Method for purifying polyhydric alcohol

Abstract

A method for purifying polyhydric alcohol, according to the present invention, as a method with high efficiency and removal capacity for decolorizing and deodorizing polyhydric alcohol, comprises the steps of preparing a mixed solution containing polyhydric alcohol, and performing concentration, fractional distillation, water supply, stripping treatment, and distillation, whereby off-color and off-odor substances contained in the polyhydric alcohol can be efficiently removed.

Description

Method for refining polyhydric alcohols

[0001] The present invention relates to a method for purifying polyhydric alcohol.

[0002] Polyhydric alcohols are compounds containing multiple hydroxyl groups (-OH) within a single molecule. Dihydric alcohols are sometimes called glycols, while trihydric alcohols are sometimes called glycerol. Polyhydric alcohols are used as hydrophilic, protic solvents and are also applied in diverse fields, such as various cosmetic compositions, pharmaceutical additives, and automotive antifreeze.

[0003] For example, 2,3-butanediol and 1,3-propanediol are widely used as raw materials or additives for electronic material additives, pesticides, cosmetics, and beauty products, and their potential for use in the pharmaceutical field is also increasing due to their chiral properties.

[0004] 2,3-Butanediol and 1,3-propanediol can be produced chemically, and can also be synthesized through bio-based fermentation processes to produce 2,3-butanediol with specific optical activity.

[0005] Colorless and odorless polyhydric alcohols need to be produced for applications in cosmetics, medicine, and other fields. However, trace amounts of impurities that are not removed during the separation and purification process can cause the polyhydric alcohol solution to appear off-white and have an off-odor.

[0006] Additionally, when polyalcohols are synthesized using bio-based processes such as microorganisms and strains, they may contain a number of unusual and off-flavoring substances derived from proteins, biomass, etc.

[0007] Accordingly, a purification process capable of efficiently removing unusual and off-flavor substances from polyalcohols is required.

[0008] The present invention provides a method for decolorizing and deodorizing polyhydric alcohols with high efficiency.

[0009] The method for purifying polyhydric alcohol according to the present invention for achieving the above-described task is as follows:

[0010] (a) a step of preparing a fermentation liquid containing a desired polyalcohol;

[0011] (b) a step of obtaining a first purified liquid by first purifying the fermented liquid in a pretreatment manner;

[0012] (c) a step of diluting the first purified solution resulting from step (b) to obtain a diluted solution of the first purified solution;

[0013] (d) a step of hydrogenating the diluted solution of the first purified solution, which is the result of step (c), to obtain a second purified solution;

[0014] (e) a step of mixing the second purified liquid resulting from the step (d) with an additive and water to obtain an additive mixture;

[0015] (f) a step of obtaining a third purified liquid by concentrating the additive mixture resulting from step (e) and then distilling it to recover the polyalcohol;

[0016] (g) a step of obtaining a fourth purified liquid by purifying the third purified liquid, which is the result of the step (f), a fourth time using a water stripping method;

[0017] (h) a step of obtaining a fifth purified liquid by mixing water and an adsorbent in the fourth purified liquid resulting from the step (g) and then performing an adsorption treatment to remove impurities; and

[0018] (i) A step of filtering out the adsorbent from the fifth purified liquid, which is the result of the step (h), and then performing a sixth purification using distillation to obtain a sixth purified liquid may be included. The pretreatment of the step (b) may include one or more of a filtration process, an electrodialysis process, and an ion exchange process.

[0019] The additive of step (e) above may include a neutralizing agent.

[0020] The neutralizing agent of step (e) may include carbonate and metal hydroxide.

[0021] The neutralizing agent of the above step (e) may be mixed in an amount of 0.1 to 1 part by weight relative to 100 parts by weight of the second purified liquid.

[0022] The distillation conditions of the above step (f) can be set in a pressure range of 10 to 60 mbar and a temperature range of 20 to 130°C.

[0023] The distillation in step (f) above is performed through a distillation column or a single distillation, and may include removing water.

[0024] The adsorbent of the above step (h) may include at least one of activated carbon, zeolite, and ion exchange resin.

[0025] The distillation conditions of step (i) above can be set in a pressure range of 10 to 60 mbar and a temperature range of 20 to 130°C.

