CN118084987A - Silicon bridged neutral ligand-containing side arm single metallocene complex and application thereof - Google Patents

Abstract

The present invention relates to the technical field of olefin polymerization catalysts, and in particular to a silicon-bridged single metallocene complex containing a neutral ligand side arm and its application. The present invention provides a silicon-bridged single metallocene complex containing a neutral ligand side arm, having a structure shown in Formula I; the silicon-bridged single metallocene complex containing a neutral ligand side arm can be used as an olefin polymerization catalyst, and can catalyze ethylene polymerization with high activity to selectively generate 1-octene or C10 or above α-olefins.

Description

Silicon-bridged single metallocene complexes containing neutral ligand side arms and their applications

Technical Field

The invention relates to the technical field of olefin polymerization catalysts, in particular to a silicon-bridged neutral ligand-containing side-arm monometallocene complex and application thereof.

Background technique

As an important organic chemical raw material, α-olefin is widely used in the fields of comonomers of polyolefin elastomers, surfactants, high-grade lubricants, plasticizers, detergents and oil additives. Among them, linear low-density polyethylene and polyolefin elastomers produced by copolymerizing α-olefin with ethylene as a comonomer are widely used in the fields of medical devices, automobiles, electronics, packaging, building materials, industry and agriculture. α-olefin is also an important raw material for the synthesis of high-grade lubricant base oil-PAO (Poly AlphaOlefin, polyalphaolefin).

In recent years, with the continuous development of the polyolefin industry, the world's demand for α-olefins has continued to increase. The main methods for industrially producing α-olefins include paraffin cracking, alkane dehydrogenation, alcohol dehydration and ethylene polymerization. According to statistics, ethylene polymerization is currently the main method for producing α-olefins.

Among them, the most common catalytic system for ethylene polymerization is a catalytic system containing metallic chromium, such as the Philips trimerization catalytic system. However, heavy metal chromium is highly toxic and can cause environmental pollution. With the development of science and technology, in recent years, there have been reports on the use of other transition metal compounds to catalyze ethylene polymerization, mainly transition metal compounds of the fourth and fifth subgroups. For example, Hessen et al. reported in 2001 and 2002 the use of [(η ⁵ -C ₅ H ₄ C(Me) ₂ RTiCl ₃ ]/MAO (methylaluminoxane) catalytic system (Angew. Chem. 2001, 113, 2584) and [(η ⁵ -C ₅ H ₃ R(bridge)ArTiCl ₃ ]/MAO catalytic system (Organometallics 2002, 21, 5122; J.Am.Chem.Soc.2009, 131, 5298) catalyzes the oligomerization of ethylene to produce 1-hexene with high selectivity. Huang Jiling et al. developed several semi-sandwich titanium complexes containing thiophene or tetrahydrofuran side arms that can catalyze the trimerization of ethylene to obtain 1-hexene (Chem. Commun., 2003, 22, 2816; J.Mol.Catal.A, 2004, 214, 227; J.Mol.Catal.A, 2014, 387, 20). In 2018, Azimnavahsi et al. reported a series of indenyl semi-sandwich titanium complexes containing thiophene side arms, which can catalyze the trimerization of ethylene to obtain 1-hexene with high activity under the activation of MAO (Appl Organometal Chem.2019, 33, 4666).

So far, most of the reported fourth-group single metallocene complex systems for catalyzing ethylene trimerization to produce 1-hexene have relatively low catalytic activity and are difficult to use in industrial production. Moreover, they can only catalyze ethylene trimerization to produce 1-hexene, and cannot selectively produce other α-olefins. Therefore, the development of new catalysts that can catalyze ethylene oligomerization to selectively produce C8 and above α-olefins is an important issue facing those skilled in the art.

Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a silicon-bridged single metallocene complex containing a neutral ligand side arm and its application, wherein the silicon-bridged single metallocene complex containing a neutral ligand side arm can catalyze ethylene polymerization with high activity to selectively produce 1-octene or C10 or higher α-olefins.

