Imidazole bridged metallocene, catalyst, preparation and application thereof
Technical Field
The invention relates to a metallocene, a catalyst and preparation and application thereof, in particular to a metallocene catalyst for preparing high-boiling-point solvent oil by butene oligomerization.
Background
The mixed butene is oligomerized to generate C8-C20 isoolefin, and the isoparaffin solvent oil can be produced through hydrogenation. The synthesized isoparaffin solvent oil is a special oil product without harmful substances such as sulfur, aromatic hydrocarbon and the like and peculiar smell, and can be used as a solvent for producing products such as paint, insecticide, printing ink and the like. And can also be used as base oil of low-melting point lubricating oil. Wherein C is 16 And C 20 The equal-high-carbon hydrocarbon is used for ink solvents and the like, and is high-value solvent oil. Ethylene cracking for petroleum refiningThe process and the olefin production process in coal chemical industry can obtain a large amount of butene. The catalyst used in butene oligomerization mainly comprises Ziegler type homogeneous catalyst, solid phosphoric acid, strong acid cation exchange resin, molecular sieve, solid super acid, supported sulfate catalyst, ionic liquid, etc.
The primary product of the early catalyst catalyzed butene oligomerization is the C8 dimer. U.S. Pat. No. 4,83305 uses nickel octoate/ethyl aluminum dichloride/halogenated acetic acid as catalyst to catalyze oligomerization of n-butene to synthesize C 8 Olefins, C 8 The selectivity to olefins was 90%.
The use of nickel salts of mixed acids of haloacetic acid and carboxylic acid [ (R) in U.S. Pat. No. 3,124, 4366087 and U.S. Pat. No. 3,84 1 COO)(R 2 COO)Ni]The catalyst system of ethyl aluminium halide catalyzes butene oligomerization to high-carbon olefin, and the oligomerization product is C 8 The olefin is the main. The catalyst system corresponds to C 8 、C 12 And C 16 The selectivity to olefins was 85%, 12% and 3%, respectively.
European patent EP0091232 uses NiCl 2 (PEt 3 )/EtAlCl 2 As a catalyst, to catalyze the oligomerization of normal butene to high-carbon olefin, C 8 And C 12 The selectivity of the olefin was 50% and 20%, respectively, and the oligomerization product contained a small amount of saturated hydrocarbon in addition to the olefin. Using nickel octoate/EtAlCl 2 In the case of a catalyst, C 8 The selectivity to olefins was 90%.
The addition of a third component, such as a Zn compound, to a Ni/Al-based Ziegler catalyst results in an increase in catalyst activity, but C 12 And C 16 The selectivity of the high-carbon olefin is not improved, C 8 The selectivity of the olefin is still 85-90%.
U.S. Pat. No. 5, 4225743 uses a high carbon fatty acid nickel/fatty acid/water/alkyl aluminum halide catalyst system to catalyze oligomerization of butene fractions containing 5 to 55 weight percent isobutylene to yield C containing small amounts of 2, 4-trimethylpentene 8 An olefin.
U.S. Pat. No. 3,182 uses a mixed acid nickel salt of a carboxylic acid and a halogenated carboxylic acid (R 1 COO)(R 2 COO) Ni/alkyl aluminum halide catalyst system for catalyzing butene alignmentPolymerization, C 8 The selectivity to olefins was 85%, C 12 Olefin selectivity was 12%, C 16 The selectivity to olefins was 3%.
European patent EP0439865 uses NiO/SiO 2 -Al 2 O 3 Supported catalysts. The conversion of butene was over 90% and the C8 olefin selectivity was 85%.
U.S. patent No. 5510555 uses silicon aluminum oxide, and the conversion of isobutene is 99% with 50%, 43% and 5% selectivity of dimer, trimer and tetramer in this order.
Sulfate supported catalyst Fe 2 (SO 4 ) 3 (NiSO 4 )/γ-Al 2 O 3 Catalytic oligomerization of isobutene. The reaction was carried out at 50℃for 5 hours with an isobutene conversion of 85% and a selectivity to dimer, trimer and tetramer of 50%, 40% and 5% in this order. Whereas WOx/ZrO developed by Lee J S et al, korean institute of chemical technology 2 The catalyst can catalyze isobutene oligomerization reaction at 70 ℃, the conversion rate can reach 100%, and the selectivity of dimer, trimer and tetramer is 5%, 80% and 15% in sequence.
