Preparation method of vinylene carbonate

Abstract

The invention relates to the technical field of lithium battery electrolyte additives, in particular to a preparation method of vinylene carbonate, which comprises the following steps: gasifying monochloroethylene carbonate in a gasification chamber, then mixing the gasified monochloroethylene carbonate with inert gas, and introducing the mixed gas into a catalytic reaction tower for catalytic reaction, the temperature in the catalytic reaction tower is kept at 200-300 DEG C, the catalytic reaction time is 5-8 min, then mixed gas obtained after the reaction is pumped out through an outlet of the catalytic reaction tower, the pumped-out mixed gas is condensed to 25-40 DEG C, a gas-liquid mixture is obtained and subjected to gas-liquid separation, liquid enters a product tank, and vinylene carbonate is obtained; a composite catalyst is placed in the catalytic reaction tower, and the composite catalyst is Cu / ZnO-SBA-15; the method has the advantage of reducing the generation of waste liquid and solid salt.

Description

Technical Field

[0001] This application relates to the technical field of lithium battery electrolyte additives, and particularly to a preparation method of vinylene carbonate. Background Art

[0002] Vinylene carbonate, also known as 1,3-dioxol-2-one, ethylene carbonate, etc., is more commonly used in batteries at present. Vinylene carbonate can undergo a polymerization reaction on the surface of the negative electrode of a lithium battery during the first charge and discharge, generating a polyalkyl lithium carbonate compound. The formation of this substance can effectively inhibit the embedding of solvent molecules and the gas expansion phenomenon of the lithium battery. And the polymerization reaction of vinylene carbonate can form a SEI (solid electrolyte interface) film on the negative electrode of the battery, which can minimize the decomposition degree of the graphite battery electrolyte, thereby effectively improving the cycle service life of the lithium battery. Therefore, based on the fact that vinylene carbonate is currently the most ideal, has the best effect, and has the largest usage amount of electrolyte additives, its demand has increased greatly, which makes the research on the synthesis process of vinylene carbonate also have very important practical significance.

[0003] At present, the preparation methods of vinylene carbonate are divided into ethylene carbonate (EC) preparation method, chloroethylene carbonate preparation (CEC) method, dichloroethylene carbonate (DCEC) preparation method, etc. according to the raw material sources. Among them, the chloroethylene carbonate preparation method is to dissolve chloroethylene carbonate in an organic solvent such as dimethyl carbonate and add a dechlorinating agent (metal oxide, composite metal, organic base, inorganic base, etc.) to obtain a salt and vinylene carbonate; this method is a commonly used industrial method, but it will produce a large amount of solid salts or dissolve in the organic solvent. The problem of recycling solid salts is the difficulty of the process, and a large amount of organic solvent waste liquid is not conducive to environmental protection. Summary of the Invention

[0004] In order to reduce the generation of waste liquid and solid salts, this application provides a preparation method of vinylene carbonate.

[0005] This application provides a preparation method of vinylene carbonate, adopting the following technical scheme: A preparation method of vinylene carbonate, which comprises the following preparation steps: S1. Vaporize chloroethylene carbonate in a vaporization chamber, keep the temperature between 160 - 250 °C, and then mix the vaporized chloroethylene carbonate with an inert gas at a temperature of 180 - 220 °C. The flow rate of the gaseous chloroethylene carbonate is 4 - 6 g / min, and the flow rate of the inert gas is 2 - 5 g / min; S2. Introduce the mixture of vinyl chloroformate and inert gas into the catalytic reaction tower for catalytic reaction. The temperature in the catalytic reaction tower is maintained at 200 - 300 °C, and the catalytic reaction time is 5 - 8 min. Then, draw out the reacted mixed gas through the outlet of the catalytic reaction tower, condense the drawn-out mixed gas to 25 - 40 °C to obtain a gas-liquid mixture. After gas-liquid separation, the liquid enters the product tank to obtain vinylene carbonate; A composite catalyst is placed in the catalytic reaction tower, and the composite catalyst is Cu / ZnO-SBA-15.