The present invention provides a silicon-bridged single metallocene complex containing a neutral ligand side arm, having a structure shown in Formula I;

In Formula I, M is selected from any one of Ti (titanium), Zr (zirconium) and Hf (hafnium);

Cp is selected from any one of cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl, substituted fluorenyl, cycloheptatrienyl and substituted cycloheptatrienyl;

A is selected from N (nitrogen element) or P (phosphorus element);

_R1 and _R2 are independently selected from substituted or unsubstituted alkyl groups with 1 to 30 carbon atoms, cycloalkyl groups with 3 to 30 carbon atoms, substituted or unsubstituted alkenyl groups with 2 to 30 carbon atoms, substituted or unsubstituted aryl groups with 6 to 30 carbon atoms; the substituents include alkyl groups with 1 to 30 carbon atoms, aryl groups with 6 to 30 carbon atoms or silane groups with 1 to 30 carbon atoms; or _R1 and _R2 are linked to form an alkylene group or an alkenylene group;

_R3 and _R4 are independently selected from hydrogen, substituted or unsubstituted alkyl having 1 to 30 carbon atoms, cycloalkyl having 3 to 30 carbon atoms, aryl having 6 to 30 carbon atoms; the substituent includes alkyl having 1 to 30 carbon atoms, aryl having 6 to 30 carbon atoms or silyl having 1 to 30 carbon atoms;

X is selected from substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms, alkylamine groups having 1 to 30 carbon atoms, alkoxy groups having 1 to 30 carbon atoms or halogen groups; the substituents include alkyl groups having 1 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms or silane groups having 1 to 30 carbon atoms.

As a further embodiment of the present invention: M is selected from any one of Ti (titanium), Zr (zirconium) and Hf (hafnium); Cp is any one of cyclopentadienyl, monomethylcyclopentadienyl, dimethylcyclopentadienyl, trimethylcyclopentadienyl, tetramethylcyclopentadienyl, dimethyldiphenylcyclopentadienyl, diphenylcyclopentadienyl, indenyl, monomethylindenyl, dimethylindenyl, benzoindenyl, 2-methylbenzoindenyl, 2-methyl-4-phenylindenyl, fluorenyl, dimethylfluorenyl, di-tert-butylfluorenyl, cycloheptatrienyl and dibenzocycloheptatrienyl; _R1 and _R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl, o-tolyl, p-tolyl, 3,5-dimethylphenyl or 3,5-di-tert-butylphenyl; or R _R1 and _R2 are linked to form 1,4-butylene, 1,5-pentylene or 1,4-butadienylene; _R3 and _R4 are independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, trimethylsilyl, phenyl, o-tolyl, p-tolyl, 3,5-dimethylphenyl or 3,5-di-tert-butylphenyl; X is selected from methyl, benzyl, neopentyl, trimethylsilylmethyl, dimethylamino, diethylamino, diisopropylamino, bistrimethylsilylamino, methoxy, ethoxy, isopropoxy, chlorine or bromine.

As a further embodiment of the present invention: M is selected from any one of Ti (titanium), Zr (zirconium) and Hf (hafnium); Cp is cyclopentadienyl, tetramethylcyclopentadienyl, dimethyldiphenylcyclopentadienyl, 3,4-diphenylcyclopentadienyl, indenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, 2-methylbenzoindenyl, fluorenyl, 4,7-dimethylfluorenyl or 4,7-di-tert-butylfluorenyl; _R1 and _R2 are independently selected from methyl, ethyl, isopropyl, tert-butyl or phenyl; or _R1 and R2 are selected from methyl, ethyl, isopropyl, tert-butyl or phenyl. ₂ is connected to 1,4-butylene, 1,5-pentylene or 1,4-butadienylene; R3 and R4 are independently selected from hydrogen, methyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl, p-tolyl or 3,5-dimethylphenyl; X is selected from methyl, benzyl, trimethylsilyl, dimethylamino, methoxy, isopropoxy or chlorine.

