Synthesis method of methylaluminoxane
By stirring and reacting the solution of trimethylaluminum and aluminum sulfate medecylhydrate in a specific proportion and order under an inert atmosphere, the problem of high cost, long cycle and poor selectivity in industrial production in the prior art is solved, and a high yield and high quality methylaluminumoxane preparation is achieved, which is suitable for industrial production.
Patent Information
- Application Number
- CN202510132409.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2025-04-25
AI Technical Summary
The existing preparation methods of methyl aluminoxane have problems such as high precision device demand, high input cost, long production cycle, poor reaction selectivity and low product yield in industrial production, resulting in high production costs and difficult to control product quality.
Under an inert atmosphere, the inert solvent solution of trimethylaluminum and the suspension of aluminium sulfate medecylhydrate were stirred in a specific proportion and sequence, and the reaction conditions such as temperature and time were controlled, and the solvent was removed by filtration and reduced pressure to obtain methylaluminoxane.
It achieves high yield (up to 75%) and high quality of methyl aluminoxane, simple process and low cost, suitable for industrial production, and stable product quality.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metal organic compounds and relates to a method for synthesizing methylaluminoxane, in particular to a method for synthesizing methylaluminoxane. Background Art
[0002] The main preparation method of methylaluminoxane is partial hydrolysis polymerization of trimethylaluminum and water. CN115368395A discloses a preparation method and application of alkylaluminoxane, comprising the following steps: (1) adding alkylaluminum and an inert organic solvent to an alkylaluminum solution preparation tank, stirring at -10-60°C for 0.1-5h to produce an alkylaluminum solution; (2) adding a stabilizer and water to a preparation tank at 10-60°C, stirring for 0.1-3h to produce a stabilizer aqueous solution; (3) dispersing the stabilizer aqueous solution in an inert organic solvent in a preparation tank at -5-60°C, stirring for 1-10h to produce a stabilizer, water and organic solvent mixture; (4) adding no more than one-third of the volume of the reactor to a reaction kettle at -5-60°C. an inert organic solvent; (5) adding the alkyl aluminum solution prepared in (1) and the stabilizer, water and inert organic solvent mixture prepared in (3) into the reaction kettle (4) at -5-30°C, wherein the alkyl aluminum and inert organic solvent solution is in contact with the stabilizer, water and inert organic solvent mixture in the reaction kettle (4) and stirred for 0.1-3 hours; (6) transferring the product of step (5) into a second reaction kettle and stirring at 20-100°C for 0.5-12 hours; (7) removing part of the organic solvent from the alkyl aluminoxane solution obtained in (6) at 10-60°C to obtain an alkyl aluminoxane solution having a mass ratio of alkyl aluminoxane to inert organic solvent of (1-40):100; or removing all of the organic solvent to obtain an alkyl aluminoxane solid. However, this method requires high-precision equipment for the production system in the industrial production process, high investment cost, long production cycle, poor reaction selectivity, low product yield, resulting in high production cost. At the same time, because water is directly used to react with trimethylaluminum, although a stabilizer is added, the reaction is still violent, resulting in difficulty in controlling product quality and difficulty in obtaining high-quality products.
[0003] In summary, the invention provides a method for synthesizing methylaluminoxane which has a simple and controllable process, low cost, high yield, high product quality and stable quality, and is suitable for industrial production and has great economic and social benefits. Summary of the invention
[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for synthesizing methylaluminoxane which is simple and controllable, has low cost, high yield, high product quality and stable quality and is suitable for industrial production.
[0006] The technical solution adopted by the present invention to solve the technical problem is as follows: Under an inert atmosphere, add an inert solvent solution of trimethylaluminum into a three-necked flask, start stirring, and then slowly drop a suspension of aluminum sulfate tetradecahydrate under freezing conditions. After the addition is complete, heat up, stir and react, filter to remove the residue, and remove part of the solvent from the filtrate under reduced pressure to obtain an inert solvent solution of methylaluminoxane; or remove the solvent from the filtrate under reduced pressure to obtain methylaluminoxane.
