A preparation method of high molecular weight polyethylene glycol

Abstract

The present application discloses a method for preparing high-molecular-weight polyethylene glycol, comprising the following steps: S1, adding raw materials PEG600 and a solid-phase catalyst into a high-pressure reaction vessel, closing the high-pressure reaction vessel, and replacing the air in the high-pressure reaction vessel with nitrogen; S2, heating and pressurizing the high-pressure reaction vessel, maintaining the temperature within the high-pressure reaction vessel between 40°C and 70°C and the pressure within the high-pressure reaction vessel between 0.54 MPa and 0.88 MPa, continuously introducing EO into the high-pressure reaction vessel at a feed ratio of EO to PEG600 of 300:1 or greater, and reacting for more than 30 minutes; S3, reducing the pressure of the high-pressure reaction vessel to normal pressure, filtering the solid-phase catalyst from the remaining liquid in the high-pressure reaction vessel, and cooling the vessel to normal temperature to obtain high-molecular-weight polyethylene glycol. The process steps of the present application are simple, can effectively solve the problem of difficult product separation and purification, and the reaction conditions are mild, with low process costs.

Description

Technical Field

[0001] The present application relates to the technical field of polymer material synthesis, and in particular to a method for preparing high molecular weight polyethylene glycol. Background Art

[0002] Polyethylene glycol (PEG) is a high-molecular-weight polymer with excellent water solubility and good compatibility with many organic components. PEG and its fatty acid esters are widely used in the cosmetics and pharmaceutical industries. PEG is prepared industrially using two main processes: one by reacting ethylene oxide (EO) with water, and the other by polymerization of ethylene glycol (EG). Common PEG products include PEG 200, PEG 400, PEG 600, and PEG 800, with average molecular weights ranging from 200 to 800.

[0003] High molecular weight PEG (PEG) has excellent water solubility, compatibility, lubricity, adhesion, and thermal stability. Therefore, it can be used as a lubricant, dispersant, adhesive, excipient, and the like, and is widely used in industries such as electronic component manufacturing and ceramics. Its good solubility, hygroscopicity, and thermal stability also make it a medium for organic synthesis, a moisturizer and viscosity modifier in the cosmetics industry, and a wetting agent for papermaking and pesticides. It also has a wide range of uses in industries such as cosmetics, pharmaceuticals, chemical fibers, rubber, plastics, papermaking, paints, and electroplating. Because its terminal hydroxyl group is resilient and can be further etherified and esterified, it is also widely used in the preparation of various surfactants. The preparation of high molecular weight PEG is relatively difficult. Due to its relatively high molecular weight, it is difficult to synthesize it using theoretical proportions and conventional catalysts during the synthesis process. High molecular weight PEG with a molecular weight exceeding 24,000 is particularly difficult to synthesize.

[0004] Currently, the main process for synthesizing high-molecular-weight PEG involves starting with low-molecular-weight PEG (such as PEG200 or PEG400) or EG monomers. These are then reacted with EO under high pressure using a KOH catalyst to increase the chain length and produce higher-molecular-weight PEG. This preparation process not only requires precise control of temperature and reaction pressure, but also requires complex purification and separation of the KOH catalyst, which is difficult to recover. It also produces alkaline wastewater, which pollutes the environment, and is costly. Furthermore, this process cannot produce PEG with a molecular weight exceeding 24,000. Currently, existing technologies disclose the use of specific organic bases as catalysts to produce PEG with a molecular weight exceeding 24,000. However, these processes also suffer from difficulties in separation and purification, difficulty in catalyst recovery, and the higher cost of organic base catalysts, resulting in higher overall process costs. Summary of the Invention

[0005] In order to solve at least one of the above technical problems, a synthesis process for high molecular weight PEG is developed with simple process steps, which can effectively solve the problem of difficult product separation and purification, and has mild reaction conditions and low process cost. The present application provides a method for preparing high molecular weight polyethylene glycol.

[0006] The present application provides a method for preparing high molecular weight polyethylene glycol, comprising the following steps:

[0007] S1, adding raw materials PEG600 and solid phase catalyst into a high-pressure reaction vessel, closing the high-pressure reaction vessel, and replacing the air in the high-pressure reaction vessel with N2;

[0008] S2. Raise the temperature and pressure of the high-pressure reaction vessel, maintain the temperature in the high-pressure reaction vessel at 40-70° C. and the pressure at 0.54 MPa-0.88 MPa, and continuously introduce EO into the high-pressure reaction vessel according to the amount of PEG600 added, maintaining the temperature and pressure, and reacting for more than 30 minutes, with a mass ratio of EO to PEG600 of 300:1 or more.