In the silicon-bridged single metallocene complex containing a neutral ligand side arm provided by the present invention, the ligand preferably has a structure shown in formula L1 to L8;

The specific preparation process of the silicon-bridged single metallocene complex containing a neutral ligand side arm is as follows:

The preparation method of the above-mentioned ligand comprises the following steps:

a) under an inert atmosphere (nitrogen or argon), 1.0 to 1.2 equivalents of n-butyl lithium are added to N,N-disubstituted aromatic amine or P,P-disubstituted o-bromoaryl phosphine, and the mixture is heated under reflux for reaction for 12 to 72 hours to determine whether the corresponding ortho-lithiation product of N,N-disubstituted aromatic amine or P,P-disubstituted aromatic phosphine is generated; or under an inert atmosphere (nitrogen or argon), 1.0 to 1.2 equivalents of n-butyl lithium are added to an ether solution of P,P-dimethyl o-bromophenylphosphine at -75 to -85°C, and the reaction is performed for 12 to 72 hours to generate the corresponding ortho-lithiation product of P,P-dimethylphenylphosphine;

b) adding the obtained lithium salt to 3 to 5 equivalents of dimethyldichlorosilane at -35 to -45°C, heating to room temperature for reaction for 6 to 72 hours, removing the reaction solvent in vacuo, heating to 70°C to remove excess dimethyldichlorosilane in vacuo, and obtaining an intermediate product;

c) Add 1.0 equivalent of cyclopentenyl lithium, substituted cyclopentenyl lithium, indenyl lithium, substituted indenyl lithium, fluorenyl lithium, substituted fluorenyl lithium, cycloheptatrienyl lithium or substituted cycloheptatrienyl lithium to the ether solution of the intermediate product at -30 to 0°C, raise the temperature to room temperature and react for 12 to 72 hours, remove the reaction solvent in vacuo, add 50 to 200 mL of toluene, filter out the inorganic salt generated by the reaction, remove the reaction solvent in vacuo to obtain a crude product, and purify it by reduced pressure distillation to obtain a ligand.

The specific preparation process of the silicon-bridged single metallocene complex containing a neutral ligand side arm is as follows:

Under an inert (nitrogen or argon) atmosphere, the ligand described above is treated with 1.0 to 1.2 equivalents of n-butyl lithium under appropriate conditions, and stirred at room temperature for a certain period of time (0.5 to 2.0 hours) to generate a corresponding ligand lithium salt; under appropriate temperature conditions (-78 to 25°C), the ligand lithium salt generated by the reaction is added to an equivalent amount of a corresponding metal halide ether solution, stirred at room temperature for a certain period of time (10 to 16 hours), and the solvent is evaporated to obtain a crude product, which is recrystallized with a mixed solvent of dichloromethane and n-hexane to obtain a pure silicon-bridged monometallocene trihalide containing a neutral ligand side arm; as needed, the obtained silicon-bridged monometallocene trihalide containing a neutral ligand side arm is reacted with an appropriate alkyl, alkoxy, amino alkali metal or alkaline earth metal reagent to obtain the corresponding metallocene alkyl, alkoxy or amino compound. The corresponding silicon-bridged side-arm monometallocene alkyl complex, alkoxy complex or amino complex containing a neutral ligand can also be generated by reacting the corresponding ligand lithium salt with a trialkyl-substituted metal halide, a trialkoxy-substituted metal halide or a triamino-substituted metal halide in an ether solvent.

It should be noted that the synthesis method of the silicon-bridged single metallocene trihalide containing a neutral ligand side arm is not limited to the aforementioned synthesis method. Those skilled in the art can synthesize the silicon-bridged single metallocene complex containing a neutral ligand side arm by different methods based on existing chemical knowledge.

In some embodiments of the present invention, the silicon-bridged single metallocene complex containing a neutral ligand side arm has a structure shown in formula Cat1 to Cat12;

The present invention also provides a use of the above-mentioned silicon-bridged neutral ligand-containing side-arm single metallocene complex as a catalyst for olefin polymerization.

The present invention also provides a catalyst for olefin polymerization, comprising a main catalyst and a co-catalyst; the main catalyst comprises the silicon-bridged neutral ligand-containing side-arm monometallocene complex described above.

