CN111019023B

CN111019023B - Catalyst for olefin polymerization, preparation method thereof, catalyst composition for olefin polymerization and application thereof

Info

Publication number: CN111019023B
Application number: CN201811172132.7A
Authority: CN
Inventors: 张雅茹; 杨芝超; 张锐; 杜亚锋; 周奇龙; 谭忠; 陈江波; 仝钦宇; 徐秀东
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Chemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2018-10-09
Filing date: 2018-10-09
Publication date: 2022-07-12
Anticipated expiration: 2038-10-09
Also published as: CN111019023A

Abstract

The invention relates to the field of olefin polymerization catalysts, and discloses an olefin polymerization catalyst which comprises a catalyst precursor and a polymer of a structural unit shown in a formula (IV), wherein the catalyst precursor contains an alkoxy magnesium carrier shown in the formula (I), an electron donor compound shown in the formula (II), a titanium compound shown in the formula (III) and an organic aluminum compound shown in the formula (V), and the polymer of the structural unit shown in the formula (IV) coats the catalyst precursor. The catalyst has uniform particle size distribution, and when the catalyst component containing the catalyst is applied to olefin polymerization, the catalyst not only has the characteristics of high activity and low fine powder content, but also is not easy to generate activity attenuation under the condition of normal-temperature storage, the isotacticity of the polymer is high, the fine powder content in polymer powder is reduced, and the bulk density is high. Mg (OEt)_2‑m(OEHA)_mFormula (I)

TiX_n(OR⁷)_4‑nFormula (III) -CH₂CHR⁸AlR of formula (IV)⁹ _nY_3‑nFormula (IV).

Description

Catalyst for olefin polymerization, preparation method thereof, catalyst composition for olefin polymerization and application thereof

Technical Field

The invention relates to the field of olefin polymerization catalysts, in particular to a catalyst for olefin polymerization and a preparation method thereof, a catalyst composition for olefin polymerization and application thereof in olefin polymerization.

Background

Polypropylene (PP) is a thermoplastic plastic with excellent performance, is one of five general synthetic resins, has the advantages of low density, no toxicity, easy processing, high impact strength, good flexibility resistance, good electrical insulation and the like, and is widely applied to the fields of electronic and electric appliances, automobiles, building materials, medical treatment, packaging and the like. Currently, Ziegler-Natta (Z-N) catalysts are the primary catalysts for producing polypropylene, with over 90% of the polypropylene produced worldwide each year using Z-N catalysts. However, the initial activity of the Z-N catalyst is relatively high, which results in large temperature fluctuation at the initial stage of the gas phase polymerization reaction and easy generation of hot spots. The strength of the catalyst particles is difficult to withstand the extrusion of the rapidly growing polymer, which in turn creates problems of catalyst breakage, excessive polymer fines, etc. On the other hand, the particle size of the catalyst also affects the particle morphology of the polymer. When the catalyst has a small particle size or a non-uniform particle size distribution, the content of fine particles in the polymer is higher. Polymer fines tend to generate static electricity, adhere to the reactor surfaces and cause fouling which reduces the reactor operating efficiency and may even cause the polymerization equipment to stop operating.

In order to solve the above problems, it is necessary to reduce the initial activity of the catalyst, to increase the strength of catalyst particles, and to control the particle size and particle size distribution of the catalyst. At present, the method widely used in industry is to introduce a prepolymerization technology. After prepolymerization, the catalyst particles become large, the resistance is improved and the morphology is controlled. The polymerization processes of the liquid-phase bulk method, such as the Spheripol process, the Borstar process, the Hypol process, etc., all use a prepolymerization technique. In the gas phase polypropylene process, such as the innoven process, the Novolen process, the Unipol process and the like, since a prepolymerization technology is not introduced during design, the problems that the catalyst particles are crushed to generate fine powder due to an excessively high polymerization rate and part of active centers are permanently inactivated due to an excessively high internal temperature of the catalyst particles exist. The introduction of continuous prepolymerization technology into gas phase polypropylene processes can alleviate such problems, but involves relatively large equipment modifications and high capital costs, which are not achievable on many plants.

The prepolymerized catalyst is directly used on the polymerization equipment of the polymerization device, new equipment is not required to be introduced, the purposes of increasing the particle strength and reducing the content of fine powder can be achieved, and the cost can be saved. WO99/48929 and WO10/34664 disclose prepolymerized catalyst components each comprising Ti, Mg, an electron donor and a certain amount of ethylene polymer. However, the prepolymerization catalyst has the problems of longer catalyst synthesis time, lower efficiency, low activity and the like.

Therefore, it is necessary to find a catalyst which can be used for olefin polymerization and has the characteristics of uniform particle size, high activity and low fine powder content; on the premise of not increasing the modification cost and energy consumption of the device, the capacity of the gas phase process device for producing the product grade with high rubber content can be widened.

Disclosure of Invention

The invention aims to overcome the defects of long catalyst synthesis time, low efficiency and low activity of a prepolymerization catalyst in the prior art, and provides a catalyst for olefin polymerization, which has uniform particle size, not only has the characteristics of high activity and low fine powder content when being applied to olefin polymerization, but also is not easy to generate activity attenuation under the condition of normal-temperature storage, and has high isotacticity of a polymer, low fine powder content in polymer powder and high bulk density.

In order to achieve the above object, a first aspect of the present invention provides a catalyst for olefin polymerization, the catalyst comprising a catalyst precursor and a polymer having a structural unit represented by formula (IV), the catalyst precursor comprising an alkoxy magnesium support represented by formula (I), an electron donor compound represented by formula (II), a titanium compound represented by formula (III), and an organoaluminum compound represented by formula (V), the polymer having a structural unit represented by formula (IV) coating the catalyst precursor;

Mg(OEt)_2-m(OEHA)_mformula (I)

TiX_n(OR⁷)_4-nFormula (III)

－CH₂CHR⁸-formula (IV)

AlR⁹ _nY_3-nFormula (IV)

In the formula (I), Et is ethyl, EHA is 2-ethylhexyl, and m is more than or equal to 0.001 and less than or equal to 0.5;

in the formula (II), R¹And R²The same or different, each is independently selected from one of straight-chain alkyl with 1-12 carbon atoms, branched-chain alkyl with 3-12 carbon atoms, naphthenic base with 3-10 carbon atoms, alkylaryl with 7-20 carbon atoms and substituted or unsubstituted aromatic hydrocarbon with 7-20 carbon atoms; r⁴And R⁵The same or different, each is independently selected from one of straight-chain alkyl with the carbon atom number of 1-10, branched-chain alkyl with the carbon atom number of 3-10, naphthenic base with the carbon atom number of 3-10, alkylaryl with the carbon atom number of 7-20 and substituted or unsubstituted aromatic hydrocarbon with the carbon atom number of 7-20; r³And R⁶The two are the same or different and are respectively and independently selected from one of hydrogen and C1-10 linear alkyl or C3-10 branched alkyl;

in the formula (III), X is halogen and R⁷Is a hydrocarbon group having 1-20 carbon atoms, n is an integer of 0-4, and when n is less than or equal to 2, R is⁷The same or different;

in the formula (IV), R⁸Is H or C1-C6 alkyl;

in the formula (V), R⁹Is hydrogen or a hydrocarbon group having 1 to 20 carbon atoms; y is halogen, and n is an integer of 1 to 3.

Preferably, in formula (I), 0.001. ltoreq. m.ltoreq.0.25;

in the formula (II), R³、R⁴、R⁵And R⁶One or more of the groups are optionally linked to form a ring;

in the formula (III), X is chlorine, bromine or iodine; r⁷Is a hydrocarbon group with 1-10 carbon atoms;

in the formula (IV), R⁸Is H, methyl, ethyl, n-butyl or n-hexyl;

in the formula (V), R⁹Is hydrogen, methyl, ethyl, butyl, isobutyl, n-hexyl or n-octyl and Y is chlorine or bromine.

Preferably, the polymer is present in an amount of from 5 wt% to 95 wt%, preferably from 10 wt% to 90 wt%, based on the total weight of the catalyst.

