KR20140105194A - Method for high-yield preparation of highly pure anhydrosugar alcohols from low-grade distillate - Google Patents

Abstract

The present invention relates to a method for preparing high purity anhydrosugar alcohols of high yield from a low-grade distillate, and more specifically, to a method for preparing anhydrosugar alcohols of high yield having the final purity of at least 98% even if the purity of a distillate is lower than 95%, which is gained by dehydrating a hydrogenated sugar, transforming the same into anhydrous sugar alcohols, and distilling the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a high-purity dihydric alcohol from a low-grade distillate at a high yield. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

The present invention relates to a process for producing a high purity anhydrous alcohol from a lower distillate in a high yield and more particularly to a process for producing a distillate obtained by converting a hydrogenated sugar to a dehydrated alcohol, To 95% or less of the purity of the unmodified alcohol with a final purity of 98% or more.

Hydrogenated sugar (also referred to as " sugar alcohol ") refers to a compound obtained by adding hydrogen to a reducing end group of a saccharide, generally HOCH ₂ (CHOH) _n CH ₂ OH (where n is an integer of 2 to 5 ), And classified into tetritol, pentitol, hexitol and heptitol (C 4, 5, 6 and 7, respectively), depending on the number of carbon atoms. Among them, hexitol having 6 carbon atoms includes sorbitol, mannitol, iditol, galactitol and the like, and sorbitol and mannitol are particularly useful substances.

Anhydrosugar alcohol has a diol form with two hydroxyl groups in the molecule and can be prepared by utilizing hexitol derived from starch (for example, Korean Patent No. 10-1079518, Korean Patent Laid- -2012-0066904). Since alcohol-free alcohol is an eco-friendly substance derived from renewable natural resources, there has been much interest for a long time and studies on the manufacturing method have been carried out. Among these alcohol-free alcohols, isosorbide prepared from sorbitol has the widest industrial application currently.

The use of anhydrous alcohol is widely used in the treatment of cardiovascular diseases, patches, adhesives, oral cleansers and the like, solvents for compositions in the cosmetics industry, and emulsifiers in the food industry. In addition, it is possible to increase the glass transition temperature of a polymer substance such as polyester, PET, polycarbonate, polyurethane, and epoxy resin, to improve the strength of these materials, and to be an environmentally friendly material derived from natural materials. useful. It is also known to be used as an environmentally friendly solvent for adhesives, environmentally friendly plasticizers, biodegradable polymers, and water-soluble lacquers.

As such, alcohol-free alcohol has attracted a great deal of attention due to its versatility and its use in real industry is increasing. However, the conventional method of producing an alcohol-free alcohol has a high catalyst cost for dehydration and low conversion, distillation and purification yield.

In order to improve the purity of the alcohol-free alcohol, it is common to increase the purity as much as possible in the distillation step and then to undergo the crystallization step, and it is usually required that the purity of the product obtained through the distillation step is 97% or more. However, in order to increase the purity in the distillation stage, the reduction of the distillation yield must be avoided, which leads to an increase in the cost and efficiency of the entire process. In addition, there is a case where the conversion liquid or impurities during the distillation flow into the distillate to degrade the purity. Such distillates can not be utilized without re-distillation. In short, even if the required purity of the distillate is lower than the conventional level, it is highly desirable in terms of cost and process efficiency if a high purity alcohol-free alcohol can be obtained.

Accordingly, there is a need to develop a technique for producing high purity alcohol free of alcohol (for example, 98% or more of final purity) from a low-grade distillate (for example, a purity of 95% or less) at a high yield.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a process for producing anhydrous alcohol having a final purity of 98% or more from a distillate having a purity of 95% The technical problem is to provide.

In order to solve the above-mentioned technical problems, the present invention provides a process for producing a dihydric alcohol, comprising the steps of: (1) dehydrogenating a hydrogenated sugar to convert it to a dihydric alcohol; (2) distilling the liquid resulting from the reaction of step (1) to obtain distillate having a purity of 95% or less; And (3) crystallizing the distillate resulting from the step (2), wherein the step (3) comprises the steps of: (3-1) dissolving the distillate in the crystallization solvent as a result of the step (2) 3-2) cooling the temperature of the resulting solution to 10 ° C or less, and (3-3) raising the temperature of the cooled product to 15 ° C or more.

