Preparation method of polyethylene oxide synthesis catalyst, catalyst prepared by the method and its uses

Abstract

A method for preparing a polyethylene oxide catalyst, the catalyst prepared by this method, and the uses of the catalyst are disclosed. The method uses calcium alkoxide, organoaluminum, and water as raw materials, reacting them in an organic solvent under a closed environment. After the reaction is complete, the polyethylene oxide catalyst is obtained. The method for preparing the polyethylene oxide catalyst of this invention features mild process conditions, simple operation, and can significantly reduce manufacturing costs. The obtained catalyst has high catalytic activity and can produce polyethylene oxide products with high molecular weight in high yields.

Description

Technical Field

[0001] This invention relates to the field of epoxide polymerization, and more specifically, to a method for preparing a catalyst for the synthesis of polyethylene oxide, the catalyst prepared by the method, and the use of the catalyst. Background Technology

[0002] Epoxyalkane polymers are low-toxicity, low-ash, water-soluble polymers with excellent solution rheological properties and binding ability with organic solvents. They also exhibit good dispersing and thickening effects. Therefore, they have broad application prospects in industries such as daily chemicals, pharmaceuticals, papermaking and printing, oil extraction and mining, and new materials.

[0003] The key to synthesizing high molecular weight polyethylene oxide (PEO) lies in the selection of catalysts. Currently, the main catalysts available for PEO synthesis are alkyl metal catalysts and alkaline earth metal ammonium catalysts. Alkyl metal catalyst systems mainly include alkoxyaluminum-water-acetylacetone systems, alkylaluminum-water-acetylacetone systems, alkylaluminum-water-zinc acetylacetone systems, and alkylaluminum-water-rare earth metal systems. The preparation of alkaline earth metal ammonium catalysts typically involves reacting alkaline earth metals, such as calcium, with liquid ammonia under predetermined conditions (-34°C) to generate calcium ammonium, followed by further modification with epoxides and organic nitriles, and finally aging. When used for epoxide alkane polymerization, this catalyst, through coordination polymerization, yields products with high degrees of polymerization. However, this catalyst system requires the use of liquid ammonia during preparation, necessitates low-temperature conditions, and carries the risk of liquid ammonia leakage.

[0004] As mentioned above, the current high molecular weight polyethylene oxide synthesis catalyst system has drawbacks such as complicated processes, harsh conditions, and the need for catalyst aging. Therefore, further improvements are needed to the catalyst preparation methods to simplify the process, reduce costs, and obtain catalyst products with high catalytic activity in the synthesis of high molecular weight polyethylene oxide. Summary of the Invention

[0005] To solve the above problems, on the one hand, the present invention provides a method for preparing a polyethylene oxide catalyst, the method comprising: (1) adding organoaluminum, distilled water and organic solvent into a sealed container and stirring at 20°C for 0.5 h under an inert atmosphere for pretreatment; (2) adding calcium alkoxide salt into it and reacting in a sealed container under an inert atmosphere, and obtaining a polyethylene oxide catalyst after the reaction is completed.

[0006] On the other hand, the present invention provides a polyethylene oxide catalyst obtained according to the aforementioned preparation method.

[0007] In another aspect, the present invention provides the use of the aforementioned catalyst in the precipitation polymerization of high molecular weight polyethylene oxide.

[0008] Compared with existing technologies, the method for preparing the polyethylene oxide catalyst of the present invention features mild process conditions, simple operation, and can significantly reduce the manufacturing cost of the catalyst. According to the preparation method of the present invention, a highly active product is formed through the interaction between calcium alkoxide and organoaluminum, which significantly enhances the catalytic activity of the obtained catalyst in the synthesis of polyethylene oxide, thereby enabling the high-yield production of polyethylene oxide products with high molecular weight. Detailed Implementation

[0009] The present application will be further described in detail below through embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0010] Furthermore, the technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0011] On the one hand, the present invention provides a method for preparing a polyethylene oxide catalyst, the method comprising: (1) adding organoaluminum, distilled water and organic solvent into a sealed container and pretreating by stirring at 20°C for 0.5 h under an inert atmosphere; (2) adding calcium alkoxide salt into the container and reacting in a sealed container under an inert atmosphere, and obtaining a polyethylene oxide catalyst after the reaction is completed.

