A method for preparing vinyl ethylene carbonate

Abstract

The present application relates to the technical field of chemical synthesis, and discloses a preparation method of vinyl ethylene carbonate, which uses a widely-sourced and low-toxicity vinyl carboxylic acid as a starting material, and sequentially undergoes three steps of epoxidation, carbon dioxide cycloaddition and hydroxy aldehyde condensation to obtain the target product under the catalysis of a functionalized polymeric ionic liquid. The method avoids the use of the highly toxic phosgene from the source, effectively avoids the generation of amine salt byproducts, and greatly improves the safety and environmental friendliness of the production process. The present application provides a new and feasible technical path for the large-scale and clean production of vinyl ethylene carbonate, and the preparation process has the advantages of low raw material cost, good controllability, green environmental protection and the like, and shows excellent industrial application potential and good market prospect in the field of high value-added fine chemical industry such as lithium ion battery electrolyte additives.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for preparing vinyl ethylene carbonate. Background Technology

[0002] Vinyl ethylene carbonate (VEC) is a multifunctional organic additive containing highly active vinyl functional groups. It possesses both excellent chemical stability and solubility, and is widely used in solvents, polymer additives, pharmaceutical synthesis intermediates, and surface coatings. Among its many applications, VEC's most crucial application is as an additive in lithium-ion battery electrolytes. As the core medium for ion transport within lithium-ion batteries, the performance of the electrolyte directly determines key indicators such as cycle life and charge-discharge efficiency. Research shows that adding trace amounts of VEC to the electrolyte can significantly improve the battery's cycle charge-discharge performance, which is of great significance for promoting the industrial application of lithium-ion batteries in the new energy field.

[0003] Currently, the common industrial method for preparing vinyl ethylene carbonate is transesterification: using halogenated hydrocarbons or aromatic hydrocarbons as solvents, organic amines as initiators and acid-binding agents, 3,4-butenediol and solid phosgene are reacted at a molar ratio of 3:1 to 1:1 under conditions of -10℃ to 50℃, yielding a crude product with a purity of up to 98% and a yield of over 70%. However, this preparation route has significant drawbacks. The reaction generates a large amount of organic amine hydrochloride byproducts, which not only increases the difficulty of subsequent separation and purification but also leads to resource waste and environmental pollution.

[0004] Existing technologies for preparing vinyl ethylene carbonate generally suffer from low yields, high production costs, and difficulty in meeting the needs of large-scale industrial production. Therefore, there is an urgent need to develop a new green, mild, efficient, and environmentally friendly route for preparing vinyl ethylene carbonate. Summary of the Invention

[0005] To address the problems of low yield, high production cost, and difficulty in meeting the needs of large-scale industrial production in existing vinyl ethylene carbonate preparation technologies, this invention provides a method for preparing vinyl ethylene carbonate.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: This invention provides a method for preparing vinyl ethylene carbonate, comprising the following steps: S1, the vinyl carboxylic acid shown in formula (I) and an oxidizing agent are subjected to an epoxidation reaction in an organic solvent to obtain the epoxidized acrylic acid intermediate shown in formula (II); S2, the epoxidized acrylic acid intermediate and carbon dioxide are subjected to an addition reaction under the catalysis of the first functionalized polymeric ionic liquid to obtain the cyclic carbonate intermediate shown in formula (Ⅲ); S3, the cyclic carbonate intermediate and the fatty aldehyde undergo an aldol condensation reaction under the catalysis of the second functionalized polymeric ionic liquid to obtain vinyl ethylene carbonate as shown in formula (Ⅳ). ; Wherein, R is H or alkyl.

[0007] Compared to existing technologies, the method for preparing vinyl ethylene carbonate provided by this invention achieves the goal of green, high-yield, and low-cost synthesis of vinyl ethylene carbonate through an innovative three-step process route consisting of epoxidation, cycloaddition, and aldol condensation. This route uses widely available, inexpensive, and low-toxicity vinyl carboxylic acids as starting materials, avoiding the use of highly toxic solid phosgene and organic amine reagents that easily produce salt byproducts in traditional processes, thus significantly improving the safety and environmental friendliness of this route.

