CN107417820B

CN107417820B - Spherical diatomite mesoporous composite material, supported catalyst and preparation method thereof

Info

Publication number: CN107417820B
Application number: CN201610348046.1A
Authority: CN
Inventors: 亢宇; 张明森
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2016-05-24
Filing date: 2016-05-24
Publication date: 2020-05-12
Anticipated expiration: 2036-05-24
Also published as: CN107417820A

Abstract

The invention relates to the field of catalysts, in particular to a spherical diatomite mesoporous composite material, a preparation method of the spherical diatomite mesoporous composite material, the spherical diatomite mesoporous composite material prepared by the method, a supported catalyst, a preparation method of the supported catalyst and the supported catalyst prepared by the method. The invention discloses a spherical diatomite mesoporous composite material which contains diatomite and a mesoporous molecular sieve material with a three-dimensional cubic cage-shaped pore passage structure. The spherical diatomite mesoporous composite material provided by the invention has larger pore volume and pore diameter and low preparation cost. The catalyst prepared from the spherical diatomite mesoporous composite material has high activity when used for catalyzing ethylene polymerization reaction, and has good fluidity.

Description

Spherical diatomite mesoporous composite material, supported catalyst and preparation method thereof

Technical Field

The invention relates to the field of mesoporous materials, in particular to a spherical diatomite mesoporous composite material, a preparation method of the spherical diatomite mesoporous composite material, the spherical diatomite mesoporous composite material prepared by the method, a supported catalyst, a preparation method of the supported catalyst and the supported catalyst prepared by the method.

Background

Since the synthesis of a regular mesoporous material with highly ordered pore channels by the company Mobile in 1992, the application of the mesoporous material in the fields of catalysis, separation, medicine and the like has attracted much attention due to the high specific surface, the regular pore channel structure and the narrow pore size distribution. A novel mesoporous material SBA-15 is synthesized by Zhao Dongyuan et al in 1998, which has highly ordered pore diameter (6-30nm) and large pore volume (1.0 cm)³Per g), thicker cell walls (4-6nm), retained high mechanical strength andgood catalytic adsorption performance (see D.Y.ZHao, J.L.Feng, Q.S.Huo, et al Science 279(1998) 548-550). CN1341553A discloses a preparation method of a mesoporous molecular sieve carrier material, and the mesoporous material prepared by the method is used as a heterogeneous reaction catalyst carrier, so that the separation of a catalyst and a product is easy to realize.

However, the conventional ordered mesoporous material SBA-15 has a rod-like microscopic morphology, the flowability of the material is poor, and the high specific surface area and the high pore volume of the material cause the material to have strong water and moisture absorption capacity, so that the agglomeration of the ordered mesoporous material is further aggravated, and the storage, transportation, post-processing and application of the ordered mesoporous material are limited.

The development and application of polyethylene catalysts is a major breakthrough in the field of olefin polymerization catalysts after traditional ziegler-natta catalysts, which makes the research of polyethylene catalysts enter a rapidly developing stage. The homogeneous phase polyethylene catalyst has high activity, needs large catalyst consumption and high production cost, and the obtained polymer has no granular shape and cannot be used in a polymerization process of a slurry method or a gas phase method which is widely applied. An effective method for overcoming the above problems is to carry out a supporting treatment of the soluble polyethylene catalyst. At present, a great number of researches on the loading of polyethylene catalysts are reported. In order to develop new support/catalyst/cocatalyst systems in depth, it is necessary to develop different supports to drive the further development of the supported catalyst and polyolefin industries.

The mesoporous material of the supported polyethylene catalyst reported in the previous literature is MCM-41, and the catalytic activity of the MCM-41 which is treated by MAO and then supported by the polyethylene catalyst after ethylene polymerization is 10⁶gPE/(mol Zr h) (Chen S T, Guo CY, Lei L, et al. Polymer,2005,46: 11093). The reason that the mesoporous material MCM-41 is low in ethylene polymerization activity after loading a catalyst is mainly that the thermal stability and the hydrothermal stability of a pore wall structure of the MCM-41 are low, partial collapse of the pore wall is caused in the loading process, the loading effect is influenced, and the catalytic activity is influenced.

In addition, the preparation cost of the currently used supported polyethylene catalyst is high, and in order to further improve the benefit, a new mesoporous material is needed to be sought, so that the preparation cost of the catalyst can be reduced, the activity of the catalyst can be ensured, and the performance of the polyethylene product can be improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the spherical diatomite mesoporous composite material with larger pore volume and pore diameter, the spherical diatomite mesoporous composite material has low preparation cost and better fluidity, and when the catalyst prepared by adopting the spherical diatomite mesoporous composite material is used for catalyzing the polymerization reaction of ethylene, a polyethylene product with lower bulk density and melt index and difficult breakage can be obtained.

In order to achieve the above objects, in one aspect, the present invention provides a spherical diatomite mesoporous composite material, wherein the spherical diatomite mesoporous composite material comprises diatomite and a mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure, and the spherical diatomite mesoporous composite material has an average particle size of 30-60 μm, a specific surface area of 200-650 m/g, a pore volume of 2.1-3.5 ml/g, and a trimodal pore size distribution, and the three peaks respectively correspond to a first mode pore size, a second mode pore size and a third mode pore size, the second mode pore size is smaller than the third mode pore size, the first mode pore size is 3-10 nm, the second mode pore size is 20-40 nm, and the third mode pore size is 30-50 nm.

