Modified alkyl aluminoxane for alpha-olefin polymerization and preparation method thereof
Through sol-gel method and surface modification technology, combined with microwave and ultrasonic assisted synthesis, the hazards and control problems in the preparation process of modified alkyl aluminoxane are solved, and efficient and safe preparation of alkyl aluminoxane is achieved. , the application in metallocene catalysts significantly improves the catalytic activity and product quality.
Patent Information
- Application Number
- CN202411578489.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-01-17
AI Technical Summary
The existing preparation methods for modified alkyl aluminoxanes have problems such as process hazard, difficulty in control, low yield and poor economic performance. In particular, trimethylaluminum reacts violently with water, resulting in high equipment quality requirements and dangerous production process.
Silica-aluminum gel was prepared by sol-gel method, and the particle size and pore size of FER zeolite molecular sieve were regulated through the synergistic action of surfactant and structural guide agent, surface modification was performed using organochlorosilane or fatty amine, combined with microwave and ultrasound Assisted synthesis, a mild hydrolysis reaction of alkylaluminoxane is achieved to prepare modified alkylaluminoxane.
The efficiency of alkylaluminum hydrolysis reaction is improved, the operation is simplified, the preparation efficiency is enhanced, and the activity and product quality of the catalyzed ethylene/1-octene copolymerization reaction is successfully applied in metallocene catalysts.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metal organic compounds, and in particular relates to a preparation method and application of modified alkylaluminoxane for α-olefin polymerization. Background Art
[0002] α-olefin polymerization refers to the process in which α-olefin (such as 1-butene, 1-hexene, etc.) monomers form polymers through a coordination insertion polymerization mechanism under the action of a catalyst. The reaction mechanism is that the C=C double bond in the α-olefin coordinates with the transition metal atom in the catalyst, and then the α-olefin monomer is translocated and inserted into the metal-carbon bond to form a high molecular weight polymer (Xu Di, Dai Li, Yao Wenzhi, Yang Guangrui, Wang Hairong, Song Pengfei, Zhu Yansong. Research Progress in Olefin Polymerization Catalysts [J]. Applied Chemistry, 2022, 39(3): 355-373.). The polymerization of α-olefins usually needs to be carried out under the action of transition metal catalysts and co-catalysts, among which transition metal catalysts mainly include Ziegler-Natta catalysts, metallocene catalysts, late transition metal catalysts and non-metallocene catalysts, etc.; co-catalysts mainly include alkylaluminoxanes (such as MAO), organic boron compounds (such as B(C6F5)3), isobutylaluminum / phenylboron and isobutylaluminum supported by magnesium chloride, etc. These co-catalysts play a key role in the polymerization of α-olefins. They can not only improve the activity of the catalyst, but also improve the properties of the polymer, such as molecular weight distribution, molecular structure, etc. Therefore, by selecting a suitable co-catalyst, it is possible to optimize the polymerization process of α-olefins, improve the yield and quality of the product, and reduce the post-processing procedures and play a role in energy conservation and environmental protection.
[0003] As the most important co-catalyst in the polymerization of α-olefins, modified alkyl aluminoxane (such as methyl aluminoxane, MAO) plays the role of activating the main catalyst and forming a cationic active center with the main catalyst and maintaining the stability of the active center. However, the common preparation methods of modified alkyl aluminoxanes currently still have a series of problems such as process danger, difficult control, low yield and poor economy; in particular, trimethylaluminum (TMA) reacts very violently with water, has high requirements on equipment quality and is highly dangerous in the production process (Zhang Mengbo, Lou Linjin, Feng Yirong, Zheng Yuting, Zhang Haomiao, Wang Jingdai, Yang Yongrong. Research Progress in Alkyl Aluminoxane Synthesis Technology [J]. Journal of Chemical Industry, 2023, 74 (02): 525-534.). In summary, modified alkyl aluminoxane plays a vital role in the polymerization of α-olefins, and it is very necessary to explore and improve its preparation method to improve its synthesis efficiency and application performance to meet the needs of industrial production. Summary of the invention
[0004] In view of the shortcomings of the existing preparation methods of modified alkyl aluminoxane, the purpose of the present invention is to provide a preparation method of modified alkyl aluminoxane for α-olefin polymerization and its application.