[0007] The order of adding the aluminum sulfate tetradecahydrate and trimethylaluminum inert solvent solution can be changed. Specifically, under an inert atmosphere, the inert solvent suspension of aluminum sulfate tetradecahydrate is added to a three-necked flask, stirred evenly, and then the inert solvent solution of trimethylaluminum is slowly added dropwise under freezing conditions. After the addition is completed, the temperature is raised, the reaction is stirred, and the residue is filtered out. The filtrate is decompressed to remove part of the solvent to obtain a methylaluminoxane inert solvent solution; or the filtrate is decompressed to remove the solvent to obtain methylaluminoxane.
[0008] The mass ratio of aluminum sulfate tetradecahydrate to the inert solvent is (10-40):100; the particle size of the aluminum sulfate tetradecahydrate powder is 80-500 meshes; the inert solvent is C4-C15 saturated alkane, benzene or C1-C5 alkyl substituted benzene aromatic hydrocarbon or a mixture thereof, naphtha, kerosene or one or more mixtures thereof; the C4-C15 saturated alkane is pentane, hexane, decane, octane, C12 alkane, and the aromatic hydrocarbon substituted benzene is toluene, xylene, ethylbenzene, propylbenzene; the mass ratio of trimethylaluminum to the inert solvent is (10-40):100; the mass ratio of trimethylaluminum to aluminum sulfate tetradecahydrate is 0.8-1.5, preferably 0.9-1.2; the inert atmosphere is one or more of nitrogen, argon or helium.
[0009] The freezing condition is -80 to 5°C, preferably -40 to -10°C; the dropping time is 1 to 10 hours, preferably 2 to 5 hours; the stirring reaction temperature is -80 to 100°C, preferably 50 to 80°C; the reaction time of the stirring reaction is 5 to 48 hours, preferably 10 to 30 hours.
[0010] The technical solution adopted by the present invention to solve the technical problem is as follows: The beneficial effects of the method of the present invention are as follows: (1) The aluminum sulfate tetradecahydrate synthesized by the method of the present invention is subjected to a hydrolysis reaction with trimethylaluminum in an inert solvent, and the degree of the hydrolysis reaction can be precisely controlled, thereby obtaining a higher yield of 75%.
[0011] (2) The method of the present invention has simple process, low cost and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION
[0013] The present invention will be further described below in conjunction with the embodiments.
[0014] The concentration of trimethylaluminum used in the examples of the present invention and the comparative examples is 10-100%; the nitrogen used in the examples of the present invention and the comparative examples is a high-purity gas with a purity of ≥99.9%; the raw materials or chemical reagents used in the examples of the present invention, unless otherwise specified, are obtained through conventional commercial channels.
[0015] A method for synthesizing methylaluminoxane Example 1 Under nitrogen atmosphere, 0.05 mol of aluminum sulfate tetradecahydrate powder (100 mesh) was added to a three-necked flask, and then 150 mL of toluene was added. After stirring evenly, 250 mL of trimethylaluminum toluene solution (2 mol / L) was added dropwise through a constant pressure dropping funnel under -50°C freezing conditions. After 2 hours of dropping, the temperature was slowly raised to 50°C for stirring reaction for 30 hours; then the reaction solution was filtered, and the filter cake was washed 4 times with 200 ml of anhydrous toluene. The washing liquid was combined with the reaction solution and then distilled to obtain 213.8 g of 9.99% methylaluminoxane, with a yield of 69.8% and a trimethylaluminum conversion rate of 77.56%.
[0016] A method for synthesizing methylaluminoxane Example 2 Under nitrogen atmosphere, 458mL of trimethylaluminum decane solution (1mol / L) was taken in a three-necked flask, stirring was started to cool down, and 120ml of decane suspension of 0.05mol aluminum sulfate tetradecahydrate powder (200 mesh) was slowly added dropwise into the three-necked flask under -30℃ freezing conditions. After 3h of addition, the temperature was slowly raised to 60℃ for stirring reaction for 15h; then the reaction solution was filtered, and the filter cake was washed 4 times with 200ml of anhydrous decane. The washing liquid was combined with the reaction solution and then distilled to obtain 109.1g of 20.21% methylaluminoxane, with a yield of 78.2% and a trimethylaluminum conversion rate of 83.20%.