The Nafion resin has isobutene oligomerization performance, the conversion rate of isobutene is 90 percent at 90 ℃, and the selectivity of diisobutene, triisobutene and tetraisobutene is 25.3 percent, 65.2 percent and 8.8 percent respectively.
The beta-25 molecular sieve and the ferrierite molecular sieve have excellent isobutene oligomerization performance. The conversion of isobutene over the beta-25 molecular sieve was 100% at 70℃and 1.5 MPa, with selectivities of diisobutene, triisobutene and tetraisobutene of 10%, 60% and 30%, respectively. Under the same reaction conditions, the conversion of isobutene on the ferrierite molecular sieve was 100% and the selectivities of diisobutene, triisobutene and tetraisobutene were 8%, 80% and 10%, respectively. The molecular sieve is renewable.
Ionic liquids such as (C) 2 H 5 ) 3 NHCl-xFeCl 3 The ionic liquid catalyzes isobutene oligomerization, and when the reaction is carried out for 60 min at 40 ℃, the isobutene conversion rate reaches 86%, and the selectivity of diisobutene, triisobutene, tetraisobutene and pentaisobutene is 21.51%, 53.91%, 19.92% and 4.66% respectively.
The existing catalyst formulation and technology can not obtain high proportion of C 16 And C 20 High-value solvent oil cannot be produced by high-carbon olefin, and the value of the special solvent oil is reduced.
Disclosure of Invention
In order to solve the above-mentioned problems, it is an object of the present invention to provide a metallocene, a catalyst composition, its preparation and use.
According to a first aspect of the present invention there is provided an imidazole bridged metallocene.
An imidazole bridged metallocene has the following structural general formula:
wherein R1, R2, R3 may be H, CH 3 、C 2 H 5 、C 3 H 7 、C 6 H 5 One of the alkyl groups, preferably H, CH 3 The method comprises the steps of carrying out a first treatment on the surface of the M may be Zr, ti, hf, etc., preferably Zr; z may be Cl, br, I, CH 3 、C 2 H 5 、C 3 H 7 、C 4 H 9 Etc., preferably Cl, br, I, C 2 H 5 . M is the valence-3 of the M metal. n is CH 2 N is 1 to 3, preferably 1.
According to a second aspect of the present invention, there is also provided a process for the preparation of an imidazole bridged metallocene.
The preparation method comprises the following steps:
(1) Cyclopentadiene is added into a solvent, cooled to-40-0 ℃, then added with lithium alkyl dropwise, stirred for 2-24h, then added with dihaloalkane and stirred for 1-24 h continuously; distilling and separating to obtain halogenated alkyl cyclopentadiene;
(2) Adding imidazole, haloalkylcyclopentadiene obtained in the step (1) and alkali into acetonitrile, and reacting at 50-80 ℃; filtering, and separating liquid to obtain N, N-dicyclopentadiene alkyl imidazole;
(3) Dissolving N, N-dicyclopentadiene alkyl imidazole in an organic solvent, cooling to-40-0 ℃, dropwise adding alkyl lithium under stirring, and stirring for reacting for 2-24 hours; adding zirconium tetrachloride into the mixture, and stirring the mixture for 24 to 48 hours;
(4) And (3) pumping the organic solvent in the solution obtained in the step (3), adding methyl chloride for dissolution, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged metallocene.
Further, the molar ratio of cyclopentadiene, butyllithium and dihaloalkane in the step (1) is 1 (0.8-1.2): 0.8-1.2. The solvent is selected from common organic solvents in the field, such as at least one selected from tetrahydrofuran, diethyl ether, petroleum ether, N-dimethylformamide and acetonitrile, preferably tetrahydrofuran.
Further, the alkyl lithium in step (1) includes ethyl lithium, propyl lithium, butyl lithium.
Further, the dihaloalkanes in the step (1) include 1, 2-dihaloethane, 1, 3-dihalopropane, 1, 4-dihalobutane, 1, 5-dihalopentane, etc., and the halogen is chlorine, bromine, iodine. Preferably dihalobutane, more preferably 1, 4-dichlorobutane.
In the step (2), the mole ratio of imidazole, halogenated alkyl cyclopentadiene and alkali is 1 (1.8-2.4), the weight ratio of imidazole to acetonitrile is 1 (10-50). The reaction time in step (2) is generally 10 to 24 hours. The separation is an operation well known in the art, such as rotary distillation may be selected.
Further, the alkali in the step (2) is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.
