阅读说明：本技术 类球形超大孔介孔材料和聚烯烃催化剂及其制备方法以及烯烃聚合方法 (Spheroidal ultra-macroporous mesoporous material, polyolefin catalyst, preparation method of polyolefin catalyst and olefin polymerization method ) 是由 亢宇 吕新平 刘东兵 郭子芳 刘红梅 李秉毅 王如恩 于 2020-06-05 设计创作，主要内容包括：本发明涉及均相催化烯烃聚合反应技术领域,公开了一种类球形超大孔介孔材料和聚烯烃催化剂及其制备方法以及烯烃聚合方法。所述类球形超大孔材料具有二维六方有序孔道结构；所述介孔材料的平均孔径为10nm～15nm,比表面积为300m～(2)/g～400m～(2)/g,平均粒径为1μm～3μm；以所述介孔材料的总质量为基准,所述介孔材料中水的质量含量<0.1ppm；所述介孔材料中氧气的质量含量<0.1ppm。将所述介孔材料用于制备的聚烯烃催化剂在用于烯烃聚合反应时,具有较高的催化效率,并且能够得到分子量分布较窄、熔融指数较优的聚烯烃产品。(The invention relates to the technical field of homogeneous catalysis olefin polymerization reaction, and discloses a sphere-like super-macroporous mesoporous material, a polyolefin catalyst, a preparation method of the sphere-like super-macroporous mesoporous material and the polyolefin catalyst, and an olefin polymerization method. The spheroidal super-macroporous material has a two-dimensional hexagonal ordered pore channel structure; the average pore diameter of the mesoporous material is 10 nm-15 nm, and the specific surface area is 300m 2 /g～400m 2 (ii)/g, the average particle diameter is 1 to 3 μm; based on the total mass of the mesoporous material, the mass content of water in the mesoporous material<0.1 ppm; the mass content of oxygen in the mesoporous material<0.1 ppm. Polyolefin catalyst prepared by using mesoporous material in olefin polymerization reactionThe method has high catalytic efficiency, and can obtain polyolefin products with narrow molecular weight distribution and excellent melt index.)

1. A mesoporous material is characterized in that the mesoporous material has a two-dimensional hexagonal ordered pore structure; the average pore diameter of the mesoporous material is 10 nm-15 nm, and the specific surface area is 300m²/g～400m²(ii)/g, the average particle diameter is 1 to 3 μm;

the mass content of water in the mesoporous material is less than 0.1ppm by taking the total mass of the mesoporous material as a reference; the mass content of oxygen in the mesoporous material is less than 0.1 ppm.

2. The mesoporous material according to claim 1, wherein the mesoporous material has a water contact angle of 101 ° to 130 °, preferably 115 ° to 125 °, and more preferably 118 ° to 124 °.

3. The mesoporous material according to claim 1 or2, wherein the mesoporous material is obtained by treatment with a chlorosilane;

preferably, the chlorosilane is selected from at least one of dichlorodimethoxysilane, monochlorotrimethoxysilane, dichlorodiethoxysilane and monochlorotriethoxysilane.

4. The mesoporous material according to any of claims 1 to 3, wherein the crushing strength of the mesoporous material is 0.001N/cm to 0.6N/cm, preferably 0.01N/cm to 0.55N/cm, and more preferably 0.1N/cm to 0.45N/cm.

5. The mesoporous material according to any of claims 1 to 4, wherein the mesoporous material has an average pore diameter of 11nm to 13nm and a specific surface area of 310m²/g～380m²(iii) a mean particle diameter of 1.1 to 2.9 μm/g.

6. The mesoporous material according to any of claims 1-5, wherein the mesoporous material has a pore volume of 1-2 mL/g, preferably 1.5-1.9 mL/g.

7. The mesoporous material according to any of claims 1 to 6, wherein the particle size distribution of the mesoporous material is 0.01 to 3, preferably 0.1 to 2.8.

8. A preparation method of a mesoporous material is characterized by comprising the following steps:

(1) in the presence of a template agent and water, mixing and contacting a silicon source, an acid agent, ammonium fluoride and heptane, and sequentially crystallizing, filtering and drying a mixture obtained after mixing and contacting to obtain mesoporous material raw powder;

(2) and sequentially carrying out demoulding agent treatment, primary thermal activation treatment and secondary thermal activation treatment on the mesoporous material raw powder.

9. The production method according to claim 8, wherein in the step (2), the conditions of the primary thermal activation treatment include: in an inert atmosphere, the treatment temperature is 250-900 ℃, preferably 250-700 ℃, and more preferably 250-650 ℃; the treatment time is 1-48 h, preferably 4-48 h, more preferably 6-24 h;

preferably, the conditions of the secondary thermal activation treatment include: in an inert atmosphere, the treatment temperature is 250-900 ℃, preferably 250-700 ℃, and more preferably 250-650 ℃; the treatment time is 1-48 h, preferably 4-48 h, more preferably 6-24 h;

more preferably, the treatment conditions of the primary thermal activation treatment are the same as those of the secondary thermal activation treatment.

10. The production method according to claim 8 or 9, wherein in the step (1), the mixing and contacting are performed in a manner including: stirring for more than 4min at the temperature of 25-60 ℃, and then standing for more than 1 h;

preferably, the molar ratio of the templating agent, the silicon source, the acid agent, the ammonium fluoride, and the heptane is 1: 2-500: 100-2000: 0.7 to 200: 20-1650;

preferably, the templating agent is a triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene EO₂₀PO₇₀EO₂₀；

Preferably, the crystallization conditions include: the crystallization temperature is 90-180 ℃, and the crystallization time is 10-40 h.

11. The production method according to any one of claims 8 to 10, wherein the method further comprises: mixing and stirring a product obtained by thermal activation treatment and chlorosilane-containing silane;

preferably, the chlorosilane is selected from at least one of dichlorodimethoxysilane, monochlorotrimethoxysilane, dichlorodiethoxysilane and monochlorotriethoxysilane.

12. The production method according to any one of claims 8 to 11, wherein the method does not include a grinding step after the heat-activation treatment.

13. A mesoporous material prepared by the preparation method of any one of claims 8 to 12.

14. A polyolefin catalyst, characterized in that the polyolefin catalyst comprises a carrier and a magnesium component and/or a titanium component supported on the carrier;

wherein the carrier is the mesoporous material of any one of claims 1 to 7 and 13.

15. The polyolefin catalyst according to claim 14, wherein the support is present in an amount of from 20 to 90 wt. -%, preferably from 30 to 70 wt. -%, based on the total weight of the polyolefin catalyst; the content of the magnesium component is 1 to 50 weight percent, preferably 1 to 30 weight percent based on magnesium element; the content of the titanium component is 1 to 50 weight percent, preferably 1 to 30 weight percent based on the titanium element.

16. The polyolefin catalyst according to claim 14 or 15, wherein the polyolefin catalyst has a pore volume of 0.5 to 1mL/g and a specific surface area of 120m²/g～300m²The most probable pore diameter is 7 nm-12 nm, the average particle diameter is 3 μm-25 μm, and the particle diameter distribution value is 0.85-0.95.

17. A process for preparing the polyolefin catalyst of any of claims 14-16, comprising:

(i) impregnating the mesoporous material (ia) according to any one of claims 1 to 7 and 13 with a solution containing a magnesium component and then with a solution containing a titanium component under an inert atmosphere, (ib) impregnating with a solution containing a titanium component and then with a solution containing a magnesium component, or (ic) co-impregnating with a solution containing both a titanium component and a magnesium component to obtain a slurry;

(ii) (ii) spray drying the slurry from step (i).

18. An olefin polymerization process, the process comprising: a) polymerizing an olefin monomer under polymerization conditions in the presence of the polyolefin catalyst of any of claims 13-15 and a co-catalyst to provide a polyolefin; and b) recovering the polyolefin.

Technical Field

The invention relates to the technical field of homogeneous catalysis olefin polymerization reaction, in particular to a sphere-like super-macroporous mesoporous material and a preparation method thereof, a polyolefin catalyst containing the sphere-like super-macroporous mesoporous material, and an olefin polymerization method adopting the polyolefin catalyst.

Background

The preparation technology of the carrier is one of the core technologies of polyolefin catalyst production, and in spite of the preparation technologies of catalysts of different processes of polyethylene at present, the used carrier is mainly silica gel, common silica gel cannot be used as a polyolefin catalyst carrier, the technical requirement of the carrier silica gel for the polyolefin catalyst is high, the development difficulty is large, and the carrier silica gel technology is monopolized by individual foreign companies for a long time. The american cabot company TS610 silica gel accounts for almost a full share of the global polyethylene catalyst support silica gel market. The carrier silica gel for polyolefin catalyst has high technical requirement and high development difficulty due to the requirements of certain bulk density, specific surface area, pore structure (pore volume, pore diameter, pore distribution), abrasion strength and the like, and the technology is mastered only by American cabot company at abroad at present.

WO2020083386A1 discloses a polyolefin catalyst component containing a mesoporous material, and a preparation method and application thereof. The mesoporous material is subjected to thermal activation treatment and is selected from the following groups: a) a mesoporous material having a two-dimensional hexagonal pore structure; b) the eggshell-shaped mesoporous material has a two-dimensional hexagonal pore channel structure; c) spherical mesoporous silica with a cubic core structure and d) hexagonal mesoporous material with a cubic cage-like pore structure. The mesoporous material is used for a polyolefin catalyst and used for olefin polymerization reaction, has high catalytic efficiency, and can obtain a polyolefin product with narrow molecular weight distribution and excellent melt index. However, the catalyst efficiency of polyolefin catalysts still needs to be further improved.

Disclosure of Invention

The invention aims to provide a novel sphere-like super-macroporous mesoporous material and a preparation method thereof, a polyolefin catalyst containing the sphere-like super-macroporous mesoporous material and an olefin polymerization method adopting the polyolefin catalyst, and the catalyst prepared by using the sphere-like super-macroporous mesoporous material has obviously higher catalytic efficiency.

