Process for the preparation of polyethers

Abstract

This application provides a method for preparing polyether, comprising the following steps: adding a polyol initiator and a supported catalyst KF / γ-Al2O3 to a first reactor, heating to 90°C, then adding a first epoxide to the first reactor at a reaction temperature of 90-110°C, continuing the reaction at this temperature until the pressure inside the first reactor no longer decreases, and removing at least one of the water and low-boiling substances generated in the reaction to obtain a polyether intermediate; adding the supported catalyst KF / γ-Al2O3, an organic solvent, and the polyether intermediate to a second reactor, heating to 80°C, then adding a second epoxide to the second reactor at a reaction temperature of 80-100°C, and continuing the reaction at this temperature until the pressure inside the second reactor no longer decreases, and removing at least one of the low-boiling substances and the organic solvent to obtain a polyether. This preparation method is advantageous for further increasing the molecular weight of the polyether under the same conditions while also reducing the molecular weight distribution of the polyether product.

Description

Technical Field

[0001] This invention relates to the technical field of polymer preparation, and more specifically to a method for preparing polyethers. Background Technology

[0002] PAG quenching fluid is a water-soluble quenching fluid made from organic polymers. The organic polymer (PAG) is generally a polyether obtained by ring-opening polymerization of ethylene oxide and propylene oxide. Existing methods for preparing the polyether in quenching fluids typically involve: gradually adding a specified amount of ethylene oxide and propylene oxide dropwise in the presence of an active hydrogen-containing initiator under a specific temperature and pressure in the presence of an alkaline catalyst (such as an alkali metal hydride, alkali metal hydroxide, or alkali metal alkoxide catalyst). After the reaction is complete, the product from the previous step is used as the initiator, and the above steps are repeated. Existing preparation methods struggle to further increase the polymer molecular weight, and at high molecular weights, they cannot simultaneously achieve a narrow molecular weight distribution and high dynamic viscosity. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing polyether, which is advantageous for further increasing the molecular weight of polyether under the same conditions, while also reducing the molecular weight distribution of polyether products.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for preparing a polyether includes the following steps: A polyol initiator and a supported catalyst KF / γ-Al2O3 were added to the first reactor. After replacing the inert gas, the reactor was heated to 90°C. Then, a first epoxide was added to the first reactor to react at a temperature of 90-110°C. After the first epoxide was added, the reactor was kept at the temperature until the pressure inside the first reactor no longer decreased. After removing at least one of the water and low-boiling substances generated in the reaction, a polyether intermediate was obtained. The supported catalyst KF / γ-Al2O3, organic solvent, and the polyether intermediate were added to the second reactor. After replacing the inert gas, the reactor was heated to 80°C. Then, the second epoxide was added to the second reactor to react at a temperature of 80-100°C. After the second epoxide was added, the reactor was kept at this temperature until the pressure inside the second reactor no longer decreased. After removing at least one of the low-boiling substances and the organic solvent, the polyether was obtained.

[0005] In some possible implementations, both the first epoxide and the second epoxide are mixtures of propylene oxide and ethylene oxide, wherein the weight ratio of propylene oxide to ethylene oxide is 1:1-5, the amount of the first epoxide is 20-75 times the weight of the polyol initiator, and the amount of the second epoxide is 3-12 times the weight of the polyether intermediate.

[0006] In some possible implementations, in the step of obtaining the polyether intermediate, the amount of the supported catalyst added is 2‰-6‰ of the total weight of the polyol initiator and the first epoxide; In the step of obtaining the polyether, the amount of the supported catalyst added is 0.1‰-0.5‰ of the total weight of the polyether intermediate and the second epoxide.

[0007] In some possible implementations, the polyol initiator is selected from at least one of pentaerythritol, propylene glycol, trimethylolpropane, or glycerol.

[0008] In some possible implementations, the number-average molecular weight of the polyether intermediate is 2800-5800.

[0009] In some possible embodiments, the organic solvent is selected from at least one of toluene, n-propyl ether, or n-butyl ether.