Further, in the step (3), the molar ratio of N, N-dicyclopentadiene alkyl imidazole, N-butyl lithium and zirconium tetrachloride is 1 (2.8-3.5): 0.8-1.2); the weight ratio of the N, N-dicyclopentadiene alkyl imidazole to the tetrahydrofuran is 1 (10-50). The organic solvent in the step (3) is selected from solvents conventional in the art, such as tetrahydrofuran, diethyl ether, petroleum ether, N-dimethylformamide, and acetonitrile. The alkyl lithium comprises at least one of ethyl lithium, propyl lithium and butyl lithium.
Further, in the step (4), the weight ratio of the N, N-dicyclopentadiene alkyl imidazole to the methylene dichloride is 1 (30-80).
Further, the methyl chloride in the step (4) comprises one of dichloromethane, chloroform and carbon tetrachloride.
According to a third aspect of the present invention there is provided a metallocene catalyst comprising an imidazole-bridged metallocene as hereinbefore described.
A metallocene catalyst comprising an imidazole-bridged metallocene, a metal alkyl, and a solvent; imidazole bridged metallocene is used as a main catalyst, and alkyl metal is used as a cocatalyst; wherein the imidazole bridged metallocene: the molar ratio of the alkyl metal is 1 (5-500), preferably 1 (10-100), and the solvent accounts for 40-90 wt%, preferably 60-80% by weight of the catalyst (composition).
Further, the metal alkyl includes at least one of magnesium alkyl, aluminum alkyl and zinc alkyl. The alkyl magnesium is at least one selected from diethyl magnesium, dipropyl magnesium, diisopropyl magnesium and dibutyl magnesium, the alkyl aluminum is at least one selected from trimethyl aluminum, triethyl aluminum, tripropyl aluminum, triisopropyl aluminum, tributyl aluminum, triisobutyl aluminum and the like, and the alkyl zinc is at least one selected from diethyl zinc, dipropyl zinc, diisopropyl zinc, dibutyl zinc, diisobutyl zinc and the like, preferably the alkyl aluminum is more preferably the triisobutyl aluminum.
Further, the solvent is tetrahydrofuran, acetonitrile, toluene, alkylated oil, etc. Preferably an alkylate.
According to a fourth aspect of the present invention, the present invention also provides a method for preparing the above metallocene catalyst.
The method comprises the following steps: adding imidazole bridged metallocene and aluminum alkyl into a solvent, and stirring uniformly to obtain the metallocene catalyst.
According to a fifth aspect of the present invention there is also provided a process for the oligomerization of n-butene wherein the metallocene catalyst described hereinbefore is employed.
An oligomerization of n-butene comprising the following: after the reactor is deoxidized, butene and a catalyst composition are added into the reactor, polymerization reaction is carried out at a certain reaction temperature and reaction pressure, and the reaction product is separated to obtain polyolefin.
Further, the reaction temperature is 40 to 100 ℃, preferably 60 to 80 ℃, and the reaction time is generally 1 to 8 hours, preferably 2 to 4 hours; the reaction pressure is the saturated vapor pressure of each component in the reaction system at the reaction temperature, so that the butene reactant is kept in a liquid state without external pressure.
Further, the reactor deoxygenation is an operation well known to those skilled in the art.
Compared with the prior art, the invention has the following characteristics:
1. the main catalyst adopts a novel metallocene structure, effectively regulates and controls the electron and space effects of the metallocene, and greatly improves the catalytic activity of the metallocene. Imidazole has electron-rich effect on zirconium metal, stabilizes the cationic property of zirconium metal, and promotes initiation and chain growth of olefin polymerization. Meanwhile, the weak covalent bond between the two has the advantages of increasing bond length, not significantly limiting the steric hindrance of the zirconocene, and being beneficial to multiolefin polymerization. Meanwhile, the imidazole ionic liquid group and the metallocene group in the novel metallocene structure have synergistic catalysis, and the zirconium metal has negative electron effect on imidazole, so that the electropositivity of imidazole cations is improved, and the initiation capability of imidazole on olefin polymerization is improved. The space distance between the two active centers is proper, so that the bimolecular reaction of olefin dimers can be promoted, and the selectivity of the high polymer is improved. The catalyst composition provided by the invention can obviously improve the butene oligomerization product C 16 And C 20 Selectivity and yield of isoparaffin.
