Refining and purifying method of 1, 3-butanediol

Abstract

The invention discloses a refining and purifying method of 1, 3-butanediol, and belongs to the field of purification of chemicals. The method comprises the following steps: feeding crude 1, 3-butanediol into a light component removal tower from a storage tank, and separating to obtain a light component I and a tower kettle heavy component I; feeding the tower kettle heavy component I into a 1, 3-butanediol tower, feeding an extracting agent into the 1, 3-butanediol tower, and separating to obtain a light component II and a tower kettle heavy component II; feeding the light component II into a heavy component removal tower, and separating to obtain a light component III and a tower kettle heavy component III; the tower kettle heavy component II is a 1, 3 butanediol product. The concentration of the separated 1, 3-butanediol can reach 99.9% or above. According to the method, high-purity 1, 3-butanediol can be obtained, the separation energy consumption can be saved, the extraction agent can be recycled, the separation and purification cost can be reduced, and the economic benefit can be improved.

Description

Technical Field

[0001] The present application relates to a method for refining and purifying 1,3-butanediol, and belongs to the field of purification of chemicals. Background Art

[0002] 1,3-Butanediol is an odorless, low-toxic, water-soluble diol, and its excellent product performance has been applied in many downstream areas. 1,3-Butanediol is widely used in resin, chemical, food, pharmaceutical and other industries. It is a key intermediate for drug synthesis and industrial compounds. The carboxylic acid monoester of 1,3-butanediol is an excellent plasticizer for PVC and other plastics. Compared with 2,3-butanediol commonly used in cosmetics, 1,3-butanediol has the same moisturizing properties and stronger antibacterial properties, and also has good biocompatibility. Due to the antibacterial properties of 1,3-butanediol, it is also used as an antibacterial agent for dairy and meat products. In addition, 1,3-butanediol can also be converted into 1,3-butadiene for nylon and rubber production.

[0003] The commonly used industrial routes for producing 1,3-butanediol are: 1) acetaldehyde condensation hydrogenation; 2) acrolein method; 3) biological fermentation method, etc. The acetaldehyde condensation hydrogenation method is the main technical route for producing 1,3-butanediol at present. Generally, the intermediate 3-hydroxybutyraldehyde is first generated. However, 3-hydroxybutyraldehyde has a relatively large viscosity and is not very stable. It will decompose when heated to about 85 degrees. Under the acid-base conditions of the acetaldehyde condensation reaction, it is very easy to dehydrate to form crotonaldehyde (crotonaldehyde). Crotonaldehyde contains both a carbonyl group and a C=C double bond. Under the conditions of the acetaldehyde condensation reaction, it can further condense with other aldehydes to form complex polymers, which seriously affect the purity, odor, color and other quality indicators of the product.

[0004] In order to solve the impact of byproducts and impurities on the odor, purity, etc. of 1,3-butanediol products, various documents have been reported. For example, CN112390705A discloses a method for extracting and purifying 1,3-butanediol with cyclohexane, which uses the characteristics that 1,3-butanediol has a low solubility in cyclohexane, while the reaction byproducts are very easily soluble in cyclohexane to extract and separate 1,3-butanediol. CN117024251A discloses a method for preparing pharmaceutical-grade 1,3-butanediol, which first adds a reducing agent (sodium borohydride) to a crude 1,3-butanediol mixture for reaction, and then adds a stabilizing complexing agent-stannous oxide for vacuum distillation after solid-liquid separation; although the above two methods can quickly and easily separate 1,3-butanediol, they either have incomplete separation of 1,3-butanediol, or have harsh reaction operating conditions, large investment and energy consumption, and are not suitable for industrial scale-up production. Therefore, in order to obtain colorless, odorless, high-quality 1,3-butanediol with low impurity content, it is imperative to develop an effective 1,3-butanediol refining and purification process. Summary of the invention

[0005] According to one aspect of the present application, a method for refining and purifying 1,3-butanediol is provided.

