Method for producing 1, 3-butanediol

Abstract

Provided is a method for producing high-purity 1, 3-butanediol having a high potassium permanganate test value, a very low content of low-boiling-point components, and a high initial boiling point at a high recovery rate. A method for producing 1, 3-butanediol, in which purified 1, 3-butanediol is obtained from a crude reaction liquid containing 1, 3-butanediol, in which a feed liquid containing 1, 3-butanediol and water and having an acetaldehyde content of 1,000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled in a dehydration tower used in a dehydration step, a low-boiling-point component concentrate containing water is distilled from above the feed layer, and a 1, 3-butanediol concentrate containing 1, 3-butanediol is obtained from a crude reaction liquid containing 1, 3-butanediol. In a product tower used in the product distillation step, a 1, 3-butanediol charging liquid having an acetaldehyde content of 500 ppm or less and a crotonaldehyde content of 200 ppm or less is distilled under the condition that the reflux ratio exceeds 0.1.

Description

[0001] This application is a divisional application of an application filed on December 23, 2020, with application number 202080090560.4 and invention name “Method for producing 1,3-butanediol”. Technical Field

[0002] The present disclosure relates to a method for producing 1,3-butanediol. This application claims priority to Japanese Patent Application Nos. 2019-239974, 2019-239975, 2019-239976, 2019-239977, 2019-239978, 2019-239979 filed in Japan on December 28, 2019, 2020-006660 filed in Japan on January 20, 2020, and 2020-018910 filed in Japan on February 6, 2020, and the contents thereof are incorporated herein by reference. Background Art

[0003] 1,3-Butanediol is a colorless, transparent, odorless liquid with low volatility, low toxicity, high hygroscopicity, and excellent chemical stability. Therefore, the uses of 1,3-Butanediol include raw materials for various synthetic resins and surfactants, as well as raw materials for cosmetics, hygroscopic agents, high-boiling-point solvents, and antifreeze. In recent years, 1,3-Butanediol has attracted much attention for its excellent properties as a moisturizer, expanding its demand in the cosmetics industry.

[0004] The crude reaction liquid during the production of 1,3-butanediol contains a large amount of low-boiling impurities such as ethanol, butanol, acetaldehyde, crotonaldehyde, and esters. Among them, if acetaldehyde, crotonaldehyde, etc. are dimerized or polymerized, high-boiling impurities are generated. In addition, in the purification process of 1,3-butanediol, low-boiling impurities and high-boiling impurities can also be generated by heat, etc. In the product of 1,3-butanediol, the less such impurities, the better. In Japanese Patent Publication No. 6-329664, a method for controlling impurities derived from low-boiling impurities, namely crotonaldehyde, is disclosed. In Japanese Patent Publication No. 2001-213828, it is disclosed that if the crude reaction liquid of 1,3-butanediol synthesized by hydrogenation of butanol aldehydes is alkalized and distilled to remove alcohol, it is possible to produce high-purity 1,3-butanediol products with good yield and economically advantageous. Furthermore, this document describes that low-boiling impurities, namely, ethanol, isopropanol, and butanol, are removed by distillation.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 6-329664

[0008] Patent Document 2: Japanese Patent Application Publication No. 2001-213828 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] However, the existing methods cannot fully remove the low-boiling point components and high-boiling point components derived from 1,3-butanediol. Cosmetics, which are important uses of 1,3-butanediol, usually contain water, and it takes a long time from production to actual use by ordinary consumers. In addition, from the perspective of storage stability, the liquid properties of cosmetics are strictly controlled.

[0011] When 1,3-butylene glycol containing low-boiling point components and high-boiling point components is used in cosmetics, the liquid balance of the cosmetics may be disrupted due to the increase in acid concentration, and the intended effect may be lost. In addition, the increase in the acid concentration of the cosmetics may also cause the user's skin to become rough.

[0012] Furthermore, when using cosmetics and storing them after use, the cosmetics are exposed to air. In addition, when manufacturing cosmetics, the work is usually carried out in an air atmosphere, and sometimes heating is used for the purpose of sterilization. When 1,3-butanediol containing a low boiling point component and a high boiling point component is used in cosmetics, it may be colored due to the presence of air and the influence of heating.

[0013] In order to solve this problem, it is necessary to remove by-products from crude 1,3-butanediol and purify 1,3-butanediol.

[0014] On the other hand, one of the quality standards of 1,3-butanediol is the initial distillation point. It can be said that the higher the initial distillation point, the better the quality. However, there has been almost no technical research aimed at improving the initial distillation point. In addition, one of the quality standards of 1,3-butanediol is the dry point. It can be said that the lower the dry point, the better the quality. If high-boiling point impurities generated in the reaction process and the purification process are mixed into the product, not only will the purity of the product be reduced, but it will also become a cause of the increase in the dry point, resulting in a problem of deviation from the product quality standard. However, there has been almost no research on the separation and removal method of high-boiling point impurities. Furthermore, one of the product standards of 1,3-butanediol is the potassium permanganate test value (abbreviated as: PMT), but the potassium permanganate test value of 1,3-butanediol products obtained by the existing method may not be completely satisfactory. In addition, in the past, the substance that caused the potassium permanganate test value of 1,3-butanediol products to decrease could not be identified. That is, conventionally, there has been no method for efficiently producing industrially 1,3-butanediol products having excellent initial boiling point and dry point, initial boiling point and potassium permanganate test value, or three properties including initial boiling point, dry point and potassium permanganate test value.

[0015] Therefore, an object of the present disclosure is to provide a method capable of industrially efficiently producing high-purity 1,3-butanediol having very low contents of low-boiling-point components and high-boiling-point components, a high initial distillation point, and a low drying point.

[0016] Another object of the present disclosure is to provide a method capable of industrially and efficiently producing high-purity 1,3-butanediol having a very small content of low-boiling point components, a high initial boiling point, and a high potassium permanganate test value.

[0017] Another object of the present disclosure is to provide a method for industrially and efficiently producing high-purity 1,3-butanediol having a high potassium permanganate test value, very small contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low drying point.

[0018] Technical Solution

[0019] The inventors of the present disclosure have conducted in-depth research to achieve the above-mentioned purpose, and found that by specifying the acetaldehyde and crotonaldehyde contents in the charge liquid flowing to the dehydration tower, and at the same time, in the product tower, the charge liquid with acetaldehyde and crotonaldehyde contents below a specific value is distilled at a specific reflux ratio, and high-purity 1,3-butanediol with very little low-boiling and high-boiling components is obtained from below the charge layer. In addition, by specifying the acetaldehyde and crotonaldehyde contents in the charge liquid flowing to the dehydration tower, and at the same time, if the charge liquid containing 1,3-butanediol is distilled at a specific reflux ratio in the de-high boiling tower, high-purity 1,3-butanediol with very little low-boiling and high-boiling components is obtained from above the charge layer. The present disclosure is completed by further research based on these insights.

[0020] That is, the present disclosure provides a method for producing 1,3-butanediol from a crude reaction liquid containing 1,3-butanediol (hereinafter, sometimes referred to as "production method 1 of the present disclosure"), which comprises:

[0021] A dehydration step of removing water by distillation; a high boiling point removal step of removing high boiling point components by distillation; and a product distillation step for obtaining purified 1,3-butanediol,

[0022] In the dehydration tower used in the dehydration step, a charge liquid containing 1,3-butanediol and water and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling-point component concentrate containing water is distilled from above the charge layer.

[0023] In the product tower used in the product distillation step, a 1,3-butanediol charge liquid having an acetaldehyde content of less than 500 ppm and a crotonaldehyde content of less than 200 ppm is distilled under a reflux ratio exceeding 0.1, a low-boiling point component concentrate is distilled from above the charge layer, and 1,3-butanediol is extracted from below the charge layer.

[0024] In the production method, it is preferred that the charge liquid containing 1,3-butanediol is distilled at a reflux ratio of 0.02 or more in the high boiling point removal tower used in the high boiling point removal step, 1,3-butanediol with higher purity is distilled from above the charge layer, and a high boiling point component concentrate is extracted from below the charge layer.

[0025] Furthermore, it is preferred that the concentration of 1,3-butanediol in the feed liquid flowing to the product column is 90 GC area % or more, and the water content in the feed liquid is 3 wt % or less.

[0026] The present disclosure also provides a method for producing 1,3-butanediol from a crude reaction liquid containing 1,3-butanediol (hereinafter sometimes referred to as "production method 2 of the present disclosure"), comprising:

[0027] A dehydration step of removing water by distillation; and a high boiling point removal step of removing high boiling point components by distillation,

[0028] In the dehydration tower used in the dehydration step, a charge liquid containing 1,3-butanediol and water and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling-point component concentrate containing water is distilled from above the charge layer.

[0029] In the high boiling point removal tower used in the high boiling point removal step, the charge liquid containing 1,3-butanediol is distilled at a reflux ratio exceeding 0.02, 1,3-butanediol with higher purity is distilled from the upper portion of the charge layer, and a high boiling point component concentrate is extracted from the lower portion of the charge layer.

[0030] In each of the above production methods, it is preferred that the reflux ratio of the dehydration tower is 0.03 or more.

[0031] Furthermore, the crude reaction liquid containing the 1,3-butanediol may be a crude reaction liquid obtained by hydrogen reduction of butanol aldehydes.

[0032] Each of the production methods may further include at least one of an alkali treatment step of treating a process stream containing 1,3-butanediol with an alkali, a desalting step of removing salt from the process stream containing 1,3-butanediol, and a dealcoholization step of removing low-boiling substances including alcohol from the process stream containing 1,3-butanediol.

[0033] It should be noted that in the present disclosure, a "1,3-butanediol product" refers to a composition in which 1,3-butanediol accounts for most of the constituent components (for example, the 1,3-butanediol content is 95% by weight or more, preferably 98% by weight or more).

[0034] Beneficial Effects

[0035] According to the production method disclosed in the present invention, high-purity 1,3-butanediol having very low contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low dry point can be produced industrially and efficiently; high-purity 1,3-butanediol having very low contents of low-boiling point components, a high initial distillation point and a high potassium permanganate test value can be produced industrially and efficiently; further, high-purity 1,3-butanediol having a high potassium permanganate test value, very low contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low dry point can be produced industrially and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart showing an example of the method for producing 1,3-butanediol (purification method) of the present disclosure. DETAILED DESCRIPTION

[0037] [1,3-Butanediol Production Method]

[0038] In the production method 1 of the present disclosure, a method for producing 1,3-butanediol for obtaining purified 1,3-butanediol from a crude reaction liquid containing 1,3-butanediol (1,3BG) (hereinafter, sometimes referred to as "crude 1,3-butanediol") comprises a dehydration step for removing water by distillation, a high boiling point removal step for removing high boiling point components by distillation, and a product distillation step for obtaining purified 1,3-butanediol. Then, in the dehydration tower used in the dehydration process, a charge liquid containing 1,3-butanediol and water, and having an acetaldehyde (AD) content of 1000 ppm or less and a crotonaldehyde (CR) content of 400 ppm or less is distilled, and a low-boiling-point component concentrated liquid containing water is distilled from the upper portion of the charge layer. In the product tower used in the product distillation process, a 1,3-butanediol charge liquid having an acetaldehyde content of 500 ppm or less and a crotonaldehyde content of 200 ppm or less is distilled under a reflux ratio exceeding 0.1, and a low-boiling-point component concentrated liquid is distilled from the upper portion of the charge layer, and 1,3-butanediol is extracted from the lower portion of the charge layer. The 1,3-butanediol thus obtained has a high potassium permanganate test value, very low contents of low-boiling-point components and high-boiling-point components, a high initial distillation point and a low dry point, and can therefore be used as a 1,3-butanediol product.

[0039] In the manufacturing method 2 of the present disclosure, a 1,3-butanediol manufacturing method for obtaining purified 1,3-butanediol from a crude reaction liquid (crude 1,3-butanediol) containing 1,3-butanediol has a dehydration step of removing water by distillation and a high-boiling point removal step of removing high-boiling point components by distillation. Then, in a dehydration tower used in the dehydration step, a charge liquid containing 1,3-butanediol and water, and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling point component concentrated liquid containing water is distilled from above the charge layer. In a high-boiling point removal tower used in the high-boiling point removal step, a charge liquid containing 1,3-butanediol is distilled under a reflux ratio of more than 0.02, and a higher-purity 1,3-butanediol is distilled from above the charge layer, and a high-boiling point component concentrated liquid is extracted from below the charge layer. The 1,3-butanediol thus obtained has very small contents of low-boiling-point components and high-boiling-point components, and therefore can be used as a 1,3-butanediol product by alkali treatment as necessary.

[0040] The “manufacturing method 1 of the present disclosure” and the “manufacturing method 2 of the present disclosure” are sometimes collectively referred to as the “manufacturing method of the present disclosure”.

[0041] In addition, the "GC area %" in this specification means the ratio of the peak area of ​​the component to the total peak area in the gas chromatography analysis described below.

[0042] [Crude 1,3-butanediol]

[0043] Examples of crude 1,3-butanediol include: (1) a crude reaction liquid obtained by reduction (hydrogenation) of butanol aldehydes; (2) a crude reaction liquid obtained by hydrolysis of 1,3-butylene oxide; (3) a crude reaction liquid obtained by selective hydrocracking of erythritol; (4) a crude reaction liquid obtained by selective water addition of butadiene; (5) a crude reaction liquid obtained by hydrogenation of n-butyraldehyde-3-one; (6) a crude reaction liquid obtained by hydrogenation of 1-butanol-3-one; (7) a crude reaction liquid obtained by hydrogenation of 3-hydroxy-1-butyric acid; (8) a crude reaction liquid obtained by hydrogenation of β-butyrolactone; and (9) a crude reaction liquid obtained by hydrogenation of diketene. In the present disclosure, the crude 1,3-butanediol may be one of the above (1) to (9) or a mixture of two or more thereof. As the crude 1,3-butanediol, the crude reaction liquid obtained by the reduction (particularly liquid phase reduction) of butanol aldehydes in (1) is preferred.