[0008] This invention first converts vinyl carboxylic acid into an epoxidized acrylic acid intermediate via a mild epoxidation reaction with high selectivity. Then, this intermediate undergoes an atom-economical cycloaddition reaction with carbon dioxide under the catalysis of a functionalized polymeric ionic liquid to construct a cyclic carbonate structure. Finally, a vinyl functional group is introduced through an aldol condensation reaction, successfully yielding a high-purity, high-yield vinyl ethylene carbonate product. In this process, both the addition and aldol condensation steps utilize mild and highly selective catalytic systems. In particular, the use of carbon dioxide in the cycloaddition step (S2) not only achieves resource utilization of greenhouse gases and reduces reaction costs, but also, the participation of CO2 provides abundant oxygen functional groups to the cyclic carbonate skeleton, which is beneficial for improving the activity of the subsequent aldol condensation reaction, thereby increasing the yield of the vinyl ethylene carbonate product. This invention has the comprehensive advantages of mild conditions, high selectivity, low cost, and environmental friendliness, providing a feasible and efficient new method for the large-scale clean production of vinyl ethylene carbonate.

[0009] Furthermore, R is H or a C1~C3 alkyl group.

[0010] As a specific embodiment of the present invention, the preparation method of the vinyl ethylene carbonate specifically includes the following steps: S1, vinyl carboxylic acid and an oxidant are subjected to an epoxidation reaction in an organic solvent to obtain an epoxidized acrylic acid intermediate reaction solution; catalase is added to the epoxidized acrylic acid intermediate reaction solution to catalyze the decomposition of the residual oxidant, and then the excess catalase in the system is removed by vacuum filtration using an ultrafiltration membrane, and finally the system is subjected to vacuum rotary evaporation to obtain the epoxidized acrylic acid intermediate. S2, the epoxidized acrylic acid intermediate and carbon dioxide are subjected to an addition reaction under the catalysis of the first functionalized polymeric ionic liquid to obtain a cyclic carbonate intermediate reaction solution; the cyclic carbonate intermediate reaction solution is filtered to remove the first functionalized polymeric ionic liquid, ethanol is added to the filtrate, and then petroleum ether is slowly added dropwise for extraction. The lower ethanol phase is collected, and the ethanol is removed by rotary evaporation under reduced pressure to obtain the cyclic carbonate intermediate. S3, the cyclic carbonate intermediate and the aliphatic aldehyde undergo an aldol condensation reaction under the catalysis of the second functionalized polymeric ionic liquid. After the reaction is completed, vacuum distillation is performed to obtain vinyl ethylene carbonate. The specific synthetic route is as follows:

[0011]

[0012]

[0013] Further, in S1, the vinylcarboxylic acid is acrylic acid, methacrylic acid, or 2-pentenoic acid.

[0014] Furthermore, in S1, the oxidant is hydrogen peroxide or concentrated sulfuric acid.

[0015] Further, in S1, the organic solvent is at least one of methanol, dichloromethane, or ethanol.

[0016] Further, in S1, the molar ratio of the vinyl carboxylic acid to the oxidant is 1:1 to 1:2.

[0017] Furthermore, in S1, the temperature of the epoxidation reaction is 40℃~80℃, and the reaction time is 2h~8h.

[0018] Furthermore, in S2, the first functionalized polymeric ionic liquid is a PILs-XSS catalyst.

[0019] PILs-XSS catalysts can promote the efficient insertion of carbon dioxide and the construction of cyclic carbonate structures. After the reaction, the catalyst can be separated and recycled, reducing production costs.

[0020] Specifically, the preparation method of the PILs-XSS catalyst includes the following steps: 1-Ethyleneimidazolium, 1,2-dibromoethane, and acrylamide were reacted at 70℃~90℃ for 5h~7h to obtain an ionic liquid monomer. 2,2-Azobisisobutyronitrile was added to the ionic liquid monomer, mixed evenly, and then added to petroleum ether. Under a nitrogen atmosphere, the mixture was first reacted at 60℃~70℃ for 2h~3h, then heated to 70℃~80℃ for 2h~3h, and finally heated to 80℃~90℃ for 2h~3h. After the reaction was completed, the precipitate was collected, filtered, washed, and dried to obtain the PILs-XSS catalyst.

[0021] Furthermore, in S2, the amount of the first functionalized polymeric ionic liquid added is 1% to 4% of the mass of the epoxidized acrylic acid intermediate.

