4]
The porous material (A) for an olefin polymerization catalyst according to any one of [1] to [3] above, wherein the specific surface area is 1000 m ² /g or more and 4000 ^{m 2} /g or less.

[5]
An olefin polymerization catalyst comprising the porous material (A) for an olefin polymerization catalyst according to any one of [1] to [4] above.

[6]
The olefin polymerization catalyst according to [5] above, further comprising at least one component (B) selected from the group consisting of the following (β-1) and (β-2):
(β-1) An organoaluminum compound represented by the following general formula (BI): R ^a _m Al(OR ^b ) _n H _p X _q (BI)
[In general formula (B-I), R ^a and R ^b each independently represent a hydrocarbon group having from 1 to 15 carbon atoms, X represents a halogen atom, m represents an integer of from 1 to 3, n represents an integer of from 0 to 2, p represents an integer of from 0 to 2, q represents an integer of from 0 to 2, and m + n + p + q = 3.]
(β-2) Organoaluminum oxy compound

[7]
A method for producing an olefin polymer, comprising a step of polymerizing an olefin in the presence of the olefin polymerization catalyst according to [5] or [6] above.

[8]
The method for producing an olefin polymer according to [7] above, wherein the step of polymerizing an olefin is a step of homopolymerizing ethylene or a step of copolymerizing ethylene with a linear or branched α-olefin having from 3 to 30 carbon atoms.

When the porous material (A) for use as an olefin polymerization catalyst of the present invention is used as an olefin polymerization catalyst, olefin polymers can be produced with higher polymerization activity than in olefin polymerization using conventional porous coordination polymers as catalysts.

The present invention will now be described in further detail.
[Porous material (A) for olefin polymerization catalyst]
The porous material (A) for an olefin polymerization catalyst of the present invention (hereinafter also simply referred to as "porous material (A)") is a porous coordination polymer used in olefin polymerization, which is composed of a Group 4 transition metal ion cluster and an organic ligand (L), and satisfies the requirements (α-1) and (α-2) described below.

<Periodic Table Group 4 Transition Metal Ion Cluster>
Examples of the transition metals of Group 4 of the periodic table contained in the transition metal ion clusters of Group 4 of the periodic table (hereinafter also simply referred to as "metal ion clusters") include titanium (Ti), zirconium (Zr), and hafnium (Hf), and zirconium (Zr) and hafnium (Hf) are preferred because they facilitate the production of porous coordination polymers having stable structures. These may be used alone or in combination of two or more.

Examples of the metal ion cluster structure include a structure represented by M ₆ O _8-x (OH) _x (M is a transition metal atomic ion of Group 4 of the periodic table, and x is an integer of 0 to 8) and a structure described in Coordination Chemistry Reviews 359 (2018) 80-101, and a specific example of the former is a structure represented by M ₆ (μ ³ -O) ₄ (μ ³ -OH) ₄ (M is a transition metal atomic ion of Group 4 of the periodic table).

<Organic ligand (L)>
The organic ligand (L) is an organic ligand that bonds the metal ion clusters together. Examples of the organic ligand include polycarboxylic acids such as dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids. These may be used alone or in combination of two or more.

(dicarboxylic acid)
Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2,5-diaminoterephthalic acid, 2,5-dihydroxyterephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 4-(4-carboxyphenyl)-3-fluorobenzoic acid, 4,4'-(ethyne-1,2-diyl)dibenzoic acid, [1,1':4',1''-terphenyl]-4,4''-dicarboxylic acid, 2',5'-dimethyl-[1,1':4',1''-terphenyl]-4,4''-dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, fumaric acid, malonic acid, adipic acid, and derivatives thereof. These may be used alone or in combination of two or more.

Of the above-mentioned compounds, terephthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-(ethyne-1,2-diyl)dibenzoic acid, [1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid, and derivatives thereof, such as 4-(4-carboxyphenyl)-3-fluorobenzoic acid and 2',5'-dimethyl-[1,1':4',1"-terphenyl]-4,4"-dicarboxylic acid, are preferred from the viewpoint of polymerization activity during olefin polymerization, which will be described later.

(tricarboxylic acid)
Examples of tricarboxylic acids include biphenyl-3,4',5-tricarboxylic acid, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, 1,3,5-tris(4-carboxyphenyl)benzene, 1,3,5-benzenetricarboxylic acid, 5'-(4-carboxyphenyl)-2',4',6'-trimethyl-[1,1':3',1''-terphenyl]-4,4''-dicarboxylic acid, 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tricarboxylic acid, and derivatives thereof. These may be used alone or in combination of two or more.

(Tetracarboxylic acid)
Examples of tetracarboxylic acids include p-terphenyl-3,3',5,5'-tetracarboxylic acid (also known as 5,5'-(1,4-phenylene)bisisophthalic acid), 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 4,4',4'',4''-(pyrene-1,3,6,8-tetrayl)tetrabenzoic acid, and derivatives thereof. These may be used alone or in combination of two or more.

