METHOD FOR MANUFACTURING 1,3-BUTYLENE GLYCOL

Abstract

Provided is a method capable of manufacturing high-purity 1,3-butylene glycol having a high potassium permanganate test value, a very low content of low boiling point components, and a high initial boiling point with a high recovery rate. A method for manufa.cturing 1,3-butylene glycol is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol. In a dehydration column used in the dehydration step, a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate; and in a product column used in the product distillation step, a 1,3-butylene glycol liquid feed having an acetaldehyde content of 500 ppm or lower and a crotonaldehyde content of 200 ppm or lower is distilled under a condition of a reflux ratio of higher than 0.1.

Description

TECHNICAL FIELD

The present disclosure relates to a method for manufacturing 1,3-butylene glycol. The present patent application claims priority from the Japanese Patent Application No. 2019-239974, Japanese Patent Application No. 2019-239975, Japanese Patent Application No. 2019.-239976, Japanese Patent Application No. 2019-239977, Japanese Patent Application No. 2019-239978 and Japanese Patent Application No. 2019-239979, all filed in Japan on Dec. 28, 2019, the Japanese Patent Application No. 2020-006660 filed in Japan on Jan. 20, 2020, and the Japanese Patent Application No. 2020-018910 filed in Japan on Feb. 6, 2020, the entire contents of which are incorporated herein by reference.

BACKGROUND ART

1,3-Butylene glycol is a colorless, transparent, and odorless liquid and has properties, such as low volatility, low toxicity, and high hygroscopicity, and has excellent chemical stability. 1,3-butylene glycol has a wide range of applications, including raw materials for various synthetic resins and surfactants, as well as materials for cosmetics, hygroscopic agents, high boiling point solvents, and antifreezes, etc. Particularly in recent years, 1,3-butylene glycol has been attracting attention for having excellent properties as a. moisturizer, and demand is growing in the cosmetic industry.

A crude reaction liquid during manufacture of 1,3-butylene glycol contains a number of low boiling point impurities such as ethanol, butanol, acetaldehyde, crotonaldehyde, and esters. Among such impurities, acetaldehyde, crotonaldehyde, and the like cause high boiling point impurities to be produced when dimerized or polymerized. In addition, even in purification process of 1,3-butylene glycol, low boiling point impurities and high boiling point impurities are produced due to heat or the like. The few such impurities in 1,3-butylene glycol products, the more desirable. Patent Document 1 discloses a method of controlling an impurity derived from crotonaldehyde, which is a low boiling point impurity. Patent Document 2 discloses that a high-purity 1,3-butylene glycol product can be produced in good yield and economically advantageously when a crude reaction liquid for 1,3-butylene glycol synthesized by hydrogenation of acetaldols is made basic, alcohol is distilled off, and then distillation is performed. Furthermore, Patent Document 2 discloses distilling off ethanol, isopropyl alcohol, and butanol, which are low boiling point impurities, by distillation.

CITATION LIST

Patent Document

Patent Document 1: JP 06-329664 A

Patent Document 2: JP 2001-213828 A

SUMMARY OF INVENTION

Technical Problem

However, with the known methods, low boiling point components and high boiling point components are not sufficiently removed from 1,3-butylene glycol. Cosmetics, which are an important application of 1,3-butylene glycol, typically contain water and require a long period of time from manufacture to actual use by general consumers. In addition, from the viewpoint, such as storage stability of cosmetics, liquidity is strictly controlled.

When 1,3-butylene glycol containing low boiling point components and high boiling point components is used in cosmetics, an acid concentration increase can disrupt the liquidity balance of the cosmetics, and this can lead to a loss of the intended effect. In addition, the acid concentration increase of cosmetics can cause rough skin or the like of the users.

Further, during use and/or storage after use of a cosmetic, the cosmetic is exposed to air. In addition, in manufacturing cosmetics, the manufacturing work is usually performed in air atmosphere, and the product may be heated for the purposes of, for example, sterilization. When 1,3-butylene glycol containing low boiling point components and high boiling point components is used in cosmetics, coloration progresses in the presence of air or by influence of heating in some cases.

To solve such problems, removing by-products from crude 1,3-butylene glycol to obtain high-purity 1,3-butylene glycol has been required.

Meanwhile, one of quality standards for 1,3-butylene glycol includes initial boiling point. The higher the initial boiling point is, the better the quality. However, almost no technical studies for the purpose of improving the initial boiling point have been conducted so far. Also, one of quality standards for 1,3-butylene glycol includes dry point. The lower the dry point is, the better the quality. When the high boiling point impurities produced in the reaction and purification processes are mixed into products, not only their purity is reduced, but also the dry point is raised, resulting in issues that the products will not meet the product quality standards. However, not many studies on methods for separating and removing high boiling point impurities have been done. Furthermore, a potassium permanganate test value (abbreviated as PMT) is one of the product standards for 1,3-butylene glycol. However, the potassium permanganate test value of the resulting 1,3-butylene glycol product obtained through known methods is not always fully satisfactory. Also, the substance that caused to reduce the potassium permanganate test value of 1,3-butylene glycol products has not been identified. That is, there has been no industrially efficient method for manufacturing a 1,3-butylene glycol product excellent in two characteristics of initial boiling point and dry point, two characteristics of initial boiling point and potassium permanganate test value, and further three characteristics of initial boiling point, dry point, and potassium permanganate test value.

Therefore, an object of the present disclosure is to provide a method capable of industrially efficiently manufacturing high-purity 1,3-butylene glycol having a very low content of low boiling point components and high boiling point components, a high initial boiling point and a low dry point.

Another object of the present disclosure is to provide a method capable of industrially efficiently manufacturing high-purity 1,3-butylene glycol having a very low content of low boiling point components, a high initial boiling point, and, besides, a high potassium permanganate test value.

Another object of the present disclosure is to provide a method capable of industrially efficiently manufacturing high-purity 1,3-butylene glycol having a high potassium permanganate test value, and a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point.

Solution to Problem

As a result of diligent research to achieve the purposes, the inventors of the present disclosure have found that, by specifying an acetaldehyde content and a crotonaldehyde content in a liquid feed into a dehydration column, and distilling a liquid feed having not higher than predetermined content of acetaldehyde and crotonaldehyde in a predetermined reflux ratio in a product column, high-purity 1,3-butylene glycol having a very low content of low boiling point components and high boiling point components is obtained from below a feed plate. Also, the inventors have found that, by specifying a content acetaldehyde and crotonaldehyde in a liquid feed into a dehydration column, and distilling a liquid feed containing 1,3-butylene glycol in a predetermined reflux ratio in a high boiling substance removal column, high-purity 1,3-butylene glycol having a very low content of low boiling point components and high boiling point components is obtained from above a feed plate. The present disclosure has been completed by conducting further studies based on these findings.

Specifically, the present disclosure provides a method for manufacturing 1,3-butylene glycol, which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol, the method including:

a dehydration step of removing water by distillation; a high boiling substance removal step of removing a high boiling point component by distillation; and a product distillation step of obtaining purified 1,3-butylene glycol,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the product distillation step, a product column is used in which a 1,3-butylene glycol liquid feed having an acetaldehyde content of 500 ppm or lower and a crotonaldehyde content of 200 ppm or lower is distilled under a condition of a reflux ratio of higher than 0.1, a liquid concentrated with a low boiling point component is distilled off from above a feed plate, and 1,3 -butylene glycol is extracted from below the feed plate (hereinafter sometimes referred to as “manufacturing method 1 of the present disclosure”).

It is preferable that, in the manufacturing method, in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of 0.02 or higher, 1,3-butylene glycol having further improved purity is distilled off frond above a feed plate, and a liquid concentrated with a high boiling point component is extracted from below the feed plate,

It is preferable that a concentration of 1,3-butylene glycol in the liquid feed into the product column is 90 GC area % or higher, and that a content of water in the liquid feed is 3 wt. % or lower.

The present disclosure also provides a method for manufacturing 1,3 butylene glycol_; which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol, the method including:

a dehydration step of removing water by distillation; and a high boiling substance removal step of removing a high boiling point component by distillation,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of higher than 0.02, higher-purity^, 1,3-butylene glycol is distilled off from above a feed plate, and a liquid concentrated with a high boiling point component is extracted from below the feed plate (hereinafter sometimes referred to as “manufacturing method 2 of the present disclosure”).

In each of the manufacturing methods, a reflux ratio in the dehydration column is preferably 0.03 or higher.

Also, the crude reaction liquid containing 1,3-butylene glycol may be a crude reaction liquid obtained by hydrogen reduction of an acetaldol.

Each of the manufacturing methods may further include at least one step of: an alkaline treatment step of treating a process stream containing 1,3-butylene glycol with a base, a desalting step of removing a salt in the process stream containing 1,3-butyl ene glycol, or a dealcoholization step of removing a low boiling substance containing alcohols in the process stream containing 1,3 -butylene glycol.

In the present disclosure, “1,3-butylene glycol product” means a composition in which 1,3-butylene glycol occupies a majority of the components (e.g., a 1,3-butylene glycol content is 95 wt. % or higher, preferably 98 wt. % or higher).

Advantageous Effects of Invention

The manufacturing method of the present disclosure can be used to industrially efficiently manufacture high-purity 1,3-butylene glycol having a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point, high-purity 1,3-butylene glycol having a very low content of low boiling point components, a high initial boiling point, a high potassium permanganate test value, and further high-purity 1,3-butylene glycol having a high potassium permanganate test value, a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart showing a manufacturing method (purification method) for 1,3-butylene glycol of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Method for manufacturing 1,3-butylene glycol

A manufacturing method 1 according to the present disclosure is a. method for manufacturing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a crude reaction liquid containing 1,3-butylene glycol (1,3 BG) (hereinafter sometimes referred to as “crude 1,3-butylene glycol”), the method including: a dehydration step of removing water by distillation, a high boiling substance removal step of removing a high boiling point component by distillation, and a product distillation step of obtaining purified 1,3-butylene glycol. In a dehydration column for use in the dehydration step, a liquid feed containing 1,3-butylene glycol and water with a content of acetaldehyde (AD) of 1000 ppm or lower and a content of crotonaldehyde (CR) of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a. feed plate. In the product distillation step, a product column is used in which a 1,3-butylene glycol liquid feed having an acetaldehyde content of 500 ppm or lower and a crotonaldehyde content of 200 ppm or lower is distilled under a condition of a reflux ratio of higher than 0.1, a liquid concentrated with a low boiling point component is distilled off from above a feed plate, and 1,3-butylene glycol is extracted from below the feed plate. The thus obtained 1,3-butylene glycol can be made into a 1,3-butylene glycol product since it has a high potassium permanganate test value, a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point.

The manufacturing method 2 of the present disclosure is a method for manufacturing 1,3-butylene glycol, in which purified 1,3-butylene glycol is obtained from a crude reaction liquid containing 1,3-butylene glycol (crude 1,3-butylene glycol), the method including: a dehydration step of removing water by distillation and a high boiling substance removal step of removing a high boiling point component by distillation. In a dehydration column for use in the dehydration step, a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate. In a high boiling substance removal column for use in the high boiling substance removal step, a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of higher than 0.02, higher-purity 1,3-butylene glycol is distilled off from above a feed plate, and a liquid concentrated with the high boiling point component is extracted from below the feed plate. Since the thus obtained 1,3-butylene glycol has a very low content of low boiling point components and high boiling point components, it can be subjected to alkaline treatment as necessary, and thus made into a 1,3-butylene glycol product.

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

The “GC area %” refers to a ratio of a peak area of a subject component relative to a total peak area in gas chromatographic analysis which will be described below.

Crude 1,3-butylene glycol

Examples of the crude 1,3-butylene glycol include: (1) a crude reaction liquid obtained by reduction (hydrogenation) of acetaldols; (2) a crude reaction liquid obtained by hydrolyzation 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 to butadiene; (5) a crude reaction liquid obtained by hydrogen addition to n-butanal-3-one; (6) a crude reaction liquid obtained by hydrogen addition to 1-butanol-3-one; (7) a crude reaction liquid obtained by hydrogen addition to 3-hydroxy-1-butanoic acid; (8) a crude reaction liquid obtained by hydrogen addition to β-butyrolactone; and (9) a crude reaction liquid obtained by hydrogen addition to diketene. in the present disclosure, the crude 1,3-butylene glycol may be one, or a mixture of two or more, of the above (1) to (9). The crude 1,3-butylene glycol is preferably (1) the crude reaction liquid obtained by reduction (in particular, liquid phase reduction) of acetaldols.

Hereinafter, a case where the crude reaction liquid obtained by reduction (hydrogenation) of acetaldols is used as the crude 1,3-butylene glycol will be mainly described. Note that the reduction (hydrogenation) step of acetaldols is sometimes referred to as “hydrogenation step”.

The acetaldols used as a raw material in the hydrogenation step are not particularly limited, as long as they are a compound that yields 1,3-butylene glycol by hydrogen reduction. Examples of the raw material acetaldols include acetaldol; its cyclic dimer paraldol; aldoxane as a cyclic trimer of acetaldehyde; and mixtures of these.

The method of manufacturing the acetaldols (e.g., acetaldol or paraldol) is not particularly limited, but the acetaldol may be, for example, those obtained by an aldol condensation reaction of acetaldehyde in the presence of a basic catalyst or those obtained by pyrolysis or the like of aldoxane. Note that the manufacturing process of the acetaldols is sometimes referred to as “acetaldol manufacture” or “acetaldehyde polymerization”.

A crude reaction liquid obtained by the reaction described above and containing acetaldols may be neutralized with an acid and used in the manufacturing of 1,3-butylene glycol. Such a crude reaction liquid may contain, in addition to acetaldols, acetaldehyde (AD), crotonaldehyde (CR), another aldehyde component; a low boiling point substance; a high boiling point substance, such as an aldehyde dimer or trimer; water; a salt; and the like. In the present specification, a compound having a lower boiling point than 1,3-butylene glycol may be referred to as a “low boiling point substance” or “low boiling substance”, and a compound having a higher boiling point than 1,3-butylene glycol may be referred to as a “high boiling point substance” or “high boiling substance”.

The crude reaction liquid containing acetaldols may be subjected to a pretreatment, such as dealcoholization distillation, dehydration distillation, desalting, alkaline treatment and deal treatment, or impurity removal, as necessary, and a product obtained by removing by-products, such as unreacted acetaldehyde and crotonaldehyde, may be used. Examples of the pretreatment method include distillation, adsorption, ion exchange, conversion to a high boiling point substance by heating, and decomposition. For the distillation, a distillation method of various types, such as reduced pressure, normal pressure, increased pressure, azeotropic, extraction, or reaction, can be used. In particular, it is preferred that the crude reaction liquid containing acetaldols is subjected to simple evaporation, distillation, or hydrogen addition to remove aldehydes such as acetaldehyde and crotonaldehyde, followed by the hydrogenation step.

The content of the acetaidois in the raw material for hydrogenation is not particularly limited but is, for example, preferably 30 wt. % or higher (e.g., from 30 to 99 wt. %), more preferably 40 wt. % or higher (for example, from 40 to 98 wt. %), 50 wt. % or higher (for example, from 50 to 97 wt. %) or 60 wt. % or higher (for example, from 60 to 95 wt. %), and even more preferably from 65 to 90 wt. %, particularly preferably from 70 to 90 wt. %, and most preferably from 75 to 90 wt. %. With the content of the acetaldol within the above ranges, impurities contained in the crude reaction liquid containing 1,3-butylene glycol (crude 1,3-butylene glycol) tend to be reduced.

The raw material for hydrogenation may or may not contain water but preferably contains water from the viewpoint of the purity of 1,3-butylene glycol product. The water content in the raw material for hydrogenation is not particularly limited but is, for example_; preferably 2 wt. % or higher, more preferably 5 wt. % or higher, even more preferably 10 wt. % or higher, and particularly preferably 15 wt. % or higher. The upper limit may be, for example, 90 wt. %, 80 wt. %, 70 wt. %, 60 wt. %, 50 wt. %, 40 wt. %, 30 wt. % or 20 wt. %. With the water content within the above ranges, the acetal of 1,3-butylene glycol and acetaldol contained in the resulting crude 1,3-butylene glycol is decreased, and thus this tends to increase the purity of the 1,3-butylene glycol product finally obtained. This is because the raw material for hydrogenation contains water to a certain extent, and the acetal is hydrolyzed into 1,3-butylene glycol accordingly as well as coexisting acetaldol is reduced into 1,3-butylene glycol.

