A method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization

Abstract

The invention discloses a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization, and belongs to the field of chemical industry. The present invention dissolves sorbic acid in a mixed solvent to obtain a sorbic acid solution, and pumps the sorbic acid solution and potassium hydroxide or potassium carbonate aqueous solution into a neutralization reactor for neutralization reaction to obtain a potassium sorbate solution, and then pumps the potassium sorbate solution into a two-stage crystallization reactor for continuous cooling crystallization, and finally the crystallized tide product potassium sorbate is dried to obtain a potassium sorbate finished product, wherein the mixed solvent is a mixed solvent composed of one or two of ethanol or acetone and water, and the concentration of ethanol or / and acetone is 10%-80%. The present invention dissolves sorbic acid in a solution and reacts liquid-liquid with a potassium hydroxide solution, and the mixing is more uniform and the reaction is easy to control, and the potassium sorbate crystals in the obtained potassium sorbate finished product are regular granular, with a content of ≥99.8% and a transmittance of ≥98.5%.

Description

Technical Field

[0001] The invention relates to a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization, belonging to the field of chemical industry. Background Art

[0002] Potassium sorbate is one of the several preservatives allowed by the World Health Organization Committee on Additives. The two double bonds in potassium sorbate combine with the sulfhydryl groups in the microbial enzyme system, which can destroy the microbial enzyme system and inhibit the reproduction of microorganisms, thus achieving the purpose of preservation. Potassium sorbate is widely used in food, beverages, medicine, cosmetics and other fields due to its good antibacterial effect and safety.

[0003] At present, the main method for preparing potassium sorbate in industrial production is: using crude sorbic acid to react with potassium carbonate or potassium hydroxide solution to obtain potassium sorbate solution by neutralization reaction, adding activated carbon to remove impurities such as pigments in the potassium sorbate solution, then filtering and separating the activated carbon to obtain potassium sorbate liquid, and then drying by high-speed centrifugal spray to obtain potassium sorbate powder, and then granulating, drying, and screening to obtain the product potassium sorbate.

[0004] Patent publication CN101402557A reports a potassium sorbate preparation process, which directly reacts a mixture of sorbic acid hydrolyzate and tar with potassium carbonate, removes the decoking step, does not use ethanol, and later uses activated carbon to remove pigments and tar from the potassium sorbate solution, and then uses a nanofiltration process to further remove pigments and tar, and later uses high-speed centrifugal spraying to dry to obtain potassium sorbate powder, which is then granulated with a granulator to obtain columnar potassium sorbate particles, and the potassium sorbate finished product has a light transmittance of 98.5%. However, this process uses activated carbon for decolorization, produces a large amount of solid waste, and the nanofiltration process is costly and is not suitable for industrial production.

[0005] Patent publication CN103351294A describes a new process for granulating potassium sorbate, in which the spray-dried dry powder is mixed with a potassium sorbate solution to increase the bonding force and achieve a good granulation effect. In the patent, the potassium sorbate solution is directly atomized and dried using a spray dryer, and impurities in the aqueous solution still remain in the potassium sorbate powder, resulting in a low product quality.

[0006] Patent publication CN112479865A provides a method for preparing high-purity feed additive potassium sorbate, wherein potassium hydroxide and sorbic acid are neutralized to obtain a potassium sorbate initial solution, which is decolorized by activated carbon 4 to 6 times to obtain a high-purity potassium sorbate solution, which is then spray-dried and granulated to obtain a finished potassium sorbate product. This process is cumbersome and will produce a large amount of solid waste.

[0007] The existing potassium sorbate preparation processes all involve solid-liquid reaction of solid sorbic acid with potassium hydroxide solution, which results in uneven reaction, excessive local concentration, and the generation of more by-products. In addition, activated carbon decolorization is used in the later stage, and a large amount of solid waste is generated in the activated carbon decolorization process, which increases the post-processing cost. Spray drying is used for the final drying, which results in the inability to effectively remove impurities in the aqueous solution, which ultimately affects the quality of potassium sorbate. Summary of the invention

