CN102153681B - Supported metallocene catalyst and application thereof - Google Patents

Abstract

The invention relates to a novel supported metallocene catalyst and application thereof. The supported metallocene catalyst is prepared by using titanium dioxide nano tubes as carriers and used for catalyzing olefin polymerization. The supported catalyst can be used for preparing polyolefin of different forms under different polymerization conditions.

Description

A kind of supported metallocene catalyst and its application

technical field

The invention relates to a supported metallocene catalyst for olefin polymerization.

Background technique

The supported metallocene catalyst means that the metallocene compound and the cocatalyst are supported on the carrier and exist in a heterogeneous phase. At present, the selected inorganic carriers mainly include: silica, alumina, montmorillonite and so on. One major problem with the supported metallocene catalysts prepared with the above supports is that the polymer morphology is difficult to control when used in the polymerization of olefins. Polymer morphology directly affects the processing and thermodynamic properties of polymers.

In order to obtain a supported metallocene catalyst that can effectively control the polymer morphology, the effective coordination and selection of the support, main catalyst and cocatalyst in the catalyst is still an important research topic in this field.

Contents of the invention

The purpose of the present invention is to overcome the problems in the prior art above, and provide a novel supported metallocene catalyst and its application. The catalyst is stable in loading and has a high loading capacity, and the supported catalyst maintains a high ethylene polymerization activity. , can significantly increase the molecular weight and melting point of the polymer, and especially can effectively realize the controllable shape of the polymer.

A supported metallocene catalyst of the present invention is composed of a main catalyst, a co-catalyst and a carrier; the main catalyst is Cp ₂ ZrCl ₂ , (CH ₃ ) ₂ C[Ind] ₂ ZrCl ₂ , (CH ₃ ) ₂ C[Cp,Ind]ZrCl ₂ , rac-Et-(Ind) ₂ ZrCl ₂ or CpSi(Me) ₂ N(t-Bu)ZrCl ₂ ;

The cocatalyst is alkyl aluminoxane or boride;

The carrier is titanium dioxide nanotube.

Said alkylalumoxane preferably includes methylalumoxane, ethylalumoxane or butylalumoxane.

The boride preferably includes B(C ₆ F ₅ ) ₃ , [Ph ₃ C]B(C ₆ F ₅ ) ₄ or HNR ₃ B(C ₆ F ₅ ) ₄ .

The preferred supported metallocene catalyst of the present invention is Cp ₂ ZrCl ₂ or (CH ₃ ) ₂ C[Cp,Ind]ZrCl ₂ as the main catalyst, methylaluminoxane as the co-catalyst, and titanium dioxide nanotube as the carrier.

Another preferred supported metallocene catalyst of the present invention is Cp ₂ ZrCl ₂ as the main catalyst, B(C ₆ F ₅ ) ₃ as the co-catalyst, and titanium dioxide nanotube as the carrier.

The above-mentioned supported metallocene catalyst is applied as a catalyst for the homopolymerization of ethylene or the copolymerization of ethylene and α-olefin.