Examples of the hydrogenation catalyst include Raney nickel. The hydrogenation catalyst can be used in a suspended state, or can also be charged into a reaction vessel and used. The amount of the hydrogenation catalyst to be used is not particularly limited but is, for example, preferably from 1 to 30 parts by weight, more preferably from 4 to 25 parts by weight, even more preferably from 8 to 20 parts by weight, and particularly preferably from 12 to 18 parts by weight relative to 100 parts by weight of the raw material for hydrogenation. The amount of hydrogen to be used in the reduction reaction is not particularly limited but is, for example, preferably from 0.5 to 40 parts by weight, more preferably from 1 to 30 parts by weight, even more preferably from 4 to 20 parts by weight, and particularly preferably from 8 to 12 parts by weight relative to 100 parts by weight of the raw material for hydrogenation. A pressure (total pressure gauge pressure) in a reaction system in the reduction reaction is not particularly limited, but is, for example, preferably from 9 to 70 MPa and more preferably from 10 to 40 MPa. A hydrogen pressure (partial pressure of hydrogen) in the reaction system is not particularly limited, but is, for example, from 7 to 60 MPa, and preferably from 10 to 30 MPa. Note that, from the perspective of reducing the reducing materials such as acetaldehyde and crotonaldehyde, it is better to increase the hydrogen pressure in the reaction system, and the hydrogen pressure is preferably 10 MPa or higher, and may be 100 MPa. The higher hydrogen pressure in the reaction system makes acetaldehyde, crotonaldehyde, and other reducing substances essentially harmless, and the concentration of acetaldehyde, crotonaldehyde, and other reducing substances, as well as other impurities such as trace acetals in the liquid feed into the dehydration column, which will be described later, can also be reduced. Thus, the product quality can be advantageously maintained even when the reflux ratios and distilled amounts of the dehydration column, high boiling substance removal column, and product column in the 1,3-butylene glycol purification step are relatively small.

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

For example, the thus-obtained crude 1,3-butylene glycol contains acetaldehyde (AD); butylaldehyde; crotonaldehyde (CR); acetone; a low boiling point substance (low boiling point compound) having an unsaturated bond, such as methyl vinyl ketone; a condensate of these; a condensate of 1,3-butylene glycol and the above low boiling point substance (e.g., an acetal of 1,3-butylene glycol and acetaldol); an alcohol such as ethanol, isopropyl alcohol, or butanol; water (for example, solvent), a salt produced by neutralization or the like, a catalyst (when used in suspension) or the like. By removing these impurities in the purification step, a 1,3-butylene glycol product (purified 1,3-butylene glycol) can he obtained.

Purification of crude 1,3-butylene glycol

The manufacturing method 1 according to the present disclosure includes, at least, a dehydration step of removing water by distillation, a high boiling substance removal step of removing a high boiling point component by distillation (high boiling substance removal distillation step), and a product distillation step of obtaining purified 1,3-butylene glycol. In the manufacturing method 2 of the present disclosure includes, at least a dehydration step of removing water by distillation and a high boiling substance removal step of removing a high boiling point component by distillation (high boiling point substance removal distillation step).

In the manufacturing method of the present disclosure, the order of the dehydration step and the high boiling substance removal step does not matter.

In the manufacturing method 1 of the present disclosure, both the dehydration step and the high boiling substance removal step are provided prior to the product distillation step. The manufacturing method according to the present disclosure may include, in addition to these steps, a desalting step, an alkaline reaction step (alkaline treatment step), and a dealkalization step. Additionally, prior to the dehydration step, a catalyst separation step, a neutralization step by alkali, a dealcoholization step (low boiling substance removal step), and the like can be provided. These steps may be performed in the order described above, but the order of these steps may he changed as appropriate except that the dealkalization step is provided after the alkaline reaction step. For example, the dealcoholization step (low boiling substance removal step), the desalting step, the alkaline reaction step, and the dealkalization step can be performed in an appropriate order, but are usually performed after the hydrogenation step. Note that, among the above-described steps, the catalyst separation step, the neutralization step by alkali, the dealcoholization step (low boiling substance removal step), the desalting step, the alkaline reaction step, and the dealkalization step may be performed as necessary, and do not necessarily have to be performed.

FIG. 1 is a flow sheet of an apparatus illustrating an example of an embodiment for manufacturing 1,3-butylene glycol of the present disclosure. A is a dehydration column and is related to the dehydration step. B is a desalting column and is related to the desalting step. C is a distillation column for removing a high boiling substance (high boiling substance removal column) and is related to the high boiling substance removal distillation step (high boiling substance removal step). D is an alkaline reactor and is related to the alkaline reaction step. E is a dealkalization column and is related to the dealkalization step. F is a product distillation column (product column) and is related to the product distillation step. A-1, B-1, C-1, E-1, and F-1 are condensers. A-2. C-2, and F-2 are reboilers. Hereinafter, an example of an embodiment of the method for manufacturing 1,3-butylene glycol of the present disclosure will be described using the present flow sheet.

Crude 1,3-butylene glycol (corresponding to “X-1”) obtained by hydrogen reduction of a raw material for hydrogenation is fed to the dehydration column A. Note that the crude 1,3-butylene glycol (corresponding tip “X-1”) may be fed to the dehydration column A after undergoing the dealcoholization (distillation step by a dealcoholization column) for removing an alcohol such as ethanol and a low boiling point substance.

In the manufacturing method according to the present disclosure, in the dehydration column A for use in the dehydration step, a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate (preferably, top of the column) (corresponding to “X-2” in FIG. 1). Further, a crude 1,3-butylene glycol stream containing 1,3-butylene glycol can he obtained from below the feed plate (preferably, the bottom of the column).

The dehydration column A and any other distillation column for separating 1,3-butylene glycol can be, for example, perforated-plate columns. bubble columns, and the like, but are more preferably packed columns with a low pressure loss, filled with Sulzer Packing, Melapack (trade names owned by Sumitomo Heavy Industries, Ltd.). This is because 1,3-butylene glycol and trace impurities would be thermally decomposed at a high temperature (e.g., 150° C. or higher) and produce a low boiling point substance, which is a coloring component, and thus the distillation temperature is to he lowered. In addition, this is also because a long thermal history (residence time) for 1,3-butylene glycol would also have a similar effect. Thus, the reboiler employed is preferably one with a short residence time of the process side fluid, for example, a thin-film evaporator, such as a natural downward flow thin-film evaporator or a forced-stirring thin-film evaporator.

The number of theoretical plates of the dehydration column A is, for example, from 1 to 100 plates, preferably from 2 to 80 plates, from 3 to 80 plates, from 4 to 60 plates, from 5 to 40 plates, from 6 to 30 plates or from 7 to 20 plates, and more preferably from 8 to 15 plates. A feed position for the liquid feed is, for example, from 10 to 90%, preferably from 20 to 80%, and more preferably from 30 to 70%, and even more preferably from 40 to 60% of a height of the column facing downward from the top of the column. During the distillation in the dehydration column A, the pressure (absolute pressure) of the top of the column is, for example, 101 kPa or lower, preferably from 0.1 to 90 kPa, more preferably from 0.5 to 70 kPa, and even more preferably from 1 to 50 kPa, from 2 to 30 kPa or from 3 to 20 kPa, and particularly preferably from 4 to 10 kPa. Note that the distillation in the dehydration column A may be performed under pressure, in which case the pressure (gauge pressure) at the top of the column may be, for example, 0.2 MPaG or lower, or 0.1 MPaG or lower.

A concentration of 1,3-butylene glycol in the liquid feed into the dehydration column A is, for example, 9 wt. % or higher, preferably 10 wt. % or higher, more preferably 15 wt. % or higher, even more preferably 20 wt. % or higher, 25 wt. % or higher, 30 wt. % or higher, 35 wt. % or higher, 40 wt. % or higher, 45 wt. % or higher, 50 wt. % or higher, 55 wt. % or higher, or 60 wt. % or higher, and particularly preferably 70% or higher. An upper limit of the concentration of 1,3-butylene glycol in the liquid feed into the dehydration column A is, for example, 90 wt. %, 85 wt. %, or 80 wt. %. However, in consideration of the hydrogen addition reaction and the like in the step prior to the dehydration step, the concentration of water in the liquid feed into the dehydration column A is preferably higher in some cases. With these things taken into consideration, the concentration of 1,3-butylene glycol in the liquid feed into the dehydration column A may be, for example, 1 wt. % or higher, 5 wt. % or higher, 10 wt. % or higher, 15 wt. % or higher, 20 wt. % or higher, 25 wt. % or higher, 30 wt. % or higher, 35 wt. % or higher, 40 wt. % or higher, 50 wt. % or higher, 60 wt. % or higher, 70 wt. % or higher, 80 wt. % or higher, or 90 wt. % or higher. Furthermore, the concentration of 1,3-butylene glycol in liquid feed into the dehydration column A may be, for example, 99 wt. % or lower, 95 wt. % or higher, 90 wt. % or lower, 85 wt. % or lower, 80 wt. % or lower, 75 wt. % or lower, 70 wt. % or lower, 65 wt. % or lower, 60 wt. % or lower, 55 wt. % or lower, 50 wt. % or lower, or 45 wt. % or lower. The concentration of 1,3-butylene glycol in the liquid feed into the dehydration column A can be, for example, in the rang described above by adjusting the reaction conditions in the hydrogenation step (for example, the concentration of acetaldols used as a raw material) and the distillation conditions of the dealcoholization column (low boiling substance removal column) provided before the dehydration column as needed.

The concentration (wt. %) of 1,3-butylene glycol is a value determined according to the following formula by determining an area proportion (GC area %) of the peak of 1,3-butylene glycol relative to a total peak area in the gas chromatographic analysis under the following conditions. Note that the concentration (wt. %) of water in the liquid feed into the dehydration column A is a value measured by the method which will he described below (Karl Fischer method).

• Concentration (wt. %) of 1,3-butylene glycol in liquid feed into dehydration column A=(1−concentration (wt. %) of water in liquid feed into dehydration column A/100)×GC area % of 1,3-butylene glycol described above,
• Conditions for the gas chromatographic analysis are as follows:

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C./min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Detector and Detection Temperature: a flame ionization detector (FID), 280° C.

In the manufacturing method of the present disclosure, the content of acetaldehyde in the liquid feed into the dehydration column A is 1000 ppm or lower, and the content of crotonaldehyde therein is 400 ppm or lower. A content of acetaldehyde in the liquid feed into the dehydration column A is preferably 900 ppm or lower, more preferably 800 ppm or lower, 700 ppm or lower, 600 ppm or lower, or 500 ppm or lower, and even more preferably 400 ppm or lower, 300 ppm or lower, 200 ppm or lower, 155 ppm or lower, or 140 ppm or lower, and may be 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, or 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or 1 ppm or lower.

The content of crotonaldehyde in the liquid feed into the dehydration column A is preferably 300 ppm or lower, more preferably 200 ppm or lower, and even more preferably 150 ppm or lower, 130 ppm or lower, 117 ppm or lower, or 100 ppm or lower, and may be 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or I ppm or lower.

The acetaldehyde content and the crotonaldehyde content in the liquid feed into the dehydration column A can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) upstream of the dehydration column A, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column). For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) can reduce the acetaldehyde content and the crotonaldehyde content of the liquid feed into the dehydration column A. Furthermore, the content can be adjusted according to the conditions for the hydrogen addition reaction in the hydrogenation step, and when hydrogen addition is fully performed, the concentration of acetaldehyde and crotonaldehyde can be lowered to below the detection limit, but there are disadvantages such as a high reaction pressure, an increase in size of the reaction tank and the like.

Note that the acetaldehyde content and the crotonaldehyde content of the liquid feed into the dehydration column A can be quantified by GC-MS analysis (gas mass spectrometry).

In the manufacturing method of the present disclosure, the content of water in the liquid feed into the dehydration column A is, for example, 90 wt. % or lower, 85 wt. % or lower, 80 wt. % or lower, 70 wt. % or lower, 60 wt. % or lower, 50 wt. % or lower, or 40 wt. % or lower, and preferably 35 wt. % or lower, more preferably 30 wt. % or lower, and even more preferably 25 wt. % or lower. A lower limit of the water content of the liquid feed into the dehydration column A is, for example, 10 wt. % or 15 wt. %. Note that, when the hydrogen addition reaction in the hydrogenation step is taken into consideration, higher water concentration and lower the viscosity are advantageous for the hydrogen addition reaction because they increase the solubility and degree of dispersion of hydrogen in the liquid. The water content of the liquid feed into the dehydration column A can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) upstream of the dehydration column A, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column). For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) can reduce the water content of the liquid feed into the dehydration column A. Note that the water content of the liquid feed into the dehydration column A can be quantified by the Karl Fischer moisture measurement instrument.

In the manufacturing method of the present disclosure, the content of the low boiling point component (excluding water) in the liquid feed into the dehydration column A is, for example, 20% or lower, preferably 10% or lower, more preferably 8% or lower, even more preferably 5% or lower, and particularly preferably 3% or lower or 2% or lower, and may be 1% or lower, 0.5% or lower, or 0.1% or lower. The content of the low boiling point component (also referred to as “low boiling point substance” or “low boiling substance”) excluding water in the liquid feed into the dehydration column A is a total area proportion (area %) of peaks having shorter retention times than the peak of 1,3-butylene glycol relative to the total peak area in the gas chromatographic analysis under the above conditions. The content of the low boiling point component (excluding water) in the liquid feed into the dehydration column A can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) upstream of the dehydration column A, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column). For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) can reduce the content of the low boiling point component (excluding water) in the liquid feed into the dehydration column A. Furthermore, the concentration of the low boiling point component (excluding water) in the liquid feed into the dehydration column A can be reduced, for example, by reaction conditions (e.g., reaction temperature) in the hydrogenation step.

The content of the high boiling point component in the liquid feed into the dehydration column A is, for example, 20% or lower, preferably 10% or lower, more preferably 7% or lower, 4% or lower, 3% or lower, or 2% or lower, even more preferably 1% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower, 0.2% or lower, 0.1% or lower, or 0.05% or lower, and particularly preferably 0.01% or lower. The content of the high boiling point component in the liquid feed into the dehydration column A can be adjusted, for example, by reaction conditions (e.g., reaction temperature) in the hydrogenation step. The content of the high boiling point component in the liquid feed into the dehydration column A is a total area proportion (area %) of peaks having longer retention times than the peak of 1,3 BG to the total peak area in the gas chromatographic analysis under the above conditions.

In the manufacturing method of the present disclosure, the reflux ratio in the dehydration column A [dehydration column reflux amount/dehydration column distilled amount (discharge amount to outside of distillation column) is, for example, 0.03 or higher. Note that, during the reflux to the dehydration column A, a condensate of dehydration column top vapor is ordinarily refluxed to the dehydration column, and a part or all of the reflux may be replaced by a water-containing liquid (e.g., pure water) charged into the dehydration column. In that case, the “dehydration column reflux amount” refers to a sum of an amount of the condensate of dehydration column top vapor refluxed to the dehydration column and an amount of the water-containing liquid (e.g., pure water) charged into the dehydration column.

The reflux ratio in the dehydration column A is preferably 0.04 or higher, 0.05 or higher, 0.06 or higher, 0.07 or higher, 0.08 or higher, 0.09 or higher, 0.1 or higher, 0.12 or higher, 0.14 or higher, 0.16 or higher, 0.18 or higher, 0.2 or higher, 0.22 or higher, 0.24 or higher, 0.26 or higher, 0.28 or higher, 0.3 or higher, 0.33 or higher, 0.36 or higher, 0.4 or higher, 0.45 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.1 or higher, 1.2 or higher, 1.3 or higher, 1.4 or higher, 1.5 or higher, 1.6 or higher, 1.7 or higher, 1.8 or higher, 1.9 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 6 or higher, 7 or higher, 8 or higher, or 9 or higher, and more preferably 10 or higher (for example, 15 or higher, 20 or higher, 25 or higher, 30 or higher, or 40 or higher), from the perspective of reducing the content of the low boiling point product (containing water) in the crude 1,3-butylene glycol stream containing 1,3-butylene glycol taken out from below the feed plate of the dehydration column A (preferably, the bottom of the column). In particular, in the manufacturing method 2 of the present disclosure, the reflux ratio in the dehydration column A is preferably 0.2 or higher, more preferably 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.5 or higher, 2 or higher, 3 or higher, or 4 or higher, even more preferably 5 or higher, and particularly preferably 10 or higher. An upper limit of the reflux ratio is, for example, 50 (lower than 50), preferably 20 (lower than 20), and more preferably 10 (lower than 10), from the point of view of energy cost. In a case where the number of theoretical plates of the dehydration column A is large, sufficient separation can be performed, even when the reflux ratio is approximately 0.03.

