A continuous production process method of dichlorophenyl sulfone

Abstract

This invention belongs to the field of fine chemical synthesis technology, specifically relating to a continuous production process for dichlorosulfonylimide. This invention utilizes a tower-type continuous condensation and physicochemical synergistic defoaming technology to stably control the foam layer height within 25% of the tower diameter without adding any organic defoamers, completely solving the problem of foam runaway in continuous reactions. Combined with three-stage segmented temperature control and online tail gas monitoring closed-loop control, the reaction steady-state determination is accurate, and its batch consistency and process stability are significantly superior to conventional batch or multi-reactor series processes. This invention constructs a quadruple closed-loop recovery system for all materials. Furthermore, the tail gas of this invention is distilled by pressure swing distillation to co-produce ≥99.9% high-purity hydrogen chloride and sulfur dioxide, which are then completely reused, increasing the by-product value by more than three times, reducing the generation of waste gas, wastewater, and solid waste, achieving near-zero tail gas emissions and green, clean production, ensuring safety and reliability.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology, specifically relating to a continuous production process for dichlorosulfonylimide. Background Technology

[0002] Dichlorosulfonylimide (HN(SO2Cl)2) is a key intermediate in the preparation of novel lithium salt electrolytes such as lithium bisfluorosulfonylimide and potassium bisfluorosulfonylimide, and is widely used in high-end fields such as lithium-ion batteries, energy storage batteries, and special electrolytes. Currently, the mainstream production processes in the industry use aminosulfonic acid, thionyl chloride, and chlorosulfonic acid as raw materials, and mostly employ batch reactors or multi-reactor series semi-continuous reactions, which generally suffer from the following technical defects:

[0003] Intermittent or semi-continuous operation results in large batch variations, making it difficult to stably control reaction temperature, residence time, and material ratio, leading to poor product purity consistency and an inability to consistently meet the high purity requirements for lithium battery grade.

[0004] The reaction process easily generates a large amount of foam. Conventional processes rely on the addition of external organic defoamers, which can easily introduce impurities, contaminate products, and increase the difficulty of purification.

[0005] The raw material recovery only recovers thionyl chloride or sulfamic acid, without forming a closed-loop system for the full fraction and all materials. As a result, the raw material utilization rate is low, the total yield is low, and the amount of waste generated is large.

[0006] The exhaust gas treatment often uses multi-stage water / alkali absorption, which can only produce low-concentration hydrochloric acid and crude sulfur dioxide, resulting in low resource utilization rate and low added value of by-products.

[0007] Continuous processes often rely on multiple reactors connected in series, failing to achieve integrated coupling of tower-type continuous reaction, in-situ foam control, full material cascade recovery, and high-purity by-product separation, resulting in insufficient process integration and greening level.

[0008] While existing technologies include continuous tower-type preparation of bis(fluorosulfonyl)imide, continuous multi-stage series production of bis(chlorosulfonyl)imide, and clean batch-type batch production, none of them have achieved systematic process innovations such as in-situ foam control without defoamers, continuous and precise tower-type reaction, closed-loop recovery of all materials, and co-production of high-purity hydrogen chloride and sulfur dioxide by pressure swing distillation. They cannot simultaneously meet the industrial production requirements of high-end lithium battery materials for high purity, high yield, low cost, intrinsic safety, and green and low-carbon production. Summary of the Invention

[0009] The purpose of this invention is to address the existing problems by providing a continuous production process for dichlorosulfonylimide.

[0010] This invention is achieved through the following technical solution:

[0011] A continuous production process for dichlorosulfonyl imide includes the following steps:

[0012] S1, Continuous Condensation Reaction and In-situ Foam Control

[0013] S101. Precise metering and continuous feeding of raw materials:

[0014] The raw materials are fed into independent precision metering buffer tanks at a molar ratio of thionyl chloride: aminosulfonic acid: chlorosulfonic acid = 2.6:1.02:1. After the ratio is stabilized by an online flow closed-loop control system, they are continuously and uniformly fed into a sieve plate tower reactor.

[0015] Chlorosulfonic anhydride ((SO2Cl)2O) is pre-added to the thionyl chloride feed line as an in-situ defoamer, with an addition amount of 0.1~0.5 wt% of the thionyl chloride mass.

