A catalyst for preparing ethylene sulfite, a method for preparing ethylene sulfite

Abstract

The present application relates to a catalyst for preparing ethylene sulfite, the catalyst comprising a hydrocarbyl borane and a nitrogen-containing organic compound, the molar ratio of the hydrocarbyl borane and the nitrogen-containing organic compound being 0.1-0.5:1. The present application also relates to a method for preparing ethylene sulfite, the method comprising: contacting ethylene oxide with sulfur dioxide in the presence of the catalyst described in the present application. The catalyst of the present application can well catalyze the synthesis of ethylene sulfite, the preparation process conditions are easy to control, and high-purity ethylene sulfite can be prepared at a high yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ester compounds, and particularly relates to a catalyst for preparing ethylene sulfite and a preparation method of ethylene sulfite. BACKGROUND

[0002] Ethylene sulfite is an important organic chemical raw material, which can be used for synthesizing other organic chemical products. Ethylene sulfite is also an excellent lithium ion battery electrolyte solvent or electrolyte additive, which can significantly improve the performance of the battery. With the vigorous development of new energy industry and lithium ion battery industry, the performance requirements of lithium ion batteries are getting higher and higher, and accordingly the demand for high-quality ethylene sulfite is also increasing.

[0003] At present, the methods for preparing ethylene sulfite mainly include: (1) ethylene glycol and thionyl chloride method, that is, ethylene glycol and thionyl chloride are reacted to prepare ethylene sulfite, but this method has the defects of high toxicity of thionyl chloride, many by-products, and difficult post-treatment and purification. The ethylene sulfite prepared by this method contains a large amount of by-product chloroethanol, which greatly affects the stability of the electrolyte in the lithium ion battery electrolyte, thereby seriously affecting the stability of the lithium ion battery. Further purification to remove chloroethanol to obtain battery-grade high-purity ethylene sulfite is a time-consuming process that increases production cost. (2) Ethylene glycol and dimethyl sulfite method, which can be carried out without catalyst, but the reaction time is very long and the reaction is not complete. CN1803767A discloses a process using p-toluenesulfonic acid as a catalyst, and continuously distilling methanol during the reaction process, thereby greatly improving the reaction efficiency. (3) Ethylene oxide and sulfur dioxide method, that is, under the action of a suitable catalyst, ethylene oxide and sulfur dioxide are catalytically reacted at high temperature and high pressure to prepare. The catalysts used include alkali metal halides, alkaline earth metal halides, and halides of iron, cobalt, nickel, and aluminum, but these methods have the problems of high operation condition requirements and low product yield. How to develop a new catalyst to prepare high-purity ethylene sulfite with high yield under easily controllable conditions is a technical problem to be solved at present. SUMMARY

[0004] The present application provides a catalyst for preparing ethylene sulfite and a preparation method of ethylene sulfite, so as to synthesize ethylene sulfite under simple and controllable conditions.

[0005] In a first aspect, the present application relates to a catalyst for preparing ethylene sulfite, which comprises a hydrocarbyl borane and a nitrogen-containing organic compound, and the molar ratio of the hydrocarbyl borane to the nitrogen-containing organic compound is 0.1-0.5:1.

[0006] Optionally, the hydrocarbyl borane is selected from trihydrocarbyl boranes, and the nitrogen-containing organic compound is selected from tertiary amines and / or diazabicyclo compounds; wherein the trihydrocarbyl borane is represented as BR1R2R3, R1, R2 and R3 are each independently selected from linear alkyl groups having a carbon number of 1-8, cyclic alkyl groups having a carbon number of 3-8, or aryl groups having a carbon number of 6-10.

[0007] Optionally, the trihydrocarbyl borane is selected from a combination of one or more of triethyl borane, tripropyl borane, tributyl borane and triphenyl borane.

[0008] Optionally, the tertiary amine is selected from a combination of one or more of triethyl amine, tripropyl amine and tributyl amine, and the diazabicyclo compound is 1,8-diazabicyclo[5.4.0.]undec-7-ene.

[0009] In a second aspect, the present application relates to a method for preparing ethylene sulfite, the method comprising: contacting ethylene oxide with sulfur dioxide in the presence of the catalyst according to the first aspect of the present application.