2. On the premise of keeping equivalent catalytic effect, the cost of the catalyst is obviously reduced.
3. The catalyst has low toxicity, low sensitivity to water and air and environmental friendliness.
Detailed Description
The technical scheme of the invention is further described below with reference to specific embodiments.
The imidazole bridged metallocenes prepared in examples were determined in their structure by elemental analysis methods. The elemental detection of the catalyst was performed by using a ZSX100e type X-ray fluorescence spectrometer manufactured by Japanese national institute of technology.
The reagents used in the examples were derived from carbofuran and were chemically pure in purity. All liquid solvents were purified in a solvent purification unit and then reused.
Example 1
(1) 66g of cyclopentadiene (66 g/mol) were added to tetrahydrofuran, cooled to-40℃and then 64g of butyllithium (64 g/mol) were added dropwise, stirred for 6 hours, followed by 127g of 1, 4-dichlorobutane (127 g/mol). Stirring was continued for 10h.
(2) 34g of imidazole (68 g/mol) and 156g of chlorobutyl cyclopentadiene (156 g/mol) and 106g of sodium carbonate (106 g/mol) are added into 680g of acetonitrile, heated and stirred, the temperature is 70 ℃, the reaction is carried out for 24 hours, solids are removed by filtration, and the liquid is subjected to rotary distillation separation to obtain N, N-dicyclopentadiene butyl imidazole.
(3) 86g of N, N-dicyclopentadiene-butylimidazole (345 g/mol) were dissolved in 3450g of tetrahydrofuran and cooled to-40 ℃. 48g of n-butyllithium (64 g/mol) was then added dropwise thereto with stirring, and the reaction was stirred for 5 hours. 58g of zirconium tetrachloride (233 g/mol) was then added thereto and stirred for 24 hours.
(4) And pumping out tetrahydrofuran in the solution, adding 6030g of dichloromethane for dissolution, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged zirconocene.
The obtained product imidazole bridged zirconocene is characterized by an elemental analysis method and has the following structural general formula:
wherein R1, R2 and R3 are H; m is Zr; z is Cl, m is 1, n is 2.
The element composition of the synthesized imidazole bridged zirconocene is N2C21ZrCl2H26, and the theoretical weight percentage composition is 5.98wt% N, 53.85wt% C, 19.44wt% Zr, 15.17wt% Cl, and 5.56wt% H. As can be seen from the elemental analysis of Table 1, the elemental composition of the synthesized imidazole bridged zirconocene conforms to the theoretical composition, indicating that the zirconocene was synthesized.
Example 2
(1) 66g of cyclopentadiene (66 g/mol) were added to tetrahydrofuran, cooled to-40℃and then 76.8g of butyllithium (64 g/mol) were added dropwise, stirred for 3h and then 127g of 1, 4-dichlorobutane (127 g/mol) were added. Stirring was continued for 10h. And distilling and separating to obtain chloro-butyl cyclopentadiene.
(2) 34g of imidazole (68 g/mol) and 187g of chlorobutyl cyclopentadiene (156 g/mol) and 159g of sodium carbonate (106 g/mol) were added to 1700g of acetonitrile, heated and stirred at 50 ℃ for 24 hours, the solids were removed by filtration, and the liquid was subjected to rotary distillation to obtain N, N-dicyclopentadiene-butylimidazole.
(3) 86g of N, N-dicyclopentadiene-butylimidazole (309 g/mol) were dissolved in 4299g of tetrahydrofuran and cooled to-40 ℃. After stirring, 56g of n-butyllithium (64 g/mol) was added dropwise thereto, and the reaction was stirred for 5 hours. 70g of zirconium tetrachloride (233 g/mol) was then added thereto and stirred for 24 hours.
(4) And pumping tetrahydrofuran in the solution, adding 6878g of dichloromethane to dissolve, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged zirconocene.
The obtained product imidazole bridged zirconocene is characterized by an elemental analysis method and has the following structural general formula:
wherein R1, R2 and R3 are H; m is Zr; z is Cl. m is 1.n is 2.
The element composition of the synthesized imidazole bridged zirconocene is N2C21ZrCl2H26, and the theoretical weight percentage composition is 5.98wt% N, 53.85wt% C, 19.44wt% Zr, 15.17wt% Cl, and 5.56wt% H. As can be seen from the elemental analysis of Table 1, the elemental composition of the synthesized imidazole bridged zirconocene conforms to the theoretical composition, indicating that the zirconocene was synthesized.
