A novel method for preparing vinyl sulfate

Abstract

The present invention provides a novel method for preparing vinyl sulfate, wherein ethylene glycol diacetate is used as a raw material, and reacts with diethyl sulfate under the catalysis of a solid superacid catalyst to generate vinyl sulfate, and the reaction liquid is post-treated and recrystallized to obtain the product vinyl sulfate. The present invention can reduce the reaction temperature and improve the reaction selectivity by improving the catalyst, and the catalyst can be recycled and reused. The preparation method of the present invention solves the problems of long reaction time, low conversion rate, low selectivity, carbonization and other side reactions in the prior art using inorganic strong acid catalysis; the catalyst prepared by the present invention is recyclable and has the advantage of recycling; there is no wastewater in the post-treatment, and it is environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical synthesis, and specifically relates to a method for preparing a novel vinyl sulfate. Background Art

[0002] Vinyl sulfate (1,3,2-Dioxathiolane 2,2-dioxide), melting point: 99°C, colorless crystals or crystalline powder at room temperature, sensitive to water and high temperature. The current market demand for vinyl sulfate is relatively stable, and production capacity is increasing year by year. With the rapid development of the electric vehicle industry, as well as the continuous expansion of production capacity and downstream application areas of products, the market demand for vinyl sulfate continues to rise. The development of efficient industrial synthesis technology of vinyl sulfate is conducive to promoting the sustainable development of downstream enterprises and will have good economic and social benefits. The wide application of vinyl sulfate has played a positive role in improving production efficiency, improving product performance and meeting market demand.

[0003] The use of vinyl sulfate is becoming more and more extensive, and the market demand is increasing. Acid vinyl ester is widely used in industry. Vinyl sulfate can be used to prepare surfactants and emulsifiers to adjust the interfacial tension of liquids and promote the mixing and dispersion of liquids and solids or liquids and liquids. These compounds are often used in detergents, cleaners, emulsions, coatings and other products. It also has a catalytic effect in certain specific chemical reactions, promoting the reaction and improving the reaction efficiency.

[0004] Vinyl sulfate can be used as a hydroxyethylating agent in organic synthesis to synthesize drug intermediates. It can also be used to synthesize certain heterocyclic compounds for gelatin hardening, antihypertensive drugs, and raw materials for new dual surfactants. Vinyl sulfate can be used as an additive for lithium-ion battery electrolytes. In the prior art, vinyl sulfate additives are generally added to the electrolyte to improve battery performance under high temperature conditions. Adding vinyl sulfate to the electrolyte of lithium-ion batteries can effectively inhibit the decline in the initial capacity of lithium-ion batteries, increase the initial discharge capacity, reduce the expansion of the battery after being placed at high temperatures, improve the charge and discharge performance of the battery, and extend the battery cycle life. In addition to being used in lithium-ion batteries, it is also widely used in the fields of medicine and material intermediates, and has broad market prospects.

[0005] At present, the synthesis methods of vinyl sulfate mainly include: acylation method, substitution method, addition method, dioxane synthesis method and direct oxidation method. At present, the commonly used method in industry is to prepare vinyl sulfite with thionyl chloride and ethylene glycol as raw materials, and further use vinyl sulfite as raw material, dichloromethane as solvent, and change the type of oxidant to obtain vinyl sulfate. Although the synthesis method of vinyl sulfate is constantly improving, there are still many problems, which cannot meet the high requirements of the market for the purity and yield of vinyl sulfate. Therefore, there is an urgent need for a method for preparing vinyl sulfate with easy-to-obtain raw materials, economical catalyst price, short reaction time, convenient operation, less by-products, high product purity and less wastewater. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to improve the deficiencies of the prior art and provide a method for preparing vinyl sulfate with readily available raw materials, economical catalyst price, short reaction time, convenient operation, fewer by-products, high product purity and less wastewater.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A novel method for preparing vinyl sulfate includes the preparation and reaction process of a solid superacid catalyst and a back-end processing process, and the preparation method includes the following steps:

