Dicarboxyl acid multi-active-site polyion liquid as well as preparation method and application thereof
By preparing a polyionic liquid with multiple active sites of dicarboxylic acids as a catalyst, the problems of insufficient catalytic activity and poor stability of existing polyionic liquid catalysts in the carbon dioxide cycloaddition reaction were solved, achieving a highly efficient and easily recoverable catalytic effect, and reducing reaction energy consumption and equipment requirements.
Patent Information
- Application Number
- CN202511023935.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-11-11
AI Technical Summary
Existing polyionic liquid catalysts suffer from insufficient catalytic activity, poor stability, and harsh reaction conditions in the catalytic carbon dioxide cycloaddition reaction, resulting in high energy consumption, increased costs, and demanding equipment requirements, which limits their industrial application.
By preparing dicarboxylic acid multi-active-site polyionic liquids, a diimidazolium cationic liquid and a hydroxyl-functionalized ionic liquid were reacted with a crosslinking agent, divinylbenzene, to form a polyionic liquid. The polyionic liquid was then obtained through anion exchange and used as a catalyst for the cycloaddition reaction of epoxides with carbon dioxide.
It achieves efficient catalytic cycloaddition reaction of epoxides with carbon dioxide under mild conditions. The catalyst is easy to recover, can be used multiple times without deactivation, and has a high yield of cyclic carbonates, reducing reaction energy consumption and equipment requirements.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyionic liquids and chemical catalysis technology, specifically relating to dicarboxylic acid multi-active-site polyionic liquids, their preparation methods, and applications. Background Technology
[0002] As is well known, heterogeneous catalysts have many advantages, such as being easier to separate from products and being reusable. In the past, the preparation of polyionic liquids (PILs) by copolymerization of ionic liquids with crosslinking agents has been extensively studied, not only because of the unique properties of ionic liquids (ILs) combined with macromolecular structures, but also because of the possibility of generating new properties and functions. The main advantages of polyionic liquids (PILs) for cycloaddition catalysts of CO2 and epoxides are: 1. High tunability: The chemical structure of polyionic liquids, such as anions, cations, and functional groups, can be controlled by design to optimize their catalytic performance; 2. Easy separation and recovery: Polyionic liquids are generally non-volatile and can be separated from the reaction system by simple filtration or centrifugation, making them easy to reuse; 3. Environmentally friendly. Although polyionic liquids have shown potential in catalyzing the cycloaddition reaction of carbon dioxide, they still have the following shortcomings: (1) Insufficient catalytic activity: Some polyionic liquids have low catalytic activity and are difficult to efficiently convert carbon dioxide under mild conditions, requiring high temperature and high pressure, which increases energy consumption and cost. (2) Stability issues: During the reaction, polyionic liquids may experience chemical structure degradation (e.g., ionic bond breakage, functional group decomposition, etc.), poor thermal stability (some polyionic liquids are prone to thermal decomposition at high temperatures, leading to catalyst deactivation and limiting their application in high-temperature reactions), and structural collapse (under long-term use or extreme conditions, the porous structure of polyionic liquids may collapse, resulting in a reduction in specific surface area and loss of active sites), which in turn leads to a decrease in catalytic performance and affects their long-term use. (3) Harsh reaction conditions: Some polyionic liquids require harsh conditions such as high temperature and high pressure, which increases the difficulty of operation and equipment requirements. Some polyionic liquids need to be at higher temperatures to exhibit good catalytic activity, leading to increased energy consumption and the possibility of side reactions or catalyst degradation; carbon dioxide cycloaddition reactions usually require a high-pressure environment (e.g., tens of atmospheres) to increase the solubility of carbon dioxide in the reaction system, which places higher demands on the equipment. The harsh conditions exhibited by polyionic liquids in catalytic reactions not only increase the difficulty and cost of the reaction operation, but also limit their application in actual industry. Therefore, it is necessary to develop more efficient and stable polyionic liquid catalysts and optimize reaction conditions to reduce dependence on temperature, pressure, and solvents. Currently, the application of polyionic liquids in catalyzing the carbon dioxide cycloaddition reaction still faces challenges related to activity, stability, selectivity, cost, and environmental impact. Summary of the Invention
[0003] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide an environmentally friendly, highly efficient, multi-active-site polyionic liquid, its preparation method and application.
[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a dicarboxylic acid multi-active-site polyionic liquid, the preparation method of which includes the following steps: reacting a diimidazolium cationic liquid and a hydroxyl-functionalized ionic liquid with a crosslinking agent divinylbenzene to obtain a polyionic liquid; then subjecting the polyionic liquid to anion exchange with a dicarboxylic acid to obtain a dicarboxylic acid multi-active-site polyionic liquid.