[0006] A method for refining and purifying 1,3-butanediol, the method comprising the following steps:

[0007] The crude 1,3-butanediol is fed from the storage tank into a light component removal tower to separate the light component I and the heavy component I in the bottom of the tower;

[0008] The heavy component I in the bottom of the tower is sent to a 1,3-butanediol tower, and the extractant is sent to the 1,3-butanediol tower to separate and obtain a light component II and a heavy component II in the bottom of the tower;

[0009] The light component II is sent to a deweighting tower to separate the light component III and the heavy component III in the bottom of the tower;

[0010] The heavy component II in the bottom of the tower is 1,3-butanediol product.

[0011] Optionally, the crude 1,3-butanediol has a 1,3-butanediol content of 80-96%, and impurities include ethanol, water, butanol, crotonaldehyde and polymers;

[0012] The light component I includes ethanol, water and butanol, and the heavy component I in the bottom includes 1,3-butanediol, crotonaldehyde and polymer;

[0013] The light component II includes an extractant, crotonaldehyde, and a polymer;

[0014] The light component III includes an extractant, and the heavy component III in the bottom includes crotonaldehyde and a polymer.

[0015] Optionally, the content of 1,3-butanediol in the crude 1,3-butanediol is 90-96%.

[0016] Optionally, the extractant includes an alkane compound and toluene;

[0017] The alkane compound is selected from at least one of cyclohexane and n-hexane.

[0018] Optionally, the extractant comprises cyclohexane and toluene.

[0019] Optionally, the usage ratio of cyclohexane to toluene is 1:0.5-1.

[0020] Optionally, the usage ratio of cyclohexane and toluene is 3:2.

[0021] Optionally, the light component I is cooled in a light removal tower cooler and then taken out from the top of the tower;

[0022] The heavy component I in the tower bottom is extracted from the bottom of the light removal tower and enters the middle of the 1,3-butanediol tower; the extractant enters from the top of the 1,3-butanediol tower;

[0023] The light component II enters the top of the deweighting tower.

[0024] Optionally, the light component III is taken out from the top of the deweighting tower, enters the solvent recovery tower, and is recycled back to the 1,3-butanediol tower for use.

[0025] Optionally, the operating conditions of the lightness removal tower are: operating pressure 0.05-0.5 bar, tower top temperature 38-50°C, tower bottom temperature 120-145°C.

[0026] Optionally, the operating conditions of the lightness removal tower are: operating pressure 0.08-0.12 bar, tower top temperature 45-50°C, tower bottom temperature 132-145°C.

[0027] Optionally, the 1,3-butanediol tower is a plate-type or packed distillation tower;

[0028] The operating conditions are: tower height of 10 to 50 theoretical plates, solvent ratio of 1 to 10, operating pressure of 0.01 to 2 bar, tower top temperature of 20 to 30° C., and tower bottom temperature of 100 to 200° C.

[0029] Optionally, the 1,3-butanediol tower is a packed distillation tower.

[0030] Optionally, the operating conditions of the 1,3-butanediol tower are: tower height is 20 to 30 theoretical plates, solvent ratio is 4 to 6, operating pressure is 0.05 to 0.15 bar, tower top temperature is 22 to 26° C., and tower bottom temperature is 120 to 141° C.

[0031] Optionally, the operating conditions of the deweighting tower are: operating pressure 0.5-2 bar, tower top temperature 60-85°C, tower bottom temperature 105-128°C.

[0032] Optionally, the operating conditions of the deweighting tower are: operating pressure 0.8-1.2 bar, tower top temperature 60-80°C, tower bottom temperature 105-120°C.

[0033] As a preferred embodiment, the method for refining and purifying 1,3-butanediol comprises the following steps:

[0034] The crude 1,3-butanediol is first separated from the storage tank by the light-removal tower, and the light components ethanol, water and butanol are cooled by the light-removal tower cooler and then enter the light-removal tower reflux tank. The heavy components in the tower bottom are sent to the butanediol tower at a set rate by the light-removal tower bottom pump. In the present invention, the crude 1,3-butanediol is a product containing 1,3-butanediol after acetaldehyde condensation hydrogenation and high-pressure flash distillation. The content of 1,3-butanediol is 80-96% of the total content of the product. The light components ethanol, water and butanol are extracted from the top of the light-removal tower; by-products such as 1,3-butanediol, polymers, and crotonaldehyde are extracted from the bottom of the tower and enter the 1,3-butanediol tower.