[0022] This catalyst dosage range allows for effective control of catalyst costs while ensuring high catalytic efficiency and selectivity in cycloaddition reactions.

[0023] Furthermore, in S2, the pressure of carbon dioxide gas is maintained at 1 MPa to 3 MPa during the addition reaction.

[0024] Furthermore, in S2, the temperature of the addition reaction is 50℃~100℃, and the reaction time is 2h~8h.

[0025] Furthermore, in S3, the fatty aldehyde is formaldehyde, acetaldehyde, or propionaldehyde.

[0026] Furthermore, in S3, the second functionalized polymeric ionic liquid is a PILCN-II catalyst.

[0027] Specifically, the preparation method of the PILCN-II catalyst includes the following steps: Methacrylic acid and diallylamine were reacted at 0℃~5℃ for 2h~4h to obtain an ionic liquid monomer; 2,2-azobisisobutyronitrile and divinylbenzene were added to the ionic liquid monomer and mixed evenly. The mixture was then reacted at 70℃~90℃ for 5h~7h under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the PILCN-II catalyst; wherein the molar ratio of divinylbenzene to methacrylic acid was 0.7:1.

[0028] Furthermore, in S3, the amount of the second functionalized polymeric ionic liquid added is 5% to 10% of the total mass of the cyclic carbonate intermediate and the aliphatic aldehyde.

[0029] Furthermore, in S3, the molar ratio of the cyclic carbonate intermediate to the aliphatic aldehyde is 1:1 to 1:5.

[0030] Furthermore, in S3, the aldol condensation reaction is carried out at a temperature of 60°C to 100°C for a reaction time of 0.5 h to 2 h.

[0031] In summary, this invention provides a method for preparing vinyl ethylene carbonate, using widely available and low-toxic vinyl carboxylic acid as the starting material. The method involves a three-step reaction process: epoxidation, carbon dioxide cycloaddition, and aldol condensation, catalyzed by a functionalized polymeric ionic liquid to obtain the target product. This method avoids the use of highly toxic phosgene at the source and effectively prevents the formation of amine salt byproducts, significantly improving the safety and environmental friendliness of the production process. This invention provides a feasible new technical route for the large-scale and clean production of vinyl ethylene carbonate, and its preparation process has outstanding advantages such as low raw material cost, good reaction controllability, and green environmental protection. It demonstrates excellent industrial application potential and a promising market prospect in high-value-added fine chemical fields such as lithium-ion battery electrolyte additives. Attached Figure Description

[0032] Figure 1 The epoxidized methacrylic acid intermediate prepared in Example 4 of this invention 1 H NMR spectrum; Figure 2 The cyclic carbonate intermediate prepared in Example 4 of this invention 1 H NMR spectrum; Figure 3 The preparation of vinyl ethylene carbonate in Example 4 of this invention 1 H NMR spectrum. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] To better illustrate the present invention, further examples are provided below.

[0035] The preparation method of the PILs-XSS catalyst in the following examples includes the following steps: 1-Ethyleneimidazolium (18.82 g), 1,2-dibromoethane (18.79 g), and acrylamide (7.11 g) were added to a three-necked flask and reacted at 80 °C for 6 h to obtain an ionic liquid monomer. Then, 2,2-azobisisobutyronitrile (0.22 g) was added as an initiator and stirred thoroughly until homogeneous. The mixture was then added to a three-necked flask containing petroleum ether and subjected to nitrogen protection throughout the reaction. The reaction was carried out under magnetic stirring: first at 65 °C for 2 h, then at 75 °C for 2 h, and then at 85 °C for 2 h. After the reaction was completed, the mixture was precipitated, filtered, washed, and dried to obtain the PILs-XSS catalyst.

[0036] The preparation method of the PILCN-II catalyst in the following examples includes the following steps: Under ice bath conditions, methacrylic acid (8.61 g, 0.1 mol) and diallylamine (9.72 g, 0.1 mol) were added to a three-necked flask and reacted for 3 h to obtain an ionic liquid monomer. 0.85 g AIBN and 9.11 g divinylbenzene (DVB) were added to the ionic liquid monomer, and the mixture was sonicated for 20 min to ensure homogeneity. The mixture was then reacted at 80 °C for 6 h under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered, washed, and dried in an oven at 80 °C to obtain the PILCN-II catalyst.

