JP2015017087A - Method for producing diol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a diol by purifying a diol derived from a non-edible biomass resource in an industrial scale, which makes operations in a purification process safe and easy by preventing staining in a purification process and avoiding thermal runaway caused by saccharides, and excels in economical efficiency.SOLUTION: Provided is a method for producing a diol, comprising supplying a diol-containing liquid to a distillation column and separating components having boiling points higher than the boiling point of the diol contained in the diol-containing liquid by distillation, where the diol-containing liquid is controlled to contain saccharides and/or saccharide derivatives in a concentration of 0.1-1,500 ppm by mass; a heating temperature at a column bottom of the distillation column is set to 110°C or more; and a concentration of the saccharides and/or saccharide derivatives contained in the diol-containing liquid of the column bottom of the distillation column is controlled to 0.5-25 mass%.

Description

  The present invention relates to a method for producing a diol. More preferably, the present invention relates to a method for obtaining a purified diol such as high-purity purified 1,4-butanediol by purifying a diol-containing liquid such as crude 1,4-butanediol containing a saccharide derived from a non-edible raw material.

Diols are one of the most widely used raw materials for polymer chemicals and are widely used as raw material monomers for polyesters and polyurethanes. Conventionally, diols have been industrially produced from petroleum resources.
For example, 1,4-butanediol (hereinafter sometimes abbreviated as “1,4BG”) is a very useful substance used as a raw material for various solvents and derivatives. Similarly, it has been industrially produced using fossil fuels such as petroleum. As the production method, for example, acetoxylation is performed using butadiene as a raw material using acetic acid and oxygen to obtain diacetoxybutene as an intermediate, and hydrogenating and hydrolyzing the diacetoxybutene to obtain 1,4BG. A process for producing a crude hydrogenated product containing 1,4BG by using maleic acid, succinic acid, maleic anhydride and / or fumaric acid as raw materials; contacting with formaldehyde aqueous solution using acetylene as a raw material And a method for producing 1,4BG by hydrogenating butynediol obtained by the above method.

  However, in consideration of alternative resources and environmental impacts associated with oil depletion, in recent years, there has been an increasing demand for the production of diols derived from biomass resources.

Many methods for producing diols from biomass resources are known. For example, in the method of obtaining 1,3-propanediol from glucose (Patent Document 1), it is known that glucose as a raw material is brought into a small purification step. It has been.
In addition, for example, regarding polyester derived from biomass resources, a method of hydrogenating succinic acid obtained by succinic acid obtained from the raw material 1,4BG by a fermentation method of sugar (Patent Document 2), or fermenting biomass resources such as sugar A method for directly obtaining 1,4BG is known (Patent Document 3).

Special table 2007-502325 gazette JP 2009-0777719 A Special table 2010-521182

  However, for example, in the case of producing 1,4BG using a sugar and / or a sugar derivative as a raw material among biomass resources, the target product is obtained by fermenting them with a microbial cell, but sugar and / or There was a problem that the sugar derivative remained in the subsequent purification step, causing contamination within the purification process, and making temperature control difficult in a heating section such as a distillation tower. Among them, the above-mentioned problem is particularly remarkable for sugars and / or sugar derivatives derived from non-edible materials.

  The present invention has been made in view of the above-mentioned problems, and prevents contamination in the purification process derived from sugar and avoids thermal runaway when a diol derived from biomass resources is purified on an industrial scale. It is an object of the present invention to provide a method for producing a diol derived from a biomass resource which makes the operation of the purification process safe and easy by doing so and has good economic efficiency.

As a result of intensive studies to solve the above problems, the present inventors can solve the above problems by controlling the concentration of sugars brought into the purification process and adopting a specific purification process. We found that the phenomenon of temperature control in the heating section such as a distillation tower is also caused by the exotherm of components derived from saccharides, and this problem is also purified by controlling the concentration of saccharides brought into the purification process and by a specific purification process. As a result, the inventors have found that this can be solved, and have completed the present invention.
That is, the gist of the present invention is the following [1] to [7].

[1] In a method for producing a diol by supplying a diol-containing liquid to a distillation tower and separating a component having a higher boiling point than the diol in the diol-containing liquid by distillation, the diol-containing liquid is 0.1 to 1500. Containing sugar and / or sugar derivative in mass ppm, heating temperature at the bottom of the distillation column is 110 ° C. or higher, and concentration of sugar and / or sugar derivative in the diol-containing liquid at the bottom of the distillation column Is controlled to 0.5-25 mass%, The manufacturing method of diol characterized by the above-mentioned.

[2] The method for producing a diol according to [1], wherein the sugar and / or sugar derivative has 5 carbon atoms.

[3] The method for producing a diol according to [1] or [2], wherein the pH of the diol-containing liquid supplied to the distillation column is 4.5 or more.

[4] The method for producing a diol according to any one of [1] to [3], wherein the heating temperature at the bottom of the distillation column is 140 to 200 ° C.

[5]
The method for producing a diol according to any one of [1] to [4], wherein the heating source of the distillation column is substantially in contact with only the bottom liquid and is not in contact with the gas phase.

[6] The method for producing a diol according to any one of [1] to [5], wherein the diol is 1,4-butanediol.

  According to the present invention, when producing diols derived from biomass resources on an industrial scale, the concentration of saccharides mixed in the purification process is controlled and a specific purification process is used to avoid contamination in the purification process. In addition, it becomes possible to operate safely and easily by avoiding heat generation in the heating section, and even when using a biomass resource derived from a non-edible material, a diol derived from a biomass resource is produced with good economic efficiency. be able to.

Hereinafter, the present invention will be described in more detail. However, the description of each constituent element described below is a representative example of embodiments of the present invention, and the present invention is not limited to these.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Moreover, the lower limit value or the upper limit value in this specification means a range including the value of the lower limit value or the upper limit value.

  The purification process in the diol production method of the present invention is suitably applied to a 1,4BG-containing composition derived from non-edible biomass resources.