[0010] In some possible embodiments, the preparation of the supported catalyst KF / γ-Al2O3 includes: CTAB, ethanol, and water are mixed in a specific ratio and then sonicated until the CTAB is completely dissolved to obtain a mixture. The mass ratio of CTAB to ethanol to water is 1:50-100:50-100. Al(NO3)3·9H2O is dissolved in the mixture, and the mixture is stirred at 20-40℃. After the solution becomes clear and transparent, the pH of the solution is adjusted to alkaline, and the mixture is kept warm and stirred until the reaction is complete. The supernatant is then discarded, and the remaining white precipitate is washed, filtered, and dried to obtain the carrier precursor. The carrier precursor is calcined at 300-400℃ for 1-3 hours, and then calcined at 400-600℃ for another 3-7 hours to obtain the γ-Al2O3 carrier. The mass ratio of CTAB to Al(NO3)3·9H2O is 1:10-20. After uniformly mixing the γ-Al2O3 support into deionized water, KF·2H2O was added. The mixture was stirred and impregnated at 70-85℃ for at least 24 hours, then dried. After calcination at 300-400℃ for 1-3 hours, the temperature was raised to 400-600℃ and calcined for another 3-7 hours to obtain the supported catalyst. The mass ratio of the γ-Al2O3 support to the KF·2H2O was 1:0.2-0.6.

[0011] In some possible implementations, the pH value is 9-10.

[0012] In some possible implementations, the amount of the organic solvent used is 30%-50% of the total weight of the polyether intermediate and the second epoxide.

[0013] In some possible embodiments, the polyether has a number-average molecular weight of 12,000-50,000, a dynamic viscosity of 12,000-180,000 mPa·s at 40°C, a viscosity index of 390-630, and a molecular weight distribution coefficient of 1.05-1.2.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: In this application, during the polyether preparation step, the polyether intermediate, the supported catalyst KF / γ-Al2O3, and the organic solvent are added to the reactor for reaction, allowing for sufficient contact between the three components. This facilitates further increasing the molecular weight of the polyether under the same conditions. Furthermore, the mesoporous structure of the KF / γ-Al2O3 support catalyst helps reduce byproducts during polymerization, thereby reducing the molecular weight distribution of the polyether product. Additionally, the supported catalyst facilitates subsequent separation from the product, thus improving the product's subsequent storage.

[0015] The present invention will be further described in detail below with reference to specific embodiments. Detailed Implementation

[0016] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] One embodiment of this application provides a method for preparing a polyether, comprising the following steps.

[0020] Step 1: Add the polyol initiator and the supported catalyst KF / γ-Al2O3 to the first reactor. After purging the inert gas, heat the reactor to 90°C. Then, add the first epoxide to the reactor and react at 90-110°C. After adding the first epoxide, continue heating until the pressure inside the reactor no longer decreases. After removing at least one of the water and low-boiling substances generated in the reaction, a polyether intermediate is obtained. For example, the heating time can be 2-3 hours. For example, at least one of the water and low-boiling substances generated in the reaction can be removed by vacuuming. For example, low-boiling substances refer to substances with a boiling point below 110°C. For example, after removing at least one of the water and low-boiling substances generated in the reaction, the material can be cooled to below 60°C for later use.

[0021] In some embodiments, the polyol initiator is selected from at least one of pentaerythritol, propylene glycol, trimethylolpropane, or glycerol.

[0022] In some embodiments, the first epoxide is a mixture of propylene oxide and ethylene oxide, wherein the weight ratio of propylene oxide to ethylene oxide is 1:1-5, and the amount of the first epoxide is 20-75 times the weight of the polyol initiator.

[0023] In some embodiments, in this step of obtaining the polyether intermediate, the amount of the supported catalyst added is 2‰-6‰ of the total weight of the polyol initiator and the first epoxide.

[0024] In some embodiments, the number-average molecular weight of the polyether intermediate is 2800-5800. For example, the number-average molecular weight can be selected from 2800, 2850, 4000, 5770, 5800 and any value between the above values.

[0025] In some embodiments, the preparation of the supported catalyst KF / γ-Al2O3 includes the following steps.

