A method for preparing a mono-titaniumocene catalyst and its application in olefin polymerization

Abstract

The present invention provides a monotitalocene catalyst as shown in formula I. The monotitalocene catalyst synthesized by the present invention belongs to a constrained geometry catalyst (CGC), and the introduction of a quinoline ring makes the monotitalocene catalyst have the advantages of high catalytic activity and good thermal stability. The monotitalocene catalyst synthesized by the present invention is used in combination with a co-catalyst (one or more of an organoaluminum compound or an organoboron compound) to efficiently catalyze the homopolymerization or copolymerization of olefin monomers. Formula I.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical catalysts, and particularly relates to a preparation method of a monotitalocene catalyst and its application in olefin polymerization. Background Art

[0002] Polyolefins are widely used in the industrial field, such as the development of new resins, rubber materials and plastic products, etc.

[0003] Currently, metallocene catalysts have been proven to be highly efficient in catalyzing olefin polymerization, and their structures have the unique single active site characteristics of transition metals, which makes it easy to regulate the molecular structure of polymers to obtain polyolefin materials with different properties.

[0004] Among them, a class of constrained geometry catalysts (CGC) among metallocene catalysts has a structural feature that one end of the transition metal is connected to cyclopentadiene or a cyclopentadiene derivative, and the other end is connected to a heteroatom group, and the groups at both ends are further connected by a bridge group. This semi-sandwich structure improves the thermal stability, catalytic activity, and stereoselectivity of the metallocene catalyst, making the application of metallocene catalysts in olefin polymerization more extensive.

[0005] Therefore, the development of new single metallocene catalysts is beneficial to provide technical reserves for olefin polymerization processes and applications. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a mono-titaniumocene catalyst and its application in olefin polymerization.

[0007] The present invention provides a mono-titanium-based catalyst, wherein the molecular structure of the mono-titanium-based catalyst is as shown in Formula I:

[0008] Formula I,

[0009] Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10 A straight chain, branched or isomerized alkyl group; or, R1 is a methyl group or a phenyl group, and R2 is a methyl group or a phenyl group.

[0010] The present invention also provides a method for preparing a monoclinocene-containing bridged ligand for obtaining the above-mentioned monoclinocene titanocene catalyst. The molecular structure of the ligand is shown in Formula II:

[0011] Formula II,

[0012] Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10A straight chain, branched or isomerized alkyl group; or, R1 is a methyl group or a phenyl group, and R2 is a methyl group or a phenyl group.

[0013] The mono-titaniumocene catalyst and the co-catalyst together form a catalytic system, which is applied in olefin polymerization such as ethylene homopolymerization, propylene homopolymerization and ethylene and 1-octene copolymerization.

[0014] The monotitanium ocene catalyst provided by the invention belongs to a restricted geometry catalyst and has good thermal stability, catalytic activity and stereoselectivity. The olefin polymer obtained by the catalytic system has the advantages of higher molecular weight and narrow molecular weight distribution.

[0015] Other features and advantages of the present invention will be described in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to better understand the preparation method of the mono-titaniumocene catalyst of the present invention, the accompanying drawings provide a reaction flow chart.

[0017] Figure 1 It is a reaction flow chart of preparing a mono-titaniumocene catalyst according to the present invention. Implementation

[0018] The present invention will be described in detail below through specific implementation methods and examples, and the features and advantages of the present invention will be fully and clearly presented. It should be understood that the described specific implementation methods and examples are only a part of the present invention listed, which are only used for explanation and description, but not for limiting the present invention.

[0019] The molecular structure of the mono-titanium ocene catalyst provided by the present invention is shown in Formula I:

[0020] Formula I,

[0021] Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10 A straight chain, branched or isomerized alkyl group; or, R1 is a methyl group or a phenyl group, and R2 is a methyl group or a phenyl group.

[0022] Among them, the C1~C 10 The straight chain, branched or isomerized alkyl group may include, but is not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

[0023] Preferably, R1 is methyl, R2 is methyl, and the structure is shown in Formula III; or, R1 is phenyl, R2 is methyl, and the structure is shown in Formula IV; or, R1 and R2 are phenyl, and the structure is shown in Formula V:

[0024] Formula III, Formula IV, Formula V.

