A method for preparing cyclic vinyl sulfite by an external circulation spray type gas-liquid contact process

Abstract

This invention discloses a method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process. The method employs a spray-type external circulation reactor, dispersing an organic solvent into the gas phases of ethylene oxide and sulfur dioxide. This invention relates to the field of vinyl sulfite preparation technology. This method applies a spray-type external circulation reactor to a large-scale production unit capable of synthesizing vinyl sulfite from sulfur dioxide and ethylene oxide at a scale of tens of thousands of tons. Combined with distillation separation and purification technology, it breaks through the limitations of traditional intermittent production modes, achieving continuous industrial-scale production and significantly increasing production capacity and efficiency. Furthermore, the reactor enhances gas-liquid mass transfer efficiency and reaction controllability, reducing raw material waste and byproduct generation, making the production process cleaner and more environmentally friendly. Simultaneously, it significantly increases output per unit time, balancing environmental protection and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of vinyl sulfite preparation technology, specifically a method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process. Background Technology

[0002] Currently, the industrially applied process for preparing vinyl sulfite (ES) involves reacting ethylene glycol and thionyl chloride as raw materials. The disadvantages of this process are that the prepared ES has low purity, low atom economy, side reactions, and the generation of wastewater and salt.

[0003] There are no reports of industrial-scale production of ES using ethylene oxide and sulfur dioxide as raw materials. The available research and technologies are as follows:

[0004] Chinese Patent No. 202211516524.7 discloses a method for preparing vinyl sulfite, wherein ethylene oxide and sulfur dioxide react under the catalysis of imidazole ionic liquid and auxiliary agent to obtain vinyl sulfite, with an ES yield ≥95.3% and an ES purity ≥99.2%;

[0005] Chinese Patent No. 202310832575.9 discloses a method for preparing vinyl sulfite, which involves proportioning ethylene oxide, sulfur dioxide, imidazole ionic liquid, and additives, and then placing the proportioned ethylene oxide, sulfur dioxide, imidazole ionic liquid, and additives into a microchannel reactor for reaction. The product yield is 96.2%, and the product purity is 99.1%.

[0006] Chinese Patent No. 200610167329.2 discloses a method for preparing vinyl sulfite, comprising reacting sulfur dioxide with ethylene oxide in the presence of a catalyst, wherein the catalyst is a complex B formed by polyethylene glycol (PEG) and a metal halide.

[0007] Chinese Patent No. 202410636482.3 discloses a method for preparing and applying vinyl sulfite ester compounds. The preparation method includes reacting an epoxy compound and sulfur dioxide under the action of a supported organic base catalyst to obtain vinyl sulfite ester compounds with a yield ≥93% and a purity ≥99.7%. The supported organic base catalyst is formed by chemically linking an organic base with a chloromethylated resin.

[0008] Chinese Patent No. 202410281765.0 discloses a method for preparing vinyl sulfite, wherein ethylene carbonate and sulfur dioxide are reacted under the catalysis of metal chloride and under elevated temperature and pressure for 6-12 hours to obtain crude vinyl sulfite.

[0009] Chinese Patent No. 202210273908.4 discloses a method for preparing vinyl sulfite using a microchannel reactor. The method uses ethylene glycol and thionyl chloride as starting materials and chloroalkanes as reaction solvents. The nucleophilic substitution reaction is carried out in the microchannel reactor at 30-50°C. The selectivity of the product is as high as 97.89%, and the product yield is increased from 91% to 96%. In addition, continuous production is achieved through microchannel reaction.

[0010] Chinese Patent No. 202310173985.7 discloses a catalyst for preparing vinyl sulfite and a method for preparing vinyl sulfite. The catalyst includes an organoaluminum compound and an amine. The method for preparing vinyl sulfite includes reacting ethylene oxide with sulfur dioxide in the presence of the catalyst. The quaternary ammonium salt and trialkylaluminum in the catalyst activate the ring-opening of the ethylene oxide monomer through phase transfer and coordination, thereby promoting the reaction of SO2 with ethylene oxide to generate vinyl sulfite. High-purity (≥99.7%) vinyl sulfite is then prepared in high yield (≥99.1%).