[0026] CTAB (short for hexadecyltrimethylammonium bromide), ethanol, and water are mixed in a specific ratio and then sonicated until the CTAB is completely dissolved to obtain a mixture. For example, this can be done by sonication for 10-15 minutes in an ultrasonic cleaner. The mass ratio of CTAB to ethanol to water is 1:50-100:50-100. CTAB is used as a pore-expanding agent. Al(NO3)3·9H2O is dissolved in a mixed solution and stirred at 20-40℃. After the solution becomes clear and transparent, the pH of the solution is adjusted to alkaline (for example, this can be done by adding ammonia). The solution is kept warm and stirred until the reaction is complete, then the supernatant is discarded. The remaining white precipitate is washed (for example, three times with deionized water), filtered, and dried (for example, a freeze dryer can be used to maintain the crystal form and dispersibility of the material) to obtain the carrier precursor. The carrier precursor is calcined at 300-400℃ for 1-3 hours, then heated to 400-600℃ and calcined for another 3-7 hours to obtain the γ-Al2O3 carrier. The mass ratio of CTAB to Al(NO3)3·9H2O is 1:10-20. For example, calcination can be carried out in a tube furnace. The heating rate can be 15℃ / min. The carrier can be a mesoporous γ-Al2O3 carrier. For example, the carrier can be placed in a desiccator for later use.

[0027] In some embodiments, the pH value is 9-10.

[0028] After uniformly mixing the γ-Al₂O₃ support with deionized water, KF·₂H₂O is added. The mixture is stirred at 70-85°C (magnetic stirring can be used as an example) and impregnated for at least 24 hours, then dried (exemplarily, in a freeze-drying oven). Following this, it is calcined at 300-400°C for 1-3 hours, then heated to 400-600°C and calcined for another 3-7 hours to obtain the supported catalyst. For example, the heating rate is 15°C / min. The mass ratio of the γ-Al₂O₃ support to the KF·₂H₂O is 1:0.2-0.6.

[0029] Step 2: The supported catalyst KF / γ-Al2O3, organic solvent, and the polyether intermediate are added to the second reactor. After purging with an inert gas, the reactor is heated to 80°C. Then, a second epoxide is added to the second reactor for reaction at 80-100°C. After the second epoxide is added, the reactor is kept at this temperature until the pressure inside the reactor no longer decreases. At least one of the low-boiling substances and the organic solvent is removed to obtain the polyether. For example, the reaction time can be 2-3 hours. For example, at least one of the low-boiling substances and the organic solvent can be removed by vacuuming. For example, low-boiling substances refer to substances with a boiling point below 110°C. For example, nitrogen can be used as the inert gas in any of the above steps.

[0030] In some embodiments, the second epoxide is a mixture of propylene oxide and ethylene oxide, wherein the weight ratio of propylene oxide to ethylene oxide is 1:1-5. The amount of the second epoxide used is 3-12 times the weight of the polyether intermediate, for example, 3 times, 3.2 times, 12 times, or any value between the above values.

[0031] In some embodiments, during the step of obtaining the polyether, the amount of the supported catalyst added is 0.1‰-0.5‰ of the total weight of the polyether intermediate and the second epoxide.

[0032] In some embodiments, the organic solvent is selected from at least one of toluene, n-propyl ether, or n-butyl ether.

[0033] In some embodiments, the amount of the organic solvent used is 30%-50% of the total weight of the polyether intermediate and the second epoxide.

[0034] In some embodiments, the polyether has a number-average molecular weight of 12,000-50,000, a dynamic viscosity of 12,000-180,000 mPa·s at 40°C, a viscosity index of 390-630, and a molecular weight distribution coefficient of 1.05-1.2. For example, the distribution coefficient can be 1.05, 1.056, 1.193, 1.2, or any value between the above values.

[0035] In this application, during the polyether preparation step, the polyether intermediate, the supported catalyst KF / γ-Al2O3, and the organic solvent are added to the reactor for reaction, allowing for sufficient contact between the three components. This facilitates further increasing the molecular weight of the polyether under the same conditions. Furthermore, the mesoporous structure of the KF / γ-Al2O3 support catalyst helps reduce byproducts during polymerization, thereby reducing the molecular weight distribution of the polyether product. Additionally, the supported catalyst facilitates subsequent separation from the product, thus improving the product's subsequent storage.

[0036] The following are detailed implementation methods.