In order to achieve the above object, a first aspect of the present invention provides a mesoporous material having a two-dimensional hexagonal ordered pore structure; the average pore diameter of the mesoporous material is 10 nm-15 nm, and the specific surface area is 300m²/g～400m²(ii)/g, the average particle diameter is 1 to 3 μm;

the mass content of water in the mesoporous material is less than 0.1ppm by taking the total mass of the mesoporous material as a reference; the mass content of oxygen in the mesoporous material is less than 0.1 ppm.

In a second aspect, the present invention provides a method for preparing a mesoporous material, comprising the following steps:

(1) in the presence of a template agent and water, mixing and contacting a silicon source, an acid agent, ammonium fluoride and heptane, and sequentially crystallizing, filtering and drying a mixture obtained after mixing and contacting to obtain raw powder of the sphere-like mesoporous material;

(2) and sequentially carrying out demoulding agent treatment, primary thermal activation treatment and secondary thermal activation treatment on the raw powder of the spheroidal mesoporous material.

The third aspect of the present invention provides a mesoporous material prepared by the above preparation method.

The fourth aspect of the present invention provides a polyolefin catalyst characterized in that the polyolefin catalyst comprises a carrier and a magnesium component and/or a titanium component supported on the carrier;

wherein the carrier is the mesoporous material.

The fifth aspect of the present invention provides a method for preparing the above polyolefin catalyst, characterized in that the method comprises:

(i) subjecting the above mesoporous material (ia) to an impregnation treatment with a solution containing a magnesium component and then to an impregnation treatment with a solution containing a titanium component, (ib) to an impregnation treatment with a solution containing a titanium component and then to an impregnation treatment with a solution containing a magnesium component, or (ic) to a co-impregnation treatment with a solution containing both a titanium component and a magnesium component, under an inert atmosphere, to obtain a slurry;

(ii) (ii) spray drying the slurry from step (i).

In a sixth aspect, the present invention provides an olefin polymerization process comprising: a) polymerizing an olefin monomer under polymerization conditions in the presence of the above polyolefin catalyst and cocatalyst to provide a polyolefin; and b) recovering the polyolefin.

By the technical scheme, the sphere-like super-macroporous mesoporous material and the preparation method thereof, the polyolefin catalyst containing the sphere-like super-macroporous mesoporous material and the polyolefin catalyst thereof, and the olefin polymerization method adopting the polyolefin catalyst have the following beneficial effects:

the mesoporous material has a two-dimensional hexagonal ordered pore structure and a spheroidal morphology, and has obvious advantages in the aspects of reducing powder agglomeration, improving the flowability and the like due to the oversized and ordered pore structure, so that the spheroidal ordered mesoporous material is used as a carrier of a polyolefin catalyst, the advantages of microspheres and the ordered mesoporous material can be combined, the characteristics of high specific surface area, large pore volume, large pore diameter and narrow distribution of the ordered mesoporous material can be retained, the agglomeration of the ordered mesoporous material can be reduced, and the flowability of the ordered mesoporous material is improved; the polyolefin catalyst particles obtained by the method have the advantages of stable structure, high strength, difficult breakage, small particle size, uniform particle size distribution and narrow particle size distribution curve, effectively controls the moisture content of the particles, prevents carrier particles from deliquescing and bonding, avoids the catalyst from agglomerating in the use process, improves the fluidity of the catalyst, and brings convenience for the storage, transportation, post-processing and application of the obtained polyolefin catalyst.

Meanwhile, the mesoporous material has large average pore diameter, so that the active components of the polyethylene catalyst can enter rich inner pores of the mesoporous material, rather than being loaded on the outer surface of the mesoporous material, and particularly, the hexagonal through pores and the spheroidal structure of the mesoporous material are more favorable for entering the active components of the catalyst, and the obtained catalyst has excellent catalytic efficiency.

Furthermore, the sphere-like mesoporous material prepared by the preparation method can obtain the sphere-like mesoporous material with small particle size, narrow particle size distribution, moderate specific surface area, large pore volume, large pore diameter and narrow distribution without grinding, has good fluidity, saves grinding procedures and can improve the catalytic efficiency of the catalyst.

Furthermore, when the polyolefin catalyst is prepared by the method, the spherical-like polyolefin catalyst can be directly obtained in one step by adopting a spray drying technology, the operation is simple, the obtained slurry is more exquisite, and the loading capacity of the active component can be effectively improved, so that the obtained polyolefin catalyst has the advantages of stable particle structure, high strength, small particle size, uniform particle size distribution, narrow particle size distribution curve and excellent catalytic activity, is not easy to break, and can be used for olefin polymerization to obtain the obviously-improved conversion rate of reaction raw materials.

Further, when the polyolefin catalyst of the present invention is used in olefin polymerization, the molecular weight distribution and melt index of the polyolefin product can be further improved, and the polyolefin product is spherical and has uniform particle size.

Drawings

FIG. 1 is an XRD spectrum of the spheroidal super macroporous mesoporous material provided in example 1;

FIG. 2 is a SEM image of the spheroidal super-macroporous mesoporous material provided in example 1;

FIG. 3 is a SEM image of the mesoporous material provided in comparative example 6;

fig. 4 and 5 are SEM images of the mesoporous material provided in comparative example 6 in different visual field ranges after ball milling.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those 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 mesoporous material in a first aspect, wherein the mesoporous material has a two-dimensional hexagonal ordered pore structure; the average pore diameter of the mesoporous material is 10 nm-15 nm, and the specific surface area is 300m²/g～400m²Per gram, the grain diameter is 1-3 mu m;

the mass content of water in the mesoporous material is less than 0.1ppm by taking the total mass of the mesoporous material as a reference; the mass content of oxygen in the mesoporous material is less than 0.1 ppm.

According to the International Union of Pure and Applied Chemistry (IUPAC) regulations, mesoporous materials refer to a class of porous materials with pore sizes between 2nm and 50 nm. In the present invention, the term "mesoporous material" is used as defined above.

In the invention, the mesoporous material is mesoporous silica.

The two-dimensional hexagonal ordered pore structure is a term with definite meaning in the field of catalysts and catalyst carriers, and in the invention, the meaning of the two-dimensional hexagonal ordered pore structure is similar to the common meaning of the prior art, namely that the pore distribution is regular and ordered, and the pore shape is a hexagonal pore.

In the present invention, the mesoporous material has a structure similar to a sphere, the term used is also called a subsphaeroidal shape, and the term "similar-spherical mesoporous material" means that the particle morphology of the mesoporous material is close to a sphere, that is, the mesoporous material does not have a perfect appearance curve like a sphere, for example, a certain local position or a plurality of local positions do not have the requirement of a sphere, but have a substantially spherical appearance.

In the invention, the mesoporous material is a sphere-like super-macroporous mesoporous material. In the present invention, the term "ultra-macroporous mesoporous material" is used to mean a mesoporous material in which the average pore diameter of the mesoporous material is not less than 10nm and the number of pores having a pore diameter of not less than 10nm accounts for 50% or more of the total number of pores.

In the invention, the average particle size and the particle size distribution SPAN value of the mesoporous material are measured by a laser particle size distribution instrument, and the specific surface area, the pore volume and the pore diameter are measured by a nitrogen adsorption method. In this context, particle size refers to the particle size of the particulate material, which is expressed as the diameter of the spheres when the particulate material is spherical, as the side length of the cubes when the particulate material is cubic, and as the mesh size of a screen that is just capable of screening out the particulate material when the particulate material is irregularly shaped.

In the invention, the content of water in the mesoporous material is measured by a Karl Fischer moisture analyzer, and the content of oxygen in the mesoporous material is measured by a nitrogen-oxygen analyzer. In the invention, the water content and the oxygen content of the mesoporous material comprise the contents of water and oxygen in the inner pore channel of the mesoporous material and the outer surface of the mesoporous material. In the present invention, ppm means a ratio of the mass content of oxygen or water to the total mass of the mesoporous material.

The sphere-like super-macroporous mesoporous material has a special two-dimensional hexagonal ordered pore structure, the mesoporous pore structure is uniform in distribution, proper in pore size, small in particle size, low in moisture and oxygen content, good in mechanical strength and good in structural stability, and is particularly beneficial to good dispersion of magnesium and titanium active components on the surface of a carrier, so that the prepared polyolefin catalyst has the advantages of a supported catalyst, such as good metal active component dispersibility, high loading amount, few side reactions, simple post-treatment and the like, and has strong catalytic activity, the supported catalyst prepared by using the sphere-like super-macroporous mesoporous material carrier as the carrier is ensured to have better catalytic activity in olefin monomer polymerization, and the conversion rate of reaction raw materials is remarkably improved.

According to the invention, when the specific surface area of the sphere-like super-macroporous mesoporous material carrier is less than 300m²When the particle size is less than 1 mu m and/or the average pore diameter is 10nm per gram, the catalytic activity of a supported catalyst prepared by using the supported catalyst as a carrier is remarkably reduced; when the specific surface area of the sphere-like super-macroporous mesoporous material carrier is more than 400m²When the particle size is more than 3 mu m and/or the average pore diameter is more than 15nm, the supported catalyst prepared by using the supported catalyst as a carrier is easy to agglomerate in the olefin polymerization reaction process, thereby influencing the conversion rate of olefin monomers in the olefin polymerization reaction.

Further, when the structural parameters of the spheroidal ultra-macroporous mesoporous material with the two-dimensional hexagonal pore channel structure are controlled in the following ranges: the average pore diameter is 11nm to 13nm, and the specific surface area is 310m²/g～380m²When the average particle size is 1.1 to 2.9 mu m/g, the conversion rate of the reaction raw material in the olefin polymerization process can be further improved by using the supported catalyst prepared by using the supported catalyst as a carrier.