(amine compounds)
Examples of the organic ligand (L), in addition to the above-mentioned dicarboxylic acids, include imidazoles such as imidazole, 2-methylimidazole, and 2-phenylimidazole, and derivatives thereof; compounds having a pyridine ring such as 4,4'-bipyridine, 1,4-bis(4-pyridyl)benzene, 2,2'-dimethyl-4,4'-bipyridine, 1,4-bis(4-pyridyl)butadiyne, 1,2-bis(4-pyridyl)ethane, and 3,6-di(4-pyridyl)-1,2,4,5-tetrazine, and derivatives thereof; compounds having a pyrazine ring such as pyrazine and 2,5-dimethylpyrazine, and derivatives thereof; and cyclic amines such as 1,4-diazabicyclo[2.2.2]octane, other than those mentioned above, and derivatives thereof.

Of these organic ligands (L), the above-mentioned dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids are preferred, with dicarboxylic acids being more preferred, because they make it easier to obtain porous coordination polymers with stable structures.

[Porous coordination polymer]
The porous coordination polymer is a porous crystalline material composed of an organic ligand (L) and a metal ion cluster occupying the central position of the structure to which the organic ligand (L) is coordinated, and is also called a metal organic framework (MOF).

Since the metal ion cluster has a positive charge, the organic ligand (L) is not necessarily in the state of the above-mentioned compound itself. For example, in the case of a carboxylic acid, the carboxy group is in a deprotonated state and coordinated to the metal ion cluster, more specifically, to the transition metal ion of Group 4 of the periodic table that constitutes the metal ion cluster.
In the porous coordination polymer, a monocarboxylic acid that may be used in the manufacturing process may be coordinated to a transition metal ion of Group 4 of the periodic table.

[Requirements (α-1) to (α-3)]
The porous material (A) according to the present invention satisfies the following requirements (α-1) and (α-2).

Requirements (α-1):
Requirement (α-1) is that the specific surface area measured by the BET multipoint method is 500 m ² /g or more and 4000 m ² /g or less, preferably 1000 m ² /g or more and 4000 ^{m 2} /g or less, more preferably 1000 m ² /g or more and 3000 m ² /g or less.

Requirements (α-2):
Requirement (α-2) is that the molar ratio of halogen atoms to Group 4 transition metal atoms of the periodic table ((halogen atoms/Group 4 transition metal atoms of the periodic table)) measured by X-ray photoelectron spectroscopy (XPS) is 0.20 or more and 1.0 or less, and the halogen atoms are chlorine atoms and/or bromine atoms (hereinafter, this molar ratio will also be referred to as the "(Cl+Br)/M ratio"). The (Cl+Br)/M ratio is preferably 0.20 or more and 0.70 or less, and more preferably 0.20 or more and 0.50 or less.

That is, it is believed that the porous material of the present invention contains the halogen atoms, and that the halogen atoms are bonded to some of the Group 4 transition metal atoms of the periodic table.
The halogen atom is a chlorine atom and/or a bromine atom, preferably a chlorine atom or a chlorine atom and a bromine atom, and more preferably a chlorine atom.
The porous material (A) preferably further satisfies the following requirement (α-3).

Requirements (α-3):
Requirement (α-3) is that the molar ratio of oxygen atoms to Group 4 transition metal atoms of the periodic table (oxygen atoms/Group 4 transition metal atoms of the periodic table, hereinafter also referred to as "O/M ratio") measured by X-ray photoelectron spectroscopy (XPS) is 2.5 or more and 4.5 or less. The O/M ratio is preferably 3.0 or more and 4.5 or less, and more preferably 3.3 or more and 4.5 or less.

<<Method for measuring O/M ratio and (Cl+Br)/M ratio>>
Measurement of the O/M ratio and the (Cl+Br)/M ratio by X-ray photoelectron spectroscopy (XPS) is carried out as follows.

The measurement sample is handled in a nitrogen atmosphere, and monochromatic AlKα is used as the X-ray source, and charge correction and neutralization are performed during measurement.
The oxygen atomic concentration (atomic %) is determined from the peak area of the O1s narrow spectrum, the chlorine atomic concentration (atomic %) from the peak area of the Cl2s narrow spectrum, and the bromine atomic concentration (atomic %) from the peak area of the Br3d narrow spectrum.

For the atomic concentration (Atomic %) of transition metals from Group 4 of the periodic table, the titanium atomic concentration (Atomic %) is calculated from the peak area of the Ti2p narrow spectrum, the zirconium atomic concentration (Atomic %) is calculated from the peak area of the Zr3d narrow spectrum, and the hafnium atomic concentration (Atomic %) is calculated from the peak area of the Hf4f narrow spectrum.

Based on these atomic concentrations, the O/M ratio and the (Cl+Br)/M ratio are calculated using the following formulas.
O/M ratio = oxygen atom concentration / periodic table group 4 transition metal atom concentration (Cl + Br)/M ratio = (chlorine atom concentration + bromine atom concentration) / periodic table group 4 transition metal atom concentration

Examples of the form of the porous material (A) include powder and molded bodies.
Examples of the shape of the molded body include a sphere, a pellet, a cylinder, a ring, a wheel, and a granule.