[0016] This substance can react directionally with foaming intermediates in the reaction system, inhibiting foam generation from the source, and ultimately transforming into the target product or exhaust gas component.

[0017] S102, segmented temperature-controlled continuous reaction:

[0018] The tower reactor is controlled in three stages using heat transfer oil: the upper stage of the reactor is controlled at 90~100℃, the middle stage at 105~115℃, and the lower stage at 110~120℃.

[0019] The raw materials are gradually and completely reacted by step-by-step heating, and the feed flow rate is interlocked to maintain the steady state of the reaction, avoiding side reactions, raw material gasification and foaming caused by excessive temperature.

[0020] S103, Physical-Chemical Synergistic Self-Defoaming:

[0021] Without adding any organic defoamers, the system employs a synergistic control of static swirl vanes and chlorosulfonic anhydride chemical defoaming.

[0022] Static swirl blades: Removable static swirl blades are installed above each sieve tray. The blade opening ratio is 30~40%, the installation angle is 15~25°, and it is matched with the rising air velocity in the tower of 0.5~1.0m / s. The rotational shear force generated by the tangential airflow is used to mechanically break up the foam and stably control the height of the foam layer within 25% of the tower diameter.

[0023] Chlorosulfonic anhydride chemical foam suppressant: Trace amounts of chlorosulfonic anhydride reduce foam generation at the source, working synergistically with physical foam breaking;

[0024] Self-cleaning design: A nitrogen pulse backflushing device is installed at the top of the tower, which automatically backflushes once a week (backflushing pressure 0.3~0.5MPa, pulse width 1~2s, interval 10~15s, duration 1~2min, to prevent scale buildup and blockage on the blades and achieve long-term stable operation).

[0025] S104. Reaction Steady-State Determination and Safety Protection:

[0026] The molar ratio of hydrogen chloride to sulfur dioxide in the exhaust gas is detected in real time by an online monitoring system. When the ratio is stable at 3.0±0.1 and the flow fluctuation is less than 5%, the reaction is determined to have reached a steady state.

[0027] The entire process is protected by a nitrogen micro-positive pressure seal, which is a gauge pressure of 0.01~0.1MPa. This seal isolates the equipment from moisture in the air and prevents hydrolysis of dichlorosulfonamide, corrosion of equipment by hydrogen chloride, and the risk of fire and explosion.

[0028] Reaction equation:

[0029] NH2SO3H+2SOCl2+ClSO3H→HN(SO2Cl)2+2SO2↑+3HCl↑

[0030] S2, stepped vacuum distillation and closed-loop recovery of all materials

[0031] The continuously reacted effluent enters a stepped vacuum distillation unit to achieve multi-component fractional separation and full-chain recycling:

[0032] S201, First-stage vacuum distillation:

[0033] The temperature is controlled at 100~130℃ and the vacuum degree is -0.095MPa to separate the excess thionyl chloride from the system. The separated thionyl chloride is 100% returned to the feed end of the tower reactor for recycling.

[0034] S202, Cooling crystallization-centrifugation recovery of aminosulfonic acid:

[0035] The residue from the first-stage vacuum distillation was cooled to 20-30°C to allow unreacted aminosulfonic acid to fully crystallize out. Solid-liquid separation was performed using a closed centrifuge. The separated aminosulfonic acid solid was directly returned to the batching system for recycling, with an aminosulfonic acid recovery rate of ≥95%.

[0036] S203, two-stage vacuum distillation:

[0037] The mother liquor obtained by centrifugation is sent to a two-stage vacuum distillation unit to separate the fore fraction and the middle fraction. All of the fore fraction is then recycled back to the tower reactor condensation system for reuse, without generating low-value waste liquid, thus achieving full recovery of the fraction.

[0038] S3, High-vacuum precision distillation purification:

[0039] The material after two-stage vacuum distillation is pumped into a thin-film high-vacuum distillation system (such as a scraped thin-film evaporator or a falling film evaporator). Taking advantage of the very short residence time of the material in the thin-film evaporator, thermal decomposition is avoided. The distillation temperature is controlled at 100~115℃ and the vacuum degree is controlled at 500~800Pa.