[0005] In order to achieve the above object, the solution of the present invention is:
[0006] A method for preparing a modified alkylaluminoxane for α-olefin polymerization, characterized in that it specifically comprises the following steps:
[0007] (1) adding a silicon source and an alkali into water and stirring them evenly, then adding a surfactant, stirring until the surfactant is dissolved, then adding an aluminum source and a structure directing agent, and then continuing to stir the resulting mixture to react to obtain a silicon-alumina sol;
[0008] (2) heating and aging the silica-alumina sol prepared in step (1) to obtain a silica-alumina gel;
[0009] (3) crystallizing the silica-alumina gel obtained in step (2), filtering, washing and drying the obtained solid, and removing the surfactant and the structure directing agent from the dried solid to obtain a FER zeolite molecular sieve;
[0010] (4) adding the FER zeolite molecular sieve prepared in step (3) into an organic solution, and then adding a surface modifier to react to obtain a surface-modified FER zeolite molecular sieve;
[0011] (5) activating the surface-modified FER zeolite molecular sieve obtained in step (4) to obtain an activated molecular sieve;
[0012] (6) adding the activated molecular sieve prepared in step (5) to a toluene solution containing alkyl aluminum, stirring the obtained mixture for reaction and filtering it, and collecting the residue after repeatedly distilling the obtained filtrate under reduced pressure to obtain the modified alkyl aluminumoxane for α-olefin polymerization.
[0013] Furthermore, the silicon source in step (1) is one of sodium silicate or silicon tetrachloride; and the alkali is one of sodium hydroxide or potassium hydroxide.
[0014] Furthermore, the aluminum source in step (1) is composed of one or more of aluminum sulfate, sodium aluminate, aluminum nitrate or aluminum trichloride.
[0015] Furthermore, the structure directing agent in step (1) is composed of one or more of pyrrolidine, pyridine, piperidine, ethylenediamine, triethylamine, isopropylamine or cyclohexylamine.
[0016] Furthermore, the surfactant described in step (1) is composed of one or more of hexadecyltrimethylammonium bromide, hexadecylmethylpiperidinium bromide or hexadecyltrimethylammonium hydroxide.
[0017] Furthermore, the heating aging method described in step (2) is microwave heating aging.
[0018] Furthermore, the surface modifier described in step (4) is one of an organochlorosilane or a fatty amine.
[0019] Furthermore, the activation condition in step (5) is heating in water vapor.
[0020] Furthermore, the alkyl aluminum described in step (6) is formed by a mixture of one or both of triethyl aluminum and triisobutyl aluminum.
[0021] Application of modified alkylaluminoxane prepared by the aforementioned method for preparing modified alkylaluminoxane for α-olefin polymerization.
[0022] The principle of the method provided by the present invention is as follows:
[0023] The main principle of the preparation method of modified alkylaluminoxane for α-olefin polymerization provided by the present invention is as follows: first, an inorganic silicon source and an aluminum salt are used to prepare a silica-alumina gel by a sol-gel method, then the obtained silica-alumina gel is crystallized and then organic substances such as surfactants and structure-directing agents are removed to prepare a FER zeolite molecular sieve, then the FER zeolite molecular sieve is modified by a surface modifier to prepare a surface-modified FER molecular sieve, and finally the obtained surface-modified FER molecular sieve is activated and can be directly used for alkylaluminum hydrolysis to prepare modified alkylaluminoxane. In the process of preparing the silica-alumina gel, the particle size and pore size of the prepared FER molecular sieve can be regulated by the synergistic effect of the surfactant and the structure-directing agent and by adjusting the synthesis conditions; next, the surface of the molecular sieve is modified by using an organic chlorosilane or aliphatic amine with a hydrophobic function as a modifier, and then the conditions that are most conducive to the reaction of alkylaluminum molecules with water molecules to form alkylaluminoxane molecules can be explored by changing the type and amount of the modifier.
[0024] Compared with the existing method, the gain effect of the present invention is as follows:
[0025] 1. The surface-modified FER zeolite molecular sieve prepared by the method for preparing modified alkylaluminoxane for α-olefin polymerization provided by the present invention can undergo mild hydrolysis reaction with alkylaluminum solution, effectively improving the efficiency of preparing alkylaluminoxane by hydrolysis reaction of alkylaluminum.
[0026] 2. The preparation method of modified alkylaluminoxane for α-olefin polymerization provided by the present invention uses microwave-assisted synthesis and ultrasound-assisted synthesis methods to greatly improve the efficiency of preparing FER zeolite molecular sieves, and has the advantages of mild reaction conditions and simple operation.