[0010] Optionally, the contacting of ethylene oxide with sulfur dioxide comprises: adding ethylene oxide into a reaction system, heating to 60-130°C, introducing sulfur dioxide to make the pressure of the reaction system 0.5-2 Mpa, and reacting for 2-8 hours.

[0011] Optionally, the method further comprises, before the adding of ethylene oxide into the reaction system, the step of: adding the catalyst into the reaction system, and introducing an inert gas for gas replacement.

[0012] Optionally, the method further comprises, before the adding of the catalyst into the reaction system, the step of: adding an organic solvent into the reaction system.

[0013] Optionally, the organic solvent is selected from a combination of one or more of tetrahydrofuran, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, dichloroethane, ethylene sulfite, dimethyl sulfoxide and N,N-dimethylformamide.

[0014] Optionally, the amount of the organic solvent is 2-5 times the weight of the ethylene oxide feed.

[0015] Optionally, the amount of the nitrogen-containing organic compound is 0.5-1% of the weight of the ethylene oxide feed.

[0016] Optionally, the method further comprises, after the contacting of ethylene oxide with sulfur dioxide, the step of: cooling, emptying and discharging the intermediate product from the reaction system; and vacuum distilling the intermediate product under reduced pressure to obtain ethylene sulfite.

[0017] Advantages:

[0018] The catalyst of the present application can well catalyze the synthesis of ethylene sulfite, the preparation process condition is easy to control, and high-purity ethylene sulfite can be prepared at a high yield. DETAILED DESCRIPTION

[0019] The present application will be further described in detail by examples. The features and advantages of the present application will become more apparent through these descriptions.

[0020] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0021] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0022] In a first aspect, the present application relates to a catalyst for preparing ethylene sulfite, which comprises a hydrocarbyl borane and a nitrogen-containing organic compound, and the molar ratio of the hydrocarbyl borane to the nitrogen-containing organic compound is 0.1-0.5:1.

[0023] It should be noted that in the catalyst for preparing ethylene sulfite of the present application, the hydrocarbyl borane can contain one hydrocarbyl group, two hydrocarbyl groups or three hydrocarbyl groups, and the nitrogen-containing organic compound can be an organic amine or a nitrogen-containing heterocyclic compound; the catalyst of the present application is a composition formula catalyst, and by making the molar ratio of the hydrocarbyl borane to the nitrogen-containing organic compound be 0.1-0.5:1, high-purity target product ethylene sulfite can be prepared at a high yield when catalyzing the synthesis of ethylene sulfite.

[0024] According to a specific embodiment of the catalyst according to the first aspect of the present application, the hydrocarbyl borane is selected from trihydrocarbyl boranes, and the nitrogen-containing organic compound is selected from tertiary amines and / or diazabicyclo compounds; wherein the trihydrocarbyl borane is represented as BR1R2R3, R1, R2 and R3 are each independently selected from a chain alkyl group with a carbon number of 1-8, a cyclic alkyl group with a carbon number of 3-8 or an aryl group with a carbon number of 6-10.

[0025] It should be noted that R1, R2 and R3 in the trihydrocarbyl borane BR1R2R3 can be the same or different groups, for example, the three groups can be methyl, ethyl and butyl respectively, or ethyl, butyl and butyl respectively, etc.; the chain alkyl group can be selected from linear alkyl and / or branched alkyl. In the catalyst of the present application, the hydrocarbyl group in the trihydrocarbyl borane can be a saturated hydrocarbyl group, i.e. an alkyl group, or an unsaturated hydrocarbyl group, such as an aryl group, etc., and the hydrocarbyl group can optionally contain atoms other than C, H and N. The three groups bonded to the N atom in the tertiary amine can be the same or different, and can be a low-carbon alkyl group, such as a chain alkyl group or a cyclic alkyl group having a carbon number of 1-8 or 1-5, the chain alkyl group can be selected from linear or branched alkyl, or can also be an unsaturated hydrocarbyl group, etc.