[0005] Further, the bisimidazole cationic ionic liquid is a bisimidazole bromide butane ionic liquid; the hydroxyl-functionalized ionic liquid is a bromoethanol-substituted ionic liquid. The dicarboxylic acid multi-active-site polyionic liquid has the general structural formula shown in (I):
[0006]
[0007] Among them, X - For anions derived from dicarboxylic acids, such as
[0008] Furthermore, the preparation method includes the following steps:
[0009] 1) Preparation of bromoethanol-substituted ionic liquid: 2-bromoethanol and 1-vinylimidazole were added to anhydrous ethanol and heated and stirred in an oil bath at 65℃-75℃ for 24h-25h. The mixture was then cooled to room temperature, rotary evaporated, washed with ethyl acetate, and dried under vacuum to obtain the bromoethanol-substituted ionic liquid.
[0010] 2) Preparation of bisimidazole bromide butane ionic liquid: 1-vinylimidazolium and 1,4-dibromobutane were added to methanol and refluxed for 24-25 h. After cooling, the mixture was rotary evaporated, washed with ethyl acetate, and dried under vacuum to obtain bisimidazole bromide butane ionic liquid.
[0011] 3) Preparation of brominated hydroxyl polyionic liquid: Under N2 atmosphere, bromoethanol-substituted ionic liquid, bisimidazole brominated butane ionic liquid, divinylbenzene (DVB) and azobisisobutyronitrile (AIBN) were dissolved in a mixed solution of water and ethanol. The resulting mixture was stirred at room temperature for 2-3 hours, and then reacted at 75℃-85℃ for 24-25 hours. After the reaction was completed, the mixture was washed with ethanol and water in sequence and dried under vacuum to obtain the brominated hydroxyl polyionic liquid.
[0012] 4) Preparation of hydroxyl exchange intermediate: Brominated hydroxyl polyionic liquid and NaOH were stirred at room temperature for 70-74 hours, the solid was collected by centrifugation and washed with hot water to obtain the hydroxyl exchange intermediate;
[0013] 5) Anion exchange: Anion exchange was performed using a dicarboxylic acid aqueous solution and a hydroxyl exchange intermediate. The mixture was washed with deionized water by centrifugation until neutral and then dried under vacuum to obtain a dicarboxylic acid multi-active-site polyionic liquid.
[0014] Further, in step 3), in the mixed solution of water and ethanol, the volume ratio of water to ethanol is 1:(4-6).
[0015] Further, in step 3), the amount of AIBN used is 0.1%-10% of the total molar amount of the bromoethanol-substituted ionic liquid and the diimidazole bromobutane ionic liquid.
[0016] Further, in step 5), the dicarboxylic acid is selected from one or more combinations of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, isophthalic acid, and terephthalic acid.
[0017] Further, in step 5), the anion exchange is carried out at a reaction temperature of 20℃-60℃ for 70h-72h.
[0018] This invention provides the application of a dicarboxylic acid multi-active-site polyionic liquid as a catalyst in the catalytic synthesis of cyclic carbonates from epoxy compounds.
[0019] Further, the method is as follows: using a dicarboxylic acid multi-active-site polyionic liquid as a catalyst, carbon dioxide and epoxy compounds are catalyzed and reacted at a pressure of 0.4MPa-0.8MPa and a temperature of 110℃-130℃ for 5h-36h to synthesize cyclic carbonates.
[0020] Further, the mass of the dicarboxylic acid multi-active-site polyionic liquid added is 3%-10% of the mass of the epoxy compound. Even further, the mass of the dicarboxylic acid multi-active-site polyionic liquid added is 3%-4% of the mass of the epoxy compound; even further, the mass of the dicarboxylic acid multi-active-site polyionic liquid added is 3.6% of the mass of the epoxy compound.
[0021] Further, the epoxy compound is propylene oxide, epichlorohydrin, epibutane, epibromopropane, styrene oxide, or allyl glycidyl ether.
[0022] The beneficial effects of this invention are:
[0023] This invention utilizes a dicarboxyl-based multi-active-site polyionic liquid as a catalyst in the cycloaddition reaction of epoxides with carbon dioxide to synthesize cyclic carbonates. Compared with traditional catalysts, the catalytic process of this invention is simple, the reaction system does not require solvents or co-catalysts, the reaction conditions are mild, the catalyst is easy to recover and can be used multiple times without losing its activity, and the yield of cyclic carbonates is high. Attached Figure Description
[0024] Figure 1 This is the 1H NMR spectrum of propylene carbonate obtained in Example 4.