[0035] 1,3-Butanediol is separated in the butanediol tower by extractive distillation. Fresh extractant from the outside and circulating extractant returned from the de-weighting tower are mixed and enter the butanediol tower from the top. The product from the bottom pump of the de-lightening tower enters the butanediol tower from the middle. The heavy component 1,3-butanediol in the tower bottom is sent to the product area after being cooled to room temperature by the product cooler. The extractant and unreacted crotonaldehyde, etc. enter the de-weighting tower at the top of the tower as light components. The extractant is extracted from the top of the de-weighting tower as a light component and enters the solvent recovery tank for reuse. The heavy components in the tower bottom are discharged to the designated area. In the present invention, the butanediol tower adopts a plate or packed distillation tower with a tower height of 10-50 theoretical plates, an operating pressure of 0.01-2 bar, a solvent ratio of 1-10, a tower top temperature of 20-30°C, a tower bottom temperature of 100-200°C, and a 1,3-butanediol concentration in the heavy components at the bottom of the tower higher than 99.9%.

[0036] In the present invention, the crude 1,3-butanediol is a product containing 1,3-butanediol after acetaldehyde condensation hydrogenation and high-pressure flash distillation. The content of 1,3-butanediol is 80-96% of the total content of the product. Light components ethanol, water and butanol are extracted from the top of the light removal tower; 1,3-butanediol, polymers, crotonaldehyde and other by-products are extracted from the bottom of the tower and enter the 1,3-butanediol tower.

[0037] In the present invention, the extractant is a low-boiling composite extractant, which includes alkane compounds such as cyclohexane, n-hexane, toluene, etc. Alkane compounds such as cyclohexane, n-hexane, toluene, etc. have low boiling points and good solubility for polymers, while the solubility of 1,3-butanediol in them is extremely low. Through the compounding of multiple compounds and the synergistic effect between the components, phase separation occurs during the contact between the composite extractant and the 1,3-butanediol solution, thereby achieving the selective separation of 1,3-butanediol and byproducts such as crotonaldehyde.

[0038] The extractant is separated and recovered in the de-weighting tower. The extractant, as a light component, is cooled in the de-weighting tower cooler at the top of the de-weighting tower and then enters the solvent recovery tank for recycling. The heavy components in the tower such as by-products are taken out from the bottom of the tower.

[0039] The beneficial effects of this application include:

[0040] The present application provides a method for refining and purifying 1,3-butanediol, in which the extractant is a low-boiling composite extractant, and through the compounding of multiple compounds and the synergistic effect between the components, phase separation occurs during the contact between the compounded solvent and the 1,3-butanediol solution, thereby achieving selective separation of 1,3-butanediol and by-products such as crotonaldehyde. The separated 1,3-butanediol can reach a concentration of more than 99.6%. In addition, by reasonably designing the process flow, not only can high-purity 1,3-butanediol be obtained, but also separation energy consumption can be saved, the extractant can be recovered, the separation and purification cost can be reduced, and the economic benefit can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a process diagram for separating and purifying 1,3-butanediol in one embodiment of the present application. DETAILED DESCRIPTION

[0042] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0043] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0044] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0045] The present invention provides a separation and purification process of 1,3-butanediol, as shown in the following Figure 1 As shown. The process includes a crude 1,3-butanediol tank, a light-removing tower, a 1,3-butanediol tower, a heavy-removing tower, and a solvent recovery tower. Specifically, the crude 1,3-butanediol tank is a crude product storage tank for storing 1,3-butanediol products after condensation and hydrogenation of acetaldehyde. The storage tank is connected to the light-removing tower. After the crude 1,3-butanediol product is separated by the light-removing tower, light components such as ethanol, water and butanol are extracted from the top of the tower, and 1,3-butanediol and other heavy components are extracted from the bottom of the tower. The heavy components extracted from the bottom of the tower are sent to the 1,3-butanediol tower at a set rate by the bottom pump of the light-removing tower for extraction and separation.