[0009] S3, releasing the pressure of the high-pressure reaction vessel to normal pressure, heating the high-pressure reaction vessel to above 68° C., filtering the remaining liquid in the high-pressure reaction vessel to remove the solid-phase catalyst, and cooling it to room temperature to obtain high molecular weight PEG;

[0010] In step S1, the solid phase catalyst is a composite catalyst of porous silica gel particles loaded with Ca(OH)2 and potassium-modified ZSM-5 molecular sieve.

[0011] By adopting the above technical solution, the present application uses PEG600 as the starting material and uses EO to react with it under catalytic conditions, thereby effectively increasing the chain length of PEG and preparing high molecular weight PEG; the present application uses PEG600 and EO to react under high pressure conditions and adopts a relatively low reaction temperature, the reaction conditions are relatively mild, and the reaction temperature and pressure are relatively easy to control; the present application uses a composite catalyst, using porous silica gel particles loaded with Ca(OH)2 and potassium-modified ZSM-5 molecular sieve as catalysts, which has an excellent catalytic effect. It can not only significantly reduce the reaction temperature to ensure that the reaction proceeds in a liquid state, but also effectively increase the contact between the reactants and the catalyst, effectively control the chain length of the reaction product, and can prepare high molecular weight PEG with a molecular weight exceeding 24,000 and a molecular weight distribution coefficient below 1.4; the present application uses EO as a raw material and a solid-phase catalyst. No water or other solvents are added during the entire synthesis process. The remaining EO and catalyst can be separated by simple exhaust and filtration. The entire process does not require any complex purification steps, and the prepared high molecular weight PEG has a high purity; the catalyst of the present application can be recycled and reused, and the overall process cost is low.

[0012] Optionally, in step S1, the Ca(OH)2 loaded porous silica gel particles have a Ca(OH)2 loading amount of more than 30% of the total mass of the particles; the added amount of the Ca(OH)2 loaded porous silica gel particles accounts for 15~20% of the total mass of the raw material PEG600.

[0013] Optionally, in step S1, the porous silica gel particles loaded with Ca(OH)2 are prepared by the following steps:

[0014] a. Prepare a Ca(OH)2 suspension with a concentration of more than 30%;

[0015] b. Place the porous silica gel particles into the Ca(OH)2 suspension and stir for more than 30 minutes;

[0016] c. Filter out the porous silica gel particles that adsorb Ca(OH)2 and heat to 105-120℃ for drying;

[0017] d. Repeat the above steps until the loading amount of Ca(OH)2 reaches the required loading amount to obtain porous silica gel particles loaded with Ca(OH)2.

[0018] Optionally, in step S1, the loading amount of potassium ions in the potassium-modified ZSM-5 molecular sieve accounts for 3-5% of the total mass of the ZSM-5 molecular sieve; and the added amount of the potassium-modified ZSM-5 molecular sieve accounts for 18-30% of the total mass of the raw material PEG600.

[0019] Optionally, in step S1, the silicon-aluminum ratio of the potassium-modified ZSM-5 molecular sieve is 28-32.

[0020] By adopting the above technical solution, the present application uses a potassium-modified ZSM-5 molecular sieve catalyst with an appropriate silicon-aluminum ratio, combined with Ca(OH)2, which can further increase the chain length of the PEG product during the catalytic reaction and obtain a PEG product with a larger molecular weight.

[0021] Optionally, in step S2, the temperature and pressure are increased to maintain the temperature in the high-pressure reaction vessel at 48-60° C. and the pressure at 0.69 MPa-0.84 MPa.

[0022] Optionally, in step S2, the temperature and pressure are maintained, and when the pressure is insufficient, N2 is charged to maintain the pressure.

[0023] By adopting the above technical solution, the present application accurately controls the reaction temperature and reaction pressure, which can effectively ensure that the PEG600 raw material and the introduced EO can remain in liquid form during the reaction; at the same time, it can also ensure that the generated high molecular weight PEG does not precipitate, effectively preventing the generated PEG product from clogging the catalyst support.

[0024] Optionally, in step S2, the reaction is carried out under stirring conditions.

[0025] Optionally, in step S3, the high-pressure reaction vessel is depressurized to normal pressure, specifically comprising the following steps: first, venting the gas and releasing the pressure; during the pressure release, the remaining liquid in the high-pressure reaction vessel is degassed with N2, and all released gases are collected; then, the temperature is lowered until EO condenses into a liquid state, and the remaining EO is collected for reuse.

[0026] Optionally, in step S3, the solid-phase catalyst is filtered out of the remaining liquid in the high-pressure reaction vessel, and the filtered solid-phase catalyst is collected, washed with ethanol, dried, and then recycled.

