A method and system for the continuous production of sodium isethionate

Abstract

The present application relates to a kind of continuously preparing sodium hydroxyethyl sulfonate method and system, the system includes: first reactor, with first sodium bisulfite channel and first ethylene oxide channel;First reaction kettle, the mixed sodium bisulfite and ethylene oxide solution in first reactor flow into the first reaction kettle, the first outlet of first reaction kettle is connected the inlet of first reactor, and the first circulation channel is formed between first reactor and first reaction kettle;Second reactor, with second ethylene oxide channel and the circulation reaction liquid channel of second reaction kettle;Second reaction kettle, the second outlet of first reaction kettle is connected, the inlet of second reaction kettle is connected with the outlet of second reactor, the second outlet of second reaction kettle is also connected with the inlet of second reactor, and the second circulation channel is formed between second reactor and second reaction kettle.The present application can shorten reaction time, improve reaction efficiency.

Description

Technical Field

[0001] This invention relates to the preparation technology of sodium hydroxyethyl sulfonate, and particularly to a method and system for the continuous preparation of sodium hydroxyethyl sulfonate. Background Technology

[0002] Sodium hydroxyethyl sulfonate is the main raw material for the production of coconut oil-based sodium hydroxyethyl sulfonate. This product is also widely used in industries such as electroplating and detergents. It can be used as a detergent for wool products, an intermediate in daily chemical products (such as shampoos and high-end soaps), a raw material for pharmaceuticals, and an intermediate in fine chemical products.

[0003] Currently, sodium hydroxyethyl sulfonate is mainly prepared by the addition reaction of sodium bisulfite with ethylene oxide (EO). The widely used production process involves preparing a 30wt%-40wt% aqueous solution of sodium bisulfite, purging with nitrogen, heating, and then adding ethylene oxide at 60-90℃ to initiate the reaction. The temperature is controlled at 80-100℃, and the pressure at 0-0.3 MPa. After adding a measured amount of ethylene oxide, the mixture is aged at 90-100℃ for 30-120 minutes to obtain a crude sodium hydroxyethyl sulfonate product with a mass concentration of 40%-45%, containing 1.5%-2.0% impurities, mainly ethylene glycol and its derivatives. The presence of these impurities affects the product quality and yield of further synthesis of sodium hydroxyethyl sulfonate derivatives; therefore, it is necessary to reduce the impurity content in the product sodium hydroxyethyl sulfonate.

[0004] Chinese patent application CN 111320558 A discloses a method for synthesizing taurine, which includes an addition reaction of an aqueous sodium bisulfite solution with liquid ethylene oxide to obtain an addition reaction solution containing sodium hydroxyethyl sulfonate. The temperature and pressure of this addition reaction are 20-100℃, 0.5 bar-5 bar, and the reaction time is 10-120 min. In the ethylene oxide process for producing taurine, sodium hydroxyethyl sulfonate is a crucial synthetic intermediate. The byproducts and yield of sodium hydroxyethyl sulfonate significantly affect the ethylene oxide production of taurine. Because the addition reaction solution contains byproducts (mainly ethylene glycol and polyethylene glycol), nanofiltration is used to filter the addition solution, and through continuous filtration, sodium hydroxyethyl sulfonate is ultimately separated from the byproducts. This method significantly increases processing costs and is not an economical approach.

[0005] Chinese patent document CN 102050764 A discloses a method for purifying sodium hydroxyethyl sulfonate. Specifically, it discloses using a freshly prepared 30-40 wt% sodium bisulfite aqueous solution and ethylene oxide as raw materials. The crude product, at 40-45 wt%, is concentrated to 55-60 wt% in a single-effect evaporator at 80-120℃, then further concentrated to 72-75 wt% in a second-effect evaporator at 100-130℃. The concentrated liquid is then fed into a continuous crystallizer for recrystallization at 20-80℃ for 1-6 hours. The crystal slurry is centrifuged, and the solid is sent to the next process. The mother liquor and crystallization residue are recovered. Purification is completed when the ethylene glycol content in the product reaches below 0.1% wt%. This method is also relatively expensive.

[0006] CN109694337B describes an ellipsoidal crystal of sodium hydroxyethyl sulfonate and its preparation method. The method involves adding crude sodium hydroxyethyl sulfonate to water to form a suspension of a certain concentration, then adding a certain proportion of gallic acid as an additive. The mixture is heated to 80–100°C and stirred until dissolved. The sodium hydroxyethyl sulfonate solution is then evaporated and concentrated to a certain degree using a programmed vacuum method. Crystals are then grown for a period of time, and the system is cooled to 10–25°C using a programmed temperature control method. After centrifugation, washing, and drying, ellipsoidal sodium hydroxyethyl sulfonate crystals are obtained. However, this method lacks control over the reaction process of sodium hydroxyethyl sulfonate, and subsequent processing involves the addition of new chemicals, resulting in higher costs.