[0012] The preparation method of this invention involves reacting calcium alkoxide and organoaluminum in a suitable organic solvent in the presence of water. The resulting catalyst product is soluble in the added organic solvent to form a solution. The reaction is carried out at a set temperature, and the solvent acts as a heat transfer medium to dissipate the heat released during the exothermic reaction, making the reaction temperature easy to control.

[0013] In one embodiment of the preparation method according to the present invention, the calcium alkoxide may be of the general formula (R 0 O)2Ca is a calcium alkoxide salt, where R is a calcium salt of O)2Ca. 0 It represents an alkyl group having 1 to 4 carbons; preferably, it is selected from one or more of calcium methoxide, calcium ethanol, calcium isopropoxide, and calcium butoxide.

[0014] In another embodiment of the preparation method according to the present invention, the organoaluminum can be of the general formula (R 1 )3Al or (R 2 O)3Al alkylaluminum or aluminum alkoxide, where R is an alkylaluminum or aluminum alkoxide of O)3Al. 1 and R 2 Each of them represents an alkyl group having 1 to 4 carbons; preferably, they are selected from one or more of trimethylaluminum, triethanolamine, triethylaluminum, triisobutylaluminum, and tert-butoxide aluminum.

[0015] In another embodiment of the preparation method according to the present invention, the organic solvent is a non-polar organic solvent, preferably one or more selected from n-heptane, n-hexane, benzene, toluene, and xylene.

[0016] In another embodiment of the preparation method according to the present invention, the molar ratio of the calcium alkoxide and the organoaluminum is 1:0.01 to 1:0.2.

[0017] In another embodiment of the preparation method according to the present invention, the reaction temperature is 50–100°C, regardless of the solvent used.

[0018] In another embodiment of the preparation method according to the present invention, the reaction time is 2 to 6 hours.

[0019] According to the preparation method of the present invention, in the presence of water, the above-mentioned calcium alkoxide and organoaluminum are placed in a reaction vessel such as a reaction kettle, and then the above-mentioned organic solvent is added, wherein the calcium alkoxide and organoaluminum dissolve in the added organic solvent to form a solution. Subsequently, the reaction vessel is sealed and purged with an inert gas, such as nitrogen, and the reaction is carried out at a set temperature.

[0020] Under the above reaction conditions, calcium alkoxides and organoaluminum undergo a related reaction in solution to generate a species with ethoxylation activity, the composition of which is (R 1 )2Al-O-CaOR 0 or (R) 2 O)2Al-O-CaOR 0 The reaction equation is as follows;

[0021] (R 1 )3Al + H2O → (R 1 )2Al-OH+R 1 H

[0022] (R 1 )2Al-OH+(R 0 O)2Ca→(R 1 )2Al-O-CaOR 0 +R 0 OH

[0023] or

[0024] (R 2 O)3Al + H2O → (R 2 O)2Al-OH+R 2 OH

[0025] (R 2 O)2Al-OH+(R 0 O)2Ca→(R 2O)2Al-O-CaOR 0 +R 0 OH

[0026] On the other hand, the present invention provides a polyethylene oxide catalyst prepared according to the aforementioned preparation method.

[0027] In another aspect, the present invention provides the use of the aforementioned catalyst in the precipitation polymerization of high molecular weight polyethylene oxide.

[0028] As mentioned above, according to the preparation method of the present invention, calcium alkoxide and organoaluminum are used as raw materials, and the synthesized catalyst has the following composition (R). 1 )2Al-O-CaOR 0 or (R) 2 O)2Al-O-CaOR 0 .

[0029] The catalyst prepared in this invention is applied to the precipitation polymerization process of polyethylene oxide. The polymerization reaction is carried out at 10℃~40℃ for 16-28h. The solvent and polymer are separated by filtration and vacuum drying to obtain polyethylene oxide product with a yield of 95-99% and a viscosity-average molecular weight of 1 million-5 million.

[0030] The present invention will be further illustrated below through examples and comparative examples.

[0031] In the following examples, a catalyst was prepared according to the preparation method of the present invention, and the catalyst was used for the synthesis of polyethylene oxide. The yield and molecular weight of the obtained polyethylene oxide product were determined. The relative molecular mass of polyethylene oxide was determined according to GB / T1841-1980, and the intrinsic viscosity of the polyethylene oxide product was determined. The viscosity-average molecular weight Mv of the product was calculated based on the measured intrinsic viscosity value using the following formula:

[0032] [η] = 12.5 × 10 5 ×Mv 0.78

[0033] Where: Mv—the average relative molecular weight of the product, g / mol;

[0034] [η]——The intrinsic viscosity of the product, dl / g.