[0044] Hereinafter, the case where a crude reaction liquid obtained by reduction (hydrogenation) of butanol aldehydes is used as crude 1,3-butanediol will be mainly described. In addition, the step of reducing (hydrogenating) butanol aldehydes may be referred to as a "hydrogenation step".

[0045] The butanol aldehyde used as a raw material in the hydrogenation step is not particularly limited as long as it is a compound that is reduced to 1,3-butanediol by hydrogen. Examples of the raw butanol aldehyde include butanol aldehyde, dimer m-hydroxybutyraldehyde as a cyclic dimer thereof, 2,6-dimethyl-1,3-dioxane-4-ol as a cyclic trimer of acetaldehyde, and mixtures thereof.

[0046] The method for producing butanol aldehydes (e.g., butanol aldehyde and dimer m-hydroxybutyraldehyde) is not particularly limited, and for example, it can be obtained by an aldol condensation reaction of acetaldehyde in the presence of a basic catalyst, or by thermal decomposition of 2,6-dimethyl-1,3-dioxane-4-ol, etc. It should be noted that the process of producing butanol aldehydes is sometimes referred to as a "butanol aldehyde production process" or an "acetaldehyde polymerization process."

[0047] The crude reaction liquid containing butanol aldehydes obtained by the above reaction is neutralized with acid to produce 1,3-butanediol. In addition to butanol aldehydes, such crude reaction liquid may also contain acetaldehyde (AD), crotonaldehyde (CR), other aldehyde components, low boiling point substances, high boiling point substances such as aldehyde dimers or trimers, water, and salts. It should be noted that in this specification, compounds with lower boiling points than 1,3-butanediol are sometimes referred to as "low boiling point substances" or "low boiling substances", and compounds with higher boiling points than 1,3-butanediol are referred to as "high boiling point substances" or "high boiling substances".

[0048] The reaction crude liquid containing the above-mentioned butanol aldehydes can be used to implement pre-treatments such as dealcoholization distillation, dehydration distillation, desalination, alkali treatment and dealkalization treatment, decontamination as needed to remove the material of by-products such as unreacted acetaldehyde and crotonaldehyde. As the method of pre-treatment, distillation, adsorption, ion exchange, heating high boiling point materialization, decomposition, etc. can be listed. Distillation can use various distillation methods such as reduced pressure, normal pressure, pressurization, azeotropic, extraction, reaction. In particular, the reaction crude liquid preferably containing butanol aldehydes is subjected to crude evaporation and distillation, hydrogenation, and after removing the aldehydes of acetaldehyde and crotonaldehyde, a hydrogenation process is implemented.

[0049] The content of butanol aldehydes in the hydrogenation raw material is not particularly limited, and is, for example, 30% by weight or more (e.g., 30% by weight to 99% by weight), more preferably 40% by weight or more (e.g., 40% by weight to 98% by weight), 50% by weight or more (e.g., 50% by weight to 97% by weight), or 60% by weight or more (e.g., 60% by weight to 95% by weight), further preferably 65% ​​by weight to 90% by weight, particularly preferably 70% by weight to 90% by weight, and most preferably 75% by weight to 90% by weight. When the content of butanol aldehydes is within the above range, there is a tendency that impurities contained in the crude reaction liquid (crude 1,3-butanediol) containing 1,3-butanediol are reduced.

[0050] The hydrogenation raw material may contain water or not contain water, but from the viewpoint of the purity of the 1,3-butanediol product, it is preferably contained water. The water content in the hydrogenation raw material is not particularly limited, for example, preferably 2% by weight or more, more preferably 5% by weight or more, further preferably 10% by weight or more, and particularly preferably 15% by weight or more. It should be noted that its upper limit value may be, for example, 90% by weight, 80% by weight, 70% by weight, 60% by weight, 50% by weight, 40% by weight, 30% by weight or 20% by weight. When the water content is within the above range, the acetal body of 1,3-butanediol and butanol aldehyde contained in the obtained crude 1,3-butanediol is reduced, so there is a tendency that the purity of the 1,3-butanediol product finally obtained becomes higher. The reason is that by including a certain degree of water in the hydrogenation raw material, the above-mentioned acetal body is hydrolyzed into 1,3-butanediol, and the butanol aldehyde generated together is reduced to 1,3-butanediol.

[0051] As a hydrogenation catalyst, for example, Raney nickel and the like can be cited. The hydrogenation catalyst can be used in a suspended state or filled in a reaction vessel for use. The amount of the hydrogenation catalyst used is not particularly limited, but relative to 100 parts by weight of hydrogenation raw materials, for example, preferably 1 part by weight to 30 parts by weight, more preferably 4 parts by weight to 25 parts by weight, further preferably 8 parts by weight to 20 parts by weight, and particularly preferably 12 parts by weight to 18 parts by weight. The amount of hydrogen used for the reduction reaction is not particularly limited, but relative to 100 parts by weight of hydrogenation raw materials, for example, preferably 0.5 parts by weight to 40 parts by weight, more preferably 1 part by weight to 30 parts by weight, further preferably 4 parts by weight to 20 parts by weight, and particularly preferably 8 parts by weight to 12 parts by weight. The pressure (total pressure; gauge pressure) in the reaction system during the reduction reaction is not particularly limited, for example, 9MPa to 70MPa, preferably 10MPa to 40MPa. The hydrogen pressure (partial pressure of hydrogen) in the reaction system is not particularly limited, for example, 7MPa to 60MPa, preferably 10MPa to 30MPa. It should be noted that, from the perspective of reducing reducing substances such as acetaldehyde and crotonaldehyde, it is better to increase the hydrogen pressure in the reaction system, preferably 10MPa or more, and can also be 100MPa. If the hydrogen pressure in the reaction system is increased, acetaldehyde, crotonaldehyde and other reducing substances can be harmlessly rendered harmless, and the concentration of acetaldehyde, crotonaldehyde and other reducing substances in the dehydration tower charge liquid described below, as well as trace amounts of other impurities such as acetals can be reduced. Therefore, even if the reflux ratio and distillation volume of the dehydration tower, de-high boiling tower, and product tower in the 1,3-butanediol purification process are relatively small, the benefits of maintaining product quality can be obtained.

[0052] The reaction temperature in the reduction reaction is not particularly limited, for example, 40°C to 150°C, preferably 50°C to 140°C, and more preferably 60°C to 130°C. The reaction time (residence time) in the reduction reaction is not particularly limited, for example, 10 minutes to 500 minutes, preferably 20 minutes to 400 minutes, more preferably 30 minutes to 300 minutes, further preferably 50 minutes to 280 minutes, and particularly preferably 80 minutes to 250 minutes. This reaction can be carried out in any of a batch form, a semi-batch form, or a continuous form.

[0053] The crude 1,3-butanediol thus obtained contains low-boiling substances (low-boiling compounds) having unsaturated bonds such as acetaldehyde (AD), butyraldehyde, crotonaldehyde (CR), acetone, and methyl vinyl ketone, their condensation products, condensation products of 1,3-butanediol and the above low-boiling substances (for example, acetals of 1,3-butanediol and butanolaldehyde, etc.), alcohols such as ethanol, isopropanol, and butanol, water (solvent, etc.), salts generated by neutralization treatment, etc., catalysts (when used in a suspended state), etc. By removing these impurities through the purification process, a 1,3-butanediol product (purified 1,3-butanediol) can be obtained.

[0054] [Purification of crude 1,3-butanediol]

[0055] In the production method 1 of the present disclosure, at least a dehydration step of removing water by distillation, a high boiling point removal step of removing high boiling point components by distillation (high boiling point removal distillation step), and a product distillation step for obtaining purified 1,3-butanediol are included. In the production method 2 of the present disclosure, at least a dehydration step of removing water by distillation and a high boiling point removal step of removing high boiling point components by distillation (high boiling point removal distillation step) are included.

[0056] In the manufacturing method disclosed in the present invention, the order of the dehydration process and the high boiling removal process is not distinguished. In the manufacturing method 1 disclosed in the present invention, the dehydration process and the high boiling removal process are both arranged before the product distillation process. In the manufacturing method disclosed in the present invention, in addition to these processes, there may also be a desalination process, an alkali reaction process (alkali treatment process), and a dealkalization process. In addition, before the dehydration process, a catalyst separation process, a neutralization process by alkali, and a dealcoholization process (removal of low boiling processes) may also be arranged. The various processes may be carried out in the order described, except that the dealkalization process is arranged after the alkali reaction process, and the order of the various processes may be appropriately changed. For example, the dealcoholization process (removal of low boiling processes), the desalination process, the alkali reaction process, and the dealkalization process may be arranged at appropriate positions, usually after the hydrogenation process. It should be noted that the catalyst separation process, the neutralization process by alkali, the dealcoholization process (removal of low boiling processes), the desalination process, the alkali reaction process, and the dealkalization process in the above-mentioned processes can be arranged as needed and are not necessarily arranged.

[0057] Figure 1 It is a flow chart of an apparatus representing an example of an implementation method of the 1,3-butanediol production method disclosed in the present invention. A is a dehydration tower, which is related to the dehydration process. B is a desalination tower, which is related to the desalination process. C is a high-boiling point distillation tower (high-boiling point removal tower), which is related to the high-boiling point distillation process (high-boiling point removal process). D is an alkali reactor, which is related to the alkali reaction process. E is a dealkalization tower, which is related to the dealkalization process. F is a product distillation tower (product tower), which is related to the product distillation process. A-1, B-1, C-1, E-1, and F-1 are condensers. A-2, C-2, and F-2 are reboilers. Below, this flow chart is used to illustrate an example of an implementation method of the 1,3-butanediol production method disclosed in the present invention.

[0058] The crude 1,3-butanediol (corresponding to "X-1") obtained by hydrogen reduction of the hydrogenated raw material is supplied to the dehydration tower A. The crude 1,3-butanediol (corresponding to "X-1") may be supplied to the dehydration tower A after passing through a dealcoholization step (a distillation step through a dealcoholization tower) for removing alcohols such as ethanol and low-boiling substances.

[0059] In the production method of the present disclosure, in the dehydration tower A used in the dehydration step, a charge liquid containing 1,3-butanediol and water and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling-point component concentrate containing water (equivalent to Figure 1 In addition, a crude 1,3-butanediol stream containing 1,3-butanediol is obtained from below the charge layer (preferably the column bottom).

[0060] As a distillation tower for separating the dehydration tower A and other 1,3-butanediol, for example, a porous plate tower, a bubble tower, etc. can be used, but a packed tower with low pressure loss filled with Sulzer Packings, Mellapak (both are trade names of Sumitomo Heavy Industries, Ltd.) or the like is more preferred. The reason is that 1,3-butanediol and the trace impurities contained therein are thermally decomposed at high temperatures (for example, above 150°C) to generate low-boiling substances as coloring components, thereby lowering the distillation temperature. In addition, the same influence is also produced when the thermal history (residence time) of 1,3-butanediol is long. Therefore, the reboiler used is preferably one with a shorter residence time of the process side fluid, for example, a thin film evaporator such as a natural falling film evaporator and a scraped film evaporator is preferred.

[0061] The number of theoretical plates of the dehydration tower A is, for example, 1 to 100, preferably 2 to 80, 3 to 80, 4 to 60, 5 to 40, 6 to 30 or 7 to 20, and more preferably 8 to 15. The feed liquid is supplied from the top of the tower downward, and the tower height is, for example, 10% to 90%, preferably 20% to 80%, more preferably 30% to 70%, and more preferably 40% to 60%. In the distillation of the dehydration tower A, the pressure (absolute pressure) at the top of the tower is, for example, 101 kPa or less, preferably 0.1 kPa to 90 kPa, more preferably 0.5 kPa to 70 kPa, more preferably 1 kPa to 50 kPa, 2 kPa to 30 kPa or 3 kPa to 20 kPa, and particularly preferably 4 kPa to 10 kPa. It should be noted that the distillation in the dehydration tower A may be performed under pressure. In this case, the pressure (gauge pressure) at the top of the tower may be, for example, 0.2 MPaG or less, or 0.1 MPaG or less.

[0062] The concentration of 1,3-butanediol in the feed liquid to the dehydration tower A is, for example, 9% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, further preferably 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more, and particularly preferably 70% by weight or more. The upper limit of the concentration of 1,3-butanediol in the feed liquid to the dehydration tower A is, for example, 90% by weight, 85% by weight, or 80% by weight. However, in consideration of the hydrogenation reaction in the step before the dehydration step, a higher water concentration in the feed liquid to the dehydration tower A may be preferable. In summary, the concentration of 1,3-butanediol in the feed liquid flowing to the dehydration tower A may be, for example, 1% by weight or more, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In addition, the concentration of 1,3-butanediol in the feed liquid flowing to the dehydration tower A may be, for example, 99% by weight or less, 95% by weight or more, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, or 45% by weight or less. The concentration of 1,3-butanediol in the feed liquid to the dehydration tower A can be adjusted to the above range by adjusting, for example, the reaction conditions of the hydrogenation step (e.g., the concentration of butanol aldehydes used as a raw material) and the distillation conditions of the dealcoholization tower (low boiling tower) provided as needed before the dehydration tower.

[0063] The above-mentioned 1,3-butanediol concentration (weight %) is a value obtained by the following formula by obtaining the ratio of the peak area of ​​1,3-butanediol to the total peak area (GC area %) in the gas chromatography analysis under the following conditions. The water concentration (weight %) in the feed liquid flowing to the dehydration tower A is a value measured by the method described below (Karl Fischer method).

[0064] Concentration of 1,3-butanediol in the feed liquid to the dehydration tower A (weight %)

[0065] =(1-water concentration (weight %) in the feed liquid flowing to the dehydration tower A / 100)×GC area % of the above 1,3-butanediol

[0066] (Conditions for gas chromatography analysis)

[0067] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0068] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0069] Sample introduction temperature: 250℃

[0070] Carrier gas: Helium

[0071] Column gas flow rate: 1mL / min

[0072] Detector and detection temperature: hydrogen flame ionization detector (FID), 280℃

[0073] In the production method disclosed herein, the acetaldehyde content in the charge liquid flowing to the dehydration tower A is 1000 ppm or less, and the crotonaldehyde content is 400 ppm or less. The acetaldehyde content in the charge liquid flowing to the dehydration tower A may be preferably 900 ppm or less, more preferably 800 ppm or less, 700 ppm or less, 600 ppm or less, or 500 ppm or less, and further preferably 400 ppm or less, 300 ppm or less, 200 ppm or less, 155 ppm or less, or 140 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less.