[0009] (1) Preparation of solid superacid catalyst: SO4 containing trace amounts of Pb was prepared by precipitation-impregnation method. 2- / ZrO2 / Al2O3 sulfated zirconium oxide alumina solid superacid, the specific preparation process is: drop concentrated ammonia water into the aqueous solution of zirconium oxychloride to obtain zirconium hydroxide colloid, wash to remove chloride ions, dry to obtain powder, continue to add alumina powder to mix, impregnate with sulfuric acid, and then dry and roast to obtain SO4 2- / ZrO2 / Al2O3 catalyst, using a tablet press to form particles, then impregnating with a palladium chloride solution, and finally drying and calcining to obtain a solid superacid catalyst;

[0010] (2) Reaction: Add ethylene glycol diacetate and a solid superacid catalyst to a reaction kettle, then add diethyl sulfate and mix, and heat the reaction in a water ring pump vacuum, and distill the by-product ethyl acetate until no fraction is distilled out, stop the reaction, add dichloroethane solvent, filter and remove the solid superacid catalyst, add activated carbon to the filtrate for decolorization, filter and remove the activated carbon, and simply distill under reduced pressure until solid precipitates, add a crystallization solvent dropwise, cool and crystallize, and filter to obtain a crude vinyl sulfate product; the reaction equation is as follows:

[0011]

[0012] (3) Refining and drying of vinyl sulfate: Add a recrystallization solvent to the crude vinyl sulfate, stir and heat until the solution is clear, filter to obtain a filtrate, stir and cool to crystallize to a certain temperature, filter to obtain vinyl sulfate solid, and vacuum dry to obtain electronic grade vinyl sulfate.

[0013] Furthermore, a solid superacid catalyst is used instead of concentrated sulfuric acid to carry out the catalytic reaction.

[0014] Furthermore, a solid superacid catalyst is used as a reaction catalyst.

[0015] Furthermore, in step (2), the temperature of the reaction is raised to 50-90°C.

[0016] Furthermore, in the step (2), the vacuum degree of the vacuum condition is controlled to be 50 mmHg to 200 mmHg, and the by-product is distilled out.

[0017] Furthermore, the molar ratio of ethylene glycol diacetate to diethyl sulfate is 1:1.0-2.0.

[0018] Furthermore, the amount of the solid superacid catalyst is 0.1-1 wt % of ethylene glycol diacetate.

[0019] Furthermore, activated carbon powder is used to decolorize the reaction solution.

[0020] Furthermore, the preparation method also includes a crystallization step, a recrystallization step and a drying step.

[0021] Furthermore, the solvent used in the crystallization step is a combination of one or more selected from dichloromethane, dichloroethane, n-heptane, and n-hexane.

[0022] Furthermore, the solvent used in the recrystallization step is a combination of one or more selected from dimethyl carbonate, diethyl carbonate, and ethyl acetate.

[0023] Furthermore, the recrystallization solvent is dimethyl carbonate.

[0024] At present, most of the ethylene glycol diacetate produced in China has a content of between 80-95%, because ethylene glycol monoacetate is often produced in the process of preparing ethylene glycol diacetate, and ethylene glycol monoacetate is difficult to separate from the system. The ethylene glycol monoacetate and ethylene glycol diacetate generated in the reaction are separated by azeotropic distillation after extraction, but the extractants used are benzene, toluene, and xylene, all of which have certain toxicity, and benzene is highly carcinogenic. While taking the extractant, an azeotropic distillation tower needs to be added, which is complicated to operate and less feasible. The ethylene glycol diacetate provided by the present invention has high purity and the method is more environmentally friendly.

[0025] Furthermore, the preparation method of ethylene glycol diacetate is:

[0026] (1) 732 ion exchange resin (purchased from Aladdin, item number A113290) was washed with deionized water for 3-5 times, soaked in a 5 wt % sodium hydroxide aqueous solution for 15 h, then washed with deionized water until neutral, and then soaked in a 7 wt % hydrochloric acid aqueous solution for 15 h to obtain a hydrogen ion resin, and a 6 wt % potassium chloride aqueous solution was taken at 25° C. to perform ion exchange with the hydrogen ion resin, washed with deionized water until there was no chloride ion, and dried to constant weight to obtain a modified resin catalyst;