Preferably, the molar ratio of the titanium compound, the electron donor compound, the magnesium alkoxide support, calculated as magnesium, to the organoaluminum compound, calculated as aluminum, is 1: (0.00005-20): (0.01-2): (0.01-100), preferably 1: (0.0002-1): (0.02-1): (0.05-10).

Preferably, the magnesium alkoxide support has an average particle size of 10 to 150 μm and a particle size distribution index SPAN < 1.1.

Preferably, the catalyst has a particle size distribution index SPAN < 0.75.

In a second aspect, the present invention provides a method for preparing the catalyst of the present invention, wherein the method comprises the steps of:

1) under the protection of inert gas, carrying out reflux reaction on metal magnesium, ethanol and 2-ethylhexanol in the presence of a halogenating agent to prepare an alkoxy magnesium carrier;

2) in the presence of an inert diluent, carrying out contact reaction on the alkoxy magnesium carrier, the electron donor compound and the titanium compound, washing by an inert solvent and drying to obtain a catalyst solid component;

3) mixing the solid catalyst component with an alkane solvent, adding an organic aluminide for first treatment to prepare a catalyst precursor, and then introducing olefin for second treatment;

4) washing, filtering and drying the product obtained in the step 3) by using alkane and/or arene to obtain a catalyst;

the structure of the electron donor compound is shown in a formula (II), the structure of the titanium compound is shown in a formula (III), the structure of the olefin is shown in a formula (IV'), and the structure of the organic alumina is shown in a formula (V);

TiX_n(OR⁷)_4-nformula (III)

CH₂＝CHR⁸Formula (IV')

AlR⁹ _nY_3-nFormula (V)

in the formula (IV'), R⁸Is H or C1-C6 alkyl;

in the formula (V), R⁹Is hydrogenOr a hydrocarbon group having 1 to 20 carbon atoms; y is halogen, and n is an integer of 1 to 3.

Preferably, in formula (II), R³、R⁴、R⁵And R⁶One or more of the groups are optionally linked to form a ring;

in the formula (IV'), the olefin is ethylene, propylene, 1-butene, 1-hexene or 1-octene.

In the formula (V), the alkyl is methyl, ethyl, butyl, isobutyl, hexyl or octyl, and Y is chlorine or bromine.

Preferably, in step 1), the reaction temperature may be 30 to 90 ℃ and the reaction time may be 2 to 30 hours.

Preferably, in step 1), the halogenating agent may be an elemental halogen and/or a halogen compound; more preferably, the halogenating agent may be at least one of iodine, bromine, chlorine, magnesium chloride, magnesium bromide, magnesium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, mercury chloride, mercury bromide, mercury iodide, ethoxymagnesium iodide, methoxymagnesium iodide, isopropylmagnesium iodide, hydrogen chloride and chloroacetyl chloride;

preferably, in the step 1), the mass ratio of the metal magnesium to the ethanol and the 2-ethylhexanol may be 1: (4-50), more preferably 1: (6-25);

the content of ethanol is 70-99 wt% based on the total weight of ethanol and 2-ethylhexanol;

the molar ratio of the metallic magnesium to the halogen atoms in the halogenating agent may be 1: (0.0002-0.2), preferably 1: (0.001-0.08);

in the halogenating agent, the weight ratio of halogen to halogen compound may be 1: (0.02-20), preferably 1; (0.1-10);

preferably, in the step 2), the contact reaction temperature can be-40 ℃ to 200 ℃, and the reaction time can be 1min to 20h, more preferably the reaction temperature is-20 ℃ to 150 ℃, and the reaction time is 5min to 8 h.

Preferably, in the step 3), the first treatment time is 0.01-300 min;

in the second treatment, the addition rate of the olefin may be 0.01 to 10g/g solid catalyst component · h, the treatment time may be 0.1 to 50h, and the treatment temperature may be-20 ℃ to 50 ℃.

Preferably, in the step 3), hydrogen is introduced while introducing the olefin, and the partial pressure ratio of the hydrogen to the olefin is (0.01-100): 1, preferably (0.1-50): 1.

in a third aspect, the present invention provides a catalyst composition for olefin polymerization, wherein the catalyst composition comprises a catalyst active component, an external electron donor organoaluminum compound and/or an external electron donor compound, and the catalyst active component is the catalyst according to the first aspect of the present invention or the catalyst prepared by the method according to the second aspect of the present invention.

In a fourth aspect, the present invention provides the use of the catalyst composition of the invention in the polymerisation of olefins.

Through the technical scheme, the initial activity of the catalyst is reduced through a prepolymerization technology, and the catalyst for olefin polymerization is provided.

Drawings

FIG. 1 shows the polypropylene powder obtained in example 1 of the present invention;

FIG. 2 shows the polypropylene powder obtained in comparative example 1 according to the present invention.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and these ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a catalyst for olefin polymerization, which comprises a catalyst precursor and a polymer of a structural unit shown in a formula (IV), wherein the catalyst precursor contains an alkoxy magnesium carrier shown in the formula (I), an electron donor compound shown in the formula (II), a titanium compound shown in the formula (III) and an organic aluminum compound shown in the formula (V), and the polymer of the structural unit shown in the formula (IV) coats the catalyst precursor;

Mg(OEt)_2-m(OEHA)_mformula (I)

TiX_n(OR⁷)_4-nFormula (III)

－CH₂CHR⁸-formula (IV)

AlR⁹ _nY_3-nFormula (IV)

in the formula (II), R¹And R²The same or different, each is independently selected from one of straight-chain alkyl with 1-12 carbon atoms, branched-chain alkyl with 3-12 carbon atoms, naphthenic base with 3-10 carbon atoms, alkylaryl with 7-20 carbon atoms and substituted or unsubstituted aromatic hydrocarbon with 7-20 carbon atoms; r is⁴And R⁵The same or different, each is independently selected from one of straight-chain alkyl with the carbon atom number of 1-10, branched-chain alkyl with the carbon atom number of 3-10, naphthenic base with the carbon atom number of 3-10, alkylaryl with the carbon atom number of 7-20 and substituted or unsubstituted aromatic hydrocarbon with the carbon atom number of 7-20; r³And R⁶The two are the same or different and are respectively and independently selected from one of hydrogen and C1-10 linear alkyl or C3-10 branched alkyl;

in the formula (IV), R⁸Is H or C1-C6 alkyl;

The present inventors have found that when a catalyst obtained by prepolymerizing an olefin, which is obtained by combining the above-mentioned alkoxy magnesium carrier represented by the formula (I), the electron donor compound represented by the formula (II), the titanium compound represented by the formula (III), the polymer having a structural unit represented by the formula (IV), and the organoaluminum compound represented by the formula (V), is used for olefin polymerization, the catalyst has the characteristics of high activity and low fine powder content, and is less likely to undergo activity deterioration under storage conditions at normal temperature, has high isotacticity of the polymer, and has reduced fine powder content in the polymer powder and increased bulk density.

Preferably, in formula (I), 0.001. ltoreq. m.ltoreq.0.25;

in the formula (III), X is chlorine, bromine or iodine; r⁷Is a hydrocarbon group having 1 to 10 carbon atoms;

in the formula (IV), R⁸Is H, methyl, ethyl, n-butyl or n-hexyl;

In the present invention, the polymer of the structural unit of the olefin represented by the formula (IV) means a hydrocarbon homopolymer of the olefin corresponding to the structural unit or a copolymer of a mixture thereof in an arbitrary ratio.

The inventors have found that when the polymer is contained in an amount of 5 to 95 wt%, preferably 10 to 90 wt%, and more preferably 30 to 60 wt%, based on the total weight of the catalyst, the overall performance of the prepared catalyst is more excellent.

Preferably, the molar ratio of the titanium compound, the electron donor compound, the magnesium alkoxide support, calculated as titanium, to the organoaluminum compound, calculated as aluminum, is 1: (0.00005-20): (0.01-2): (0.01-100), preferably 1: (0.0002-1): (0.02-1): (0.05-10).

In the invention, preferably, the average particle diameter of the alkoxy magnesium carrier is 10-150 μm, and the particle size distribution index SPAN is less than 1.1; more preferably, the magnesium alkoxide support is spheroidal in appearance, has an average particle diameter D50 of 18 to 80 μm, and a particle size distribution index SPAN < 1.05.

