Olefin polymerization catalyst system and application thereof in preparation of polyolefin elastomer

Abstract

The invention provides an olefin polymerization catalyst system and an application of the olefin polymerization catalyst system in preparation of a polyolefin elastomer. The olefin polymerization catalyst system comprises at least one of compounds with a structure as shown in a formula (1) and at least one of compounds with a structure as shown in a formula (2): # imgabs0. The olefin polymerization catalyst system comprises the compound with the structure as shown in the formula (1) and the compound with the structure as shown in the formula (2), polyolefin prepared by the olefin polymerization catalyst system has the characteristic of narrow molecular weight distribution, so that the polyolefin has good processability, mechanical property and thermal stability. Meanwhile, the olefin polymerization catalyst system is high in thermal stability and also has good polymerization activity under a high-temperature polymerization condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of olefin polymerization, and particularly relates to an olefin polymerization catalyst system and its application in the preparation of polyolefin elastomers. Background Art

[0002] Polyolefin elastomers were first industrially produced by The Dow Chemical Company in the United States in 1993. Currently, the demand for polyolefin elastomers in China is large, and relying solely on domestic chemical enterprises cannot meet the current needs, and a large amount of imports are required, especially for high-performance polyolefin elastomers.

[0003] Existing olefin polymerization catalyst systems can be divided into Ziegler-Natta catalyst systems and metallocene catalyst systems. Among them, the metallocene catalyst system consists of a main catalyst and a cocatalyst. Generally, the main catalyst is a compound containing a transition metal as the main component, and the cocatalyst is generally a compound containing aluminum as the main component.

[0004] The main catalyst in the metallocene catalyst system has uniformly distributed active sites. Therefore, when this catalyst system is used in the preparation of polymers, the polymers obtained have good properties, and the copolymerization reaction of the polymers can be easily carried out, and the distribution of comonomers is uniform. However, there is still room for improvement when used in the preparation of high-performance polyolefin elastomers. That is, developing new catalyst systems for the preparation of high-performance polyolefin elastomers is still a research direction with great challenges and significance. Summary of the Invention

[0005] In order to improve the deficiencies of the prior art, the present invention provides an olefin polymerization catalyst system and its application in the preparation of polyolefin elastomers. Specifically, the present invention provides the following technical solutions:

[0006] An olefin polymerization catalyst system, the olefin polymerization catalyst system includes at least one of the compounds shown in formula (1) and at least one of the compounds shown in formula (2):

[0007]

[0008] In formula (1), M is a transition metal; X1 and X2 are the same or different, and are independently selected from Cl or alkyl; R1 and R2 are the same or different, and are independently selected from hydrogen or alkyl, or R1 and R2 form a ring to form an aryl; R3 is selected from absent, substituted or unsubstituted alkyl, and when it is substituted, the substituent is halogen or alkyl; R4 is selected from linear alkyl;

[0009] In formula (2), M1 is a transition metal; X3 and X4 are the same or different, and are independently selected from Cl or alkyl; R5 and R6 are the same or different, and are independently selected from hydrogen or alkyl, or R5 and R6 form a ring to form an aryl.

[0010] The application of the above olefin polymerization catalyst system is used for the preparation of polyolefin elastomers.

[0011] Advantages of the present invention:

[0012] The present invention provides an olefin polymerization catalyst system. The olefin polymerization catalyst system includes a compound having the structure shown in formula (1) and a compound having the structure shown in formula (2). The polyolefin prepared by the olefin polymerization catalyst system has the characteristics of a narrow molecular weight distribution, which enables the polyolefin to have good processing properties, mechanical properties and thermal stability. At the same time, the olefin polymerization catalyst system has high thermal stability and also has good polymerization activity under high-temperature polymerization conditions. Detailed implementation manners

[0013] As described above, the present invention provides an olefin polymerization catalyst system, which includes at least one of the compounds having the structure shown in formula (1) and at least one of the compounds having the structure shown in formula (2):

[0014]

[0015] In formula (1), M is a transition metal; X1 and X2 are the same or different and are independently selected from Cl or an alkyl group; R1 and R2 are the same or different and are independently selected from hydrogen or an alkyl group, or R1 and R2 form a ring to form an aryl group; R3 is selected from absent, substituted or unsubstituted alkyl, and when it is substituted, the substituent is a halogen or an alkyl group; R4 is selected from a straight-chain alkyl group;

[0016] In formula (2), M1 is a transition metal; X3 and X4 are the same or different and are independently selected from Cl or an alkyl group; R5 and R6 are the same or different and are independently selected from hydrogen or an alkyl group, or R5 and R6 form a ring to form an aryl group.