[0007] Patent CN114436904A provides a method for preparing sodium hydroxyethyl sulfonate using ethylene oxide, comprising the following steps: (1) hydrogenating and / or passivating the interfacial solvent; (2) reacting sodium bisulfite solution with ethylene oxide through the treated interfacial solvent to obtain sodium hydroxyethyl sulfonate; (3) after the reaction, removing excess ethylene oxide with nitrogen, and centrifuging the interfacial solvent and reaction solution for reuse. The main purpose of this method is to avoid the miscibility of ethylene oxide and sodium bisulfite solution, reducing the generation of impurities such as ethylene glycol. However, the use of an interfacial solvent introduces new chemicals, posing certain risks to subsequent use, and simultaneously increasing production costs.

[0008] Patent CN 113801041B discloses a method for preparing sodium hydroxyethyl sulfonate, comprising the following steps: introducing a new eutectic solvent, which has good solubility for both sodium bisulfite and ethylene oxide, but no solubility for the product; firstly, passivating the eutectic solvent with an inhibitor, dissolving sodium bisulfite in the passivated eutectic solvent, and then introducing ethylene oxide into the reaction solution in a certain proportion, causing sodium bisulfite to undergo an addition reaction with ethylene oxide to obtain sodium hydroxyethyl sulfonate. Because the solvent cannot dissolve sodium hydroxyethyl sulfonate, it continuously precipitates out in solid form as the reaction proceeds, without affecting the reuse of the mother liquor. This method solves the problem of ethylene glycol accumulation in the traditional ethylene oxide method, and can directly obtain high-purity solid sodium hydroxyethyl sulfonate. However, it also introduces a new chemical, which will increase production costs accordingly.

[0009] Patent CN112592296B discloses a continuous reaction method for producing sodium hydroxyethyl sulfonate. This method uses an aqueous solution of sodium bisulfite and ethylene oxide as raw materials for an addition reaction. First, a sodium bisulfite aqueous solution of a certain concentration is mixed with ethylene oxide at a certain flow rate, and the mixture enters a first reactor and remains for a period of time. The first-stage reaction solution is then mixed with ethylene oxide at a certain flow rate and enters a second reactor, where it remains for a period of time. This process is repeated in the third and fourth reactors. In the fourth reactor, an acidic substance is added to adjust the pH to 7.0–8.0 before the final product is discharged. However, this method has a long residence time, a lengthy process, complex operation, and low production efficiency.

[0010] Some of the above processes reduce the impurity content in the product sodium hydroxyethyl sulfonate through post-treatment, while others modify the chemical process by adding new chemicals. Some processes involve long residence times and low efficiency, which not only complicates the process but also increases the generation of waste and significantly raises production costs. Therefore, there is an urgent need to find a simpler, more economical production method that produces fewer byproducts and achieves higher yields. Summary of the Invention

[0011] The purpose of this invention is to provide a method and system for the continuous preparation of sodium hydroxyethyl sulfonate, in order to solve the problems of the prior art.

[0012] This invention discloses a system for the continuous preparation of sodium hydroxyethyl sulfonate, comprising: a first reactor having a first sodium bisulfite channel and a first ethylene oxide channel, and capable of controlling the flow rate and reaction temperature between the first sodium bisulfite channel and the first ethylene oxide channel; a first reaction vessel into which a solution of sodium bisulfite and ethylene oxide mixed in the first reactor flows, the first outlet of the first reaction vessel being connected to the inlet of the first reactor, and a first circulation channel being formed between the first reactor and the first reaction vessel; a second reactor having a second ethylene oxide channel and a circulation reaction liquid channel of the second reaction vessel, and capable of controlling the flow rate and reaction temperature between the circulation reaction liquid of the second reaction vessel and the second ethylene oxide channel; and a second reaction vessel connected to a second outlet of the first reaction vessel, the inlet of the second reaction vessel being connected to the outlet of the second reactor, the second outlet of the second reaction vessel also being connected to the inlet of the second reactor, and a second circulation channel being formed between the second reactor and the second reaction vessel.

[0013] According to one embodiment of the system of the present invention, it includes: a first pump connected between a first outlet of a first reactor and an inlet of a first reactor; and a second pump connected between a first outlet of a second reactor and an inlet of a second reactor.

[0014] According to one embodiment of the system of the present invention, the first reactor includes an ethylene oxide feed channel, a sodium bisulfite channel is arranged around the ethylene oxide feed channel, and a cooling water channel is arranged around the sodium bisulfite channel; the pipe wall between the ethylene oxide channel and the sodium bisulfite channel is a permeable pipe wall; one end of the ethylene oxide feed channel is an inlet and the other end is a closed end.