[0006] By adopting the above technical solution, the reactants in this application are gasified, eliminating the addition of reaction solvents. By designing the catalyst, acidic gases are generated during the reaction without the generation of solid salts, which can greatly reduce the treatment and discharge of organic waste liquids, effectively reduce production costs, be beneficial to the environment, and the generated hydrogen chloride can be collected for secondary utilization.

[0007] Preferably, the preparation method of the composite catalyst is as follows: S1. Using a mixed solution with a volume ratio of ethanol to water of 1:1 as the solvent, add 0.04 - 0.06 mol of amino silane coupling agent, stir until dissolved, then add 4 - 6 g of molecular sieve SBA-15, stir and disperse, and then raise the temperature to 75 - 85 °C and stir to react to obtain amino silane coupling agent-modified molecular sieve SBA-15; S2. Disperse the amino silane coupling agent-modified molecular sieve SBA-15 in 300 - 400 mL of an ethanol solution of copper nitrate with a concentration of 0.04 - 0.06 mol / L, stir and react at 40 - 50 °C, then add 50 - 70 mL of an aqueous solution of sodium borohydride with a concentration of 0.3 - 0.5 mol / L, stir and react at 35 - 45 °C, then filter, wash, and dry to obtain a solid; S3. Disperse the solid obtained in S2 in 300 - 400 ml / L of an ethanol solution of zinc nitrate with a concentration of 0.04 - 0.06 mol / L, stir and react at 45 - 55 °C, filter, wash, and dry, and then calcine at 450 - 520 °C for 2 - 4 h to obtain the Cu / ZnO-SBA-15 composite catalyst.

[0008] By adopting the above technical solution, in this application, the molecular sieve SBA-15 is coupled and modified by the amino silane coupling agent, making its surface contain amino groups, which can complex with copper ions, enabling the mesoporous molecular sieve SBA-15 to contain more active components, that is, more copper particles, and having a higher copper specific surface area (S Cu ) and copper dispersion degree (D Cu) This increases the contact area between the active components on the surface of the composite catalyst and the reactants; then it combines with zinc oxide, improving the selectivity and catalytic activity of the catalyst. The purity of the prepared products can all reach 99.97% and above, and the yield is all above 92.2%.

[0009] Preferably: The amino silane coupling agent is one or more of 221 aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, and anilinomethyltriethoxysilane.

[0010] By adopting the above technical solution, selecting the amino silane coupling agent within this range can theoretically achieve similar effects to those of this application. This application has not explored them one by one, but they are all within the protection scope of this application.

[0011] Preferably: The SBA-15 is a mesoporous material.

[0012] By adopting the above technical solution, the pores of the mesoporous material are larger than those of the microporous material. After loading copper and zinc oxide, the material still contains more pores, which will not cause pore blockage, resulting in a significant decrease in its specific surface area, a reduction in the contact area with the reactants, and a decrease in the reaction rate, and a reduction in the yield under the same reaction time.

[0013] Preferably: The composite catalyst is Cu / ZnO / CeO-SBA-15.

[0014] By adopting the above technical solution, by introducing cerium oxide into the composite catalyst, the selectivity of the composite catalyst can be improved, and the yield is also increased by 1.2%. The introduction of cerium oxide can make the catalytic center of the composite catalyst more stable, and after the composite catalyst is recycled and catalyzed, through calcination activation, the catalytic center can be restored to a greater extent.

[0015] Preferably: The preparation method of the Cu / ZnO / CeO-SBA-15 is as follows: S1. Using a mixed solution with a volume ratio of ethanol to water of 1:1 as the solvent, adding 0.04 - 0.06 mol of amino silane coupling agent, stirring until dissolved, then adding 4 - 6 g of molecular sieve SBA-15, stirring and dispersing, and then heating to 75 - 85 °C, stirring and reacting to obtain amino silane coupling agent-modified molecular sieve SBA-15; S2. Disperse the amino-silane-coupling-agent-modified molecular sieve SBA-15 in 300 - 400 mL of an ethanol solution of copper nitrate with a concentration of 0.04 - 0.06 mol / L, stir and react at 40 - 50 °C, then add 50 - 70 mL of an aqueous solution of sodium borohydride with a concentration of 0.3 - 0.5 mol / L, stir and react at 35 - 45 °C, then filter, wash, and dry to obtain a solid; S3. In an ethanol solution of zinc nitrate and cerium nitrate with a concentration of 300 - 400 mL / L, the concentration of zinc nitrate is 0.04 - 0.06 mol / L, and the concentration of cerium nitrate is 0.005 - 0.015 mol / L. Stir and react at 45 - 55 °C, filter, wash, and dry, then calcine at 450 - 520 °C for 2 - 4 h to obtain the Cu / ZnO / CeO-SBA-15 composite catalyst; The SBA-15 is a mesoporous material.