(1) Biomass resources Biomass resources are those in which solar light energy is converted into forms such as starch and cellulose by the photosynthetic action of plants, the bodies of animals that grow by eating plants, Includes products made from processed animals. Specifically, non-edible biomass resources such as wood, rice straw, corn cob, EFB, tapioca cass, bagasse, vegetable oil scum, waste paper and paper residue, marine product residue, livestock excrement, sewage sludge, food waste, etc. Edible biomass such as rice bran, old rice, corn, sugarcane, cassava, sago palm, okara, rice bran, buckwheat, soybeans, fats and oils. Among these, non-edible biomass resources are preferable, and non-edible biomass resources such as wood, rice straw, corn cob, EFB, tapioca cass, bagasse, and waste paper are preferred, and wood, rice straw, corn cob, EFB, bagasse, waste paper are more preferred. Most preferred are wood, corn cob, EFB, and bagasse.

  Biomass resources generally contain many alkali metals and alkaline earth metals such as elemental nitrogen, Na, K, Mg, and Ca.

The method of these biomass resources is not particularly limited. For example, the biomass resources are subjected to known pretreatment and saccharification processes such as chemical treatment with acids and alkalis, biological treatment using microorganisms, physical treatment, and the like. Induced to carbon source. The process often includes a refinement process by pretreatment such as chipping, scraping, or crushing biomass resources, and further includes a grinding process by a grinder or a mill as necessary.
The refined biomass resources are usually guided to a carbon source through further pretreatment and saccharification steps. Specific methods include chemical methods such as acid treatment with strong acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid, alkali treatment, ammonia freeze steaming explosion method, solvent extraction, supercritical fluid treatment, oxidizing agent treatment; Examples thereof include physical methods such as pulverization, steam explosion, microwave treatment, and electron beam irradiation; biological treatments such as hydrolysis by microorganisms and enzyme treatment.

  Carbon sources derived from the above biomass resources usually include hexoses such as glucose, mannose, galactose, fructose, sorbose, tagatose; pentoses such as arabinose, xylose, ribose, xylulose, ribulose; pentose, saccharose, starch, cellulose Disaccharides and polysaccharides such as butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, renolenic acid, monoctinic acid, arachidic acid, eicosene Fats and oils such as acid, arachidonic acid, behenic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, lignoceric acid, ceracolonic acid; polyalcohols such as glycerin, mannitol, xylitol, ribitol Sex sugar is used. Of these, hexoses such as glucose, fructose, xylose, and saccharose, pentose, and disaccharides are preferable, and glucose and xylose are particularly preferable. As a carbon source derived from a broader plant resource, cellulose which is a main component of paper is also preferable.

(2) Diol Although it does not specifically limit as diol manufactured by this invention, Aromatic hydrocarbon type diol, aliphatic hydrocarbon type diol, etc. are mentioned as a suitable thing. Preferred examples of the aliphatic hydrocarbon diol include linear aliphatic hydrocarbon diols, branched aliphatic hydrocarbon diols, and alicyclic hydrocarbon diols. Among these, linear aliphatic hydrocarbon diols are preferred, more preferred are linear aliphatic hydrocarbon diols having 2 to 10 carbon atoms in the main chain, and particularly preferred are main chain carbon atoms. It is a linear aliphatic hydrocarbon diol having 2 to 6 numbers. These diols may have a substituent, and the substituent preferably has a molecular weight of about 100 to 400.

Specific examples of the diol include, for example, ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3- Methyl-1,5-pentanediol, 1,10-decanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,6-hexanediol, decamethylene glycol, 1, Examples include 9-nonanediol and 1,4-cyclohexanedimethanol.
Of these, 1,3-butanediol, 1,4-butanediol (1,4BG), 1,3-propanediol, 1,6-hexanediol, and 1,10-decanediol are preferable. 1,4-butanediol is particularly preferred.

In the present invention, the crude diol-containing liquid containing the above diol may be produced directly from a carbon source such as glucose obtained from the above biomass resource by a fermentation method, or a dicarboxylic acid obtained by a fermentation method. The acid, dicarboxylic acid anhydride, or cyclic ether may be converted into a diol by a chemical reaction.
For example, when the diol is 1,4-butanediol, as a means for obtaining a crude diol-containing liquid, succinic acid and succinic anhydride obtained by fermentation from a carbon source such as glucose obtained from the above biomass resources , Succinic acid ester, maleic acid, maleic anhydride, maleic acid ester, tetrahydrofuran (THF), γ-butyrolactone, etc. may be produced by chemical synthesis, or from a carbon source such as glucose obtained from the above biomass resources 1,4-butanediol may be produced directly by fermentation, or 1,4-butanediol may be obtained from 1,3-butadiene obtained by fermentation from a carbon source such as glucose obtained from the above biomass resources. It may be manufactured. Among them, a method of directly producing 1,4-butanediol by a fermentation method and a method of obtaining 1,4-butanediol by hydrogenating succinic acid with a reduction catalyst are efficient and preferable.

When the above carbon source is used to obtain a dicarboxylic acid by a fermentation method by microbial conversion using a microorganism having a dicarboxylic acid-producing ability, and this is converted to a diol, the microorganism having the dicarboxylic acid-producing ability has a dicarboxylic acid-producing ability. The microorganism is not particularly limited as long as it is a microorganism, and examples thereof include enterobacteria such as Escherichia coli, Bacillus bacteria, and coryneform bacteria. Among these, it is preferable to use an aerobic microorganism, a facultative anaerobic microorganism, or a microaerobic microorganism.
Examples of the aerobic microorganism include Coryneform Bacterium, Bacillus genus bacteria, Rhizobium genus bacteria, Arthrobacter genus bacteria, Mycobacterium genus bacteria, Rhodococcus genus bacteria, Examples include Rhodococcus bacteria, Nocardia bacteria, and Streptomyces bacteria, with coryneform bacteria being more preferred.
The coryneform bacterium is not particularly limited as long as it is classified as such, and examples thereof include bacteria belonging to the genus Corynebacterium, bacteria belonging to the genus Brevibacterium, and bacteria belonging to the genus Arthrobacter. Among these, those belonging to the genus Corynebacterium or Brevibacterium are preferred, and Corynebacterium glutamicum, Brevibacterium flavum, Brevibacterium ammoniagenes or Brevibacterium ammoniagenes More preferred is a bacterium classified as a lactofermentum (Brevacterium lactofermentum).
When a succinic acid-producing bacterium is used as a microorganism having dicarboxylic acid-producing ability, it is preferable to use a strain having enhanced pyruvate carboxylase activity and reduced lactate dehydrogenase activity.

