Method and system for improving purity of neopentyl glycol product

Abstract

The invention provides a method and a system for improving the purity of a neopentyl glycol product, and in the method and the system, an alkaline substance is added into a crude neopentyl glycol solution before the crude neopentyl glycol solution enters a light component removal tower, so that the crude neopentyl glycol solution is in a hydrolysis environment of ester substances, esterification reaction of acid and neopentyl glycol is reduced, and the purity of the neopentyl glycol product is improved. Furthermore, the generation of ester substances is reduced, and the purity of neopentyl glycol in the crude neopentyl glycol solution is improved. Besides, ester substances in the crude neopentyl glycol solution are hydrolyzed to generate organic salt under the pressure of-85 to-65 kPa and the temperature of 165 to 170 DEG C, so that the content of the ester substances in the crude neopentyl glycol solution is further reduced, the purity of the neopentyl glycol in the crude neopentyl glycol solution is improved, the product quality is improved, and the aim of purifying the neopentyl glycol is fulfilled. The method and the system can effectively reduce the discharge capacity, improve the purification of neopentyl glycol, reduce the production cost and increase the production benefit.

Description

Technical Field

[0001] The present invention belongs to the technical field of neopentyl glycol production, and relates to a method and system for improving the purity of neopentyl glycol products. Background Art

[0002] Neopentyl glycol is a white crystalline solid with hygroscopicity, and is mainly used in the production of unsaturated resins, oil-free alkyd resins, plasticizers for polyurethane foam plastics and elastomers, surfactants, etc., and has wide applications.

[0003] The crude neopentyl glycol solution produced in the neopentyl glycol production process needs to be decontaminated by a light-removing tower and a heavy-removing tower before a neopentyl glycol aqueous solution can be obtained, and then the neopentyl glycol product can be obtained through further treatment. When the crude neopentyl glycol solution removes wastewater through the light-removing tower, ester substances will be generated. The ester substances mainly include 0.2 - 0.5% of neopentyl glycol isobutyrate, 0.1 - 0.2% of neopentyl glycol formate, 0.05 - 0.1% of neopentyl glycol hydroxypivalate, etc. The generation of ester substances seriously affects the purity and acid value of neopentyl glycol products. In addition, when the crude neopentyl glycol solution after being treated by the light-removing tower removes ester substances such as neopentyl glycol formate generated by the heavy-removing tower, new ester substances will be generated at the same time, resulting in a decrease in product purity. If the purity of neopentyl glycol is to be improved, the external discharge amount needs to be increased, resulting in waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for improving the purity of neopentyl glycol products to solve the problem of low product purity in the existing production method.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: The present application provides a method for improving the purity of neopentyl glycol products, including: before the crude neopentyl glycol solution enters the light-removing tower, adding an alkaline substance to the crude neopentyl glycol solution to make the crude neopentyl glycol solution in an ester hydrolysis environment, wherein the alkaline substance includes sodium hydroxide or barium hydroxide, and the ester substances include one or more of neopentyl glycol isobutyrate, neopentyl glycol formate, and neopentyl glycol hydroxypivalate.

[0006] Preferably, the feeding mass ratio of the crude neopentyl glycol solution to the alkaline substance is 1:(0.002 - 0.003).

[0007] Preferably, the concentration of the alkaline substance is 1 - 2%.

[0008] Preferably, the pressure in the light-removing tower is -85 to -65 kPa, and the bottom temperature of the tower is 165 - 170 °C.

[0009] Preferably, the temperature of the alkaline substance is 15 - 30 °C.

[0010] The present application provides a system for improving the purity of neopentyl glycol products, including a de-light tower and a de-heavy tower connected in communication. The de-light tower is connected to a crude product tank and an alkaline substance storage tank respectively through the same pipeline.

[0011] Preferably, a de-light tower feed flowmeter is provided between the crude product tank and the de-light tower.

[0012] Preferably, a metering pump, a metering pump outlet flowmeter, and a metering pump outlet regulating valve are successively provided between the alkaline substance storage tank and the de-light tower, and the de-light tower feed flowmeter is located between the metering pump outlet regulating valve and the de-light tower.

