A method for synthesizing a key intermediate of lithium bis(fluorosulfonyl)imide by heterogeneous catalysis

Abstract

The present invention discloses a method for heterogeneous catalytic synthesis of a key intermediate of a lithium bis(fluorosulfonyl)imide electrolyte (chemical name: bis(chlorosulfonyl)imide). The heterogeneous catalytic method comprises: reacting chlorosulfonic acid with chlorosulfonyl isocyanate under the action of a heterogeneous catalyst, filtering the catalyst directly after the reaction is completed, and directly applying it to the next batch of synthetic reactions, filtering the mother liquor and performing vacuum distillation to collect the target intermediate bis(chlorosulfonyl)imide fraction. Compared with the prior art, the present invention has the advantages of reusable catalyst, less residual waste, low cost, extremely high industrial application value, and is also in line with the upgrading of the green chemical industry alternative industry.

Description

Technical Field

[0001] The invention relates to the field of electrolytes for lithium batteries, and in particular to a method for preparing bischlorosulfonyl imide, a key intermediate of bisfluorosulfonyl imide lithium. Background Art

[0002] Lithium bis(fluorosulfonyl)imide is expected to gradually replace lithium hexafluorophosphate (LiPF6), which is widely used as electrolyte in lithium-ion batteries, due to its excellent electrical conductivity and thermal stability. Among the existing technologies, the most mature technology is to prepare lithium bis(fluorosulfonyl)imide by fluorination and salt formation using bis(chlorosulfonyl)imide as raw material, and the source of industrial chemical raw materials is sufficient.

[0003] For the synthesis of bis(chlorosulfonyl)imide compounds, early literature (Chem. Ber. 1962, 95, 625; Chem. Ber. 1962, 95, 1753) reported a one-step synthesis by reacting chlorosulfonic acid with chlorosulfonyl isocyanate under catalyst-free conditions, and the fractions were collected by distillation with a moderate yield.

[0004] Chinese patent CN106044728B discloses the use of Lewis acid (FeCl3, NiCl2, etc.) or protonic acid (concentrated sulfuric acid, etc.) as a catalyst to promote the reaction of chlorosulfonic acid and chlorosulfonyl isocyanate, and the yield is greatly improved by about 10% compared with the condition without catalyst.

[0005] The example in US Pat. No. 9096502B2 discloses that under the condition of no catalyst, when chlorosulfonic acid is in excess (molar ratio N (氯磺酸) / N (氯磺酰异氰酸酯) =1.1 / 0.7), the distillation yield of bischlorosulfonyl imide was only 51%.

[0006] Although the above-mentioned process for preparing bischlorosulfonyl imide, a key intermediate of lithium bisfluorosulfonyl imide, can initially meet the current development needs of the lithium battery industry, it still has bottleneck problems in the development of the industry, such as the inability to recycle the catalyst, a large amount of distillation kettle residue, and high environmental protection disposal costs. Therefore, the field urgently needs a greener method for preparing bischlorosulfonyl imide to replace and upgrade the process technology. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for utilizing heterogeneous catalytic technology to realize the recycling of heterogeneous catalysts, reduce the cost of using a single batch of catalysts, and greatly reduce the generation of distillation still residues, so as to solve the deficiencies in the prior art.

[0008] The technical solution of the present invention is as follows:

[0009] According to the present invention, the chemical synthesis steps are as follows:

[0010]

[0011] According to the present invention, the method for preparing bischlorosulfonyl imide by using heterogeneous catalyst catalytic technology comprises: mixing raw material chlorosulfonic acid with a heterogeneous catalyst to form a heterogeneous mixed system, then heating and dropwise adding chlorosulfonyl isocyanate to react, filtering and separating the heterogeneous catalyst after the reaction is completed, directly applying the heterogeneous catalyst to the next batch of reactions, and collecting the target intermediate fraction bischlorosulfonyl imide by vacuum distillation of the mother liquor.

[0012] In the above method, the heterogeneous catalyst is a solid superacid heteropolyacid catalyst with SiO2, zeolite molecular sieve or MCM-41 as a carrier.

[0013] More specifically, the heterogeneous catalyst can be purchased from the market, such as one or more combinations selected from the brands HND-580, HND-587, HND-583, HND-5w, HND-31, HND-64, HND-270 or HND-260.

[0014] In the above method, the heterogeneous catalyst can be used at least three times without significant reduction in catalytic activity.

[0015] In the above method, the mass ratio of the heterogeneous catalyst to the chlorosulfonic acid is m (催化剂) / m (氯磺酸) =1 / (5~200), preferably 1 / 10~1 / 100.

[0016] In the above method, the molar ratio of chlorosulfonic acid to chlorosulfonyl isocyanate is (氯磺酸) :N (氯磺酰异氰酸酯) =1:0.9~1:1.5, preferably 1:1.1~1:1.3.

[0017] In the above method, the reaction temperature of the reaction system is 80 to 140°C, preferably 100 to 130°C.

[0018] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention adopts a solid superacid heteropolyacid catalyst to achieve heterogeneous catalysis, mild reaction conditions, and significantly improve the product yield compared with the conditions without a catalyst.