  On the other hand, Escherichia coli, Corynebacterium, yeast, etc., in which the genes are modified can be used for the method for directly producing 1,4BG. For example, 1,4BG can be biologically produced from an organic fermentation medium by the method described in JP-T-2010-521182.

(3) Purification method of diol When obtaining diol directly by fermentation from a carbon source such as glucose obtained from the above biomass resources, the diol-containing composition after separating and removing cells and salt from the fermentation medium contains a large amount. Of water may be included. The method for removing the water is not particularly limited, but it is preferably removed by continuous or batch distillation. As the distillation column used for distilling off the water, it is preferable to use a distillation column having 2 or more and 100 or less theoretical plates, more preferably 5 or more and 50 or less. The reflux ratio is arbitrary, but is preferably 0.01 or more and 100 or less, more preferably 0.1 or more and 50 or less, and particularly preferably 0.2 or more and 20 or less.

  The reboiler which is the heating part of the distillation column is not particularly limited, but is preferably a forced circulation type reboiler or a thin film flow down type reboiler. In particular, a shorter residence time at the site of contact with the heating source at the bottom of the column is preferable from the viewpoint of avoiding contamination, and a structure in which the heating source does not contact the gas phase part or a structure in which the contact amount is minimized is preferable.

  The top pressure of this distillation column is preferably 1 kPa or more and 200 kPa or less as an absolute pressure, more preferably 2 kPa or more and 100 kPa or less, and particularly preferably 5 kPa or more and 50 kPa or less. The lower the pressure at the top of the column, the lower the temperature inside the column and avoiding saccharide-derived dirt, but if it is too low, cooling becomes inefficient. Moreover, the capacity | capacitance of tower | column itself can be reduced, so that tower | column top pressure is high, but when too high, tower | floor bottom temperature will rise and it will become easy to produce | generate dirt and an impurity.

  The temperature in this distillation is determined by the composition and pressure, but the temperature at the bottom of the column that is the highest is preferably 110 ° C. or higher and 200 ° C. or lower, more preferably 120 ° C. or higher and 190 ° C. or lower, Preferably they are 140 degreeC or more and 180 degrees C or less. When the temperature at the bottom of this distillation column is lower than the above lower limit, the temperature at the top of the column is lowered and the cooling cost is increased. If it is higher than the above upper limit, the biomass resources-derived components, particularly dirt and impurities due to side reactions of sugars increase. The temperature at the top of the column is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 40 ° C. or higher and 80 ° C. or lower, and particularly preferably 40 ° C. or higher and 60 ° C. or lower. When the column top temperature is lower than the above lower limit, the cooling cost increases, and when it is higher than the above upper limit, dirt and side reactions in the column increase.

  Further, the preferred distribution at the top of this distillation column (= (column top distillate flow rate / feed flow rate) × 100) varies depending on the water concentration in the diol-containing composition, but is preferably 2 to 40%. More preferably, it is 5 to 30%, particularly preferably 8 to 25%. If the distribution at the top of the column is too high, the loss of diol increases, and if it is too low, moisture and lightly boiling acid are brought into the diol-containing liquid that is sent to the next step.

  In this distillation column, the pH at the bottom of the column is preferably controlled to 4 to 9, and particularly preferably 5 to 8. If the pH is too low, dirt and dehydration by-products increase in the distillation tower, making operation difficult. If the pH is too high, side reactions such as high boiling are promoted.

  When dicarboxylic acid, dicarboxylic acid anhydride or cyclic ether obtained by fermentation is converted to diol by chemical reaction, water may be removed before chemical reaction, or dehydration may be performed after conversion to diol. Good.

In the present invention, a diol-containing composition (hereinafter referred to as "crude diol-containing liquid") is supplied to a distillation column to separate and purify components having a higher boiling point than the diol by treating the diol-containing composition treated as necessary by the above-described operation. It is sometimes referred to as “liquid”.
In the following, according to the present invention, a distillation column that distills a crude diol-containing liquid and separates components having a boiling point higher than that of the diol may be referred to as “distillation column (a)”.

In the present invention, such a crude diol-containing liquid is distilled in the distillation column (a), and a purified diol having a high purity is obtained through a step of removing components having a higher boiling point than the diol in the crude diol-containing liquid. .
In the following description, unless otherwise specified, the distillation operation in the distillation column may be either a batch type or a continuous type, and a continuous type distillation operation is preferable from the viewpoint of productivity. Although single distillation or multistage distillation may be used, multistage distillation is preferable from the viewpoint of separation performance, and either a plate or a regular and / or irregular packing can be used for the distillation column.

  In the present invention, the crude diol-containing liquid is supplied to the distillation tower (a), and the distillation is carried out by controlling the heating temperature at the tower bottom to 110 ° C. or higher and the saccharide concentration in the diol-containing liquid at the tower bottom to 0.5 to 25% by mass. By performing, a component having a higher boiling point than the diol in the crude diol-containing liquid (high-boiling component) is removed, and a diol from which the high-boiling component has been removed is obtained as a column top distillate of the distillation column (a). In the distillation column (a), components having a boiling point higher than that of a diol peculiar to a fermentation method such as saccharides and decomposition products thereof, and other nitrogen-containing components derived from amino acids and proteins are removed.

  According to the present invention in which distillation is performed under such distillation conditions, it is possible to stably obtain a high-quality diol while preventing contamination and thermal runaway in the purification process. In order to more reliably avoid thermal runaway due to dirt and heat generation in the purification process, it is preferable to reduce the concentration of saccharides in the crude diol-containing liquid that is supplied to the distillation column (a) for purification.

  In the present invention, the saccharide contained in the crude diol-containing liquid to be purified by supplying to the distillation column (a) is a saccharide derived from the biomass resources and derivatives thereof (hereinafter collectively referred to as “saccharide”). And a compound having a polyhydroxyketone or polyhydroxyaldehyde skeleton. That is, it represents an organic compound containing two or more molecules of a hydroxy group and one or more molecules of an aldehyde group or a ketone group. Specific examples include hexoses such as glucose, mannose, galactose, fructose, sorbose and tagatose, pentoses such as arabinose, xylose, ribose, xylulose and ribulose, and disaccharides or polysaccharides such as sucrose, raffinose and starch. . The sugar derivative in the present invention is a sugar alcohol, deoxy sugar, a sugar dehydrogenated product obtained by dehydrogenating a sugar, a sugar dehydrated product obtained by dehydrating a sugar, and the sugar is chemically converted, It is a compound derived through processes such as pyrolysis and fermentation. Specifically, for example, deoxy sugars such as deoxyribose, fucose, fucose, rhamnose, quinobose, and paratose, sugar alcohols such as sorbitol, mannitol, and xylitol, sugar dehydrogenated substances such as gluconolactone, levoglucosan, 4-deoxy- Single-molecule dehydrates such as 3-hexosulose are listed.