[0026] The distillation in step (i) above may be performed as an atmospheric distillation process to remove water.

[0027] The distillation of step (i) may further include a distillation process performed in one or more distillation columns to remove molecules having a boiling point higher than the boiling point of the target polyhydric alcohol; and a distillation process performed in one or more distillation columns to remove molecules having a boiling point lower than the boiling point of the target polyhydric alcohol.

[0028] The desired polyhydric alcohol may include 2,3-butanediol or 1,3-propanediol.

[0029] According to the present invention, the polyalcohol purification process provided in the present invention can efficiently remove unusual color and odor substances contained in the polyalcohol.

[0030] According to the present invention, the purification method of the present invention can obtain a colorless and odorless polyhydric alcohol from which foreign matter and odorous substances are completely removed by including a hydrogenation process.

[0031] For example, the present invention produces substantially colorless and odorless 2,3-butanediol from a 2,3-butanediol synthetic solution containing a number of impurities, colors, and odors by being bio-synthesized.

[0032] In addition, the present invention produces substantially colorless and odorless 1,3-propanediol from a 1,3-propanediol synthetic solution containing a number of impurities, colors, and odorous substances by being synthesized based on biomaterials.

[0033] Figure 1 is a flowchart showing a method for purifying polyalcohol according to embodiments of the present invention.

[0034] FIG. 2 is a conceptual diagram illustrating a purification system for polyalcohol according to embodiments of the present invention.

[0035] Figure 3 is a gas chromatography analysis graph of the purified 2,3-butanediol solution obtained in Example 1 and Comparative Example 1 of the present invention.

[0036] The present invention provides a detailed description of the polyhydric alcohol purification method. While preferred embodiments of the present invention are presented herein, these embodiments are merely illustrative and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various modifications and variations to the embodiments are possible within the scope and spirit of the present invention, and it is also understood that such modifications and variations fall within the scope of the appended claims.

[0037] FIG. 1 is a flowchart illustrating a method for purifying polyhydric alcohol according to embodiments of the present invention, and FIG. 2 is a conceptual diagram illustrating a system for purifying polyhydric alcohol according to embodiments of the present invention.

[0038] Hereinafter, a method for purifying polyalcohol will be described with reference to FIGS. 1 and 2.

[0039]

[0040] Referring to Figure 1, the method for purifying polyalcohol according to the present invention is as follows:

[0041] (a) a step of preparing a fermentation liquid containing a desired polyalcohol;

[0042] (b) a step of obtaining a first purified liquid by first purifying the fermented liquid in a pretreatment manner;

[0043] (c) a step of diluting the first purified solution resulting from step (b) to obtain a diluted solution of the first purified solution;

[0044] (d) a step of hydrogenating the diluted solution of the first purified solution, which is the result of step (c), to obtain a second purified solution;

[0045] (e) a step of mixing the second purified liquid resulting from the step (d) with an additive and water to obtain an additive mixture;

[0046] (f) a step of obtaining a third purified liquid by concentrating the additive mixture resulting from step (e) and then distilling it to recover the polyalcohol;

[0047] (g) a step of obtaining a fourth purified liquid by purifying the third purified liquid, which is the result of the step (f), a fourth time using a water stripping method;

[0048] (h) a step of obtaining a fifth purified liquid by mixing water and an adsorbent in the fourth purified liquid resulting from the step (g) and then performing an adsorption treatment to remove impurities; and

[0049] (i) a step of filtering out the adsorbent from the fifth purified liquid, which is the result of the step (h), and then performing a sixth purification using a distillation method to obtain a sixth purified liquid;

[0050]

[0051] (a) Step

[0052] First, the polyhydric alcohol purification method of the present invention includes a step of preparing a fermentation liquid containing the desired polyhydric alcohol.

[0053] Here, the desired polyhydric alcohol may be a polyhydric alcohol collected after a separation process for the polyhydric alcohol fermentation liquid. The polyhydric alcohol fermentation liquid may be produced by fermenting a bio-raw material using a strain. The bio-raw material may be a grain (kernel), a wood-based material, and / or a starch-based material. For example, a starch-based material may be used as the bio-raw material, and examples of the starch-based material may include starch-containing grains such as corn and rye, cassava, raw sugar, glucose, etc., and a material containing sugar derived from biomass may also be used.