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

(1) providing a mesoporous molecular sieve material with a three-dimensional cage-shaped pore channel structure or preparing a filter cake of the mesoporous molecular sieve material with the three-dimensional cage-shaped pore channel structure as a component a;

(2) providing silica gel or preparing a filter cake of silica gel as component b;

(3) mixing and ball-milling the component a, the component b, the diatomite and the binder, pulping solid powder obtained after ball-milling with water, and then carrying out spray drying on the obtained slurry;

the average particle size of the spherical diatomite mesoporous composite material is 30-60 micrometers, the specific surface area is 200-650 square meters per gram, the pore volume is 2.1-3.5 milliliters per gram, the pore diameters are in trimodal distribution, the three peaks respectively correspond to a first most probable pore diameter, a second most probable pore diameter and a third most probable pore diameter, the second most probable pore diameter is smaller than the third most probable pore diameter, the first most probable pore diameter is 3-10 nanometers, the second most probable pore diameter is 20-40 nanometers, and the third most probable pore diameter is 30-50 nanometers.

In a third aspect, the invention provides the spherical diatomite mesoporous composite material prepared by the preparation method.

In a fourth aspect, the present invention provides a supported catalyst, which comprises a carrier and a magnesium salt and/or a titanium salt supported on the carrier, wherein the carrier is the spherical diatomite mesoporous composite material provided by the present invention.

In a fifth aspect, the present invention provides a method for preparing a supported catalyst, the method comprising: in the presence of inert gas, the carrier is soaked in mother liquor containing magnesium salt and/or titanium salt, and then is sequentially filtered and dried; wherein, the carrier is the spherical diatomite mesoporous composite material provided by the invention.

In a sixth aspect, the present invention provides a supported catalyst prepared by the above method.

The spherical diatomite mesoporous composite material provided by the invention has larger pore volume, and simultaneously, cheap diatomite is introduced into the composite material, so that the production cost of the carrier can be reduced to a great extent. In addition, the supported catalyst provided by the invention is spherical and has good flow property, the supported catalyst has higher activity when being used for preparing polyethylene by ethylene polymerization, the prepared polyethylene has lower bulk density and melt index, and polymer particles are not easy to break, specifically, the bulk density of the prepared polyethylene is less than 0.4g/mL, the melt index is less than 0.6g/10min, and the crushing rate is not more than 3%.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is an X-ray diffraction pattern of a spherical diatomite mesoporous composite material C1 according to example 1 of the present invention;

FIG. 2 is an SEM scanning electron microscope image of the micro-morphology of the spherical diatomite mesoporous composite material C1 in example 1 of the invention;

fig. 3 is a pore size distribution diagram of the spherical diatomite mesoporous composite material C1 according to example 1 of the present invention.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

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.

In a first aspect, the present invention provides a spherical diatomite mesoporous composite material, wherein the spherical diatomite mesoporous composite material comprises diatomite and a mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure, and the spherical diatomite mesoporous composite material has an average particle size of 30-60 microns, a specific surface area of 200-650 square meters/g, a pore volume of 2.1-3.5 ml/g, and trimodal pore diameters, and the three peaks respectively correspond to a first most probable pore diameter, a second most probable pore diameter, and a third most probable pore diameter, wherein the second most probable pore diameter is smaller than the third most probable pore diameter, and the first most probable pore diameter is 3-10 nm, the second most probable pore diameter is 20-40 nm, and the third most probable pore diameter is 30-50 nm.

In the invention, the average particle size of the spherical diatomite mesoporous composite material is measured by a laser particle size distribution instrument, the specific surface area, the pore volume and the most probable pore diameter are measured by a nitrogen adsorption method, and the surface morphology of the spherical diatomite mesoporous composite material is measured by a Scanning Electron Microscope (SEM). In the present invention, the average particle diameter is an average particle diameter.

In the present invention, the conversion rate of the reaction raw material in the ethylene polymerization process can be improved by using the supported catalyst prepared by using the spherical diatomite mesoporous composite material as the carrier by controlling the particle size of the spherical diatomite mesoporous composite material within the above range.

Preferably, the average particle diameter of the spherical diatomite mesoporous composite material is 30-55 microns, the specific surface area is 200-450 square meters per gram, the pore volume is 2.1-3 milliliters per gram, the first mode pore diameter is 4-8 nanometers, the second mode pore diameter is 20-40 nanometers, and the third mode pore diameter is 30-50 nanometers.

Further preferably, the average particle size of the spherical diatomite mesoporous composite material is 50-55 microns, the specific surface area is 200-260 square meters per gram, the pore volume is 2.1-2.5 milliliters per gram, the first mode pore diameter is 5-7 nanometers, the second mode pore diameter is 20-40 nanometers, and the third mode pore diameter is 30-50 nanometers.

The content of the molecular sieve material with the three-dimensional cubic cage-shaped pore structure and the diatomite in the spherical diatomite mesoporous composite material is not particularly limited, as long as the microscopic size of the spherical diatomite mesoporous composite material meets the conditions.

According to the present invention, the content of the diatomaceous earth may be 1 to 100 parts by weight, preferably 10 to 80 parts by weight, and more preferably 20 to 50 parts by weight, with respect to 100 parts by weight of the mesoporous molecular sieve material having a three-dimensional cubic cage-like pore structure.

In the present invention, the spherical diatomite mesoporous composite may further contain silica introduced through silica gel. The term "silica introduced through silica gel" refers to a silica component which is introduced into the finally prepared spherical diatomite mesoporous composite material from silica gel as a preparation raw material during the preparation of the spherical diatomite mesoporous composite material. In the spherical diatomite mesoporous composite material, the content of the silica introduced through the silica gel may be 1 to 200 parts by weight, preferably 50 to 200 parts by weight, with respect to 100 parts by weight of the mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure.

Preferably, the above steps make the average particle diameter of the spherical diatomite mesoporous composite material be 30-55 microns, the specific surface area be 200-450 square meters/g, the pore volume be 2.1-3 ml/g, the first most probable pore diameter be 4-8 nm, the second most probable pore diameter be 20-40 nm, and the third most probable pore diameter be 30-50 nm.

Further preferably, the above steps are carried out so that the average particle diameter of the spherical diatomite mesoporous composite material is 50-55 microns, the specific surface area is 200-260 square meters/g, the pore volume is 2.1-2.5 ml/g, the first mode pore diameter is 5-7 nanometers, the second mode pore diameter is 20-40 nanometers, and the third mode pore diameter is 30-50 nanometers.