According to a further aspect of the present invention there is provided a process for the preparation of (i) dissolving an anhydrous alcohol having a purity of not more than 95% in a crystallization solvent, (ii) cooling the resultant solution to a temperature below 10 ° C, and (iii) To 15 [deg.] C or higher, characterized by comprising the step of raising the temperature of the free alcohol to 15 [deg.] C or higher.

According to the present invention, since a distillate having a purity of 95% or less can be used to produce a nonaqueous alcohol having a final purity of 98% or more at a high yield (for example, a crystallization yield of 87% or more) by a simpler process, The economical efficiency and process efficiency of the process can be remarkably improved.

Hereinafter, the present invention will be described in detail.

According to a first aspect of the present invention there is provided a process for the preparation of (1) a process for the dehydration of a hydrogenated sugar, (2) distilling the liquid resulting from the reaction of step (1) to obtain distillate having a purity of 95% or less; And (3) crystallizing the distillate resulting from the step (2), wherein the step (3) comprises the steps of: (3-1) (3-2) cooling the temperature of the resulting solution to 10 ° C or lower, and (3-3) raising the temperature of the cooled resultant solution to 15 ° C or higher. Method is provided.

[Step (1)] The method for producing an alcohol-free alcohol of the present invention includes a step of dehydrating a hydrogenated sugar to convert it to an alcohol-free alcohol.

The hydrogenated sugar is generally referred to as sugar alcohol and means a compound obtained by adding hydrogen to the reducing end group of the saccharide. Hydrogenated sugars are classified into tetritol, pentitol, hexitol and heptitol (C 4, 5, 6 and 7, respectively) depending on the number of carbon atoms. Among them, hexitol having 6 carbon atoms includes sorbitol, mannitol, iditol, galactitol and the like, and sorbitol and mannitol are particularly useful substances.

As used herein, the expression ' anhydrous alcohol ' refers to any material obtained by removing one or more water molecules from the original internal structure of the hydrogenated sugar in one or more steps in any manner.

In the present invention, hexitol is preferably used as the hydrogenated sugar, more preferably hydrogenated sugar selected from sorbitol, mannitol, editol, and mixtures thereof, and more preferably hydrogenated sugar from starch Lt; RTI ID = 0.0 > sorbitol < / RTI >

The hydrogenated sugar is converted to a dihydric alcohol by dehydration reaction. There is no particular limitation on the method of dehydrogenating the hydrogenated sugar, and known methods known in the art can be used as it is or modified appropriately.

It is preferable that an acid catalyst is used to convert the hydrogenated sugar to dehydrated and converted to anhydrated alcohol.

According to one embodiment of the present invention, a single acid catalyst such as sulfuric acid, nitric acid, hydrochloric acid, p-toluenesulfonic acid, or phosphoric acid may be used as the acid catalyst, more preferably sulfuric acid may be used.

According to another embodiment of the present invention, a mixed acid of a first acid and a second acid can be used as the acid catalyst, more preferably, sulfuric acid as a first acid, p-toluenesulfonic acid as a second acid, At least one sulfur-containing acid material selected from the group consisting of phosphoric acid, ethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid and aluminum sulfate can be used.

When a mixed acid is used, the ratio of the first acid to the second acid is preferably 1: 9 to 9: 1 by weight. If the ratio is less than 1: 9 (i.e., the amount of the primary acid is relatively excessively small), the rate of production of an alcohol free alcohol may be lowered, and if it exceeds 9: 1 If too much, the production of saccharide polymers may be increased.

The amount of the acid catalyst to be used is preferably 0.5 to 10 parts by weight per 100 parts by weight of hydrogenated sugar (e.g., hexitol). If the amount of the acid catalyst is less than 0.5 parts by weight per 100 parts by weight of hydrogenation, the conversion time to the alcohol without sugar alcohol may be too long. If the amount is more than 10 parts by weight, the production of the saccharide polymer may be increased and the conversion may be lowered.

According to one embodiment of the present invention, the step of converting the hydrogenated sugar into anhydrosugar alcohol is carried out in the presence of an acid catalyst as described above at a temperature condition of 105 to 190 DEG C and a pressure of 1 to 100 mmHg for 1 to 10 hours But is not necessarily limited thereto.