[0015] According to one embodiment of the system of the present invention, the second reactor includes a central ethylene oxide feed channel, a reaction liquid channel is arranged around the ethylene oxide feed channel, and a cooling water channel is arranged around the reaction liquid channel; wherein the pipe wall between the ethylene oxide channel and the reaction liquid channel is a permeable pipe wall; one end of the ethylene oxide feed channel is an inlet and the other end is a closed end.

[0016] According to one embodiment of the system of the present invention, a sodium bisulfite pipe inlet is connected between the first outlet of the first reactor and the inlet of the first pump.

[0017] According to one embodiment of the system of the present invention, the temperature of the first reactor and the second reactor is controlled by cooling water.

[0018] According to one embodiment of the system of the present invention, the permeable tube walls of the first reactor and the second reactor are microporous tube walls.

[0019] This invention discloses a method for the continuous preparation of sodium hydroxyethyl sulfonate, comprising: mixing an aqueous solution of sodium bisulfite with ethylene oxide for reaction, and conducting a first-stage reaction using a first circulation channel formed between a first reactor and a first reaction vessel, wherein the reaction solution circulates with newly added ethylene oxide and sodium bisulfite, and the mixing rate, molar ratio, and reaction temperature of ethylene oxide and sodium bisulfite are continuously controlled during the reaction; the reaction solution generated after circulation in the first circulation channel flows into a second circulation channel formed between a second reactor and a second reaction vessel for a second-stage reaction, wherein ethylene oxide is added for mixing and reaction in the second-stage reaction, and the mixing rate, amount of added ethylene oxide, and reaction temperature are continuously controlled during the reaction.

[0020] In one embodiment of the method according to the present invention, the concentration of the sodium bisulfite aqueous solution is 20-45 wt%, more preferably 30-40 wt%.

[0021] According to one embodiment of the method of the present invention, the molar ratio of sodium bisulfite to ethylene oxide in the first stage reaction is 1.03:1 to 1.1:1.

[0022] According to one embodiment of the method of the present invention, the pH value in the first reaction vessel of the first stage reaction is controlled to be 6.5-7.0.

[0023] According to one embodiment of the method described in this invention, the temperature of the first reactor in the first stage reaction is controlled at 60-70°C.

[0024] According to one embodiment of the method of the present invention, the content of sodium bisulfite in the first reaction vessel of the first stage reaction is 1%-3%.

[0025] According to one embodiment of the method of the present invention, the pH value in the first reaction vessel of the first stage reaction is controlled by adding sodium hydroxide.

[0026] According to one embodiment of the method described in this invention, the reaction liquid in the first reaction vessel of the first stage reaction is circulated more than or equal to 3 times per hour.

[0027] According to one embodiment of the method of the present invention, the reaction liquid in the second reaction vessel of the second stage reaction is circulated more than or equal to 4 times per hour.

[0028] According to one embodiment of the method of the present invention, the reaction temperature in the second reactor of the second stage reaction is 70-75°C.

[0029] According to one embodiment of the method of the present invention, the pH value in the second reaction vessel of the second stage reaction is controlled at 8.0-10.0.

[0030] According to one embodiment of the method of the present invention, the sodium bisulfite content in the second reaction vessel of the second stage reaction is less than 0.05%.

[0031] This invention discloses a method and system for the continuous preparation of sodium hydroxyethyl sulfonate. By employing a reactor and precisely controlling the process flow and parameters, the content of byproducts such as ethylene glycol in the product is effectively reduced. This not only improves the yield of sodium hydroxyethyl sulfonate but also avoids subsequent purification processes, making it more convenient for other applications. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the system principle for the continuous reaction production of sodium hydroxyethyl sulfonate used in this embodiment of the invention;

[0033] Figure 2 This is a schematic diagram of the reactor for the continuous production of sodium hydroxyethyl sulfonate according to the present invention. Detailed Implementation

[0034] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0035] To illustrate the technical effects of the preparation method of the present invention, examples are provided below. Unless otherwise specified, all raw materials used in the following examples are commercially available products, and all methods used are conventional methods. Unless otherwise specified, all material contents refer to mass-volume percentages.

