CN1243029C - Method for preparing solid homogenous metallocene cataloyst carried by poly phenylethylene - Google Patents

Abstract

The invention discloses a preparation method of a solid homogeneous metallocene catalyst supported by polystyrene. The present invention introduces a cyclopentadienyl group on a linear polystyrene chain, and in the presence of a metallocene, utilizes the Diels-Alder crosslinking reaction between the cyclopentadienyl groups to load the metallocene to the crosslinked polystyrene in the network. The appearance of the catalyst prepared by this method is solid, and the solvent can enter the polystyrene network during the polymerization process so that the metallocene catalyst is in a homogeneous environment to catalyze olefin polymerization, and the cross-linked network of the carrier can be gradually untied during the polymerization process, so that The active center originally wrapped inside the carrier is gradually released, which makes the polymerization kinetics of the catalyst relatively stable when catalyzing olefin polymerization, which is very beneficial in the industrial catalytic process.

Description

Preparation method of solid homogeneous metallocene catalyst supported by polystyrene

technical field

The invention relates to a preparation method of a solid homogeneous metallocene catalyst supported by polystyrene.

Background technique

In order to make metallocenes suitable for industrial slurry polymerization or gas phase polymerization, it is very important to support metallocenes to prepare supported metallocene catalysts. At present, the supports used to support metallocenes usually include inorganic supports and polymer supports. Inorganic carriers are generally SiO ₂ , Al ₂ O ₃ , etc. The surface of these inorganic carriers contains hydroxyl groups. Generally, the surface of the carrier must be treated before the metallocene is loaded. The acidic groups remaining on the surface may affect the performance of the metallocene catalyst obtained. , and the use of metallocene catalysts supported by inorganic substances to catalyze olefin polymerization, due to the high ash content in the product, will have a negative impact on the performance of the polymerized product. The macromolecular carrier can overcome some shortcomings of the inorganic carrier. US Patent No. 5,587,439 discloses a kind of ethylene/methacrylic acid ester copolymer loaded metallocene, and the carrier can be used to support CpZrCl _or ZrCl ₄ (THF) ₂ , using MAO as cocatalyst to catalyze ethylene polymerization in toluene solution, the resulting polyethylene has a relatively narrow molecular weight distribution (M _w /M _n =2.3-3.0). Eur.Pat.Appl.518092 discloses a method for preparing Me ₂ Si(Ind) ₂ ZrCl ₂ -MAO supported on polypropylene particles. The polymer-supported metallocene catalyst prepared by this method has good stability, and the corresponding polymer Olefin products have better morphology.

Contents of the invention

The object of the present invention is to provide a preparation method of polystyrene supported solid homogeneous metallocene catalyst.

The technical scheme adopted in the present invention is:

1. the catalyst prepared by the present invention mainly contains two components of A and B to form:

A. Polystyrene with a cross-linked network structure: the cross-linked structure of polystyrene is produced by the Diels-Alder cross-linking reaction of the cyclopentadienyl group connected to the polystyrene benzene ring;

B. Metallocene: Molecular formula Cp _x MCl _y , x=1-2, y=2-3, Cp is a cyclopentadiene group, M is Zr;

The preparation process of the catalyst is as follows:

1). Preparation of linear polystyrene

Linear polystyrene is prepared by suspension polymerization, adding styrene monomer, benzoyl peroxide initiator, and polyvinyl alcohol stabilizer to deionized water, reacting at 60°C to 80°C for 3 to 5 hours, and drying the product in vacuum , deionized water: styrene: benzoyl peroxide: polyvinyl alcohol weight ratio is 500: 100 ~ 150: 1 ~ 4: 1 ~ 2;

2). Preparation of chloromethylated linear polystyrene

Under anhydrous and oxygen-free conditions, dissolve linear polystyrene in carbon tetrachloride solvent, then add catalyst solution containing anhydrous aluminum trichloride and 1-nitropropane, chloromethyl methyl ether, system React at room temperature for 1 to 4 hours, use methanol as a precipitant, and vacuum-dry the obtained product at room temperature; linear polystyrene: chloromethyl methyl ether: aluminum chloride: 1-nitropropane weight ratio is 1 to 5 :5～7:0.8～3:10～20;

