A method for purifying high-purity dimethyl sulfoxide

Abstract

The application discloses a purification method of high-purity dimethyl sulfoxide, and particularly relates to the use of the purification of crude dimethyl sulfoxide to electronic-grade refined product, solves the problems of complex equipment, numerous processes and insufficient purity of the existing purification method, and has the technical advantages of green and high efficiency, and even low-purity crude product can be purified to obtain the electronic-grade refined product.

Description

Technical Field

[0001] This invention relates to the field of chemical purification, specifically to a method for purifying high-purity dimethyl sulfoxide. Background Technology

[0002] Dimethyl sulfoxide (DMSO), as a key aprotic polar solvent, directly impacts its application in high-end fields such as pharmaceuticals and electronic materials. Existing purification processes generally suffer from high energy consumption, complex steps, and severe pollution. This patent aims to provide an efficient, green, and economical industrial purification solution through an innovative process flow.

[0003] Currently, dimethyl sulfoxide (DMSO) is mainly produced via the oxidation of dimethyl sulfide, resulting in crude products containing various impurities. Traditional purification methods rely on multi-step vacuum distillation combined with adsorption and crystallization, which carries the risk of high-temperature decomposition, requires stringent vacuum conditions and complex equipment, and can easily affect product color and stability. Methods such as molecular sieve dehydration or azeotropic distillation face problems such as high regeneration energy consumption and azeotropic agent residue, leading to complex and costly processes that struggle to simultaneously achieve high purity and green production requirements. Therefore, developing a simple, environmentally friendly process that can stably produce high-purity products is of great significance. Summary of the Invention

[0004] To improve the purification method of dimethyl sulfoxide, especially low-purity dimethyl sulfoxide, this invention designs a simple and efficient purification process that has low equipment requirements and can meet the purification needs of most crude dimethyl sulfoxide products.

[0005] On the one hand, this application provides a method for purifying dimethyl sulfoxide, characterized by comprising the following steps: 1) Add the dimethyl sulfoxide sample into a vacuum distillation apparatus and obtain the dimethyl sulfoxide vapor phase separator by vacuum distillation; 2) Input the vapor phase separator into the primary purification tank from the bottom; 3) The top of the primary purification tank is connected to the top of the refined purification tank. The vapor phase separation product of the initial purification is fed into the refined purification tank filled with solid particles of sulfonic acid cation exchange resin from the top, and the purified product of dimethyl sulfoxide is collected from the bottom.

[0006] In some embodiments, the reduced pressure distillation conditions are 130-150℃ and 10-40 kPa. In some embodiments, the reduced pressure distillation conditions in step 1) are 140-150℃ and 20-40 kPa. In some specific embodiments, the reduced pressure distillation conditions in step 1) are 140-145℃ and 20-30 kPa. In some specific embodiments, the reduced pressure distillation conditions in step 1) are 140-145℃ and 30 kPa. In some specific embodiments, the reduced pressure distillation conditions in step 1) are 145℃ and 30 kPa.

[0007] In some embodiments, the temperature conditions for vacuum fractionation are 130°C, 135°C, 140°C, 145°C, and 150°C, and the pressure conditions are 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, and 40 kPa. In some specific embodiments, the vacuum fractionation conditions in step 1) are 145°C and 30 kPa.

[0008] In some embodiments, the initial purification tank is provided with perfluorosulfonic acid type cation exchange membranes arranged at 30-90 degrees to the direction of vapor flow; in some specific embodiments, the arrangement angle is 30-60 degrees; in some specific embodiments, the arrangement angle is 30, 45 or 60 degrees; in some specific embodiments, the arrangement angle is 45 degrees.

[0009] In some embodiments, a gap is left between the tank wall of the primary purification tank and the perfluorosulfonic acid type cation exchange membrane to facilitate the smooth passage of vapor phase separators.

[0010] In some implementations, the bottom of the side wall of the purification tank is provided with an air inlet, through which low-temperature nitrogen gas is injected at a low pressure. A temperature sensor is installed at the bottom of the purification tank, and a pressure difference is formed between the top and the bottom. The standard is that the vapor phase at the top can smoothly enter the purification tank and uniformly form a low-temperature dimethyl sulfoxide purification product at the bottom.

[0011] In some implementations, the cryogenic nitrogen gas is specifically nitrogen gas at 4°C.

[0012] In some embodiments, the low-temperature dimethyl sulfoxide purified product is specifically a dimethyl sulfoxide purified product at a temperature of approximately 15°C.