[0074] The crotonaldehyde content in the charge liquid flowing to the dehydration tower A may preferably be 300 ppm or less, more preferably 200 ppm or less, further preferably 150 ppm or less, 130 ppm or less, 117 ppm or less, or 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or 1 ppm or less.

[0075] The acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the dehydration tower A can be reduced by, for example, setting a dealcoholization tower (removal of low boiling tower) upstream of the dehydration tower A and adjusting the distillation conditions of the dealcoholization tower (removal of low boiling tower). For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization tower (removal of low boiling tower), the acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the dehydration tower A can be reduced. Furthermore, the hydrogenation reaction conditions of the hydrogenation process can also be adjusted. When hydrogenation is fully carried out, the concentrations of acetaldehyde and crotonaldehyde can be reduced to below the detection limit, but unfavorable conditions such as increased reaction pressure and larger reaction tank will occur.

[0076] It should be noted that the acetaldehyde content and crotonaldehyde content in the feed liquid flowing into the dehydration tower A can be quantitatively determined by GC-MS analysis (gas chromatography-mass spectrometry) as described below.

[0077] In the manufacturing method disclosed herein, the water content in the charge liquid flowing to the dehydration tower A is, for example, 90% by weight or less, 85% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, or 40% by weight or less, preferably 35% by weight or less, more preferably 30% by weight or less, and further preferably 25% by weight or less. The lower limit of the water content in the charge liquid flowing to the dehydration tower A is, for example, 10% by weight or 15% by weight. It should be noted that, in the case of considering the hydrogenation reaction in the hydrogenation process, the side with high water concentration and low viscosity is beneficial to the hydrogenation reaction because the solubility and dispersion of hydrogen in the liquid increase. The water content in the charge liquid flowing to the dehydration tower A can be reduced by, for example, setting a dealcoholization tower (removal of low boiling tower) upstream of the dehydration tower A and adjusting the distillation conditions of the dealcoholization tower (removal of low boiling tower). For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization tower (low-boiling tower), the water content in the feed liquid flowing to the dehydration tower A can be reduced. It should be noted that the water content in the feed liquid flowing to the dehydration tower A can be quantified by a Karl Fischer moisture meter.

[0078] In the production method disclosed herein, the content of low-boiling components (excluding water) in the feed liquid flowing to the dehydration tower A is, for example, 20% or less, preferably 10% or less, more preferably 8% or less, further preferably 5% or less, particularly preferably 3% or less or 2% or less, and may be 1% or less, 0.5% or less, or 0.1% or less. The content of low-boiling components (also referred to as "low-boiling substances" or "low-boiling substances") excluding water in the feed liquid flowing to the dehydration tower A is the total area ratio (area %) of peaks having a shorter retention time than the peak of 1,3-butanediol relative to the total peak area in the gas chromatography analysis under the above conditions. The content of low-boiling components (excluding water) in the feed liquid flowing to the dehydration tower A can be reduced by, for example, setting a dealcoholization tower (removal of low-boiling tower) upstream of the dehydration tower A and adjusting the distillation conditions of the dealcoholization tower (removal of low-boiling tower). For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization tower (low-boiling tower), the concentration of low-boiling components (excluding water) in the feed liquid flowing to the dehydration tower A can be reduced. In addition, the concentration of low-boiling components (excluding water) in the feed liquid flowing to the dehydration tower A can be reduced by, for example, the reaction conditions (for example, reaction temperature, etc.) in the hydrogenation step.

[0079] The content of the high boiling point component in the feed liquid to the dehydration tower A is, for example, 20% or less, preferably 10% or less, more preferably 7% or less, 4% or less, 3% or less, or 2% or less, further preferably 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. The content of the high boiling point component in the feed liquid to the dehydration tower A can be adjusted by, for example, the reaction conditions (e.g., reaction temperature, etc.) in the hydrogenation step. The content of the high boiling point component in the feed liquid to the dehydration tower A is the total area ratio (area %) of the peak having a longer retention time than the peak of 1,3BG relative to the total peak area in the gas chromatography analysis under the above conditions.

[0080] In the production method disclosed in the present invention, the reflux ratio of the dehydration tower A [reflux amount of the dehydration tower / distillate amount of the dehydration tower (amount discharged to the outside of the distillation tower)] is, for example, 0.03 or more. It should be noted that, in the reflux to the dehydration tower A, the condensate of the vapor from the top of the dehydration tower is usually refluxed to the dehydration tower, but a part or all of the reflux may be replaced by the water-containing liquid (e.g., pure water, etc.) charged to the dehydration tower. In this case, the "reflux amount of the dehydration tower" refers to the sum of the reflux amount of the condensate of the vapor from the top of the dehydration tower flowing to the dehydration tower and the charge amount of the water-containing liquid (e.g., pure water, etc.) flowing to the dehydration tower.

[0081] From the viewpoint of reducing the content of low boiling point substances (including water) in the crude 1,3-butanediol stream containing 1,3-butanediol withdrawn from the lower portion of the charge layer of the dehydration tower A (preferably the tower bottom), the reflux ratio of the dehydration tower A is preferably 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.12 or more, 0.14 or more, 0.16 or more, 0.18 or more, 0.2 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.28 or more, 0.3 1 or more, 0.33 or more, 0.36 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, or 9 or more, and more preferably 10 or more (e.g., 15 or more, 20 or more, 25 or more, 30 or more, or 40 or more). In particular, in the production method 2 of the present disclosure, the reflux ratio of the dehydration tower A is preferably 0.2 or more, more preferably 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.5 or more, 2 or more, 3 or more, or 4 or more, further preferably 5 or more, and particularly preferably 10 or more. From the viewpoint of energy consumption, the upper limit of the reflux ratio is, for example, 50 (less than 50), preferably 20 (less than 20), and more preferably 10 (less than 10). It should be noted that when the number of theoretical plates of the dehydration tower A is large, sufficient separation can be achieved even if the reflux ratio is about 0.03.

[0082] In the production method of the present disclosure, the distillation rate of the dehydration tower A can be appropriately set according to the concentration of water in the charge liquid flowing to the dehydration tower A. Preferably, the distillation rate is a distillation rate sufficient to distill all the water in the charge liquid. For example, when the concentration of water in the charge liquid flowing to the dehydration tower A is × weight %, it is preferred that the distillation rate of the dehydration tower A is set to × weight % or more. Therefore, the distillation rate of the dehydration tower A is, for example, 95 weight % or less, 90 weight % or less, 85 weight % or less, 80 weight % or less, 75 weight % or less, 70 weight % or less, 65 weight % or less, 60 weight % or less, 55 weight % or less, 50 weight % or less, 45 weight % or less, 40 weight % or less, 35 weight % or less, 30 weight % or less, 25 weight % or less, 20 weight % or less, 15 weight % or less, 10 weight % or less, or 5 weight % or less. The distillation rate refers to the ratio (weight %) of the amount of liquid extracted from the upper portion of the loading layer of the dehydration tower A (for example, the top portion) to the loading amount of the dehydration tower A to the outside of the distillation tower.

[0083] In the production method disclosed herein, the 1,3BG recovery rate of the dehydration tower A is, for example, 99.3% or more. In this specification, the 1,3BG recovery rate of the dehydration tower A is a value (%) calculated by the following formula.

[0084] {1-[1,3BG concentration in distillate (weight %) × (distillate amount (portion) - recycled amount (portion))] / (1,3BG concentration in charge liquid (weight %) × charge amount (portion))} × 100 It should be noted that low-boiling and high-boiling substances may generate 1,3BG through hydrolysis with water, while high-boiling substances may be generated through polymerization of 1,3BG. Furthermore, trace impurities may be generated and disappear, so the material balance in the dehydration tower may not necessarily be achieved. This also applies to other distillation towers such as the dealcoholization tower (low-boiling tower), high-boiling tower, and product tower.

[0085] Next, the crude 1,3-butanediol stream containing 1,3-butanediol taken out from the lower portion of the loading layer of the dehydration tower A (preferably the bottom of the tower) is supplied to the demineralization tower B. In the demineralization tower B, the crude 1,3-butanediol stream after desalination is obtained from the top of the tower by distillation, and salts and high boiling point substances are discharged from the bottom of the tower as the extraction liquid. The extraction rate (%) of the demineralization tower B [(extraction amount of the demineralization tower (parts)) / extraction amount of the demineralization tower (parts) × 100] is, for example, 0.1% by weight to 40% by weight, preferably 1% by weight to 35% by weight, more preferably 2% by weight to 30% by weight, further preferably 3% by weight to 25% by weight, particularly preferably 5% by weight to 20% by weight, and may also be 7% by weight to 15% by weight. It should be noted that at least a portion of the extraction liquid of the demineralization tower can be recycled in the process before the desalination process.

[0086] The above-mentioned crude 1,3-butanediol stream after desalting is supplied to the high boiling point removal column C. In the high boiling point removal column C, high boiling point components (high boiling point substances) are discharged from below the charge layer (preferably from the bottom of the column). On the other hand, a crude 1,3-butanediol stream (1,3-butanediol with higher purity) after high boiling point substances are removed is obtained from above the charge layer.

[0087] As the high-boiling tower C, for example, a porous plate tower, a bubble tower, etc. can be used, but a packed tower with low pressure loss such as Sulzer Packings and Mellapak (both are trade names of Sumitomo Heavy Industries, Ltd.) is more preferably used. The reason is that 1,3-butanediol and the trace impurities contained therein are thermally decomposed at high temperatures (for example, above 150°C) to generate low-boiling substances as coloring components, thereby lowering the distillation temperature. In addition, the same influence is also produced when the thermal history (residence time) of 1,3-butanediol is long. Therefore, the reboiler used is preferably one with a shorter residence time of the process side fluid, for example, a thin film evaporator such as a natural falling film evaporator and a scraper stirred thin film evaporator is preferred.

[0088] The number of layers of the high boiling removal column C is, as the number of theoretical plates, for example, 1 to 100 layers, preferably 2 to 90 layers, more preferably 3 to 80 layers, further preferably 4 to 70 layers, 5 to 60 layers, 8 to 50 layers or 10 to 40 layers, and particularly preferably 15 to 30 layers. The supply position of the charge liquid is from the top of the high boiling removal column to the bottom, for example, at a position of 10% to 90% of the tower height, preferably 20% to 80%, more preferably 30 to 70 layers, and further preferably 40% to 60%. In the distillation of the high boiling removal column C, the pressure (absolute pressure) at the top of the column is, for example, 0.01 kPa to 50 kPa, preferably 0.1 kPa to 30 kPa, more preferably 0.3 kPa to 20 kPa, and further preferably 0.5 kPa to 10 kPa.

[0089] The concentration of 1,3BG in the charge liquid flowing to the high boiling tower C is, for example, 95% or more, preferably 96% or more, more preferably 97% or more, further preferably 98% or more, and particularly preferably 99% or more. In particular, in the production method 2 of the present disclosure, the concentration of 1,3BG in the charge liquid flowing to the high boiling tower C is preferably 97% or more, more preferably 98% or more, and further preferably 99% or more. The concentration of 1,3BG in the charge liquid flowing to the high boiling tower C can be increased by adjusting the distillation conditions of the dehydration tower A and the demineralization tower B. For example, the concentration of 1,3BG in the charge liquid flowing to the high boiling tower C can be increased by increasing the reflux ratio of the dehydration tower A or increasing the recovery rate of the demineralization tower B. It should be noted that the above-mentioned concentration of 1,3BG is the ratio (area %) of the peak area of ​​1,3BG relative to the total peak area in the gas chromatography analysis (GC analysis) under the following conditions.

[0090] (Conditions for gas chromatography analysis)

[0091] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0092] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0093] Sample introduction temperature: 250℃

[0094] Carrier gas: Helium

[0095] Column gas flow rate: 1mL / min

[0096] Detector and detection temperature: hydrogen flame ionization detector (FID), 280℃

[0097] The content of high boiling point components in the feed liquid flowing to the high boiling point removal column C is, for example, 4% or less, preferably 3% or less, more preferably 2% or less, further preferably 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. In particular, in the production method 2 of the present disclosure, the content of high boiling point components in the feed liquid flowing to the high boiling point removal column C is preferably 3% or less, more preferably 2% or less, further preferably 1.5% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.05% or less, and particularly preferably 0.01% or less. The content of high boiling point components in the feed liquid flowing to the high boiling point removal column C can be reduced by adjusting the distillation conditions of the demineralization column B. For example, by increasing the extraction rate of the demineralization tower B, the content of high boiling point components in the feed liquid flowing to the high boiling point removal tower C can be reduced. It should be noted that the content of high boiling point components in the feed liquid flowing to the above-mentioned high boiling point removal tower C is the total area ratio (area %) of the peak with a longer retention time than the peak of 1,3BG relative to the total peak area in the gas chromatography analysis under the above-mentioned conditions.

[0098] In the production method disclosed herein, the acetaldehyde content in the charge liquid flowing to the high-boiling tower C is, for example, 500 ppm or less, preferably 205 ppm or less (for example, 200 ppm or less), more preferably 100 ppm or less, further preferably 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less, particularly preferably 5 ppm or less, and may be less than 2 ppm or less than 1 ppm. The crotonaldehyde content in the charge liquid flowing to the high-boiling tower C is, for example, 200 ppm or less, preferably 110 ppm or less, more preferably 100 ppm or less, further preferably 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or 3 ppm or less, particularly preferably 2 ppm or less, and may be less than 1 ppm. The acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the high-boiling tower C can be reduced by, for example, setting a dealcoholization tower (low-boiling tower removal) and a dehydration tower upstream of the high-boiling tower C, and adjusting the distillation conditions of the dealcoholization tower (low-boiling tower removal) and the dehydration tower. For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization tower (low-boiling tower removal) and the dehydration tower, the acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the high-boiling tower C can be reduced. It should be noted that the acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the high-boiling tower C can be quantified by GC-MS analysis (gas chromatography-mass spectrometry analysis), as described below.

