Preparation method for methanesulfonic acid with low sulfate radical residue

Abstract

A preparation method for methanesulfonic acid with low sulfate radical residue. The method comprises the following steps: in a tank reactor, taking dimethyl disulfide having the content of dimethyl polysulfide lower than 350 ppm, preferably lower than 220 ppm as a raw material, and enabling the dimethyl disulfide to react in the presence of a catalyst and an oxidizing agent; and after the reaction is completed, carrying out post-treatment on a reaction liquid to obtain methanesulfonic acid. By controlling the content of dimethyl polysulfide in the raw material, the problem that the content of sulfate radicals in a methanesulfonic acid product is high can be solved, the obtained product has high quality, the content of heavy component impurities is also remarkably reduced, the product yield is increased, and a heavy component removal process is simplified or energy consumption is reduced.

Description

A method for preparing methanesulfonic acid with low sulfate residue Technical Field

[0001] The present application relates to a preparation method, for example, a method for preparing methanesulfonic acid with low sulfate residue. Background Art

[0002] Methanesulfonic acid, a strong organic acid, has broad market demand in industrial cleaning, electronic electroplating, organic synthesis, and other fields. The current mainstream production process for methanesulfonic acid uses dimethyl disulfide as the starting material, which is then oxidized with strong oxidants such as nitric acid. Studies have found that this oxidation process generates a certain amount of sulfate and heavy impurities. After the oxidation product is stripped of light components such as nitric acid, it must be further refined to remove the sulfate and heavy impurities. This not only consumes a lot of energy, but some sulfate inevitably evaporates with the product, resulting in residual sulfate levels in the product generally exceeding 50 ppm, and even reaching several thousand ppm, significantly affecting product quality. In the field of electronic electroplating, in particular, the presence of large amounts of sulfate makes it easier to generate plating slag during the electroplating process. Furthermore, in higher-end silicon wafer plating solutions, the product must undergo repeated purification to meet usage requirements, which poses significant challenges to industrial application.

[0003] Therefore, it is necessary to develop new process conditions to reduce the content of sulfate and heavy component impurities in methanesulfonic acid as much as possible.

[0004] Summary of the Invention

[0005] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0006] To address the above technical issues, the present application proposes a method for preparing methanesulfonic acid with low sulfate residue. By controlling the content of dimethyl polysulfide in the raw material, the present application can address the problem of high sulfate content in the methanesulfonic acid product. The resulting product is of high quality and the content of heavy impurities is significantly reduced. This not only improves product yield but also facilitates the simplification of the desulfurization process and reduces energy consumption.

[0007] A method for preparing methanesulfonic acid with low sulfate residue, characterized in that it comprises the following steps:

[0008] In a tank reactor, dimethyl polysulfide with a content of less than 350 ppm, optionally less than 220 ppm, is used as a raw material and reacted in the presence of a catalyst and an oxidant; after the reaction is terminated, the reaction liquid is post-treated to obtain methanesulfonic acid.

[0009] Through continuous research, the applicant has found that due to the limitations of the raw material preparation process, dimethyl disulfide usually contains a certain amount of dimethyl polysulfide. Surprisingly, by controlling the content of dimethyl polysulfide, the applicant unexpectedly found that the sulfate content in the product has a decreasing trend, especially when the dimethyl polysulfide content is below 350 ppm, which has a significant advantage in reducing the sulfate content in the product. It is speculated that the presence of dimethyl polysulfide in the reaction system is a key factor in promoting the free radical reaction to produce sulfate. At the same time, further research found that when the dimethyl polysulfide content is controlled below 220 ppm, the amount of heavy components generated in the system is also significantly reduced, and the product yield is improved, thereby completing the present application.

[0010] The method for controlling the content of dimethyl polysulfide in the raw material dimethyl disulfide can be conventional distillation separation or other raw material deep purification methods, which does not limit the present application in any form.

[0011] In one embodiment, the catalyst is one or more of nitric acid, nitric oxide, and nitrogen dioxide.

[0012] In one embodiment, the catalyst content is 0.01-0.50% by weight of dimethyl disulfide.

[0013] In one embodiment, the oxidant is oxygen or air.

[0014] In one embodiment, the content of the oxidant is 3-15 times based on the molar amount of dimethyl disulfide.

[0015] In one embodiment, the dimethyl polysulfide includes at least one of dimethyl trisulfide and dimethyl tetrasulfide.

[0016] In one embodiment, the reaction temperature is 50-180° C., and the reaction gauge pressure is 0.1-1.0 MPa.

[0017] In one embodiment, the reaction is carried out in the presence of an optional solvent; the amount of the solvent used is, for example, 3-10 times the mass of dimethyl disulfide.

[0018] Optionally, the solvent is one or more of water, ethylene glycol, propylene glycol, N,N-dimethylformamide, and acetonitrile.