[0037] Example 1 This embodiment provides a method for preparing vinyl ethylene carbonate, comprising the following steps: S1, 4.30 g of methacrylic acid, 4.25 g (40 wt%) of hydrogen peroxide aqueous solution and 10 mL of methanol were added to a three-necked flask and reacted at 40 °C for 2 h to obtain a colorless and transparent crude solution; 0.0004 g of catalase was added to the crude solution and reacted at room temperature for 2 h. The enzyme was removed by ultrafiltration membrane filtration under reduced pressure. The filtrate was rotary evaporated under reduced pressure at 50 °C and 0.1 MPa to obtain 4.90 g of pure epoxidized methacrylic acid intermediate; S2, the colorless and transparent solution of the epoxidized methacrylic acid intermediate obtained above was cooled to room temperature and transferred to a reaction vessel. 0.0490 g of PILs-XSS catalyst was added, and the reaction vessel was pressurized to 1 MPa with CO2. The reaction was carried out at 50 °C for 2 h. After the reaction was completed, the catalyst was removed by filtration, and the filtrate was collected. The filtrate was added to 50 mL of anhydrous ethanol, and petroleum ether was added dropwise for extraction. The lower ethanol phase was collected. The ethanol was removed by rotary evaporation under reduced pressure at 50 °C and 0.1 MPa to obtain 6.52 g of cyclic carbonate intermediate. S3, the above cyclic carbonate intermediate was added to a flask, along with 0.51 g of PILCN-II catalyst and 3.62 g of formaldehyde solution (37 wt%). The mixture was reacted at 60 °C for 30 min to obtain a colorless and transparent crude vinyl ethylene carbonate product. Methanol was then removed by vacuum distillation to obtain 4.58 g of vinyl ethylene carbonate product, with a yield of 81.06% and a purity of 99.07%.

[0038] Example 2 This embodiment provides a method for preparing vinyl ethylene carbonate, comprising the following steps: S1, 3.60 g of acrylic acid, 4.68 g (40 wt%) of hydrogen peroxide aqueous solution and 10 mL of dichloromethane were added to a three-necked flask and reacted at 60 °C for 5 h to obtain a colorless and transparent crude solution; 0.0023 g of catalase was added to the crude solution and reacted at room temperature for 2 h. The enzyme was removed by ultrafiltration under reduced pressure. The filtrate was rotary evaporated under reduced pressure at 50 °C and 0.1 MPa to obtain 4.14 g of pure epoxidized acrylic acid intermediate. S2, the colorless and transparent solution of the epoxidized acrylic acid intermediate obtained above was cooled to room temperature and transferred to a reaction vessel. 0.1035 g of PILs-XSS catalyst was added, and the reaction vessel was pressurized to 2.0 MPa with CO2. The reaction was carried out at 100 °C for 4 h. After the reaction was completed, the catalyst was removed by filtration, and the filtrate was collected. The filtrate was added to 50 mL of anhydrous ethanol, and petroleum ether was added dropwise for extraction. The lower ethanol phase was collected. The ethanol was removed by rotary evaporation under reduced pressure at 50 °C and 0.1 MPa to obtain 5.65 g of cyclic carbonate intermediate. S3. The cyclic carbonate intermediate obtained above was added to a flask, along with 1.1505 g of PILCN-II catalyst and 17.36 g of formaldehyde solution (37 wt%). The mixture was reacted at 80 °C for 2 h to obtain a colorless and transparent crude vinyl ethylene carbonate product. Methanol was then removed by vacuum distillation to obtain 4.63 g of vinyl ethylene carbonate product, with a yield of 81.95% and a purity of 99.42%.