In the manufacturing method of the present disclosure, the distillation rate in the dehydration column A can be appropriately set in accordance with the concentration of water in the liquid feed into the dehydration column A. Desirably, the distillation rate is a sufficient distillation rate for the total amount of water in the liquid feed to be distilled. For example, in a case where the concentration of water in the liquid feed into the dehydration column A is X wt. %, the distillation rate in the dehydration column A is preferably X wt. % or higher. Therefore, the distillation rate in the dehydration column A is, for example, 95 wt. % or lower, 90 wt. % or lower, 85 wt. % or lower, 80 wt. % or lower, 75 wt. % or lower, 70 wt. % or lower, 65 wt. % or lower, 60 wt. % or lower, 55 wt. % or lower, 50 wt. % or lower. 45 wt. % or lower. 40 wt. % or lower, 35 wt. % or lower, 30 wt. % or lower. 25 wt. % or lower. 20 wt. % or lower, 15 wt. % or lower, 10 wt. % or lower, or 5 wt. % or lower. The distillation rate refers to a proportion (wt. %) of an amount of liquid extracted from above the feed plate of the dehydration column A (e.g., the top of the column) to the outside of the distillation column with respect to a charged amount into the dehydration column A.

In the manufacturing method of the present disclosure, the 1,3 BG recovery rate in the dehydration column A is, for example, 99.3% or higher.

Note that, in the present specification, the 1,3 BG recovery rate in the dehydration column A is a value (%) determined by the following formula. {1−[concentration (wt. %) of 1,3 BG in distillate×(distilled amount (part)−recycled amount (part))]/(concentration (wt. %) of 1,3 BG in liquid feed×charged amount (part))}×100

Note that the low boiling point substance and the high boiling point substance may be hydrolyzed by water to produce 1,3 BG, while the high boiling point substance may be produced by polymerization of 1,3 BG. Further, trace impurities may be produced or disappear. Thus, the mass balance in the dehydration column may not always be made. This applies to the dealcoholization column (low boiling substance removal column), the high boiling substance removal column, the product column, and other distillation columns.

Next, the crude 1,3-butylene glycol stream containing 1,3-butylene glycol taken out from below the feed plate of the dehydration column A (preferably, the bottom of the column) is fed to the desalting column B. In the desalting column B, the crude 1,3-butylene glycol stream after the desalting is obtained from the top of the column, and a salt, a high boiling point substance, or the like is discharged from the bottom of the column. The bottom rate (%) of the desalting column B [(desalting column bottom amount (part)/desalting column charged amount (part)×100] is, for example, from 0.1 to 40 wt. %, preferably from 1 to 35 wt. %, more preferably from 2 to 30 wt. %, even more preferably from 3 to 25 wt. %, and particularly preferably from 5 to 20 wt. %, and may be from 7 to 15 wt. %. At least a portion of the bottom in the desalting column may be recycled to the step prior to the desalting step.

The crude 1,3-butylene glycol stream after the desalting described above is fed to the high boiling substance removal column C. In the high boiling substance removal column C, the high boiling point component (preferably, high boiling point substance) is discharged from below the feed plate (preferably, from the bottom of the column). Meanwhile, the crude 1,3-butylene glycol stream after high boiling point substance removal (higher-purity 1,3-butylene glycol) is obtained from above the feed plate.

The high boiling substance removal column C can be, for example, a perforated-plate column, a bubble column, or the like, but is more preferably a packed column with a low pressure loss, filled with Sulzer Packing, Melapack (trade names of Sumitomo Heavy Industries, Ltd.). This is because 1,3-butylene glycol and trace impurities would be thermally decomposed at a high temperature (e.g., 150° C. or higher) and produce a low boiling point substance, which is a coloring component and thus the distillation temperature is to be lowered. In addition, this is also because a long thermal history (residence time) for 1,3-butylene glycol would also have a similar effect. Thus, the reboiler employed is preferably one with a short residence time of the process side fluid, for example, a thin-film evaporator, such as a natural downward flow thin-film evaporator or a forced-stirring thin-film evaporator.

The number of theoretical plates of the high boiling substance removal column C is, for example, from 1 to 100 plates, preferably from 2 to 90 plates, more preferably from 3 to 80 plates, more preferably from 4 to 70 plates, from 5 to 60 plates, from 8 to 50 plates, or from 10 to 40 plates, and particularly preferably from 15 to 30 plates. A feed position for the liquid feed is, for example, from 10 to 90%, preferably from 20 to 80%, and more preferably from 30 to 70 plates, and even more preferably from 40 to 60% of a height of the column facing downward from the top of the high boiling substance removal column. In the distillation in the high boiling substance removal column C, a pressure (absolute pressure) at the top of the column is, for example, from 0.01 to 50 kPa, preferably from 0.1 to 30 kPa, more preferably from 0.3 to 20 kPa, and even more preferably from 0.5 to 10 kPa.

A concentration of 1,3 BG in the liquid feed into the high boiling substance removal column C is, for example, 95% or higher, preferably 96% or higher, more preferably 97% or higher, even more preferably 98% or higher, and particularly preferably 99% or higher. In particular, in the manufacturing method 2 of the present disclosure, the concentration of 1,3 BG in the liquid feed into the high boiling substance removal column C is preferably 97% or higher, more preferably 98% or higher, and even more preferably 99% or higher. The concentration of 1,3 BG into the liquid feed into the high boiling substance removal column C can be improved by adjusting the distillation conditions of the dehydration column A and the desalting column B. For example, by increasing the reflux ratio in the dehydration column A or increasing the bottom rate of the desalting column B, the concentration of 1,3 BG in the liquid feed into the high boiling substance removal column C can be increased. Note that the concentration of the 1,3 BG described above is an area proportion (area %) of a 1,3 BG peak relative to a total peak area in a gas chromatographic analysis (GC analysis) under the following conditions. Conditions for the gas chromatographic analysis are as follows:

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C./min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Detector and Detection Temperature: a flame ionization detector (FID), 280° C.

A content of the high boiling point component in the liquid feed into the high boiling substance removal column C is, for example, 4% or lower, preferably 3% or lower, more preferably 2% or lower, even more preferably 1% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower, 0.2% or lower, 0.1% or lower, or 0.05% or lower, and particularly preferably 0.01% or lower. In particular, in the manufacturing method 2 of the present disclosure, a content of the high boiling point component in the liquid feed into the high boiling substance removal column C is preferably 3% or lower, more preferably 2% or lower, even more preferably 1.5% or lower, 1% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower, 0.2% or lower, 0.1% or lower, or 0.05% or lower, and particularly preferably 0.01% or lower. The content of the high boiling point component in the liquid feed into the high boiling substance removal column C can be reduced by adjusting the distillation conditions of the desalting column B. For example, by increasing the bottom rate of the desalting column B, it is possible to reduce the content of the high boiling point component in the liquid feed into the high boiling substance removal column C. Note that the content of the high boiling point component in the liquid feed into the high boiling substance removal column C is a total area proportion (area %) of peaks having longer retention times than the 1,3 BG peaks relative to the total peak area in the gas chromatographic analysis under the above conditions.

In the manufacturing method of the present disclosure, the content of acetaldehyde in liquid feed into the high boiling substance removal column C is, for example, 500 ppm or lower, preferably 205 ppm or lower (e.g., 200 ppm or lower), more preferably 100 ppm or lower, even more preferably 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower or 10 ppm or lower, and particularly preferably 5 ppm or lower, and may be lower than 2 ppm or lower than 1 ppm. The content of crotonaldehyde in the liquid feed into the high boiling substance removal column C is, for example, 200 ppm or lower, preferably 110 ppm or lower, more preferably 100 ppm or lower, even more preferably 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, or 3 ppm or lower, and particularly preferably 2 ppm or lower, and may be lower than 1 ppm. The acetaldehyde content and the crotonaldehyde content in the liquid feed into the high boiling substance removal column C can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) and a dehydration column upstream of the high boiling substance removal column C, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column) and the dehydration column. For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) and the dehydration column can reduce the acetaldehyde content and the crotonaldehyde content of the liquid feed into the high boiling substance removal column C. Note that the acetaldehyde content and the crotonaldehyde content of the liquid feed into the high boiling substance removal column C can be quantified by GC-MS analysis (gas mass spectrometry).

In the manufacturing method of the present disclosure, the content of water in liquid feed into the high boiling substance removal column C is, for example, 1.2 wt. % or lower, preferably 1.1 wt. % or lower, more preferably 1.0 wt. % or lower, even more preferably 0.95 wt. % or lower, 0.9 wt. % or lower, 0.8 wt. % or lower, 0.7 wt. % or lower, 0.6 wt. % or lower, 0.5 wt. % or lower, 0.4 wt. % or lower, 0.3 wt. % or lower, or 0.2 wt. % or lower, and particularly preferably 0.1 wt. % or lower. The content of water in the liquid feed into the high boiling substance removal column C can be reduced by adjusting the distillation conditions of the dehydration column A. For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dehydration column A can reduce the concentration of water in the liquid feed into the high boiling substance removal column C. Note that the water content of the liquid feed into the high boiling substance removal column CF can be quantified by the Karl Fischer moisture measurement instrument.

In the manufacturing method of the present disclosure, the content of the low boiling point component (excluding water) in the liquid feed into the high boiling substance removal column C is, for example, 1.8% or lower, preferably 1.6% or lower, more preferably 1.4% or lower, even more preferably 1.2% or lower, 1.1% or lower, 1% or lower, 0.9% or lower, 0.8% or lower, 0.7% or lower, 0.6% or lower, 0.5% or lower, 0.4% or lower. 0.3% or lower, or 0.2% or lower, and particularly preferably 0.1% or lower. The content of the low boiling point component (also referred to as “low boiling point substance” or “low boiling substance”) excluding water in the liquid feed into the high boiling substance removal column C is a total area proportion (area %) of peaks of having shorter retention times than the peak of 1,3-butylene glycol relative to the total peak area in the gas chromatographic analysis under the above conditions. The content of the low boiling point component (excluding water) in the liquid feed into the high boiling substance removal column C can be reduced, for example, by providing a deal cotton zation column (low boiling substance removal column) upstream of the high boiling substance removal column C, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column). For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) can reduce the content of the low boiling point component (excluding water) in the liquid feed into the high boiling substance removal column C.

In the manufacturing method 1 of the present disclosure, the reflux ratio in the high boiling substance removal column C [high boiling substance removal column reflux amount/high boiling substance removal column distilled amount (discharge amount to outside of distillation column)] is, for example, 0.02 or higher. The reflux ratio is preferably 0.03 or higher, more preferably 0.04 or higher, even more preferably 0.05 or higher, 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.2 or higher, 1.5 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, or 10 or higher, and particularly preferably 20 or higher, from the perspective of reducing the dry point of the 1.3-butylene glycol product. In particular, in the manufacturing method 2 of the present disclosure, the reflux ratio in the high boiling substance removal column C is preferably 0.02 or higher, more preferably 0.03 or higher, more preferably 0.04 or higher, 0.05 or higher, 0.06 or higher, 0.07 or higher, 0.08 or higher, or 0.09 or higher, even more preferably 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.2 or higher, 1.5 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher or 10 or higher, and particularly preferably 20 or higher. An upper limit of the reflux ratio is, for example, 100, preferably 50 from the point of energy cost. In a case where the number of theoretical plates of the high boiling substance removal column C is large, sufficient separation can be performed, even when the reflux ratio in the high boiling substance removal column C is approximately 0.02.

In the manufacturing method of the present disclosure, the reflux ratio in the high boiling substance removal column C is within the range described above, and thus 1,3 BG having a very low content of the high boiling point component and a low dry point can be manufactured with a high recovery rate.

In the manufacturing method of the present disclosure, the bottom rate of the high boiling substance removal column C is, for example, lower than 30 wt.%. In addition, it is not limited to this value when the bottom of the high boiling substance removal column is distilled in a further distillation column to commercialize 1,3 BG after high boiling point substance removal. When an amount of the final high boiling substance-containing product extracted to the outside of the system is reduced to lower than 30 wt. % with respect to the charged amount into the high boiling substance removal column C, it is possible to obtain 1,3 BG in a high yield. Note that the bottom rate refers to a proportion (wt. %) of an amount of liquid extracted from below the feed plate (for example, bottom of the column) of the high boiling substance removal column C with respect to a charged amount into the high boiling substance removal column C (also including an amount of the liquid recycled, when the liquid is recycled to the previous steps which will be described later).removal column C to the high boiling column C. Note that when the liquid is recycled to the previous steps described below, the recovery rate of 1,3 BG is improved as the discharge rate to the outside is lower.

The bottom rate of the high boiling substance removal column C can also be preferably 25 wt. % or lower, more preferably 20 wt. % or lower, even more preferably 15 wt. % or lower, 10 wt. % or lower, 7 wt. % or lower, 5 wt. % or lower, 4 wt. % or lower, 3 wt. % or lower, or 2 wt. % or lower, and can be 1 wt. % or lower, from the perspective of improving the recovery rate of 1,3 BG. In addition, the bottom rate of the high boiling point component removal column C is, for example, 0.01 wt. % or higher, preferably 0.1 wt. % or higher, 0.5 wt. % or higher, or 1 wt. % or higher, more preferably 2 wt. % or higher, 3 wt. % or higher, 4 wt. % or higher, 5 wt. % or higher, 6 wt. % or higher, 7 wt. % or higher, 8 wt. % or higher, 9 wt. % or higher, 10 wt. % or higher, or 15 wt. % or higher, and particularly preferably 20 wt. % or higher, from the perspective of reducing the dry point of the 1,3-butylene glycol product.

At least a portion of the liquid (hereinafter, sometimes referred to as “bottom”) in which the high boiling component is concentrated, which is extracted from below the feed plate of the high boiling substance removal column C, may be recycled to step prior to the high boiling substance removal step (dashed arrow illustrated in the lower part of the high boiling substance removal column C in FIG. 1), The recovery rate of 1,3 BG can be improved by recycling at least a portion of the bottom to the step prior to the hi gh boiling substance removal step. Note that, in the present specification, the recovery rate of 1,3 BG in the high boiling substance removal column C is a value (%) determined by the following formula.

{1−[GC area % of 1,3 BG in bottom]×(bottom amount (part)−amount (part) of bottom recycled]/(GC area % of 1,3 BG in liquid feed×charged amount (part)}×100

Note that the low boiling point substance and the high boiling point substance may be hydrolyzed by water to produce 1,3 BG, while the high boiling point substance may be produced by polymerization of 1,3 BG. Further, trace impurities may be produced or disappear. Thus, the mass balance in the high boiling substance removal column may not always be made.

The recovery rate of 1,3 BG in the high boiling substance removal column C is, for example, higher than 80%, preferably 85% or higher, more preferably 90% or higher, even more preferably 95% or higher, and particularly preferably 99% or higher.

Examples of the step prior to the high boiling point substance removal step include an acetaldehyde polymerization step (aldol condensation step of acetaldehyde), a reaction step (hydrogenation step), a dealcoholization step (low boiling point substance removal step), a dehydration step, and a desalting step. Among these steps, the bottom is preferably recycled to the acetaldehyde polymerization step (aldol condensation step of acetaldehyde), since 1,3 BG is produced by hydrolysis of the high boiling point substance. In addition, the hydrogen addition reduction may produce 1,3 BG, and the bottom may be recycled to the hydrogen addition step from that viewpoint.