According to the invention, the content of water in the mesoporous material is controlled to be less than 0.1ppm, the content of oxygen is controlled to be less than 0.1ppm, a catalyst prepared by using the mesoporous material as a carrier is not easy to agglomerate in the olefin polymerization reaction process, and the obtained catalyst has excellent catalytic activity.

According to the present invention, the contact angle of the mesoporous material is 101 ° to 130 °, preferably 115 ° to 125 °, and more preferably 118 ° to 124 °. In the invention, when the contact angle of the mesoporous material is 101-130 degrees, the mesoporous material is used as a supported catalyst prepared from a carrier, which is particularly beneficial to the good dispersion of magnesium and titanium active components on the surface of the carrier, so that the prepared polyolefin catalyst has the advantages of the supported catalyst, such as good metal active component dispersibility, high loading amount, less side reactions, simple post-treatment and the like, and has stronger catalytic activity, and the supported catalyst prepared by using the spheroidal super-macroporous mesoporous material carrier as the carrier is ensured to have better catalytic activity when being used for olefin monomer polymerization. While the contact angle of the general mesoporous material in the prior art is far less than 100 ℃, for example, the contact angle of the commercial mesoporous material SBA-15 product is 20 degrees.

Furthermore, when the contact angle of the mesoporous material is 115 to 125 degrees, preferably 118 to 124 degrees, the catalyst prepared from the mesoporous material has more excellent technical effects.

In the invention, the contact angle of the mesoporous material is measured by RDAX.

According to the present invention, the mesoporous material is obtained by treating a thermally activated mesoporous material with chlorosilane.

Preferably, the chlorosilane is selected from at least one of dichlorodimethoxysilane, monochlorotrimethoxysilane, dichlorodiethoxysilane and monochlorotriethoxysilane.

In the present invention, the chlorosilane-containing treatment may be performed by stirring the thermally activated mesoporous material together with the chlorosilane in the presence or absence of other media such as an inert solvent, and the treatment temperature may be in the range of 20 to 150 ℃, preferably in the range of 30 to 120 ℃, and more preferably in the range of 40 to 100 ℃.

The dosage of the chlorosilane is 0.2 to 1.5 grams per gram of the mesoporous material subjected to thermal activation treatment.

The heat activation treatment will be explained below.

In a preferred embodiment of the present invention, the mesoporous material has a pore volume of 1mL/g to 2mL/g, and when the pore diameter satisfies the above range, the obtained supported catalyst is not easy to agglomerate during the olefin polymerization reaction, and has more excellent catalytic activity.

Furthermore, the pore volume of the mesoporous material is 1.5 mL/g-1.9 mL/g.

The crushing strength of the mesoporous material of the invention measured according to the GB3635-1983 standard method is 0.001N/cm-0.6N/cm, preferably 0.01N/cm-0.55N/cm, and more preferably 0.1N/cm-0.45N/cm.

In the invention, when the crushing strength of the mesoporous material meets the range, the catalyst particles prepared from the mesoporous material have stable structure and high strength and are not easy to crush.

In the invention, when the particle size distribution of the mesoporous material meets 0.01-3, the mesoporous material is used as a supported catalyst prepared from a carrier, the catalyst is not easy to agglomerate in the olefin polymerization reaction process, and the catalyst has higher catalytic activity. Furthermore, the particle size distribution of the mesoporous material is 0.1-2.8.

The second aspect of the present invention provides a method for preparing a sphere-like mesoporous material, which is characterized in that the method comprises the following steps:

(1) in the presence of a template agent and water, mixing and contacting a silicon source, an acid agent, ammonium fluoride and heptane, and sequentially crystallizing, filtering and drying a mixture obtained after mixing and contacting to obtain raw powder of the sphere-like mesoporous material;

(2) and sequentially carrying out demoulding agent treatment, primary thermal activation treatment and secondary thermal activation treatment on the raw powder of the spheroidal mesoporous material.

In the present invention, in the step (1), the mixing and contacting manner includes: stirring for more than 4min at the temperature of 25-60 ℃, and then standing for more than 1 h. In order to further facilitate uniform mixing between the substances, according to a preferred embodiment of the invention, the mixing contact is carried out under stirring conditions. Preferably, the manner of mixing contact comprises: stirring for 10-240 min at 25-60 ℃, and then standing for 4-24 h.

According to the invention, the molar ratio of the templating agent, the silicon source, the acid agent, the ammonium fluoride and the heptane is 1: 2-500: 100-2000: 0.7 to 200: 20 to 1650.

Still further, the templating agent, the silicon source, the acid agent, the ammonium fluoride, and the heptane are present in a molar ratio of 1: 10-250: 200-500: 1-180: 50-1450.

In the invention, the addition of ammonium fluoride and the mutual matching of heptane and secondary thermal activation treatment are more key factors for obtaining the spheroidal ultra-macroporous mesoporous material.

Preferably, the templating agent is a triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene EO₂₀PO₇₀EO₂₀. The template may be obtained commercially (e.g., from Aldrich under the trade name P123, formula EO)₂₀PO₇₀EO₂₀) It can also be prepared by various conventional methods. When the template agent is polyethylene glycol-polyglycerol-polyethylene glycol, the mole number of the template agent is calculated according to the average molecular weight of the polyethylene glycol-polyglycerol-polyethylene glycol.

According to the present invention, the crystallization conditions include: the crystallization temperature is 90-180 ℃, and the crystallization time is 10-40 h. Preferably, the crystallization temperature is 95-105 ℃, and the crystallization time is 20-36 h.

In the present invention, examples of the silicon source include, but are not limited to, ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate, and silica sol, and more preferably ethyl orthosilicate. The acid agent may be a substance capable of providing acidic conditions, which is conventional in the art, such as hydrochloric acid, sulfuric acid, and the like, preferably hydrochloric acid. In the present invention, the heptane is a straight-chain or branched alkane having 7 carbon atoms, and n-heptane is preferable.

In the present invention, the stripper plate agent treatment comprises: calcining the raw powder of the sphere-like mesoporous material at 300-600 ℃ for 8-20 h. The mass content of water in the mesoporous material is controlled below 100ppm and the mass content of oxygen is controlled below 100ppm through one-time thermal activation treatment.

In the invention, the thermal activation treatment is carried out in an inert atmosphere, and after the primary thermal activation treatment, the temperature is reduced to the ambient temperature (such as room temperature), and then the temperature is continuously increased to carry out the secondary thermal activation treatment.

In the invention, the secondary thermal activation treatment is adopted to control the water content of the mesoporous material to be less than 0.1ppm and the oxygen content to be less than 0.1 ppm. The catalyst prepared by using the catalyst as a carrier is not easy to agglomerate in the olefin polymerization reaction process, and the obtained catalyst has excellent catalytic activity.

According to the present invention, the conditions of the primary thermal activation treatment include: in an inert atmosphere, the treatment temperature is 250-900 ℃, preferably 250-700 ℃, and more preferably 250-650 ℃; the treatment time is 1 to 48 hours, preferably 4 to 48 hours, and more preferably 6 to 24 hours. In the present invention, unless otherwise specified, the treatment time means a time within the above treatment temperature range.

Preferably, the mode of one heat activation treatment comprises the following steps: in an inert atmosphere, the temperature is raised from the ambient temperature to 200-300 ℃ at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃, and kept for 1-10 hours, and then raised to 400-900 ℃, preferably 500-700 ℃, more preferably 550-650 ℃ at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃, and then kept for 2-10 hours.

According to the present invention, the conditions of the secondary thermal activation treatment include: in an inert atmosphere, the treatment temperature is 250-900 ℃, preferably 250-700 ℃, and more preferably 250-650 ℃; the treatment time is 1 to 48 hours, preferably 4 to 48 hours, and more preferably 6 to 24 hours. In the present invention, unless otherwise specified, the treatment time means a time within the above treatment temperature range.

Preferably, the mode of the secondary thermal activation treatment comprises: in an inert atmosphere, the temperature is raised from the ambient temperature to 200-300 ℃ at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃, and kept for 1-10 hours, and then raised to 400-900 ℃, preferably 500-700 ℃, more preferably 550-650 ℃ at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃, and then kept for 2-10 hours.

More preferably, the treatment conditions of the primary thermal activation treatment are the same as those of the secondary thermal activation treatment.

In a preferred embodiment of the present invention, the conditions of the thermal activation treatment include: raising the temperature from the ambient temperature to 200-300 ℃ at the speed of 0.5-10 ℃, preferably 0.5-1.5 ℃ per minute in nitrogen atmosphere, staying for 1-10 hours, raising the temperature to 400-900 ℃, preferably 500-700 ℃, more preferably 550-650 ℃ at the speed of 0.5-10 ℃, preferably 0.5-1.5 ℃ per minute, preserving the temperature for 2-10 hours, carrying out primary heat activation treatment, and then reducing the temperature to the ambient temperature (such as room temperature) for secondary heat activation treatment: in nitrogen atmosphere, raising the temperature from the ambient temperature to 200-300 ℃ at the speed of 0.5-10 ℃, preferably 0.5-1.5 ℃ per minute, staying for 1-10 hours, raising the temperature to 400-900 ℃, preferably 500-700 ℃, more preferably 550-650 ℃, keeping the temperature for 2-10 hours, and cooling to room temperature to obtain the spheroidal ultra-macroporous mesoporous material. And in the processes of primary thermal activation treatment and secondary thermal activation treatment, the nitrogen atmosphere is always kept introduced.

In the present invention, the filtering process may include: and after filtering, repeatedly washing with deionized water (the washing frequency can be 2-10), and then carrying out suction filtration.

In the present invention, the drying may be performed in a drying oven. The drying conditions may include: the temperature is 110-150 ℃ and the time is 3-6 h.

According to a preferred embodiment of the invention, the method further comprises: mixing and stirring the product obtained by the thermal activation treatment and the chlorosilane.