  In the present invention, the value of the saccharide concentration in the crude diol-containing liquid before purification that is supplied to the distillation column (a) and purified is 0.1 to 1500 ppm by mass, preferably 1 to 1200 ppm by mass, and particularly preferably. Is 10 to 800 ppm by mass. By making the saccharide within this concentration range, it is possible not only to avoid dirt and thermal runaway in the heating section, but also to control the color tone of the diol obtained and the concentration of carbonyl impurities and dehydrated products. A lower saccharide concentration value can reduce the purification cost of the present invention, which is economically desirable. However, in order to lower the saccharide concentration of the crude diol-containing liquid before purification to less than 0.1 mass ppm, the fermentation time is reduced. There are problems such as a decrease in efficiency due to extension and a decrease in selectivity due to sequential reaction of fermentation products.

  The method of reducing the value of the saccharide concentration in the crude diol-containing liquid is not particularly limited, but a method of consuming saccharides in the fermentation process, a method of performing purification operations such as membrane separation and crystallization after fermentation, hydrocracking, Or the method of performing thermal decomposition etc. are mentioned.

  The water concentration of the crude diol-containing liquid is not particularly limited, but usually the upper limit is 20% by mass or less, preferably 18% by mass or less, and more preferably 15% by mass or less. On the other hand, the lower limit is usually 0.01% by mass or more, preferably 0.02% by mass or more, and more preferably 0.03% by mass or more. If the water content of the crude diol-containing liquid is too high, the steam recovery temperature from the top of the tower is lowered in the subsequent distillation tower as described later, which is not preferable. For example, in the distillation column (a), the temperature at the top of the column decreases, and steam cannot be recovered from the cooling condenser. Therefore, when the water concentration of the crude diol-containing liquid is higher than the above upper limit, it is preferable to introduce the water into the distillation column (a) after removing water by repeating distillation. On the other hand, in order to make the water concentration of the crude diol-containing liquid excessively low, the distillation load for removing water becomes large, which is not preferable. Furthermore, the dehydration reaction of saccharides tends to proceed, resulting in a risk of contamination and heat generation, which is not preferable.

  Moreover, it is preferable that pH of a crude diol containing liquid is 4.5 or more, More preferably, it is 5.0-9.0, Most preferably, it is 5.2-8.0. The low pH of the crude diol-containing liquid means that the pH of the bottom liquid of the distillation column for removing water is low, and there are problems of dirt and dehydration by-products as described above. Moreover, the risk of thermal runaway in the distillation column (a) can be reduced as the pH of the crude diol-containing liquid is higher. On the other hand, as described above, when the pH of the crude diol-containing liquid is too high, that is, when the pH of the bottom liquid of the distillation column for removing water is too high, side reactions such as high boiling are promoted.

  The means for adjusting the pH of the bottom liquid is not particularly limited, but to reduce the pH, organic acids such as acetic acid, propionic acid, butyric acid, lactic acid, methanesulfonic acid, paratoluenesulfonic acid, sulfuric acid, nitric acid, phosphoric acid In order to increase the pH, a method of adding an inorganic acid such as cation exchange resin or the like, a method of thermally decomposing sugars in the column bottom liquid and acidifying, a method of adding an acidic liquid in other steps, etc. The addition of weakly basic anion exchange resins such as acrylic and styrenic polyamine types, strong basic anion exchange resins with trimethylammonium groups and dimethylethanolammonium groups, lithium hydroxide, sodium hydroxide, Alkali metal hydroxides such as potassium hydroxide, alkaline earth metal hydroxides such as barium hydroxide and calcium hydroxide, sodium carbonate, potassium carbonate, charcoal Carbonate such as sodium hydrogen, sodium methoxide, sodium ethoxide, sodium butoxide, potassium methoxide, potassium ethoxide, metal alkoxide of potassium butoxide, methylamine, etheramine, ethylamine, trimethylamine, triethylamine, tributylamine, triethanolamine N, N-diisopropylethylamine, piperidine, piperazine, morpholine, quinuclidine, 1,4-diazabicyclooctane, pyridine, 4-dimethylaminopyridine, ethylenediamine, tetramethylethylenediamine, hexamethylenediamine, aniline, catecholamine, phenethylamine, 1 , 8-bis (dimethylamino) naphthalene (proton sponge) or other organic amine addition method, basicity of other steps And a method of adding a liquid.

  Further, the diol concentration of the crude diol-containing liquid is not particularly limited, but usually, the lower limit is 80% by mass or more, preferably 82% by mass or more, and more preferably 85% by mass or more. On the other hand, the upper limit is usually 99.5% by mass or less, preferably 99.0% by mass or less, and more preferably 98.0% by mass or less.

As the distillation column (a), it is preferable to use a distillation column having 3 or more and 100 or less theoretical plates, and more preferably 5 or more and 50 or less.
The reflux ratio is arbitrary, but is preferably 0.01 or more and 100 or less, more preferably 0.1 or more and 50 or less. A reflux ratio of 0.2 or more and 20 or less is particularly preferable.
Although the reboiler which is a heating part of the distillation column (a) is not particularly limited, it is preferably a forced circulation reboiler or a thin film falling reboiler. In particular, a shorter residence time at the site of contact with the heating source at the bottom of the column is preferable from the viewpoint of avoiding contamination, and a structure in which the heating source does not contact the gas phase part or a structure in which the contact amount is minimized is preferable. It is also possible to recover steam from the cooling condenser at the top of the distillation column (a).

  The top pressure of the distillation column (a) is preferably 1 kPa or more and 200 kPa or less as an absolute pressure, more preferably 2 kPa or more and 100 kPa or less, and particularly preferably 5 kPa or more and 50 kPa or less. The lower the pressure at the top of the tower, the lower the temperature in the tower, and it can be avoided that new impurities are generated from components derived from biomass resources such as amino acids and sugars. Moreover, the higher the tower top pressure, the more suitable for steam recovery from the tower top part, and the capacity of the tower itself can be reduced.