Wherein SPAN ═ (D90-D10)/D50 formula (VI)

In the formula (VI), D90 represents a particle size value corresponding to a cumulative weight fraction of 90%, D10 represents a particle size value corresponding to a cumulative weight fraction of 10%, and D50 represents a particle size value corresponding to a cumulative weight fraction of 50%.

In the invention, the content control requirement of the magnesium ethoxide and the magnesium 2-ethyl hexanoate in the magnesium alkoxide carrier is that m is more than or equal to 0.001 and less than or equal to 0.5, the m value is too large, the reaction of carrier preparation becomes too weak, and the particle size is difficult to reach the proper range required by the invention; if the value of m is too small, the reaction for the preparation of the carrier is too vigorous to control, and the size distribution (SPAN value) of the carrier particles becomes broad, affecting the final catalyst activity and the ultrafine powder content and bulk density of the polymer to be prepared, preferably 0.001. ltoreq. m.ltoreq.0.25, more preferably 0.001. ltoreq. m.ltoreq.0.1

In the alkoxy magnesium shown in the formula (I), the formula (I) only shows the composition content of the ethoxy and 2-ethylhexyloxy, and does not represent the specific structure of the alkoxy magnesium. Specifically, for example, Mg (OEt) (OEHA) only represents that the mole ratio of ethoxy to 2-ethylhexyloxy in the magnesium alkoxide compound is 1, and the magnesium alkoxide compound can be a mixture of diethoxymagnesium and bis (2-ethylhexyloxy) magnesium with the mole ratio of 1, or an ethoxy (2-ethylhexyloxy) magnesium compound, or a mixture of the three; it can be a mixture of alkoxy magnesium compounds with various structures, wherein the total mole ratio of the ethoxy group to the 2-ethylhexyloxy group is 1.

In the present invention, the magnesium alkoxide carrier may contain a trace amount of magnesium halide (e.g., MgI)₂Or MgCl₂) Or an alcoholate thereof, but the purity should be higher than 90%, preferably higher than 95%, more preferably above 98% if calculated as the content of the magnesium compound of formula (I).

Preferably, the electron donor compound may be at least one of 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane, 9-bis (methoxymethyl) fluorene, 2-isobutyl-2-isopropyl-1, 3-dimethoxypropane, 2-dicyclopentanyl dimethoxypropane, 2-diphenyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-dimethoxypropane, more preferably 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane and/or 9, 9-bis (methoxymethyl) fluorene.

Preferably, the titanium compound may be at least one of tetraalkoxytitanium, titanium tetrahalide, trihaloalkoxytitanium, dihalodialkoxytitanium and monohalotrialkoxytitanium;

preferably, the titanium tetraalkoxide may be at least one of titanium tetramethoxide, titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-isopropoxide, titanium tetra-n-butoxide, titanium tetra-isobutoxide, titanium tetracyclohexyloxide, and titanium tetraphenoxide;

the titanium tetrahalide may be at least one of titanium tetrachloride, titanium tetrabromide or titanium tetraiodide, and is more preferably titanium tetrachloride;

the trihaloalkoxy titanium can be at least one of trichloromethoxy titanium, trichloroethoxy titanium, trichloropropoxy titanium, trichloron-butoxy titanium and tribromoethoxy titanium;

the dihalo dialkoxy titanium can be at least one of dichlorodimethoxytitanium, dichlorodiethoxy titanium, dichlorodi-n-propoxytitanium, dichlorodiisopropoxy titanium and dibromodiethoxy titanium;

the monohalotrialkoxy group can be at least one of titanium monochlorotrimethoxy titanium, chlorotriethoxytitanium, chlorotris-n-propoxy titanium or chlorotriisopropoxytitanium.

Preferably, the organoaluminium compound comprises a trialkylaluminium compound and/or an alkylaluminium halide,

preferably, the trialkylaluminum compound comprises triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum; the alkylaluminum halide includes diethylaluminum monochloride or ethylaluminum dichloride.

In the present invention, the catalyst preferably has a particle size distribution index SPAN of < 0.75, more preferably 0.58 to 0.66. Controlling the particle size distribution of the catalyst can further improve the overall activity of the catalyst.

In a second aspect, the present invention provides a method for preparing the catalyst of the present invention, which comprises the steps of:

TiX_n(OR⁷)_4-nformula (III)

CH₂＝CHR⁸Formula (IV')

AlR⁹ _nY_3-nFormula (V)

in the formula (II), R¹And R²The same or different, each independently selected from one of linear alkyl with 1-12 carbon atoms, branched alkyl with 3-12 carbon atoms, cycloalkyl with 3-10 carbon atoms, alkylaryl with 7-20 carbon atoms and substituted or unsubstituted aromatic hydrocarbon with 7-20 carbon atoms；R⁴And R⁵The same or different, each is independently selected from one of straight-chain alkyl with the carbon atom number of 1-10, branched-chain alkyl with the carbon atom number of 3-10, naphthenic base with the carbon atom number of 3-10, alkylaryl with the carbon atom number of 7-20 and substituted or unsubstituted aromatic hydrocarbon with the carbon atom number of 7-20; r³And R⁶The two are the same or different and are respectively and independently selected from one of hydrogen and C1-10 linear alkyl or C3-10 branched alkyl;

in the formula (IV'), R⁸Is H or C1-C6 alkyl;

In the invention, in the step 1), the reaction temperature can be 30-90 ℃, and the reaction time can be 2-30 h.

Preferably, in the step 1), the halogenating agent is a halogen element and/or a halogen compound;

preferably, the halogenating agent is at least one of iodine, bromine, chlorine, magnesium chloride, magnesium bromide, magnesium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, mercuric chloride, mercuric bromide, mercuric iodide, ethoxymagnesium iodide, methoxymagnesium iodide, isopropylmagnesium iodide, hydrogen chloride and chloroacetyl chloride; more preferably, the halogenating agent may be a combination of iodine and magnesium chloride.

Preferably, the mass ratio of the metallic magnesium to the ethanol and 2-ethylhexanol may be 1: (4-50), preferably 1: (6-25);

preferably, the ethanol is present in an amount of 70 to 99 wt%, based on the total weight of ethanol and 2-ethylhexanol;

preferably, the molar ratio of the metallic magnesium to the halogen atoms in the halogenating agent may be 1: (0.0002-0.2), more preferably 1: (0.001-0.08);

preferably, in the halogenating agent, the weight ratio of halogen to halogen compound may be 1: (0.02-20), more preferably 1: (0.1-10);

in the present invention, the water content of the alcohol to be used is not particularly limited, and in order to obtain a magnesium alkoxide carrier having more excellent performance, it is required that the water content is as small as possible, and the water content in the alcohol is generally controlled to 1000ppm or less, preferably 200ppm or less.

In the present invention, the magnesium used is metallic magnesium, and when the reactivity is good, the magnesium may be in any shape, and may be in the form of particles, ribbons, powders, or the like. In order to facilitate the production of magnesium alkoxide having an average particle size within a suitable range and excellent particle morphology, the magnesium metal is preferably spherical particles having an average particle size of 10 to 360 μm, more preferably 50 to 300. mu.m. The surface of the magnesium metal is not particularly limited, but the total amount of active magnesium is preferably > 95%, more preferably > 98%, because the formation of a coating such as hydroxide on the surface of the magnesium metal slows down the reaction by reducing the total amount of active magnesium.

The inert gas atmosphere in the present invention is preferably a nitrogen atmosphere or an argon atmosphere.

According to the preparation of the alkoxy magnesium carrier, an inert organic solvent can be selectively used in the preparation process. In the present invention, the inert solvent may be at least one selected from the group consisting of C6-C10 alkanes and aromatics, and preferably at least one selected from the group consisting of hexane, heptane, octane, decane, benzene, toluene, xylene and derivatives thereof.

According to the preparation of the alkoxy magnesium carrier, the method for adding the halogenating agent is not particularly limited, and the alkoxy magnesium carrier can be added by dissolving in alcohol, or can be directly added to the metal magnesium and the alcohol in a solid or liquid form, or can be added by dropping the halogenating agent alcohol solution in the process of heating the metal magnesium and the alcohol solution, so as to carry out the reaction for preparing the carrier.

