A method for continuously producing high-purity sulfoxoline

Abstract

The application discloses a method for continuously preparing high-purity sulfolane, and belongs to the technical field of organic synthesis. By introducing a solvent and a stable free radical type polymerization inhibitor, the self-polymerization of butadiene is effectively inhibited. By adopting a cooling crystallization mode to remove sulfur dioxide, the thermal decomposition of sulfolene sulfone is avoided, high yield and high purity are realized, the service life of a hydrogenation catalyst is not affected, and the catalyst can be completely reused. The cooling crystallization also realizes the separation of the polymerization inhibitor and sulfolene sulfone. The polymerization inhibitor is dissolved in the solvent and recycled, and does not enter the hydrogenation system, so that the final sulfolane product has a purity of above 99.9% and has no chromaticity problem. The process saves energy consumption, the solvent has wide universality, operation is simple, the process is safe and environment-friendly, easy to scale up, and meets the green production requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to a method for continuously preparing high-purity sulfolane. BACKGROUND

[0002] Sulfolane is also called tetrahydrothiophene-1,1-dioxide, is a colorless transparent liquid, is an excellent aprotic polar solvent, can be mutually soluble with water, acetone, toluene and the like, and is also an ideal solvent in an aromatic extraction process in petroleum chemical industry.

[0003] Patent CN117658977A discloses a method for reacting butadiene and sulfur dioxide in a cyclopentane solvent in the presence of a polymerization inhibitor to obtain a cyclobutene sulfone solution; then flash evaporation of the obtained cyclobutene sulfone solution to obtain a gas phase and a liquid phase; the gas phase is condensed and recycled, and the liquid phase is stripped with cyclopentane gas to obtain cyclobutene sulfone; the cyclobutene sulfone is then subjected to a catalytic hydrogenation reaction to obtain a hydrogenation product; the hydrogenation product is then decomposed by evaporation, the gas phase is condensed and solvent purified, and the obtained solvent is recycled; the liquid phase is purified to obtain cyclobutene sulfone. The main purpose of this method is to overcome problems such as equipment pipeline blockage and sulfur dioxide loss, but the process still has the following defects: 1. Using a large amount of cyclopentane gas to strip sulfur dioxide increases energy consumption and cannot completely strip the sulfur dioxide from the cyclobutene sulfone reaction solution, leaving 200-300 ppm of sulfur dioxide, which will deactivate the hydrogenation catalyst in the second step; 2. The stripping and flash evaporation temperatures are both 70°C. ℃, but sulfolane begins to decompose slowly at 60 ℃. As the temperature increases, the decomposition rate accelerates, so the yield of sulfolane will decrease; 3. The selected polymerization inhibitor is 1,2-dihydro-2,2,4-trimethylquinoline polymer. The boiling point of this polymer is >315 ℃, so it will enter the hydrogenation step with the reaction liquid and eventually remain in the bottom liquid of the sulfolane distillation column. It will be mixed with impurities in the bottom liquid and treated, and cannot be recycled. Patent CN117510459A discloses a method for reacting sulfur dioxide with butadiene in the presence of a 1,2-dihydro-2,2,4-trimethylquinoline polymer to obtain a product containing cyclobutene sulfone. The 1,2-dihydro-2,2,4-trimethylquinoline polymer acts as a polymerization inhibitor to suppress the self-polymerization of butadiene during the synthesis of cyclobutene sulfone from sulfur dioxide and butadiene, resulting in a high yield of cyclobutene sulfone and improved selectivity. The main purpose of this method is to overcome the shortcomings of existing polymerization inhibitors, which have poor polymerization inhibition effects. The drawbacks include: 1. The 1,2-dihydro-2,2,4-trimethylquinoline polymer cannot be removed and can only be processed in the bottom liquid of the distillation column; 2. Sulfolane is used as a solvent in the synthesis of sulfolane, and sulfolane has good solubility for sulfur dioxide, so sulfur dioxide cannot be completely removed under flash evaporation or hot nitrogen stripping; 3. Although a large amount of hot nitrogen stripping can strip most of the sulfur dioxide from the sulfolane reaction solution, it also causes the loss of sulfur dioxide and unreacted butadiene; 4. The flash evaporation and nitrogen temperature of 70 ℃ will lead to the decomposition of some sulfolane.Patent CN102020632B discloses a process in which sulfur dioxide and a polymerization inhibitor are added to a synthesis mixing reactor, followed by the injection of butadiene. The reactor is then circulated using a circulating pump in a synthesis static mixer, a synthesis heater / cooler, and another synthesis mixing reactor. The resulting sulfolane is diluted with benzene and then reacted with a catalyst and hydrogen in a hydrogenation mixing reactor, a hydrogenation static mixer, and a hydrogenation heater / cooler to produce sulfolane. This patent only provides a brief description of the process without mentioning specific process parameters, focusing instead on the equipment. This reaction process requires continuous circulation of the reaction liquid, resulting in a long reaction time and low production efficiency.

