A method for purifying bischlorosulfonylimide acid and bischlorosulfonylimide acid obtained by the method

Abstract

The application provides a purification method and dichloroisocyanurate obtained by using the method. The purification method of dichloroisocyanurate comprises the following steps: repeatedly crystallizing crude dichloroisocyanurate obtained in a production synthesis process to obtain purified dichloroisocyanurate. The purification method of dichloroisocyanurate of the application utilizes the different melting points of dichloroisocyanurate and other impurities, and is designed to be repeatedly crystallized at different gradient temperatures. By adjusting the crystallization temperature and the crystallization time, the impurities in the dichloroisocyanurate can be removed. Compared with the crude distillation method, the obtained dichloroisocyanurate has higher purity, and is safer and easier to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of purification of bischlorosulfonyl imide acid, and in particular to a purification method and the bischlorosulfonyl imide acid obtained by the method. Background Art

[0002] With the increasing market demand for lithium bis(fluorosulfonyl)imide, a novel lithium battery electrolyte, in recent years, the production process for its intermediate bis(chlorosulfonyl)imidic acid has become increasingly important. Currently, the industry faces the problem of low product purity after the synthesis of bis(chlorosulfonyl)imidic acid. Impurities such as chlorosulfonyl isocyanate and chlorosulfonic acid in the dichloro solution adversely affect subsequent reactions. Existing techniques purify bis(chlorosulfonyl)imidic acid by crude distillation at elevated temperatures. However, the bis(chlorosulfonyl)imidic acid obtained by crude distillation at elevated temperatures still contains a large number of impurities, resulting in insufficient purity. Therefore, the existing technology needs further development. Summary of the Invention

[0003] In view of the various deficiencies of the prior art and in order to solve the above problems, a purification method and bischlorosulfonyl imide acid obtained by the method are proposed, and the following technical solutions are provided:

[0004] The invention discloses a method for purifying bischlorosulfonyl imide acid. The crude bischlorosulfonyl imide acid obtained in the production and synthesis process is subjected to multiple crystallization purification to obtain purified bischlorosulfonyl imide acid.

[0005] Further, the crude bischlorosulfonyl imide acid is subjected to a first crystallization and a second crystallization to obtain purified bischlorosulfonyl imide acid.

[0006] Furthermore, the first crystallization is carried out by cooling the temperature from 120° C. to 140° C. to 36-37° C., which takes 5-6 hours.

[0007] Furthermore, the second crystallization is performed by cooling the temperature from 36-37° C. to 35-35.5° C., and then isothermally crystallizing at 35-35.5° C. for 2-3 hours.

[0008] Furthermore, after the second crystallization, the temperature is raised to 39-40° C. and maintained for 30-40 minutes to remove the mother liquor.

[0009] Furthermore, after removing the mother liquor, the bischlorosulfonyl imide acid is heated to 43-45° C. and maintained at 43-45° C. for 1.5-2 h to obtain purified bischlorosulfonyl imide acid.

[0010] Furthermore, the crude bischlorosulfonyl imide acid is fed into a static crystallizer for multiple crystallizations.

[0011] In addition, the present invention also provides a bischlorosulfonyl imide acid, which is obtained by the above-mentioned purification method of bischlorosulfonyl imide acid.

[0012] Beneficial effects:

[0013] 1. A method for purifying bischlorosulfonyl imide acid of the present invention utilizes the different melting points of bischlorosulfonyl imide acid and other impurities to design multiple crystallizations at different gradient temperatures. By regulating the crystallization temperature and crystallization time, impurities in the bischlorosulfonyl imide acid can be removed. Compared with the method of heating crude distillation, the obtained bischlorosulfonyl imide acid has higher purity and is safer and easier to operate.

[0014] 2. The purity of the bischlorosulfonyl imide acid obtained by the purification method of the bischlorosulfonyl imide acid of the present invention reaches 97.6%. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making any creative work should fall within the scope of protection of this application.

