A method for removing the odor of thiodipropionic acid

Abstract

The present application relates to the technical field of antioxidant preparation, and particularly relates to a method for removing the smell of thiodipropionic acid. The method comprises the following steps: preparing thiodipropionic acid solution by adding water to thiodipropionic acid, then passing water vapor to perform steam stripping, then passing ozone to perform oxidation treatment, and then performing cooling crystallization, centrifugation and drying. The method can improve the smell stability of thiodipropionic acid during storage.

Description

Technical Field

[0001] This invention relates to the field of antioxidant preparation technology, specifically to a method for deodorizing thiodipropionic acid. Background Technology

[0002] Thiodipropionic acid is a key intermediate in the synthesis of thiodipropionic acid ester antioxidants and is also used as a metal extractant. Currently, the main production processes for thiodipropionic acid both domestically and internationally are the acrylonitrile process and the acrylic acid process.

[0003] The acrylonitrile process mainly uses acrylonitrile and hydrogen sulfide as raw materials to synthesize thiodipropionitrile via catalytic addition, followed by hydrolysis to obtain thiodipropionic acid; or it uses acrylonitrile and sodium sulfide as raw materials, obtaining thiodipropionitrile by dropwise addition of acrylonitrile to a sodium sulfide solution, followed by hydrolysis to obtain thiodipropionic acid. The acrylic acid process mainly uses acrylic acid and hydrogen sulfide as raw materials to synthesize sodium thiodipropionate in the presence of sodium hydroxide, followed by acidification to obtain thiodipropionic acid; or it uses acrylic acid and sodium sulfide as raw materials, reacting and then crystallizing with water after acidification to obtain thiodipropionic acid.

[0004] Thiodipropionic acid prepared using existing processes develops an irritating odor after being stored for a period of time, affecting downstream applications. The inventors of this application conducted an in-depth analysis of the odor source and discovered that the odor in thiodipropionic acid originates from sulfur-containing compounds with distinctive odors, such as thiophene, thiazole, and thiaran. Summary of the Invention

[0005] Based on existing technical problems and research, this application proposes a method for deodorizing thiodipropionic acid. By employing a combination of steam stripping and oxidant oxidation, sulfur-containing heterocyclic compounds such as thiophene, thiazole, and thioranin in thiodipropionic acid can be effectively removed, thereby effectively eliminating odors and ensuring the odor stability of thiodipropionic acid.

[0006] This invention provides a method for deodorizing thiodipropionic acid, specifically comprising:

[0007] Thiodipropionic acid is dissolved in water to prepare a thiodipropionic acid solution. Steam is then introduced into the solution to perform steam stripping, removing easily volatile small-molecule odorous impurities. An oxidant is then added to perform an oxidation reaction to remove poorly volatile odorous impurities. The solution is then cooled and crystallized, centrifuged, and dried to obtain deodorized thiodipropionic acid.

[0008] The oxidant mentioned is O3.

[0009] Preferably, the steam injection rate is 0.5 to 5 times the mass of thiodipropionic acid, and the stripping time is 1-2 hours. Too little steam will not achieve a good deodorization effect, while too much steam will cause product loss.

[0010] Preferably, the amount of water used in the thiodipropionic acid solution is twice the mass of the thiodipropionic acid.

[0011] Preferably, the amount of O3 added is 0.1 to 0.5 times that of thiodipropionic acid, based on molar amounts.

[0012] Preferably, during the oxidation reaction, the oxidation temperature is 60–95°C and the oxidation time is 0.5–2 h.

[0013] Preferably, in the cooling crystallization process, the crystallization temperature is 10–30°C, and the crystallization time is 1–4 hours. A shorter time is chosen when the crystallization temperature is low, and a longer time is chosen when the crystallization temperature is high.

[0014] Preferably, the drying process involves a drying temperature of 80–105°C and a drying time of 2–6 hours. Lower drying temperatures require a longer drying time, while higher drying temperatures require a shorter drying time.

[0015] In this invention, thiodipropionic acid undergoes a combination of steam stripping and ozone oxidation for deodorization, resulting in a significant reduction in odor. The deodorization effect is superior to using ozone oxidation or steam stripping alone, with a high yield and a simple method. Furthermore, the deodorized thiodipropionic acid exhibits significantly improved odor stability during long-term storage. Detailed Implementation

[0016] The following detailed embodiments further illustrate the above-described content of the present invention, but should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0017] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available products, obtained by purchasing from the market or preparing the same batch of thiodipropionic acid from other literature; the ozone generator brand is Absolute Ozone, model ATLASH 30, the gas source is O2, and the ozone concentration is 22%.

[0018] Example 1

[0019] 100g of thiodipropionic acid was dissolved in 200g of water, and steam was introduced at a flow rate of 50g / h for 1h. The reaction system temperature was then controlled at 60℃, and O3 concentration was introduced at a flow rate of 25g / h for 0.5h. After the reaction was completed, the temperature was lowered to 10℃ and kept at that temperature for 1h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 80℃ for 6h to obtain 94.2g of deodorized thiodipropionic acid, with a yield of 94.2%.

[0020] Example 2

[0021] 100g of thiodipropionic acid was dissolved in 200g of water, and steam was introduced at a flow rate of 150g / h for 1.5h. The reaction system temperature was then controlled at 80℃, and O3 concentration was introduced at a flow rate of 30g / h for 1h. After the reaction was completed, the temperature was lowered to 20℃ and kept at that temperature for 2.5h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 90℃ for 4h to obtain 94.8g of deodorized thiodipropionic acid, with a yield of 94.8%.