[0008] The purpose of the present invention is to provide a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization, so as to solve the problems that the neutralization reaction is uneven, there are many by-products, there are many solid wastes, and the product quality is not high, which are easily generated in the current production process of potassium sorbate. The present invention uses ethanol or acetone as a good solvent for sorbic acid to obtain a sorbic acid solution, which undergoes a liquid-liquid neutralization reaction with a potassium hydroxide solution or a potassium carbonate solution. Compared with the traditional solid-liquid neutralization reaction, the reaction of the present invention is easy to control, the reactants are mixed more evenly, and the obtained potassium sorbate solution can be directly obtained by continuous cooling crystallization, which greatly improves the quality of the potassium sorbate product, and does not need to use activated carbon for decolorization, reduces a large amount of solid waste, and has good industrial prospects.

[0009] In order to achieve the above object, the present invention provides a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization. The method comprises: dissolving sorbic acid in a mixed solvent to obtain a sorbic acid solution, and pumping the sorbic acid solution and a potassium hydroxide aqueous solution or a potassium carbonate aqueous solution into a neutralization reactor for neutralization reaction to obtain a potassium sorbate solution, then pumping the potassium sorbate solution into a two-stage crystallization reactor for continuous cooling crystallization, and finally drying the damp potassium sorbate obtained by separating the potassium sorbate crystal liquid after crystallization to obtain a potassium sorbate product, wherein the mixed solvent is a mixed solvent composed of one or both of ethanol or acetone and water, and the concentration of ethanol and / or acetone in the mixed solvent is 10%-90% (v / v).

[0010] Furthermore, the method is implemented by a continuous production method.

[0011] Furthermore, the mass concentration of the sorbic acid solution is 10-60%.

[0012] Furthermore, the process of dissolving sorbic acid in the mixed solvent is carried out at 30-80°C.

[0013] Furthermore, the neutralization reaction temperature is 40-80°C, the pH is 9-11, and the reaction residence time is 0.5-5h.

[0014] Furthermore, the concentration of the potassium hydroxide aqueous solution is 5 to 30 wt %, and the concentration of the potassium carbonate aqueous solution is 5 to 30 wt %.

[0015] Furthermore, the molar ratio of the sorbic acid to potassium hydroxide or potassium carbonate is 1:0.9-1.3.

[0016] Furthermore, the flow rates of the sorbic acid solution and the potassium hydroxide aqueous solution (or potassium carbonate aqueous solution) are 3-15 mL / min and 3-15 mL / min, respectively.

[0017] Furthermore, in the continuous cooling crystallization process, the crystallization temperature of the primary crystallizer is controlled at 45-60°C, the crystallization residence time is 0.5-3h, and the crystallization temperature of the secondary crystallizer is controlled at 10-30°C, the crystallization residence time is 0.5-5h.

[0018] Furthermore, the preferred system pressure for cooling crystallization is normal pressure.

[0019] Furthermore, the crystallizer is a kettle crystallizer or a tubular crystallizer.

[0020] Furthermore, after the reaction is completed, the mother liquor accounting for 5 to 30% of the total mass of the mother liquor is subjected to solvent recovery under normal pressure, the kettle liquid after the solvent recovery is directly incinerated, and the recovered solvent and the remaining mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution; wherein the mother liquor is the liquid obtained after crystals are precipitated after crystallization.

[0021] Furthermore, the potassium sorbate crystals in the potassium sorbate finished product are in regular granular form, with a content of ≥99.8%, a transmittance of ≥98.5%, a proportion of less than 80 meshes <1%, and a proportion of more than 30 meshes <5%.

[0022] The present invention also provides application of the method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization in the fields of food, beverage, medicine, cosmetics, chemical industry, etc.

[0023] The present invention provides a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization, which has the following beneficial effects:

[0024] 1) According to the present invention, sorbic acid is dissolved in a solvent and subjected to a liquid-liquid reaction with a potassium hydroxide solution or a potassium carbonate solution, so that the reaction system can be uniformly mixed, and the reaction is more controllable. A continuous crystallizer is then used for continuous crystallization, so that the generation of crystal scale and solid waste in the crystallizer is avoided. The wet product obtained by crystallization has a high potassium sorbate content and high product quality, and the drying energy consumption is reduced.

