Production system and preparation method of dimethyl sulfoxide

Abstract

The invention discloses a method for synthesizing dimethyl sulfoxide, and particularly relates to a production system and a preparation method of dimethyl sulfoxide by taking dimethyl sulfide, oxygen and nitrogen dioxide as raw materials. Dimethyl sulfoxide is added into the oxidation reactor until overflowing and discharging are carried out, and the dimethyl sulfoxide is used as a reactor bottom material for material circulation and temperature control; continuing to add dimethyl sulfoxide to a specified liquid level of the stripping tower kettle, and starting the tower kettle to heat to a specified temperature; quantitatively adding nitrogen dioxide into the oxidation reactor until the pressure of a reaction system is stable; dimethyl sulfide and oxygen are continuously metered and fed, and dimethyl sulfoxide is continuously metered and discharged. The systematic production method provided by the invention realizes closed-loop use of nitrogen dioxide in a reaction system, the nitrogen dioxide loss in the production process is greatly reduced, the output of waste salt in the production process is also reduced, the reaction process is simple and convenient to control and safe to operate, and the method is suitable for upgrading and reconstruction of existing similar production processes.

Description

Technical Field

[0001] The invention discloses a method for synthesizing dimethyl sulfoxide, and particularly relates to a production system and a preparation method for dimethyl sulfoxide using dimethyl sulfide, oxygen and nitrogen dioxide as raw materials. Background Art

[0002] Dimethyl sulfoxide (DMSO) is a widely used sulfur-containing organic compound with the characteristics of high polarity, aproticity, and miscibility with water. It can be used as an organic solvent, reaction medium, and organic synthesis intermediate. It can also be used as a dyeing solvent, de-dyeing agent, dyeing carrier for synthetic fibers, and an absorbent for recovering acetylene and sulfur dioxide. It can also be added as an active ingredient in certain drugs.

[0003] The mainstream production process of the dimethyl sulfoxide industry is the liquid phase emulsified oxidation process with dimethyl sulfide, nitrogen dioxide and oxygen as the main raw materials. In this process, the tail gas nitrogen dioxide and oxygen are absorbed and recycled by dimethyl sulfoxide, and the production tail gas is absorbed and discharged by alkali solution. The utilization rate of nitrogen dioxide is low, and the nitrate and nitrite generated by the lost nitrogen dioxide are prone to safety hazards during the recovery process. With the continuous improvement of the concepts of green development, energy conservation, emission reduction and intrinsic safety, improving the utilization rate of oxidants and reducing the discharge of three wastes are major challenges facing the industry. Summary of the invention

[0004] The object of the present invention is to provide a production system and a preparation method of dimethyl sulfoxide, which can make the consumption of dimethyl sulfide and oxygen as raw materials close to the theoretical amount and the loss of nitrogen dioxide in the reaction process close to zero.

[0005] To achieve the above purpose, the present invention adopts the following technical solution:

[0006] A production system of dimethyl sulfoxide comprises a feed pump 1, a circulation pump 2, a heat exchanger 4, a reactor 13 and a distillation tower 17, wherein the circulation pump 2, the heat exchanger 4 and the reactor 13 are sequentially connected in series to form a closed loop, and the feed pump 1 is connected to a pipeline between the reactor 13 and the circulation pump 2 through a pipeline, an oxygen metering inlet 7, a nitrogen inlet 8, a nitrogen dioxide metering inlet 9, an ejector 10, a venting port 11 and a liquid overflow port 12 are arranged at the upper end of the reactor 13, and the ejector 10 is connected to an output gas phase pipeline 23 at the upper end of the distillation tower 17, and the liquid overflow port 12 is connected to an input pipeline 24 at the upper end of the distillation tower 17.

[0007] A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially provided on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction, a second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 13, and a sampling port 16, a third temperature sensor and a third pressure sensor are sequentially provided on the pipeline between the reactor 13 and the circulation pump 2 along the material flow direction.

[0008] The heat exchanger 4 is provided with a first heat exchange medium inlet 5 at one end and a first heat exchange medium outlet 6 at the other end.

[0009] The reactor 13 is provided with an insulation jacket 25 outside, and a second heat exchange medium inlet 14 is provided on one side of the insulation jacket 25, and a second heat exchange medium outlet 15 is provided on the other side. A second pressure sensor is provided at the upper end of the reactor 13.