[0017] According to an embodiment of the present invention, in formula (1), M is Ti or Zr.

[0018] According to an embodiment of the present invention, in formula (1), X1 and X2 are the same or different and are independently selected from Cl or C 1-6 alkyl. Exemplarily, X1 and X2 are the same or different and are independently selected from Cl or C 1-3 alkyl.

[0019] According to an embodiment of the present invention, in formula (1), R1 and R2 are the same or different and are independently selected from hydrogen or C 1-6 alkyl, or R1 and R2 form a ring to form C 6-12 aryl. Exemplarily, R1 and R2 are the same or different and are independently selected from hydrogen or C 1-3alkyl, or R1 and R2 form a ring to form C 6-8 aryl.

[0020] According to an embodiment of the present invention, in formula (1), R3 is selected from absent, substituted or unsubstituted C 1-6 alkyl, and when substituted, the substituent is halogen or C 1-6 alkyl. Exemplarily, R3 is selected from absent, substituted or unsubstituted C 1-3 alkyl, and when substituted, the substituent is halogen or C 1-3 alkyl.

[0021] According to an embodiment of the present invention, in formula (1), R4 is selected from C 3-12 linear alkyl. Exemplarily, R4 is selected from C 3-10 linear alkyl. Also exemplarily, R4 is selected from C 4-8 linear alkyl.

[0022] According to an embodiment of the present invention, in formula (1), M is Ti or Zr; R3 is selected from absent, substituted or unsubstituted C 1-6 alkyl, and when substituted, the substituent is halogen or C 1-6 alkyl; R4 is selected from C 3-12 linear alkyl;

[0023] X1 and X2 are the same or different and are independently selected from Cl or C 1-6 alkyl; R1 and R2 are the same or different and are independently selected from hydrogen or C 1-6 alkyl, or R1 and R2 form a ring to form C 6-12 aryl.

[0024] According to an embodiment of the present invention, in formula (1), M is Ti or Zr; R3 is selected from absent, substituted or unsubstituted C 1-3 alkyl, and when substituted, the substituent is halogen or C 1-3 alkyl; R4 is selected from C 3-10 linear alkyl;

[0025] X1 and X2 are the same or different and are independently selected from Cl or C 1-3 alkyl; R1 and R2 are the same or different and are independently selected from hydrogen or C 1-3 alkyl, or R1 and R2 form a ring to form C 6-8 aryl.

[0026] According to an embodiment of the present invention, in formula (1), M is Ti or Zr; R3 is selected from absent, substituted or unsubstituted C 1-3 alkyl, and when substituted, the substituent is halogen or C 1-3 alkyl; R4 is selected from C 4-8 linear alkyl;

[0027] X1 and X2 are the same or different and are each independently selected from Cl or C 1-3 alkyl; R1 and R2 are the same or different and are each independently selected from hydrogen or C 1-3 alkyl, or R1 and R2 form a ring to form a phenyl group.

[0028] According to an embodiment of the present invention, the compound represented by the formula (1) is selected from at least one of the following compounds 1 - compound 4:

[0029]

[0030] According to an embodiment of the present invention, in formula (2), M1 is Ti or Zr.

[0031] According to an embodiment of the present invention, in formula (2), X3 and X4 are the same or different and are each independently selected from Cl or C 1-6 alkyl. Exemplarily, X3 and X4 are the same or different and are each independently selected from Cl or C 1-3 alkyl.

[0032] According to an embodiment of the present invention, in formula (2), R5 and R6 are the same or different and are each independently selected from hydrogen or C 1-6 alkyl, or R5 and R6 form a ring to form C 6-12 aryl. Exemplarily, R5 and R6 are the same or different and are each independently selected from hydrogen or C 1-3 alkyl, or R5 and R6 form a ring to form C 6-8 aryl.

[0033] According to an embodiment of the present invention, in formula (2), M1 is Ti or Zr; X3 and X4 are the same or different and are each independently selected from Cl or C 1-6 alkyl; R5 and R6 are the same or different and are each independently selected from hydrogen or C 1-6 alkyl, or R5 and R6 form a ring to form C 6-12 aryl.

