A process for reusing ruthenium trichloride catalyst in the synthesis of ethylene sulfate

Abstract

This invention relates to the field of battery electrolyte additives, specifically to a process for recovering ruthenium trichloride catalyst in the ethylene sulfate synthesis process: In the ethylene sulfate synthesis process, an aqueous solution of ruthenium trichloride obtained through organic phase extraction is added to adjust the pH with a strong acid, and then rotary evaporated under reduced pressure until the volume of the ruthenium trichloride aqueous solution remains at 45-55%, resulting in the precipitation of a large amount of salt. The solution is then filtered under reduced pressure, and the filter cake is washed with deionized water to remove the salt until it turns white. After repeated rotary evaporation and washing, the pH is adjusted with sodium carbonate to obtain an aqueous solution of ruthenium trichloride, which is then used in the synthesis of ethylene sulfate. This process achieves a high recovery rate of ruthenium trichloride, realizes efficient utilization of the catalyst, and is highly economical.

Description

Technical Field

[0001] This invention belongs to the field of battery electrolyte additives, specifically relating to a process for reusing ruthenium trichloride catalyst in the synthesis of ethylene sulfate. Background Technology

[0002] Lithium batteries are a type of clean energy source, with high safety and no pollution. Lithium-ion batteries can be used in new energy vehicles, electronic products and other fields. In recent years, the new energy vehicle industry has developed rapidly, especially during the period when government subsidy policies were introduced. The new energy vehicle industry has grown rapidly, especially with the large-scale application of power batteries and energy storage batteries, which has driven the development of the lithium battery industry and made lithium batteries an ever-expanding global industry.

[0003] Ethylene sulfate (DTD), also known as ethanol sulfate, ethylene glycol sulfate, and ethylene ester sulfate, is an SEI film-forming additive used in lithium-ion battery electrolytes. Its function is to suppress the decline in initial battery capacity, increase initial discharge capacity, reduce battery expansion after high-temperature storage, and improve battery charge-discharge performance and cycle life. Currently, the commonly used industrial method for synthesizing ethylene sulfate involves using sodium hypochlorite as an oxidant, catalyzed by ruthenium trichloride. This method generates large amounts of saline wastewater, and the precious metal catalyst ruthenium trichloride is difficult to recover. Ruthenium is an extremely expensive rare metal, making the synthesis process of ethylene sulfate very costly.

[0004] Ruthenium (Ru) possesses unique, stable, and highly efficient catalytic properties, demonstrating significant industrial value in industrial catalysis and organic synthesis. However, my country's ruthenium resources are scarce and sparsely distributed, leading to high smelting difficulties and costs. Furthermore, my country's chemical industry generates a large amount of degraded ruthenium catalysts annually, and the ruthenium content in these degraded catalysts is far higher than that of primary mineral resources. In addition, the price of ruthenium has been rising continuously in recent years. Therefore, the recovery and utilization of ruthenium catalysts in the synthesis of ethylene sulfate has significant social and economic value. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, this invention provides a process for recycling ruthenium trichloride catalyst in the ethylene sulfate synthesis process, so as to realize the recycling of ruthenium catalyst in the ethylene sulfate synthesis process and maximize the value of resources.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] (1) Take the ruthenium trichloride aqueous solution obtained from the organic phase extraction and separation in the ethylene sulfate synthesis process and add strong acid to adjust the pH;

[0008] (2) Reduce pressure and rotary evaporate until the volume of the ruthenium trichloride aqueous solution from step (1) remains at 45-55%;

[0009] (3) Filter under reduced pressure using filter paper, and wash the filter cake with deionized water;

[0010] (4) Combine the filtrate and washing liquid and repeatedly rotary evaporate and wash. Add sodium carbonate to the final solution to adjust the pH to obtain ruthenium trichloride aqueous solution.

[0011] Furthermore, the ruthenium trichloride aqueous solution mentioned in step (1) is an aqueous solution obtained by enrichment after organic phase extraction and separation in the ethylene sulfate synthesis process.

[0012] Furthermore, the strong acids are 12 mol / L concentrated hydrochloric acid, 12 mol / L concentrated nitric acid, and 18.4 mol / L concentrated sulfuric acid. After adding the strong acids, the pH is adjusted to ≤2.

[0013] Furthermore, the rotary evaporation temperature in step (2) is 60-90℃.

[0014] Furthermore, in step (3), the filter cake is washed with deionized water 3-5 times.

[0015] Further, in step (4), the pH value is adjusted to 3-4 using sodium carbonate.