[0040] Single distillation: Removes low-boiling-point impurities from the system, and the resulting fore fraction is returned to the condensation system for reuse.

[0041] Secondary distillation: The main fraction is precisely cut to obtain lithium-ion grade dichlorosulfonamide product with a purity of ≥98.7%;

[0042] Triple distillation: The residue in the reactor is monitored in real time by an online refractometer or densitometer to detect the effective components (dichlorosulfonyl imide content). When the content is ≥50%, it is automatically returned to the condensation system for reuse; when it is below 50%, it is disposed of as hazardous waste in accordance with regulations.

[0043] Distillation unit product yield ≥ 92%;

[0044] S4, high-purity byproducts from pressure swing distillation

[0045] The tail gas produced by the condensation reaction (mainly hydrogen chloride and sulfur dioxide) is compressed and pressurized before being sent to a pressure swing distillation system for efficient separation.

[0046] S401, Low-pressure distillation column:

[0047] By controlling the operating pressure to 0.3~0.5MPa, the top temperature to -10~5℃, and the bottom temperature to 40~50℃, high-purity hydrogen chloride byproduct with a purity ≥99.9% is obtained at the top of the column.

[0048] S402, High-pressure distillation column:

[0049] The bottom liquid of the low-pressure distillation column is fed into the high-pressure distillation column, and the operating pressure is controlled at 1.0~1.2MPa, the top temperature is 30~40℃, and the bottom temperature is 70~80℃. High-purity sulfur dioxide by-product with a purity of ≥99.9% is obtained at the top of the column.

[0050] The high-purity hydrogen chloride and high-purity sulfur dioxide obtained from the co-production are directly transported as raw materials to other production units in the plant area, realizing the high-value utilization of by-products and near-zero emissions of exhaust gas.

[0051] The present invention has the following advantages over the prior art:

[0052] 1. This invention utilizes a tower-type continuous condensation and physicochemical synergistic self-defoaming technology to stably control the foam layer height within 25% of the tower diameter without adding any organic defoamers, thus completely solving the problem of foam runaway in continuous reactions. Combined with three-stage segmented temperature control and online tail gas monitoring closed-loop control, the reaction steady-state determination is accurate, and its batch consistency and process stability are significantly superior to conventional batch or multi-reactor series processes.

[0053] 2. This invention constructs a four-stage closed-loop recovery system for all materials. The first stage involves vacuum distillation to recover 100% of thionyl chloride for reuse; cooling crystallization and centrifugation to recover sulfamic acid; and the second stage involves vacuum distillation to condense all the fore- and middle fractions back into the system. Finally, the system is purified by thin-film high-vacuum short-path distillation. The overall utilization rate of raw materials reaches over 98.5%, the total yield is ≥93%, and the purity of the product after thin-film high-vacuum short-path distillation is consistently ≥98.7%, meeting the requirements of high-end applications such as lithium-ion batteries and electronic products. Furthermore, comparative analysis shows that without the complete recovery of the fore- and middle fractions, almost no sulfamic acid is recovered, resulting in a yield reduction of approximately 14.7 percentage points. This fully demonstrates the core role of the closed-loop full-fraction recovery system in improving raw material utilization and reducing waste.

[0054] 3. The present invention produces ≥99.9% high-purity hydrogen chloride and sulfur dioxide through pressure swing distillation of the exhaust gas, and all of them are recycled. The value of by-products is increased by more than 3 times, the generation of waste gas, wastewater, and solid waste is reduced, and near-zero emissions of exhaust gas and green and clean production are achieved, which is safe and reliable. Detailed Implementation

[0055] To further explain the present invention, the following specific embodiments are described.

[0056] Example 1

[0057] A continuous production process for dichlorosulfonyl imide includes the following steps:

[0058] S1. Continuous condensation reaction and in-situ foam control:

[0059] According to the molar ratio of thionyl chloride: aminosulfonic acid: chlorosulfonic acid = 2.6:1.02:1, the three raw materials are respectively transported to independent precision metering buffer tanks. After the ratio is stabilized by the online flow closed-loop control system, they are continuously and uniformly fed into the sieve plate tower reactor.

[0060] Chlorosulfonic anhydride ((SO2Cl)2O) was pre-added to the thionyl chloride feed line as an in-situ defoaming agent at an amount of 0.1 wt% of the thionyl chloride mass.