Example 3
(1) 66g of cyclopentadiene (66 g/mol) was added to tetrahydrofuran, cooled to-40℃and then 51.2g of butyllithium (64 g/mol) was added dropwise, stirred for 3 hours, followed by 101.6g of 1, 4-dichlorobutane (127 g/mol). Stirring was continued for 10h.
(2) 34g of imidazole (68 g/mol) and 140g of chlorobutyl cyclopentadiene (156 g/mol) and 53g of sodium carbonate (106 g/mol) were added to 340g of acetonitrile, heated and stirred, reacted at 80 ℃ for 24 hours, filtered to remove solids, and the liquid was subjected to rotary distillation to separate N, N-dicyclopentadiene-butyl imidazole.
(3) 86g of N, N-dicyclopentadiene-butylimidazole (309 g/mol) were dissolved in 860g of tetrahydrofuran and cooled to-40 ℃. After stirring, 44.8g of n-butyllithium (64 g/mol) was added dropwise thereto, and the reaction was stirred for 5 hours. 46.6g of zirconium tetrachloride (233 g/mol) was then added thereto and stirred for 24 hours.
(4) And pumping out tetrahydrofuran in the solution, adding 2579g of dichloromethane for dissolution, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged zirconocene.
The obtained product imidazole bridged zirconocene is characterized by an elemental analysis method and has the following structural general formula:
wherein R1, R2 and R3 are H; m is Zr; z is Cl. m is 1 and n is 2.
The element composition of the synthesized imidazole bridged zirconocene is N2C21ZrCl2H26, and the theoretical weight percentage composition is 5.98wt% N, 53.85wt% C, 19.44wt% Zr, 15.17wt% Cl, and 5.56wt% H. As can be seen from the elemental analysis of Table 1, the elemental composition of the synthesized imidazole bridged zirconocene conforms to the theoretical composition, indicating that the zirconocene was synthesized.
Example 4
(1) 66g of cyclopentadiene (66 g/mol) were added to tetrahydrofuran, cooled to-40℃and then 70g of butyllithium (64 g/mol) were added dropwise, stirred for 3h and 114g of 1, 4-dichlorobutane (127 g/mol) were then added. Stirring was continued for 10h. And distilling and separating to obtain chloro-butyl cyclopentadiene.
(2) 34g of imidazole (68 g/mol) and 163.8g of chlorobutyl cyclopentadiene (156 g/mol) and 133g of sodium carbonate (106 g/mol) were added to 1360g of acetonitrile, the mixture was heated and stirred at 80℃for 24 hours, the solid was removed by filtration, and the liquid was subjected to rotary distillation to obtain N, N-dicyclopentadiene-butylimidazole.
(3) 86g of N, N-dicyclopentadiene-butylimidazole (309 g/mol) were dissolved in 2579g of tetrahydrofuran and cooled to-40 ℃. After stirring, 49.6g of n-butyllithium (64 g/mol) was added dropwise thereto, and the reaction was stirred for 5 hours. 64g of zirconium tetrachloride (233 g/mol) was then added thereto and stirred for 24 hours.
(4) And pumping tetrahydrofuran in the solution, adding 4298g of dichloromethane for dissolution, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged zirconocene.
The obtained product imidazole bridged zirconocene is characterized by an elemental analysis method and has the following structural general formula:
wherein R1, R2 and R3 are H; m is Zr; z is Cl. m is 1.n is 2.
The element composition of the synthesized imidazole bridged zirconocene is N2C21ZrCl2H26, and the theoretical weight percentage composition is 5.98wt% N, 53.85wt% C, 19.44wt% Zr, 15.17wt% Cl, and 5.56wt% H. As can be seen from the elemental analysis of Table 1, the elemental composition of the synthesized imidazole bridged zirconocene conforms to the theoretical composition, indicating that the zirconocene was synthesized.
Example 5
(1) 108g of 1,2, 3-trimethyl-cyclopentadiene (108 g/mol) were added to tetrahydrofuran, cooled to-40℃and 70g of butyllithium (64 g/mol) were then added dropwise, stirred for 3h, followed by 101g of 1, 3-dichloropropane (101 g/mol). Stirring was continued for 10h. And distilling and separating to obtain the 1,2, 3-trimethyl-4-chloropropyl cyclopentadiene.