[0026] According to a specific embodiment of the catalyst according to the first aspect of the present application, the trihydrocarbyl borane is selected from one or more combinations of triethyl borane, tripropyl borane, tributyl borane and triphenyl borane.

[0027] It should be noted that when one or more combinations of triethyl borane, triphenyl borane, tributyl borane and tripropyl borane described above are used as the trihydrocarbyl borane in the catalyst for preparing ethylene sulfite according to the present application, the catalyst can further achieve better catalytic effect in the catalytic synthesis of ethylene sulfite, and higher-purity ethylene sulfite can be prepared at a higher yield.

[0028] According to a specific embodiment of the catalyst according to the first aspect of the present application, the tertiary amine is selected from one or more combinations of triethylamine, tripropylamine and tributylamine, and the diazabicyclo compound is 1,8-diazabicyclo[5.4.0.]undec-7-ene.

[0029] It should be noted that when one or more combinations of triethylamine, tripropylamine, tributylamine and 1,8-diazabicyclo[5.4.0.]undec-7-ene described above are used as the nitrogen-containing organic compound in the catalyst for preparing ethylene sulfite according to the present application, and the trihydrocarbyl borane is compounded according to the above molar ratio to form the catalyst, the catalyst can further achieve better catalytic effect, and higher-purity ethylene sulfite can be prepared at a higher yield.

[0030] According to a specific embodiment of the catalyst according to the first aspect of the present application, the trihydrocarbyl borane is selected from one or more combinations of triethyl borane, tripropyl borane, tributyl borane and triphenyl borane.

[0031] According to a specific embodiment of the catalyst according to the first aspect of the present application, the trihydrocarbyl borane is selected from one or more combinations of triethyl borane, tripropyl borane, tributyl borane and triphenyl borane.

[0032] It should be noted that in the method for preparing ethylene sulfite according to the present application, the catalyst according to the present application can well catalyze the reaction of ring-opening of ethylene oxide and sulfur dioxide to generate ethylene sulfite.

[0033] According to an embodiment of the method for preparing ethylene sulfite according to the second aspect of the present application, the step of reacting ethylene oxide with sulfur dioxide comprises:

[0034] The ethylene oxide is added into the reaction system, the temperature is raised to 60-130°C, and the sulfur dioxide is introduced to make the pressure of the reaction system 0.5-2Mpa, and the reaction is carried out for 2-8 hours.

[0035] According to an embodiment of the method for preparing ethylene sulfite according to the second aspect of the present application, the method further comprises the following steps before the step of adding ethylene oxide into the reaction system:

[0036] The catalyst is added into the reaction system, and inert gas is introduced for gas replacement.

[0037] According to an embodiment of the method for preparing ethylene sulfite according to the second aspect of the present application, the method further comprises the following steps before the step of adding the catalyst into the reaction system:

[0038] The organic solvent is added into the reaction system.

[0039] It should be noted that in the method for preparing ethylene sulfite according to the present application, in the first step, the organic solvent is added into the reaction system; in the second step, the catalyst is added, the reaction system is closed, and inert gas such as nitrogen is introduced to replace the ambient atmosphere in the reaction system with inert gas; in the third step, the ethylene oxide is added, and then the mixed solution in the reaction system is heated to the target temperature; in the fourth step, the sulfur dioxide is introduced to the target pressure, and along with the reaction, the pressure in the system will decrease, and then the sulfur dioxide is supplemented to the target pressure, and after the reaction pressure no longer decreases, the aging time of 15-45 minutes is allowed and the entire reaction time (including the aging time) is completed. The method for preparing according to the present application makes the ethylene oxide react with sulfur dioxide under high pressure in the presence of the organic solvent and the catalyst, and the conditions of the entire preparation process are mild and easy to control.

[0040] According to an embodiment of the method for preparing ethylene sulfite according to the second aspect of the present application, the organic solvent is selected from the group consisting of one or more of tetrahydrofuran, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, dichloroethane, ethylene sulfite, dimethyl sulfoxide, and N,N-dimethylformamide.