[0017] A method for synthesizing methylaluminoxane Example 3 Under nitrogen atmosphere, take 211.5mL trimethylaluminum xylene solution (1mol / L) in a three-necked flask, start stirring and cooling, add 0.05mol aluminum sulfate tetradecahydrate powder (200 mesh) and 150mL xylene dropwise into the three-necked flask under -20℃ freezing conditions, after 5h of dropwise addition, slowly raise the temperature to 70℃ and stir to react for 10h; then filter the reaction solution, wash the filter cake 4 times with 200ml anhydrous xylene, combine the washing solution with the reaction solution and distill to obtain 62.63g of 30.8% methylaluminoxane, with a yield of 74.5% and a trimethylaluminum conversion rate of 84.66%.
[0018] A method for synthesizing methylaluminoxane Example 4 Under nitrogen atmosphere, 0.05 mol of aluminum sulfate tetradecahydrate powder (200 mesh) was added to a three-necked flask, and then 120 mL of hexane was added. After stirring evenly, 392.9 mL of trimethylaluminum hexane solution (1 mol / L) was added dropwise through a constant pressure dropping funnel under -20°C freezing conditions. After 7 hours of dropping, the temperature was slowly raised to 80°C for stirring reaction for 5 hours; then the reaction solution was filtered, and the filter cake was washed 4 times with 200 ml of anhydrous hexane. The washing liquid was combined with the reaction solution and then distilled to obtain 146.9 g of 11.1% methylaluminoxane, with a yield of 67.8% and a trimethylaluminum conversion rate of 86.92%.
[0019] Comparative Example 1 Under nitrogen atmosphere, 0.05 mol of aluminum sulfate hexadecahydrate powder (100 mesh) was added to a three-necked flask, and then 150 mL of toluene was added. After stirring evenly, 250 mL of trimethylaluminum toluene solution (2 mol / L) was added dropwise through a constant pressure dropping funnel under -50°C freezing conditions. After 2 hours of dropping, the temperature was slowly raised to 50°C for stirring reaction for 30 hours; then the reaction solution was filtered, and the filter cake was washed 4 times with 200 ml of anhydrous toluene. The washing liquid was combined with the reaction liquid and distilled to obtain 146.3 g of 11.5% methylaluminoxane, with a yield of 55.01% and a trimethylaluminum conversion rate of 84.61%.
[0020] Comparative Example 2 Under nitrogen atmosphere, take 458mL of trimethylaluminum decane solution (1mol / L) in a three-necked flask, start stirring and cooling, and slowly drop 0.05mol of aluminum sulfate pentahydrate powder (200 mesh) in 120ml of decane suspension into the three-necked flask under -30℃ freezing conditions. After 3h of addition, slowly heat to 60℃ and stir to react for 15h; then filter the reaction solution, and wash the filter cake 4 times with 200ml of anhydrous decane. Combine the washing solution with the reaction solution and distill to obtain 87.58g of 19.6% methylaluminoxane, with a yield of 61.2% and a trimethylaluminum conversion rate of 88.69%.
[0021] Comparative Example 3 Under nitrogen atmosphere, take 211.5mL trimethylaluminum xylene solution (1mol / L) in a three-necked flask, start stirring and cooling, add 0.05mol aluminum sulfate tetradecahydrate powder (200 mesh) and 150mL xylene dropwise into the three-necked flask under -20℃ freezing conditions, after 5h of dropwise addition, slowly raise the temperature to 70℃ and stir to react for 10h; then filter the reaction solution, wash the filter cake 4 times with 200ml anhydrous xylene, combine the washing solution with the reaction solution and distill to obtain 53.33g of 30.2% methylaluminoxane, with a yield of 62.2% and a trimethylaluminum conversion rate of 82.93%.
[0022] Comparative Example 4 Under nitrogen atmosphere, 0.05 mol of aluminum sulfate dodecahydrate powder (200 mesh) was added to a three-necked flask, and then 120 mL of hexane was added. After stirring evenly, 392.9 mL of trimethylaluminum hexane solution (1 mol / L) was added dropwise through a constant pressure dropping funnel under -20°C freezing conditions. After 7 hours of dropping, the temperature was slowly raised to 80°C for stirring reaction for 5 hours; then the reaction solution was filtered, and the filter cake was washed 4 times with 200 ml of anhydrous hexane. The washing liquid was combined with the reaction solution and then distilled to obtain 47.41 g of 28.5% methylaluminoxane, with a yield of 56.2% and a trimethylaluminum conversion rate of 74.9%.