3). Synthesis of linear polystyrene containing cyclopentadienyl

Under anhydrous and oxygen-free conditions, react chloromethylated linear polystyrene with excess cyclopentadienyl sodium at -78°C with tetrahydrofuran as a solvent, and use methanol as a precipitating agent. The precipitate is at -15 Vacuum drying at ℃～0℃ for 6～12 hours; chloromethylated linear polystyrene: cyclopentadienyl sodium molar ratio is 1:20～40;

4). Preparation of solid homogeneous catalyst

Under anhydrous and oxygen-free conditions, dissolve the linear polystyrene containing cyclopentadienyl and metallocene in toluene, mix well, remove the toluene solvent in vacuum, and react the residue at 40℃～60℃ for 12～24 hours After the reaction, the product is washed with toluene, and then vacuum-dried; the zirconium content of the obtained polystyrene-supported solid homogeneous metallocene catalyst is 0.1741-0.8159 mmol/g.

2. The group used to form the polystyrene cross-linked structure is the cyclopentadiene group connected to the polystyrene benzene ring.

3. The molar content of chloromethyl groups in chloromethylated linear polystyrene is 16% to 53%.

4. When chloromethylated linear polystyrene reacts with cyclopentadienyl sodium, the chlorine groups in chloromethylated linear polystyrene can be completely replaced by cyclopentadienyl groups.

The beneficial effects that the present invention has are:

The appearance of the catalyst prepared by this method is solid, and the solvent can enter the polystyrene network during the polymerization process so that the metallocene catalyst is in a homogeneous environment to catalyze olefin polymerization, and the cross-linked network of the carrier can be gradually untied during the polymerization process, so that The active center originally wrapped inside the carrier is gradually released, which makes the polymerization kinetics of the catalyst relatively stable when catalyzing olefin polymerization, which is very beneficial in the industrial catalytic process.

Detailed ways

The invention is to synthesize a solid homogeneous metallocene catalyst, which not only has the characteristics of heterogeneous catalysts, but also maintains the characteristics of homogeneous metallocene catalysts. By linking chloromethyl groups on the linear polystyrene support, the number of chloromethyl groups on the linear polystyrene chain can be conveniently controlled by controlling the reaction conditions, thereby obtaining a catalyst with controllable structure. In this polymer-supported metallocene catalyst system, the metallocene exists in a cross-linked network without any chemical bond between the cross-linked network and the metallocene. During the olefin polymerization process, the solvent (toluene) first swells the crosslinked network, and the swollen network provides a micro-homogeneous polymerization environment for the metallocene. During the polymerization process, the crosslinked network of the carrier is broken as the polymer grows. , the internal new active centers are constantly exposed, making the catalyst activity higher and the polymerization process stable.

Example 1

1) Synthesis of linear polystyrene

In the four-necked flask of 1000 milliliters that thermometer is housed, mechanical stirring paddle is added successively 500 milliliters of deionized water, 2 gram polyvinyl alcohols, 100 gram styrene monomers and 1 gram initiator benzoyl peroxide, vigorously stir, The reaction was carried out at 80°C for 3 hours, and the product was vacuum-dried for 12 hours.

2) Synthesis of chloromethylated linear polystyrene

Under anhydrous and oxygen-free conditions, in a 1000 ml three-necked flask, 4.5 grams of linear polystyrene prepared by step 1) was dissolved in 450 ml of _CCl4 solution to form a polymer solution; in a 250 ml three-necked flask, add 2.8 g of anhydrous AlCl ₃ , 170 ml of CCl ₄ and 10 g of 1-nitropropane were prepared as a catalyst solution. Add 6 g of chloromethyl methyl ether into the polymer solution at room temperature, and then slowly drop the catalyst solution into the polymer solution. The reaction was carried out at room temperature for 3 hours, and then 10 ml of acetic acid was added to the system to terminate the reaction. Methanol was used as a precipitating agent, and the precipitate was dried under vacuum at room temperature for 12 hours. The chloromethyl content in the product was 16.73% (mol%).