[0046] The 1,3-butanediol tower is a tower for extracting the bottom of the light-removal tower containing 1,3-butanediol for separation. The top of the tower is connected to the heavy-removal tower, and the extractant enters from the top of the tower. During the extraction and separation process of the 1,3-butanediol tower, a mixture of the extractant and crotonaldehyde is extracted from the top of the tower, and the 1,3-butanediol product is extracted from the bottom of the tower.

[0047] The deweighting tower is a tower for separating and recovering the extractant. The bottom of the tower is connected to the heavy component tank, and the top of the tower is connected to the extractant recovery tank. During the separation and recovery of the extractant, cyclohexane, toluene and other composite extractants are produced at the top of the tower, and the crotonaldehyde by-product is produced at the bottom of the tower.

[0048] Example 1

[0049] T101: The crude 1,3-butanediol tank contains 95% 1,3-butanediol, 3% ethanol, water and other light components, and 2% other by-products. The liquid product enters the light-removal tower at a flow rate of 16kg / h. The operating pressure of the light-removal tower is 0.1bar, the top temperature is 45℃, and the bottom temperature is 132℃. The light components ethanol, water and butanol are cooled by the light-removal tower cooler and then taken out from the top of the tower at a rate of 3.5kg / h. The heavy components in the bottom of the tower are sent to the 1,3-butanediol tower by the bottom pump of the light-removal tower at a rate of 13kg / h.

[0050] T102: The mixture taken out from the bottom of the light removal tower enters the middle of the 1,3-butanediol tower. The extractant enters from the top of the 1,3-butanediol tower, whereby the 1,3-butanediol mixture to be separated contacts the extractant in countercurrent in the tower. Under the action of the extractant, 1,3-butanediol is separated from other components, the extractant mixture is taken out from the top of the tower, and 1,3-butanediol is taken out from the bottom of the tower. The packing height of the 1,3-butanediol tower is 20 theoretical plates, the operating pressure is 0.1 bar, the solvent ratio is 5, the top temperature is 25°C, the bottom temperature is 141°C, the extractant inlet temperature is 25°C, and the extractant includes cyclohexane and toluene, of which cyclohexane accounts for 60% and toluene accounts for 40%. The heavy component 1,3-butanediol in the bottom of the tower is cooled to room temperature by the product cooler and sent to the tank area. The purity of 1,3-butanediol is greater than 99.99%. The composite extractant and unreacted crotonaldehyde are extracted as light components at the top of the tower and enter the de-weighting tower.

[0051] T103: The mixture extracted from the top of the 1,3-butanediol tower enters the de-weighting tower for separation of the extractant. The extractant is extracted from the top of the tower, and the heavy components in the bottom of the tower enter the tank area. The operating pressure of the de-weighting tower is 1 bar, the top temperature is 80°C, and the bottom temperature is 117°C. Cyclohexane and toluene, as light components, are cooled by the de-weighting tower cooler at the top of the tower and enter the de-weighting tower reflux tank. Part of the toluene returns to the de-weighting tower through the de-weighting tower reflux pump, and the remaining toluene and cyclohexane return to the solvent recovery tank for reuse.

[0052] Example 2

[0053] T201: The crude 1,3-butanediol tank contains 95% 1,3-butanediol, 3% ethanol, water and other light components, and 2% other by-products. The liquid product enters the light-removal tower at a flow rate of 12kg / h. The operating pressure of the light-removal tower is 0.1bar, the top temperature is 50℃, and the bottom temperature is 145℃. The light components ethanol, water and butanol are cooled by the light-removal tower cooler and then taken out from the top of the tower at a rate of 2.5kg / h. The heavy components in the bottom of the tower are sent to the 1,3-butanediol tower by the bottom pump of the light-removal tower at a rate of 11kg / h.