[0027] (2) In a fixed bed reactor, ethylene glycol methyl ether and acetic acid were mixed at a molar ratio of 1:1.7 and preheated to 105°C. Then, the prepared modified resin catalyst was continuously introduced at a flow rate of 37 L / h. The temperature was raised to 128°C for esterification reaction. The reaction space velocity was 4 h -1 After the reaction is completed, the product is dehydrated; the dehydration is carried out in the presence of entrainer benzene, and an azeotrope is formed at 68°C. After condensation and stratification, the upper organic phase is returned to the dehydration tower, and the lower aqueous phase is dehydrated. The materials in the bottom of the dehydration tower enter the light removal tower, and the materials in the bottom of the light removal tower enter the distillation tower for distillation, and ethylene glycol diacetate with a purity of 99.8% is distilled out at the top of the tower.

[0028] Furthermore, the preparation method of diethyl sulfate is as follows: ethyl hydrogen sulfate and anhydrous sodium sulfate in a mass ratio of 2.7:1 are mixed, and the temperature is raised to 95°C for reaction for 2.4 hours under stirring conditions; the temperature is further raised to 125°C for reaction for 3.2 hours; after the reaction is completed, the mixture is cooled to 40°C to obtain a mixed solution, water with a temperature of 15°C and a volume that is 7 times the volume of the mixed solution is added, and the mixture is stirred until it is completely dissolved, and the mixture is allowed to stand and separated to obtain an upper ester phase; the upper ester phase is distilled to obtain diethyl sulfate with a purity of 99.9%.

[0029] Diethyl sulfate is an organic compound, and diethyl sulfate has multiple application fields in industry. It can be used as a diluent in solvents, coatings and paints, and can also be used in the preparation of dyes, resins and plastics. In addition, diethyl sulfate can also be used as a raw material for catalysts, surfactants and emulsifiers. In the present invention, diethyl sulfate is used as a reaction raw material, which also has a very important influence on the purity and yield of the product. At present, the domestic production of diethyl sulfate mainly uses the sulfuric acid-ethylene method and the sulfuric acid (sulfur trioxide)-ethanol method. The process is divided into two steps. The first step is to prepare the intermediate of diethyl sulfate; the second step is to reduce the pressure of the intermediate under high temperature vacuum distillation. In this process, ethyl hydrogen sulfate reacts to generate diethyl sulfate and sulfuric acid. During the reduced pressure distillation process, the water content in the distillation bottom liquid is getting less and less, the sulfuric acid concentration is getting higher and higher, and the distillation efficiency is getting lower and lower. Concentrated sulfuric acid has strong oxidizing properties at high temperature, which will cause many side reactions, reduce the yield of diethyl sulfate, and produce a large amount of by-product sulfuric acid containing oxides. The preparation method of the present invention has few side reactions, high product purity, and no pollution to the environment.

[0030] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0031] 1. The preparation method of the present invention solves the problems of long reaction time, low conversion rate, low selectivity, and side reactions such as carbonization when using inorganic strong acid catalysis in the prior art; the catalyst prepared by the present invention is recyclable and has the advantage of recycling; there is no wastewater in the post-treatment, which is environmentally friendly.

[0032] 2. The present invention provides a new synthetic route for vinyl sulfate, which uses ethylene glycol diacetate as a raw material, reacts with diethyl sulfate under the catalysis of a solid superacid catalyst to generate vinyl sulfate, and the reaction liquid is post-treated and recrystallized to obtain the product vinyl sulfate. The present invention can reduce the reaction temperature and improve the reaction selectivity by improving the catalyst, and the catalyst can be recycled and reused.

[0033] 3. The reaction of the present invention is simple, and the product vinyl sulfate is generated in one step; by improving the catalyst, the reaction selectivity is improved, the reaction time is shortened, there is no obvious carbonization phenomenon, and the reaction yield is increased by 10-20%; the present invention uses a solid superacid catalyst, which can realize the reuse of the catalyst and has little corrosion to the equipment; compared with other reaction routes, this reaction route has the advantage of no wastewater.