[0016] Preferably: After the cyclic reaction, the composite catalyst is washed, dried, and then calcined at 430 - 500 °C for activation.

[0017] By adopting the above technical solution, through activation, the catalytic centers of the composite catalyst can be restored to a certain extent, so that its catalytic activity is improved and it can be recycled.

[0018] Preferably: In S2, after the gas-liquid mixture is separated, hydrogen chloride in the obtained gas is removed by water, and then non-condensable gas is obtained.

[0019] By adopting the above technical solution, hydrogen chloride in the gas can be efficiently removed by water, and the obtained hydrochloric acid can be reused, sold, etc., saving costs.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application vaporizes the reactants, eliminating the addition of reaction solvents. By designing the catalyst, acidic gases are generated during the reaction without the generation of solid salts, which can greatly reduce the treatment and discharge of organic waste liquids, effectively reduce production costs, and be beneficial to the environment.

[0021] 2. Catalyzed by the catalyst prepared by the present application, the purity of the obtained vinylene carbonate is 99.97% or above, and the highest can reach 99.99%. And the yield can reach between 92.2 - 94.7%. And the present application reacts through gases, without the need to add organic solvents, which can greatly reduce organic waste liquids, reduce production costs, recover hydrogen chloride through water, and the obtained hydrochloric acid solution can be reused, sold, etc. Specific Embodiments

[0022] The present application will be further described in detail below in conjunction with specific content.

[0023] Raw materials All raw materials used in the examples of the present application are commercially available products. Among them, the particle size of the mesoporous molecular sieve SBA-15 powder is 3 mm, the bulk density is 0.48 g / mL, it is a mesoporous material, and it is purchased from Dalian Ze'er Catalytic Materials Co., Ltd.

[0024] Preparation examples Preparation example 1 A Cu / ZnO-SBA-15 composite catalyst, and its preparation method is as follows: S1. In a mixed solvent of 300 mL of ethanol and water with a volume ratio of 1:1, add 0.05 mol of an amino silane coupling agent, stir until dissolved, then add 5 g of mesoporous molecular sieve SBA-15 powder, stir to disperse, then raise the temperature to 80 °C, stir and react for 24 h, then filter and dry to obtain amino silane coupling agent-modified mesoporous molecular sieve SBA-15; the amino silane coupling agent is aminopropyltriethoxysilane; S2. Disperse the amino silane coupling agent-modified mesoporous molecular sieve SBA-15 in 350 mL of an ethanol solution of copper nitrate with a concentration of 0.05 mol / L, stir and react at 45 °C for 5 h, then add 60 mL of an aqueous solution of sodium borohydride with a concentration of 0.4 mol / L, stir and react at 40 °C for 60 min, then filter, wash, and dry to obtain a solid; S3. Disperse the solid obtained in S2 in 350 ml / L of an ethanol solution of zinc nitrate with a concentration of 0.05 mol / L, stir and react at 50 °C for 5 h, filter, wash, and dry, and then calcine at 500 °C for 3 h to obtain a Cu / ZnO-SBA-15 composite catalyst; the composite catalyst is detected, and the Cu loading is 6.3 wt%, and the Zn loading is 5.8 wt%.