[0054] T202: The mixture taken out from the bottom of the light removal tower enters the middle of the 11,3-butanediol tower. The extractant enters from the top of the 1,3-butanediol tower, so that the 1,3-butanediol mixture to be separated contacts the extractant in countercurrent in the tower. Under the action of the extractant, 1,3-butanediol is separated from other components, the extractant mixture is taken out from the top of the tower, and 1,3-butanediol is taken out from the bottom of the tower. The packing height of the 1,3-butanediol tower is 30 theoretical plates, the operating pressure is 0.1 bar, the solvent ratio is 5, the top temperature is 25°C, the bottom temperature is 120°C, the extractant inlet temperature is 25°C, and the extractant includes cyclohexane and toluene, of which cyclohexane accounts for 60% and toluene accounts for 40%. The heavy component 1,3-butanediol in the bottom of the tower is cooled to room temperature by the product cooler and sent to the tank area. The purity of 1,3-butanediol is greater than 99.99%. The composite extractant and unreacted crotonaldehyde are extracted as light components at the top of the tower and enter the de-weighting tower.

[0055] T203: The mixture extracted from the top of the 1,3-butanediol tower enters the de-weighting tower for separation of the extractant. The extractant is extracted from the top of the tower, and the heavy components in the bottom of the tower enter the tank area. The operating pressure of the de-weighting tower is 1 bar, the top temperature is 70°C, and the bottom temperature is 105°C. Cyclohexane and toluene, as light components, are cooled by the de-weighting tower cooler at the top of the tower and enter the de-weighting tower reflux tank. Part of the toluene returns to the de-weighting tower through the de-weighting tower reflux pump, and the remaining toluene and cyclohexane return to the solvent recovery tank for reuse.

[0056] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for refining and purifying 1,3-butanediol, characterized in that: The method comprises the following steps: The crude 1,3-butanediol is fed from the storage tank into a light component removal tower to separate the light component I and the heavy component I in the bottom of the tower; The heavy component I in the bottom of the tower is sent to a 1,3-butanediol tower, and the extractant is sent to the 1,3-butanediol tower to separate and obtain a light component II and a heavy component II in the bottom of the tower; The light component II is sent to a deweighting tower to separate the light component III and the heavy component III in the bottom of the tower; The heavy component II in the bottom of the tower is 1,3-butanediol product.

2. The method according to claim 1, characterized in that The crude 1,3-butanediol has a 1,3-butanediol content of 80-96%, and impurities include ethanol, water, butanol, crotonaldehyde and polymers; The light component I includes ethanol, water and butanol, and the heavy component I in the bottom includes 1,3-butanediol, crotonaldehyde and polymer; The light component II includes an extractant, crotonaldehyde, and a polymer; The light component III includes an extractant, and the heavy component III in the bottom includes crotonaldehyde and a polymer.

3. The method according to claim 1, characterized in that The extractant includes alkane compounds and toluene; The alkane compound is selected from at least one of cyclohexane and n-hexane.

4. The method according to claim 1, characterized in that: The light component I is cooled in a light removal tower cooler and then extracted from the top of the tower; The heavy component I in the bottom of the tower is extracted from the bottom of the light removal tower and enters the middle of the 1,3-butanediol tower; the extractant enters from the top of the 1,3-butanediol tower; The light component II enters the top of the deweighting tower.

5. The method according to claim 4, characterized in that The light component III is taken out from the top of the deweighting tower, enters the solvent recovery tower, and is recycled back to the 1,3-butanediol tower for use.

6. The method according to claim 1, characterized in that The operating conditions of the light removal tower are: operating pressure 0.05-0.5 bar, tower top temperature 38-50° C., tower bottom temperature 120-145° C.

7. The method according to claim 1, characterized in that The 1,3-butanediol tower is a plate-type or packed distillation tower; The operating conditions are: tower height of 10 to 50 theoretical plates, solvent ratio of 1 to 10, operating pressure of 0.01 to 2 bar, tower top temperature of 20 to 30° C., and tower bottom temperature of 100 to 200° C.

8. The method according to claim 1, characterized in that The operating conditions of the deweighting tower are: operating pressure 0.5-2 bar, tower top temperature 60-85° C., tower bottom temperature 105-128° C.

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