Metallocene polypropylene catalyst and process for its preparation

Abstract

The application provides a metallocene polypropylene catalyst and a preparation method thereof. The preparation method of the metallocene polypropylene catalyst comprises the following steps: 1) performing a thermal activation treatment on a carrier to obtain an activated carrier; 2) loading a first part of a cocatalyst on at least part of the surface of the activated carrier to obtain a first intermediate product; 3) after a second part of the cocatalyst is subjected to a first reaction with a metallocene compound, a pyrrole compound is added to generate a second reaction to obtain a catalyst precursor; and 4) the first intermediate product is subjected to a third reaction with the catalyst precursor to obtain the metallocene polypropylene catalyst; wherein the pyrrole compound comprises an ester group. The preparation method of the metallocene polypropylene catalyst of the application is simple in operation, uses less chemical reagents, and the prepared metallocene polypropylene catalyst has excellent activity, and the polymer has a wider molecular weight distribution.

Description

Technical Field

[0001] This invention relates to the field of metallocene compound catalysis technology, and in particular to a metallocene polypropylene catalyst and its preparation method. Background Technology

[0002] Metallocene catalysts represent another major breakthrough following Ziegler-Natta (ZN) catalysts. Since Professor Kaminsky of the University of Hamburg, Germany, first discovered the high activity of metallocene (MAO) catalysts for olefin polymerization in the early 1980s, this catalytic system has been a hot topic of research for scientists and is currently gradually replacing ZN catalysts.

[0003] Patent CN113173999A discloses a method for improving the activity of metallocene-catalyzed olefin polymerization, comprising: adding an electron donor with a fused-ring structure to the metallocene catalytic system for modification, thereby generating a π-π superposition effect with the fused-ring structure of the metallocene catalyst, enhancing the stabilizing effect of the fused-ring structure on the transition metal active center in the catalytic system, and thus improving the activity of catalytic olefin polymerization. However, this technology belongs to a homogeneous metallocene catalyst system, which cannot control the particle morphology of the polymer and cannot be applied to the current mainstream production processes of metallocene polyethylene or polypropylene, such as gas-phase polymerization, slurry polymerization, and liquid-phase bulk polymerization.

[0004] Patent CN101454356A discloses a single-point catalyst activator, its preparation method, and its use in catalysts and olefin polymerization. The method involves adding an ion-pair activator composition, wherein the cation includes a bronsted acid, and the anion's organic ligand has at least two heteroatoms covalently chelated to a metal atom. This chelation of the organic ligand with the metal atom increases the stability of the activator composition and significantly reduces the tendency for deactivation, especially for ligands without electron-withdrawing groups. However, this method is complex and requires a variety of chemical reagents, hindering its industrial application.

[0005] Patent CN106661154A discloses a catalyst activator, its preparation method, and its use in polymerization methods, including: enhancing catalyst activity by adding a perfluorinated group system based on at least one compound containing at least one active hydrogen moiety and at least one fluorine substituent, relying on these electron-withdrawing groups for stabilization. However, metallocene catalysts using perfluorophenol-based activators in this method are prone to deactivation and have a short lifespan.

[0006] Patent CN112679634A discloses a solid metallocene catalyst and its application, comprising: instead of using an inert support to load the metallocene active component, solidifying an aluminoxane and then loading the metallocene active component. Compared with traditional supported metallocene catalysts, the catalyst of this invention has more uniform active centers, higher catalyst loading, and better catalyst performance. It exhibits good performance and significantly improved polymerization activity in propylene polymerization. However, this technology, which improves the activity of the metallocene catalyst through the solidification of an aluminoxane, suffers from problems such as the large amount of aluminoxane required and the inability to control the catalyst particle morphology.

[0007] Therefore, it is necessary to provide a method for preparing metallocene polypropylene catalysts that is simple to operate, requires few chemical reagents, and can produce highly active catalysts with a wide molecular weight distribution. Summary of the Invention

[0008] This invention provides a metallocene polypropylene catalyst and its preparation method. The preparation method of the metallocene polypropylene catalyst of this invention is simple to operate, uses few chemical reagents, and the prepared metallocene polypropylene catalyst has excellent activity.

[0009] A method for preparing a metallocene polypropylene catalyst includes the following steps:

[0010] 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier;

[0011] 2) The first portion of the co-catalyst is loaded onto at least a portion of the surface of the activated support to obtain a first intermediate product;

[0012] 3) After the second part of the co-catalyst undergoes a first reaction with the metallocene compound, a pyrrole compound is added to undergo a second reaction, yielding the catalyst precursor;

[0013] 4) The first intermediate product is reacted with the catalyst precursor in a third reaction to obtain the metallocene polypropylene catalyst;

[0014] The pyrrole compound includes an ester group;

[0015] In the second reaction, the temperature is 60-120℃ and the time is 2-16h.