  In the present invention, the column bottom temperature (heating temperature at the column bottom) of the distillation column (a) is 110 ° C. or higher, and preferably 220 ° C. or lower. The tower bottom temperature is more preferably 130 ° C. or more and 210 ° C. or less, and particularly preferably 140 ° C. or more and 200 ° C. or less. When the bottom temperature of the distillation column (a) is not less than the above lower limit, steam recovery from the top of the column is appropriate, and if it is not more than the above upper limit, the production of by-products is suppressed and the risk of thermal runaway is reduced. be able to.

  Further, the residence time of the bottom liquid in the distillation column (a) is preferably 10 minutes or more and 100 hours or less, more preferably 30 minutes or more and 50 hours or less, and further preferably 1 hour or more and 30 hours or less. Especially preferably, it is 1 hour or more and 20 hours or less. A longer residence time is preferable in terms of not requiring an excessive extraction flow rate and ease of liquid level control. However, if it is excessively long, self-reactive substances such as radicals are likely to be generated, leading to thermal runaway. Risk increases.

  The concentration of the saccharide in the crude diol-containing liquid at the bottom of the distillation column (a) is controlled to 0.5 to 25% by mass in order to avoid thermal runaway. The saccharide concentration is preferably controlled to 20% by mass or less, more preferably 15% by mass or less. The higher this concentration, the greater the risk of thermal runaway and the amount of heat generated during thermal runaway. In addition, since C5 saccharides such as xylose have a higher risk of thermal runaway than C6 saccharides such as glucose, stricter concentration management is required. When using biomass resources derived from non-edible raw materials, a large effect can be obtained by the purification according to the present invention.

  It is preferable that the distillate obtained in the distillation column (a) that removes components having a boiling point higher than that of the diol is further distilled in the next distillation step. The bottoms containing a higher boiling point component than the diol may be discarded as it is, but the distillation column (hereinafter referred to as “distillation column (b)”) that is further purified to recover the highly purified diol. Is preferred).

  By keeping the diol concentration in the bottoms of the distillation column (a) high, the dirt rate at the bottom of the distillation column (a) can be greatly reduced. This is because concentration of an excessively high-boiling component promotes precipitation of a solid component derived from saccharides. Therefore, the bottoms extracted from the bottom of the distillation column (a) preferably contains diol to some extent, preferably the diol concentration in the bottoms is 30 to 99.5% by mass, and more preferably Is from 50 to 99.0% by mass, particularly preferably from 55 to 98.5% by mass. In addition, the column top distribution ratio (= (column top distillate flow rate / feed flow rate) × 100) in the distillation column (a) is preferably 50 to 98%, more preferably 60 to 95%, particularly preferably. 70-90%.

From the viewpoint that the diol contained in the component having a higher boiling point than the diol separated in the distillation column (a) can be further recovered by the distillation column (b), in the present invention, the bottoms of the distillation column (a) are removed. Further distillation in the distillation column (b) is preferred.
In the distillation column (b), a component having a higher boiling point than that of the diol separated in the distillation column (a), that is, the bottoms of the distillation column (a) is distilled to separate and recover the diol.

The distillation column (b) is preferably a distillation column having 2 or more and 50 or less theoretical plates, more preferably 5 or more and 30 or less.
The reflux ratio is arbitrary, but is preferably 0.01 or more and 100 or less, more preferably 0.1 or more and 50 or less. A reflux ratio of 0.2 or more and 20 or less is particularly preferable.
Vapor can also be recovered from the cooling condenser at the top of the distillation column (b).

  The reboiler which is a heating part of the distillation column (b) is not particularly limited, but is preferably a forced circulation type reboiler or a thin film flow down type reboiler. In particular, a shorter residence time at the site of contact with the heating source at the bottom of the column is preferable from the viewpoint of avoiding contamination, and a structure in which the heating source does not contact the gas phase part or a structure in which the contact amount is minimized is preferable. Unlike the distillation column (a), only the distillation column (b) is used when the inside of the distillation column (b) becomes dirty even during continuous operation of the diol production process including the distillation column (a). It is also possible to temporarily stop and perform bypass operation during that time.

  The top pressure of the distillation column (b) is preferably from 0.1 kPa to 100 kPa as an absolute pressure, more preferably from 0.2 kPa to 50 kPa, and particularly preferably from 1 kPa to 20 kPa. The lower the pressure at the top of the column, the lower the temperature inside the column, so that thermal runaway at the bottom of the column, blockage due to the progress of polymerization, and gas generation due to decomposition of sugar can be avoided. Moreover, the capacity | capacitance of tower itself can be reduced, so that tower top pressure is high.

  The temperature at the bottom of the distillation column (b) is 110 ° C. or higher, and preferably 220 ° C. or lower. More preferably, it is 140 degreeC or more and 200 degrees C or less, Most preferably, it is 160 degreeC or more and 190 degrees C or less. If the bottom temperature of the distillation column (b) is lower than the lower limit, recovery is difficult when steam is recovered from the top of the column, and if it is higher than the upper limit, it causes contamination and increases the risk of thermal runaway. Become.

  The residence time of the bottom liquid in the distillation column (b) is preferably 10 minutes or more and 100 hours or less, more preferably 30 minutes or more and 50 hours or less, and further preferably 1 hour or more and 30 hours or less. Especially preferably, it is 1 hour or more and 20 hours or less. A longer residence time is preferable in terms of not requiring an excessive extraction flow rate and ease of liquid level control. However, if it is excessively long, self-reactive substances such as radicals are likely to be generated, leading to thermal runaway. Risk increases.

  The saccharide concentration at the bottom of the distillation column (b) is preferably controlled to 0.5 to 25% by mass in order to avoid thermal runaway. The saccharide concentration is more preferably controlled to 20% by mass or less, more preferably 15% by mass or less. Further, the lower limit of the saccharide concentration is more preferably 1% by mass or more, and still more preferably 5% by mass or more. The higher the sugar concentration, the greater the risk of thermal runaway and the amount of heat generated during thermal runaway, but the less diol is lost along with the high-boiling components. In addition, since C5 saccharides such as xylose have a higher risk of thermal runaway than C6 saccharides such as glucose, stricter concentration management is required.