[0037] Preparation of supported catalyst 1: (1) Weigh 16 g of CTAB and dissolve it in 1500 mL of a 1:1 (mass ratio) ethanol-water mixture (correspondingly, the mass ratio of CTAB:ethanol:water is 1:50:50). Then, sonicate the mixture in an ultrasonic cleaner for 10-15 min until CTAB is completely dissolved in the solution to obtain a mixture. Accurately weigh 225 g of Al(NO3)3·9H2O (correspondingly, the mass ratio of CTAB:Al(NO3)3·9H2O is 1:14) and add it to the mixture. Stir mechanically at 30 °C until the solution is clear and transparent. Then, start adding diluted ammonia water dropwise until the pH of the solution is 9-10. React for 12 h and overnight. Discard the supernatant, take the white precipitate, wash it three times with deionized water, filter it, and place it in a freeze dryer (to maintain the crystal form and dispersibility) to dry, to obtain a white solid (carrier precursor). Finally, the white solid was calcined in a tube furnace at 350 °C for 2 h, then heated to 550 °C for 6 h at a heating rate of 15 °C / min. After removing CTAB, mesoporous γ-Al₂O₃ support was obtained and placed in a desiccator for later use.

[0038] (2) Weigh 10 g of the prepared mesoporous γ-Al2O3 support into a 500 mL flask, add 50 mL of deionized water, mix well, and then add 5 g of KF·2H2O (correspondingly, the mass ratio of the γ-Al2O3 support to the KF·2H2O is 1:0.5). Then, use magnetic stirring to impregnate at 80 °C for 24 h, remove the solution and place it in a freeze dryer to dry. Afterwards, calcine it in a tube furnace at 350 °C for 2 h, and then raise the temperature to 550 °C for 6 h, with a heating rate of 15 °C / min. Finally, the supported mesoporous solid strong base KF / γ-Al2O3 catalyst can be obtained and placed in a desiccator for later use.

[0039] Preparation of polyether intermediate 1: 58g of propylene glycol initiator and 26.4g of the prepared supported catalyst KF / γ-Al2O3 were added to a high-pressure reactor (first reactor). After purging with nitrogen, the reactor was heated. When the temperature inside the reactor reached 90°C, 2175g of ethylene oxide (EO) and 2175g of propylene oxide (PO) were simultaneously introduced into the reactor. The ethylene oxide and propylene oxide mixed to form the first epoxide. The reaction temperature was controlled at 90-110°C. After the first epoxide was added, the reactor was kept at this temperature until the pressure inside the reactor no longer decreased. The reaction continued for 2-3 hours. After the reaction was completed, low-boiling substances were removed using a vacuum, and the temperature was lowered to below 60°C for later use, yielding a polyether intermediate. Correspondingly, the amount of the supported catalyst added was 6‰ of the total weight of the polyol initiator and the first epoxide. The amount of the first epoxide was 75 times the weight of the polyol initiator.

[0040] Catalysts 2-4 differ from catalyst 1, as detailed below.

[0041] Catalysts 2-4 are the same as catalyst 1, except for the changes in the mass ratio of substances and time parameters in the table below.

[0042]

[0043] Polyether intermediates 2-4 differ from polyether intermediate 1, as detailed below.

[0044] For details, please refer to the summary table below.

[0045]

[0046] As can be seen from the above, in polyether intermediate 1, the amount of the first epoxide is 75 times the weight of the polyol initiator; in polyether intermediate 2, the amount of the first epoxide is 28.9 times the weight of the polyol initiator; in polyether intermediate 3, the amount of the first epoxide is 42.5 times the weight of the polyol initiator; and in polyether intermediate 4, the amount of the first epoxide is 20 times the weight of the polyol initiator.

[0047] In the step of obtaining the polyether intermediate, the amount of the supported catalyst added is 2‰-6‰ of the total weight of the polyol initiator and the first epoxide.

[0048] Preparation of high molecular weight polyether The prepared polyether intermediate, 2g of the prepared supported catalyst KF / γ-Al₂O₃, and solvent were added to a high-pressure reactor (second reactor). After purging with nitrogen, the reactor was heated to 80°C. A mixture of ethylene oxide and propylene oxide (second epoxide) was then simultaneously introduced into the reactor. The reaction temperature was controlled at 80-100°C. After the epoxide was added, the reactor was kept at this temperature until the pressure inside the second reactor no longer decreased. The reaction continued for 2-3 hours. After the reaction was complete, low-boiling substances and solvent were removed under vacuum to obtain the polyether.

