CN115651101A - Supported metallocene catalyst for ethylene polymerization and preparation method thereof - Google Patents
Supported metallocene catalyst for ethylene polymerization and preparation method thereof Download PDFInfo
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Abstract
The invention provides a supported metallocene catalyst for ethylene polymerization and a preparation method thereof, belonging to the technical field of olefin polymerization catalysts. The supported metallocene catalyst for ethylene polymerization comprises: (1) a metallocene compound; (2) aluminum and fluorine modified silica gel support. MAO is not needed to be used in the preparation process and the polymerization process of the supported metallocene catalyst, so that the production cost is greatly reduced. The obtained catalyst has good particle shape and adjustable particle size. Has good copolymerization reaction performance of catalyzing ethylene and high alpha-olefin and high copolymerization activity. The resin powder obtained by polymerization has good particle shape and high bulk density, and is suitable for polymerization processes of a slurry method and a gas phase method.
Description
Technical Field
The invention belongs to the technical field of olefin polymerization catalysts, and particularly relates to a supported metallocene catalyst for ethylene polymerization and a preparation method thereof.
Background
The development and application of metallocene catalysts is another major breakthrough in the field of olefin polymerization catalysts after the traditional Ziegler-Natta catalysts, and particularly in the 80 s, kaminsky and Sinn et al (angelw. Chem.,1980, 19, 390, adv. Organic. Chem.,1980, 18, 99) developed high-efficiency co-catalyst Methylaluminoxane (MAO), so that the research of metallocene catalysts has entered a rapid development stage. However, the metallocene catalyst needs to achieve high activity, the amount of MAO required is large, the production cost is high, and the wide application of the metallocene catalyst in the field of olefin polymerization is limited.
Two types of methods are generally used to solve the above problems, the most common method is to use MAO to modify the surface of the support, i.e. to load MAO, so that no homogeneous MAO solution is required to be added during the polymerization process, and the studies on MAO modified supports are very numerous, and the studies on MAO modified silica gel supports are the most. Such as CN200910235933.8; CN201010519660.2; CN201110336517.4; CN201210418645.8; CN201310521768.9; US6777366; US7294600; US8436112; US10233268. Although this method avoids the addition of homogeneous MAO solution during the polymerization, there is still a loss of MAO solution during the modification of the silica gel support, which requires a cost reduction by adding recycling procedures (CN 02104332.9), but this method makes the process more complicated.
Another approach is to use borides instead of MAO as cocatalysts, including boron trihalides, trifluorophenylboron, organo borates, etc. Chinese invention patent CN201310541010.1 discloses a supported metallocene catalyst for ethylene polymerization, which comprises the reaction product of the following components: (1) a metallocene compound; (2) a silicon hydrocarbyl chloride; (3) an aluminum alkyl; (4) a borate compound; and (5) silica gel carrier. The used N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate compound has the function of replacing MAO as a cocatalyst, but the borate compounds can not be directly bonded with functional groups on the surface of the carrier, but the borate compounds can be loaded only by sequentially modifying the carrier through silicon alkyl chloride, alkyl aluminum and the like, and the reaction steps are multiple.
Disclosure of Invention
The invention provides a supported metallocene catalyst for ethylene polymerization, which aims to solve the problems of high MAO consumption, high production cost and the like in the polymerization reaction process of the supported metallocene.
The invention provides a supported metallocene catalyst for ethylene polymerization, which comprises the following components in percentage by weight:
(1) A metallocene compound; (2) aluminum and fluorine modified silica gel supports.
Further, the general formula I of the metallocene compound is Cp 2 (Z)MX n ；
Wherein Cp is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group;
z is a linking unit linking two metallocenes, if formula I is a non-bridged metallocene complex, Z does not represent any element; if the formula I is a bridged metallocene complex, Z is selected from SiR 2 、CR* 2 、SiR* 2 SiR* 2 、CR* 2 CR* 2 CR = CR or CR 2 SiR* 2 Wherein R is hydrogen or alkyl, aryl, silyl, halogenated alkyl or halogenated aryl with the number of carbon atoms less than 20;
m is a group IVB or group VB transition metal;
x is independently selected from one of halogen, alkyl, oxyl, acid radical and amino;
n is an integer satisfying the valence of M.
Further, cp is substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl, wherein the substituent is selected from C 1 -C 20 Alkyl, alkoxy, silyl, aralkoxy or halogen;
m is zirconium or hafnium;
x is independently selected from halogen, alkyl, allyl, cyclopentadienyl, alkoxy or arene oxy; preferably, X is independently selected from chloro, bromo, methyl, ethyl, methoxy or isopropoxy;
n＝2。
further, the dosage ratio of the aluminum and fluorine modified silica gel carrier to the metallocene compound was 1g:10-500 mu mol.