[0010] A liquid distributor 22 is provided inside the upper end of the distillation tower 17, and the input pipeline 24 is connected to the liquid distributor 22. A heat exchange pipeline is provided inside the lower end of the distillation tower 17, and a third heat exchange medium inlet 18 connected to the heat exchange pipeline is provided on one side of the lower end shell of the distillation tower 17, and a third heat exchange medium outlet 19 connected to the heat exchange pipeline is provided on the other side. A discharge pipeline is provided at the lower end of the distillation tower 17, and a cooler 22 and a metering discharge pump 21 are sequentially provided on the discharge pipeline.

[0011] A method for preparing dimethyl sulfoxide using the production system, wherein dimethyl sulfoxide (bottom material) is added to a reactor 13 by a metering pump 1 through a heat exchanger until the material overflows and is used as the bottom material of the reactor for material circulation and temperature control;

[0012] In addition, the valve of the liquid overflow port 12 of the reactor 13 is opened, and dimethyl sulfoxide is continuously added to flow into the stripping tower kettle, and nitrogen dioxide is simultaneously added into the reactor until the pressure of the reaction system is stable;

[0013] After the pressure in the reactor is stabilized, the reaction raw material dimethyl sulfide is continuously added to the reactor through a heat exchanger. At this time, oxygen is also introduced, and a liquid-phase oxidation reaction is carried out in the reactor under closed conditions. The product after the reaction is separated by distillation to obtain dimethyl sulfoxide, and the oxidation product nitrogen dioxide is recycled under closed reaction conditions.

[0014] The raw materials are subjected to liquid phase oxidation reaction in the reactor, the nitrogen dioxide dissolved in the liquid phase is mixed with the raw material dimethyl sulfide for reaction, the oxidation product nitrogen monoxide is mixed with oxygen in the gas phase for reaction to generate nitrogen dioxide which is absorbed by the reaction liquid and continues to participate in the oxidation reaction process; after the oxidation reaction is completed, the dimethyl sulfoxide is separated by distillation, and the produced nitrogen dioxide is recycled under closed reaction conditions.

[0015] When adding dimethyl sulfoxide as the reaction base material, the temperature of the reactor is controlled at 20-100° C.;

[0016] The bottom material in the reactor flows into the distillation tower through the liquid overflow port 12 and the liquid distributor 22 until the bottom material liquid level reaches one-half to two-thirds of the tower bottom liquid level, and the tower bottom is heated to a specified temperature range of 50-200°C, and the tower top temperature range is 20-100°C.

[0017] The stripping tower is a plate tower or a packed tower, with 2-20 theoretical plates, the bottom material feed position reaches the feed port of the liquid distributor at the top of the tower, and the vapor phase is discharged from the top of the tower.

[0018] The nitrogen dioxide dosage corresponds to a material concentration range of 0.1%-10% (m NO2 / (m NO2 +m DMSO(底料) )×100%);

[0019] The dimethyl sulfide and oxygen are continuously metered and fed, and the molar feed ratio of dimethyl sulfide to oxygen is 1:0.45-0.55.

[0020] The pressure range of the reaction system pressure in the reactor is between -0.1 and 0.1 MPa (gauge pressure).

[0021] The production method of the present invention has the following advantages:

[0022] The present invention realizes the recycling of nitrogen dioxide under closed conditions in the production process of dimethyl sulfoxide by liquid phase oxidation method with dimethyl sulfide, nitrogen dioxide and oxygen as main raw materials; in the liquid phase oxidation reaction stage, nitrogen dioxide dissolved in the liquid phase realizes a rapid mixing reaction with the raw material dimethyl sulfide, and the oxidation product nitrogen monoxide reacts rapidly with oxygen in the gas phase to generate nitrogen dioxide, which is absorbed by the reaction liquid and continues to participate in the oxidation reaction process; after the oxidation reaction is completed, the loss of nitrogen dioxide in the oxidation reaction process is greatly reduced through distillation separation, and at the same time, the cost of three wastes treatment in the dimethyl sulfoxide production process is reduced, thereby improving the production competitiveness of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A process flow chart of a dimethyl sulfoxide production method provided in an embodiment of the present invention; wherein, 1-dimethyl sulfide / dimethyl sulfoxide metering feed pump, 2-circulation pump, 3-discharge port, 4-heat exchanger, 5-heat exchange medium inlet, 6-heat exchange medium outlet, 7-oxygen metering inlet, 8-nitrogen inlet, 9-nitrogen dioxide metering inlet, 10-ejector, 11-vent, 12-liquid overflow port, 13-reactor, 4-heat exchange medium inlet, 15-heat exchange medium outlet, 16-sampling port, 17-distillation tower, 18-heat exchange medium inlet, 19-heat exchange medium outlet, 20-cooler, 21-tower kettle metering discharge pump, 22-liquid distributor, 23-tower top gas phase pipeline, 24-input pipeline, 25-insulation jacket. DETAILED DESCRIPTION

[0024] The technical scheme and features of the present invention are described in detail through specific embodiments. The specific embodiments are included in but not limited to the present invention.