In the case of using an acid catalyst in the dehydrogenation reaction of the hydrogenated sugar, it is preferable that the reaction liquid is neutralized. Neutralization can be carried out by lowering the temperature of the reaction liquid after completion of the dehydration reaction (for example, 110 ° C or less) and adding a known alkali such as sodium hydroxide. The pH of the solution is preferably 6 to 8 as a result of the neutralization reaction.

According to one preferred embodiment of the process for preparing anhydrosugar alcohol of the present invention, the liquid resulting from the conversion of the hydrogenated sugar to the anhydride alcohol can be pretreated prior to the subsequent distillation step. This pretreatment is intended to remove moisture and low boiling matter remaining in the liquid resulting from the conversion step. The liquid obtained by the conversion step under the conditions of a temperature of 90 ° C. to 110 ° C. and a pressure of 10 mmHg to 100 mmHg is stirred for 30 minutes or more , 30 minutes to 4 hours), but is not limited thereto.

In the present invention, dianhydrohexitol, which is a dehydrate of hexitol, is preferably obtained as the resultant product of the conversion reaction, more preferably isosorbide (1,4-diol, Sorbitol), isomannide (1,4-3,6-dianhydromonitol), isoidide (1,4-3,6-dianhydride), and mixtures thereof. Of these, isosorbide is particularly high in industrial and medicinal applications.

[Step (2)] In the method for producing an alcohol-free alcohol according to the present invention, the reaction mixture obtained in the above step (1) is distilled to obtain a product having a purity of 95% or less (for example, 89 to 95%, more specifically 90 to 93% Of distillate is obtained.

The distillation is preferably carried out at a temperature of 100 to 250 DEG C, more preferably 150 to 220 DEG C and preferably 10 mmHg or less (for example, 0.1 to 10 mmHg), more preferably 8 mmHg or less (for example, 8 mmHg). ≪ / RTI > When the distillation temperature is less than 100 ° C, the distillation of the alcohol without alcohol is not performed well. If the distillation temperature is higher than 250 ° C, the purity of the alcohol without alcohol is lowered, and the color becomes darker. If the distillation pressure is higher than 10 mmHg, the distillation temperature must be increased in order to distill the alcohol without sugar, and the above-mentioned problems may arise. On the other hand, in order to lower the distillation pressure, a high vacuum apparatus cost is further required, and distillation purity is lowered, so that an excessively low distillation pressure is not preferable. The distillation may be carried out in two or more stages as required. There is no particular limitation on the method and apparatus for distillation, and known methods and apparatuses known to those skilled in the art can be used as is or modified appropriately. For example, a general condenser type distiller or distillation tower still can be used, or a thin film still can be used. According to a preferred embodiment of the present invention, this distillation step can be carried out using a thin film still, for example, a condenser built-in thin film still or a condenser external thin film still, and more preferably using a condenser built-in thin film still .

[Step (3)] In the method for producing an alcohol-free alcohol according to the present invention, distillate resulting from the step (2) is crystallized.

The crystallization step of the present invention comprises the steps of (3-1) dissolving the distillate as a result of step (2) in a crystallization solvent, (3-2) cooling the resultant solution to a temperature below 10 ° C, and (3-3 ) Raising the temperature of the cooled product to < RTI ID = 0.0 > 15 C < / RTI >

In the step (3-1), a solvent such as ethyl acetate, ketone, toluene, benzene, xylene or alcohol may be used alone or as a mixed solvent. Preferably, the solvent is a ketone alone or a mixed solvent containing a ketone Can be used. The ketone is preferably a ketone having 2 to 8 carbon atoms, more preferably a ketone having 2 to 6 carbon atoms. Most preferably, acetone can be used.

The use ratio of the crystallization solvent to the distillate to be crystallized is preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight, and most preferably 30 to 50 parts by weight per 100 parts by weight of the distillate. If the ratio of the crystallization solvent to the distillate is too small, the effect of purification due to crystallization may not be sufficient. On the other hand, if too large, the crystallization yield may be low.

In the step (3-1), the distillate can be dissolved in the crystallization solvent under the condition of elevating the temperature from room temperature, preferably 30 ° C or more (for example, 30 to 40 ° C).

In the step (3-2), the temperature of the resultant solution obtained in the step (3-1) is cooled to 10 ° C or less (for example, 10 to 5 ° C) to precipitate crystals. At this time, a crystallization seed may be injected at the initial stage of cooling or during cooling as required.