[0025] Preparation example 2 A composite catalyst, which is different from Preparation example 1 in that in S2, the ethanol solution of copper nitrate also contains cerium nitrate with a concentration of 0.01 mol / L, and the remaining steps are the same as those in Preparation example 1, and the obtained composite catalyst is Cu / ZnO / CeO-SBA-15; the composite catalyst is detected, and the Cu loading is 6.3 wt%, the Zn loading is 5.3 wt%, and the Ce loading is 0.6 wt%. Examples

[0026] Example 1 A preparation method of vinylene carbonate, the preparation principle is shown in Formula 1, and the experimental preparation amount takes the input amount of 1 kg of ethylene chlorocarbonate as an example, and its preparation method is as follows: S1. Vaporize ethylene chlorocarbonate in a vaporization chamber at a temperature maintained between 160 - 250 °C. Then mix the vaporized ethylene chlorocarbonate with an inert gas at 200 °C. The flow rate of gaseous ethylene chlorocarbonate is 5 g / min, and the flow rate of the inert gas is 3 g / min. Here, the inert gas is nitrogen. S2. Pass the mixture of ethylene chlorocarbonate and the inert gas into a catalytic reaction tower for catalytic reaction. The temperature in the catalytic reaction tower is maintained at 200 - 300 °C, and the catalytic reaction time is 7 min. In the catalytic reaction tower, ethylene chlorocarbonate catalytically removes hydrogen chloride to obtain a mixed gas, which mainly consists of a small amount of unreacted ethylene chlorocarbonate, the reaction-generated vinylene carbonate, hydrogen chloride, nitrogen, and a small amount of impurity chloroacetaldehyde and carbon dioxide, etc. Then the reacted mixed gas is drawn out from the upper outlet of the catalytic reaction tower. The drawn gas is cooled to 40 °C through three-stage condensation to obtain a gas-liquid mixture. After gas-liquid separation, the liquid enters the product tank to obtain a liquid vinylene carbonate product. The gas is passed into water, and its function is to absorb the hydrogen chloride gas in the mixed gas. The remaining is non-condensable gas, mainly the inert gas. Sample and analyze the obtained vinylene carbonate product. The content of vinylene carbonate is 99.98%, the yield is 93.3%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm. Among them, the catalyst is a Cu / ZnO-SBA-15 composite catalyst, which is prepared by the preparation method of Preparation Example 1. The catalyst is loaded and fixed through a mesh made of polytetrafluoroethylene material (it can also be a ceramic material), and is placed alternately in the catalytic reaction tower.

[0027] Formula 1 Example 2 A preparation method of vinylene carbonate, which is different from Example 1 in that its catalyst is Cu / ZnO / CeO-SBA-15, and is prepared by the preparation method of Preparation Example 2. The remaining steps are the same as those in Example 1.

[0028] Example 3 A preparation method of vinylene carbonate, which is different from Example 2 in that in S2, the reacted mixed gas in the catalytic reaction tower is drawn out from the upper outlet of the catalytic reaction tower, and the drawn gas is cooled to 25 °C through three-stage condensation. The remaining steps are the same as those in Example 2.

[0029] Example 4 A preparation method of vinylene carbonate, which is different from that of Example 1. Through experiments, in its S2, after the catalyst is continuously recycled 500 times, that is, when the reaction input amount of ethylene carbonate monochloride is 500 kg, the obtained vinylene carbonate product is sampled and analyzed. The content of vinylene carbonate is 99.93%, and the yield is 90.1%. Then the catalyst is taken out from the catalytic reaction tower, washed with ethanol, dried, calcined at 450 °C for 2 h, and then put back into the catalytic reaction tower for catalytic reaction. The remaining steps are the same as those of Example 1.

[0030] Example 5 A preparation method of vinylene carbonate, which is different from that of Example 2. Through experiments, in its S2, after the catalyst is continuously recycled 500 times, that is, when the reaction input amount of ethylene carbonate monochloride is 500 kg, the obtained vinylene carbonate product is sampled and analyzed. The content of vinylene carbonate is 99.95%, and the yield is 92.1%. Then the catalyst is taken out from the catalytic reaction tower, washed with ethanol, dried, calcined at 450 °C for 2 h, and then put back into the catalytic reaction tower for catalytic reaction. The remaining steps are the same as those of Example 2.