[0027] 3. The modified alkylaluminoxane for α-olefin polymerization obtained by the preparation method provided by the present invention can be successfully used to prepare metallocene catalysts. The catalyst system composed of the obtained metallocene catalyst as the main catalyst and the modified alkylaluminoxane as the co-catalyst can be used to catalyze ethylene / 1-octene copolymerization. The catalytic reaction results are: the catalyst polymerization activity is 1.91×10 3 (gCopolymer:gcat -1 h -1 ); Mw is 12.03×10 4 , Mn is 5.17×10 4 , PDI is 2.33; the density of the obtained copolymer is 0.901 g / cm 3 ; The insertion rate of 1-octene in the copolymer is 2.51%; The melting point Tm of the obtained copolymer is 112°C. DETAILED DESCRIPTION
[0028] The present invention is further described in detail below in conjunction with the embodiments. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. The specific quality, reaction time and temperature, process parameters, etc. in the examples are only examples within the appropriate ranges. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present invention all belong to the scope of protection of the present invention.
[0029] All reagents used were commercial reagents unless otherwise specified and were not further purified before use.
[0030] The reagent hexadecylmethylpiperidinium bromide used in the examples of the present invention is a non-commercial reagent, and the specific synthesis steps are as follows:
[0031] 3 g of 1-bromohexadecane and 1.2 g of N-methylpiperidine were added to 15 mL of acetonitrile and stirred evenly, and then the resulting solution was heated at 80 ° C for 24 h. After the reaction was completed, the reaction solution was concentrated using a rotary evaporator, 10 mL of diethyl ether was added to the resulting concentrated solution, and the resulting white precipitate product was collected by filtration, and the resulting solid was washed 3 times with 5 mL of diethyl ether. The washed solid was placed in a vacuum drying oven and vacuum dried at 50 ° C for 4 h. The resulting white solid was the final product, hexadecylmethylpiperidinium bromide.
[0032] Embodiment 1:
[0033] The preparation method of ethylaluminoxane specifically comprises the following steps:
[0034] (1) Under stirring, 6.3 g of sodium silicate and 0.2 g of sodium hydroxide were added to 15 mL of deionized water, stirred evenly, and then 0.18 g of hexadecyltrimethylammonium bromide was added. Stirring was continued until the hexadecyltrimethylammonium bromide was dissolved, and then 0.41 g of sodium aluminate was added. Then, 2.5 mL of ethylenediamine was slowly added dropwise. The resulting mixture was stirred and reacted for 1 hour and then allowed to stand to obtain a silica-alumina sol;
[0035] (2) placing the silica-alumina sol prepared in step (1) into a microwave reactor for aging reaction, setting the microwave power to 450 W, and aging the reaction at a reaction temperature of 80° C. for 1.5 h to obtain a silica-alumina gel;
[0036] (3) placing the silica-alumina gel obtained in step (2) into an ultrasonic reactor for crystallization: controlling the ultrasonic power to 300 W, the ultrasonic frequency to 80 kHz, the crystallization temperature to 90° C., and the crystallization time to 45 min; after the crystallization is completed, filtering and washing the obtained solid product with 5 mL of deionized water and 5 mL of anhydrous ethanol for more than 3 times in sequence, and then placing it in a vacuum drying oven and drying it at 110° C. for 6 h; transferring the dried solid into a dielectric barrier discharge device, and treating it for 35 min in an air atmosphere at a voltage of 220 V and a current of 3.5 A to remove organic matter such as surfactants and structure directing agents to obtain FER zeolite molecular sieve;
[0037] (4) adding the FER zeolite molecular sieve prepared in step (3) to 50 mL of toluene, and then adding 2.3 mL of trimethylchlorosilane, and heating the resulting mixture at 30° C. for 24 h; after the reaction, filtering and washing the resulting solid with a 95% ethanol solution until no chloride ions remain (detecting the filtrate with a 0.1 mol / L AgNO3 solution until no precipitation occurs); placing the washed solid in a vacuum drying oven and vacuum drying at 80° C. for 6 h to obtain a trimethylchlorosilane-modified FER zeolite molecular sieve;
[0038] (5) placing the trimethylchlorosilane-modified FER zeolite molecular sieve obtained in step (4) in water vapor at 120° C. for activation, controlling the flow rate of the water vapor to 50 mL / min, and obtaining an activated molecular sieve after 45 min of activation. The obtained molecular sieve is recorded as TMC-FER-Z-1;
[0039] (6) Under an ice bath, 0.5 g of the activated molecular sieve TMC-FER-Z-1 obtained in step (5) was added to a reaction bottle, and the bottle mouth was sealed with a rubber stopper after replacing the gas with nitrogen three times; then 50 ml of a 2 mol / L toluene solution of triethylaluminum was injected into the reaction bottle, and the resulting mixture was stirred for reaction for 30 min under an ice bath; the ice bath was removed, and the reaction was continued to stir at room temperature for 2 h. After filtering under a nitrogen atmosphere, the resulting filtrate was heated and the solvent was removed by vacuum distillation. The resulting residue was then dissolved in 100 ml of dry toluene and continued to be distilled under vacuum. Finally, the resulting residue was collected to obtain ethylaluminoxane, with a total product of 3.4 g.