[0016] In the preparation method described above, the molar ratio of the pyrrole compound to the metallocene compound is (0.01-1):1.

[0017] In the preparation method described above, the molar ratio of the second co-catalyst to the metallocene compound is (10-100):1.

[0018] In the preparation method described above, the temperature in the first reaction is 20-100℃ and the time is 1-24h.

[0019] In the preparation method described above, the molar ratio of the metallocene compound to the support is (0.001-0.01):1; and / or,

[0020] In the third reaction, the temperature is 20-80℃ and the time is 2-8h.

[0021] In the preparation method described above, the temperature during the thermal activation treatment is 200-800℃ and the time is 6-48h.

[0022] In the preparation method described above, the molar ratio of the support to the first portion of the co-catalyst is (1-30):1; and / or,

[0023] In step 2), the temperature is 30-100℃ and the time is 2-6 hours.

[0024] In the preparation method described above, the pyrrole compound is selected from methyl methylpyrrole-2-carboxylate, ethyl pyrrole-2-carboxylate, methyl methylpyrrole-1-carboxylate, ethyl 4-methyl-2-pyrrolecarboxylate, methyl 1-methyl-2-pyrroleacetic acid, methyl pyrrole-3-carboxylate, ethyl 2,4-dimethylpyrrole-3-carboxylate, diethyl 3,4-pyrroledicarboxylate, ethyl pyrrole-3-carboxylate, diethyl 2,4-dimethylpyrrole-3,5-dicarboxylate, ethyl 2-methylpyrrole-3-carboxylate, methyl 3-(2-pyrrole)propionate, and ethyl 4-phenylpyrrole-3-carboxylate. Ethyl 4-methylpyrrole-3-carboxylate, ethyl 3,4-dimethylpyrrole-2-carboxylate, methyl 4-methylpyrrole-3-carboxylate, ethyl 3,4,5-trimethyl-2-pyrrolecarboxylate, ethyl 3-methylpyrrole-2-carboxylate, ethyl 5-methylpyrrole-2-carboxylate, methyl 2-methylpyrrole-3-carboxylate, methyl 5-methylpyrrole-2-carboxylate, methyl 3-methylpyrrole-2-carboxylate, methyl 1-methylpyrrole-3-carboxylate, ethyl 5-phenylpyrrole-3-carboxylate, methyl 1,2,5-trimethylpyrrole-3-carboxylate, or any combination thereof.

[0025] This invention provides a metallocene polypropylene catalyst, wherein the catalyst is prepared using the preparation method described above.

[0026] The method for preparing the metallocene polypropylene catalyst of the present invention uses an electron donor, a pyrrole compound containing an ester group, to modify the active site, thereby improving the activity of the metallocene polypropylene catalyst. Simultaneously, it alters the electronic and steric effects around the active site, increasing the variety of active sites and broadening the molecular weight distribution of the polypropylene obtained after polymerization, thus improving the processing performance of polypropylene. Furthermore, this preparation method is simple, uses few chemical reagents, and can be widely applied. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] A first aspect of the present invention provides a method for preparing a metallocene polypropylene catalyst, comprising the following steps:

[0029] 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier;

[0030] 2) The first part of the co-catalyst is loaded onto at least a portion of the surface of the activated support to obtain the first intermediate product;

[0031] 3) After the second part of the co-catalyst undergoes a first reaction with the metallocene compound, a pyrrole compound is added to undergo a second reaction, yielding the catalyst precursor;

[0032] 4) The first intermediate product is reacted with the catalyst precursor in a third reaction to obtain a metallocene polypropylene catalyst.

[0033] Among them, pyrrole compounds include ester groups;

[0034] In the second reaction, the temperature is 60-120℃ and the time is 2-16h.

[0035] The preparation method of the metallocene polypropylene catalyst of the present invention specifically includes:

[0036] 1) The carrier is thermally activated to improve its activity, which facilitates the subsequent loading of active components onto the surface of the carrier, thereby obtaining an activated carrier;

[0037] 2) The first part of the co-catalyst is loaded onto part or the entire surface of the activated support to obtain the first intermediate product;

[0038] 3) After the second part of the co-catalyst undergoes a first reaction with the metallocene compound, a pyrrole compound containing an ester group is added to undergo a second reaction, yielding the catalyst precursor;

[0039] 4) The first intermediate product undergoes a third reaction with the catalyst precursor, and the catalyst precursor is loaded onto the surface of the support to obtain a metallocene polypropylene catalyst.

[0040] The present invention does not impose any particular limitation on the carrier, which can be any carrier commonly used in the art. For example, the carrier can be selected from at least one of silica gel, magnesium chloride, alumina, montmorillonite, molecular sieve, polyethylene, polystyrene, polysiloxane, polyvinyl alcohol and polymethyl methacrylate. Further, the carrier can be silica gel.