3) Synthesis of linear polystyrene containing cyclopentadiene groups

In anhydrous and oxygen-free conditions, at a temperature of -78°C, 60 ml of tetrahydrofuran solution of cyclopentadienyl sodium (40 mmol of cyclopentadienyl sodium), 11 g of hexamethylphosphorus were successively added to a 250 ml three-necked flask. Amide triamide [(CH ₃ ) ₂ N] ₃ P(O), 1.26 g of chloromethylated linear polystyrene (chloromethyl content: 1.88 mmol) prepared in step 2). The temperature was raised to 0°C with stirring and reacted at 0°C for 3.5 hours, and finally 10 ml of saturated NH ₄ Cl solution was added to terminate the reaction. Using anhydrous methanol as a precipitating agent, the obtained precipitate was vacuum-dried at 0°C for 12 hours.

4) Preparation of polystyrene-supported solid-state homogeneous metallocene catalyst

Under anhydrous and oxygen-free conditions, dissolve 0.8789 g of cyclopentadiene-containing linear polystyrene prepared in step 3) into 25 mL of toluene, then add 0.2631 g of Cp ₂ ZrCl ₂ , mix well, and vacuum remove After removing the solvent, the system was heated to 50°C and held for 24 hours. The final product obtained was washed with toluene solution and dried in vacuum. The zirconium content of the prepared catalyst was 0.1741 mmol/g.

Example 2

1) same as step 1) of embodiment 1

2) Synthesis of chloromethylated linear polystyrene

Under anhydrous and oxygen-free conditions, in a 100 milliliter three- _necked flask, 1.1 gram of linear polystyrene prepared by step 1) was dissolved in 25 milliliters of CCl solution to form a polymer solution; in another 100 milliliter three-necked flask 0.8 g of anhydrous AlCl ₃ , 20 ml of CCl ₄ and 16 g of 1-nitropropane were sequentially added to prepare a catalyst solution. Add 5.8 g of chloromethyl methyl ether into the polymer solution at normal temperature, and then slowly add the catalyst solution into the polymer solution dropwise. The reaction was carried out at room temperature for 1 hour, and then 10 ml of acetic acid was added to the system to terminate the reaction. Anhydrous methanol was used as a precipitating agent, and the precipitate was vacuum-dried at room temperature for 12 hours. The chloromethyl content in the product is 52.88% (mol%).

3) Synthesis of linear polystyrene containing cyclopentadiene groups

Under anhydrous and oxygen-free conditions at a temperature of -78°C, 60 ml of tetrahydrofuran solution of cyclopentadienyl sodium (cyclopentadienyl sodium is 130 mmol), 29 g of hexamethylphosphorus were successively added to a 250 ml three-necked flask. Acyl triamide [(CH ₃ ) ₂ N] ₃ P(O), 1 gram of chloromethylated linear polystyrene (4.08 mmol of chloromethyl) prepared by step 2) of this example. Warm up to 0°C with stirring and react at 0°C for 3.5 hours, and finally add 10 ml of saturated NH ₄ Cl solution to terminate the reaction, use anhydrous methanol as precipitant, and vacuum-dry the obtained precipitate at 0°C for 12 hours .

4) Preparation of polystyrene-supported solid-state homogeneous metallocene catalyst

Under anhydrous and oxygen-free conditions, dissolve 0.8887 g of cyclopentadiene group-containing polystyrene prepared in step 3) of this example into 25 mL of toluene, then add 0.3049 g of Cp ₂ ZrCl ₂ , mix well, and vacuum After removing the solvent, the system was heated to 50°C and held for 24 hours. The final product obtained was washed with toluene solution and dried in vacuum. The zirconium content of the prepared catalyst was 0.8159mmol/g.

Examples of the invention being used for ethylene polymerization:

1. Embodiment 1 catalyst is used for ethylene polymerization

In a polymerization bottle with a stirring device, 50 milliliters of toluene, cocatalyst MAO and the catalyst prepared in Example 1 were added successively. At 50°C, feed ethylene gas and keep the ethylene pressure at 1 atm, [Al]/[Zr]=500-3000, react for 0.5 hours, stop the reaction with acidified ethanol and precipitate the product, wash the product several times with ethanol, and filter Then vacuum-dry at 60°C to constant weight. The catalytic efficiency is 0.39-1.1×10 ⁶ gPE/molZr.h. The polymerization process was found to be stable through kinetic observation.

