Preparation method of alkylaluminoxane solution

Abstract

The invention provides a preparation method of an alkylaluminoxane solution. According to the method, the alkylaluminoxane solution is prepared by taking sodium alginate hydrate and aluminum alkyl as raw materials, the cost is low, the reaction process is easy to control, the safety of the production process is high, and the conversion rate of aluminum alkyl reaches 70% or above. When the alkylaluminoxane solution prepared by the method is used as a promoter of a metallocene catalyst to catalyze ethylene polymerization, quite high polymerization activity can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to a preparation method of an alkylaluminoxane solution, specifically to a preparation method of an alkylaluminoxane solution which is a cocatalyst for metallocene catalysts and late transition metal catalysts. Background Art

[0002] Methylaluminoxane and modified methylaluminoxane are highly efficient cocatalysts for metallocene catalytic systems, and play a role in activating the main catalyst to transform into an active center in the catalytic olefin polymerization reaction. Alkylaluminoxane is a product of partial hydrolysis of alkylaluminum, and its synthesis methods can be divided into hydrolysis methods and non-hydrolysis methods. The hydrolysis method has two types: direct hydrolysis process and indirect hydrolysis process according to different preparation processes. The direct hydrolysis process involves direct contact reaction of alkylaluminum with water, with a fast reaction rate and high product yield, which is very suitable for large-scale production (US 3242099, US 4730071, US 4730072, US 4772736, US4908463, US 4924018, US 5041584, CN 100413870C, CN 102190678 B, CN 111004265 A). However, the reaction degree is difficult to control, a large amount of heat is released during the reaction, so it is very difficult to ensure process safety, the requirements for production equipment are high, and the investment and construction costs are large.

[0003] The indirect hydrolysis process introduces water into the reaction system by slowly releasing crystal water from a crystal hydrate to react with the alkylaluminum in the solution (US 4544762, US 4404344, US 4665208, US 5041583, US 5099050, US5147137, CN1309724C). The advantage of this method is that the reaction rate is slower and the production process is safe and controllable, but the yield is generally lower than that of the direct hydrolysis process, usually only about 50%.

[0004] Therefore, it is necessary to develop a new method for efficiently preparing an alkylaluminoxane solution. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a preparation method of an alkylaluminoxane solution, which uses sodium alginate hydrate and alkylaluminum as raw materials to prepare the alkylaluminoxane solution, and has the advantage of high conversion rate.

[0006] When the alkylaluminoxane solution prepared by the method of the present invention is used as a cocatalyst for a metallocene catalyst to catalyze ethylene polymerization, a quite high polymerization activity can be obtained.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing an alkylaluminoxane solution, and the steps include:

[0009] (1) Mix sodium alginate and / or modified sodium alginate with water to form a gel-like sodium alginate hydrate, and then disperse it in In organic solvent A , and stir until Viscous liquid ;

[0010] (2) Mix trimethylaluminum with at least one trialkylaluminum having a C2-C10 alkyl group and an organic solvent B to obtain an alkylaluminum solution;

[0011] (3) Add the Continuous viscous liquid in step (1) to the alkylaluminum solution in step (2), carry out the reaction under stirring, and then Filter obtain an alkylaluminoxane solution;

[0012] The operations in the above steps (1)-(3) are all carried out in a protective gas environment.

[0013] In the present invention, the sodium alginate described in step (1) is an existing compound and has a structure shown by the following formula,

[0014] where M is β-D-mannuronic acid, G is α-L-guluronic acid, G is the stereoisomer of M at the C-5 position, the molecular chain of sodium alginate is composed of M blocks, G blocks and MG alternating blocks with a certain length, and n, that is, the degree of polymerization, is a natural number from 100 to 1000;

[0015] Preferably, the degree of polymerization of the sodium alginate described in step (1) of the present invention is 100-1000, such as 100, 300, 500, 700, 900, 1000, and more preferably 500-600. For example, food-grade sodium alginate produced by Qingdao Nanshan Biotechnology Co., Ltd. and powdered sodium alginate produced by Qingdao Shuangcheng Algae Co., Ltd. can be used.