[0004] The existing industrial-scale production processes for sulfolane primarily employ batch reactors, resulting in poor reaction efficiency and low yields. Furthermore, some patented processes omit solvents during sulfolane preparation, making them highly susceptible to clogging if equipment or pipeline temperatures are not properly controlled. Sulfur dioxide removal from the sulfolane reaction solution often involves flash evaporation, acid-base neutralization, and solvent and hot nitrogen stripping, which offer limited effectiveness and result in significant sulfur dioxide loss. Simultaneously, sulfur dioxide participates in the second hydrogenation step, deactivating the catalyst, impacting sulfolane conversion, and increasing production costs. Furthermore, the high temperatures of flash evaporation and stripping can cause thermal decomposition of sulfolane, affecting its yield. The polymerization inhibitors used in the preparation of sulfolane are mostly molecular inhibitors such as hydroquinone, p-tert-butylcatechol, p-benzoquinone, and 1,2-dihydro-2,2,4-trimethylquinoline polymer. These inhibitors have relatively poor polymerization inhibition effects and require a high proportion. The presence of these inhibitors also leads to two problems: hydroquinone and p-tert-butylcatechol have boiling points close to that of the product sulfolane, making them impossible to separate during distillation and causing them to enter the final product, affecting its purity and color; while 1,2-dihydro-2,2,4-trimethylquinoline polymer, although having higher boiling points than sulfolane, is itself a polymer mixture that cannot be effectively recycled and accumulates in the distillation column, requiring waste treatment and increasing production costs. Summary of the Invention

[0005] The purpose of this application is to provide a method for the continuous preparation of high-purity sulfolane, in order to solve the technical problems in the existing preparation of sulfolane, such as low butadiene conversion rate, easy low-temperature crystallization of sulfolane clogging of equipment or pipelines, easy decomposition upon heating, difficulty in separating sulfur dioxide and sulfolane , sulfolane and polymerization inhibitors, and poor polymerization inhibitor effect.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for the continuous preparation of high-purity sulfolane, specifically including the following steps: (i) Inert ball packing is added to a fixed-bed reactor, the temperature is raised, sulfur dioxide is added, the pressure is increased, and polymerization inhibitor, sulfur dioxide and butadiene are introduced to react and obtain a mixed reaction solution. (ii) Cool the mixed reaction solution to crystallize and obtain sulfolane and filtrate; after the sulfolane is dissolved, it enters the reactor, the reactor is filled with nickel-based catalyst, hydrogen is introduced, and the pressure and temperature are increased to carry out the reaction. After the reaction is completed, the system is dehydrated and distilled to obtain sulfolane.

[0007] In one embodiment, The cooling and crystallization temperature in step (ii) is -20~0 ℃.

[0008] In one embodiment, In step (1), the polymerization inhibitor is dissolved in methanol to prepare a polymerization inhibitor solution; the molar ratio of methanol, sulfur dioxide added for the second time and butadiene is 4:1.5:1.

[0009] In one embodiment, The polymerization inhibitor mentioned in step (1) is one of polymerization inhibitor 701, DPPH or TEMPO.

[0010] In one embodiment, The mass ratio of butadiene to polymerization inhibitor in step (1) is 1:0.001-0.009.

[0011] In one embodiment, The temperature for heating in step (1) is 80-130 ℃, and the pressure for pressurizing is 0.5-3.0 MPa.