In the step (1), the process of preparing a filter cake of the mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore channel structure may include: in an acidic aqueous solution, in the presence of potassium sulfate, a template agent is contacted with a silicon source, and a mixture obtained after the contact is crystallized and filtered.

In the step (1), the amount of the potassium sulfate may be 800 moles, preferably 400 moles, relative to 1 mole of the template agent; the silicon source may be used in an amount of 20 to 200 moles, preferably 100 to 200 moles.

In the present invention, the templating agent may be various templating agents conventionally used in the art. Most preferably, the templating agent is a triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene, which is commercially available (e.g., from Fuka corporation under the trade name

F108, molecular formula EO₁₃₂PO₆₀EO₁₃₂And Mn is 14600), or can be prepared by a conventional method. When the template is polyoxyethylene-polyoxypropylene-polyoxyethylene, the number of moles of the template is calculated from the average molecular weight of polyoxyethylene-polyoxypropylene-polyoxyethylene.

In the present invention, the silicon source may be various silicon sources conventionally used in the art, preferably the silicon source is at least one of tetraethoxysilane, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol, and most preferably tetraethoxysilane.

In the present invention, the acidic aqueous solution may be various acidic aqueous solutions conventionally used in the art, and for example, may be at least one aqueous solution of hydrochloric acid, sulfuric acid, nitric acid, and hydrobromic acid, and preferably an aqueous hydrochloric acid solution.

In the present invention, the conditions for contacting the templating agent with the silicon source may include: the temperature is 25-60 ℃, the time is 10-72 hours, and the pH value is 1-7; preferably, the conditions under which the templating agent is contacted with the silicon source include: the temperature is 35-45 deg.C, and the time is 20-30 hr. In order to further facilitate uniform mixing between the substances, the contacting of the templating agent and the silicon source is preferably performed under stirring conditions. The dosage of the acidic aqueous solution is preferably such that the pH value of the contact reaction system of the template agent and the silicon source is 1-7.

In the step (1), the crystallization conditions may include: the temperature is 90-150 ℃, and the time is 10-40 h; preferably, the temperature is 90-120 ℃ and the time is 20-30 h. Further preferably, the crystallization is performed by a hydrothermal crystallization method.

In the above process of preparing a filter cake of a mesoporous molecular sieve material having a three-dimensional cubic cage pore structure, the process of obtaining the filter cake by filtration may include: after filtration, repeated washing with deionized water (washing times may be 2 to 10) and suction filtration.

In the step (1), "providing the mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure" may be a product obtained by directly weighing or selecting the mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure, or may be a product obtained by preparing the mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure. The preparation method of the mesoporous molecular sieve material with the three-dimensional cage-shaped pore channel structure can be implemented according to a conventional method, and for example, the preparation method can comprise the following steps: according to the method, the filter cake of the mesoporous molecular sieve material with the three-dimensional cage-shaped pore channel structure is prepared, and then the obtained filter cake is dried.

In the step (2), the process of preparing the filter cake of silica gel may include: the water glass is contacted with the polyhydric alcohol in the presence of the mineral acid, and the mixture obtained after the contact is filtered.

In the present invention, the polyol is not particularly limited, and is preferably at least one of ethylene glycol, propylene glycol and glycerin, preferably ethylene glycol and/or glycerin, and more preferably glycerin.

The conditions for contacting the water glass with the polyol in the present invention are not particularly limited, and may be appropriately determined according to the conventional process for preparing silica gel. Preferably, the contacting conditions include: the temperature is 10-60 ℃, preferably 30-45 ℃; for a period of 1 to 5 hours, preferably 1 to 3 hours; the pH value is 2-4, preferably 2.5-3.5.

In order to facilitate the uniform mixing of the materials, the contact reaction of the water glass and the polyol is preferably carried out under stirring.

Preferably, the weight ratio of the water glass, the inorganic acid and the polyhydric alcohol is 3-6: 2-3: 1; more preferably 3 to 5: 1: 1.

the water glass is an aqueous solution of sodium silicate, and the concentration thereof may be 3 to 20% by weight, preferably 10 to 20% by weight.

The inorganic acid may be various inorganic acids conventionally used in the art, and for example, may be at least one of sulfuric acid, nitric acid, and hydrochloric acid. The inorganic acid may be used in a pure form or in the form of an aqueous solution thereof. The inorganic acid is preferably used in such an amount that the pH of the contact reaction system of water glass and a polyhydric alcohol is 2 to 4.

In the step (2), "providing silica gel" may be directly weighing or selecting the silica gel product, or may be preparing silica gel. The method for preparing silica gel may be carried out according to conventional methods, and may include, for example: a filter cake of silica gel was prepared according to the above method and the resulting filter cake was then dried.

The amount and type of the binder are not particularly limited, and in order to improve the strength of the spherical diatomite mesoporous composite material and the performance of the polyethylene product, the amount of the component b may be 1 to 200 parts by weight, preferably 50 to 200 parts by weight, relative to 100 parts by weight of the component a; the amount of the diatomaceous earth may be 1 to 100 parts by weight, preferably 20 to 50 parts by weight; the binder may be used in an amount of 1 to 10 parts by weight, preferably 2 to 8 parts by weight.

Preferably, the binder is polyvinyl alcohol and/or polyethylene glycol, most preferably polyvinyl alcohol.

In the step (3), the ball milling may be performed in a ball mill, the inner wall of a ball milling pot in the ball mill is preferably agate lining, and the diameter of the milling balls in the ball mill may be 2-3 mm; the number of the grinding balls can be reasonably selected according to the size of the ball milling tank, and for the ball milling tank with the size of 50-150mL, 1 grinding ball can be generally used; the material of the grinding ball can be agate, polytetrafluoroethylene and the like, and agate is preferred. The ball milling conditions may include: the rotation speed of the grinding ball is 200-; preferably, the rotation speed of the grinding balls is 300-.

