CN101619111B - Silica gel loaded alpha-nickel diimine olefin polymerization catalyst, preparation method and application - Google Patents

Abstract

The invention relates to a silica gel-supported α-bisimine nickel olefin polymerization catalyst. The catalyst utilizes chemical bonding to load α-bisimine nickel on silica gel, which can achieve the purpose of high-efficiency loading; the catalyst is modified Under the action of methylaluminoxane, the Al/Ni molar ratio is 50-400, which can efficiently catalyze ethylene polymerization, and the activity can reach 966-2400gPE/gcat·h, and produce high molecular weight polyethylene with good shape.

Description

Silica gel-supported α-bisimine nickel olefin polymerization catalyst, preparation method and application

technical field

The invention relates to a silica gel-loaded α-bisimine nickel olefin polymerization catalyst, a preparation method and application.

Background technique

Polyolefins are a class of synthetic polymer materials with large output and wide application. Catalyst is the core of the development of polyolefin industry and the key to control the structure and performance of polyolefin. In 1995, Brookhart et al. found that α-diimine nickel showed high catalytic activity for the polymerization of ethylene and α-olefins, and could prepare high-molecular-weight polymers with controllable structure, which made late transition metal catalysts more important. The process flow of the existing polyolefin industrial equipment requires that the catalyst must be heterogeneous and supported. If the catalyst is not supported, the shape of the polyolefin particles will be poor, which will affect the product delivery and even cause polymer agglomeration and wall sticking. Therefore, the key to the application and development of homogeneous polymerization catalysts is catalyst support to make it suitable for gas-phase fluidized bed or slurry polymerization processes; in addition, catalyst support can greatly reduce the amount of co-catalyst and increase the stability of the active center. However, studies have found that the support of late transition metal catalysts is relatively difficult by using traditional physical adsorption methods (Macromol. It is not easy to obtain the desired effect; the method of using "polymerization technology" to immobilize the late transition metal catalyst on polystyrene has higher activity, but the polyolefin form is poor (Appl.Catal.A 2004, 262, 13-18; New J. Chem. 2002, 10, 1485-1489). Kim et al. and Herrmann et al. attempted to load diimide pyridinium iron (II) on silica gel by covalent bonding and achieved success, but the loading capacity was low, only about 0.13mgFe/gcat (Macromolecules 2003, 36, 6689; Organometallics 2002, 21, 74). Zheng Zhanjiang and others disclosed two methods for loading diimide pyridinium iron (II), and the loading amount reached about 0.5 mgFe/gcat (Journal of Catalysis 2005, 234, 101-110).

Contents of the invention

The purpose of the present invention is to use chemical bonding to load the α-bisimine nickel catalyst on silica gel to obtain a high-efficiency loaded α-bisimine nickel olefin polymerization catalyst, and to catalyze the high-efficiency polymerization of ethylene under the condition of low co-catalyst dosage , to obtain high molecular weight polyethylene with good morphology.

The silica gel supported α-bisimine nickel olefin polymerization catalyst disclosed by the present invention has the following structure:

In the formula, X is Br or Cl, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ and so on.

The silica gel-loaded α-bisimine nickel olefin polymerization catalyst disclosed by the present invention can efficiently catalyze ethylene polymerization under the action of modified methylalumoxane (MMAO) or other alkylaluminum cocatalysts, and generate high-molecular weight catalysts with good morphology. Structurally controlled polyethylene.

In order to achieve the above object, the present invention provides a preparation method of silica gel supported α-bisimine nickel olefin polymerization catalyst, the steps and conditions are as follows:

Synthesis of 1,4-allyl-2,6-diisopropylaniline

Add 0.2 mol of 2,6-diisopropylaniline and 0.1 mol of allyl chloride to a 250 mL reaction bottle, and react at reflux at 70°C for 8 hours, a solid appears (the generated HCl reacts with excess aniline to form aniline hydrochloride), hydrogenation The sodium oxide solution was neutralized until it was weakly alkaline, extracted with ether, dried over anhydrous magnesium sulfate, concentrated, and then evaporated under reduced pressure to remove part of the excess aniline. The result is a mixture of N-allyl-2,6-diisopropylaniline and aniline, both of which have similar boiling points and are not easy to separate completely, so the rearrangement reaction continues, because the product 4-allyl-2, The difference between the boiling points of 6-diisopropylaniline and 2,6-diisopropylaniline is larger than that of the previous ones, and the separation is relatively easy. So there is no need to completely separate before rearranging.