[0099] In the manufacturing method disclosed herein, the water content in the charge liquid flowing to the high boiling tower C is, for example, 1.2% by weight or less, preferably 1.1% by weight or less, more preferably 1.0% by weight or less, further preferably 0.95% by weight or less, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less or 0.2% by weight or less, particularly preferably 0.1% by weight or less. The water content in the charge liquid flowing to the high boiling tower C can be reduced by adjusting the distillation conditions of the dehydration tower A. For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dehydration tower A, the concentration of water in the charge liquid flowing to the high boiling tower C can be reduced. It should be noted that the water content in the charge liquid flowing to the high boiling tower C can be quantified by a Karl Fischer moisture meter.

[0100] In the production method disclosed herein, the content of low boiling point components (excluding water) in the feed liquid to the high boiling point removal column C is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, further preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of low boiling point components (also referred to as "low boiling point substances" or "low boiling substances") excluding water in the feed liquid to the high boiling point removal column C is the total area ratio (area %) of the peaks having a shorter retention time than the peak of 1,3-butanediol relative to the total peak area in the gas chromatography analysis under the above conditions. The content of low-boiling components (excluding water) in the feed liquid flowing to the high-boiling removal column C can be reduced by, for example, setting a dealcoholization column (low-boiling removal column) upstream of the high-boiling removal column C and adjusting the distillation conditions of the dealcoholization column (low-boiling removal column). For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization column (low-boiling removal column), the concentration of low-boiling components (excluding water) in the feed liquid flowing to the high-boiling removal column C can be reduced.

[0101] In the production method 1 of the present disclosure, the reflux ratio of the high boiling tower C [the reflux amount of the high boiling tower / the distillate amount of the high boiling tower (the amount discharged to the outside of the distillation tower)] is, for example, 0.02 or more. From the viewpoint of lowering the dry point of the 1,3-butanediol product, the reflux ratio is preferably 0.03 or more, more preferably 0.04 or more, further preferably 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 10 or more, and particularly preferably 20 or more. In particular, in the production method 2 of the present disclosure, the reflux ratio in the high boiling point removal column C exceeds 0.02, preferably 0.03 or more, more preferably 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, or 0.09 or more, further preferably 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 10 or more, and particularly preferably 20 or more. In addition, from the viewpoint of energy consumption, the upper limit of the reflux ratio is, for example, 100, preferably 50. When the theoretical plate number of the high boiling point removal column C is large, sufficient separation can be achieved even if the reflux ratio of the high boiling point removal column C is about 0.02.

[0102] In the production method of the present disclosure, by setting the reflux ratio in the high boiling point removal column C to the above-mentioned specific range, high-purity 1,3BG having a very small content of high boiling point components and a low dry point can be produced at a high recovery rate.

[0103] In the production method disclosed in the present invention, the recovery rate of the high-boiling tower C is, for example, less than 30% by weight. However, in the case where the extracted liquid of the high-boiling tower is further distilled by a distillation tower and the 1,3BG after high boiling is removed is commercialized, it is not limited to this. If the amount of the final high-boiling content extracted outside the system is suppressed to less than 30% by weight relative to the charge amount flowing to the high-boiling tower C, 1,3BG can be obtained at a high yield. It should be noted that the above-mentioned recovery rate refers to the ratio (weight %) of the amount of liquid extracted from the charging layer of the high-boiling tower C (for example, the bottom of the tower) relative to the charge amount flowing to the high-boiling tower C (including the recycled amount when the liquid is recycled to the previous process described below). It should be noted that when the liquid is recycled to the previous process described below, the smaller the discharge rate outside the system, the higher the recovery rate of 1,3BG can be.

[0104] From the viewpoint of improving the recovery rate of 1,3BG, the recovery rate of the high boiling tower C is preferably 25% by weight or less, more preferably 20% by weight or less, further preferably 15% by weight or less, 10% by weight or less, 7% by weight or less, 5% by weight or less, 4% by weight or less, 3% by weight or less, or 2% by weight or less, and may be 1% by weight or less. In addition, from the viewpoint of lowering the dry point of the 1,3-butanediol product, the recovery rate of the high boiling tower C is, for example, 0.01% by weight or more, preferably 0.1% by weight or more, 0.5% by weight or more, or 1% by weight or more, further preferably 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, 10% by weight or more, or 15% by weight or more, and particularly preferably 20% by weight or more.

[0105] At least a portion of the high boiling component concentrated liquid (hereinafter referred to as "produced liquid") extracted from below the charge layer of the high boiling component removal tower C can be recycled in a step before the high boiling component removal step. Figure 1 By recycling at least a portion of the produced liquid in a step before the high boiling removal step, the recovery rate of 1,3BG can be increased. It should be noted that in this specification, the recovery rate of 1,3BG in the high boiling removal tower C is a value (%) calculated by the following formula.

[0106] {1-[GC area % of 1,3BG in the produced liquid × (produced amount (parts) - recycled amount (parts))] / (GC area % of 1,3BG in the charged liquid × charged amount (parts))}×100

[0107] It should be noted that low-boiling point substances and high-boiling point substances may generate 1,3BG through hydrolysis with water, while high-boiling point substances may be generated through polymerization of 1,3BG. Furthermore, trace impurities may be generated and disappeared, so it is not always possible to obtain a material balance in the high-boiling point removal column.

[0108] The recovery rate of 1,3BG in the high boiling point removal column C is, for example, more than 80%, preferably 85% or more, more preferably 90% or more, further preferably 95% or more, particularly preferably 99% or more.

[0109] As the process before the above-mentioned high boiling point removal process, for example, there can be mentioned: acetaldehyde polymerization process (acetaldehyde aldol condensation process), reaction process (hydrogenation process), dealcoholization process (low boiling point removal process), dehydration process, desalination process, etc. Among these, since 1,3BG is generated by hydrolysis of high boiling point substances, it is preferably recycled in the acetaldehyde polymerization process (acetaldehyde aldol condensation process). In addition, there are cases where 1,3BG is generated by hydrogenation reduction. From this point of view, it can also be recycled in the hydrogenation process.

[0110] The recycling amount of the process before the high boiling removal process of the above-mentioned produced liquid can be appropriately selected within the range of the amount of produced liquid. Relative to the charge amount flowing to the high boiling removal tower C, the recycling amount of the process before the high boiling removal process of the above-mentioned produced liquid is, for example, less than 30% by weight, preferably less than 25% by weight. It should be noted that, relative to the charge amount flowing to the high boiling removal tower C, the above-mentioned recycling amount can also be less than 20% by weight, less than 15% by weight, less than 10% by weight, less than 7% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight or less than 1% by weight. In addition, from the viewpoint of improving the 1,3BG recovery rate of the high-boiling tower and the yield of the entire 1,3BG production process, the recycling amount of the above-mentioned produced liquid in the process before the high-boiling process is, for example, 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, or 10% by weight or more, and particularly preferably 20% by weight or more, relative to the charge amount flowing to the high-boiling tower C. It should be noted that when the produced amount reaches the limit, 1,3BG can be recovered at a high yield even without recycling in the previous process.

[0111] In the production method 2 of the present disclosure, the crude 1,3-butanediol stream taken out from above the charging layer of the high-boiling tower C can be directly used as a 1,3-butanediol product. In addition, the crude 1,3-butanediol stream taken out from above the charging layer of the high-boiling tower C is subjected to an alkali treatment using an alkali reactor D described below, and evaporated (or distilled) in a dealkalization tower E, and the top distillate of the dealkalization tower E can be used as a 1,3-butanediol product.

[0112] In the production method 2 disclosed in the present invention, by setting the acetaldehyde content and the crotonaldehyde content in the charge liquid flowing to the dehydration tower A to a specific range and setting the reflux ratio of the high-boiling tower C to a specific value or above, high-purity 1,3-butanediol with a high potassium permanganate test value, very small contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low drying point can be effectively produced industrially.

[0113] In the manufacturing method 1 disclosed in the present invention, the crude 1,3-butanediol stream taken out from the charging layer above the de-high-boiling tower C is supplied to, for example, an alkali reactor (e.g., a flow-through tubular reactor) D for alkali treatment. By alkali treatment, by-products contained in 1,3-butanediol can be decomposed. Alkali is added to the alkali reactor D or its upstream piping, etc. The amount of alkali added is, for example, 0.05% by weight to 10% by weight, preferably 0.1% by weight to 1.0% by weight, relative to the crude 1,3-butanediol stream subjected to alkali treatment. If the amount of alkali added exceeds 10% by weight, there will be a situation where the alkali precipitates in the distillation tower, piping, etc., which becomes a cause of blockage. In addition, sometimes the decomposition reaction of high-boiling point compounds also occurs, and there are cases where by-products are produced instead. When the amount of alkali added is less than 0.05% by weight, the effect of decomposing by-products is small.

[0114] The alkali added to the alkali reactor D or its upstream piping is not particularly limited, but alkali metal compounds are preferred, for example. As alkali metal compounds, for example, sodium hydroxide, potassium hydroxide, sodium (heavy) carbonate, potassium (heavy) carbonate can be listed. In addition, as the alkali, a basic ion exchange resin can be used. From the viewpoint of reducing the by-products contained in the final 1,3-butanediol product, sodium hydroxide and potassium hydroxide are preferred as the alkali. The alkali can be directly added to the solid substance, but for operation and to promote contact with the liquid to be treated, it is preferably added as an aqueous solution. It should be noted that the above-mentioned alkali can be used alone or in combination of two or more.

[0115] In the alkaline reactor D, the reaction temperature is not particularly limited, but is preferably 90°C to 140°C, more preferably 110°C to 130°C, for example. When the reaction temperature is less than 90°C, a long reaction residence time is required, so the reactor capacity becomes large and uneconomical. If the reaction temperature exceeds 140°C, the coloring of the final 1,3-butanediol product will increase. The reaction residence time is, for example, preferably 5 minutes to 120 minutes, more preferably 10 minutes to 30 minutes. When the reaction residence time is less than 5 minutes, the reaction becomes insufficient and the quality of the final 1,3-butanediol product deteriorates. If the reaction residence time exceeds 120 minutes, a large reactor is required and the equipment cost becomes high, so it is disadvantageous from an economic point of view.

[0116] After leaving the alkali reactor D, the crude reaction liquid flow is supplied to the dealkalization tower (e.g., thin film evaporator) E as needed, and the alkali and the like are removed from the bottom of the tower by evaporation. On the other hand, a dealkalized crude 1,3-butanediol flow (in the manufacturing method 2 disclosed in the present invention, a 1,3-butanediol product) is obtained from the top of the dealkalization tower E. For the purpose of suppressing the thermal history of the process fluid, the evaporator used for the dealkalization tower E is suitable for a natural falling film evaporator and a scraper-stirred thin film evaporator with a short residence time. It should be noted that a demister can be provided in the space above the loading position of the dealkalization tower (e.g., thin film evaporator) E to remove droplets of alkali and the like. By providing a demister, it is possible to prevent alkali and high-boiling substances from being mixed into the 1,3-butanediol product.

[0117] In the evaporator used for the dealkalization tower E, for example, evaporation is performed under reduced pressure at an absolute pressure of 20 kPa or less, preferably 0.5 kPa to 10 kPa at the top of the tower. The temperature of the evaporator is preferably 90° C. to 120° C. The crude 1,3-butanediol stream containing low boiling point substances distilled from the top of the tower is supplied to the product distillation tower (product tower) F. It should be noted that, as described above, in the production method 2 of the present disclosure, the distillate from the top of the dealkalization tower E (equivalent to E-1) can be used as a 1,3-butanediol product.

[0118] It should be noted that the alkali reactor D and the dealkalization tower E can be arranged between the desalination tower B and the high boiling tower C, between the dehydration tower A and the desalination tower B (in this case, the desalination tower can also serve as the dealkalization tower), or before the dehydration tower A. In addition, without setting the alkali reactor D and the dealkalization tower E, the alkali can be charged into the high boiling tower charging line or the dehydration tower charging line, or added to the reaction liquid after hydrogenation [thereafter, charged into the dealcoholization tower (low boiling tower)], and the alkali treatment can also be carried out.

[0119] In the production method 1 of the present disclosure, in the product column F used in the product distillation step, a 1,3-butanediol charge liquid having an acetaldehyde content of 500 ppm or less and a crotonaldehyde content of 200 ppm or less is distilled under a reflux ratio exceeding 0.1, and a liquid (equivalent to 1,3-butanediol) concentrated with low boiling point components is distilled from the upper portion of the charge layer. Figure 1 "X-6"), extract 1,3-butanediol (equivalent to Figure 1 The extracted 1,3-butanediol can be used as a 1,3-butanediol product.

[0120] As the product tower F, although a porous plate tower, a bubble tower, etc. can be used, a packed tower with low pressure loss such as Sulzer Packings and Mellapak (both are trade names of Sumitomo Heavy Industries, Ltd.) is more preferably used. The reason is that 1,3-butanediol and the trace impurities contained therein are thermally decomposed at high temperatures (for example, above 150°C) to generate low-boiling substances as coloring components, thereby lowering the distillation temperature. In addition, the same influence is also produced when the thermal history (residence time) of 1,3-butanediol is long. Therefore, the reboiler used is preferably one with a shorter residence time of the process side fluid, for example, a thin film evaporator such as a natural falling film evaporator and a scraper stirred thin film evaporator is preferred.

[0121] The number of theoretical plates of the product column F is, for example, 1 to 100, preferably 2 to 90, 3 to 80, 4 to 70, 5 to 60, 8 to 50 or 10 to 40, and more preferably 15 to 30. The feed liquid is supplied from the top of the column downward, for example, at a position of 10% to 90%, preferably 20% to 80%, more preferably 30% to 70%, and more preferably 40 to 60% of the column height. In the distillation in the product distillation column F, the pressure (absolute pressure) at the top of the column is, for example, 20 kPa or less, preferably 0.1 kPa to 10 kPa, more preferably 0.3 kPa to 8 kPa, and more preferably 0.5 kPa to 5 kPa.