[0041] This invention does not specifically limit the cocatalyst; it can be any cocatalyst commonly used in the art, such as alkylaluminoxane compounds or organoboron compounds. Alkylaluminoxane compounds include, but are not limited to, methylaluminoxane, ethylaluminoxane, butylaluminoxane, pentylaluminoxane, decylaluminoxane, modified methylaluminoxane, or mixtures thereof. Further, alkylaluminoxane compounds can be methylaluminoxane. Organoboron compounds include neutral boron compounds, borates, and combinations thereof. For example, organoboron compounds can be fluoroorganoboron compounds and fluoroorganoboronate compounds. Specifically, fluoroorganoboronate compounds include, but are not limited to, tetra(2,3,5,6-tetrafluorophenyl)borate, tetra(pentafluorophenyl)borate, N,N-dimethylaniline[3,5-bis(trifluoromethyl)phenyl]borate, or mixtures thereof. Fluoroorganoboron compounds include, but are not limited to, tris(pentafluorophenyl)borane, tris[3,5-bis(trifluoromethyl)phenyl]boron, or mixtures thereof.

[0042] This invention does not specifically limit the metallocene compounds; the metallocene compounds can be any commonly used metallocene compounds in the art. In some embodiments, the metallocene compounds have the general formula shown in Formula 1:

[0043]

[0044] In Formula 1, M is selected from transition metals of Groups III, IV, V, and VI of the periodic table, or lanthanides or osmium series elements; in some embodiments, M is selected from titanium, zirconium, or hafnium.

[0045] X is selected from hydrogen, halogen, R, OR, OCOR, SR, NR2, or PR2, wherein R is selected from substituted or unsubstituted C1-C. 40 Alkyl, substituted or unsubstituted C2-C 40 Alkenyl, substituted or unsubstituted C1-C 40 Alkyne, substituted or unsubstituted C6-C 40The aryl group, and the substituents can be halogenated, substituted, or unsubstituted C1-C. 30 Alkyl, C 6-30 Aryl group, exemplarily, R can be an alkyl-substituted aryl group or an aryl-substituted alkyl group; in some embodiments, R further comprises a heteroatom of Groups IIIA-VIIA of the periodic table; furthermore, R is selected from straight-chain or branched C1-C6 atoms. 20 Alkyl group; the two X groups may optionally form a substituted or unsubstituted butadienyl or OR'O group, wherein R' is selected from substituted or unsubstituted C1-C groups. 40 Alkylene, substituted or unsubstituted C6-C 40 The divalent group of the aryl group can have halogenated, substituted, or unsubstituted C1-C groups. 30 Alkyl, substituted or unsubstituted C6-C 40 Arylene, exemplarily, R can be an alkyl-substituted arylene or an arylene-substituted alkyl; further, X is selected from hydrogen, halogen, or the R group; even further, X is selected from chlorine or C. l -C 10 Alkyl groups (e.g., methyl or ethyl);

[0046] L is selected from divalent C1-C heteroatoms in Groups IIIA-VIIA of the periodic table. 40 The hydrocarbon group or a divalent silyl group containing up to 5 silicon atoms; further, L is selected from a divalent bridging group, wherein the bridging group is selected from substituted or unsubstituted C1-C groups. 40 Alkylenes (including chain alkylenes or cycloalkylenes), substituted or unsubstituted C6-C 40 aryl groups, where the substituents can be halogenated, substituted, or unsubstituted C1-C. 30 Alkyl, substituted or unsubstituted C6-C 40 aryl group; in some embodiments, L further comprises a heteroatom belonging to Groups IIIA-VIIA of the periodic table, or a silyl group containing up to 5 silicon atoms, such as SiMe2, SiPh2; further, L is a group (Z(R″)2)n, wherein Z is a carbon or silicon atom, n is 1 or 2, and R″ optionally comprises C1-C of a heteroatom belonging to Groups 13-17 of the periodic table. 20 Hydrocarbon group; further, R″ is selected from substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C2-C 20 Alkenyl, substituted or unsubstituted C2-C 20 Alkyne, substituted or unsubstituted C6-C 20 The aryl group, and the substituents can be halogenated, substituted, or unsubstituted C1-C. 20 Alkyl, substituted or unsubstituted C6-C 20The aryl group optionally contains a heteroatom belonging to Groups IIIA-VIIA of the periodic table; further, the (Z(R″)2)n group is selected from Si(CH3)2, SiPh2, SiPhMe, SiMe(SiMe3), CH2, (CH2)2 and C(CH2)2; even further, ((Z(R″)2)n is Si(CH3)2. 1 and R 5 Optionally includes C1-C of heteroatoms from Groups IIIA-VIIA of the periodic table 40 hydrocarbon groups; further, R 1 and R 5 Selected from substituted or unsubstituted C1-C 40 Alkyl, substituted or unsubstituted C2-C 40 Alkenyl, substituted or unsubstituted C1-C 40 Alkyne, substituted or unsubstituted C6-C 40 The aryl group, and the substituents can be halogenated, substituted, or unsubstituted C1-C. 30 Alkyl, substituted or unsubstituted C6-C 40 Alpha-aryl; furthermore, R 1 and R 5 It contains heteroatoms from Groups IIIA to VIIA of the periodic table; furthermore, R 1 and R 5 It is a straight-chain or branched, saturated or unsaturated C1-C 20 alkyl;