[0027] By adopting the above technical solution, the remaining EO in the process of this application can be completely recovered by simple gas collection and cooling liquefaction separation; and the catalyst of this application can also be recovered and reused by simple filtration and cleaning; not only is the recovery method simple, but it can also greatly reduce the overall cost of this application.

[0028] In summary, the present invention includes at least one of the following beneficial technical effects:

[0029] 1. This application uses PEG600 and EO to react under high pressure conditions and adopts a relatively low reaction temperature. During the entire reaction process, EO and PEG600 react in the liquid phase, which effectively improves the reaction efficiency and shortens the reaction time.

[0030] 2. This application uses a composite catalyst, with porous silica gel particles loaded with Ca(OH)2 and potassium-modified ZSM-5 molecular sieve as catalysts. The catalytic effect is very excellent. It can not only significantly reduce the reaction temperature and ensure that the reaction is carried out in a liquid state, but also effectively increase the contact between the reactants and the catalyst, effectively control the chain length of the reaction product, and can prepare high molecular weight PEG with a molecular weight exceeding 24,000 and a molecular weight distribution coefficient less than 1.4.

[0031] 3. This application uses EO as a raw material and an all-solid-state catalyst. No water or other solvents are added during the entire synthesis process. The remaining EO and catalyst can be separated by simple exhaust and filtration. The entire process does not require any complex purification steps and the process difficulty is relatively low.

[0032] 4. The solid-phase catalyst of the present application can be recovered and reused by simple filtration and washing, and the raw materials used are relatively low-cost low-molecular-weight PEG and EO, so the overall cost of the entire process is low. DETAILED DESCRIPTION

[0033] The present application is further described in detail below with reference to the embodiments.

[0034] Glossary: ​​PEG-polyethylene glycol, EG-ethylene glycol, ethylene oxide-EO, PEG200-polyethylene glycol product with an average molecular weight of about 200, PEG400-polyethylene glycol product with an average molecular weight of about 400, PEG600-polyethylene glycol product with an average molecular weight of about 600, PEG800-polyethylene glycol product with an average molecular weight of about 800.

[0035] The present invention provides a method for preparing high molecular weight polyethylene glycol, comprising the following steps:

[0036] S1, adding raw material PEG600 and solid phase catalyst into a high-pressure reaction vessel, sealing the high-pressure reaction vessel, and replacing the air in the high-pressure reaction vessel with N2;

[0037] S2. Raise the temperature and pressure of the high-pressure reaction vessel, maintain the temperature in the high-pressure reaction vessel at 40-70° C. and the pressure at 0.54 MPa-0.88 MPa, and continuously introduce EO into the high-pressure reaction vessel according to the amount of PEG600 added, maintaining the temperature and pressure, and reacting for more than 30 minutes, with a mass ratio of EO to PEG600 of 300:1 or more.

[0038] S3. Reduce the pressure of the high-pressure reaction vessel to normal pressure, raise the temperature of the high-pressure reaction vessel to above 68° C., filter the remaining liquid in the high-pressure reaction vessel to remove the solid phase catalyst, and reduce the temperature to room temperature to obtain high molecular weight PEG.

[0039] The solid phase catalyst of the present application adopts a composite catalyst of porous silica gel particles loaded with Ca(OH)2 and potassium-modified ZSM-5 molecular sieve.

[0040] Prior to this application, there were two main methods for preparing high-molecular-weight polyethylene glycol (PEG) that were widely industrialized in the field. One method used low-molecular-weight PEG400 as a starting material, EO as another raw material, and an alkali metal, its salts, or alkali metal hydroxide as a catalyst. Using an autoclave as the reaction vessel, the reaction was carried out at high temperature and high pressure to increase the chain length of the PEG, thereby producing high-molecular-weight PEG. The other method used EG monomer as a starting material, and an alkali metal, its salts, or alkali metal hydroxide as a catalyst. By precisely controlling the ratio of raw materials and catalyst, as well as the reaction conditions, higher-molecular-weight PEG was produced. The first process could only produce PEG with a molecular weight below 18,000, while the second process could only produce PEG with a molecular weight below 8,000.

[0041] A Chinese invention patent, publication number CN114672011A, entitled "A Method for Bulk Polymerization of High Molecular Weight Polyethylene Glycol," discloses a process for producing PEG with a molecular weight exceeding 20,000. This process uses a specific organic base as a catalyst and adds a plasticizer to produce high molecular weight PEG with an average molecular weight of 20,000 to 50,000. However, the inclusion of the plasticizer results in a low product purity, and the catalyst used is difficult to recover, resulting in high costs and making it unsuitable for industrial application.

