阅读说明：本技术 烷氧基镁载体及制备方法与含该载体的聚烯烃固体催化剂 (Alkoxy magnesium carrier, preparation method thereof and polyolefin solid catalyst containing same ) 是由 王仪森 李红明 高玉李 张蔚 义建军 雷珺宇 李荣波 于 2020-05-08 设计创作，主要内容包括：本发明公开了一种烷氧基镁载体及制备方法与含该载体的聚烯烃固体催化剂。该制备方法包括以下步骤：在硅氧烷存在条件下,以卤素单质和/或含卤素化合物的至少一种引发金属镁与醇进行反应,得到所述烷氧基镁载体。所得到的烷氧基镁载体颗粒具有更加窄的粒度分布(小于1),较高的堆积密度、良好的颗粒形态。(The invention discloses an alkoxy magnesium carrier, a preparation method thereof and a polyolefin solid catalyst containing the same. The preparation method comprises the following steps: in the presence of siloxane, metal magnesium and alcohol are reacted by at least one of elementary halogen and/or halogen-containing compounds to obtain the alkoxy magnesium carrier. The obtained alkoxy magnesium carrier particles have narrower particle size distribution (less than 1), higher bulk density and good particle morphology.)

1. A preparation method of an alkoxy magnesium carrier comprises the following steps:

in the presence of siloxane, metal magnesium and alcohol are reacted by at least one of elementary halogen and/or halogen-containing compounds to obtain the alkoxy magnesium carrier.

2. The method of claim 1, wherein the siloxane is selected from the group consisting of those of the formula R¹ _nSi(OR²)_(4-n)One or a combination of two or more of the compounds of (a);

wherein n is 0, 1 or 2;

R¹selected from C1-6 straight chain or branched chain alkyl and aryl; when n is 2, two R¹The same or different;

R²selected from methyl or ethyl; (4-n) R²The same or different.

3. The method according to claim 1, wherein the siloxane is one or a combination of two or more of tetraethoxysilane, methylphenyldimethoxysilane, tetramethoxysilane, and propyltriethoxysilane.

4. The production method according to claim 3, wherein the siloxane is tetraethoxysilane.

5. The production method according to any one of claims 1 to 4, wherein the siloxane is added in an amount of (0.001 to 1) times equivalent to that of metallic magnesium; preferably (0.005 to 1) times equivalent, more preferably (0.01 to 1) times equivalent.

6. The production method according to claim 1, wherein the elemental halogen is selected from elemental chlorine, elemental bromine, or elemental iodine; said halogen-containing compound is selected from MgCl₂、Mg(OEt)Cl、Mg(OEt)I、MgBr₂、CaCl₂NaCl or KBr.

7. The production method according to claim 6, wherein the elemental halogen is elemental iodine, and the halogen-containing compound is magnesium chloride.

8. The production process according to claim 1, 6 or 7, wherein the molar amount of the total halogen in the reaction system is (0.0001 to 1) times that of the metallic magnesium; preferably (0.0005 to 1) times, more preferably (0.001 to 1) times.

9. The method according to claim 1, wherein the alcohol is a C1-6 alcohol; ethanol is preferred.

10. The production method according to claim 1 or 9, wherein the molar amount of the alcohol is 4 times or more that of the metallic magnesium; preferably 4-10 times.

11. The production method according to claim 1, wherein the metallic magnesium and the alcohol are added to the reaction system in portions to carry out the reaction.

12. The method of claim 11, wherein the time interval of the batch addition is 10 minutes to 120 minutes.

13. The production method according to claim 11 or 12, wherein the magnesium metal and the alcohol are added to the reaction system in their entirety and no H is present₂After the generation, the reaction system is subjected to aging treatment at a temperature of from 70 ℃ to the reflux temperature of the alcohol.

14. The magnesium alkoxide carrier obtained by the process as set forth in any one of claims 1 to 13, wherein the magnesium alkoxide carrier has a particle size distribution represented by (D90-D10)/D50 of less than 1; preferably less than 0.8, more preferably less than 0.6.

15. A polyolefin solid catalyst comprising the magnesium alkoxide support of claim 14.

Technical Field

The invention relates to the field of polyolefin catalysts, in particular to an alkoxy magnesium carrier, a preparation method thereof and a polyolefin solid catalyst containing the carrier.