The invention also provides a preparation method of any one of the supported metallocene catalysts for ethylene polymerization, which comprises the following steps:
(1) Heating the silica gel carrier under a vacuum condition to obtain a heat-activated silica gel carrier;
(2) Under the protection of inert gas or nitrogen, adding the thermally activated silica gel carrier into a reactor, adding a solvent, dispersing into a suspension, adding an alkyl aluminum solution, reacting, washing and drying to obtain an alkyl aluminum modified silica gel carrier;
(3) Under the protection of inert gas or nitrogen, carrying out primary thermal activation on the aluminum alkyl modified silica gel carrier; carrying out secondary thermal activation on the alkyl aluminum modified silica gel carrier subjected to the primary thermal activation treatment in an oxygen atmosphere to obtain a thermally activated alkyl aluminum modified silica gel carrier;
(4) Under the protection of inert gas or nitrogen, mixing the thermally activated alkylaluminum modified silica gel carrier with fluoride for three times of thermal activation to obtain a fluorinated-alkylaluminum modified silica gel carrier;
(5) Under the protection of inert gas or nitrogen, adding the fluorinated-alkyl aluminum modified silica gel carrier into a solvent to prepare slurry, dropwise adding a metallocene compound solution into the slurry, and reacting to obtain the supported metallocene catalyst.
Further, the dosage ratio of the silica gel carrier to the aluminum alkyl is 1g:0.05-10mmol.
Further, the mass of the fluoride is 1-50% of that of the thermally activated alkylaluminum modified silica gel carrier;
preferably, the metallocene compound is added in an amount of 10 to 500. Mu. Mol per gram of the fluoro-alkylaluminum-modified silica gel support.
Further, in the step (1), the heating temperature is 110-250 ℃, and the heating time is 1-24 hours;
preferably, in the step (2), the reaction temperature is 0-90 ℃, and the reaction time is 1-24 hours;
preferably, in the step (3), the temperature of the first thermal activation is 200-600 ℃, and the time of the first thermal activation is 1-24 hours; the temperature of the secondary thermal activation is 200-600 ℃, and the time of the secondary thermal activation is 1-24 hours;
preferably, in the step (4), the temperature of the three times of thermal activation is 200-600 ℃, and the time of the three times of thermal activation is 1-24 hours;
preferably, in the step (5), the reaction temperature is 0 to 90 ℃ and the reaction time is 0.5 to 12 hours.
Further, in the step (2), the alkyl aluminum is selected from at least one of trimethyl aluminum, triethyl aluminum, tri-n-alkyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum or triphenyl aluminum;
preferably, in the step (4), the fluoride is at least one selected from ammonium fluoride, ammonium bifluoride and ammonium fluorosilicate.
The invention also provides the application of any one of the supported metallocene catalysts and the supported metallocene catalyst prepared by any one of the preparation methods in olefin polymerization reaction.
The invention has the following advantages:
according to the metallocene catalyst loaded by the aluminum and fluorine modified silica gel, MAO is not needed in the preparation process and the polymerization process of the loaded metallocene catalyst, so that the production cost is greatly reduced. The obtained catalyst has good particle shape and adjustable particle size. Has good copolymerization reaction performance of catalyzing ethylene and higher alpha-olefin and high copolymerization activity. The resin powder obtained by polymerization has good particle shape and high bulk density, and is suitable for polymerization processes of a slurry method and a gas phase method.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
One embodiment of the present invention provides a supported metallocene catalyst for ethylene polymerization, comprising:
(1) A metallocene compound; (2) aluminum and fluorine modified silica gel support.
In a preferred embodiment of the present invention, the metallocene compound has the general formula I Cp 2 (Z)MX n ；
Wherein Cp is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group;
z is a linking unit linking two metallocenes, if formula I is a non-bridged metallocene complex, Z does not represent any element; if the formula I is a bridged metallocene complex, Z is selected from SiR 2 、CR* 2 、SiR* 2 SiR* 2 、CR* 2 CR* 2 CR = CR or CR 2 SiR* 2 Wherein R is hydrogen or alkyl, aryl, silyl, halogenated alkyl or halogenated aryl with the number of carbon atoms less than 20;
m is a group IVB or group VB transition metal;
x is independently selected from one of halogen, alkyl, oxyl, acid radical and amino;
n is an integer satisfying the valence of M.
Preferably, cp is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group, wherein the substituents are selected from C 1 -C 20 Alkyl, alkoxy, silyl, aralkoxy or halogen;
m is zirconium or hafnium;
x is independently selected from halogen, alkyl, allyl, cyclopentadienyl, alkoxy or arene oxy; preferably, X is independently selected from chloro, bromo, methyl, ethyl, methoxy or isopropoxy;
n＝2。
in a preferred embodiment of the present invention, the ratio of the amount of the silica gel carrier modified with aluminum and fluorine to the amount of the metallocene compound is 1g:10-500 mu mol.
In a preferred embodiment of the present invention, the preparation method of the aluminum and fluorine modified silica gel support is the same as the steps (1) to (4) of the preparation method of the supported metallocene catalyst for ethylene polymerization.