[0011] Yang Mingxia reported on the effects of reaction temperature, raw material ratio, solvent amount on the yield of vinyl sulfite and the effect of catalyst on reaction time using ethylene glycol and thionyl chloride as raw materials and acetonitrile as solvent.

[0012] F. Zbigniew et al. reported that sulfur dioxide and ethylene oxide undergo copolymerization in the presence of Lewis bases capable of forming ononium ions (such as amines, phosphines, diethyl sulfide, dimethyl sulfoxide, and N,N-dimethylformamide) to produce vinyl sulfite containing a small amount of homologous sequences of ethylene oxide monomer units.

[0013] A comprehensive analysis of domestic and international literature reveals that research and reports on the synthesis of vinyl sulfite from ethylene oxide and sulfur dioxide mainly focus on catalysts, while process technology inventions primarily utilize reactors or microchannel reactors. This invention is specifically designed for ethoxylation reactions using a spray-type external circulation reactor. Leveraging its unique structural design and technical characteristics, this reactor enhances gas-liquid mass transfer, provides precise temperature control, and is suitable for continuous ethoxylation production while remaining safe and convenient. Applying this reactor to the synthesis of vinyl sulfite from ethylene oxide and sulfur dioxide can effectively improve the quality and capacity of ES products while reducing production costs, making it the preferred equipment for this synthesis reaction. Summary of the Invention

[0014] To address the shortcomings of existing technologies, this invention provides a method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process. This method solves the problems of low gas-liquid mass transfer efficiency, poor temperature control accuracy, uneven catalyst dispersion, easy leakage of volatile raw materials, and insufficient adaptability to continuous production in the preparation of vinyl sulfite.

[0015] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process, employing a spray-type external circulation reactor, wherein an organic solvent is atomized and dispersed into the gas phases of ethylene oxide and sulfur dioxide, and under the action of a catalyst, at a reaction pressure of 0.3-5.0 MPa and a reaction temperature of 80-300°C, sulfur dioxide and alkyl epoxides are used as raw materials to react and prepare vinyl sulfite;

[0016] The specific reaction process is as follows: The catalyst and organic solvent are added to a spray-type external circulation reactor. After the airtightness is verified, nitrogen is purged three to five times. Then, the circulation system and heating system are started. After heating to 80-300℃, ethylene oxide and sulfur dioxide are continuously introduced. The reaction temperature is controlled by the external circulation heating and cooling system. The reaction pressure is controlled within 0.3-5.0MPa by controlling the feed rate of ethylene oxide and sulfur dioxide. After the required amount of ethylene oxide and sulfur dioxide is reached, the feeding is stopped. The reaction temperature is maintained to start aging for 2-5 hours. Then, the temperature is lowered to 60-70℃ and the product is discharged. After discharge, qualified products are obtained by vacuum distillation and resin purification.

[0017] Preferably, the sulfur dioxide and ethylene oxide in the reactants need to be strictly dehydrated (water content <50ppm) to avoid hydrolysis to generate ethylene glycol or sulfurous acid, which would affect purity and thermal stability. The molar ratio of the two is 1.0-1.5:1.

[0018] Preferably, the range of organic solvents selected includes: cyclohexane, n-hexane, n-heptane, toluene, xylene, vinyl sulfite, ethylene carbonate, and dimethyl carbonate, and the amount used is 2-4 times the mass of ethylene oxide, which can prevent the organic solvent from reacting with the catalyst or reactants.