[0016] According to an embodiment of the present invention, a method for purifying bischlorosulfonyl imide acid is provided. The crude bischlorosulfonyl imide acid obtained during the production and synthesis process is subjected to multiple crystallization purification to obtain purified bischlorosulfonyl imide acid. Chlorosulfonic acid and chlorosulfonyl isocyanate are reacted, and chlorosulfonyl isocyanate is added dropwise to the chlorosulfonic acid to produce bischlorosulfonyl imide acid and carbon dioxide. After the dropwise addition is completed, the temperature is maintained until the reaction is complete, thereby obtaining bischlorosulfonyl imide acid. The melting point of bischlorosulfonyl imide is 37°C; the melting point of chlorosulfonic acid is -80°C; and the melting point of chlorosulfonyl isocyanate is -44°C. Taking advantage of the different melting points of bischlorosulfonyl imide acid and other impurities, multiple crystallizations are designed at different gradient temperatures. By regulating the crystallization temperature and crystallization time, impurities in the bischlorosulfonyl imide acid can be removed. Compared with the crude distillation method of increasing the temperature, the resulting bischlorosulfonyl imide acid has higher purity and is safer and easier to operate.

[0017] The purified disulfone acid is obtained after the first and second crystallization of the crude disulfone acid. The first crystallization is from 120-140°C to 36-37°C, which takes 5-6 hours, and the second crystallization is from 36-37°C to 35-35.5°C, which takes 2-3 hours. The process is carried out in stages, the first stage is the cooling stage, and too fast cooling speed will affect the equipment and cause the phenomenon of porcelain explosion; slow cooling will result in a low condensation rate on the surface and make it difficult to form large and good crystals. Therefore, 36-37°C for 5-6 hours is selected. The second crystallization is at 35-35.5°C for 2-3 hours. Compared with the mother liquor without this stage, the disulfone acid content in the mother liquor after further cooling for 2-3 hours can be reduced to 2-4%, and the disulfone acid content in the mother liquor without this stage can reach 15-18% (the disulfone acid content in the disulfone mother liquor obtained by using the crude distillation method is only 75-88%).

[0018] Example 1

[0019] The reaction completed disulfone is put into a static crystallizer, and heat conducting oil is used to cool the static crystallizer, the temperature is reduced from 120°C to 36°C in the first stage, which takes 6 hours. In the second stage, the heat conducting oil is used to continue cooling, the temperature is reduced from 36°C to 35°C, which takes 1.5 hours, the material temperature is at 35°C, and the holding time is 3 hours. After the crystallization is completed, the material is heated to 40°C at the bottom of the static crystallizer using heat conducting oil, and the mother liquor is discharged for 30 minutes. After the mother liquor is completed, the heat conducting oil is used to continue heating to 45°C, and the holding time is 1.8h. The high-purity disulfone crystal is dissolved and discharged into the purified product tank.

[0020] Example 2

[0021] The reaction completed disulfone is put into a static crystallizer, and heat conducting oil is used to cool the static crystallizer, the temperature is reduced from 140°C to 37°C in the first stage, which takes 5 hours. In the second stage, the heat conducting oil is used to continue cooling, the temperature is reduced from 37°C to 35.5°C, which takes 1 hour, the material temperature is at 35.5°C, and the holding time is 2 hours. After the crystallization is completed, the material is heated to 39°C at the bottom of the static crystallizer using heat conducting oil, and the holding time is 40 minutes, and the mother liquor is discharged. After the mother liquor is completed, the heat conducting oil is used to continue heating to 43°C, and the holding time is 1.5h. The high-purity disulfone crystal is dissolved and discharged into the purified product tank.

[0022] Example 3

[0023] The reacted bischlorosulfonyl imide was pumped into a static crystallizer and cooled using thermal oil. In the first stage, the temperature was lowered from 130°C to 36.5°C over 5.5 hours. In the second stage, thermal oil was used to continue cooling the temperature from 36.5°C to 35°C over 2 hours. The material temperature was maintained at 35°C for 2.5 hours. After crystallization was complete, thermal oil was used to raise the temperature of the material at the bottom of the static crystallizer to 39.5°C and hold it for 35 minutes. The mother liquor was then discharged. After the mother liquor was cleared, thermal oil was used to raise the temperature to 42°C and hold it for 2 hours. The high-purity bischlorosulfonyl imide crystals were dissolved and placed into a storage tank for the purified product.