[0034] 4. The inventors found that the commercially available ethylene glycol diacetate and diethyl sulfate were not of high purity and had many impurities. The present invention used ethylene glycol diacetate and diethyl sulfate from Jinan Guoshi Weiye Chemical Co., Ltd., and the product results were relatively ideal. However, in order to further reduce the impact of the reaction raw materials on the product and improve the yield and purity of the product, the present invention provides a method for preparing ethylene glycol diacetate and diethyl sulfate, and the obtained product has higher purity, which has a higher effect when used in the process of the present invention, and can further improve the purity and yield of the product. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment provides a method for preparing a novel vinyl sulfate, the preparation method comprising the following steps:

[0038] (1) Reaction: A simple vacuum distillation apparatus was set up, and the refrigerant was condensed at 5°C. 50 g of ethylene glycol diacetate, 52.8 g of diethyl sulfate and 0.2 g of concentrated sulfuric acid (98%) were weighed and added to a reaction flask. The reaction system was stirred magnetically and the vacuum was controlled to 100 mmHg. The temperature was raised to 60°C. A fraction gradually distilled out of the receiving flask. The obtained fraction was ethyl acetate. The internal temperature was controlled to 70°C and the reaction was kept warm for 9 h until no fraction was distilled out. The reaction liquid was an orange-yellow liquid. The reaction was stopped, the temperature was lowered to 30°C, 200 g of ethylene dichloride and 2 g of activated carbon powder were added, stirred for 1 h, and filtered to obtain a colorless vinyl sulfate solution. The dichloroethane solvent was removed by rotary evaporation at 40°C in a water bath, and about 120 g was transferred to a crystallization apparatus. Under stirring, 100 g of n-heptane was slowly added dropwise to the vinyl sulfate solution. Solid precipitated out of the system to form a white suspension. The temperature was slowly lowered to 0-5°C. 25.7 g of white solid was obtained by filtration.

[0039] (2) Purification: Put the crude vinyl sulfate into a 100 ml beaker, add 50 g of dimethyl carbonate, and heat to about 50° C. with magnetic stirring to dissolve. Filter with a Buchner funnel to obtain a colorless filtrate. Cool and stir to crystallize to an internal temperature of 10° C. Filter to obtain a filter cake, transfer to a rotary evaporator, dry in a water bath at 60° C., evacuate to less than 70 mmHg, and dry to constant weight to obtain 21.6 g of finished vinyl sulfate, with a yield of 50.87%, a purity of 99.53%, a moisture content of 32 ppm, and an acid value of 24 ppm.

[0040] The raw materials in this example are all commercially available. Ethylene glycol diacetate and diethyl sulfate were purchased from Jinan Guoshi Weiye Chemical Co., Ltd.

[0041] Embodiment 2:

[0042] This embodiment provides a method for preparing a novel vinyl sulfate, the preparation method comprising the following steps:

[0043] (1) Preparation of solid superacid catalyst: prepare a deionized water solution of zirconium oxychloride, drop a certain amount of concentrated ammonia water into the zirconium oxychloride solution to obtain a colloid of zirconium hydroxide, wash with a large amount of deionized water to remove chloride ions, detect with silver nitrate, wash the water until no chloride ions are washed out, dry in an oven at 120°C to obtain a powder, add an appropriate amount of alumina powder, stir and mix, add sulfuric acid for impregnation, dry at 120°C, and roast at 500°C to obtain SO4 2- / ZrO2 / Al2O3 catalyst is tableted into particles by a tablet press, sieved to obtain uniform particles of 10-20 mesh, then impregnated with palladium chloride solution, finally dried at 120°C, calcined at 650°C to obtain a solid superacid catalyst, cooled and packaged for use;

[0044] (2) Reaction: Set up a simple vacuum distillation apparatus, condense the refrigerant at 5°C, weigh 100g of ethylene glycol diacetate, 158.2g of diethyl sulfate and 1.0g of a solid superacid catalyst and add them to a reaction flask, stir magnetically, control the vacuum of the reaction system to 100mmHg, raise the temperature to 60°C, and gradually distill out of the receiving flask. The obtained distillate is ethyl acetate. Control the internal temperature at 60°C and keep the reaction for 4h until no distillate is distilled out. The reaction liquid is a yellow liquid, and the reaction is stopped. The mixture was cooled to 30°C, 400 g of ethylene dichloride was added to dissolve the mixture, and the catalyst was recovered by filtration. 5 g of activated carbon powder was added to the filtrate, and the mixture was stirred for 1 h. The mixture was filtered to obtain a colorless vinyl sulfate solution. About 200 g of the ethylene dichloride solvent was removed by rotary evaporation at 40°C in a water bath, and the mixture was transferred to a crystallization device. Under stirring, 150 g of n-heptane was slowly added dropwise to the vinyl sulfate solution. Solids precipitated from the system to form a white suspension. The mixture was slowly cooled to an internal temperature of 5°C and 64.2 g of a white solid was obtained by filtration.

