KR20220046832A - Method for separating two lignin with different dissolution properties from lignin - Google Patents

Abstract

Provided is a method for separating two lignin with different dissolution properties from lignin. The method comprises the steps of: a) reacting a eutectic solution with lignin; b) adding ethanol to the product of step a) and recovering a first precipitate; c) recovering a first liquid product except for the first precipitate; d) adding water to the first liquid product and recovering a second precipitate; and e) recovering a second liquid product except for the second precipitate. Through the method, it is possible to separate lignin that is insoluble in water and ethanol and lignin that is insoluble in water but soluble in ethanol.

Description

{Method for separating two lignin with different dissolution properties from lignin}

Various embodiments of the present invention relate to a method for separating two lignins having different dissolution properties from lignin. Specifically, various embodiments of the present invention relate to a method for separating lignin that is insoluble in water and ethanol from lignin, and lignin that is insoluble in water but is soluble in ethanol.

It is possible to respond to climate change and replace fossil fuels by producing biofuels using biomass resources existing on the earth. The lignocellulosic biomass is the most abundant resource and has the advantage of being able to secure stable raw materials in most regions. Wood-based biomass is composed of cellulose, hemicellulose, and lignin, and cellulose and hemicellulose can produce bioalcohol through a microbial fermentation process. In order to utilize cellulose and hemicellulose, it is necessary to separate them from the lignin surrounding them through a pretreatment process. Acid or base catalysts can be used in the pretreatment process of lignocellulosic biomass. Among them, the acid hydrolysis pretreatment process has a high reaction rate and can increase the saccharification yield of cellulose and hemicellulose in the subsequent hydrolysis process. Lignin is present in about 25wt% in lignocellulosic biomass, and in the acid hydrolysis pretreatment process, lignin residues corresponding to 30-40wt% of lignocellulosic biomass raw materials are generated. Included. Due to the steady production of bioalcohol, lignin residues are also expected to increase continuously, and attempts are being made to utilize it. It is also possible to recover kraft lignin from black liquor generated in the pulping process. When cooking kraft, it is treated in an aqueous solution of sodium hydroxide and sodium sulfide for about 2 hours at a temperature of around 170 degrees. In this process, about 90-95% of wood lignin is dissolved and discharged as black liquor. Kraft lignin can be produced by neutralizing and acidifying the pulping black liquor with inorganic acid or carbon dioxide, etc. to precipitate it, and then purifying it through pickling. Kraft lignin made from pulping black liquor is being actively developed not only for use as a raw material for biofuel production, but also for use as a fine chemical material that can replace various phenolic polymers derived from petrochemicals.

Lignin generated in the process of producing bioalcohol from lignocellulosic biomass can be used as fuel for liquid power generation through liquefaction and deoxygenation reactions. Ethanol can be used under supercritical conditions as a reaction solvent for liquid fuel production. However, the lignin obtained through the acid hydrolysis pretreatment process has poor miscibility with ethanol, which often causes clogging of the slurry feeder in the continuous supercritical ethanol liquefaction process. The polarity indices of water and ethanol are 10.2 and 5.2, respectively, and strong acid hydrolyzed lignin has a property of being immiscible with any solvent with a polarity between 5.2 and 10.2. Therefore, strong acid hydrolysis lignin is not miscible with lignin in the slurry feeder, and only ethanol passes through the nozzle first, causing clogging.

In order to solve the above-mentioned problem, the present invention is to isolate lignin with improved compatibility with ethanol by improving the dissolution properties of lignin.

In addition, an object of the present invention is to provide a separation method capable of separating not only lignin with improved compatibility with ethanol, but also lignin that is not soluble in both water and ethanol. That is, an object of the present invention is to provide a method for separating two lignins having different dissolution properties from lignin.