[0024] Comparative Example 1

[0025] Open the pneumatic discharge valve at the bottom of the reactor and transfer the reaction liquid to a short steamer for vacuum distillation. Heat oil is supplied to the short steamer, maintaining the temperature at 125°C. A vacuum is applied to the short steamer to a pressure of -0.095 MPa to remove unreacted chlorosulfonic acid, chlorosulfonyl isocyanate, and the like. The resulting bischlorosulfonimide content after this step is 86.83%.

[0026] Comparative Example 2

[0027] The reacted bischlorosulfonyl imide was pumped into a static crystallizer and cooled using thermal oil from 130°C to 36°C over one hour. Isothermal crystallization was then performed at 36°C for six hours. Once crystallization was complete, the material was heated to 40°C at the bottom of the static crystallizer using thermal oil, and the mother liquor was discharged. After the mother liquor was purified, the temperature was further raised to 45°C using thermal oil, and the bischlorosulfonyl imide crystals were dissolved and placed in a storage tank for the purified product.

[0028] Comparative Example 3

[0029] The reacted bischlorosulfonyl imide was pumped into a static crystallizer and cooled using thermal oil. The first stage reduced the temperature from 130°C to 36.5°C over 5.5 hours. The second stage continued with thermal oil cooling, from 36.5°C to 35°C over 2 hours. The material temperature was maintained at 35°C for 2.5 hours. Upon completion of crystallization, the mother liquor was discharged. The bischlorosulfonyl imide crystals were dissolved and placed in a storage tank for the purified product.

[0030] The purity of the bischlorosulfonyl imide obtained in Examples 1-3 and Comparative Examples 1-3 was tested, and the test results are shown in Table 1 below.

[0031] Table 1 Purity test results of bischlorosulfonimide obtained in Examples 1-3 and Comparative Examples 1-3

[0032]

[0033] As can be seen from Table 1, each embodiment utilizes the different melting points of bischlorosulfonyl imide acid and other impurities to design multiple crystallizations at different gradient temperatures. By regulating the crystallization temperature and crystallization time, the impurities in the bischlorosulfonyl imide acid can be removed. Compared with Comparative Examples 1-3, the bischlorosulfonyl imide acid obtained in the embodiments of the present invention has a higher purity. In particular, in Example 1, the purity of the bischlorosulfonyl imide acid reaches 95.5%, while the content of chlorosulfonic acid is only 0.03%.

[0034] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for purifying bischlorosulfonyl imide acid, characterized in that: The crude bischlorosulfonyl imide acid obtained in the production and synthesis process is subjected to multiple crystallization purification to obtain purified bischlorosulfonyl imide acid; The crude bischlorosulfonyl imide acid is subjected to a first crystallization and a second crystallization to obtain purified bischlorosulfonyl imide acid; The first crystallization is cooled from 120-140°C to 36-37°C, which takes 5-6 hours; The second crystallization is carried out by cooling the temperature from 36-37°C to 35-35.5°C for 1-2 hours, and then isothermally crystallizing at 35-35.5°C for 2-3 hours.

2. The method for purifying bischlorosulfonyl imide acid according to claim 1, wherein After the second crystallization, the temperature is raised to 39-40°C and maintained for 30-40 minutes to remove the mother liquor.

3. The method for purifying bischlorosulfonyl imide acid according to claim 2, wherein After removing the mother liquor, the bischlorosulfonyl imide acid is heated to 43-45° C. and maintained at 43-45° C. for 1.5-2 hours to obtain purified bischlorosulfonyl imide acid.

4. The method for purifying bischlorosulfonyl imide acid according to claim 1, wherein The crude bischlorosulfonyl imide acid is fed into a static crystallizer for multiple crystallizations.

Images