In the embodiment of the invention, the weight content of aluminum in the obtained supported metallocene catalyst is 1-20%, preferably 5-10%; fluorine content of 0.1-10%, preferably 1-5%; the content by weight of the transition metal M is from 0.01 to 5%, preferably from 0.1 to 1%.
An embodiment of the present invention provides a method for preparing a supported metallocene catalyst for ethylene polymerization, comprising the steps of:
(1) Heat treatment of the silica gel carrier: heating the silica gel carrier under a vacuum condition to obtain a heat-activated silica gel carrier;
(2) Preparation of the aluminum alkyl modified silica gel carrier: under the protection of inert gas or nitrogen, adding the thermally activated silica gel carrier into a reactor, adding a solvent, dispersing into a suspension, adding an alkyl aluminum solution, reacting, washing and drying to obtain an alkyl aluminum modified silica gel carrier;
(3) And (3) heat treatment of the aluminum alkyl modified silica gel carrier: under the protection of inert gas or nitrogen, carrying out primary thermal activation on the aluminum alkyl modified silica gel carrier; carrying out secondary thermal activation on the alkyl aluminum modified silica gel carrier subjected to the primary thermal activation treatment in an oxygen atmosphere to obtain a thermally activated alkyl aluminum modified silica gel carrier;
(4) Carrying out fluorination modification treatment on the carrier: under the protection of inert gas or nitrogen, mixing the thermally activated alkylaluminum modified silica gel carrier with fluoride for thermal activation for three times to obtain a fluorinated-alkylaluminum modified silica gel carrier;
(5) Preparation of modified Supported metallocene catalyst: under the protection of inert gas or nitrogen, adding the fluorinated-alkyl aluminum modified silica gel carrier into a solvent to prepare slurry, dropwise adding a metallocene compound solution into the slurry, and reacting to obtain the supported metallocene catalyst.
In the embodiment of the invention, the step (1) is mainly used for carrying out heat treatment on the silica gel carrier to remove trace adsorbed water and paving the subsequent aluminum and fluorine modification.
In one embodiment of the invention, in the step (1), the heating temperature is 110-250 ℃, and the heating time is 1-24 hours. Preferably, the heating temperature is 130-200 deg.C, and the heating time is 2-6 hr.
In the embodiment of the invention, in the step (2), firstly, the thermally activated silica gel carrier is modified by alkyl aluminum for the first time, and the alkyl aluminum reacts with hydroxyl on the surface of the carrier to prepare the alkyl aluminum modified silica gel carrier.
In one embodiment of the invention, in the step (2), the reaction temperature is 0-90 ℃ and the reaction time is 1-24 hours. Preferably, the reaction temperature is 30-60 ℃ and the reaction time is 2-4 hours.
In an embodiment of the present invention, in the step (2), the alkyl aluminum is at least one selected from trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum and triphenyl aluminum.
In one embodiment of the present invention, in step (2), the concentration of the aluminum alkyl solution is 1-10mmol/mL.
In one embodiment of the present invention, in the step (2), the ratio of the silica gel carrier to the aluminum alkyl is 1g:0.05-10mmol; preferably, the ratio of the silica gel carrier to the aluminum alkyl is 1g:1-5mmol.
In the embodiment of the invention, the step (3) is followed by carrying out thermal activation treatment on the silica gel carrier modified by the alkyl aluminum to form an-Al-O-structure, so that subsequent fluorine modification is facilitated.
In one embodiment of the present invention, in the step (3), the temperature of the first thermal activation is 200-600 ℃, and the time of the first thermal activation is 1-24 hours. Preferably, the temperature of the first thermal activation is 400-500 ℃, and the time of the first thermal activation is 6-10 hours.
In one embodiment of the present invention, in the step (3), the temperature of the second thermal activation is 200-600 ℃, and the time of the second thermal activation is 1-24 hours. Preferably, the temperature of the first thermal activation is 400-500 ℃, and the time of the first thermal activation is 6-10 hours.
In the embodiment of the invention, the thermally activated alkylaluminum modified silica gel carrier is secondarily modified by fluoride in the step (4) to form an F-Al-O structure, so that the fluorine modified silica gel carrier is prepared.
In one embodiment of the present invention, in the step (4), the temperature of the three thermal activations is 200 to 600 ℃, and the time of the three thermal activations is 1 to 24 hours. Preferably, the temperature of the three thermal activations is 400-500 ℃, and the time of the three thermal activations is 6-10 hours.
In an embodiment of the present invention, in the step (4), the fluoride is at least one selected from ammonium fluoride, ammonium bifluoride, and ammonium fluorosilicate.
In an embodiment of the present invention, in the step (4), the mass of the fluoride is 1% to 50% of the mass of the thermally activated alkylaluminum modified silica gel carrier. Preferably, the mass of the fluoride is 5-20% of the mass of the aluminum alkyl modified silica gel carrier after thermal activation.
In the embodiment of the invention, in the step (5), the fluorine-modified silica gel carrier and the metallocene are loaded to obtain the final modified carrier-loaded metallocene catalyst.
