A method of extracting an intermediate ACH

Abstract

This invention discloses a method for extracting the intermediate ACH, belonging to the field of fine chemicals. The method involves passing a layered acid containing acesulfame potassium (DCM) and a dichloromethane solution into a rotary extraction tower for extraction. The temperature of the layered acid entering the tower is 30-31°C. The extraction pressure and the temperature of the dichloromethane entering the tower are controlled. The extracted dichloromethane layer enters a vibrating extraction tower for back-extraction with deionized water. The back-extracted DCM is neutralized, concentrated, crystallized, and dried to obtain the finished product, potassium acesulfame potassium. Using this method, the ACH content in the extracted acid is reduced to below 0.1%, and the ACH extraction yield reaches over 98%. Because the rotary extraction tower effectively reduces the acid carryover in the DCM, it lowers the back-extraction load, ensuring the product quality of potassium acesulfame potassium. Simultaneously, it simplifies the process conditions, reduces energy consumption, and saves production costs.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for extracting acesulfame potassium (intermediate ACH) from the layered acid produced in the hydrolysis step of the acesulfame potassium preparation process. Background Technology

[0002] Acesulfame K has received widespread attention as the world's fourth-generation synthetic sweetener. Acesulfame K is a colorless or white, odorless crystalline powder with a strong sweet taste; it is readily soluble in water and slightly soluble in ethanol, with a sweetness 200 times that of sucrose. Acesulfame K exhibits good light and heat stability (withstanding temperatures up to 225°C) and a wide applicable pH range (Ph=3-7), making it one of the most stable sweeteners in the world. It is suitable for baked goods, acidic beverages, jellies, desserts, and more.

[0003] Currently, the main raw materials used in production are sulfamic acid, triethylamine, diketene, sulfur trioxide, and glacial acetic acid. These react to produce triethylamine acetoacetaminophen, which is then ring-closed with sulfur trioxide to obtain acesulfame potassium, which reacts with potassium hydroxide to produce acesulfame potassium. In this method, excess SO3 reacts with water to form sulfuric acid, creating an acid layer containing ACH. Existing methods extract ACH from this acid layer through batch extraction or a packed tower at room temperature. This method suffers from low extraction efficiency, high residual ACH content in the extracted acid, and low atom economy. Patent CN104225956B provides a forced circulation extraction method in acesulfame potassium production. The extractant and hydrolyzed acid are simultaneously injected into a forced circulation pump. The pump is then turned on, and the thoroughly mixed solution is pumped into an extraction mixer. This method suffers from high energy consumption, and the extraction solution needs to be further separated in a separator, making the method complex. Therefore, a more efficient method for extracting the intermediate ACH is needed.

[0004] Rotary disc extraction towers are widely used in the chemical, food, and pharmaceutical industries as a separation and extraction device. They not only have high mass and heat transfer efficiency, enabling rapid separation and extraction of target substances, but also good stability and reliability, allowing for long-term stable operation and maintaining high separation efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for extracting the intermediate ACH from the layered acid produced in the hydrolysis step of the acesulfame potassium preparation process, addressing the aforementioned technical problems. This invention involves passing a layered acid containing acesulfame potassium and a dichloromethane solution into a rotary extraction tower for extraction, controlling the extraction temperature and pressure, and then back-extracting the extracted dichloromethane layer with deionized water. This method not only effectively reduces the acid carryover in the dichloromethane layer and lowers the back-extraction load, but also removes SO4 from the back-extracted dichloromethane. 2-With a content below 10 ppm, the product quality of acesulfame potassium is ensured. At the same time, the process conditions are simplified, energy consumption is reduced, and production costs are saved.

[0006] The technical solution adopted in this invention involves passing a layered acid containing acesulfame potassium (ACH) produced during the hydrolysis step of the acesulfame potassium preparation process into a rotary extractor for extraction. The temperature of the layered acid entering the extractor, the extraction pressure, and the temperature of the dichloromethane entering the extractor are controlled. The extracted dichloromethane layer is then back-extracted with deionized water. This invention utilizes a rotary extractor, controlling the temperature of the layered acid entering the extractor, the temperature of the dichloromethane entering the extractor, and the extraction pressure to reduce the ACH content in the extracted acid to below 0.1%, achieving an ACH extraction yield of over 98%. Because the rotary extractor effectively reduces the acid carryover in the dichloromethane solution (DCM), it lowers the back-extraction load, ensuring the product quality of acesulfame potassium. Simultaneously, it simplifies the process conditions, reduces energy consumption, and saves production costs.