[0042] The inventor of the present application has designed the preparation technology of the present application by conducting in-depth research on the synthesis technique of high molecular weight PEG, and has effectively solved the problems existing in the prior art. The inventor of the present application, in order to effectively increase the molecular weight of PEG, adopts composite catalyst, with potassium ion and Ca (OH) 2 as catalyst, and respectively using mesoporous molecular sieve and porous silica gel particles as catalyst carriers, by the effective design of catalyst, has achieved the preparation of high molecular weight PEG. Meanwhile, the application takes into account the problems existing in the prior art, and when catalyst design, just adopts solid phase design, not only effectively increases the contact of catalyst and reactant, and is easy to separation and recovery, and catalyst is reusable, effectively reduces cost. In addition, the application, in order to effectively increase the chain length of PEG, has also carried out accurate design to process parameters, ensures that building-up reactions is liquid phase reaction, not only effectively improves reaction efficiency, also effectively improves the molecular weight of the PEG obtained.

[0043] The following are examples of the present application.

[0044] The raw materials and equipment information of each component in the examples of this application are as follows:

[0045] PEG600: purity greater than 99%, Nantong Runfeng Petrochemical Co., Ltd.

[0046] EO: purity greater than 99%, TCI (Shanghai);

[0047] Porous silica particles: particle size 2~3mm, specific surface area 300m 2 / g, Shanghai Aladdin;

[0048] Ca(OH)2: purity greater than 99%, Nantong Runfeng Petrochemical Co., Ltd.

[0049] Potassium-modified ZSM-5 molecular sieve: Beijing Bailingwei Technology Co., Ltd.;

[0050] N2: Wuxi Kaiteng Energy Technology Co., Ltd.;

[0051] Ethanol: 95%, Changzhou Runcheng Chemical;

[0052] Water: deionized water, homemade;

[0053] High-pressure reaction vessel: TGYF-B magnetic stirring high-pressure reactor, Zhengzhou Keda;

[0054] Thermal drying equipment: DHG-9075AE constant temperature forced air circulation oven, Shanghai Jinlan.

[0055] The porous silica gel particles loaded with Ca(OH)2 used in the examples of the present application were prepared by the following steps:

[0056] a. Prepare a Ca(OH)2 suspension with a concentration of more than 30%;

[0057] b. Place the porous silica gel particles into the Ca(OH)2 suspension and stir for more than 30 minutes;

[0058] c. Filter out the porous silica gel particles that adsorb Ca(OH)2 and heat to 105-120℃ for drying;

[0059] d. Repeat the above steps until the Ca(OH)2 loading reaches more than 30%, thereby obtaining porous silica gel particles loaded with Ca(OH)2.

[0060] The porous silica gel particles loaded with Ca(OH)2 used in the embodiments of the present application have a Ca(OH)2 loading amount of 30~34%.

[0061] The potassium-modified ZSM-5 molecular sieve used in the examples of the present application is a potassium-modified ZSM-5 molecular sieve customized by the manufacturer, with a potassium ion loading of 5%, and a total of six types of products with silicon-aluminum ratios of 20, 24, 28, 30, 32, and 36.

[0062] Example 1

[0063] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 20.

[0064] The preparation method of the high molecular weight PEG of this embodiment comprises the following steps:

[0065] S1. 500 g of PEG600, 60 g of porous silica gel particles loaded with Ca(OH)2, and 60 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0066] S2. Heat the TGYF-B magnetic stirring high-pressure reactor and introduce N2 to increase the pressure, maintaining the temperature in the reactor at 40-45°C and the pressure at 0.54 MPa-0.60 MPa; then, turn on the magnetic stirring and continuously and slowly introduce 150 kg of EO into the reactor. When introducing EO, control the temperature and pressure in the reactor to maintain at 40-45°C and 0.54 MPa-0.60 MPa; maintain the temperature and pressure in the reactor, add N2 to maintain the pressure when the pressure drops, and react for 60 min.

[0067] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 68°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0068] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0069] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0070] The prepared high molecular weight PEG was tested to have an average molecular weight of about 24,800, a molecular weight distribution coefficient of 1.37, and a purity of more than 99%.

[0071] Example 2

[0072] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 24.

[0073] S1. 500 g of PEG600, 75 g of porous silica gel particles loaded with Ca(OH)2, and 90 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0074] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 45-50°C and the pressure at 0.60 MPa-0.66 MPa. Then, magnetic stirring was turned on and 170 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 45-50°C and 0.60 MPa-0.66 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped, and the reaction was carried out for 30 min.