In the step (3), the process of slurrying the solid powder obtained after ball milling with water may be performed at 25 to 60 ℃. The weight ratio of solid powder to water used in the pulping process may be 1:0.1-5, preferably 1: 0.5-3.5.

In step (3), the spray drying may be carried out according to conventional means, for example in an atomizer. The conditions of the spray drying may include: the temperature is 150-; preferably, the spray drying conditions include: the temperature is 150-250 ℃, and the rotating speed is 11000-13000 r/min.

In the step (3), when the component a is a filter cake of a mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure, and the component b is a filter cake of silica gel, that is, when the step (1) is a process of preparing a filter cake of a mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore structure, and the step (2) is a process of preparing a filter cake of silica gel, the method for preparing the spherical diatomite mesoporous composite material further includes: after the spray-drying process of step (3), the template is removed from the spray-dried product. Preferably, the conditions for removing the template agent include: the temperature is 90-600 ℃, and more preferably 400-600 ℃; the time is 10 to 80 hours, more preferably 10 to 24 hours.

In a third aspect, the invention also provides the spherical diatomite mesoporous composite material prepared by the method.

In a fourth aspect, the invention further provides a supported catalyst, which comprises a carrier and magnesium salt and/or titanium salt loaded on the carrier, wherein the carrier is the spherical diatomite mesoporous composite material provided by the invention.

According to the invention, in the supported catalyst, the content of the magnesium salt and/or the titanium salt is not particularly limited, and preferably, the content of the spherical diatomite mesoporous composite material is 90-99 wt% based on the total weight of the catalyst, and the sum of the contents of the magnesium salt and the titanium salt in terms of magnesium element and titanium element is 1-10 wt%; more preferably, the content of the spherical diatomite mesoporous composite material is 94-96 wt%, and the sum of the contents of the magnesium salt and the titanium salt calculated by the magnesium element and the titanium element respectively is 4-6 wt%; more preferably, the content of the spherical diatomite mesoporous composite material is 94.3-95 wt%, and the sum of the contents of the magnesium salt and the titanium salt calculated by magnesium element and titanium element respectively is 5-5.7 wt%.

In the present invention, the catalyst may be prepared according to various methods conventionally used in the art, as long as a magnesium salt and/or a titanium salt is supported on the spherical diatomaceous earth mesoporous composite.

In a fifth aspect, the present invention also provides a method for preparing a supported templating agent, comprising: in the presence of inert gas, the carrier is soaked in mother liquor containing magnesium salt and/or titanium salt, and then is sequentially filtered and dried; wherein, the carrier is the spherical diatomite mesoporous composite material provided by the invention.

According to the invention, the impregnation conditions may include: the temperature is 25-100 ℃, and the time is 0.1-5 h; preferably, the impregnation conditions include: the temperature is 40-60 ℃ and the time is 1-3 h.

In the present invention, the amount of the magnesium salt and the titanium salt is not particularly limited, and preferably, the amount of the carrier, the magnesium salt and the titanium salt is such that the content of the spherical diatomite mesoporous composite material in the prepared supported catalyst is 90-99 wt% and the sum of the contents of the magnesium salt and the titanium salt in terms of magnesium element and titanium element is 1-10 wt%, based on the total weight of the catalyst; more preferably, the content of the spherical diatomite mesoporous composite material is 94-96 wt%, and the sum of the contents of the magnesium salt and the titanium salt calculated by the magnesium element and the titanium element respectively is 4-6 wt%; more preferably, the content of the spherical diatomite mesoporous composite material is 94.3-95 wt%, and the sum of the contents of the magnesium salt and the titanium salt calculated by magnesium element and titanium element respectively is 5-5.7 wt%.

In a preferred embodiment of the present invention, the magnesium salt and the titanium salt are used in a weight ratio of 1:0.1 to 2, preferably 1: 0.5-2.

In the present invention, the magnesium salt may be various magnesium salts conventionally used in the art, for example, may be one or more of magnesium chloride, magnesium sulfate, magnesium nitrate and magnesium bromide, and is preferably magnesium chloride.

In the present invention, the titanium salt may be various titanium salts conventionally used in the art, and for example, titanium tetrachloride and/or titanium trichloride may be mentioned.

In the invention, the content of the elements in the catalyst can be measured by adopting an X-ray fluorescence spectrum analysis method.

The mother liquor may preferably further contain an organic solvent for dissolving the magnesium salt and the titanium salt, and the organic solvent is not particularly limited in the present invention as long as the magnesium salt and the titanium salt can be dissolved, and for example, isopropanol and tetrahydrofuran may be used, and the volume ratio of isopropanol to tetrahydrofuran may be 1: 1-3, preferably 1: 1-1.5.

In the present invention, the drying conditions for the preparation of the catalyst in the present invention are not particularly limited, and may be various conditions commonly used in the art; preferably, the preparation of the catalyst also comprises a washing process after filtration and before drying, and/or a milling process after drying. The washing and milling conditions can be selected by the person skilled in the art according to the practical circumstances and will not be described in detail here.

In the present invention, the inert gas is a gas which does not react with the raw materials and the product, and may be, for example, nitrogen gas or at least one of group zero element gases in the periodic table, preferably nitrogen gas, which is conventional in the art.

In a sixth aspect, the present invention also provides a supported catalyst prepared by the above method.

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

In the following examples and comparative examples, polyoxyethylene-polyoxypropylene-polyoxyethylene was obtained from Fuka under the trade name

F108, molecular formula EO₁₃₂PO₆₀EO₁₃₂Abbreviated as F108, and an average molecular weight Mn of 14600.

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 a nitrogen desorption apparatus model Autosorb-1 available from corna, usa, wherein the sample was degassed at 200 ℃ for 4 hours before testing; the X-ray fluorescence analysis was carried out on an X-ray fluorescence analyzer of the Netherlands company, model Axios-Advanced.