In one embodiment of the present invention, in the step (5), the reaction temperature is 0 to 90 ℃ and the reaction time is 0.5 to 12 hours. Preferably, the reaction temperature is 20-40 ℃ and the reaction time is 1-2 hours.
In an embodiment of the present invention, the solvent is toluene. The dosage ratio of the fluorinated-alkyl aluminum modified silica gel carrier to the solvent is 1g:15-30mL. Preferably, the amount ratio of the fluorinated-alkylaluminum modified silica gel support to the solvent is 1g:20mL.
In one embodiment of the present invention, the metallocene compound is added in an amount of 10 to 500. Mu. Mol per gram of the silica gel support.
Specifically, the concentration of the metallocene compound solution is 0.1-25mg/ml; preferably, the concentration of the metallocene compound solution is 4 to 6mg/ml.
The embodiment of the invention also provides the application of any one of the supported metallocene catalysts in olefin polymerization reaction. The olefin polymerization reaction comprises olefin homopolymerization reaction and olefin copolymerization reaction.
The supported metallocene catalyst prepared by the preparation method of the embodiment of the invention can be applied to different polymerization methods. For example, it can be used for gas phase polymerization of olefins, slurry polymerization of olefins, etc. It can also be used for homopolymerization or copolymerization of olefin, especially for homopolymerization of ethylene or copolymerization of ethylene and other alpha-olefin, wherein the alpha-olefin adopts propylene, butylene, amylene, hexylene, octylene or 4-methylpentene-1, etc.
The solvent used for the polymerization is selected from alkanes, aromatic hydrocarbons or halogenated hydrocarbons. Preferably one or a mixture of hexane, pentane, heptane, benzene, toluene, dichloromethane, chloroform, dichloroethane. Most preferred is one of hexane, toluene, heptane or mixtures thereof.
The concentration of the supported metallocene catalyst during polymerization is 1X 10 -8 Mole/liter
1×10 -3 The concentration of the supported metallocene catalyst is preferably in the range of 1X 10 mol/l -8 Mol/l
1×10 -5 Mol/l.
The polymerization temperature is-78 ℃ to 100 ℃, preferably 0 ℃ to 90 ℃.
The polymerization pressure is from 0.01 to 10.0MPa, preferably from 0.01 to 2.0MPa.
The present invention will be described in detail with reference to examples.
Example 1A method for preparing a supported metallocene catalyst A for ethylene polymerization, comprising the steps of:
(1) Thermal activation treatment of silica gel carrier
955 the silica gel carrier is heated in a vacuum state, the temperature is raised from 20 ℃ to 200 ℃, and the heating rate is 10 ℃/min. Keeping the temperature for 24 hours after the temperature reaches 200 ℃ to obtain a heat-activated silica gel carrier;
(2) Preparation of aluminum alkyl modified silica gel carrier
Under the protection of nitrogen, adding 2.0 g of the heat-activated silica gel carrier into a glass reactor, adding 80 mL of dried toluene, dispersing into suspension, adding 0.5 mL of 10mmol/mL trimethylaluminum toluene solution, heating to 90 ℃, stirring for reaction for 1 hour, washing with 60 mL of toluene for three times, washing with 60 mL of hexane for one time, and drying in vacuum to obtain solid powder with good fluidity, namely the alkyl aluminum modified silica gel carrier;
(3) One-time thermal activation treatment of alkyl aluminum modified silica gel carrier
Heating the alkyl aluminum modified silica gel carrier obtained in the step (2) in a nitrogen atmosphere, raising the temperature from 20 ℃ to 200 ℃, keeping the temperature for 24 hours after the temperature reaches 200 ℃, and obtaining the heat-activated silica gel carrier;
(4) Secondary thermal activation treatment of alkyl aluminum modified silica gel carrier
Heating the alkyl aluminum modified silica gel carrier obtained in the step (3) in an oxygen atmosphere, raising the temperature from 20 ℃ to 200 ℃, keeping the temperature for 24 hours after the temperature reaches 200 ℃, and obtaining the heat-activated silica gel carrier;
(5) Fluorination treatment
Heating 1g of the alkylaluminum modified silica gel carrier obtained in the step (4) and 0.5 g of ammonium fluoride in a nitrogen atmosphere, raising the temperature from 20 ℃ to 200 ℃, keeping the temperature for 24 hours after the temperature reaches 200 ℃, and obtaining a fluorinated-alkylaluminum modified silica gel carrier;
(6) Preparation of Supported metallocene catalyst A
Under the protection of nitrogen, 1g of the fluorinated-alkylaluminum modified silica gel carrier obtained in the step (5) was added to a glass reactor, 20ml of dried toluene was added to prepare a slurry, and 40.4 mg of bis- (n-butylcyclopentadienyl) zirconium dichloride (nBuCp) was dissolved in 10 ml of toluene 2 ZrCl 2 The solution is dripped into a reactor to react for 12 hours at 40 ℃, and then 20ml of toluene is used for washing and vacuum drying to obtain the loaded metallocene catalyst A.