[0039] Example 3 This embodiment provides a method for preparing vinyl ethylene carbonate, comprising the following steps: S1. In a three-necked flask, 5.01 g of 2-pentenoic acid, 9.8 g of concentrated sulfuric acid, and 10 mL of methanol were added and reacted at 80 °C for 8 h to obtain a colorless and transparent crude solution. 0.0026 g of catalase was added to the crude solution, and after reacting at room temperature for 2 h, the solution was filtered under reduced pressure through an ultrafiltration membrane to remove the enzyme. The filtrate was placed in an ice-water bath at 0-5 °C and stirred to cool. Anhydrous sodium bicarbonate solid was added in batches, with each addition allowed to wait until the bubbles in the system completely disappeared before adding more, until the filtrate tested neutral (pH=7) on pH paper. After neutralization, the filtrate was rotary evaporated under reduced pressure at 50 °C and 0.1 MPa to remove methanol and trace amounts of water, yielding 5.34 g of pure epoxidized pentenoic acid intermediate. S2, after cooling the colorless and transparent solution of the epoxidized pentenoic acid intermediate obtained above to room temperature, it was transferred to a reaction vessel, 0.1869g of PILs-XSS catalyst was added, and then the reaction vessel was pressurized to 3.0MPa with CO2 and reacted at 85℃ for 8h. After the reaction was completed, the catalyst was removed by filtration, the filtrate was collected, the filtrate was added to 50mL of anhydrous ethanol, petroleum ether was added dropwise for extraction, the lower ethanol phase was collected, and the ethanol was removed by rotary evaporation under reduced pressure at 50℃ and 0.1MPa to obtain 6.92g of cyclic carbonate intermediate; S3. The cyclic carbonate intermediate obtained above was added to a flask, along with 1.168 g of PILCN-II catalyst and 4.76 g of acetaldehyde solution (40 wt%). The mixture was reacted at 100 °C for 60 min to obtain a colorless and transparent crude vinyl ethylene carbonate product. Methanol was then removed by vacuum distillation to obtain 4.59 g of vinyl ethylene carbonate product, with a yield of 81.24% and a purity of 99.01%.

[0040] Example 4 This embodiment provides a method for preparing vinyl ethylene carbonate, comprising the following steps: S1, 4.30 g of methacrylic acid, 5.1 g (40 wt%) of hydrogen peroxide aqueous solution and 10 mL of anhydrous ethanol were added to a three-necked flask and reacted at 80 °C for 6 h to obtain a colorless and transparent crude solution; 0.0026 g of catalase was added to the crude solution and reacted at room temperature for 2 h. The enzyme was removed by ultrafiltration under reduced pressure. The filtrate was rotary evaporated under reduced pressure at 50 °C and 0.1 MPa to obtain 4.95 g of pure epoxidized methacrylic acid intermediate. S2, after cooling the colorless and transparent solution of the epoxidized methacrylic acid intermediate obtained above to room temperature, it was transferred to a reaction vessel, 0.12 g of PILs-XSS catalyst was added, and then the reaction vessel was pressurized to 1.5 MPa with CO2 and reacted at 85 °C for 4 h. After the reaction was completed, the catalyst was removed by filtration, the filtrate was collected, the filtrate was added to 50 mL of anhydrous ethanol, and petroleum ether was added dropwise for extraction. The lower ethanol phase was collected, and the ethanol was removed by rotary evaporation under reduced pressure at 50 °C and 0.1 MPa to obtain 6.98 g of cyclic carbonate intermediate; S3. The cyclic carbonate intermediate obtained above was added to a flask, along with 1.09 g of PILCN-II catalyst and 3.88 g of formaldehyde solution (37 wt%). The mixture was reacted at 70 °C for 50 min to obtain a colorless and transparent crude vinyl ethylene carbonate product. Methanol was then removed by vacuum distillation to obtain 5.35 g of vinyl ethylene carbonate product, with a yield of 94.70% and a purity of 99.87%.

[0041] Comparative Example 1 This comparative example provides a method for preparing vinyl ethylene carbonate, which differs from Example 4 only in the catalyst used in step S2. The specific preparation method is as follows: S1, 4.30 g of methacrylic acid, 5.1 g (40 wt%) of hydrogen peroxide aqueous solution and 10 mL of ethanol were added to a three-necked flask and reacted at 80 °C for 6 h to obtain a colorless and transparent crude solution; 0.0026 g of catalase was added to the crude solution and reacted at room temperature for 2 h. The enzyme was removed by ultrafiltration membrane filtration under reduced pressure. The filtrate was rotary evaporated under reduced pressure at 50 °C and 0.1 MPa to obtain 4.95 g of pure epoxidized methacrylic acid intermediate; S2, after cooling the colorless and transparent solution of the epoxidized methacrylic acid intermediate obtained above to room temperature, it was transferred to a reaction vessel, 0.12 g of SF-L / Co catalyst was added, and then the reaction vessel was pressurized to 1.5 MPa with CO2 and reacted at 85 °C for 4 h. After the reaction was completed, the catalyst was removed by filtration, the filtrate was collected, the filtrate was added to 50 mL of anhydrous ethanol, and petroleum ether was added dropwise for extraction. The lower ethanol phase was collected, and the ethanol was removed by rotary evaporation under reduced pressure at 50 °C and 0.1 MPa to obtain 2.90 g of cyclic carbonate intermediate; S3. The cyclic carbonate intermediate obtained above was added to a flask, along with 1.09 g of PILCN-II catalyst and 3.88 g of formaldehyde solution (37 wt%). The mixture was reacted at 70 °C for 50 min to obtain a colorless and transparent crude vinyl ethylene carbonate product. Methanol was then removed by vacuum distillation to obtain 1.16 g of vinyl ethylene carbonate product, with a yield of 20.53% and a purity of 62.1%.

