CN115558043A - A kind of polyolefin catalyst and its application - Google Patents

Abstract

The invention relates to a polyolefin catalyst, which takes composite cellulose as a carrier and a metallocene complex as an active component, wherein the composite cellulose is prepared by the following method: adding a solvent into the dried cellulose powder under the protection of inert gas to disperse the cellulose powder into a suspension, continuously adding alkyl aluminoxane into the suspension under the condition of stirring to react, and then distilling the mixture under reduced pressure under the condition of isolating air to obtain the composite cellulose. The invention also relates to the use of the above polyolefin catalyst in the homogeneous polymerization or copolymerization of olefins, and in the gas phase polymerization or slurry polymerization of olefins. The polyolefin product produced by the polyolefin catalyst provided by the invention can be used for preparing cellulose-reinforced polyethylene or polypropylene resin composite materials, and the cellulose component is not only a carrier material, but also a reinforcing component in the final composite material, so that carriers such as inorganic salt, silica gel and the like do not become ash which is difficult to remove in the polyolefin resin material finally.

Description

A kind of polyolefin catalyst and its application

technical field

The invention relates to the field of polyolefin catalysis, in particular to a polyolefin catalyst and its application in the homogeneous polymerization or copolymerization of olefins, and in the gas phase polymerization or slurry polymerization of olefins.

Background technique

Metallocene catalysts are a pioneering discovery after Ziegler-Natta catalysts, which have high catalytic activity, single active center, narrow molecular weight distribution of polymer products, and the ability to control the performance of polymer products by adjusting catalyst ligands. When metallocene catalysts are used, they need to consume a large amount of alkylaluminoxane and produce amorphous products. Therefore, it is necessary to carry out supporting treatment on metallocene catalysts to reduce the cost of use and control the shape of polymer products.

At present, there are many research reports on metallocene catalyst support, and some of them have been put into production. Among them, materials such as silicon dioxide and magnesium chloride are used as carriers. Although the above methods are effective, the cost of carrier preparation is high, the process is complicated, and the produced polyolefin products are introduced with inorganic impurities that are difficult to remove.

Due to the increasingly urgent demand for environmental protection and the stricter relevant laws and regulations, cellulose materials have gradually received more attention and developed in high-end applications. Among them, polypropylene composite materials reinforced with cellulose materials are one of the current research and development hotspots. one. However, the compatibility between cellulose materials and polypropylene or polyethylene materials is poor, and the performance improvement of composite materials obtained by mixing the two through simple ball milling is not obvious, and the energy consumption is large, and it is not easy to scale up to achieve industrial mass production; while the cellulose materials Although chemical pretreatment to improve its compatibility with polypropylene materials is effective, it brings unnegligible cost increases and environmental pollution problems during the process of scaling up.

Contents of the invention

Based on the above, one of the objectives of the present invention is to propose a polyolefin catalyst, with metallocene complexes as the active component and cellulose carrier as the carrier, which has a wide range of sources of cellulose materials, low production costs, and easy regulation of product morphology. The particle morphology of supported metallocene catalysts can be controlled.

The second object of the present invention is to provide a method for preparing the above-mentioned polyolefin catalyst.

The third object of the present invention is to provide the application of the above-mentioned polyolefin catalyst in the homogeneous polymerization or copolymerization of olefins, and in the gas phase polymerization or slurry polymerization of olefins.

For this reason, the present invention provides a kind of polyolefin catalyst, take composite cellulose as carrier, take metallocene complex as active component, described composite cellulose is to make by following method: the cellulose powder after drying, Under the protection of an inert gas, add a solvent to disperse into a suspension, continue to add alkyl aluminoxane to react under the condition of stirring, and then conduct vacuum distillation under the condition of cutting off the air to obtain the composite cellulose.

Specifically, the metallocene complex may be all current metallocene complex catalysts capable of catalyzing polyolefins.

In the polyolefin catalyst described in the present invention, preferably, the drying process of the cellulose powder is: vacuum drying the cellulose powder at 45-55° C. for 24-48 hours.

In the polyolefin catalyst described in the present invention, preferably, the conditions of the reaction are: 20-30° C. for 3-5 hours.

In the polyolefin catalyst of the present invention, preferably, the alkyl aluminoxane is methyl aluminoxane, ethyl aluminoxane or derivatives thereof that also have the function of a polyolefin co-catalyst; the metallocene The complex is a metallocene complex with polyolefin catalysis.

In the polyolefin catalyst of the present invention, preferably, the process of loading the metallocene complex on the composite cellulose is: adding the composite cellulose to the solvent under stirring conditions, and adding the composite cellulose dropwise After reacting the solution containing the metallocene complex to obtain a dispersion liquid, the dispersion liquid is distilled under reduced pressure under the condition of cutting off air to obtain the polyolefin catalyst.