[0036] Figure 1 This is a schematic diagram of the continuous reaction system for producing sodium hydroxyethyl sulfonate used in this embodiment of the invention, including: reactor 1, reactor 2, reaction vessel 3, and reaction vessel 4. Reactor 1 has a sodium bisulfite channel and an ethylene oxide channel, and can control the flow rate and reaction temperature between the sodium bisulfite channel and the ethylene oxide channel. Reactor 2 has a sodium bisulfite channel and an ethylene oxide channel, and can control the flow rate and reaction temperature between the sodium bisulfite channel and the ethylene oxide channel. Reaction vessel 3 has its inlet connected to the outlet of the mixed sodium bisulfite and ethylene oxide solution in reactor 1. A first circulation channel is formed between reactor 1 and reaction vessel 3. The outlet of reaction vessel 4 is connected to another outlet of reaction vessel 3, the inlet of reaction vessel 4 is connected to the outlet of reactor 2, and the outlet of reaction vessel 4 is also connected to the inlet of reactor 2, forming a circulation channel between reactor 2 and reaction vessel 4.

[0037] like Figure 1As shown, the system for the continuous preparation of sodium hydroxyethyl sulfonate includes: a circulation pump 5 connected between the outlet of reactor 3 and the inlet of reactor 1; and a circulation pump 6 connected between the outlet of reactor 4 and the inlet of reactor 2.

[0038] like Figure 1 As shown, the outlet of the reactor 3 is connected to the inlet of the sodium bisulfite pipe between the circulating pump 5 and the outlet of the reactor 3 for solution mixing.

[0039] like Figure 1 As shown, in a preferred embodiment, the other outlet of reactor 3 can supply reaction liquid into reactor 4 through the connected outlet of reactor 4. This allows reactor 4 to pre-solubilize a certain amount of reaction liquid before operation to avoid the system running dry.

[0040] Figure 2 This is a schematic diagram of the reactor for the continuous production of sodium hydroxyethyl sulfonate according to the present invention, as shown below. Figure 2 As shown, taking reactor 1 as an example, the structure of reactor 2 can be referenced from reactor 1. Reactor 1 includes a central ethylene oxide feed channel, with one end being the inlet and the other end being a closed end. A sodium bisulfite channel is located around the ethylene oxide feed channel, and a cooling water channel is located around the sodium bisulfite channel. The wall between the ethylene oxide channel and the sodium bisulfite channel is a permeable wall, which can be a microporous type or other permeable membrane. Reactor 1 also includes: an ethylene oxide inlet, a sodium bisulfite inlet, a cooling water inlet and outlet, and a post-reaction material outlet.

[0041] like Figure 2 As shown, reactor 1 cools down during the reaction of ethylene oxide and raw material sodium bisulfite. At the same time, the use of materials from circulating reactor 1 facilitates the removal of heat from the reaction process. In addition, this reactor is equipped with a cooling device and has a large heat exchange area, enabling temperature control while reacting. This allows for precise temperature control during the reaction process.

[0042] like Figure 2 As shown, preferably, reactor 1 can also be a plate reactor or a tubular reactor, as long as the overall structure meets the requirements for permeation rate control between the ethylene oxide channel and the sodium bisulfite channel, and also meets the temperature control requirements. Specifically, a plate reactor uses plates as heat transfer units, with many plates arranged and pressed together according to a certain rule to form the final reactor. A tubular reactor uses pipes as heat transfer units, with many pipes arranged and combined together according to a certain rule to form the final reactor.

[0043] like Figure 2As shown, reactors 1 and 2 should have the following functions: 1. Two material channels; 2. Cooling function, the cooling function zone mainly removes the heat from the mixing reaction channel zone of ethylene oxide and sodium bisulfite; 3. There are many tiny permeable diffusion distribution pores between the ethylene oxide channel and the sodium bisulfite channel (the reaction liquid channel of reactor 2) to achieve slow and uniform addition of ethylene oxide to the sodium bisulfite channel zone.

[0044] The reactor of this invention enables precise temperature control during the reaction process, solving the problem in existing technologies where ethylene oxide and sodium bisulfite are mixed and reacted before cooling, making precise temperature control impossible during the reaction. This invention avoids the conventional approach of controlling the materials after the reaction is complete. It employs a dedicated reactor, ensuring a full reaction of ethylene oxide and sodium bisulfite while promptly removing heat from the reaction process, thus guaranteeing the optimal reaction outcome.