[0019] In one embodiment, the post-treatment of the reaction solution includes refined light removal and optionally refined heavy removal; wherein the refined light removal adopts the following conditions: 20-120° C., 10 KPa-0.1 MPa;

[0020] The refining and deweighting conditions are as follows: 120-230°C, 10Pa-0.1MPa.

[0021] The preparation method of the present application can produce high-quality methanesulfonic acid with a significantly reduced sulfate content, preferably less than 1 ppm, which is more suitable for applications in high-precision industries such as electronic electroplating. In addition, the product has a low content of heavy components, which makes it possible to simplify the subsequent deweighting process and has application advantages in saving production costs and reducing energy consumption. At the same time, the stability of the product is greatly improved. When stored at 60°C for one month, the increase in the product color number is less than 20.

[0022] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0023] The present application is further described below through specific examples. The examples described in this application are only used to illustrate the present application and do not limit the scope of the present application.

[0024] Unless otherwise specified, the raw materials and reagents in the following examples of this application can be purchased from commercial sources.

[0025] The main test methods used in this application are:

[0026] The content of dimethyl polysulfide is detected by gas chromatography using a polyethylene glycol column. Dimethyl disulfide is directly injected and vaporized, flows through the column, and the components are separated. Then, the components are detected by the detector. The peaks of each component are measured and quantitatively calculated using the calibration area normalization method. The specific chromatographic analysis conditions are as follows:

[0027] Table 1. Gas chromatography analysis conditions

[0028] The methanesulfonic acid content was tested by acid-base neutralization titration: phenolphthalein was used as the indicator solution and sodium hydroxide standard solution (1 mol / L) was used for neutralization titration until neutrality. The methanesulfonic acid content was calculated based on the amount of sodium hydroxide standard solution used.

[0029] Sulfate is determined by high performance ion chromatography: methanesulfonic acid sample is diluted 5-10 times with deionized water and then tested on an ion chromatography machine.

[0030] The color number is tested in accordance with the provisions of GB / T 1664.

[0031] [Example 1]

[0032] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide combined, 35 ppm total), 68% nitric acid, and water were added sequentially to a reactor, ensuring that the pure nitric acid added was 0.2% of the dimethyl disulfide mass and the water added was 5 times the mass of the dimethyl disulfide. Oxygen was then introduced at 5 times the molar amount of the dimethyl disulfide. The reactor was sealed and reacted at 120°C and 0.3 MPa for 1 hour. After completion of the reaction, sampling and testing revealed a dimethyl disulfide conversion rate exceeding 99%. The reaction solution was fed to a lightness removal tower, where light components such as nitric acid and water were removed at 100°C and 0.05 MPa. The resulting methanesulfonic acid product, with a purity of 99.9%, contained less than 1 ppm of sulfate and a product yield of 99.2%, was collected from the bottom of the tower. The product was stored at 60°C for 1 month, with an increase in color (APHA) of 9.

[0033] [Example 2]

[0034] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide, totaling 107 ppm), 68% nitric acid, and water were sequentially added to a reactor, ensuring that the pure nitric acid added was 0.3% of the dimethyl disulfide mass and the water added was 3 times the mass of the dimethyl disulfide. Oxygen was then introduced at 9 times the molar amount of the dimethyl disulfide. The reactor was sealed and reacted at 140°C and 0.8 MPa for 5 hours. After completion, sampling and testing revealed a dimethyl disulfide conversion rate exceeding 99%. The reaction solution was fed to a lightness removal tower, where light components such as nitric acid and water were removed at 80°C and 0.03 MPa. The resulting methanesulfonic acid product, with a purity of 99.5% and a sulfate content of 4 ppm, was collected from the bottom of the tower, yielding 98.9%. The product was stored at 60°C for one month, with an increase in color (APHA) of 15.

[0035] [Example 3]

[0036] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide, totaling 219 ppm) and water were added to a reactor in sequence, ensuring that the amount of water added was 5 times the mass of the dimethyl disulfide. Oxygen (7 times the molar amount of the dimethyl disulfide) and nitrogen dioxide (0.45% of the mass of the dimethyl disulfide) were then introduced. The reactor was sealed and reacted at 100°C and 0.7 MPa for 6 hours. After completion of the reaction, sampling and testing showed that the conversion rate of dimethyl disulfide was greater than 99%. The reaction liquid was sent to a lightness removal tower, where light components such as nitric acid and water were removed at 120°C and atmospheric pressure. The tower bottom was collected to obtain a 99.3% pure methanesulfonic acid product with 5 ppm sulfate and a product yield of 98.7%. The product was stored at 60°C for 1 month, and the color number (APHA) increased by 13.