Add the mixture of N-allyl-2,6-diisopropylaniline and aniline into a 250mL flask, then add 0.1mol of zinc chloride as a catalyst, heat to 170°C, and carry out rearrangement reaction under nitrogen protection. After reacting for 6 hours, cool down, pour the reaction solution into 400mL sodium hydroxide solution to adjust to weak alkalinity, extract with ether, wash with sodium chloride solution, dry over anhydrous magnesium sulfate for 12 hours, filter, and carefully evaporate the filtrate to remove ether Heating and vacuum distillation collected 95-100 ° C fractions. ¹ H NMR (CDCl ₃ ): δ6.84(s, 2H, Ph-Hm), 5.94(m, 1H, -CH=C), 5.03(t, 2H, C=CH ₂ ), 3.55(s, 2H , _NH2 ), 3.24 (d, 2H, _CH2 -C=C), 2.86 (m, 1H, CH(Me) ₂ ), 1.22 (d, _-CH3 , 12H).

In the formula, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ .

Synthesis of Bisallyl Acenaphthoquinone Bis-imine Ligand

Add 0.91g (5mmol) of acenaphthenequinone and 3.3g (15mmol) of 4-allyl-2,6-diisopropylaniline into the 250mL reaction flask, take 70mL methanol as solvent, then add 1mL formic acid as catalyst, and stir at room temperature for 18 After 1 hour, a small part of the solvent was removed, and a yellow solid precipitated out. After filtration, the resulting yellow solid was recrystallized with ethanol to obtain light yellow crystals. ¹ H NMR(CDCl ₃ ): δ7.81(d, 2H, Nap-H), 7.30(t, 2H, Nap-H), 6.99(s, 4H, Ar-H), 6.57(d, 2H, Nap-H) -H), 6.06 (m, 2H, -CH=C), 5.07 (t, 4H, C=CH ₂ ), 3.42 (d, 4H, CH ₂ -C=C), 2.92 (m, 2H, CH( Me) ₂ ), 1.16(d, C(CH ₃ ) ₂ ), 24H)

In the formula, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ and so on.

Synthesis of Ligands of Bissilyl Chloroacenaphthoquinone Bis-imine

Add 1.5g of bisallyl acenaphthoquinone bisimine to a 100mL reaction bottle, then add 5g of chlorodimethylsilane, add 0.5mL of tetrahydrofuran solution of chloroplatinic acid hexahydrate as a catalyst, and then use 40mL of CH ₂ Cl ₂ As a solvent, the reaction was refluxed at 50°C for 12 hours, the solvent and excess chlorodimethylsilane were removed, and vacuum-dried for 4 hours to obtain a yellow powder. ¹ H NMR(CDCl ₃ ): δ7.81(d, 2H, Nap-H), 7.30(t, 2H, Nap-H), 6.99(s, 4H, Ar-H), 6.57(d, 2H, Nap-H) -H), 3.42(d, 4H, _CH2 -C=C), 2.92(m, 2H, CH(Me) ₂ ), 1.16(d, C( _CH3 ) ₂ ), 24H)

In the formula, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ .

Synthesis of acenaphthoquinone bis-imine ligand supported on silica gel

Add 0.85 g of bissilylchloroacenaphthoquinone bis-imine ligand to a 100 mL reaction flask, then add 2 g of silica gel calcined at 500 ° C for 8 hours (or 2 g of trimethylaluminum-treated silica gel) into the reaction flask, As a solvent, 3 mL of triethylamine was added as a proton capture agent, heated to reflux at 110°C for 14 hours, vacuum filtered, washed twice with 10 mL of tetrahydrofuran to remove ligands that did not react with silica gel, and dried in vacuum.

In the formula, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ .

Synthesis of Acenaphthoquinone Bis-imine Ni(II)

Add 2g (0.38mmol) of ligand supported on silica gel to a 100mL reaction bottle, use 20mL dichloromethane as solvent, add 0.045g (0.5mmol) of ethylene glycol dimethyl ether and stir for 30 minutes, then add nickel bromide or chloride Nickel 0.38mmol, stirred at room temperature for 24 hours, the solvent was carefully removed, washed with 5mL of ether, and vacuum-dried to obtain the target catalyst.

In the formula, X is Br or Cl, R is CH ₃ , or iC ₃ H ₇ , or C ₆ H ₆ .