In the polyolefin catalyst described in the present invention, preferably, the conditions of the reaction are: 20-30° C. for 3-5 hours.

The polyolefin catalyst of the present invention, wherein preferably, the diameter of the cellulose powder is nanometer and/or micrometer, the cellulose powder contains lignin and hemicellulose, and its purity is above 40wt%; Further preferably, the cellulose powder has been chemically modified in advance.

In the polyolefin catalyst of the present invention, preferably, the color of the cellulose powder can be white, yellow or brown, and its source can be bacteria or plants.

The polyolefin catalyst of the present invention, wherein preferably, in the polyolefin catalyst, the molar ratio of the aluminum element to the metal element of the metallocene complex is 40 to 100; more preferably, the polyolefin catalyst is directly used or Use after mixing with industrial white oil.

In the polyolefin catalyst of the present invention, preferably, the inert gas is nitrogen, helium or argon, and the solvent is toluene or hexane.

For this reason, the present invention also provides a kind of preparation method of polyolefin catalyst, comprises the following steps: under the protection of inert gas, add above-mentioned composite cellulose into solvent and mix, then slowly drop the solution of metallocene complex, in 20- The reaction is carried out at 30°C for 3-5 hours, and the dispersion obtained by the reaction is distilled under reduced pressure under the condition of cutting off the air to obtain a composite cellulose-supported metallocene catalyst.

In the preparation method of the polyolefin catalyst of the present invention, preferably, the solvent is toluene or hexane.

For this reason, the present invention also provides the application of a kind of above-mentioned polyolefin catalyst in homogeneous polymerization or copolymerization of olefin, and the gained polyolefin can be made into the additive component that is used to make cellulose reinforced polypropylene or polyethylene material, It can overcome the problem of poor compatibility faced by directly using cellulose materials to reinforce polypropylene or polyethylene materials at present, and avoid the negative effect that it will eventually become ash when inorganic salts, silica gel, etc. are used as carrier materials.

To this end, the present invention also provides an application of the above-mentioned polyolefin catalyst in the gas phase polymerization or slurry polymerization of olefins.

Concrete, the preparation method of polyolefin catalyst of the present invention, comprises the following steps:

Step 1, cellulose pretreatment: vacuum-dry the cellulose powder at 45-55°C for 24-48 hours to fully dry it;

Step 2, preparation of cellulose carrier: under the protection of inert rare gas, add the dry cellulose powder obtained in (1) into the reactor, add a solvent to disperse into a suspension, continue to add alkyl aluminoxane, 20-30 Stirring and reacting at ℃ for 3-5 hours; then distilling under reduced pressure in the absence of air to obtain a cellulose carrier containing alkyl aluminoxane;

Step 3, catalyst preparation: under the protection of an inert gas, add the cellulose carrier prepared in (2) to the solvent and apply mechanical stirring, slowly add the metallocene catalyst solution dropwise, and react at 20-30°C for 3 -5 hours, and finally the dispersion liquid was distilled under reduced pressure under the condition of cutting off the air to obtain a cellulose-supported metallocene catalyst solid.

The chemical structure of the cellulose material selected in the present invention is similar to that of silica in that there are a large number of hydroxyl groups on the surface of the material, so it can realize the loading of metallocene catalysts like a silica carrier, and realize polymerization during the polymerization process. Acrylic material covering. This operation not only avoids the chemical pretreatment of cellulose, but also reduces the difficulty of mixing the cellulose material with the polypropylene material. The polypropylene powder coated with the cellulose material can be mixed with the polypropylene powder/ The pellets are mixed and can be further processed to produce reinforced polypropylene or polyethylene composites containing a certain amount of cellulosic material.

The beneficial effects of the present invention are:

(1) The commercialized cellulose material has rich particle morphology and high selectivity, so the catalyst particle shape after loading is also easy to control; meanwhile, the cellulose material is cheap, which can reduce the preparation cost of the supported metallocene catalyst.

(2) The loaded metallocene catalyst obtained by this method can be used to catalyze the copolymerization reaction of propylene or ethylene, and the powder produced can be used to prepare cellulose-reinforced polyethylene or polypropylene resin composite materials, thereby avoiding this type of Poor compatibility of composite materials and the need to chemically modify pretreatment of cellulose materials. At the same time, the cellulose component is not only the carrier material, but also the reinforcing component in the final composite material, and the carrier such as inorganic salt and silica gel will not eventually become the ash that is difficult to remove in the polyolefin resin material.

(3) The cellulose material-supported metallocene catalyst of the present invention can be used in gas-phase polymerization process and slurry polymerization process, and can meet the requirements of different polymerization processes.

detailed description

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are provided, but the protection scope of the present invention is not limited to the following embodiments, the following The experimental method that does not indicate specific condition in the embodiment, generally according to routine condition. The percentages involved in the following examples are all mass percentages.