[0122] exist Figure 1 In the process, the charge flowing to the product tower F will be fed with the liquid obtained by condensing the top vapor of the dealkalization tower E using the condenser E-1, or the top vapor from the dealkalization tower E can be directly fed to the product tower F.

[0123] The concentration of 1,3-butanediol in the feed liquid (1,3-butanediol feed liquid) flowing to the product column F is, for example, 90% or more, preferably 92% or more, more preferably 95% or more, further preferably 97% or more, 97.1% or more, 97.2% or more, 97.3% or more, 97.4% or more, 97.5% or more, 97.6% or more, 97.7% or more, 97.8% or more, 97.9% or more, 98% or more, 98.1% or more, 98.2% or more, 98.3% or more, 98.4% or more, 98.5% or more, 98.6% or more, 98.7% or more, 98.8% or more, or 98.9% or more, and particularly preferably 99% or more. If the number of theoretical plates, the reflux amount, and the reflux ratio of the product column F are sufficient, the product can be produced even if the concentration of 1,3-butanediol in the feed liquid flowing to the product column F is less than 90%.

[0124] The concentration of 1,3-butanediol in the feed liquid to the product tower F can be increased by, for example, adjusting the distillation conditions of the dehydration tower A, or setting a dealcoholization tower (low-boiling tower) before the dehydration tower A and adjusting its distillation conditions, or adjusting the distillation conditions of the high-boiling tower C. For example, the purity of 1,3-butanediol in the feed liquid to the product tower F can be increased by increasing the reflux ratio of the dealcoholization tower (low-boiling tower), the dehydration tower A and / or the high-boiling tower C, or increasing the number of layers.

[0125] The concentration of 1,3-butanediol in the feed liquid flowing into the product column F is the ratio (area %) of the peak area of ​​1,3-butanediol to the total peak area in gas chromatography analysis under the following conditions.

[0126] (Conditions for gas chromatography analysis)

[0127] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0128] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0129] Sample introduction temperature: 250℃

[0130] Carrier gas: Helium

[0131] Column gas flow rate: 1mL / min

[0132] Detector and detection temperature: hydrogen flame ionization detector (FID), 280℃

[0133] In the manufacturing method 1 of the present disclosure, the acetaldehyde content in the charge liquid flowing to the product tower F is set to 500ppm or less, and the crotonaldehyde content is set to 200ppm or less. The acetaldehyde content in the charge liquid flowing to the product tower F is preferably 205ppm or less (e.g., 200ppm or less), more preferably 150ppm or less, further preferably 120ppm or less, 100ppm or less, 90ppm or less, 80ppm or less, 70ppm or less, 60ppm or less, 50ppm or less, 40ppm or less, 30ppm or less, 20ppm or less, or 10ppm or less, particularly preferably 5ppm or less, and may be less than 2ppm. The crotonaldehyde content in the charge liquid flowing to the product tower F is preferably 150ppm or less, more preferably 130ppm or less, further preferably 110ppm or less, 100ppm or less, 80ppm or less, 70ppm or less, 60ppm or less, 50ppm or less, 40ppm or less, 30ppm or less, 20ppm or less, 10ppm or less, 5ppm or less or 3ppm or less, particularly preferably 2ppm or less, and may be less than 1ppm. The acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the product tower F can be reduced by, for example, setting a dealcoholization tower (removal of low boiling tower) and a dehydration tower upstream of the product tower F, and adjusting the distillation conditions of the dealcoholization tower (removal of low boiling tower) and the dehydration tower. For example, by increasing the reflux ratio, the number of layers and the distillation rate of the dealcoholization tower (removal of low boiling tower) and the dehydration tower, the acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the product tower F can be reduced. In addition, in the alkali reaction step, the acetaldehyde content and crotonaldehyde content in the feed liquid flowing to the product tower F can be reduced by increasing the reaction temperature, extending the residence time or increasing the amount of alkali added. It should be noted that the acetaldehyde content and crotonaldehyde content in the feed liquid flowing to the product tower F can be quantified by GC-MS analysis (gas chromatography mass spectrometry) as described below.

[0134] In the manufacturing method 1 of the present disclosure, the water content in the charge liquid flowing to the product tower F is, for example, 1.2% by weight or less, preferably 1.1% by weight or less, more preferably 1.0% by weight or less, further preferably 0.95% by weight or less, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.6% by weight or less, 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, or 0.2% by weight or less, and particularly preferably 0.1% by weight or less. The water content in the charge liquid flowing to the product tower F can be reduced by adjusting the distillation conditions of the dehydration tower A. For example, by increasing the reflux ratio, the number of layers, and the distillation rate of the dehydration tower A, the concentration of water in the charge liquid flowing to the product tower F can be reduced. It should be noted that the water content in the charge liquid flowing to the product tower F can be quantified by a Karl Fischer moisture meter.

[0135] The content of low boiling point components (excluding water) in the feed liquid flowing to the product column F is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, further preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of low boiling point components (also referred to as "low boiling substances") excluding water in the feed liquid flowing to the product column F is the total area ratio (area %) of the peaks having a shorter retention time than the peak of 1,3-butanediol relative to the total peak area in the gas chromatography analysis under the above conditions. The content of low boiling point components (excluding water) in the feed liquid flowing to the product column F can be reduced by, for example, setting a dealcoholization tower (removal of low boiling tower) upstream of the product column F and adjusting the distillation conditions of the dealcoholization tower (removal of low boiling tower). For example, by increasing the reflux ratio, number of layers and distillation rate of the dealcoholization tower (low-boiling removal tower), the concentration of low-boiling components (except water) in the feed liquid flowing to the product tower F can be reduced.

[0136] The content of high boiling point components (excluding water) in the feed liquid flowing to the product column F is, for example, 1.8% or less, preferably 1.6% or less, more preferably 1.4% or less, further preferably 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less. The content of high boiling point components (also referred to as "high boiling point substances" or "high boiling substances") excluding water in the feed liquid flowing to the product column F is the ratio (area %) of the total area of ​​the peak having a longer retention time than the peak of 1,3-butanediol relative to the total peak area in the gas chromatography analysis under the above conditions. The content of high boiling point components (excluding water) in the feed liquid flowing to the product column F can be reduced, for example, by adjusting the distillation conditions of the high boiling removal column. For example, by increasing the reflux ratio, the number of layers and the distillation rate of the high boiling point removal tower, the concentration of high boiling point components (except water) in the feed liquid flowing to the product tower F can be reduced.

[0137] In the production method 1 of the present disclosure, the reflux ratio [product column reflux amount / product column distillate amount (amount discharged to the outside of the distillation column)] in the product column F is set to a value greater than 0.1. From the viewpoint of increasing the initial distillation point of the 1,3-butanediol product, the reflux ratio is preferably 0.2 or more, more preferably 0.3 or more, further preferably 0.4 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 or more, or 50 or more, and particularly preferably 400 or more (for example, 500 or more). From the viewpoint of energy consumption, the upper limit of the reflux ratio of the product column F is, for example, 700 or 1000.

[0138] In the production method 1 of the present disclosure, from the viewpoint of improving the recovery rate of 1,3-butanediol, the distillation rate of the product column F is, for example, less than 30% by weight, preferably 29% by weight or less, more preferably 28% by weight or less, further preferably 27% by weight or less, 26% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, 21% by weight or less, 20% by weight or less, 19% by weight or less, 18% by weight or less, 17% by weight or less, 16% by weight or less, 15% by weight or less, 12% by weight or less, 10% by weight or less, 8% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, or 0.6% by weight or less, and particularly preferably 0.4% by weight or less. It should be noted that the above-mentioned distillation rate refers to the ratio (weight %) of the amount of liquid extracted from the upper portion of the charging layer of the product column F (for example, the top portion) to the outside of the distillation column (including the amount recycled in the case of recycling in the previous step described below) relative to the amount of liquid flowing into the product column F.

[0139] At least a portion of the liquid concentrated with low boiling components (hereinafter sometimes referred to as "distillate") extracted from the upper portion of the charging layer of the product column F can be recycled in a step before the product distillation step. Figure 1 By recycling at least a portion of the distillate in a step prior to the product distillation step, the recovery rate of 1,3-butanediol can be increased.

[0140] Examples of the process before the product distillation process include a dehydration process, a dealcoholization process (low boiling point removal process), etc. The dealcoholization process (low boiling point removal process) is preferably provided before the dehydration process.

[0141] The recycling amount of the distillate in the process before the product distillation process can be appropriately selected within the range of the amount of the distillate. The recycling amount of the distillate in the process before the product distillation process is, for example, less than 30% by weight relative to the charge amount flowing to the product column F. In addition, from the viewpoint of improving the 1,3BG recovery rate of the product column and the yield of the entire process, the recycling amount of the distillate in the process before the product distillation process is, for example, 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 1.5% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 7% by weight or more, or 10% by weight or more, and particularly preferably 20% by weight or more, relative to the charge amount flowing to the product column F.

[0142] In the production method 1 disclosed in the present invention, by setting the acetaldehyde content and crotonaldehyde content in the charge liquid flowing to the dehydration tower A to a specific range, setting the acetaldehyde and crotonaldehyde contents in the charge liquid flowing to the product tower F to below a specific value, and setting the reflux ratio of the product tower F to a specific range, high-purity 1,3-butanediol with a high potassium permanganate test value, very small contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low dry point can be produced at a usual high recovery rate.

[0143] The recovery rate of 1,3BG in the product tower F is, for example, more than 80%, preferably 85% or more, more preferably 90% or more, further preferably 95% or more, and particularly preferably 99% or more.

[0144] In addition, in this specification, the 1,3BG recovery rate in the product column F is a value (%) calculated|required by the following formula.

[0145] {1-[GC area % of 1,3BG in distillate × (distillate amount (parts) - recycled amount (parts))] / (GC area % of 1,3BG in charge liquid × charge amount (parts))}×100

[0146] As described above, low-boiling and high-boiling substances may generate 1,3BG by hydrolysis with water, while high-boiling substances may be generated by polymerization of 1,3BG. Therefore, the material balance in the product column cannot always be obtained.

[0147] [1,3-Butanediol products]

[0148] According to the method for producing 1,3-butanediol disclosed in the present invention, it is possible to obtain: a 1,3-butanediol product having an initial boiling point higher than 203°C and a potassium permanganate test value (PMT) of more than 30 minutes; a 1,3-butanediol product having an initial boiling point higher than 203°C and a dry point of less than 209°C; and further, a 1,3-butanediol product having an initial boiling point higher than 203°C, a dry point of less than 209°C, and a potassium permanganate test value (PMT) of more than 30 minutes. The initial boiling point is preferably higher than 204°C, more preferably higher than 205°C, further preferably higher than 206°C or 207°C, and particularly preferably higher than 208°C. The potassium permanganate test value (PMT) is more preferably more than 30 minutes (e.g., more than 32 minutes), further preferably more than 35 minutes (e.g., more than 40 minutes), and particularly preferably more than 50 minutes (especially more than 60 minutes).

[0149] Furthermore, according to the method for producing 1,3-butanediol of the present disclosure, in addition to the above characteristics, a 1,3-butanediol product having a peak area ratio of 1,3-butanediol higher than 98.7% in a gas chromatography analysis (GC analysis) under the following conditions can be obtained. Furthermore, according to the method for producing 1,3-butanediol of the present disclosure, in addition to the above characteristics, a 1,3-butanediol product having a total area ratio of peaks shorter than the retention time of the peak of 1,3-butanediol lower than 0.3% can be obtained. Furthermore, according to the method for producing 1,3-butanediol of the present disclosure, in addition to the above characteristics, a 1,3-butanediol product having a total area ratio of peaks longer than the retention time of the peak of 1,3-butanediol lower than 1.2% can be obtained.

[0150] (Conditions for gas chromatography analysis)

[0151] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0152] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0153] Sample introduction temperature: 250℃

[0154] Carrier gas: Helium

[0155] Column gas flow rate: 1mL / min

[0156] Detector and detection temperature: hydrogen flame ionization detector (FID), 280℃

[0157] The peak area ratio of the 1,3-butanediol is preferably 98.8% or more, more preferably 98.9% or more, further preferably 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, or 99.7% or more, particularly preferably 99.8% or more.

[0158] The total area ratio of peaks having a shorter retention time than the peak of 1,3-butanediol is preferably 0.28% or less, more preferably 0.25% or less, further preferably 0.23% or less, 0.2% or less, 0.17% or less, 0.15% or less, 0.12% or less, 0.1% or less, 0.07% or less, 0.04% or less, 0.03% or less, 0.02% or less, 0.01% or less, or 0.007% or less, and particularly preferably 0.005% or less (e.g., 0.002% or less).

[0159] The total area ratio of peaks having a longer retention time than the peak of 1,3-butanediol is preferably 1% or less, more preferably 0.9% or less, further preferably 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less, and particularly preferably 0.1% or less.

[0160] It should be noted that, in the present disclosure, the "area ratio" of a peak means the ratio (area %) of the area of ​​a specific peak to the sum of the areas of all peaks appearing in the spectrum. In addition, all peaks refer to, for example, all peaks that appear when the relative retention time of the peak of 1,3-butanediol is set to 1.0 and the analysis is continued until the relative retention time is 7.8 and then stopped.

[0161] According to the method for producing 1,3-butanediol disclosed in the present invention, a 1,3-butanediol product having a water content of less than 0.4% by weight can be obtained. The water content is preferably 0.3% by weight or less, more preferably 0.2% by weight or less, further preferably 0.1% by weight or less, 0.07% by weight or less, 0.05% by weight or less, 0.03% by weight or less, 0.02% by weight or less, or 0.01% by weight or less, and particularly preferably 0.005% by weight or less. It should be noted that the water content can be quantified by a Karl Fischer moisture analyzer.