[0019] Preferably, the catalytic system includes triethylaluminum, triethylboron composite system, quaternary ammonium salt-quaternary phosphonium salt, organic amine, metal halide complex, ionic liquid, with the following selection range: tetrabutylammonium bromide, tetrabutylammonium chloride, tetraethylammonium bromide, tetrabutylphosphonium chloride, tetraphenylphosphonium bromide, triethylaluminum, 1,8-diazabicyclo(5,4,0)undec-7-ene, triethylenediamine, triisopropanolamine, potassium iodide, potassium bromide, sodium bromide, calcium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium tetrafluoroborate.

[0020] Preferably, the reaction process is controlled by a reactor heating system, specifically by a stepped heating method with a heating rate of 1-5°C per minute to avoid local overheating.

[0021] Preferably, the vacuum distillation specifically involves distilling the crude product at a temperature of 80-90℃ and a pressure of 0.08-0.1MPa to remove light components and catalyst residues, followed by resin adsorption purification to further improve the purity to 99.99%+.

[0022] Preferably, the catalyst is pretreated with ultrasound for 10-20 minutes before use, with a pretreatment power of 80-120W, to ensure uniform dispersion of catalyst particles and increase the exposure of catalytic active sites.

[0023] Preferably, when sulfur dioxide is introduced, a microporous distributor is used to disperse the gas intake, with the micropore diameter being 5-20 μm, to enhance the gas-liquid contact area and mass transfer efficiency.

[0024] Preferably, the aging stage adopts an intermittent stirring mode, stirring for 15 minutes and stopping for 5 minutes, and repeating the cycle to promote the full reaction of residual raw materials in the reaction system.

[0025] Preferably, the resin refining process uses a combination of macroporous adsorption resin and cation exchange resin in series. First, the macroporous adsorption resin removes organic impurities, and then the cation exchange resin removes residual metal ions.

[0026] Beneficial effects

[0027] This invention provides a method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process. Compared with existing technologies, it has the following advantages:

[0028] (1) The method for preparing cyclic vinyl sulfite by the external circulation spray gas-liquid contact process is to apply the spray-type external circulation reactor to a 10,000-ton-level production unit for the catalytic synthesis of vinyl sulfite from sulfur dioxide and ethylene oxide, and combine it with distillation separation and purification technology to break the limitations of the traditional intermittent production mode, realize industrial continuous mass production, and greatly improve the production capacity and efficiency.

[0029] Secondly, by enhancing gas-liquid mass transfer efficiency and reaction controllability through the reactor, raw material waste and by-product generation are reduced, making the production process cleaner and more environmentally friendly. At the same time, the output per unit time is significantly increased, balancing environmental protection and production efficiency. Furthermore, the spray-type external circulation reactor has an optimized ejector and circulation pump structure design, resulting in a low failure rate and eliminating the need for frequent replacement of seals. It also exhibits strong long-term operational stability, significantly reducing equipment maintenance costs and downtime losses.

[0030] (2) The method for preparing cyclic vinyl sulfite by external circulation spray gas-liquid contact process, by pre-treating the catalyst with ultrasound before use, makes the catalyst particles more uniformly dispersed and the catalytic active sites fully exposed, effectively solving the problems of uneven catalyst dispersion and low activity utilization in traditional processes, and helping to improve the reaction rate and raw material conversion rate.

[0031] (3) The method for preparing cyclic vinyl sulfite by external circulation spray gas-liquid contact process is to disperse sulfur dioxide through a microporous distributor. The microporous structure expands the gas-liquid contact area and enhances the mass transfer efficiency, so that ethylene oxide reacts more fully with sulfur dioxide, reduces local unreacted raw material residues, and reduces the probability of side reactions.

[0032] (4) The method for preparing cyclic vinyl sulfite by the external circulation spray gas-liquid contact process is to promote the full contact reaction of residual raw materials in the reaction system by adopting an intermittent stirring mode during the aging stage and by circulating "stirring and settling", thereby further improving the raw material conversion rate and reducing the impurity content in the product.

