A catalyst for preparing medium and low molecular weight polyethylene oxide and a method for preparing the same and use thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI LIANSHENG CHEM CO LTD
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-02
Smart Images
Figure CN121914175B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation technology, specifically to a method for preparing low to medium molecular weight polyethylene oxide catalyst and its application. Background Technology
[0002] Polyethylene oxide (PEO) is a water-soluble polyether material with excellent hydrophilicity, biocompatibility, lubricity, and film-forming properties. It is widely used in pharmaceutical sustained-release systems, daily chemical products, lubricants, coating additives, and functional polymer materials. Based on molecular weight, PEO can be classified into low-molecular-weight, medium-molecular-weight, and high-molecular-weight products. Among these, low- and medium-molecular-weight PEO, due to its moderate viscosity, rapid dissolution, and good processing performance, has significant application value in surfactant synthesis, lubricants, dispersants, and fine chemicals. PEO is mainly synthesized from ethylene oxide through ring-opening polymerization; in this process, the catalyst plays a crucial role in the reaction. However, existing catalytic systems still have significant limitations: on the one hand, low catalyst efficiency leads to long reaction times and insufficient conversion rates; on the other hand, molecular weight control is difficult, easily generating widely distributed and oligomer byproducts.
[0003] Chinese invention patent CN107674195A discloses a catalyst for the synthesis of polyethylene oxide polymers and a method thereof, comprising components 1, 2, and 3, wherein component 1 is a crown ether, component 2 is a quaternary phosphine salt, and component 3 is an alkali metal and / or an alkali metal compound. The catalyst disclosed in this patent can reduce the concentration of alkali metal ions in the product, improving product quality and making it suitable for high-standard industrial applications. However, the control of the molecular weight and molecular weight distribution of the polyethylene oxide synthesized using this catalyst needs further improvement. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing medium- and low-molecular-weight polyethylene oxide catalysts and their applications.
[0005] A method for preparing a medium-to-low molecular weight polyethylene oxide catalyst includes the following steps:
[0006] Zinc chloride solution was added dropwise to potassium cobalt cyanide solution, a complexing agent was added to react, and the catalyst was obtained after post-treatment.
[0007] The structural formula of the complexing agent is as follows:
[0008]
[0009] The complexing agent is prepared by the following method:
[0010] S1: The reaction of heptaethylene glycol with epichlorohydrin yields intermediate 1, and the reaction equation is shown below:
[0011]
[0012] S2: Intermediate 1 reacts with iminodiacetic acid to give a complexing agent, and the reaction equation is shown below:
[0013]
[0014] In step S1, the molar ratio of polyethylene glycol to epichlorohydrin is 1:(2.3-2.4).
[0015] In step S2, the molar ratio of intermediate 1 to iminodiacetic acid is 1:(2.08-2.1).
[0016] The solvent used in step S1 is toluene, the reaction temperature is 30-40℃, and the reaction time is 5-7h.
[0017] The solvent used in step S2 is DMF, the reaction temperature is 60-70℃, and the reaction time is 4-6h.
[0018] The molar ratio of potassium cobalt cyanide, zinc chloride and complexing agent is 1:(5-8):(1-1.5).
[0019] The reaction temperature is 30-40℃ and the reaction time is 6-8h.
[0020] A catalyst for preparing medium- and low-molecular-weight polyethylene oxide is prepared by the above method.
[0021] Application of a catalyst for preparing medium and low molecular weight polyethylene oxide.
[0022] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:
[0023] The catalyst prepared by this invention has high catalytic activity, and the synthesized polyethylene oxide has a high yield and a narrow molecular weight distribution. Furthermore, it is possible to synthesize polyethylene oxide with different molecular weights by adjusting the amount of catalyst used. Attached Figure Description
[0024] Figure 1 The image shows the 1H NMR spectrum of the complexing agent prepared in Example 1.
[0025] Figure 2 The high-resolution mass spectrum of the complexing agent prepared in Example 1 is shown.