[0025] The present invention utilizes a systematic production method to achieve closed-loop use of nitrogen dioxide in a reaction system. In the reaction stage, the generated nitric oxide can be converted into nitrogen dioxide, and the nitrogen dioxide is absorbed and dissolved into the reaction system. In the separation stage, the nitrogen dioxide can be separated from the reaction system. The loss of nitrogen dioxide in the production process is greatly reduced, and the output of waste salt in the production process is also reduced accordingly. In addition, the reaction process is simple to control and safe to operate, and is suitable for upgrading and transformation of existing similar production processes.

[0026] Specifically:

[0027] Adding dimethyl sulfoxide into the oxidation reactor until overflowing, and using it as reactor bottom material for material circulation and temperature control; continuing to add dimethyl sulfoxide to a specified liquid level in the stripping tower kettle, opening the kettle and heating it to a specified temperature; quantitatively adding nitrogen dioxide into the oxidation reactor until the pressure of the reaction system is stable; continuously metering dimethyl sulfide and oxygen into the reactor, and continuously metering dimethyl sulfoxide out of the reactor; heating the reaction liquid that meets the process requirements through a stripping tower, separating the product from the reactor (tower kettle), and low-boiling components such as nitrogen dioxide being absorbed from the top of the stripping tower into the reaction system to continue to participate in the reaction; the entire reaction and separation process is operated in a closed manner under the same equipment environment, thereby achieving zero emission of nitrogen dioxide in the reaction process.

[0028] Example 1

[0029] like Figure 1As shown, a production system of dimethyl sulfoxide includes a feed pump 1, a circulation pump 2, a heat exchanger 4, a reactor 13 and a distillation tower 17, wherein the circulation pump 2, the heat exchanger 4 and the reactor 13 are sequentially connected in series to form a closed loop, and the feed pump 1 is connected to the pipeline between the reactor 13 and the circulation pump 2 through a pipeline, and the upper end of the reactor 13 is provided with an oxygen metering inlet 7, a nitrogen inlet 8, a nitrogen dioxide metering inlet 9, an ejector 10, a vent 11 and a liquid overflow port 12, and the ejector 10 is connected to the output gas phase pipeline 23 at the upper end of the distillation tower 17, and the liquid overflow port 12 is connected to the input pipeline 24 at the upper end of the distillation tower 17.

[0030] A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially provided on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction, a second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 13, and a sampling port 16, a third temperature sensor and a third pressure sensor are sequentially provided on the pipeline between the reactor 13 and the circulation pump 2 along the material flow direction.

[0031] The heat exchanger 4 is provided with a first heat exchange medium inlet 5 at one end and a first heat exchange medium outlet 6 at the other end.

[0032] The reactor 13 is provided with an insulation jacket 25 outside, and a second heat exchange medium inlet 14 is provided on one side of the insulation jacket 25, and a second heat exchange medium outlet 15 is provided on the other side. A second pressure sensor is provided at the upper end of the reactor 13.

[0033] A liquid distributor 22 is provided inside the upper end of the distillation tower 17, and the input pipeline 24 is connected to the liquid distributor 22. A heat exchange pipeline is provided inside the lower end of the distillation tower 17, and a third heat exchange medium inlet 18 connected to the heat exchange pipeline is provided on one side of the lower end shell of the distillation tower 17, and a third heat exchange medium outlet 19 connected to the heat exchange pipeline is provided on the other side. A discharge pipeline is provided at the lower end of the distillation tower 17, and a cooler 22 and a metering discharge pump 21 are sequentially provided on the discharge pipeline.

[0034] Example 2

[0035] Dimethyl sulfoxide is prepared using the system shown in Example 1. The heat exchange medium used in the heat exchanger 4 in the device is hot water. The reactor 13 is a steel vertical jacketed kettle, and the heat exchange medium used is warm water. The distillation tower 17 is a structured packing tower with 10 theoretical plates, and the medium used for heat exchange in its reboiler is hot oil.