The amount of the bottom recycled to the step prior to the high boiling point substance removal step can be appropriately selected within a range of the amount of the bottom. The amount of the bottom recycled to the step prior to the high boiling point substance removal step is, for example, lower than 30 wt. %, preferably 25 wt. % or lower with respect to the charged amount into the high boiling substance removal column C. Note that the amount of the bottom recycled may be 20 wt. % or lower, 15 wt. % or lower, 10 wt. % or lower, 7 wt. % or lower, 5 wt. % or lower, 4 wt. % or lower, 3 wt. % or lower, 2 wt. % or lower, or 1 wt. % or lower with respect to the charged amount into the high boiling substance removal column C. In addition, from the perspective of improving the recovery rate of 1,3 BG in the high boiling substance removal column and the yield throughout the 1,3 BG manufacturing process, the amount of the bottom recycled to the step prior to the high boiling point substance removal step is, for example, 0.01 wt. % or higher, preferably 0.1 wt. % or higher, more preferably 2 wt. % or higher, 3 wt. % or higher, 4 wt. % or higher, 5 wt. % or higher, 7 wt. % or higher, or 10 wt. % or higher, and particularly preferably 20 wt. % or higher relative to the amount of charge into the high boiling substance removal column C. Note that, in a case where the amount of the bottom is minimized as much as possible, 1,3 BG can be recovered in a high yield, even without being recycled to the previous steps.

The crude 1,3-butylene glycol stream taken out from above the feed plate of the high boiling substance removal column C can be a 1,3 -butylene glycol product as it is in the manufacturing method 2 of the present disclosure. Furthermore, the crude 1,3-butylene glycol stream taken out from above the feed plate of the high boiling substance removal column C is subjected to alkaline treatment in the alkaline reactor D described below, and evaporated (or distilled) with the dealkalization column E, and the distillate at the top of the dealkalization column E can be a 1,3-butylene glycol product.

According to the manufacturing method 2 of the present disclosure, the acetaldehyde content and the crotonaldehyde content in the liquid feed into the dehydration column A are within the predetermined ranges, and the reflux ratio in the high boiling substance removal column C is the predetermined value or higher. Therefore, it is possible to industrially efficiently manufacture high-purity 1,3-butylene glycol having a high potassium permanganate test value, a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point.

In the manufacturing method 1 of the present disclosure, the crude 1,3-butylene glycol stream taken out from above the feed plate of the high boiling substance removal column C is fed, for example, to the alkaline reactor (e.g., a flow-through tubular reactor) D and is treated with a base (treated with alkali). The base treatment can decompose by-products contained in the crude 1,3-butylene glycol. The base is added to the alkaline reactor D or its upstream piping or the like. The base is added in an amount of, for example, from 0.05 to 10 wt. %, preferably from 0.1 to 1.0 wt. % relative to the crude 1,3-butylene glycol stream subjected to the alkaline treatment. With the added amount of the base exceeding 10 wt. %, the base would precipitate in the distillation column, piping, or the like, and this may cause blockage. In addition, the decomposition reaction of a high boiling point compound would occur, and by-products may be produced on the contrary. With the added amount of the base of lower than 0.05 wt. %, the effect of decomposing by-products is reduced.

The base added in the alkaline reactor D or its upstream piping is not particularly limited but is, for example, preferably an alkali metal compound. Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, sodium (bi)carbonate, and potassium (bi)carbonate. A basic ion exchange resin can also be used as the base. The base is preferably sodium hydroxide or potassium hydroxide from the perspective of reducing the byproducts contained in the 1,3-butylene glycol product obtained finally. The base may be added as is in the solid form but is preferably added in an aqueous solution to facilitate operation and contact with a solution to be treated. One of the bases described above may be used alone, or two or more may be used sitnultaneously.

The reaction temperature in the alkaline reactor D is not particularly limited but is, for example, preferably from 90 to 140° C. and more preferably from 110 to 130° C. The reaction at a reaction temperature lower than 90″C would require long reaction residence time and thus require a reactor with a large volume and make the process uneconomical. The reaction at a reaction temperature exceeding 140° C. would increase coloration in the 1.3-butylene glycol product obtained finally. The reaction residence time is, for example, preferably from 5 to 120 minutes and more preferably from 10 to 30 minutes. A reaction residence time shorter than 5 minutes may cause an insufficient reaction and deteriorate the quality of the 1,3-butylene glycol product obtained finally. A reaction residence time exceeding 120 minutes would require a large reactor and increase the cost of equipment, and thus would be disadvantageous from the economic point of view.

After exiting the alkaline reactor D, the crude reaction liquid stream is fed to the dealkalization column (e.g., thin film evaporator) E according to need, and the base and the like are removed from the bottom of the column by evaporation. Meanwhile, from the top of the dealkalization column E is obtained a crude 1,3-butylene glycol stream after the removal of a base (which is used as the 1,3-butylene glycol product, in the manufacturing method 2 of the present disclosure). The evaporator used for the dealkalization column E is suitably a natural downward flow thin-film evaporator or a forced-stirring thin-film evaporator with a short residence time for the purpose of reducing the thermal history to the process fluid. A demister may be installed in a space above the charging position of the dealkalization column (e.g., thin film evaporator) E, and droplets of a base or the like may be removed. This makes it possible to prevent the base and the high boiling point substance from being mixed into the 1,3-butylene glycol product.

Evaporation is performed in the evaporator used for the dealkalization column E, for example, under a reduced pressure at the top of the column of 20 kPa or lower (absolute pressure), preferably from 0.5 to 10 kPa (absolute pressure). The temperature of the evaporator is, for example, preferably from 90 to 120° C. The crude 1,3-butylene glycol stream containing a low boiling point substance distilled off from the top of the column is fed to the product distillation column (product column) F. Note that, as described above, in the manufacturing method 2 of the present disclosure, the distillate (corresponding to E-1) from the top of the dealkalization column E can be a 1,3-butylene glycol product.

Note that the alkaline reactor D and the dealkalization column E may be installed between the desalting column B and the high boiling substance removal column C, or between the dehydration column A and the desalting column B (in this case, the desalting column may also serve as a dealkalization column), or before the dehydration column A. In addition, without providing the alkaline reactor D or the dealkalization column F, the alkaline treatment can be performed by adding the base into a high boiling substance removal column charging line or into a dehydration column charging line, or adding the base to the reaction solution after the hydrogenation [and then charging the dealcoholization column (low boiling substance removal column) with the solution].

In the manufacturing method 1 of the present disclosure, in the product column F for use in the product distillation step, a 1,3-butylene glycol liquid feed having a concentration of acetaldehyde of 500 ppm or lower and a. concentration of crotonaldehyde of 200 ppm or lower is distilled under a condition of a reflux ratio of higher than 0.1, a liquid having a concentrated low boiling point component is distilled off from above the feed plate (corresponding to “X-6” in FIG. 1), and 1,3-butylene glycol is extracted from below the feed plate (corresponding to “Y” in FIG. 1). The extracted 1,3-hutylene glycol can be a 1,3-hutylene glycol product.

The product column F can be, for example, a perforated-plate column, a bubble column, or the like, but is more preferably a packed column with a low pressure loss, filled with Sulzer Packing, Melapack (trade names owned by Sumitomo Heavy Industries, Ltd.). This is because 1,3-butylene glycol and trace impurities would be thermally decomposed at a high temperature (e.g., 150° C. or higher) and produce a low boiling point substance, which is a coloring component, and thus the distillation temperature is to be lowered. In addition, this is also because a long thermal history (residence time) for 1,3-butylene glycol would also have a similar effect. Thus, the reboiler employed is preferably one with a short residence time of the process side fluid, for example, a thin-film evaporator, such as a natural downward flow thin-film evaporator or a forced-stirring thin-film evaporator.

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

In FIG. 1, in charging the product column F, the column top vapor from the dealkalization column E is condensed in the condenser E-1, and the resulting condensed liquid is fed, but the column top vapor from the dealkalization column E may be directly fed to the product column F.

The concentration of 1,3-butylene glycol in the liquid feed (1,3-butylene glycol liquid feed) into the product column F is, for example, 90% or higher, preferably 92% or higher, more preferably 95% or higher, even more preferably 97% or higher, 97.1% or higher. 97.2% or higher, 97.3% or higher. 97.4% or higher, 97.5% or higher. 97.6% or higher. 97.7% or higher. 97.8% or higher, 97.9% or higher, 98% or higher, 98,1% or higher, 98,2% or higher, 98,3% or higher, 98.4% or higher. 98.5% or higher. 98.6% or higher. 98.7% or higher, 98.8% or higher, or 98.9% or higher, and particularly preferably 99% or higher. When the number of theoretical plates, the reflux amount, and the reflux ratio of the product column F are sufficient, 1,3-butylene glycol can be commercialized even if the concentration of 1,3-butylene glycol in the liquid feed into the product column F is lower than 90% .

The concentration of 1,3-butylene glycol in the liquid feed into the product column F can he improved, for example, by adjusting the distillation conditions of the dehydration column A, providing a dealcoholization column (low boiling substance removal column) before the dehydration column A, and adjusting the distillation conditions thereof, or adjusting the distillation conditions of the high boiling substance removal column C. For example, it is possible to increase the purity of 1,3-butylene glycol in liquid feed into the product column F by increasing the reflux ratio of the dealcoholization column (low boiling substance removal column), the dehydration column A, and/or the high boiling substance removal column C or increasing the number of plates.

Note that the concentration of 1,3-butylene glycol in the liquid feed into the product column F is an area proportion (area %) of the peak of 1,3-butylene glycol relative to the total peak area in the gas chromatographic analysis of the following conditions,

• Conditions for the gas chromatographic analysis are as follows:

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 pm

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C. min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Detector and Detection Temperature: a flame ionization detector (FID), 280° C.

In the manufacturing method 1 of the present disclosure, the content of acetaldehyde in liquid feed into the product column F is 500 ppm or lower, and the content of crotonaldehyde therein is 200 ppm or lower. The content of acetaldehyde in liquid feed into the product column F is preferably 205 ppm or lower (e.g., 200 ppm or lower more preferably 150 ppm or lower, even more preferably 120 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower or 10 ppm or lower, and particularly preferably 5 ppm or lower, and may be lower than 2 ppm. The content of the crotonaldehyde in the liquid feed into the product column F is preferably 150 ppm or lower, more preferably 130 ppm or lower, even more preferably 110 ppm or lower, 100 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower or 3 ppm or lower, and particularly preferably 2 ppm or lower, and may be lower than 1 ppm. The acetaldehyde content and the crotonaldehyde content in the liquid feed into the product column F can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) and a dehydration column upstream of the product column F, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column) and the dehydration column. For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) and the dehydration column can reduce the acetaldehyde content and the crotonaldehyde content of the liquid feed into the product column F. In addition, the acetaldehyde content and the crotonaldehyde content in the liquid feed into the product column F can be reduced by increasing the reaction temperature, increasing the residence time, or increasing the added amount of the base, in the alkaline reaction step. Note that the acetaldehyde content and the crotonaldehyde content of the liquid feed into the product column F can be quantified by GC-MS analysis (gas mass spectrometry).

In the manufacturing method 1 of the present disclosure, a content of water in liquid feed into the product column F is, for example, 1.2 wt. % or lower, preferably 1.1 wt. % or lower, more preferably 1.0 wt. % or lower, even more preferably 0.95 wt. % or lower, 0.9 wt. % or lower, 0.8 wt. % or lower, 0.7 wt. % or lower, 0.6 wt. % or lower, 0.5 wt. % or lower, 0.4 wt. % or lower, 0.3 wt. % or lower, or 0.2 wt. % or lower, and particularly preferably 0.1 wt. % or lower. The content of water in the liquid feed into the product column F can be reduced by adjusting the distillation conditions of the dehydration column A. For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dehydration column A can reduce the concentration of water in the liquid feed into the product column F. Note that the water content of the liquid feed into the product column F can be quantified by the Karl Fischer moisture measurement instrument.

The content of the low boiling point component (excluding water) in the liquid feed into the product column F is, for example, 1.8% or lower, preferably 1.6% or lower, more preferably 1.4% or lower, more preferably 1.2% or lower, 1.1% or lower, 1% or lower, 0.9% or lower, 0.8% or lower, 0.7% or lower, 0.6% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower or 0.2% or lower, and particularly preferably 0.1% or lower. The content of the low boiling point component (also referred to as “low boiling point substance”) excluding water in the liquid feed into the product column F is a total area proportion (area %) of peaks of having shorter retention times than the peak of 1,3-butylene glycol relative to the total peak area in the gas chromatographic analysis under the above conditions. The content of the low boiling point component excluding water) in the liquid feed into the product column F can be reduced, for example, by providing a dealcoholization column (low boiling substance removal column) upstream of the product column F, and adjusting the distillation conditions of the dealcoholization column (low boiling substance removal column). For example, increasing the reflux ratio and the number of plates, and the distillation rate in the dealcoholization column (low boiling substance removal column) can reduce the concentration of the low boiling point component (excluding water) in the liquid feed into the product column F.

The content of the high boiling point component (excluding water) in the liquid feed into the product column F is, for example, 1.8% or lower, preferably 1.6% or lower, more preferably 1.4% or lower, more preferably 1.2% or lower, 1.1% or lower, 1% or lower, 0.9% or lower, 0.8% or lower, 0.7% or lower, 0.6% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower or 0.2% or lower, and particularly preferably 0.1% or lower. The content of the high boiling point component (also referred to as “high boiling point substance” or “high boiling substance”) excluding water in the liquid feed into the product column F is a total area proportion (area %) of peaks having longer retention times than the peak of 1,3-butylene glycol relative to the total peak area in the gas chromatographic analysis under the above conditions. The content of the high boiling point component (excluding water) in the liquid feed into the product column F can be reduced, for example, by adjusting the distillation conditions of the high boiling substance removal column. For example, increasing the reflux ratio, the number of plates, or the bottom rate of the high boiling substance removal column can reduce the concentration of the high boiling point component (excluding water) in the liquid feed into the product column F.

In the manufacturing method 1 of the present disclosure, the reflux ratio in the product column F [product column reflux amount/product column distilled amount (discharge amount to outside of distillation column)] is higher than 0.1. The reflux ratio is preferably 0.2 or higher, more preferably 0.3 or higher, even more preferably 0.4 or higher, 0.5 or higher, 1 or higher, 2 or higher. 3 or higher, 4 or higher, 5 or higher, 6 or higher, 7 or higher. 8 or higher, 9 or higher, 10 or higher, 20 or higher, or 50 or higher, and particularly preferably 400 or higher (for example, 500 or higher), from the perspective of increasing the initial boiling point of the 1,3-butylene glycol product. An upper limit of the reflux ratio of the product column F is, for example, 700 or 1000 from the perspective of energy cost.

In the manufacturing method 1 of the present disclosure, the distillation rate in the product column F is, for example, lower than 30 wt. %, 29 wt. % or lower, more preferably 28 wt. % or lower, even more preferably 27 wt. % or lower, 26 wt. % or lower, 25 wt. % or lower, 24 wt. % or lower, 23 wt. % or lower, 22 wt. % or lower, 21 wt. % or lower, 20 wt. % or lower, 19 wt. % or lower, 18 wt. % or lower, 17 wt. % or lower, 16 wt. % or lower, 15 wt. % or lower, 12 wt. % or lower, 10 wt. % or lower, 8 wt. % or lower, 5 wt. % or lower, 3 wt. % or lower, 2 wt. % or lower, I wt. % or lower, 0.8 wt. % or lower, or 0.6 wt. % or lower, and particularly preferably 0.4 wt. % or lower, from the perspective of improving the recovery rate of 1,3-butylene glycol. Note that the distillation rate refers to a proportion (wt. %) of an amount of liquid extracted from above the feed plate of the product column F (for example, the top of the column) to the outside of the distillation column (when recycled to the previous step which will be described below, including also the amount of liquid recycled) with respect to a charged amount into the product column F.

At least a portion of the liquid (hereinafter, sometimes referred to as “distillate”) in which the low boiling point component is concentrated, which is extracted from above the feed plate of the product column F, may be recycled to the step prior to the product distillation step (dashed arrow illustrated on the right side of the product column F in FIG. 1). The recovery rate of 1,3-butylene glycol can be improved by recycling at least a portion of the distillate to the step prior to the product distillation step.

Examples of the step prior to the product distillation step include a dehydration step and a dealcoholization step (low boiling point substance removal step). Note that the dealcoholization step (low boiling substance removal step) is preferably provided before the dehydration step.

The amount of the distillate recycled to the step prior to the product distillation step can be appropriately selected within the range of the amount of distillate. The amount of the distillate recycle to the step prior to the product distillation step is lower than 30 wt. %, for example, with respect to the charged amount into the product column F. Also, from the perspective of improving the 1,3 BG recovery rate in the product column and the yield throughout the process, the amount of the distillate recycled to the step prior to the product distillation step is, for example, 0.01 wt. % or higher, preferably 0.05 wt. % or higher, more preferably 0.1 wt. % or higher, 0.5 wt. % or higher, 1 wt. % or higher, 1.5 wt. % or higher, 2 wt. % or higher, 3 wt. % or higher, 4 wt. % or higher, 5 wt. % or higher, 7 wt. % or higher, or 10 wt. % or higher, and particularly preferably 20 wt. % or higher with respect to the charged amount into the product column F.