A method for separating two lignins having different dissolution properties from lignin, the method comprising the steps of: a) reacting lignin with a eutectic solution; b) adding ethanol to the product of step a) and recovering the first precipitate; c) recovering a first liquid product excluding the first precipitate; d) adding water to the first liquid product and recovering a second precipitate; and e) recovering a second liquid product excluding the second precipitate.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, the first precipitate includes lignin insoluble in water and ethanol, and the second precipitate is not soluble in water but soluble in ethanol. It is characterized in that it contains lignin.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, in step a), the lignin is strong acid hydrolyzed lignin obtained by hydrolyzing lignocellulosic biomass with acid, or kraft lignin recovered from black liquor characterized by being.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, the eutectic solution in step a) comprises: a hydrogen bond acceptor comprising at least one selected from the group consisting of choline chloride, proline and betaine; And formic acid, acetic acid, propionic acid, lactic acid, glycerol, urea, monoethanolamine, diethanolamine, cocamide MEA and at least one selected from the group consisting of cocamide DEA It is a solution of a mixture of a hydrogen bond donor containing characterized.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, in step a), the eutectic solution is prepared by mixing a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:0.25 to 1:4 characterized by being

In the method of separating two lignins having different dissolution properties from lignin of the present invention, in step a), the lignin and the eutectic solution are mixed in a weight ratio of 1:8 to 1:10.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, the reaction temperature in step a) is 60° C. to 120° C., and the reaction time is 1 hour to 6 hours.

In the method of separating two lignins having different dissolution properties from lignin of the present invention, the method further comprising: f) removing water and ethanol from the second liquid product and recovering the eutectic solution after step e) characterized.

Strong acid hydrolysis lignin has a problem of clogging the slurry feeder when producing biofuel for power generation using ethanol because miscibility with water, ethanol, and organic solvents is insignificant. In the present invention, it is possible to separate lignin with increased miscibility with ethanol from such strongly acid hydrolyzed lignin. On the other hand, kraft lignin used as a raw material for biofuels or biochemicals also has a similar problem, but in the present invention, lignin with increased miscibility with ethanol can be separated from kraft lignin. In addition, in the present invention, it is possible to separate lignin that is not soluble in both water and ethanol, so that lignin having different dissolution properties can be used in various ways.

In the present invention, the yield of lignin having different dissolution characteristics can be controlled by changing the type, molar ratio, reaction conditions, etc. of the hydrogen bond acceptor and hydrogen bond donor of the eutectic solution. That is, it is possible to control the separation yield of lignin having a desired dissolution property.

1 is a process flow diagram of a method for separating two lignins having different dissolution properties from lignin according to an embodiment of the present invention.
Figure 2 is a graph showing the yield of the first precipitate and the second precipitate according to the reaction time and temperature.
3 is a FT-IR analysis result of strong acid hydrolysis lignin and kraft lignin.
4 and 5 are photographs confirming the solubility characteristics in water and ethanol according to the type of lignin.
6 is a graph showing the yield of the first precipitate and the second precipitate according to the type and temperature/time of the eutectic solution.
7 is a graph showing the yield of the first precipitate and the second precipitate according to the reaction time and temperature.
8 is a graph showing the yield of the first precipitate and the second precipitate according to the type of eutectic solution.
9 is a graph showing the yield of the first precipitate and the second precipitate according to the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor.
10 is a graph showing the yield of the first precipitate and the second precipitate according to the type of lignin and the type of eutectic solution.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings. The examples and terms used therein are not intended to limit the technology described in this document to a specific embodiment, but should be understood to include various modifications, equivalents, and/or substitutions of the embodiments.

1 is a process flow diagram of a method for separating two lignins having different dissolution properties from lignin according to an embodiment of the present invention.

Referring to FIG. 1 , in the method for separating two lignins having different dissolution properties from lignin according to an embodiment of the present invention, a) reacting a eutectic solution with lignin (S100), b) product of step a) Adding ethanol to and recovering the first precipitate (S200), c) recovering the first liquid product excluding the first precipitate (S300), d) adding water to the first liquid product and removing the second precipitate It may include the steps of recovering (S400) and e) recovering the second liquid product excluding the second precipitate (S500).