[0061] The tower reactor is controlled in three stages using heat transfer oil: the upper stage of the reactor is controlled at 90-95℃, the middle stage at 105-108℃, and the lower stage at 110-113℃.

[0062] Each sieve tray is equipped with detachable static swirl blades with an opening rate of 30% and an installation angle of 15°. The rising gas velocity inside the tower is controlled at 0.5~0.6m / s.

[0063] A nitrogen pulse backflushing device is installed at the top of the tower, with a backflushing pressure of 0.3 MPa, a pulse width of 1 second, an interval of 15 seconds, and a duration of 1 minute. It automatically backflushes once a week.

[0064] The molar ratio of hydrogen chloride to sulfur dioxide in the exhaust gas is detected in real time by an online monitoring system. When the ratio is stable at 3.0±0.1 and the flow fluctuation is less than 5%, the reaction is determined to have reached a steady state.

[0065] The entire process is protected by a nitrogen micro-positive pressure seal, where the micro-positive pressure is a gauge pressure of 0.01 MPa.

[0066] S2, stepped vacuum distillation and closed-loop recovery of all materials:

[0067] The continuously reacted effluent enters the stepped vacuum distillation unit. The first-stage vacuum distillation is controlled at a temperature of 100~110℃ and a vacuum degree of -0.095MPa to separate out excess thionyl chloride. The separated thionyl chloride is 100% returned to the feed end of the tower reactor for recycling.

[0068] The residue from the first-stage vacuum distillation is cooled to 20-30°C to allow unreacted aminosulfonic acid to fully crystallize out. A closed centrifuge is then used for solid-liquid separation, and the separated aminosulfonic acid solid is directly returned to the batching system for recycling.

[0069] The mother liquor obtained by centrifugation is sent to a two-stage vacuum distillation unit to separate the fore fraction and the middle fraction, and all of it is refluxed back to the tower reactor condensation system for reuse.

[0070] S3, High-vacuum precision distillation purification:

[0071] The material after two-stage vacuum distillation is pumped into a scraped film evaporator system, and the distillation temperature is controlled at 100~105℃ and the vacuum degree at 500~600Pa.

[0072] Low-boiling-point impurities in the system are removed by a single distillation, and the resulting fore fraction is returned to the condensation system for reuse.

[0073] Secondary distillation precisely cuts the main fraction to obtain lithium-ion grade dichlorosulfonyl imide product;

[0074] The residue from the triple distillation vessel is monitored in real time by an online refractometer to detect the effective components. When the content is ≥50%, it is automatically returned to the condensation system for reuse; when it is below 50%, it is disposed of as hazardous waste in accordance with regulations.

[0075] S4, high-purity byproducts from pressure swing distillation

[0076] The tail gas produced by the condensation reaction is compressed and pressurized before being sent to a pressure swing distillation system for efficient separation.

[0077] The low-pressure distillation column operates at a pressure of 0.3 MPa, a top temperature of -10 to 0°C, and a bottom temperature of 40 to 45°C, yielding high-purity hydrogen chloride as a byproduct at the top.

[0078] The high-pressure distillation column operates at a pressure of 1.0 MPa, a top temperature of 30~33℃, and a bottom temperature of 70~75℃, yielding high-purity sulfur dioxide as a byproduct at the top.

[0079] Example 2

[0080] A continuous production process for dichlorosulfonyl imide includes the following steps:

[0081] S1. Continuous condensation reaction and in-situ foam control:

[0082] According to the molar ratio of thionyl chloride: aminosulfonic acid: chlorosulfonic acid = 2.6:1.02:1, the three raw materials are respectively transported to independent precision metering buffer tanks. After the ratio is stabilized by the online flow closed-loop control system, they are continuously and uniformly fed into the sieve plate tower reactor.

[0083] Chlorosulfonic anhydride ((SO2Cl)2O) was pre-added to the thionyl chloride feed line as an in-situ defoaming agent at an amount of 0.3 wt% of the thionyl chloride mass.

[0084] The tower reactor is controlled in three stages using heat transfer oil. The upper stage of the reactor is controlled at 94~98℃, the middle stage at 108~112℃, and the lower stage at 114~118℃.