[0054] As the above strain, for example, a microorganism capable of producing a diol-containing fermentation product can be utilized without any particular limitation. For example, Klebsiella, Bacillus, Serratia, Enterobacter, Clostridium, yeast, E. coli, etc. can be utilized as the above microorganism.

[0055] In the present invention, the bio-raw material and strain can be selected by considering the target polyhydric alcohol. According to one embodiment of the present invention, the target polyhydric alcohol can be 2,3-butanediol. In one embodiment, the 2,3-butanediol can include its optical isomers, 2R,3R-butanediol, 2S,3S-butanediol, 2R,3S-butanediol, 2S,3R-butanediol, and preferably 2R,3S-butanediol.

[0056] For example, cassava may be used as the bio-raw material and Klebsiella may be used as the strain for producing 2,3-butanediol. For example, Klebsiella oxytoca, Klebsiella pneumoniae, etc. may be used as the strain, and Klebsiella oxytoca is preferred.

[0057] The above-mentioned polyalcohol fermentation solution can be produced through a saccharification process and a fermentation process. For example, the bio-based raw material can be ground, mixed in a liquid such as fresh water, and a saccharification enzyme can be added to react with the bio-based raw material to produce a saccharification solution. The saccharification enzyme can include, for example, an amylase-based enzyme.

[0058] Thereafter, the strain may be added to the saccharification solution to prepare a fermentation broth. The fermentation broth may contain, for example, 2,3-butanediol, 1,3-propanediol, 1,6-hexanediol as the desired polyhydric alcohol, which is a diol, and may contain, for example, 2,3-butanediol, but may further contain, in addition to these, monoalcohols and other glycols (for example, ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, etc.). In addition, the fermentation broth may contain various inorganic salts, organic acids, and impurities causing off-color or off-odor (off-color or off-odor substances), such as bio-byproducts derived from the strain or its metabolites.

[0059] Non-limiting examples of the above impurities include, but are not limited to, acetaldehyde, acetoin, diacetyl, furfural, methanol, methyl ethyl ketone, dioxolane, pyrazine, and the like.

[0060]

[0061] (b) Step

[0062] Next, step (b) is performed to obtain a first purified liquid by pretreating the fermentation liquid obtained in step (a). Step (b) can be performed to separate the desired polyhydric alcohol and remove some impurities.

[0063] The pretreatment in step (b) above may include one or more of a filtration process, an electrodialysis process, and an ion exchange process, and for example, may be performed sequentially including all of the filtration process, the electrodialysis process, and the ion exchange process.

[0064] The above filtration process is a process of removing solids in the fermentation liquid using a membrane filter, and microfiltration and ultrafiltration can be performed sequentially.

[0065] The above microfiltration (MF) can be performed using a polymer or ceramic membrane having a pore size in the range of about 0.05 to 10 μm to remove large particles and microorganisms that do not dissolve in the fermentation liquid.

[0066] The above ultrafiltration (UF) can be performed using an organic polymer membrane or organic hollow fiber laminate having a pore size in the range of about 0.001 to 0.1 μm to block solutes (polymers, proteins, colloids, etc.) having a molecular weight cut off (MWCO) of 1,000 to 100,000 Da, while allowing water or low-molecular-weight solutes to pass through.

[0067] The above electrodialysis process is a process of dividing an electrodialysis device into compartments by placing a cation exchange membrane and an anion exchange membrane between an anode and a cathode, and supplying direct current using the anode and cathode to purify a salt component.

[0068] For example, Na + , K+ Monovalent cations such as Ca 2+ , Mg 2+ Divalent cations such as these cannot pass through the anion exchange membrane and accumulate in the compartment, allowing the filtrate, from which inorganic salts such as metal salts have been removed, to be diluted and discharged in a desalinated state.

[0069] The above ion exchange process is a process of removing remaining weak salts or weak ionic organic acids by sequentially passing the solution through a cation exchange resin column and an anion exchange resin column. The ion exchanger used in the ion exchange treatment may include ion exchange resins, ion exchange fibers, gel ion exchangers, liquid ion exchangers, zeolites, carbonaceous ion exchangers, ion exchange resins, etc.