[0034] According to an embodiment of the present invention, in formula (2), M1 is Ti or Zr; X3 and X4 are the same or different and are each independently selected from Cl or C 1-3 alkyl; R5 and R6 are the same or different and are each independently selected from hydrogen or C 1-3 alkyl, or R5 and R6 form a ring to form C 6-8 aryl.

[0035] According to an embodiment of the present invention, in formula (2), M1 is Ti or Zr; X3 and X4 are the same or different and are each independently selected from Cl or C 1-3 alkyl; R5 and R6 are the same or different and are each independently selected from hydrogen or C1-3 an alkyl group, or R5 and R6 form a ring to form a phenyl group.

[0036] According to an embodiment of the present invention, the compound represented by the formula (2) is selected from at least one of the following compounds 5 - compound 8:

[0037]

[0038] According to an embodiment of the present invention, the molar ratio of the compound represented by the formula (1) to the compound represented by the formula (2) is 1:(2 - 5), for example, 1:2, 1:3, 1:4 or 1:5.

[0039] According to an embodiment of the present invention, when the compound represented by the formula (1) and the compound represented by the formula (2) are used in combination, it is unexpectedly found that the molecular weight distribution of the obtained polyolefin is significantly narrowed, and the processing performance, mechanical properties and thermal stability of the obtained polyolefin are all improved. At the same time, the catalyst system can be applied to higher temperatures, which greatly shortens the reaction time and increases the annual output of polyolefin.

[0040] The inventors speculate that this may be because the compound represented by the formula (1) contains a pentacoordinate complex, and there is a silicon bridging structure and two other types of bridging structures in the pentacoordinate complex, such as two other types of bridging structures (pyridine - M - cyclopentadiene and pyridine - R - OR4 - M - cyclopentadiene) between the cyclopentadiene and pyrrole rings described in the formula (1). X - ray diffraction analysis reveals that due to the presence of the pentacoordinate in the catalyst containing the pentacoordinate complex structure, the bridging structures therein cannot be matched, resulting in the continuous rocking vibration of the electronegative group OR4, so that the catalyst continuously opens and closes rings during the polymerization process, activating the activity of the transition metal active center. And the compound represented by the formula (2) has a sufficiently high thermal stability to ensure the catalytic activity. More importantly, when the two compounds are used in combination, due to the existence of the electronic effect and steric effect in the catalytic system, the uniform insertion of α - olefin can be ensured, and finally the preparation of polyolefin with a narrow molecular weight distribution is realized.

[0041] According to an embodiment of the present invention, the olefin polymerization catalyst system further includes a cocatalyst.

[0042] According to an embodiment of the present invention, the cocatalyst is selected from alkyl aluminums and / or organoboron compounds.

[0043] According to an embodiment of the present invention, the alkyl aluminum is preferably trimethyl aluminum, triethyl aluminum, triisobutyl aluminum or a mixture of at least two of them.

[0044] According to an embodiment of the present invention, the organoboron compound is at least selected from Ph3CB(C6F5)4, B(C6F5)3, PhNMe2HB(C6F5)4, Ph3CB[(CF3)2C6H3]4, or a mixture of at least two of them.

[0045] Compared with aluminoxane cocatalysts, the olefin polymerization catalyst system of the present application can well match the main catalyst by using alkylaluminum and / or organoboron compounds, can achieve good olefin polymerization efficiency, and can also greatly reduce the cost of the production process.

[0046] According to an embodiment of the present invention, the molar ratio of the main catalyst to the cocatalyst is 1:500 - 2000, for example, 1:500, 1:1000, 1:1500, or 1:2000.

[0047] According to an embodiment of the present invention, the olefin is at least one selected from ethylene and olefins having 3 - 10 carbon atoms. Preferably, the olefin is at least one selected from ethylene and at least one of propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene.

[0048] According to an embodiment of the present invention, the compound of the structure shown in formula (1) is prepared, for example, by a method including the following steps:

[0049] After compound 1-1 reacts with a lithium salt, a metal salt containing M is added to obtain compound 1, that is, the compound of the structure shown in formula (1);

[0050]

[0051] Wherein, R1, R2, R3, R4, X1, X2, and M independently have the definitions described above.

[0052] According to an embodiment of the present invention, the lithium salt can be selected from alkyllithium reagents, such as butyllithium (specifically, it can be n-butyllithium, isobutyllithium, or tert-butyllithium, preferably n-butyllithium) or lithium diisopropylamide.