[0049] The parameters of the polyethers in Examples 1 to 5 are statistically analyzed as follows.

[0050]

[0051] As can be seen from the above, in Example 1, the amount of the second epoxide was 3.2 times the weight of the polyether intermediate; in Example 2, the amount of the second epoxide was 5.25 times the weight of the polyether intermediate; in Example 3, the amount of the second epoxide was 6.5 times the weight of the polyether intermediate; in Example 4, the amount of the second epoxide was 12 times the weight of the polyether intermediate; and in Example 5, the amount of the second epoxide was 6.8 times the weight of the polyether intermediate. As can be seen from the above embodiments, in the step of obtaining polyether, in Example 1, the amount of the supported catalyst added is 0.1‰ of the total weight of the polyether intermediate and the second epoxide; in Example 2, the amount of the supported catalyst added is 0.2‰ of the total weight of the polyether intermediate and the second epoxide; in Example 3, the amount of the supported catalyst added is 0.3‰ of the total weight of the polyether intermediate and the second epoxide; in Example 4, the amount of the supported catalyst added is 0.1‰ of the total weight of the polyether intermediate and the second epoxide; and in Example 5, the amount of the supported catalyst added is 0.5‰ of the total weight of the polyether intermediate and the second epoxide.

[0052] As can be seen from the above embodiments, in Embodiment 1, the amount of organic solvent used is 30% of the total weight of the polyether intermediate and the second epoxide; in Embodiment 2, the amount of organic solvent used is 30% of the total weight of the polyether intermediate and the second epoxide; in Embodiment 3, the amount of organic solvent used is 35% of the total weight of the polyether intermediate and the second epoxide; in Embodiment 4, the amount of organic solvent used is 40% of the total weight of the polyether intermediate and the second epoxide; and in Embodiment 5, the amount of organic solvent used is 50% of the total weight of the polyether intermediate and the second epoxide.

[0053] Comparative Example 1 680g of pentaerythritol (PE) initiator and 2g of KOH catalyst were added to a high-pressure reactor. After purging with nitrogen, the reactor was heated. When the temperature inside the reactor reached 90℃, 1100g of ethylene oxide and 220g of propylene oxide were simultaneously introduced into the reactor. The reaction temperature was controlled at 90-110℃. After the addition was complete, the reactor was kept at this temperature until the pressure inside the reactor no longer decreased, a process that took 2-3 hours. After the reaction was complete, low-boiling-point substances were removed using vacuum. The first polyether intermediate (pentaerythritol polyether 400) was obtained.

[0054] 400g of the first polyether intermediate and 2g of KOH catalyst were added to a high-pressure reactor. After purging with nitrogen, the reactor was heated to 80°C. Then, 3000g of ethylene oxide and 600g of propylene oxide were simultaneously introduced into the reactor. The reaction temperature was controlled between 80-100°C, and the reactor was kept at this temperature until the pressure no longer decreased. The reaction time was 2-3 hours. After the reaction was complete, low-boiling-point substances were removed under vacuum to obtain the second polyether intermediate 4000.

[0055] 1333g of the prepared second polyether intermediate and 2g of KOH catalyst were added to a high-pressure reactor. After purging with nitrogen, the reactor was heated to 80°C. Then, 2222g of ethylene oxide and 444g of propylene oxide were simultaneously introduced into the reactor. The reaction temperature was controlled between 80-100°C, and the reactor was kept at this temperature until the pressure no longer decreased. The reaction time was 2-3 hours. After the reaction was complete, low-boiling-point substances were removed under vacuum to obtain a high molecular weight polyether.

[0056] Comparative Examples 2-5 The difference from Comparative Example 1 is that the type and amount of initiator, the type of catalyst, and the amounts of ethylene oxide and propylene oxide were adjusted. See the table below for details.

[0057]

[0058] The test results of the above embodiments and comparative examples are shown in the table below.

[0059]

[0060] Dynamic viscosity (40℃) and dynamic viscosity (100℃) were both measured according to GB 265-1988.