[0013] In some embodiments, the purification tank holds solid particles of sulfonic acid-type cation exchange resin with a particle size range of 0.5-5 mm; in some specific embodiments, the particle size is selected to be 2-3 mm; in some specific embodiments, the particle size is selected to be 2 mm; and in some specific embodiments, the particle size is selected to be 3 mm.

[0014] In some embodiments, the purification tank is further filled with copper-nickel chelating resin and iron-removing resin; in some specific embodiments, the copper-nickel chelating resin and iron-removing resin are located at the lower end of the sulfonic acid type cation exchange resin solid particles.

[0015] In some embodiments, the perfluorosulfonic acid type cation exchange membrane is non-planar; in some specific embodiments, it is preferably wavy; in some specific embodiments, it is preferably smooth wavy or zigzag wavy.

[0016] In some embodiments, the purity of the dimethyl sulfoxide sample is 70-99.98%; in some embodiments, the purity of the dimethyl sulfoxide sample is 80-99.98%; in some embodiments, the purity of the dimethyl sulfoxide sample is 85-99.98%; in some embodiments, the purity of the dimethyl sulfoxide sample is 80%, 85%, 90%, 95%, 99%, 99.5%, 99.9%, 99.95%, or 99.98%.

[0017] In some embodiments, the water content of the dimethyl sulfoxide sample is less than 0.1%; in some embodiments, the water content of the dimethyl sulfoxide sample is less than 0.05%; in some embodiments, the water content of the dimethyl sulfoxide sample is less than or equal to 0.01%; and in some embodiments, the water content of the dimethyl sulfoxide sample is less than 0.01%.

[0018] In some embodiments, the purified product of the dimethyl sulfoxide is an electronic-grade product.

[0019] In some embodiments, the water content of the purified product of dimethyl sulfoxide is less than 0.01%; in some embodiments, the water content of the purified product of dimethyl sulfoxide is less than 0.005%; in some embodiments, the water content of the purified product of dimethyl sulfoxide is less than or equal to 0.001%; ​​in some embodiments, the water content of the purified product of dimethyl sulfoxide is less than 0.001%.

[0020] This patent offers the following advantages: High temperatures are avoided throughout the purification process; the temperature gradually decreases as the purification steps progress, effectively controlling the decomposition rate and ensuring product yield; complex devices such as falling film reboilers and circulating transport channels are avoided, while the pressure reduction requirements are relatively low, making the entire purification equipment simple and efficient; a simple solution achieves high-level purification of samples, meeting the standards for electronic-grade products; even crude products with low purity can be refined to obtain products of the expected purity through minor improvements. Attached Figure Description

[0021] Figure 1 This represents the purification process flow diagram. The components are: 1. Reduced pressure distillation unit; 2. Primary purification tank; 3. Refined purification tank; 4. Product storage tank; 5. Perfluorosulfonic acid cation exchange membrane; 6. Gas inlet; 7. Temperature sensor.

[0022] Figure 2 This is a schematic diagram showing the shape of a perfluorosulfonic acid type cation exchange membrane. Figure 2 A is a smooth, wavy shape; Figure 2 B is a folded, wavy shape. Detailed Implementation

[0023] The following description of specific embodiments further illustrates this application, but it is not intended to limit the scope of this disclosure. Those skilled in the art can make various modifications or improvements based on the teachings of this application without departing from its basic ideas and scope. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0024] Dimethyl sulfoxide sample 1 (crude product, purity 90%, water content less than 0.01%) was added to vacuum distillation apparatus 1 (equipped with a stirrer, vacuum device, heating and temperature control device) and vacuum distilled at 145℃ and 30KPa. The vapor phase was introduced from the bottom of the primary purification tank 2. The primary purification tank 2 is circular and has square perfluorosulfonic acid type cation exchange membranes 5 arranged perpendicular to the vapor phase flow direction. The top of the primary purification tank 2 is connected to the top of the purification tank 3. Nitrogen gas at 4℃ was injected at low pressure through the air inlet 6 at the bottom of the side wall of the purification tank 3. A temperature sensor 7 was installed at the bottom of the purification tank 3 to form a pressure difference between the top and the bottom. The pressure was set so that the vapor phase at the top could smoothly enter the purification tank 3 and form a purified product of dimethyl sulfoxide at a temperature of about 15℃ at the bottom. If the temperature was too high, the nitrogen pressure at the bottom was increased; if the temperature was too low, the nitrogen pressure at the bottom was decreased.

