Method and device for recycling catalyst in dimethyl sulfoxide synthesis process
By using nitric oxide as a catalyst in the dimethyl sulfoxide production process and through recycling technology, the problem of nitrogen dioxide cannot be recycled is solved, and the effect of reducing costs and improving product purity is achieved.
Patent Information
- Application Number
- CN202311655706.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-05
- Publication Date
- 2025-06-06
AI Technical Summary
During the production process of dimethyl sulfoxide, nitrogen dioxide cannot be recycled as a catalyst, resulting in increased production costs and problems of by-product generation and equipment corrosion.
Nitric oxide is used as a catalyst to control the slight excess of sulfide ether to achieve the recycling of nitric oxide. The method includes using dimethyl sulfide and oxygen as raw materials and nitric oxide as catalysts. After heating and reaction, the catalyst can be recycled through gas-liquid separation, condensation and compression.
The recycling of catalysts is realized, production costs are reduced, by-products are reduced, and the purity of the product and the safety of the equipment are improved.
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Figure CN120097875A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of dimethyl sulfoxide production, and in particular relates to a method and a device for recycling a catalyst in a dimethyl sulfoxide synthesis process. Background Art
[0002] Dimethyl sulfoxide (DMSO) is a sulfur-containing organic compound with high polarity, high boiling point, good thermal stability, aprotic, and miscible with water. It can dissolve in most organic substances such as ethanol and benzene. It is the most soluble organic solvent and is known as the "universal solvent". Dimethyl sulfoxide has a wide range of applications in defense, textiles, chemicals, medicine, electronic information, carbon fiber and other fields.
[0003] At present, dimethyl sulfoxide is mainly produced by catalytic oxidation of dimethyl sulfide. Common oxidation methods include nitric acid oxidation, nitrogen dioxide oxidation and hydrogen peroxide oxidation. Among them, nitric acid oxidation is more corrosive to equipment, and the cost of hydrogen peroxide is higher. Currently, the most commonly used method is nitrogen dioxide oxidation. In order to ensure safety during the production process, an excess of oxygen is used to ensure complete oxidation of sulfide. Therefore, after the reaction, the catalyst still exists in the form of nitrogen dioxide. Nitrogen dioxide has a high solubility in sulfoxide, so this part of nitrogen dioxide cannot be reused. At the same time, because nitrogen dioxide is oxidizing, dimethyl sulfoxide will be slowly oxidized to dimethyl sulfone. In addition, some nitrogen dioxide is converted into nitric acid and lost (the dissolved nitrogen dioxide and nitric acid are measured by the acid value in production). Therefore, the conventional reaction method not only produces a large number of by-products, but also nitrogen dioxide is a one-time consumable, resulting in an increase in production costs.
[0004] At present, in order to reduce the impact of nitrogen dioxide dissolved in dimethyl sulfoxide, a process of degassing followed by neutralization is usually adopted. However, the degassed nitrogen dioxide contains a large amount of nitrogen and cannot be recycled. In order not to pollute the atmosphere, it can only be absorbed by liquid alkali. The residual nitrogen dioxide after degassing is also fixed as sodium nitrate and sodium nitrite after neutralization with liquid alkali, becoming waste salt and unable to be recycled. It also increases the difficulty of product separation, and the introduced metal ions reduce product quality and increase product production costs. Summary of the invention
[0005] The invention provides a method and device for recycling catalyst in the process of synthesizing dimethyl sulfoxide, which can recycle the catalyst nitrogen monoxide without affecting the quality of the product.
[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a method for recycling catalyst in the process of synthesizing dimethyl sulfoxide, comprising the following steps: Dimethyl sulfide and oxygen are used as raw materials, nitric oxide is used as a catalyst, and heating is performed to react; after the reaction is completed, the temperature is lowered and cooled, and then gas-liquid separation is performed, and the gas phase is nitric oxide, which is pressurized after condensation and impurity removal, and then enters the reaction link for recycling; the liquid phase of the gas-liquid separation is neutralized by adding liquid alkali, and then enters the distillation tower for distillation to obtain the finished product dimethyl sulfoxide.
[0007] Furthermore, the molar ratio of dimethyl sulfide to oxygen is 2.1-2.2:1.
[0008] Furthermore, NO and O 2 The flow ratio is 1 / 4~1 / 2.
[0009] Furthermore, the heating temperature is 70° C. or higher.
[0010] Furthermore, after the reaction is completed, the temperature is lowered to below 60° C. to perform gas-liquid separation; the separated gas phase is subjected to three-stage condensation.