[0040] Example 2
[0041] The preparation method of ethylaluminoxane is based on Example 1, except that the hexadecyltrimethylammonium bromide in step (1) is replaced with hexadecyltrimethylammonium hydroxide, and the amount of hexadecyltrimethylammonium hydroxide used is 0.14 g; the other conditions are the same as those in Example 1, and 3.7 g of ethylaluminoxane is finally obtained.
[0042] Example 3
[0043] The preparation method of ethylaluminoxane is prepared by referring to Example 1, except that the hexadecyltrimethylammonium bromide in step (1) is replaced with hexadecylmethylpiperidinium bromide, and the amount of hexadecylmethylpiperidinium bromide is 0.20 g; the other conditions are the same as those in Example 1, and finally 4.2 g of ethylaluminoxane is obtained.
[0044] Example 4
[0045] The preparation method of ethylaluminoxane is based on Example 1, except that the hexadecyltrimethylammonium bromide in step (1) is replaced with hexadecylmethylpiperidinium bromide, and the amount of hexadecylmethylpiperidinium bromide is 0.30 g; the other conditions are the same as those in Example 1, and 4.4 g of ethylaluminoxane is finally obtained.
[0046] Example 5
[0047] The preparation method of ethylaluminoxane is prepared by referring to Example 1, except that the hexadecyltrimethylammonium bromide in step (1) is replaced with hexadecylmethylpiperidinium bromide, and the amount of hexadecylmethylpiperidinium bromide is 0.40 g; the other conditions are the same as those in Example 1, and finally 4.7 g of ethylaluminoxane is obtained.
[0048] Example 6
[0049] The preparation method of ethylaluminoxane is based on Example 1, except that the ethylenediamine in step (1) is replaced with isopropylamine; the other conditions are the same as those in Example 1, and 3.5 g of ethylaluminoxane is finally obtained.
[0050] Example 7
[0051] The preparation method of ethylaluminoxane is the same as that of Example 1, except that the ethylenediamine in step (1) is replaced with cyclohexylamine; the other conditions are the same as those of Example 1, and 3.4 g of ethylaluminoxane is finally obtained.
[0052] Example 8
[0053] The preparation method of ethylaluminoxane is the same as that of Example 1, except that the ethylenediamine in step (1) is replaced with piperidine; the other conditions are the same as those of Example 1, and 4.1 g of ethylaluminoxane is finally obtained.
[0054] Example 9
[0055] The preparation method of ethylaluminoxane is based on Example 1, except that step (2) is changed to: the silica-alumina sol prepared in step (1) is placed in a polytetrafluoroethylene hydrothermal reactor and sealed, and heated at 80°C for 7h to obtain silica-alumina gel; other conditions are the same as in Example 1, and finally 3.3g of ethylaluminoxane is obtained.
[0056] Example 10
[0057] The preparation method of ethylaluminoxane is prepared by referring to Example 1, except that: step (3) is changed to: the silica-alumina gel prepared in step (2) is placed in a polytetrafluoroethylene hydrothermal reactor and sealed, and heated to 190°C for crystallization for 10 hours; the treatment method after crystallization is the same as that in Example 1; other conditions are the same as those in Example 1, and finally 3.4 g of ethylaluminoxane is prepared.
[0058] Embodiment 11
[0059] The preparation method of ethylaluminoxane is based on Example 1, except that the method for removing organic matter such as surfactants and structure directing agents in step (3) is changed to: the dried solid is transferred into a muffle furnace and calcined at 550°C for 10 hours; the other conditions are the same as in Example 1, and finally 3.1 g of ethylaluminoxane is obtained.
[0060] Example 12
[0061] The preparation method of ethylaluminoxane is the same as that of Example 1, except that the trimethylsilyl chloride in step (4) is replaced with dodecylamine; the other conditions are the same as those of Example 1, and finally 3.9 g of ethylaluminoxane is obtained.