[0061] Molecular weight (Mn) and distribution coefficient were determined by gel permeation chromatography (GPC). A 0.01 g / mL solution was prepared using chromatographically pure tetrahydrofuran as the mobile phase, and the test temperature was 40 °C.

[0062] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a polyether, characterized in that, Includes the following steps: A polyol initiator and a supported catalyst KF / γ-Al2O3 were added to the first reactor. After replacing the inert gas, the reactor was heated to 90°C. Then, a first epoxide was added to the first reactor to react at a temperature of 90-110°C. After the first epoxide was added, the reactor was kept at the temperature until the pressure inside the first reactor no longer decreased. After removing at least one of the water and low-boiling substances generated in the reaction, a polyether intermediate was obtained. The supported catalyst KF / γ-Al2O3, organic solvent, and the polyether intermediate were added to the second reactor. After replacing the inert gas, the reactor was heated to 80°C. Then, the second epoxide was added to the second reactor to react at a temperature of 80-100°C. After the second epoxide was added, the reactor was kept at this temperature until the pressure inside the second reactor no longer decreased. After removing at least one of the low-boiling substances and the organic solvent, the polyether was obtained.

2. The preparation method according to claim 1, characterized in that, Both the first epoxide and the second epoxide are mixtures of propylene oxide and ethylene oxide, wherein the weight ratio of propylene oxide to ethylene oxide is 1:1-5, the amount of the first epoxide is 20-75 times the weight of the polyol initiator, and the amount of the second epoxide is 3-12 times the weight of the polyether intermediate.

3. The preparation method according to claim 1, characterized in that, In the step of obtaining the polyether intermediate, the amount of the supported catalyst added is 2‰-6‰ of the total weight of the polyol initiator and the first epoxide; In the step of obtaining the polyether, the amount of the supported catalyst added is 0.1‰-0.5‰ of the total weight of the polyether intermediate and the second epoxide.

4. The preparation method according to claim 1, characterized in that, The polyol initiator is selected from at least one of pentaerythritol, propylene glycol, trimethylolpropane, or glycerol.

5. The preparation method according to claim 1, characterized in that, The number-average molecular weight of the polyether intermediate is 2800-5800.

6. The preparation method according to claim 1, characterized in that, The organic solvent is selected from at least one of toluene, n-propyl ether, or n-butyl ether.

7. The preparation method according to claim 1, characterized in that, The preparation of the supported catalyst KF / γ-Al2O3 includes: CTAB, ethanol, and water are mixed in a specific ratio and then sonicated until the CTAB is completely dissolved to obtain a mixture. The mass ratio of CTAB to ethanol to water is 1:50-100:50-100. Al(NO3)3·9H2O is dissolved in the mixture, and the mixture is stirred at 20-40℃. After the solution becomes clear and transparent, the pH of the solution is adjusted to alkaline, and the mixture is kept warm and stirred until the reaction is complete. The supernatant is then discarded, and the remaining white precipitate is washed, filtered, and dried to obtain the carrier precursor. The carrier precursor is calcined at 300-400℃ for 1-3 hours, and then calcined at 400-600℃ for another 3-7 hours to obtain the γ-Al2O3 carrier. The mass ratio of CTAB to Al(NO3)3·9H2O is 1:10-20. After uniformly mixing the γ-Al2O3 support into deionized water, KF·2H2O was added. The mixture was stirred and impregnated at 70-85℃ for at least 24 hours, then dried. After calcination at 300-400℃ for 1-3 hours, the temperature was raised to 400-600℃ and calcined for another 3-7 hours to obtain the supported catalyst. The mass ratio of the γ-Al2O3 support to the KF·2H2O was 1:0.2-0.

6.

8. The preparation method according to claim 7, characterized in that, The pH value is 9-10.

9. The preparation method according to claim 6, characterized in that, The amount of organic solvent used is 30%-50% of the total weight of the polyether intermediate and the second epoxide.

10. The preparation method according to any one of claims 1 to 9, characterized in that, The polyether has a number-average molecular weight of 12,000-50,000, a dynamic viscosity of 12,000-180,000 mPa·s at 40°C, a viscosity index of 390-630, and a molecular weight distribution coefficient of 1.05-1.2.

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