The bulk density of the polyolefin powder was determined by the method specified in GB/T1636-2008.

Polymer melt index: measured according to ASTM D1238-99.

Polyethylene pulverization rate: determined by sieving through a 800 mesh screen.

Example 1

This example is used to illustrate the spherical diatomite mesoporous composite material and supported catalyst of the present invention and their preparation methods.

(1) Preparation of spherical diatomite mesoporous composite material

1.46g (0.0001mol) of template F108 and 5.24g (0.03mol) of K₂SO₄Stirring with 60g hydrochloric acid solution with equivalent concentration of 2 at 38 ℃ until F108 is completely dissolved;

4.2g (0.02mol) of tetraethyl orthosilicate was added to the above solution, stirred at 38 ℃ for 15 minutes, and left to stand at 38 ℃ for 24 hours;

then transferring the mixture into a reaction kettle with an agate inner lining, crystallizing the mixture for 24 hours at the temperature of 100 ℃, then filtering the mixture, washing the mixture for 4 times by using deionized water, and then carrying out suction filtration to obtain a filter cake A1 of the mesoporous molecular sieve material with the three-dimensional cubic cage-shaped pore channel structure.

Mixing 15 wt% of water glass, 12 wt% of sulfuric acid solution and glycerol in a weight ratio of 5: 1: 1 at 30 ℃ for 1.5 hours, followed by adjustment of the pH to 3 with 98% strength by weight sulfuric acid, suction filtration of the resulting reaction mass and washing with distilled water to a sodium ion content of 0.02% by weight, to give a filter cake of silica gel B1.

And (3) putting 10g of the prepared filter cake A1, 10g of the prepared filter cake B1, 5g of diatomite and 0.5g of polyvinyl alcohol into a 100mL ball milling tank, wherein the ball milling tank is made of agate, grinding balls are made of agate, the diameter of each grinding ball is 3mm, the number of the grinding balls is 1, and the rotating speed is 400 r/min. Sealing the ball milling tank, and ball milling for 5 hours in the ball milling tank at the temperature of 25 ℃ to obtain solid powder; dissolving the solid powder in 25g of deionized water, and spray-drying at 200 ℃ at a rotating speed of 12000 r/min; calcining the product obtained after spray drying in a muffle furnace at 550 ℃ for 10h, and removing F108 (template) to obtain the spherical diatomite mesoporous composite material C1.

The spherical diatomite mesoporous composite material C1 is characterized by XRD, a scanning electron microscope and a nitrogen adsorption instrument.

Fig. 1 is an X-ray diffraction pattern, and it can be seen from the figure that the spherical diatomite mesoporous composite material C1 has a three-dimensional cubic cage-shaped pore structure specific to mesoporous materials.

Fig. 2 is a microscopic morphology SEM image of the spherical diatomaceous earth mesoporous composite material C1, which shows that the microscopic morphology of the spherical diatomaceous earth mesoporous composite material C1 is microspheres with a particle size of 30-60 μm, and the dispersion performance is good.

Fig. 3 is a pore size distribution diagram of the spherical diatomite mesoporous composite material C1, and it can be seen from the diagram that the spherical diatomite mesoporous composite material C1 has a three-pore structure distribution and uniform pore channels.

The pore structure parameters of the spherical diatomite mesoporous composite material C1 are shown in the following table 1.

TABLE 1

*: the first most probable aperture, the second most probable aperture, and the third most probable aperture are separated by commas: the first most probable aperture, the second most probable aperture and the third most probable aperture are arranged from front to back in sequence.

(2) Preparation of the catalyst

0.1g of magnesium chloride and 0.1g of titanium tetrachloride were dissolved in 10mL of a composite solvent of tetrahydrofuran and isopropanol (the volume ratio of tetrahydrofuran to isopropanol was 1: 1.2) to form a catalyst mother liquor. 1g of the spherical diatomite mesoporous composite material C1 was added to the mother liquor at 45 ℃ for immersion for 1h, then filtered, and washed with n-hexane for 4 times, dried at 75 ℃ and ground to obtain the catalyst D1.

As a result of X-ray fluorescence analysis, in the catalyst D1 described in this example, the content of magnesium element was 4.1% by weight and the content of titanium element was 1.5% by weight in terms of element.

Example 2

1.46g (0.0001mol) of template F108 and 6.96g (0.04mol) of K₂SO₄Stirring with 60g hydrochloric acid solution with equivalent concentration of 2 at 38 ℃ until F108 is completely dissolved;

adding 3.1g (0.015mol) tetraethyl orthosilicate into the solution, stirring for 15min at 45 ℃, and standing for 30h at 45 ℃;

then transferring the mixture into a reaction kettle with an agate inner lining, crystallizing the mixture for 30 hours at 120 ℃, then filtering the mixture, washing the mixture for 4 times by using deionized water, and then carrying out suction filtration to obtain a filter cake A2 of the mesoporous molecular sieve material with the three-dimensional cubic cage-shaped pore channel structure.

Mixing 20 wt% of water glass, 12 wt% of sulfuric acid solution and glycerol in a weight ratio of 4: 1: 1, and then the reaction mixture was subjected to a contact reaction at 40 ℃ for 3 hours, followed by adjusting the pH to 4 with sulfuric acid having a concentration of 98% by weight, and then the resulting reaction mass was subjected to suction filtration and washed with distilled water until the sodium ion content was 0.02% by weight, to obtain a silica gel cake B2.

10g of the filter cake A2, 5g of the filter cake B2, 4g of diatomite and 0.2g of polyvinyl alcohol are put into a 100mL ball milling tank together, wherein the ball milling tank is made of agate, grinding balls are made of agate, the diameter of each grinding ball is 3mm, the number of the grinding balls is 1, and the rotating speed is 500 r/min. Sealing the ball milling tank, and carrying out ball milling for 10 hours in the ball milling tank at the temperature of 30 ℃ to obtain solid powder; dissolving the solid powder in 100g of deionized water, and spray-drying at 150 ℃ at the rotating speed of 13000 r/min; calcining the product obtained after spray drying in a muffle furnace at 600 ℃ for 15h, and removing F108 (template) to obtain the spherical diatomite mesoporous composite material C2.