[0053] According to an embodiment of the present invention, the metal salt containing M can be a halogen salt containing M, such as titanium tetrachloride or zirconium tetrachloride.

[0054] According to an embodiment of the present invention, compound 1-1 is prepared by a method including the following steps:

[0055] (1) Compound 1-3 reacts with compound 1-4 to obtain compound 1-2;

[0056] (2) Compound 1-2 is deprotected to obtain compound 1-1;

[0057]

[0058] Among them, R1, R2, R3, and R4 each independently have the definitions described above; X is selected from halogens, such as Br, Cl, or I; PG is selected from N-protecting groups, such as Boc, Bn, Cbz.

[0059] According to an embodiment of the present invention, the compound having the structure shown in formula (2) is prepared, for example, by a method including the following steps:

[0060] After the compound 2-1 reacts with a lithium salt, a metal salt containing M1 is added to obtain compound 2, that is, the compound having the structure shown in formula (2);

[0061]

[0062] Among them, R5, R6, X3, X4, and M1 each independently have the definitions described above.

[0063] According to an embodiment of the present invention, the lithium salt can be selected from at least one of alkyllithium reagents, such as butyllithium (specifically, n-butyllithium, isobutyllithium, or tert-butyllithium, preferably n-butyllithium) or lithium diisopropylamide.

[0064] According to an embodiment of the present invention, the metal salt containing M1 can be a halogen salt containing M1, such as titanium tetrachloride or zirconium tetrachloride.

[0065] According to an embodiment of the present invention, compound 2-1 is prepared by a method including the following steps:

[0066] (1) Compound 2-3 reacts with compound 1-4 to obtain compound 2-2;

[0067] (2) Compound 2-2 is deprotected to obtain compound 2-1;

[0068]

[0069] Among them, R5 and R6 each independently have the definitions described above; X is selected from halogens, such as Br, Cl, or I; PG is selected from N-protecting groups, such as Boc, Bn, Cbz.

[0070] As described above, the present invention also provides a method for preparing a polyolefin elastomer, which includes polymerizing an olefin in the presence of the above olefin polymerization catalyst system to obtain a polyolefin elastomer.

[0071] According to an embodiment of the present invention, the method includes the following steps:

[0072] Inject the olefin polymerization catalyst system into the reaction kettle, introduce an olefin and hydrogen, and carry out a polymerization reaction.

[0073] According to an embodiment of the present invention, the polymerization reaction does not require activation treatment of the catalyst before the reaction because the catalyst of the present application has high solubility in the solvent, and the catalytic activity and catalytic efficiency obtained directly after use without additional activation treatment can still meet the requirements of olefin polymerization production.

[0074] According to an embodiment of the present invention, the olefin includes ethylene and a comonomer; specifically, the comonomer is selected from at least one of propylene, 1-butene, 1-pentene, and 1-hexene.

[0075] According to an embodiment of the present invention, the temperature of the polymerization reaction is 25°C - 180°C, such as 38°C, 58°C, 98°C, 128°C, 149°C, 169°C, or 179°C.

[0076] According to an embodiment of the present invention, the pressure of the polymerization reaction is 0.1 MPa - 5 MPa, such as 0.8 MPa, 1.5 MPa, 2.6 MPa, 3.9 MPa, or 4.9 MPa.

[0077] The preparation method of the present invention will be further described in detail below with reference to specific examples. It should be understood that the following examples are only for illustrative explanation of the present invention and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection of the present invention.

[0078] The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0079] The molecular weight distribution of the polymer was tested by gel permeation chromatography.

[0080] Preparation Example 1

[0081]

[0082] Step 1: At -78°C, 1.5 equivalents of lithium 2,2,6,6-tetramethylpiperidine were added to a 100 mL solution of 10 g of compound 1a in tetrahydrofuran in a reactor. After the addition, the temperature was raised to room temperature and the reaction was carried out for 3 h. Then 1 equivalent of compound 1b was added to the reaction solution, and the stirring reaction was continued for 2 h. After the reaction was completed, saturated ammonium chloride was added for quenching, and the mixture was extracted with ethyl acetate. After layering, the organic phases were combined and purified by silica gel column to obtain compound 1c (14.2 g).