The polyolefin catalyst provided by the present invention uses composite cellulose as a carrier and a metallocene complex as an active component. The composite cellulose is prepared by the following method: the dried cellulose powder is placed under the protection of an inert gas Add a solvent to disperse into a suspension, continue to add alkyl aluminoxane to react under the condition of stirring, and then distill under reduced pressure under the condition of cutting off the air to obtain composite cellulose.

In some embodiments, preferably, the drying process of the cellulose powder is: vacuum drying the cellulose powder at 45-55° C. for 24-48 hours.

In some embodiments, preferably, the conditions of the reaction are: 20-30° C. for 3-5 hours.

In some embodiments, it is preferred that the alkylaluminoxane is methylalumoxane, ethylalumoxane or derivatives thereof that also have the function of polyolefin cocatalyst; the metallocene complex is Metallocene complexes for polyolefin catalysis.

In some embodiments, preferably, the process of loading the metallocene complex on the composite cellulose is: adding the composite cellulose to the solvent under stirring conditions, adding the metallocene complex dropwise The solution of the metal complex is post-reacted to obtain a dispersion liquid, and the dispersion liquid is distilled under reduced pressure under the condition of cutting off air to obtain the polyolefin catalyst.

In some embodiments, preferably, the conditions of the reaction are: 20-30° C. for 3-5 hours.

In some embodiments, preferably, the diameter of the cellulose powder is nanoscale and/or micron, the cellulose powder contains lignin, hemicellulose, and its purity is above 40wt%; more preferably, The cellulose powder is chemically modified in advance.

In some embodiments, preferably, in the polyolefin catalyst, the molar ratio of the aluminum element to the metal element of the metallocene complex is 40-100; more preferably, the polyolefin catalyst is directly used or mixed with industrial white oil used later.

In some embodiments, preferably, the inert gas is nitrogen, helium or argon, and the solvent is toluene or hexane.

The preparation method of the polyolefin catalyst provided by the present invention comprises the following steps: under the protection of an inert gas, adding the above-mentioned composite cellulose into a solvent for mixing, then slowly adding the solution of the metallocene complex dropwise, and reacting at 20-30°C After 3-5 hours, the dispersion liquid obtained by the reaction is distilled under reduced pressure under the condition of cutting off the air to obtain the metallocene catalyst supported by composite cellulose.

In some embodiments, preferably, the solvent is toluene or hexane.

The present invention also provides the application of the above-mentioned polyolefin catalyst in the homogeneous polymerization or copolymerization of olefins.

The present invention also provides the application of the above-mentioned polyolefin catalyst in the gas phase polymerization or slurry polymerization of olefins.

Example 1

(1) Vacuum-dry cellulose whisker powder with a purity of not less than 98%, white, sourced from coniferous wood, about 30 nanometers in diameter and about 500 nanometers in length at 50°C for 24 hours to fully dry. Afterwards, it was stored under the protection condition of nitrogen atmosphere until use.

(2) Under the condition of nitrogen protection, add 10 g of dried cellulose powder obtained in step (1) into the reactor, and add the solvent toluene to disperse into a suspension. The ratio of use is 1 g of cellulose powder: 100 mL of toluene; continue to add 300 ml of 10% methylaluminoxane toluene solution was stirred and reacted at room temperature for 4 hours, and then distilled under reduced pressure in the absence of air to obtain a cellulose carrier containing methylaluminoxane.

(3) Under the condition of nitrogen protection, 5 g of the cellulose carrier containing methylaluminoxane prepared in step (2) was added to toluene and mechanically stirred, and 0.2 g of the metallocene complex (Cp ₂ ZrCl ₂ ) was dissolved in 20mL of toluene, and then slowly added dropwise to the reactor. The reaction was carried out at room temperature for 3 hours, and finally the dispersion liquid was washed with toluene and dried in vacuum under the condition of being isolated from air to obtain a solid metallocene catalyst supported on cellulose.

The resulting solid can be used directly or mixed with industrial white oil. Characterized by ICP, the weight content of Zr in the prepared catalyst is 0.67%, and the weight content of Al is 7.2%. The particle size of the supported catalyst is not greater than 1 micron.

(4) After purging the 5L autoclave with nitrogen and removing impurities with triethylaluminum, feed propylene at 35°C to a pressure of 1.0 MPa, then add 0.2 g of the prepared supported metallocene catalyst, and pass through again Add propylene until the pressure of the reactor is 2.0MPa, and polymerize at 60°C for 1 hour. Catalyst activity and polymer molecular weight are shown in Table 1.