In the step (3-3), the temperature of the resultant cooled in the step (3-3) is raised to 15 ° C or more (for example, 15 to 25 ° C) to dissolve impurities on the crystal surface. At this time, if the re-rise temperature is less than 15 deg. C, the effect of removing impurities due to dissolution may be insufficient. Conversely, if the re-rise temperature is excessively high, the crystallization yield may be lowered.

There is no particular limitation on the method and apparatus used for crystallization, and the crystallization method and apparatus that have been known in the art for a long time can be used as is or modified appropriately. Concretely, for example, an alcohol-free alcohol is dissolved in a ketone solvent, for example, at an elevated temperature as required, and then the temperature of the solution is lowered to 10 ° C or lower to precipitate an alcohol-free alcohol crystal. So that impurities on the crystal surface can be dissolved. The amount of the solvent used and the temperature for raising / lowering the cooling rate can be appropriately determined according to the throughput and the specific equipment conditions. According to one preferred embodiment of the present invention, acetone and an alcohol-free alcohol distillate are mixed as a solvent, the temperature of the solution is raised to 30 ° C or higher, a crystallization seed is added if necessary, To precipitate anhydrous alcohol crystals. The resultant temperature is raised to 20 ° C, and then filtered to obtain an alcohol-free alcohol crystal. The crystalline mother liquor from which crystals have been separated can be recycled to the distillation step after mixing with the converted liquor after concentration and recovery in order to improve the overall yield of the alcohol without sugar. In this case, the distillation yield is improved and the overall yield improvement effect can be obtained.

The method for producing an alcohol-free alcohol of the present invention may further include the step of purifying the resulting alcohol-free alcohol crystals obtained in the step (3) by one or more treatments selected from a decoloring treatment and an ion exchange resin treatment.

The decolorizing treatment can be preferably performed by bringing the aqueous solution obtained by dissolving the obtained crystallized product of anhydrosugar alcohol in water (for example, distilled water) into contact with activated carbon. In this case, the average particle size of activated carbon is preferably 0.1 to 1 mm, more preferably 0.2 to 0.7 mm. If the average particle size of the activated carbon particles is too small and the average particle size of the activated carbon particles is less than 0.1 mm, there is a problem that the liquid passing speed is significantly lowered and the pressure in the column is increased. On the other hand, mm, there may be a problem that the ion content and electrical conductivity of the resulting alcohol-free alcohol are increased and the chromaticity is increased.

There is no particular limitation on the method of contacting the aqueous solution of alcohol-free alcohol with the activated carbon. For example, a method in which an aqueous solution of an alcohol-free alcohol is passed through a column packed with activated carbon, or alternatively, an aqueous solution of an alcohol-free alcohol and an activated carbon may be fed into a reactor and stirred for a certain period of time. According to one preferred embodiment of the present invention, the decoloring treatment proceeds in such a manner that an aqueous solution of an alcohol-free alcohol is passed through a column packed with activated carbon.

As the activated carbon, there may be used one or more selected from the group consisting of plant raw materials such as wood and coconut, activated carbon obtained by activating mineral raw materials such as lignite, bituminous coal, bituminous coal and anthracite. There is no particular limitation on the shape of the activated carbon particles, and shapes such as fine particles (for example, average particle size of 0.25 to 0.75 mm), particles (for example, average particle size of 0.75 mm or more), and powders (for example, average particle size of 0.25 mm or less) It is possible. According to a preferred embodiment of the present invention, activated carbon in the form of fine particles is used. In order to increase the efficiency of activated carbon, it is also possible to use pre-treated activated carbon such as washing.

The purification treatment with an ion exchange resin can be carried out by contacting an aqueous solution of an alcohol-free alcohol with an ion exchange resin. This can be carried out by passing an aqueous solution of an alcohol-free alcohol through a column filled with ion exchange resin.

Preferably, the ion-exchange resin treatment can be carried out using a cationic exchange resin, an anionic ion-exchange resin, or both, more preferably a cationic ion exchange resin treatment and a strong anionic ion exchange resin Processing can be sequentially performed.

As the cationic ion exchange resin, it is possible to use all of a cationic ion exchange resin (for example, TRILITE-SCR-B) and a weak cationic ion exchange resin (for example, DIAION WK11) Lt; / RTI > Examples of cation exchange resins include H-type ion exchange resins (for example, TRILITE-SCR-BH) and Na-type ion exchange resins (for example, TRILITE-SCR-B ) Can be preferably used.