[0162] In addition, according to the 1,3-butanediol production method disclosed in the present invention, a 1,3-butanediol product having an acetaldehyde content of less than 2ppm can be obtained. In addition, according to the 1,3-butanediol production method disclosed in the present invention, a 1,3-butanediol product having a crotonaldehyde content of less than 1.2ppm can be obtained. The acetaldehyde content and crotonaldehyde content in the 1,3-butanediol product can be quantified by GC-MS analysis (gas chromatography mass spectrometry), such as GC-MS analysis under the following conditions. In GC-MS analysis, even for very small peaks, a full mass analysis is performed to quantify each component. In order to analyze a specific mass, even if other impurities overlap with the peak, substances with different masses will not be detected, and the sensitivity is higher than that of the GC analysis. In this specification, the unit "ppm" of the content of each component analyzed by GC-MS refers to "ppm by weight".

[0163] (Conditions for GC-MS analysis)

[0164] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0165] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0166] Sample introduction temperature: 250℃

[0167] Carrier gas: Helium

[0168] Column gas flow rate: 1mL / min

[0169] Ion source temperature: EI 230℃, CI 250℃

[0170] Quadrupole temperature: 150°C

[0171] Sample: Directly used for analysis

[0172] In the above GC-MS analysis conditions, when the relative retention time of the peak of 1,3-butanediol is 1.0, the relative retention time of the peak of acetaldehyde is 0.3 to 0.5, and the relative retention time of the peak of crotonaldehyde is 0.3 to 0.5.

[0173] The acetaldehyde content in the 1,3-butanediol product obtained by the production method of the present disclosure is more preferably 1.8 ppm or less, further preferably 1.7 ppm or less, 1.5 ppm or less, 1.4 ppm or less, 1.3 ppm or less, 1.2 ppm or less, 1.1 ppm or less, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, or 0.5 ppm or less, and particularly preferably 0.3 ppm or less (e.g. 0.2 ppm or less). In addition, the crotonaldehyde content in the 1,3-butanediol product obtained by the production method of the present disclosure is more preferably 1.0 ppm or less, further preferably 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.4 ppm or less, or 0.3 ppm or less, and particularly preferably 0.2 ppm or less (e.g. 0.1 ppm or less).

[0174] Therefore, through the 1,3-butanediol production method disclosed in the present invention, a high-quality 1,3-butanediol product with excellent initial distillation point and dry point, a large potassium permanganate test value, a high peak area ratio of 1,3-butanediol, a low total area ratio of peaks with a retention time shorter than that of the peak of 1,3-butanediol, a low total area ratio of peaks with a retention time longer than that of the peak of 1,3-butanediol, a low acetaldehyde content, a low crotonaldehyde content, and high purity can be obtained.

[0175] [Moisturizers and cosmetics]

[0176] Therefore, the 1,3-butanediol product obtained by the manufacturing method disclosed in the present invention is suitable for use as a raw material for a moisturizer or a cosmetic. The moisturizer may also contain components other than the above-mentioned 1,3-butanediol product, for example, moisturizer components other than the above-mentioned 1,3-butanediol product. In such moisturizers, the content of the above-mentioned 1,3-butanediol product is, for example, 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, further preferably 80% by weight or more, particularly preferably 90% by weight or more, or may be composed only of the above-mentioned 1,3-butanediol product.

[0177] According to the type and form of the cosmetic, the amount of the 1,3-butylene glycol product in the cosmetic can be an amount that can exert moisturizing properties. The amount of the 1,3-butylene glycol product in such cosmetics is, for example, 0.01% to 40% by weight, preferably 0.1% to 30% by weight, more preferably 0.2% to 20% by weight, further preferably 0.5% to 15% by weight, and particularly preferably 1% to 10% by weight.

[0178] In addition to the above-mentioned 1,3-butylene glycol products, the cosmetics may also include, for example: other moisturizers; oils such as vegetable oils, hydrocarbon oils, higher fatty acids, higher alcohols, silicones, etc.; surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc.; preservatives, chelating agents, thickeners, powders, ultraviolet absorbers, ultraviolet shielding agents, fragrances, pH adjusters; vitamins, skin activators, blood circulation promoters, whitening agents, antibacterial agents, anti-inflammatory agents, etc., and pharmacological components and physiologically active components, etc.

[0179] The cosmetic material can be made into skin cosmetics such as lotion, emulsion, cream, gel, mask cream, and mask; hair cosmetics such as shampoo, conditioner, and hair growth agent. In addition, there can also be sunscreen cosmetics and color cosmetics. In addition, it can also be made into medicines and skin care products formulated with medical components. The cosmetic material can be manufactured by using its own known method.

[0180] It should be noted that the various schemes disclosed in this specification can be combined with any other features disclosed in this specification. In addition, each configuration and combination of configurations in each embodiment is an example, and appropriate addition, omission and other changes of configurations can be made within the scope of the main purpose of the present disclosure. The present disclosure is not limited by the embodiments, but only by the claims.

[0181] Example

[0182] The present disclosure is described in more detail below by way of examples, but the present disclosure is not limited by these examples. It should be noted that the "parts" used in the examples refer to "parts by weight" unless otherwise specified. Gas chromatography analysis (GC analysis), initial boiling point determination, and water content measurement were performed by the methods described below.

[0183] [Example 1]

[0184] use Figure 1 The method for producing 1,3-butanediol will be described.

[0185] With respect to 100 parts of a butanol aldehyde solution containing 30 wt% of water as a raw material (comprising a mixed solution of 69 parts of butanol aldehyde and 29 parts of water, 2 parts in total of low-boiling and high-boiling impurities, and less than 0.1 parts of Na salt), 10 parts of hydrogen gas are charged into a reactor for liquid-phase hydrogen reduction, 15 parts of Raney nickel as a catalyst are added, and the reactor is maintained at 120° C. and 10 MPa (gauge pressure) to perform liquid-phase hydrogen reduction. After the catalyst is separated from the liquid after the reaction, it is neutralized with caustic soda to obtain crude 1,3-butanediol (1) containing low-boiling impurities and water.

[0186] The butanol aldehyde solution containing 30 wt % of water used as a raw material was produced by stirring acetaldehyde and water in the presence of 100 wt ppm of NaOH at 30° C. for a residence time of 10 hours to dimerize acetaldehyde [acetaldehyde polymerization step (acetaldehyde aldol condensation step)].

[0187] The crude 1,3-butanediol (1) (equivalent to Figure 1 "X-1" in the dehydration tower A. The concentration of 1,3-butanediol in the feed liquid flowing to the dehydration tower A is 56% by weight, the concentration of water is 40% by weight, the content of acetaldehyde (AD) is 130ppm, the content of crotonaldehyde (CR) is 89ppm, and in the GC analysis described below, the total area ratio of the impurity peaks with a shorter retention time (retention time; RT) than that of 1,3-butanediol is 3%, and the total area ratio of the impurity peaks with a longer retention time than that of 1,3-butanediol is 1%. In the dehydration tower A, distillation is carried out under the conditions of a top pressure of 10 kPa (absolute pressure) and a reflux ratio of 0.05, and water is extracted from the top of the tower. Relative to 100 parts of the feed liquid, 43 parts (distillate) are removed and discharged to the outside of the system (equivalent to Figure 1 From the bottom of the column, crude 1,3-butanediol (2) having a 1,3-butanediol concentration of 96.9 GC area %, water of 0.9 wt %, a total area ratio of impurity peaks having a shorter retention time than 1,3-butanediol of 0.8%, a total area ratio of impurity peaks having a longer retention time than 1,3-butanediol of 2.3%, an acetaldehyde content of 18 ppm, and a crotonaldehyde content of 17 ppm was obtained.

[0188] Next, the crude 1,3-butanediol (2) is fed into a demineralization tower B. In the demineralization tower B, salts, high boiling point substances, and a portion of 1,3-butanediol are discharged from the bottom of the tower as an evaporation residue (equivalent to Figure 1 ) The discharge amount of the evaporation residue was 5 parts per 100 parts of the loading liquid. On the other hand, crude 1,3-butanediol (3) containing 1,3-butanediol, low boiling point substances, and a part of high boiling point substances was obtained from the top of the column.

[0189] Next, the crude 1,3-butanediol (3) was charged into the high boiling removal column C. In the high boiling removal column C, distillation was performed under the conditions of a column top pressure of 5 kPa (absolute pressure) and a reflux ratio of 0.05, and high boiling point substances and a portion of 1,3-butanediol (equivalent to Figure 1 The amount of the column bottom discharge was 20 parts relative to 100 parts of the loading liquid. On the other hand, 80 parts of crude 1,3-butanediol (4) containing low boiling point substances was obtained as a distillate from the top of the column.

[0190] Next, crude 1,3-butanediol (4) was charged into the alkali reactor D. At this time, a 20 wt % caustic soda aqueous solution was added so that the concentration of caustic soda relative to the charge liquid was 0.1 wt %. The reaction temperature of the alkali reactor D was maintained at 120° C., and the reaction was carried out with a residence time of 20 minutes.

[0191] Next, the crude reaction liquid discharged from the alkali reactor D is fed into the dealkalization tower E. In the dealkalization tower E, caustic soda, high boiling point substances, and a portion of 1,3-butanediol (equivalent to Figure 1 "X-5" in the column). The amount discharged from the bottom of the column was 10 parts relative to 100 parts of the loading liquid. On the other hand, 90 parts of crude 1,3-butanediol (5) containing 1,3-butanediol and low-boiling substances were obtained from the top of the column. The crude 1,3-butanediol (5) containing 1,3-butanediol and low-boiling substances was subjected to moisture measurement, GC analysis and GC-MS analysis. The results were: the moisture concentration was 1.1% by weight, the area ratio of 1,3-butanediol was 99%, the total area ratio of impurity peaks with a shorter retention time than 1,3-butanediol was 0.4%, the total area ratio of impurity peaks with a longer retention time than 1,3-butanediol was 0.6%, the acetaldehyde content was 21 ppm, and the crotonaldehyde content was 10 ppm.

[0192] Next, the crude 1,3-butanediol (5) was charged into the product column F. In the product column F, 10 parts of low boiling point substances and a part of 1,3-butanediol (equivalent to 100 parts of the charged liquid) were distilled from the top of the column. Figure 1 At this time, the tower was operated at a reflux ratio of 0.5 (reflux volume / distillate volume), and 90 parts of 1,3-butanediol products (distillate volume was 10 parts) were obtained from the bottom of the tower (equivalent to Figure 1 in the text box).

[0193] The obtained 1,3-butanediol product was subjected to initial distillation point determination, moisture determination, GC analysis and GC-MS analysis. The results were as follows: initial distillation point was 203.3°C, dry point was 209°C, moisture concentration was 0.2% by weight, area ratio of 1,3-butanediol was 99.2%, total area ratio of impurity peaks with shorter retention time than 1,3-butanediol was 0.08%, total area ratio of impurity peaks with longer retention time than 1,3-butanediol was 0.7%, acetaldehyde content was 1.6ppm, crotonaldehyde content was 1.0ppm. In addition, the potassium permanganate test value was 35 minutes. The 1,3-butanediol recovery rate of product tower F was 90%.

[0194] [Example 2]

[0195] The same operation as in Example 1 was performed except that the reflux ratio of the dehydration tower A was changed to 10. The 1,3-butanediol product was obtained from the bottom of the product tower F. It should be noted that due to the change in the conditions of the dehydration tower A, the composition of the dehydration tower extraction changed, and the charging liquid groups of the high boiling tower C and the product tower F changed, respectively, resulting in a change in the quality of the product.

[0196] The obtained 1,3-butanediol product was subjected to initial distillation point determination, moisture determination, GC analysis and GC-MS analysis. The results were as follows: initial distillation point was 206.5°C, dry point was 208.9°C, moisture concentration was 0.1% by weight, area ratio of 1,3-butanediol was 99.2%, total area ratio of impurity peaks with shorter retention time than 1,3-butanediol was 0.06%, total area ratio of impurity peaks with longer retention time than 1,3-butanediol was 0.7%, acetaldehyde content was 0.8ppm, crotonaldehyde content was 0.8ppm. In addition, the potassium permanganate test value was 45 minutes. The 1,3-butanediol recovery rate of product tower F was 90%.

[0197] [Examples 3 to 28]

[0198] The dehydration tower A, the high boiling tower C and the product tower F were operated under the conditions shown in Tables 1 to 3. It should be noted that in Examples 4 to 22 and 24 to 26, all the distillate from the product tower F was recycled in the hydrogen reduction reactor. In Examples 23 and 28, the product tower F was not used, and the top distillate from the dealkalization tower E (a demister was provided in the space above the loading position) was used as the 1,3-butanediol product. At this time, the concentration of the caustic soda aqueous solution in the alkali reactor D was set to 1.5 times, and the amount of the caustic soda aqueous solution added was set to half of that in Example 1, so as to avoid the increase of water content caused by the alkali treatment as much as possible. It should be noted that if the alkali concentration of the caustic soda aqueous solution is too high, crystals will precipitate, so it is preferably heated to 40°C or above. In Table 3, the composition and physical properties of the top distillate from the dealkalization tower E are recorded in the "Product Tower F Extraction" column of Examples 23 and 28. It should be noted that in Example 16, 10 parts of the high-boiling tower produced liquid were recycled in the hydrogenation process, and 2 parts were discharged outside the system. In addition, in Example 25, the pressure of the hydrogenation reaction dropped to 7MPaG (gauge pressure). Therefore, the acetaldehyde content and crotonaldehyde content in the dehydration tower charging liquid are relatively high. In Example 26, the pressure of the hydrogenation reaction rose to 40MPaG (gauge pressure) (the remaining conditions are the same as in Example 18).

[0199] [Comparative Example 1]

[0200] 80 parts of 1,3-butanediol products were obtained from the bottom of product tower F by the same method as in Example 1, except that the reflux ratio of dehydration tower A was changed to 0.03, the distillate amount was changed to 42 parts, the reflux ratio of dehydration tower C was changed to 0.02, the reflux ratio of product tower F was changed to 0.05, and the distillate amount was changed to 20 parts. The initial boiling point of the obtained 1,3-butanediol product was 193.1°C, the dry point was 210.2°C, the water concentration was 0.6% by weight, the area ratio of 1,3-butanediol was 98.2%, the total area ratio of impurity peaks with shorter retention time than 1,3-butanediol was 0.3%, the total area ratio of impurity peaks with longer retention time than 1,3-butanediol was 1.5%, the acetaldehyde content was 5ppm, and the crotonaldehyde content was 4ppm. In addition, the potassium permanganate test value was 0 minutes. The 1,3-butanediol recovery rate of product tower F was 81%.