The cocatalyst is an aluminum-containing cocatalyst, which may be various alkylaluminoxanes, trialkylaluminum/organoboron compound composite cocatalysts, alkylaluminum chloride/organoboron compound composite cocatalysts or other reagents that can play the same activation role. Among them, alkylaluminoxanes include (but are not limited to): methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane, isobutylaluminoxane; alkylaluminum chlorides include (but are not limited to): diethylaluminum chloride, ethylaluminum dichloride, sesquiethylaluminum chloride or ethylaluminum dichloride; trialkylaluminums include (but are not limited to): trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum; organic boron compounds include (but are not limited to): B(C ₆ F ₅ ) ₃ , Ph ₃ CB(C ₆ F ₅ ) ₄ , Me ₃ CB(C ₆ F ₅ ) ₄ , PhMe ₂ HNB(C ₆ F ₅ ) ₄ or PhQ ₂ HNB(C ₆ F ₅ ) ₄ (Q is an alkyl group with 2 to 18 carbon atoms). The co-catalyst is preferably at least one of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane, isobutylaluminoxane, and triisobutylaluminum/tetrakis(pentafluorophenyl)borate composite co-catalyst.

The molar ratio of the aluminum atoms in the co-catalyst to the metal atoms in the main catalyst is 1:5 to 10000, preferably 1:60 to 8000, and more preferably 1:100 to 1000.

The molar ratio of the boron atoms in the co-catalyst to the metal atoms in the main catalyst is 1 to 2:1, such as 1 to 1.5:1.

The olefin polymerization catalyst is used to catalyze olefin polymerization reaction, which can be carried out in a solution polymerization process and in a batch reactor or a continuous reaction device.

The olefin polymerization catalyst is used for catalyzing ethylene polymerization to selectively generate 1-octene or C8 or higher α-olefins, specifically, to generate 1-octene or C10 or higher α-olefins.

The catalytic olefin polymerization reaction can be carried out in any solvent that has no adverse effect on the catalyst system, or in the absence of a solvent. The ethylene pressure can be determined as required, such as 0 to 150 atmospheres. The polymerization temperature is -20 to 200°C, preferably -20 to 120°C.

The present invention also provides a method for olefin polymerization, comprising the following steps:

In the presence of ethylene, the main catalyst and the co-catalyst are added into the polymerization kettle and reacted at -20 to 200°C.

The pressure of ethylene can be determined according to needs, for example, 0 to 150 atmospheres.

The reaction time is 5 to 720 minutes. The reaction is a stirring reaction.

After the reaction, ethanol is added to terminate the ethylene polymerization reaction, the temperature of the reaction system is lowered to room temperature, the gas product is collected in a gas metering tank, the liquid product is collected in a conical flask, and the gas and liquid products are measured and then analyzed for components using gas chromatography.

The ethylene oligomerization products can be detected by gas chromatography and analyzed by retention value and peak area.

The present invention has no particular limitation on the sources of the raw materials used above, and they can be generally commercially available.

Beneficial effects of the present invention:

1. The synthesis method of the silicon-bridged single metallocene complex containing a neutral ligand side arm provided by the present invention is simple, low in cost and high in yield;

2. Compared with the chromium-based catalysts with high toxicity, the silicon-bridged single metallocene complex containing a neutral ligand side arm as a catalyst of the present invention is environmentally friendly and has low pollution;

3. The silicon-bridged single metallocene complex containing a neutral ligand side arm of the present invention has a stable structure, good stability, long life and high catalytic activity during the catalytic reaction;

4. The silicon-bridged single metallocene complex containing a neutral ligand side arm of the present invention is used to catalyze the polymerization reaction of ethylene, and has high catalytic activity. By adjusting the substituents on the ligand and the reaction conditions, 1-octene or α-olefins above C8 can be generated with high selectivity. The obtained α-olefin can be used as a plasticizer, a detergent, an emulsifier, a flotation agent, and an adhesive, and can also be synthesized into a lubricating oil base oil through homopolymerization. It can also be used as a comonomer to copolymerize with ethylene, propylene, etc. to synthesize linear low-density polyethylene and polyolefin elastomers, and has a wide range of applications.