[0026] Figure 3 This is a graph showing the relationship between different catalyst dosages and the number-average molecular weight and molecular weight distribution of polyethylene oxide. Detailed Implementation
[0027] Example 1 Preparation of Complexing Agent
[0028] S1: Add 250 ml toluene, 0.1 mol polyethylene glycol, 2.5 g tetrabutylammonium bromide, and 0.22 mol sodium hydroxide to a reaction flask, stir and mix well, then add 0.23 mol epichlorohydrin dropwise over 30 min. Heat to 50 °C and react for 7 h. Cool to room temperature, filter, and rotary evaporate the filtrate at 75 °C to constant weight. Purify by column chromatography (V... 石油醚 / V 乙酸乙酯 (5:1 to 1:1 gradient elution), rotary evaporated at 60℃ to constant weight, to obtain intermediate 1; its 1H NMR data are as follows: 1 H NMR (400 MHz, CDCl3) δ 3.81 – 3.74(m, 2H), 3.73 – 3.68 (m, 6H), 3.64 – 3.58(m, 24H), 3.56 – 3.51 (s, 2H), 3.23– 3.16 (m, 4H); HRMS (m / z):439.2469[M+H] + ;
[0029] S2: Add 150 ml DMF, 0.208 mol iminodiacetic acid, and 0.4 mol triethylamine to a reaction flask, stir and mix well, heat to 60℃, and add 200 ml of DMF solution containing 0.1 mol intermediate 1 dropwise over 1 hour. After reacting for 6 hours, cool to room temperature, slowly pour the reaction solution into 500 ml of diethyl ether, stir to precipitate, filter, and wash the filter cake with a mixed solution of diethyl ether and anhydrous ethanol (volume ratio of diethyl ether to anhydrous ethanol is 1:1) (2 × 50 ml). Dry under vacuum at 60℃ for 12 hours to obtain the complexing agent; its 1H NMR spectrum is as follows. Figure 1 As shown, the proton NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 12.32 (s, 4H), 4.41 (d, J = 6.8 Hz, 2H), 4.00 – 3.88 (m, 2H), 3.70 – 3.65 (m, 4H), 3.61 – 3.51 (m, 32H), 3.50 – 3.37 (m, 4H), 2.87 – 2.75 (m, 4H); its high-resolution mass spectrum is as follows: Figure 2 As shown, HRMS (m / z): 705.3221 [M+H] + .
[0030] Example 2 Preparation of Complexing Agent
[0031] S1: Add 250 ml toluene, 0.1 mol polyethylene glycol, 2.5 g tetrabutylammonium bromide, and 0.22 mol sodium hydroxide to a reaction flask, stir and mix well, then add 0.235 mol epichlorohydrin dropwise over 30 min. Heat to 55 °C and react for 6 h. Cool to room temperature, filter, and rotary evaporate the filtrate at 75 °C to constant weight. Purify by column chromatography (V... 石油醚 / V 乙酸乙酯 Elution was performed using a gradient from 5:1 to 1:1, and the mixture was rotary evaporated at 60°C to constant weight to obtain intermediate 1.
[0032] S2: Add 150 ml DMF, 0.209 mol iminodiacetic acid, and 0.4 mol triethylamine to a reaction flask, stir and mix well, heat to 65°C, add 200 ml of DMF solution containing 0.1 mol intermediate 1 dropwise, the addition is completed in 1 h, react for 5 h, cool to room temperature, slowly pour the reaction solution into 500 ml of diethyl ether, stir to precipitate, filter, wash the filter cake with a mixed solution of diethyl ether and anhydrous ethanol (volume ratio of diethyl ether to anhydrous ethanol is 1:1) (2 × 50 ml), dry under vacuum at 60°C for 12 h to obtain the complexing agent.