(Method for producing porous material (A))
As a method for producing the porous material (A) of the present invention, a conventionally known method for producing a porous coordination polymer can be appropriately adopted, except that the production conditions are adjusted so as to satisfy the above requirements (α-1) to (α-2), and preferably also the above requirement (α-3).
A method in which two types of solutions, a solution containing a transition metal ion of Group 4 of the periodic table and a solution containing the above-mentioned organic ligand, are gradually diffused and reacted at the liquid-liquid interface;
a method of adding the organic ligand or a solution thereof to a solution containing a transition metal ion of Group 4 of the periodic table and reacting the organic ligand with stirring;
One example of such a method is to react a solution containing a transition metal ion of Group 4 of the periodic table and the above-mentioned organic ligand in a pressure vessel.

Sources of Group 4 transition metals in the periodic table include chlorides (titanium chloride, zirconium chloride, hafnium chloride), bromides (zirconium bromide, titanium bromide), oxychlorides (titanium oxychloride, zirconium oxychloride, hafnium oxychloride, and their hydrates).

In these methods, the value of the specific surface area in the above requirement (α-1) can be adjusted by changing the type of organic ligand.
Furthermore, in order to satisfy the above requirement (α-2), and preferably also the requirement (α-3), a source of oxygen atoms and a source of chlorine atoms or bromine atoms are first required. Examples of the source of oxygen atoms include organic ligands having oxygen atoms, such as dicarboxylic acid compounds, tricarboxylic acid compounds, and tetracarboxylic acid compounds, monocarboxylic acid compounds described below, solvents consisting of compounds having oxygen atoms, and water. Examples of the source of chlorine atoms or bromine atoms include chlorides, bromides, and oxychlorides of transition metals of Group 4 of the periodic table, as well as hydrogen chloride, hydrogen bromide, and aqueous solutions thereof.

Next, by shortening the time for reacting the raw material of the transition metal of Group 4 of the periodic table with the organic ligand, the (Cl+Br)/M ratio in the above requirement (α-2) tends to increase.
More specific examples of manufacturing methods include:
a step (i) of mixing a raw material of a transition metal of Group 4 of the periodic table, a solvent (e.g., N,N-dimethylformamide), and hydrochloric acid to prepare a solution containing a transition metal ion of Group 4 of the periodic table;
(ii) a step of mixing the solution with an organic ligand and a solvent (e.g., N,N-dimethylformamide), and stirring the resulting mixed solution at, for example, 25 to 250°C, preferably 50 to 200°C, for, for example, 1 to 15 hours, preferably 3 to 10 hours, to react the Group 4 transition metal ion with the organic ligand; and (iii) an optional post-treatment step of washing, drying, calcining, etc.
The porous material (A) of the present invention can be produced by a method comprising the steps of:

When preparing the mixed solution in step (ii), a monocarboxylic acid is preferably mixed as the organic ligand in addition to the organic ligand (L). The addition of a monocarboxylic acid promotes the formation of Group 4 transition metal ion clusters. The monocarboxylic acid can be removed by washing in the post-treatment step (iii).

Examples of monocarboxylic acids include formic acid (which can be produced in step (i) by reacting N,N-dimethylformamide with hydrochloric acid), acetic acid, benzoic acid, biphenylcarboxylic acid, and derivatives thereof. These may be used alone or in combination of two or more.

In the post-treatment step (iii), for example, the solid component is separated from the reaction solution by centrifugation or the like, washed, and then dried or calcined at room temperature or with heat under atmospheric or reduced pressure to remove the solvent, water, monocarboxylic acid, excess organic ligand (L), and other components contained in the porous material. The lower the pressure or temperature at which the drying or calcination is performed, or the lower the molecular weight of the components contained, the smaller the O/M ratio in the above requirement (α-3) tends to be.

[Olefin polymerization catalyst]
The olefin polymerization catalyst according to the present invention comprises the porous material (A) according to the present invention, and preferably further comprises at least one component (B) selected from the group consisting of the following (β-1) and (β-2):
(β-1) An organoaluminum compound represented by the following general formula (BI): R ^a _m Al(OR ^b ) _n H _p X _q (BI)
[In general formula (B-I), R ^a and R ^b each independently represent a hydrocarbon group having from 1 to 15 carbon atoms, X represents a halogen atom, m represents an integer of from 1 to 3, n represents an integer of from 0 to 2, p represents an integer of from 0 to 2, q represents an integer of from 0 to 2, and m + n + p + q = 3.]
(β-2) Organoaluminum Oxy Compound The olefin polymerization catalyst of the present invention may further contain (C) a carrier, and may further contain (D) an organic compound, if necessary.

