A method for directly synthesizing vinylene carbonate

Abstract

The present invention relates to the field of chemical engineering technology, and in particular to a method for directly synthesizing vinylene carbonate; a method for directly synthesizing vinylene carbonate, the steps are as follows: After mixing diketene, a catalyst, and a solvent, carbon dioxide is introduced for reaction to obtain vinylene carbonate; In this application, diketene and carbon dioxide are used as raw materials, and the heteropolyacid salt catalyst added reacts with the imidazole-based ionic liquid to obtain a heteropolyacid salt-imidazole-based homogeneous catalyst. The generated heteropolyacid salt-imidazole-based homogeneous catalyst has weak alkalinity, good phase transfer activity and catalytic activity, so that diketene and carbon dioxide can directly synthesize vinylene carbonate under the action of the heteropolyacid salt-imidazole-based homogeneous catalyst; The catalyst and the imidazole-based ionic liquid used in this application can be recycled, the reaction is clean without by-products, the atom economy is high, and it is environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical engineering, and particularly to a method for directly synthesizing vinylene carbonate. Background Art

[0002] As a film-forming additive and overcharge protection additive for lithium-ion battery electrolytes, vinylene carbonate is the most ideal and effective additive for battery electrolytes. Vinylene carbonate can effectively inhibit the embedding of solvent molecules and the gas expansion phenomenon of lithium batteries, and can improve the battery capacity and cycle life. Vinylene carbonate can also be used as a monomer for preparing poly(ethylene carbonate) or for preparing photoresists, etc. At the same time, it can also be used in medical organic polymer materials, enzyme immobilization after modification, intermediates for organic synthesis, etc. Vinylene carbonate has great application potential and can play an obvious role in many aspects of different fields, and it is a product with high economic value.

[0003] In the prior art, the reaction principles involved in the synthesis process of vinylene carbonate are generally the same, that is, first, chloroethylene carbonate is obtained by chlorination reaction using ethylene carbonate as a reaction raw material, then the generated chloroethylene carbonate is subjected to dechlorination reaction to obtain a crude product of vinylene carbonate, and finally, the battery-grade VC finished product meeting the production requirements is obtained through crystallization purification; in the prior art, multiple steps of reactions are required to prepare vinylene carbonate products, and the steps are complex. Therefore, how to simplify the steps has become a problem to be solved by many manufacturers. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present application provides a method for directly synthesizing vinylene carbonate.

[0005] The present application provides a method for directly synthesizing vinylene carbonate, adopting the following technical scheme:

[0006] A method for directly synthesizing vinylene carbonate, the steps are as follows: After mixing diketene, a catalyst, and a solvent, carbon dioxide is introduced for reaction to obtain vinylene carbonate.

[0007] Preferably, the molar ratio of diketene, carbon dioxide, the catalyst, and the solvent is 1:(1 - 3):(0.005 - 0.05):(1 - 5).

[0008] Preferably, the solvent is an imidazole-based ionic liquid.

[0009] Preferably, the imidazole-based ionic liquid is at least one of 1-ethyl-3-methylimidazolium bromide, 1-ethyl-4-methylimidazolium bromide, and 1-ethyl-5-methylimidazolium bromide.

[0010] Preferably, the catalyst is a heteropolyacid salt catalyst.

[0011] Preferably, the catalyst is at least one of Dawson-type phosphomolybdates, Dawson-type vanadomolybdates, Keggin-type phosphomolybdates, and Keggin-type silicomolybdates.

[0012] Preferably, the catalyst is at least one of M6(P2Mo 18 O 62 )、M6(V2Mo 18 O 62 )、M3(PMo 12 O 40 )、M4(SiMo 12 O 40 ); where M is an alkali metal or an alkaline earth metal.

[0013] For example, the catalyst is Mg3(P2Mo 18 O 62 ), K6(V2Mo 18 O 62 ), Na3(PMo 12 O 40 ), Ca2(SiMo 12 O 40 ), or K4(SiMo 12 O 40 ).

[0014] Preferably, the reaction temperature is 110 - 150 °C; the reaction pressure is 3 - 6 Mpa; the reaction time is 0.5 - 2 h.

[0015] Preferably, the reaction temperature is 120 - 140 °C; for example, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C.

[0016] Preferably, the reaction pressure is 4 - 5 Mpa; for example, 4 Mpa, 4.1 Mpa, 4.2 Mpa, 4.3 Mpa, 4.4 Mpa, 4.5 Mpa, 4.6 Mpa, 4.7 Mpa, 4.8 Mpa, 4.9 Mpa, 5 Mpa.