[0016] In step (1) of the present invention, modified sodium alginate can also be used, and the modifying groups are selected from at least one of mercapto (-SH), sulfonic acid group (-SO 3 H), sulfonyl group (-SOCl), amino group (-NH 2 ), ureido group (-NH-CO-NH 2 ), siloxy group (-SiO), nitro group (-NO 2 ), and preferably at least one of amino group and ureido group;

[0017] Preferably, for the modified sodium alginate, the content of the modifying group is 1.2 - 15.6 wt%, such as 1.2 wt%, 2.0 wt%, 5.0 wt%, 8.0 wt%, 10.0 wt%, 12.0 wt%, 15.0 wt%, preferably 4.1 - 5.4 wt%, and the sodium ion content is 2.25 - 11.62 wt%, such as 2.25 wt%, 3.00 wt%, 5.00 wt%, 7.00 wt%, 9.00 wt%, 11.00 wt%, preferably 8.19 - 9.68 wt%;

[0018] For the modified sodium alginate, the modification methods include but are not limited to physical blending, grafting, oxidation, crosslinking, esterification, amidation, etherification, etc. Preferably, it is amino - modified sodium alginate. The present invention does not make specific limitations on its source, and it can be obtained by purchase or self - preparation; the self - preparation method can refer to the existing reported technologies and can be prepared by any achievable method. The present invention has no special requirements. For example, it can refer to the method described in "Preparation of Amino Sulfonic Acid Modified Sodium Alginate and Its Adsorption of Fe" 3+ for preparation.

[0019] In the present invention, when the sodium alginate and / or modified sodium alginate in step (1) are mixed with water to form a gel - like sodium alginate hydrate, the mixing conditions include: the stirring speed is 200 - 1200 r / min, such as 200 r / min, 400 r / min, 600 r / min, 800 r / min, 1000 r / min, 1200 r / min, preferably 500 - 700 r / min; the temperature is 20 - 80 °C, such as 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, preferably 40 - 60 °C; and the time is 0.2 - 1.0 h, preferably 0.2 h, 0.4 h, 0.6 h, 0.8 h, 1.0 h, preferably 0.5 - 1.0 h.

[0020] In the sodium alginate hydrate in step (1) of the present invention, the content of sodium alginate and / or modified sodium alginate is 8 - 16 wt%, such as 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, preferably 10 - 12 wt%. The present invention forms a concentrated solution by dissolving sodium alginate / modified sodium alginate in water. At the same time, a large number of carboxylate anions and hydroxyl groups in sodium alginate associate with water molecules through hydrogen bonds and intermolecular interactions to form a physical gel, thereby obtaining the sodium alginate hydrate.

[0021] In the present invention, the organic solvent A in step (1) is selected from at least one of saturated alkanes and aromatic solvents, preferably at least one of saturated alkanes with C6-C12 such as C6, C8, C10, C12 or aromatic solvents with C6-C10 such as C6, C8, C10, and more preferably at least one of n-heptane, n-hexane, n-octane, methylcyclohexane, isoparaffin, and toluene, and particularly preferably at least one of toluene and isoparaffin.

[0022] In the present invention, the dispersion concentration of sodium alginate hydrate in the organic solvent A in step (1) is 0.05-2.9 g / mL, such as 0.05 g / mL, 0.5 g / mL, 1.0 g / mL, 1.5 g / mL, 2.0 g / mL, 2.5 g / mL, 2.9 g / mL, and preferably 0.5-2.0 g / mL.

[0023] In the present invention, in step (1), stirring is carried out until a fluid Viscous liquid, preferably, the stirring time is is formed for 0.5-5 h, preferably 1-3 h.