According to the invention, the product obtained by thermal activation treatment is mixed and stirred with chlorosilane, so that modification of the mesoporous material by chlorosilane is realized, and the prepared sphere-like super-macroporous mesoporous material has the characteristic of lipophilicity, thereby further ensuring that the mesoporous material is in a state of low moisture content and low oxygen content for a long time.

According to the invention, the chlorosilane means various substances containing carbon, chlorine and silicon, containing or not containing oxygen atoms and not containing hydrophilic groups such as hydroxyl, amino and carboxyl, and can contain one or more chlorine atoms and one or more silicon atoms, and when the chlorine atoms are multiple, the chlorine atoms can be positioned on the same silicon atom or different silicon atoms. The chlorine-containing silane is selected from at least one of dichlorodimethoxysilane, monochlorotrimethoxysilane, dichlorodiethoxysilane and monochlorotriethoxysilane.

In the invention, the mesoporous material obtained by the method has the characteristics of small and uniform particle size, so that the mesoporous material subjected to thermal activation treatment obtained by the method does not need to be subjected to a grinding step in the prior art. Therefore, the method of the invention not only can save the working procedures, but also can reduce the damage to the structure of the mesoporous material caused by grinding, reduce the loss of the mesoporous material and ensure the mechanical strength of the mesoporous material, and more importantly, in the prior art, the ball milling can directly damage even though the broken slag blocks the pore channel of the mesoporous material carrier, thereby reducing the activity of the catalyst.

In one embodiment of the present invention, the mesoporous material may be prepared by a method comprising the following steps:

step 1, triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene (EO)₂₀PO₇₀EO₂₀Abbreviated as P123) and ammonium fluoride (NH)₄F) Adding the mixture into a hydrochloric acid aqueous solution, wherein the molar feed ratio is that the triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene: ammonium fluoride (NH)₄F) The method comprises the following steps Hydrogen chloride ═ 1: 1-3: 100-2000, and stirring at 25-60 ℃ until the mixture is dissolved;

step 2, adding tetraethoxysilane and heptane into the solution obtained in the previous step, violently stirring for more than 10 minutes at the temperature of 25-60 ℃, and standing for more than 10 hours at the temperature of 25-60 ℃; the feed ratio of the massages is as follows: ethyl orthosilicate: 1-heptane: 20-500: 20 to 500 parts by weight;

step 3, placing the solution obtained in the step 3 in a closed reaction container, and crystallizing at the temperature of 90-180 ℃ for 10-40 h;

step 4, diluting the crystallized product with deionized water, filtering, washing and drying to obtain spherical-like super-macroporous mesoporous material raw powder;

step 5, calcining the obtained mesoporous material raw powder at 300-600 ℃ for 8-20 h, and removing the template agent;

step 6, heating the material without the template agent to 200-300 ℃ from the ambient temperature at the speed of 0.5-10 ℃, preferably 0.5-1.5 ℃ per minute under the condition of introducing nitrogen, staying for 1-10 hours, heating to 400-900 ℃, preferably 500-700 ℃, more preferably 550-650 ℃ at the speed of 0.5-10 ℃, preferably 0.5-1.5 ℃ per minute, and then preserving heat for 2-10 hours for primary heat activation treatment;

and 7, cooling the material subjected to the primary thermal activation treatment to room temperature, heating the material to 200-300 ℃ from the ambient temperature at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃ under the condition of introducing nitrogen, staying for 1-10 hours, heating the material to 400-900 ℃ at the speed of 0.5-10 ℃ per minute, preferably 0.5-1.5 ℃, preferably 500-700 ℃, more preferably 550-650 ℃ for 2-10 hours, and performing secondary thermal activation treatment to obtain the spheroidal ultra-macroporous mesoporous material.

The third aspect of the present invention provides a spheroidal mesoporous material prepared by the above preparation method.

In the invention, the spheroidal mesoporous material has a two-dimensional hexagonal ordered pore structure; the average pore diameter of the mesoporous material is 10 nm-15 nm, and the specific surface area is 300m²/g～400m²(ii)/g, the average particle diameter is 1 to 3 μm;

the mass content of water in the mesoporous material is less than 0.1ppm by taking the total mass of the mesoporous material as a reference; the mass content of oxygen in the mesoporous material is less than 0.1 ppm.

The fourth aspect of the present invention provides a polyolefin catalyst, wherein the polyolefin catalyst comprises a carrier and a magnesium component and/or a titanium component supported on the carrier;

wherein the carrier is the sphere-like mesoporous material.

The polyolefin catalyst comprises the sphere-like super-macroporous mesoporous material carrier. The sphere-like super-macroporous mesoporous material carrier has a special two-dimensional hexagonal structure, the mesoporous pore structure of the sphere-like super-macroporous mesoporous material carrier is uniform in distribution, proper in pore size, small in particle size, good in mechanical strength and good in structural stability, and is particularly beneficial to good dispersion of magnesium and titanium active components on the surface of the carrier, so that the prepared polyolefin catalyst has the advantages of a supported catalyst, such as good metal active component dispersibility, high loading capacity, few side reactions, simple post-treatment and the like, and has strong catalytic activity, the supported catalyst prepared by using the sphere-like super-macroporous material carrier as the carrier is ensured to have better catalytic activity in olefin monomer polymerization, and the conversion rate of reaction raw materials is remarkably improved.

According to the present invention, the content of the support is 20 to 90 wt%, preferably 30 to 70 wt%, based on the total weight of the polyolefin catalyst; the content of the magnesium component is 1 to 50 weight percent, preferably 1 to 30 weight percent based on magnesium element; the content of the titanium component is 1 to 50 weight percent, preferably 1 to 30 weight percent based on the titanium element.

According to the present invention, when the active metal component supported on the carrier in the polyolefin catalyst includes only the magnesium component, the content of the carrier may be 20 to 90% by weight, and the content of the magnesium component may be 1 to 50% by weight, preferably 1 to 30% by weight, and more preferably 1 to 20% by weight, based on the total weight of the polyolefin catalyst; when the active metal component supported on the carrier in the polyolefin catalyst includes only the titanium component, the content of the carrier may be 20 to 90% by weight, and the content of the titanium component may be 1 to 50% by weight, preferably 1 to 15% by weight, and more preferably 1 to 5% by weight, based on the total weight of the polyolefin catalyst.

Preferably, in the polyolefin catalyst, the molar ratio of the magnesium component (in terms of magnesium element) to the titanium component (in terms of titanium element) is 0.5 to 50: 1, preferably 5 to 18: 1.

according to the invention, the polyolefin catalyst has a pore volume of 0.5 to 1mL/g and a specific surface area of 120m²/g～300m²The most probable pore diameter is 7 nm-12 nm, the average particle diameter is 3 μm-25 μm, and the particle diameter distribution value is 0.85-0.95.

In the invention, the average particle size of the polyolefin catalyst is measured by a particle size distribution SPAN in a Malvern laser particle size analyzer, and the specific surface area, the pore volume, the average pore diameter and the most probable pore diameter are measured by nitrogen adsorption.

In one embodiment of the present invention, the polyolefin catalyst component comprises a spheroidal ultra-macroporous mesoporous material, magnesium, titanium, a halogen, and an electron donor. In the present invention, the halogen means at least one of fluorine, chlorine, bromine and iodine.

The fifth aspect of the present invention provides a method for preparing the above polyolefin catalyst, characterized in that the method comprises:

(i) subjecting the above-mentioned spheroidal mesoporous material (ia) to an impregnation treatment with a solution containing a magnesium component and then to an impregnation treatment with a solution containing a titanium component under an inert atmosphere, (ib) to an impregnation treatment with a solution containing a titanium component and then to an impregnation treatment with a solution containing a magnesium component, or (ic) to a co-impregnation treatment with a solution containing both a titanium component and a magnesium component, to obtain a slurry;

(ii) (ii) spray drying the slurry from step (i).

According to the present invention, the solution containing the magnesium component and/or the titanium component may be an organic solution containing a magnesium salt and/or a titanium salt, and the organic solvent in the organic solution may be an electron donor solvent, for example, the organic solvent may be selected from at least one of alkyl esters, aliphatic ethers, and cyclic ethers of aliphatic or aromatic carboxylic acids, preferably alkyl esters of saturated aliphatic carboxylic acids of C1 to C4, alkyl esters of aromatic carboxylic acids of C7 to C8, aliphatic ethers of C2 to C6, and cyclic ethers of C3 to C4; more preferably at least one of methyl formate, ethyl acetate, butyl acetate, diethyl ether, hexyl ether and Tetrahydrofuran (THF); further preferred is tetrahydrofuran.

According to the invention, the mesoporous material loaded with the magnesium component and/or the titanium component can adopt an impregnation mode, the magnesium component and/or the titanium component enter the pore channels of the mesoporous material by virtue of capillary pressure of the pore channel structure of the carrier, and the magnesium component and/or the titanium component can be adsorbed on the surface of the mesoporous material at the same time until the magnesium component and/or the titanium component reach adsorption equilibrium on the surface of the mesoporous material. When the mesoporous material supports the magnesium component and the titanium component, the impregnation treatment may be co-impregnation treatment or step-by-step impregnation treatment. In order to save the preparation cost and simplify the experimental process, the dipping treatment is preferably co-dipping treatment; further preferably, the conditions of the co-impregnation treatment include: the impregnation conditions may include: the dipping temperature is 25-100 ℃, and preferably 40-80 ℃; the dipping time is 0.1 to 5 hours, preferably 1 to 4 hours.

According to the present invention, the mesoporous material, the magnesium component and the titanium component are preferably used in such amounts that the mesoporous material is present in an amount of 20 to 90 wt%, preferably 30 to 70 wt%, based on the total weight of the polyolefin catalyst component, in the polyolefin catalyst component, the magnesium component is present in an amount of magnesium element, and the titanium component is present in an amount of 1 to 50 wt%, preferably 1 to 30 wt%, more preferably 10 to 30 wt%, based on titanium element.