Organoaluminum Compound (β-1)
Examples of organoaluminum compound (β-1) (hereinafter also referred to as "component (β-1)") include:
tri-n-alkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum, tri-n-butylaluminum, tripentylaluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum;
tri-branched alkylaluminums such as triisopropylaluminum, triisobutylaluminum, trisec-butylaluminum, tritert-butylaluminum, tri-2-methylbutylaluminum, tri-3-methylbutylaluminum, tri-2-methylpentylaluminum, tri-3-methylpentylaluminum, tri-4-methylpentylaluminum, tri-2-methylhexylaluminum, tri-3-methylhexylaluminum, and tri-2-ethylhexylaluminum;
tricycloalkylaluminums such as tricyclohexylaluminum and tricyclooctylaluminum;
triarylaluminum such as triphenylaluminum and tritolylaluminum;
dialkylaluminum hydrides such as diisobutylaluminum hydride;
alkylaluminum alkoxides such as isobutylaluminum methoxide, isobutylaluminum ethoxide, and isobutylaluminum isopropoxide;
dialkylaluminum alkoxides such as dimethylaluminum methoxide, diethylaluminum ethoxide, and dibutylaluminum butoxide;
alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide;
dialkylaluminum aryloxides such as diethylaluminum phenoxide, diethylaluminum (2,6-di-t-butyl-4-methylphenoxide), ethylaluminum bis(2,6-di-t-butyl-4-methylphenoxide), diisobutylaluminum (2,6-di-t-butyl-4-methylphenoxide), and isobutylaluminum bis(2,6-di-t-butyl-4-methylphenoxide);
dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide, and diisobutylaluminum chloride;
alkylaluminum sesquihalides such as ethylaluminum sesquichloride, butylaluminum sesquichloride, and ethylaluminum sesquibromide;
partially halogenated alkylaluminums such as alkylaluminum dihalides such as ethylaluminum dichloride, propylaluminum dichloride, butylaluminum dibromide, etc.;
Dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride;
Other partially hydrogenated alkylaluminums (other than dialkylaluminum hydrides), such as alkylaluminum dihydrides such as ethylaluminum dihydride and propylaluminum dihydride;
Partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxychloride, butylaluminum butoxychloride, and ethylaluminum ethoxybromide are included.
The organoaluminum compound (β-1) may be used alone or in combination of two or more kinds.

Organoaluminum oxy compound (β-2)
As the organoaluminum oxy compound (β-2) (hereinafter also referred to as "component (β-2)"), a conventionally known aluminoxane can be used as it is. Specifically, aluminoxanes represented by the following general formula [B-II1] can be used.

and/or the following general formula [B-II2]

(wherein R is a hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 or more), benzene-insoluble organoaluminum oxy compounds described in JP-A Nos. 2-78687 and 2-167305, and aluminoxanes having two or more types of alkyl groups described in JP-A No. 3-103407.
Further, examples of the organoaluminum oxy compound (β-2) include modified methylaluminoxanes represented by the following general formula [B-II3].

(In the formula, R represents a hydrocarbon group having 1 to 10 carbon atoms, and m and n each independently represent an integer of 2 or greater.)
This modified methylaluminoxane is prepared using trimethylaluminum and an alkylaluminum other than trimethylaluminum. Such compounds are generally called MMAO. Such MMAO can be prepared by the methods described in U.S. Patent Nos. 4,960,878 and 5,041,584.
Further, the organoaluminum oxy compound (β-2) may also include a boron-containing organoaluminum oxy compound represented by the following general formula [B-II4]:

(In the formula, ^Rc represents a hydrocarbon group having 1 to 10 carbon atoms. ^Rd may be the same or different and represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms.)
As the organoaluminum oxy compound (β-2), methylaluminoxane, which is a commercially available product and therefore easily available, and MMAO prepared using trimethylaluminum and triisobutylaluminum are preferred. Of these, MMAO, which has improved solubility in various solvents and storage stability, is particularly preferred.
The organoaluminum compound (β-2) may be used alone or in combination of two or more kinds.

(Carrier (C))
The support (C) is an inorganic or organic compound, and is a granular or fine particle solid. It is possible to use a support that has been conventionally used in olefin polymerization using a transition metal compound and a support as catalyst components, such as those described in paragraphs [0220] to [0235] of JP2012-72365A.

(Organic compound component (D))
As a constituent component of the olefin polymerization catalyst, an organic compound component (D) may be used as needed. The organic compound component (D) is used for the purpose of improving the polymerization performance and the physical properties of the resulting polymer. Examples of the organic compound component (D) include alcohols, phenolic compounds, carboxylic acids, phosphorus compounds, amides, polyethers, and sulfonates.

[Production method of olefin polymer]
The method for producing an olefin polymer of the present invention is characterized by polymerizing an olefin in the presence of the above-mentioned olefin polymerization catalyst of the present invention.

In the method for producing an olefin polymer of the present invention, an olefin homopolymer may be produced by polymerizing one type of olefin, or an olefin copolymer may be produced by copolymerizing two or more types of olefins. In this specification, the term "polymerization" is used without any distinction between polymerization and copolymerization, and the term "olefin polymer" is used without any distinction between an olefin homopolymer and an olefin copolymer.