Characterization was performed using ICP, which is characterized by quantitative determination of the weight percent of metal in the supported catalyst. The instrument is a P1000 type ICP-AES plasma emission spectrometer produced by PE company in America.
By ICP characterization, in catalyst a, the Zr content was 0.39 wt%, the F content was 9.48 wt%, and the A1 content was 7.64 wt%.
Example 2A method for preparing a supported metallocene catalyst B for ethylene polymerization, comprising the steps of:
(1) Thermal activation treatment of silica gel carrier
The 955 silica gel carrier is heated in a vacuum state, the temperature is raised from 20 ℃ to 110 ℃, and the heating rate is 10 ℃/min. Keeping for 8 hours after reaching 110 ℃ to obtain the heat activated silica gel carrier
(2) Preparation of aluminum alkyl modified silica gel carrier
Under the protection of nitrogen, 2.0 g of the heat activated silica gel carrier obtained above is added into a glass reactor, 80 mL of dried toluene is added to be dispersed into suspension, 0.5 mL of 10mmol/mL triethylaluminum toluene solution is added, the temperature is raised to 40 ℃, the mixture is stirred to react for 2 hours, then 60 mL of toluene is used for washing for three times, then 60 mL of hexane is used for washing once, and vacuum drying is carried out to obtain solid powder with good fluidity, namely the alkyl aluminum modified silica gel carrier.
(3) Thermal activation treatment of silica gel carrier
And (3) heating the alkyl aluminum modified silica gel carrier obtained in the step (2) in a nitrogen atmosphere, raising the temperature from 20 ℃ to 450 ℃, and raising the temperature at a speed of 10 ℃/min. Keeping for 8 hours after reaching 450 ℃, and obtaining the silica gel carrier subjected to heat activation treatment
(4) Thermal activation treatment of silica gel carrier
And (4) heating the alkyl aluminum modified silica gel carrier obtained in the step (3) in an oxygen atmosphere, raising the temperature from 20 ℃ to 450 ℃, and raising the temperature at a rate of 10 ℃/min. Keeping the temperature for 8 hours after the temperature reaches 450 ℃ to obtain a silica gel carrier subjected to heat activation treatment;
(5) Fluorination treatment
And (3) heating 1g of the alkyl aluminum modified silica gel carrier obtained in the step (4) and 0.2 g of ammonium fluosilicate in a nitrogen atmosphere, raising the temperature from 20 ℃ to 450 ℃, and raising the temperature at a rate of 10 ℃/min. Keeping for 8 hours after reaching 450 ℃ to obtain the fluorinated-alkyl aluminum modified silica gel carrier
(6) Preparation of Supported metallocene catalyst B
Under the protection of nitrogen, 1g of the fluorinated-alkylaluminum modified silica gel carrier obtained in the step (5) is added into a glass reactor, 20ml of dried toluene is added to prepare slurry, and the slurry is dissolved in 10 ml of the dried toluene43.3 mg of bis (1, 3-butylmethylcyclopentadienyl) zirconium dichloride (1, 3-BuMeCp) in toluene 2 ZrCl 2 The solution is dripped into a reactor to react for 1 hour at 25 ℃, and then 20ml of toluene is used for washing and vacuum drying to obtain the supported metallocene catalyst B.
ICP indicates that in the catalyst B, the Zr content is 0.41 percent, the F content is 4.16 percent and the A1 content is 6.87 percent.
Example 3A method for preparing a supported metallocene catalyst C for ethylene polymerization, comprising the steps of:
(1) Thermal activation treatment of silica gel carrier
955 the silica gel carrier is heated in a vacuum state, the temperature is raised from 20 ℃ to 250 ℃, and the heating rate is 10 ℃/min. Keeping for 1 hour after reaching 250 ℃ to obtain the silica gel carrier subjected to thermal activation treatment;
(2) Preparation of aluminum alkyl modified silica gel carrier
Under the protection of nitrogen, adding 2.0 g of the obtained heat-activated silica gel carrier into a glass reactor, adding 80 mL of dried toluene, dispersing into suspension, adding 0.1 mL of 1mmol/mL triphenylaluminum toluene solution, cooling to 0 ℃, stirring for reaction for 24 hours, washing with 60 mL of toluene for three times, washing with 60 mL of hexane for one time, and drying in vacuum to obtain solid powder with good fluidity, namely the alkyl aluminum modified silica gel carrier;
(3) One-time thermal activation treatment of alkyl aluminum modified silica gel carrier
And (3) heating the alkylaluminum modified silica gel carrier obtained in the step (2) in a nitrogen atmosphere, and raising the temperature from 20 ℃ to 600 ℃ at a temperature raising rate of 10 ℃/min. Keeping for 1 hour after the temperature reaches 600 ℃ to obtain a silica gel carrier subjected to heat activation treatment;
(4) Secondary thermal activation treatment of alkyl aluminum modified silica gel carrier
And (4) heating the alkyl aluminum modified silica gel carrier obtained in the step (3) in an oxygen atmosphere, raising the temperature from 20 ℃ to 600 ℃, and raising the temperature at a speed of 10 ℃/min. Keeping for 1 hour after the temperature reaches 600 ℃ to obtain the silica gel carrier subjected to heat activation treatment;
(5) Fluorination treatment
And (5) heating 1g of the alkylaluminum modified silica gel carrier obtained in the step (4) and 0.01 g of ammonium bifluoride in a nitrogen atmosphere, raising the temperature from 20 ℃ to 600 ℃, and raising the temperature at a rate of 10 ℃/min. Keeping for 1 hour after the temperature reaches 600 ℃ to obtain a fluorinated-alkyl aluminum modified silica gel carrier;
(6) Preparation of Supported metallocene catalyst C
Under the protection of nitrogen, 1g of the fluorinated-alkylaluminum modified silica gel support obtained in (5) was charged into a glass reactor, 20ml of dried toluene was added to prepare a slurry, and 52.1 mg of bis (1, 3-butylmethylcyclopentadienyl) hafnium dichloride (1, 3-BuMeCp) was dissolved in 10 ml of toluene 2 HfCl 2 The solution is dripped into a reactor to react for 12 hours at the temperature of 0 ℃, and then 20ml of toluene is used for washing and vacuum drying to obtain the loaded metallocene catalyst C.