[0045] like Figure 1 as well as Figure 2 As shown, the production process of the continuous preparation system of sodium hydroxyethyl sulfonate according to the present invention mainly consists of two steps. The first step is the initial reaction, in which a large amount of ethylene oxide reacts. The second step is the finishing reaction, in which a small amount of ethylene oxide is added. In the initial reaction stage, the residual amount of sodium bisulfite is controlled at a constant level of 1%-3%, and the pH value of the reaction stage is controlled at 6.5-7.0. In the second step, the residual amount of sodium bisulfite is controlled to be less than 0.05% by adding a small amount of ethylene oxide, and the pH value after the reaction is 8-10. This effectively ensures that the reaction process is carried out under the condition of excess sodium bisulfite. The reaction temperature is controlled at 60℃-75℃. It should be noted that in the initial reaction, because the material concentration is high and the reaction rate is fast, the reaction temperature can be controlled at a lower level. However, in the finishing reaction stage, because the reactant concentration is very low, in order to prevent the reaction rate from being too slow and the ethylene oxide from accumulating for a long time and causing side reactions, the reaction temperature is appropriately increased in this stage with a small amount of ethylene oxide and a low flow rate, so as to control the reaction at the optimal state of high yield and few side reactions. Furthermore, the residual amount of sodium bisulfite needs to be controlled in the initial reaction stage. Too low a level can easily lead to side reactions in the initial stage, while too high a level requires more ethylene oxide to be added in the final reaction stage. Under alkaline conditions and with a low sodium bisulfite content, ethylene oxide is more prone to side reactions, resulting in excessively high levels of ethylene glycol and other byproducts. This invention can shorten the reaction time, improve reaction efficiency, simplify operation, and ultimately effectively reduce the content of byproducts such as ethylene glycol, thereby increasing the yield of sodium hydroxyethyl sulfonate.

[0046] The specific technical solution of an embodiment of the method for continuous reaction production of sodium hydroxyethyl sulfonate according to the present invention includes:

[0047] An addition reaction is carried out using sodium bisulfite aqueous solution and ethylene oxide as raw materials in a dedicated reactor and process flow. The addition reaction is divided into two stages, specifically including:

[0048] Step 1: Sodium bisulfite is added between the outlet of reactor 1 and the inlet of circulating pump 5. Ethylene oxide is introduced into port a of reactor 1, and an aqueous solution of sodium bisulfite is added to port b of reactor 1 via circulating pump 5. Ethylene oxide is contained within the ethylene oxide channel of reactor 1. The ethylene oxide channel and the sodium bisulfite channel have numerous micropores, ensuring that ethylene oxide slowly and uniformly permeates into the sodium bisulfite channel. This avoids the localized large-scale exothermic reaction caused by the instantaneous mixing of sodium bisulfite and ethylene oxide in conventional reactions, which can lead to side reactions. Simultaneously, this invention connects cooling water to ports d and e of reactor 1, ensuring that the heat generated during the reaction is instantly removed, achieving precise temperature control and enabling micro-level quantitative reactions. In this stage, the feed molar ratio of sodium bisulfite to ethylene oxide is 1.03:1-1.1:1, and the pH in the reactor is controlled at 6.5-7.0, and the temperature at 60-70℃. Furthermore, to ensure that sodium bisulfite is always in excess in the reactor, which is beneficial for the reaction between ethylene oxide and sodium bisulfite and prevents side reactions of ethylene oxide, the material circulation rate in reactor 1 should be greater than 3 times per hour. Specifically, the circulation rate is determined by the amount of material in the reactor; physicochemically, the higher the better, but in actual industrial production, too high a rate is not economically viable, so a suitable circulation ratio (i.e., circulation rate) needs to be selected. Controlling the circulation rate facilitates the mixing of sodium bisulfite raw material with the material in the reactor, ensuring the pH of the material entering the reactor to react with ethylene oxide, further reducing side reactions. Simultaneously, the sodium bisulfite content in reactor 1 needs to be monitored regularly to ensure it is between 1% and 3%. The main influencing factor is the molar ratio of sodium bisulfite to ethylene oxide, so the sodium bisulfite content in reactor 1 can be controlled by fine-tuning the sodium bisulfite flow rate. Additionally, due to the excess sodium bisulfite, the reaction process may result in a pH below 6.5; in this case, sodium hydroxide can be added appropriately to maintain the reaction conditions.

[0049] Step 2: The material from reactor 1 is transferred to reactor 2. Ethylene oxide slowly permeates from the ethylene oxide channel in reactor 2 into the reaction liquid channel. No additional sodium bisulfite is needed in this step, but the flow rate of circulating pump 6 and the flow rate and velocity of added ethylene oxide must be controlled to ensure that the molar amount of ethylene oxide added per unit time is less than the molar amount of sodium bisulfite in the reaction liquid channel of reactor 2 per unit time. To ensure an excess of sodium bisulfite during the reaction, since the amount of sodium bisulfite is relatively small at this stage, the material in reactor 2 can be circulated more than 4 times per hour. Simultaneously, the temperature inside the reactor is controlled at 70-75℃. When the sodium bisulfite content reaches 0.1%-0.2%, the addition of ethylene oxide is stopped. After circulating the reaction for 0.5 hours, the pH in reactor 2 is 8.0-10.0, the sodium bisulfite content is less than 0.05%, the ethylene glycol content is less than 0.05%, and the yield is greater than 99.7%.