[0085] Each sieve tray is equipped with detachable static swirl blades with an opening rate of 35% and an installation angle of 20°. The rising gas velocity inside the tower is controlled at 0.7~0.8m / s.

[0086] A nitrogen pulse backflushing device is installed at the top of the tower, with a backflushing pressure of 0.4 MPa, a pulse width of 1.5 s, an interval of 12 s, and a duration of 1.5 min. It automatically backflushes once a week.

[0087] The molar ratio of hydrogen chloride to sulfur dioxide in the exhaust gas is detected in real time by an online monitoring system. When the ratio is stable at 3.0±0.1 and the flow fluctuation is less than 5%, the reaction is determined to have reached a steady state.

[0088] The entire process is protected by a nitrogen micro-positive pressure seal, where the micro-positive pressure is a gauge pressure of 0.05 MPa.

[0089] S2, stepped vacuum distillation and closed-loop recovery of all materials:

[0090] The continuously reacted effluent enters the stepped vacuum distillation unit. The first-stage vacuum distillation is controlled at a temperature of 110~120℃ and a vacuum degree of -0.095MPa to separate out excess thionyl chloride. The separated thionyl chloride is 100% returned to the feed end of the tower reactor for recycling.

[0091] The residue from the first-stage vacuum distillation is cooled to 24-27°C to allow unreacted aminosulfonic acid to fully crystallize out. A closed centrifuge is then used for solid-liquid separation, and the separated aminosulfonic acid solid is directly returned to the batching system for recycling.

[0092] The mother liquor obtained by centrifugation is sent to a two-stage vacuum distillation unit to separate the fore fraction and the middle fraction, and all of it is refluxed back to the tower reactor condensation system for reuse.

[0093] S3, High-vacuum precision distillation purification:

[0094] The material after two-stage vacuum distillation is pumped into a scraped thin-film evaporator system, and the distillation temperature is controlled at 106~110℃ and the vacuum degree at 650~700Pa.

[0095] Low-boiling-point impurities in the system are removed by a single distillation, and the resulting fore fraction is returned to the condensation system for reuse.

[0096] Secondary distillation precisely cuts the main fraction to obtain lithium-ion grade dichlorosulfonyl imide product;

[0097] The residue from the triple distillation vessel is monitored in real time by an online refractometer to detect the effective components. When the content is ≥50%, it is automatically returned to the condensation system for reuse; when it is below 50%, it is disposed of as hazardous waste in accordance with regulations.

[0098] S4, high-purity byproducts from pressure swing distillation

[0099] The tail gas produced by the condensation reaction is compressed and pressurized before being sent to a pressure swing distillation system for efficient separation.

[0100] The low-pressure distillation column operates at a pressure of 0.4 MPa, a top temperature of -5 to 3°C, and a bottom temperature of 43 to 48°C, yielding high-purity hydrogen chloride as a byproduct at the top.

[0101] The high-pressure distillation column operates at a pressure of 1.1 MPa, a top temperature of 33~37℃, and a bottom temperature of 73~78℃, yielding high-purity sulfur dioxide as a byproduct at the top.

[0102] Example 3

[0103] A continuous production process for dichlorosulfonyl imide includes the following steps:

[0104] S1. Continuous condensation reaction and in-situ foam control:

[0105] According to the molar ratio of thionyl chloride: aminosulfonic acid: chlorosulfonic acid = 2.6:1.02:1, the three raw materials are respectively fed to independent precision metering buffer tanks. After the ratio is stabilized by the online flow closed-loop control system, they are continuously and uniformly fed into the sieve plate tower reactor.

[0106] Chlorosulfonic anhydride ((SO2Cl)2O) was pre-added to the thionyl chloride feed line as an in-situ defoamer, at a dosage of 0.5 wt% of the thionyl chloride mass.

[0107] The tower reactor is controlled in three stages using heat transfer oil: the upper stage of the reactor is controlled at 97~100℃, the middle stage at 112~115℃, and the lower stage at 117~120℃.

[0108] Each sieve tray is equipped with detachable static swirl blades with an opening rate of 40% and an installation angle of 25°. The rising gas velocity inside the tower is controlled at 0.9~1.0m / s.