Silica gel treated with trimethylaluminum:

Under anhydrous and oxygen-free conditions, add silica gel and toluene to the dry reactor, place the reactor in an ice-water bath, use a syringe to extract the pentane solution of trimethylaluminum and slowly add it to the system until no gas is released Then slowly raise the temperature of the reaction system to 20-30° C. and stir for 1 hour, vacuum filter and dry to obtain trimethylaluminum-treated silica gel. The ratio relationship therein is, for every 8.5 g of silica gel, 40 mL of toluene, and 15 mL of a hexane solution of 2 mol/L trimethylaluminum.

Under the action of a small amount of modified methyl aluminoxane (Al/Ni molar ratio 50-400), the catalyst can efficiently catalyze the polymerization of ethylene to produce high-molecular-weight polyethylene with good shape.

The specific application method is as follows:

Ethylene polymerization: After the stainless steel kettle with a volume of 100 or 200mL is fully replaced with high-purity nitrogen, add the above-mentioned α-bisimide nickel olefin polymerization catalyst supported on silica gel, modified methylaluminoxane, and anhydrous n-hexane. The reaction temperature is 2.0MPa, and the reaction temperature is 25-30°C for 60 minutes to obtain a spherical polymer.

Beneficial effects of the present invention:

Under the action of modified methyl aluminoxane (Al/Ni molar ratio 50-400), the catalyst can efficiently catalyze ethylene polymerization, the activity can reach 966-2400gPE/gcat·h, and produce high molecular weight polyethylene with good shape .

Detailed ways

The present invention is further described by the following examples. It should be noted that these examples are only used for further illustration, rather than limiting the protection scope of the present invention.

Example 1

Catalyst preparation:

Synthesis of 1,4-allyl-2,6-diisopropylaniline

Add 0.2 mol of 2,6-diisopropylaniline and 0.1 mol of allyl chloride to a 250 mL reaction flask, react at reflux at 70°C for 8 hours, add sodium hydroxide solution to neutralize until weakly alkaline, extract with ether, anhydrous Concentrate after drying over magnesium sulfate, and then distill off part of excess aniline under reduced pressure. A mixture of N-allyl-2,6-diisopropylaniline and aniline is obtained. Put the mixture into a 250mL flask, add 0.1mol of zinc chloride as a catalyst, heat to 170°C, and carry out rearrangement reaction under nitrogen protection. After reacting for 6 hours, it was cooled, and the reaction solution was poured into 400 mL of sodium hydroxide solution to adjust to weak alkalinity. Extract with ether, wash with NaCl solution, dry over anhydrous magnesium sulfate for 12 hours, and filter. The filtrate is carefully evaporated to remove ether, then heated and distilled under reduced pressure to collect fractions at 95-100°C. ¹ H NMR (CDCl ₃ ): δ6.84(s, 2H, Ph-Hm), 5.94(m, 1H, -CH=C), 5.03(t, 2H, C=CH ₂ ), 3.55(s, 2H , _NH2 ), 3.24 (d, 2H, _CH2 -C=C), 2.86 (m, 1H, CH(Me) ₂ ), 1.22 (d, _-CH3 , 12H).

Synthesis of Bisallyl Acenaphthoquinone Bis-imine Ligand

Add 0.91g (5mmol) of acenaphthenequinone and 3.3g (15mmol) of 4-allyl-2,6-diisopropylaniline into the 250mL reaction flask, take 70mL methanol as solvent, then add 1mL formic acid as catalyst, and stir at room temperature for 18 After 1 hour, a small part of the solvent was removed, and a yellow solid precipitated out. After filtration, the resulting yellow solid was recrystallized with ethanol to obtain light yellow crystals. ¹ H NMR(CDCl ₃ ): δ7.81(d, 2H, Nap-H), 7.30(t, 2H, Nap-H), 6.99(s, 4H, Ar-H), 6.57(d, 2H, Nap-H) -H), 6.06 (m, 2H, -CH=C), 5.07 (t, 4H, C=CH ₂ ), 3.42 (d, 4H, CH ₂ -C=C), 2.92 (m, 2H, CH( Me) ₂ ), 1.16(d, C(CH ₃ ) ₂ ), 24H)