By ICP characterization, for catalyst C, the weight content of Hf was 0.11%, the weight content of F was 1.03%, and the weight content of A1 was 1.28%.
Example 4A method for preparing a supported metallocene catalyst D for ethylene polymerization, comprising the steps of:
(1) Thermal activation treatment of silica gel carrier
Heating 955 silica gel carrier in vacuum state, heating from 20 deg.C to 150 deg.C, heating rate 10 deg.C/min. Keeping for 10 hours after reaching 150 ℃ to obtain the silica gel carrier subjected to heat activation treatment;
(2) Preparation of aluminum alkyl modified silica gel carrier
Under the protection of nitrogen, 2.0 g of the obtained thermal activation treatment silica gel carrier is added into a glass reactor, 80 mL of dried toluene is added to be dispersed into suspension, 1 mL of 10mmol/mL triisobutylaluminum toluene solution is added, the temperature is raised to 50 ℃, stirring is carried out for reaction for 4 hours, then 60 mL of toluene is used for washing for three times, then 60 mL of hexane is used for washing for one time, and vacuum drying is carried out to obtain solid powder with good fluidity, namely the alkylaluminum modified silica gel carrier;
(3) One-time thermal activation treatment of alkyl aluminum modified silica gel carrier
And (3) heating the alkyl aluminum modified silica gel carrier obtained in the step (2) in a nitrogen atmosphere, raising the temperature from 20 ℃ to 350 ℃, and raising the temperature at a speed of 10 ℃/min. Keeping for 10 hours after the temperature reaches 350 ℃ to obtain the silica gel carrier subjected to heat activation treatment;
(4) Secondary thermal activation treatment of alkyl aluminum modified silica gel carrier
And (4) heating the alkyl aluminum modified silica gel carrier obtained in the step (3) in an oxygen atmosphere, raising the temperature from 20 ℃ to 350 ℃, and raising the temperature at a speed of 10 ℃/min. Keeping for 10 hours after the temperature reaches 350 ℃ to obtain the silica gel carrier subjected to heat activation treatment;
(5) Fluorination treatment
And (3) heating 1g of the alkylaluminium modified silica gel carrier obtained in the step (4) and 0.1 g of ammonium fluoride in a nitrogen atmosphere, raising the temperature from 20 ℃ to 350 ℃, and raising the temperature at a speed of 10 ℃/min. Keeping for 10 hours after reaching 350 ℃ to obtain a fluorinated-alkyl aluminum modified silica gel carrier;
(6) Preparation of Supported metallocene catalyst D
Under nitrogen protection, 1g of the aluminum fluoride-alkylaluminum modified silica gel support obtained in (5) was charged into a glass reactor, 20ml of dried toluene was added to prepare a slurry, and 41.8 mg of ethylenebis (1-indenyl) zirconium dichloride CH was dissolved in 10 ml of toluene 2 (Ind) 2 ZrCl 2 The solution is dripped into a reactor to react for 2 hours at 40 ℃, and then 20ml of toluene is used for washing and vacuum drying to obtain the loaded metallocene catalyst D.
By ICP characterization, in catalyst D, zr content was 0.94% by weight, F content was 3.02% by weight, and A1 content was 19.46% by weight.
Example 5A method for preparing a supported metallocene catalyst E for ethylene polymerization, comprising the steps of:
(1) - (5), same as in steps (1) - (5) of example 2.
(6) Preparation of Supported metallocene catalyst E
The same as in step (6) in example 2, except that 43.3 mg of bis (1, 3-butylmethylcyclopentadienyl) zirconium dichloride (1, 3-BuMeCp) was added 2 ZrCl 2 Replacement with 4.3 mg of bis (1, 3-butylmethylcyclopentadienyl) zirconium dichloride (1, 3-BuMeCp) 2 ZrCl 2 Obtaining the load metallocene catalyst E.