[0033] Example 3 Preparation of Complexing Agent
[0034] S1: Add 250 ml toluene, 0.1 mol polyethylene glycol, 2.5 g tetrabutylammonium bromide, and 0.22 mol sodium hydroxide to a reaction flask, stir and mix well, then add 0.24 mol epichlorohydrin dropwise over 30 min. Heat to 60 °C and react for 5 h. Cool to room temperature, filter, and rotary evaporate the filtrate at 75 °C to constant weight. Purify by column chromatography (V... 石油醚 / V 乙酸乙酯 Elution was performed using a gradient from 5:1 to 1:1, and the mixture was rotary evaporated at 60°C to constant weight to obtain intermediate 1.
[0035] S2: Add 150 ml DMF, 0.21 mol iminodiacetic acid, and 0.4 mol triethylamine to a reaction flask, stir and mix well, heat to 70°C, add 200 ml of DMF solution containing 0.1 mol intermediate 1 dropwise, the addition is completed in 1 h, react for 4 h, cool to room temperature, slowly pour the reaction solution into 500 ml of diethyl ether, stir to precipitate, filter, wash the filter cake with a mixed solution of diethyl ether and anhydrous ethanol (volume ratio of diethyl ether to anhydrous ethanol is 1:1) (2 × 50 ml), dry under vacuum at 60°C for 12 h to obtain the complexing agent.
[0036] Example 4
[0037] (1) Preparation of catalyst
[0038] Under stirring conditions, 50 ml of 1 M zinc chloride solution was slowly added dropwise to 100 ml of 0.1 M potassium cobalt cyanide solution. After 30 min, 0.01 mol of complexing agent (prepared in Example 1) was added, the temperature was raised to 30 °C, and the reaction was carried out for 8 h. After cooling to room temperature, the mixture was filtered, and the filter cake was washed with deionized water (3 × 50 ml). The mixture was then vacuum dried at 60 °C for 18 h to obtain the prepared low molecular weight polyethylene oxide catalyst.
[0039] (2) Preparation of polyethylene oxide
[0040] 10g of ethylene glycol and 0.01g of catalyst were added to a high-pressure reactor. The reactor was evacuated and heated to 120°C. Ethylene oxide was added until the reactor pressure reached 0.1MPa. The reactor was sealed and stirred at 120°C. When the reactor pressure dropped to 0.05MPa, ethylene oxide was continuously introduced. The pressure was maintained at 0.2MPa during the feeding process. When the feed was turned off and the pressure inside the reactor no longer changed significantly within 10 minutes, the addition of ethylene oxide was stopped. Stirring was continued for 4 hours. The mixture was then cooled to room temperature to obtain polyethylene oxide.
[0041] Example 5
[0042] (1) Preparation of catalyst
[0043] Under stirring conditions, 60 ml of 1 M zinc chloride solution was slowly added dropwise to 100 ml of 0.1 M potassium cobalt cyanide solution. After 30 min, 0.012 mol of complexing agent (prepared in Example 2) was added, the temperature was raised to 35 °C, and the reaction was carried out for 7 h. After cooling to room temperature, the mixture was filtered, and the filter cake was washed with deionized water (3 × 50 ml). The mixture was then vacuum dried at 60 °C for 18 h to obtain the prepared low molecular weight polyethylene oxide catalyst.
[0044] (2) Preparation of polyethylene oxide
[0045] 10g of ethylene glycol and 0.01g of catalyst were added to a high-pressure reactor. The reactor was evacuated and heated to 120°C. Ethylene oxide was added until the reactor pressure reached 0.1MPa. The reactor was sealed and stirred at 120°C. When the reactor pressure dropped to 0.05MPa, ethylene oxide was continuously introduced. The pressure was maintained at 0.2MPa during the feeding process. When the feed was turned off and the pressure inside the reactor no longer changed significantly within 10 minutes, the addition of ethylene oxide was stopped. Stirring was continued for 4 hours. The mixture was then cooled to room temperature to obtain polyethylene oxide.