As the anionic ion exchange resin, a strong anionic ion exchange resin (for example, TRILITE AMP24) and a weak anionic ion exchange resin (for example, DIAION WA10) can be used, and a strongly anionic ion exchange resin is preferably used . As the strong anionic ion exchange resin, Cl type strong anion ion exchange resin (for example, TRILITE AMP24) may be preferably used.

There is no particular limitation on the ion purification method and the column apparatus using the ion exchange resin, and known methods and apparatuses known in the art can be used as is or modified appropriately.

The method for producing an alcohol-free alcohol of the present invention may further comprise, as necessary, a step of concentrating or solidifying the alcohol-free alcoholic solution refined in the step (4). Through such concentration or solidification step, a fruitless alcohol product with a flake property or a granule property can be finally obtained.

According to the method for producing alcohol-free alcohol of the present invention as described above, an alcohol-free alcohol having a final purity of 98% or more can be obtained from a low-grade distillate having a purity of 95% or less at an excellent crystallization yield of 87% or more.

According to another aspect of the present invention, there is provided a method for producing a polyvinyl alcohol solution, comprising the steps of: (i) dissolving an anhydrous alcohol having a purity of 95% or less in a crystallization solvent; (ii) And raising the temperature of the resultant product to 15 DEG C or higher, so as to improve the purity of the alcohol without sugar.

In the method for improving the purity of the alcohol without sugar alcohol according to the present invention, the solvent used for crystallizing the alcohol without sugar alcohol and the method thereof are as described above. According to the method of the present invention, the purity of the alcohol without sugar alcohol is 98% .

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples are intended to assist the understanding of the present invention, and the scope of the present invention is not limited thereto.

[ Example ]

≪ Measurement of physical properties &

The purity of alcohol without sugar was analyzed by gas chromatography (GC) (GC7890).

Example  One

100 g of sulfuric acid (Duksan Chemical Co.) and 42 g of methane sulfonic acid (Duksan Chemical Co., Ltd.) were added thereto. The mixture was heated to 110 DEG C to dissolve therein 10,000 g of sorbitol powder (D-sorbitol, And the temperature of the reactor was raised to about 140 캜. The dehydration reaction was carried out under reduced pressure of about 30 mmHg to convert it to alcohol without sugar. After completion of the dehydration reaction, the temperature of the reaction mixture was lowered to 110 占 폚, and about 300 g of 50% sodium hydroxide solution (Samseon Pure Chemical Co., Ltd.) was added to neutralize the resultant solution. After the temperature of the neutralized solution was adjusted to 100 ° C, the solution was concentrated under an inert pressure of 40 mmHg or less for 1 hour or more to remove moisture and low boiling point substances present in the resultant solution. After the neutralization and water removal were completed, the conversion of sorbitol was 74%, and the content of sorbitan and sorbitan isomers in the resultant liquid was 1% by weight and the content of other polymer was 15%.

The sorbitol conversion solution with neutralization and moisture removal was introduced into a condenser built-in thin film evaporator (internal condenser type), and thin film distillation was carried out at a distillation temperature of 200 ° C and an internal pressure of 5.0 mmHg. As a result, the isosorbide purity of the distillate was 90.8%, the color was light brown, and the distilled water rate was about 96%.

3000 g of the distillate and 1000 g of acetone as a crystallization solvent were added to a 5 L batch crystallizer equipped with a stirrer and completely dissolved at 40 캜 and then cooled to 30 캜. Subsequently, 1 g of powder-free alcohol was added as a crystallization seed, and the temperature was cooled to 10 ° C at a rate of 0.16 ° C / min to precipitate crystals. Thereafter, the temperature was raised again to 20 ° C at a rate of 0.16 ° C / min to dissolve impurities on the crystal surface.

After completion of the crystallization step, the resultant was vacuum filtered using a 5A filter paper in a buchner funnel. The resulting crystals were dried in a 40 DEG C vacuum dryer for 1 hour to completely remove the residual solvent.

The final purity of the alcohol-free alcohol alcohol obtained was 98.6%, and the crystallization yield calculated by the formula [crystal weight * crystal purity] / [distillate weight * distillate purity] was 87.1%.