[0047] R 2 R 3 and R 4 They may be equal to or different from each other, and are selected from hydrogen atoms or C1-C atoms containing heteroatoms belonging to Groups IIIA-VIIA of the periodic table. 40 Hydrocarbon group; further, R 2 R 3 and R 4 They are equal to or different from each other, and are hydrogen, substituted or unsubstituted C1-C. 40 Alkyl, substituted or unsubstituted C2-C 40 Alkenyl, substituted or unsubstituted C1-C 40 Alkyne group, substituted or unsubstituted C6-C 40 The aryl group, and the substituents can be halogenated, substituted, or unsubstituted C1-C. 40 Alkyl, substituted or unsubstituted C6-C 40 aryl; optionally containing heteroatoms from Groups IIIA to VIIA of the periodic table; furthermore, R 2 R 3 and R 4 It is a hydrogen atom or C1-C 20 alkyl.

[0048] R 6 R 7 R 8 R 9 and R 10 They are equal to or different from each other, selected from hydrogen or C1-C2 elements containing heteroatoms belonging to Groups IIIA-VIIA of the periodic table. 40 Hydrocarbon group; further, R 6 R 7 R 8 R 9 and R 10 They may be equal to or different from each other, and are selected from hydrogen, substituted or unsubstituted C1-C. 40 Alkyl, substituted or unsubstituted C2-C 40 Alkenyl, substituted or unsubstituted C1-C 40 Alkyne group, substituted or unsubstituted C6-C 40 The aryl group, and the substituents can be halogenated, substituted, or unsubstituted C1-C. 40 Alkyl, substituted or unsubstituted C6-C 40 aryl; optionally containing heteroatoms from Groups IIIA to VIIA of the periodic table; furthermore, R 6 R 7 R 8 R 9 and R 10 At least one of them is not a hydrogen atom; furthermore, R 6 R 7 R 8 R 9 and R 10 It is a hydrogen atom; further, R 8 It is C l -C 40 Alkyl, and further, R 8 It is C l -C 40 Alkyl groups, wherein the atom at the α-position is a secondary or tertiary carbon, such as isopropyl or tert-butyl;

[0049] In some embodiments, M can be titanium, zirconium, or hafnium; X can be chlorine; L can be Si(CH3)2 or (CH2)2; R 1 and R 5 Selected from C1-C 20 hydrocarbon group; R 2 R 3 and R 4 Selected from hydrogen atoms or C1-C 20 Alkyl; R 8 Selected from C l -C 40 Alkyl group, wherein the atom at the α-position is a secondary or tertiary carbon.

[0050] The method for preparing the metallocene polypropylene catalyst of the present invention involves modifying the active sites using electron donors of pyrrole compounds containing ester groups under specific reaction conditions. This enhances the activity of the metallocene polypropylene catalyst and alters the electronic and steric effects around the active sites, resulting in a greater variety of active sites and a wider molecular weight distribution of the polypropylene obtained after polymerization, thereby improving the processing performance of polypropylene. Furthermore, this preparation method is simple, uses few chemical reagents, and can be widely applied.

[0051] In some embodiments of the present invention, when the molar ratio of pyrrole compound to metallocene compound is (0.01-1):1, the pyrrole compound and the metallocene compound can be better matched, resulting in a metallocene polypropylene catalyst with excellent activity. Further, the molar ratio of pyrrole compound to metallocene compound can be (0.1-1):1.

[0052] Furthermore, in the second reaction, the temperature can be 70-100℃ and the time can be 2-8h.

[0053] The inventors also discovered that when the molar ratio of the second-part co-catalyst to the metallocene compound is (10-100):1, the co-catalyst can react more fully with the metallocene compound, thereby improving the activity of the metallocene polypropylene catalyst.

[0054] Furthermore, when the temperature in the first reaction is 20-100℃ and the time is 1-24h, the metallocene compound and the co-catalyst can fully react in the first reaction while saving energy, thus improving the spark of the metallocene polypropylene catalyst. In some embodiments, the temperature in the first reaction is 20-60℃ and the time is 4-8h.