Example 2

Use white, source is the microcrystalline cellulose powder of cotton linters, particle diameter is about 30 microns to replace cellulose whisker powder, protective gas uses helium, all the other are the same as embodiment 1.

The obtained catalyst has a Zr weight content of 0.60% and an Al weight content of 6.9%. The supported catalyst particle size is about 30 microns. Catalyst activity and polymer molecular weight are shown in Table 1.

Example 3

Use light yellow, source is broad-leaved wood, micron-scale wood powder with a particle size of about 40 microns to replace the cellulose whisker powder, the protective gas uses argon, and the rest are the same as in Example 1.

The obtained catalyst has a Zr weight content of 0.71% and an Al weight content of 3.5%. The supported catalyst particle size is about 40 microns. See Table 1 for activities and polymer molecular weights.

Example 4

Use milky white, hydroxyethyl cellulose powder with a molar substitution degree of 1.8-2.0 and a particle size of about 80 microns to replace the cellulose whisker powder, and use it after vacuum drying at 55°C for 48 hours, and the rest are the same as in Example 1.

The obtained catalyst has a Zr weight content of 0.63% and an Al weight content of 2.9%. The supported catalyst particle size was about 85 microns. See Table 1 for activities and polymer molecular weights.

Table 1 Catalyst activity and polymer molecular weight distribution

Activity (gPE/g cat.H) M_w/M_n Example 1 770 1.55 Example 2 671 1.34 Example 3 455 1.67 Example 4 326 1.85

It can be seen from Table 1 that the commercial cellulose material particles have rich morphology and high selectivity, so the catalyst particle morphology after loading is also easy to control. At the same time, the cellulose material is cheap, which can reduce the preparation cost of the supported metallocene catalyst. The supported metallocene catalyst obtained by the method can be used to catalyze the copolymerization reaction of propylene or ethylene, and the powder produced can be used to prepare cellulose-reinforced polyethylene or polypropylene resin composite materials, thereby avoiding the disadvantages of this type of composite materials. Poor compatibility and the need for chemically modified pre-treatments of the cellulosic material, while the cellulosic component will end up as a reinforcing component rather than as ash. The cellulose material-supported metallocene catalyst described in the present invention can be used in gas phase polymerization process and also in slurry polymerization process to meet the requirements of different polymerization processes.

Certainly, the present invention also can have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes And deformation should belong to the protection scope of the present invention.

Claims (11)

1. a polyolefin catalyst, it is characterized in that, take composite cellulose as carrier, take metallocene complex as active component, described composite cellulose is made by following method: the cellulose powder after drying, Under the protection of an inert gas, add a solvent to disperse into a suspension, continue to add alkyl aluminoxane to react under the condition of stirring, and then conduct vacuum distillation under the condition of cutting off the air to obtain the composite cellulose. 2 . The polyolefin catalyst according to claim 1 , characterized in that, the drying process of the cellulose powder is: vacuum drying the cellulose powder at 45-55° C. for 24-48 hours. 3. The polyolefin catalyst according to claim 1, characterized in that the conditions of the reaction are: 20-30° C. for 3-5 hours. 4. The polyolefin catalyst according to claim 1, characterized in that, the alkyl aluminoxane is methyl aluminoxane, ethyl aluminoxane or derivatives thereof which also possess the function of a polyolefin cocatalyst; The metallocene complex is a metallocene complex with polyolefin catalytic function. 5. polyolefin catalyst according to claim 1, is characterized in that, the process that described metallocene complex is supported on described composite cellulose is: under the condition of stirring, described composite cellulose is added in solvent After dropping the solution containing the metallocene complex and reacting to obtain a dispersion liquid, the dispersion liquid is distilled under reduced pressure under the condition of cutting off the air to obtain the polyolefin catalyst. 6 . The polyolefin catalyst according to claim 5 , characterized in that, the conditions of the reaction are: 20-30° C. for 3-5 hours. 7. polyolefin catalyst according to claim 1, is characterized in that, the diameter of described cellulose powder is nanoscale and/or micron order, and described cellulose powder comprises lignin, hemicellulose, and its purity is at 40wt % or more; preferably, the cellulose powder is chemically modified in advance. 8. The polyolefin catalyst according to claim 1, characterized in that, in the polyolefin catalyst, the molar ratio of the aluminum element to the metal element of the metallocene complex is 40 to 100; preferably, the polyolefin catalyst is directly Use it or mix it with industrial white oil. 9. The polyolefin catalyst according to claim 1, wherein the inert gas is nitrogen, helium or argon, and the solvent is toluene or hexane. 10. The application of the polyolefin catalyst according to any one of claims 1 to 9 in the homogeneous polymerization or copolymerization of olefins. 11. The application of the polyolefin catalyst according to any one of claims 1 to 9 in the gas phase polymerization or slurry polymerization of olefins.