[0031] Comparative example Comparative example 1 A preparation method of vinylene carbonate, which is different from that of Example 1. When preparing the catalyst, in its S2, reduction with sodium borohydride is not carried out, and the remaining steps are the same as those of Example 1.

[0032] Comparative example 2 A preparation method of vinylene carbonate, which is different from that of Example 1. When preparing the catalyst, its S1 step is not carried out, that is, the mesoporous molecular sieve SBA-15 is not coupled with an amino silane coupling agent, and the remaining steps are the same as those of Example 1.

[0033] Comparative example 3 A preparation method of vinylene carbonate, which is different from that of Example 1. When preparing the catalyst, the amino silane coupling agent in its S1 step is replaced with a silane coupling agent without amino, which is cetyltrimethoxysilane, and the remaining steps are the same as those of Example 1.

[0034] Performance detection test Detection method / Test method Vinylene carbonate is prepared respectively according to the preparation methods of Examples 1-5 and Comparative examples 1-3, and then the prepared products and composite catalysts are detected. The detection results are shown in Tables 1 and 2.

[0035] Table 1 Detection results of copper element of the composite catalyst of Example 1 and Comparative examples 1-3 <![CDATA[S Cu (m 2 / g)]]> <![CDATA[D Cu (%)]]> Example 1 31.3 23.2 Comparative Example 1 26.1 19.3 Comparative Example 2 22.4 15.9 Comparative Example 3 22.8 16.4 From the detection data in Table 1, it can be seen that in this application, the mesoporous molecular sieve SBA-15 is coupled and modified with an amino silane coupling agent, so that its surface contains amino groups, which can complex with copper ions, making the mesoporous molecular sieve SBA-15 contain more active components, that is, more copper particles, and can have a higher copper specific surface area (S Cu ) and copper dispersion (D Cu ), making the contact area between the active components on the surface of the composite catalyst and the reactants larger.

[0036] Detection Results of Examples 1-5 and Comparative Examples 1-3 in Table 2 From Examples 1-5 and Comparative Examples 1-3, as well as the detection data in Table 2, it can be seen that when the catalyst prepared by this application is used for catalysis, the purity of the prepared vinylene carbonate is 99.97% or above, and the highest can reach 99.99%, and the yield can reach between 92.2-94.7%; and this application uses gas for the reaction, without adding organic solvents, which can greatly reduce organic waste liquid, reduce production costs, recycle hydrogen chloride with water, and the prepared hydrochloric acid solution can be reused.

[0037] By modifying the mesoporous molecular sieve SBA-15 with an amino silane coupling agent, a large number of amino groups are introduced on the surface of SBA-15, which can complex with copper ions, making the composite catalyst contain more active sites. Acting together with zinc oxide, the selectivity of the catalyst reaches the optimum, and the purity and yield of the prepared product are both high. This can be verified by the detection data of Example 1 and Comparative Examples 1-3.

[0038] Combined with Example 2, by introducing cerium oxide into the composite catalyst, the selectivity of the composite catalyst can be improved, and the yield is also increased by 1.2%; combined with Examples 4-5, the introduction of cerium oxide can make the catalytic center of the composite catalyst more stable, and after the composite catalyst is recycled and catalyzed, through calcination activation, the catalytic center can be restored to a greater extent.

[0039] From the detection data of Example 2 and Example 3, it can be seen that when the temperature of the three-stage condensation is reduced, the product purity and yield can be further improved. It is speculated that this is because vinylene carbonate is prone to decomposition at high temperatures, and rapid cooling and lower temperatures are beneficial to its structural stability.