[0055] In some embodiments of the present invention, when the molar ratio of the metallocene compound to the support is (0.001-0.01):1, the metallocene compound can be more fully loaded onto the support while conserving the metallocene compound, resulting in a metallocene polypropylene catalyst with excellent overall performance.

[0056] Furthermore, when the temperature is 20-80℃ and the time is 2-8h in the third reaction, the metallocene compound, support, pyrrole compound and co-catalyst can react more fully to obtain a more active metallocene polypropylene catalyst.

[0057] The inventors also discovered that when the thermal activation treatment is carried out at a temperature of 200-800℃ for 6-48 hours, the support can be activated more fully while saving energy. This allows the activated support to better combine with the subsequent co-catalyst, metallocene compounds, and pyrrole compounds, resulting in a metallocene polypropylene catalyst with superior activity.

[0058] Furthermore, when the molar ratio of the support to the first cocatalyst is (1-30):1, a metallocene polypropylene catalyst with excellent activity can be prepared with less cocatalyst. In some embodiments, the molar ratio of the support to the cocatalyst can be (1-20):1.

[0059] In particular, when the temperature is 30-100℃ and the time is 2-6h in step 2), the co-catalyst can be more fully loaded on the surface of the activated support, improving the reaction efficiency of the subsequent first, second, and third reactions, resulting in a metallocene polypropylene catalyst with superior overall performance. In some embodiments, the temperature in step 2) can be 50-80℃ and the time can be 2-6 hours.

[0060] This invention does not particularly limit the pyrrole compound and can use any pyrrole compound containing an ester group commonly used in the art. In some embodiments of this invention, when the pyrrole compound is selected from methyl methylpyrrole-2-carboxylate, ethyl pyrrole-2-carboxylate, methyl methylpyrrole-1-carboxylate, ethyl 4-methyl-2-pyrrolecarboxylate, methyl 1-methyl-2-pyrroleacetic acid, methyl pyrrole-3-carboxylate, ethyl 2,4-dimethylpyrrole-3-carboxylate, diethyl 3,4-pyrroledicarboxylate, ethyl pyrrole-3-carboxylate, diethyl 2,4-dimethylpyrrole-3,5-dicarboxylate, ethyl 2-methylpyrrole-3-carboxylate, methyl 3-(2-pyrrole)propionate, ethyl 4-phenylpyrrole-3-carboxylate, ethyl 4-methylpyrrole-3-carboxylate, ... When ethyl 3,4-dimethyl-pyrrole-2-carboxylate, methyl 4-methyl-pyrrole-3-carboxylate, ethyl 3,4,5-trimethyl-2-pyrrolecarboxylate, ethyl 3-methyl-pyrrole-2-carboxylate, ethyl 5-methyl-pyrrole-2-carboxylate, methyl 2-methyl-pyrrole-3-carboxylate, methyl 5-methyl-pyrrole-2-carboxylate, methyl 3-methyl-pyrrole-2-carboxylate, methyl 1-methyl-pyrrole-3-carboxylate, ethyl 5-phenyl-pyrrole-3-carboxylate, methyl 1,2,5-trimethyl-pyrrole-3-carboxylate, or any combination thereof, the pyrrole compound can further enhance the activity of the metallocene polypropylene catalyst. In some embodiments, methyl methyl-pyrrole-2-carboxylate can be methyl 1-methyl-pyrrole-2-carboxylate.

[0061] In some embodiments of the present invention, the metallocene polypropylene catalyst can be prepared by a method including the following steps:

[0062] 1) The carrier is calcined under nitrogen to perform thermal activation treatment to obtain activated carrier. The temperature of thermal activation treatment is 200-800℃ and the time is 6-48 hours.

[0063] 2) Under nitrogen protection, toluene is used as a solvent, an activated support is added, and then the first part of the co-catalyst is added. The molar ratio of the support to the first part of the co-catalyst is controlled to be (1~30):1. The reaction temperature is 30℃~100℃ and the reaction time is 1~12 hours, so that the first part of the co-catalyst is loaded on at least part of the surface of the activated support to obtain the first intermediate product.

[0064] 3) In a toluene solution, a second part of the co-catalyst and a metallocene compound are added, and the molar ratio of the second part of the co-catalyst to the metallocene compound is controlled at (10-100):1, so that the second part of the co-catalyst and the metallocene compound undergo a first reaction. The reaction temperature is 20℃-100℃, and the reaction time is 1-24 hours. After the reaction is completed, a pyrrole compound is added to undergo a second reaction to obtain a slurry containing the catalyst precursor. The molar ratio of the pyrrole compound to the metallocene compound is controlled at (0.01-1):1, the reaction temperature is 60℃-120℃, and the reaction time is 2-16 hours.