[0025] 2) The solvent is recovered after the mother liquor is partially eliminated. The elimination process can remove the impurities of the reaction from the eliminated mother liquor without excessive accumulation of impurities. Therefore, compared with the existing process, the decolorization process can be eliminated, the use of activated carbon is eliminated, the raw material cost is reduced, and the generation of solid waste is reduced;

[0026] 3) The present invention adopts a continuous crystallization process, and the impurities can be well separated during the crystallization process. Potassium sorbate presents a better crystal form, the potassium sorbate content in the tide product is higher, the amount of moisture and residual solvent after drying is less, the energy consumption of drying and the residence time of the material at high temperature are greatly reduced, and the product quality and product drying capacity are further improved. The potassium sorbate crystals in the obtained potassium sorbate finished product are in regular granular form, with a content of ≥99.8%, a transmittance of ≥98.5%, a proportion of more than 30 meshes of less than 5%, a proportion of 30-80 meshes of more than 94%, and a proportion of less than 80 meshes of less than 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention provides a flow chart of a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization.

[0028] Figure 2 A picture of the columnar potassium sorbate prepared by a granulator in Example 1.

[0029] Figure 3 Picture of granular potassium sorbate obtained by crystallization in Example 1. DETAILED DESCRIPTION

[0030] The invention provides a method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization. The method comprises: dissolving sorbic acid in a mixed solvent to obtain a sorbic acid solution, and pumping the sorbic acid solution and a potassium hydroxide aqueous solution or a potassium carbonate solution into a neutralization reactor for neutralization reaction to obtain a potassium sorbate solution, then pumping the potassium sorbate solution into a two-stage crystallization reactor for continuous cooling crystallization, and finally drying the damp potassium sorbate obtained after separation of potassium sorbate crystal liquid after crystallization to obtain a potassium sorbate finished product, wherein the mixed solvent is a mixed solvent composed of one or both of ethanol or acetone and water, and the concentration of ethanol and / or acetone is 10%-90% (v / v). The potassium sorbate crystals in the obtained potassium sorbate finished product are in a regular granular shape, with a content of ≥99.8%, a transmittance of ≥98.5%, a proportion of more than 30 meshes of less than 5%, a proportion of 30-80 meshes of more than 94%, and a proportion of less than 80 meshes of less than 1%.

[0031] The present invention is further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0032] Test method:

[0033] Potassium sorbate content determination method: Weigh 0.2g of dry potassium sorbate, accurate to 0.0002g, and place it in a 250mL iodine volumetric flask containing 48mL glacial acetic acid and 2mL acetic anhydride, and warm it to make a solution. Cool to room temperature, add 2 drops of crystal violet indicator solution, and titrate with perchloric acid standard titration solution (C=0.1mol / L) until the solution changes from purple to blue-green as the end point. The required volume of perchloric acid standard titration solution is V1. At the same time as the determination, according to the same steps as the determination, a blank test is performed on the actual solution with the same amount of sample added, and the required volume of perchloric acid standard titration solution is V2.

[0034] The mass fraction of potassium sorbate (on a dry basis) W1 = (V1-V2) / 1000*0.1*150.2 / m*100%, where m is the mass of the sample.

[0035] Transmittance test method: Weigh 5.0g (accurate to 0.01g) of potassium sorbate sample and dissolve it in 20mL of distilled water. Use distilled water as the reference solution and measure its transmittance at 430nm.

[0036] Particle size test method: Take 100g (accurate to 0.01g) of potassium sorbate sample and sieve it with sieves of different mesh sizes. The particle size ratio = mass at the particle size / total mass*100%.

[0037] Example 1

[0038] (1) Weighing 100 g of sorbic acid and 550 g of an aqueous solution with a 60% alcohol content, mixing and dissolving them continuously at 50° C., wherein the mass concentration of sorbic acid after dissolution is 15.4%; then, the sorbic acid solution and 500 g of an aqueous solution with a concentration of 10.1 wt % of potassium hydroxide are respectively introduced into a neutralization reactor at flow rates of 6.6 mL / min and 3.3 mL / min for continuous neutralization reaction, wherein the temperature of the neutralization reaction is 70° C., the reaction residence time is 3 h, and the pH is controlled to be maintained at 10.5;

[0039] (2) The obtained potassium sorbate neutralized solution is then pumped into a two-stage continuous kettle crystallizer at a flow rate of 9.9 mL / min for continuous cooling crystallization. The pressure of the crystallization system is atmospheric pressure. The crystallization temperature of the first crystallizer is controlled at 45° C., and the crystallization residence time is 3 h. The crystallization temperature of the second crystallizer is controlled at 13° C., and the crystallization residence time is 4 h. The precipitated potassium sorbate crystal liquid is then separated, and the separated damp potassium sorbate is dried to obtain a finished potassium sorbate product.