[0011] Further, the nitric oxide is pressurized to 0.18~0.25MPa The present invention also relates to a device for recycling catalysts in the process of synthesizing dimethyl sulfoxide, comprising a synthesis reactor, wherein a discharge pipe thereof is connected to a gas-liquid separator after passing through a heat exchanger, a gas phase pipeline of the gas-liquid separator is connected to a condenser, and an outlet of the condenser is connected to a compressor; the device also comprises a nitric oxide buffer tank, which is provided with an exogenous feed pipeline and a discharge pipeline, and the discharge pipeline is connected to the synthesis reactor; and a compressed gas outlet of the compressor is connected to a circulating feed pipeline of the nitric oxide buffer tank.
[0012] Furthermore, flow meters and regulating valves are provided on the external feed pipeline, the circulating feed pipeline and the discharge pipeline.
[0013] Furthermore, the condenser is a three-stage condensing device.
[0014] The present invention has the following beneficial effects: The present invention uses nitric oxide as a catalyst, and during the catalytic process, NO and O 2 Contact reaction to form NO 2 , NO 2 Dissolved in dimethyl sulfoxide and reacted with dimethyl sulfide, oxidizing dimethyl sulfide to dimethyl sulfoxide, and itself was reduced to NO and removed from dimethyl sulfoxide. By controlling the slight excess of sulfide, after complete reaction, NO and O 2 The NO produced by the reaction 2 All of it is consumed and reduced to NO. Since NO is insoluble in dimethyl sulfoxide, the catalyst and the product can be completely separated, and the catalyst can be recycled after simple condensation and compression.
[0015] The present invention uses NO for recycling, and controls the amount of sulfide to be slightly excessive, thereby preventing NO from being oxidized to NO. 2 , NO dissolved in the product sulfoxide 2 The content is extremely low, and in later processing, only a very small amount of liquid alkali is needed to complete the neutralization. The amount of waste salt generated is greatly reduced compared to traditional processes, which facilitates the separation and purification of subsequent products and reduces the output of solid waste.
[0016] The catalyst of the present invention is NO, which is inert to raw materials such as sulfide. There is no danger of reacting with trace amounts of sulfide in the circulation process, and the corrosion to equipment is relatively poor compared with NO. 2 Lighter, simpler to operate, easier to control and safer. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a schematic diagram of the structure of the device for recycling the catalyst in the process of synthesizing dimethyl sulfoxide in Example 1. DETAILED DESCRIPTION
[0018] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.
[0019] Example 1 A method for recycling a catalyst in a process of synthesizing dimethyl sulfoxide comprises the following steps: Dimethyl sulfide and oxygen were used as raw materials, with a feed molar ratio of 2:1. The excess of dimethyl sulfide was set at 0.5%, 1%, 2%, 3%, 5%, 7% and 10%, respectively. Nitric oxide was used as a catalyst with a flow rate of O 2 1 / 4 of the flow rate, dimethyl sulfoxide as the solvent, enters the reactor for reaction at 70°C, and is cooled to 50°C after the reaction. Then, gas-liquid separation is carried out, and the gas phase is nitric oxide, which is compressed and recycled by a compressor after three-stage condensation.
[0020] Sampling was performed to detect the content of each component and the acid value, and the NO loss was calculated. The experimental results are shown in Table 1.
[0021] The acid value determination method is as follows: weigh about 50g of dimethyl sulfoxide product and add it to a conical flask with 100mL of water, add 2-3 drops of phenolphthalein indicator solution, and then titrate with 0.05mol / L KOH standard solution until pink appears and remains unfaded for 30 seconds. At the same time as the determination, a blank test is performed using the same amount of reagent solution without adding the sample according to the same steps as the determination.
[0022] Sample acid value = (V- V1) × C × 56.1 / M; Where: V is the volume of KOH standard solution consumed when titrating the sample, mL; V1—the volume of KOH standard solution consumed in the blank experiment, mL; C—the molar concentration of KOH solution, mol / L; M—sample mass, g.
[0023] Table 1
[0024] It can be seen from Table 1 above that when the excess of sulfide reaches 5%, the loss of NO is reduced to below 0.5%, and the production of the by-product dimethyl sulfoxide is significantly reduced.
[0025] Example 2 A method for recycling a catalyst in a process of synthesizing dimethyl sulfoxide comprises the following steps: Dimethyl sulfide and oxygen were used as raw materials, with a feed molar ratio of 2.1:1, and nitric oxide was used as a catalyst with a flow rate of O 2 1 / 4 of the flow rate enters the reactor for reaction at 30-90℃ (specifically, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ and 90℃ are set respectively). After the reaction is completed, the temperature is cooled and then the gas-liquid separation is carried out. The gas phase is nitric oxide, which is compressed by the compressor for recycling after three-stage condensation.
[0026] Sampling was performed to detect the content of each component and the acid value, and the NO loss was calculated. The experimental results are shown in Table 2.
[0027] Table 2
[0028] It can be seen from Table 2 above that when the reaction temperature reaches 70°C or above, the reaction is completed within 5 to 15 seconds at more than 99%, and the amount of by-product dimethyl sulfone produced is less than 0.5%.