[0065] 4) The first intermediate product obtained in 2) is added to the slurry in 3) to carry out the third reaction. The ratio of metallocene compound to support is controlled at (0.001-0.01):1. The reaction is carried out at 20-80℃ for 2-8 hours to obtain a slurry containing metallocene compound.

[0066] In this invention, the slurry containing the metallocene polypropylene catalyst after the reaction is completed can be directly used for the polymerization reaction, or the slurry containing the metallocene polypropylene catalyst can be filtered, washed, and dried under reduced pressure to obtain a solid metallocene polypropylene catalyst, which can then be used for the polymerization reaction.

[0067] A second aspect of the present invention provides a metallocene polypropylene catalyst prepared using the preparation method of the first aspect.

[0068] The metallocene polypropylene catalyst of the present invention uses an electron donor of an ester-containing pyrrole compound for active center modification. This metallocene polypropylene catalyst has excellent activity, and with the change of electronic and spatial effects around the active center, the types of active centers increase, resulting in a wider molecular weight distribution of polypropylene obtained after polymerization, thereby improving the processing performance of polypropylene.

[0069] The technical solution of the present invention will be further described below with reference to specific embodiments. The sources of the chemical reagents in the embodiments and comparative examples of the present invention are as follows:

[0070] Toluene and hexane: Xilong Scientific Co., Ltd.;

[0071] Methylaluminoxane and silica gel: Grace Corporation, USA.

[0072] Example 1

[0073] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0074] 1 mol of Grace Davison 955 silica gel (support) and 0.2 mol of methylaluminoxane were added to 300 mL of toluene after thermal activation at 600 °C for 12 hours. The mixture was heated to 50 °C and reacted for 6 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0075] In 300 mL of toluene, 0.1 mol of methylaluminoxane and 0.001 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and heated to 60 °C for 4 hours. Then, 0.001 mol of methyl 1-methylpyrrole-2-carboxylate was added and heated to 80 °C for 8 hours to obtain the catalyst precursor.

[0076] The first intermediate was added to the catalyst precursor, and the mixture was heated to 80°C and reacted for 2 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0077] Example 2

[0078] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0079] 1 mol of Grace Davison 955 silica gel and 0.1 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 50 °C and reacted for 4 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0080] In 300 mL of toluene, 0.05 mol of methylaluminoxane and 0.005 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added. After reacting at 20 °C for 8 hours, 0.003 mol of pyrrole-2-carboxylate was added, and the mixture was heated to 100 °C for 8 hours to obtain the catalyst precursor.

[0081] The first intermediate was added to the catalyst precursor, and the reaction was carried out at 60°C for 6 hours. After washing with toluene and hexane three times each, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0082] Example 3

[0083] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0084] 1 mol of Grace Davison 955 silica gel and 0.05 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 50 °C and reacted for 6 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0085] In 300 mL of toluene, 0.5 mol of methylaluminoxane and 0.001 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added. After reacting at 40 °C for 6 hours, 0.007 mol of methyl 1-methyl-2-pyrroleacetic acid was added, and the mixture was heated to 100 °C for 2 hours to obtain the catalyst precursor.

[0086] The first intermediate was added to the catalyst precursor, and the mixture was heated to 80°C and reacted for 2 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0087] Example 4

[0088] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0089] 1 mol of Grace Davison 955 silica gel and 0.5 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 70 °C and reacted for 3 hours. After washing with toluene three times, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0090] In 300 mL of toluene, 0.01 mol of methylaluminoxane and 0.001 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added, and the mixture was cooled to 30 °C and reacted for 6 hours. Then, 0.001 mol of diethyl 3,4-pyrroledicarboxylate was added, and the mixture was heated to 80 °C and reacted for 3 hours to obtain the catalyst precursor.

[0091] The first intermediate was added to the catalyst precursor, and the reaction was carried out at 20°C for 8 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0092] Example 5

[0093] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0094] 1 mol of Grace Davison 955 silica gel and 1 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 60 °C and reacted for 4 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0095] In 300 mL of toluene, 0.3 mol of methylaluminoxane and 0.008 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added. After reacting at 20 °C for 8 hours, 0.004 mol of methyl 4-methylpyrrole-3-carboxylate was added, and the mixture was heated to 80 °C and reacted for 8 hours to obtain the catalyst precursor.

[0096] The first intermediate was added to the catalyst precursor, and the mixture was heated to 80°C and reacted for 2 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0097] Example 6

[0098] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0099] 1 mol of Grace Davison 955 silica gel and 1 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 60 °C and reacted for 4 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0100] In 300 mL of toluene, 0.5 mol of methylaluminoxane and 0.005 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and heated to 60 °C for 4 hours. Then, 0.003 mol of ethyl 2-methylpyrrole-3-carboxylate was added and the temperature was raised to 90 °C for 6 hours to obtain the catalyst precursor.