[0024] In the present invention, the trialkylaluminum with C2-C10 alkyl groups in step (2) has a structure that can be represented as AlR 3 , where R is an alkyl group with C2-C10 such as C2, C4, C6, C8, C10;

[0025] Preferably, the trialkylaluminum with C2-C10 alkyl groups is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum, and more preferably triisobutylaluminum and trioctylaluminum.

[0026] In the present invention, the organic solvent B in step (2) is selected from at least one of saturated alkanes and aromatic solvents, preferably at least one of saturated alkanes with C6-C8 such as C6, C7, C18 or aromatic solvents with C6-C10 such as C6, C8, C10, and more preferably at least one of n-heptane, n-hexane, n-octane, methylcyclohexane, isoparaffin, dichloromethane, 1,2-dichloroethane, and toluene, and particularly preferably at least one of toluene and isoparaffin;

[0027] The organic solvent B in step (2) may be the same as or different from the organic solvent A in step (1).

[0028] In the present invention, the concentration of trimethylaluminum in organic solution B in step (2) is 0.01 - 4 mol / L, such as 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, preferably 1 - 3 mol / L;

[0029] The total concentration of the at least one trialkylaluminum having a C2 - C10 alkyl group in organic solution B is 0.01 - 4 mol / L, such as 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, preferably 1 - 3 mol / L.

[0030] In the present invention, in step (3), the viscous liquid in step (1) is fed continuously, and the feeding temperature is -80 to 50 °C, such as -80 °C, -60 °C, -40 °C, -20 °C, 0 °C, 20 °C, 40 °C, 50 °C, preferably -10 to 10 °C; the sodium alginate hydrate is continuously and uniformly added to the alkylaluminum solution. This feeding method can ensure that the alkylaluminum is greatly in excess at the beginning of the reaction, avoid the excessive hydrolysis of the alkylaluminum, and improve the reaction yield;

[0031] The feeding rate of the viscous liquid is controlled such that the molar amount of water contained in the viscous liquid added per minute, in terms of the molar amount of water, and the total molar amount of alkylaluminum (including trimethylaluminum and the at least one trialkylaluminum having a C2 - C10 alkyl group) in the alkylaluminum solution in step (2) is 0.005 - 0.5:1, such as 0.005:1, 0.01:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, preferably 0.02 - 0.2:1;

[0032] Preferably, during the feeding process of the viscous liquid, the temperature fluctuation in the system is controlled to be less than ±2 °C.

[0033] In the present invention, in step (3), the molar ratio of alkylaluminum (including trimethylaluminum and the at least one trialkylaluminum having a C2 - C10 alkyl group) in the alkylaluminum solution to water in the viscous liquid is 1:0.2 - 1.5, such as 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1.0, 1:1.2, 1:1.4, 1:1.5, preferably 1:0.6 - 0.8.

[0034] In the present invention, for the reaction in step (3), the stirring speed is 350 - 1000 r / min, such as 350 r / min, 400 r / min, 600 r / min, 800 r / min, 1000 r / min, preferably 450 - 550 r / min, the temperature is 20 - 60 °C, such as 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, preferably 25 - 40 °C, and the reaction time after the addition is completed is 1 - 48 h, preferably 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 40 h, 48 h, preferably 16 - 24 h.

[0035] In the present invention, the protective gas is nitrogen or an inert gas such as argon, preferably with a gas purity greater than 99.9%, and the water content is less than 10 ppm, such as 10 ppm, 8 ppm, 6 ppm, 4 ppm, 2 ppm, 0 ppm.

[0036] In the method of the present invention, the yield of alkylaluminoxane is as high as over 70%.

[0037] The alkylaluminoxane solution prepared by the present invention can be used in the polymerization reaction of olefins (such as ethylene) as a cocatalyst for metallocene catalysts, enabling the catalytic reaction to obtain a rather high polymerization activity, which can be as high as 1×10 14 gPE / mol(Zr) or more.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] The sodium alginate / modified sodium alginate introduced in the preparation method of the present invention has good water absorption, can absorb several times its own weight of water, and has a higher water content compared with general crystalline hydrates; the water in the sodium alginate hydrate is slowly released by hydrogen bond dissociation, reacts more stably with the alkylaluminum solution, effectively controls the "temperature runaway" phenomenon, can make the total alkylaluminum concentration higher, thus effectively solving the safety problem of synthesizing alkylaluminoxane by the direct water process, and can greatly improve the production capacity of the device; the yield of alkylaluminoxane can reach over 70%.