[0070] According to one example, the pretreatment of the fermentation liquid in step (b) may further include, after the filtration-electrodialysis-ion exchange process, a concentration (evaporation) process and a distillation process to remove water and impurities having a boiling point higher than the desired polyhydric alcohol.

[0071] The above concentration process can be performed by evaporating the first purified liquid to concentrate the water content from about 90% to about 20%. For example, the concentration process can be performed using equipment such as a concentration column (10) or a recompression (MR) evaporator.

[0072] The above distillation process can recover the target polyhydric alcohol by removing water through distillation of the concentrated product through the concentration process, and can also remove impurities with a boiling point higher than the target polyhydric alcohol by controlling the pressure through reduced pressure distillation. This allows for at least partial removal of unusual color and odor substances.

[0073] For example, when the target polyhydric alcohol is 2,3-butanediol, examples of off-flavor substances having a lower boiling point than 2,3-butanediol may include acetoin, methyl ethyl ketone, dioxolane, etc., and examples of off-flavor substances having a higher boiling point may include pyrazine, etc., but are not limited thereto.

[0074] Since the target polyhydric alcohol has a lower boiling point than the off-color and off-flavor substances, a reduced pressure distillation process can be used to discharge some of the off-flavor substances from the top of the distillation column, and the polyhydric alcohol can be recovered from the bottom. An additional distillation process can also be performed from the recovered polyhydric alcohol, thereby removing substances with a higher boiling point than the polyhydric alcohol and separating them from the top of the distillation column.

[0075] The above distillation process can set process conditions within a temperature range of room temperature (20 to 25°C) to 80°C and a pressure range of 7 mbar to 60 mbar.

[0076]

[0077] (c) Step

[0078] Next, the purification method of the present invention includes a step of obtaining a diluted solution of the first purified solution by supplying water to the first purified solution, which is the result of step (b), and diluting the first purified solution.

[0079] In one embodiment, the water may be supplied in the form of steam.

[0080] According to one embodiment, the content of water or steam relative to 100 parts by weight of the first purified liquid may be about 40 to 200 parts by weight. If the amount of water or steam added is less than about 40 parts by weight, it may not be easy to proceed with the subsequent hydrogenation process, and if it exceeds about 200 parts by weight, the amount of treatment in the additive distillation process (= (e) to (f) steps) after the hydrogenation process may become excessively large, thereby lowering the productivity and yield of the desired polyhydric alcohol.

[0081]

[0082] (d) Step

[0083] Next, the purification method of the present invention includes a step of performing a second purification by hydrogenating a diluted solution of the first purified solution, which is the result of step (c), to obtain a second purified solution.

[0084] By carrying out the hydrogenation process in this way, color formers can be removed, thereby obtaining better control over the intrinsic viscosity and color index of the target polyhydric alcohol, and discoloration and odor substances can be removed more efficiently.

[0085] In the purification method of the present invention, the hydrogenation reaction step may utilize a hydrogenation reactor. The hydrogenation reactor may refer to any known chemical reactor, including a shaking test tube, a batch autoclave, a slurry reactor, an upflow packed bed reactor, a drip-flow packed bed reactor, and the like.

[0086] Hydrogenation can be achieved by contacting polyhydric alcohols with hydrogen in the presence of a catalyst at elevated temperature and pressure. It is important to control the process so that the polyhydric alcohols are not completely hydrogenated to alkane compounds, while selectively removing off-color and off-flavor substances.

[0087] The catalyst may be composed of an element from Group VIII of the Periodic Table of Elements. More specifically, any metal selected from the group consisting of Ni, Co, Ru, Rh, Pd, Ir, and Pt, in the presence or absence of various promoters, may be used as the catalyst.

[0088] The catalyst may be a porous metal structure or may be supported on a substrate. The catalyst support may be selected from any support material known in the art, such as carbon, alumina, silica, titania, silica-alumina, silica-titania, titania-alumina, clay, aluminosilicates, water-insoluble salts of calcium, barium, barium sulfate, calcium carbonate, strontium carbonate, compounds thereof, and mixtures thereof.

[0089] The above hydrogenation can be carried out in various gas / liquid / solid contact reactors known in the art. These reactors can be operated in batch, semi-batch, and flow modes.