Background

At present, olefin polymerization catalysts are still based on Ziegler-Natta catalysts. The magnesium chloride supported Ziegler-Natta catalyst is typically a solid catalyst component consisting of magnesium, titanium, halogen and an electron donating organic compound. When used in the polymerization of α -olefins, such as propylene, it may be mixed and used with an organoaluminum compound as a cocatalyst and an organosilane compound as a stereoregularity modifier in an appropriate ratio. The Ziegler-Natta catalyst taking the alkoxy magnesium as the carrier has the unique advantages of good hydrogen regulation sensitivity, good copolymerization performance and the like, and is widely applied to a gas-phase polypropylene process copolymerization brand and a slurry polyethylene process bimodal brand; and when the solid catalyst component is used for olefin polymerization, the polymer has a 'renaturation' effect, and the particle performance of the carrier/solid catalyst component directly determines the particle performance of polymer powder. The requirements of the polymerization process for the particle properties of the polymer powder can be met by developing a carrier/solid catalyst component of suitable particle properties. The existing industrial polymerization apparatuses such as a slurry polyethylene process, a bulk polypropylene process, a gas phase polypropylene process require polymer powder having a suitable particle size, a uniform particle size distribution, (a minimum amount of large particles or fine particles) and a high bulk density, etc. Technical solutions in this respect are disclosed in patent documents such as CN201510716358.9, CN201510717138.8, CN201510684825.4, CN201410273530.3, CN201210397456.7, CN201110270295.0, CN201110197236.5, and CN 98118334.4.

The preparation method of dialkoxy magnesium particles is mainly disclosed as follows: firstly, reacting alcohol with metal magnesium to generate dialkoxy magnesium, and then adjusting the particle size by mechanical crushing; a production method in which the final ratio of magnesium to ethanol is controlled to be 1/9 to 1/15 when magnesium metal reacts with ethanol, and ethanol and magnesium react intermittently or continuously during ethanol reflux (JP3772331B 2); thirdly, a process for producing fine round particles by spray-drying an alcoholic solution of carboxylated magnesium and successively decarboxylating the solution (JP2545076B 2. all of the above processes can produce alkoxymagnesium particles having an adjustable particle size and a high bulk density, but the particle size distribution span ((D90-D10)/D50) is generally larger than 1, the distribution is broad, and the contents of large particles and fine particles are expected to be further reduced. patent application CN201280050513.2 discloses a process for producing alkoxymagnesium particles having a small particle size, a narrow particle size distribution, a spherical shape or an ellipsoidal shape, in which at least one of halogen or halogen atom-containing compound, metallic magnesium and alcohol are added to a reaction system under alcohol reflux in portions to react the alkoxymagnesium, wherein the reaction system is added with at least one of halogen or halogen atom-containing compound, a mixture of metallic magnesium and alcohol at each time of the addition in portions, but the process requires a plurality of additions of halogens such as elemental iodine, resulting in higher halogen addition, increased manufacturing costs, and more stringent washing conditions to remove excess halogen.

Disclosure of Invention

The invention aims to provide an alkoxy magnesium carrier, a preparation method thereof and a polyolefin solid catalyst containing the carrier. The carrier has narrower particle size distribution, higher bulk density and good particle morphology.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of an alkoxy magnesium carrier comprises the following steps:

and (2) in the presence of siloxane, initiating the reaction of the metal magnesium and the alcohol by at least one of halogen and/or halogen-containing compounds to obtain the alkoxy magnesium carrier.

The alkoxy magnesium carrier obtained by the preparation method is spherical or ellipsoidal particles, and the particle size distribution of the alkoxy magnesium carrier is less than 1. Wherein the particle size distribution is represented by (D90-D10)/D50, and D10, D50 and D90 represent particle sizes at which the cumulative particle sizes are 10%, 50% and 90%; for example, D10 refers to the particle size when the cumulative mass of the particulates is 10 wt.% as measured by the particle size distribution of the particulates; d50 represents the median value of the particle diameters of all the pellets, and this value represents the average particle diameter.

In one embodiment of the invention, the siloxane is selected from the group consisting of those of the formula R¹ _nSi(OR²)_(4-n)One or a combination of two or more of the compounds of (a); wherein n is 0, 1 or 2; r¹Selected from C1-6 straight chain or branched chain alkyl and aryl; when n is 2, two R¹May be the same or different; r²Selected from methyl or ethyl; (4-n) R²May be the same or different. Such as phenyl, substituted phenyl, and the like.