In the present invention, when the mesoporous material is subjected to the impregnation treatment in the solution containing only the magnesium component, the mesoporous material and the magnesium component are preferably used in such amounts that the content of the mesoporous material in the prepared polyolefin catalyst component is 20 to 90 wt%, and the content of the magnesium component (in terms of magnesium element) is 1 to 50 wt%, preferably 1 to 30 wt%, and more preferably 1 to 20 wt%, based on the total weight of the polyolefin catalyst component.

In one embodiment of the present invention, in the prepared polyolefin catalyst component, the content of the mesoporous material is 20 to 90 wt% based on the total weight of the polyolefin catalyst component, the magnesium component is calculated by magnesium element, the titanium component is calculated by titanium element, and the sum of the contents of the magnesium component and the titanium component is 10 to 30 wt%.

Preferably, in step (i), the mesoporous material, the solution containing the magnesium component and/or the titanium component may be used in a weight ratio of 1: 50-150, preferably 1: 75-120.

Preferably, in the step (i), the magnesium component and the titanium component are used in amounts such that the molar ratio of the magnesium component in terms of magnesium element to the titanium component in terms of titanium element in the produced polyolefin catalyst component is 0.5 to 50: 1, preferably 5 to 18: 1.

in the present invention, the magnesium component may be of the general formula Mg (OR1)_mX_2-mWherein R1 is a hydrocarbon group having 2 to 20 carbon atoms, X is a halogen atom, and m is 0. ltoreq. m.ltoreq.2, and the magnesium component may be at least one of diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, dioctoxymagnesium, and magnesium dichloride, for example.

In the present invention, the titanium component may be of the general formula Ti (OR2)_nX_4-nWherein R2 is a hydrocarbon group having 2 to 20 carbon atoms, X is a halogen atom, 0. ltoreq. n.ltoreq.4, and/or titanium trichloride, and the titanium component may be at least one of tetraethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, titanium trichloride and titanium tetrachloride.

In the method of the present invention, a magnesium component precursor capable of being converted into the above-mentioned magnesium component during the preparation of the catalyst may be used in place of the magnesium component; the titanium component is titanium tetrachloride and/or titanium trichloride, more preferably titanium tetrachloride.

In the present invention, the concentrations of the magnesium component and the titanium component are not particularly limited and may be conventionally selected in the art, for example, the concentration of the magnesium component may be 0.1 to 1mol/L and the concentration of the titanium component may be 0.01 to 0.2 mol/L.

According to the present invention, the inert gas is a gas that does not react with the raw materials and the products during the impregnation treatment, and may be, for example, at least one of nitrogen gas or a group zero element gas in the periodic table, which is conventional in the art, and is preferably nitrogen gas. In the present invention, the impregnation conditions include: the dipping temperature is 25-100 ℃, and the dipping time is 0.1-5 h.

According to the present invention, the spray drying may be carried out according to a conventional method. May be at least one selected from the group consisting of a pressure spray drying method, a centrifugal spray drying method and a pneumatic spray drying method. According to a preferred embodiment of the present invention, the spray drying is an air-flow spray drying method. The spray drying may be carried out in an atomizer. The conditions of the spray drying may include: the process is carried out in the nitrogen protective atmosphere, the temperature of an air inlet is 100-150 ℃, the temperature of an air outlet is 100-120 ℃, and the flow rate of carrier gas is 10-50L/s. The above conditions impart a relatively high viscosity to the slurry to be sprayed, making it suitable for spray forming operations, and also impart good mechanical strength to the sprayed particles. Preferably, the spray drying condition is such that the average particle size of the prepared polyolefin catalyst is 3 to 25 μm and the particle size distribution value is 0.85 to 0.95.

According to a preferred embodiment of the present invention, said steps (i) - (ii) are carried out as follows: adding an electron donor solvent Tetrahydrofuran (THF) into a reactor with a stirrer in an inert atmosphere, controlling the temperature of the reactor to be 25-40 ℃, quickly adding magnesium chloride and titanium tetrachloride when stirring and starting, adjusting the temperature of the system to be 60-75 ℃, and reacting for 1-5 h at constant temperature until the magnesium chloride and the titanium tetrachloride are completely dissolved to obtain an organic solution containing magnesium dichloride and titanium tetrachloride. Mixing the organic solution containing magnesium dichloride and titanium tetrachloride with the spherical mesoporous material, controlling the proportion of the components to be 0.5-50 mol, preferably 1-10 mol, relative to 1mol of titanium element, magnesium element content, and electron donor solvent Tetrahydrofuran (THF) to be 0.5-200 mol, preferably 20-200 mol, controlling the temperature of a reactor to be 60-75 ℃, and stirring for reaction for 0.1-5 h to prepare the slurry to be sprayed with uniform concentration. The amount of the spheroidal mesoporous material added should be sufficient to form a slurry suitable for spray forming, and the sum of the contents of the magnesium chloride and the titanium tetrachloride in terms of magnesium element and titanium element is 1 to 50 wt%, preferably 1 to 30 wt%. The resulting slurry to be sprayed is then introduced into a spray dryer at N₂Under protection, the temperature of an air inlet of the spray dryer is controlled to be 100-150 ℃, the temperature of an air outlet is controlled to be 100-120 ℃, and the flow rate of carrier gas is controlled to be 10-50L/s, so that the sphere-like polyolefin catalyst with the average particle size of 3-25 mu m, preferably 3-20 mu m is obtainedAgent particles.

The polyolefin catalysts prepared by the above-described process have a spheroidal morphology and are therefore sometimes conveniently referred to as spheroidal catalyst components. The term "spheroidal catalyst component" as used herein means that the catalyst component has a morphology approaching a sphere. The catalyst of the invention has high magnesium component and titanium component loading capacity and reasonable pore channel structure. When the catalyst is used for olefin monomer polymerization, the polymerization activity is higher, and the obtained polymer has good particle form, narrow molecular weight distribution and excellent fluidity.

In the invention, when the catalyst is used for ethylene polymerization, the catalyst efficiency (gPE/gcat. h) is more than 25000, preferably 28000-29000. Whereas the catalytic efficiency of the prior art catalysts does not exceed 22000, usually not 20000.

In the polyolefin catalyst, the used carrier mesoporous material has an average pore diameter far larger than that of the conventional mesoporous material, so that the polyethylene catalyst can enter rich inner pore channels instead of being loaded on the outer surface in the loading process, and the hexagonal straight-through pore channels are also more favorable for entering the catalyst, so that the obtained catalyst has excellent catalytic efficiency.

In a sixth aspect, the present invention provides an olefin polymerization process comprising: a) polymerizing an olefin monomer under polymerization conditions in the presence of the above polyolefin catalyst and cocatalyst to provide a polyolefin; and b) recovering the polyolefin.

In the present invention, the term "polymerization" is used to include both homopolymerization and copolymerization. The term "polymer" as used herein includes homopolymers, copolymers and terpolymers.

The reaction of the polyolefin catalyst component used in the present invention for preparing polyolefin by polymerizing olefin monomers includes homopolymerization of ethylene or copolymerization of ethylene and other alpha-olefin, wherein the alpha-olefin may be at least one selected from propylene, 1-butene, 1-hexene, 1-octene, 1-pentene and 4-methyl-1-pentene.

According to the present invention, the reaction conditions of the polymerization reaction are not particularly limited, and may be those conventional in the art for olefin polymerization. For example, the reaction may be carried out under an inert atmosphere, and the conditions of the polymerization reaction may include: the temperature is 10-100 ℃, the time is 0.5-5 h, and the pressure is 0.1-2 MPa; preferably, the conditions of the polymerization reaction may include: the temperature is 20-95 ℃, the time is 1-4 h, and the pressure is 0.5-1.5 MPa; more preferably, the temperature is 70-85 ℃, the time is 1-2 h, and the pressure is 1-1.5 MPa.

The polyethylene obtained by the olefin polymerization method has good particle shape, excellent fluidity, larger melt index of polymer powder and narrow molecular weight distribution of the polymer powder. Preferably, the melt index MI2.16(g/10min) of the polyethylene powder is more than 1.6g/10min, and preferably 1.7g/10 min-3 g/10 min; the molecular weight distribution index (Mw/Mn) of the polyethylene powder is less than 3.5, and preferably 2.8-3.

The pressure referred to herein is gauge pressure.

In the present invention, the polymerization reaction may be carried out in the presence of a solvent, and the solvent used in the polymerization reaction is not particularly limited, and may be, for example, hexane.

In one embodiment of the present invention, the supported polyolefin catalyst component may be a supported polyethylene catalyst component, and the polymerization reaction is an ethylene polymerization reaction, and the ethylene polymerization method includes: polymerizing ethylene in the presence of a catalyst and a cocatalyst under ethylene polymerization conditions; preferably, the cocatalyst is an alkyl aluminum compound.

The cocatalyst which can be used in the process of the present invention may be any cocatalyst commonly used in the art. For example, the cocatalyst can be an alkyl aluminum compound represented by formula I:

AlR_nX_(3-n)formula I

In the formula I, R can be alkyl of C1-C5 respectively; x may each be one of halogen atoms, preferably a chlorine atom; n is 0, 1, 2 or 3.

Preferably, the alkyl group of C1 to C5 may be one or more of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, and neopentyl.

Specific examples of the alkyl aluminum compound include, but are not limited to: trimethylaluminum, dimethylaluminum chloride, triethylaluminum, diethylaluminum chloride, tri-n-propylaluminum, di-n-propylaluminum chloride, tri-n-butylaluminum, tri-sec-butylaluminum, tri-tert-butylaluminum, di-n-butylaluminum chloride and diisobutylaluminum chloride. Most preferably, the alkyl aluminium compound is triethyl aluminium.

The amount of the alkyl aluminum compound may also be selected as is conventional in the art. In general, the molar ratio of the catalyst component to the amount of alkylaluminum compound used may be 1: 20 to 300.