[0020] (2) The heterogeneous catalyst of the present invention is separated from the reaction liquid by a simple filtration operation, and the catalyst is directly applied to the next batch of reactions, which significantly reduces the emission of distillation still residues in each batch, is greener, and has more economical cost advantages.

[0021] Therefore, the present invention provides a green industrial preparation method for preparing bischlorosulfonyl imide. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto. It should be noted that the embodiments and features in the embodiments in this application can be combined with each other.

[0023] Example 1

[0024] Add 116.5g of chlorosulfonic acid and 6.0g of HND-580 heteropoly acid to a dry 500mL reaction bottle, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.2g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C and continue to keep warm for 15h. When the reaction is completed and the temperature is lowered to about 40°C, the catalyst is filtered, and the mother liquor begins high vacuum distillation. After the fraction temperature is greater than 95°C, 188.5g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 88.1%.

[0025] Example 2

[0026] Add 116.4g of chlorosulfonic acid and 6.0g of HND-31 heteropoly acid to a dry 500mL reaction bottle, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.3g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C and continue to keep warm for 15h. When the reaction is completed and the temperature is lowered to about 40°C, the catalyst is filtered, and the mother liquor begins high vacuum distillation. After the fraction temperature is greater than 95°C, 179.1g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 83.7%.

[0027] Example 3

[0028] Add 116.5g of chlorosulfonic acid and 6.0g of HND-260 heteropoly acid to a dry 500mL reaction bottle, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.1g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C and continue to keep warm for 15h. When the reaction is completed and the temperature is lowered to about 40°C, the catalyst is filtered, and the mother liquor begins high vacuum distillation. After the fraction temperature is greater than 95°C, 167.3g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 78.2%.

[0029] Example 4

[0030] Add 116.6g of chlorosulfonic acid and 3.0g of HND-580 heteropoly acid to a dry 500mL reaction bottle, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.5g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C and continue to keep warm for 15h. When the reaction is completed and the temperature is lowered to about 40°C, the catalyst is filtered, and the mother liquor begins high vacuum distillation. After the fraction temperature is greater than 95°C, 156.4g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 73.1%.

[0031] Example 5

[0032] Add 116.3g of chlorosulfonic acid, 3.0g of HND-5w heteropoly acid, and 3.0g of HND-580 heteropoly acid to a dry 500mL reaction bottle, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.0g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C, and continue to keep the reaction for 15h. When the reaction is completed and the temperature is lowered to about 40°C, the filtered catalyst is directly used for the next batch, and the mother liquor begins high vacuum decompression distillation. After the fraction temperature is greater than 95°C, 185.5g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 86.7%.

[0033] Example 6

[0034] Add 116.5g of chlorosulfonic acid to a dry 500mL reaction bottle, recover and apply the catalyst in Example 5, evacuate the nitrogen, heat to 80-110°C, and start to drop 184.2g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135°C, and continue to keep warm for 15h. When the reaction is completed and the temperature is lowered to about 40°C, filter the catalyst and directly apply it to the next batch, and start high vacuum decompression distillation of the mother liquor. After the fraction temperature is greater than 95°C, collect 184.2g of bischlorosulfonyl imide fraction, which is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 86.1%.

[0035] Example 7

[0036] Add 116.2 g of chlorosulfonic acid to a dry 500 mL reaction bottle, recover the catalyst in Example 6, evacuate the nitrogen, heat to 80-110 ° C, and start to drop 184.3 g of chlorosulfonyl isocyanate. After the addition is completed, slowly heat to 120-135 ° C, and continue to keep warm for 15 hours. When the reaction is completed and the temperature is lowered to about 40 ° C, the catalyst is filtered, and the mother liquor begins high vacuum distillation. After the fraction temperature is greater than 95 ° C, 185.2 g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 86.5%.

[0037] Comparative Example

[0038] Add 116.5g of chlorosulfonic acid to a dry 500mL reaction bottle, exhaust nitrogen, heat to 100-110°C, and start to drop 184.5g of chlorosulfonyl isocyanate. After the dropwise addition is completed, slowly heat to 130-140°C, and continue to keep the reaction for 30h. When the reaction is completed and the temperature is lowered to about 40°C, high vacuum reduced pressure distillation is started. When the fraction temperature is greater than 95°C, 151.1g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent, and solidifies into a white solid at room temperature, with a yield of 70.6%.

[0039] The above description is only a specific embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, supplement, etc. made within the scope of the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heterogeneous catalytic synthesis method of bischlorosulfonyl imide, characterized in that: The method comprises the following steps: Add 116.5 g of chlorosulfonic acid and 6.0 g of HND-580 heteropoly acid to a dry 500 mL reaction bottle, evacuate the nitrogen, heat to 80-110 ° C, start to drop 184.2 g of chlorosulfonyl isocyanate, slowly raise the temperature to 120-135 ° C after the addition is completed, continue to keep the reaction for 15 hours, and when the reaction is completed, the temperature is lowered to about 40 ° C, the catalyst is filtered, and the mother liquor is distilled under high vacuum. After the fraction temperature is greater than 95 ° C, 188.5 g of bischlorosulfonyl imide fraction is collected. The fraction is colorless and transparent and solidifies into a white solid at room temperature.

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