[0083] Step 2: Dissolve 10 g of Compound 1c in dichloromethane (80 mL), then add trifluoroacetic acid (20 mL), and stir at room temperature for 3 h. After concentration under reduced pressure, slowly add saturated sodium bicarbonate solution to adjust the pH to 8 - 9, extract with dichloromethane, wash with saturated brine, dry over anhydrous sodium sulfate, filter and concentrate to obtain Compound 1d (6.8 g).

[0084] Step 3: At -78 °C, dropwise add a solution of 2.0 g of ligand 1d in tetrahydrofuran (20 mL) with 2 equivalents of a solution of n-butyllithium in tetrahydrofuran (4.0 M) to the reactor. After the addition is complete, warm to room temperature and react for 2 h. Then add 1.5 equivalents of titanium tetrachloride to the reaction solution and stir for 1 h. Quench the reaction by adding 10 mL of water, and continue to stir for 0.5 h. Remove the reaction solvent under vacuum, dissolve the residue in toluene, filter off the insoluble matter, and then remove the solvent again. Recrystallize the obtained solid from dichloromethane and n-hexane to obtain Compound 1 (1.65 g). Theoretical values: C 17 H 25 Cl2NOSiTi: C, 50.26; H, 6.20; Cl, 17.45; N, 3.45; O, 3.94; Si, 6.91; Measured values: C, 50.22; H, 6.96; Cl, 17.04; N, 3.11; O, 3.43; Si, 6.25.

[0085] Preparation Example 2 - 4

[0086] Refer to Preparation Example 1 to obtain the following Compounds 2 to 4;

[0087]

[0088]

[0089] Preparation Example 5

[0090]

[0091] Step 1: At -78 °C, add 1.5 equivalents of lithium 2,2,6,6-tetramethylpiperidide to a solution of 10 g of Compound 5a in tetrahydrofuran (100 mL) in the reactor. After the addition is complete, warm to room temperature and react for 4 h. Then add 1 equivalent of Compound 1b to the reaction solution and continue to stir for 4 h. Quench the reaction with saturated ammonium chloride after completion, and extract with ethyl acetate. After layering, combine the organic phases and purify by silica gel column chromatography to obtain Compound 1c (10.7 g).

[0092] Step 2: Dissolve 10 g of compound 5c in dichloromethane (80 mL), then add trifluoroacetic acid (20 mL), and stir at room temperature for 2 h. After concentration under reduced pressure, slowly add saturated sodium bicarbonate solution to adjust the pH to 8 - 9, extract with dichloromethane, wash with saturated brine, dry over anhydrous sodium sulfate, filter and concentrate to obtain compound 5d (5.3 g).

[0093] Step 3: At -78 °C, dropwise add a solution of 2.0 M n-butyllithium in tetrahydrofuran (4.0 M) to a solution of 2.0 g of ligand 5d in tetrahydrofuran (20 mL) in a reactor. After the addition is complete, warm the reaction mixture to room temperature and react for 5 h. Then add 1.5 equivalents of titanium tetrachloride to the reaction solution and stir for 2 h. Quench the reaction by adding 10 mL of water, and continue to stir for 0.5 h. Remove the reaction solvent under vacuum, dissolve the residue in toluene, filter off the insoluble matter, and then remove the solvent again. Recrystallize the resulting solid from dichloromethane and n-hexane to obtain compound 5 (1.22 g). Theoretical values: C 15 H 21 Cl2NSiTi: C, 49.74; H, 5.84; Cl, 19.58; N, 3.87; Si, 7.75; Measured values: C, 49.25; H, 6.11; Cl, 19.10; N, 3.61; Si, 7.26.

[0094] Preparation Examples 6 - 8

[0095] Following Reference Preparation Example 5, the following Compounds 6 to 8 were obtained;

[0096]

[0097] Example 1

[0098] Mix the compound prepared in Preparation Example 1 and the compound prepared in Preparation Example 5 in a molar ratio of 1:2 as the main catalyst, then add triisobutylaluminum as the cocatalyst, and ensure that the molar ratio of the cocatalyst to the main catalyst is 1500:1 to obtain an olefin polymerization catalyst system.

[0099] Example 2

[0100] The preparation of the catalyst system was the same as in Example 1, except that the composition of the catalyst was specifically as shown in Table 1.