[0046] Example 6
[0047] (1) Preparation of catalyst
[0048] Under stirring conditions, 80 ml of 1 M zinc chloride solution was slowly added dropwise to 100 ml of 0.1 M potassium cobalt cyanide solution. After 30 min, 0.015 mol of complexing agent (prepared in Example 3) was added, the temperature was raised to 40 °C, and the reaction was carried out for 6 h. After cooling to room temperature, the mixture was filtered, and the filter cake was washed with deionized water (3 × 50 ml). The mixture was then vacuum dried at 60 °C for 18 h to obtain the prepared low molecular weight polyethylene oxide catalyst.
[0049] (2) Preparation of polyethylene oxide
[0050] 10g of ethylene glycol and 0.01g of catalyst were added to a high-pressure reactor. The reactor was evacuated and heated to 120°C. Ethylene oxide was added until the reactor pressure reached 0.1MPa. The reactor was sealed and stirred at 120°C. When the reactor pressure dropped to 0.05MPa, ethylene oxide was continuously introduced. The pressure was maintained at 0.2MPa during the feeding process. When the feed was turned off and the pressure inside the reactor no longer changed significantly within 10 minutes, the addition of ethylene oxide was stopped. Stirring was continued for 4 hours. The mixture was then cooled to room temperature to obtain polyethylene oxide.
[0051] Figure 3 The graph shows the relationship between different catalyst dosages and the number-average molecular weight and molecular weight distribution of polyethylene oxide. The preparation methods of the catalyst and polyethylene oxide are basically the same as in Example 4, except that the amount of catalyst added is different.
[0052] from Figure 3 It can be seen that as the amount of catalyst added increases, the number average molecular weight of the obtained polyethylene oxide gradually decreases. Furthermore, by adjusting the amount of catalyst used in this application, polyethylene oxide with a number average molecular weight of 150,000 to 800,000 can be prepared. At the same time, the molecular weight distribution of the obtained polyethylene oxide is controlled between 1.05 and 1.1, and the molecular weight distribution is relatively narrow.
[0053] Comparative Example 1
[0054] The preparation methods for the catalyst and polyethylene oxide are basically the same as in Example 4, except that the complexing agent is replaced with an equal weight of a complexing agent prepared by the following method:
[0055] The preparation method of the complexing agent is basically the same as that in Example 1, except that the heptaethylene glycol in step S1 is replaced with an equimolar amount of triethylene glycol.
[0056] Comparative Example 2
[0057] The preparation methods for the catalyst and polyethylene oxide are basically the same as in Example 4, except that the complexing agent is replaced with an equal weight of a complexing agent prepared by the following method:
[0058] The preparation method of the complexing agent is basically the same as that in Example 1, except that the heptaethylene glycol in step S1 is replaced with an equimolar amount of polyethylene glycol (PEG 1000).
[0059] Comparative Example 3
[0060] The preparation methods for the catalyst and polyethylene oxide are basically the same as in Example 4, except that the complexing agent is replaced with an equal weight of a complexing agent prepared by the following method:
[0061] The preparation method of the complexing agent is basically the same as that in Example 1, except that iminodiacetic acid in step S2 is replaced with an equimolar amount of sarcosine.
[0062] Comparative Example 4
[0063] The preparation methods for the catalyst and polyethylene oxide are basically the same as in Example 4, except that the complexing agent is replaced with an equal weight of a complexing agent prepared by the following method:
[0064] The preparation method of the complexing agent is basically the same as that in Example 1, except that the amount of iminodiacetic acid added in step S2 is replaced with 0.104 mol.
[0065] The molecular weight and molecular weight distribution of the polyethylene oxide prepared in the examples and comparative examples were determined using a PL-GPC50 gel permeation chromatography instrument, and the results are shown in Table 1.
[0066] The polymerization yield is calculated using the following formula:
[0067] ;
[0068] Where m is the actual mass of polyethylene oxide obtained. This refers to the total mass of ethylene glycol and ethylene oxide added.
[0069] Table 1 Performance Test Data
[0070]
[0071] As can be seen from the data in Table 1, the catalyst prepared in this invention has a high yield and a narrow molecular weight distribution in the synthesis of polyethylene oxide from ethylene oxide.