[0036] Production method of dimethyl sulfoxide:

[0037] (1) Check the valve switch status of the system, open the nitrogen valve 8 to adjust the system pressure, replace the gas phase space of the system 3 times, introduce 30°C warm water into the reactor jacket heat exchange medium inlet 14 and the heat exchanger heat exchange medium inlet 15 to preheat the reaction system, preheat 50L of dimethyl sulfoxide (bottom material) and add it to the reactor 13 through the metering pump 1, start the circulation pump 2, open the valve of the liquid overflow port 12, and continue to meter dimethyl sulfoxide until the bottom liquid level of the stripping tower 17 reaches a specified height (i.e., one-half to two-thirds of the height of the bottom liquid level gauge (the bottom liquid level gauge in this embodiment is one-half of the height)), and introduce heat transfer oil into the heat exchange medium inlet 18 of the stripping tower to start heating until the top temperature of the stripping tower rises to a specified temperature (i.e., the bottom temperature is constant to the boiling temperature of the material);

[0038] (2) Open the nitrogen dioxide metering feed port 9 and quantitatively add 0.75 kg of nitrogen dioxide until the system pressure stabilizes at 0.001 MPa (gauge pressure);

[0039] (3) Open the metering feed pump 1 to adjust the flow rate, and continuously introduce 15.0 kg of dimethyl sulfide into the reaction system (dimethyl sulfide feed flow rate 6.0 L / h), open the oxygen metering valve 7 to adjust the flow rate, and continuously introduce oxygen into the reaction system. The oxygen feed rate is 0.9 m 3 / h, the oxidation reactor temperature reaches 60°C and the reaction begins. The material status of the reaction process is monitored through the sampling port 16. The reaction temperature is controlled to be maintained at 60°C by controlling the temperature of the heat exchanger and the reactor jacket heat exchange medium.

[0040] (4) The heat exchange medium of the cooler 20 is turned on (i.e., the heat exchange medium is cooling water at room temperature), and the product is taken out after being cooled in the distillation tower. The distillation tower kettle discharge is 6.4 kg / h. The dimethyl sulfoxide metering discharge pump 21 is turned on to continuously take out the product. The acid value of the tower kettle discharge is tested to be 0.024 mgKOH / g, and the impurity content is 0.56% (wt). The system operates stably, and sampling is performed to monitor the material status.

[0041] During the above-mentioned oxidation reaction, low-boiling components such as nitrogen dioxide are reabsorbed from the top of the distillation tower through the ejector and enter the reaction system to participate in the reaction. The entire reaction and separation process is operated in a closed manner under the same device environment, achieving zero emission of nitrogen dioxide during the reaction process.

[0042] Example 3

[0043] The system described in Example 1 was used for preparation. The difference from Example 2 was that the oxidation reactor was fed with 15.0 kg of dimethyl sulfoxide, 0.75 kg of nitrogen dioxide, 12.0 L / h of dimethyl sulfide feed flow rate, and 1.8 m / h of oxygen feed rate. 3 / h, oxidation reactor temperature 70 ° C, reactor pressure 0.005Mpa (gauge pressure), distillation tower kettle discharge 12.7kg / h, the test distillation tower kettle discharge acid value 0.035mgKOH / g, impurity content 0.75% (wt).

[0044] Example 4

[0045] The system described in Example 1 was used for preparation. The difference from Example 2 was that the oxidation reactor was fed with 15.0 kg of dimethyl sulfoxide, 0.30 kg of nitrogen dioxide, 4.0 L / h of dimethyl sulfide feed flow rate, and 0.6 m / h of oxygen feed. 3 / h, oxidation reactor temperature 50 ° C, reactor pressure 0.005Mpa (gauge pressure), distillation tower kettle discharge 4.2kg / h, the test distillation tower kettle discharge acid value 0.021mgKOH / g, impurity content 0.15% (wt).

[0046] Example 5

[0047] The system described in Example 1 was used for preparation. The difference from Example 2 was that the oxidation reactor was fed with 15.0 kg of dimethyl sulfoxide, 0.15 kg of nitrogen dioxide, 2.0 L / h of dimethyl sulfide feed flow rate, and 0.3 m / h of oxygen feed rate. 3 / h, oxidation reactor temperature 55 ° C, reactor pressure 0.001Mpa (gauge pressure), distillation tower kettle discharge 2.1kg / h, the test distillation tower kettle discharge acid value 0.015mgKOH / g, impurity content 0.10% (wt).

Claims

1. A production system of dimethyl sulfoxide, characterized in that: The invention comprises a feed pump 1, a circulation pump 2, a heat exchanger 4, a reactor 13 and a distillation tower 17, wherein the circulation pump 2, the heat exchanger 4 and the reactor 13 are sequentially connected in series to form a closed loop, and the feed pump 1 is connected to the pipeline between the reactor 13 and the circulation pump 2 through a pipeline, and an oxygen metering inlet 7, a nitrogen inlet 8, a nitrogen dioxide metering inlet 9, an ejector 10, a vent 11 and a liquid overflow port 12 are arranged at the upper end of the reactor 13, and the ejector 10 is connected to the output gas phase pipeline 23 at the upper end of the distillation tower 17, and the liquid overflow port 12 is connected to the input pipeline 24 at the upper end of the distillation tower 17.