[0025] Figure 2 This is the 1H NMR spectrum of propylene chloride obtained in Example 4.
[0026] Figure 3 This is the 1H NMR spectrum of butene carbonate obtained in Example 4.
[0027] Figure 4 This is the 1H NMR spectrum of bromopropylene carbonate obtained in Example 4.
[0028] Figure 5 This is the 1H NMR spectrum of styrene oxide ester obtained in Example 4.
[0029] Figure 6 This is the 1H NMR spectrum of allyl glycidyl ether ester obtained in Example 4. Detailed Implementation
[0030] Example 1: Dicarboxylic acid multi-active-site polyionic liquid ([A-C4DOH][PA])
[0031] (I) Preparation method
[0032] 1. Preparation of bromoethanol-substituted ionic liquids
[0033] 2-Bromoethanol (6.26 g, 50.0 mmol) and 50.0 mmol of 1-vinylimidazole were added to 25 mL of anhydrous ethanol. The mixture was heated and stirred in an oil bath at 70 °C for 24 h. The reaction mixture was then cooled to room temperature, and the ethanol was evaporated by rotary evaporation. The mixture was washed five times with ethyl acetate to remove impurities. Finally, it was dried under vacuum at 60 °C for 24 h to obtain the bromoethanol-substituted ionic liquid.
[0034] 2. Preparation of Bisimilar Butane Bromoisocyanate Ionic Liquid
[0035] 20.0 mmol of 1-vinylimidazole and 10.0 mmol of 1,4-dibromobutane were added to 10 mL of methanol, and the mixture was refluxed for 24 h. After cooling, the crude product was evaporated by rotary evaporation, washed five times with ethyl acetate, and dried under vacuum at 60 °C for 24 h to obtain the ionic liquid of bisimidazole bromide.
[0036] 3. Preparation of brominated hydroxyl polyionic liquids
[0037] Under a nitrogen atmosphere, 5.0 mmol of bromoethanol-substituted ionic liquid, 5.0 mmol of diimidazole bromobutane ionic liquid, 5.0 mmol of DVB and 0.5 mmol of AIBN were dissolved in a water / ethanol (5 mL / 25 mL) mixture. The resulting mixture was stirred at room temperature for 2 h, then reacted at 80 °C for 24 h. The mixture was washed five times with ethanol and water, and finally dried under vacuum at 60 °C for 24 h to obtain a white solid bromohydroxy polyionic liquid.
[0038] 4. Preparation of hydroxyl exchange intermediates
[0039] 0.5 g of white solid brominated hydroxyl polyionic liquid and NaOH (2 M, 100 mL) were stirred at room temperature for 72 h. The solid was then separated by centrifugation and washed several times with hot water to obtain the hydroxyl exchange intermediate.
[0040] 5. Anion exchange
[0041] The hydroxyl exchange intermediate was treated with malonic acid aqueous solution (1M, 150mL) for 72h at room temperature, then washed several times by centrifugation, filtration and washing with deionized water until the solution was neutral, and finally dried under vacuum at 60℃ for 48h to obtain a dicarboxylic acid multi-active site polyionic liquid, labeled as [A-C4DOH][PA], with the following structural formula:
[0042]
[0043] Example 2: Dicarboxylic acid multi-active-site polyionic liquid ([A-C4DOH][OA])
[0044] (I) Preparation method
[0045] 1. Preparation of bromoethanol-substituted ionic liquids: Same as in Example 1.
[0046] 2. Preparation of the diimidazole bromide ionic liquid: Same as in Example 1.
[0047] 3. Preparation of brominated hydroxyl polyionic liquid: Same as in Example 1.
[0048] 4. Preparation of hydroxyl exchange intermediate: Same as in Example 1
[0049] 5. Anion exchange
[0050] The hydroxyl exchange intermediate was treated with oxalic acid aqueous solution (1M, 150mL) for 72h at room temperature, then washed several times by centrifugation, filtration and washing with deionized water until the solution was neutral, and finally dried under vacuum at 60℃ for 48h to obtain a dicarboxylic acid multi-active-site polyionic liquid, labeled as [A-C4DOH][OA], with the following structural formula:
[0051]
[0052] Example 3: Dicarboxylic acid multi-active-site polyionic liquid ([A-C4DOH][SA])
[0053] (I) Preparation method
[0054] 1. Preparation of bromoethanol-substituted ionic liquids: Same as in Example 1.
[0055] 2. Preparation of the diimidazole bromide ionic liquid: Same as in Example 1.
[0056] 3. Preparation of brominated hydroxyl polyionic liquid: Same as in Example 1.