[0072] The complexing agent of this invention contains multiple functional groups, including polyether segments, carboxyl groups, and hydroxyl groups, in its molecular structure. During the preparation of the bimetallic cyanide catalyst, the carboxyl and hydroxyl groups in the complexing agent can react with Zn. 2+Coordination occurs, forming Zn-O coordination bonds, which introduces the complexing agent into the surface or defect sites of the Zn-Co bimetallic cyanide structure in a coordinated form. This improves the catalyst's dispersibility and specific surface area, and forms more structural defects and unsaturated metal sites on the crystal surface, thereby increasing the number of Lewis acid active centers that can participate in the reaction. The electron-donating ability of the ether oxygen atoms in the polyether segments allows them to interact with Zn. 2+ The weak coordination interaction and the flexible polyether segments enable a more uniform distribution of active sites, which is beneficial to the stable polymerization reaction. In addition, the polyether structure has similar structural units to ethylene oxide monomers, which can generate a certain structural matching and adsorption enrichment effect on the catalyst surface, increasing the local concentration of ethylene oxide near the active sites and promoting its activation and ring-opening reaction. As a result, the prepared catalyst exhibits high catalytic activity, good reaction stability and controllability when catalyzing the polymerization of ethylene oxide to prepare polyethylene oxide. Therefore, the polyethylene oxide prepared using this catalyst has a high yield and a narrow molecular weight distribution.
[0073] In Comparative Example 1, the polyether segments in the complexing agent were significantly shortened, resulting in a reduction in the number of ether oxygen atoms in the molecule. This reduced the multi-site coordination ability, leading to a decrease in the number of active sites. Simultaneously, the shorter polyether segments had weaker adsorption and enrichment capabilities for ethylene oxide, resulting in a lower local concentration of monomers on the catalyst surface. Consequently, the polymerization rate decreased, manifesting as a lower polymerization yield and a wider molecular weight distribution. In Comparative Example 4, the number of carboxyl groups in the complexing agent was reduced, and they were located at one end, leading to a decrease in the complexing agent's ability to coordinate with Zn. 2+ The reduced coordination ability and increased differences in the active center environment lead to uneven growth rate of the polymerization chain, resulting in decreased polymerization activity, reduced polymerization yield, and a wider molecular weight distribution of the obtained polyethylene oxide.
[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.
Claims
1. A method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide, characterized in that, Includes the following steps: Zinc chloride solution was added dropwise to potassium cobalt cyanide solution, a complexing agent was added to react, and the catalyst was obtained after post-treatment. The structural formula of the complexing agent is as follows: 。 2. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 1, characterized in that, The complexing agent is prepared by the following method: S1: The reaction of heptaethylene glycol with epichlorohydrin yields intermediate 1. S2: Intermediate 1 reacts with iminodiacetic acid to obtain a complexing agent.
3. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 2, characterized in that, In step S1, the molar ratio of polyethylene glycol to epichlorohydrin is 1:(2.3-2.4).
4. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 2, characterized in that, In step S2, the molar ratio of intermediate 1 to iminodiacetic acid is 1:(2.08-2.1).
5. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 2, characterized in that, The solvent used in step S1 is toluene, the reaction temperature is 30-40℃, and the reaction time is 5-7h.
6. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 2, characterized in that, The solvent used in step S2 is DMF, the reaction temperature is 60-70℃, and the reaction time is 4-6h.
7. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 1, characterized in that, The molar ratio of potassium cobalt cyanide, zinc chloride and complexing agent is 1:(5-8):(1-1.5).
8. The method for preparing a catalyst for preparing medium- and low-molecular-weight polyethylene oxide according to claim 1, characterized in that, The reaction temperature is 30-40℃ and the reaction time is 6-8h.
9. A catalyst for preparing medium- and low-molecular-weight polyethylene oxide, characterized in that, It is prepared by the method described in any one of claims 1-8.
10. The application of a catalyst prepared by the method according to any one of claims 1-8 in the catalytic preparation of low molecular weight polyethylene oxide from ethylene oxide.