The supported metallocene catalyst with titanium dioxide nanotube as the carrier of the invention is composed of a carrier, a main catalyst and a co-catalyst. The main catalyst selected by the present invention is Cp ₂ ZrCl ₂ , (CH ₃ ) ₂ C[Ind] ₂ ZrCl ₂ , (CH ₃ ) ₂ C[Cp,Ind]ZrCl ₂ , rac-Et-(Ind) ₂ ZrCl ₂ or For CpSi(Me) ₂ N(t-Bu)ZrCl ₂ , since the central metal of these main catalysts is Zr, the ligand has little influence on the morphology of the polymer after loading. Zirconocene dichloride (Cp ₂ ZrCl ₂ ), which is easy to operate, cheap and readily available, is the most suitable and preferred main catalyst in the present invention. Compared with the main catalyst, the co-catalyst selected in the present invention can effectively make the main catalyst form a compound of metal cation active center, such as alkyl aluminoxane or boride, etc., wherein suitable alkyl aluminoxane includes methyl aluminoxane , ethylaluminoxane, butylaluminoxane and boron compounds, etc., preferably methylaluminoxane, suitable borides include B(C ₆ F ₅ ) ₃ , [Ph ₃ C]B(C ₆ F ₅ ) ₄ or HNR ₃ B(C ₆ F ₅ ) ₄ etc. The co-catalyst that can be added during the polymerization reaction first activates the main catalyst on the carrier to form an active center, and then catalyzes the polymerization. In addition, the determination of the carrier of the present invention is also very important. In order to obtain a catalyst with a controllable polymer shape, we also try to use other carriers to support the selected main catalyst and co-catalyst of the present invention, such as Cp ₂ ZrCl ₂ etc. are used to catalyze In the polymerization of ethylene, no matter how the polymerization conditions are changed, a polymer with controllable morphology cannot be obtained, and the morphology, molecular weight and melting point of the polymer obtained by homogeneous polymerization are not much different (see comparative example). It is precisely because the inventor has tried and cooperated with the above three aspects of the main catalyst, the co-catalyst and the carrier that the technical solution that the present invention can be implemented can be obtained, and the catalyst load can be effectively stabilized, the load capacity is high, and the supported catalyst maintains Higher ethylene polymerization activity is high, which can significantly increase the molecular weight and melting point of the polymer, and control the shape of the polymer.

The catalyst of the present invention can be used for olefin polymerization, such as ethylene polymerization and ethylene and α-olefin copolymerization and the like. After adopting the catalyst component of the present invention, technicians only need to control the polymerization conditions, especially the dosage of the cocatalyst of the present invention, to obtain polyolefin products in different forms.

In the prior art, although the main catalyst and the co-catalyst selected by the present invention can catalyze the polymerization of ethylene and the copolymerization of ethylene and α-olefins under unloaded conditions, it is still impossible to effectively control the morphology of the polymer, and only the main catalyst Only when it is effectively combined with the cocatalyst and the carrier described in the present invention can the polymer morphology control be really effectively realized.

Description of drawings

Fig. 1. Example 1 makes comparison of three kinds of polyethylene scanning electron micrographs, wherein a and b are supported catalysts to catalyze ethylene polymerization to obtain polyethylene, and the Al/Zr ratio during polymerization is 1000 and 3000 respectively; c is non-supported catalysts catalyzed ethylene Polymerization yields polyethylene.

Fig. 2. Scanning electron micrographs of two kinds of polyethylenes obtained in Example 2, where a and b are Al/Zr ratios of 1000 and 3000 respectively during polymerization.

Fig. 3. Scanning electron micrographs of two kinds of polyethylenes obtained in Example 3, where a and b are Al/Zr ratios of 1000 and 3000 respectively during polymerization.

Fig. 4. Scanning electron micrographs of two kinds of polyethylenes obtained in Example 4, where a and b are B/Zr ratios of 1000 and 3000 respectively during polymerization.

Fig. 5. Scanning electron micrographs of two kinds of polyethylenes obtained in Example 5, where a and b are B/Zr ratios of 1000 and 3000 respectively during polymerization.

Figure 6. Scanning electron micrographs of two polyethylenes prepared in Comparative Example 1, wherein a and b are Al/Zr ratios of 1000 and 3000 during polymerization, respectively.

Detailed ways

The following examples of preparation process and effect are intended to illustrate the present invention rather than further limit the present invention.

Example 1

The main catalyst is: Cp ₂ ZrCl ₂ ;

The carrier is: titanium dioxide nanotubes;

Preparation of supported catalyst: 1 gram of titania nanotubes and 50 mL of methylaluminoxane (20 mmol) were stirred at 50° C. for 5 hours. After filtration, it was washed with 25 ml of toluene, and the liquid was removed by filtration. Then add 50 milliliters of toluene and Cp ₂ ZrCl ₂ with an aluminum-zirconium ratio of 50 and stir for 5 hours at 50 ° C. After filtering, wash 5 times with 25 milliliters of toluene each time, and then filter to remove the liquid to obtain a solid supported catalyst. All operations are under nitrogen protection. next.