ICP showed that catalyst E contained 0.03 wt% Zr, 4.55 wt% F and 5.35 wt% A1.
Example 6A method for preparing a supported metallocene catalyst F for ethylene polymerization, comprising the steps of:
(1) - (5), same as in steps (1) to (5) of example 2.
(6) Preparation of Supported metallocene catalyst F
Similar to example 2, step (6), 43.3 mg of bis (1, 3-butylmethylcyclopentadienyl) zirconium dichloride (1, 3-BuMeCp) alone 2 ZrCl 2 Replacement with 216.5 mg of bis (1, 3-butylmethylcyclopentadienyl) zirconium dichloride (1, 3-BuMeCp) 2 ZrCl 2 Obtaining the supported metallocene catalyst F.
The catalyst F was characterized by ICP by 4.81 wt.% Zr, 3.38 wt.% F and 8.14 wt.% A1.
Comparative example 1A method for preparing a supported metallocene catalyst G (modified with aluminum alkyl only and without fluoride) for ethylene polymerization, comprising the following steps:
(1) - (4), same as in steps (1) - (4) of example 2.
(5) Preparation of Supported metallocene catalyst G
The support obtained in the step (4) was subjected to metallocene compound loading according to the step (6) of example 2, to obtain a supported metallocene catalyst G.
ICP representation shows that in the catalyst H, the weight content of Zr is 0.50%, and the weight content of Al is 8.17%.
Comparative example 2A method for preparing a supported metallocene catalyst H (fluoride-only modified, no aluminum alkyl) for ethylene polymerization, comprising the steps of:
(1) The procedure is as in (1) of example 2.
(2) Fluoride modified supports
The carrier obtained in the step (1) is subjected to fluoride modification according to the step (5) in the example 2;
(3) Preparation of Supported metallocene catalyst H
The support obtained in the step (2) is subjected to metallocene compound loading according to the step (6) of example 2, so as to obtain a supported metallocene catalyst H.
ICP indicates that the weight content of Zr in the catalyst H is 0.25 percent, and the weight content of F in the catalyst H is 5.37 percent.
Comparative example 3A supported metallocene catalyst I (MAO modified support) for ethylene polymerization was prepared according to the invention patent CN201110336517.4 example 1.
The catalyst I was characterized by ICP that Zr content was 0.46% and A1 content was 11.63%.
Test example 1High pressure ethylene polymerization experiment
The high pressure ethylene polymerization experiment procedure was as follows:
in a 1L stainless steel high pressure polymerizer, which was purged with nitrogen and ethylene three times each, then 2L hexane solvent was added, and with the addition of hexane, 4 mL of a1 mol/L Triethylaluminum (TEA) hexane solution and the required amount of 1-hexene were added, followed by the addition of 10 to 50 mg of the supported metallocene catalyst obtained in the above example, heating to 85 ℃ and raising and maintaining the pressure to and at 1.0MPa for 2 hours. After the polymerization reaction is finished, cooling, collecting polyethylene particle powder, and weighing.
And characterizing the product polyethylene by a characterization mode of polymer molecular weight and molecular weight distribution. The molecular weight and the distribution thereof are determined by Gel Permeation Chromatography (GPC) with AgilentPL220 as the solvent, 1,2, 4-trichlorobenzene, sample concentration lmg/mL, solvent flow rate 1.0mL/min; the measurement temperature was 150 ℃. Each sample was measured twice. Specific polymerization results are listed in table 1.
TABLE 1 polymerization results of Supported metallocene catalysts
As can be seen from Table 1, the polymerization activity of the catalyst carrier was improved by treating it with an aluminum alkyl and a fluoride in this order. Compared with the catalyst prepared by the MAO treated carrier, the indexes such as activity, weight average molecular weight distribution and the like are basically unchanged. Therefore, after the carrier is treated by using the alkyl aluminum and the fluoride, the technical index of the product can be ensured to reach the standard, the activity is improved, and MAO is not used.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A supported metallocene catalyst for ethylene polymerization, comprising:
(1) A metallocene compound; (2) aluminum and fluorine modified silica gel support.
2. The supported metallocene catalyst according to claim 1, characterized in that,
the general formula I of the metallocene compound is Cp 2 (Z)MX n ；
Wherein Cp is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group;
z is a linking unit linking two metallocenes, if formula I is a non-bridged metallocene complex, Z does not represent any element; if the general formula I is a bridged metallocene complex, Z is selected from SiR 2 、CR* 2 、SiR* 2 SiR* 2 、CR* 2 CR* 2 CR = CR or CR 2 SiR* 2 Wherein R is hydrogen or alkyl, aryl, silyl, halogenated alkyl or halogenated aryl with the number of carbon atoms less than 20;
m is a group IVB or group VB transition metal;
x is independently selected from one of halogen, alkyl, oxyl, acid radical and amino;
n is an integer satisfying the valence of M.