In the present invention, the first precipitate may include lignin that is not soluble in water and ethanol, and the second precipitate may include lignin that is not soluble in water and is soluble in ethanol. That is, two lignins having different dissolution properties can be obtained from the first precipitate and the second precipitate.

More specifically, in a) reacting the eutectic solution with lignin ( S100 ), strong acid hydrolyzed lignin obtained by hydrolyzing woody biomass with acid, or kraft lignin recovered from black liquor may be used.

Strong acid hydrolysis lignin has a problem of clogging the slurry feeder when producing biofuel for power generation using ethanol because miscibility with water, ethanol, and organic solvents is insignificant. In the present invention, it is possible to separate lignin with increased miscibility with ethanol from such strongly acid hydrolyzed lignin. On the other hand, kraft lignin used as a raw material for biofuels or biochemicals also has a similar problem, but in the present invention, lignin with increased miscibility with ethanol can be separated from kraft lignin. In addition, in the present invention, it is possible to separate lignin that is not soluble in both water and ethanol, so that lignin having different dissolution properties can be used in various ways.

On the other hand, a) the eutectic solution used in the step of reacting the eutectic solution with lignin (S100) includes a hydrogen bond acceptor (hydrogen bond acceptor) and a hydrogen bond donor (hydrogen bond donor).

A eutectic solution refers to an ionic solvent that forms a eutectic mixture having a melting point significantly lower than the melting point of each component. Eutectic solutions do not react with water, are mostly biodegradable, and are environmentally friendly alternative solvents.

According to various embodiments of the present invention, the hydrogen bond acceptor of the eutectic solution may include at least one selected from the group consisting of choline chloride, proline, and betaine. The hydrogen bond donor of the eutectic solution is formic acid, acetic acid, propanoic acid, lactic acid, glycerol, urea, monoethanolamine, di It may include at least one selected from the group consisting of ethanolamine (Diethanolamine), cocamide MEA, and cocamide DEA. Preferably, the eutectic solution may contain choline chloride as a hydrogen bond acceptor and propionic acid as a hydrogen bond acceptor.

On the other hand, the yield of the first precipitate and the second precipitate may vary depending on the type of the hydrogen bond acceptor and the hydrogen bond donor. That is, the eutectic solution can be prepared by changing the types of hydrogen bond acceptors and hydrogen bond acceptors according to the type or amount of lignin having desired dissolution properties.

For example, when the hydrogen bond acceptor is choline chloride and the hydrogen bond donor is urea, monoethanolamine, diethanolamine, cocamide ME or cocamide DA, the yield of the first precipitate may be higher than that of the second precipitate. there is. Therefore, when it is desired to recover more of the first precipitate, a eutectic solution is prepared using choline chloride as a hydrogen bond acceptor, urea, monoethanolamine, diethanolamine, cocamide ME or cocamide DA as a hydrogen bond acceptor can do. In other words, if you want to recover more lignin that is not soluble in water and ethanol, use choline chloride as a hydrogen bond acceptor and urea, monoethanolamine, diethanolamine, cocamide ME or cocamide DA as a hydrogen bond donor. A eutectic solution can be prepared.

At this time, the eutectic solution may be prepared by mixing the hydrogen bond acceptor and the hydrogen bond donor in a molar ratio of 1:0.25 to 1:4. For example, the eutectic solution may be prepared by mixing a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:4, 1:2, 1:1, 2:1, or 4:1. If it is out of this molar ratio, the reaction time may be long, and the reaction temperature may be too high in allowing the hydrogen bond acceptor and the hydrogen bond donor to mix and exist as a liquid.

On the other hand, the yield of the first precipitate and the second precipitate may vary depending on the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor. That is, the eutectic solution can be prepared by varying the molar ratio of the hydrogen bond acceptor and the hydrogen bond acceptor according to the type or amount of lignin to be recovered.