Ethylene polymerization: ethylene polymerization pressure is 0.13MPa, polymerization temperature is 60°C, polymerization solvent is 100mL toluene, supported catalyst concentration is 2.5μmolZr/L, cocatalyst is methylaluminoxane (MAO), under different Al/Zr ratio conditions After polymerization for 0.5 hours, the reaction was terminated with 10% ethanol solution of hydrochloric acid, petroleum ether precipitated, washed by suction filtration, dried and weighed. As a comparison, under the same polymerization conditions, the non-supported procatalyst in this example was used to catalyze ethylene polymerization.

The ethylene polymerization activity and polymer physical properties are shown in the following table: The morphology of polyethylene prepared in the table is shown in Figure 1

Example 2

The main catalyst Cp ₂ ZrCl ₂ in Example 1 was changed to (CH ₃ ) ₂ C[Cp,Ind]ZrCl ₂ , and the rest were the same as in Example 1.

The ethylene polymerization activity and polymer properties are shown in the following table: Polyethylene morphology is shown in Figure 2

Example 3

Change ethylene in embodiment 1 into ethylene and octene-1 copolymerization, wherein octene content is 15%, all the other are the same as embodiment 1.

The ethylene polymerization activity and polymer properties are shown in the following table: Polyethylene morphology is shown in Figure 3

Example 4

In Example 1, the cocatalyst was changed from methylaluminoxane (MAO) to B(C ₆ F ₅ ) ₃ , and the rest were the same as in Example 1.

The ethylene polymerization activity and polymer properties are shown in the following table: Polyethylene morphology is shown in Figure 4

Example 5

In Example 2, the cocatalyst was changed from methylaluminoxane (MAO) to B(C ₆ F ₅ ) ₃ , and the rest were the same as in Example 2.

The ethylene polymerization activity and polymer properties are shown in the following table: Polyethylene morphology is shown in Figure 5

Comparative example 1

As a comparison, we choose _SiO2 instead of titanium dioxide nanotubes, and the rest are the same as in Example 1.

The ethylene polymerization activity and polymer properties are shown in the following table: polyethylene morphology see Figure 6

Claims (6)

1. a carried metallocene catalyst is made up of Primary Catalysts, promotor and carrier; Described Primary Catalysts is Cp ₂ZrCl ₂, (CH ₃) ₂C [Ind] ₂ZrCl ₂, (CH ₃) ₂C [Cp, Ind] ZrCl ₂, rac-Et-(Ind) ₂ZrCl ₂Or CpSi (Me) ₂N (t-Bu) ZrCl ₂

Described promotor is alkylaluminoxane or boride;

Described carrier is a titania nanotube.

2. a kind of carried metallocene catalyst according to claim 1, described alkylaluminoxane comprise MAO, ethyl aikyiaiurnirsoxan beta or butyl aikyiaiurnirsoxan beta.

3. a kind of carried metallocene catalyst according to claim 1, described boride comprises B (C ₆F ₅) ₃, [Ph ₃C] B (C ₆F ₅) ₄

4. a kind of carried metallocene catalyst according to claim 1, Primary Catalysts are Cp ₂ZrCl ₂Or (CH ₃) ₂C [Cp, Ind] ZrCl ₂, promotor is a MAO, carrier is a titania nanotube.

5. a kind of carried metallocene catalyst according to claim 1, Primary Catalysts are Cp ₂ZrCl ₂, promotor is B (C ₆F ₅) ₃, carrier is a titania nanotube.

6. each described a kind of carried metallocene catalyst of claim 1-5 is used the catalyzer as ethylene homo or ethene and alpha-olefin copolymer.

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