Comparative Example  One

3000 g of the distillate obtained in Example 1 and 1000 g of acetone as a crystallization solvent were added to a 5 L batch crystallizer equipped with a stirrer and completely dissolved at 40 캜 and then cooled to 30 캜. Subsequently, 1 g of powder-free alcohol was added as a crystallization seed, and the temperature was cooled to 10 ° C at a rate of 0.16 ° C / min to precipitate crystals. Thereafter, the resultant was vacuum filtered using a 5A filter paper in a buchner funnel, and the filtered crystals were washed and vacuum filtered by adding 1/3 of the weight of acetone to 10 wt% of the crystal weight. The resulting crystals were dried in a 40 DEG C vacuum dryer for 1 hour to completely remove the residual solvent. The purity of the final alcohol-free alcohol crystals obtained was 98.5%, and the crystallization yield was 85.1%.

As can be seen from the above results, in Example 1 of the present invention in which the temperature of the solution in the step of crystallizing the distillate having a purity level of about 90% was cooled to 10 ° C or lower, Free alcohol crystals having a final purity of 98% or more can be obtained at a high crystallization yield of 87% or more. On the other hand, the crystallization yield of the alcohol-free alcohol crystals obtained in Comparative Example 1 in which the crystallization was terminated at a temperature of 10 ° C or lower and the resultant crystal was washed with a solvent at a temperature of 10 ° C was only 85.1%. Thus, according to the present invention, it has been confirmed that an unstructured alcohol having a final purity of 98% or more can be obtained from a low-grade distillate having a purity of 95% or less by a more simplified process at a high crystallization yield of 87% or more.

Claims (14)

(1) dehydrating the hydrogenated sugar to convert it to an alcohol-free alcohol;
(2) distilling the liquid resulting from the reaction of step (1) to obtain a distillate having a purity of 95% or less; And
(3) crystallizing the distillate as a result of the step (2)
(3) is a step of dissolving the distillate as a result of (3-1) (2) in a crystallization solvent, (3-2) cooling the resultant solution to a temperature of 10 ° C or less, and (3-3 ) Raising the temperature of the cooled product to < RTI ID = 0.0 > 15 C &
A method for producing alcohol-free alcohol. The process according to claim 1, wherein the hydrogenated saccharide is hexitol and the anhydrous alcohol is dianhydrohexitol. The process for producing an alcohol-free alcohol according to claim 1, wherein an acid catalyst is used in the step of dehydrating the hydrogenated sugar to convert it to an alcohol-free alcohol. 4. The process according to claim 3, wherein the acid catalyst is a single acid selected from sulfuric acid, nitric acid, hydrochloric acid, p-toluenesulfonic acid and phosphoric acid. 4. The process of claim 3 wherein the acid catalyst is a mixed acid of a first acid and a second acid wherein the first acid is sulfuric acid and the second acid is selected from the group consisting of p-toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, naphthalene Sulfonic acid, and aluminum sulfate. ≪ RTI ID = 0.0 > 15. < / RTI > The method according to claim 1, wherein the dehydration reaction of the hydrogenated saccharide is neutralized in the step (1). 7. The method of claim 6, wherein the dehydration reaction of the neutralized hydrogenated sugar is pre-treated to remove moisture and low boiling substances before the distillation step. The process for producing an alcohol-free alcohol according to claim 1, wherein the distillation is carried out using the thin film still in the step (2). The method for producing an alcohol-free alcohol according to claim 1, wherein the crystallization solvent used in the step (3) is a ketone alone or a mixed solvent comprising a ketone. The process for producing an alcohol-free alcohol according to claim 9, wherein the ketone is acetone. The method of claim 1, further comprising purifying the washed, anhydrous alcoholic alcohol crystals obtained as a result of the step (4) by one or more treatments selected from a decoloring treatment and an ion exchange resin treatment. A method for producing an alcohol. 12. The process according to claim 11, wherein the decolorizing treatment is carried out using activated carbon. 12. The method for producing an alcohol-free alcohol according to claim 11, wherein the treatment of the ion exchange resin and the treatment of the strong anion exchange resin are sequentially carried out. (i) dissolving an anhydrosugar alcohol having a purity of 95% or less in a crystallization solvent, (ii) cooling the resultant solution to a temperature of 10 DEG C or lower, and (iii) raising the temperature of the cooled product to 15 DEG C or higher ≪ / RTI > wherein the purity of the alcohol is increased.