[0040] The alkylaluminoxane prepared by the method of the present invention is used as a cocatalyst to activate the metallocene catalyst for ethylene polymerization, and the polymerization activity can be as high as 1×10 14 gPE / mol(Zr). Specific Embodiments

[0041] The following examples further illustrate the specific implementation of the present method. However, the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights required by the present invention.

[0042] In each embodiment and comparative example of the present invention, the main raw material sources are as follows. Unless otherwise specified, other raw materials and reagents are obtained through ordinary commercial channels:

[0043] Sodium alginate (degree of polymerization is 100 - 750, M w / M n = 1.5 - 2.5, sodium content is about 10 wt%): Food - grade sodium alginate produced by Qingdao Nanshan Biotechnology Co., Ltd.

[0044] Aminated sodium alginate: Refer to the method described in "Preparation of Amino - sulfonic Acid Modified Sodium Alginate and Its Adsorption of Fe 3+ " to prepare amino - sulfonic acid modified sodium alginate shown in Formula III, add 1M sodium hydroxide solution for further hydrolysis, and after freeze - drying, aminated sodium alginate with the structure shown in Formula IV can be obtained (degree of polymerization is 500, amino content is about 4.5 wt%, sodium content is about 9.1 wt%);

[0045]

[0046] Urea - modified sodium alginate: React the structure shown in Formula II above with urea to obtain a mixture of urea - modified sodium alginate with the structures shown in Formula V and Formula VI (degree of polymerization is 500, urea group content is about 5.2 wt%, sodium content is about 9.0 wt%), where the selectivity of the structure of Formula V is 60% and the selectivity of the structure of Formula VI is 40%.

[0047]

[0048] The main properties in the embodiments of the present invention are tested by the following methods:

[0049] Conversion rate: The mass of aluminum atoms in the alkylaluminum solution described in step (2) is m1, and the mass of aluminum atoms in the alkylaluminum oxyalkane solution is measured by ICP method (inductively coupled plasma emission spectroscopy) as m2. The conversion rate = m2 / m1×100%, where the instrument model used is Agilent (Varian) ICP - OES 720ES.

[0050] Activity: Use the alkylaluminum oxyalkane solution as the cocatalyst for the homogeneous polymerization of ethylene by metallocene catalyst. Control the catalyst dosage, temperature, pressure, polymerization time, and Al / Zr ratio in the polymerization reaction to be the same. Evaluate the activity of the alkylaluminum oxyalkane solution by the mass of polyethylene obtained by the polymerization of ethylene per mole of metallocene catalyst (unit: g(PE) / mol(Zr)).

[0051] Example 1

[0052] Prepare the alkylaluminum oxyalkane solution, operating in a nitrogen atmosphere. The steps are as follows:

[0053] (1) Add 32.4 g of water and 3.6 g of sodium alginate to a beaker, stir at 50 °C and a rotation speed of 500 r / min for 1 hour to form a gel-like sodium alginate hydrate, and then disperse it in 70 mL In toluene , stir for 1 hour to form a fluid Viscous liquid ;

[0054] (2) Add 8000 mL of toluene to a three-necked round-bottom flask, and then add 0.15 mol of pure trimethylaluminum and 0.07 mol of pure triisobutylaluminum (the total molar concentration of alkylaluminum is 0.03 mol / L), start stirring to obtain an alkylaluminum solution;

[0055] (3) At -80 °C, add the Viscous liquid from step (1) to the alkylaluminum solution in step (2), and control the feeding rate to be Viscous liquid per minute. The added amount, calculated based on the molar amount of water it contains, is in a ratio of 0.05:1 to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2), and the total added amount is an alkylaluminum / water molar ratio of 1:0.2; during the feeding process, control the temperature fluctuation in the system to be less than ±2 °C; after the feeding is completed, raise the reaction temperature to 20 °C, continue to stir and react at a rotation speed of 350 r / min for 1 hour, and after the reaction is completed, filter to remove the solid to obtain a clear alkylaluminoxane solution. The reaction results are shown in Table 1.