In the manufacturing method 1 of the present disclosure, the acetaldehyde content and the crotonaldehyde content in the liquid feed into the dehydration column A are within the predetermined ranges, the acetaldehyde content and the crotonaldehyde content in the liquid feed into product column F are the predetermined values or lower, and the reflux ratio of the product column F is within the predetermined range. Therefore, it is possible to industrially efficiently manufacture high-purity 1,3-butylene glycol having a high potassium permanganate test value, a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point, generally with a high recovery rate.

The recovery rate of 1,3 BG in the product column F is, for example, higher than 80%, preferably 85% or higher, more preferably 90% or higher, even more preferably 95% or higher, and particularly preferably 99% or higher.

Note that, in the present specification, the recovery rate of 1,3 BG in the product column F is a value (%) determined by the following formula. {1−[GC area % of 1,3 BG in distillate]×(distilled amount (part)−amount (part) of distillate recycled]/(GC area % of 1,3 BG in liquid feed x charged amount (part)}×100

Note that, as described above, the low boiling point substance and the high boiling point substance may be hydrolyzed by water to produce 1,3 BG, while the high boiling point substance may be produced by polymerization of 1,3 BG. Thus, the mass balance in the product column may not always be made.

1,3-Butylene glycol product

According to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product having an initial boiling point of higher than 203° C. and a potassium permanganate test value (PMT) of 30 minutes or longer, a 1,3-butylene glycol product having an initial boiling point of higher than 203° C. and a dry point of 209° C. or lower, and further, a 1,3-butylene glycol product having an initial boiling point of higher than 203° C. a dry point of 209° C. or lower, and a potassium permanganate test value (PMT) of 30 minutes or longer can be obtained. The initial boiling point is preferably 204° C. or higher, more preferably 205° C. or higher, even more preferably 206° C. or higher or 207° C. or higher, and particularly preferably 208° C. or higher. The potassium permanganate test value (PMT) is more preferably longer than 30 minutes (e.g., 32 minutes or longer), even more preferably 35 minutes or longer (e.g., 40 minutes or longer), and particularly preferably 50 minutes or longer (especially, 60 minutes or longer).

Additionally, according to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product further having an area ratio of a peak of 1,3-butylene glycol of higher than 98.7% in the gas chromatographic analysis (GC analysis) under the following conditions, in addition to the above characteristics, can be obtained. Additionally, according to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product further having a total area ratio of peaks having shorter retention times than the peak of 1,3-butylene glycol of lower than 0.3%, in addition to the above characteristics, can be obtained. Additionally, according to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product further having a total area ratio of peaks having longer retention times than the peak of 1,3-butylene glycol of lower than 1.2%, in addition to the above characteristics, can be obtained. The conditions for the gas chromatographic analysis are as follows:

Analytical Column: a column with dimethvlpolvsiloxane as a stationarw phase, having a length of 30 in, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2″Clmin and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: I mL/min

Detector and Detection Temperature: a flame ionization detector (FID), 280° C.

The area ratio of the 1,3-butylene glycol peak is preferably 98.8% or higher, more preferably 98.9% or higher, even more preferably 99% or higher, 99.1% or higher, 99.2% or higher, or 99.3% or higher, more preferably 99.4% or higher, 99.5% or higher, or 99.6% or higher, or 99.7% or higher, and particularly preferably 99.8% or higher.

The total area ratio of peaks having shorter retention times than the peak of 1,3-butylene glycol is preferably 0.28% or lower, more preferably 0.25% or lower, even more preferably 0.23% or lower, 0.2% or lower, 0.17% or lower, 0.15% or lower, 0.12% or lower, 0.1% or lower, 0.07% or lower, 0.04% or lower, 0.03% or lower. 0.02% or lower, 0.01% or lower, or 0.007% or lower, and particularly preferably 0.005% or lower (for example, 0.002% or lower).

The total area ratio of the peak having longer retention times than the peak of 1,3-butylene glycol is preferably 1% or lower, more preferably 0.9% or lower, more preferably 0.8% or lower, 0.7% or lower, 0.6% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower. or 0.2% or lower, and particularly preferably 0.1% or lower.

In the present disclosure, the “(peak) area ratio” means an area proportion (area %) of a specific peak relative to the sum of the areas of all peaks appearing in the chromatogram. In addition, all peaks mean, for example, all of the peaks appearing in the analysis continued until and discontinued at a relative retention time of 7.8, provided that the relative retention time of 1,3-butylene glycol is 1.0,

According to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product having a water content of lower than 0.4 wt. % can be obtained. The content of water is preferably 0.3 wt. % or lower, more preferably 0.2 wt. % or lower, even more preferably 0.1 wt. % or lower, 0.07 wt. % or lower, 0.05 wt. % or lower, 0.03 wt. % or lower, 0.02 wt. % or lower, or 0.01 wt. % or lower, and particularly preferably 0.005 wt. % or lower. Note that the content of water can be quantified by a Karl Fischer moisture.

According to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product having an acetaldehyde content of lower than 2 ppm can be obtained. According to the method for manufacturing 1,3-butylene glycol of the present disclosure, a 1,3-butylene glycol product having a crotonaldehvde content of lower than 1.2 ppm can be obtained. The acetaldehyde content and the crotonaldehyde content of the 1,3-butylene glycol product can be quantified by GC-MS analysis (gas mass analysis), for example GC-MS analysis under the following conditions. In GC-MS analysis, even very small peaks are all subjected to mass spectrometry, and each component is quantified. Since the analysis is performed for a specific mass, a substance different in mass is not detected even when another impurity overlaps the peak. Therefore, the analysis is more sensitive than GC analysis which will be described below. In the present specification, the unit “ppm” of the content of each component by GC-MS analysis [content of each compound or the like represented by Formula (A) or (B)] means “ppm by weight”. Conditions for GC-MS analysis

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C.; min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Ion source temperature: EI 230° C., CI 250° C.

Q Pole temperature: 150° C.

Sample: subjected to analysis as it was

When the relative retention time of the peak of 1,3-butylene glycol is 1.0 in the GC-MS analysis conditions, a relative retention time of a peak of acetaldehyde is from 0.3 to 0.5, and a relative retention time of a peak of crotonaldehyde is from 0.3 to 0.5.

The acetaldehyde content of the 1,3-butylene glycol product obtained by the manufacturing method of the present disclosure is more preferably 1.8 ppm or lower, even more preferably 1.7 ppm or lower, 1.5 ppm or lower, 1.4 ppn or lower, 1.3 ppm or lower, 1.2 ppm or lower, 1.1 ppm or lower, 1.0 ppm or lower, 0.9 ppm or lower, 0.8 ppm or lower, 0.7 ppm or lower, 0.6 ppm or lower, or 0.5 ppm or lower, and particularly preferably 0.3 ppm or lower (e. g., 0.2 ppm or lower). Furthermore, the crotonaldehyde content of the 1,3-butylene glycol product obtained by the manufacturing method of the present disclosure is more preferably 1.0 ppm or lower, even more preferably 0.9 ppm or lower, 0.8 ppm or lower, 0.7 ppm or lower, 0.6 ppm or lower, 0.5 ppm or lower, 0.4 ppm or lower, or 0.3 ppm or lower, and particularly preferably 0.2 ppm or lower (e. g., 0.1 ppm or lower).

According to the method for manufacturing 1,3-butylene glycol of the present disclosure, it is possible to obtain a high-purity and high-quality 1,3-butylene glycol product having excellent initial boiling point and dry point, and, further, a large potassium permanganate test value, a high area ratio of the peak of 1,3-butylene glycol, a low total area ratio of the peaks having shorter retention times than the peak of 1.3-butylene glycol, a low total area ratio of the peaks having longer retention times than the peak of the 1,3-butylene glycol, a low content of acetaldehyde, and a low content of crotonaldehyde.

Moisturizer and Cosmetic Product

Therefore, the 1,3-butylene glycol product obtained by the manufacturing method of the present disclosure can be suitably used as a raw material for moisturizers and cosmetic products. The moisturizer of the present disclosure may contain a component other than the 1,3-butyl ene glycol product described above, such as a moisturizer component other than the 1,3-butyl ene glycol product described above. In such a moisturizer, the content of the 1,3-butyl ene glycol product described above is, for example, 10 wt. % or higher, preferably 30 wt. % or higher, more preferably 50 wt. % or higher, even more preferably 80 wt. % or higher, and particularly preferably 90 wt. % or higher, and the moisturizer may contain the 1,3-butylene glycol product described above only.

The blending amount of the 1,3-butylene glycol product in the cosmetic product is any amount in which the moisturizing performance can be exhibited according to the type and form of cosmetic. The blending amount of the 1,3-butylene glycol product in such a cosmetic product is, for example, from 0.01 to 40 wt. %, preferably from 0.1 to 30 wt. %, more preferably from 0.2 to 20 wt. %, even more preferably from 0.5 to 15 wt. %, and particularly preferably from 1 to 10 wt. %.

The cosmetic product may contain, in addition to the 1,3-butylene glycol product, for example, another moisturizer; an oil, such as a vegetable oil, a hydrocarbon oil, a higher fatty acid, a higher alcohol, or a silicone; a surfactant, such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant; a preservative, a sequestrant, a thickener, a powder, an ultraviolet absorber, an ultraviolet blocker, a fragrance, or a pH adjuster or a medicinal ingredient or bioactive component, such as a vitamin preparation, a skin activator, a blood circulation promoter, a skin-lightening preparation, an antibacterial agent, or an anti-inflammatory agent.

The cosmetic product can be a skin cosmetic product, such as a lotion, an emulsion, a cream, a gel, a pack, or a mask; or a hair cosmetic product, such as a shampoo, a rinse, or a hair restorer. In addition, the cosmetic product may be a sunscreen cosmetic product, a make-up cosmetic product or the like. Furthermore, the cosmetic product can be a pharmaceutical product or quasi drug containing a medical component. The cosmetic product can be manufactured by utilizing a method known per se.

Each aspect disclosed in the present specification can be combined with any other feature disclosed herein. Note that each of the configurations, combinations thereof, and the like in each of the embodiments are an example, and various additions, omissions, and other changes may be made as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments and is limited only by

EXAMPLES

Hereinafter, the present disclosure will be described more specifically with reference to examples, but the present disclosure is not limited by these examples. “Parts” used in the examples means “parts by weight” unless otherwise specified. Gas chromatographic analysis (GC analysis), initial boiling point measurement, and moisture measurement were performed according to the methods which will be described below.

Example 1

The method of manufacturing 3-butylene glycolI be described using FIG. 1.

Relative to 100 parts of an acetaldol solution containing 30 wt. % of water (mixed solution of 69 parts of acetaldol and 29 parts of water, containing a total of 2 parts of low boiling and high boiling impurities, Na salt: lower than 0.1 parts) as a raw material, 10 parts of hydrogen were charged into a reactor for liquid-phase hydrogen reduction, and 15 parts of Raney nickel were added as a catalyst. The reactor was kept at 120° C. and 10 MPa (gauge pressure), and liquid-phase hydrogen reduction was performed. After the catalyst was separated, the liquid after the reaction was neutralized with sodium hydroxide, and crude 1,3-butylene glycol (1) containing low boiling impurities and water was obtained.

Note that the acetaldol solution containing 30 wt. % of water used as the raw material was manufactured by stirring acetaldehyde and water in the presence of 100 ppm by weight NaOH at 30° C. at a residence time of 10 hours and dimerizing the acetaldehyde [acetaldehyde polymerization step (aldol condensation step of acetaldehyde)].

The crude 1,3-buty ene glycol (1) (corresponding to “X-1” in FIG. 1) was charged into the dehydration column A. The concentration of 1,3-butylene glycol in the liquid feed into the dehydration column A was 56 wt. %, the water concentration was 40 wt. %, the content of acetaldehyde (AD) was 130 ppm, the content of crotonaldehyde (CR) was 89 ppm, the total area ratio of impurity peaks having shorter retention times (RT) than 1,3-butylene glycol m GC analysis which will be described later was 3%, and the total area ratio of impurity peaks having longer retention tittles than 1,3-butylene glycol was 1%. In the dehydration column A, the liquid feed containing 1,3-butylene glycol was distilled under conditions of a pressure at the top of 10 kPa (absolute pressure) and a reflux ratio of 0.05, water was extracted from the top of the column, and 43 parts (distilled amount) was discharged and removed to the outside of the system relative to 100 parts of the liquid feed amount (corresponding to “X-2” in FIG. 1). From the bottom of the column, crude 1,3-butylene glycol (2) having a 1,3-butylene glycol concentration of 96.9 GC area %, a water content of 0.9 wt. %, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol in the GC analysis, which will be described later, of 0.8%, a total area ratio of peaks having longer retention times than peak of 1,3-butylene glycols of 2.3%, an acetaldehyde content of 18 ppm, and a crotonaldehyde content of 17 ppm was obtained.

The crude 1,3-butylene glycol (2) was then charged into the desalting column B. In the desalting column B, a salt, a high boiling point substance, and a portion of 1,3-butylene glycol were discharged as the evaporation residue from the bottom of the column (corresponding to “X-3” in FIG. 1). The discharge amount of the evaporation residue was 5 parts relative to 100 parts of the liquid feed amount. Meanwhile, from the top of the column was obtained crude 1,3-butylene glycol (3) containing 1,3-butylene glycol, a low boiling point substance, and a portion of a high boiling point substance.

The crude 1,3-butylene glycol (3) was then charged into the high boiling substance removal column C. In the high boiling substance removal column C, distillation was performed under the conditions of a pressure at the top of the column of 5 kPa (absolute pressure) and a reflux ratio of 0.05, and a high boiling point substance and a portion of 1,3-butylene glycol were discharged from the bottom of the column (corresponding to “X-4” in FIG. 1). The discharge amount from the bottom of the column was 20 parts relative to 100 parts of the liquid feed amount. Meanwhile, 80 parts of crude 1,3-butylene glycol (4) containing a low boiling point substance was obtained, as a distillate, from the top of the column.

The crude 1,3-butylene glycol (4 was then charged into the alkaline reactor D. At this time, a 20 wt. % sodium hydroxide aqueous solution was added to give a. concentration of sodium hydroxide of 0.1 wt. % relative to the liquid feed. The resection temperature was maintained at 120° C. in the alkaline reactor D, and a. reaction was performed at a residence time of 20 minutes,

A crude reaction liquid exiting the alkaline reactor D was then charged into the dealkalization column E. In the dealkalization column E, sodium hydroxide, a high boiling point substance, and a portion of 1,3-butylene glycol were discharged from the bottom of the column (corresponding to “X-5” in FIG. 1). The discharge amount from the bottom of the column was 10 parts relative to 100 parts of the liquid feed amount. Meanwhile, from the top of the column were obtained 90 parts of crude 1,3-butylene glycol (5) containing 1,3-butylene glycol and a low boiling point substance. The crude 1,3-butylene glycol (5) containing 1,3-butylene glycol and a low boiling point product was measured for moisture, and subjected to GC analysis and GC MS analysis. As a result, the moisture concentration was 1.1 wt. %, the area ratio of 1,3 -butylene glycol was 99%, the total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol was 0.4%, the total area ratio of impurity peaks having longer retention times than 1,3-butylene glycol was 0.6%, the content of acetaldehyde was 21 ppm, and the content of crotonaldehyde was 10 ppm.

The crude 1,3-butylene glycol (5) was then charged into the product column F. In the product column F, 10 parts of the low boiling point substance and a portion of 1,3-butylene glycol relative to 100 parts of the liquid feed amount were distilled off from the top of the column (corresponding to “X-6” in FIG. 1). and the entire amount was discharged to the outside of the system. The operation was performed at a reflux ratio (reflux amount; distilled amount) of 0.5 at that time, and 90 parts of a 1,3-butylene glycol product was obtained from the bottom of the column (distilled amount: 10 parts) (corresponding to “Y” in FIG. 1).