[0045] (3) Purification: Put the crude vinyl sulfate into a 500 ml beaker, add 100 g of dimethyl carbonate, and heat to about 50° C. under magnetic stirring to dissolve. Filter with a Buchner funnel to obtain a colorless filtrate. Cool and stir to crystallize to an internal temperature of 10° C. Filter to obtain a filter cake, transfer to a rotary evaporator, dry in a water bath at 40° C., evacuate to less than 70 mmHg, and dry to constant weight to obtain 59.6 g of finished vinyl sulfate, with a yield of 70.18%, a purity of 99.73%, a moisture content of 45 ppm, and an acid value of 39 ppm.

[0046] The raw materials in this example are all commercially available. Ethylene glycol diacetate and diethyl sulfate were purchased from Jinan Guoshi Weiye Chemical Co., Ltd.

[0047] Embodiment 3:

[0048] This embodiment provides a method for preparing a novel vinyl sulfate, the preparation method comprising the following steps:

[0049] (1) Reaction: Set up a simple vacuum distillation apparatus, condense the refrigerant at 5°C, weigh 80g of ethylene glycol diacetate and 126g of diethyl sulfate and add them to a reaction flask, add 1g of the recovered solid superacid catalyst and add them to the reaction flask, stir and heat, control the vacuum of the reaction system to 110mmHg, heat to the internal temperature of 60°C, and gradually distill out of the receiving flask. The obtained distillate is ethyl acetate. Control the internal temperature at 60°C and keep the reaction for 5h until no distillate is distilled out. The reaction liquid is a yellow liquid, and the reaction is stopped. The mixture was cooled to 40°C, 350g of ethylene dichloride was added to dissolve it, and the secondary recovered catalyst was obtained by suction filtration. 5g of activated carbon powder was added to the filtrate, and the mixture was stirred for 1h. The mixture was suction filtered to obtain a colorless vinyl sulfate solution. About 200g of the ethylene dichloride solvent was removed by rotary evaporation at 40°C in a water bath, and the mixture was transferred to a crystallization device. Under stirring, 150g of n-heptane was slowly added dropwise to the vinyl sulfate solution. Solids precipitated from the system to form a white suspension. The mixture was slowly cooled to an internal temperature of 5°C and suction filtered to obtain 44.7g of a white solid.

[0050] (2) Purification: Put the crude vinyl sulfate into a 500 ml beaker, add 80 g of dimethyl carbonate, and heat to about 50° C. under magnetic stirring to dissolve. Filter with a Buchner funnel to obtain a colorless filtrate. Cool and stir to crystallize to an internal temperature of 10° C. Filter to obtain a filter cake, transfer to a rotary evaporator, dry in a water bath at 40° C., evacuate to less than 70 mmHg, and dry to constant weight to obtain 40.6 g of finished vinyl sulfate, with a yield of 59.76%, a purity of 99.55%, a moisture content of 36 ppm, and an acid value of 17 ppm.

[0051] The raw materials in this example are all commercially available. Ethylene glycol diacetate and diethyl sulfate were purchased from Jinan Guoshi Weiye Chemical Co., Ltd.

[0052] Example 4

[0053] The difference between this embodiment and embodiment 2 is that the preparation method of ethylene glycol diacetate is:

[0054] (1) 732 ion exchange resin (purchased from Aladdin, item number A113290) was washed with deionized water for 4 times, soaked in a 5 wt % sodium hydroxide aqueous solution for 15 h, then washed with deionized water until neutral, and then soaked in a 7 wt % hydrochloric acid aqueous solution for 15 h to obtain a hydrogen ion resin, and a 6 wt % potassium chloride aqueous solution was taken at 25° C. to perform ion exchange with the hydrogen ion resin, washed with deionized water until there was no chloride ion, and dried to constant weight to obtain a modified resin catalyst;