[0025] Different purification tanks (group 3) were set up, each containing solid particles of sulfonic acid-type cation exchange resin with particle sizes of 5 mm, 3 mm, 2 mm, 1.5 mm, 1 mm, and 0.5 mm, respectively. Samples were collected from the bottom of purification tanks (group 3), and the purity of dimethyl sulfoxide was determined using gas chromatography.

[0026] The results are shown in Table 1. The purity was 99.86% and 99.55% when the particle size was 3 mm and 2 mm, respectively, both exceeding 99.50%. It was possible to obtain a dimethyl sulfoxide sample with relatively high purity. When the particle size was too large, the adsorption and purification may not be sufficient. When the particle size was too small, it was speculated that the cooling was incomplete and degradation and other adverse factors may occur.

[0027] Table 1. Results of Initial Purity Measurement resin particles Product purity 5mm particle size 95.22% Particle size 3mm 99.76% Particle size 2mm 99.69% Particle size 1.5mm 99.02% Particle size 1mm 98.01% Particle size 0.5mm 98.84%

[0028] To verify the applicability of the two preferred particle sizes of 3 mm and 2 mm obtained in Example 1, dimethyl sulfoxide samples with purities of 85% and 95% were purified according to the method in Example 1, and the purity was detected using the same method. Then, trace metal ions were detected using ICP.

[0029] The purity test results are shown in Table 2. Both 3mm and 2mm particle sizes can increase the purity of low-purity samples by more than 8%, and purify high-purity samples to nearly 99.9%. It is speculated that the two 2-3mm particle sizes are the most ideal choices under the current purification conditions. The metal ion detection results show that the detection values ​​of most product ions are close to the electronic grade DMSO standard. The ions with poor removal effects are iron, copper, and nickel, which may be because the adsorption effect of these ions decreases when the resin particle size is larger.

[0030] Table 2. Results of Initial Purity Measurement Group resin particles Sample purity Product purity 1 Particle size 3mm 85% 93.22% 2 Particle size 2mm 85% 94.46% 3 Particle size 3mm 95% 99.85% 4 Particle size 2mm 95% 99.89% Table 3. Detection results of metal ions metal ions Group 1 product Group 2 products Group 3 products Group 4 products Sodium / ppb 0.313 1.300 0.313 0.981 Potassium / ppb 2.221 2.128 0.221 0.112 Iron / ppb 12.218 10.117 3.112 4.254 Copper / ppb 1.091 2.117 1.121 2.766 Nickel / ppb 1.118 1.221 1.001 1.251 Magnesium / ppb 1.009 1.010 1.101 0.760 Aluminum / ppb 0.161 1.110 / 0.011 Calcium / ppb 1.875 0.802 0.120 0.208 Manganese / ppb 0.108 0.108 0.015 0.019 Lead / ppb 0.002 0.012 0.001 0.002 Note: / indicates not detected.

[0031] Even with a sample purity of 95%, it is currently impossible to purify to 99.99% electronic purity, and the concentration of some metal ions is also below expectations. Therefore, the purification steps in Example 1 were further improved. First, the square perfluorosulfonic acid cation exchange membrane, which was arranged perpendicular to the vapor flow direction in the primary purification tank, was changed to be placed at a 45-degree angle to the vapor flow direction, while maintaining the square shape, to facilitate a more uniform and rapid flow of the vapor over the exchange membrane surface. At the same time, the resin composition of the purification tank was adjusted. The original resin was placed in the upper half, and a mixed resin component consisting of copper-nickel chelating resin CH-90Na (Kehaisi) and iron-removing resin T-IRR (Kehaisi) was placed in the lower half. Other purification and detection conditions were performed as described in Examples 1 and 2.

[0032] The purity of DMSO and the results of metal ion detection are shown in Tables 4-5. The results show that, after the improved purification steps, even crude products with low purity can achieve a purity close to the electronic grade. Samples with high purity not only have all their purity purified to the electronic grade, but also all their metal ions meet the electronic grade standard. Even the metal ions after purification of the crude product basically meet the electronic grade standard.