[0029] Example 3 A method for recycling a catalyst in a process of synthesizing dimethyl sulfoxide comprises the following steps: Dimethyl sulfide and oxygen were used as raw materials, with a feed molar ratio of 2.1:1, and nitric oxide was used as a catalyst with a flow rate of O 2 1 / 8~1 / 2 of the flow rate (specific settings are 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2 respectively); enter the reactor for reaction at 70℃, cool down after the reaction, and then separate the gas and liquid. The gas phase is nitric oxide, which is compressed by the compressor for recycling after three-stage condensation.
[0030] Sampling was performed to detect the content of each component and the acid value), and the NO loss was calculated. The experimental results are shown in Table 3.
[0031] Table 3
[0032] From Table 3 above, we can see that the flow rate of NO is 2 When the flow rate is within 1 / 2~1 / 4, the production of by-product dimethyl sulfone is less than 0.5%.
[0033] Example 4 The present invention also relates to a recycling device for synthesizing a dimethyl sulfoxide catalyst, such as Figure 1 As shown, it includes a synthesis reactor 1, whose discharge pipe is connected to a gas-liquid separator 3 after passing through a heat exchanger 2, the gas phase pipeline of the gas-liquid separator 3 is connected to a condenser 4, and the condenser outlet is connected to a compressor 5; the device also includes a nitric oxide buffer tank 6, which is provided with an exogenous feed pipeline and a discharge pipeline, and the discharge pipeline is connected to the synthesis reactor 1; the compressed gas outlet of the compressor 5 is connected to the circulating feed pipeline of the nitric oxide buffer tank. Flow meters and regulating valves are respectively provided on the exogenous feed pipeline, the circulating feed pipeline and the discharge pipeline, so as to facilitate timely understanding and adjustment of the flow conditions of each pipeline. The specific condenser 4 is a three-stage condenser.
[0034] In specific operation, the nitric oxide catalyst enters the nitric oxide buffer tank 6 through the external feed pipeline as the initial feed amount, enters the dimethyl sulfoxide synthesis reactor 1 through the discharge pipeline, reacts with the raw oxygen and dimethyl sulfide, and is cooled by the heat exchanger 2. The nitric oxide is separated from the reaction product by the gas-liquid separator 3, and the nitric oxide enters the condenser 4 through the gas phase pipeline. The dimethyl sulfoxide entrained in the gas phase is condensed by three-stage condensation cooling, and the nitric oxide is purified. The purified nitric oxide is pressurized by the compressor 5 and enters the nitric oxide buffer tank 6 through the circulating feed pipeline for recycling. In the later stage, it is only necessary to replenish the lost nitric oxide through the external feed pipeline.
[0035] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for recycling catalyst in the process of synthesizing dimethyl sulfoxide, It is characterized in that The following steps are involved: Dimethyl sulfide and oxygen are used as raw materials, dimethyl sulfoxide is used as a solvent, and nitric oxide is used as a catalyst, and heating is performed to react; after the reaction is completed, the temperature is lowered and cooled, and then gas-liquid separation is performed, and the gas phase is nitric oxide, which is pressurized after condensation and impurity removal, and then enters the reaction link again for recycling; the liquid phase of the gas-liquid separation is neutralized by adding liquid alkali, and then enters the distillation tower for distillation to obtain the finished dimethyl sulfoxide.
2. The method according to claim 1, Features: The molar ratio of dimethyl sulfide to oxygen is 2.1~2.2:
1.
3. The method according to claim 1, Features: NO and O 2 The flow ratio is 1 / 4~1 / 2.
4. The preparation method according to claim 1, Features: The heating temperature is 70°C or higher.
5. The preparation method according to claim 4, Features: The heating temperature is 70~90℃.
6. The preparation method according to claim 1, Features: After the reaction is completed, the temperature is lowered to below 60°C for gas-liquid separation; the separated gas phase is subjected to three-stage condensation.
7. The preparation method according to any one of claims 1 to 6, Features: Nitric oxide is pressurized to 0.18~0.25MPa.
8. A device for recycling catalyst in the process of synthesizing dimethyl sulfoxide, Features: The device comprises a synthesis reactor (1), wherein a discharge pipe is connected to a gas-liquid separator (3) after passing through a heat exchanger (2), a gas phase pipeline of the gas-liquid separator (3) is connected to a condenser (4), and an outlet of the condenser is connected to a compressor (5); the device also comprises a nitric oxide buffer tank, which is provided with an external source feed pipeline and a discharge pipeline, and the discharge pipeline is connected to the synthesis reactor (1); and a compressed gas outlet of the compressor (5) is connected to a circulating feed pipeline of the nitric oxide buffer tank.
9. The device according to claim 8, Features: The external source feed pipeline, circulating feed pipeline and discharge pipeline are all equipped with flow meters and regulating valves.
10. The device according to claim 8, Features: The condenser (4) is a three-stage condensing device.