[0075] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 70°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0076] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0077] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0078] The obtained high molecular weight PEG was tested to have an average molecular weight of about 24,600, a molecular weight distribution coefficient of 1.34, and a purity of more than 99%.

[0079] Example 3

[0080] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 28.

[0081] S1. 500 g of PEG600, 80 g of porous silica gel particles loaded with Ca(OH)2, and 100 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0082] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 48-52°C and the pressure at 0.64 MPa-0.70 MPa. Then, magnetic stirring was turned on and 190 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 48-52°C and 0.64 MPa-0.70 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped, and the reaction was carried out for 35 minutes.

[0083] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 72°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0084] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0085] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0086] The obtained high molecular weight PEG was tested to have an average molecular weight of about 27,200, a molecular weight distribution coefficient of 1.32, and a purity of more than 99%.

[0087] Example 4

[0088] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 30.

[0089] S1. 500 g of PEG600, 90 g of porous silica gel particles loaded with Ca(OH)2, and 120 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0090] S2. Heat the TGYF-B magnetic stirring high-pressure reactor and introduce N2 to increase the pressure, maintaining the temperature in the reactor at 52-58°C and the pressure at 0.70 MPa-0.76 MPa; then, turn on the magnetic stirring and continuously and slowly introduce 200 kg of EO into the reactor. When introducing EO, control the temperature and pressure in the reactor to maintain at 52-58°C and 0.70 MPa-0.76 MPa; maintain the temperature and pressure in the reactor, add N2 to maintain the pressure when the pressure drops, and react for 45 minutes.

[0091] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 68°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0092] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0093] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0094] The obtained high molecular weight PEG was tested to have an average molecular weight of about 29,300, a molecular weight distribution coefficient of 1.27, and a purity of more than 99%.

[0095] Example 5

[0096] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 32.

[0097] S1. 500 g of PEG600, 100 g of porous silica gel particles loaded with Ca(OH)2, and 150 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and N2 was introduced into the autoclave to displace the air.

[0098] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 66-70°C and the pressure at 0.76 MPa-0.82 MPa. Then, magnetic stirring was turned on and 220 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 66-70°C and 0.76 MPa-0.82 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped, and the reaction was carried out for 40 min.

[0099] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 68°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0100] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0101] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0102] The obtained high molecular weight PEG was tested to have an average molecular weight of about 30,400, a molecular weight distribution coefficient of 1.28, and a purity of more than 99%.

[0103] Example 6

[0104] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 36.

[0105] S1. 500 g of PEG600, 95 g of porous silica gel particles loaded with Ca(OH)2, and 130 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0106] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 60-66°C and the pressure at 0.82 MPa-0.88 MPa. Then, magnetic stirring was turned on and 240 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 60-66°C and 0.82 MPa-0.88 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped. The reaction was continued for 55 min.

[0107] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 75°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0108] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0109] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0110] The obtained high molecular weight PEG was tested to have an average molecular weight of about 33,200, a molecular weight distribution coefficient of 1.28, and a purity of more than 99%.

[0111] Example 7

[0112] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 30.

[0113] S1. 500 g of PEG600, 90 g of porous silica gel particles loaded with Ca(OH)2, and 130 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0114] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 44-50°C and the pressure at 0.69 MPa-0.74 MPa. Then, magnetic stirring was turned on and 193 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 44-50°C and 0.69 MPa-0.74 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped, and the reaction was carried out for 50 min.

[0115] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 72°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0116] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0117] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0118] The obtained high molecular weight PEG was tested to have an average molecular weight of about 32,300, a molecular weight distribution coefficient of 1.26, and a purity of more than 99%.

[0119] Example 8

[0120] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 32.

[0121] S1. 500 g of PEG600, 95 g of porous silica gel particles loaded with Ca(OH)2, and 135 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0122] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 46-52°C and the pressure at 0.72 MPa-0.78 MPa. Then, magnetic stirring was turned on and 200 kg of EO was continuously and slowly introduced into the reactor. When EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 46-52°C and 0.72 MPa-0.78 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped. The reaction was continued for 54 min.

[0123] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 72°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0124] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0125] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0126] The obtained high molecular weight PEG was tested to have an average molecular weight of about 35,200, a molecular weight distribution coefficient of 1.23, and a purity of more than 99%.

[0127] Example 9

[0128] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 28.

[0129] S1. 500 g of PEG600, 100 g of porous silica gel particles loaded with Ca(OH)2, and 140 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and N2 was introduced into the autoclave to displace the air.

[0130] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 58-64°C and the pressure at 0.84 MPa-0.88 MPa. Then, magnetic stirring was turned on and 210 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 58-64°C and 0.84 MPa-0.88 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped, and the reaction was carried out for 60 min.