[0022] Example 3

[0023] 100g of thiodipropionic acid was dissolved in 200g of water, and steam was introduced at a flow rate of 250g / h for 2h. The reaction system temperature was then controlled at 95℃, and O3 concentration was introduced at a flow rate of 30g / h for 2h. After the reaction was completed, the temperature was lowered to 30℃ and kept at that temperature for 4h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 105℃ for 2h to obtain 93.9g of deodorized thiodipropionic acid, with a yield of 93.9%.

[0024] Comparative Example 1

[0025] 100g of thiodipropionic acid was dissolved in 200g of water, and steam was introduced at a flow rate of 50g / h for 0.8h. The reaction system temperature was then controlled at 80℃, and O3 concentration was introduced at a flow rate of 30g / h for 0.3h. After the reaction was completed, the temperature was lowered to 20℃ and kept at that temperature for 2.5h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 90℃ for 4h to obtain 93.1g of deodorized thiodipropionic acid, with a yield of 93.1%.

[0026] Comparative Example 2

[0027] 100g of thiodipropionic acid was dissolved in 200g of water, and steam was introduced at a flow rate of 250g / h for 3h. The reaction system temperature was then controlled at 80℃, and O3 concentration was introduced at a flow rate of 30g / h for 2.5h. After the reaction was completed, the temperature was lowered to 20℃ and kept at that temperature for 2.5h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 90℃ for 4h to obtain 90.4g of deodorized thiodipropionic acid, with a yield of 90.4%.

[0028] Comparative Example 3

[0029] 100g of thiodipropionic acid was dissolved in 200g of water without steam stripping. The reaction system temperature was 80℃, the O3 concentration was 22%, the flow rate was 30g / h, and the oxidation time was 1h. After the reaction was completed, the temperature was lowered to 20℃ and kept at that temperature for 2.5h. The mixture was then centrifuged to constant weight, and the wet material was vacuum dried at 90℃ for 4h to obtain 92.6g of deodorized thiodipropionic acid, with a yield of 92.6%.

[0030] Comparative Example 4

[0031] 100g of thiodipropionic acid was dissolved in 200g of water. Without ozone oxidation, only steam was introduced at a flow rate of 150g / h for 1.5h. The solution was then cooled to 20℃ and kept at that temperature for 2.5h. After centrifugation to constant weight, the wet material was vacuum dried at 90℃ for 4h to obtain 91.7g of deodorized thiodipropionic acid, with a yield of 91.7%.

[0032] Comparative Example 5

[0033] The same thiodipropionic acid is not treated with any deodorization.

[0034] The thiodipropionic acid of Examples 1-3 and Comparative Examples 1-5 of this application was sealed and stored for different periods of time for odor testing. Odor determination method:

[0035] Five evaluators were asked to assess the odor, and the average of the results was taken as the odor value of the corresponding product.

[0036] The odor rating is between 1 and 6: 1 is an imperceptible odor; 2 is a slightly perceptible odor with no interference; 3 is a clearly perceptible odor with no interference; 4 is an odor that causes interference; 5 is an odor that causes strong interference; and 6 is an odor that is intolerable. The average value is taken as the result of the odor rating.

[0037] An evaluation was conducted at regular intervals, and the results are shown in Table 1 below.

[0038] Table 1. Odor stability of thiodipropionic acid in the examples and comparative examples.

[0039]

[0040] As shown in the table above, the odor of thiodipropionic acid is significantly reduced after a combination of ozone oxidation and steam stripping. The deodorization effect is better than that of ozone oxidation or steam stripping alone, and the odor stability during long-term storage is also significantly improved.

[0041] Those skilled in the art can refer to the content of this document and appropriately improve the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and fall within the scope of this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

Claims

1. A method for deodorizing with thiodipropionic acid, characterized in that, Specifically, it includes: Thiodipropionic acid is dissolved in water to prepare a thiodipropionic acid solution. Steam is then introduced into the solution to perform steam stripping, removing easily volatile small-molecule odorous impurities. An oxidant is then added to perform an oxidation reaction to remove poorly volatile odorous impurities. The solution is then cooled and crystallized, centrifuged, and dried to obtain deodorized thiodipropionic acid. The oxidant is O3.

2. The method for deodorizing thiodipropionic acid according to claim 1, characterized in that, The steam flow rate is 0.5 to 5 times the mass of thiodipropionic acid, and the stripping time is 1-2 hours.

3. The method for deodorizing thiodipropionic acid according to claim 1, characterized in that, The amount of O3 added is 0.1 to 0.5 times that of thiodipropionic acid, based on molar amounts.

4. The deodorization method for thiodipropionic acid according to claim 1, characterized in that, During the oxidation reaction, the oxidation temperature is 60–95℃ and the oxidation time is 0.5–2h.

5. The method for deodorizing thiodipropionic acid according to claim 1, characterized in that, The cooling crystallization process described herein involves a crystallization temperature of 10–30°C and a crystallization time of 1–4 hours.

6. The deodorization method for thiodipropionic acid according to claim 1, characterized in that, The drying process involves a drying temperature of 80–105℃ and a drying time of 2–6 hours.

7. The deodorization method for thiodipropionic acid according to claim 1, characterized in that, The amount of water used in the thiodipropionic acid solution is twice the mass of the thiodipropionic acid.

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