The obtained 1,3-butylene glycol product was measured for initial boiling point and moisture, and subjected to GC analysis and GC-MS analysis. As a result, the initial boiling point was 203.3° C., the dry point was 209° C., the moisture concentration was 0.2 wt. %, the area ratio of 1,3-butylene glycol was 99.2%, the total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol was 0.08%, the total area ratio of impurity peaks having longer retention times than 1,3-butylene glycol was 0.7%, the acetaldehyde content was 1.6 ppm, and the crotonaldehyde content was 1.0 ppm. The potassium permanganate test value was 35 minutes. The 1,3-butylene glycol recovery rate in the product column F was 90%.

Example 2

The same operation as in Example 1 was performed except that the reflux ratio in the dehydration column A was changed to 10. A 1,3-butylene glycol product was obtained from the bottom of the product column F. Note that, due to the changes in conditions employed in the dehydration column A, the dehydration column bottom composition changed, and the liquid feed compositions in the high boiling substance removal column C and the product column F changed. As a result, the product qualities changed.

The obtained 1,3-butylene glycol product was measured for initial boiling point and moisture, and subjected to GC analysis and GC-MS analysis. As a result, the 1,3-butylene glycol product had an initial boiling point was 206.5° C., the dry point was 208.9° C., the moisture concentration was 0.1 wt. %, the area ratio of 1,3-butylene glycol was 99.2%, the total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol was 0.06%, the total area ratio of impurity peaks having longer retention times than 1,3-butylene glycol was 0.7%, the acetaldehyde content was 0.8 ppm, and the crotonaldehyde content was 0.8 ppm. The potassium permanganate test value was 45 minutes. The 1,3-butylene glycol recovery rate in the product column F was 90%.

Examples 3 to 28

Under the conditions shown in Table 1 to Table 3, the dehydration column A, the high boiling substance removal column C, and the product column F were operated. In Examples 4 to 22 and 24 to 26, the entire amount of the distillate from the product column F was recycled to hydrogen reduction reactor. In Examples 23 and 28, the product column F was not used, and a distillate at the top of the dealkalization column E (demister was installed in a space above the charging position) was a 1,3-butylene glycol product. At this time, the concentration of the sodium hydroxide aqueous solution in the alkaline reactor D was set to 1.5 times, and the added amount of the sodium hydroxide aqueous solution was set to the half of the amount in Example 1. Thus, the increase in moisture due to alkaline treatment was avoided as much as possible. Note that, when the alkali concentration of the sodium hydroxide aqueous solution is too high, crystals precipitate, and thus that heating is performed to 40° C. or higher. In Table 3, the column “Bottom from product column F” of Examples 23 and 28 shows the composition and physical properties of the distillate at the top of the dealkalization column E. Note that, in Example 16, 8 parts of 10 parts of the bottom from the high boiling substance removal column was recycled to the hydrogenation step, and 2 parts thereof was discharged to the outside of the system. In addition, in Example 25. the pressure of the hydrogen addition reaction was reduced to 7 MPaG (gauge pressure). Therefore, the acetaldehyde content and crotonaldehyde content of the liquid feed into the dehydration column are high. In Example 26, the pressure of the hydrogen addition reaction was increased to 40 MPaG (gauge pressure) (the remaining conditions are the same as in Example 18).

Comparative Example 1

Eighty (80) parts of a 1,3-butylene glycol product was obtained from the bottom of the product column F by the same method as in Example 1 except that the reflux ratio in the dehydration column A was changed to 0.03, that the distilled amount was changed to 42 parts, that the reflux ratio of the high boiling substance removal column C was changed to 0.02, that the reflux ratio of the product column F was changed to 0.05, and that the distilled amount was changed to 20 parts. The obtained 1,3-hutylene glycol product had an initial boiling point of 193.1° C., a dry point of 210.2° C., a moisture concentration of 0.6 wt. %, an area ratio of 1,3-butylene glycol of 98.2%, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol of 0.3%, a total area ratio of impurity peaks having longer retention times than 1,3-butylene glycol of 1.5%, an acetaldehyde content of 5 ppm, and a crotonaldehyde content of 4 ppm. The potassium permanganate test value was 0 minutes. The 1,3-butylene glycol recovery rate in the product column F was 81%.

Comparative Example 2

Eighty (80) parts of a 1,3-butylene glycol product was obtained from the bottom of the product column F by the same method as in Example 1 except that the charged composition in the dehydration column A was changed, that the reflux ratio and the distilled amount were changed to 0.03 and 32 parts, respectively, that the reflux ratio of the high boiling substance removal column C was changed to 0.02, that the reflux ratio of the product column F was changed to 0.05, and that the distilled amount was changed to 20 parts. The obtained 1,3-butylene glycol product had an initial boiling point of 198.9° C., a dry point of 210.1° C., a moisture concentration of 0.4 wt. %, an area ratio of 1,3-butylene glycol of 98.5%, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol of 0.1″43, a total area ratio of impurity peaks having longer retention times than 1,3-butylene glycol of 1,4%, an acetaldehyde content of 4 ppm, and a crotonaldehyde content of 2 ppm. The potassium permanganate test value was 5 minutes. The 1,3-butylene glycol recovery rate in the product column F was 80%.

Comparative Example 3

Seventy (70) parts of a 1,3-butylene glycol product was obtained from the bottom of the product column F by the same method as in Example 1 except that the charged composition in the dehydration column A was changed, that the reflux ratio and the distilled amount were changed to 0.03 and 32 parts, respectively, that the reflux ratio of the high boiling substance removal column C was changed to 0.02, that the reflux ratio of the product column F was changed to 0.05, and that the distilled amount was changed to 30 parts. The obtained 1,3-butylene glycol product had an initial boiling point of 203.0° C., a dry point of 210.2° C., a moisture concentration of 0.2 wt. %, an area ratio of 1,3-butylene glycol of 98.4%, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol of 0.1%, a total area ratio of impurity peaks haying longer retention times than 1,3-butylene glycol of 1.5%, an acetaldehyde content of 2 ppm, and a crotonaidehyde content of 1.4 ppm. The potassium permanganate test value was 30 minutes. The 1,3-butylene glycol recovery rate in the product column F was 70%.

Comparative Example 4

Eighty (80) parts of a 1,3-butylene glycol product was obtained from the bottom of the product column F by the same method as in Example 1 except that the charged composition in the dehydration column A was changed, that the reflux ratio and the distilled amount were changed to 0.03 and 23 parts, respectively, that the reflux ratio of the high boiling substance removal column C was changed to 0.02, that the reflux ratio of the product column F was changed to 0.1, and that the distilled amount was changed to 20 parts. The obtained 1,3-butylene glycol product had an initial boiling point of 203.1° C., a dry point of 2095° C., a moisture concentration of 0.2 wt. %, an area ratio of 1,3-butylene glycol of 98.8%, a total area ratio of impurity peaks having shorter retention times than 1,3-butylene glycol of 0.1%, a total area ratio of impurity peaks having longer retention times than 1,3-hutylene glycol of 1,1%, an acetaldehyde content of 2 ppm, and a crotonaldehyde content of 1.4 ppm. The potassium permanganate test value was 30 minutes. The 1,3-butylene glycol recovery rate in the product column F was 80%.

Gas Chromatographic Analysis

A gas chromatographic analysis of the target 1,3-butylene glycol product was performed under the conditions below.

• Conditions for the gas chromatographic analysis:

Analytical Instrument: Shimadzu GC 2010

Analytical Column: column with dimethylpolysiloxane as a stationary phase (a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm) (Agilent J&W GC column—DB-1, available from Agilent Technologies Japan, Ltd.)

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C./min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. fur 18 minutes

Sample Introduction and Temperature: split sample introduction, 250° C.

Gas Flow Rate of Split and Carrier Gas: 23 mL/min, helium

Column Gas Flow Rate and Carrier Gas: 1 mL/min, helium

Detector and Temperature: a flame ionization detector (YID), 280° C.

Injection Sample: 0.2 μL of a 80 wt. % 1,3-butvlene glycol product aqueous solution

Measurement of Initial Boiling Point and Dry Point

Measurement was made according to the test method specified in the normal pressure distillation test method of HS K2254 “Petroleum products—distillation test method”.

Measurement of Moisture

Measurement was made using a Karl Fischer moisture measurement instrument.

GC-MS Analysis

Analytical Instrument: Agilent 6890A-GC/5973A-MSD

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2° C./min and maintaining for 2 minutes, and further heating to 230° C. at 10′C/min and maintaining at 230° C. for 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Ion source temperature: EI 230° C., CI 250° C.

Q Pole temperature: 150° C.

Sample: subjected to analysis as it was

Potassium Permanganate Test

In the present specification, the potassium permanganate test value (PMT) is a value measured in accordance with the visual colorimetric procedure of JIS K1351 (1993).

Considerations of Results

Results of the above comparative examples and examples are shown in Table 1 to Table 3.

TABLE 1
		Comparative	Comparative	Comparative	Comparative
		Example 1	Example 2	Example 3	Example 4	Example 1	Example 2	Example 3
Charge into	Part	100	100	←	100	100	←	←
dehydration	1,3 BG GC area %	56	66	←	76	56	←	←
column A	Water wt. %	40	30	←	20	40	←	←
	AD ppm	130	145	←	155	130	←	←
	CR ppm	89	110	←	117	89	←	←
	Low boiling substance	3	3	←	3	3	←	←
	GC area %
	High boiling substance	1	1	←	1	1	←	←
	GC area %
Reflux ratio of		0.03	0.03	←	0.03	0.05	10	10
dehydration column A
Distillation from	Part	42	32	←	23	43	43	43
dehydration column A
1,3 BG recover rate	%	99.3	99.8	←	99.8	99.6	99.9 or	99.6
							higher
Charge into high	Part	100	←	←	←	←	←	←
boiling substance	1,3 BG GC area %	96.5	97.2	←	97.8	97.3	97.9	←
removal column C	Water wt. %	1.3	1.2	←	0.8	1.0	0.2	←
	AD ppm	71	55	←	47	21	11	10
	CR ppm	49	40	←	29	20	12	10
	Low boiling substance	1.7	1.3	←	0.9	0.9	0.3	←
	GC area %
	High boiling substance	1.8	1.5	←	1.3	1.8	1.8	←
	GC area %
High boiling substance	Reflux ratio	0.02	0.02	0.02	0.02	0.05	0.05	0.05
removal column C	Distillation extraction	80	80	80	80	80	80	80
	part
	Bottom extraction part	20	20	20	20	20	20	20
	Recycle	Absent	Absent	Absent	Absent	Absent	Absent	Absent
	1,3 BG recovery rate %	81	81	81	81	82	81	81
Charge into	Part	100	100	←	100	100	←	100
product column F	1,3 BG GC area %	97.7	98.1	←	98.5	99.0	99.1	99.2
	Water wt %	1.4	1.3	←	0.8	1.1	0.3	0.3
	AD ppm	48	41	←	41	21	10	10
	CR ppm	21	13	←	14	10	7	7
	Low boiling substance	1.1	0.8	←	0.7	0.4	0.3	0.3
	GC area %
	High boiling substance	1.2	1.1	←	0.8	0.6	0.6	0.5
	GC area %
Reflux ratio of		0.05	0.05	0.05	0.1	0.5	0.5	10
product column F
Distillation from	Part	20	20	30	20	10	10	1
product column F	Recycle	Absent	Absent	Absent	Absent	Absent	Absent	Absent
Bottom (product)	Part	80	80	70	80	90	90	99
from product	1,3 BG GC area %	98.2	98.5	98.4	98.8	99.2	99.2	99.5
column F	Water wt. %	0.6	0.4	0.2	0.2	0.2	0.1	0.1
	AD ppm	5	4	2	2	1.6	0.8	1.1
	CR ppm	4	2	1.4	1.4	1.0	0.8	0.8
	Low boiling substance	0.3	0.1	0.1	0.1	0.08	0.06	0.05
	GC area %
	High boiling substance	1.5	1.4	1.5	1.1	0.7	0.7	0.5
	GC area %
	Initial boiling point	193.1	198.9	203.0	203.1	203.3	206.5	206.6
	° C.
	Dry point ° C.	210.2	210.1	210.2	209.5	209	208.9	208.7
	PMT min.	0	5	30	30	35	45	40
	1,3 BG recovery rate %	81	80	70	80	90	90	99 or
								higher
			Example 4	Example 5	Example 6	Example 7	Example 8	Example 9	Example 10
	Charge into	Part	100	←	←	←	←	←	←
	dehydration	1,3 BG GC area %	66	←	←	←	←	←	←
	column A	Water wt. %	30	←	←	←	←	←	←
		AD ppm	145	←	←	←	←	←	←
		CR ppm	110	←	←	←	←	←	←
		Low boiling substance	3	←	←	←	←	←	←
		GC area %
		High boiling substance	1	←	←	←	←	←	←
		GC area %
	Reflux ratio of		0.2	1	2	2	2	10	20
	dehydration column A
	Distillation from	Part	33	33	33	33	33	33	33
	dehydration column A
	1,3 BG recover rate	%	99.9	99.9 or	99.9 or	99.9 or	99.9 or	99.9 or	99.9 or
				higher	higher	higher	higher	higher	higher
	Charge into high	Part	←	←	←	←	←	←	←
	boiling substance	1,3 BG GC area %	98.2	98.3	98.3	98.3	98.3	98.3	98.4
	removal column C	Water wt. %	0.5	0.1	0.09	0.09	0.09	0.03	0.02
		AD ppm	41	19	14	14	14	6	4
		CR ppm	33	14	12	12	12	6	3
		Low boiling substance	0.3	0.2	0.2	0.2	0.2	0.2	0.1
		GC area %
		High boiling substance	1.5	1.5	1.5	1.5	1.5	1.5	1.5
		GC area %
	High boiling substance	Reflux ratio	0.05	0.05	0.05	0.05	0.05	0.05	0.05
	removal column C	Distillation extraction	80	80	80	80	80	80	80
		part
		Bottom extraction part	20	20	20	20	20	20	20
		Recycle	Absent	Absent	Absent	Absent	Absent	Absent	Absent
		1,3 BG recovery rate %	81	81	80	81	81	81	81
	Charge into	Part	100	←	←	←	←	←	←
	product column F	1,3 BG GC area %	99.2	99.3	97.8	99.3	99.3	99.3	99.4
		Water wt %	0.6	0.3	0.2	0.2	0.2	0.1	0.1
		AD ppm	31	18	11	12	10	3	2
		CR ppm	14	6	3	3	3	2	1
		Low boiling substance	0.3	0.2	0.2	0.2	0.2	0.2	0.1
		GC area %
		High boiling substance	0.5	0.5	2	0.5	0.5	0.5	0.5
		GC area %
	Reflux ratio of		0.5	0.5	2	100	500	2	2
	product column F
	Distillation from	Part	10	10	1	1	1	1	1
	product column F	Recycle	Present	Present	Present	Present	Present	Present	Present
	Bottom (product)	Part	90	90	99	99	99	99	99
	from product	1,3 BG GC area %	99.4	99.4	99.4	99.5	99.6	99.4	99.5
	column F	Water wt. %	0.2	0.1	0.1	0.003	0.002	0.05	0.04
		AD ppm	2	1.2	1.1	0.2	lower	0.3	lower
							than 0.2		than 0.2
		CR ppm	1.1	0.8	0.7	0.1	lower	0.2	lower
							than 0.1		than 0.1
		Low boiling substance	0.04	0.03	0.07	0.005	0.003	0.06	0.02
		GC area %
		High boiling substance	0.6	0.6	0.5	0.5	0.4	0.5	0.5
		GC area %
		Initial boiling point	203.5	206.6	206.8	208.2	208.4	207.3	207.2
		° C.
		Dry point ° C.	208.9	208.9	208.8	208.8	208.7	208.8	208.8
		PMT min.	35	40	40	55	55	45	55
		1,3 BG recovery rate %	99 or	99 or	99 or	99 or	99 or	99 or	99 or
			higher	higher	higher	higher	higher	higher	higher