[0025] The structure of the bridging ligand used for preparing the mono-titaniumocene catalyst of the present invention is shown in Formula II:

[0026] Formula II,

[0027] Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched or isomerized alkyl group, R2 is hydrogen, or C 1~ C 10 A straight chain, branched or isomerized alkyl group; or, R1 is a methyl group or a phenyl group, and R2 is a methyl group or a phenyl group.

[0028] Among them, the C1~C 10 The straight chain, branched or isomerized alkyl group may include, but is not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

[0029] The preparation method of the bridging ligand is characterized in that the components and proportions are:

[0030] (1) The structural formula of component A is shown in formula VI, and the molecular structural formula of component B is shown in formula VII:

[0031] Formula VI, Formula VII,

[0032] Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10 A straight chain, branched or isomerized alkyl group; or, R1 is methyl or phenyl, and R2 is methyl or phenyl;

[0033] (2) Ratio: The molar ratio is n(A):n(B)=1:1.

[0034] The specific preparation steps of the mono-titanocene bridged ligand (Formula II) in the present invention are as follows: under a nitrogen protection environment, 1 part of component A and 1 part of component B are dissolved in a tetrahydrofuran solution, n-butyl lithium is used as a catalyst, and the reaction is carried out at -60°C to 0°C for 12 to 20 hours, and the product is cooled and filtered to obtain the ligand.

[0035] The above ligand (Formula II) is reacted with titanium tetrachloride to obtain a monotitalocene catalyst. The specific preparation method is: in a nitrogen environment, 1 part of the ligand of Formula II is dissolved in petroleum ether, and 1 part of titanium chloride dissolved in petroleum ether is slowly added dropwise, and the reaction is carried out at -60°C to -40°C for 2-6 hours. The reaction solution is filtered under reduced pressure, the product is dissolved in toluene for recrystallization, and the monotitalocene catalyst is obtained after vacuum drying.

[0036] The present invention provides a preparation method of a single titanocene catalyst and its application in olefin polymerization. The single titanocene catalyst and a co-catalyst together form a catalytic system. The co-catalyst is: methylaluminoxane, ethylaluminoxane, triisobutylaluminum B(C6F5)3, [PhMe2NH][B(C6F5)4] and [Ph3C][B(C6F5)4], one or more of which are used in combination. The molar ratio of the titanocene catalyst to the co-catalyst is preferably: the molar ratio of aluminum in the organoaluminum compound to the titanocene compound is (1-300):1; the molar ratio of boron in the boride to the titanocene compound is 10:1.

[0037] The present invention also provides three polymerization methods: ethylene homopolymerization, propylene homopolymerization and ethylene and 1-octene copolymerization.

[0038] The steps for preparing polyethylene are as follows: deoxygenating and dehydrating the reactor, introducing nitrogen for protection, adding a toluene solution containing a certain amount of a promoter, introducing ethylene gas to replace the nitrogen until saturation, balancing for 10 to 30 minutes, adding a toluene solution containing a certain amount of monotantalum, polymerizing for 0.2 to 0.5 hours at a total pressure of 1.0 atmospheres and 40 to 60°C, adding an ethanolic hydrochloric acid solution to terminate the reaction, filtering, and vacuum drying the product at 50 to 60°C.

[0039] The steps for preparing polypropylene are as follows: deoxygenating and dehydrating the reactor, introducing nitrogen for protection, adding a toluene solution containing a certain amount of a promoter, introducing propylene gas to replace the nitrogen until saturation, balancing for 10 to 30 minutes, adding a toluene solution containing a certain amount of monotantalum, polymerizing for 0.5 to 1 hour at a total pressure of 1.0 atmospheres and 40 to 60°C, adding an ethanolic hydrochloric acid solution to terminate the reaction, filtering, and vacuum drying the product at 50 to 60°C.

[0040] The preparation steps of ethylene / 1-octene copolymer are as follows: deoxygenation and water removal from the reactor, nitrogen protection, adding a toluene solution containing a certain amount of promoter, then adding a certain amount of 1-octene solution, introducing ethylene gas to replace nitrogen until saturation (ethylene / 1-octene=3~15 mol), balancing for 10~30 minutes, adding a toluene solution containing a certain amount of monotantalum, polymerizing for 0.2~1 hour at a total pressure of 1.0 atmospheres and 40~60°C, adding ethanol hydrochloric acid solution to terminate the reaction, filtering, and vacuum drying the product at 50~60°C.