[0057] 4. Preparation of hydroxyl exchange intermediate: Same as in Example 1
[0058] 5. Anion exchange
[0059] The hydroxyl exchange intermediate was treated with succinic acid aqueous solution (1M, 150mL) for 72h at room temperature, then washed several times by centrifugation, filtration and washing with deionized water until the solution was neutral, and then dried under vacuum at 60℃ for 48h to obtain a dicarboxylic acid multi-active site polyionic liquid, labeled as [A-C4DOH][SA], with the following structural formula:
[0060]
[0061] Example 4: Cycloaddition reaction of epoxides catalyzed by dicarboxylic acid multi-active-site polyionic liquids
[0062] I. Effect of temperature on reaction yield
[0063] Method: In a 50 mL high-pressure reactor, 0.1 g of catalyst [A-C4DOH][PA] and 2.7756 g of epichlorohydrin were added, mixed well, and CO2 was introduced at 0.6 MPa. The reaction was carried out at the temperatures shown in Table 1 for 8 h. After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 1.
[0064] Table 1 Yields of cyclic carbonates at different temperatures
[0065] Temperature / °C 90 100 110 120 130 Yield / % 32.97 51.38 92.96 98.07 98.21
[0066] II. Effect of CO2 pressure on reaction yield
[0067] Method: In a 50 mL high-pressure reactor, 0.1 g of catalyst [A-C4DOH][PA] and 2.7756 g of epichlorohydrin were added, mixed well, and CO2 was introduced at the pressure shown in Table 2. The reaction was carried out at 120 °C for 8 h. After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 2.
[0068] Table 2 Yields of cyclic carbonates under different CO2 pressures
[0069] Pressure / MPa 0.4 0.5 0.6 0.7 0.8 Yield / % 92.16 96.34 98.07 98.13 98.13
[0070] III. Effect of catalyst dosage on reaction yield
[0071] Method: In a 50 mL high-pressure reactor, catalyst [A-C4DOH][PA] and 2.7756 g epichlorohydrin were added as shown in Table 3, mixed well, and CO2 was introduced at 0.6 MPa. The reaction was carried out at 120 °C for 8 h. After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 3.
[0072] Table 3 Yields of cyclic carbonates at different catalyst dosages
[0073] Catalyst dosage / g 0.08 0.09 0.10 0.11 0.12 Yield / % 95.28 96.75 98.07 98.12 98.23
[0074] IV. Effect of reaction time on reaction yield
[0075] Method: In a 50 mL high-pressure reactor, 0.1 g of catalyst [A-C4DOH][PA] and 2.7756 g of epichlorohydrin were added, mixed well, and CO2 was introduced at 0.6 MPa. The reaction time was adjusted as shown in Table 4 at 120 °C. After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 4.
[0076] Table 4 Yields of cyclic carbonates at different reaction times
[0077] Time / h 5 6 7 8 9 Yield / % 89.32 93.01 96.19 98.07 98.23
[0078] 1H NMR results ( Figure 2 This is consistent with the references, confirming the acquisition of the pure target product, propylene chloride carbonate. In summary, the cycloaddition reaction of epoxides catalyzed by dicarboxylic acid multi-site polyionic liquids is optimally performed under the following conditions: a pressure of 0.4 MPa-0.8 MPa and a temperature of 110℃-130℃ for 5-9 hours, with the dicarboxylic acid multi-site polyionic liquid added at 3%-4% of the epoxide mass, to synthesize cyclic carbonates. Considering energy consumption, cost, and yield, the optimal reaction conditions are: 0.6 MPa CO2 introduction, reaction at 120℃ for 8 hours, with the dicarboxylic acid multi-site polyionic liquid added at 3.6% of the epoxide mass.
[0079] V. Effect of different catalysts on reaction yield
[0080] Method: In a 50 mL high-pressure reactor, 0.10 g of different catalysts (as shown in Table 5) and 2.7756 g of epichlorohydrin were added, mixed well, and CO2 was introduced at 0.6 MPa. The reaction was carried out at 120 °C for 8 h. After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 5.
[0081] Table 5 Yields of cyclic carbonates synthesized by different catalysts
[0082] catalyst <![CDATA[[A-C4DOH][PA]]]> <![CDATA[[A-C4DOH][OA]]]> <![CDATA[[A-C4DOH][SA]]]> Yield / % 98.07 97.5 97.8
[0083] VI. Reaction yields of different epoxides
[0084] Method: In a 50 mL high-pressure reactor, 0.1 g of catalyst [A-C4DOH][PA] and 2.7756 g of different epoxides (as shown in Table 6) were added, mixed, and 0.6 MPa CO2 was introduced. The reaction was carried out at 120 °C (reaction conditions a: 8 h; reaction conditions b: 36 h). After the reaction was completed, the yield of cyclic carbonates was calculated, and the results are shown in Table 6. The products were detected by 1H NMR spectroscopy, and the results are as follows. Figure 1-6 As shown.