[0016] The application of the ruthenium trichloride catalyst obtained from the aforementioned recycling process in the synthesis of vinyl sulfate includes the following steps:

[0017] S1. Add vinyl sulfite, dichloromethane, the compliant ruthenium trichloride aqueous solution obtained from the above process, and deionized water to the reaction vessel in a certain proportion, and finally add sodium bicarbonate to adjust the pH of the reaction system to 7.

[0018] S2. Control the temperature of the mixture in the above reaction vessel to <10℃, set the cold trap temperature, add sodium hypochlorite dropwise while stirring, continue stirring after the dropwise addition is completed, and keep the temperature and stir after the temperature of the reaction system drops to the same as the actual temperature of the cold trap.

[0019] S3. Add sodium bisulfite for quenching. After quenching, add deionized water and dichloromethane to the system for separation. Separate the organic phase and the aqueous phase. Wash the aqueous phase with dichloromethane. Combine the organic phases and wash with deionized water. Collect the aqueous phase separated by separation and the aqueous phase used to wash the organic phase with dichloromethane. This is ruthenium trichloride aqueous solution.

[0020] S4. Add molecular sieves and / or activated carbon to the organic phase, stir, filter under positive pressure, and evaporate by rotary evaporation to obtain a white solid, which is vinyl sulfate.

[0021] Furthermore, in step S2, the cold trap temperature is -10°C.

[0022] Furthermore, in step S4, the stirring temperature is 0℃, the stirring time is 2 h, and the rotary evaporation temperature is 30℃.

[0023] By adopting the above technical solution, the ruthenium trichloride aqueous solution obtained by organic phase extraction and separation in the vinyl sulfate synthesis process is adjusted to pH with a strong acid, subjected to rotary evaporation under reduced pressure, filtered, and the filter cake is washed with deionized water. After repeated rotary evaporation and washing, sodium carbonate is added to adjust the pH to obtain the ruthenium trichloride aqueous solution, which is then used for the synthesis of vinyl sulfate. This achieves the recycling of ruthenium catalyst in the vinyl sulfate synthesis process, simplifies the operation, greatly reduces production costs, and maximizes resource value. Attached Figure Description

[0024] Figure 1 Here is a graph showing the recovery rate of ruthenium trichloride.

[0025] Figure 2 This is a graph showing the yield of DTD synthesis. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] The process for reusing ruthenium trichloride catalyst in the synthesis of ethylene sulfate is as follows:

[0029] (1) Take 400 ml of ruthenium trichloride aqueous solution obtained from organic phase extraction and separation in the ethylene sulfate synthesis process, add 12 mol / L concentrated hydrochloric acid to adjust the pH to ≤2, so that the solution changes from an alkaline environment to an acidic environment, so that ruthenium exists in the form of ruthenium trichloride. Rotary evaporate under reduced pressure at a temperature of 75℃ until the solution volume is reduced to 200 ml, and a large amount of salt is precipitated. Filter under reduced pressure, wash the filter cake three times with deionized water until the sodium chloride turns white, then combine the washing liquid and filtrate and rotary evaporate until the solution volume is halved. Filter under reduced pressure, wash the filter cake five times with deionized water, combine the washing liquid and filtrate, and rotary evaporate until the solution volume is halved. Repeat this process until almost no solid is filtered out. Add sodium carbonate to adjust the pH of the solution to 3-4 to obtain a 0.1 wt% ruthenium trichloride aqueous solution for later use.

[0030] (2) In a three-necked flask, add 50 g of vinyl sulfite, 200 ml of dichloromethane, and 200 ml of the pH-adjusted ruthenium trichloride recovery solution, followed by 200 ml of deionized water. Finally, add sodium bicarbonate to adjust the pH of the reaction system to 7. Controlling the temperature of the reaction system at <10℃, set the cold trap temperature to -10℃, mechanically stir at 300 r / min, and simultaneously add 240 ml of 12wt% sodium hypochlorite solution dropwise over 60 min. After the addition is complete, continue low-temperature stirring for 60 min at 300 r / min. Once the temperature of the reaction system drops to match the actual temperature of the cold trap, continue low-temperature stirring for 30 min at 300 r / min. Finally, add 20 ml of 10wt% sodium bisulfite solution for quenching, and test with starch-potassium iodide test paper. Add the system solution dropwise onto the starch-potassium iodide test paper; if the test paper does not change color, the quenching is complete. After quenching, 200 ml of deionized water and 200 ml of dichloromethane were added to the system, followed by separation. The organic phase was separated first, and the remaining aqueous phase was washed three times with 200 ml of dichloromethane, collecting 600 ml of the aqueous phase. Then, the separated organic phase, including the organic phase from the washings, was combined and washed 4-5 times with 200 ml of deionized water, collected together with the first washings, for a total of 1800 ml. Finally, 60 g of 4Å molecular sieve (approximately 3% of the solvent) and 10 g of activated carbon (approximately 1% of the solvent) were added to the organic phase. The mixture was stirred at 0°C for 2 h, filtered under positive pressure, and rotary evaporated at 30°C to obtain a white solid, which was ethylene sulfate with a purity of 98%.