For example, when the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor is 1:4, the yield of the first precipitate may be higher than that of the second precipitate. Therefore, when it is desired to recover more of the first precipitate, a eutectic solution may be prepared by setting the molar ratio of the hydrogen bond acceptor and the hydrogen bond acceptor to 1:4. That is, when more lignin that is not soluble in water and ethanol is to be recovered, a eutectic solution can be prepared by setting the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor to 1:4.

On the other hand, when the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor is 1:2 or 1:1, the yield of the first precipitate is about 20% to 30%, and the yield of the second precipitate may be 65% to 76% . Accordingly, if more of the second precipitate is recovered than the first precipitate, and the first precipitate is also properly recovered, a molar ratio of the hydrogen bond acceptor and the hydrogen bond donor may be 1:2 or 1:1 to prepare a eutectic solution.

On the other hand, when the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor is 2:1 or 4:1, the yield of the second precipitate may be higher than that of the first precipitate. Therefore, when it is desired to recover more of the second precipitate, the eutectic solution may be prepared by setting the molar ratio of the hydrogen bond acceptor and the hydrogen bond acceptor to 2:1 or 4:1. That is, when more lignin that is not soluble in water but soluble in ethanol is to be recovered, the eutectic solution can be prepared by setting the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor to 2:1 or 4:1.

a) In the step of reacting the eutectic solution with lignin (S100), the lignin and the eutectic solution may be mixed in a weight ratio of 1:8 to 1:10. Since lignin is a solid powder and the eutectic solution is a viscous liquid, if the lignin content is increased above the above range, the viscosity increases and stirring and reaction are difficult. Additional processing costs are incurred. Preferably, the lignin and the eutectic solution may be mixed in a weight ratio of 1:9.

a) In the step (S100) of reacting the eutectic solution with lignin, the reaction temperature is 60 °C to 120 °C, and the reaction time may be 1 hour to 6 hours. Since the eutectic solution already exists in a liquid state between 60 ℃ and 100 ℃, there is an advantage that the reaction can be performed even at a relatively low temperature. Even when the temperature is raised to 120 °C, the reaction can be carried out in the absence of vapor pressure. The reaction time may vary depending on the physical properties of the lignin or the mixing conditions (type or molar ratio, etc.) of the eutectic solution, and the reaction is preferably carried out for 1 to 6 hours.

As described above, the yield of the first precipitate and the second precipitate may vary depending on the type, molar ratio, and reaction conditions of the hydrogen bond acceptor and the hydrogen bond donor in the eutectic solution. Therefore, in the present invention, the yield of lignin having different dissolution characteristics can be controlled by changing the type, molar ratio, reaction conditions, etc. of the hydrogen bond acceptor and the hydrogen bond donor of the eutectic solution. That is, it is possible to control the separation yield of lignin having a desired dissolution property.

Next, b) adding ethanol to the product of step a) and recovering the first precipitate (S200) may be performed. When ethanol is added to the product of step a), some of the lignin is precipitated and exists as a first precipitate. This first precipitate comprises lignin which is insoluble in water and ethanol. On the other hand, the other portion may be dissolved in ethanol to exist as a first liquid product, and c) recovering the first liquid product excluding the first precipitate (S300) may be performed.

Next, d) adding water to the first liquid product and recovering the second precipitate (S400) may be performed. When water is added to the first liquid product, some of the lignin is precipitated and is present as a second precipitate. This second precipitate comprises lignin which is not soluble in water but is soluble in ethanol. On the other hand, the other portion is dissolved in water to exist as a second liquid product, e) may proceed to the step (S500) of recovering the second liquid product excluding the second precipitate.

On the other hand, according to various embodiments of the present invention, f) recovering the eutectic solution from the second liquid product (S600) may be further included. The second liquid product may include water, ethanol, and a eutectic solution, and the eutectic solution may be recovered by removing water and ethanol through an evaporation process. The recovered eutectic solution can be reused, so it is economical.