2. The production system of dimethyl sulfoxide according to claim 1, characterized in that: A first temperature sensor, a first pressure sensor and a discharge port 3 are sequentially provided on the pipeline between the circulation pump 2 and the heat exchanger 4 along the material flow direction, a second temperature sensor is provided on the pipeline between the heat exchanger 4 and the reactor 13, and a sampling port 16, a third temperature sensor and a third pressure sensor are sequentially provided on the pipeline between the reactor 13 and the circulation pump 2 along the material flow direction.

3. The production system of dimethyl sulfoxide according to claim 1, characterized in that: The heat exchanger 4 is provided with a first heat exchange medium inlet 5 at one end and a first heat exchange medium outlet 6 at the other end.

4. The production system of dimethyl sulfoxide according to claim 1, characterized in that: The reactor 13 is provided with an insulation jacket 25 outside, and a second heat exchange medium inlet 14 is provided on one side of the insulation jacket 25, and a second heat exchange medium outlet 15 is provided on the other side. A second pressure sensor is provided at the upper end of the reactor 13.

5. The production system of dimethyl sulfoxide according to claim 1, characterized in that: A liquid distributor 22 is provided inside the upper end of the distillation tower 17, and the input pipeline 24 is connected to the liquid distributor 22. A heat exchange pipeline is provided inside the lower end of the distillation tower 17, and a third heat exchange medium inlet 18 connected to the heat exchange pipeline is provided on one side of the lower end shell of the distillation tower 17, and a third heat exchange medium outlet 19 connected to the heat exchange pipeline is provided on the other side. A discharge pipeline is provided at the lower end of the distillation tower 17, and a cooler 22 and a metering discharge pump 21 are sequentially provided on the discharge pipeline.

6. A method for preparing dimethyl sulfoxide using the production system of claim 1, characterized in that: Through the system described in claim 1, dimethyl sulfoxide is added from the metering pump 1 to the reactor 13 through the heat exchanger until it overflows and is used as the reactor bottom material for material circulation and temperature control; In addition, the valve of the liquid overflow port 12 of the reactor 13 is opened, and dimethyl sulfoxide is continuously added to flow into the stripping tower kettle, and nitrogen dioxide is simultaneously added into the reactor until the pressure of the reaction system is stable; After the pressure in the reactor is stabilized, the reaction raw material dimethyl sulfide is continuously added to the reactor through a heat exchanger. At this time, oxygen is also introduced, and a liquid-phase oxidation reaction is carried out in the reactor under closed conditions. The product after the reaction is separated by distillation to obtain dimethyl sulfoxide, and the oxidation product nitrogen dioxide is recycled under closed reaction conditions.

7. The method for preparing dimethyl sulfoxide according to claim 6, characterized in that: The raw materials are subjected to liquid phase oxidation reaction in the reactor, the nitrogen dioxide dissolved in the liquid phase is mixed with the raw material dimethyl sulfide for reaction, the oxidation product nitrogen monoxide is mixed with oxygen in the gas phase for reaction to generate nitrogen dioxide which is absorbed by the reaction liquid and continues to participate in the oxidation reaction process; after the oxidation reaction is completed, the dimethyl sulfoxide is separated by distillation, and the produced nitrogen dioxide is recycled under closed reaction conditions.

8. The method for preparing dimethyl sulfoxide according to claim 6, characterized in that: When adding dimethyl sulfoxide as the reaction base material, the temperature of the reactor is controlled at 20-100° C.; The bottom material in the reactor flows into the distillation tower through the liquid overflow port 12 and the liquid distributor 22 until the bottom material liquid level reaches one-half to two-thirds of the tower bottom liquid level, and the tower bottom is heated to a specified temperature range of 50-200°C, and the tower top temperature range is 20-100°C.

9. The method for preparing dimethyl sulfoxide according to claim 6 or 7, characterized in that: The stripping tower is a plate tower or a packed tower, with 2-20 theoretical plates, the bottom material feed position reaches the feed port of the liquid distributor at the top of the tower, and the vapor phase is discharged from the top of the tower.

10. The method for preparing dimethyl sulfoxide according to claim 6 or 7, characterized in that: The nitrogen dioxide dosage corresponds to a material concentration range of 0.1%-10% (m NO2 / (m NO2 +m DMSO )×100%); The dimethyl sulfide and oxygen are continuously metered and fed, and the molar feed ratio of dimethyl sulfide to oxygen is 1:0.45-0.55.

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