[0017] Preferably, the reaction time is 0.75 - 1 h; for example, 0.75 h, 0.85 h, 0.95 h, 1 h.

[0018] In a specific feasible embodiment, diketene, a catalyst, and a solvent are mixed, then nitrogen is introduced for displacement, and then carbon dioxide is introduced, and the mixture is heated for reaction. After the reaction is completed, it is cooled, subjected to vacuum distillation, and rectified to obtain vinylene carbonate.

[0019] The synthesis process route of this application is as follows:

[0020]

[0021] In the present application, a heteropolyacid salt catalyst is added, and the added heteropolyacid salt (heteropolyacid salt catalyst) reacts with a solvent (imidazole ionic liquid) to obtain a heteropolyacid-imidazole homogeneous catalyst. The generated heteropolyacid-imidazole homogeneous catalyst has weak alkalinity, good phase transfer activity and catalytic activity.

[0022] In the present application, diketene and carbon dioxide are used as raw materials. Diketene is depolymerized into two vinyl ketones at high temperature. The vinyl ketone forms an acetylene alcohol intermediate state under the action of a heteropolysalt-imidazole homogeneous catalyst. This state is unstable and undergoes a carbonyl cycloaddition reaction with carbon dioxide to directly synthesize vinylene carbonate.

[0023] The catalyst and imidazole ionic liquid used in this application can be recycled, the reaction is clean and has no by-products, high atom economy, and is environmentally friendly.

[0024] In a specific embodiment, a method for directly synthesizing vinylene carbonate comprises the following steps: adding diketene, a heteropolyacid salt catalyst, and an ionic liquid as a solvent to a 5000 mL high-pressure reactor, replacing the atmosphere with nitrogen three times, introducing carbon dioxide, heating to the reaction temperature, and maintaining the reactor pressure by nitrogen pressure after the pressure drops. After the reaction is completed, the reactor is cooled to room temperature, and the product vinylene carbonate is obtained by vacuum distillation and rectification.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] In the present application, a heteropolyacid salt catalyst is added, and the added heteropolyacid salt catalyst reacts with an imidazole ionic liquid to obtain a heteropolyacid-imidazole homogeneous catalyst. The generated heteropolyacid-imidazole homogeneous catalyst has weak alkalinity, good phase transfer activity and catalytic activity, thereby enabling diketene and carbon dioxide to be directly synthesized into vinylene carbonate under the action of the heteropolyacid-imidazole homogeneous catalyst. DETAILED DESCRIPTION

[0027] The raw materials involved in this application are all commercially available products. The ionic liquids used in this embodiment are all conventional imidazole commercially available ionic liquids purchased from Aladdin. The application is further described in detail below in conjunction with the embodiments.

[0028] Source of raw materials:

[0029] Preparation of heteropolyacid salt catalyst:

[0030] Heteropolyacid salt catalyst (Mg3P2Mo 18 O 62) The synthesis method is as follows: Mix 1825.25 g of phosphomolybdic acid with 40.34 g of magnesium hydroxide and 7300 ml of water, carry out an acid-base neutralization reaction at 80 °C for 3 hours to obtain a heteropolyacid salt, bake the obtained heteropolyacid salt in a muffle furnace at 400 °C for 2 hours, and let it cool naturally for later use.

[0031] Heteropolyacid salt catalyst (K6V2Mo 18 O 62 ) The synthesis method is as follows: Mix 261.9 g of vanadomolybdic acid with 94.196 g of potassium hydroxide and 1047 ml of water, carry out an acid-base neutralization reaction at 80 °C for 3 hours to obtain a heteropolyacid salt, bake the obtained heteropolyacid salt in a muffle furnace at 400 °C for 2 hours, and let it cool naturally for later use.

[0032] Heteropolyacid salt catalyst (Na3PMo 12 O 40 ) The synthesis method is as follows: Mix 1825.25 g of phosphomolybdic acid with 61.98 g of sodium hydroxide and 7300 ml of water, carry out an acid-base neutralization reaction at 80 °C for 3 hours to obtain a heteropolyacid salt, bake the obtained heteropolyacid salt in a muffle furnace at 400 °C for 2 hours, and let it cool naturally for later use.

[0033] Heteropolyacid salt catalyst (Ca2SiMo 12 O 40 ) The synthesis method is as follows: Mix 1841.63 g of silicomolybdic acid with 56.08 g of calcium hydroxide and 7366 ml of water, carry out an acid-base neutralization reaction at 80 °C for 3 hours to obtain a heteropolyacid salt, bake the obtained heteropolyacid salt in a muffle furnace at 400 °C for 2 hours, and let it cool naturally for later use.