[0085] Table 6. Products and yields synthesized from the reaction of catalyst [A-C4DOH][PA] with different epoxides.
[0086]
Claims
1. A dicarboxylic acid multi-active-site polyionic liquid, characterized in that, The preparation method includes the following steps: reacting a diimidazole cationic liquid and a hydroxyl-functionalized ionic liquid with a crosslinking agent divinylbenzene to obtain a polyionic liquid; then performing anion exchange between the polyionic liquid and a dicarboxylic acid to obtain a dicarboxylic acid multi-active-site polyionic liquid.
2. The dicarboxylic acid multi-active-site polyionic liquid according to claim 1, characterized in that, The bisimidazole cationic liquid is a bisimidazole bromide butane ionic liquid; the hydroxyl-functionalized ionic liquid is a bromoethanol-substituted ionic liquid.
3. The dicarboxylic acid multi-active-site polyionic liquid according to claim 2, characterized in that, The preparation method includes the following steps: 1) Preparation of bromoethanol-substituted ionic liquid: 2-bromoethanol and 1-vinylimidazole were added to anhydrous ethanol and heated and stirred in an oil bath at 65℃-75℃ for 24h-25h. The mixture was then cooled to room temperature, rotary evaporated, washed with ethyl acetate, and dried under vacuum to obtain the bromoethanol-substituted ionic liquid. 2) Preparation of bisimidazole bromide butane ionic liquid: 1-vinylimidazolium and 1,4-dibromobutane were added to methanol and refluxed for 24-25 h. After cooling, the mixture was rotary evaporated, washed with ethyl acetate, and dried under vacuum to obtain bisimidazole bromide butane ionic liquid. 3) Preparation of brominated hydroxyl polyionic liquid: Under N2 atmosphere, bromoethanol-substituted ionic liquid, bisimidazole brominated butane ionic liquid, divinylbenzene and AIBN were dissolved in a mixed solution of water and ethanol. The resulting mixture was stirred at room temperature for 2-3 hours, and then reacted at 75℃-85℃ for 24-25 hours. After the reaction was completed, the mixture was washed with ethanol and water in sequence and dried under vacuum to obtain brominated hydroxyl polyionic liquid. 4) Preparation of hydroxyl exchange intermediate: Brominated hydroxyl polyionic liquid and NaOH were stirred at room temperature for 70-74 hours. The solid was collected by centrifugation and washed with hot water to obtain a hydroxyl exchange intermediate. 5) Anion exchange: Anion exchange was performed using a dicarboxylic acid aqueous solution and a hydroxyl exchange intermediate. The mixture was washed with deionized water by centrifugation until neutral and then dried under vacuum to obtain a dicarboxylic acid multi-active-site polyionic liquid.
4. The dicarboxylic acid multi-active-site polyionic liquid according to claim 3, characterized in that, In step 3), the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1:(4-6).
5. The dicarboxylic acid multi-active-site polyionic liquid according to claim 3, characterized in that, In step 3), the amount of AIBN used is 0.1%-10% of the total molar amount of the bromoethanol-substituted ionic liquid and the diimidazole bromide ionic liquid.
6. The dicarboxylic acid multi-active-site polyionic liquid according to claim 3, characterized in that, In step 5), the dicarboxylic acid is selected from one or more combinations of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, isophthalic acid, and terephthalic acid.
7. The dicarboxylic acid multi-active-site polyionic liquid according to claim 3, characterized in that, In step 5), the anion exchange is carried out at a reaction temperature of 20℃-60℃ for 70h-72h.
8. The application of a dicarboxylic acid multi-active-site polyionic liquid as a catalyst in the catalytic synthesis of cyclic carbonates from epoxides, as described in any one of claims 1-7.
9. The application according to claim 8, characterized in that, The method is as follows: using a dicarboxylic acid multi-active-site polyionic liquid as a catalyst, carbon dioxide and epoxy compounds are reacted at a pressure of 0.4MPa-0.8MPa and a temperature of 110℃-130℃ for 5h-36h to synthesize cyclic carbonates.
10. The application according to claim 9, characterized in that, The amount of the dicarboxylic acid multi-active-site polyionic liquid added is 3%-10% of the mass of the epoxy compound; the epoxy compound is propylene oxide, epichlorohydrin, epibutane, epibromopropane, styrene oxide, or allyl glycidyl ether.