[0109] A nitrogen pulse backflushing device is installed at the top of the tower. The backflushing pressure is 0.5MPa, the pulse width is 2s, the interval is 10s, and the duration is 2min. It automatically backflushes once a week.

[0110] The molar ratio of hydrogen chloride to sulfur dioxide in the exhaust gas is detected in real time by an online monitoring system. When the ratio is stable at 3.0±0.1 and the flow fluctuation is less than 5%, the reaction is determined to have reached a steady state.

[0111] The entire process is protected by a nitrogen micro-positive pressure seal, where the micro-positive pressure is a gauge pressure of 0.1 MPa.

[0112] S2, stepped vacuum distillation and closed-loop recovery of all materials:

[0113] The continuously reacted effluent enters the stepped vacuum distillation unit. The first-stage vacuum distillation is controlled at a temperature of 120~130℃ and a vacuum degree of -0.095MPa to separate out excess thionyl chloride. The separated thionyl chloride is 100% returned to the feed end of the tower reactor for recycling.

[0114] The residue from the first-stage vacuum distillation is cooled to 27-30°C to allow unreacted aminosulfonic acid to fully crystallize out. A closed centrifuge is then used for solid-liquid separation, and the separated aminosulfonic acid solid is directly returned to the batching system for recycling.

[0115] The mother liquor obtained by centrifugation is sent to a two-stage vacuum distillation unit to separate the fore fraction and the middle fraction, and all of it is refluxed back to the tower reactor condensation system for reuse.

[0116] S3, High-vacuum precision distillation purification:

[0117] The material after two-stage vacuum distillation is pumped into a scraped thin-film evaporator system, and the distillation temperature is controlled at 111~115℃ and the vacuum degree is 700~800Pa.

[0118] Low-boiling-point impurities in the system are removed by a single distillation, and the resulting fore fraction is returned to the condensation system for reuse.

[0119] Secondary distillation precisely cuts the main fraction to obtain lithium-ion grade dichlorosulfonyl imide product;

[0120] The residue from the triple distillation vessel is monitored in real time by an online refractometer to detect the effective components. When the content is ≥50%, it is automatically returned to the condensation system for reuse; when it is below 50%, it is disposed of as hazardous waste in accordance with regulations.

[0121] S4, high-purity byproducts from pressure swing distillation

[0122] The tail gas produced by the condensation reaction is compressed and pressurized before being sent to a pressure swing distillation system for efficient separation.

[0123] The low-pressure distillation column operates at a pressure of 0.5 MPa, a top temperature of 0~5℃, and a bottom temperature of 45~50℃, yielding high-purity hydrogen chloride as a byproduct at the top.

[0124] The high-pressure distillation column operates at a pressure of 1.2 MPa, a top temperature of 37~40℃, and a bottom temperature of 77~80℃, yielding high-purity sulfur dioxide as a byproduct at the top.

[0125] Comparative Example 1: A batch reactor process was used, without a continuous condensation reaction.

[0126] A conventional 500L reactor was used. Aminosulfonic acid and chlorosulfonic acid were added in a single batch. After heating to 95°C, thionyl chloride was added dropwise over approximately 4 hours. After the addition was complete, the reaction was maintained at 110°C for another 6 hours. During the reaction, a large amount of foam was generated, requiring manual stirring every 30 minutes to remove the bubbles, and the addition of 0.5 wt% silicone defoamer to control the foam. After the reaction, the temperature was lowered to 25°C to crystallize. Aminosulfonic acid was separated by centrifugation, and the mother liquor was subjected to intermittent vacuum distillation to obtain the dichlorosulfonylimide product. The entire process was conducted without nitrogen-sealed protection.

[0127] Comparative Example 2: Continuous process but without the use of chlorosulfonic anhydride for defoaming, only physical defoaming was employed.

[0128] The same continuous sieve plate tower reactor and process parameters as in Example 2 were used, but chlorosulfonic anhydride was not added as an in-situ defoamer; physical defoaming was achieved solely through static swirl blades. The remaining steps were the same as in Example 2.

[0129] Comparative Example 3: Continuous process but without gradient closed-loop recovery, fractions were not recycled.