[0041] The preparation method of a mono-titanocene catalyst provided by the present invention and its application in olefin polymerization will be described in detail below with reference to the examples.

[0042] Example 1: Preparation of Mono-titanocene Bridged Ligand 1a: Under nitrogen protection, 1 mmol of 7-bromoquinoline and 1 mmol of cyclopentadienyldimethylsilyl chloride were dissolved in 20 mL of tetrahydrofuran solution, and 5 mL of tetrahydrofuran solution containing 1 mmol of n-butyl lithium was slowly added dropwise over 0.5 hours, and the mixture was reacted at -60 °C for 12 hours. The mixture was filtered under reduced pressure and washed with ether to obtain a yellow product with a yield of 67%.

[0043] Example 2: Preparation of mono-titanocene bridged ligand 1b: Under nitrogen protection, 1 mmol 7-bromoquinoline and 1 mmol 1-(chloromethylphenylsilyl)-cyclopentadiene-(1,3) were dissolved in 20 mL tetrahydrofuran solution, and 5 mL tetrahydrofuran solution containing 1 mmol n-butyl lithium was slowly added dropwise over 0.5 hours, and the mixture was reacted at -60 °C for 15 hours. The mixture was filtered under reduced pressure and washed with ether to obtain a yellow product with a yield of 53%.

[0044] Example 3: Preparation of Mono-titanocene Bridged Ligand 1c: Under nitrogen protection, 1 mmol of 7-bromoquinoline and 1 mmol of cyclopentadienyldiphenylsilyl chloride were dissolved in 20 mL of tetrahydrofuran solution, and 5 mL of tetrahydrofuran solution containing 1 mmol of n-butyl lithium was slowly added dropwise over 0.5 hours, and the mixture was reacted at -60 °C for 15 hours. The mixture was filtered under reduced pressure and washed with ether to obtain a yellow product with a yield of 69%.

[0045] Example 4: Preparation of mono-titanocene catalyst 2a: In a nitrogen environment, 0.5 mmol 1a ligand was dissolved in 10 mL petroleum ether, and 10 ml of petroleum ether solution containing 0.1 mmol titanium tetrachloride was slowly added dropwise, and the reaction was carried out at -60 °C for 3 hours. The reaction solution was filtered under reduced pressure, and the product was dissolved in toluene and recrystallized. The product was a reddish brown powder with a yield of 43%. The structural formula is shown in Formula III. Elemental analysis: Measured value (calculated value), C%, 52.39 (52.06); H%, 4.17 (4.37); N%, 3.90 (3.79).

[0046] Example 5: Preparation of mono-titanocene catalyst 2b: In a nitrogen environment, 0.5 mmol 1b ligand was dissolved in 10 mL petroleum ether, and 10 ml of petroleum ether solution containing 0.1 mmol titanium tetrachloride was slowly added dropwise, and the reaction was carried out at -60 °C for 3 hours. The reaction solution was filtered under reduced pressure, and the product was dissolved in toluene and recrystallized. The product was a reddish brown powder with a yield of 39%. The structural formula is shown in Formula IV. Elemental analysis: Measured value (calculated value), C%, 58.23 (58.49); H%, 4.19 (4.21); N%, 3.46 (3.25).

[0047] Example 6: Preparation of mono-titanocene catalyst 2c: In a nitrogen environment, 0.5 mmol 1c ligand was dissolved in 10 mL petroleum ether, and 10 ml of petroleum ether solution containing 0.1 mmol titanium tetrachloride was slowly added dropwise, and the reaction was carried out at -60 °C for 3 hours. The reaction solution was filtered under reduced pressure, and the product was dissolved in toluene and recrystallized. The product was a reddish brown powder with a yield of 47%. The structural formula is shown in Formula V. Elemental analysis: Measured value (calculated value), C%, 64.51 (64.30); H%, 3.79 (4.09); N%, 2.90 (2.84).

[0048] Example 7: Preparation of polyethylene: The reactor was deoxygenated and dehydrated, and nitrogen was introduced for protection. 20 mL of toluene solution containing a certain amount of co-catalyst (such as methylaluminoxane as the co-catalyst, with a molar ratio of Al / Ti=100) was added, and ethylene gas was introduced to replace the nitrogen until saturation, and the mixture was balanced for 10 to 20 minutes. 20 mL of toluene solution containing 0.4 μmmol of mono-titanocene catalyst (2a, 2b or 2c) was added, and the mixture was polymerized at a total pressure of 1.0 atm and 60°C for 0.2 hours. An ethanolic hydrochloric acid solution was added to terminate the reaction, and the mixture was filtered. The product was vacuum dried at 60°C. Table 1 records the relevant polymerization data of this example.