According to the preparation of the alkoxy magnesium carrier, the metal magnesium, the alcohol, the halogenating agent and the inert solvent are added, and the reactants can be initially added at one time or can be added in portions. The divided charging of the raw materials prevents instantaneous generation of a large amount of hydrogen and prevents the generation of droplets of the alcohol or the halogenating agent due to the instantaneous generation of a large amount of hydrogen, and such a charging method is preferable from the viewpoint of safety and uniformity of reaction. The number of divisions can be determined according to the scale of the reactor and the amount of each material used.

According to the preparation of the alkoxy magnesium carrier, the reaction temperature can be 30-90 ℃, preferably 30-80 ℃, and more preferably 50-75 ℃. The reaction time may be 2 to 30 hours, preferably 5 to 20 hours, more preferably 5 to 12 hours. In actual practice, the end of the reaction can be judged by observing the cessation of the discharge of hydrogen produced by the reaction.

According to the invention, after the reaction is completed, the resulting final product magnesium alkoxide support may be stored dry or suspended in an inert diluent used in the preparation of the solid component of the catalyst in the next step.

In the invention, in the step 2), the contact reaction temperature can be-40 ℃ to 200 ℃, and the reaction time can be 1min to 20 h; preferably, the reaction temperature can be between-20 ℃ and 150 ℃, and the reaction time can be between 5min and 8 h.

Preferably, in the step 2), the molar ratio of the titanium compound, the electron donor compound and the magnesium alkoxide support is 1: (0.00005-20): (0.01-2), preferably 1: (0.0002-1): (0.02-1).

According to the preparation of the solid catalyst component of the present invention, the inert diluent is preferably toluene and the inert solvent washing agent is preferably hexane.

According to the preparation of the solid catalyst component according to the invention, the inert diluent may be used in a molar ratio with respect to the magnesium of the magnesium alkoxide compound of (0.5 to 100): 1; preferably (1-50): 1.

the method for the washing is not particularly limited, and the method of decantation, filtration, etc. is preferable for the preparation of the catalyst solid component according to the present invention. The amount of the inert solvent to be used, the washing time and the number of washing times are not particularly limited, and the amount of the inert solvent to be used is usually 1 to 1000 mol, preferably 10 to 500 mol, based on 1mol of the magnesium compound, and the washing time is usually 1 to 24 hours, preferably 6 to 10 hours. In addition, from the viewpoint of washing uniformity and washing efficiency, it is preferable to carry out stirring during the washing operation.

The solid catalyst component, the alkoxy magnesium compound, the electron donor compound and the titanium compound can be contacted and reacted in any way to prepare the solid catalyst component. For example, it can be prepared by the following method:

the method comprises the following steps:

1: preparing alkoxy magnesium carrier, internal electron donor and inert diluent into suspension, then reacting with the mixture formed by titanium compound and inert diluent, and filtering; 2. adding a mixture of a titanium compound and an inert diluent into the obtained solid matter for continuous reaction, and filtering; 3. repeating the reaction of the step 2 for 2-4 times; 3. washing the solid with inert solvent to obtain the catalyst solid component.

The second method comprises the following steps:

1: preparing an alkoxy magnesium carrier, a part of internal electron donor and an inert diluent into a suspension, then reacting with a mixture formed by a titanium compound and the inert diluent, and filtering; 2. adding titanium compound, inert diluent and the rest of the mixture formed by internal electron donor into the obtained solid matter, continuously reacting, and filtering; 3. continuously adding a mixture of a titanium compound and an inert diluent into the obtained solid for continuous reaction, and filtering; 4. repeating the reaction of the step 3 for 2-4 times; 5. washing the solid with inert solvent to obtain the catalyst solid component.

The third method comprises the following steps:

1. preparing an alkoxy magnesium carrier and an inert diluent into a suspension, then reacting the suspension with a mixture formed by a titanium compound and the inert diluent, adding an electron donor compound, continuing to react, and filtering; 2. adding a mixture formed by a titanium compound and an inert diluent into the obtained solid to continuously react, and filtering; 3. repeating the reaction of the step 2 for 2-4 times; 4. washing the solid with inert solvent to obtain the catalyst solid component.

The method four comprises the following steps:

1. preparing an alkoxy magnesium carrier, a part of internal electron donor and an inert diluent into a suspension, then reacting with a mixture formed by a titanium compound and the inert diluent, adding the rest of the electron donor compound, continuing to react, and filtering; 2. adding a mixture formed by a titanium compound and an inert diluent into the obtained solid to continuously react, and filtering; 3. repeating the reaction of the step 2 for 2-4 times; 4. washing the solid with inert solvent to obtain the catalyst solid component.

In the present invention, in step 3), the first treatment time may be 0.01 to 300min, preferably 0.5 to 250min, and more preferably 30 to 180min, and the treatment temperature is arbitrary, preferably not higher than 50 ℃, more preferably-20 ℃ to 30 ℃, and further preferably 10 to 30 ℃.

Preferably, in the first treatment, the molar ratio of the solid component of the catalyst, calculated as titanium, to the organoaluminium compound, calculated as aluminium, is 1: (0.01-100), more preferably 1: (0.05-10), more preferably 1: (0.1-5).

Preferably, in the second treatment, the speed of feeding the olefin is preferably relatively slow in feeding speed and polymerization speed, and the feeding speed of the olefin is controlled to be 0.01-10g/g solid catalyst component.

The time for passing the olefin may be determined by the content of the olefin polymer produced in the step in the final catalyst, and is preferably from 0.1 to 50 hours, more preferably from 0.5 to 25 hours, and further preferably from 2 to 10 hours, so that the content of the olefin polymer produced in the step in the final catalyst is from 5% by weight to 95% by weight, preferably from 10% by weight to 90% by weight, and further preferably from 30% by weight to 60% by weight.

In the second treatment, the treatment temperature of the olefin means a temperature of the suspension at the time of introducing the olefin, preferably from-20 ℃ to-50 ℃, more preferably from-20 ℃ to-40 ℃, and still more preferably from 5 ℃ to 30 ℃.

In the second treatment, hydrogen may be simultaneously introduced, and the partial pressure ratio of hydrogen to olefin may be (0.01 to 100): 1, preferably (0.1-50): 1, more preferably (0.1 to 10): 1, more preferably (0.1 to 3): 1.

preferably, the alkane in step 3) can be an aliphatic alkane containing 5 to 10 carbon atoms, more preferably n-pentane, isopentane, n-hexane, n-heptane or n-octane, and still more preferably n-hexane and/or n-heptane.

Preferably, the solvent used for the washing in step 4) may be an alkane, an aromatic hydrocarbon or a mixture thereof in any proportion, which is liquid at room temperature. The aromatic hydrocarbon comprises benzene, toluene, xylene, ethylbenzene, propylbenzene or trimethylbenzene, and toluene and/or xylene are preferred. The alkane solvent is aliphatic alkane containing 5-10 carbon atoms, including n-pentane, isopentane, n-hexane, n-heptane or n-octane, preferably n-hexane and/or n-heptane. The aromatic hydrocarbon and the alkane may be used alone or in combination. The solvent used for washing is preferably n-hexane and/or n-heptane. The temperature of washing is optional and preferably does not exceed the boiling point of the solvent used. The amount of the washing solvent to be used is preferably not less than 2 times the volume of the catalyst component based on the complete immersion of the catalyst component.

In step 4), the drying is not particularly limited, and for example, the solution obtained by filtration may be placed in an oven at a certain temperature, and the drying temperature may be set according to the solvent selected.

The third aspect of the present invention provides a catalyst composition for olefin polymerization, which is characterized in that the catalyst composition comprises a catalyst active component, an external electron donor compound and/or an external electron donor compound, wherein the catalyst active component is the catalyst according to the present invention or the catalyst prepared by the method according to the present invention.