[0035] The polyethylene oxide aqueous solution used in the above determination had a mass concentration of 0.1% and a measurement temperature of 30℃.

[0036] Unless otherwise specified, the materials and reagents used in the embodiments and comparative examples are all commercially available, such as commercially available analytical grade chemical reagents.

[0037] Example 1

[0038] (1) Preparation of catalyst

[0039] 0.001 mol of triethylaluminum, 0.002 mol of distilled water and 50 ml of n-heptane were added to a reaction vessel. After sealing, nitrogen was purged three times. After stirring at room temperature for 0.5 h, 0.1 mol of calcium methoxide was added. After sealing, nitrogen was purged three times again. The mixture was then heated to 50 °C and stirred for 2 h to obtain a polyethylene oxide catalyst.

[0040] (2) Polymerization of ethylene oxide

[0041] Take 1g (solid content) of the above catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 16h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 97% and the viscosity-average molecular weight is 1.1 million.

[0042] Example 2

[0043] (1) Preparation of catalyst

[0044] 0.02 mol of trimethylaluminum, 0.014 mol of distilled water and 50 ml of toluene were added to a reaction vessel. After sealing, nitrogen was purged three times. After stirring at room temperature for 0.5 h, 0.1 mol of calcium isopropoxide was added. After sealing, nitrogen was purged three times again. The temperature was then raised to 80 °C and stirred for 3 h to obtain a polyethylene oxide catalyst.

[0045] (2) Polymerization of ethylene oxide

[0046] Take 1g (solid content) of catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 20h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 95% and the viscosity-average molecular weight is 2.6 million.

[0047] Example 3

[0048] (1) Preparation of catalyst

[0049] 0.01 mol of triisobutylaluminum, 0.012 mol of distilled water and 50 ml of n-heptane were added to a reaction vessel. After sealing, nitrogen was purged three times. After stirring at room temperature for 0.5 h, 0.1 mol of calcium ethoxide was added. After sealing, nitrogen was purged three times again. The temperature was then raised to 70 °C and stirred for 6 h to obtain a polyethylene oxide catalyst.

[0050] (2) Polymerization of ethylene oxide

[0051] Take 1g (solid content) of catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 22h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 99% and the viscosity-average molecular weight is 3.2 million.

[0052] Example 4

[0053] (1) Preparation of catalyst

[0054] 0.015 mol aluminum tert-butoxide, 0.015 mol distilled water and 50 ml toluene were added to a reaction vessel. After sealing, nitrogen was purged three times. After stirring at room temperature for 0.5 h, 0.1 mol calcium methoxide was added. After sealing, nitrogen was purged three times again. The temperature was then raised to 65 °C and stirred for 3 h to obtain a polyethylene oxide catalyst.

[0055] (2) Polymerization of ethylene oxide

[0056] Take 1g (solid content) of catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 24h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 96% and the viscosity-average molecular weight is 4.6 million.

[0057] Example 5

[0058] (1) Preparation of catalyst

[0059] 0.008 mol of aluminum triethanolamine, 0.008 mol of distilled water and 50 ml of n-hexane were added to a reaction vessel. After sealing, nitrogen was purged three times. After stirring at room temperature for 0.5 h, 0.1 mol of calcium ethoxide was added. After sealing, nitrogen was purged three times again. The mixture was then heated to 90 °C and stirred for 5 h to obtain a polyethylene oxide catalyst.

[0060] (2) Polymerization of ethylene oxide

[0061] Take 1g (solid content) of catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 28h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 98% and the viscosity-average molecular weight is 4.9 million.

[0062] Example 6

[0063] (1) Preparation of catalyst

[0064] 0.005 mol of triisobutylaluminum, 0.0075 mol of distilled water and 50 ml of n-heptane were added to a reaction vessel. After sealing, the mixture was purged with nitrogen three times. After stirring at room temperature for 0.5 h, 0.1 mol of calcium isopropoxide was added. After sealing, the mixture was purged with nitrogen three times again. The temperature was then raised to 100 °C and stirred for 4 h to obtain a polyethylene oxide catalyst.

[0065] (2) Polymerization of ethylene oxide

[0066] Take 1g (solid content) of catalyst and add 500ml of n-hexane to a 2L reactor. After purging with nitrogen, start the stirrer and lower the temperature inside the reactor to about 10℃, the initiation temperature. Slowly add 200g of ethylene oxide and then gradually increase the polymerization temperature. The polymerization reaction is carried out at 10℃~40℃ for 18h. Filter to separate the solvent and the obtained polymer. After vacuum drying, polyethylene oxide is obtained. The yield is 97% and the viscosity-average molecular weight is 3.5 million.