(2) 34g of imidazole (68 g/mol) and 193.1g of 1,2, 3-trimethyl-4-chloropropyl cyclopentadiene (184 g/mol) and 133g of sodium carbonate (106 g/mol) are added into 1360g of acetonitrile, heated and stirred, reacted for 24 hours at 80 ℃, solid is removed by filtration, and the liquid is subjected to rotary distillation to obtain N, N-bis (1, 2, 3-trimethyl-cyclopentadienyl-butyl) imidazole.
(3) 93.8g of N, N-bis (1, 2, 3-trimethyl-cyclopentadienyl-butyl) imidazole (337 g/mol) were dissolved in 2579g of tetrahydrofuran and cooled to-40 ℃. After stirring, 49.6g of n-butyllithium (64 g/mol) was added dropwise thereto, and the reaction was stirred for 5 hours. 64g of zirconium tetrachloride (233 g/mol) was then added thereto and stirred for 24 hours.
(4) And pumping tetrahydrofuran in the solution, adding 4298g of dichloromethane for dissolution, carrying out solid-liquid separation, and carrying out distillation concentration to obtain the imidazole bridged zirconocene.
The obtained product imidazole bridged zirconocene is characterized by an elemental analysis method and has the following structural general formula:
wherein R1, R2 and R3 are CH 3 The method comprises the steps of carrying out a first treatment on the surface of the M is Zr; z is Cl. m is 1.n is 1.
The element composition of the synthesized imidazole bridged zirconocene is N2C23ZrCl2H30, and the theoretical weight percentage composition is 5.64wt% N:55.66wt% C:18.35wt% Zr:14.31wt% Cl:6.05wt% H. As can be seen from the elemental analysis of Table 1, the elemental composition of the synthesized imidazole bridged zirconocene conforms to the theoretical composition, indicating that the zirconocene was synthesized.
TABLE 1 elemental analysis (wt%) of metallocene
Example 6
4.68g of the metallocene (468 g/mol) prepared in example 1 and 39.6g of tributylaluminum (198 g/mol) were added to 103g of an alkylate, and stirred well to obtain a catalyst composition. Metallocenes: the molar ratio of the alkyl metal is 1:20. The solvent was 70wt% in the catalyst.
Example 7
4.68g of the metallocene (468 g/mol) prepared in example 1 and 139g of tributylaluminum (198 g/mol) were added to 574g of the alkylate, and stirred well to obtain a catalyst composition. Metallocenes: the molar ratio of the alkyl metal was 70. The solvent was 80wt% in the catalyst.
Example 8
4.68g of the metallocene (468 g/mol) prepared in example 1 and 198g of tributylaluminum (198 g/mol) were added to 1824g of the alkylate, and stirred well to obtain a catalyst composition. Metallocenes: the molar ratio of the alkyl metal is 1:100. The solvent content in the catalyst was 90wt%.
Example 9
4.68g of the metallocene (468 g/mol) prepared in example 1 and 19.8g of tributylaluminum (198 g/mol) were added to 36.7g of an alkylate, and stirred well to obtain a catalyst composition. Metallocenes: the molar ratio of the alkyl metal is 1:10. The solvent content in the catalyst was 60wt%.
Examples 10 to 13
The oligomerization of n-butene is carried out in an autoclave equipped with electromagnetic stirring. Before the reaction, the autoclave is cleaned, heated and vacuumized in an oil bath at 140 ℃ to negative pressure, and kept for 0.5h. The autoclave was charged with high purity nitrogen and then evacuated, and the above was repeated three times. The reaction vessel was cooled to the reaction temperature. High-purity nitrogen is filled into the autoclave, and the pressure is 3MPa. Heating in oil bath, and stirring. The liquid butene steel cylinder and the catalyst feeding tank are respectively connected with a metering pump, and butene and catalyst are led into the autoclave through the metering pump.
Specific process conditions and reaction results are shown in Table 2.
TABLE 2 Process conditions and results
Comparative example 1
The existing metallocene catalyst adopts n-butyl cyclopentadiene zirconium chloride metallocene and methylaluminoxane to catalyze butene alignmentPolymerization, 4.06g of n-butylcyclopentadiene zirconium chloride metallocene and 58g of methylaluminoxane, and 14L of liquid butene were separately charged into an autoclave, stirred and heated. The reaction conditions were 3MPa, 70℃and 2 hours. Conversion of butene was 49%, C 16 +C 20 The total selectivity was 38%.
By comparison of the inventive graded catalyst with existing catalysts, it was found that the activity and the total c16+c20 selectivity of the inventive catalyst composition were significantly better than the existing catalysts.