[0007] Specifically, the present invention provides a method for extracting intermediate ACH from the layered acid produced in the hydrolysis step of the acesulfame preparation process, which includes the following steps:

[0008] (1) The layered acid is provided, which contains sulfuric acid, ACH and water;

[0009] (2) The layered acid and dichloromethane are passed into a rotary extraction tower for extraction to obtain a dichloromethane extract containing ACH and the extracted acid;

[0010] (3) The dichloromethane extract containing ACH is back-extracted with water (e.g., deionized water) to obtain a dichloromethane solution containing ACH.

[0011] In one embodiment of the present invention, the ACH content of the layered acid is 2.0-3.0%, for example 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, or 2.9%.

[0012] In one embodiment of the present invention, the mass ratio of the amount of dichloromethane used to the amount of the layering acid used is 1:1-8:1, for example 2:1, 3:1, 4:1, 5:1, 6:1, or 7:1.

[0013] In one embodiment of the present invention, the extraction pressure in the rotary extraction tower is 0.1-0.5 MPa, for example 0.2, 0.3, or 0.4 MPa.

[0014] In one embodiment of the present invention, the temperature at which the stratified acid enters the rotary extraction tower is 30-35°C, for example, 31, 32, 33, or 34°C.

[0015] In one embodiment of the present invention, the temperature at which the dichloromethane enters the rotary extraction tower is 20-45°C, for example 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44°C.

[0016] In one embodiment of the present invention, the vibration frequency of the rotary extraction tower is 100-500 r / min, for example 150, 200, 250, 300, 350, 400, 450 r / min.

[0017] In one embodiment of the present invention, in step (3), the mass ratio of the dichloromethane extract containing ACH to water is 100 to 50:1, for example 100:1, 75:1, 50:1.

[0018] In one embodiment of the present invention, the temperature for step (3) is 10-30°C.

[0019] In one embodiment of the invention, the dichloromethane extract containing ACH has an ACH extraction rate of more than 98% relative to the ACH extraction rate of the layered acid, for example, 98-99.9% or 98.1%, 98.5%, 99%, 99.5%, or 99.7%.

[0020] In one embodiment of the invention, the SO4 in the dichloromethane solution containing ACH 2- The content is less than 10 ppm, for example, 4-10 ppm or 5, 6, 7, 8, 9 ppm.

[0021] In one embodiment of the present invention, the ACH content of the extracted acid is less than or equal to 0.05%, for example 0.01-0.05% or 0.02, 0.03, or 0.04%.

[0022] In one embodiment of the present invention, the dichloromethane solution containing ACH is further subjected to neutralization, concentration, crystallization and drying to obtain the finished product acesulfame potassium.

[0023] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0024] This invention employs a rotary disc extraction column. By controlling the extraction temperature and pressure within the column, the extraction yield of ACH is effectively improved; the acid carryover in DCM is reduced, lowering the back-extraction load and decreasing the SO4 content in dichloromethane after back-extraction. 2- The content is no higher than 10 ppm, ensuring the product quality of acesulfame potassium. At the same time, it simplifies the process conditions, reduces energy consumption, and saves production costs. Attached Figure Description

[0025] Figure 1 The process flow diagrams are for Examples 1-6. Detailed Implementation

[0026] The present invention will be described in more detail below with reference to the embodiments. These embodiments are merely descriptions of the best mode of implementation of the present invention and do not limit the scope of protection of the present invention in any way.

[0027] Example 1

[0028] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the preparation of acesulfame K, is fed into a rotary extractor at the top feed port at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom at a temperature of 38-39°C. The mass ratio of DCM to acid feed is 1:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.2 MPa and a vibration frequency of 300 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.01%, and the extraction yield of ACH in DCM reaches 99.6%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 100:1) at a temperature of 20°C. The SO42- in the dichloromethane after back-extraction is then removed. 2- The content is 4 ppm.

[0029] Example 2

[0030] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the acesulfame K preparation process, is fed into a rotary extractor at the top feed port at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom at a temperature of 30-31°C. The mass ratio of DCM to acid feed is 2:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.1 MPa and a vibration frequency of 300 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.02%, and the ACH extraction yield in DCM reaches 99.3%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 75:1) at a temperature of 10°C. The SO42- in the dichloromethane after back-extraction is then removed. 2- The content is 6 ppm.

[0031] Example 3

[0032] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the preparation of acesulfame K, is fed into a rotary extractor at the top feed port at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom at a temperature of 44-45°C. The mass ratio of DCM to acid feed is 3:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.1 MPa and a vibration frequency of 200 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.03%, and the extraction yield of ACH in DCM reaches 98.9%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 50:1) at a temperature of 30°C. The SO42- in the dichloromethane after back-extraction is reduced. 2- The content is 7 ppm.