[0101] Table 1 Composition of the catalyst system

[0102]

[0103] Test Example 1

[0104] Carry out ethylene-1-octene copolymerization reactions using the catalysts of the examples and comparative examples respectively

[0105] The specific polymerization method includes the following steps:

[0106] (1) Add toluene into a stirred reactor protected by nitrogen, then add the olefin polymerization catalyst system prepared above, and control the temperature of the reactor at 30 °C;

[0107] (2) Then add 1-octene, then add hydrogen, and finally continuously introduce ethylene to keep the total polymerization pressure constant at 2.0 MPa, and react for 120 min under the condition of 80 °C;

[0108] (3) Terminate the reaction, cool to room temperature, and test the hydrogen content, the yield of the polymerization product and related properties as shown in Table 2.

[0109] Table 2 Performance test results of polyolefins prepared by the catalysts of the examples and comparative examples

[0110]

[0111] It can be seen from Table 2 that the catalyst of the present invention has high polymerization activity, high α-olefin insertion rate, good insertion uniformity, and narrow molecular weight distribution of the obtained polyolefin.

[0112] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An olefin polymerization catalyst system, characterized in that, The olefin polymerization catalyst system comprises at least one compound having the structure shown in formula (1) and at least one compound having the structure shown in formula (2): In formula (1), M is a transition metal; X1 and X2 are the same or different and are independently selected from Cl or an alkyl group; R1 and R2 are the same or different and are independently selected from hydrogen or an alkyl group, or R1 and R2 form a ring to form an aryl group; R3 is selected from absent, substituted or unsubstituted alkyl, and when substituted, the substituent is a halogen or an alkyl group; R4 is selected from a linear alkyl group; In formula (2), M1 is a transition metal; X3 and X4 are the same or different and are independently selected from Cl or an alkyl group; R5 and R6 are the same or different and are independently selected from hydrogen or an alkyl group, or R5 and R6 form a ring to form an aryl group.

2. The olefin polymerization catalyst system according to claim 1, wherein, In formula (1), M is Ti or Zr; And / or, in formula (1), R3 is selected from absent, substituted or unsubstituted C 1-6 alkyl, and when it is substituted, the substituent is halogen or C 1-6 alkyl; And / or, in formula (1), R4 is selected from C 3-12 linear alkyl. Exemplarily, R4 is selected from C 3-10 linear alkyl; and / or, in formula (1), X1 and X2 are the same or different and are each independently selected from Cl or C 1-6 alkyl; And / or, in formula (1), R1 and R2 are the same or different and are each independently selected from hydrogen or C 1-6 alkyl, or R1 and R2 form a ring to form C 6-12 aryl.

3. The olefin polymerization catalyst system according to claim 1 or 2, wherein The compound shown in formula (1) is selected from at least one of the following compounds 1 - compound 4:

4. The olefin polymerization catalyst system according to any one of claims 1-3, wherein, In formula (2), M1 is Ti or Zr; and / or, in formula (2), X3 and X4 are the same or different and are each independently selected from Cl or C 1-6 alkyl; And / or, in formula (2), R5 and R6 are the same or different and are each independently selected from hydrogen or C 1-6 alkyl, or R5 and R6 form a ring to form C 6-12 aryl.

5. The olefin polymerization catalyst system according to any one of claims 1-4, wherein, The compound shown in formula (2) is selected from at least one of the following compounds 5 - compound 8:

6. The olefin polymerization catalyst system according to any one of claims 1-5, wherein, The molar ratio of the compound having the structure shown in formula (1) to the compound having the structure shown in formula (2) is 1:(2 - 5).

7. The olefin polymerization catalyst system according to any one of claims 1-6, wherein, The olefin polymerization catalyst system further comprises a cocatalyst; The cocatalyst is selected from an alkylaluminum and / or an organoboron compound.

8. The olefin polymerization catalyst system according to claim 7, wherein, The molar ratio of the main catalyst to the cocatalyst is 1:500 - 2000.

9. A method for preparing a polyolefin elastomer, the method comprising polymerizing an olefin in the presence of the olefin polymerization catalyst system according to any one of claims 1 - 8 to obtain a polyolefin elastomer.

10. According to the preparation method of claim 9, the method comprises the following steps: Inject the olefin polymerization catalyst system into a reaction kettle, introduce an olefin and hydrogen, and carry out a polymerization reaction. Preferably, the temperature of the polymerization reaction is 25°C - 180°C; the pressure of the polymerization reaction is 0.1 MPa - 5 MPa.

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