[0040] After testing, it was found that the finished potassium sorbate was in regular granular form (see Figure 2 and Figure 3), potassium sorbate content 99.83%, transmittance 98.7%, 0.3% below 80 mesh, 4.6% above 30 mesh, finally, the mother liquor separated after crystallization, which accounts for 18% of the total mother liquor mass, is subjected to solvent recovery under normal pressure, and the recovered solvent and the rest of the mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution, and the above production process is circulated.

[0041] Example 2

[0042] (1) 100 g of sorbic acid and 170 g of a 60% acetone aqueous solution were continuously mixed and dissolved at 70° C., and the mass concentration of the dissolved sorbic acid was 37%; then the obtained sorbic acid solution and 270 g of a 18.7 wt % potassium hydroxide aqueous solution were continuously introduced into a neutralization reactor at flow rates of 5.5 mL / min and 5.5 mL / min for continuous neutralization reaction, the neutralization reaction temperature was 80° C., the reaction residence time was 1 h, and the pH was controlled to be maintained at 10.5;

[0043] (2) The potassium sorbate neutralized solution obtained in step (1) is then pumped into a two-stage continuous autoclave crystallizer at a flow rate of 11 mL / min for continuous cooling crystallization. The pressure of the crystallization system is atmospheric pressure. The crystallization temperature of the first crystallizer is controlled at 50° C., and the crystallization residence time is 1.5 h. The crystallization temperature of the second crystallizer is controlled at 22° C., and the crystallization residence time is 2.5 h. The precipitated potassium sorbate crystals are then continuously separated, and the separated damp potassium sorbate is dried to obtain a potassium sorbate finished product.

[0044] After measurement, the finished potassium sorbate is in the form of regular particles, with a potassium sorbate content of 99.85%, a transmittance of 98.6%, 0.5% below 80 mesh, and 3.2% above 30 mesh. Finally, the mother liquor separated after crystallization, which accounts for 22% of the total mother liquor mass, is subjected to solvent recovery under normal pressure, and the recovered solvent and the remaining mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution, and the above production process is repeated.

[0045] Example 3

[0046] (1) 100 g of sorbic acid and 270 g of a 45% acetone aqueous solution were continuously mixed and dissolved at 70° C., and the mass concentration of the dissolved sorbic acid was 27%; the sorbic acid solution with a mass concentration of 27% and 200 g of a 25.3 wt % potassium hydroxide aqueous solution were respectively introduced into a neutralization reactor at flow rates of 7.3 mL / min and 3.5 mL / min for continuous neutralization reaction, the temperature of the neutralization reaction was controlled at 80° C., the residence time was 2 h, and the pH of the neutralization reaction was maintained at 10;

[0047] (2) The potassium sorbate neutralized solution obtained in the above step (1) is then pumped into a two-stage continuous tubular crystallizer at a flow rate of 10.8 mL / min for continuous cooling crystallization. The crystallization system pressure is atmospheric pressure, wherein the crystallization temperature of the first crystallizer is controlled at 47° C., the crystallization residence time is 3 h, and the crystallization temperature of the second crystallizer is controlled at 19° C., the crystallization residence time is 4.5 h; and the precipitated potassium sorbate crystals are continuously separated, and the separated damp potassium sorbate is dried to obtain a potassium sorbate finished product.

[0048] After measurement, the finished potassium sorbate is in the form of regular particles, with a potassium sorbate content of 99.82%, a transmittance of 98.5%, 0.1% below 80 mesh, and 2.5% above 30 mesh. Finally, the mother liquor separated after crystallization, which accounts for 20% of the total mother liquor mass, is subjected to solvent recovery under normal pressure, and the recovered solvent and the remaining mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution, and the above production process is repeated.