[0056] Example 2

[0057] Prepare an alkylaluminoxane solution, operate in a nitrogen atmosphere, and the steps are as follows:

[0058] (1) Add 8.64 g of water and 0.75 g of sodium alginate to a beaker, stir at 20 °C and a rotation speed of 200 r / min for 0.2 hour to form a gel-like sodium alginate hydrate, and then disperse it in 10 mL In hexane , stir for 2 hours to form a fluid Viscous liquid ;

[0059] (2) Add 2000 mL of toluene to a three-necked round-bottom flask, and then add 0.15 mol of pure trimethylaluminum and 0.03 mol of pure triethylaluminum (the total molar concentration of alkylaluminum is 0.09 mol / L), start stirring to obtain an alkylaluminum solution;

[0060] (3) At -40 °C, add the Viscous liquid from step (1) to the alkylaluminum solution in step (2), and control the feeding rate to be Viscous liquidThe addition amount, calculated based on the molar amount of water contained therein, is in a ratio of 0.1:1 to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2), and the total addition amount is an alkylaluminum / water molar ratio of 0.4; during the feeding process, the temperature fluctuation in the system is controlled to be less than ±2°C; after the feeding is completed, the reaction temperature is raised to 300°C, and stirring reaction is continued at a rotation speed of 450 r / min for 3 hours. After the reaction is completed, the solid is removed by filtration to obtain a clear alkylaluminum oxane solution. The reaction results are shown in Table 1.

[0061] Example 3

[0062] To prepare an alkylaluminum oxane solution, the operation is carried out in a nitrogen atmosphere, and the steps are as follows:

[0063] (1) Add 19.8 g of water and 3.8 g of sodium alginate to a beaker, stir at 40°C and a rotation speed of 400 r / min for 0.4 h to form a gel-like sodium alginate hydrate, and then disperse it in 35 mL In heptane , stir for 3 h to form a fluid Viscous liquid ;

[0064] (2) Add 200 mL of toluene to a three-necked round-bottom flask, then add 0.15 mol of pure trimethylaluminum and 0.04 mol of pure trihexylaluminum (the total molar concentration of alkylaluminum is 0.95 mol / L), start stirring to obtain an alkylaluminum solution;

[0065] (3) At 0°C, add the Viscous liquid from step (1) to the alkylaluminum solution in step (2), and control the feeding rate to be Viscous liquid The addition amount, calculated based on the molar amount of water contained therein, is in a ratio of 0.2:1 to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2), and the total addition amount is an alkylaluminum / water molar ratio of 1:0.6; during the feeding process, the temperature fluctuation in the system is controlled to be less than ±2°C; after the feeding is completed, the reaction temperature is raised to 40°C, and stirring reaction is continued at a rotation speed of 550 r / min for 9 hours. After the reaction is completed, the solid is removed by filtration to obtain a clear alkylaluminum oxane solution. The reaction results are shown in Table 1.

[0066] Example 4

[0067] To prepare an alkylaluminum oxane solution, the operation is carried out in a nitrogen atmosphere, and the steps are as follows:

[0068] (1) Add 65 g of water and 7.2 g of sodium alginate to a beaker, stir at 80°C and a rotation speed of 600 r / min for 0.6 h to form a gel-like sodium alginate hydrate, and then disperse it in 45 mL In octane , stir for 2 h to form a fluid Viscous liquid ;

[0069] (2) Add 100 mL of toluene to a three-necked round-bottom flask, then add 0.15 mol of pure trimethylaluminum and 0.04 mol of pure triisobutylaluminum (the total molar concentration of alkylaluminum is 1.9 mol / L), start stirring to obtain an alkylaluminum solution;