Specifically, when n is 0, 4R²May be the same, e.g. both methyl or ethyl, or may be different, e.g. at least one is methyl or at least one is ethyl; when n is 1, R²Is C1-6 linear or branched alkyl, for example, any one selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, cyclopentyl and cyclohexyl, 3R²May be the same or different and is selected from either or both of methyl and ethyl; when n is 2, 2R¹The groups may be the same or different, and are selected from any one or two of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, cyclopentyl and cyclohexyl, and 2R are²The alkyl group may be the same or different and is selected from either or both of a methyl group and an ethyl group.

In the preparation method, siloxane is beneficial to the formation and growth of alkoxy magnesium microcrystals, so that the growth process of the microcrystals and the chemical reaction process of alcohol/magnesium are more synchronous, the growth periods of different alkoxy magnesium particles are more concentrated, and the particle size distribution of the alkoxy magnesium particles is more concentrated. The presence of siloxane helps to concentrate the distribution of the magnesium alkoxide particles, but it does not participate in the alcohol/magnesium reaction process, and residual siloxane on the surface of the magnesium alkoxide particles will be removed in the subsequent washing step. In order to ensure the technical effect of the invention, the addition amount of the siloxane is preferably controlled to be (0.001-1) time equivalent of the metal magnesium; preferably (0.005 to 1) times equivalent, more preferably (0.01 to 1) times equivalent.

The magnesium metal used in the production method of the present invention may have any shape, for example, any shape of granular, ribbon, or powder, as long as it has good reactivity. From the viewpoint of reactivity, metallic magnesium whose surface oxidation degree is as low as possible is preferable, and for example, metallic magnesium stored in an atmosphere of an inert gas such as nitrogen, metallic magnesium whose surface is treated with a solvent or the like which does not affect the reaction to prevent surface oxidation, and the like are preferable. There is no particular requirement for the particle size of the metallic magnesium, and magnesium powder having an average particle size of 200 to 40 mesh is preferable from the viewpoint of controlling the reaction rate.

In the preparation method of the present invention, the kind of the simple substance halogen is not particularly limited, and the simple substance chlorine, the simple substance bromine or the simple substance iodine is preferable, and the simple substance iodine is particularly preferable. The kind of the halogen-containing compound is not limited, and any halogen-containing compound may be used as long as it contains a halogen atom in its chemical formula. Specifically, MgCl can be exemplified₂、Mg(OEt)Cl、Mg(OEt)I、MgBr₂、CaCl₂NaCl, KBr, etc., and MgCl is preferably used among them₂、MgI₂. The state, shape, particle size and the like of the halogen or halogen atom-containing compound added to the reaction system are not particularly limited, and may be any. For example, the solvent may be used in the form of a solution dissolved in an alcohol solvent such as ethanol.

In one embodiment of the present invention, the halogen is elemental iodine and the halogen-containing compound is magnesium chloride; the magnesium chloride is preferably anhydrous magnesium chloride.

In the production method of the present invention, 1 kind of halogen and 2 or more kinds of halogen-containing compounds are used alone or in combination, respectively. In addition, a halogen and a halogen-containing compound may be used in combination. The amount of the halogen and/or the halogen-containing compound used is not particularly limited as long as the amount is sufficient for the reaction between the metallic magnesium and the alcohol, and the molar amount of all halogen atoms in the reaction system is (0.0001 to 1) times that of the metallic magnesium at the time of completion of addition of all the raw materials to the reaction system; preferably (0.0005 to 1) times, more preferably (0.001 to 1) times. The reaction system is understood by those skilled in the art to mean a system for carrying out a reaction, including all raw materials and catalysts, solvents, etc. for carrying out the reaction.

In the production method of the present invention, the alcohol to be used may be any alcohol, and preferably C1-6 alcohol is used. In particular, if ethanol is used, an ethoxymagnesium support is obtained, and the performance of a catalyst prepared therefrom is remarkably improved, and thus it is preferable.

The purity and water content of the alcohol are not particularly limited, and an alcohol having a small water content is preferable. Specifically, an alcohol having a water content of 1% or less is preferably used, and an alcohol having a water content of 2000ppm or less is more preferably used. When an alcohol having a large water content is used, magnesium hydroxide tends to be easily formed on the surface of metal magnesium. In order to obtain a magnesium alkoxide having a more favorable form, it is preferable that the amount of water in the alcohol is as small as possible, and in general, 200ppm or less is preferable.