  Since the saccharide concentration at the bottom of the distillation column (b) is concentrated more than the saccharide concentration at the bottom of the distillation column (a), the top pressure of the distillation column (b) is set lower than that of the distillation column (a). It is desirable to reduce the risk of dirt and thermal runaway at the bottom of the tower by lowering the tower bottom temperature.

  The pH at the bottom of the distillation column (b) is preferably controlled to 4 to 9, particularly preferably 5 to 8. If the pH is too low, dirt and dehydration by-products increase in the distillation column (b), which makes operation difficult and increases the risk of thermal runaway. If the pH is too high, side reactions such as high boiling are promoted.

  The distillate containing the diol separated in the distillation column (b) is preferably circulated to the distillation column (a) to recover the diol. The bottoms containing more of the high boiling point component concentrated in the distillation column (b) is discarded as it is, but it is preferable to recover the heat by incineration.

  By the above distillation operation, it is possible to separate and discharge most of the high boiling point components in the crude diol-containing liquid out of the system, but by setting the theoretical stage of the distillation column (b) within the above range, More high boiling components can be further discarded. Further, it is possible to discharge a large amount of nitrogen and sulfur in the high boiling point component.

  Impurities in the diol-containing composition produced by the fermentation method contain components containing chlorine, sulfur, and the like, which becomes a factor for lowering the pH of the diol-containing liquid. For this reason, it is preferable to perform a base treatment step (hereinafter sometimes referred to as “step (c)”) for removing these chlorine and sulfur components. This base treatment may be performed on the crude diol-containing liquid supplied to the distillation column (a) after the dehydration treatment or on the crude diol-containing liquid before the dehydration treatment. Moreover, you may carry out with respect to the diol containing distillate from which the high boiling component was removed by the distillation column (a).

  As the base that can be used in this step (c), a base that dissolves in a diol-containing liquid such as various amines may be used. Specific examples of such a base include trimethylamine, triethylamine, tripropylamine, Tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, tridecanylamine, triphenylamine, diphenylmethylamine, diphenylethylamine, diphenylbutylamine, dimethylphenylamine, diethylphenylamine, dibutylphenylamine, tributylamine Cyclopentylamine, tricyclohexylamine, tricycloheptylamine, pyridine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] -7-undecane, 1, -Diazabicyclo [4.3.0] -5-nonene, 2,5-diazabicyclo [2.2.1] heptane, etc. are preferable, and tributylamine, tripentylamine, trihexylamine, triheptylamine, tri Octylamine, dimethylphenylamine, tricyclohexylamine, pyridine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] -7-undecane, 1,5-diazabicyclo [ 4.3.0] -5-nonene, particularly preferably trioctylamine, pyridine, 1,8-diazabicyclo [5.4.0] -7-undecane, 1,4-diazabicyclo [2.2.2]. ] Octane.

  However, in the step (c), it is preferable to use a solid base that can be easily separated after contact with the diol-containing liquid or the crude diol-containing liquid rather than the base dissolved in the diol-containing liquid or the crude diol-containing liquid. The solid base is effective and usable as long as it is a solid compound having basicity, but preferably an anion exchange resin, a triazine ring-containing compound having an amino group or a substituted amino group, polyamide, and Examples include at least one selected from inorganic bases.

  The anion exchange resin as the solid base is not particularly limited, and a commercially available product can be used. Further, the type of structure is not particularly limited, and any of gel type, MR type (macroreticular) type, porous type and high porous type can be used, and in particular, it has a quaternary ammonium salt as a functional group. Styrenic or acrylic resins are preferred.

  The triazine ring-containing compound having an amino group or a substituted amino group is preferably a melamine resin or CTU guanamine (3,9-bis [2- (3,5-diamino-2,4-6-triazaphenyl)]. Ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane), CMTU guanamine (3,9-bis [1- (3,5-diamino-2,4,6-triazaphenyl) Methyl] -2,4,8,10-tetraoxaspiro [5,5] undecane). Two or more of these may be used in combination.

  Examples of the polyamide include nylon 6, nylon 12, nylon 4/6, nylon 6/6, nylon 6/10, nylon 6/12 and the like. Two or more of these may be used in combination.

Examples of the inorganic base include alkali or alkaline earth metal compounds. Specifically, metal oxides such as CaO and MgO, metal hydroxides such as Ca (OH) ₂ and Mg (OH) ₂ , Na ₂ CO ₂ , metal carbonates such as K ₂ CO ₂ , CaCO ₂ , and MgCO _2, and metal inorganic acid salts such as borates and phosphates thereof. These may be used in combination of two or more. .

  Among the above solid bases, a triazine ring-containing compound having an amino group or a substituted amino group and an anion exchange resin are particularly preferred, and an anion exchange resin is particularly preferred.

  The temperature at the time of contacting the base and the diol-containing liquid or the crude diol-containing liquid in the step (c) is preferably -20 to 200 ° C, more preferably 0 to 120 ° C, and particularly preferably 30 to 100 ° C. . If this temperature is too low, a special device such as a freezer is required and process competitiveness is lowered. If it is too high, deterioration of the solid base proceeds.

  The contact time is preferably 1 minute to 100 hours, more preferably 10 minutes to 20 hours, and particularly preferably 20 minutes to 10 hours. If the contact time is too short, it is difficult to sufficiently remove chlorine and sulfur components. If the contact time is too long, the process becomes inefficient.

  Moreover, the solid base brought into contact with the diol-containing liquid or the crude diol-containing liquid can be used in a mass ratio of 0.01 to 100 with respect to the diol-containing liquid or the crude diol-containing liquid. It is 1-20, Most preferably, it is 0.2-10.

  The contact method between the diol-containing liquid or the crude diol-containing liquid and the solid base may be either a batch type or a continuous type, but a continuous flow type is particularly preferable from the viewpoint of easy operation.

  The diol-containing liquid obtained through the distillation column (a), the distillation column (b), and optionally the step (c) can be used as a product as it is, but the following distillation column (hereinafter referred to as “distillation column” (D) "may be referred to)).