[0033] (5) The method for preparing cyclic vinyl sulfite by external circulation spray gas-liquid contact process adopts a series purification process of macroporous adsorption resin and cation exchange resin to first remove organic impurities and then remove metal ion residues, which precisely solves the problem of incomplete purification by single purification method, so that the product purity can reach up to 99.99%+, which meets the stringent requirements of lithium battery grade. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] Please see Figure 1 This invention provides ten technical solutions:

[0037] Example 1

[0038] A 50L spray-type circulating reactor was used. 5 kg of ethylene carbonate was added as a solvent, along with 25 g of triethylborane and 50 g of triethylamine (catalyst composition molar ratio 0.5:1). After purging with nitrogen three times, 2 kg of ethylene oxide was added, and the reaction mixture was heated. When the reaction temperature reached 120℃, 3 kg of sulfur dioxide was introduced to bring the reaction pressure to 1.0 MPa. As the reaction proceeded, the reaction pressure decreased, and ethylene oxide and sulfur dioxide were added to bring the pressure back to 1.0 MPa. 10.2 kg of ethylene oxide and 15.9 kg of sulfur dioxide were continuously added until the reaction pressure no longer decreased. The reactor was then aged for another 60 minutes, for a total reaction time of 4 hours. The reactor was cooled to 50℃, emptied, and the product was discharged, yielding 30 kg of a mixture of ethylene sulfite and ethylene carbonate. This mixture was then subjected to vacuum distillation to obtain approximately 30 kg of ethylene sulfite, with a selectivity of 99% and a yield of 99%.

[0039] Example 2

[0040] A 50L spray-type external circulation reactor was used. 10 kg of vinyl sulfite was added as a solvent, along with 100 g of a mixed catalyst of triphenylborane and tripropylamine. After purging with nitrogen three times, 2 kg of ethylene oxide was added. The reaction mixture was then heated to 120°C. 3 kg of sulfur dioxide was introduced to bring the reaction pressure to 0.5 MPa. As the reaction proceeded and the pressure decreased, sulfur dioxide was added again to bring the pressure back to 0.5 MPa. 10.2 kg of ethylene oxide and 15.9 kg of sulfur dioxide were continuously added until the reaction pressure no longer decreased. The reactor was then aged for another 60 minutes, for a total reaction time of 4 hours. The reactor was cooled to 50°C, emptied, and the product was discharged, yielding 30 kg of a mixture of vinyl sulfite and ethylene carbonate. This mixture was then subjected to vacuum distillation to obtain approximately 30 kg of vinyl sulfite, with a selectivity of 99.1% and a yield of 99%.

[0041] Example 3

[0042] A 50L spray-type circulating reactor was used. The reaction system included: cyclohexane as solvent (dehydrated to <30ppm water content), triethylaluminum-tetrabutylammonium bromide composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 15 minutes (power 100W) before use, the catalyst dosage was 0.5% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.04:1, and the mass ratio of solvent to ethylene oxide was 3:1.

[0043] Specific reaction process: Under nitrogen protection, cyclohexane, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) are added sequentially to a spray-type external circulation reactor. The air inside the reactor is replaced three times, the spray circulation is started, and the temperature is increased stepwise (2℃ / min) to 110℃. Dehydrated sulfur dioxide is introduced through a microporous distributor (pore size 10μm) to a pressure of 1.2MPa inside the reactor. The reaction is carried out at constant temperature and pressure for 3 hours. After the reaction is completed, the temperature is naturally cooled to below 60℃, the pressure is slowly released, and excess sulfur dioxide is absorbed by alkaline solution. After discharge, the product is purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0044] Test results: Ethylene oxide conversion rate 99.2%, vinyl sulfite selectivity 98.6%, product purity 99.8%, and thermal stability meets the standard (thermal decomposition temperature ≥120℃).

[0045] Example 4

[0046] A 50L spray-type circulating reactor was used. The reaction system included: toluene as solvent (dehydrated to <30ppm water content), triisobutylaluminum-tetrabutylammonium chloride composite catalyst (molar ratio 4:1), the catalyst was pretreated with ultrasound for 12 minutes (90W power) before use, the catalyst dosage was 0.6% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.03:1, and the mass ratio of solvent to ethylene oxide was 3:1.