[0055] (2) In a fixed bed reactor, ethylene glycol methyl ether and acetic acid were mixed at a molar ratio of 1:1.7 and preheated to 105°C. Then, the prepared modified resin catalyst was continuously introduced at a flow rate of 37 L / h. The temperature was raised to 128°C for esterification reaction. The reaction space velocity was 4 h -1 After the reaction is completed, the product is dehydrated; the dehydration is carried out in the presence of entrainer benzene, and an azeotrope is formed at 68°C. After condensation and stratification, the upper organic phase is returned to the dehydration tower, and the lower aqueous phase is dehydrated. The materials in the bottom of the dehydration tower enter the light removal tower, and the materials in the bottom of the light removal tower enter the distillation tower for distillation, and ethylene glycol diacetate with a purity of 99.8% is distilled out at the top of the tower.

[0056] The preparation method of diethyl sulfate is as follows: ethyl hydrogen sulfate and anhydrous sodium sulfate in a mass ratio of 2.7:1 are mixed, and the temperature is raised to 95° C. for reaction for 2.4 hours under stirring conditions; the temperature is further raised to 125° C. for reaction for 3.2 hours; after the reaction is completed, the mixture is cooled to 40° C. to obtain a mixed solution, water with a temperature of 15° C. and 7 times the volume of the mixed solution is added, and the mixture is stirred until all dissolved, and the mixture is allowed to stand and separated to obtain an upper ester phase; the upper ester phase is distilled to obtain diethyl sulfate with a purity of 99.9%.

[0057] The yield of this embodiment is 75.39%, the purity is 99.80%, the moisture content is 26 ppm, and the acid value is 15 ppm.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 2 is that the charging amount of diethyl sulfate is 300g.

[0060] The product yield of this comparative example is 63.28%, the purity is 99.62%, the moisture content is 40ppm, and the acid value is 33ppm.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 2 is that the feeding amount of diethyl sulfate is 250g.

[0063] The product yield of this comparative example is 65.32%, the purity is 99.67%, the moisture content is 37ppm, and the acid value is 35ppm.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 2 is that the feed amount of diethyl sulfate is 70 g. The product yield of this comparative example is 65.01%, the purity is 99.69%, the water content is 36 ppm, and the acid value is 31 ppm.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 2 is that the feed amount of diethyl sulfate is 50 g. The product yield of this comparative example is 64.71%, the purity is 99.64%, the water content is 37 ppm, and the acid value is 35 ppm.

[0068] Comparative Example 5

[0069] The difference between this comparative example and Example 2 is that the amount of the solid superacid catalyst is 0.07 wt % of ethylene glycol diacetate.

[0070] The product yield of this comparative example is 60.76%, the purity is 99.53%, the moisture content is 43ppm, and the acid value is 36ppm.

[0071] It can be seen from Comparative Example 3 that if the solid superacid catalyst is too low, the reaction rate will be reduced, resulting in incomplete reaction within the same time and reduced yield.

[0072] Comparative Example 6

[0073] The difference between this comparative example and Example 2 is that the preparation method of ethylene glycol diacetate is:

[0074] (1) 732 ion exchange resin (purchased from Aladdin, item number A113290) was washed with deionized water for 3 times, soaked in a 4 wt % sodium hydroxide aqueous solution for 12 h, then washed with deionized water until neutral, and then soaked in a 5 wt % hydrochloric acid aqueous solution for 20 h to obtain a hydrogen ion resin, and an 8 wt % potassium chloride aqueous solution was taken at 30° C. to perform ion exchange with the hydrogen ion resin, washed with deionized water until there was no chloride ion, and dried to constant weight to obtain a modified resin catalyst;

[0075] (2) In a fixed bed reactor, ethylene glycol methyl ether and acetic acid were mixed at a molar ratio of 1:1.8 and preheated to 100°C. Then, the prepared modified resin catalyst was continuously introduced at a flow rate of 30 L / h. The temperature was raised to 120°C for esterification reaction. The reaction space velocity was 5 h -1 After the reaction is completed, the product is dehydrated; the dehydration is carried out in the presence of the azeotropic agent benzene, and an azeotrope is formed at 68°C. After condensation and stratification, the upper organic phase returns to the dehydration tower, and the lower aqueous phase is dehydrated. The materials in the bottom of the dehydration tower enter the light removal tower, and the materials in the bottom of the light removal tower enter the distillation tower for distillation, and ethylene glycol diacetate with a purity of 99.3% is distilled out at the top of the tower.