The pore structure parameters of the spherical diatomite mesoporous composite material C2 are shown in table 2 below.

TABLE 2

(2) Preparation of the catalyst

0.1g of magnesium chloride and 0.2g of titanium tetrachloride were dissolved in 10mL of a composite solvent of tetrahydrofuran and isopropanol (the volume ratio of tetrahydrofuran to isopropanol was 1: 1.5) to form a catalyst mother liquor. 1g of spherical diatomite mesoporous composite material C2 was added to the mother liquor at 60 ℃ for immersion for 1h, then filtered, and washed with n-hexane for 4 times, dried at 75 ℃ and ground to obtain catalyst D2.

As a result of X-ray fluorescence analysis, in the catalyst D2 described in this example, the content of magnesium was 3.6% by weight and the content of titanium was 2.1% by weight in terms of element.

Example 3

(1) Preparation of spherical diatomite mesoporous composite material

1.46g (0.0001mol) of template F108 and 3.48g (0.02mol) of K₂SO₄Stirring with 60g hydrochloric acid solution with equivalent concentration of 2 at 38 ℃ until F108 is completely dissolved;

adding 2.1g (0.01mol) tetraethyl orthosilicate into the solution, stirring at 35 ℃ for 15min, and standing at 35 ℃ for 20 h;

then transferring the mixture into a reaction kettle with an agate inner lining, crystallizing the mixture for 20 hours at the temperature of 90 ℃, then filtering the mixture, washing the mixture for 4 times by using deionized water, and then carrying out suction filtration to obtain a filter cake A3 of the mesoporous molecular sieve material with the three-dimensional cubic cage-shaped pore channel structure.

Mixing 10 wt% of water glass, 12 wt% of sulfuric acid solution and glycerol in a weight ratio of 3: 1: 1 at 45 ℃ and then adjusted to a pH of 2 with sulfuric acid having a concentration of 98% by weight, the reaction mass obtained is filtered off with suction and washed with distilled water to a sodium ion content of 0.02% by weight, giving a silica gel cake B3.

10g of the filter cake A3, 20g of the filter cake B3, 2g of diatomite and 0.8g of polyvinyl alcohol are placed into a 100mL ball milling tank together, wherein the ball milling tank is made of agate, grinding balls are made of agate, the diameter of each grinding ball is 3mm, the number of the grinding balls is 1, and the rotating speed is 300 r/min. Sealing the ball milling tank, and ball milling for 20 hours in the ball milling tank at the temperature of 50 ℃ to obtain solid powder; dissolving the solid powder in 50g of deionized water, and spray-drying at 250 ℃ at the rotating speed of 11000 r/min; calcining the product obtained after spray drying in a muffle furnace at 400 ℃ for 24h, and removing F108 (template) to obtain the spherical diatomite mesoporous composite material C3.

The pore structure parameters of the spherical diatomite mesoporous composite material C3 are shown in table 3 below.

TABLE 3

(2) Preparation of the catalyst

0.2g of magnesium chloride and 0.1g of titanium tetrachloride were dissolved in 10mL of a composite solvent of tetrahydrofuran and isopropanol (the volume ratio of tetrahydrofuran to isopropanol was 1: 1) to form a catalyst mother liquor. 1g of the spherical diatomite mesoporous composite material C3 was added to the mother liquor at 40 ℃ for immersion for 3h, then filtered, and washed with n-hexane for 4 times, dried at 75 ℃ and ground to obtain the catalyst D3.

As a result of X-ray fluorescence analysis, in the catalyst D3 described in this example, the content of magnesium was 3.2% by weight and the content of titanium was 1.8% by weight in terms of element.

Example 4

The spherical diatomite mesoporous composite material and the supported catalyst were prepared according to the same method as in example 1, except that during the preparation of the spherical diatomite mesoporous composite material in the step (1), glycerol was not added during the preparation of the filter cake of silica gel, to obtain the spherical diatomite mesoporous composite material C4 and the supported catalyst D4.

The pore structure parameters of the spherical diatomite mesoporous composite material C4 are shown in table 4 below.

TABLE 4

As a result of X-ray fluorescence analysis, in the catalyst D4 described in this example, the content of magnesium element was 4.2% by weight and the content of titanium element was 1.4% by weight in terms of element.

Comparative example 1

A spherical diatomite mesoporous composite material and a supported catalyst were prepared according to the method of example 1, except that in the preparation of the spherical diatomite mesoporous composite material, filter cake a1 of a mesoporous molecular sieve material having a three-dimensional cubic cage-shaped pore channel structure was replaced with rod-shaped mesoporous silica SBA-15 (purchased from high-tech, inc., gilin university) of the same weight, thereby preparing a mesoporous composite material DC1 and a supported catalyst DD 1.

Comparative example 2

The diatomite is calcined for 10 hours at 400 ℃ under the protection of nitrogen to remove hydroxyl and residual moisture, thereby obtaining the diatomite raw soil subjected to heat activation.

A catalyst was prepared according to the procedure of step (2) of example 1, except that the same parts by weight of the above thermally activated diatomite as-is used in place of the spherical diatomite mesoporous composite material C1, thereby obtaining a comparative catalyst DD 2.

Comparative example 3

A spherical diatomaceous earth mesoporous composite and a supported catalyst were prepared in the same manner as in example 1, except that, in the preparation of the spherical diatomaceous earth mesoporous composite in step (1), 10g of the filter cake a1, 10g of the filter cake B1, and 5g of diatomaceous earth were put together in a 100mL ball mill pot, that is, polyvinyl alcohol was not added as a binder. Thus, comparative catalyst DD3 was obtained.