[0130] The same continuous sieve tray reactor and process parameters as in Example 2 were used, but the fore- and middle fractions obtained from the secondary vacuum distillation in S2 were not returned to the condensation system as recycled materials, but were collected and treated separately as waste liquid. The remaining operations were the same as in Example 2.

[0131] Comparative Example 4: No nitrogen micro-positive pressure sealing protection was used.

[0132] The same continuous process parameters as in Example 2 were used, but nitrogen micro-positive pressure sealing protection was not used throughout the process, and the reactor and piping system were in direct contact with air. The remaining operations were the same as in Example 2.

[0133] Performance testing

[0134] (1) Purity test of dichlorosulfonamide product:

[0135] Gas chromatography (based on the method "Determination of Purity of Dichlorosulfonamide by Gas Chromatography" established by Haohan Chromatography (Shandong) Application Technology Development Co., Ltd.) was used for detection. The product purity was calculated using the area normalization method, and the average value was taken from three parallel determinations.

[0136] (2) Distillation unit yield:

[0137] Calculate using the following formula:

[0138]

[0139] (3) Aminosulfonic acid recovery rate:

[0140] The ratio of the recovered solid aminosulfonic acid to the amount that should be recovered after the theoretical consumption of the reaction is multiplied by 100%.

[0141] (4) Foam layer height:

[0142] A scale was set at the observation window of each tray in the sieve plate tower reactor. After 4 hours of continuous and stable operation, the height of the foam layer was recorded every 10 minutes, and the average value was taken as a percentage of the diameter of that section of the tower.

[0143] (5) Purity of hydrogen chloride byproduct:

[0144] Following the methods specified in GB / T 14602-2014, the main content was determined using the gas chromatography-thermal conductivity detector differential method, and moisture content was determined using the electrolysis method or the dew point method. The average value was taken from three determinations.

[0145] (6) Purity of sulfur dioxide by-product:

[0146] The determination was performed according to the methods specified in GB / T 3637-2021. The main content was determined by iodometric titration, moisture by Karl Fischer titration, and sulfate by ion chromatography. The average value was taken from three determinations.

[0147] The test results are shown in the table below.

[0148] Table 1 Performance comparison of each embodiment and comparative example

[0149] Example 1 98.7 92.5 95.2 23 99.92 99.91 Example 2 98.9 93.2 96.5 20 99.94 99.93 Example 3 98.8 92.8 96.0 22 99.91 99.90 Comparative Example 1 95.5 75.3 — 65 — — Comparative Example 2 97.0 82.1 94.8 48 — — Comparative Example 3 94.8 78.5 Unrecycled 22 — — Comparative Example 4 94.5 80.2 95.0 21 — —

[0150] As shown in Table 1 above, Examples 1-3 can stably produce lithium-ion grade dichlorosulfonamide, with product purity ≥98.7%, distillation unit yield ≥92%, aminosulfonic acid recovery rate ≥95%, foam layer height controlled within 25% of the tower diameter, and by-product HCl and SO2 purity ≥99.9%. This indicates that the continuous process parameter window proposed in this invention is wide, highly adaptable, and has excellent technical effects.

[0151] Compared to Comparative Example 2, the continuous process of this invention improves product purity by approximately 1.9 percentage points and yield by approximately 18 percentage points, and eliminates the need for silicone defoamers, thus avoiding product contamination. This demonstrates that the continuous tower reaction combined with in-situ foam control is significantly superior to the batch process.

[0152] In Comparative Example 2, relying solely on physical swirl vanes, the foam height reached 48% of the tower diameter, exceeding the control target, and the yield decreased by approximately 11 percentage points, resulting in poor continuous operation stability. This indicates that the synergistic effect of chemical foam suppression by chlorosulfonic anhydride and physical foam breaking by static swirl vanes is key to achieving effective foam control and ensuring steady-state production.

[0153] In Comparative Example 3, the fraction was not recycled, and the complete recovery of the fore- and middle fractions was not achieved. As a result, almost no aminosulfonic acid was recovered, leading to a yield reduction of approximately 14.7 percentage points. This demonstrates that a closed-loop full-fraction recovery system is crucial for improving feedstock utilization and reducing emissions of waste gas, wastewater, and solid waste.

[0154] Comparative Example 4, without nitrogen micro-positive pressure sealing, resulted in a product purity of 94.5%, indicating that nitrogen micro-positive pressure sealing plays a crucial role in isolating moisture and preventing hydrolysis.