[0050] Furthermore, the source of sodium bisulfite in reactor 2 is the amount of sodium bisulfite contained in the material transferred from reactor 1 to reactor 2. If reactor 1 transfers a volume V of material to reactor 2, and the sodium bisulfite content (mass-volume content) is C (1%-3%), then the mass of sodium bisulfite in reactor 2 is: C*V, and the molar amount n of sodium bisulfite per unit time is: n = Q*Cv. The flow rate Q of the circulating pump per unit time and the molar volume concentration Cv of sodium bisulfite in reactor 2 are also given. The molar volume concentration Cv of sodium bisulfite can be obtained by converting the sodium bisulfite content.

[0051] This invention involves reacting sodium bisulfite and ethylene oxide in two stages. The first stage is the main reaction, in which a large amount of ethylene oxide and sodium bisulfite react. The reaction is controlled with an excess of sodium bisulfite, and the large amount of heat released during the reaction can be removed in time, greatly reducing the side reactions of ethylene oxide. In the second stage, a small amount of sodium bisulfite remains, and a small amount of ethylene oxide reacts slowly with a large flow of circulating material. At the same time, the reaction temperature is controlled at a certain level, which ensures the reaction rate and reduces the side reactions of ethylene oxide.

[0052] This invention, through extensive comparative experiments involving sodium bisulfite and ethylene oxide, reveals that ethylene oxide readily hydrolyzes to produce ethylene glycol under both acidic and alkaline conditions. Furthermore, within the same timeframe, higher temperatures result in greater hydrolysis. The reaction of sodium bisulfite with ethylene oxide releases a significant amount of heat, hindering reaction control. However, at lower temperatures, the reaction rate between sodium bisulfite and ethylene oxide slows considerably, preventing large quantities of ethylene oxide from reacting. As the reaction progresses, these unreacted ethylene oxide accumulates in the system and ultimately converts into byproducts such as ethylene glycol. By rationally controlling the sodium bisulfite and pH levels during the reaction, the hydrolysis of ethylene oxide is effectively reduced, resulting in an ethylene glycol content below 0.05%. This system is a continuous reaction process, suitable for industrial production.

[0053] Preferably, the concentration of the sodium bisulfite aqueous solution is 20-45 wt%; more preferably 30-40 wt%.

[0054] Preferably, in the first stage of the reaction, the feed molar ratio of sodium bisulfite to ethylene oxide is 1.03:1 to 1.1:1.

[0055] Preferably, the pH of the first-stage reaction vessel is 6.5-7.0.

[0056] Preferably, the temperature of the reactor in the first stage of the reaction is 60-70°C.

[0057] Preferably, the sodium bisulfite content in the reactor during the first stage of the reaction is 1%-3%.

[0058] Preferably, the pH of the reactor in the first stage of the reaction can be controlled by adding sodium hydroxide when the pH is low.

[0059] Preferably, in the first stage of the reaction, the material in reactor 1 should be circulated more than 3 times per hour.

[0060] Preferably, in the second stage of the reaction, the material in reactor 2 should be circulated more than 4 times per hour.

[0061] Preferably, the temperature of the second-stage reaction in this reactor is 70-75°C.

[0062] Preferably, the pH of the second-stage reaction in this reactor is 8.0-10.0.

[0063] Preferably, the sodium bisulfite content in the reactor for the second stage reaction is less than 0.05%.

[0064] Example 1: Experiments with different sodium bisulfite mass concentrations at different flow rates

[0065] Sodium bisulfite aqueous solutions of different concentrations are added to reactor 1 at a certain flow rate. Simultaneously, ethylene oxide is introduced into reactor 1. The flow rate of ethylene oxide is controlled based on a feed molar ratio of sodium bisulfite to ethylene oxide of 1.05:1. Once the liquid level in reactor 1 reaches a certain level, the circulation pump is turned on, and the pH in reactor 1 is controlled to be 6.5-7.0. If the pH is too low, a small amount of sodium hydroxide can be added to adjust it to a suitable range. The reaction temperature in the reactor is controlled to be 60-70℃. After the material in reactor 1 reaches a certain level, it is discharged into reactor 2. Once the material in reactor 2 reaches a certain level, the circulation pump is turned on, and ethylene oxide is added to reactor 2. Because the amount and concentration of residual sodium bisulfite are relatively small at this stage, less ethylene oxide is required; therefore, the flow rate of ethylene oxide must be strictly controlled to prevent it from being too fast. The reaction temperature in reactor 2 was controlled at 70-75℃. When the sodium bisulfite content reached 0.1%-0.2%, the addition of ethylene oxide was stopped. After circulating the reaction for 0.5 hours, the pH in reactor 2 was 8.0-10.0, and the sodium bisulfite content was less than 0.05%. The experimental data are as follows:

[0066]

[0067]

[0068] Example 2: Comparison of different sodium bisulfite flow rates and ethylene oxide flow rates

[0069] A 40% sodium bisulfite aqueous solution was added to reactor 1 at a certain flow rate. Simultaneously, ethylene oxide was introduced into reactor 1, and the feed flow rate of ethylene oxide was adjusted according to different molar ratios. Once the liquid level in reactor 1 reached a certain level, the circulation pump was turned on, and the pH in reactor 1 was controlled at 6.5–7.0. If the pH was too low, a small amount of sodium hydroxide could be added to adjust it to a suitable range. The reaction temperature in the reactor was controlled at 60–70℃. After the material in reactor 1 reached a certain level, it was discharged into reactor 2. Once the material in reactor 2 reached a certain level, the circulation pump was turned on, and ethylene oxide was added to reactor 2. The reaction temperature in reactor 2 was controlled at 70–75℃. When the sodium bisulfite content reached 0.1%–0.2%, the addition of ethylene oxide was stopped. After circulating the reaction for 0.5 hours, the pH in reactor 2 was 8.0–10.0, and the sodium bisulfite content was less than 0.05%. The experimental data are as follows:

[0070]

[0071] Example 3: Comparison of different reaction temperatures

[0072] A 40% sodium bisulfite aqueous solution was added to reactor 1 at a certain flow rate. Ethylene oxide was fed into reactor 1 at a feed rate controlled according to a sodium bisulfite to ethylene oxide molar ratio of 1.05:1. Once the liquid level in reactor 1 reached a certain level, the circulation pump was turned on, and the pH in the reactor was controlled to be 6.5-7.0. If the pH was too low, a small amount of sodium hydroxide was added to adjust it to a suitable range. Simultaneously, the reaction temperature in the reactor was controlled. After the material in reactor 1 reached a certain level, it was discharged into reactor 2. Once the feed level in reactor 2 reached a certain level, the circulation pump was turned on, and ethylene oxide was added to reactor 2. The reaction temperature in reactor 2 was controlled. When the sodium bisulfite content reached 0.1%-0.2%, the addition of ethylene oxide was stopped. After circulating the reaction for 0.5 hours, the pH in reactor 2 was 8.0-10.0, and the sodium bisulfite content was less than 0.05%. The experimental data are as follows:

[0073]

[0074] Example 4: Comparison of different pH values ​​in reactor 1

[0075] A 40% sodium bisulfite aqueous solution was added to reactor 1 at a certain flow rate. Ethylene oxide was fed into reactor 1 at a feed rate controlled according to a sodium bisulfite to ethylene oxide molar ratio of 1.05:1. Once the liquid level in reactor 1 reached a certain level, the circulation pump was started, and the pH in reactor 1 was controlled at different levels. Simultaneously, the reaction temperature in the reactor was controlled at 60-70℃. After the material in reactor 1 reached a certain level, it was discharged into reactor 2. Once the material in reactor 2 reached a certain level, the circulation pump was started, and ethylene oxide was added to reactor 2. The reaction temperature in reactor 2 was controlled at 70-75℃. When the sodium bisulfite content reached 0.1%-0.2%, the addition of ethylene oxide was stopped. After circulating the reaction for 0.5 hours, the pH in reactor 2 was 8.0-10.0, and the sodium bisulfite content was less than 0.05%. The experimental data are as follows:

[0076]

[0077] As can be clearly seen from the above examples, the method of this invention can significantly improve the yield, significantly reduce by-products, and achieve a more complete reaction. This invention is a simple and efficient chemical process.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] This invention discloses a method and system for the continuous production of sodium hydroxyethyl sulfonate. Based on existing processes, the method optimizes the reaction equipment, process flow, and control parameters, effectively controlling the generation of ethylene oxide byproducts during the reaction stage. The entire process is simple, with a short reaction time and high efficiency. This patented method can control the ethylene glycol content to below 0.05%, and the yield of sodium hydroxyethyl sulfonate is as high as 99.7%. This system is a continuous reaction process, suitable for industrial production.