[0201] [Comparative Example 2]

[0202] 80 parts of 1,3-butanediol products were obtained from the bottom of product tower F by the same method as in Example 1, except that the charge composition of dehydration tower A was changed, the reflux ratio was changed to 0.03, the distillate amount was changed to 32 parts, the reflux ratio of dehydration tower C was changed to 0.02, the reflux ratio of product tower F was changed to 0.05, and the distillate amount was changed to 20 parts. The initial boiling point of the obtained 1,3-butanediol product was 198.9°C, the dry point was 210.1°C, the water concentration was 0.4% by weight, the area ratio of 1,3-butanediol was 98.5%, the total area ratio of impurity peaks with shorter retention time than 1,3-butanediol was 0.1%, the total area ratio of impurity peaks with longer retention time than 1,3-butanediol was 1.4%, the acetaldehyde content was 4ppm, and the crotonaldehyde content was 2ppm. In addition, the potassium permanganate test value was 5 minutes. The recovery rate of 1,3-butanediol in product tower F was 80%.

[0203] [Comparative Example 3]

[0204] 70 parts of 1,3-butanediol products were obtained from the bottom of product tower F by the same method as in Example 1, except that the charge composition of dehydration tower A was changed, the reflux ratio was changed to 0.03, the distillate amount was changed to 32 parts, the reflux ratio of dehydration tower C was changed to 0.02, the reflux ratio of product tower F was changed to 0.05, and the distillate amount was changed to 30 parts. The initial boiling point of the obtained 1,3-butanediol product was 203.0°C, the dry point was 210.2°C, the water concentration was 0.2% by weight, the area ratio of 1,3-butanediol was 98.4%, the total area ratio of impurity peaks with shorter retention time than 1,3-butanediol was 0.1%, the total area ratio of impurity peaks with longer retention time than 1,3-butanediol was 1.5%, the acetaldehyde content was 2ppm, and the crotonaldehyde content was 1.3ppm. In addition, the potassium permanganate test value was 30 minutes. The 1,3-butanediol recovery rate of the product tower F is 70%.

[0205] [Comparative Example 4]

[0206] 80 parts of 1,3-butanediol product were obtained from the bottom of product tower F by the same method as in Example 1 except that the charge composition of dehydration tower A was changed, the reflux ratio was changed to 0.03, the distillate amount was changed to 23 parts, the reflux ratio of high boiling tower C was changed to 0.02, and the reflux ratio of product tower F was changed to 0.1, and the distillate amount was changed to 20 parts. The obtained 1,3-butanediol product had an initial boiling point of 203.1°C, a dry point of 209.5°C, a water concentration of 0.2 wt%, an area ratio of 1,3-butanediol of 98.8%, a total area ratio of impurity peaks with a shorter retention time than 1,3-butanediol of 0.1%, a total area ratio of impurity peaks with a longer retention time than 1,3-butanediol of 1.1%, an acetaldehyde content of 2 ppm, and a crotonaldehyde content of 1.4 ppm. In addition, the potassium permanganate test value was 30 minutes. The 1,3-butanediol recovery rate of the product tower F was 80%.

[0207] [Gas chromatography analysis]

[0208] The gas chromatography analysis of the 1,3-butanediol product was performed under the following conditions.

[0209] (Conditions for gas chromatography analysis)

[0210] Analytical device: Shimadzu GC2010

[0211] Analytical column: a column with a stationary phase of polydimethylsiloxane (film thickness 1.0 μm×length 30 m×inner diameter 0.25 mm) (“Agilent J&W GC column-DB-1”, manufactured by Agilent Technologies Japan, Ltd.)

[0212] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0213] Sample introduction and temperature: Split sample introduction method, 250°C

[0214] Slit gas flow and carrier gas: 23mL / min, helium

[0215] Column gas flow and carrier gas: 1 mL / min, helium

[0216] Detector and temperature: Flame ionization detector (FID), 280°C

[0217] Injection sample: 0.2 μL of 80 wt% 1,3-butanediol aqueous solution

[0218] [Determination of initial boiling point and dry point]

[0219] The measurement was carried out according to the test method specified in the atmospheric distillation test method of JIS K2254 "Petroleum products - Distillation test methods".

[0220] [Water content measurement]

[0221] The content was measured using a Karl Fischer moisture analyzer.

[0222] [GC-MS analysis]

[0223] Analytical device: Agilent 6890A-GC / 5973A-MSD

[0224] Analytical column: Column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)

[0225] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0226] Sample introduction temperature: 250℃

[0227] Carrier gas: Helium.

[0228] Column gas flow rate: 1mL / min

[0229] Ion source temperature: EI 230℃, CI 250℃

[0230] Quadrupole temperature: 150°C

[0231] Sample: Directly used for analysis

[0232] [Potassium permanganate test]

[0233] In this specification, the potassium permanganate test value (PMT) is a value measured by a sequential method based on the visual colorimetric method of JIS K1351 (1993).

[0234] [Research Results]

[0235] The results of the comparative examples and examples are shown in Tables 1 to 3.

[0236]

[0237]

[0238]

[0239]

[0240] [Table 3]

[0241]

[0242]

[0243] From Comparative Examples 1 to 4, it can be seen that when the reflux ratio and distillation volume of each distillation tower are low, even if the dehydration tower charge composition is changed, the product quality is not good. In Comparative Examples 3 and 4, by increasing the discharge volume of the product tower outside the distillation system or reducing the moisture content of the dehydration tower charge, the initial distillation point and PMT are sufficient, but the dry point is high. In addition, the recovery rate of 1,3BG is also low, which is not economical. It should be noted that the separation of acetaldehyde and crotonaldehyde in the dehydration tower is more difficult than usual, and there is a possibility that acetaldehyde and crotonaldehyde are generated in the tower.

[0244] It can be seen from Comparative Example 1 and Examples 1 and 27 that if the dehydration tower charge composition is set to the same, and among the dehydration tower, the high boiling point removal tower and the product tower, at least the reflux ratio of the product tower is set to be above a specific value, then the initial distillation point, PMT and dry point are satisfied at the same time, and the 1,3BG recovery factors of the dehydration tower, the high boiling point removal tower and the product tower can also be maintained at a higher value at an allowable level.

[0245] It can be seen from Examples 1 and 2 that when the reflux ratio of the dehydration tower is increased to a certain value or above, the contents of water, acetaldehyde and crotonaldehyde are reduced, and in particular the initial distillation point and PMT are increased.

[0246] As shown in Examples 2 and 3, if the reflux ratio of the product tower is increased to a certain value or more and the distillate volume is reduced, the increase in low-boiling impurities due to the reduction in the distillate volume is offset by the increase in the separation of low-boiling impurities due to the increase in the reflux ratio, and the product quality does not change, and the 1,3BG recovery rate of the product tower can be improved.

[0247] It can be seen from Comparative Example 2 and Example 4, and Comparative Example 4 and Example 11 that the quality is improved by setting the dehydration tower charge composition to be the same and setting the distillation conditions of the dehydration tower, the high boiling tower, and the product tower to be within the range specified in the present disclosure.

[0248] It can be seen from Examples 4 and 5 that the initial distillation point and PMT can be further improved by further increasing the reflux ratio of the dehydration tower.

[0249] It can be seen from Examples 5 and 6 that if the reflux ratio of the dehydration tower is increased and the distillation rate of the product tower is reduced, although the initial distillation point is reduced, it is within the specified range and the 1,3BG recovery rate is increased.

[0250] It can be seen from Examples 6 to 8 that if the reflux ratio of the product column is extremely increased, the initial distillation point and PMT are increased to the limit. However, if the reflux ratio is reduced to about 500, the quality approaches the limit.

[0251] As can be seen from Examples 6, 9, and 10, the initial boiling point and PMT increase as the reflux ratio of the dehydration tower increases. However, when an alkaline aqueous solution is used for treatment between the dehydration tower and the product tower, the water content increases in this process, so the extreme water removal in the dehydration tower becomes not very meaningful, so the reflux ratio of the dehydration tower does not need to be too high. However, since the alkali reactor can be changed to the upstream of the dehydration tower, in this case, it is effective even if the reflux ratio of the dehydration tower is increased to a certain extent.

[0252] In Examples 11 to 13, the reflux ratio of the dehydration tower was increased under the condition of reducing the water concentration in the dehydration tower feed liquid, and the reflux and distillation amount of the product tower were changed. As mentioned above, the respective effects and influences are the result of satisfying the initial distillation point and PMT.

[0253] It can be seen from Examples 14 to 21 that if the reflux ratio of the high-boiling tower is increased, the high-boiling impurity content in the product is reduced and the dry point is increased. In addition, Example 16 is a condition in which 8 out of 10 parts of the high-boiling tower produced liquid are recycled in the hydrogenation process and 2 parts are discharged outside the system, thereby lowering the boiling point of the impurities through hydrogenation. Based on this, although the 1,3BG recovery rate of the high-boiling tower is improved, the high-boiling substances in some products increase and the dry point rises. However, it can be seen that it meets the regulations.

[0254] It can be seen from Examples 1 and 22 that even if the reflux ratio of the dehydration tower is 0.05, high quality of the product can be maintained as long as the reflux ratio of the product tower is increased.

[0255] From Comparative Example 4, Examples 13, 23, and 28, it can be seen that if the reflux ratio of the dehydration tower is greatly increased, even without a product tower, the acetaldehyde, crotonaldehyde, and water contents can be reduced and the product can be produced. It should be noted that the water concentration in the product can be further reduced by performing an alkali treatment before distillation in the dehydration tower.

[0256] Example 24 is an example in which the water concentration in the dehydration tower feed liquid reached the limit. Although the water content in the dehydration tower output liquid and the high boiling tower feed liquid increased significantly, the product quality was maintained by adjusting the distillation rate and reflux ratio of the product tower.

[0257] It can be seen from Examples 4 and 25 that even if the acetaldehyde and crotonaldehyde contents in the dehydration tower feed liquid are very high, the product can maintain high quality by increasing the distillation volume and reflux ratio of the product tower to remove acetaldehyde and crotonaldehyde.

[0258] It can be seen from Example 26 that if the pressure of the hydrogenation reaction is increased, acetaldehyde, crotonaldehyde and other reducing substances are rendered harmless by hydrogenation, and the concentrations of acetaldehyde, crotonaldehyde, other reducing substances, and trace amounts of other impurities such as acetals in the dehydration tower charge liquid are reduced, the product quality can be maintained even if the reflux ratio and distillation volume of the dehydration tower, high boiling tower and product tower are relatively small.

[0259] It should be noted that among the 1,3-butanediol products obtained by the existing methods, there is no high-quality product with an initial distillation point higher than 203°C and a potassium permanganate test value of more than 30 minutes, or an initial distillation point higher than 203°C and a dry point of less than 209°C, or an initial distillation point higher than 203°C, a dry point of less than 209°C and a potassium permanganate test value of more than 30 minutes.

[0260] As a summary of the above, the configuration and changes of the present disclosure are supplementally described below.

[0261] [1] A method for producing 1,3-butanediol by obtaining purified 1,3-butanediol from a crude reaction liquid containing 1,3-butanediol, comprising:

[0262] A dehydration step of removing water by distillation; a high boiling point removal step of removing high boiling point components by distillation; and a product distillation step for obtaining purified 1,3-butanediol,

[0263] In the dehydration tower used in the dehydration step, 1,3-butanediol and water are distilled, and the acetaldehyde content is 1000 ppm or less (or 900 ppm or less, 800 ppm or less, 700 ppm or less, 600 ppm or less, 500 ppm or less, 400 ppm or less, 300 ppm or less, 200 ppm or less, 155 ppm or less, 140 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less) , 5 ppm or less, 3 ppm or less, 2 ppm or less or 1 ppm or less) and a charging liquid having a crotonaldehyde content of 400 ppm or less (or 200 ppm or less, 150 ppm or less, 130 ppm or less, 117 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less or 1 ppm or less), and distilling a low-boiling-point component concentrate containing water from above the charging layer,

[0264] In the product tower used in the product distillation step, the acetaldehyde content is 500ppm or less (or, 205ppm or less, 200ppm or less, 150ppm or less, 120ppm or less, 100ppm or less, 90ppm or less, 80ppm or less, 70ppm or less, 60ppm or less, 50ppm or less, 40ppm or less, 30ppm or less, 20ppm or less, 10ppm or less, 5ppm or less or less than 2ppm), and the crotonaldehyde content is 200ppm or less (or, 205ppm or less, 200ppm or less, 150ppm or less, 120ppm or less, 100ppm or less, 90ppm or less, 80ppm or less, 70ppm or less, 60ppm or less, 50ppm or less, 40ppm or less, 30ppm or less, 20ppm or less, 10ppm or less, 5ppm or less or less than 2ppm). m or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or less than 2 ppm), and distilling a 1,3-butanediol charge liquid having a reflux ratio exceeding 0.1 (or 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 50 or more, 400 or more, or 500 or more), distilling a low-boiling point component concentrate from above the charge layer, and extracting 1,3-butanediol from below the charge layer.

[0265] [2] The method for producing 1,3-butanediol according to [1], wherein in the high boiling point removal tower used in the high boiling point removal step, a charge liquid containing 1,3-butanediol is distilled at a reflux ratio of 0.02 or more (or 0.03 or more, 0.04 or more, 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, or 20 or more), 1,3-butanediol of higher purity is distilled from above the charge layer, and a high boiling point component concentrate is extracted from below the charge layer.