[0070] (3) At 15 °C, add the Viscous liquid from step (1) to the alkylaluminum solution in step (2), and control the feeding rate to be Viscous liquid per minute. The added amount, calculated by the molar amount of water contained therein, has a ratio of 0.3:1 to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2), and the total added amount is an alkylaluminum / water molar ratio of 1:1.2; during the feeding process, control the temperature fluctuation in the system to be less than ±2 °C; after the feeding is completed, raise the reaction temperature to 30 °C, and continue stirring and reacting at a rotation speed of 650 r / min for 12 hours. After the reaction is completed, filter off the solid to obtain a clear alkylaluminoxane solution. The reaction results are shown in Table 1.

[0071] Example 5

[0072] Prepare an alkylaluminoxane solution, and operate in a nitrogen atmosphere. The steps are as follows:

[0073] (1) Add 65 g of water and 9 g of sodium alginate to a beaker, stir at 80 °C and a rotation speed of 800 r / min for 0.8 h to form a gel-like sodium alginate hydrate, and then disperse it in 45 mL of In isoparaffin , stir for 0.5 h to form a Viscous liquid with fluidity;

[0074] (2) Add 50 mL of toluene to a three-necked round-bottom flask, then add 0.15 mol of pure trimethylaluminum and 0.03 mol of pure trioctylaluminum (the total molar concentration of alkylaluminum is 3.6 mol / L), start stirring to obtain an alkylaluminum solution;

[0075] (3) At 50 °C, add the Viscous liquid from step (1) to the alkylaluminum solution in step (2), and control the feeding rate to be Viscous liquid per minute. The added amount, calculated by the molar amount of water contained therein, has a ratio of 0.25:1 to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2), and the total added amount is an alkylaluminum / water molar ratio of 1:1.5; during the feeding process, control the temperature fluctuation in the system to be less than ±2 °C; after the feeding is completed, raise the reaction temperature to 60 °C, and continue stirring and reacting at a rotation speed of 850 r / min for 24 hours. After the reaction is completed, filter off the solid to obtain a clear alkylaluminoxane solution. The reaction results are shown in Table 1.

[0076] Example 6

[0077] Prepare an alkylaluminoxane solution, and operate in a nitrogen atmosphere. The steps are as follows:

[0078] (1) Add 58 g of water and 10.6 g of amino-modified sodium alginate to a beaker, stir at 30 °C and a rotation speed of 1000 r / min for 1 hour to form a gel-like sodium alginate hydrate, and then disperse it in 35 mL In methylcyclohexane , stir for 4 hours to form a fluid Viscous liquid ;

[0079] (2) Add 100 mL of toluene to a three-necked round-bottom flask, then add 0.15 mol of pure trimethylaluminum and 0.05 mol of pure trihexylaluminum (the total molar concentration of alkylaluminum is 2 mol / L), start stirring to obtain an alkylaluminum solution;

[0080] (3) At 10 °C, add the product of step (1) Viscous liquid to the alkylaluminum solution of step (2), and control the feeding rate to be Viscous liquid The added amount is calculated based on the molar amount of water contained therein, and the ratio to the total molar amount of alkylaluminum in the alkylaluminum solution of step (2) is 0.08:1. The total added amount is an alkylaluminum / water molar ratio of 1:0.8; during the feeding process, control the temperature fluctuation in the system to be less than ±2 °C; after the feeding is completed, raise the reaction temperature to 60 °C and continue to stir and react at a rotation speed of 900 r / min for 36 hours. After the reaction is completed, filter to remove solids to obtain a clear alkylaluminum oxane solution. The reaction results are shown in Table 1.