[0101] The first intermediate was added to the catalyst precursor, and the reaction was carried out at 50°C for 8 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0102] Example 7

[0103] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0104] 1 mol of Grace Davison 955 silica gel and 0.6 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 80 °C and reacted for 2 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0105] In 300 mL of toluene, 0.1 mol of methylaluminoxane and 0.01 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and heated to 60 °C for 4 hours. Then, 0.001 mol of ethyl 5-methylpyrrole-2-carboxylate was added and the temperature was raised to 80 °C for 6 hours to obtain the catalyst precursor.

[0106] The first intermediate was added to the catalyst precursor, and the mixture was heated to 60°C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0107] Example 8

[0108] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0109] 1 mol of Grace Davison 955 silica gel and 0.08 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 80 °C and reacted for 6 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0110] In 300 mL of toluene, 0.4 mol of methylaluminoxane and 0.008 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and reacted at 50 °C for 4 hours. Then, 0.08 mol of methyl 1-methylpyrrole-3-carboxylate was added and the temperature was raised to 75 °C for 6 hours to obtain the catalyst precursor.

[0111] The first intermediate was added to the catalyst precursor, and the reaction was carried out at 20°C for 8 hours. After washing with toluene and hexane three times each, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0112] Example 9

[0113] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0114] 1 mol of Grace Davison 955 silica gel and 0.8 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 50 °C and reacted for 5 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0115] In 300 mL of toluene, 0.15 mol of methylaluminoxane and 0.003 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and heated to 40 °C for 5 hours. Then, 0.003 mol of ethyl 4-phenylpyrrole-3-carboxylate was added and the temperature was raised to 100 °C for 2 hours to obtain the catalyst precursor.

[0116] The first intermediate was added to the catalyst precursor, and the reaction was carried out at 20°C for 8 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0117] Example 10

[0118] The preparation method of the metallocene polypropylene catalyst in this embodiment includes the following steps:

[0119] 1 mol of Grace Davison 955 silica gel and 0.6 mol of methylaluminoxane, which were thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 50 °C and reacted for 6 hours. After washing three times with toluene, the solvent was removed under negative pressure to obtain a solid powder with a catalyst supported (first intermediate product).

[0120] In 300 mL of toluene, 0.5 mol of methylaluminoxane and 0.007 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride were added and heated to 60 °C for 8 hours. Then, 0.002 mol of ethyl 3,4-dimethyl-pyrrole-2-carboxylate was added and the temperature was raised to 70 °C for 8 hours to obtain the catalyst precursor.

[0121] The first intermediate was added to the catalyst precursor, and the mixture was heated to 80°C and reacted for 2 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0122] Comparative Example 1

[0123] The preparation method of the metallocene polypropylene catalyst in this comparative example includes the following steps:

[0124] 1 mol of Grace Davison 955 silica gel and 0.2 mol of methylaluminoxane, which had been thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 50 °C and reacted for 6 hours. Then, 0.001 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added. The mixture was cooled to -15 °C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0125] Comparative Example 2

[0126] The preparation method of the metallocene polypropylene catalyst in this comparative example includes the following steps:

[0127] 1 mol of Grace Davison 955 silica gel and 0.15 mol of methylaluminoxane were added to 300 mL of toluene after thermal activation at 600 °C for 12 hours. The mixture was heated to 50 °C and reacted for 6 hours. Then, 0.005 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added. The mixture was cooled to -15 °C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0128] Comparative Example 3

[0129] The preparation method of the metallocene polypropylene catalyst in this comparative example includes the following steps:

[0130] 1 mol of Grace Davison 955 silica gel and 0.65 mol of methylaluminoxane, which had been thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 80 °C and reacted for 2 hours. Then, 0.001 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added. The mixture was cooled to 0 °C and reacted for 8 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0131] Comparative Example 4

[0132] The preparation method of the metallocene polypropylene catalyst in this comparative example includes the following steps:

[0133] 1 mol of Grace Davison 955 silica gel and 0.15 mol of methylaluminoxane, which had been thermally activated at 600 °C for 12 hours, were added to 300 mL of toluene. The mixture was heated to 60 °C and reacted for 6 hours. Then, 0.001 mol of dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added. The mixture was cooled to -30 °C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0134] Comparative Example 5

[0135] The preparation method of the metallocene polypropylene catalyst in this comparative example includes the following steps:

[0136] 1 mol of Grace Davison 955 silica gel and 0.08 mol of methylaluminoxane were added to 300 mL of toluene after thermal activation at 600 °C for 12 hours. The mixture was heated to 50 °C and reacted for 5 hours. Then, 0.008 mol of dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride was added. The mixture was cooled to -15 °C and reacted for 6 hours. After washing three times each with toluene and hexane, the toluene solvent was removed under negative pressure to obtain the metallocene polypropylene catalyst.