[0031] Example 2

[0032] The process for reusing ruthenium trichloride catalyst in the synthesis of ethylene sulfate is as follows:

[0033] (1) Take 600 ml of ruthenium trichloride aqueous solution obtained from organic phase extraction and separation in the ethylene sulfate synthesis process, add 12 mol / L concentrated nitric acid to adjust the pH to ≤2, so that the solution changes from an alkaline environment to an acidic environment, so that ruthenium exists in the form of ruthenium trichloride. Rotary evaporation under reduced pressure at 60℃ until the solution volume is reduced to 330 ml, and a large amount of salt is precipitated. Filter under reduced pressure, wash the filter cake 5 times with deionized water until the sodium chloride turns white, then combine the washing liquid and filtrate and rotary evaporate until the solution volume is halved, filter under reduced pressure, wash the filter cake 3 times with deionized water, combine the washing liquid and filtrate, rotary evaporate until the solution volume is halved, repeat this process until almost no solid is filtered out. Add sodium carbonate to adjust the pH of the solution to 3-4 to obtain a 0.1 wt% ruthenium trichloride aqueous solution for later use.

[0034] (2) In a three-necked flask, add 50 g of vinyl sulfite, 200 ml of dichloromethane, and 200 ml of the pH-adjusted ruthenium trichloride recovery solution, followed by 200 ml of deionized water. Finally, add sodium bicarbonate to adjust the pH of the reaction system to 7. Controlling the temperature of the reaction system at <10℃, set the cold trap temperature to -10℃, mechanically stir at 300 r / min, and simultaneously add 240 ml of 12wt% sodium hypochlorite solution dropwise over 60 min. After the addition is complete, continue low-temperature stirring for 60 min at 300 r / min. Once the temperature of the reaction system drops to match the actual temperature of the cold trap, continue low-temperature stirring for 30 min at 300 r / min. Finally, add 20 ml of 10wt% sodium bisulfite solution for quenching, and test with starch-potassium iodide test paper. Add the system solution dropwise onto the starch-potassium iodide test paper; if the test paper does not change color, the quenching is complete. After quenching, 200 ml of deionized water and 200 ml of dichloromethane were added to the system, followed by separation. The organic phase was separated first, and the remaining aqueous phase was washed three times with 200 ml of dichloromethane, collecting 600 ml of the aqueous phase. Then, the separated organic phase, including the organic phase from the washings, was combined and washed 4-5 times with 200 ml of deionized water, collected together with the first washings, for a total of 1800 ml. Finally, 50 g of 4Å molecular sieve was added to the organic phase, approximately 3% of the solvent volume. The mixture was stirred at 0°C for 2 h, filtered under positive pressure, and rotary evaporated at 30°C to obtain a white solid, which was ethylene sulfate with a purity of 98%.

[0035] Example 3

[0036] The process for reusing ruthenium trichloride catalyst in the synthesis of ethylene sulfate is as follows:

[0037] (1) Take 800 ml of ruthenium trichloride aqueous solution obtained from organic phase extraction and separation in the ethylene sulfate synthesis process, add 18.4 mol / L concentrated sulfuric acid to adjust the pH to ≤2, so that the solution changes from an alkaline environment to an acidic environment, so that ruthenium exists in the form of ruthenium trichloride. Rotary evaporate under reduced pressure at a temperature of 90℃ until the solution volume is reduced to 360 ml, and a large amount of salt is precipitated. Filter under reduced pressure, wash the filter cake with deionized water 4 times until the sodium chloride is washed white, then combine the washing liquid and filtrate and rotary evaporate until the solution volume is halved. Filter under reduced pressure, wash the filter cake with deionized water 4 times, combine the washing liquid and filtrate, and rotary evaporate until the solution volume is halved. Repeat this process until almost no solid is filtered out. Add sodium carbonate to adjust the pH of the solution to 3-4 to obtain a 0.1 wt% ruthenium trichloride aqueous solution for later use.