[0155] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A continuous production process for dichlorosulfonyl imide, characterized in that, Includes the following steps: S1. Thionyl chloride, aminosulfonic acid, and chlorosulfonic acid are continuously fed into a sieve plate tower reactor according to a molar ratio, and the tower reactor is subjected to three-stage temperature control using heat transfer oil. S2. The reaction product obtained in step S1 is subjected to first-stage vacuum distillation to separate excess thionyl chloride and recycled back to S1; cooling and crystallization-centrifugation to recover unreacted aminosulfonic acid and recycled back to S1; and second-stage vacuum distillation to separate the fore fraction and middle fraction and recycled back to S1. S3. The material processed in step S2 is fed into a thin-film high-vacuum distillation system and distilled three times in sequence at a temperature of 100~115℃ and a vacuum of 500~800Pa to obtain the dichlorosulfonamide product.

2. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S1, the molar ratio of thionyl chloride, aminosulfonic acid, and chlorosulfonic acid is 2.6:1.02:

1.

3. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S1, chlorosulfonic anhydride is added to the thionyl chloride feed line as an in-situ defoamer, with an addition amount of 0.1~0.5wt% of the mass of thionyl chloride. Static swirl vanes are installed above each sieve tray in the tower reactor to achieve physical-chemical synergistic defoaming by utilizing the rotational shear force of the airflow in conjunction with chlorosulfonic anhydride. The static swirl blades have an opening ratio of 30-40% and an installation angle of 15-25°, which matches the rising gas velocity inside the tower of 0.5-1.0 m / s, and controls the height of the foam layer to within 25% of the tower diameter. The top of the sieve plate tower reactor is equipped with a nitrogen pulse backflushing device. The backflushing pressure is 0.3~0.5MPa, the pulse width is 1~2s, the interval is 10~15s, the duration is 1~2min, and it automatically backflushes once a week.

4. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S1, the three-segment temperature control process is as follows: upper segment 90~100℃, middle segment 105~115℃, and lower segment 110~120℃.

5. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S1, the molar ratio of hydrogen chloride to sulfur dioxide is monitored in real time by an online monitoring system. When the ratio is stable at 3.0±0.1 and the flow rate fluctuation is less than 5%, the reaction is determined to have reached a steady state. The entire process is protected by nitrogen micro-positive pressure sealing, where the micro-positive pressure is a gauge pressure of 0.01~0.1 MPa.

6. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S2, the temperature of the first-stage vacuum distillation is 100~130℃, the vacuum degree is -0.095MPa, and the separated thionyl chloride is 100% returned to S1 for recycling. The cooling and crystallization temperature is 20~30℃.

7. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, In step S3, the three distillations are performed sequentially as follows: the first distillation removes low-boiling-point impurities and the fore fraction is recycled back to S1; the second distillation is used to cut the dichlorosulfonamide product; and the third distillation is performed and the amount of effective components in the residue is determined to be recycled back to S1 or disposed of as hazardous waste.

8. The continuous production process of dichlorosulfonylimide according to claim 7, characterized in that, In step S3, the thin-film high-vacuum distillation system is a scraped-film evaporator or a falling-film evaporator; in the tertiary distillation, the content of dichlorosulfonamide in the residue is monitored in real time using an online refractometer or densitometer. When the content is ≥50%, it is automatically returned to S1 for recycling; when it is below 50%, it is disposed of as hazardous waste.

9. The continuous production process of dichlorosulfonylimide according to claim 1, characterized in that, It also includes S4, which compresses the tail gas generated by the condensation reaction of S1 and sends it to the pressure swing distillation system. The hydrogen chloride byproduct is obtained by separation in a low-pressure distillation column, and the sulfur dioxide byproduct is obtained by separation in a high-pressure distillation column.

10. The continuous production process of dichlorosulfonylimide according to claim 9, characterized in that, The low-pressure distillation column operates at a pressure of 0.3~0.5MPa, a top temperature of -10~5℃, and a bottom temperature of 40~50℃; the high-pressure distillation column operates at a pressure of 1.0~1.2MPa, a top temperature of 30~40℃, and a bottom temperature of 70~80℃.

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