[0013] Preferably, a de-light tower bottom pump, a pH meter, and a de-heavy tower feed flowmeter are successively provided between the de-light tower and the de-heavy tower.

[0014] The present invention has the following beneficial effects: (1) Before entering the de-light tower, an alkaline substance is added to the crude neopentyl glycol solution to make the crude neopentyl glycol solution in an ester hydrolysis environment, reducing the esterification reaction between acid and neopentyl glycol, thereby reducing the generation of esters and improving the purity of neopentyl glycol in the crude neopentyl glycol solution.

[0015] (2) At a pressure of -85 to -65 kPa and a temperature of 165 - 170 °C, esters such as neopentyl glycol formate and neopentyl glycol isobutyrate in the crude neopentyl glycol solution undergo hydrolysis to generate organic salts such as sodium formate, neopentyl glycol, and sodium isobutyrate, further reducing the content of esters in the crude neopentyl glycol solution, improving the purity of neopentyl glycol in the crude neopentyl glycol solution, improving the product quality, and achieving the purpose of purifying neopentyl glycol.

[0016] (3) This method and system can effectively reduce the external discharge volume, improve the purification of neopentyl glycol, reduce the production cost, and increase the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the system for improving the purity of neopentyl glycol products provided by the embodiment of the present application; Symbol representation: 1 - crude product tank, 2 - alkaline substance storage tank, 3 - metering pump, 4 - de-light tower bottom pump, 5 - de-light tower, 6 - de-heavy tower, 7 - pH meter, 8 - de-light tower feed flowmeter, 9 - metering pump outlet flowmeter, 10 - metering pump outlet regulating valve, 11 - de-heavy tower feed flowmeter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present application provides a system for improving the purity of neopentyl glycol products. The system includes a light - removal tower 5 and a heavy - removal tower 6 that are connected. The light - removal tower 5 is connected to a crude product tank 1 and an alkaline substance storage tank 2 through the same pipeline, as shown in the appendix. Figure 1 The crude product tank 1 is a device for storing the crude neopentyl glycol solution, and the alkaline substance storage tank 2 is a device for storing alkaline substances. Both the crude product tank 1 and the alkaline substance storage tank 2 are connected to the light - removal tower 5 through the same pipeline, so that the crude neopentyl glycol solution and the alkaline substance are mixed in the pipeline and then introduced into the light - removal tower 5 to complete the process of removing wastewater.

[0019] In the embodiment of the present application, a light - removal tower feed flowmeter 8 is provided between the crude product tank 1 and the light - removal tower 5 to control the flow rate of the mixed liquid of the crude neopentyl glycol solution and the alkaline substance entering the light - removal tower 5. Between the alkaline substance storage tank 2 and the light - removal tower 5, a metering pump 3, a metering pump outlet flowmeter 9, and a metering pump outlet regulating valve 10 are arranged in sequence, and the light - removal tower feed flowmeter 8 is located between the metering pump outlet regulating valve 10 and the light - removal tower 5. Under the action of the metering pump outlet regulating valve 10 and the metering pump 3, the alkaline substance storage tank 2 introduces alkaline substances into the light - removal tower 5 through the metering pump outlet flowmeter 9 to control the addition amount of the alkaline substance, so that when the crude neopentyl glycol solution and the alkaline substance reach the bottom of the light - removal tower 5, the crude neopentyl glycol solution is in an ester hydrolysis environment. In the embodiment of the present application, the ester substances refer to the ester substances generated when the crude neopentyl glycol solution removes wastewater in the light - removal tower 5, including one or more of neopentyl glycol isobutyrate, neopentyl glycol formate, and neopentyl glycol hydroxypivalate.

[0020] In the embodiment of the present application, a temperature control device is provided on the alkaline substance storage tank 2 to make the temperature of the material in the alkaline substance storage tank 2 be 15 - 30 °C. A pressure regulating device is provided at the top of the light - removal tower 5 to maintain the pressure inside the light - removal tower 5 at - 85 - - 65 kpa. A temperature control device is also provided at the bottom of the light - removal tower 5 to make the temperature at the bottom of the light - removal tower 5 be 165 - 170 °C.