Detailed ways

The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

Under an inert atmosphere (nitrogen), 30 mmol of n-butyl lithium was added to 30 mmol of N,N-dimethylaniline and heated under reflux for 12 h to generate the corresponding ortho-lithiation product of N,N-disubstituted aromatic amine;

Add the lithium salt obtained above to 150 mmol of dimethyldichlorosilane at -40°C, heat to room temperature and react for 6 hours, remove the reaction solvent in vacuo, heat to 70°C and remove excess dimethyldichlorosilane in vacuo to obtain an intermediate product;

30 mmol of tetramethylcyclopentenyl lithium was added to the ether solution of the intermediate product at -30°C, and after reacting for 12 hours, the reaction solvent was removed in vacuo, 60 mL of toluene was added, and the inorganic salt generated by the reaction was filtered out, and after the reaction solvent was removed in vacuo, the ligand L1 was obtained by distillation under reduced pressure. ¹ H NMR (400 MHz, CDCl ₃ , 298K) δ7.20-7.13 (m, 1H), 7.02-6.89 (m, 3H), 3.50 (d, 1H), 2.61 (s, 6H), 1.89 (s, 9H), 0.82 (d, 3H) 0.66 (s, 3H), 0.62 (s, 3H) ppm.

Example 2

Under an inert atmosphere (nitrogen), 30 mmol of n-butyl lithium was added to an ether solution of P,P-dimethyl-o-bromophenylphosphine at -78°C, and the mixture was reacted for 12 hours at this temperature to generate the corresponding ortho-lithiation product of P,P-dimethylphenylphosphine;

The lithium salt obtained above was added to 150 mmol of dimethyldichlorosilane at -40°C, the temperature was raised to room temperature for reaction for 6 hours, the reaction solvent was removed in vacuo, and the excess dimethyldichlorosilane was removed in vacuo at 70°C to obtain an intermediate product;

30 mmol of tetramethylcyclopentadienyl lithium was added to the ether solution of the intermediate product at -30°C, and after reacting for 12 hours, the reaction solvent was removed in vacuo, 60 mL of toluene was added, and the inorganic salt generated by the reaction was filtered out. After the reaction solvent was removed in vacuo, the ligand L6 was obtained by distillation under reduced pressure. ¹ H NMR (400 MHz, CDCl ₃ , 298 K) δ 7.42–7.38 (m, 1H), 7.27-6.92 (m, 3H), 3.53 (d, 1H), 2.65 (s, 6H), 1.82 (s, 9H), 0.83 (d, 3H) 0.64 (s, 3H), 0.62 (s, 3H) ppm.

Example 3

Under an inert atmosphere (nitrogen), 10 mmol of n-butyl lithium was added to an ether solution of ligand L1 at -78°C and reacted for 12 hours to obtain a solution of the lithiation product of ligand L1, recorded as solution a1; 30 mmol of methyl lithium ether solution was added to 10 mmol of titanium tetrachloride tetrahydrofuran ether solution at -20°C and reacted for 15 minutes, recorded as solution a2; solution a1 was added to solution a2, the temperature was raised to room temperature and reacted for 6 hours, the reaction solvent was removed in vacuo, 60 mL of toluene was added, the inorganic salts generated by the reaction were filtered out, and after concentration, 20 mL of n-hexane was added for recrystallization to obtain complex Cat1 with a yield of 56.2%. ¹ H NMR (400 MHz, C ₆ D ₆ , 298 K) δ 7.42-7.39 (m, 1H) 6.97-6.89 (m, 3H), 2.46 (s, 6H), 2.07-2.01 (m, 6H), 1.96-1.91 (m, 6H,), 1.38 (t, 9H) ppm.