The method of using each component constituting the olefin polymerization catalyst of the present invention and the order of adding them to a polymerization vessel can be selected arbitrarily, but the following method is exemplified: Hereinafter, the porous material (A), component (B), carrier (C), and organic compound component (D) will also be referred to as "components (A) to (D)," respectively.
(1) A method in which component (A) is added alone to a polymerization reactor.
(2) A method in which component (A) and component (B) are added to a polymerization reactor in any order.
(3) A method in which a catalyst component in which component (A) is supported on component (C) and component (B) are added to a polymerization vessel in any order.
(4) A method in which a catalyst component in which component (B) is supported on component (C) and component (A) are added to a polymerization vessel in any order.
(5) A method in which a catalyst component in which component (A) and component (B) are supported on component (C) is added to a polymerization reactor.

In each of the above methods, component (D) may be added at any stage.
In each of the above methods, at least two of the catalyst components may be contacted in advance.
In the above methods (4) and (5) in which component (B) is supported, unsupported component (B) may be added in any order, if necessary. In this case, the components (B) may be the same or different. Furthermore, the solid catalyst component in which component (A) is supported on component (C) and the solid catalyst component in which components (A) and (B) are supported on component (C) may be prepolymerized with an olefin, or the prepolymerized solid catalyst component may have further catalyst components supported thereon.

In the present invention, olefin polymerization can be carried out by either liquid-phase polymerization methods such as solution polymerization and suspension polymerization, or gas-phase polymerization methods. Specific examples of inert hydrocarbon media used in liquid-phase polymerization methods include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene, and dichloromethane, or mixtures thereof. The olefin (monomer) itself to be (co)polymerized can also be used as the solvent.

When olefin polymerization is carried out using the above-mentioned olefin polymerization catalyst, the porous material (A) is used in an amount equivalent to 1× ¹⁰ to 1× ¹⁰ mol, preferably 1× ¹⁰ to 1× ¹⁰ mol, per liter of reaction volume in terms of transition metal atoms in the porous material (A).

The organoaluminum compound (β-1) is used in an amount such that the molar ratio [(β-1)/M] of the organoaluminum compound (β-1) to the total transition metal atoms (M) in the porous material (A) is typically 0.01 to 100,000, preferably 0.05 to 50,000.

The organoaluminum oxy compound (β-2) is used in an amount such that the molar ratio [(β-2)/M] of aluminum atoms in the organoaluminum oxy compound (β-2) to all transition metal atoms (M) in the porous material (A) is typically 10 to 500,000, preferably 20 to 100,000.

The polymerization temperature for olefins using such an olefin polymerization catalyst is usually in the range of -50 to +200°C, preferably 0 to 170°C. The polymerization pressure is usually normal pressure to 100 kgf/ ^cm2 -G, preferably normal pressure to 50 kgf/ ^cm2 -G, and the polymerization reaction can be carried out in any of batch, semi-continuous, and continuous systems. Furthermore, the polymerization can be carried out in two or more stages with different reaction conditions.

The molecular weight of the resulting olefin polymer can be adjusted by adding hydrogen to the polymerization system or by changing the polymerization temperature. It can also be adjusted by the amount of compound (B) used.

<Olefin>
The process for producing an olefin polymer of the present invention is a process for polymerizing an olefin in the presence of the olefin polymerization catalyst of the present invention.

A preferred embodiment of the method for producing an olefin polymer of the present invention is
Examples of the process include a process for producing an olefin polymer, which comprises a step of homopolymerizing ethylene in the presence of the olefin polymerization catalyst of the present invention, and a process for producing an olefin polymer, which comprises a step of copolymerizing ethylene with a linear or branched α-olefin having from 3 to 30 carbon atoms in the presence of the olefin polymerization catalyst of the present invention.

When copolymerization is carried out in the method for producing an olefin polymer of the present invention, the amount of each monomer fed is appropriately set depending on the composition of the olefin polymer to be produced.
The α-olefins include
Examples of linear or branched α-olefins having 3 to 30, preferably 3 to 20, and more preferably 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

These may be used alone or in combination of two or more.
In addition, together with ethylene and the above-mentioned α-olefins, small amounts (for example, 1 mol % or less) of other monomers (for example, cyclic olefins, non-conjugated polyenes) may be copolymerized.

The olefin polymer produced by the process for producing an olefin polymer of the present invention has a high molecular weight and a broad molecular weight distribution.
When the porous material (A) of the present invention is used as an olefin polymerization catalyst, an olefin polymer can be produced with higher polymerization activity than when a conventional MOF is used as an olefin polymerization catalyst. The reason for this is not necessarily clear, but is presumed to be as follows.

First, as indicated by requirement (α-1), porous material (A) has a large specific surface area, resulting in high contact efficiency with olefin monomers, and as indicated by requirement (α-2), it contains many Group 4 transition metal atoms that serve as polymerization active centers. Furthermore, by preferably satisfying requirement (α-3), i.e., by containing many coordinatively unsaturated Group 4 transition metal atoms, the reactivity (acidity) of the entire metal ion cluster is enhanced. For these reasons, it is believed that using porous material (A) according to the present invention as an olefin polymerization catalyst will enable the production of olefin polymers with high polymerization activity.

The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples in any way.