[0034] Heteropolyacid salt catalyst (K4SiMo 12 O 40 ) The synthesis method is as follows: Mix 1841.63 g of silicomolybdic acid with 94.2 g of potassium hydroxide and 7366 ml of water, carry out an acid-base neutralization reaction at 80 °C for 3 hours to obtain a heteropolyacid salt, bake the obtained heteropolyacid salt in a muffle furnace at 400 °C for 2 hours, and let it cool naturally for later use.

[0035] Example 1:

[0036] In a 5000 mL high-pressure reactor, add 300 g of diketene and the heteropolyacid salt catalyst (Mg3P2Mo 18 O 62)101.83 g, 2045.4 g of imidazole-based ionic liquid (1-ethyl-3-methylimidazolium bromide). After purging with nitrogen three times, 329.71 g of carbon dioxide was charged. It was heated and reacted at 120 °C and 5 Mpa for 1 hour. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 516.84 g of vinylene carbonate with a purity of 99.99% could be obtained, with a yield of 84.21% and a conversion rate of 97.57%.

[0037] Example 2:

[0038] In a 5000 mL high-pressure reaction kettle, 300 g of diketene, 218.05 g of heteropolyacid salt catalyst (K6V2Mo 18 O 62 ) and 2727.20 g of imidazole-based ionic liquid (1-ethyl-4-methylimidazolium bromide) were added. After purging with nitrogen three times, 345.41 g of carbon dioxide was charged. It was heated and reacted at 130 °C and 4 Mpa for 0.75 hour. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 495.48 g of vinylene carbonate with a purity of 99.99% could be obtained, with a yield of 80.73% and a conversion rate of 94.93%.

[0039] Example 3:

[0040] In a 5000 mL high-pressure reaction kettle, 300 g of diketene, 202.45 g of heteropolyacid salt catalyst (Na3PMo 12 O 40 ) and 1363.60 g of imidazole-based ionic liquid (1-ethyl-4-methylimidazolium bromide) were added. After purging with nitrogen three times, 376.82 g of carbon dioxide was charged. It was heated and reacted at 140 °C and 4 Mpa for 1 hour. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 502.60 g of vinylene carbonate with a purity of 99.99% could be obtained, with a yield of 81.89% and a conversion rate of 96.57%.

[0041] Example 4:

[0042] In a 5000 mL high-pressure reaction kettle, 300 g of diketene, 202.45 g of heteropolyacid salt catalyst (Ca2SiMo 12 O 40)67.78 g, 1-ethyl-5-methylimidazolium bromide (an imidazolium ionic liquid) 1363.60 g. After purging with nitrogen three times, 329.71 g of carbon dioxide was charged. It was heated and reacted at 120 °C and 5 MPa for 0.75 hours. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 521.81 g of vinylene carbonate with a purity of 99.99% was obtained, with a yield of 85.02% and a conversion rate of 98.21%.

[0043] Example 5:

[0044] In a 5000 mL high-pressure reaction kettle, 300 g of diketene, 67.78 g of heteropolyacid salt catalyst (Ca2SiMo 12 O 40 ), and 1363.60 g of imidazolium ionic liquid (1-ethyl-5-methylimidazolium bromide) were added. After purging with nitrogen three times, 329.71 g of carbon dioxide was charged. It was heated and reacted at 120 °C and 5 MPa for 0.75 hours. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 522.18 g of vinylene carbonate with a purity of 99.99% was obtained, with a yield of 85.08% and a conversion rate of 98.28%.

[0045] The heteropolyacid salt catalyst (Ca2SiMo 12 O 40 ) and the imidazolium ionic liquid (1-ethyl-5-methylimidazolium bromide) used in this example were recovered from Example 4.

[0046] Example 6:

[0047] In a 5000 mL high-pressure reaction kettle, 300 g of diketene, 70.50 g of heteropolyacid salt catalyst (K4SiMo 12 O 40 ), and 1363.60 g of imidazolium ionic liquid (1-ethyl-5-methylimidazolium bromide) were added. After purging with nitrogen three times, 329.71 g of carbon dioxide was charged. It was heated and reacted at 120 °C and 5 MPa for 0.75 hours. After the pressure dropped, nitrogen was charged to maintain the pressure in the reaction kettle. After the reaction was completed, it was cooled to room temperature. Through vacuum distillation and rectification, 520.28 g of vinylene carbonate with a purity of 99.99% was obtained, with a yield of 84.77% and a conversion rate of 98.10%.