[0021] In the embodiment of the present application, a light - removal tower bottom pump 4, a pH meter 7, and a heavy - removal tower feed flowmeter 11 are arranged in sequence between the light - removal tower 5 and the heavy - removal tower 6. Among them, the pH meter 7 is used to monitor the hydrolysis environment at the bottom of the light - removal tower 5 in real time, and then facilitate the adjustment of the flow rates of the materials in the crude product tank 1 and the alkaline substance storage tank 2. After the light - removal tower 5 removes wastewater from the crude neopentyl glycol solution, under the monitoring of the pH meter 7, it is discharged into the heavy - removal tower 6 through the light - removal tower bottom pump 4 and the heavy - removal tower feed flowmeter 11, and then the removal of ester substances is completed to improve the product purity of neopentyl glycol.

[0022] The present application also provides a method for improving the purity of neopentyl glycol products. The method includes: before the crude neopentyl glycol solution enters the light removal tower 5, adding an alkaline substance to the crude neopentyl glycol solution through the alkaline substance storage tank 2 to make the crude neopentyl glycol solution in an ester hydrolysis environment, reducing the esterification reaction between acid and neopentyl glycol, and thus reducing the generation of esters. In addition, when the crude neopentyl glycol solution is in an ester hydrolysis environment, esters such as neopentyl glycol formate and neopentyl glycol isobutyrate can be hydrolyzed to generate organic salts such as sodium formate, neopentyl glycol, and sodium isobutyrate, further reducing the content of esters in the crude neopentyl glycol solution, improving the purity of neopentyl glycol in the crude neopentyl glycol solution, and improving the product quality. The organic salts generated by the hydrolysis of esters are removed by the heavy removal tower 6.

[0023] In the embodiment of the present application, the temperature of the alkaline substance is 15-30°C, which includes sodium hydroxide or barium hydroxide with a concentration of 1-2%. The feed mass ratio of the crude neopentyl glycol solution to the alkaline substance is 1:(0.002-0.003) to control the crude neopentyl glycol solution at the bottom of the light removal tower 5 in an ester hydrolysis environment. After adding the alkaline substance, the purity of neopentyl glycol in the crude neopentyl glycol solution rises from 97.5% to over 99%, and the content of neopentyl glycol formate decreases from 0.1-0.2% to 0, which greatly improves the purity of neopentyl glycol in the crude neopentyl glycol solution and is beneficial to the removal of esters by the heavy removal tower 6. After the esters are removed by the heavy removal tower 6, the purity of neopentyl glycol increases from 99.3% to 99.7%.

[0024] In the embodiment of the present application, the pressure in the light removal tower 5 is -85--65 kpa, and the bottom temperature is 165-170°C.

[0025] The technical solution of the present invention will be further explained and illustrated through specific embodiments below.

[0026] Example 1 The embodiment of the present application provides a method for improving the purity of neopentyl glycol products. The method includes: before the crude neopentyl glycol solution with a pH value of 6 enters the light removal tower, adding sodium hydroxide with a concentration of 1% to the crude neopentyl glycol solution according to the feed mass ratio of the crude neopentyl glycol solution to sodium hydroxide of 1:0.002 to make the crude neopentyl glycol solution in an ester hydrolysis environment. After the sodium hydroxide is mixed with the crude neopentyl glycol solution, it reacts in a light removal tower with a pressure of -85 kpa and a temperature of 165°C. After the reaction, the mixed solution is passed into the heavy removal tower to remove organic salts and esters to form a neopentyl glycol solution.