[0062] Example 13
[0063] The preparation method of ethylaluminoxane is the same as that of Example 1, except that the trimethylsilyl chloride in step (4) is replaced with dodecylamine, and the amount of dodecylamine used is 3.4 mL; the other conditions are the same as those of Example 1, and finally 4.3 g of ethylaluminoxane is obtained.
[0064] Embodiment 14
[0065] The preparation method of ethylaluminoxane is as follows: the preparation method is as follows: the hexadecyltrimethylammonium bromide in step (1) is replaced by hexadecylmethylpiperidinium bromide, and the amount of hexadecylmethylpiperidinium bromide is 0.40 g; the ethylenediamine in step (1) is replaced by piperidine; the trimethylchlorosilane in step (4) is replaced by dodecylamine, and the amount of dodecylamine is 3.4 mL; the other conditions are the same as in Example 1, and finally 5.4 g of ethylaluminoxane is obtained.
[0066] Embodiment 15
[0067] The preparation method of modified aluminoxane is prepared by referring to Example 1, except that triethylaluminum in step (6) is replaced by triisobutylaluminum; other conditions are the same as those in Example 1, and finally 4.5 g of triisobutylaluminoxane is obtained.
[0068] Example 16
[0069] The steps of catalytic ethylene / 1-octene copolymerization are as follows:
[0070] (1) Preparation of metallocene catalyst: All operations were carried out under nitrogen protection. 7.5 g of silica gel carrier was placed in an oven at 110° C. and dried for 6 hours before being added to a reaction flask. Then, 0.3 g of ethylaluminoxane, 0.08 g of pentafluorophenyl zinc, and 0.03 g of 1-(phenylbenzyl)azetidinol olefin and 80ml toluene, move the reaction flask into an ultrasonic reactor and ultrasonically oscillate at 35°C for 45min, filter and wash the obtained solid with 25ml toluene 3 times to prepare ethylaluminoxane and 1-(phenylbenzyl)azetidinol olefin-loaded silica gel carrier; add the prepared ethylaluminoxane and 1-(phenylbenzyl)azetidinol olefin-loaded silica gel carrier and 0.15g metallocene complex Me2SiCp2ZrCl2 into 45ml toluene, then move the reaction flask into an ultrasonic reactor and ultrasonically oscillate at 35°C for 35min, filter and wash the obtained solid with 30ml toluene, repeat the washing at least 3 times, and vacuum dry the obtained solid to prepare the metallocene catalyst;
[0071] (2) Catalytic ethylene / 1-octene copolymerization:
[0072] All operations were carried out under nitrogen protection. The 1L stainless steel polymerization kettle was replaced with high-purity nitrogen for no less than three times, and then 30ml of n-hexane, 20ml of 1-octene, 0.58g ethylaluminoxane and 0.02g of the metallocene catalyst prepared in step (1), start stirring and raise the temperature of the polymerization kettle to 120°C, inject ethylene into the polymerization kettle at a pressure of 1.2MPa, keep the temperature and pressure of the reaction system constant, maintain the polymerization reaction for 2.5h and then cool down, pour the reaction solution into 100ml of 10% acidified ethanol solution (hydrochloric acid / ethanol=1 / 10) to terminate the reaction, filter and wash the obtained copolymer with 30ml of deionized water and 30ml of anhydrous ethanol in turn, and finally place it in a vacuum drying oven at 80°C and dry it to constant weight to obtain ethylene-1-octene copolymer; the obtained ethylene-1-octene copolymer is characterized under the following specific conditions: the weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (PDI=Mw / Mn) of the copolymer are determined by high temperature gel permeation chromatography; DSC of the copolymer is measured at SHIMADZU The temperature was measured on DSC-50 at a rate of 20°C / min. The density of the copolymer was measured using a density balance. The insertion rate of 1-octene in the copolymer was measured using a high temperature 13 C-NMR test: Weigh 50 mg of the copolymer and dissolve it in deuterated 1,1,2,2-tetrachloroethane as solvent and test it at 100°C. The reaction results are: the polymerization activity of the catalyst is 1.91×10 3 (gCopolymer:gcat -1 h -1 ); Mw is 12.03×10 4 , Mn is 5.17×10 4 , PDI is 2.33; the density of the obtained copolymer is 0.901 g / cm 3 ; The insertion rate of 1-octene in the copolymer is 2.51%; The melting point Tm of the obtained copolymer is 112°C.
[0073] Comparative Example 1
[0074] The preparation method of modified aluminoxane is similar to that of Example 1, except that step (4) is omitted, that is, the surface of the FER zeolite molecular sieve is not modified; other conditions are the same as those of Example 1, and 2.5 g of ethyl aluminoxane is finally obtained.