[0266] [3] The method for producing 1,3-butanediol according to [1] or [2], wherein the concentration of 1,3-butanediol in the feed liquid flowing into the product column is 90 GC area % or more (or, 92 GC area % or more, 95 GC area % or more, more preferably 97 GC area % or more, 97.1 GC area % or more, 97.2 GC area % or more, 97.3 GC area % or more, 97.4 GC area % or more, 97.5 GC area % or more, 97.6 GC area % or more, 97.7 GC area % or more, 97.8 GC area % or more, 97.9 GC area % or more, 98 GC area % or more, 98.1 GC area % or more, 98.2 GC area % or more % by weight or more, 98.3 GC area % or more, 98.4 GC area % or more, 98.5 GC area % or more, 98.6 GC area % or more, 98.7 GC area % or more, 98.8 GC area % or more, 98.9 GC area % or more or 99 GC area % or more), and the water content in the charging liquid is 3 wt % or less (or, 1.2 wt % or less, 1.1 wt % or less, 1.0 wt % or less, 0.95 wt % or less, 0.9 wt % or less, 0.8 wt % or less, 0.7 wt % or less, 0.6 wt % or less, 0.5 wt % or less, 0.4 wt % or less, 0.3 wt % or less, 0.2 wt % or less or 0.1 wt %).

[0267] [4] The method for producing 1,3-butanediol according to any one of [1] to [3], wherein the content of low-boiling point components other than water in the feed liquid flowing into the product tower is 1.8 GC area % or less (or, 1.6 GC area % or less, 1.4 GC area % or less, 1.2 GC area % or less, 1.1 GC area % or less, 1 GC area % or less, 0.9 GC area % or less, 0.8 GC area % or less, 0.7 GC area % or less, 0.6 GC area % or less, 0.5 GC area % or less, 0.4 GC area % or less, 0.3 GC area % or less, 0.2 GC area % or less, or 0.1 GC area % or less).

[0268] [5] According to any one of [1] to [4], the acetaldehyde content in the charge liquid flowing into the product tower is 205 ppm or less (or, 200 ppm or less, 150 ppm or less, 120 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, or less than 2 ppm), and the crotonaldehyde content in the charge liquid is 110 ppm or less (or, 100 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less, or less than 1 ppm).

[0269] [6] The method for producing 1,3-butanediol according to any one of [1] to [5], wherein the product column has 1 to 100 theoretical plates.

[0270] [7] The method for producing 1,3-butanediol according to any one of [1] to [6], wherein at least a portion of the distillate from the product column is recycled in a step prior to the product distillation step, i.e., a dehydration step, a dealcoholization step, a low boiling point removal step, or a step prior to these steps.

[0271] [8] A method for producing 1,3-butanediol by obtaining purified 1,3-butanediol from a crude reaction liquid containing 1,3-butanediol, comprising:

[0272] A dehydration step of removing water by distillation; and a high boiling point removal step of removing high boiling point components by distillation,

[0273] In the dehydration tower used in the dehydration step, 1,3-butanediol and water are distilled, and the acetaldehyde content is 1000 ppm or less (or 900 ppm or less, 800 ppm or less, 700 ppm or less, 600 ppm or less, 500 ppm or less, 400 ppm or less, 300 ppm or less, 200 ppm or less, 155 ppm or less, 140 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less) , 5 ppm or less, 3 ppm or less, 2 ppm or less or 1 ppm or less) and a charging liquid having a crotonaldehyde content of 400 ppm or less (or 200 ppm or less, 150 ppm or less, 130 ppm or less, 117 ppm or less, 100 ppm or less, 90 ppm or less, 80 ppm or less, 70 ppm or less, 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, 2 ppm or less or 1 ppm or less), and distilling a low-boiling-point component concentrate containing water from above the charging layer,

[0274] In the high boiling point removal tower used in the high boiling point removal step, a charge liquid containing 1,3-butanediol is distilled under the condition of a reflux ratio exceeding 0.02 (or, 0.1 or more, more preferably 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more or 20 or more), 1,3-butanediol of higher purity is distilled from above the charge layer, and a high boiling point component concentrate is extracted from below the charge layer.

[0275] [9] The method for producing 1,3-butanediol according to any one of [1] to [8], wherein the reflux ratio of the dehydration tower is 0.03 or more (or 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.2 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.28 or more, 0.3 or more, 0.33 or more, 0.36 or more, 0.4 or more). above, 0.45 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more or 40 or more).

[0276]

[10] The method for producing 1,3-butanediol according to any one of [1] to [9], wherein the crude reaction liquid containing the 1,3-butanediol is a crude reaction liquid obtained by hydrogen reduction of butanol aldehydes.

[0277]

[11] The method for producing 1,3-butanediol according to any one of [1] to

[10] , further comprising an alkali treatment step of treating a process stream containing 1,3-butanediol with an alkali.

[0278]

[12] The method for producing 1,3-butanediol according to any one of [1] to

[11] , further comprising a desalting step of removing salt from a process stream containing 1,3-butanediol.

[0279]

[13] The method for producing 1,3-butanediol according to any one of [1] to

[12] , further comprising a dealcoholization step of removing low boiling points including alcohol in a process stream containing 1,3-butanediol.

[0280]

[14] The method for producing 1,3-butanediol according to any one of [1] to

[13] , wherein the water content in the feed liquid flowing into the dehydration tower is 90% by weight or less (or, 85% by weight or less, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, or 25% by weight or less).

[0281]

[15] The method for producing 1,3-butanediol according to any one of [1] to

[14] , wherein the number of theoretical plates of one or more distillation towers among the dehydration tower and the high boiling point removal tower is 1 to 100.

[0282]

[16] The method for producing 1,3-butanediol according to any one of [1] to

[15] , wherein the concentration of 1,3-butanediol in the feed liquid flowing into the high boiling point removal tower is 95% or more (or 96% or more, 97% or more, 98% or more, or 99% or more).

[0283]

[17] According to any one of [1] to

[16] , the content of high boiling point components in the charge liquid flowing to the high boiling removal tower is 4% or less (or, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less or 0.01% or less).

[0284]

[18] A 1,3-butanediol product having an initial boiling point of greater than 203°C (or greater than 204°C, greater than 205°C, greater than 206°C, greater than 207°C or greater than 208°C) and a potassium permanganate test value of greater than 30 minutes (or greater than 30 minutes, greater than 32 minutes, greater than 35 minutes, greater than 40 minutes, greater than 50 minutes or greater than 60 minutes).

[0285]

[19] A 1,3-butanediol product having an initial distillation point higher than 203°C (or higher than 204°C, higher than 205°C, higher than 206°C, higher than 207°C or higher than 208°C) and a dry point lower than 209°C.

[0286]

[20] A 1,3-butanediol product having an initial boiling point of higher than 203°C (or higher than 204°C, higher than 205°C, higher than 206°C, higher than 207°C or higher than 208°C), a dry point of lower than 209°C, and a potassium permanganate test value of 30 minutes or more (or more than 30 minutes, 32 minutes or more, 35 minutes or more, 40 minutes or more, 50 minutes or more, or 60 minutes or more).

[0287]

[21] The 1,3-butanediol product according to any one of

[18] to

[20] , which satisfies (a) the peak area ratio of 1,3-butanediol is higher than 98.7% (or 98.8% or higher, 98.9% or higher, 99% or higher, 99.1% or higher, 99.2% or higher, 99.3% or higher, 99.4% or higher, 99.5% or higher, 99.6% or higher, 99.7% or higher, or 99.8% or higher) in a gas chromatography analysis under the following conditions; and (b) the total area ratio of peaks having a shorter retention time than that of the peak of 1,3-butanediol is lower than 0.3% (or 0.28% or lower, 0. (c) in a gas chromatography analysis under the following conditions, the total area ratio of the peak having a retention time longer than that of the peak of 1,3-butanediol is less than 1.2% (or less than 1%, less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.4%, less than 0.5%, less than 0.6%, less than 0.7%, less than 0.8 ... (d) the water content is less than 0.4 wt% (or, 0.3 wt% or less, 0.2 wt% or less, 0.1 wt% or less, 0.07 wt% or less, 0.05 wt% or less, 0.03 wt% or less, 0.02 wt% or less, 0.01 wt% or less, or 0.005 wt% or less), (e) the acetaldehyde content is less than 2 ppm (or, 1.8 ppm or less, 1.7 ppm or less, 1.5 ppm or less, 1.4 ppm or less, 1.3 ppm or less, 1.2 ppm or less, 1.1 ppm or less, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.3 ppm or less or 0.2 ppm or less), (f) at least one selected from the following six conditions (preferably two or more, more preferably three or more, further preferably four or more, particularly preferably five or more, and especially all of the conditions) of crotonaldehyde content less than 1.2 ppm (or, 1.0 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.4 ppm or less, 0.3 ppm or less, 0.2 ppm or less).

[0288] (Conditions for gas chromatography analysis)

[0289] Analytical column: a column with polydimethylsiloxane as the stationary phase (film thickness 1.0 μm×length 30 m×inner diameter 0.25 mm).

[0290] Heating conditions: After heating from 80°C to 120°C at 5°C / min, heating to 160°C at 2°C / min and maintaining for 2 minutes, heating to 230°C at 10°C / min and maintaining at 230°C for 18 minutes.

[0291] Sample introduction temperature: 250°C.

[0292] Carrier gas: Helium.

[0293] Column gas flow rate: 1 mL / min.

[0294] Detector and detection temperature: hydrogen flame ionization detector (FID), 280°C.

[0295]

[22] A moisturizer comprising the 1,3-butanediol product according to any one of

[18] to

[21] .

[0296]

[23] According to the moisturizing agent described in

[22] , the content of the 1,3-butanediol product described in any one of

[18] to

[21] is 10 weight% or more (or 30 weight% or more, 50 weight% or more, 80 weight% or more, or 90 weight% or more).

[0297]

[24] A cosmetic comprising the moisturizing agent described in

[22] or

[23] .

[0298]

[25] According to the cosmetic described in

[24] , the content of the 1,3-butanediol product described in any one of

[18] to

[21] is 0.01% by weight to 40% by weight (or 0.1% by weight to 30% by weight, 0.2% by weight to 20% by weight, 0.5% by weight to 15% by weight or 1% by weight to 10% by weight).

[0299]

[26] The cosmetic according to

[24] or

[25] , which is a skin cosmetic, a hair cosmetic, a sunscreen cosmetic, or a makeup cosmetic.

[0300] Industrial Applicability

[0301] According to the production method disclosed in the present invention, high-purity 1,3-butanediol having very low contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low dry point can be produced industrially and efficiently; high-purity 1,3-butanediol having very low contents of low-boiling point components, a high initial distillation point and a high potassium permanganate test value can be produced industrially and efficiently; further, high-purity 1,3-butanediol having a high potassium permanganate test value, very low contents of low-boiling point components and high-boiling point components, a high initial distillation point and a low dry point can be produced industrially and efficiently.

[0302] Description of Reference Numerals

[0303] A: Dehydration tower

[0304] B: Desalination tower

[0305] C: High boiling point removal distillation tower (high boiling point removal tower)

[0306] D: Alkali Reactor

[0307] E: Dealkalization Tower

[0308] F: Product distillation tower (product tower)

[0309] A-1, B-1, C-1, E-1, F-1: Condenser

[0310] A-2, C-2, F-2: Reboiler

[0311] X-1: Crude 1,3-butanediol

[0312] X-2: Water (drainage)

[0313] X-3: Salt, high boiling point substances and part of 1,3-butanediol

[0314] X-4: high boiling point substances and part of 1,3-butanediol

[0315] X-5: caustic soda, high boiling point substances and part of 1,3-butanediol

[0316] X-6: Low boiling point substances and part of 1,3-butanediol

[0317] Y: 1,3-Butanediol products

Claims

1. A method for producing 1,3-butanediol by obtaining purified 1,3-butanediol from a crude reaction solution containing 1,3-butanediol, the method comprising: A dehydration step of removing water by distillation; a high boiling point removal step of removing high boiling point components by distillation; and a product distillation step for obtaining purified 1,3-butanediol, In the dehydration tower used in the dehydration step, a charge liquid containing 1,3-butanediol and water and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling-point component concentrate containing water is distilled from above the charge layer. In the product tower used in the product distillation step, a 1,3-butanediol charge liquid having an acetaldehyde content of less than 500 ppm and a crotonaldehyde content of less than 200 ppm is distilled under a reflux ratio exceeding 0.1, a low-boiling point component concentrate is distilled from above the charge layer, and 1,3-butanediol is extracted from below the charge layer.

2. The method for producing 1,3-butanediol according to claim 1, wherein in the high boiling point removal tower used in the high boiling point removal step, the charge liquid containing 1,3-butanediol is distilled at a reflux ratio of 0.02 or more, 1,3-butanediol with higher purity is distilled from the upper portion of the charge layer, and a high boiling point component concentrate is extracted from the lower portion of the charge layer. 3 . The method for producing 1,3-butanediol according to claim 1 , wherein the concentration of 1,3-butanediol in the feed liquid flowing to the product column is 90 GC area % or more, and the water content in the feed liquid is 3 wt % or less.

4. A method for producing 1,3-butanediol by obtaining purified 1,3-butanediol from a crude reaction solution containing 1,3-butanediol, the method comprising: A dehydration step of removing water by distillation; and a high boiling point removal step of removing high boiling point components by distillation, In the dehydration tower used in the dehydration step, a charge liquid containing 1,3-butanediol and water and having an acetaldehyde content of 1000 ppm or less and a crotonaldehyde content of 400 ppm or less is distilled, and a low-boiling-point component concentrate containing water is distilled from above the charge layer. In the high boiling point removal tower used in the high boiling point removal step, the charge liquid containing 1,3-butanediol is distilled at a reflux ratio exceeding 0.02, 1,3-butanediol with higher purity is distilled from the upper portion of the charge layer, and a high boiling point component concentrate is extracted from the lower portion of the charge layer. 5 . The method for producing 1,3-butanediol according to claim 1 , wherein the reflux ratio of the dehydration tower is 0.03 or more. 6 . The method for producing 1,3-butanediol according to claim 1 , wherein the crude reaction liquid containing the 1,3-butanediol is a crude reaction liquid obtained by hydrogen reduction of butanol aldehydes. 7 . The method for producing 1,3-butanediol according to claim 1 , further comprising an alkali treatment step of treating a process stream containing 1,3-butanediol with an alkali. 8 . The method for producing 1,3-butanediol according to claim 1 , further comprising a desalting step of removing salt from a process stream containing 1,3-butanediol. 9 . The method for producing 1,3-butanediol according to claim 1 , further comprising a dealcoholization step of removing low boiling points including alcohol in a process stream including 1,3-butanediol.

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