[Measurement method]
The various measurement methods are as follows:

(Measurement of Porous Materials)
≪Specific surface area≫
The specific surface area of the porous material was measured by measuring the adsorption/desorption isotherm using a nitrogen gas adsorption method (Microtrac-Bell "BELSORP-max") at liquid nitrogen temperature. The specific surface area was determined using the multipoint method specified in JIS Z8830:2013.

<O/M ratio and (Cl+Br)/M ratio>
The O/M ratio and (Cl + Br)/M ratio of the porous material were calculated from the oxygen atom concentration, chlorine atom concentration, and metal atom concentration determined by X-ray photoelectron spectroscopy (XPS) (measurement device: "AXIS-NOVA" manufactured by KRATOS). The sample was handled in a nitrogen atmosphere, and measurements were performed using a monochromated AlKα X-ray source. During measurements, charge correction and neutralization were performed using the charge neutralization function of the measurement device. The oxygen atomic concentration (Atomic %) was determined from the peak area of the O1s narrow spectrum, the chlorine atomic concentration (Atomic %) from the peak area of the Cl2s narrow spectrum, the zirconium atomic concentration (Atomic %) from the peak area of the Zr3d narrow spectrum, and the hafnium atomic concentration (Atomic %) from the peak area of the Hf4f narrow spectrum, and the oxygen atom (O)/Group 4 transition metal (Zr, Hf) atomic ratio and the chlorine atom (Cl)/Group 4 transition metal (Zr, Hf) atomic ratio were calculated.

(Measurement of Olefin Polymer)
<<Weight average molecular weight (Mw), molecular weight distribution (Mw/Mn)>>
The weight average molecular weight (Mw), number average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the olefin polymer were determined by gel permeation chromatography (GPC). Specifically, they were calculated from the molecular weight distribution curve obtained by a gel permeation chromatograph (high temperature size exclusion chromatograph) "Alliance GPC 2000" manufactured by Waters Corporation, and the operating conditions were as follows:
Analysis software: Chromatography Data System Empower (Waters)
Column: TSKgel GMH6-HT x 2 + TSKgel GMH6-HT x 2
(Inner diameter 7.5 mm x length 30 cm, Tosoh Corporation)
Mobile phase: o-dichlorobenzene Detector: differential refractometer (built-in)
Column temperature: 140°C
Flow rate: 1.0mL/min Injection volume: 400μL
Sampling time interval: 1 second Sample concentration: 0.15% (w/v)
Molecular weight calibration: Monodisperse polystyrene (Tosoh Corporation) / molecular weight 495 to 20.6 million

<Melting point (Tm)>
Using an SII RDC220 differential scanning calorimeter, approximately 5 mg of sample was heated from 30°C to 200°C at a heating rate of 50°C/min under a nitrogen atmosphere and held at that temperature for 10 minutes. The sample was then cooled to 30°C at a heating rate of 10°C/min, held at that temperature for 5 minutes, and then heated to 200°C at a heating rate of 10°C/min. The endothermic peak observed during this second heating was taken as the melting peak, and the temperature at which the melting peak (the highest peak if multiple peaks were present) appeared was determined as the melting point (Tm).

[Preparation of porous materials, etc.]
<Raw materials>
As raw materials for the porous material, the following metal sources (M-1) to (M-3) containing Group 4 transition metals of the periodic table and the following organic ligands (L-1) to (L-7) were used. In addition to the raw materials for the porous material, the following metal source (M-4) was also prepared.
Metal source (M-1): Fujifilm Wako Pure Chemical Industries, Ltd. Zirconium (IV) chloride
Metal source (M-2): Fujifilm Wako Pure Chemical Industries, Ltd., Zirconium oxide chloride octahydrate, Wako special grade Metal source (M-3): Aldrich Corporation, Hafnium (IV) chloride 99.9% trace metals basis
Metal source (M-4): Fujifilm Wako Pure Chemical Industries, Ltd. Zirconium oxide nanoparticles (10 nm)
・Organic ligand (L-1): Tokyo Chemical Industry Co., Ltd. 4,4'-Biphenyldicarboxylic Acid
・Organic ligand (L-2): Combi-Blocks 4-(4-Carboxyphenyl)-3-fluorobenzoic acid
Organic Ligand (L-3): Terephthalic Acid (Wako Pure Chemical Industries, Ltd.) Organic Ligand (L-4): 4,4'-(Ethyne-1,2-diyl)dibenzoic Acid (Combi-Blocks)
Organic ligand (L-5): 2',5'-dimethyl-[1,1':4',1''-terphenyl]-4,4''-dicarboxylic acid synthesized by the method described in J. Am. Chem. Soc. 2012, 134, 36, 14690-14693
・Organic ligand (L-6): BLDpharm 4,4',4'',4'''-(Pyrene-1,3,6,8-tetrayl)tetrabenzoic acid
Monocarboxylic acid: FUJIFILM Wako Pure Chemical Corporation, acetic acid, reagent grade