[0076] The yield of this comparative example is 70.12%, the purity is 99.75%, the moisture content is 29 ppm, and the acid value is 20 ppm.

[0077] Comparative Example 7

[0078] The difference between this comparative example and Example 2 is that the preparation method of diethyl sulfate is as follows: ethyl hydrogen sulfate and anhydrous sodium sulfate in a mass ratio of 2.5:1 are mixed, and the temperature is raised to 100°C for reaction for 2 hours under stirring; the temperature is further raised to 130°C and the reaction is performed for 4 hours; after the reaction is completed, the mixture is cooled to 50°C to obtain a mixed solution, water with a temperature of 10°C and an amount of 8 times the volume of the mixed solution is added, and the mixture is stirred until all dissolved, and the mixture is allowed to stand and separated to obtain an upper ester phase; the upper ester phase is distilled to obtain diethyl sulfate with a purity of 99.4%.

[0079] The yield of this comparative example is 75.42%, the purity is 99.76%, the moisture content is 28ppm, and the acid value is 17ppm.

[0080] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing vinyl sulfate, characterized in that: The preparation method comprises the following steps: (1) Preparation of solid superacid catalyst: Pb-loaded SO was prepared by precipitation-impregnation method. 2- / ZrO / Al O Solid superacid, the specific preparation process is: add concentrated ammonia water to the aqueous solution of zirconium oxychloride to obtain zirconium hydroxide colloid, wash to remove chloride ions, dry to obtain powder, continue to add aluminum oxide powder to mix, impregnate with sulfuric acid, and then dry and roast to obtain SO4 2- / ZrO2 / Al2O3 catalyst, using a tablet press to form particles, then impregnating with a palladium chloride solution, and finally drying and calcining to obtain a solid superacid catalyst; (2) Reaction: Add ethylene glycol diacetate and a solid superacid catalyst to a reaction kettle, then add diethyl sulfate and mix. Under vacuum with a water ring pump, use a simple distillation apparatus under reduced pressure to increase the temperature for reaction, distill out the by-product ethyl acetate until no fraction is distilled out, stop the reaction, add dichloroethane solvent, remove the solid superacid catalyst by filtration, add activated carbon to the filtrate for decolorization, remove the activated carbon by filtration, simply distill under reduced pressure until solid precipitates, add a crystallization solvent dropwise, cool down for crystallization, and filter to obtain a crude vinyl sulfate product. The reaction equation is as follows: ； (3) Refining and drying of vinyl sulfate: Add a recrystallization solvent to the crude vinyl sulfate, stir and heat until the solution becomes clear, filter to obtain a filtrate, stir and cool to crystallize to a certain temperature, filter to obtain vinyl sulfate solid, and vacuum dry to obtain vinyl sulfate.

2. The method for preparing vinyl sulfate according to claim 1, characterized in that: In the step (2), the temperature is raised to 50-90°C.

3. The method for preparing vinyl sulfate according to claim 1, characterized in that: In the step (2), the vacuum degree of the vacuum condition is controlled to be 50 mmHg to 200 mmHg, and the by-product is distilled out.

4. The method for preparing vinyl sulfate according to claim 1, characterized in that: The molar ratio of ethylene glycol diacetate to diethyl sulfate is 1:1.0-2.

0.

5. The method for preparing vinyl sulfate according to claim 1, characterized in that: The amount of the solid super acid catalyst is 0.1-1 wt % of ethylene glycol diacetate.

6. The method for preparing vinyl sulfate according to claim 1, characterized in that: The crystallization solvent is selected from a combination of one or more of dichloromethane, dichloroethane, n-heptane and n-hexane.

7. The method for preparing vinyl sulfate according to claim 1, characterized in that: The recrystallization solvent is selected from a combination of one or more of dimethyl carbonate, diethyl carbonate and ethyl acetate.

8. The method for preparing vinyl sulfate according to claim 7, characterized in that: The recrystallization solvent used in the recrystallization step is dimethyl carbonate.

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