[0049] Example 8: Preparation of polypropylene: The reactor was deoxygenated and dehydrated, and nitrogen was introduced for protection. 20 mL of toluene solution containing a certain amount of co-catalyst (such as methylaluminoxane, Al / Ti=100) was added, and propylene gas was introduced to replace nitrogen until saturation, and equilibrated for 10 to 15 minutes. 20 mL of toluene solution containing 0.4 μmmol of mono-titanium ocene catalyst (2a, 2b or 2c) was added, and polymerization was carried out at a total pressure of 1.0 atm and 60°C for 0.5 hour. Ethanol hydrochloric acid solution was added to terminate the reaction, and the product was filtered and dried in vacuum at 60°C. Table 1 records the relevant polymerization data of this example.

[0050] Example 9: Preparation of ethylene / 1-octene copolymer: The reactor was deoxygenated and dehydrated, and nitrogen was introduced for protection. 20 mL of toluene solution containing a certain amount of cocatalyst (such as methylaluminoxane, Al / Ti=100-300) was added, and then 5 mL of 1-octene solution was added. Ethylene gas was introduced to replace nitrogen until saturation, and the mixture was balanced for 10-20 minutes. 20 mL of toluene solution containing 0.4 μmmol of mono-titanium ocene catalyst (2a, 2b or 2c) was added, and the mixture was polymerized at a total pressure of 1.0 atm and 60°C for 0.2 hour. Ethanol hydrochloric acid solution was added to terminate the reaction, and the mixture was filtered. The product was vacuum dried at 60°C. Table 1 records the relevant polymerization data of Examples 7-9.

[0051] Table 1 Polymerization data of Examples 7 to 9.

[0052]

[0053] Note: The molecular weight and molecular weight distribution of polymers are measured by GPC, and the standard sample is polystyrene.

[0054] The invention discloses a mono-titanium ocene catalyst for olefin polymerization. The catalyst can efficiently catalyze olefin polymerization, such as ethylene homopolymerization, propylene homopolymerization, and ethylene / 1-octene copolymerization. The catalyst has good application prospects in industrial large-scale production of olefin polymers.

Claims

1. A mono-titanium-based catalyst for olefin polymerization, characterized in that: Its molecular structure is shown in Formula I: Formula I, Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10 or, R1 is methyl or phenyl, and R2 is phenyl.

2. A method for preparing the mono-titanocene catalyst as claimed in claim 1, characterized in that: The steps and conditions of the method are as follows: in a nitrogen environment, dissolving the monoclinocene-containing bridging ligand of the structure shown in formula II in petroleum ether, adding titanium tetrachloride at -60°C to -40°C, reacting for 2-6 hours, filtering under reduced pressure, recrystallizing the product, and vacuum drying to obtain the monoclinocene catalyst; Formula II, Wherein, R1 is hydrogen, or C1~C 10 A straight chain, branched chain or isomerized alkyl group, R2 is hydrogen, or C1~C 10 or, R1 is methyl or phenyl, and R2 is phenyl.

3. The method according to claim 2, characterized in that The molar ratio of the bridging ligand to the titanium tetrachloride is 1:

1.

4. The use of the mono-titanium ocene catalyst in olefin polymerization as claimed in claim 1, characterized in that: The mono-titaniumocene catalyst and the co-catalyst together form a catalytic system to catalyze the homopolymerization or copolymerization reaction of olefins. The co-catalyst is an organic aluminum compound and / or an organic boron compound. The organic aluminum compound is at least one of methylaluminoxane, ethylaluminoxane and triisobutylaluminum. The organic boron compound is at least one of B(C6F5)3, [PhMe2NH][B(C6F5)4] and [Ph3C][B(C6F5)4].

5. The use according to claim 4, characterized in that: The monotitanium catalyst, the organoaluminum compound and the organoboron compound together form a catalytic system, the molar ratio of aluminum in the organoaluminum compound to the monotitanium catalyst is (1-300):1, and the molar ratio of boron in the organoboron compound to the monotitanium catalyst is 10:1.

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