In the present invention, the olefin polymerization method may further comprise, after the polymerization reaction is completed, subjecting the final reaction mixture to suction filtration separation to obtain polyolefin particle powder.

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

In the following examples and comparative examples:

triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene P123, available from Aldrich, abbreviated as P123, and having a molecular formula of EO₂₀PO₇₀EO₂₀The substance having a registration number of 9003-11-6 in the American chemical Abstract, and an average molecular weight Mn of 5800; the other raw materials used in the examples and comparative examples are commercially available.

In the following examples and comparative examples, X-ray diffraction analysis was carried out on an X-ray diffractometer, model D8Advance, available from Bruker AXS, Germany; scanning electron microscopy analysis was performed on a scanning electron microscope, model XL-30, available from FEI, USA; pore structure parameter analysis was performed on an ASAP2020-M + C type adsorber, available from Micromeritics, USA, and BET method was used for the specific surface area and pore volume calculation of the sample; the particle size distribution SPAN values of the samples were carried out on a Malvern laser granulometer (Malvern, England); the rotary evaporator is produced by German IKA company, and the model is RV10 digital; the component loading of the polyolefin catalyst component was measured on a wavelength dispersive X-ray fluorescence spectrometer, model Axios-Advanced, available from Pasnake, Netherlands; spray drying was carried out on a spray dryer model B-290, commercially available from Buchi, Switzerland. The moisture content in the mesoporous material is measured by an MA-30 intelligent Karl Fischer moisture tester. The oxygen content ONH-3000 oxygen nitrogen hydrogen analyzer in the mesoporous material.

The molecular weight distribution index (Mw/Mn) of the polyolefin powder was measured by the method prescribed in ASTM D6474-99 using a gel permeation chromatograph model PL-GPC220 manufactured by Polymer Laboratories Ltd. in UK.

The melt index of polyolefins is determined using the method specified in ASTM D1238-99.

The average particle size of the particulate material was determined using a scanning electron microscope.

Example 1

This example illustrates the polyolefin catalyst component and the process for its preparation.

(I) Preparation of the support

(1) 2.4 g of P123 (substance having a mean molecular weight Mn of 5800, which is registered under the American chemical Abstract accession number 9003-11-6) and 0.028 g of ammonium fluoride are added to 80mL of a 1.75mol/L hydrochloric acid solution and stirred at 20 ℃ until P123 and ammonium fluoride are completely dissolved together;

(2) then 17mL of n-heptane and 5.5mL of ethyl orthosilicate are added into the solution, stirred vigorously for 4 minutes at 20 ℃ and then kept stand for 1 hour;

(3) transferring the obtained solution into a reaction kettle with a polytetrafluoroethylene lining, and crystallizing for 24 hours at 100 ℃;

(4) filtering, washing and drying to obtain a raw powder mesoporous material;

(5) calcining the mesoporous material in a muffle furnace at 500 ℃ for 24 hours, removing the template agent, and introducing nitrogen at a flow rate of 1.3m³Introducing nitrogen at a flow rate/s, heating to 250 ℃ from room temperature at a speed of 1 ℃ per minute, staying for 2 hours, heating to 550 ℃ at a speed of 1 ℃ per minute, then preserving heat for 8 hours, carrying out primary thermal activation treatment, and cooling to room temperature; under the condition of nitrogen gas introduction, the nitrogen gas is introduced into the reactor at a flow rate of 13m³Introducing nitrogen at a flow rate of/s, heating the mixture from room temperature to 250 ℃ at a speed of 1 ℃ per minute,and staying for 2 hours, heating to 550 ℃ at the speed of 1 ℃ per minute, then preserving the heat for 8 hours, carrying out secondary thermal activation treatment, and cooling to room temperature to obtain the spheroidal super-macroporous mesoporous material B1. Sampling the mesoporous material subjected to thermal activation treatment in the presence of nitrogen, wherein the spherical super-macroporous mesoporous material is not detected to contain moisture in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit (in terms of mass content) of the MA-30 intelligent Karl Fischer moisture tester is 0.1ppm, so that the moisture content in the spherical super-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm. And (3) putting 10g of the thermally activated mesoporous material B1 into a three-necked bottle, adding 10mL of toluene and 5mL of dichlorodimethylsilane, stirring at 30 ℃ for 10 hours, and blow-drying with nitrogen to obtain 10g of the spheroidal super-macroporous mesoporous material carrier C1.

(II) preparation of polyolefin catalyst

To pass through N₂Blowing and holding N₂Adding 130mL of tetrahydrofuran electron donor solvent into a reactor with a stirring device in the atmosphere, controlling the temperature of the reactor to be 30 ℃, adding 5.3g of magnesium dichloride and 1mL of titanium tetrachloride, adjusting the temperature of the system to 70 ℃, and reacting for 4 hours at constant temperature to obtain a solution containing the magnesium dichloride and the titanium tetrachloride. Cooling the solution to 50 ℃, adding 6g of the sphere-like super-macroporous mesoporous material carrier C1 into the solution containing magnesium dichloride and titanium tetrachloride, and stirring for 2 hours to prepare the slurry to be sprayed with uniform concentration. The resulting slurry to be sprayed is then introduced into a spray dryer at N₂Under protection, the temperature of an air inlet of the spray dryer is controlled to be 140 ℃, the temperature of an air outlet is controlled to be 105 ℃, and the flow rate of carrier gas is controlled to be 30L/s, and spray drying is carried out to obtain the polyolefin catalyst component Cat-1.

The spherical-like super-macroporous mesoporous material A1 and the polyolefin catalyst Cat-1 are characterized by an XRD, a scanning electron microscope, a particle size analyzer and an ASAP2020-M + C type nitrogen adsorption instrument.

As a result of X-ray fluorescence analysis, in the catalyst component Cat-1 obtained in this example, the content of magnesium element was 11.17% by weight and the content of titanium element was 2.55% by weight in terms of elements.

FIG. 1 is an XRD spectrum of a spheroidal ultra-macroporous mesoporous material. The XRD spectrogram shows that the mesoporous material has highly ordered pore structure.

FIG. 2 is a Scanning Electron Microscope (SEM) image (magnification of 20000 ×) of the spheroidal ultra-macroporous mesoporous material, and the SEM image shows that the microscopic morphology of the mesoporous material is spheroidal.

Table 1 shows the performance parameters of the mesoporous material.

Comparative example 1

This comparative example serves to illustrate a reference polyolefin catalyst and a process for its preparation.

(I) Preparation of the support

Commercially available silica gel (a product of Cabot Corporation under the trade name of TS610, particle size 0.02 to 0.1 μm) as a carrier D1, contained no moisture in the carrier D1 in the MA-30 smart Karl Fischer moisture meter in the presence of nitrogen gas, and the detection limit of the MA-30 smart Karl Fischer moisture meter was 0.1ppm (by mass content), so that the moisture content of the carrier D1 was <0.1 ppm; in the presence of nitrogen, the carrier D1 was not detected to contain oxygen in the ONH-3000 oxy-hydrogen analyzer, whereas the detection limit of the ONH-3000 oxy-hydrogen analyzer was 0.1ppm (by mass), so that the oxygen content in the carrier D1 was <0.1 ppm.

(II) preparation of polyolefin catalyst

A polyolefin catalyst was prepared according to the method of example 1, except that the same parts by weight of the above silica gel carrier D1 was used in place of the spheroidal super macroporous mesoporous material carrier C1, to thereby prepare a comparative catalyst Cat-D-1.

In the catalyst Cat-D-1, the content of magnesium element was 15.3% by weight and the content of titanium element was 2.5% by weight, based on the element.

Comparative example 2

This comparative example serves to illustrate a reference polyolefin catalyst and a process for its preparation.

A polyolefin catalyst was prepared according to the method of example 1, except that the same weight of alumina carrier was used instead of the spheroidal ultra-macroporous mesoporous material carrier C1, thereby preparing a carrier D2 and a polyolefin catalyst Cat-D-2, respectively.

X-ray fluorescence analysis shows that, in the catalyst Cat-D-2, the content of magnesium element is 14.6 wt% and the content of titanium element is 1.8 wt% in terms of elements.

Comparative example 3

This comparative example serves to illustrate a reference polyolefin catalyst and a process for its preparation.

The polyolefin catalyst Cat-D-3 was prepared according to the method of example 1, except that spray drying and organic modification treatment were not used in the preparation of the polyolefin catalyst Cat-D-3, but the polyolefin catalyst Cat-D-3 was prepared by directly filtering after the impregnation treatment, washing with n-hexane for 4 times, and drying at 75 ℃.

X-ray fluorescence analysis shows that, in the catalyst Cat-D-3, the content of magnesium element is 11.13 wt% and the content of titanium element is 1 wt% in terms of elements.