Example 4

Under an inert atmosphere (nitrogen), 40 mmol of methylmagnesium bromide in ether solution was added to 10 mmol of zirconium tetrachloride in toluene solution at -40°C, reacted for 5 min, 10 mmol of n-butyllithium was added, added to the ether solution of ligand L3, heated to room temperature for 6 h, filtered to remove inorganic salts generated by the reaction, concentrated, added 15 mL of n-hexane for recrystallization, and complex Cat5 was obtained with a yield of 63.1%. ¹ HNMR (400 MHz, C6D6, 298K) δ7.42-7.38 (m, 2H), 7.35-7.22 (m, 4H) 6.97-6.89 (m, 2H), 6.56-6.45 (m, 2H), 3.46-3.38 (m, 4H), 1.96-1.88 (m, 4H), -0.83 (s, 9H) ppm.

Example 5

Under an inert atmosphere (nitrogen), 40 mmol of methylmagnesium bromide in ether solution was added to 10 mmol of hafnium tetrachloride in toluene solution at -40°C, reacted for 5 min, 10 mmol of n-butyllithium was added, added to the ether solution of ligand L6, heated to room temperature and reacted for 6 h, the inorganic salts generated by the reaction were filtered off, concentrated and recrystallized by adding 18 mL of n-hexane to obtain complex Cat12, with a yield of 72.1%. ¹ H NMR (400 MHz, C6D6, 298K) δ7.39-7.32 (m, 1H), 6.99-6.92 (m, 3H), 2.46 (s, 6H), 2.07-2.01 (m, 6H), 1.96-1.91 (m, 6H,), -0.81 (t, 9H) ppm.

Example 6

Heat the polymerization kettle equipped with a magnetic stirrer to 120°C, evacuate for 1h, add 250g toluene, add 1.5mL of MMAO-3A hexane solution with a mass concentration of 5.8wt% and 25g toluene to the feed tank, press the MMAO-3A solution into the reactor with low-pressure ethylene, start stirring, stabilize the reactor temperature at 50°C, increase the ethylene pressure to 3.5Mpa, then add a solution containing 1μmol of the main catalyst Cat1 and 25g toluene into the reactor through the main catalyst feed tank, increase the ethylene pressure to 4MPa, stir the reaction for 30min, add 1mL of ethanol as a terminator, and terminate the ethylene polymerization reaction. Then lower the temperature of the reaction liquid to room temperature, collect the gas product in the gas metering tank, and collect the liquid product in a conical flask.

The gas and liquid products were measured and then analyzed by gas chromatography. The obtained data are shown in Table 1.

Example 7

The reaction temperature was controlled at 70°C, the main catalyst was replaced with Cat2, and the remaining steps were the same as Example 6.

Example 8

The reaction temperature was controlled at 90° C., the main catalyst was replaced with Cat3, n-hexane was selected as the polymerization solvent, and the remaining steps were the same as those in Example 6.

Example 9

The main catalyst was replaced with Cat4, the amount of hexane solution of the co-catalyst MMAO-3A with a mass concentration of 5.8wt% was 2mL, and the remaining steps were the same as those in Example 6.

Example 10

The main catalyst was replaced with Cat5, the ethylene pressure was 3.5 MPa, and the remaining steps were the same as Example 6.

Embodiment 11

The main catalyst was replaced with Cat6, the ethylene pressure was 5 MPa, and the remaining steps were the same as Example 6.

Example 12

The main catalyst was replaced by Cat7, the co-catalyst was replaced by MAO (specifically, 1.2 mL of a 10 wt % MAO toluene solution was used), and the remaining steps were the same as those in Example 6.

Example 13

The main catalyst was replaced with Cat8, and the co-catalysts were MMAO-3A and Ph ₃ CB(C ₆ F ₅ ) ₄ (specifically, 1 mL of 5.8 wt % MMAO-3A hexane solution and 1.2 μmol Ph ₃ CB(C ₆ F ₅ ) ₄ were used. The remaining steps were the same as those in Example 6.