[0037] [Example 4]

[0038] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide, totaling 235 ppm), 68% nitric acid, and water were sequentially added to a reactor, ensuring that the pure nitric acid added was 0.1% of the mass of the dimethyl disulfide and the water added was 7 times the mass of the dimethyl disulfide. Air at 15 times the molar amount of dimethyl disulfide was then introduced. The reactor was sealed and reacted at 120°C and 0.8 MPa for 10 hours. After completion, sampling and testing revealed a dimethyl disulfide conversion rate exceeding 99%. The reaction solution was fed to a lightness removal tower, where light components such as nitric acid and water were removed at 80°C and 0.2 MPa. The resulting methanesulfonic acid product, with a purity of 98.3% and a sulfate content of 7 ppm, was collected from the bottom of the tower, yielding 97.5%. The product was stored at 60°C for one month, with an increase in color (APHA) of 19.

[0039] [Example 5]

[0040] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide combined, 345 ppm total), 68% nitric acid, and water were sequentially added to a reactor, ensuring that the pure nitric acid added was 0.1% of the mass of the dimethyl disulfide and the water added was 7 times the mass of the dimethyl disulfide. Air at 15 times the molar amount of dimethyl disulfide was then introduced. The reactor was sealed and reacted at 120°C and 0.8 MPa for 10 hours. After completion, sampling and testing revealed a dimethyl disulfide conversion rate exceeding 99%. The reaction solution was fed to a lightness removal tower, where light components such as nitric acid and water were removed at 80°C and 0.2 MPa. The resulting methanesulfonic acid product, with a purity of 97.9% and a sulfate content of 9 ppm, was collected from the bottom of the tower, yielding 96.5%. The product was stored at 60°C for one month, with an APHA color increase of 26.

[0041] [Comparative Example 1]

[0042] Dimethyl disulfide (dimethyl trisulfide and dimethyl tetrasulfide, totaling 430 ppm), 68% nitric acid, and water were sequentially added to a reactor, ensuring that the pure nitric acid added was 0.2% of the dimethyl disulfide mass and the water added was 5 times the mass of the dimethyl disulfide. Oxygen was then introduced at 5 times the molar amount of the dimethyl disulfide. The reactor was sealed and reacted at 120°C and 0.3 MPa for 1 hour. After completion, sampling and testing revealed a dimethyl disulfide conversion rate exceeding 99%. The reaction liquid was fed to a lightness removal column to remove light components such as nitric acid and water at 100°C and 0.05 MPa. The bottoms were then fed to a heavyness removal column for purification by distillation at 170°C and 300 Pa. Methanesulfonic acid product with a purity of 97.2% and a sulfate content of 4300 ppm was obtained, yielding 86.7%. The product was stored at 60°C for 1 month, with an increase in color (APHA) to 589.

[0043] The above is only a preferred embodiment of the present application. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present application. These improvements and supplements should also be regarded as the scope of protection of the present application.

Claims

1. A preparation method of methanesulfonic acid with low sulfate residue, which comprises the following steps: In a kettle reactor, using dimethyl disulfide with a content of dimethyl polysulfide lower than 350 ppm as a raw material, reacting it in the presence of a catalyst and an oxidant; after the reaction is terminated, the reaction solution is post-treated to obtain methanesulfonic acid.

2. The preparation method of methanesulfonic acid with low sulfate residue according to claim 1, wherein, the content of dimethyl polysulfide in the dimethyl disulfide is lower than 220 ppm.

3. The preparation method of methanesulfonic acid with low sulfate residue according to claim 1 or 2, wherein, the catalyst is one or more of nitric acid, nitric oxide, and nitrogen dioxide.

4. The preparation method of methanesulfonic acid with low sulfate residue according to claim 3, wherein, the content of the catalyst is 0.01 - 0.50% of the weight of dimethyl disulfide.

5. The preparation method of methanesulfonic acid with low sulfate residue according to any one of claims 1 - 4, wherein, the oxidant is oxygen or air.

6. The preparation method of methanesulfonic acid with low sulfate residue according to claim 5, wherein, the content of the oxidant is 3 - 15 times the molar amount of dimethyl disulfide.

7. The preparation method of methanesulfonic acid with low sulfate residue according to any one of claims 1 - 6, wherein, the dimethyl polysulfide includes at least one of dimethyl trisulfide and dimethyl tetrasulfide.

8. The preparation method of methanesulfonic acid with low sulfate residue according to any one of claims 1 - 7, wherein, the temperature of the reaction is 50 - 180 °C, and the gauge pressure of the reaction is 0.1 - 1.0 MPa.

9. The preparation method of methanesulfonic acid with low sulfate residue according to any one of claims 1 - 8, wherein, the reaction is carried out in the presence of a solvent.

10. The preparation method of methanesulfonic acid with low sulfate residue according to claim 9, wherein, the solvent is one or more of water, ethylene glycol, propylene glycol, N, N - dimethylformamide, and acetonitrile.

11. The preparation method of methanesulfonic acid with low sulfate residue according to any one of claims 1 - 10, wherein, the post-treatment of the reaction solution includes refining and light component removal and optionally refining and heavy component removal; wherein, the refining and light component removal adopts the following conditions: 20 - 120 °C, 10 KPa - 0.1 MPa; the refining and heavy component removal adopts the following conditions: 120 - 230 °C, 10 Pa - 0.1 MPa.

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