[0047] Specific reaction process: Under nitrogen protection, toluene, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) are added sequentially to a spray-type external circulation reactor. The air inside the reactor is replaced three times, external circulation is turned on, and the temperature is increased stepwise (2℃ / min) to 115℃. Dehydrated sulfur dioxide is introduced through a microporous distributor (pore size 8μm) to a pressure of 1.3MPa inside the reactor. The reaction is carried out at constant temperature and pressure for 3.5h. After the reaction is completed, the temperature is naturally cooled to below 60℃, the pressure is slowly released, and excess sulfur dioxide is absorbed by alkaline solution. After discharge, the product is purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0048] Test results: Ethylene oxide conversion rate 99.6%, vinyl sulfite selectivity 98.8%, product purity 99.85%, thermal stability meets standards, and there are no obvious byproducts (polyethylene glycol content <0.1%).

[0049] Example 5

[0050] A 50L spray-type circulating reactor was used. The reaction system included: n-heptane as solvent (dehydrated to <30ppm water content), triethylaluminum-benzyltriethylammonium chloride composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 18 minutes (power 110W) before use, the amount of catalyst was 0.5% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.04:1, and the mass ratio of solvent to ethylene oxide was 3:1.

[0051] Specific reaction process: Under nitrogen protection, n-heptane, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) are added sequentially to a spray-type external circulation reactor. The air inside the reactor is replaced three times, and the temperature is increased stepwise (2℃ / min) to 120℃. Dehydrated sulfur dioxide is introduced through a microporous distributor (pore size 12μm) to a pressure of 1.5MPa inside the reactor. The reaction is carried out at constant temperature and pressure for 4 hours. After the reaction is completed, the temperature is naturally cooled to below 60℃, the pressure is slowly released, and excess sulfur dioxide is absorbed by alkaline solution. After discharge, the product is purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0052] Test results: Ethylene oxide conversion rate 99.8%, vinyl sulfite selectivity 99.0%, product purity 99.9%, fully meeting the requirements for lithium battery grade vinyl sulfite.

[0053] Example 6

[0054] A 50L spray-type circulating reactor was used. The reaction system included: cyclohexane as solvent (dehydrated to <30ppm water content), triethylaluminum-tetrabutylammonium bromide composite catalyst (molar ratio 3:1), the catalyst was pretreated with ultrasound for 10 minutes (power 80W) before use, the catalyst dosage was 0.5% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.04:1, and the mass ratio of solvent to ethylene oxide was 2.5:1.

[0055] Specific reaction process: Under nitrogen protection, cyclohexane, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) are added sequentially to a spray-type external circulation reactor. The air inside the reactor is replaced three times, external circulation is turned on, and the temperature is increased stepwise (2℃ / min) to 105℃. Dehydrated sulfur dioxide is introduced through a microporous distributor (pore size 15μm) to a pressure of 1.1MPa inside the reactor. The reaction is carried out at constant temperature and pressure for 3.5h. After the reaction is completed, the temperature is naturally cooled to below 60℃, the pressure is slowly released, and excess sulfur dioxide is absorbed by alkaline solution. After discharge, the product is purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0056] Test results: Ethylene oxide conversion rate 99.0%, vinyl sulfite selectivity 98.5%, product purity 99.7%, thermal stability met the standard, and catalyst amount was reduced by 16.7% compared with Example 1.

[0057] Example 7

[0058] A 50L spray-type circulating reactor was used. The reaction system included: toluene as solvent (dehydrated to <30ppm water content), triethylaluminum-tetrabutylammonium bromide composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 20 minutes (power 120W) before use, the catalyst dosage was 0.7% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.04:1, and the mass ratio of solvent to ethylene oxide was 3:1.