[0131] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 75°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0132] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0133] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0134] The obtained high molecular weight PEG was tested to have an average molecular weight of about 35,400, a molecular weight distribution coefficient of 1.24, and a purity of more than 99%.

[0135] Example 10

[0136] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 32.

[0137] S1. 500 g of PEG600, 95 g of porous silica gel particles loaded with Ca(OH)2, and 140 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0138] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 52-58°C and the pressure at 0.78 MPa-0.84 MPa. Then, magnetic stirring was turned on and 225 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 52-58°C and 0.78 MPa-0.84 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped. The reaction was continued for 58 min.

[0139] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 75°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0140] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0141] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0142] The obtained high molecular weight PEG was tested to have an average molecular weight of about 36,800, a molecular weight distribution coefficient of 1.22, and a purity of more than 99%.

[0143] Example 11

[0144] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 32.

[0145] S1. 500 g of PEG600, 95 g of porous silica gel particles loaded with Ca(OH)2, and 140 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0146] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 52-58°C and the pressure at 0.78 MPa-0.84 MPa. Then, magnetic stirring was turned on and 245 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 52-58°C and 0.78 MPa-0.84 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped. The reaction was continued for 58 min.

[0147] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 75°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0148] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0149] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0150] The prepared high molecular weight PEG was tested to have an average molecular weight of about 37,600, a molecular weight distribution coefficient of 1.19, and a purity of more than 99%.

[0151] Example 12

[0152] The potassium-modified ZSM-5 molecular sieve of this embodiment adopts a ZSM-5 molecular sieve with a potassium loading of 5% and a silicon-aluminum ratio of 32.

[0153] S1. 500 g of PEG600, 95 g of porous silica gel particles loaded with Ca(OH)2, and 140 g of potassium-modified ZSM-5 molecular sieve were placed in a TGYF-B magnetic stirring autoclave. The autoclave cover was closed, and nitrogen was introduced into the autoclave to displace the air.

[0154] S2. The temperature of the TGYF-B magnetic stirring high-pressure reactor was increased and nitrogen was introduced to increase the pressure, maintaining the temperature in the reactor at 52-58°C and the pressure at 0.78 MPa-0.84 MPa. Then, magnetic stirring was turned on and 256 kg of EO was continuously and slowly introduced into the reactor. When the EO was introduced, the temperature and pressure in the reactor were controlled to be maintained at 52-58°C and 0.78 MPa-0.84 MPa. The temperature and pressure in the reactor were maintained, and nitrogen was added to maintain the pressure when the pressure dropped. The reaction was continued for 58 min.

[0155] S3. Turn off the magnetic stirring, vent the TGYF-B magnetic stirring high-pressure reactor, release the gas and pressure to normal pressure, and collect all the released gases; then, heat the reactor to 75°C, and collect all the gases released in the reactor during and after the heating process until no gas overflows; finally, discharge the remaining liquid in the reactor, filter out the solid phase, and cool the liquid from which the solid phase has been filtered out to room temperature to obtain high molecular weight PEG.

[0156] S4. Cool all the gases collected in step S3 to below 5°C until no condensate is produced, separate and recover the condensate to obtain the remaining EO, and the remaining uncondensed gas is N2, which is also recovered and reused.

[0157] S5. Recover and reuse the solid phase catalyst filtered out in step S3.

[0158] The prepared high molecular weight PEG was tested to have an average molecular weight of about 38,000, a molecular weight distribution coefficient of 1.21, and a purity of more than 99%.

[0159] In Examples 1 to 12 of the present application, in step S5, the recovery of the solid phase catalyst is specifically carried out by the following steps:

[0160] 1) Soak the filtered solid phase catalyst in 95% ethanol for 5-10 minutes;

[0161] 2) Rinse the soaked and cleaned solid phase catalyst with 95% ethanol 3 to 5 times;

[0162] 3) Place the washed solid-phase catalyst into a tray, place it in an oven, and bake it at 100-105°C for 5-8 minutes, then cool it to room temperature.

[0163] The recovered solid phase catalyst is stored in a sealed container for reuse.

[0164] The following are comparative examples of this application.

[0165] Comparative Example 1

[0166] The process of this comparative example is basically the same as that of Example 5, except for the feed ratio.

[0167] In this comparative example, 500 g of PEG600, 110 g of porous silica gel particles loaded with Ca(OH)2, and 160 g of potassium-modified ZSM-5 molecular sieve were added.

[0168] The high molecular weight PEG prepared in this comparative example was tested to have an average molecular weight of about 30,500, a molecular weight distribution coefficient of 1.29, and a purity of more than 99%.