<Example A1>
A 200 mL reactor was charged with a rotor, 201 mg of metal source (M-1), 15 mL of N,N-dimethylformamide, and 1.5 mL of hydrochloric acid (concentration 35-37%), followed by 10 minutes of ultrasonic irradiation. To this was added 270 mg of organic ligand (L-1) and 30 mL of N,N-dimethylformamide, followed by 10 minutes of ultrasonic irradiation. The mixture was heated to 80°C while stirring with a rotor, and stirring was continued for 5 hours. The mixture was then cooled to room temperature and stirring was stopped. The liquid and solid components in the reactor were transferred to a centrifuge tube and centrifuged, after which the supernatant was removed by decantation. After further washing with N,N-dimethylformamide and ethanol, the solid components were transferred to a Schlenk flask and dried under reduced pressure at 200°C for 4 hours, followed by cooling to room temperature under a nitrogen atmosphere to prepare 110 mg of porous material (A-1).

<Example A2>
115 mg of porous material (A-2) was prepared in the same manner as in Example A1, except that 290 mg of organic ligand (L-2) was used instead of 270 mg of organic ligand (L-1).

<Example A3>
75 mg of porous material (A-3) was prepared in the same manner as in Example A1, except that 185 mg of organic ligand (L-3) was used instead of 270 mg of organic ligand (L-1).

<Example A4>
142 mg of porous material (A-4) was prepared in the same manner as in Example A1, except that 300 mg of organic ligand (L-4) was used instead of 270 mg of organic ligand (L-1).

<Example A5>
266 mg of porous material (A-5) was prepared in the same manner as in Example A1, except that 395 mg of organic ligand (L-5) was used instead of 270 mg of organic ligand (L-1) and the mixture was stirred at 80° C. for 8 hours.

<Example A6>
192 mg of porous material (A-6) was prepared in the same manner as in Example A1, except that 195 mg of organic ligand (L-6) was used instead of 270 mg of organic ligand (L-1).

<Example A7>
113 mg of porous material (A-7) was prepared in the same manner as in Example A1, except that 270 mg of organic ligand (L-1) was replaced with 270 mg of organic ligand (L-1) and 273 mg of acetic acid.

<Example A8>
150 mg of porous material (A-8) was prepared in the same manner as in Example A1, except that 261 mg of metal source (M-2) was used instead of 201 mg of metal source (M-1).

<Example A9>
162 mg of porous material (A-9) was prepared in the same manner as in Example A1, except that 276 mg of metal source (M-3) was used instead of 201 mg of metal source (M-1).

<Comparative Example a1>
238 mg of porous material (A'-1) was prepared in the same manner as in Example A1, except that the stirring time after raising the temperature to 80°C was changed to 20 hours.

<Comparative example a2>
263 mg of porous material (A'-2) was prepared in the same manner as in Example A6, except that the stirring time after raising the temperature to 80°C was changed to 20 hours.

<Comparative example a3>
The metal source (M-4) was transferred to a Schlenk flask and dried under reduced pressure at 200°C for 4 hours, and then cooled to room temperature under a nitrogen atmosphere to prepare a material (hereinafter also referred to as "porous material" for convenience) (A'-3).

The production conditions, yield, specific surface area, O/M ratio, and (Cl+Br)/M ratio of the porous materials (A-1) to (A-9) and (A'-1) to (A'-3) are shown in Table 1. Since the porous materials (A-1) to (A-9) and (A'-1) to (A'-2) have a high specific surface area, they can all be said to form a porous coordination polymer composed of a metal ion cluster (basically represented by M ₆ (μ ³ -O) ₄ (μ ³ -OH) ₄ (M is Zr or Hf)) and an organic ligand (L).

[Production of olefin polymer]
<Example P1>
500 mL of heptane was added to a 1-liter SUS autoclave reactor that had been thoroughly purged with nitrogen under a nitrogen atmosphere, and then ethylene was passed through to saturate the reactor with ethylene. Next, 0.375 mL of a decane solution of triisobutylaluminum (1.0 mol/L in terms of Al) and 50 mg of the porous material (A-1) obtained in Example A1 were charged into the reactor. The temperature and pressure were then increased to 80°C and 0.8 MPaG using ethylene, and a polymerization reaction was carried out for 60 minutes at a rotation speed of 350 rpm. After completion of the reaction, the contents of the reactor were filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Examples P2 to P9>
A polymerization reaction was carried out in the same manner as in Example P1, except that 50 mg of each of the porous materials (A-2) to (A-9) obtained in Examples A2 to A9 was used instead of the porous material (A-1). After completion of the reaction, the content in the reactor was filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Comparative examples p1 to p3>
A polymerization reaction was carried out in the same manner as in Example P1, except that 50 mg of each of the porous materials (A'-1) to (A'-3) obtained in Comparative Examples a1 to a3 was used instead of the porous material (A-1). After completion of the reaction, the content in the reactor was filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Example P10>
A polymerization reaction was carried out in the same manner as in Example P1, except that 0.375 mL of a decane solution of triethylaluminum (1.0 mol/L in terms of Al) was used instead of the decane solution of triisobutylaluminum. After completion of the reaction, the contents in the reactor were filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Example P11>
A polymerization reaction was carried out in the same manner as in Example P1, except that 0.375 mL of a toluene solution of methylaluminoxane (MAO) (1.0 mol/L in terms of Al) was used instead of the decane solution of triisobutylaluminum. After completion of the reaction, the contents in the reactor were filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Example P12>
500 mL of heptane was added to a 1-liter SUS autoclave reactor that had been thoroughly purged with nitrogen under a nitrogen atmosphere, and then ethylene was passed through to saturate the reactor with ethylene. Next, 10 mL of 1-hexene, 0.375 mL of a decane solution of triisobutylaluminum (1.0 mol/L in terms of Al), and 50 mg of the porous material (A-1) obtained in Example A1 were charged into the reactor. The temperature and pressure were then increased to 80°C and 0.8 MPaG using ethylene, and a polymerization reaction was carried out for 60 minutes at a rotation speed of 350 rpm. After completion of the reaction, the contents of the reactor were filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