[0081] Example 7

[0082] Prepare an alkylaluminum oxane solution, operate in a nitrogen atmosphere, and the steps are as follows:

[0083] (1) Add 50 g of water and 8 g of urea-modified sodium alginate to a beaker, stir at 40 °C and a rotation speed of 1200 r / min for 1 hour to form a gel-like sodium alginate hydrate, and then disperse it in 20 mL In toluene , stir for 5 hours to form a fluid Viscous liquid ;

[0084] (2) Add 200 mL of toluene to a three-necked round-bottom flask, then add 0.15 mol of pure trimethylaluminum and 0.06 mol of pure trioctylaluminum (the total molar concentration of alkylaluminum is 1.05 mol / L), start stirring to obtain an alkylaluminum solution;

[0085] (3) At 0 °C, add the product of step (1) Viscous liquid to the alkylaluminum solution of step (2), and control the feeding rate to be Viscous liquidThe addition amount is calculated based on the molar amount of water contained therein, and the ratio to the total molar amount of alkylaluminum in the alkylaluminum solution in step (2) is 0.05:1. The total addition amount is such that the molar ratio of alkylaluminum / water is 1:0.6. During the feeding process, the temperature fluctuation in the system is controlled to be less than ±2 °C. After the feeding is completed, the reaction temperature is raised to 50 °C, and stirring reaction is continued at 1000 r / min for 48 hours. After the reaction ends, the solid is removed by filtration to obtain a clear alkylaluminum oxane solution. The reaction results are shown in Table 1.

[0086] Comparative Example 1

[0087] Referring to the preparation method of Example 3, the difference is only that: in step (1), sodium alginate is not added, and other operations remain unchanged, to obtain an alkylaluminum oxane toluene solution. The reaction results are shown in Table 1.

[0088] Comparative Example 2

[0089] Referring to the preparation method of Example 3, the difference is only that: in step (1), sodium alginate is replaced by sodium D-glucuronate, and other operations remain unchanged, to obtain an alkylaluminum oxane toluene solution. The reaction results are shown in Table 1.

[0090] Application of the alkylaluminum oxane solutions prepared in the examples and comparative examples of the present invention:

[0091] Taking its use in the ethylene polymerization reaction as an example, as a cocatalyst for the metallocene catalyst, the conditions include:

[0092] At 130 °C and 3 atmospheres, using dimethylsilyl bridged bis(indenyl)zirconium dichloride catalyst as the main catalyst (this catalyst can be purchased from commercial channels, and production companies such as Grace, Lake, etc.), the concentration of the catalyst is 10 micromoles per liter, the molar ratio of alkylaluminum oxane to the main catalyst is 2500, and the polymerization time is 5 minutes. The result test is carried out, and the catalytic ethylene polymerization results are shown in Table 1.

[0093] Table 1 Reaction results of the examples of the present invention and results for ethylene polymerization

[0094]

[0095]

[0096] Table 1 results show that the alkylaluminum oxane prepared by the method of the present invention has good yield and cocatalytic performance.

Claims

1. A method for preparing an alkylaluminoxane solution, characterized in that the steps include: (1) Sodium alginate and / or modified sodium alginate is mixed with water to form a gel-like sodium alginate hydrate, which is then dispersed in Organic solvent A , stir until formed Viscous liquid ; (2) mixing trimethylaluminum, at least one trialkylaluminum having a C2-C10 alkyl group, and an organic solvent B to obtain an alkylaluminum solution; (3) Replace the Viscous liquid continuous Add to the alkyl aluminum solution of step (2), react under stirring, and then filter, Obtaining an alkylaluminoxane solution; The steps (1) to (3) are all performed in a protective gas environment.

2. The preparation method according to claim 1, characterized in that: The sodium alginate in step (1) has a degree of polymerization of 100-1000, preferably 500-600; and / or; The modified sodium alginate in step (1) has a modified group selected from at least one of a thiol group, a sulfonic acid group, a sulfonyl group, an amino group, a urea group, a siloxy group, and a nitro group, preferably at least one of an amino group and a urea group; Preferably, the modified sodium alginate has a modified group content of 1.2-15.6 wt%, preferably 4.1-5.4 wt%, and a sodium ion content of 2.25-11.62 wt%, preferably 8.19-9.68 wt%.