Embodiment 14

The main catalyst was replaced with Cat9, and the co-catalysts were MMAO-3A and Ph ₃ CB(C ₆ F ₅ ) ₄ (specifically, 1 mL of 5.8 wt % MMAO-3A hexane solution and 1.2 μmol Ph ₃ CB(C ₆ F ₅ ) ₄ were used. The remaining steps were the same as those in Example 6.

Embodiment 15

The main catalyst was replaced with Cat10, and the co-catalysts were MMAO-3A and PhMe ₂ HNB(C ₆ F ₅ ) ₄ (specifically, 1 mL of 5.8 wt % MMAO-3A hexane solution and 1.2 μmol PhMe ₂ HNB(C ₆ F ₅ ) ₄ were used. The remaining steps were the same as those in Example 6.

Example 16

The main catalyst was replaced with Cat11, and the co-catalysts were MMAO-3A and (C ₁₇ H ₃₅ ) ₂ CB(C ₆ F ₅ ) ₄ (specifically, 1 mL of 5.8 wt % MMAO-3A hexane solution and 1.2 μmol (C ₁₇ H ₃₅ ) ₂ CB(C ₆ F ₅ ) ₄ were used. The remaining steps were the same as those in Example 6.

Embodiment 17

The main catalyst was replaced with Cat11, and the co-catalysts were MMAO-3A and pC ₈ H ₁₇ Ph ₃ CB(C ₆ F ₅ ) ₄ (specifically, 1 mL of 5.8 wt % MMAO-3A hexane solution and 1.2 μmol pC ₈ H ₁₇ Ph ₃ CB(C ₆ F ₅ ) ₄ were used. The remaining steps were the same as those in Example 6.