[0090] The hydrogenation reaction in the purification method of the present invention can be achieved in a temperature range of 25 to 200°C, preferably in a temperature range of 40 to 130°C, and preferably in a pressure range of 5 to 30 atm.

[0091]

[0092] (e) Step

[0093] The purification method of the present invention includes the step (e) of mixing the second purified liquid resulting from the step (d) with an additive and water to obtain an additive mixture liquid.

[0094] The second purified liquid, which is the result of the above step (d), may contain impurities such as different colors, different odors, organic acids, and inorganic acids in addition to the desired polyhydric alcohol (e.g., 2,3-butanediol or 1,3-propanediol). Therefore, it is necessary to remove these impurities. Therefore, water and additives are mixed with the second purified liquid.

[0095] It is preferable to select the additive that can adjust the pH of the second purified liquid, remove target acid substances such as organic acids and inorganic acids through a neutralization or precipitation reaction, or promote the removal of unusual colors and odors through differences in boiling points. From this perspective, the additive may include a neutralizing agent.

[0096] The neutralizing agent may include a carbonate and a metal hydroxide. For example, the carbonate may include one or more of NaHCO3, KHCO3, Na2CO3, and K2CO3, but is not limited to the above types. In one example, the neutralizing agent may use a monovalent carbonate and a divalent carbonate together to increase the neutralization reaction efficiency. As a specific example, NaHCO3 and K2CO3 may be used together as the neutralizing agent.

[0097] The above metal hydroxide may include at least one of Ca(OH)2 and Mg(OH)2, but is not limited to the above types.

[0098] For example, the neutralizing agent may be included in an amount of about 0.1 to 1 part by weight relative to 100 parts by weight of the second purified liquid. If the amount of the neutralizing agent is less than about 0.1 part by weight, the acid removal effect described above may not be sufficiently achieved. If the amount of the neutralizing agent exceeds about 1 part by weight, the amount of residue generated in the distillation process of the subsequent step may increase, thereby lowering the recovery rate of the polyhydric alcohol.

[0099]

[0100] (f) Step

[0101] Next, the purification method of the present invention includes a step (f) of obtaining a third purified liquid by concentrating the additive mixture resulting from the step (e) and then distilling it to recover the polyalcohol.

[0102] The concentration process of step (f) above can be performed by evaporating the water contained in the additive mixture to concentrate the water content from about 90% to about 20%. For example, the concentration process can be performed using equipment such as a concentration column or a recompression (MR) evaporator.

[0103]

[0104] *The distillation process of step (f) above can remove water by vaporization by distilling the resultant product concentrated by the concentration process, and at the same time, remove any remaining unusual color or odor substances, substances with a boiling point lower than the target polyhydric alcohol, and impurities.

[0105] According to an example, the distillation process of (f) above can be performed under conditions of a temperature of about 20°C to 130°C and a pressure of about 10 mbar to 60 mbar, and depending on the target substance to be removed, can be performed at a temperature lower or higher than the boiling point of the target polyhydric alcohol.

[0106] By the distillation process of the above step (f), 1 to 10 ppm of unusual color and odor substances can be removed, and purging with air, nitrogen or steam can be additionally performed during the distillation process to promote the removal of unusual color and odor substances.

[0107] By at least partially removing the foreign substances and off-flavor substances through the third purification step (f), a third purified liquid in which the target polyhydric alcohol is more concentrated or purified can be obtained.

[0108]

[0109] (g) Step

[0110] Next, a step is included of obtaining a fourth purified liquid by purifying the third purified liquid, which is the result of the step (f), a fourth time using a water stripping method. In the step (f), a water stripping process was used to remove water together with volatile substances.

[0111] In order to increase the efficiency of water stripping, water may be added to the third purified liquid to dilute it before carrying out the water stripping process, and the mixing weight ratio of the third purified liquid and water may be 1:1 to 1:5.

[0112] According to an example, the water stripping in step (f) may be performed by a reduced pressure distillation method, and may be performed through a distillation column or a single distillation, and water, steam, nitrogen, etc. may be used in the water stripping step.

[0113] For example, the step (f) may be performed under process conditions of a temperature of 20 to 80°C and a pressure of 10 to 60 mbar, preferably at a temperature of 24°C and a reduced pressure of about 30 mbar. In this way, a fourth purified liquid may be obtained through the fourth purification process that removes water using a water stripping method.