<Example P13>
500 mL of heptane was added to a 1-liter SUS autoclave reactor that had been thoroughly purged with nitrogen under a nitrogen atmosphere, and then ethylene was passed through to saturate the reactor with ethylene. Next, 0.375 mL of a decane solution of triisobutylaluminum (1.0 mol/L in terms of Al) and 50 mg of the porous material (A-1) obtained in Example A1 were charged into the reactor. The reactor was then heated and pressurized to 80°C and 0.8 MPaG using an ethylene/hydrogen mixed gas with a hydrogen concentration of 0.10 vol%, and a polymerization reaction was carried out for 60 minutes at a rotation speed of 350 rpm. After completion of the reaction, the contents of the reactor were filtered and dried under reduced pressure at 80°C for 10 hours to obtain an olefin polymer having the physical properties shown in Table 2.

Claims (7)

a porous coordination polymer composed of a Group 4 transition metal ion cluster and an organic ligand (L);
Contains halogen atoms,
Satisfy the following requirements (α-1) and (α-2),
The periodic table group 4 transition metal ion cluster is
M ₆ O _8-x (OH) _x
(M is a transition metal atom ion of Group 4 of the periodic table, and x is an integer of 0 to 8.)
It has a structure represented by
At least one of the organic ligands (L) is selected from a ligand having two or more carboxy groups in one molecule and an amine compound;
the amine compound is selected from imidazole, 2-methylimidazole, 2-phenylimidazole, 4,4′-bipyridine, 1,4-bis(4-pyridyl)benzene, 2,2′-dimethyl-4,4′-bipyridine, 1,4-bis(4-pyridyl)butadiyne, 1,2-bis(4-pyridyl)ethane, 3,6-di(4-pyridyl)-1,2,4,5-tetrazine, pyrazine, 2,5-dimethylpyrazine, and 1,4-diazabicyclo[2.2.2]octane;
Porous material for olefin polymerization catalyst (A).
(α-1) The specific surface area measured by the BET multipoint method is 500 m ² /g or more and 4000 m ² /g or less.
(α-2) The molar ratio of halogen atoms to Group 4 transition metal atoms of the periodic table (halogen atoms/Group 4 transition metal atoms of the periodic table) measured by X-ray photoelectron spectroscopy (XPS) is 0.20 or more and 1.0 or less, and the halogen atoms are chlorine atoms and/or bromine atoms. The porous material (A) for an olefin polymerization catalyst according to claim 1 , further satisfying the following requirement (α-3):
(α-3) The molar ratio of oxygen atoms to transition metal atoms of Group 4 of the periodic table (oxygen atoms/transition metal atoms of Group 4 of the periodic table) measured by X-ray photoelectron spectroscopy (XPS) is 2.5 or more and 4.5 or less. 3. The porous material (A) for use as an olefin polymerization catalyst according to claim 1 , wherein the specific surface area is 1000 m ² /g or more and 4000 ^{m 2} /g or less. An olefin polymerization catalyst comprising the porous material (A) for an olefin polymerization catalyst according to any one of claims 1 to 3 . The olefin polymerization catalyst according to claim 4 , further comprising at least one component (B) selected from the group consisting of the following (β-1) and (β-2):
(β-1) An organoaluminum compound represented by the following general formula (BI): R ^a _m Al(OR ^b ) _n H _p X _q (BI)
[In general formula (B-I), R ^a and R ^b each independently represent a hydrocarbon group having from 1 to 15 carbon atoms, X represents a halogen atom, m represents an integer of from 1 to 3, n represents an integer of from 0 to 2, p represents an integer of from 0 to 2, q represents an integer of from 0 to 2, and m + n + p + q = 3.]
(β-2) Organoaluminum oxy compound A method for producing an olefin polymer, comprising a step of polymerizing an olefin in the presence of the olefin polymerization catalyst according to claim 4 or 5 . 7. The method for producing an olefin polymer according to claim 6 , wherein the step of polymerizing an olefin is a step of homopolymerizing ethylene or a step of copolymerizing ethylene with a linear or branched α-olefin having from 3 to 30 carbon atoms.