2. Embodiment 2 catalyst is used for ethylene polymerization

In a polymerization bottle with a stirring device, 50 milliliters of toluene, cocatalyst MAO and the catalyst prepared in Example 1 were added successively. At 50°C, feed ethylene gas and keep the ethylene pressure at 1 atm, [Al]/[Zr]=500-3000, react for 0.5 hours, stop the reaction with acidified ethanol and precipitate the product, wash the product several times with ethanol, and filter Then vacuum-dry at 60°C to constant weight. The catalytic efficiency is 0.3-0.7×10 ⁶ gPE/molZr,h. The polymerization process was found to be stable through kinetic observation.

Claims (4)

1. the preparation method of the solid-state homogeneous phase metallocene catalyst of a loaded by polystyrene is characterized in that, the catalyzer of the present invention's preparation mainly contains A and B two components are formed:

A. the polystyrene that has cross-linked network structure: the crosslinking structure of polystyrene is by the cyclopentadienyl that is connected on the polystyrene phenyl ring generation of Diels-Alder crosslinking reaction to take place;

B. metallocene: molecular formula Cp _xMCl _y, x=1-2, y=2-3, Cp are cyclopentadienyl group, M is Zr;

The Preparation of catalysts process is as follows:

1). the preparation of linear polystyrene

Linear polystyrene prepares by suspension polymerization, in deionized water, add styrene monomer, the benzoyl peroxide initiator, the polyvinyl alcohol stablizer, reacted 3～5 hours down at 60 ℃～80 ℃, product vacuum-drying, deionized water: vinylbenzene: benzoyl peroxide: the polyvinyl alcohol weight ratio is 500: 100～150: 1～4: 1～2;

2). the preparation of chloromethylation linear polystyrene

Under the condition of anhydrous and oxygen-free, linear polystyrene is dissolved in the carbon tetrachloride solvent, add the catalyst solution that contains aluminum trichloride (anhydrous) and 1-nitropropane then successively, chloromethyl methyl ether, system was reacted 1～4 hour at normal temperatures, with methyl alcohol is precipitation agent, vacuum-drying under the product normal temperature that obtains; Linear polystyrene: chloromethyl methyl ether: aluminum chloride: 1-nitropropane weight ratio is 1～5: 5～7: 0.8～3: 10～20;

3). contain linear polystyrene synthetic of cyclopentadienyl

Under the anhydrous and oxygen-free condition, at-78 ℃, be solvent with the tetrahydrofuran (THF), with excessive cyclopentadienyl sodium reaction, be precipitation agent with the linear polystyrene of chloromethylation with methyl alcohol, throw out was-15 ℃～0 ℃ following vacuum-drying 6～12 hours; Chloromethane base unit weight in the linear polystyrene of chloromethylation: cyclopentadienyl sodium mol ratio is 1: 20～40;

4). the preparation of solid-state homogeneous catalyst

Under the anhydrous and oxygen-free condition, the linear polystyrene and the metallocene that will contain cyclopentadienyl are dissolved in the toluene, mix final vacuum and remove toluene solvant, and residuum was 40 ℃～60 ℃ reactions 12～24 hours, reaction finishes after product toluene wash, vacuum-drying then; The zirconium content of the solid-state homogeneous phase metallocene catalyst of gained loaded by polystyrene is 0.1741～0.8159mmol/g.

2. the preparation method of the solid-state homogeneous phase metallocene catalyst of a kind of loaded by polystyrene according to claim 1 is characterized in that: the group that is used for forming the polystyrene crosslinking structure is the cyclopentadienyl group that is connected on the polystyrene phenyl ring.

3. the preparation method of the solid-state homogeneous phase metallocene catalyst of a kind of loaded by polystyrene according to claim 1, it is characterized in that: the molar content of chloromethyl is 16%～53% in the chloromethylation linear polystyrene.

4. the preparation method of the solid-state homogeneous phase metallocene catalyst of a kind of loaded by polystyrene according to claim 1, it is characterized in that: when the chloromethylation linear polystyrene reacted with cyclopentadienyl sodium, the cl radical in the chloromethylation linear polystyrene can be replaced by cyclopentadienyl group fully.