In the production method of the present invention, the molar ratio of the amount of the alcohol added to the reaction system to the metallic magnesium should be more than 4, preferably between 4 and 10. Too little alcohol is added, the reaction of the metal magnesium is insufficient, unreacted magnesium is mixed in the product, too much alcohol is added, particles with out-of-control shapes are easily generated, and the preparation cost is increased.

In the preparation method of the present invention, the halogen simple substance and/or the halogen-containing compound may be added to the reaction system at a single time or may be added in portions.

In the preparation method of the present invention, the metal magnesium and the alcohol may be added to the reaction system in a single time or in batches, but in the single addition, the metal magnesium and the alcohol in the reaction system have a large instantaneous amount, so the reaction is relatively violent, and the reaction liquid in the reactor is easy to splash and generate coalesced heterotype alkoxy magnesium particles, so the batch addition is a preferable feeding mode. The mass ratio of the metallic magnesium to the alcohol to be added in portions is not particularly limited, and may be different or the same for each addition in portions. For example, the magnesium metal may be added in such a manner that the ratio of magnesium metal is higher than the final addition ratio in the initial stage of the reaction and the ratio of magnesium metal is decreased in the latter half.

In the production method of the present invention, the interval of the batch addition varies depending on other conditions such as the size and temperature of the reaction apparatus, and preferably 10 to 120 minutes. That is, it is preferable that the magnesium alkoxide is generated by the reaction after the batch addition in the previous stage, and H is₂The subsequent raw material is added at a stage where the generation of (1) is almost completed (a stage where unreacted metallic magnesium hardly remains). Preferably, magnesium is added after the addition at the point when the reaction of the added magnesium is almost completed, and preferably, magnesium is added so that the molar mass ratio of the final alcohol to the metallic magnesium is in the range of more than 4.

In the preparation method of the invention, the metal magnesium and the alcohol are all added into the reaction system, and no H is left₂After the generation, the reaction system is subjected to aging treatment at a temperature of from 70 ℃ to the reflux temperature of the alcohol. The aging treatment is not less than 0.5 hour to promote structural stabilization of the resultant magnesium alkoxide particles.

After the above-mentioned aging treatment is completed, the obtained magnesium alkoxide carrier particles are preferably washed with an inert solvent to remove unnecessary compounds such as siloxane, halogen compounds and the like from the surfaces of the particles, and a part of fine powder adhering to the surfaces of the carrier particles can also be removed by the washing step. The detergent used in the washing step is not particularly limited, and any inert solvent which is insoluble or slightly soluble in the magnesium alkoxide compound and can remove the siloxane and halogen compounds is acceptable. By way of example, but not limitation, ethanol, hexane, isopentane, heptane, and the like. The amount of the detergent to be used and the number of washing operations are not particularly limited, and the washing operations can be carried out by a conventional washing method in the art.

The alkoxy magnesium carrier obtained by the preparation method of the invention has narrow particle size distribution and high bulk density, is in a spherical or ellipsoidal particle form, and is particularly suitable for preparing the polyolefin solid catalyst component.

In another aspect of the present invention, there is provided an alkoxy magnesium carrier obtained by the above preparation method; the particle size distribution of the alkoxy magnesium carrier expressed by (D90-D10)/D50 is less than 1; preferably less than 0.8 and most preferably less than 0.6.

In still another aspect of the present invention, there is provided a polyolefin solid catalyst component comprising the above magnesium alkoxide support.

When the magnesium alkoxide support of the present invention is used as a starting material for producing a solid catalyst for polyolefin, the magnesium alkoxide support of the present invention is contacted with a halide of titanium having a valence of 4 and an electron donating compound by a known method to produce a catalyst, and an organoaluminum compound is allowed to act thereon. Among them, examples of the halide of the 4-valent titanium include titanium tetrachloride, alkoxy titanium halide, and the like; examples of the electron-donating compound include organic silicon compounds such as alcohols, ethers, esters, and alkoxysilanes; examples of the aluminum compound include triethylaluminum and diethylaluminum chloride.