Hereinafter, it will be described in detail through specific embodiments of the present invention.

However, the following examples are only for illustrating the present invention, and the present invention is not limited by the following examples.

Example 1: Separation yield of lignin according to reaction time and reaction temperature

A eutectic solution was used to selectively separate ethanol-miscible lignin from strong acid hydrolyzed lignin (GS) and kraft lignin (KR). The eutectic solution was mixed with choline chloride and propionic acid in a molar ratio of 1:2, and the solid-liquid ratio of lignin and the eutectic solution was set to a mass ratio of 1:9. Reaction conditions were compared as 80 °C for 6 hours, 100 °C for 3 hours, and 120 °C for 1 hour, respectively. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 2, the yield of the first precipitate in the strongly acid hydrolyzed lignin was 79.7% or more under all conditions. On the other hand, the yield of the second precipitate was the highest at 19.7% when the reaction was performed at 80 °C for 6 hours. In the case of kraft lignin, the yield of the second precipitate was 51.9% or more under all conditions, and the yield of the second precipitate was rapidly decreased at 120 °C.

Example 2: FT-IR analysis result of the second precipitate

FT-IR analysis was performed on the second precipitate recovered after the reaction with lignin and the eutectic solution. As a result, referring to FIG. 3 , it was found that kraft lignin had no significant change in functional groups before (KR) and after (KR') reaction. On the other hand, it can be seen that strong acid hydrolysis lignin has different functional groups before (GS) and after (GS') reaction, and it was confirmed that it has a functional group similar to that of kraft lignin after reaction. That is, the strongly acid hydrolyzed lignin has a property of not being soluble in ethanol, but it is possible to separate lignin having a property of being soluble in ethanol through the embodiment of the present invention.

Example 3: Comparison of solubility properties of lignin

Referring to FIG. 4 , both the strong acid hydrolyzed lignin and the kraft lignin had a property that the first precipitate did not dissolve in water and ethanol, and the second precipitate did not dissolve in water and it was confirmed that it had a property of being soluble in ethanol. Therefore, it can be seen that the separation of two lignins with different dissolution properties is possible using the eutectic solution. In particular, although strongly acid hydrolyzed lignin does not dissolve in ethanol, it is possible to partially separate lignin that is soluble in ethanol through a eutectic solution reaction.

On the other hand, for elemental analysis of lignin, the strong acid hydrolyzed lignin sample was washed three times with distilled water with a solid-liquid ratio of 1:10 (w/w) with stirring for 30 minutes. dried. The dried sample was pulverized using a ball mill, and only particles of 250 μm or less were selected and prepared. Referring to Table 1 below, the initial sulfur content of the strong acid hydrolyzed lignin was 1.58 wt%, and after washing three times with distilled water, the sulfur content was reduced to 0.20 wt%. Most of the inorganic sulfur components remaining in the sulfuric acid pretreatment of biomass for bioalcohol production were removed through the washing process. The oxygen content was as high as 36wt%, and the O/C ratio was 0.48.

N (wt%) C (wt%) H (wt%) S (wt%) O ^* (wt%) O/C (mol/mol) Strong acid hydrolysis lignin 0.11 56.70 5.49 1.58 36.12 0.48 [Washing] Strong acid hydrolysis lignin 0.06 57.28 5.61 0.20 36.85 0.48

* Oxygen content (O)=100-(N+C+H+S)

Meanwhile, the solubility of kraft lignin (KR), sodium lignin sulfonate (SA), pulping kraft lignin (PP), and strong acid hydrolyzed lignin (GS) in water and ethanol was investigated. As a result, referring to FIG. 5 , kraft lignin (KR) and pulping kraft lignin (PP) were not dissolved in water, but were dissolved in ethanol. Sodium lignin sulfonate (SA) was soluble in water and insoluble in ethanol. Strong acid hydrolyzed lignin (GS) exhibited insoluble properties in water and ethanol.