[0012] In one embodiment, Step (1): The mass ratio of the first addition of sulfur dioxide to the second addition of sulfur dioxide is 1-3:1.

[0013] In one embodiment, In step (ii), the mass ratio of cyclobutene sulfone to nickel-based catalyst is 1:0.02-0.12, the volume ratio of nickel-based catalyst to inert spherical packing is 1:70-90, and the hydrogen flow rate is 1-10 g / h.

[0014] In one embodiment, The pressure for pressurization in step (ii) is 0.5-4.0 MPa, and the temperature for heating is 30-70 ℃.

[0015] In one embodiment, The filtrate in step (ii) includes a polymerization inhibitor solution, sulfur dioxide, and butadiene. After being recovered, the filtrate is returned to the fixed-bed reactor to continue participating in the reaction.

[0016] This application provides a method for the continuous preparation of high-purity sulfolane, simultaneously achieving continuous production of sulfolane, significantly improving production efficiency and saving energy. This method, by introducing solvents such as methanol and acetonitrile into the reaction system, not only weakens the self-polymerization of butadiene in the gas phase space of the reactor and improves the butadiene conversion rate, but also avoids the problem of equipment or pipeline blockage caused by low-temperature crystallization of sulfolane. Simultaneously, the selection of a stable free radical polymerization inhibitor can efficiently terminate the chain reaction, exhibiting excellent polymerization inhibition effect on butadiene, with a small addition ratio and superior performance compared to traditional polymerization inhibitors such as phenols and aromatic amines; DPPH can be added at concentrations as low as 10... -4 At a concentration of mol / L, polymerization can be completely inhibited, effectively preventing the self-polymerization of butadiene during synthesis, separation, purification, storage, or transportation, making the reaction process more stable and significantly reducing the polymer content. This innovative method employs cooling crystallization to solve the problem of separating sulfur dioxide and sulfolane. Low-temperature operation avoids the thermal decomposition of sulfolane, resulting in a yield of over 99% and a purity of over 99% during continuous operation. Furthermore, the residual sulfur dioxide content is as low as below 10 ppm, preventing it from entering subsequent hydrogenation reactions and affecting catalyst lifespan. The hydrogenation catalyst can thus be completely recycled, significantly reducing production costs. Simultaneously, unreacted butadiene and sulfur dioxide can be dissolved in solvents for recycling, reducing raw material loss and making the process safer and more environmentally friendly. In addition, cooling crystallization also achieves the separation of sulfolane from the polymerization inhibitor: the inhibitor is dissolved in the solvent and recycled, preventing it from entering the hydrogenation reaction with sulfolane. This avoids the inhibitor's adverse effects on the purity and color of the sulfolane product, resulting in a low-impurity sulfolane reaction solution. After distillation, a high-purity product with acceptable color can be obtained. In terms of energy utilization, the high-temperature material at the outlet of the fixed-bed reactor is coupled with the low-temperature material from other units, effectively saving energy consumption. This process has high solvent versatility (such as acetonitrile, methanol, ethanol, toluene, acetone and other common solvents), the raw materials are readily available and unrestricted, the overall operation is simple, there are no complex reaction devices, it is highly safe and environmentally friendly, and it has the feasibility of industrial scale-up. Through cooling crystallization, sulfur dioxide, butadiene, polymerization inhibitors and solvents are fully recovered and reused, and waste liquid and waste gas emissions are low. At the same time, the coupling of materials and energy in each unit optimizes the process, significantly reducing material consumption and energy consumption, and meeting the requirements of clean production. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram of the production process equipment. Figure 2 The hydrogen NMR spectrum of sulfolane obtained in Example 1; Figure 3 The carbon NMR spectrum of sulfolane obtained in Example 1; Figure 4 The gas chromatogram of sulfolane obtained in Example 1; Figure 5 The image shows the gas-mass chromatogram of sulfolane obtained in Example 1.