[0027] Example 2 The embodiments of the present application provide a method for improving the purity of neopentyl glycol products. The method includes: before the crude neopentyl glycol solution with a pH value of 6 enters the light removal tower, barium hydroxide with a concentration of 2% is added to the crude neopentyl glycol solution according to the feeding mass ratio of the crude neopentyl glycol solution to barium hydroxide of 1:0.003, so that the crude neopentyl glycol solution is in an ester hydrolysis environment. After barium hydroxide is mixed with the crude neopentyl glycol solution, the reaction takes place in a light removal tower under a pressure of -65 kPa and a temperature of 170 °C. After the reaction is completed, the mixed liquid is introduced into a heavy removal tower to remove organic salts and ester substances, forming a neopentyl glycol solution.

[0028] Example 3 The embodiments of the present application provide a method for improving the purity of neopentyl glycol products. The method includes: before the crude neopentyl glycol solution with a pH value of 6 enters the light removal tower, sodium hydroxide with a concentration of 1.5% is added to the crude neopentyl glycol solution according to the feeding mass ratio of the crude neopentyl glycol solution to sodium hydroxide of 1:0.002, so that the crude neopentyl glycol solution is in an ester hydrolysis environment. After sodium hydroxide is mixed with the crude neopentyl glycol solution, the reaction takes place in a light removal tower under a pressure of -75 kPa and a temperature of 168 °C. After the reaction is completed, the mixed liquid is introduced into a heavy removal tower to remove organic salts and ester substances, forming a neopentyl glycol solution.

[0029] Among them, the contents of various impurities in the crude neopentyl glycol solution and the neopentyl glycol solution in Examples 1-3 are shown in Table 1.

[0030] Table 1: Contents of various impurities in the crude neopentyl glycol solution and the neopentyl glycol solution in Examples 1-3 As can be seen from Table 1, after using the method provided by the embodiments of the present application, the contents of ester substances such as neopentyl glycol butyrate, neopentyl glycol formate, and neopentyl glycol hydroxypivalate are greatly reduced. The purity of neopentyl glycol in the neopentyl glycol solution rises from 97.5% to over 99%, improving the product quality and achieving the purpose of purifying neopentyl glycol.

[0031] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving the purity of neopentyl glycol products, characterized in that, Including: Before the crude neopentyl glycol solution enters the light component removal column, an alkaline substance is added to the crude neopentyl glycol solution to make the crude neopentyl glycol solution in a hydrolysis environment of ester substances. Wherein, the alkaline substance includes sodium hydroxide or barium hydroxide, and the ester substances include one or more of neopentyl glycol isobutyrate, neopentyl glycol formate, and neopentyl glycol hydroxypivalate.

2. The method for improving the purity of neopentyl glycol product according to claim 1, characterized in that, The feeding mass ratio of the crude neopentyl glycol solution to the alkaline substance is 1:(0.002 - 0.003).

3. The method for improving the purity of neopentyl glycol product according to claim 1, wherein The concentration of the alkaline substance is 1 - 2%.

4. The method for improving the purity of neopentyl glycol product according to claim 1, wherein The pressure in the light component removal column is -85 to -65 kPa, and the bottom temperature of the column is 165 - 170 °C.

5. The method for improving the purity of neopentyl glycol product according to claim 1, characterized in that, The temperature of the alkaline substance is 15 - 30 °C.

6. A system for improving the purity of neopentyl glycol products, characterized in that, Including a connected light component removal column (5) and a heavy component removal column (6), the light component removal column (5) is respectively connected to a crude product tank (1) and an alkaline substance storage tank (2) through the same pipeline.

7. The system for improving the purity of neopentyl glycol product according to claim 6, wherein A light component removal column feed flowmeter (8) is provided between the crude product tank (1) and the light component removal column (5).

8. The system for improving the purity of neopentyl glycol product according to claim 7, characterized in that, A metering pump (3), a metering pump outlet flowmeter (9), and a metering pump outlet regulating valve (10) are sequentially provided between the alkaline substance storage tank (2) and the light component removal column (5), and the light component removal column feed flowmeter (8) is located between the metering pump outlet regulating valve (10) and the light component removal column (5).

9. The system for improving the purity of neopentyl glycol product according to claim 6, characterized in that, A light component removal column bottom pump (4), a pH meter (7), and a heavy component removal column feed flowmeter (11) are sequentially provided between the light component removal column (5) and the heavy component removal column (6).

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