[0059] Specific reaction process: Under nitrogen protection, toluene, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) were added sequentially to a spray-type external circulation reactor. The air inside the reactor was replaced three times, circulation was started, and the temperature was increased stepwise (2℃ / min) to 118℃. Dehydrated sulfur dioxide was introduced through a microporous distributor (pore size 6μm) to a pressure of 1.4MPa inside the reactor. The reaction was carried out at constant temperature and pressure for 3.8h. After the reaction was completed, the temperature was naturally cooled to below 60℃, the pressure was slowly released, and excess sulfur dioxide was absorbed by alkaline solution. After discharge, the product was purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0060] Test results: Ethylene oxide conversion rate 99.7%, vinyl sulfite selectivity 98.9%, product purity 99.88%, and raw material loss rate reduced to below 0.4%.

[0061] Example 8

[0062] A 50L spray-type circulating reactor was used. The reaction system included: n-heptane as solvent (dehydrated to <30ppm water content), triethylaluminum-triethylammonium chloride composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 16 minutes (100W power) before use, the catalyst dosage was 0.5% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.04:1, and the mass ratio of solvent to ethylene oxide was 3.5:1.

[0063] Specific reaction process: Under nitrogen protection, n-heptane, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) were added sequentially to a spray-type external circulation reactor. The air inside the reactor was replaced three times, circulation was started, and the temperature was increased stepwise (2℃ / min) to 112℃. Dehydrated sulfur dioxide was introduced through a microporous distributor (pore size 18μm) to a pressure of 1.3MPa inside the reactor. The reaction was carried out at constant temperature and pressure for 3.2h. After the reaction was completed, the temperature was naturally cooled to below 60℃, the pressure was slowly released, and excess sulfur dioxide was absorbed by alkaline solution. After discharge, the product was purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0064] Test results: Ethylene oxide conversion rate 99.5%, vinyl sulfite selectivity 98.9%, product purity 99.92%, meeting the requirements for lithium battery grade vinyl sulfite; equipment operation is stable, with no material sticking to the wall.

[0065] Example 9

[0066] A 50L spray-type circulating reactor was used. The reaction system included: cyclohexane as solvent (dehydrated to <30ppm water content), triethylaluminum-tetrabutylammonium chloride composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 14 minutes (power 95W) before use, the catalyst dosage was 0.6% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.03:1, and the mass ratio of solvent to ethylene oxide was 2:1.

[0067] Specific reaction process: Under nitrogen protection, cyclohexane, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) were added sequentially to a spray-type external circulation reactor. The air inside the reactor was replaced three times, circulation was started, and the temperature was increased stepwise (2℃ / min) to 110℃. Dehydrated sulfur dioxide was introduced through a microporous distributor (pore size 10μm) to a pressure of 1.2MPa inside the reactor. The reaction was carried out at constant temperature and pressure for 3.6h. After the reaction was completed, the temperature was naturally cooled to below 60℃, the pressure was slowly released, and excess sulfur dioxide was absorbed by alkaline solution. After discharge, the product was purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0068] Test results: Ethylene oxide conversion rate 99.3%, vinyl sulfite selectivity 98.6%, product purity 99.78%, and solvent recovery rate over 95%.

[0069] Example 10

[0070] A 50L spray-type circulating reactor was used. The reaction system included: toluene as solvent (dehydrated to <30ppm water content), triethylaluminum-tetrabutylammonium bromide composite catalyst (molar ratio 5:1), the catalyst was pretreated with ultrasound for 17 minutes (power 105W) before use, the catalyst dosage was 0.7% of the mass of ethylene oxide, the molar ratio of sulfur dioxide to ethylene oxide was 1.2:1, and the mass ratio of solvent to ethylene oxide was 3:1.