[0019] Explanation of symbols in the diagram: 1. Fixed-bed reactor; 2. First heat exchanger; 3. Crystallizer; 4. Filter; 5. Second heat exchanger; 6. Hydrogenation reactor; 7. Flash distillation column; 8. Distillation column. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0021] like Figure 1 As shown, the process flow of this application is as follows: Butadiene, sulfur dioxide and polymerization inhibitor are fed into fixed-bed reactor 1 for reaction. The mixed reaction liquid enters crystallizer 3 through second heat exchanger 5 and first heat exchanger 2. After cooling and crystallization, sulfolane and filtrate are obtained. Sulfolane and filtrate enter filter 4 for filtration. The filtrate is returned to fixed-bed reactor 1 through first heat exchanger 2 to participate in the next round of reaction. Sulfolane enters hydrogenation reactor 6 through second heat exchanger 5. Hydrogen is introduced into hydrogenation reactor 6 and reacts with sulfolane. After the reaction is completed, the system is fed into flash distillation tower 7 for dehydration. Water is circulated to the front end of second heat exchanger 5 to dissolve sulfolane. The crude sulfolane enters distillation tower 8 for distillation to obtain the final product sulfolane.

[0022] Example 1 A method for the continuous preparation of high-purity sulfolane specifically includes the following steps: (i) Fill a fixed-bed reactor with inert ball packing, raise the temperature of the fixed-bed reactor to 85 ℃, introduce 80 g of sulfur dioxide, raise the pressure of the reactor and maintain it at 1.0 MPa, and then introduce the polymerization inhibitor solution (polymerization inhibitor 701 is prepared by dissolving it in methanol) at a rate of 64.02 g / h, sulfur dioxide at a rate of 48.0 g / h, and butadiene at a rate of 27.0 g / h from the bottom of the reactor to carry out the reaction and obtain a mixed reaction solution; The molar ratio of methanol, sulfur dioxide, and butadiene is 4:1.5:1, and the mass ratio of butadiene to polymerization inhibitor is 1:0.005. (II) The mixed reaction solution flows into the crystallizer from the top of the fixed-bed reactor and is cooled and crystallized at -10 ℃ to obtain sulfolane and filtrate. The crystallized sulfolane is dissolved in water at 200 g / h and then enters the top of the hydrogenation reactor. The hydrogenation reactor is filled with 2.95 g of spherical nickel-based catalyst particles. At the same time, hydrogen gas is introduced from the top of the hydrogenation reactor at a rate of 2.0 g / h to maintain the pressure of the hydrogenation reactor at 1.0 MPa and the temperature at 40 ℃ for reaction. After the reaction is completed, the system is discharged from the bottom and sent to the flash distillation tower to remove water, and then sent to the distillation tower for distillation to finally obtain the sulfolane product with a purity of 99.9% and a yield of 99.2%. The filtrate after crystallization (polymerization inhibitor solution, sulfur dioxide, butadiene) is returned to the fixed-bed reactor to continue to participate in the reaction.

[0023] Example 2 The difference between this embodiment and Example 1 is that the cooling crystallization temperature in step (II) is -20 ℃, while the rest of the operation is the same, and sulfolane is obtained with a purity of 99.5% and a yield of 99.2%.

[0024] Example 3 The difference between this embodiment and Example 1 is that the cooling crystallization temperature in step (II) is 0 ℃, while the rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 97.0%.

[0025] Example 4 The difference between this embodiment and Example 1 is that the polymerization inhibitor 701 is replaced with DPPH, while the rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 97.9%.

[0026] Example 5 The difference between this embodiment and Example 1 is that the polymerization inhibitor 701 is replaced with TEMPO, while the rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 98.6%.

[0027] Example 6 The difference between this embodiment and Example 1 is that the mass ratio of butadiene to polymerization inhibitor is 1:0.002, while the rest of the operations are the same, to obtain sulfolane with a purity of 99.9% and a yield of 96.3%.

[0028] Example 7 The difference between this embodiment and Example 1 is that the mass ratio of butadiene to polymerization inhibitor is 1:0.009, while the rest of the operations are the same, to obtain sulfolane with a purity of 99.8% and a yield of 98.8%.

[0029] Example 8 The difference between this embodiment and Example 1 is that the molar ratio of methanol, the second addition of sulfur dioxide, and butadiene is 2:1:1. The rest of the operations are the same, and sulfolane is obtained with a purity of 99.9% and a yield of 96.9%.