Synthesis of Ligands of Bissilyl Chloroacenaphthoquinone Bis-imine

Add 1.5g of bisallyl acenaphthylquinone bisimine to a 100mL reaction flask, then add 5g of monochlorodimethylsilane, add 0.5mL of a THF solution of chloroplatinic acid hexahydrate as a catalyst, and then use 40mL of dichloromethane as a solvent , The reaction was refluxed at 50°C for 12 hours, the solvent and excess chlorodimethylsilane were removed, and vacuum-dried for 4 hours to obtain a yellow powder. ¹ H NMR(CDCl ₃ ): δ7.81(d, 2H, Nap-H), 7.30(t, 2H, Nap-H), 6.99(s, 4H, Ar-H), 6.57(d, 2H, Nap-H) -H), 3.42(d, 4H, _CH2 -C=C), 2.92(m, 2H, CH(Me) ₂ ), 1.16(d, C( _CH3 ) ₂ ), 24H)

Synthesis of acenaphthoquinone bis-imine ligand supported on silica gel

Add 0.85 g of bissilyl chloride acenaphthoquinone bis-imine ligand to the 100 mL reaction flask, then add 2 g of treated silica gel to the reaction flask, use 50 mL of toluene as the solvent, and then add 3 mL of triethylamine as the proton capture agent, 110 It was heated to reflux at ℃ for 14 hours, vacuum filtered, washed twice with 10 mL of tetrahydrofuran to remove ligands that did not react with silica gel, and dried in vacuum.

Synthesis of Ni(II) acenaphthoquinone bisimine supported on silica gel

Add 2g (0.38mmol) of acenaphthoquinonebisimine ligand supported on silica gel to a 100mL reaction bottle, use 20mL dichloromethane as a solvent, add 0.045g (0.5mmol) of ethylene glycol dimethyl ether and stir for 30 minutes, then add bromide Nickel 0.38mmol, stirred at room temperature for 24 hours, the solvent was carefully removed, washed with 5mL of ether, and vacuum-dried to obtain the target catalyst.

According to elemental analysis, the α-bisimine nickel olefin polymerization catalyst supported on silica gel contains 55.1 mg of nickel per gram.

Example 2

The catalyst prepared in Example 1 has an activity of 2400 gPE/gcat.h under the condition of an aluminum-nickel ratio of 1:400, and the product is a spherical polymer.

Example 3

The synthesis of acenaphthoquinone bisimine ligand supported on silica gel is the same as that in Example 1.

Synthesis of Ni(II) acenaphthoquinone bisimine supported on silica gel

Add 2g (0.38mmol) of acenaphthoquinone bisimine ligand supported on silica gel to a 100mL reaction bottle, use 20mL dichloromethane as solvent, add 0.045g (0.5mmol) of ethylene glycol dimethyl ether and stir for 30 minutes, then add chlorinated Nickel 0.38mmol, stirred at room temperature for 24 hours, the solvent was carefully removed, washed with 5mL of ether, and vacuum-dried to obtain the target catalyst.

According to elemental analysis, the α-bisimine nickel olefin polymerization catalyst supported on silica gel contains 35.4 mg of nickel per gram.

Example 4

The catalyst prepared in Example 3 has an activity of 1700 gPE/gcat·h under the condition of an aluminum-nickel ratio of 1:400, and the product is a spherical polymer.

Claims (1)

1. The application of a silica gel supported α-bisimine nickel olefin polymerization catalyst, characterized in that: the catalyst is used for ethylene oligomerization to prepare high molecular weight polyethylene, and the catalyst has the following structure:

X is Cl, R is CH ₃ , iC ₃ H ₇ or C ₆ H ₆ ; The pore volume of the carrier silica gel used is 1.0-2.0mL/g, and the surface area is 150-600m ² /g; Silica gel is calcined at 500°C for 8 hours, and the amount of silica gel to be calcined is 0.5 to 3 grams per gram of α-bisimine nickel olefin polymerization catalyst; Or the silica gel is treated with trimethylaluminum, and the amount of silica gel treated with trimethylaluminum is 0.5 to 3 grams per gram of α-bisimine nickel olefin polymerization catalyst; The method of treating silica gel with trimethylaluminum: under anhydrous and oxygen-free conditions, add silica gel and toluene to a dry reactor, place the reactor in an ice-water bath, and extract the pentane solution of trimethylaluminum with a syringe Slowly add it into the system, wait until no gas is released, then slowly raise the temperature of the reaction system to 20-30°C, stir for 1 hour, vacuum filter and dry to obtain trimethylaluminum-treated silica gel, the ratio of which is: For every 8.5 g of silica gel, 40 mL of toluene and 15 mL of 2M trimethylaluminum in hexane.