In the present invention, the external organoaluminum compound includes a trialkylaluminum compound and/or an alkylaluminum halide, preferably, the trialkylaluminum compound may be at least one of triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, and tri-n-octylaluminum, and the alkylaluminum halide may be at least one of diethylaluminum monohydrochloride, diisobutylaluminum monohydrochloride, diethylaluminum monochloride, diisobutylaluminum dichloride, and more preferably, triethylaluminum and triisobutylaluminum.

The amount of the external organoaluminum compound can be an amount conventionally used in the art. Typically, the molar ratio of aluminum in the exo-organoaluminum compound to titanium in the catalyst active component is (5-5000): 1; preferably (20-1000): 1; more preferably (50-500): 1.

in the present invention, the external electron donor compound is conventionally selected in the art, and is not particularly limited. The external electron donor compound may be an organosilicon compound represented by formula (VI),

R¹⁰ _mR¹¹ _nSi(OR¹²)_4-m-nformula (VI)

Wherein R is¹⁰And R¹¹The functional groups are the same or different and are respectively and independently selected from one of the following functional groups: halogen, hydrogen atom, alkyl group having 1 to 20 carbon atoms, cycloalkyl group having 3 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms or haloalkyl group having 1 to 20 carbon atoms; r¹²One of the following functional groups: an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms or a haloalkyl group having 1 to 20 carbon atoms; m and n are each an integer of 0 to 3, and m + n<4。

Preferably, the organosilicon compound of the formula (VI) is selected from at least one of the following compounds: trimethylmethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isopropylisobutyldimethoxysilane, di-t-butyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylethyldimethoxysilane, t-butylpropyldimethoxysilane, t-butylisopropyldimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyl-t-butyldimethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentylethyldimethoxysilane, dicyclopentyldimethoxysilane, cyclopentylcyclohexyldimethoxysilane, bis (2-methylcyclopentyl) dimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isopropyldimethoxysilane, isopropylmethyldimethoxysilane, di-t-butyldimethoxysilane, cyclohexyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyldimethoxysilane, bis (2-methylcyclopentyl) dimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, pentyltrimethoxysilane, isopentyltrimethoxysilane, cyclopentyltrimethoxysilane, cyclohexyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane or tetrabutoxysilane;

more preferably, the organosilicon compound of formula (VI) is selected from at least one of the following compounds: dicyclopentyldimethoxyalkane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane or tetraethoxysilane.

The catalyst composition for olefin polymerization according to the third aspect of the present invention is not particularly limited in the amount of the external organoaluminum compound used. In a preferred case, the molar ratio of aluminum in the external electron donor organoaluminum compound to the external electron donor compound represented by formula (VI) is (0.1-500): 1, preferably (1-300): 1, more preferably (3-100): 1.

In the present invention, the catalyst or catalyst component can be used for the polymerization of olefins of the general formula CH₂＝CHR¹³Wherein R is¹³Can be H or C1-C12 alkyl. Linear olefins such as: ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-limonene, 1-decene; branched alkenes such as: 3-methyl-1-buteneAnd 4-methyl-1-pentene; dienes such as: butadiene, vinylcyclopentene, and vinylcyclohexene. These olefins may be used alone or in mixtures of more, preferably the catalyst component is used in the polymerization of ethylene and/or propylene.

The catalyst or catalyst component comprising the olefin polymer of the present invention can be used in the olefin polymerization processes known at present, including slurry, gas phase, bulk, and the polymerization conditions can be selected from those commonly used in the art. Thus, the polymerization is generally carried out at from 0 to 120 ℃ and preferably from 20 to 95 ℃. In particular, higher yields can be obtained with higher bulk densities in gas phase polymerization processes using such catalysts. Furthermore, sequentially different polymerization stages may be applied. In any of the polymerization processes used, the catalyst component may be precontacted with an exo-alkylaluminum compound prior to introducing the catalyst into the polymerization reactor. The pre-contact time is 0.1-30min, preferably 1-10 min; the pre-contact temperature is from-20 ℃ to 80 ℃, preferably from 0 to 50 ℃. The precontacting step may be carried out without olefin addition.

The invention has the technical effects that:

1. the invention provides a method for coating olefin polymer with a certain molecular weight outside catalyst particles, which utilizes the toughness of the polymer to improve the structural strength of the catalyst. At the same time, the prepolymerization consumes a part of the initial activity of the original catalyst to be exhibited in the polymerization under controlled conditions, thereby allowing the subsequent polymerization reaction to be stabilized.

2. When the catalyst component containing the olefin polymer is used for catalyzing olefin polymerization, the catalyst component has the characteristics of high isotacticity, good hydrogen regulation performance and high bulk density, and can reduce the fine powder content of the polymer. The initial polymerization activity is reduced, while the overall polymerization activity is significantly improved. Meanwhile, the catalyst component can be stored for a long time at normal temperature without activity degradation.

3. The catalyst containing the olefin polymer provided by the invention can increase the strength and uniformity of particles, avoid the aggregation and agglomeration of catalyst components, and is beneficial to the exertion and improvement of the overall activity of the catalyst; meanwhile, the regular and unbroken particles are suitable for synthesizing ethylene-propylene random copolymer and alloy polymer in a reaction kettle with high rubber content. Therefore, the catalyst containing the olefin polymer has better popularization and application prospects in industrial implementation.

The present invention will be described in detail below by way of examples.

The relevant data in the invention and its examples were obtained as follows:

determination of the polymer content in the catalyst:

accurately weigh about 1 gram (m)₁) Soaking the catalyst in 50ml of absolute ethyl alcohol solution, carrying out ultrasonic oscillation treatment for 60 minutes, filtering, washing for 3 times by using 50ml of absolute ethyl alcohol, and drying in vacuum to obtain solid powder (m)₂) From this, the content of polymer is calculated: m is₂/m₁×100％。

The titanium atom content in the titanium-containing catalyst is tested by adopting a 722N visible spectrophotometer purchased from Shanghai Cyanine science and technology instruments, Inc.;

the particle size and particle size distribution of the alkoxy magnesium carrier and the catalyst are measured by a Malvern Mastersizer TM2000 laser diffraction method, and n-hexane is used as a dispersing agent (wherein SPAN is (D90-D10)/D50);

in the formula, D90 represents a particle size value corresponding to a cumulative weight fraction of 90%, D10 represents a particle size value corresponding to a cumulative weight fraction of 10%, and D50 represents a particle size value corresponding to a cumulative weight fraction of 50%;

determination of the m value in the magnesium alkoxide support: 0.1 g of an alkoxy magnesium carrier was added with 10ml of a hydrochloric acid aqueous solution having a concentration of 1.2mol/L, and decomposed by shaking for 24 hours, and ethanol and 2-ethylhexanol were measured by a gas chromatograph (available from Allen analytical instruments, Ltd., model number GC-7960), and then the value of m was calculated according to the following formula:

wherein, w₁Is the mass of 2-ethylhexanol, w₂Is the mass of ethanol.

The content of internal electron donor in the Ziegler-Natta catalyst is determined by using Waters 600E liquid chromatography or gas chromatography.

The isotacticity of the polymer was determined as described in GB/T2412.

The melt index of the polymer was determined according to ASTM D1238 at 230 ℃ under a load of 2.16 kg.

The fines content of the polymer was determined according to ASTM E1187, below a 80 mesh screen (corresponding to a particle size of less than 180 μm), and is defined as fines.

The bulk density of the polymer was determined according to GB/T1636-2008.

Preparation of solid catalyst component:

the preparation of the solid catalyst component can be referred to CN103788237B, and specifically, the following method can be adopted:

after a 16L pressure-resistant reactor equipped with a stirrer was sufficiently replaced with nitrogen, 10L of ethanol, 300mL of 2-ethylhexanol, 11.2g of iodine, 8g of magnesium chloride and 640g of magnesium powder were charged into the reactor. The system is heated to 75 ℃ while stirring for reflux reaction until no hydrogen is discharged. The reaction was stopped, washed with 3L of ethanol, filtered and dried to obtain the magnesium alkoxide support. The obtained magnesium alkoxide support D50 was 30.2 μm, SPAN value 0.81, and m value 0.015.