TABLE 2
		Example 11	Example 12	Example 13	Example 14	Example 15	Example 16
Charge into	Part	100	←	←	100	←	←
dehydration	1,3 BG GC area %	76	←	←	66	←	←
column A	Water wt. %	20	←	←	30	←	←
	AD ppm	155	←	←	145	←	←
	CR ppm	117	←	←	110	←	←
	Low boiling substance	3	←	←	3	←	←
	GC area %
	High boiling substance	1	←	←	1	←	1.2
	GC area %
Reflux ratio of		0.2	1	20	1	1	1
dehydration column A
Distillation from	Part	23	23	23	33	33	33
dehydration column A
1,3 BG recovery rate	%	99.8	99.9 or	99.9 or	99.8	99.8	99.8
			higher	higher
Charge into high	Part	100	←	←	←	←	←
boiling substance	1,3 BG GC area %	98.4	98.5	98.6	98.3	←	98.1
removal column C	Water wt. %	0.1	0.09	0.01	0.1	←	0.1
	AD ppm	33	16	2	20	←	20
	CR ppm	22	9	1	12	←	13
	Low boiling substance	0.3	0.2	0.1	0.2	←	0.2
	GC area %
	High boiling substance	1.3	1.3	1.3	1.5	←	1.7
	GC area %
High boiling substance	Reflux ratio	0.05	0.05	0.05	0.1	0.5	0.5
removal column C	Distillation extraction	80	80	80	90	90	90
	part
	Bottom extraction part	20	20	20	10	10	10
	Recycle	Absent	Absent	Absent	Absent	Absent	Present
	1,3 BG recovery rate %	81	81	81	91	91	99.9 or
							higher
Charge into product	Part	100	←	←	100	100	100
column F	1,3 BG GC area %	99.3	99.4	99.5	99.4	99.6	99.5
	Water wt. %	0.3	0.1	0.1	0.3	0.3	0.3
	AD ppm	24	13	1	11	10	12
	CR ppm	15	6	1	6	7	7
	Low boiling substance	0.3	0.2	0.1	0.2	0.2	0.2
	GC area %
	High boiling substance	0.4	0.4	0.4	0.4	0.2	0.3
	GC area %
Reflux ratio of		1	2	2	1	1	1
product column F
Distillation from	Part	10	1	1	10	10	10
product column F	Recycle	Present	Present	Present	Present	Present	Present
Bottom (product)	Part	90	99	99	90	90	90
from product	1,3 BG GC area %	99.4	99.4	99.6	99.5	99.8	99.6
column F	Water wt. %	0.06	0.05	0.04	0.05	0.05	0.05
	AD ppm	1.7	1.1	lower	1.0	0.8	0.9
				than 0.2
	CR ppm	1.1	0.9	lower	0.8	0.7	0.7
				than 0.1
	Low boiling substance	0.09	0.07	0.05	0.02	0.02	0.02
	GC area %
	High boiling substance	0.5	0.5	0.4	0.5	0.2	0.4
	GC area %
	Initial boiling point	207.3	207.5	207.2	207.5	207.5	207.4
	° C.
	Dry point ° C.	208.9	208.9	208.8	208.8	208.6	208.8
	PMT min	35	40	55	40	45	40
	1,3 BG recovery rate %	90	99 or	99 or	99.9 or	99.9 or	99.9 or
			higher	higher	higher	higher	higher
			Example 17	Example 18	Example 19	Example 20	Example 21
	Charge into	Part	←	←	←	←	←
	dehydration	1,3 BG GC area %	←	←	←	←	←
	column A	Water wt. %	←	←	←	←	←
		AD ppm	←	←	←	←	←
		CR ppm	←	←	←	←	←
		Low boiling substance	←	←	←	←	←
		GC area %
		High boiling substance	←	←	←	←	←
		GC area %
	Reflux ratio of		1	1	1	1	1
	dehydration column A
	Distillation from	Part	33	33	33	33	33
	dehydration column A
	1,3 BG recovery rate	%	99.8	99.8	99.8	99.8	99.8
	Charge into high	Part	←	←	←	←	←
	boiling substance	1,3 BG GC area %	98.3	←	←	←	←
	removal column C	Water wt. %	0.1	←	←	←	←
		AD ppm	20	←	←	←	←
		CR ppm	12	←	←	←	←
		Low boiling substance	0.2	←	←	←	←
		GC area %
		High boiling substance	1.5	←	←	←	←
		GC area %
	High boiling substance	Reflux ratio	0.5	1	2	5	20
	removal column C	Distillation extraction	95	95	95	95	95
		part
		Bottom extraction part	5	5	5	5	5
		Recycle	Absent	Absent	Absent	Absent	Absent
		1,3 BG recovery rate %	96	96	96	96	96
	Charge into	Part	100	100	100	100	100
	product column F	1,3 BG GC area %	99.5	99.7	99.7	99.7	99.7
		Water wt. %	0.3	0.3	0.3	0.3	0.3
		AD ppm	11	10	9	9	8
		CR ppm	6	6	6	4	4
		Low boiling substance	0.2	0.2	0.2	0.2	0.2
		GC area %
		High boiling substance	0.3	0.1	0.09	0.07	0.06
		GC area %
	Reflux ratio of		1	1	1	1	1
	product column F
	Distillation from	Part	10	10	10	10	10
	product column F	Recycle	Present	Present	Present	Present	Present
	Bottom (product)	Part	90	90	90	90	90
	from product	1,3 BG GC area %	99.6	99.9	99.9	99.9	99.9
	column F	Water wt. %	0.05	0.05	0.05	0.05	0.05
		AD ppm	1.0	1.0	1.0	0.9	0.8
		CR ppm	0.5	0.5	0.4	0.4	0.3
		Low boiling substance	0.02	0.02	0.02	0.01	0.02
		GC area %
		High boiling substance	0.4	0.1	0.09	0.08	0.07
		GC area %
		Initial boiling point	207.5	207.4	207.5	207.6	207.6
		° C.
		Dry point ° C.	208.8	208.6	208.5	208.5	208.3
		PMT min	40	40	40	45	45
		1,3 BG recovery rate %	99.9 or	99.9 or	99.9 or	99.9 or	99.9 or
			higher	higher	higher	higher	higher

	TABLE 3
	Example 22	Example 23	Example 24	Example 25	Example 26	Example 27	Example 28
Charge into	Part	100	100	100	100	100	100	100
dehydration	1,3 BG GC area %	56	76	9	66	69	56	76
column A	Water wt. %	40	20	90	30	30	40	20
	AD ppm	130	155	85	970	3	130	155
	CR ppm	89	117	71	390	1	89	117
	Low boiling substance	3	3	0.4	3	1	3	3
	GC area %
	High boiling substance	1	1	0.1	1	1	1	1
	GC area %
Reflux ratio		0.05	20	2	0.2	1	0.03	20
of dehydration
column A
Distillation from	Part	42	23	91	33	32	42	23
dehydration column A
1,3 BG recovery rate	%	99.3	99.9 or	99.0	99.9 or	99.9 or	99.3	99.9 or
			higher		higher	higher		higher
Charge into high	Part	100	100	100	100	100	100	100
boiling substance	1,3 BG GC area %	97.3	98.6	97.4	98.1	99.1	96.5	98.6
removal column C	Water wt. %	1.0	0.01	3	0.5	0.1	1.3	0.01
	AD ppm	21	2	10	259	0.3	71	2
	CR ppm	20	1	4	139	0.2	49	1
	Low boiling substance	0.9	0.1	1.2	0.4	0.1	1.7	0.1
	GC area %
	High boiling substance	1.8	1.3	1.4	1.5	0.8	1.8	1.3
	GC area %
High boiling substance	Reflux ratio	0.1	1	1	0.05	1	0.02	0.1
removal column C	Distillation extraction	90	90	90	80	95	80	90
	part
	Bottom extraction part	10	10	10	20	5	20	10
	Recycle	Absent	Absent	Absent	Absent	Absent	Absent	Absent
	1,3 BG recovery rate %	92	91	91	81	96	81	91
Charge into	Part	100	—	100	100	100	100	—
product column F	1,3 BG GC area %	99.2	—	98.6	99.2	99.7	97.7	—
	Water wt. %	1	—	3.2	0.7	0.3	1.4	—
	AD ppm	19	—	8	223	0.3	48	—
	CR ppm	10	—	3	119	0.2	21	—
	Low boiling substance	0.4	—	0.9	0.3	0.1	1.1	—
	GC area %
	High boiling substance	0.4	—	0.5	0.5	0.2	1.2	—
	GC area %
Reflux ratio of		5	—	10	10	1	0.5	—
product column F
Distillation from	Part	10	—	10	10	10	20	—
product column F	Recycle	Present	—	Present	Present	Present	Absent	—
Bottom (product)	Part	90	—	90	90	90	80	—
from product	1,3 BG GC area %	99.4	99.5	99.4	99.4	99.8	98.2	99.4
column F	Water wt. %	0.09	0.09	0.1	0.02	0.05	0.2	0.09
	AD ppm	1.0	1.6	0.3	1.3	lower	1.5	1.6
						than 0.2
	CR ppm	0.3	1.1	0.2	1.2	lower	1.1	1.0
						than 0.1
	Low boiling substance	0.08	0.1	0.02	0.005	0.01	0.3	0.1
	GC area %
	High boiling substance	0.5	0.4	0.6	0.6	0.2	1.5	0.5
	GC area %
	Initial boiling point	207.0	206.9	206.7	207.9	207.6	203.4	206.9
	° C.
	Dry point ° C.	208.8	208.7	208.9	208.9	208.5	209.0	208.8
	PMT min	40	35	50	35	65	35	35
	1,3 BG recovery rate %	99.9 or	—	99.9 or	99 or	99.9 or	81	—
		higher		higher	higher	higher

From Comparative Examples 1 to 4, even when the composition charged into the dehydration column is changed, the product quality is not favorable, when the reflux ratio and the distilled amount of each distillation column are low. Comparative Examples 3 and 4 are cases in which the discharge amount of the distillate to the outside of the system of the product column is increased, or the content of water charged into the dehydration column is reduced, the initial boiling point and PMT are satisfied, but the dry point is high. In addition, the recovery rate of 1,3 BG is low, which is not economical. Note that acetaldehyde and crotonaldehyde seem less likely to separate in the dehydration column than usual, and that acetaldehyde and crotonaldehyde can be produced in the column.

It is clear from Comparative Example 1 and Examples 1 and 27 that, when the same composition charged into the dehydration column is used, and the reflux ratio of at least the product column, out of the dehydration column, the high boiling substance removal column and the product column, is set to the predetermined value or higher, the initial boiling point, the PMT, and the dry point can be satisfied at the same time, and that the 1,3 BG recovery rates in the dehydration column, the high boiling substance removal column, and the product column can he maintained at acceptably high values.

It is clear from Examples 1 and 2 that, by increasing the reflux ratio in the dehydration column to the predetermined value or higher, the content of water, acetaldehyde, and crotonaldehyde are reduced, and in particular, the initial boiling point and PMT are improved.

As demonstrated in Examples 2 and 3, when the reflux ratio in the product column is increased to the predetermined value or higher and the distilled amount is decreased, the increase in low boiling impurities due to the decrease in distilled amount is offset by the improvement in low boiling impurity separation due to the increase in reflux ratio, and the 1,3 BG recovery rate in the product column can be improved without changing the product quality.

It is clear from Comparative Example 2 and Example 4, and Comparative Example 4 and Example 11 that, when the same composition charged into the dehydration column is employed, and the distillation conditions of the dehydration column, the high boiling substance removal column, and the product column are set to within the ranges specified. in the present disclosure, quality is improved.

It is clear, from Examples 4 and 5, that the reflux ratio in the dehydration column is further increased, resulting in further improvement in initial boiling point and PMT.

From Examples 5 and 6, when the reflux ratio in the dehydration column is increased, and the distilled amount from the product column is lowered, the initial boiling point is reduced, but falling within the specification, and the 1,3 BG recovery rate is improved.

From Examples 6 to 8, when the reflux ratio in the product column is extremely improved, the initial boiling point and PMT are improved to the maximum. However, it is clear that the quality is almost not improved any more, when the reflux ratio is approximately 500.

It is clear from Examples 6, 9 and 10 that the initial boiling point and PMT are improved by increasing the reflux ratio in the dehydration column. However, when treatment with an alkali aqueous solution is performed between the dehydration column and the product column, moisture is increased in this step, and thus extreme water removal in the dehydration column does not make much sense. Thus, the reflux ratio in the dehydration column need not be very high. The alkaline reactor can also be used upstream of the dehydration column. Thus, in that case, effects are obtained even when the reflux ratio in the dehydration column is increased to a certain extent.

In Examples 11 to 13, the reflux ratio in the dehydration column is increased and the reflux and distilled amount in the product column are changed under the condition that the concentration of water in the liquid feed into the dehydration column is decreased. As described above, the respective effects and influences result in satisfactory initial boiling point and PMT.

It is clear from Examples 14 to 21 that increasing the reflux ratio in the high boiling substance removal column decreases the high boiling impurity content of the product, and improves the dry point. In addition, Example 16 is a case under a condition where 8 parts, out of 10 parts of the bottom from the high boiling substance removal column, is recycled to the hydrogenation step, and 2 parts thereof is discharged to the outside of the system, and thus the impurities are reduced in boiling point by hydrogen addition, This improves the 1,3 BG recovery rate in the high boiling substance removal column, but slightly increases the content of the high boiling substances in the product, and increases the dry point. However, it is clear that they fall within the specifications.

From Examples 1 and 22, it is clear that, even when the reflux ratio in the dehydration column is 0.05, a high-quality product can be maintained by increasing the reflux ratio in the product column.

From Comparative Examples 4 and Examples 13, 23 and 28, when the reflux ratio in the dehydration column is significantly increased, the content of acetaldehyde, crotonaldehyde and water can be reduced even without the product column, and the product can be commercialized. By performing the alkaline treatment before the distillation in the dehydration column, the concentration of water in the product can be further reduced.

Example 24 is an example where the concentration of water in the liquid feed into the dehydration column is extremely high. The content of moisture in the bottom from the dehydration column and the liquid feed into the high boiling substance removal column can be significantly increased, but the product quality can be maintained by adjusting the distilled amount and the reflux ratio in the product column.

It is clear from Examples 4 and 25 that, even when the acetaldehyde content and the crotonaldehyde content in the liquid feed into the dehydration column are significantly high, the distilled amount and reflux ratio in the product column are increased to remove acetaldehyde and crotonaldehyde, and thus that the product can maintain high quality.

It is clear from Example 26 that, when the pressure in the hydrogen addition reaction is increased, acetaldehyde, crotonaldehyde, and other reducing substances are made harmless by hydrogen addition, and the concentrations of acetaldehyde, crotonaldehyde, and other reducing substances, as well as other impurities such as trace acetals in the liquid feed into the dehydration column are reduced, the product quality can be maintained even when the reflux ratios and distilled amounts in the dehydration column, high boiling substance removal column, and the product column are relatively reduced.

Note that, in the 1,3-butylene glycol products obtained by known methods, there was no high-quality product having an initial boiling point of higher than 203° C. and a potassium permanganate test value of 30 minutes or longer, having an initial boiling point of higher than 203° C. and a dry point of 209° C. or lower, or having an initial boiling point of higher than 203° C., a dry point of 209° C. or lower, and a potassium permanganate test value of 30 minutes or longer.

As a summary of the above, configurations and variations of the present disclosure are described below.

[1] A method for manufacturing 1,3-butylene glycol, which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol,

the method including: a dehydration step of removing water by distillation; a high boiling substance removal step of removing a high boiling point component by distillation; and a product distillation step of obtaining purified 1,3-butylene glycol,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower (or 900 ppm or lower, 800 ppm or lower. 700 ppm or lower, 600 ppm or lower. 500 ppm or lower, 400 ppm or lower, 300 ppm or lower, 200 ppm or lower. 155 ppm or lower, 140 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or 1 ppm or lower) and a crotonaldehyde content of 400 ppm or lower (or 200 ppm or lower, 150 ppm or lower, 130 ppm or lower, 117 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or I ppm or lower) is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the product distillation step, a product column is used in which a 1,3-butylene glycol liquid feed having an acetaldehyde content of 500 ppm or lower (or 205 ppm or lower, 200 ppm or lower, 150 pprn or lower, 120 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, or lower than 2 ppm) and a crotonaldehyde content of 200 ppm or lower (or 205 ppm or lower, 200 ppm or lower, 150 ppm or lower, 120 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, or lower than 2 ppm) is distilled under a condition of a reflux ratio of higher than 0.1 (or 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, I or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 6 or higher, 7 or higher, 8 or higher, 9 or higher, 10 or higher, 20 or higher, 50 or higher, 400 or higher, or 500 or higher), a liquid concentrated with a low boiling point component is distilled off from above a feed plate, and 1,3-butylene glycol is extracted from below the feed plate.