Table 1 Ethylene polymerization results

As can be seen from Table 1, the silicon-bridged single metallocene complex containing a neutral ligand side arm provided in the embodiment of the present invention has the characteristics of low usage of co-catalyst, high catalytic activity, good thermal stability and long catalytic life when used. When catalyzing ethylene polymerization, octene products can be obtained with high selectivity and have a wide range of applications.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A silicon-bridged single metallocene complex containing a neutral ligand side arm having a structure shown in Formula I; In Formula I, M is selected from any one of Ti, Zr and Hf; Cp is selected from any one of cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl, substituted fluorenyl, cycloheptatrienyl and substituted cycloheptatrienyl; A is selected from N or P; _R1 and _R2 are independently selected from substituted or unsubstituted alkyl groups with 1 to 30 carbon atoms, cycloalkyl groups with 3 to 30 carbon atoms, substituted or unsubstituted alkenyl groups with 2 to 30 carbon atoms, substituted or unsubstituted aryl groups with 6 to 30 carbon atoms; the substituents include alkyl groups with 1 to 30 carbon atoms, aryl groups with 6 to 30 carbon atoms or silane groups with 1 to 30 carbon atoms; or _R1 and _R2 are linked to form an alkylene group or an alkenylene group; _R3 and _R4 are independently selected from hydrogen, substituted or unsubstituted alkyl having 1 to 30 carbon atoms, cycloalkyl having 3 to 30 carbon atoms, aryl having 6 to 30 carbon atoms; the substituent includes alkyl having 1 to 30 carbon atoms, aryl having 6 to 30 carbon atoms or silyl having 1 to 30 carbon atoms; X is selected from substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms, alkylamine groups having 1 to 30 carbon atoms, alkoxy groups having 1 to 30 carbon atoms or halogen groups; the substituents include alkyl groups having 1 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms or silane groups having 1 to 30 carbon atoms. 2. The silicon-bridged single metallocene complex containing a neutral ligand sidearm according to claim 1, characterized in that M is selected from any one of Ti, Zr and Hf; Cp is any one of cyclopentadienyl, monomethylcyclopentadienyl, dimethylcyclopentadienyl, trimethylcyclopentadienyl, tetramethylcyclopentadienyl, dimethyldiphenylcyclopentadienyl, diphenylcyclopentadienyl, indenyl, monomethylindenyl, dimethylindenyl, benzoindenyl, 2-methylbenzoindenyl, 2-methyl-4-phenylindenyl, fluorenyl, dimethylfluorenyl, di-tert-butylfluorenyl, cycloheptatrienyl and dibenzocycloheptatrienyl; _R1 and R _{R 2} is independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl, o-tolyl, p-tolyl, 3,5-dimethylphenyl or 3,5-di-tert-butylphenyl; or R ₁ and R ₂ are linked to form 1,4-butylene, 1,5-pentylene or 1,4-butadienylene; R ₃ and R ₄ are independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, trimethylsilyl, phenyl, o-tolyl, p-tolyl, 3,5-dimethylphenyl or 3,5-di-tert-butylphenyl; X is selected from methyl, benzyl, neopentyl, trimethylsilylmethyl, dimethylamino, diethylamino, diisopropylamino, bistrimethylsilylamino, methoxy, ethoxy, isopropoxy, chlorine or bromine. 3. The silicon-bridged single metallocene complex containing a neutral ligand sidearm according to claim 1, characterized in that M is selected from any one of Ti, Zr and Hf; Cp is cyclopentadienyl, tetramethylcyclopentadienyl, dimethyldiphenylcyclopentadienyl, 3,4-diphenylcyclopentadienyl, indenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, 2-methylbenzoindenyl, fluorenyl, 4,7-dimethylfluorenyl or 4,7-di-tert-butylfluorenyl; _R1 and _R2 are independently selected from methyl, ethyl, isopropyl, tert _- butyl or phenyl; or R1 and R2 are independently selected from methyl, ethyl, isopropyl, tert-butyl or phenyl. ₂ is connected to 1,4-butylene, 1,5-pentylene or 1,4-butadienylene; R3 and R4 are independently selected from hydrogen, methyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl, p-tolyl or 3,5-dimethylphenyl; X is selected from methyl, benzyl, trimethylsilyl, dimethylamino, methoxy, isopropoxy or chlorine. 4. The silicon-bridged single metallocene complex containing a neutral ligand side arm according to claim 1, characterized in that the silicon-bridged single metallocene complex containing a neutral ligand side arm has a structure shown in formula Cat1 to Cat12; 5. Use of the silicon-bridged single metallocene complex containing a neutral ligand side arm as claimed in any one of claims 1 to 4 as a catalyst for olefin polymerization. 6. A catalyst for olefin polymerization, comprising a main catalyst and a co-catalyst; the main catalyst comprises the silicon-bridged neutral ligand-containing side-arm single metallocene complex according to any one of claims 1 to 4. 7. The catalyst for olefin polymerization according to claim 6, characterized in that the co-catalyst is an alkylaluminoxane, a trialkylaluminum/organoboron compound composite co-catalyst or an alkylaluminum chloride/organoboron compound composite co-catalyst. 8. The catalyst for olefin polymerization according to claim 7, characterized in that the alkylaluminoxane includes: methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, isobutylaluminoxane; the alkylaluminum chloride includes: diethylaluminum chloride, ethylaluminum dichloride, sesquiethylaluminum chloride or ethylaluminum dichloride; the trialkylaluminum includes: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum; The organic boron compounds include: B(C ₆ F ₅ ) ₃ , Ph ₃ CB(C ₆ F ₅ ) ₄ , Me ₃ CB(C ₆ F ₅ ) ₄ , PhMe ₂ HNB(C ₆ F ₅ ) ₄ or PhQ ₂ NB(C ₆ F ₅ ) ₄ , wherein Q is an alkyl group having 2 to 18 carbon atoms. 9. The catalyst for olefin polymerization according to claim 6, characterized in that the molar ratio of aluminum atoms in the co-catalyst to metal atoms in the main catalyst is 1:5 to 10000; The molar ratio of the boron atoms in the co-catalyst to the metal atoms in the main catalyst is 1 to 2:1; The olefin polymerization catalyst is used for catalyzing ethylene polymerization to selectively generate 1-octene or C8 or higher α-olefins. 10. A method for olefin polymerization comprising the steps of: In the presence of ethylene, the main catalyst and the co-catalyst are added into the polymerization kettle and reacted at -20 to 200°C.