[0169] Comparative Example 2

[0170] The process of this comparative example is basically the same as that of Example 12, except for the amount of EO added.

[0171] The total amount of EO introduced in this comparative example was 260 kg.

[0172] The high molecular weight PEG prepared in this comparative example was tested to have an average molecular weight of about 38,000, a molecular weight distribution coefficient of 1.22, and a purity of more than 99%.

[0173] Comparative Example 3

[0174] The process of this comparative example is basically the same as that of Example 12, except for the solid phase catalyst.

[0175] The solid phase catalyst of this comparative example adopts porous silica gel particles loaded with Ca(OH)2, and the catalyst addition amount is 235g.

[0176] The high molecular weight PEG prepared in this comparative example was tested, and the average molecular weight was about 13,000, the molecular weight distribution coefficient was 1.47, and the purity was above 99%.

[0177] Comparative Example 4

[0178] The process of this comparative example is basically the same as that of Example 12, except for the solid phase catalyst.

[0179] The solid phase catalyst of this comparative example adopts potassium-modified ZSM-5 molecular sieve, and the catalyst addition amount is 235g.

[0180] The high molecular weight PEG prepared in this comparative example was tested to have an average molecular weight of about 15,000, a molecular weight distribution coefficient of 1.42, and a purity of more than 99%.

[0181] Comparative Example 5

[0182] This comparative example adopts Example 1 of the Chinese invention patent with publication number CN114672011A and invention name: A method for bulk polymerization of high molecular weight polyethylene glycol.

[0183] The high molecular weight PEG prepared in this comparative example was tested, and the average molecular weight was about 31,000, the molecular weight distribution coefficient was 1.03, and the purity was 92%.

[0184] It can be seen from the various performance indicators of the products prepared by Examples 1 to 12 of the present application and Comparative Examples 1 to 5 that the purity of the high molecular weight PEG prepared by Examples 1 to 12, and Comparative Examples 1 and 2 using the solid-phase catalyst of the present application is extremely high, and can reach more than 99%. And the purity of the high molecular weight PEG prepared by Comparative Examples 3 and 4 using one of the two solid-phase catalysts of the present application is also extremely high, and can also reach more than 99%. Using the organic base catalyst of the prior art and adding the comparative example 5 of the plasticizer, the purity of the high molecular weight PEG prepared is relatively low, and can only reach 92%. It can be seen from this that the present application adopts a solid-phase catalyst and does not add any other auxiliary agent preparation process, and the purity of the high molecular weight PEG prepared is higher, much higher than the product of the prior art.

[0185] The various performance indicators of the products prepared in Examples 1 to 12 of the present application and Comparative Examples 1 to 4 also show that the average molecular weight of the high molecular weight PEG prepared in Examples 1 to 12 of the present application, as well as Comparative Examples 1 and 2, can reach over 24,000. However, the average molecular weight of the high molecular weight PEG prepared in Comparative Examples 3 and 4 can only reach 15,000, which is much lower than that in Examples 1 to 12 of the present application, as well as Comparative Examples 1 and 2. Thus, it can be seen that the composite catalyst used in the present application can effectively extend the chain length of PEG and prepare a high molecular weight PEG product with an average molecular weight exceeding 24,000.

[0186] Furthermore, analysis of Examples 1-6 of the present application shows that the average molecular weight of the high molecular weight PEG prepared herein increases with increasing EO feed rates. Analysis of Examples 10-12 of the present application, as well as Comparative Example 2, shows that, with other conditions remaining unchanged, the average molecular weight of the high molecular weight PEG prepared herein continues to increase with increasing EO feed rates. However, when the EO to PEG600 feed ratio exceeds 512:1, the average molecular weight of the high molecular weight PEG prepared herein increases only slightly.

[0187] Analysis of Examples 1 to 6 of the present application also shows that as the amount of catalyst added increases, the average molecular weight of the high molecular weight PEG prepared in the present application increases, and the molecular weight distribution coefficient gradually decreases. Analysis of Examples 1 to 5 of the present application and Comparative Example 1 shows that when the amount of Ca(OH)2-loaded porous silica gel particles and potassium-modified ZSM-5 molecular sieve added exceeds a certain amount, the average molecular weight of the high molecular weight PEG prepared in the present application increases only slightly.