[0080] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A system for the continuous preparation of sodium hydroxyethyl sulfonate, characterized in that, include: The first reactor has a first sodium bisulfite channel and a first ethylene oxide channel, and is capable of controlling the flow rate and reaction temperature between the first sodium bisulfite channel and the first ethylene oxide channel. The first reaction vessel contains a solution of sodium bisulfite and ethylene oxide mixed in the first reactor. The first outlet of the first reaction vessel is connected to the inlet of the first reactor. A first circulation channel is formed between the first reactor and the first reaction vessel for the main reaction. The second reactor has a second ethylene oxide channel and a circulating reaction liquid channel for the second reactor, and can control the flow rate and reaction temperature between the circulating reaction liquid in the second reactor and the second ethylene oxide channel. The second reactor is connected to the second outlet of the first reactor. The inlet of the second reactor is connected to the outlet of the second reactor. The second outlet of the second reactor is also connected to the inlet of the second reactor. A second circulation channel is formed between the second reactor and the second reactor for fine reaction. The first reactor includes an ethylene oxide feed channel, a sodium bisulfite channel is arranged around the ethylene oxide feed channel, a cooling water channel is arranged around the sodium bisulfite channel, and the pipe wall between the ethylene oxide feed channel and the sodium bisulfite channel of the first reactor is a permeable pipe wall. The second reactor includes a central ethylene oxide feed channel, a reaction liquid channel surrounding the ethylene oxide feed channel, and a cooling water channel surrounding the reaction liquid channel; the pipe wall between the ethylene oxide feed channel and the reaction liquid channel of the second reactor is a permeable pipe wall.

2. The system as described in claim 1, characterized in that, include: The first pump is connected between the first outlet of the first reactor and the inlet of the first reactor. The second pump is connected between the first outlet of the second reactor and the inlet of the second reactor.

3. The system as described in claim 1, characterized in that, The ethylene oxide feed channel of the first reactor has an inlet at one end and a closed end at the other.

4. The system as described in claim 3, characterized in that, The second reactor has an ethylene oxide feed channel with an inlet at one end and a closed end at the other.

5. The system as described in claim 2, characterized in that, A sodium bisulfite pipeline inlet is connected between the first outlet of the first reactor and the inlet of the first pump.

6. The system as described in claim 1, characterized in that, The temperature of both the first and second reactors is controlled by cooling water.

7. The system as described in claim 4, characterized in that, The walls of the permeable tubes in the first and second reactors are microporous.

8. A method for the continuous preparation of sodium hydroxyethyl sulfonate using the system according to any one of claims 1-7, characterized in that, include: Sodium bisulfite aqueous solution is mixed with ethylene oxide and reacted. The first stage reaction is carried out by the first circulation channel formed between the first reactor and the first reaction vessel, so that the reaction solution is circulated and reacted with the newly added ethylene oxide and sodium bisulfite. During the reaction, the mixing rate, molar ratio and reaction temperature of ethylene oxide and sodium bisulfite are continuously controlled. The reaction liquid generated after circulation in the first circulation channel flows into the second circulation channel formed between the second reactor and the second reaction vessel to carry out the second stage reaction. In the second stage reaction, ethylene oxide is added and mixed, and the mixing rate of ethylene oxide, the amount of ethylene oxide added, and the reaction temperature are continuously controlled during the reaction.

9. The method as described in claim 8, characterized in that, The concentration of the sodium bisulfite aqueous solution is 20-45 wt%.

10. The method as described in claim 8, characterized in that, The molar ratio of sodium bisulfite to ethylene oxide in the first stage reaction is 1.03:1 to 1.1:

1.

11. The method as described in claim 8, characterized in that, The pH value in the first reaction vessel of the first stage reaction is controlled at 6.5-7.

0.

12. The method as described in claim 8, characterized in that, The temperature of the first reactor in the first stage of the reaction is controlled at 60-70℃.

13. The method as described in claim 8, characterized in that, The sodium bisulfite content in the first reaction vessel of the first stage reaction is 1%-3%, and the content refers to the mass-volume percentage.

14. The method as described in claim 8, characterized in that, The pH value in the first reaction vessel of the first stage reaction is controlled by adding sodium hydroxide.

15. The method as described in claim 8, characterized in that, In the first stage of the reaction, the reaction liquid in the first reactor circulates at least 3 times per hour.

16. The method as described in claim 8, characterized in that, In the second reaction vessel of the second stage reaction, the reaction liquid circulates at least 4 times per hour.

17. The method as described in claim 8, characterized in that, The reaction temperature in the second reactor during the second stage of the reaction is 70-75℃.

18. The method as described in claim 8, characterized in that, The pH value in the second reaction vessel of the second stage reaction is controlled at 8.0-10.

0.

19. The method as described in claim 8, characterized in that, The sodium bisulfite content in the second reaction vessel of the second stage reaction is less than 0.05%, and the content refers to the mass-volume percentage.

20. The method as described in claim 8, characterized in that, The concentration of the sodium bisulfite aqueous solution is 30-40 wt%.

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