Experimental example 1

This experimental example is used to illustrate the application of the supported catalyst provided by the present invention.

In a 2L stainless steel high pressure polymerization reactor, nitrogen and ethylene were each replaced three times, then 200mL of hexane was added, the reactor was warmed to 80 ℃ and 800mL of hexane was added, 2mL of a 1mol/L Triethylaluminum (TEA) solution in hexane was added with the addition of hexane, then 0.5g of catalyst D1 was added, ethylene gas was introduced, the pressure was raised to 1.0MPa and maintained at 1.0MPa, and after 1 hour of reaction at 70 ℃, separation by suction filtration was carried out to obtain a polyethylene pellet powder. The Bulk Density (BD) of the polyethylene granular powder was 0.35g/mL and the melt index MI was measured_2.16The powder grinding rate is less than 3 percent when the powder is 0.5g/10 min. The efficiency of the catalyst was determined by calculation to be 1980g PE/gcat·h。

Experimental example 2

In a 2L stainless steel autoclave, each of which was replaced with nitrogen and ethylene three times, 200mL of hexane was added, the autoclave was warmed to 75 ℃ and 900mL of hexane was added, 2mL of a 1mol/L solution of Triethylaluminum (TEA) in hexane was added with the addition of hexane, 0.1g of catalyst D2 was added, ethylene gas was introduced, the pressure was raised to 1.0MPa and maintained at 1.0MPa, and the reaction was carried out at 75 ℃ for 1.5 hours, followed by separation by suction filtration to obtain a polyethylene pellet powder. The polyethylene granular powder obtained had a Bulk Density (BD) of 0.4g/mL and a melt index MI_2.16The powder grinding rate is less than 3 percent when the powder is 0.6g/10 min. The efficiency of the catalyst was determined by calculation to be 1924g PE/gcat h.

Experimental example 3

In a 2L stainless steel high pressure polymerization reactor, nitrogen and ethylene were each replaced three times, then 200mL of hexane was added, the reactor was warmed to 85 ℃ and 700mL of hexane was added, 2mL of a 1mol/L Triethylaluminum (TEA) solution in hexane was added with the addition of hexane, 1g of catalyst D3 was added, ethylene gas was introduced, the pressure was raised to 1.0MPa and maintained at 1.0MPa, and after reacting at 85 ℃ for 2 hours, the reaction mixture was separated by suction filtration to obtain a polyethylene pellet powder. The polyethylene granular powder obtained had a Bulk Density (BD) of 0.3g/mL and a melt index MI_2.16The powder grinding rate is less than 2.5 percent when the powder is 0.4g/10 min. The efficiency of the catalyst was determined by calculation to be 1912g PE/gcat h.

Experimental example 4

Polymerization of ethylene was carried out in accordance with the procedure of Experimental example 1, except that the same parts by weight of the catalyst D4 prepared in example 4 was used in place of the catalyst D1 prepared in example 1. The polyethylene pellet powder obtained had a Bulk Density (BD) of 0.31g/mL and a melt index MI_2.16＝0.41g10min, the crushing rate is less than 3 percent. The efficiency of the catalyst was determined by calculation to be 1790g PE/gcat h.

Experimental comparative example 1

Polymerization of ethylene was carried out in accordance with the procedure of Experimental example 1, except that the same parts by weight of comparative catalyst DD1 prepared in comparative example 1 was used in place of catalyst D1 prepared in example 1. The polyethylene granular powder obtained had a Bulk Density (BD) of 0.46g/mL and a melt index MI_2.16The powder grinding rate is less than 3 percent when the powder is equal to 0.72g/10 min. The efficiency of the catalyst was determined by calculation to be 1700g PE/gcat h.

Experimental comparative example 2

Polymerization of ethylene was carried out in accordance with the procedure of Experimental example 1, except that the same parts by weight of comparative catalyst DD2 prepared in comparative example 2 was used in place of catalyst D1 prepared in example 1. The polyethylene pellet powder obtained had a Bulk Density (BD) of 0.42g/mL and a melt index MI_2.16When the powder is equal to 0.64g/10min, the crushing rate is more than 7 percent. The efficiency of the catalyst was determined by calculation to be 1640g PE/gcat h.

Experimental comparative example 3

Polymerization of ethylene was carried out in accordance with the procedure of Experimental example 1, except that the same parts by weight of comparative catalyst DD3 prepared in comparative example 3 was used in place of catalyst D1 prepared in example 1. Polyethylene pellet powder obtained the Bulk Density (BD) of the polyethylene pellet powder was 0.63g/mL, and the melt index MI was_2.16When the powder is equal to 0.66g/10min, the crushing rate is more than 8 percent. The efficiency of the catalyst was found by calculation to be 1760g PE/gcat h.

From the results of comparing the above experimental examples 1 to 4 with the comparative examples 1 to 3, it can be seen that when the spherical diatomite mesoporous composite material and the supported catalyst provided by the present invention are used in ethylene polymerization reaction, the catalyst has high catalytic activity, and can obtain polyethylene products with low bulk density and melt index and difficult breakage, specifically, the prepared polyethylene has a bulk density of 0.4g/mL or less, a melt index of 0.6g/10min or less, and a breakage rate of not more than 3%.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. The spherical diatomite mesoporous composite material is characterized by comprising diatomite and a mesoporous molecular sieve material with a three-dimensional cubic cage-shaped pore channel structure, wherein the average particle size of the spherical diatomite mesoporous composite material is 30-60 micrometers, the specific surface area is 200-650 square meters/g, the pore volume is 2.1-3.5 milliliters/g, the pore diameter is in trimodal distribution, the three peaks respectively correspond to a first most probable pore diameter, a second most probable pore diameter and a third most probable pore diameter, the second most probable pore diameter is smaller than the third most probable pore diameter, the first most probable pore diameter is 3-10 nanometers, the second most probable pore diameter is 20-40 nanometers, and the third most probable pore diameter is 30-50 nanometers;

the preparation method of the spherical diatomite mesoporous composite material comprises the following steps:

wherein, in the step (3), the component b is used in an amount of 1-200 parts by weight, the diatomaceous earth is used in an amount of 1-100 parts by weight, and the binder is used in an amount of 1-10 parts by weight, relative to 100 parts by weight of the component a.