[0040] This specific embodiment is only an interpretation of the present invention and is not a limitation thereof. After reading this specification, those skilled in the art may make modifications to this embodiment that do not contribute creatively, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preparing vinylene carbonate, characterized in that: It comprises the following preparation steps: S1. Ethylene monochlorocarbonate is gasified in a gasification chamber at a temperature of 160-250° C., and then the gasified ethylene monochlorocarbonate is mixed with an inert gas at a temperature of 180-220° C., the flow rate of the gas phase ethylene monochlorocarbonate is 4-6 g / min, and the flow rate of the inert gas is 2-5 g / min; S2, passing a mixed gas of vinyl monochloride carbonate and an inert gas into a catalytic reaction tower for catalytic reaction, wherein the temperature in the catalytic reaction tower is maintained at 200-300° C., and the catalytic reaction time is 5-8 min, and then the mixed gas after the reaction is extracted through the outlet of the catalytic reaction tower, and the extracted mixed gas is condensed to 25-40° C. to obtain a gas-liquid mixture, and after gas-liquid separation, the liquid enters a product tank to obtain vinylene carbonate; A composite catalyst is placed in the catalytic reaction tower, and the composite catalyst is Cu / ZnO-SBA-15.

2. A method for preparing vinylene carbonate according to claim 1, characterized in that: The preparation method of the composite catalyst is as follows: S1. Using a mixed solution of ethanol and water in a volume ratio of 1:1 as solvent, add 0.04-0.06 mol of aminosilane coupling agent, stir until dissolved, then add 4-6 g of molecular sieve SBA-15, stir and disperse, then heat to 75-85° C., stir and react to obtain aminosilane coupling agent modified molecular sieve SBA-15; S2, dispersing the aminosilane coupling agent modified molecular sieve SBA-15 in 300-400 mL of 0.04-0.06 mol / L copper nitrate ethanol solution, stirring the reaction at 40-50° C., then adding 50-70 mL of 0.3-0.5 mol / L sodium borohydride aqueous solution, stirring the reaction at 35-45° C., then filtering, washing, and drying to obtain a solid; S3. Disperse the solid obtained in S2 in 300-400 ml / L of 0.04-0.06 mol / L zinc nitrate ethanol solution, stir and react at 45-55°C, filter, wash and dry, and then calcine at 450-520°C for 2-4h to obtain a Cu / ZnO-SBA-15 composite catalyst.

3. A method for preparing vinylene carbonate according to claim 2, characterized in that: The aminosilane coupling agent is one or more of aminopropyltriethoxysilane 221, N-aminoethyl-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, and anilinemethyltriethoxysilane.

4. A method for preparing vinylene carbonate according to claim 2, characterized in that: The SBA-15 is a mesoporous material.

5. A method for preparing vinylene carbonate according to claim 1, characterized in that: The composite catalyst is Cu / ZnO / CeO-SBA-15.

6. A method for preparing vinylene carbonate according to claim 5, characterized in that: The preparation method of the Cu / ZnO / CeO-SBA-15 is as follows: S1. Using a mixed solution of ethanol and water in a volume ratio of 1:1 as solvent, add 0.04-0.06 mol of aminosilane coupling agent, stir until dissolved, then add 4-6 g of molecular sieve SBA-15, stir and disperse, then heat to 75-85° C., stir and react to obtain aminosilane coupling agent modified molecular sieve SBA-15; S2, dispersing the aminosilane coupling agent modified molecular sieve SBA-15 in 300-400 mL of 0.04-0.06 mol / L copper nitrate ethanol solution, stirring the reaction at 40-50° C., then adding 50-70 mL of 0.3-0.5 mol / L sodium borohydride aqueous solution, stirring the reaction at 35-45° C., then filtering, washing, and drying to obtain a solid; S3, in a 300-400 ml / L ethanol solution of zinc nitrate and cerium nitrate, the concentration of zinc nitrate is 0.04-0.06 mol / L, the concentration of cerium nitrate is 0.005-0.015 mol / L, stirring and reacting at 45-55°C, filtering, washing and drying, and then calcining at 450-520°C for 2-4h to obtain a Cu / ZnO / CeO-SBA-15 composite catalyst; The SBA-15 is a mesoporous material.

7. The method for preparing vinylene carbonate according to any one of claims 1 to 6, characterized in that: After the cyclic reaction, the composite catalyst is washed, dried, and then calcined at 430-500°C for activation.

8. A method for preparing vinylene carbonate according to claim 1, characterized in that: In S2, after the gas-liquid mixture is separated into gas and liquid, hydrogen chloride in the obtained gas is removed by water, and then non-condensable gas is obtained.

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