650g of the above-mentioned magnesium alkoxide carrier and 3250ml of toluene were taken to prepare a suspension. Adding 2600ml of toluene and 3900ml of titanium tetrachloride into a 16L pressure-resistant reaction kettle repeatedly replaced by high-purity nitrogen, heating to 80 ℃, then adding the prepared suspension into the kettle, keeping the temperature for 1 hour, adding 130ml of 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, slowly heating to 110 ℃, keeping the temperature for 2 hours, and performing filter pressing to obtain a solid substance. The obtained solid was treated with a mixture of toluene 5070ml and titanium tetrachloride 3380ml at 110 ℃ for 1 hour with stirring, and thus treated 3 times. And (3) performing filter pressing, washing the obtained solid with hexane for 4 times (6000 mL each time), performing filter pressing, and drying to obtain the catalyst solid component A. The obtained catalyst component A contained 1.98 wt% of titanium atom and 10.6 wt% of 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane.

Preparation examples 1 to 3 are illustrative of the preparation of the magnesium alkoxide support.

Preparation example 1

After a 16L pressure-resistant reactor equipped with a stirrer was sufficiently replaced with nitrogen, 10L of ethanol, 300mL of 2-ethylhexanol, 11.2g of iodine, 8g of magnesium chloride, and 640g of magnesium powder were added to the reactor. And (3) heating the system to 75 ℃ while stirring for reflux reaction, and stopping the reaction when no hydrogen is discharged from the system after the reaction is carried out for about 5 hours. Washing with 3L ethanol, filtering, and drying to obtain alkoxy magnesium carrier A1. The obtained magnesium alkoxide support D50 was 30.2 μm, SPAN value 0.81, and m value 0.015.

Preparation example 2

After a 16L pressure-resistant reactor equipped with a stirrer was sufficiently replaced with nitrogen, 10L of ethanol, 2500mL of 2-ethylhexanol, 5g of iodine, 40g of magnesium chloride and 400g of magnesium powder were charged into the reactor. And (3) heating the system to 62 ℃ while stirring, carrying out reflux reaction, and stopping the reaction when no hydrogen is discharged from the system after about 8 hours of reaction. Washing with 3L ethanol, filtering, and drying to obtain alkoxy magnesium carrier A2. The obtained alkoxy magnesium carrier D50 ═ 65.9 μm, SPAN value 0.65, m value 0.19.

Preparation example 3

After a 16L pressure-resistant reactor equipped with a stirrer was sufficiently replaced with nitrogen, 10L of ethanol, 3300mL of 2-ethylhexanol, 15.6g of iodine, 4.3g of magnesium chloride and 1100g of magnesium powder were charged into the reactor. And (3) heating the system to 50 ℃ while stirring, carrying out reflux reaction, and stopping the reaction when no hydrogen is discharged from the system after the reaction is carried out for about 12 hours. Washing with 3L ethanol, filtering, and drying to obtain alkoxy magnesium carrier A3. The obtained magnesium alkoxide support D50 was 19.2 μm, SPAN value 1.01, and m value 0.01.

Preparation examples 4 to 6 are for illustrating the preparation of the solid component of the catalyst.

Preparation example 4

A suspension was prepared from the magnesium alkoxide support A1650 g and 3250ml of toluene. Adding 2600ml of toluene and 3900ml of titanium tetrachloride into a 16L pressure-resistant reaction kettle repeatedly replaced by high-purity nitrogen, heating to 80 ℃, then adding the prepared suspension into the kettle, keeping the temperature for 1h, adding 130ml of 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, slowly heating to 110 ℃, keeping the temperature for 2h, and performing filter pressing to obtain a solid. The obtained solid was treated with a mixture of toluene 5070ml and titanium tetrachloride 3380ml at 110 ℃ for 1 hour with stirring, and thus treated 3 times. And (4) performing filter pressing, washing the obtained solid with hexane for 4 times, and each time washing the solid with 6000mL, performing filter pressing, and drying to obtain a catalyst solid component B1. The titanium atom content of the obtained catalyst component B1 was 1.98% by weight, and the 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane content was 10.6% by weight.

Preparation example 5

The same as in production example 4 except that 130ml of 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane in production example 4 was replaced with 130g of 9, 9-bis (methoxymethyl) fluorene, to obtain a catalyst solid component B2. The titanium atom content of the obtained catalyst component B2 was 4.63 wt%, and the 9, 9-bis (methoxymethyl) fluorene content was 12.5 wt%.

Preparation example 6

The same as in production example 4 except that the magnesium alkoxide support A1 in production example 4 was replaced with A3 to obtain a catalyst solid component B3. The obtained catalyst component B3 contained 3.65 wt% of titanium atom and 11.6 wt% of 2-isopropyl-2-isopentyl-1, 3-dimethoxypropane.

Example 1

1. Preparation of the catalyst

To a 500mL glass vessel fully purged with nitrogen at a temperature of 10 ℃ was added 300mL of n-hexane, followed by 17g of catalyst solid component B1. While maintaining a constant internal temperature, 0.4mL of triisobutylaluminum was dissolved in 99.6mL of an n-hexane solution, and then slowly added to the reactor and treated for 100 min. The suspension of the solid component of the catalyst treated with triisobutylaluminum was then washed 3 times with n-hexane. Ethylene was then fed in at the same temperature and at a rate of 2.5g/h, and when the theoretical conversion value corresponding to 1g of olefin polymer per gram of catalyst had been reached (about 7h), the feeding was stopped and the polymerization was stopped. After 3 n-hexane washes at10 ℃, the resulting olefin polymer-containing catalyst Cat1 was dried and analyzed. The polymer content of Cat1 was 50.5 wt%, the titanium content was 0.99 wt%, and the particle size distribution index SPAN was 0.59.

2. Polymerisation

A5 liter autoclave equipped with a catalyst feeder, propylene and hydrogen feed lines was fully replaced with vapor phase propylene. Feeding catalyst into the reactor at room temperature5mL of a hexane solution of triethylaluminum (concentration of triethylaluminum: 0.5mol/L), 1mL of a hexane solution of Cyclohexylmethyldimethoxysilane (CHMMS) (concentration of CHMMS: 0.1mol/L), 10mL of anhydrous hexane, and 30mg of Cat1 prepared above were added, mixed for 2min (pre-complexation), and then the autoclave was charged₂)]2.4L of liquid propylene was added under a pressure of 0.9 MPa; the temperature was raised to 70 ℃ within 20min with stirring. After polymerization reaction is carried out for 1h at 70 ℃, the reaction kettle is cooled and the stirring is stopped, the unpolymerized propylene monomer is removed, and the polymer is obtained by collection.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat1 were as shown in Table 1.

Example 2

1. Preparation of the catalyst

To a 500mL glass kettle sufficiently purged with nitrogen at a temperature of 30 ℃ was added 300mL of n-heptane, followed by 17g of catalyst solid component B1. While maintaining a constant internal temperature, 10.1mL of triisobutylaluminum was dissolved in 89.9mL of an n-hexane solution, then slowly added to the reactor and treated for 180 min. The suspension of the solid component of the catalyst treated with triisobutylaluminum was then washed 3 times with n-hexane. Ethylene was then fed in at the same temperature and at a rate of 5g/h, and when the theoretical conversion value corresponding to 1.2g of olefin polymer per gram of catalyst had been reached (about 4h), the admission was stopped and the polymerization was stopped. After 3 n-hexane washes at 30 ℃, the resulting olefin polymer-containing catalyst Cat2 was dried and analyzed. The polymer content of the catalyst Cat2 was 55.5 wt%, the titanium content was 0.89 wt%, and the particle size distribution index SPAN was 0.66.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat2 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat2 were as shown in Table 1.

Example 3

1. Preparation of the catalyst

To a 500mL glass vessel fully purged with nitrogen at a temperature of 20 ℃ was added 300mL of n-hexane, followed by 17g of catalyst solid component B1. While maintaining a constant internal temperature, 4.0mL of triisobutylaluminum was dissolved in 96.0mL of an n-hexane solution, then slowly added to the reactor and treated for 30 min. The suspension of the solid component of the catalyst treated with triisobutylaluminum was then washed 3 times with n-hexane. Ethylene was then fed in at 0.8g/h at the same temperature, and when the theoretical conversion of 0.8g of olefin polymer per gram of catalyst had been deemed to have been reached (about 17h), the feed was stopped and the polymerization was stopped. After 3 n-hexane washes at 20 ℃, the resulting olefin polymer-containing catalyst Cat2 was dried and analyzed. The polymer content of Cat2 was 44.4 wt%, the titanium content was 1.09 wt%, and the particle size distribution index SPAN was 0.61.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat3 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat3 were as shown in Table 1.