[0041] It should be noted that, in order to avoid the reaction of water in the organic solvent with ethylene oxide to generate by-products, the water content of the organic solvent can be controlled to be less than 0.1%, or, as a preferred embodiment, the organic solvent can be subjected to water removal and impurity removal by means of vacuum distillation or the like before being added to the reaction system, so as to reduce the introduction of impurities and the occurrence of side reactions; in the preparation method of the present application, the polar organic solvent is first added to the reaction system, which can make the catalyst better exert the catalytic effect, so as to better catalyze the reaction of ethylene oxide ring-opening with sulfur dioxide to generate ethylene sulfite.

[0042] According to a specific embodiment of the preparation method of the second aspect of the present application, the amount of the organic solvent is 2-5 times the weight of the ethylene oxide feed.

[0043] According to a specific embodiment of the preparation method of the second aspect of the present application, the amount of the nitrogen-containing organic compound is 0.5-1% of the weight of the ethylene oxide feed.

[0044] It should be noted that, when the amount of the nitrogen-containing organic compound in the catalyst is controlled to be 0.5-1% of the weight of the ethylene oxide feed, and less than 0.5% of the weight of the prepared ethylene sulfite, the catalyst can better exert the catalytic effect, so as to prepare the ethylene sulfite product with higher purity at a higher yield when the catalyst is used to catalyze the reaction of ethylene oxide with sulfur dioxide to synthesize ethylene sulfite.

[0045] According to a specific embodiment of the preparation method of the second aspect of the present application, the preparation method further comprises the following steps after the reaction of the ethylene oxide with the sulfur dioxide:

[0046] cooling, emptying and discharging the intermediate product from the reaction system; and subjecting the intermediate product to vacuum vacuum distillation to obtain ethylene sulfite.

[0047] It should be noted that the intermediate product obtained after cooling and emptying is a mixture of the target product ethylene sulfite and the organic solvent first added to the reaction system, and the vacuum vacuum distillation can obtain the ethylene sulfite and improve the purity of the prepared target product.

[0048] The present application will be further described in detail by means of the following examples, but the present application is not limited thereto.

[0049] The reagents used in the following examples can be commercially available product reagents, except for specifically stated otherwise.

[0050] Example 1

[0051] In a 500ml stirred autoclave, 100g of ethylene carbonate as solvent, 0.25g of triethylborane and 0.5g of triethylamine (molar ratio of catalyst composition 0.5:1) were added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 130°C, sulfur dioxide was introduced until the reaction pressure reached 2MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 2MPa, until the reaction pressure no longer decreased, and then aging for 30 minutes, the cumulative reaction time was 2 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get 222.5g of ethylene sulfite and ethylene carbonate mixture, then vacuum and reduced pressure rectification to get 122g of ethylene sulfite.

[0052] Example 2

[0053] In a 500ml stirred autoclave, 250g of ethylene sulfite as solvent, 0.04g of triphenylborane and 0.25g of tripropylamine (molar ratio of catalyst composition 0.1:1) were added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 120°C, sulfur dioxide was introduced until the reaction pressure reached 1MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 1MPa, until the reaction pressure no longer decreased, and then aging for 30 minutes, the cumulative reaction time was 3 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get 371.5g of ethylene sulfite mixture, then vacuum and reduced pressure rectification to get 371.5g of ethylene sulfite. Deduct the amount of ethylene sulfite used as solvent, 250g, the actual reaction obtained 121.5g of ethylene sulfite.

[0054] Example 3

[0055] In a 500ml stirred autoclave, 200g of dimethyl sulfoxide as solvent, 0.06g of tributylborane and 0.3g of tributylamine (molar ratio of catalyst composition 0.2:1) were added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 100°C, sulfur dioxide was introduced until the reaction pressure reached 0.5MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 0.5MPa, until the reaction pressure no longer decreased, and then aging for 30 minutes, the cumulative reaction time was 5 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get 322.1g of dimethyl sulfoxide and ethylene sulfite mixture, then vacuum and reduced pressure rectification to get 122g of ethylene sulfite.