[0042] The preparation of the above SF-L / Co catalyst is described in the reference: Preparation of Schiff base metal catalyst and its catalytic synthesis of propylene carbonate from CO2, Sustainable Chemistry and Pharmacy, 2024, 41: 101696.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing vinyl ethylene carbonate, characterized in that, Includes the following steps: S1, the vinyl carboxylic acid shown in formula (I) and an oxidizing agent are subjected to an epoxidation reaction in an organic solvent to obtain the epoxidized acrylic acid intermediate shown in formula (II); S2, the epoxidized acrylic acid intermediate and carbon dioxide are subjected to an addition reaction under the catalysis of the first functionalized polymeric ionic liquid to obtain the cyclic carbonate intermediate shown in formula (Ⅲ); S3, the cyclic carbonate intermediate and the fatty aldehyde undergo an aldol condensation reaction under the catalysis of the second functionalized polymeric ionic liquid to obtain vinyl ethylene carbonate as shown in formula (Ⅳ). ； Wherein, R is H or alkyl.

2. The method for preparing vinyl ethylene carbonate as described in claim 1, characterized in that, In S1, the vinyl carboxylic acid is acrylic acid, methacrylic acid, or 2-pentenoic acid; In S1, the oxidant is hydrogen peroxide or concentrated sulfuric acid; and / or In S1, the organic solvent is at least one of methanol, dichloromethane, or ethanol.

3. The method for preparing vinyl ethylene carbonate as described in claim 1 or 2, characterized in that, In S1, the molar ratio of the vinyl carboxylic acid to the oxidant is 1:1 to 1:

2.

4. The method for preparing vinyl ethylene carbonate as described in claim 1 or 2, characterized in that, In S1, the temperature of the epoxidation reaction is 40℃~80℃, and the reaction time is 2h~8h.

5. The method for preparing vinyl ethylene carbonate as described in claim 1, characterized in that, In S2, the first functionalized polymeric ionic liquid is a PILs-XSS catalyst.

6. The method for preparing vinyl ethylene carbonate as described in claim 5, characterized in that, In S2, the amount of the first functionalized polymeric ionic liquid added is 1% to 4% of the mass of the epoxidized acrylic acid intermediate.

7. The method for preparing vinyl ethylene carbonate according to claim 1, characterized in that, In S2, the pressure of carbon dioxide gas is maintained between 1 MPa and 3 MPa during the addition reaction; and / or In S2, the temperature of the addition reaction is 50℃~100℃, and the reaction time is 2h~8h.

8. The method for preparing vinyl ethylene carbonate as described in claim 1, characterized in that, In S3, the fatty aldehyde is formaldehyde, acetaldehyde, or propionaldehyde; and / or In S3, the second functionalized polymeric ionic liquid is a PILCN-II catalyst.

9. The method for preparing vinyl ethylene carbonate as described in claim 8, characterized in that, In S3, the molar ratio of the cyclic carbonate intermediate to the aliphatic aldehyde is 1:1 to 1:5; and / or In S3, the amount of the second functionalized polymeric ionic liquid added is 5% to 10% of the total mass of the cyclic carbonate intermediate and the aliphatic aldehyde.

10. The method for preparing vinyl ethylene carbonate according to claim 1, characterized in that, In S3, the aldol condensation reaction is carried out at a temperature of 60℃~100℃ for a reaction time of 0.5h~2h.

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