[0114]

[0115] (h) step

[0116] Next, the purification method of the present invention includes the step (h) of obtaining a fifth purified liquid by mixing water and an adsorbent with the fourth purified liquid resulting from the step (g) and then performing an adsorption treatment to remove impurities. The removed impurities may include unusual color or odor substances that can be removed by the adsorption treatment.

[0117] In one example, the adsorbent may include, but is not limited to, one or more of activated carbon, zeolite, and ion exchange resin.

[0118] The above adsorbent can be used in an amount of 0.3 to 3.0 parts by weight relative to 100 parts by weight of the fourth purified liquid. Even though the adsorbent is used in a relatively small amount compared to existing processes, it can efficiently remove unusual color and odor substances.

[0119] According to one example, the step (h) may be performed by supplying the fourth purified liquid mixed with water to an adsorption treatment member having an adsorbent built in, and the adsorption treatment chamber may include a bed or column on which the adsorbent is immobilized.

[0120] For example, the adsorption treatment chamber may be equipped with powdered activated carbon. Accordingly, the fourth mixed solution is brought into contact with the adsorbent through stirring, and any remaining unusual color or odor substances can be removed.

[0121] Water is added to activate the adsorption reaction, and 10 to 100 parts by weight of water can be mixed with 100 parts by weight of the fourth purified liquid, and the temperature at which the adsorption treatment is performed can be maintained at a temperature of about 40°C to 90°C.

[0122]

[0123] (i) Step

[0124] Next, the purification method of the present invention includes (i) a step of filtering out the adsorbent from the fifth purified liquid, which is the result of the step (h), and then performing a sixth purification using a distillation method to obtain a sixth purified liquid.

[0125] According to an example, the distillation conditions of step (i) may be set in a pressure range of 10 to 60 mbar and a temperature range of 20 to 130°C.

[0126] For example, in order to remove water in the distillation of step (i) above, an atmospheric distillation process can be selected.

[0127] The above step (i) is intended to remove water, and by controlling the distillation process conditions or arranging a plurality of distillation columns, molecules having a boiling point higher or lower than that of the target polyhydric alcohol can be additionally removed. According to one example, the method may further include a distillation process performed in one or more distillation columns to remove molecules having a boiling point higher than that of the target polyhydric alcohol; and a distillation process performed in one or more distillation columns to remove molecules having a boiling point lower than that of the target polyhydric alcohol.

[0128] For example, light impurities having a boiling point lower than that of the target polyhydric alcohol may be discharged from the top of the distillation column. Additionally, heavy impurities having a boiling point higher than that of the target polyhydric alcohol may be discharged from the bottom of the distillation column.

[0129] In one example, the final product from which the above light and heavy impurities have been removed can be sent to a product storage tank.

[0130] By the above step (i), the colorless and off-flavor substances at the level of 1 to 10 pppm can be removed. In addition, the removal of such colorless and off-flavor substances can be promoted by purging with air, nitrogen, or steam during the distillation process of the above step (i).

[0131] Hereinafter, the aforementioned polyhydric alcohol purification method will be described in detail with reference to various examples and comparative examples to illustrate the properties of the present invention. However, the following examples are intended to aid understanding of the present invention and are not intended to limit the scope of the present invention.

[0132] <Example>

[0133] Example 1

[0134] (1) Preparation of polyalcohol fermentation liquid (step (a))

[0135] Cassava was washed as a raw material, and then the washed cassava was placed in a blender and used as a ground carbon source together with water (cassava:water = 1:1 w / v ratio) to prepare a fermentation medium, inoculated with Klebsiella oxytoca (GSC0850), and maintained under conditions of 30°C and pH 6. After microaerobic fermentation, centrifugation was performed to obtain a polyhydric alcohol fermentation solution containing 2,3-butanediol.