[0030] Example 9 The difference between this embodiment and Example 1 is that the molar ratio of methanol, the second addition of sulfur dioxide, and butadiene is 4:3:1. The rest of the operations are the same, and sulfolane is obtained with a purity of 99.9% and a yield of 97.7%.

[0031] Example 10 The difference between this embodiment and Example 1 is that the reaction temperature in step (1) is 80 ℃ and the pressure is 0.5 MPa. The rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 96.2%.

[0032] Example 11 The difference between this embodiment and Example 1 is that the reaction temperature in step (i) is 130 ℃ and the pressure is 3.0 MPa. The rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 98.6%.

[0033] Example 12 The difference between this embodiment and Example 1 is that in step (ii), the mass ratio of sulfolane to nickel-based catalyst is 1:0.02, the volume ratio of nickel-based catalyst to inert ball packing is 1:70, the hydrogen flow rate is 1 g / h, and the rest of the operations are the same, to obtain sulfolane with a purity of 99.7% and a yield of 98.1%.

[0034] Example 13 The difference between this embodiment and Example 1 is that in step (ii), the mass ratio of sulfolane to nickel-based catalyst is 1:0.12, the volume ratio of nickel-based catalyst to inert ball packing is 1:90, the hydrogen flow rate is 10 g / h, and the rest of the operations are the same, to obtain sulfolane with a purity of 99.9% and a yield of 99.3%.

[0035] Example 14 The difference between this embodiment and Example 1 is that the reaction temperature in step (ii) is 30 ℃ and the pressure is 0.5 MPa. The rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 96.4%.

[0036] Example 15 The difference between this embodiment and Example 1 is that the reaction temperature in step (ii) is 70 ℃ and the pressure is 4.0 MPa. The rest of the operation is the same, and sulfolane is obtained with a purity of 99.9% and a yield of 98.5%.

[0037] Example 16 The difference between this embodiment and Example 1 is that the polymerization inhibitor solution was prepared by dissolving polymerization inhibitor 701 in acetonitrile. The rest of the operations were the same, and sulfolane was obtained with a purity of 99.9% and a yield of 99.3%.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for the continuous preparation of high-purity sulfolane, characterized in that, Specifically, the following steps are included: (i) Inert ball packing is added to a fixed-bed reactor, the temperature is raised, sulfur dioxide is added, the pressure is increased, and polymerization inhibitor, sulfur dioxide and butadiene are introduced to react and obtain a mixed reaction solution. (ii) Cool the mixed reaction solution to crystallize and obtain sulfolane and filtrate; after the sulfolane is dissolved, it enters the reactor, the reactor is filled with nickel-based catalyst, hydrogen is introduced, and the pressure and temperature are increased to carry out the reaction. After the reaction is completed, the system is dehydrated and distilled to obtain sulfolane.

2. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The cooling and crystallization temperature in step (ii) is -20~0 ℃.

3. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, In step (1), the polymerization inhibitor is dissolved in methanol or acetonitrile to prepare a polymerization inhibitor solution; the molar ratio of methanol or acetonitrile, sulfur dioxide added for the second time, and butadiene is 2-6 : 1-3 :

1.

4. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The polymerization inhibitor mentioned in step (1) is one of polymerization inhibitor 701, DPPH or TEMPO.

5. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The mass ratio of butadiene to polymerization inhibitor in step (1) is 1:0.001-0.

009.

6. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The temperature for heating in step (1) is 80-130 ℃, and the pressure for pressurizing is 0.5-3.0 MPa.

7. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, Step (1): The mass ratio of the first addition of sulfur dioxide to the second addition of sulfur dioxide is 1-3:

1.

8. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, In step (ii), the mass ratio of cyclobutene sulfone to nickel-based catalyst is 1:0.02-0.12, the volume ratio of nickel-based catalyst to inert spherical packing is 1:70-90, and the hydrogen flow rate is 1-10 g / h.

9. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The pressure for pressurization in step (ii) is 0.5-4.0 MPa, and the temperature for heating is 30-70 ℃.

10. The method for continuous preparation of high-purity sulfolane according to claim 1, characterized in that, The filtrate in step (ii) includes a polymerization inhibitor solution, sulfur dioxide, and butadiene. After being recovered, the filtrate is returned to the fixed-bed reactor to continue participating in the reaction.

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