2. The spherical diatomite mesoporous composite material according to claim 1, wherein in the step (3), the component b is used in an amount of 50-200 parts by weight, the diatomite is used in an amount of 20-50 parts by weight, and the binder is used in an amount of 2-8 parts by weight, relative to 100 parts by weight of the component a.

3. The spherical diatomite mesoporous composite material according to claim 1, wherein the diatomite is contained in an amount of 1 to 100 parts by weight with respect to 100 parts by weight of the mesoporous molecular sieve material having a three-dimensional cubic cage-like pore structure.

4. The spherical diatomite mesoporous composite material according to claim 1, wherein the content of the diatomite is 20 to 50 parts by weight with respect to 100 parts by weight of the mesoporous molecular sieve material having a three-dimensional cubic cage-like pore structure.

5. A method for preparing a spherical diatomite mesoporous composite material comprises the following steps:

6. The method according to claim 5, wherein in the step (3), the component b is used in an amount of 1 to 200 parts by weight, the diatomaceous earth is used in an amount of 1 to 100 parts by weight, and the binder is used in an amount of 1 to 10 parts by weight, relative to 100 parts by weight of the component a.

7. The method according to claim 5, wherein in the step (3), the component b is used in an amount of 50 to 200 parts by weight, the diatomaceous earth is used in an amount of 20 to 50 parts by weight, and the binder is used in an amount of 2 to 8 parts by weight, relative to 100 parts by weight of the component a.

8. The method of claim 5, wherein the binder is polyvinyl alcohol and/or polyethylene glycol.

9. The method of claim 5, wherein the binder is polyvinyl alcohol.

10. The method of claim 5, wherein, in step (1), the process of preparing a filter cake of mesoporous molecular sieve material having a three-dimensional cubic cage pore structure comprises: in an acidic aqueous solution, in the presence of potassium sulfate, a template agent is contacted with a silicon source, and a mixture obtained after the contact is crystallized and filtered.

11. The method as claimed in claim 10, wherein the amount of potassium sulfate is 100-800 moles and the amount of silicon source is 20-200 moles with respect to 1 mole of the template.

12. The method of claim 10, wherein the templating agent is a triblock copolymer polyoxyethylene-polyoxypropylene-polyoxyethylene; the silicon source is at least one of ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, sodium orthosilicate and silica sol; the acidic aqueous solution is at least one aqueous solution of hydrochloric acid, sulfuric acid, nitric acid and hydrobromic acid.

13. The method of claim 10, wherein the conditions of the contacting comprise: the temperature is 25-60 ℃, the time is 10-72 hours, and the pH value is 1-7; the crystallization conditions include: the temperature is 90-150 ℃ and the time is 10-40 hours.

14. The method of claim 5, wherein, in the step (2), the process of preparing the filter cake of silica gel comprises: the water glass is contacted with the polyhydric alcohol in the presence of the mineral acid, and the mixture obtained after the contact is filtered.

15. The method of claim 14, wherein the conditions of the contacting comprise: the temperature is 10-60 ℃, the time is 1-5 hours, and the pH value is 2-4; the inorganic acid is at least one of sulfuric acid, nitric acid and hydrochloric acid; the polyalcohol is at least one of ethylene glycol, propylene glycol and glycerol.

16. The method of claim 14, wherein the polyol is ethylene glycol and/or glycerol.

17. The method of claim 14, wherein the weight ratio of the water glass, the inorganic acid, and the polyol is 3-6: 2-3: 1.

18. the method of any one of claims 5-10 and 14, wherein in step (3), the ball milling conditions comprise: the rotation speed of the grinding ball is 300-; the conditions of the spray drying include: the temperature is 150-600 ℃, and the rotating speed is 10000-15000 r/min.

19. The process according to any one of claims 5 to 9, wherein component a is a filter cake of a mesoporous molecular sieve material having a three-dimensional cubic cage-like pore structure, and component b is a filter cake of silica gel; the preparation method of the spherical diatomite mesoporous composite material further comprises the following steps: after the spray-drying process of step (3), the template is removed from the spray-dried product.

20. The method of claim 19, wherein the conditions to remove the templating agent comprise: the temperature is 90-600 ℃, and the time is 10-80 hours.

21. The spherical diatomite mesoporous composite prepared by the method of any one of claims 5-20.

22. A supported catalyst comprising a carrier and a magnesium salt and/or a titanium salt supported on the carrier, wherein the carrier is the spherical diatomaceous earth mesoporous composite according to any one of claims 1 to 4 and 21.

23. The catalyst according to claim 22, wherein the carrier is contained in an amount of 90 to 99% by weight, and the sum of the contents of the magnesium salt and the titanium salt is 1 to 10% by weight, based on the total weight of the supported catalyst, in terms of the magnesium element and the titanium element, respectively.

24. A method of preparing a supported catalyst, the method comprising: in the presence of inert gas, the carrier is soaked in mother liquor containing magnesium salt and/or titanium salt, and then is sequentially filtered and dried; wherein the carrier is the spherical diatomite mesoporous composite material according to any one of claims 1-4 and 21.

25. The method of claim 24, wherein the conditions of the impregnation comprise: the temperature is 25-100 ℃ and the time is 0.1-5 h.

26. The process of claim 24, wherein the carrier, magnesium salt and titanium salt are used in amounts such that the carrier is present in an amount of 90 to 99 wt%, and the sum of the amounts of the magnesium salt and the titanium salt, calculated as magnesium and titanium, respectively, is 1 to 10 wt%, based on the total weight of the catalyst, in the resulting supported catalyst.

27. A supported catalyst prepared by the process of any one of claims 24-26.