  In the distillation column (d), the diol-containing liquid obtained through the distillation column (a), the distillation column (b), and optionally the step (c) is distilled to produce purified diol from the top or side fraction. Extract as Further, in addition to the above steps, the distillation may be performed in a distillation column (d) after passing through a distillation column or a hydrogenation reaction step for separating light boiling components. When a purified diol is obtained as a side distillation of the distillation column (d), a diol containing a small amount of light-boiling components such as a light-boiling carboxylic acid, water, and a dehydration product of the diol is distilled from the top of the distillation column (d). The diol-containing liquid containing a small amount of high-boiling components is discharged from the bottom of the tower. It is preferable that the column top distillate and the column bottom distillate of these distillation columns (d) are collected individually or mixed and recovered in the previous step.

  As the distillation column (d), as long as the distillation column can satisfy these quality items, distillation can be performed at an arbitrary number of stages and conditions to obtain a purified diol. d) is preferably a distillation column having 5 or more and 100 or less theoretical plates, more preferably 10 or more and 50 or less.

  In the case of obtaining purified diol as a side distillation, the side distillation extraction position is preferably located above the raw material liquid feed stage, and the interval between the raw material liquid feed stage and the side distillation extraction position is two or more as the theoretical stage, Preferably, it is 3 or more stages, for example, 3 to 20 stages. The number of theoretical plates from the top of the column to the side distillation position is preferably 1 or more and 50 or less, more preferably 2 or more and 20 or less, and particularly preferably 3 or more and 10 or less. .

  The reflux ratio of the distillation column (d) is arbitrary, but is preferably 0.01 or more and 100 or less, more preferably 0.1 or more and 50 or less. A reflux ratio of 0.2 or more and 20 or less is particularly preferable.

  Moreover, the reboiler which is the heating part of the distillation column (d) is not particularly limited, but is preferably a forced circulation reboiler or a thin-film reboiler. In particular, a shorter residence time at the site of contact with the heating source at the bottom of the column is preferable from the viewpoint of avoiding contamination, and a structure in which the heating source does not contact the gas phase part or a structure in which the contact amount is minimized is preferable. Steam can also be recovered from the cooling condenser at the top of the distillation column (d).

  The top pressure of the distillation column (d) is preferably 1 kPa or more and 200 kPa or less as an absolute pressure, more preferably 2 kPa or more and 100 kPa or less, and particularly preferably 2 kPa or more and 50 kPa or less. The lower the pressure at the top of the column, the lower the temperature in the column, and the generation of new impurities due to the reaction of impurities in the column can be avoided. On the other hand, the higher the tower top pressure, the better the steam recovery from the tower top site, and the capacity of the tower itself can be further reduced.

The temperature in the distillation column (d) is determined by the composition and pressure, but the temperature at the highest column bottom is preferably 120 ° C. or higher and 200 ° C. or lower, more preferably 130 ° C. or higher and 180 ° C. or lower. Particularly preferably, it is 140 ° C. or higher and 170 ° C. or lower. Moreover, the tower | column top part used as the lowest temperature is 40 degreeC or more, More preferably, it is 50 degreeC or more, Especially preferably, it is 60 degreeC or more. If the tower bottom temperature is too high, the diol and a small amount of impurities react at the tower bottom, and the quality of the purified diol may deteriorate. If the bottom temperature is too low, a high vacuum is required, which is economically undesirable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.

In the following, the analysis of 1,4-butanediol (1,4BG) and tetrahydrofuran (THF) was carried out using a gas chromatographic analyzer “Shimadzu GC-2014 type” manufactured by Shimadzu Corporation, and “PEG-20M column manufactured by GL Science Co., Ltd.” (Polarity) "and performed by gas chromatography.
The color tone of the distillate was evaluated by measuring ultraviolet (UV) absorbance at a wavelength of 260 nm using UV-2400 manufactured by Shimadzu Corporation. Note that pure water was used for the blank measurement. The higher the UV absorbance, the worse the color tone.
The pH was measured by using “TOA-DKKHM-25G” manufactured by Toa DKK Co., Ltd. and dissolving 10 g of a sample in a mixed solution (pH 7) of isopropyl alcohol and water (10: 6 by volume).
For differential scanning calorimetry (DSC), a “DSC1” manufactured by METTLER TOLEDO was used, and a sealed cell (manufactured by Switzerland) “F-40” manufactured by SUS316L was used. The measurement temperature range was 25 ° C. to 450 ° C. and the temperature was increased in a nitrogen atmosphere at 10 ° C./min.

[Distillation separation of high boiling point components in distillation column (a)]
[Example 1]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 1000 ppm by mass to prepare a crude 1,4BG-containing liquid. From this crude 1,4BG-containing liquid, a high-boiling component containing glucose was distilled ( Removed in a). The crude 1,4BG-containing liquid had a water concentration of 0.03% by mass and a pH of 4.64.
As the distillation column (a), an Oldershaw distillation column having 30 theoretical plates (the heating source substantially contacts only the bottom liquid and does not involve contact with the gas phase portion) was used. The pressure at the top of the column is 15.7 kPa, the reflux ratio is 1.0, the column top temperature is 176 ° C., the column bottom temperature is 184 ° C., the distribution at the column top is 86%, and the residence time is 10 hours. The crude 1,4BG-containing liquid was continuously introduced at a flow rate of 86 mL / hr at 10 positions from the top, continuously distilled at 74 mL / hr from the top of the column, and continuously extracted at 12 mL / hr from the bottom. At this time, the glucose concentration in the 1,4BG-containing liquid at the bottom of the distillation column (a) was controlled to 0.5% by mass. The 1,4BG concentration in the bottoms was 99.0% by mass.
As a result, continuous operation for 200 hours could be carried out stably without producing solids. Moreover, the color tone of the distillate and the concentration of THF as impurities were also good.

[Example 2]
Distillation purification was carried out in the same manner as in Example 1 except that an aqueous solution obtained by saccharifying bagasse so that the glucose concentration was 1000 ppm by mass was added to commercially available 1,4BG to prepare a crude 1,4BG-containing solution. At this time, the glucose concentration in the bottom liquid of the distillation column (a) was 1.1% by mass, and as a result of continuous operation for 200 hours, no solid matter was produced. Moreover, although the color tone of the distillate was slightly worse than that of Example 1, the THF concentration was lower than that of Example 1.