3. The preparation method according to claim 1, characterized in that: In step (1), the mixing process of the sodium alginate and / or modified sodium alginate and water is carried out at a stirring speed of 200-1200 r / min, preferably 500-700 r / min, a temperature of 20-80° C., preferably 40-60° C., and a time of 0.2-1.0 h, preferably 0.5-1.0 h; and / or In the sodium alginate hydrate of step (1), the content of sodium alginate and / or modified sodium alginate is 8-16wt%, preferably 10-12wt%.

4. The preparation method according to claim 1, characterized in that: The organic solvent A in step (1) is selected from at least one of saturated alkanes and aromatic solvents, preferably at least one of C6-C12 saturated alkanes or C6-C10 aromatic solvents, more preferably at least one of n-heptane, n-hexane, n-octane, methylcyclohexane, isoparaffins and toluene, particularly preferably at least one of toluene and isoparaffins; and / or The dispersion concentration of the sodium alginate hydrate in the organic solvent A in step (1) is 0.05-2.9 g / mL, preferably 0.5-2.0 g / mL; and / or Step (1) The gel is stirred until it forms a fluid Viscous liquid, preferably, the stirring time is 0.5-5h, preferably 1-3h.

5. The preparation method according to claim 1, characterized in that: The trialkylaluminum having a C2-C10 alkyl group in step (2) may have a structure represented by AlR3, wherein R is a C2-C10 alkyl group; Preferably, the trialkylaluminum having a C2-C10 alkyl group is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum, more preferably triisobutylaluminum and tri-n-octylaluminum.

6. The preparation method according to claim 1, characterized in that: The organic solvent B in step (2) is selected from at least one of saturated alkanes and aromatic solvents, preferably at least one of C6-C8 saturated alkanes or C6-C10 aromatic solvents, more preferably at least one of n-heptane, n-hexane, n-octane, methylcyclohexane, isoalkane, dichloromethane, 1,2-dichloroethane, toluene, particularly preferably at least one of toluene and isoalkane; and / or The concentration of trimethylaluminum in the organic solution B in step (2) is 0.01-4 mol / L, preferably 1-3 mol / L; and / or The total concentration of the at least one trialkylaluminum having a C2-C10 alkyl group in the organic solution B in step (2) is 0.01-4 mol / L, preferably 1-3 mol / L.

7. The preparation method according to claim 1, characterized in that: Step (3) The viscous liquid in step (1) is continuously fed at a feeding temperature of -80-50°C, preferably -10-10°C; Preferably, the viscous liquid feeding rate is controlled such that the ratio of the amount of viscous liquid added per minute, measured by the molar amount of water contained therein, to the total molar amount of the alkyl aluminum in the alkyl aluminum solution of step (2) is 0.005-0.5:1, preferably 0.02-0.2:1, wherein the alkyl aluminum in the alkyl aluminum solution comprises trimethyl aluminum and at least one trialkyl aluminum having a C2-C10 alkyl group; Preferably, during the viscous liquid adding process, the temperature fluctuation in the system is controlled to be less than ±2°C.

8. The preparation method according to claim 1, characterized in that: The molar ratio of the alkyl aluminum in the alkyl aluminum solution of step (3) to the water in the viscous liquid is 1:0.2-1.5, preferably 1:0.6-0.8, and the alkyl aluminum in the alkyl aluminum solution includes trimethyl aluminum and at least one trialkyl aluminum having a C2-C10 alkyl group.

9. The preparation method according to claim 1, characterized in that: In the reaction of step (3), the stirring speed is 350-1000 r / min, preferably 450-550 r / min, the temperature is 20-60°C, preferably 25-40°C, and the reaction time after the addition is completed is 1-48h, preferably 16-24h.

10. The preparation method according to claim 1, characterized in that: The protective gas is nitrogen or an inert gas, and preferably the gas purity is greater than 99.9% and the water content is less than 10 ppm.

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