[0056] Example 4

[0057] In a 500ml stirred autoclave, 150g of dichloroethane as solvent, 0.11g of tripropylborane and 0.4g of 1,8-diazabicyclo[5.4.0.]undec-7-ene (DBU) (catalyst composition molar ratio of 0.3:1) were added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 80°C, sulfur dioxide was introduced until the reaction pressure reached 0.8MPa, as the reaction proceeded, the reaction pressure dropped, then sulfur dioxide was supplemented to 0.8MPa, until the reaction pressure no longer dropped, then aging for 30 minutes, the cumulative reaction time was 8 hours. The reaction autoclave was cooled to 50°C, emptied and the product in the autoclave was released, obtaining a mixture of dichloroethane and ethylene sulfite 272.3g, then vacuum and reduced pressure rectification was carried out, obtaining 122.3g of ethylene sulfite.

[0058] Example 5

[0059] In a 500ml stirred autoclave, 200g of tetrahydrofuran as solvent, 0.06g of tributylborane and 0.3g of tri-butylamine (catalyst composition molar ratio of 0.2:1) were added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 60°C, sulfur dioxide was introduced until the reaction pressure reached 0.5MPa, as the reaction proceeded, the reaction pressure dropped, then sulfur dioxide was supplemented to 0.5MPa, until the reaction pressure no longer dropped, then aging for 30 minutes, the cumulative reaction time was 5 hours. The reaction autoclave was cooled to 50°C, emptied and the product in the autoclave was released, obtaining a mixture of tetrahydrofuran and ethylene sulfite 322.3g, then vacuum and reduced pressure rectification was carried out, obtaining 122g of ethylene sulfite.

[0060] Comparative Example 1:

[0061] In a 500ml stirred autoclave, 100g of ethylene carbonate as solvent, 0.25g of triethylborane was added, the autoclave was sealed and purged with nitrogen three times, then 50g of ethylene oxide was added, and then the reaction mixture was heated, when the reaction temperature reached 130°C, sulfur dioxide was introduced until the reaction pressure reached 2MPa, as the reaction proceeded, the reaction pressure dropped, then sulfur dioxide was supplemented to 2MPa, until the reaction pressure no longer dropped, then aging for 30 minutes, the cumulative reaction time was 2 hours. The reaction autoclave was cooled to 50°C, emptied and the product in the autoclave was released, obtaining a mixture of ethylene sulfite and ethylene carbonate 158.5g, then vacuum and reduced pressure rectification was carried out, obtaining 57.7g of ethylene sulfite.

[0062] Comparative Example 2:

[0063] In a 500ml stirred autoclave, 100g of ethylene carbonate as solvent, 0.5g of triethylamine were charged, the autoclave was closed and purged with nitrogen three times, then 50g of ethylene oxide was added, the reaction mixture was heated, when the reaction temperature reached 130°C, sulfur dioxide was introduced until the reaction pressure reached 2MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 2MPa, until the reaction pressure did not decrease, then aging for 30 minutes, the cumulative reaction time was 2 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get a mixture of 187g of ethylene sulfite and ethylene carbonate, then vacuum distillation, get 85g of ethylene sulfite.

[0064] Comparative Example 3:

[0065] In a 500ml stirred autoclave, 100g of ethylene carbonate as solvent, 0.5g of triethylamine were charged, the autoclave was closed and purged with nitrogen three times, then 50g of ethylene oxide was added, the reaction mixture was heated, when the reaction temperature reached 130°C, sulfur dioxide was introduced until the reaction pressure reached 2MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 2MPa, until the reaction pressure did not decrease, then aging for 30 minutes, the cumulative reaction time was 2 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get a mixture of 187g of ethylene sulfite and ethylene carbonate, then vacuum distillation, get 85g of ethylene sulfite.

[0066] Comparative Example 4:

[0067] In a 500ml stirred autoclave, 100g of ethylene carbonate as solvent, 0.5g of triethylamine were charged, the autoclave was closed and purged with nitrogen three times, then 50g of ethylene oxide was added, the reaction mixture was heated, when the reaction temperature reached 130°C, sulfur dioxide was introduced until the reaction pressure reached 2MPa, as the reaction proceeded, the reaction pressure decreased, then sulfur dioxide was added to 2MPa, until the reaction pressure did not decrease, then aging for 30 minutes, the cumulative reaction time was 2 hours. Cool the reactor to 50°C, empty and release the product in the autoclave, get a mixture of 187g of ethylene sulfite and ethylene carbonate, then vacuum distillation, get 85g of ethylene sulfite.

