High-purity bis (chlorosulfonyl) imide acid prepared by rectification method and method thereof

Abstract

The invention discloses high-purity bis (chlorosulfonyl) imide acid prepared by a rectification method and a method for preparing the bis (chlorosulfonyl) imide acid by the rectification method. According to the method, the boiling point of the bis (chlorosulfonyl) imide acid is different from that of other impurities, different fillers in a rectifying tower are screened, and coarse bis (chlorosulfonyl) imide acid is rectified by adjusting the split ratio under the conditions of different temperatures and different negative pressures, so that the purity of the bis (chlorosulfonyl) imide acid is improved by brushing the fillers, and the purity of the bis (chlorosulfonyl) imide acid is improved. Impurities in the bis (chlorosulfonyl) imide acid can be better removed by adjusting the temperature, the negative pressure and the split ratio, compared with a rough steaming mode under the negative pressure condition of only heating, the purity of the bis (chlorosulfonyl) imide acid prepared through rectification is higher, and the method is simple and easy to operate and has high social use value and application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a method for preparing high-purity bischlorosulfonyl imide acid by distillation. Background Art

[0002] Lithium bis(fluorosulfonyl)imide, abbreviated as LiFSI in English, is the most widely used lithium salt electrolyte in lithium-ion batteries except lithium hexafluorophosphate, and plays the role of ion transport in lithium-ion batteries. Due to the excellent thermal stability, water stability and high ionic conductivity of LiFSI, it has always been considered a high-end substitute for lithium hexafluorophosphate. Bis(chlorosulfonyl)imide, generally abbreviated as HCSI in English, is a key intermediate in the synthesis of LiFSI. Calculated based on the total domestic production scale of LiFSI of 200,000 tons / year, the equivalent HCSI consumption reaches 300,000 tons / year. Although most manufacturers currently produce independently, due to factors such as lack of resources, insufficient production experience and difficulty in treating three wastes, the production costs of most manufacturers remain high, which has become one of the key factors restricting cost reduction and efficiency improvement. At present, the industry mainly prepares bischlorosulfonyl imide acid by distillation, melt crystallization and other methods. The distillation method has the problem of low product purity. The heavy components, chlorosulfonic acid and other impurities in the dichloro solution will have an adverse effect on the subsequent reaction; the melt crystallization method mainly utilizes the physical property of the low melting point of bischlorosulfonyl imide acid to make the product in the reaction solution crystallize out by cooling after the reaction, but this method has difficulties in crystallization and discharge, high requirements for production equipment, and high technical requirements and thresholds. The distillation method provided by the present invention is simple to operate and has high product purity compared with the above method. Summary of the invention

[0003] In order to solve the problems mentioned in the above background technology, the present invention provides a distillation and purification method for bischlorosulfonyl imide acid, wherein the crude bischlorosulfonyl imide acid obtained in the production and synthesis process is distilled and purified to obtain bischlorosulfonyl imide acid with higher purity.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing high-purity bischlorosulfonyl imide acid by distillation method comprises the following steps:

[0006] The crude bischlorosulfonyl imide acid obtained in the production and synthesis process is distilled and purified under different temperatures, different negative pressures and different split ratios to obtain high-purity bischlorosulfonyl imide acid;

[0007] The different temperatures are controlled during the heating stage of the crude bis(chlorosulfonyl)imidic acid;

[0008] Different negative pressure control when the temperature reaches the set temperature;

[0009] Different split ratios are controlled in the distillation stage;

[0010] The distillation purification adopts a distillation tower, the filler material in the distillation tower is one or a combination of glass, ceramics, titanium alloy, and the crude bischlorosulfonyl imide acid is distilled and purified under different filler conditions to obtain bischlorosulfonyl imide acid with higher purity.

[0011] Preferably, the different temperature is one of 80-90°C, 90-100°C, 100-110°C, 110-120°C, 120-130°C, 130-140°C.

[0012] Preferably, the different negative pressure is one of 8 mmHg, 7 mmHg, 6 mmHg, 5 mmHg, 4 mmHg, and 3 mmHg.

[0013] Preferably, the different split ratios are one of 2:1, 3:2, 3:1, 4:1, 4:3, 5:1, 6:1, and 7:1.

[0014] Preferably, the shape of the filler is annular, spherical, or a wire mesh corrugated tube. The crude bischlorosulfonyl imide acid is distilled and purified under different filler shapes such as annular, spherical, or wire mesh corrugated tube to obtain bischlorosulfonyl imide acid with higher purity.

[0015] Preferably, the crude bischlorosulfonyl imide has a purity of 77%-87%.

[0016] Preferably, the purity of the high-purity bischlorosulfonyl imide acid reaches more than 99%.

[0017] A high-purity bischlorosulfonyl imide acid is prepared by adopting the method for preparing high-purity bischlorosulfonyl imide acid by a distillation method.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The purification method of the present invention mainly utilizes the different boiling points of bischlorosulfonyl imide acid and other impurities. By screening different fillers in a distillation tower, the crude bischlorosulfonyl imide acid is designed to be distilled by adjusting the split ratio under different temperatures and different negative pressure conditions. By brushing the fillers, regulating the temperature, negative pressure and split ratio, the impurities in the bischlorosulfonyl imide acid can be better removed. Compared with the crude distillation method under negative pressure conditions with only heating, the bischlorosulfonyl imide acid prepared by distillation has higher purity and is simple and easy to operate.

[0020] 2. This technical invention mainly purifies crude bis(chlorosulfonyl)imide acid by screening different filler materials and shapes and controlling the temperature, negative pressure and split ratio during the distillation process to obtain a product with a purity of 99%. Compared with melt crystallization and heating crude distillation, it has the advantages of higher purity, simple and convenient operation, etc., and has high social use value and application prospects. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0023] The purity of the bischlorosulfonyl imide acid in the following examples was mainly detected by chromatography.