[0048] Example 7:

[0049] The difference from Example 4 is that the reaction temperature was 115 °C.

[0050] 443.87 g of vinylene carbonate with a purity of 99.99% was prepared, with a yield of 72.32% and a conversion rate of 96.38%.

[0051] Example 8:

[0052] The difference from Example 4 is that the reaction temperature is 145 °C.

[0053] 459.64 g of vinylene carbonate with a purity of 99.99% was prepared, with a yield of 74.89% and a conversion rate of 96.43%.

[0054] Example 9:

[0055] The difference from Example 4 is that the reaction pressure is 3.5 Mpa.

[0056] 397.53 g of vinylene carbonate with a purity of 99.99% was prepared, with a yield of 64.77% and a conversion rate of 95.29%.

[0057] Example 10:

[0058] The difference from Example 4 is that the reaction pressure is 5.5 Mpa.

[0059] 491.12 g of vinylene carbonate with a purity of 99.99% was prepared, with a yield of 80.02% and a conversion rate of 95.43%.

[0060] For the vinylene carbonate prepared in Example 7 and Example 8, its output, yield, and conversion rate are all lower than those in Example 4, indicating that for high-pressure catalytic reactions, the reaction temperature affects the reaction time. If the reaction temperature is too low, the reaction time will be too long, causing the product to self-polymerize and affecting the yield; if the reaction temperature is too high, the product will decompose, thus affecting the output, yield, and conversion rate of the product.

[0061] For the vinylene carbonate prepared in Example 9 and Example 10, its output, yield, and conversion rate are all lower than those in Example 4, indicating that for high-pressure catalytic reactions, the reaction pressure affects the reaction time. If the reaction pressure is too low, the reaction time will be too long, causing the product to self-polymerize and affecting the yield; if the reaction pressure is too high, the product will decompose, thus affecting the output, yield, and conversion rate of the product.

[0062] The heteropolyacid salt catalyst (Ca2SiMo 12 O 40) The imidazole-based ionic liquid (1-ethyl-5-methylimidazolium bromide) was recovered in Example 4. The vinylene carbonate prepared in Example 5 had slightly higher yield, recovery rate, and conversion rate than the product prepared in Example 4. This was because the recovered catalyst contained residual products and some raw materials from before, resulting in slightly higher yield and recovery rate.

[0063] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for directly synthesizing vinylene carbonate, characterized in that, The steps are as follows: After mixing diketene, a catalyst, and a solvent, carbon dioxide is introduced for reaction to obtain vinylene carbonate; The solvent is an imidazole-based ionic liquid; The imidazole-based ionic liquid is at least one of 1-ethyl-3-methylimidazolium bromide, 1-ethyl-4-methylimidazolium bromide, and 1-ethyl-5-methylimidazolium bromide; The catalyst is a heteropolyacid salt catalyst; The catalyst is at least one of Dawson-type phosphomolybdates, Dawson-type vanadium molybdates, Keggin-type phosphomolybdates, and Keggin-type silicomolybdates.

2. A method for directly synthesizing vinylene carbonate according to claim 1, characterized in that: The molar ratio of diketene, carbon dioxide, the catalyst, and the solvent is 1:(1 - 3):(0.005 - 0.05):(1 - 5).

3. A method for directly synthesizing vinylene carbonate according to claim 1, characterized in that: The catalyst is at least one of M6(P2Mo 18 O 62 ), M6(V2Mo 18 O 62 ), M3(PMo 12 O 40 ), M4(SiMo 12 O 40 ); wherein, M is an alkali metal or an alkaline earth metal.

4. A method for directly synthesizing vinylene carbonate according to claim 1, characterized in that: The reaction temperature is 110 - 150 °C; the reaction pressure is 3 - 6 Mpa; the reaction time is 0.5 - 2 h.

5. A method for directly synthesizing vinylene carbonate according to claim 4, characterized in that: The reaction temperature is 120 - 140 °C; the reaction pressure is 4 - 5 Mpa; the reaction time is 0.75 - 1 h.

6. A method for directly synthesizing vinylene carbonate according to any one of claims 1-5, characterized in that: After mixing diketene, a catalyst, and a solvent, nitrogen is introduced for displacement, then carbon dioxide is introduced, and heating is carried out for reaction. After the reaction is completed, it is cooled, subjected to vacuum distillation, and rectified to obtain vinylene carbonate.

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