[0188] Finally, an analysis of Examples 1-12 of this application demonstrates that the control of reaction temperature and pressure in the present process significantly influences the average molecular weight of the products produced. For example, the average molecular weight of the high-molecular-weight PEG produced in Example 6 is higher than that of the product produced in Example 5; and the average molecular weight of the high-molecular-weight PEG produced in Examples 7-12 is also significantly higher than that of the products produced in Examples 5 and 6. This demonstrates that the use of higher reaction pressures and lower reaction temperatures (e.g., 52-58°C and 0.78 MPa-0.84 MPa) in this application is more conducive to increasing PEG chain length and producing high-molecular-weight PEG products with higher average molecular weights. The inventors speculate that the use of low-temperature, high-pressure process parameters results in the reaction of the EO raw material in a substantially liquid state, resulting in a liquid-phase or liquid-solid two-phase reaction. This facilitates the reaction and further increases the chain length of the reaction product.

[0189] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing high molecular weight polyethylene glycol, characterized in that: The steps include: S1, adding raw materials PEG600 and solid phase catalyst into a high-pressure reaction vessel, closing the high-pressure reaction vessel, and replacing the air in the high-pressure reaction vessel with N2; S2. Raise the temperature and pressure of the high-pressure reaction vessel, maintain the temperature in the high-pressure reaction vessel at 40-70° C. and the pressure at 0.54 MPa-0.88 MPa, and continuously introduce EO into the high-pressure reaction vessel according to the amount of PEG600 added, maintaining the temperature and pressure, and reacting for more than 30 minutes, with a mass ratio of EO to PEG600 of 300:1 or more. S3, releasing the pressure of the high-pressure reaction vessel to normal pressure, heating the high-pressure reaction vessel to above 68° C., filtering the remaining liquid in the high-pressure reaction vessel to remove the solid-phase catalyst, and cooling it to room temperature to obtain high molecular weight PEG; In step S1, the solid phase catalyst is a composite catalyst of porous silica gel particles loaded with Ca(OH)2 and potassium-modified ZSM-5 molecular sieve.

2. The method for preparing a high molecular weight polyethylene glycol according to claim 1, wherein: In step S1, the porous silica gel particles loaded with Ca(OH)2 have a Ca(OH)2 loading amount of more than 30% of the total mass of the particles; the added amount of the porous silica gel particles loaded with Ca(OH)2 accounts for 15-20% of the total mass of the raw material PEG600.

3. The method for preparing a high molecular weight polyethylene glycol according to claim 1 or 2, characterized in that: In step S1, the porous silica gel particles loaded with Ca(OH)2 are prepared by the following steps: a. Prepare a Ca(OH)2 suspension with a concentration of more than 30%; b. Place the porous silica gel particles into the Ca(OH)2 suspension and stir for more than 30 minutes; c. Filter out the porous silica gel particles that adsorb Ca(OH)2 and heat to 105-120℃ for drying; d. Repeat the above steps until the loading amount of Ca(OH)2 reaches the required loading amount to obtain porous silica gel particles loaded with Ca(OH)2.

4. The method for preparing a high molecular weight polyethylene glycol according to claim 1, wherein: In the step S1, the potassium ion loading amount of the potassium-modified ZSM-5 molecular sieve accounts for 3-5% of the total mass of the ZSM-5 molecular sieve; and the added amount of the potassium-modified ZSM-5 molecular sieve accounts for 18-30% of the total mass of the raw material PEG600.

5. The method for preparing high molecular weight polyethylene glycol according to claim 4, wherein: In the step S1, the silicon-aluminum ratio of the potassium-modified ZSM-5 molecular sieve is 28-32.

6. The method for preparing high molecular weight polyethylene glycol according to claim 1, wherein: In step S2, the temperature and pressure are increased to maintain the temperature in the high-pressure reaction vessel at 48-60° C. and the pressure at 0.69 MPa-0.84 MPa.

7. The method for preparing high molecular weight polyethylene glycol according to claim 1, wherein: In the step S2, the temperature and pressure are maintained, and when the pressure is insufficient, N2 is charged to maintain the pressure.

8. The method for preparing high molecular weight polyethylene glycol according to claim 1, wherein: In the step S2, the reaction is carried out under stirring conditions.

9. The method for preparing high molecular weight polyethylene glycol according to claim 1, wherein: In step S3, the high-pressure reaction vessel is depressurized to a normal pressure state, specifically comprising the following steps: first, venting the gas to release the pressure, during which the remaining liquid in the high-pressure reaction vessel is degassed by filling it with N2, and all released gas is collected; then, the temperature is lowered until the EO condenses into a liquid state, and the remaining EO is collected for reuse.

10. The method for preparing high molecular weight polyethylene glycol according to claim 1, characterized in that: In the step S3, the solid phase catalyst is filtered out of the remaining liquid in the high-pressure reaction vessel, and the filtered solid phase catalyst is collected, washed with ethanol, dried, and then recycled.