[0136] (2) First purification (step (b)) - pretreatment

[0137] The fermentation solution obtained in the above (1) was filtered using a polymer membrane filter with a pore size of 0.5 to 1 ㎛ to remove solids. Then, a cationic membrane and anionic membrane were cross-stacked to form an electrodialysis stack, and then electrodialysis was performed under the conditions of a current density of 5 to 10 mA / cm² and a voltage of 1 to 2 V / cell to remove organic and inorganic ionic impurities. Then, the solution was sequentially passed through a cationic column (CEX, H type) and an anionic column (AEX, OH type) to remove any remaining salts or ionic organic acids. Then, water was removed through an evaporation process under a reduced pressure condition of approximately 10 mbar to adjust the concentration of the fermentation solution to approximately 60%, and then the remaining water and high-boiling-point impurities were removed through a reduced pressure distillation column, and 2,3-butanediol was recovered to complete the pretreatment, thereby obtaining a first purified solution.

[0138] (3) Second purification (steps (c) to (d)) - hydrogenation reaction

[0139] After mixing and diluting the first purified solution (pretreated 2,3-butanediol recovery solution) and water (first purified solution: water = 1:1 w / v ratio), a hydrogenation reaction was performed at a temperature of about 60°C using a lutetium catalyst (HyFlex 570) tablet, and at this time, 2,3-butanediol was not generated into butane, but other organic substances were reacted to be hydrogenated, thereby obtaining a second purified solution.

[0140] (4) Third purification (steps (e) to (f)) - Distillation after mixing additives

[0141] For 100 parts by weight of the second purified liquid obtained in the above step (3), 0.3 parts by weight of NaHCO3, 0.1 parts by weight of K2CO3, and 5 parts by weight of water were mixed to prepare an additive mixture, and the additive mixture was concentrated to about 80%. Thereafter, 2,3-butanediol was recovered from the concentrated additive mixture through the top of a reduced pressure fractional distillation column at a temperature of about 80°C to obtain a third purified liquid, and the third purified liquid was recovered in a weight of 90% of the weight of the second purified liquid.

[0142] (5) Fourth purification (steps (e) to (f)) - water stripping

[0143] The fourth purification was performed by diluting the third purified liquid with water in a 1:1 ratio, then removing water through reduced pressure distillation under conditions of a reduced pressure of about 30 mbar and a temperature of 24°C to recover high-concentration 2,3-butanediol, thereby obtaining the fourth purified liquid.

[0144] (6) Fifth purification ((h) step) - adsorption treatment

[0145] A fifth purification was performed by mixing 50 parts by weight of water and 1 part by weight of powdered activated carbon (Norit SX Plus) as an adsorbent with respect to 100 parts by weight of the above fourth purified liquid, stirring at room temperature for about 1 hour to perform adsorption treatment, and then filtering and removing the powdered activated carbon to obtain a fifth purified liquid.

[0146] (7) 6th purification ((i) step) - distillation

[0147] The sixth purification step was performed by mixing 40 parts by weight of water with 100 parts by weight of the above-mentioned fifth purified liquid, and then distilling under reduced pressure conditions of approximately 30 mbar and 24°C. During this process, some off-flavor substances were removed by volatilization while removing water. The sixth purification step was completed, and the sixth purified liquid was obtained as the final purified product.

[0148] Comparative Example 1

[0149] In Comparative Example 1, the process was carried out in the same manner as in Example 1, except that the “(3) Second Purification ((c) to (d) steps) - Hydrogenation Reaction” was not performed.

[0150]

[0151] <Method of evaluating physical properties>

[0152] 1. Gas chromatography analysis

[0153] For the final results of 2,3-butanediol obtained in Example 1 and Comparative Example 1, gas chromatography analysis was performed using the equipment “Agilent 6890 GC-MS (column: HP-5MS)”, and the results are shown in Fig. 3. As shown in Fig. 3, in the case of Example 1, no organic impurity peaks that needed to be removed were observed other than the peak of 2,3-butanediol, whereas in Comparative Example 1, impurity peaks were observed together with the peak of 2,3-butanediol, confirming that impurity removal was not sufficiently achieved. The impurity content in Fig. 3 was estimated through the ratio of the integral value of the impurity among the integral value of the total area of ​​the GC peak, and the peak of Impurity 1 is interpreted as a peak containing methyl ethyl ketone (MEK), and impurities 2 and 3 are interpreted as peaks containing acetoin. Although not all impurity peaks were analyzed in Fig. 3, it was confirmed through the GC pattern that the present invention, which performed impurity purification by conducting a hydrogenation reaction as in Example 1, exhibited a higher impurity removal effect.