[0137] Test case

[0138] The metallocene polypropylene catalysts used in the examples and comparative examples were subjected to polymerization reactions, specifically including:

[0139] The reactor was evacuated and purged with nitrogen three times. 3 kg of propylene was added, followed by 90 mmol of triethylaluminum and 0.1 g of hydrogen. After stirring for 30 minutes, 50 mg of catalyst from Examples 1-10 and Comparative Examples 1-5 were added respectively. Polymerization was then carried out at 70°C for 1 hour, and the reaction was terminated to obtain resin powder. The catalytic activity and polymer molecular weight distribution (PDI) were tested. Results are shown in Table 1.

[0140] The catalyst activity was calculated as the mass of the prepared polyolefin divided by the mass of the solid catalyst component. Polymer molecular weight distribution (PDI) was determined using gel permeation chromatography with o-dichlorobenzene as the mobile phase solvent. Narrowly distributed polystyrene was used as a standard for general calibration at a test temperature of 135°C.

[0141] Table 1. Catalyst activity and polymer molecular weight distribution obtained in the examples and comparative examples.

[0142]

[0143]

[0144] As can be seen from Table 1, the metallocene polypropylene catalyst in the embodiments of the present invention has higher catalytic activity when applied to the polymerization reaction, and the resulting polypropylene product has a wider molecular weight distribution.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a metallocene polypropylene catalyst, characterized in that, Includes the following steps: 1) The carrier is subjected to thermal activation treatment to obtain an activated carrier; 2) The first portion of the co-catalyst is loaded onto at least a portion of the surface of the activated support to obtain a first intermediate product; 3) After the second part of the co-catalyst undergoes a first reaction with the metallocene compound, a pyrrole compound is added to undergo a second reaction, yielding the catalyst precursor; 4) The first intermediate product is reacted with the catalyst precursor in a third reaction to obtain the metallocene polypropylene catalyst; The pyrrole compound includes an ester group; In the second reaction, the temperature is 60-120℃ and the time is 2-16h.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the pyrrole compound to the metallocene compound is (0.01-1):

1.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of the second part of the co-catalyst to the metallocene compound is (10-100):

1.

4. The preparation method according to any one of claims 1-3, characterized in that, In the first reaction, the temperature is 20-100℃ and the time is 1-24h.

5. The preparation method according to any one of claims 1-4, characterized in that, The molar ratio of the metallocene compound to the support is (0.001-0.01):

1.

6. The preparation method according to any one of claims 1-5, characterized in that, In the third reaction, the temperature is 20-80℃ and the time is 2-8h.

7. The preparation method according to any one of claims 1-6, characterized in that, In the aforementioned thermal activation treatment, the temperature is 200-800℃ and the time is 6-48h.

8. The preparation method according to any one of claims 1-7, characterized in that, The molar ratio of the support to the first portion of the co-catalyst is (1-30):1; and / or, In step 2), the temperature is 30-100℃ and the time is 2-6 hours.

9. The preparation method according to any one of claims 1-8, characterized in that, The pyrrole compound is selected from methyl methylpyrrole-2-carboxylate, ethyl pyrrole-2-carboxylate, methyl methylpyrrole-1-carboxylate, ethyl 4-methyl-2-pyrrolecarboxylate, methyl 1-methyl-2-pyrroleacetic acid, methyl pyrrole-3-carboxylate, ethyl 2,4-dimethylpyrrole-3-carboxylate, diethyl 3,4-pyrroledicarboxylate, ethyl pyrrole-3-carboxylate, diethyl 2,4-dimethylpyrrole-3,5-dicarboxylate, ethyl 2-methylpyrrole-3-carboxylate, methyl 3-(2-pyrrole)propionate, ethyl 4-phenylpyrrole-3-carboxylate, and 4-methylpyrrole. Ethyl 3-carboxylate, ethyl 3,4-dimethyl-pyrrole-2-carboxylate, methyl 4-methyl-pyrrole-3-carboxylate, ethyl 3,4,5-trimethyl-2-pyrrolecarboxylate, ethyl 3-methyl-pyrrole-2-carboxylate, ethyl 5-methyl-pyrrole-2-carboxylate, methyl 2-methyl-pyrrole-3-carboxylate, methyl 5-methyl-pyrrole-2-carboxylate, methyl 3-methyl-pyrrole-2-carboxylate, methyl 1-methyl-pyrrole-3-carboxylate, ethyl 5-phenyl-pyrrole-3-carboxylate, methyl 1,2,5-trimethyl-pyrrole-3-carboxylate, or any combination thereof.

10. A metallocene polypropylene catalyst, characterized in that, It was prepared using the preparation method according to any one of claims 1-9.

Images