[0038] (2) In a three-necked flask, add 50 g of vinyl sulfite, 200 ml of dichloromethane, and 200 ml of the pH-adjusted ruthenium trichloride recovery solution, followed by 200 ml of deionized water. Finally, add sodium bicarbonate to adjust the pH of the reaction system to 7. Controlling the temperature of the reaction system at <10℃, set the cold trap temperature to -10℃, mechanically stir at 300 r / min, and simultaneously add 240 ml of 12wt% sodium hypochlorite solution dropwise over 60 min. After the addition is complete, continue low-temperature stirring for 60 min at 300 r / min. Once the temperature of the reaction system drops to match the actual temperature of the cold trap, continue low-temperature stirring for 30 min at 300 r / min. Finally, add 20 ml of 10wt% sodium bisulfite solution for quenching, and test with starch-potassium iodide test paper. Add the system solution dropwise onto the starch-potassium iodide test paper; if the test paper does not change color, the quenching is complete. After quenching, add 200 ml of deionized water and 200 ml of dichloromethane to the system, and then perform liquid-liquid separation. First, separate the organic phase. Wash the remaining aqueous phase three times with 200 ml of dichloromethane, and collect 600 ml of the aqueous phase. Then, combine the separated organic phase, including the washed aqueous phase, and wash it 4-5 times with 200 ml of deionized water. Collect it together with the first washed aqueous phase, for a total of 1800 ml. Finally, add 10 g of activated carbon to the organic phase, with the amount of activated carbon added being approximately 1% of the solvent. Stir at 0℃ for 2 h, filter under positive pressure, and rotary evaporate at 30℃ to obtain a white solid, which is vinyl sulfate with a purity of 98%.

[0039] The experiment was repeated 20 times according to Example 1. The recovery rate of ruthenium trichloride was based on the data obtained by ICP measurement. The results are as follows: Figure 1 As shown, the recovery rate of ruthenium trichloride can reach 90%-95%.

[0040] Testing of the vinyl sulfate products obtained from 20 experiments showed that this recovery method can effectively recover ruthenium trichloride from the system and reuse it in subsequent reactions. The test results are as follows: Figure 2 As shown, the yield of vinyl sulfate synthesis is 56-60%.

[0041] In summary, the present invention can effectively recover ruthenium trichloride catalyst in the ethylene sulfate synthesis process and reuse it in subsequent reactions. The method is simple to operate, realizes the recycling of ruthenium catalyst in the ethylene sulfate synthesis process, greatly reduces production costs, and maximizes resource value.

Claims

1. An application of a ruthenium trichloride catalyst prepared by a process utilizing the recycling of ruthenium trichloride catalyst in the synthesis of vinyl sulfate, characterized in that, Includes the following steps: S1. Ethylene sulfite, dichloromethane, ruthenium trichloride aqueous solution obtained from the recycling process, and deionized water are placed into the reaction vessel in a certain proportion. Finally, sodium bicarbonate is added to adjust the pH of the reaction system to 7. S2. Control the temperature of the mixture in the above reaction vessel to <10℃, set the cold trap temperature, add sodium hypochlorite dropwise while stirring, continue stirring after the dropwise addition is completed, and keep the temperature and stir after the temperature of the reaction system drops to the same as the actual temperature of the cold trap. S3. Add sodium bisulfite for quenching. After quenching, add deionized water and dichloromethane to the system for separation. Separate the organic phase and the aqueous phase. Wash the aqueous phase with dichloromethane. Combine the organic phases and wash with deionized water. Collect the aqueous phase separated by separation and the aqueous phase used to wash the organic phase with dichloromethane. This is ruthenium trichloride aqueous solution. S4. Add molecular sieves and / or activated carbon to the organic phase, stir, filter under positive pressure, and evaporate by rotary evaporation to obtain a white solid, which is vinyl sulfate. The recycling process for the ruthenium trichloride aqueous solution obtained from the recycling process described in S1 is as follows: (1) Take the ruthenium trichloride aqueous solution obtained by organic phase extraction and separation in step S3 of the ethylene sulfate synthesis process and add strong acid to adjust the pH to ≤2; (2) Reduce pressure and rotary evaporate until the volume of the ruthenium trichloride aqueous solution from step (1) remains at 45-55%; (3) Reduced pressure filtration, the filter cake is washed with deionized water; (4) After combining the filtrate and washing liquid, the solution is repeatedly washed by rotary evaporation. The final solution is then adjusted to pH 3-4 by adding sodium carbonate to obtain a ruthenium trichloride aqueous solution.

2. The application according to claim 1, characterized in that, Step (1) The strong acid is 12 mol / L concentrated hydrochloric acid, 12 mol / L concentrated nitric acid or 18.4 mol / L concentrated sulfuric acid. After adding the strong acid, adjust the pH to ≦2.

3. The application according to claim 1, characterized in that, Step (2) The rotary evaporation temperature is 60-90℃.

4. The application according to claim 1, characterized in that, In step (3), the filter cake is washed with deionized water 3-5 times.

5. The application according to claim 1, characterized in that, In step S2, the cold trap temperature is -10℃.

6. The application according to claim 1, characterized in that, In step S4, the stirring temperature is 0℃, the stirring time is 2 h, and the rotary evaporation temperature is 30℃.

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