[0049] Example 4

[0050] (1) 100 g of sorbic acid and 400 g of a 70% alcohol aqueous solution were continuously mixed and dissolved at 50° C., and the mass concentration of the dissolved sorbic acid was 20%; the sorbic acid solution with a mass concentration of 20% and 500 g of a 10.1 wt % potassium hydroxide aqueous solution were respectively introduced into a neutralization reactor at a flow rate of 5 mL / min and 5 mL / min for continuous neutralization reaction, the reaction temperature was controlled at 65° C., the residence time was 3.5 h, and the pH was maintained at 10 during the neutralization reaction;

[0051] (2) the potassium sorbate neutralized solution in step (1) is then pumped into a two-stage continuous autoclave crystallizer at a flow rate of 10 mL / min for continuous cooling crystallization, the pressure of the crystallization system is atmospheric pressure, wherein the crystallization temperature of the first crystallizer is controlled at 58° C., the crystallization residence time is 1.5 h, and the crystallization temperature of the second crystallizer is controlled at 22° C., the crystallization residence time is 3.5 h; and the precipitated potassium sorbate crystals are continuously separated, and the separated damp potassium sorbate is dried to obtain a finished potassium sorbate product.

[0052] After measurement, the finished potassium sorbate is in the form of regular particles, with a potassium sorbate content of 99.82%, a light transmittance of 98.7%, 0.41% below 80 mesh, and 2.9% above 30 mesh. Finally, the mother liquor separated after crystallization, which accounts for 25% of the total mother liquor mass, is subjected to solvent recovery under normal pressure, and the recovered solvent and the remaining mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution, and the above production process is repeated.

[0053] Example 5

[0054] (1) 100 g of sorbic acid and 400 g of a 70% alcohol aqueous solution were continuously mixed and dissolved at 60° C., and the mass concentration of sorbic acid after dissolution was 20%; the sorbic acid solution with a mass concentration of 20% and 250 g of a 20.2 wt % potassium hydroxide aqueous solution were respectively introduced into a neutralization reactor at flow rates of 6.6 mL / min and 3.3 g / min to carry out a continuous neutralization reaction, the reaction temperature was controlled at 75° C., the residence time was 1 h, and the pH was maintained at 10 during the neutralization reaction;

[0055] (2) the potassium sorbate neutralized solution in step (1) is injected into a two-stage continuous autoclave crystallizer at a flow rate of 9.9 mL / min for continuous cooling and crystallization, wherein the pressure of the crystallization system is atmospheric pressure, wherein the crystallization temperature of the first crystallizer is controlled at 45° C., the crystallization residence time is 0.5 h, and the crystallization temperature of the second crystallizer is controlled at 10° C., the crystallization residence time is 0.5 h; and the precipitated potassium sorbate crystal solution is continuously separated, and the separated damp potassium sorbate is dried to obtain a potassium sorbate finished product, wherein the finished potassium sorbate is in the form of regular particles, has a potassium sorbate content of 99.8%, a transmittance of 98.6%, 4.1% of the particles above 30 mesh, 95.2% of the particles between 30 and 80 mesh, and 0.7% of the particles below 80 mesh.

[0056] When the concentration of ethanol and / or acetone in the mixed solvent is 10%-90% (v / v), according to the methods of Examples 1 to 5, the potassium sorbate crystals in the prepared potassium sorbate product are regular granular, with a content of ≥99.8%, a transmittance of ≥98.5%, a proportion of less than 80 meshes <1%, and a proportion of more than 30 meshes <5%.

[0057] Comparative Example 1

[0058] (1) 10 g of sorbic acid and 1020 g of water were continuously mixed and dissolved at 80° C., and the mass concentration of sorbic acid after dissolution was 0.97%; the sorbic acid solution with a mass concentration of 0.97% and 500 g of a 1% potassium hydroxide aqueous solution were respectively introduced into a neutralization reactor at flow rates of 6.6 mL / min and 3.3 g / min for continuous neutralization reaction, the reaction temperature was controlled at 70° C., the residence time was 3 h, and the pH was maintained at 10.5 during the neutralization reaction;

[0059] (2) The potassium sorbate neutralized solution in step (1) is then pumped into a two-stage continuous kettle crystallizer at a flow rate of 9.9 mL / min for continuous cooling crystallization. The pressure of the crystallization system is atmospheric pressure. The crystallization temperature of the first crystallizer is controlled at 45° C., the crystallization residence time is 3 h, and the crystallization temperature of the second crystallizer is controlled at 13° C., the crystallization residence time is 4 h. No potassium sorbate is precipitated.