Example 2

(I) Preparation of the support

(1) 2.4 g of P123 (substance having a mean molecular weight Mn of 5800, which is registered under the American chemical Abstract accession number 9003-11-6) and 0.01 g of ammonium fluoride are added to 80mL of a 1.75mol/L hydrochloric acid solution and stirred at 20 ℃ until the P123 and ammonium fluoride are completely dissolved together;

(2) then 1mL of n-heptane and 5.5mL of ethyl orthosilicate are added into the solution, stirred vigorously for 4 minutes at 20 ℃ and then kept stand for 1 hour;

(3) transferring the obtained solution into a reaction kettle with a polytetrafluoroethylene lining, and crystallizing for 24 hours at 100 ℃;

(4) filtering, washing and drying to obtain a raw powder mesoporous material;

(5) calcining the mesoporous material in a muffle furnace at 500 ℃ for 24 hours, removing the template agent and introducing nitrogen gas at a pressure of 1.3m³Introducing nitrogen at a flow rate/s, heating to 250 ℃ from room temperature at a speed of 1 ℃ per minute, staying for 2 hours, heating to 550 ℃ at a speed of 1 ℃ per minute, then preserving heat for 8 hours, carrying out primary thermal activation treatment, and cooling to room temperature;under the condition of introducing nitrogen, the nitrogen concentration is 1.3m³Introducing nitrogen at a flow rate/s, heating to 250 ℃ from room temperature at a speed of 1 ℃ per minute, staying for 2 hours, heating to 550 ℃ at a speed of 1 ℃ per minute, then preserving heat for 8 hours, carrying out secondary thermal activation treatment, and cooling to room temperature to obtain a spheroidal ultra-macroporous mesoporous material B2, wherein in the presence of nitrogen, the spheroidal ultra-macroporous mesoporous material is not detected to contain moisture in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit of the MA-30 intelligent Karl Fischer moisture tester is (by mass content) 0.1ppm, so that the moisture content in the spheroidal ultra-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm. 10g of the thermally activated mesoporous material B2 is put into a three-necked bottle, 10mL of toluene and 5mL of dichlorodimethylsilane are added, stirred at 30 ℃ for 10 hours and then dried by nitrogen, and 10g of the sphere-like super-macroporous mesoporous material carrier C2 is obtained.

(II) preparation of polyolefin catalyst

The polyolefin catalyst Cat-2 was obtained according to the method of example 1.

Example 3

(I) Preparation of the support

(1) 2.4 g of P123 (substance having a mean molecular weight Mn of 5800, which is registered under the American chemical Abstract accession number 9003-11-6) and 3g of ammonium fluoride are added to 80mL of a 1.75mol/L hydrochloric acid solution and stirred at 20 ℃ until the P123 and ammonium fluoride are completely co-dissolved;

(2) then 100mL of n-heptane and 5.5mL of ethyl orthosilicate are added into the solution, stirred vigorously for 4 minutes at 20 ℃ and then kept stand for 1 hour;

(3) transferring the obtained solution into a reaction kettle with a polytetrafluoroethylene lining, and crystallizing for 24 hours at 100 ℃;

(4) filtering, washing and drying to obtain a raw powder mesoporous material;

(5) calcining the mesoporous material in a muffle furnace at 500 ℃ for 24 hours, removing the template agent, and introducing nitrogen at a flow rate of 1.3m³Introducing nitrogen at a flow rate/s, heating to 250 ℃ from room temperature at a speed of 1 ℃ per minute, staying for 2 hours, heating to 550 ℃ at a speed of 1 ℃ per minute, then preserving heat for 8 hours, carrying out primary thermal activation treatment, and cooling to room temperature; under the condition of introducing nitrogen, the nitrogen concentration is 1.3m³Introducing nitrogen at a flow rate/s, heating to 250 ℃ from room temperature at a speed of 1 ℃ per minute, staying for 2 hours, heating to 550 ℃ at a speed of 1 ℃ per minute, then preserving heat for 8 hours, carrying out secondary thermal activation treatment, and cooling to room temperature to obtain a spheroidal ultra-macroporous mesoporous material B3, wherein in the presence of nitrogen, the spheroidal ultra-macroporous mesoporous material is not detected to contain moisture in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit of the MA-30 intelligent Karl Fischer moisture tester is (by mass content) 0.1ppm, so that the moisture content in the spheroidal ultra-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm. 10g of the thermally activated mesoporous material B3 is put into a three-necked bottle, 10mL of toluene and 5mL of dichlorodimethylsilane are added, stirred at 30 ℃ for 10 hours and then dried by nitrogen, and 10g of the sphere-like super-macroporous mesoporous material carrier C3 is obtained.

(II) preparation of polyolefin catalyst

The polyolefin catalyst Cat-3 was obtained according to the method of example 1.

Example 4

The polyolefin catalyst component was prepared according to the method of example 1 except that in the preparation of the carrier of (I), the mesoporous material obtained by the thermal activation treatment was ball-milled under the nitrogen-free condition in the step (5), and the sphere-like super macroporous mesoporous material carrier C4 was prepared. In the presence of nitrogen, the moisture in the spherical super-macroporous mesoporous material is not detected in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit (by mass content) of the MA-30 intelligent Karl Fischer moisture tester is 0.1ppm, so the moisture content in the spherical super-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm.

(II) preparation of polyolefin catalyst

The polyolefin catalyst Cat-4 was obtained according to the method of example 1.

Example 5

A polyolefin catalyst component was prepared according to the procedure of example 1 except that in the step (I) support preparation, ammonium fluoride was used in an amount of 0.046 g. To obtain the sphere-like super macroporous mesoporous material carrier C5.

In the presence of nitrogen, the moisture in the spherical super-macroporous mesoporous material is not detected in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit (by mass content) of the MA-30 intelligent Karl Fischer moisture tester is 0.1ppm, so the moisture content in the spherical super-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm. The polyolefin catalyst Cat-5 was obtained according to the method of example 1.

Example 6

A polyolefin catalyst component was prepared according to the procedure of example 1 except that heptane was used in an amount of 28mL in the preparation of the support in step (I). To obtain the sphere-like super macroporous mesoporous material carrier C6. In the presence of nitrogen, the moisture in the spherical super-macroporous mesoporous material is not detected in an MA-30 intelligent Karl Fischer moisture tester, and the detection limit (by mass content) of the MA-30 intelligent Karl Fischer moisture tester is 0.1ppm, so the moisture content in the spherical super-macroporous mesoporous material is less than 0.1 ppm; in the presence of nitrogen, the mesoporous material is not detected to contain oxygen in an ONH-3000 oxygen-nitrogen-hydrogen analyzer, and the detection limit (calculated by mass content) of the ONH-3000 oxygen-nitrogen-hydrogen analyzer is 0.1ppm, so that the oxygen content in the spherical super-macroporous mesoporous material is less than 0.1 ppm. The polyolefin catalyst Cat-5 was obtained according to the method of example 1.

Comparative example 4

(I) Preparation of the support

2g of template F127 was added to a solution containing 37% by weight of hydrochloric acid (2.9g) and water (56g), and stirred at 40 ℃ until F127 was completely dissolved; then adding 8.2g (0.04mol) of tetraethoxysilane into the solution, stirring for 45min at 40 ℃, then transferring the obtained solution into a reaction kettle with a polytetrafluoroethylene lining, crystallizing for 24h at 100 ℃, filtering, washing for 4 times by using deionized water, and then carrying out suction filtration and drying to obtain mesoporous material raw powder with a cubic core structure; calcining the mesoporous material raw powder with the cubic core structure in a muffle furnace at 400 ℃ for 10 hours, and removing the template agent to obtain spherical mesoporous silicon dioxide D4 with the average grain diameter of 3-9 mu m and without the template agent; then calcining the spherical mesoporous silica D4 without the template agent at 400 ℃ for 10h under the protection of nitrogen for thermal activation treatment, and removing hydroxyl and residual moisture of the spherical mesoporous silica D4 to obtain thermally activated spherical mesoporous silica; in the presence of nitrogen, the mesoporous material after thermal activation treatment is sampled, the moisture content (by mass content) in the spheroidal super-macroporous mesoporous material is 500ppm measured by an MA-30 intelligent Karl Fischer moisture tester, and the oxygen content (by mass content) in the mesoporous material is 300ppm measured by an ONH-3000 oxygen-nitrogen analyzer.

And (2) putting 10g of the thermally activated spherical mesoporous silica D4 and 1g of dichlorodimethylsilane into a 100mL ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of each grinding ball is 3-15 mm, the number of the grinding balls is 30, the rotating speed is 400r/min, sealing the ball milling tank, and carrying out ball milling at the temperature of 25 ℃ in the ball milling tank for 12 hours to obtain the spherical mesoporous silica carrier D4 with the cubic core structure and the average particle size of 3-8 mu m.

(II) preparation of polyolefin catalyst

The polyolefin catalyst Cat-D-4 was obtained in the same manner as in example 1.

Comparative example 5

(I) Preparation of the support

Adding 1g of triblock copolymer polyethylene glycol-polyglycerol-polyethylene glycol P123 and 1.69 g of ethanol into 28mL of acetic acid with the pH value of 4.4 and sodium acetate buffer solution, and stirring at 15 ℃ until the polyethylene glycol-polyglycerol-polyethylene glycol P123 is completely dissolved; then 6g of trimethylpentane is added into the solution, 2.13 g of tetramethoxysilane is added into the solution after stirring for 8h at 15 ℃, the solution is transferred into a reaction kettle with a polytetrafluoroethylene lining after stirring for 20h at 15 ℃, crystallization is carried out for 24h at 60 ℃, and then raw powder of the eggshell-shaped mesoporous material is obtained after filtration, washing by deionized water and drying. Calcining the eggshell-shaped mesoporous material raw powder in a muffle furnace at 550 ℃ for 24h, and removing the template agent to obtain an eggshell-shaped mesoporous material D5 with the particle size between 3 and 22 mu m and without the template agent; then calcining the eggshell-shaped mesoporous material D5 without the template agent at 400 ℃ for 10h under the protection of nitrogen for thermal activation treatment to remove hydroxyl and residual moisture of the eggshell-shaped mesoporous material D5 and obtain the thermally activated eggshell-shaped mesoporous material; in the presence of nitrogen, the mesoporous material after thermal activation treatment was sampled, and the moisture content (by mass) in the mesoporous material was measured to be 300ppm in an MA-30 Smart Karl Fischer moisture meter, and the oxygen content (by mass) in the mesoporous material was measured to be 280ppm in an ONH-3000 OxN-H analyzer.

10g of the heat-activated eggshell-shaped mesoporous material D5 and 1g of dichlorodimethylsilane are put into a 100mL ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of the grinding balls is between 3 and 15mm, the number of the grinding balls is 30 (the number ratio of the large (more than 10mm), the medium (between 6 and 10mm) and the small (less than 6mm) grinding balls is approximately 1:2:3), and the ball milling tank is closed. Ball milling is carried out for 12 hours in a ball milling tank at the temperature of 25 ℃ and the rotating speed of 400r/min, and 10g of ground eggshell-shaped mesoporous material carrier D5 is obtained.