Example 4

1. Preparation of the catalyst

The procedure of example 1 was followed except that: ethylene was fed in at a rate of 2.5g/h, and when the theoretical conversion value of 1.9g of olefin polymer per g of catalyst considered had been reached (about 13h), the admission was stopped and the polymerization was stopped. The catalyst Cat4 was prepared, and analyzed to obtain catalyst Cat4 having a polymer content of 65.1 wt%, a titanium content of 0.69 wt%, and a particle size distribution index SPAN of 0.71.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat4 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat4 were as shown in Table 1.

Example 5

1. Preparation of the catalyst

The procedure of example 1 was followed except that: ethylene was fed in at a rate of 2.5g/h, and when the theoretical conversion value of 0.25g of olefin polymer per gram of catalyst (ca. 2h) was deemed to have been reached, the feed was stopped and the polymerization was stopped. The catalyst Cat4 was prepared, and analyzed to obtain catalyst Cat4 having a polymer content of 19.9 wt%, a titanium content of 1.57 wt%, and a particle size distribution index SPAN of 0.72.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat5 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat5 were as shown in Table 1.

Example 6

1. Preparation of the catalyst

The procedure of example 1 was followed except that: ethylene was fed in at a rate of 2.5g/h, and when the theoretical conversion value of 3g of olefin polymer per gram of catalyst had been reached (about 20h), the feed was stopped and the polymerization was stopped. The catalyst Cat6 was prepared, and analyzed to obtain catalyst Cat6 having a polymer content of 74.6 wt%, a titanium content of 0.49 wt%, and a particle size distribution index SPAN of 0.75.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat6 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of catalyst Cat6 are shown in Table 1.

Example 7

1. Preparation of the catalyst

The procedure of example 1 was followed except that: 0.1mL of triisobutylaluminum was dissolved in 99.9mL of n-hexane solution and then slowly added to the reactor. The catalyst Cat7 was prepared, and analyzed to obtain catalyst Cat7 having a polymer content of 53.1 wt%, a titanium content of 0.94 wt%, and a particle size distribution index SPAN of 0.69.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat7 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat7 were as shown in Table 1.

Example 8

1. Preparation of the catalyst

The procedure of example 1 was followed except that: 16mL of triisobutylaluminum was dissolved in 84mL of n-hexane solution and then slowly added to the reactor. The catalyst Cat8 was prepared, and analyzed to obtain catalyst Cat8 having a polymer content of 47.4 wt%, a titanium content of 0.99 wt%, and a particle size distribution index SPAN of 0.74.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat8 was used instead of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat8 were as shown in Table 1.

Example 9

1. Preparation of the catalyst

To a 500mL glass kettle sufficiently purged with nitrogen was added 300mL of n-hexane at10 ℃ followed by addition of 17g of catalyst solid component B1. While maintaining a constant internal temperature, 0.4mL of triisobutylaluminum was dissolved in 99.6mL of an n-hexane solution, and then slowly added to the reactor and treated for 20 min. The suspension of the solid component of the catalyst treated with triisobutylaluminum was then washed 3 times with n-hexane. Then, at the same temperature, an ethylene/hydrogen mixed gas (partial pressure ratio hydrogen: ethylene: 0.8: 1) was introduced and polymerization was carried out under a steady-state pot pressure of 0.2MPa, and when the reaction was considered to have reached the theoretical conversion of 1.3g of the olefin polymer per gram of the catalyst (about 1.5 hours), the gas introduction was stopped and the polymerization was stopped. After 3 n-hexane washes at10 ℃, the resulting olefin polymer-containing catalyst Cat9 was dried and analyzed. The polymer content of the catalyst Cat9 was 57.6 wt%, the titanium content was 0.81 wt%, and the particle size distribution index SPAN was 0.62, as determined by analysis.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat9 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of catalyst Cat9 are shown in Table 1.

Example 10

1. Preparation of the catalyst

The catalyst Cat1 in example 1 was used and left at room temperature for 100 days, and this was designated as catalyst Cat 10. The polymer content of the catalyst Cat10 was 50.2 wt%, the titanium content was 0.97 wt%, and the particle size distribution index SPAN was 0.63, as determined by analysis.

2. Polymerisation

The polymerization process of example 1 was followed, except that: catalyst Cat10 was used in place of Cat 1.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of the catalyst Cat10 were as shown in Table 1.

Comparative example 1

A5 liter autoclave equipped with a catalyst feeder, propylene and hydrogen feed lines was fully replaced with vapor phase propylene. 5mL of a hexane solution of triethylaluminum (concentration of triethylaluminum: 0.5mol/L), 1mL of a hexane solution of cyclohexylmethyldimethoxysilane (CHMMS: 0.1mol/L), 10mL of anhydrous hexane and 15mg of B1(DCat1) and particle size distribution index SPAN of 0.86 were fed to the catalyst feeder at room temperature, mixed for 2min (pre-complexation), and then fed to the autoclave, which was closed, and the hydrogen partial pressure [ p (H) was respectively applied₂)]2.4L of liquid propylene was added under a pressure of 0.9 MPa; the temperature was raised to 70 ℃ within 20min with stirring. After polymerization reaction is carried out for 1h at 70 ℃, the reaction kettle is cooled and the stirring is stopped, the unpolymerized propylene monomer is removed, and the polymer is obtained by collection.

The polymerization activity, polymer Melt Index (MI), polymer isotacticity (II), polymer Bulk Density (BD) and micropowder content of catalyst B1 were as shown in Table 1.

Comparative example 2

Will be connected with a catalyst feeder, propylene and hydrogenThe 5 l autoclave of the feed line was fully replaced with vapor phase propylene. 5mL of a hexane solution of triethylaluminum (concentration of triethylaluminum: 0.5mol/L), 1mL of a hexane solution of cyclohexylmethyldimethoxysilane (CHMMS: 0.1mol/L), 10mL of anhydrous hexane and 15mg of B1(DCat1) and particle size distribution index SPAN of 0.88 were fed to the catalyst feeder at room temperature, mixed for 2min (pre-complexation), and then fed into the autoclave, which was closed, and the hydrogen partial pressure [ p (H) was respectively applied₂)]2.4L of liquid propylene was added under a pressure of 0.9 MPa; stirring at room temperature for 10min (corresponding to prepolymerization); the temperature was raised to 70 ℃ within 20min with stirring. After polymerization reaction is carried out for 1h at 70 ℃, the reaction kettle is cooled and the stirring is stopped, the non-polymerized propylene monomer is removed, and the polymer is collected.

TABLE 1

As can be seen from Table 1, the catalyst of the present invention has uniform particle size distribution (small SPAN value), and when it is used for propylene gas phase polymerization, it has the characteristics of high aggregation activity, high isotacticity and high bulk density, and at the same time, it can reduce the fine powder content of the polymer.

As can be seen from FIGS. 1 and 2, when the catalyst composition of the present invention is used for the gas phase polymerization of propylene, the obtained polypropylene powder is more uniform, and therefore, the polypropylene powder is not easy to agglomerate during the polymerization process, thereby improving the polymerization activity of the catalyst.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A catalyst for olefin polymerization comprises a catalyst precursor and a polymer of a structural unit shown as a formula (IV), wherein the catalyst precursor contains an alkoxy magnesium carrier shown as a formula (I), an electron donor compound shown as a formula (II), a titanium compound shown as a formula (III) and an organic aluminum compound shown as a formula (V), and the polymer of the structural unit shown as the formula (IV) coats the catalyst precursor;

Mg(OEt)_2-m(OEHA)_mformula (I)

Formula (II)

TiX_n(OR⁷)_4-nFormula (III)

－CH₂CHR⁸-formula (IV)

AlR⁹ _nY_3-nFormula (V)

in the formula (IV), R⁸Is H or C1-C6 alkyl;

in the formula (V), R⁹Is hydrogen or a hydrocarbon group having 1 to 20 carbon atoms; y is halogen, n is an integer of 1 to 3;

in the catalyst, the content of the polymer is 5-95 wt% based on the total weight of the catalyst;

the preparation method of the catalyst comprises the following steps:

2) in the presence of an inert diluent, carrying out contact reaction on the alkoxy magnesium carrier, the electron donor compound and the titanium compound, washing by an inert solvent and drying to prepare a catalyst solid component;

4) washing, filtering and drying the product obtained in the step 3) by using alkane and/or aromatic hydrocarbon to obtain a catalyst;

CH₂＝CHR⁸formula (IV')

in the formula (IV'), R⁸Is H or C1-C6 alkyl;

wherein, in the step 3), the adding speed of the olefin in the second treatment is 0.01-10g/g of the solid catalyst component.