[0067] Comparative Example 1

[0068] 1g of calcium isopropoxide and 500ml of n-hexane were added to a 2L reactor. After purging with nitrogen, the stirrer was started and the temperature inside the reactor was lowered to about 10℃, the initiation temperature. 200g of ethylene oxide was slowly added, and then the polymerization reaction temperature was gradually increased. The polymerization reaction was carried out at 10℃~40℃ for 18h. The solvent and the obtained polymer were separated by filtration. After vacuum drying, polyethylene oxide was obtained. The yield was 10% and the viscosity-average molecular weight was 13,000.

[0069] Comparative Example 2

[0070] 1g of triisobutylaluminum, 0.09g of distilled water, and 500ml of n-hexane were added to a 2L reactor. After purging with nitrogen, the stirrer was started and the temperature inside the reactor was lowered to about 10℃, the initiation temperature. 200g of ethylene oxide was slowly added, and then the polymerization reaction temperature was gradually increased. The polymerization reaction was carried out at 10℃~40℃ for 18h. The solvent and the obtained polymer were separated by filtration. After vacuum drying, polyethylene oxide was obtained. The yield was 8% and the viscosity-average molecular weight was 17,000.

[0071] Comparative Example 3

[0072] The steps described in Example 5 were repeated, except that during the catalyst preparation process, organoaluminum, distilled water and organic solvent were added to a sealed container and pretreated by stirring at 20°C for 0.5 h under an inert atmosphere. Then, calcium alkoxide was added and stirred briefly before being directly used for the precipitation polymerization of polyethylene oxide to obtain polyethylene oxide. The yield was 14% and the viscosity-average molecular weight was 21,000.

[0073] Comparative Example 4

[0074] The steps described in Example 3 were repeated, except that the amount of triisobutylaluminum added during catalyst preparation was 0.1 mol and the amount of distilled water added was 0.12 mol. The obtained polyethylene oxide had a yield of 18% and a viscosity-average molecular weight of 19,000.

[0075] As can be seen from the above examples and comparative examples, the polyethylene oxide catalyst prepared according to the method of the present invention has high catalytic activity and low dosage when applied to ethylene oxide polymerization, which significantly improves the synthesis yield of the obtained polyethylene oxide products and can synthesize high molecular weight polyethylene oxide products with molecular weights of 1 million to 5 million.

[0076] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely illustrative and exemplary. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the scope of protection of the present application.

Claims

1. A method for preparing a polyethylene oxide catalyst, the method comprising: (1) Add organoaluminum, distilled water and organic solvent into a sealed container and stir at 20°C for 0.5 h under an inert atmosphere for pretreatment; (2) Add calcium alkoxide salt into it and react in a sealed container under an inert atmosphere. After the reaction is completed, a polyethylene oxide catalyst is obtained. The calcium alkoxide salt is selected from the general formula (R 0 One or more of the calcium alkoxides represented by O)2Ca, where R is a calcium alkoxide salt. 0 Represents an alkyl group having 1 to 4 carbon atoms; The organoaluminum is selected from one or more of the alkylaluminum represented by general formula (R¹)3Al and the aluminum alkoxide represented by general formula (R²O)3Al, where R¹ and R² each represent an alkyl group having 1 to 4 carbons. The molar ratio of the calcium alkoxide and organoaluminum is 1:0.01~0.2; The molar ratio of distilled water to organoaluminum is 1:0.5~1.5; The reaction temperature is 50~100℃.

2. The method according to claim 1, wherein the calcium alkoxide is selected from one or more of calcium methoxide, calcium ethanol, calcium isopropoxide, and calcium butoxide.

3. The method according to claim 1, wherein the organoaluminum is selected from one or more of trimethylaluminum, triethanolamine, triethylaluminum, triisobutylaluminum, and aluminum tert-butoxide.

4. The method according to claim 1, wherein the organic solvent is one or more selected from n-heptane, n-hexane, benzene, toluene, and xylene.

5. The method according to claim 1, wherein the reaction time is 2-6 h.

6. A polyethylene oxide catalyst prepared according to the preparation method of any one of the preceding claims.

7. Use of the catalyst according to claim 6 in the precipitation polymerization of high molecular weight polyethylene oxide.