[0033] Table 2. Results of Initial Purity Measurement Group resin particles Sample purity Product purity 1 Particle size 3mm 85% 99.95% 2 Particle size 2mm 85% 99.96% 3 Particle size 3mm 95% 99.99% 4 Particle size 2mm 95% 99.99% Table 3. Detection results of metal ions metal ions Group 1 product Group 2 products Group 3 products Group 4 products Sodium / ppb 0.017 0.398 0.203 / Potassium / ppb 0.921 / 0.024 / Iron / ppb / / / / Copper / ppb 0.001 0.127 / / Nickel / ppb 0.301 / / / Magnesium / ppb 0.089 0.414 0.008 0.197 Aluminum / ppb 0.001 / / / Calcium / ppb 1.138 0.102 0.010 / Manganese / ppb 0.016 / / / Lead / ppb / / / / Note: / indicates not detected.

[0034] The purification method established in Example 3 can meet the purification requirements of most dimethyl sulfoxides. Conventional methods, by superimposing and cyclically repeating some purification steps, can achieve high-purity extraction of the crude product. However, this obviously complicates the purification process, increases equipment complexity and operating costs, and may disrupt the balance of income and expenditure. Therefore, we attempted to establish a low-cost, improved purification method, that is, to avoid introducing as many steps and equipment as possible based on Example 3.

[0035] During the exploration of the method in Example 3, we found that the placement of the exchange membrane in the primary purification tank also had a significant impact on the results. Therefore, we tried adjusting the placement angle of the exchange membrane (including 30, 45, 60, and 90 degrees). The detection results still showed that 45 degrees was optimal, and 30-60 degrees was also significantly better than 90 degrees. If, after purification in groups 1 and 2, the products at the beginning and end of the purification process are discarded and only the intermediate purified products are retained, electron-grade products can also be achieved. However, this may result in product waste. Even if the products are recycled, additional recycling equipment is required, thereby increasing costs.

[0036] Therefore, we returned to optimizing the exchange membrane and resin particles. After experimentation, replacing the flat exchange membrane with a smooth, wavy shape and then a folded wavy shape, resulted in both groups 1 and 2 achieving a purity of 99.99%, with metal ion and water content reaching electronic grade levels. This demonstrates that increasing the contact area is highly beneficial for purification. Purifying from 99.95% industrial grade to 99.99% electronic grade typically requires complex steps, but this patent's small modification achieves highly efficient purification from crude to electronic grade products, undoubtedly representing an innovation with significant advantages in cost and ease of operation.

[0037] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for purifying dimethyl sulfoxide, characterized in that, Includes the following steps: 1) Add the dimethyl sulfoxide sample into a vacuum distillation apparatus and obtain the dimethyl sulfoxide vapor phase separator by vacuum distillation; 2) Input the vapor phase separator into the primary purification tank from the bottom; 3) The top of the primary purification tank is connected to the top of the refined purification tank. The vapor phase separation product of the initial purification is fed into the refined purification tank filled with solid particles of sulfonic acid cation exchange resin from the top, and the purified product of dimethyl sulfoxide is collected from the bottom.

2. The method according to claim 1, characterized in that, The vacuum fractionation conditions are 130-150℃ and 10-40KPa.

3. The method according to claim 2, characterized in that, The initial purification tank is equipped with perfluorosulfonic acid type cation exchange membranes arranged at a 30-60 degree angle to the vapor flow direction; preferably, the arrangement angle is 45 degrees.

4. The method according to claim 3, characterized in that, The primary purification tank has a gap between its wall and the perfluorosulfonic acid cation exchange membrane to facilitate the smooth passage of vapor phase separators.

5. The method according to claim 4, characterized in that, The purification tank has an air inlet at the bottom of its side wall. Low-temperature nitrogen gas is injected into the tank at a low pressure through the air inlet. A temperature sensor is installed at the bottom of the purification tank. A pressure difference is formed between the top and the bottom. The purification tank is designed so that the vapor phase at the top can smoothly enter the purification tank and form a low-temperature dimethyl sulfoxide purification product uniformly at the bottom.

6. The method according to claim 5, characterized in that, The low-temperature nitrogen gas is specifically nitrogen gas at 4°C, and the low-temperature dimethyl sulfoxide purification product is specifically a dimethyl sulfoxide purification product at a temperature of approximately 15°C.

7. The method according to claim 6, characterized in that, The purification tank contains solid particles of sulfonic acid-type cation exchange resin with a particle size range of 0.5-5 mm; preferably, the particle size is selected to be 2-3 mm.

8. The method according to claim 7, characterized in that, The purification tank is also filled with copper-nickel chelating resin and iron-removing resin.

9. The method according to claim 8, characterized in that, The perfluorosulfonic acid type cation exchange membrane is wavy.

10. The method according to claim 9, characterized in that, The purified dimethyl sulfoxide product is an electronic-grade product.

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