[0060] Comparative Example 2

[0061] (1) 100 g of sorbic acid and 400 g of a 70% alcohol aqueous solution are continuously mixed and dissolved at 50° C., and the mass concentration of the dissolved sorbic acid is 20%; the sorbic acid solution with a mass concentration of 20% and 500 g of a 10.1% potassium hydroxide aqueous solution are respectively introduced into a neutralization reactor at a flow rate of 5 mL / min and 5 mL / min to carry out a continuous neutralization reaction, the reaction temperature is controlled at 65° C., the residence time is 3.5 h, and the pH is maintained at 10 during the neutralization reaction;

[0062] (2) the potassium sorbate neutralized solution in step (1) is then pumped into a two-stage continuous autoclave crystallizer at a flow rate of 10 mL / min for continuous cooling and crystallization, wherein the pressure of the crystallization system is atmospheric pressure, wherein the crystallization temperature of the first crystallizer is controlled at 40° C., the crystallization residence time is 0.5 h, and the crystallization temperature of the second crystallizer is controlled at 10° C., the crystallization residence time is 20 min; and the precipitated potassium sorbate crystal solution is continuously separated, and the separated damp potassium sorbate is dried to obtain a potassium sorbate finished product, wherein the finished potassium sorbate is in the form of regular particles, has a potassium sorbate content of 98.3%, a transmittance of 96.2%, 30 mesh or more accounts for 3.8%, 30-80 mesh accounts for 89.8%, and 80 mesh or less accounts for 6.4%.

[0063] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization, characterized in that: The method comprises: dissolving sorbic acid in a mixed solvent to obtain a sorbic acid solution, and pumping the sorbic acid solution and a potassium hydroxide aqueous solution or a potassium carbonate aqueous solution into a neutralization reactor for neutralization reaction to obtain a potassium sorbate solution, then pumping the potassium sorbate solution into a two-stage crystallization reactor for continuous cooling crystallization, and finally drying the potassium sorbate obtained by separating the potassium sorbate crystal liquid after crystallization to obtain a finished potassium sorbate product, wherein the mixed solvent is a mixed solvent composed of one or both of ethanol or acetone and water, and the concentration of ethanol and / or acetone in the mixed solvent is 10%-90% (v / v). In the continuous cooling crystallization process, the crystallization temperature of the primary crystallizer is controlled at 45-60°C, the crystallization residence time is 0.5-3h, and the crystallization temperature of the secondary crystallizer is controlled at 10-30°C, and the crystallization residence time is 0.5-5h. The mass concentration of the sorbic acid solution is 10-60%; The process of dissolving sorbic acid in the mixed solvent is carried out at 30-80°C.

2. The method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization according to claim 1, characterized in that: The temperature of the neutralization reaction is 40-80° C., the pH is 9-11, and the reaction residence time is 0.5-5 h.

3. The method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization according to claim 1, characterized in that: The concentration of the potassium hydroxide aqueous solution is 5-30 wt %, and the concentration of the potassium carbonate aqueous solution is 5-30 wt %.

4. The method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization according to claim 1, characterized in that: The flow rate of the sorbic acid solution is 3-15 mL / min, and the flow rate of the potassium hydroxide aqueous solution or the potassium carbonate aqueous solution is 3-15 mL / min.

5. The method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization according to claim 1, characterized in that: The system pressure of cooling crystallization is normal pressure.

6. The method for producing potassium sorbate by liquid-liquid neutralization reaction and continuous cooling crystallization according to claim 1, characterized in that: After the reaction is completed, the mother liquor accounting for 5-30% of the total mass of the mother liquor is subjected to solvent recovery under normal pressure, and the recovered solvent and the remaining mother liquor are returned to the sorbic acid dissolution step for sorbic acid dissolution to prepare a sorbic acid solution.

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