[0023] By comparing Examples 1 to 4 with Examples 1 to 4 Through comparative analysis of experimental data, aluminum sulfate tetrahydrate has obvious yield advantages in the synthesis of methylaluminoxane. Under the same molar ratio, the conversion rate of trimethylaluminum to aluminum sulfate tetrahydrate was significantly improved compared with aluminum sulfate tetrahydrate when aluminum sulfate hexahydrate and aluminum sulfate pentahydrate were used to synthesize methylaluminoxane, but the yield was low, mainly due to side reactions that affected the yield; the conversion rate of trimethylaluminum to aluminum sulfate tetrahydrate was slightly reduced compared with aluminum sulfate tetrahydrate when aluminum sulfate trihydrate and aluminum sulfate dodecahydrate were used, and the yield was also greatly reduced; this shows that the release of aluminum sulfate crystal water is different, and the crystal water that is easily released is easy to react with trimethylaluminum to generate side reactions, thereby affecting the yield, such as aluminum sulfate pentahydrate and aluminum sulfate hexahydrate; the crystal water of aluminum sulfate is reduced, and the difficulty of releasing the crystal water increases, and a higher temperature is required to gradually release it. The temperature rise leads to an increase in side reactions, so aluminum sulfate tridecahydrate and aluminum sulfate dodecahydrate have a low yield in the process of synthesizing methylaluminoxane.
[0024] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present invention should be subject to the scope of protection of the claims.
Claims
1. A method for synthesizing methylaluminoxane, characterized in that: The following steps are involved: Under an inert atmosphere, add an inert solvent solution of trimethylaluminum into a three-necked flask, start stirring, and then slowly add a suspension of aluminum sulfate tetradecahydrate under freezing conditions. After the addition is completed, heat up, stir and react, filter to remove the filter residue, and reduce the pressure of the filtrate to remove part of the solvent to obtain an inert solvent solution of methylaluminoxane; or reduce the pressure of the filtrate to remove the solvent to obtain methylaluminoxane.
2. The method for synthesizing methylaluminoxane according to claim 1, characterized in that: The order of adding aluminum sulfate tetradecahydrate and trimethylaluminum inert solvent solution can be changed. Specifically, under an inert atmosphere, the inert solvent suspension of aluminum sulfate tetradecahydrate is added to a three-necked flask, stirred evenly, and then the inert solvent solution of trimethylaluminum is slowly added dropwise under freezing conditions. After the addition is completed, the temperature is raised, the reaction is stirred, and the residue is filtered out, and the filtrate is decompressed to remove part of the solvent to obtain methylaluminoxane inert solvent solution; or the filtrate is decompressed to remove the solvent to obtain methylaluminoxane.
3. The method for synthesizing methylaluminoxane according to claim 1, 2, characterized in that: The mass ratio of aluminum sulfate tetradecahydrate to the inert solvent is (10-40):100; the particle size of the aluminum sulfate tetradecahydrate powder is 80-500 meshes; the inert solvent is C4-C15 saturated alkane, benzene or C1-C5 alkyl substituted benzene aromatic hydrocarbon or a mixture thereof, naphtha, kerosene or one or more mixtures thereof; the C4-C15 saturated alkane is pentane, hexane, decane, octane, C12 alkane, and the aromatic hydrocarbon substituted benzene is toluene, xylene, ethylbenzene, propylbenzene; the mass ratio of trimethylaluminum to the inert solvent is (10-40):100; the mass ratio of trimethylaluminum to aluminum sulfate tetradecahydrate is 0.8-1.5, preferably 0.9-1.2; the inert atmosphere is one or more of nitrogen, argon or helium.
4. The method for synthesizing methylaluminoxane according to claim 1 or 2, characterized in that: The freezing condition is -80 to 5°C, preferably -40 to -10°C; the dropping time is 1 to 10 hours, preferably 2 to 5 hours; the stirring reaction temperature is -80 to 100°C, preferably 50 to 80°C; the reaction time of the stirring reaction is 5 to 48 hours, preferably 10 to 30 hours.