3. The supported metallocene catalyst according to claim 2, characterized in that,
cp is substituted or unsubstituted cyclopentadienyl, indeneOr fluorenyl, wherein the substituents are selected from C 1 -C 20 Alkyl, alkoxy, silyl, aralkoxy or halogen;
m is zirconium or hafnium;
x is independently selected from halogen, hydrocarbyl, allyl, cyclopentadienyl, alkoxy or aryloxy; preferably, X is independently selected from chloro, bromo, methyl, ethyl, methoxy or isopropoxy;
n＝2。
4. the supported metallocene catalyst according to claim 1, characterized in that,
the dosage ratio of the aluminum and fluorine modified silica gel carrier to the metallocene compound is 1g:10-500 mu mol.
5. The method for preparing a supported metallocene catalyst for ethylene polymerization according to any one of claims 1 to 4, comprising the steps of:
(1) Heating the silica gel carrier under a vacuum condition to obtain a heat-activated silica gel carrier;
(2) Under the protection of inert gas or nitrogen, adding the thermally activated silica gel carrier into a reactor, adding a solvent, dispersing into a suspension, adding an alkyl aluminum solution, reacting, washing and drying to obtain an alkyl aluminum modified silica gel carrier;
(3) Under the protection of inert gas or nitrogen, carrying out primary thermal activation on the aluminum alkyl modified silica gel carrier; carrying out secondary thermal activation on the alkyl aluminum modified silica gel carrier subjected to the primary thermal activation treatment in an oxygen atmosphere to obtain a thermally activated alkyl aluminum modified silica gel carrier;
(4) Under the protection of inert gas or nitrogen, mixing the thermally activated alkylaluminum modified silica gel carrier with fluoride for three times of thermal activation to obtain a fluorinated-alkylaluminum modified silica gel carrier;
(5) Under the protection of inert gas or nitrogen, adding the fluorinated-alkyl aluminum modified silica gel carrier into a solvent to prepare slurry, dropwise adding a metallocene compound solution into the slurry, and reacting to obtain the supported metallocene catalyst.
6. The production method according to claim 5,
the dosage ratio of the silica gel carrier to the aluminum alkyl is 1g:0.05-10mmol.
7. The production method according to claim 5,
the mass of the fluoride is 1-50% of that of the thermally activated alkylaluminium modified silica gel carrier;
preferably, the metallocene compound is added in an amount of 10 to 500. Mu. Mol per gram of the fluoro-alkylaluminum-modified silica gel support.
8. The method according to claim 5,
in the step (1), the heating temperature is 110-250 ℃, and the heating time is 1-24 hours;
preferably, in the step (2), the reaction temperature is 0-90 ℃, and the reaction time is 1-24 hours;
preferably, in the step (3), the temperature of the first thermal activation is 200-600 ℃, and the time of the first thermal activation is 1-24 hours; the temperature of the secondary thermal activation is 200-600 ℃, and the time of the secondary thermal activation is 1-24 hours;
preferably, in the step (4), the temperature of the three times of thermal activation is 200-600 ℃, and the time of the three times of thermal activation is 1-24 hours;
preferably, in the step (5), the reaction temperature is 0 to 90 ℃ and the reaction time is 0.5 to 12 hours.
9. The production method according to claim 5,
in the step (2), the alkyl aluminum is selected from at least one of trimethyl aluminum, triethyl aluminum, tri-n-alkyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum or triphenyl aluminum;
preferably, in the step (4), the fluoride is at least one selected from ammonium fluoride, ammonium bifluoride and ammonium fluorosilicate.
10. Use of the supported metallocene catalyst according to any one of claims 1 to 4 or the supported metallocene catalyst prepared by the preparation method according to any one of claims 5 to 9 in olefin polymerization reactions.
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| US6147173A (en) * | 1998-11-13 | 2000-11-14 | Univation Technologies, Llc | Nitrogen-containing group 13 anionic complexes for olefin polymerization |
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| CN103108894A (en) * | 2010-09-07 | 2013-05-15 | 切弗朗菲利浦化学公司 | Novel catalyst systems and methods of making and using same |
| CN105566519A (en) * | 2014-10-17 | 2016-05-11 | 中国石油化工股份有限公司 | Supported metallocene catalyst and preparation method and application thereof |
| CN114685703A (en) * | 2015-04-20 | 2022-07-01 | 埃克森美孚化学专利公司 | Catalyst compositions comprising fluorinated supports and methods of use thereof |
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| US6147173A (en) * | 1998-11-13 | 2000-11-14 | Univation Technologies, Llc | Nitrogen-containing group 13 anionic complexes for olefin polymerization |
| CN102015781A (en) * | 2007-09-28 | 2011-04-13 | 切弗朗菲利浦化学公司 | Polymerization catalysts for producing polymers with low melt elasticity |
| CN103108894A (en) * | 2010-09-07 | 2013-05-15 | 切弗朗菲利浦化学公司 | Novel catalyst systems and methods of making and using same |
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