When the polyolefin solid catalyst prepared by the alkoxy magnesium carrier is used for olefin polymerization, an olefin polymer with controlled particle size distribution, particle size and particle type can be obtained.

Drawings

FIG. 1 is a graph showing a distribution of particle diameters of the magnesium alkoxide carrier obtained in example 1.

FIG. 2 is a graph showing a distribution of particle diameters of the magnesium alkoxide carrier obtained in comparative example 1.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The bulk density, particle size and distribution index (span) of the magnesium alkoxide support of the present invention are determined as follows:

(1) bulk density:

a quantity of magnesium alkoxide carrier is loosely added to a fixed volume container and the container tared on a balance to obtain the weight of the magnesium alkoxide (in grams, two decimal places are recorded).

Bulk density is the measured weight/measured volume; the unit is g/cm³(ii) a Arithmetic averaging the two measured valuesAll are recorded as the measurement results.

(2) Particle size distribution:

using a Malvern Mastersizer^TM2000 measuring the particle size of the alkoxy magnesium; average particle size (D50): particle size corresponding to 50% cumulative weight; span ═ D90-D10/D50 was used to characterize the degree of uniformity of the particle size distribution.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1

This example prepares a narrow distribution magnesium ethoxide by the following procedure:

a reflux condenser pipe, a thermometer and a burette are arranged in the reactor with the stirrer, a guide pipe is connected above the reflux condenser pipe, and the other end of the guide pipe is connected with an oil seal device to facilitate observing H₂Is generated.

After the reaction system is fully filled with nitrogen for replacement, 60mL of absolute ethyl alcohol (water content is 50ppm) is filled, stirring is started, and 0.9g of iodine and 0.5g of tetraethoxysilane are continuously added for dissolution; charging metal magnesium 4g (granularity 300-; the reaction is stabilized within 10 minutes from the loading of the metal magnesium, then 40mL of ethanol and 4g of metal magnesium are loaded into the reaction kettle for 1 time and 3 times every 15 minutes, the total loading amount of the metal magnesium is 16g, and the usage amount of the ethanol is 180 mL; then 100mL of ethanol with the same quality as the previously used ethanol is added dropwise for 1 hour, the reaction is continued until no hydrogen is generated, and then the curing reaction is continued for 1 hour; wherein the molar ratio of the total amount of ethanol charged into the reaction system to the total amount of the metal magnesium is 7.3.

After the completion of the reaction, the liquid in the reaction system was dried under reduced pressure by a rotary evaporator to obtain 71g of white ethoxymagnesium particles, the particle size distribution of which is shown in FIG. 1, and the particle size distribution Span value was 0.647 and the particle size was very narrow.

The ethoxymagnesium white particles had a D50 of 34.47 μm, a D10 of 24.76 μm, a D90 of 47.12 μm, and a particle size distribution (Span) of 0.647. The bulk density was measured to be 0.34 g/mL. The results are shown in Table 2.

Examples 2 to 5

The procedure of example 1 was repeated except that the numerical values corresponding to the conditions used in example 1 were changed to the numerical values shown in table 1. The results are shown in Table 2. In table 1, "Mg" represents magnesium, "I" represents iodine, and "the number of times" of batch addition "represents the number of times of batch addition of metallic magnesium.

Comparative example 1

The reaction was carried out under the same conditions as in example 1, except that no siloxane was added in the reaction. The results are shown in Table 2.

The particle size distribution of the obtained magnesium ethoxide is shown in fig. 2, and the particle size distribution Span value is 1.248, which is wider than that of example 1.

TABLE 1 Experimental conditions for examples 1-6 and comparative example 1

TABLE 2 results of ethanol/magnesium metal test obtained in examples 1-6 and comparative example 1

As can be seen from Table 2, the size distribution of the magnesium ethoxide carrier obtained by the preparation method of the invention is significantly narrowed, and the magnesium ethoxide carrier has higher bulk density and meets the requirements of polyolefin catalyst preparation.

The present invention can provide magnesium alkoxide particles having controlled particle size distribution, particle size, and particle shape, and having a quality which has not been achieved in the past.

When the polyolefin solid catalyst component prepared by the alkoxy magnesium carrier is used for olefin polymerization, an olefin polymer with controlled particle size distribution, particle size and particle type can be obtained. As described above, the production method and the magnesium alkoxide carrier of the present invention are extremely useful industrially.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.