[0071] Specific reaction process: Under nitrogen protection, toluene, premixed catalyst, and purified ethylene oxide (dehydrated to <50ppm moisture) are added sequentially to a spray-type external circulation reactor. The air inside the reactor is replaced three times, circulation is started, and the temperature is increased stepwise (2℃ / min) to 115℃. Dehydrated sulfur dioxide is introduced through a microporous distributor (pore size 9μm) to a pressure of 1.2MPa inside the reactor. The reaction is carried out at constant temperature and pressure for 3 hours. After the reaction is completed, the temperature is naturally cooled to below 60℃, the pressure is slowly released, and excess sulfur dioxide is absorbed by alkaline solution. After discharge, the product is purified by vacuum distillation and a series of macroporous adsorption resin and cation exchange resin to obtain vinyl sulfite product.

[0072] Test results: Ethylene oxide conversion rate 99.4%, vinyl sulfite selectivity 98.7%, product purity 99.83%, and reaction cycle shortened by 14.3% compared to Example 2.

Claims

1. A method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process, characterized in that: A spray-type external circulation reactor is used to prepare vinyl sulfite by atomizing and dispersing organic solvents into the gas phases of ethylene oxide and sulfur dioxide under the action of a catalyst, at a reaction pressure of 0.3-5.0 MPa and a reaction temperature of 80-300℃, using sulfur dioxide and alkyl epoxides as raw materials. The specific reaction process is as follows: The catalyst and organic solvent are added to a spray-type external circulation reactor. After the airtightness is verified, nitrogen is purged three to five times. Then, the circulation system and heating system are started. After heating to 80-300℃, ethylene oxide and sulfur dioxide are continuously introduced. The reaction temperature is controlled by the external circulation heating and cooling system. The reaction pressure is controlled within 0.3-5.0MPa by controlling the feed rate of ethylene oxide and sulfur dioxide. After the required amount of ethylene oxide and sulfur dioxide is reached, the feeding is stopped. The reaction temperature is maintained to start aging for 2-5 hours. Then, the temperature is lowered to 60-70℃ and the product is discharged. After discharge, qualified products are obtained by vacuum distillation and resin purification.

2. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The sulfur dioxide and ethylene oxide in the reactants must be strictly dehydrated, and their molar ratio is 1.0-1.5:

1.

3. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The range of organic solvents selected includes: cyclohexane, n-hexane, n-heptane, toluene, xylene, vinyl sulfite, ethylene carbonate, and dimethyl carbonate, and the amount used is 2-4 times the mass of ethylene oxide.

4. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The catalytic system includes triethylaluminum, triethylboron composite system, quaternary ammonium salt-quaternary phosphonium salt, organic amine, metal halide complex, and ionic liquid, with the following selection range: tetrabutylammonium bromide, tetrabutylammonium chloride, tetraethylammonium bromide, tetrabutylphosphonium chloride, tetraphenylphosphonium bromide, triethylaluminum, 1,8-diazabicyclo(5,4,0)undec-7-ene, triethylenediamine, triisopropanolamine, potassium iodide, potassium bromide, sodium bromide, calcium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium tetrafluoroborate.

5. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The reaction process is controlled by a reactor heating system, specifically by a stepped heating method with a heating rate of 1-5°C per minute.

6. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The vacuum distillation specifically involves distilling the crude product at a temperature of 80-90℃ and a pressure of 0.08-0.1MPa to remove light components and catalyst residues. The purity is further improved to 99.99%+ by resin adsorption purification.

7. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The catalyst is pretreated with ultrasound for 10-20 minutes before use, with a pretreatment power of 80-120W.

8. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: When sulfur dioxide is introduced, it is dispersed into the air using a microporous distributor with a pore size of 5-20 μm.

9. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The aging stage employs an intermittent stirring mode, stirring for 15 minutes and then stopping for 5 minutes, repeating this cycle.

10. The method for preparing cyclic vinyl sulfite using an external circulation spray-type gas-liquid contact process according to claim 1, characterized in that: The resin refining process uses a combination of macroporous adsorption resin and cation exchange resin. First, the macroporous adsorption resin removes organic impurities, and then the cation exchange resin removes residual metal ions.

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