[0075] Comparative Example 2
[0076] The preparation method of the modified aluminoxane is as follows:
[0077] (1) 5 g of 5A molecular sieve was vacuum dried at 110° C. for 10 h, then added to 50 mL of toluene, and then 2.3 ml of trimethylsilyl chloride was added, and the resulting mixture was heated at 30° C. for 24 h; after the reaction, the solid was filtered and washed with a 95% ethanol solution until there was no chloride ion (the filtrate was tested with a 0.1 mol / L AgNO3 solution until there was no precipitation); the washed solid was placed in a vacuum drying oven and vacuum dried at 80° C. for 6 h to obtain a trimethylsilyl chloride-modified 5A molecular sieve;
[0078] (2) placing the trimethylchlorosilane-modified 5A molecular sieve obtained in step (1) in water vapor at 120° C. for activation, controlling the flow rate of the water vapor to 50 mL / min, and obtaining an activated molecular sieve after 45 min of activation, and recording the obtained molecular sieve as TMC-5A;
[0079] (3) Under an ice bath, 0.5 g of the activated molecular sieve TMC-5A prepared in step (2) was added to a reaction bottle, and the bottle mouth was sealed with a rubber stopper after replacing the atmosphere with nitrogen three times; then 50 ml of a 2 mol / L toluene solution of triethylaluminum was injected into the reaction bottle, and the resulting mixture was stirred for reaction for 30 min under an ice bath; the ice bath was removed, and the reaction was continued to stir at room temperature for 2 h. After filtering under a nitrogen atmosphere, the resulting filtrate was heated and the solvent was removed by vacuum distillation, and the resulting residue was dissolved in 100 ml of dry toluene and continued to be vacuum distilled. Finally, the resulting residue was collected to obtain ethylaluminoxane, with a total product of 2.1 g.
Claims
1. A method for preparing a modified alkylaluminoxane for α-olefin polymerization, characterized in that: The specific steps include: (1) adding a silicon source and an alkali to water and stirring them evenly, then adding a surfactant, stirring until the surfactant is dissolved, then adding an aluminum source and a structure directing agent, and then continuing to stir the resulting mixture to react to obtain a silicon-alumina sol; (2) heating and aging the silica-alumina sol prepared in step (1) to obtain a silica-alumina gel; (3) crystallizing the silica-alumina gel obtained in step (2), filtering, washing and drying the obtained solid, and removing the surfactant and the structure directing agent from the dried solid to obtain a FER zeolite molecular sieve; (4) adding the FER zeolite molecular sieve prepared in step (3) into an organic solution, and then adding a surface modifier to react to obtain a surface-modified FER zeolite molecular sieve; (5) activating the surface-modified FER zeolite molecular sieve obtained in step (4) to obtain an activated molecular sieve; (6) adding the activated molecular sieve prepared in step (5) to a toluene solution containing alkyl aluminum, stirring the obtained mixture for reaction and filtering it, and collecting the residue after repeatedly distilling the obtained filtrate under reduced pressure to obtain the modified alkyl aluminumoxane for α-olefin polymerization.
2. The method for preparing a modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The silicon source in step (1) is one of sodium silicate or silicon tetrachloride; and the alkali is one of sodium hydroxide or potassium hydroxide.
3. The method for preparing a modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The aluminum source described in step (1) is composed of one or more of aluminum sulfate, sodium aluminate, aluminum nitrate or aluminum trichloride.
4. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The structure directing agent in step (1) is composed of one or more of pyrrolidine, pyridine, piperidine, ethylenediamine, triethylamine, isopropylamine or cyclohexylamine.
5. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The surfactant described in step (1) is composed of one or more of hexadecyltrimethylammonium bromide, hexadecylmethylpiperidinium bromide or hexadecyltrimethylammonium hydroxide.
6. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The heating aging method described in step (2) is microwave heating aging.
7. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The surface modifier described in step (4) is one of organic chlorosilane or fatty amine.
8. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The activation condition described in step (5) is heating in water vapor.
9. The method for preparing modified alkylaluminoxane for α-olefin polymerization according to claim 1, characterized in that: The alkyl aluminum described in step (6) is prepared by mixing one or both of triethyl aluminum and triisobutyl aluminum.
10. Use of the modified alkylaluminoxane prepared by the method for preparing the modified alkylaluminoxane for α-olefin polymerization according to claims 1 to 9.