[0154] 2. Sensory evaluation

[0155] To evaluate the quality, the final products of 2,3-butanediol obtained by Example 1 and Comparative Example 1 were subjected to off-flavor evaluations. Specifically, a sensory evaluation was conducted on the presence or absence of off-flavors using the evaluation criteria below by 30 panelists, and the average score was calculated. As a result of the evaluation, the sensory score for Example 1 was 7.6, while the sensory score for Comparative Example 1 was 4.0.

[0156] It was confirmed that when purified according to the present invention, the off-flavor substance of 2,3-butanediol was significantly removed.

[0157] <Taste Evaluation Score>

[0158] 1 point: Very strong off-flavor

[0159] 3 points: Strong off-flavor

[0160] 5 points: Moderate off-flavor

[0161] 7 points: A brief, faint off-flavor occurs.

[0162] 8 points: Occurrence of a difficult-to-detect residual odor

[0163] 10 points: Odorless

[0164]

[0165] Those skilled in the art will understand that the present invention can be practiced in forms other than those disclosed without altering the technical spirit or essential characteristics of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. (a) A step of preparing a fermentation liquid containing the desired polyhydric alcohol; (b) a step of obtaining a first purified liquid by first purifying the fermented liquid in a pretreatment manner; (c) a step of diluting the first purified solution resulting from step (b) to obtain a diluted solution of the first purified solution; (d) a step of hydrogenating the diluted solution of the first purified solution, which is the result of step (c), to obtain a second purified solution; (e) a step of mixing the second purified liquid resulting from the step (d) with an additive and water to obtain an additive mixture; (f) a step of obtaining a third purified liquid by concentrating the additive mixture resulting from step (e) and then distilling it to recover the polyalcohol; (g) a step of obtaining a fourth purified liquid by purifying the third purified liquid, which is the result of the step (f), a fourth time using a water stripping method; (h) a step of obtaining a fifth purified liquid by mixing water and an adsorbent in the fourth purified liquid resulting from the step (g) and then performing an adsorption treatment to remove impurities; and (i) a step of filtering out the adsorbent from the fifth purified liquid, which is the result of the step (h), and then performing a sixth purification to obtain a sixth purified liquid; Method for purifying polyhydric alcohols.

2. In paragraph 1, The pretreatment of step (b) above includes one or more processes among a filtration process, an electrodialysis process, and an ion exchange process. Method for purifying polyhydric alcohols.

3. In paragraph 1, The additive of step (e) above includes a neutralizing agent, Method for purifying polyhydric alcohols.

4. In paragraph 3, The neutralizing agent of step (e) above includes carbonate and metal hydroxide. Method for purifying polyhydric alcohols.

5. In paragraph 3, The neutralizing agent of the above step (e) is mixed in an amount of 0.1 to 1 part by weight relative to 100 parts by weight of the second purified liquid. Method for purifying polyhydric alcohols.

6. In paragraph 1, The distillation conditions of the above step (f) are set in a pressure range of 10 to 60 mbar and a temperature range of 20 to 130°C. Method for purifying polyhydric alcohols.

7. In paragraph 1, The distillation of step (f) is performed through a distillation column or a single distillation, and includes removing water. Method for purifying polyhydric alcohols.

8. In paragraph 1, The adsorbent of the above step (h) comprises at least one of activated carbon, zeolite, and ion exchange resin. Method for purifying polyhydric alcohols.

9. In paragraph 1, The distillation conditions of step (i) above are set in a pressure range of 10 to 60 mbar and a temperature range of 20 to 130°C. Method for purifying polyhydric alcohols.

10. In paragraph 1, A method for purifying polyhydric alcohol, wherein the distillation in step (i) is performed by an atmospheric distillation process to remove water.

11. In paragraph 10, The distillation of step (i) above, A distillation process performed in one or more distillation columns to remove molecules having a boiling point higher than the boiling point of the desired polyhydric alcohol; and further comprising a distillation process performed in one or more distillation columns to remove molecules having a boiling point lower than the boiling point of the target polyhydric alcohol; Method for purifying polyhydric alcohols.

12. In paragraph 1, The above-mentioned polyhydric alcohol comprises 2,3-butanediol or 1,3-propanediol. Method for purifying polyhydric alcohols.

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