[0068] Test Example 1

[0069] The purity of the ethylene sulfite prepared in the above examples and comparative examples was analyzed by gas chromatography, and the analysis results are shown in Table 1 below.

[0070] Table 1

[0071]

[0072] From the data in Table 1 above, it can be seen that the purity of the vinyl ethylene sulfite prepared in the above examples is higher than 99%.

[0073] Test Example 2

[0074] The yield of the vinyl ethylene sulfite prepared in the above examples and comparative examples (relative to ethylene oxide) was calculated according to the following formula, and the results are shown in Table 2 below:

[0075]

[0076] Table 2

[0077]

[0078] From the data in Table 2 above, it can be seen that the yield of the vinyl ethylene sulfite prepared in the above examples by reacting ethylene oxide with sulfur dioxide using the catalyst of the present application is significantly improved compared to the comparative examples, and the yield of the vinyl ethylene sulfite in the above examples is greater than 99%. In addition, by yield = raw material conversion rate * selectivity, it can be concluded that the selectivity of the product in the above examples is also greater than 99%.

[0079] The above describes the present application in combination with preferred embodiments, but these embodiments are only exemplary and are for illustrative purposes only. On this basis, various substitutions and improvements can be made to the present application, and these all fall within the scope of protection of the present application.

Claims

1. A method for preparing vinyl sulfite, wherein: The preparation method comprises: In the presence of a catalyst, ethylene oxide is contacted with sulfur dioxide to react. The catalyst comprises a hydrocarbyl borane and a nitrogen-containing organic compound, the molar ratio of the hydrocarbyl borane to the nitrogen-containing organic compound is 0.1-0.5:1, and the nitrogen-containing organic compound is selected from tertiary amines and / or diazabicyclic compounds.

2. The preparation method according to claim 1, wherein The contact reaction of ethylene oxide and sulfur dioxide comprises: Ethylene oxide is added to the reaction system, the temperature is raised to 60-130° C., sulfur dioxide is introduced to make the pressure of the reaction system 0.5-2 MPa, and the reaction is carried out for 2-8 hours.

3. The preparation method according to claim 2, wherein The preparation method further comprises the following steps before adding ethylene oxide to the reaction system: The catalyst is added into the reaction system, and an inert gas is introduced to perform gas replacement.

4. The preparation method according to claim 3, wherein The preparation method further comprises the following steps before adding the catalyst to the reaction system: An organic solvent is added to the reaction system.

5. The preparation method according to claim 4, wherein The organic solvent is selected from one or more combinations of tetrahydrofuran, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethylene dichloride, ethylene sulfite, dimethyl sulfoxide and N,N-dimethylformamide.

6. The preparation method according to claim 4, wherein The amount of the organic solvent is 2-5 times the weight of the ethylene oxide feed.

7. The preparation method according to claim 1, wherein The amount of the nitrogen-containing organic compound used is 0.5-1% of the weight of the ethylene oxide feed.

8. The preparation method according to claim 1, wherein The preparation method further comprises the following steps after the ethylene oxide and sulfur dioxide are contacted and reacted: The reaction system is cooled, emptied and the intermediate product is released; the intermediate product is subjected to vacuum decompression distillation to obtain vinyl sulfite.

9. The preparation method according to claim 1, wherein The hydrocarbyl borane is selected from trihydrocarbyl borane, and the trihydrocarbyl borane is represented by BR1R2R3, where R1, R2 and R3 are each independently selected from a chain alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms or an aryl group having 6 to 10 carbon atoms.

10. The preparation method according to claim 9, wherein The trialkylborane is selected from a combination of one or more of triethylborane, tripropylborane, tributylborane and triphenylborane.

11. The preparation method according to claim 1, wherein The tertiary amine is selected from a combination of one or more of triethylamine, tripropylamine and tributylamine, and the diazabicyclic compound is 1,8-diazabicyclo[5.4.0.]undec-7-ene.

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