[Comparative Example 1]
Distillation purification was performed in the same manner as in Example 1 except that glucose was added to commercially available 1,4BG so that the glucose concentration was 2000 mass ppm to prepare a crude 1,4BG-containing liquid. At this time, the glucose concentration in the bottom liquid of the distillation column (a) was 1.0 mass%, and as a result of continuous operation for 200 hr, 2 mg of solid matter adhered to the bottom of the column. Further, the color tone and THF concentration of the distillate were worse than those of Example 1.

[Comparative Example 2]
Prepare a crude 1,4BG-containing liquid by adding glucose to commercially available 1,4BG so that the glucose concentration is 4000 ppm by mass, so that the heating source is in addition to the tower bottom liquid and comes into contact with the gas phase. Distillation purification was performed in the same manner as in Example 1 except that distillation was performed. The tower bottom temperature at this time was 186 ° C., the glucose concentration in the tower bottom liquid was 1.8% by mass, and as a result of continuous operation for 200 hours, 235 mg of solid matter adhered to the tower bottom. Further, the color tone and THF concentration of the distillate were worse than those of Example 1.

  The above results are summarized in Table 1.

[Thermal evaluation of sugar-containing 1,4BG solution]
[Reference Example 1]
As a result of conducting differential scanning calorimetry of commercially available 1,4BG, no exotherm was detected.

[Reference Example 2]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 1% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetry of this saccharide-containing 1,4BG solution, no exotherm was detected.

[Reference Example 3]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 8% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, an exotherm was detected at 248 ° C., and the exotherm was 27 J / g.

[Reference Example 4]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 244 ° C., and the heat generation amount was 43 J / g.

[Reference Example 5]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 20% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 243 ° C., and the heat generation amount was 51 J / g.

[Reference Example 6]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 25% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, an exotherm was detected at 237 ° C., and the exotherm was 57 J / g.

  The above results are summarized in Table 2.

[Reference Example 7]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 1% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 230 ° C., and the heat generation amount was 44 J / g.

[Reference Example 8]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 8% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 223 ° C., and the heat generation amount was 73 J / g.

[Reference Example 9]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 10% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 227 ° C., and the heat generation amount was 84 J / g.

[Reference Example 10]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, an exotherm was detected at 219 ° C., and the exotherm was 88 J / g.

[Reference Example 11]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 20% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, an exotherm was detected at 227 ° C., and the exotherm was 89 J / g.

[Reference Example 12]
Xylose was added to commercially available 1,4BG so that the xylose concentration was 25% by mass to prepare a saccharide-containing 1,4BG solution. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 209 ° C., and the heat generation amount was 82 J / g.

  The above results are summarized in Table 3.

[Reference Example 13]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution, and paratoluenesulfonic acid was added so that the pH was 3.5. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 215 ° C., and the heat generation amount was 60 J / g.

[Reference Example 14]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution, and paratoluenesulfonic acid was added so that the pH was 4.5. As a result of differential scanning calorimetric analysis of the saccharide-containing 1,4BG solution, heat generation was detected at 221 ° C., and the heat generation amount was 53 J / g.

[Reference Example 15]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution, and paratoluenesulfonic acid was added so that the pH was 5.5. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 220 ° C., and the heat generation amount was 55 J / g.

[Reference Example 16]
Glucose was added to commercially available 1,4BG so that the glucose concentration was 15% by mass to prepare a saccharide-containing 1,4BG solution, and sodium hydroxide was added so that the pH was 6.5. As a result of differential scanning calorimetric analysis of this saccharide-containing 1,4BG solution, heat generation was detected at 222 ° C., and the heat generation amount was 48 J / g.

  The above results are summarized in Table 4.

From Table 1, it can be seen that the bottom of the distillation tower becomes dirty as the saccharide concentration in the crude 1,4BG-containing liquid increases. Further, it can be seen that the amount of dirt attached increases when the gas phase part is heated.
In addition, it can be seen that the color tone and impurity concentration of the distillate (diol) can be improved by controlling the saccharide concentration, and it is particularly effective in the case of using biomass resources derived from specific edible raw materials in reducing impurities.

From Tables 2 and 3, it can be seen that the higher the saccharide concentration in the saccharide-containing 1,4BG solution, the lower the heat generation start temperature and the more the heat generation amount. In particular, when the saccharide concentration is increased to 25% by mass, a heat source temperature of 100 ° C. or less is required to obtain a margin of 100 ° C., which is generally required from the heat generation start temperature of differential scanning calorimetry, and saccharide-containing 1,4BG Distillation of the solution becomes impossible. Since differential scanning calorimetry is not a measurement under adiabatic conditions, it is generally known that heat is generated at a temperature lower than the heat generation start temperature detected in the reference example in an actual scale. Since most diols are difficult to distill below 100 ° C., management of the sugar concentration is important according to the present invention.
Furthermore, it can be seen from Table 4 that as the pH of the 1,4BG solution is higher, the calorific value can be reduced.
As mentioned above, the risk of thermal runaway in the distillation tower can be reduced by controlling the saccharide concentration in the 1,4BG-containing liquid below a certain concentration, using a heat source according to the saccharide concentration, and adjusting the pH. It can be seen that contamination at the bottom of the tower can be reduced and the quality of the diol obtained can be improved.

Claims (6)

  In the method of supplying a diol-containing liquid to a distillation tower and separating a component having a higher boiling point than the diol in the diol-containing liquid by distillation to produce a diol, the diol-containing liquid is 0.1 to 1500 ppm by mass. It contains sugar and / or a sugar derivative, the heating temperature at the bottom of the distillation column is 110 ° C. or higher, and the sugar and / or sugar derivative concentration in the diol-containing liquid at the bottom of the distillation column is 0. A method for producing a diol, which is controlled to 5 to 25% by mass.   The method for producing a diol according to claim 1, wherein the sugar and / or sugar derivative has 5 carbon atoms.   The method for producing a diol according to claim 1 or 2, wherein the pH of the diol-containing liquid supplied to the distillation column is 4.5 or more.   The method for producing a diol according to any one of claims 1 to 3, wherein the heating temperature at the bottom of the distillation column is 140 to 200 ° C.   The method for producing a diol according to any one of claims 1 to 4, wherein the heating source of the distillation column is substantially in contact with only the bottom liquid and is not accompanied by contact with the gas phase.   The said diol is 1, 4- butanediol, The manufacturing method of the diol of any one of Claims 1-5 characterized by the above-mentioned.