[2] The method for manufacturing 1,3-butylene glycol according to [1], wherein in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-hutylene glycol is distilled under a condition of a reflux ratio of 0.02 or higher (or 0.03 or higher, 0.04 or higher, 0.05 or higher, 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.2 or higher, 1.5 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 10 or higher, or 20 or higher), 1,3-butylene glycol having further improved purity is distilled off from above a feed plate, and a liquid concentrated with a high boiling point component is extracted from below the feed plate.

[3] The method for manufacturing 1,3-butylene glycol according to [1] or [2], wherein the liquid feed into the product column has a 1.3-butylene glycol concentration of 90 GC area % or higher (or 92 GC area % or higher, 95 GC area % or higher, more preferably 97 GC area % or higher, 97.1 GC area % or higher, 97.2 GC area % or higher, 97.3 GC area % or higher, 97.4 GC area % or higher, 97.5 GC area % or higher, 97.6 GC area % or higher, 97.7 GC area % or higher, 97.8 GC area % or higher, 97.9 GC area % or higher, 98 GC area % or higher, 98.1 GC area % or higher, 98.2 GC area % or higher, 98.3 GC area % or higher, 98.4 GC area % or higher, 98.5 GC area % or higher, 98.6 GC area % or higher, 98.7 GC area % or higher, 98.8 GC area % or higher, 98.9 GC area % or higher, or 99 GC area % or higher), and a content of water in the liquid feed is 3 wt. % or lower (or 1.2 wt. % or lower, 1.1 wt. % or lower, 1.0 wt. % or lower, 0.95 wt. % or lower, 0.9 wt. % or lower, 0.8 wi.% or lower, 0.7 wt. % or lower, 0.6 wt. % or lower, 0.5 wt .% or lower. 0.4 wt. % or lower, 0.3 wt. % or lower, 0.2 wt. % or lower, or 0.1 wt. % or lower).

[4] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [3], wherein the liquid feed into the product column has a content of the low boiling point component other than water of 1.8 GC area % or lower (or 1.6 GC area % or lower, 1.4 GC area % or lower, 1.2 GC area % or lower, 1.1 GC area % or lower, 1 GC area % or lower, 0.9 GC area % or lower, 0.8 GC area % or lower, 0.7 GC area % or lower, 0.6 GC area % or lower, 0.5 GC area % or lower, 0.4 GC area % or lower, 0.3 GC area % or lower, 0.2 GC area % or lower, or 0.1 GC area % or lower).

[5] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [4], wherein the liquid feed into the product column the acetaldehyde content of 205 ppm or lower (or 200 ppm or lower, 150 ppm or lower, 120 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, or lower than 2 ppm), and the content of crotonaldehyde in the liquid feed is 110 ppm or lower (100 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or lower than 1 ppm).

[6] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [5], wherein the product columns have the number of theoretical plates of from 1 to 100. [7] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [6]. wherein at least a portion of a distillate from the product column is recycled to a step prior to the product distillation step, namely the dehydration step, the dealcoholization step, the low boiling substance removal step, or another step prior to these steps. [8] A method for manufacturing 1.3-butylene glycol, which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene

the method including:

a dehydration step of removing water by distillation; and a high boiling substance removal step of removing a high boiling point component by distillation,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower (or 900 ppm lower, 800 ppm lower, 700 ppm or lower, 600 ppm or lower, 500 ppm or lower, 400 ppm or lower, 300 ppm or lower, 200 ppm or lower, 155 ppm or lower, 140 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or 1 ppm or lower) and a crotonaldehyde content of 400 ppm or lower (or 200 ppm or lower, 150 ppm or lower, 130 ppm or lower, 117 ppm or lower, 100 ppm or lower, 90 ppm or lower, 80 ppm or lower, 70 ppm or lower, 60 ppm or lower, 50 ppm or lower, 40 ppm or lower, 30 ppm or lower, 20 ppm or lower, 10 ppm or lower, 5 ppm or lower, 3 ppm or lower, 2 ppm or lower, or 1 ppm or lower) is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of higher than 0.02 (or 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.2 or higher, 1.5 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 10 or higher, or 20 or higher), higher-purity 1,3-butylene glycol is distilled off from above a feed plate, and a liquid concentrated with the high boiling point component is extracted from below the feed plate.

[9] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [8], wherein the dehydration column has a reflux ratio of 0.03 or higher (or 0.04 or higher, 0.05 or higher, 0.06 or higher, 0.07 or higher, 0.08 or higher, 0.09 or higher, 0.1 or higher, 0.12 or higher, 0.14 or higher, 0.16 or higher, 0.18 or higher, 0.2 or higher, 0.22 or higher, 0.24 or higher, 0.26 or higher, 0.28 or higher, 0.3 or higher, 0.33 or higher, 0.36 or higher, 0.4 or higher, 0.45 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, 1.1 or higher, 1.2 or higher, 1.3 or higher, 1.4 or higher, 1.5 or higher, 1.6 or higher, 1.7 or higher, 1.8 or higher, 1.9 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, 6 or higher, 7 or higher, 8 or higher, 9 or higher, 10 or higher, 15 or higher, 20 or higher, 25 or higher, 30 or higher, or 40 or higher).

[10] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [9], wherein the crude reaction liquid containing 1,3-butylene glycol is a crude reaction liquid obtained by hydrogen reduction of an acetaldol.

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [10], further including an alkaline treatment step of treating a process stream containing 1,3-butylene glycol with a base.

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [11], further including a desalting step of removing a salt in a process stream containing 1,3-butylene

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [12], further including a dealcoholization step of removing a low boiling substance containing alcohols in a process stream containing 1,3-butylene glycol.

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [13], wherein the liquid feed into the dehydration column has a water content of 90 wt. % or lower (or 85 wt. % or lower, 80 wt. % or lower, 70 wt. % or lower, 60 wt. % or lower, 50 wt. % or lower, 40 wt. % or lower, 35 wt. % or lower, 30 wt. % or lower, or 25 wt.'/i, or lower).

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [14], wherein in the dehydration column and/or the high boiling substance removal column, the number of theoretical plates in at least one of these distillation columns is 1 to 100.

[16] The method for manufacturing 1,3-butylene glycol according to any one of [1] to [15], wherein the liquid feed into the high boiling substance removal column has a 1,3-butylene glycol concentration of 95% or higher (or 96% or higher, 97% or higher, 98% or higher, or 99% or higher).

The method for manufacturing 1,3-butylene glycol according to any one of [1] to [16], wherein the liquid feed into the high boiling substance removal column has a content of the high boiling point component of 4% or lower (or 3% or lower, 2% or lower, 1% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower. 0.2% or lower, 0.1% or lower, 0.05% or lower, or 0.01% or lower).

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

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

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

[21] The 1,3-butylene glycol product according to any one of [18] to [20], which satisfies at least one (preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, particularly preferably 5 or more, and especially all) condition(s) selected from the following six conditions:

(a) an area ratio of a 1,3-butylene glycol peak of 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) according to a gas chromatographic analysis performed under conditions set forth below,

(b) a total area ratio of peaks having shorter retention times than the 1,3-butylene glycol peak of lower than 0.3% (or 0.28% or lower, 0.25% or lower, 0.23% or lower, 0.2% or lower, 0.17% or lower, 0.15% or lower, 0.12% or lower, 0.1% or lower, 0.07% or lower, 0.04% or lower, 0.03% or lower, 0.02% or lower, 0.01% or lower, 0.007% or lower, 0.005% or lower, or 0.002% or lower) according to a gas chromatographic analysis performed under conditions set forth below,

(c) a total area ratio of peaks having longer retention times than the 1,3-butylene glycol peak of lower than 1.2% (or 1% or lower, 0.9% or lower, 0.8% or lower, 0.7% or lower, 0.6% or lower, 0.5% or lower, 0.4% or lower, 0.3% or lower, 0.2% or lower, or 0.1% or lower) according to a gas chromatographic analysis performed under conditions set forth below,

(d) a water content of lower than 0.4 wt. % (or 0.3 wt. % or lower, 0.2 wt. % or lower, 0.1 wt. % or lower, 0.07 wt. % or lower, 0.05 wt. % or lower, 0.03 wt. % or lower, 0.02 wt. % or lower, 0.01 wt. % or lower, or 0.005 wt. % or lower),

(e) an acetaldehyde content of lower than 2 ppm (or 1.8 ppm or lower, 1.7 ppm or lower, 1.5 ppm or lower, 1.4 ppn or lower, 1.3 ppm or lower, 1.2 ppm or lower, 1.1 ppm or lower, 1.0 ppm or lower, 0.9 ppm or lower, 0.8 ppm or lower, 0.7 ppm or lower, 0.6 ppm or lower, 0.5 ppm or lower, 0.3 ppm or lower, or 0.2 ppm or lower), and

(f) a crotonaldehyde content of lower than 1.2 ppm (or 1.0 ppm or lower, 0.9 ppm or lower, 0.8 ppm or lower, 0.7 ppm or lower, 0.6 ppm or lower, 0.5 ppm or lower, 0.4 ppm or lower, 0.3 ppm lower, 0.2 ppm or lower, or 0.1 ppm or lower),

• in which the conditions for the gas chromatographic analysis are as follows:

Analytical Column: a column with dimethylpolysiloxane as a stationary phase, having a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 1.0 μm

Heating Conditions: heating from 80° C. to 120° C. at 5° C./min, then heating again to 160° C. at 2″C./min and maintaining for 2 minutes, and further heating to 230° C. at 10° C./min and maintaining at 230° C. fur 18 minutes

Sample Introduction Temperature: 250° C.

Carrier Gas: helium

Column Gas Flow Rate: 1 mL/min

Detector and Detection Temperature: a flame ionization detector (FID) 280° C.

[22] A moisturizer comprising the 1,3-butylene glycol product described in any one of [18] to [21].

[23] The moisturizer according to [22], wherein a content of the 1,3-butylene glycol product described in any one of [18] to [21] is 10 wt. % or higher (or 30 wt. % or higher, 50 wt. % or higher, 80 wt. % or higher, or 90 wt. % or higher).

[24] A cosmetic product comprising the moisturizer described in [22] or [23].

[25] The cosmetic product according to [24], wherein a content of the 1,3-butylene glycol product described in any one of [18] to [21] is from 0.01 to 40 wt. % (or from 0.1 to 30 wt. %, from 0.2 to 20 wt. %, from 0.5 to 15 wt. %, or from 1 to 10 wt. %).

[26] The cosmetic product according to [24] or [25], which is a skin cosmetic product, a hair cosmetic product, a sunscreen cosmetic product, or a make-up cosmetic product.

INDUSTRIAL APPLICABILITY

The manufacturing method of the present disclosure can be used to industrially efficiently manufacture high-purity 1,3-butylene glycol having a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point, high-purity 1,3-butylene glycol having a very low content of low boiling point components, a high initial boiling point, a high potassium permanganate test value, and further high-purity 1,3-butylene glycol having a high potassium permanganate test value, a very low content of low boiling point components and high boiling point components, a high initial boiling point, and a low dry point.

REFERENCE SIGNS LIST

• A: Dehydration column
• B: Desalting column
• C: Distillation column for removing a high boiling point substance (high boiling substance removal column)
• D: Alkaline reactor
• E: Dealkalization column
• F: Product distillation column (product column)
• A-1, B-1, C-1, E-1, F-1: Condenser
• A-2, C-2, F-2: Reboiler
• X-1: Crude 1,3-butylene glycol
• X-2: Water (discharged water)
• X-3: A salt, a high boiling point substance, and a portion of 1.3-butylene glycol
• X-4: A high boiling point substance and a portion of 1,3-butylene glycol
• X-5: Sodium hydroxide, a high boiling point substance, and a portion of 1,3-butylene glycol
• X-6: A low boiling point substance and a portion of 1,3-butylene glycol
• Y: 1,3-butylene glycol product

Claims

1. A method for manufacturing 1,3-butylene glycol, which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol, the method comprising:

a dehydration step of removing water by distillation; a high boiling substance removal step of removing a high boiling point component by distillation; and a product distillation step of obtaining purified 1,3-butylene glycol,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the product distillation step, a product column is used in which a 1,3-butylene glycol liquid feed having an acetaldehyde content of 500 ppm or lower and a crotonaldehyde content of 200 ppm or lower is distilled under a condition of a reflux ratio of higher than 0.1, a liquid concentrated with a low boiling point component is distilled off from above a feed plate, and 1,3-butylene glycol is extracted from below the feed plate.

2. The method for manufacturing 1,3-butylene glycol according to claim 1, wherein in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of 0.02 or higher, 1,3-butylene glycol having further improved purity is distilled off from above a feed plate, and a liquid concentrated with a high boiling point component is extracted from below the feed plate.

3. The method for manufacturing 1,3-butylene glycol according to claim 1, wherein the liquid feed into the product column has a concentration of 1,3-butylene glycol of 90 GC area % or higher, and a content of water is 3 wt. % or lower.

4. A method for manufacturing 1,3-butylene glycol, which is a method for obtaining purified 1,3-butylene glycol from a crude reaction liquid containing 1,3-butylene glycol, the method comprising:

a dehydration step of removing water by distillation, and a high boiling substance removal step of removing a high boiling point component by distillation,

wherein in the dehydration step, a dehydration column is used in which a liquid feed containing 1,3-butylene glycol and water with an acetaldehyde content of 1000 ppm or lower and a crotonaldehyde content of 400 ppm or lower is distilled, and a liquid concentrated with a low boiling point component containing water is distilled off from above a feed plate, and

in the high boiling substance removal step, a high boiling substance removal column is used in which a liquid feed containing 1,3-butylene glycol is distilled under a condition of a reflux ratio of higher than 0.02, higher-purity 1,3-butylene glycol is distilled off from above a feed plate, and a liquid concentrated with the high boiling point component is extracted from below the feed plate.

5. The method for manufacturing 1,3-butylene glycol according to claim 1, wherein the dehydration column has a reflux ratio of 0.03 or higher.

6. The method for manufacturing 1,3-butylene glycol according to claim 1, wherein the crude reaction liquid containing 1,3-butylene glycol is a crude reaction liquid obtained by hydrogen reduction of an acetaldol.

7. The method for manufacturing 1,3-butylene glycol according to claim 1, further comprising an alkaline treatment step of treating a process stream containing 1,3-butylene glycol with a base.

8. The method for manufacturing 1,3-butylene glycol according to claim 1, further comprising a desalting step of removing a salt in a process stream containing 1,3-butylene glycol.

9. The method for manufacturing 1,3-butylene glycol according to claim 1, further comprising a dealcoholization step of removing a low boiling substance containing alcohols in a process stream containing 1,3-butylene glycol.

10. The method for manufacturing 1,3-butylene glycol according to claim 2, wherein the liquid feed into the product column has a concentration of 1,3-butylene glycol of 90 GC area % or higher, and a content of water is 3 wt. % or lower.

11. The method for manufacturing 1,3-butylene glycol according to claim 2, wherein the dehydration column has a reflux ratio of 0.03 or higher.

12. The method for manufacturing 1,3-butylene glycol according to claim 2, wherein the crude reaction liquid containing 1,3-butylene glycol is a crude reaction liquid obtained by hydrogen reduction of an acetaldol.

13. The method for manufacturing 1,3-butylene glycol according to claim 2, further comprising an alkaline treatment step of treating a process stream containing 1,3-butylene glycol with a base.

14. The method for manufacturing 1,3-butylene glycol according to claim 2, further comprising a desalting step of removing a salt in a process stream containing 1,3-butylene glycol.

15. The method for manufacturing 1,3-butylene glycol according to claim 2, further comprising a dealcoholization step of removing a low boiling substance containing alcohols in a process stream containing 1,3-butylene glycol.

16. The method for manufacturing 1,3-butylene glycol according to claim 4, wherein the dehydration column has a reflux ratio of 0.03 or higher.

17. The method for manufacturing 1,3-butylene glycol according to claim 4, wherein the crude reaction liquid containing 1,3-butylene glycol is a crude reaction liquid obtained by hydrogen reduction of an acetaldol.

18. The method for manufacturing 1,3-butylene glycol according to claim 4, further comprising an alkaline treatment step of treating a process stream containing 1,3-butylene glycol with a base.

19. The method for manufacturing 1,3-butylene glycol according to claim 4, further comprising a desalting step of removing a salt in a process stream containing 1,3-butylene glycol.

20. The method for manufacturing 1,3-butylene glycol according to claim 4, further comprising a dealcoholization step of removing a low boiling substance containing alcohols in a process stream containing 1,3-butylene glycol.