(II) preparation of polyolefin catalyst

The polyolefin catalyst Cat-D-5 was obtained in the same manner as in example 1.

Comparative example 6

(I) Preparation of the support

4g (0.0007mol) of template P123 was added to a solution containing 37% by weight of hydrochloric acid (16.4mL) and water (128mL) and stirred at 40 ℃ until P123 was completely dissolved; then adding 8.86g (0.042mol) of tetraethoxysilane into the solution, stirring for 24 hours at 40 ℃, then transferring the obtained solution into a reaction kettle with a polytetrafluoroethylene lining, crystallizing for 24 hours at 150 ℃, filtering, washing for 4 times by using deionized water, and then carrying out suction filtration and drying to obtain mesoporous material raw powder; washing the mesoporous material raw powder for 24 hours by using ethanol under the reflux condition, and removing a template agent to obtain a mesoporous molecular sieve D6; then calcining the product without the template agent for 10 hours at 400 ℃ under the protection of nitrogen to carry out thermal activation treatment, and removing hydroxyl and residual moisture of the mesoporous material to obtain a thermally activated mesoporous material D6; in the presence of nitrogen, the mesoporous material after thermal activation treatment was sampled, and the moisture content (by mass) in the mesoporous material was 250ppm as measured by an MA-30 Smart Karl Fischer moisture meter, and the oxygen content (by mass) in the mesoporous material was 390ppm as measured by an ONH-3000 OxN-H analyzer. And (2) putting 10g of the thermally activated mesoporous material D6 and 1g of dichlorodimethylsilane into a 100mL ball milling tank, wherein the ball milling tank is made of polytetrafluoroethylene, the grinding balls are made of agate, the diameter of each grinding ball is 3-15 mm, the number of the grinding balls is 30, the rotating speed is 400r/min, sealing the ball milling tank, and carrying out ball milling at the temperature of 25 ℃ in the ball milling tank for 12 hours to obtain 10g of mesoporous material carrier D6 with the average particle diameter of 1-10 mu m.

FIG. 3 is a scanning electron micrograph of a mesoporous material D6 obtained in comparative example 6. The mesoporous material is rod-shaped as can be seen from the scanning electron microscope spectrogram.

Fig. 4 to 5 are Scanning Electron Microscopes (SEM) of the mesoporous material D6 prepared in comparative example 6 in different visual field ranges after ball milling, and it can be seen from the SEM images that the mesoporous material D6 is completely crushed after ball milling.

(II) preparation of polyolefin catalyst

The procedure of example 1 was followed to obtain a polyolefin catalyst Cat-D-6.

Comparative example 7

A polyolefin catalyst component was prepared according to the procedure of example 1 except that in step (I) support preparation, the same weight of cyclohexane was used in place of heptane. Thus obtaining the mesoporous material D7.

In the presence of nitrogen, the mesoporous material after thermal activation treatment was sampled, and the moisture content (by mass) in the mesoporous material was measured to be 100ppm in an MA-30 Smart Karl Fischer moisture meter, and the oxygen content (by mass) in the mesoporous material was measured to be 130ppm in an ONH-3000 OxN-H analyzer.

The polyolefin catalyst Cat-D-7 was obtained in the same manner as in example 1.

Comparative example 8

A polyolefin catalyst component was prepared according to the procedure of example 1 except that no ammonium fluoride was added in the preparation of the support in step (I). Thus obtaining the mesoporous material D8. The mesoporous material after the thermal activation treatment was sampled in the presence of nitrogen, and the moisture content (by mass content) was measured to be 112ppm in an MA-30 Smart Karl Fischer moisture meter, and the oxygen content (by mass content) was measured to be 109ppm in the mesoporous material by an ONH-3000 OxN-Hydrogen analyzer. The polyolefin catalyst Cat-D-8 was obtained in the same manner as in example 1.

Comparative example 9

A polyolefin catalyst component was prepared according to the method of example 1, except that: in the step (I), the carrier preparation is carried out by one-time thermal activation treatment to obtain the sphere-like super-macroporous mesoporous material carrier D9. The mesoporous material after the thermal activation treatment was sampled in the presence of nitrogen, and the moisture content (by mass content) was measured to be 60ppm in an MA-30 Smart Karl Fischer moisture meter, and the oxygen content (by mass content) was measured to be 50ppm in the mesoporous material in an ONH-3000 OxN-H analyzer. The polyolefin catalyst Cat-D-9 was obtained in the same manner as in example 1.

TABLE 1 structural parameters of mesoporous materials

TABLE 2 structural parameters of the catalysts

Experimental example 1

This example is intended to illustrate the preparation of polyethylene by polymerization of ethylene using the polyolefin catalyst Cat-1 of the present invention

In a 2L stainless steel high-pressure polymerization kettle, replacing with nitrogen and ethylene for three times respectively, adding 1L hexane, 1mmol triethyl aluminum and 20-50 mg catalyst Cat-1 into the 2L stainless steel stirring kettle, then increasing the temperature to 85 ℃, adding 0.28MPa hydrogen at one time, then maintaining the total system pressure at 1MPa with ethylene for polymerization reaction, after 2 hours of reaction, stopping adding ethylene, reducing the temperature, relieving the pressure, weighing polyethylene powder, calculating the catalyst activity, and testing the molecular weight distribution index, the melt index MI2.16 of the polyethylene powder and the catalyst efficiency shown in Table 3.

Experimental comparative examples 1 to 9 and Experimental examples 2 to 6 were conducted in the same manner as in Experimental example 1.

TABLE 3

As can be seen from tables 1 to 3, the spherical-like super-macroporous mesoporous material C1 provided by the invention has the average particle size distribution (1-3 μm) and the specific surface area (350 m) as a carrier²The catalyst is most moderate, can be directly used as a catalyst carrier without ball milling, and the catalyst prepared from the catalyst has high catalytic activity, and particularly, the catalyst prepared from the sphere-like super-macroporous mesoporous material carrier C1 has the highest catalyst efficiency of 28000 gPE/gcat.h in the ethylene polymerization process.

While comparative example D4 had an average particle size distribution of 3 to 9 μm,the specific surface area is 800m²(ii)/g; the average particle size of D5 is 3-22 μm, and the specific surface area is 261m²The average particle size of D6 is 1-10 μm, and the specific surface area is 598m²The particle size distribution range of the mesoporous materials D4-D5 is wide, so that the three materials can be used after ball milling when being used as a polyolefin catalyst carrier. And the ball milling directly damages and even has slag to block the pore channels of the mesoporous material carrier (fig. 3, fig. 4 and fig. 5), thereby causing the activity of the catalyst to be reduced. The catalyst efficiency of the catalyst prepared from the mesoporous material D4 in the ethylene polymerization process is 19500 gPE/gcat.h; the catalyst efficiency of the catalyst prepared from the mesoporous material D5 in the ethylene polymerization process is 19000 gPE/gcat.h; the catalyst efficiency of the catalyst prepared from the mesoporous material D6 in the ethylene polymerization process is 17000 gPE/gcat.

It can be seen that the specific surface is too large>500m²A/g or too small<280m²The/g is not favorable for synthesizing polyethylene catalyst with high catalytic activity. This is because the specific surface area is too large>500m²The supported amount is too large in the catalyst synthesis process, so that the implosion is easily generated in the ethylene polymerization process, and the reduction of the catalytic activity is directly caused. While the specific surface area is too small<280m²The supported amount is small in the catalyst synthesis process, and the performance of the catalyst is not sufficiently exerted in the ethylene polymerization process, so that the catalytic activity is directly reduced.

This makes these three materials useful as polyolefin catalyst supports that must be ball milled before they can be used. And the pore channel of the mesoporous material carrier can be directly damaged after ball milling, so that the pore channel of the mesoporous material carrier is blocked, and the activity of the catalyst is further reduced.

As can be seen from tables 1-3, the average pore size of the spherical-like super-macroporous mesoporous material C1 provided by the invention is 12nm, and the average pore size of the material is most moderate, so that the material can be directly used as a catalyst carrier. And the highest catalyst efficiency of 28000gPE/gcat h was obtained. While comparative example D4 has an average pore size of 3nm, catalyst efficiency of 19500g PE/gcat.h, D5 has an average pore size of 9.8nm, catalyst efficiency of 19000g PE/gcat.h, D6 has an average pore size of 4.8nm, catalyst efficiency of 17000g PE/gcat.h, and catalytic effects are all less than the catalytic activity of the spheroidal support. It can be seen that the average pore size is less than 10nm, which is not favorable for synthesizing polyethylene catalyst with high catalytic activity. The reason is that the average pore diameter is less than 10nm, the macromolecular catalyst is not easy to enter a pore channel in the catalyst synthesis process, the catalytic efficiency is not sufficiently exerted in the ethylene polymerization process, and the catalytic activity is directly reduced. Therefore, the average pore diameter of the sphere-like mesoporous material C1 is most moderate, namely 12 nm. This directly leads to a maximum catalytic activity of 28000gPE/gcat h in the ethylene polymerization process.

From the results in table 3, it can be seen that the polyolefin catalyst component prepared by loading the titanium component and the magnesium component on the spheroidal ultra-macroporous mesoporous material carrier prepared by the method of the present invention has high catalytic activity, the polymer particles obtained when used for catalyzing ethylene polymerization have good morphology and excellent fluidity, the melt index of the polymerized powder is large, and the molecular weight distribution of the polymerized powder is narrow. The method brings convenience to storage, transportation, post-processing and application of the obtained polyolefin catalyst. In addition, the preparation method of the invention can be used for preparing the load type catalyst, and the spheroidal polyolefin catalyst can be directly obtained in one step by a spray drying method, so that the operation is simple and convenient.

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.