2. The catalyst according to claim 1, wherein in formula (I), 0.001. ltoreq. m.ltoreq.0.25;

in the formula (II), R³、R⁴、R⁵And R⁶One of the radicalsOr a plurality of the components are arbitrarily connected to form a ring;

in the formula (III), X is chlorine, bromine or iodine; r is⁷Is a hydrocarbon group with 1-10 carbon atoms;

in the formula (IV), R⁸Is H, methyl, ethyl, n-butyl or n-hexyl;

3. The catalyst of claim 1 wherein the polymer is present in an amount of from 10 wt% to 90 wt%, based on the total weight of the catalyst.

4. The catalyst of claim 3, wherein the molar ratio of the titanium compound, the electron donor compound, the magnesium alkoxide support, and the organoaluminum compound, based on titanium and aluminum, respectively, is 1: (0.00005-20): (0.01-2): (0.01-100).

5. The catalyst of claim 4, wherein the molar ratio of the titanium compound, the electron donor compound, the magnesium alkoxide support, and the organoaluminum compound, based on titanium and aluminum, respectively, is 1: (0.0002-1): (0.02-1): (0.05-10).

6. The catalyst according to claim 1, wherein the magnesium alkoxide support has an average particle size of 10 to 150 μm and a particle size distribution index SPAN < 1.1.

7. The catalyst according to claim 1, characterized in that the magnesium alkoxide support has an average particle size of 15-100 μm and a particle size distribution index SPAN < 1.05.

8. The catalyst of claim 1, wherein the electron donor compound comprises at least one of 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 9-bis (methoxymethyl) fluorene, 2-isobutyl-2-isopropyl-1, 3-dimethoxypropane, 2-dicyclopentanyl dimethoxypropane, 2-diphenyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-dimethoxypropane.

9. The catalyst of claim 8, wherein the electron donor compound is 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane and/or 9, 9-bis (methoxymethyl) fluorene.

10. The catalyst of claim 1 wherein the titanium compound comprises at least one of a titanium tetraalkoxide, a titanium tetrahalide, a titanium trihalidealkoxide, a titanium dihalodialkoxide, and a titanium monohalotrialkoxyate.

11. The catalyst of claim 10, wherein the titanium tetraalkoxide is at least one of titanium tetramethoxide, titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-isopropoxide, titanium tetra-n-butoxide, titanium tetra-isobutoxide, titanium tetra-cyclo-hexyloxide, and titanium tetraphenoxide;

the titanium tetrahalide is at least one of titanium tetrachloride, titanium tetrabromide or titanium tetraiodide;

the trihaloalkoxy titanium is at least one of trichloromethoxy titanium, trichloroethoxy titanium, trichloropropoxy titanium, trichloron-butoxy titanium and tribromoethoxy titanium;

the dihalo-dialkoxy titanium is at least one of dichloro dimethoxy titanium, dichloro diethoxy titanium, dichloro di-n-propoxy titanium, dichloro diisopropoxy titanium and dibromo diethoxy titanium;

the monohalotrialkoxy is at least one of titanium monochlorotrimethoxy titanium, chlorotriethoxytitanium, chlorotris-n-propoxy titanium or chlorotriisopropoxytitanium.

12. The catalyst of claim 11 wherein the titanium tetrahalide is titanium tetrachloride.

13. The catalyst according to claim 1, characterized in that the organoaluminium compound comprises a trialkylaluminium compound and/or an alkylaluminium halide.

14. The catalyst according to claim 13, characterized in that the trialkylaluminum compound comprises triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum; the alkylaluminum halide includes diethylaluminum monochloride or ethylaluminum dichloride.

15. The catalyst of any one of claims 1 to 14, wherein the catalyst has a particle size distribution index SPAN < 0.75.

16. The catalyst of claim 15 wherein the catalyst has a particle size distribution index of from 0.58 to 0.66.

17. A method for preparing the catalyst of any one of claims 1 to 16, comprising the steps of:

formula (II)

TiX_n(OR⁷)_4-nFormula (III)

CH₂＝CHR⁸Formula (IV')

AlR⁹ _nY_3-nFormula (V)

in the formula (IV'), R⁸Is H or C1-C6 alkyl;

wherein, in the step 3), the adding speed of the olefin is 0.01-10g/g of the solid catalyst component h in the second treatment.

18. The method of claim 17, wherein formula (la) isIn (II), R³、R⁴、R⁵And R⁶One or more of the groups are optionally linked to form a ring;

in the formula (IV'), the olefin is ethylene, propylene, 1-butene, 1-hexene or 1-octene;

19. The method as claimed in claim 17 or 18, wherein in step 1), the reaction temperature is 30-90 ℃ and the reaction time is 2-30 h.

20. The method of claim 19, wherein in step 1), the halogenating agent is elemental halogen and/or a halogen compound.

21. The method of claim 20, wherein in step 1), the halogenating agent is at least one of iodine, bromine, chlorine, magnesium chloride, magnesium bromide, magnesium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, mercuric chloride, mercuric bromide, mercuric iodide, ethoxymagnesium iodide, methoxymagnesium iodide, isopropylmagnesium iodide, hydrogen chloride, and chloroacetyl chloride.

22. The method according to claim 21, wherein in step 1), the mass ratio of the metallic magnesium to the ethanol and 2-ethylhexanol is 1: (4-50);

the content of the ethanol is 70-99 wt% based on the total weight of the ethanol and the 2-ethylhexanol;

the molar ratio of the metal magnesium to the halogen atoms in the halogenating agent is 1: (0.0002-0.2);

in the halogenating agent, the weight ratio of halogen to halogen compound is 1: (0.02-20).

23. The method according to claim 22, wherein in step 1), the mass ratio of the metallic magnesium to the ethanol and 2-ethylhexanol is 1: (6-25);

the molar ratio of the metal magnesium to the halogen atoms in the halogenating agent is 1: (0.001-0.08);

in the halogenating agent, the weight ratio of halogen to halogen compound is 1; (0.1-10).

24. The method as claimed in claim 17 or 18, wherein in the step 2), the contact reaction temperature is-40 ℃ to 200 ℃ and the reaction time is 1min to 20 h.

25. The method as claimed in claim 24, wherein in the step 2), the contact reaction temperature is-20 ℃ to 150 ℃ and the reaction time is 5min to 8 h.

26. The method according to claim 17 or 18, wherein in step 3), the first processing time is 0.01-300 min;

in the second treatment, the treatment time is 0.1-50h, and the treatment temperature is-20 ℃ to 50 ℃.

27. The process according to claim 17 or 18, wherein in step 3), hydrogen is simultaneously fed in while feeding the olefin, and the partial pressure ratio of hydrogen to olefin is (0.01-100): 1.

28. the process of claim 27 wherein in step 3) hydrogen is passed simultaneously with the olefin, the partial pressure ratio of hydrogen to olefin being (0.1 to 50): 1.

29. a catalyst composition for olefin polymerization, characterized in that the catalyst composition comprises a catalyst active component, an external organoaluminum compound and/or an external electron donor compound, and the catalyst active component is the catalyst according to any one of claims 1 to 16 or the catalyst prepared by the process according to any one of claims 17 to 28.

30. Use of the catalyst composition of claim 29 in the polymerization of olefins.