[0024] The crude bischlorosulfonyl imide acid in the following examples is mainly prepared by chlorosulfonic acid, aminosulfonic acid and thionyl chloride, wherein the crude bischlorosulfonyl imide has a purity of 77%-87%.

[0025] Example 1

[0026] A distillation device was built, the filler was annular ceramic, crude bis(chlorosulfonyl)imide acid was added to the flask, the system was under negative pressure during the heating stage, the temperature was raised from 30°C to 110-120°C, the heating rate was about 2°C / min, and the negative pressure was 0.05Mpa. When the temperature reached 110°C, the negative pressure was controlled to 3mm Hg pressure, and the split ratio was 5:1. The fractions were collected, accounting for 84.9% of the total mass, with a purity of 99.1%.

[0027] Example 2

[0028] A distillation device was built, with annular glass as the filler. Crude bis(chlorosulfonyl)imide acid was added to the flask. The system was under negative pressure during the heating stage. The temperature was raised from 30°C to 100-110°C, with a heating rate of about 2°C / min and a negative pressure of 0.05Mpa. When the temperature reached 110°C, the negative pressure was controlled to 5mm Hg pressure, and the split ratio was 4:1. The fractions were collected, accounting for 83.2% of the total mass, with a purity of 98.7%.

[0029] Example 3

[0030] A distillation device was built, the filler was a ring-shaped titanium alloy, crude bis(chlorosulfonyl)imide acid was added to the flask, the system was under negative pressure during the heating stage, the temperature was raised from 30°C to 110-120°C, the heating rate was about 2°C / min, and the negative pressure was 0.05Mpa. When the temperature reached 110°C, the negative pressure was controlled to 4mm Hg pressure, and the split ratio was 7:1. The fractions were collected, accounting for 84.7% of the total mass, with a purity of 98.1%.

[0031] Example 4

[0032] A distillation device was built, with spherical ceramic as the filler. Crude bis(chlorosulfonyl)imide acid was added to the flask. The system was under negative pressure during the heating stage. The temperature was raised from 30°C to 120-130°C, with a heating rate of about 2°C / min and a negative pressure of 0.05Mpa. When the temperature reached 130°C, the negative pressure was controlled to 3mm Hg pressure, and the split ratio was 5:1. The fractions were collected, accounting for 85.7% of the total mass, with a purity of 96.9%.

[0033] Example 5

[0034] A distillation device was built, and the filler was a wire mesh corrugated tube titanium alloy. Crude bis(chlorosulfonyl)imide acid was added to the flask. The system was under negative pressure during the heating stage. The temperature was raised from 30°C to 110-120°C, and the heating rate was about 2°C / min. The negative pressure was 0.05Mpa. When the temperature reached 110°C, the negative pressure was controlled to 4mm Hg pressure, and the split ratio was 6:1. The fractions were collected, accounting for 82.4% of the total mass, and the purity was 98.7%.

[0035] Example 6

[0036] A distillation device was built, with spherical titanium alloy as the filler. Crude bis(chlorosulfonyl)imide acid was added to the flask. The system was under negative pressure during the heating stage. The temperature was raised from 30°C to 120-130°C, with a heating rate of about 2°C / min and a negative pressure of 0.05Mpa. When the temperature reached 130°C, the negative pressure was controlled to 3mm Hg pressure, and the split ratio was 3:1. The fractions were collected, accounting for 85.8% of the total mass, with a purity of 98.2%.

[0037] In the above embodiments, the distillation scheme is mainly designed by utilizing the different boiling points of bischlorosulfonyl imide acid and other impurities. By adjusting different temperatures, negative pressures and split ratios, high-purity bischlorosulfonyl imide acid is purified from the crude product. The bischlorosulfonyl imide acid obtained in the embodiments of the present invention has a higher purity. In Example 1, the purity of the bischlorosulfonyl imide acid reaches 99.1% and the yield can reach 84.9%.

[0038] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing high-purity bischlorosulfonyl imide acid by distillation, characterized in that: The following steps are involved: The crude bischlorosulfonyl imide acid obtained in the production and synthesis process is distilled and purified under different temperatures, different negative pressures and different split ratios to obtain high-purity bischlorosulfonyl imide acid; The different temperatures are controlled during the heating stage of the crude bis(chlorosulfonyl)imidic acid; Different negative pressure control when the temperature reaches the set temperature; Different split ratios are controlled in the distillation stage; The distillation purification adopts a distillation tower, and the filling material in the distillation tower is one or a combination of glass, ceramic, and titanium alloy.

2. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The different temperature is one of 80-90°C, 90-100°C, 100-110°C, 110-120°C, 120-130°C, and 130-140°C.

3. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The different negative pressures are one of 8 mmHg, 7 mmHg, 6 mmHg, 5 mmHg, 4 mmHg, and 3 mmHg.

4. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The different split ratios are one of 2:1, 3:2, 3:1, 4:1, 4:3, 5:1, 6:1, and 7:

1.

5. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The shape of the filler is annular, spherical, or a wire mesh bellows.

6. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The purity of the crude bischlorosulfonyl imide is 77%-87%.

7. The method for preparing high-purity bischlorosulfonyl imide acid by distillation according to claim 1, characterized in that: The purity of the high-purity bischlorosulfonyl imide acid reaches more than 99%.

8. A high-purity bischlorosulfonyl imide acid, characterized in that: The product is prepared by the method for preparing high-purity bischlorosulfonyl imide acid by a distillation method as described in any one of claims 1 to 7.