[0033] Example 4

[0034] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the preparation of acesulfame K, is fed into a rotary extractor at the top of the column at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom of the column at a temperature of 30-31°C. The mass ratio of DCM to acid is 4:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.2 MPa and a vibration frequency of 200 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.02%, and the extraction yield of ACH in DCM reaches 99.3%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 100:1) at a temperature of 30°C. The SO42- in the dichloromethane after back-extraction is then removed. 2- The content is 10 ppm.

[0035] Example 5

[0036] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the acesulfame K preparation process, is fed into a rotary extractor at the top feed port at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom at a temperature of 25-26°C. The mass ratio of DCM to acid feed is 5:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.2 MPa and a vibration frequency of 100 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.05%, and the ACH extraction yield in DCM reaches 98.2%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 75:1) at a temperature of 20°C. The SO42- in the dichloromethane after back-extraction is then removed. 2-The content is 8 ppm.

[0037] Example 6

[0038] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step in the preparation of acesulfame K, is fed into a rotary extractor at the top feed port at a temperature of 30-31°C. Dichloromethane (DCM) solution is fed from the bottom at a temperature of 20-21°C. The mass ratio of DCM to acid feed is 8:1. The two are subjected to countercurrent extraction in the rotary extractor at an extraction pressure of 0.5 MPa and a vibration frequency of 500 r / min. After continuous extraction, the ACH content in the extracted acid is reduced to 0.04%, and the extraction yield of ACH in DCM reaches 98.6%. The extracted DCM layer is then back-extracted in a vibrating extractor with deionized water (mass ratio 50:1) at a temperature of 10°C. The SO42- in the dichloromethane after back-extraction is then removed. 2- The content is 9 ppm.

[0039] Comparative Example 1

[0040] A layered acid containing acesulfame K (ACH: 2.8%), produced from the hydrolysis step of the acesulfame K preparation process, and a dichloromethane solution were added to a packed column. The inlet temperature of the layered acid was 30-31℃, and the inlet temperature of the DCM solution was 38-39℃. The mass ratio of DCM to acid feed was 1:1. The two were subjected to countercurrent extraction in the packed column at an extraction pressure of 0.2 MPa. After continuous extraction, the ACH content in the extracted acid was 0.25%, and the extraction yield of ACH in DCM reached 91%. The extracted DCM layer was then back-extracted with deionized water (mass ratio 100:1) at 20℃. The SO42- in the dichloromethane after back-extraction was... 2- The content is 50 ppm.

[0041] Table 1

[0042]

Claims

1. A method for extracting intermediate ACH from the layered acid produced in the hydrolysis step of the acesulfame preparation process, comprising the following steps: (1) The layered acid is provided, which contains sulfuric acid, ACH and water; (2) The layered acid and dichloromethane are passed into a rotary extraction tower for extraction to obtain a dichloromethane extract containing ACH and the extracted acid; (3) The dichloromethane extract containing ACH is back-extracted with water to obtain a dichloromethane solution containing ACH.

2. The method of claim 1, wherein the ACH content of the layered acid is 2.0-3.0%.

3. The method of claim 1 or 2, wherein The mass ratio of the amount of dichloromethane used to the amount of the stratifying acid used is 1:1 to 8:1; and / or The extraction pressure in the rotary extraction tower is 0.1-0.5 MPa; and / or The temperature at which the stratified acid enters the rotary extractor is 30-35°C; and / or The temperature at which the dichloromethane enters the rotary extractor is 20-45°C; and / or The vibration frequency of the rotary extraction tower is 100-500 r / min.

4. The method of any one of claims 1-3, wherein In step (3), the mass ratio of the dichloromethane extract containing ACH to water is 100~50:1; and / or The temperature for step (3) is 10-30℃.

5. The method of any one of claims 1-4, wherein the dichloromethane extract containing ACH has an ACH extraction rate of more than 98% relative to the layered acid.

6. The process of any one of claims 1-5, wherein the ACH-containing dichloromethane solution has a SO4 content of no more than 10 ppm. 2- ppm.

7. The method of any one of claims 1-6, wherein the ACH content of the extracted acid is less than or equal to 0.05%.

8. The method of any one of claims 1-7, wherein the dichloromethane solution containing ACH is further subjected to neutralization, concentration, crystallization and drying to obtain the finished product acesulfame potassium.

Images