Example 4: Separation yield of lignin according to type of eutectic solution and reaction temperature/time

The separation yield of lignin according to the type of eutectic solution and the reaction temperature/time was confirmed. The eutectic solution was mixed with choline chloride as a hydrogen bond acceptor and lactic acid (L), propionic acid (P), formic acid (F) or urea (U) as a hydrogen bond donor at a molar ratio of 1:2, and the solid-liquid ratio of lignin and eutectic solution was set to a mass ratio of 1:9. The reaction conditions were compared for 6 hours at 80°C and 1 hour at 120°C. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 6 , the strong acid hydrolyzed lignin had a very high yield of the first precipitate, and the yield of the second precipitate was 20% or less. The yield of the second precipitate was the highest at 19.7% at 80°C for 6 hours among the reaction conditions. Among the three acids (lactic acid, propionic acid, formic acid), the yield was highest in propionic acid, and decreased in the order of formic acid and lactic acid. In a reaction at 120° C. for 1 hour in which urea was used as a hydrogen bond donor, the second precipitate was very low at 0.4%, so that lignin having miscibility with ethanol was hardly produced.

Example 5: Separation yield of lignin according to reaction temperature/time

The separation yield of lignin according to the reaction temperature/time was confirmed. The eutectic solution was mixed with choline chloride and propionic acid in a molar ratio of 1:2, and the solid-liquid ratio of lignin and the eutectic solution was set to a mass ratio of 1:9. Reaction conditions were compared at 80°C for 6 hours/12 hours and at 120°C for 6 hours/12 hours. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 7 , the yield of the first precipitate was very high in the strongly acid hydrolyzed lignin. The reaction for 6 hours at 80 °C and 120 °C showed a relatively high yield of the second precipitate. At 120° C. for 6 hours, the yield of the second precipitate was increased to 31.8%. However, when the reaction time was increased to 12 hours, it was found that the yield of the second precipitate decreased again.

Example 6: Separation yield of lignin according to the type of eutectic solution

The separation yield of lignin according to the type of eutectic solution was confirmed. The eutectic solution was mixed with choline chloride as a hydrogen bond acceptor and monoethanolamine, diethanolamine, cocamide MEA and cocamide DEA as a hydrogen bond donor at a molar ratio of 1:2, and the solid-liquid ratio of lignin and eutectic solution was mass ratio 1:9. The reaction conditions were 80° C. for 6 hours. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 8 , it was found that, for strong acid hydrolyzed lignin, the second precipitate did not occur with respect to hydrogen bond donors of amine and amide series. That is, lignin having miscibility with ethanol was hardly produced. The recovery rate of Cocamide MEA was very low, and the liquid phase except for the general second precipitate showed a yellowish color system, while the phenomenon of changing to milk color appeared to have other side reactions.

Example 7: Separation yield of lignin according to the molar ratio of hydrogen bond acceptor and hydrogen bond donor

The separation yield of lignin according to the molar ratio of the hydrogen bond acceptor and the hydrogen bond donor was confirmed. The eutectic solution was mixed with choline chloride and propionic acid in a molar ratio of 1:4, 1:2, 1:1, 2:1, and 4:1, and the solid-liquid ratio of lignin and the eutectic solution was set to a mass ratio of 1:9. The reaction conditions were 100° C. for 3 hours. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 9 , it was observed that the yield of the first precipitate gradually decreased as the relative ratio of choline chloride to kraft lignin increased. When the molar ratio was 2:1 and 4:1, the yield of the first precipitate was reduced to a very low level of 3%. On the other hand, it was confirmed that the yield of the second precipitate gradually increased.

Example 8: Separation yield of lignin according to the type of lignin and the type of eutectic solution

The separation yield of lignin according to the type of lignin and the type of eutectic solution was confirmed. That is, for each strong acid hydrolyzed lignin (GS) and kraft lignin (KR), the eutectic solution contains cholineCl, proline, betaine as a hydrogen bond acceptor, and propionic acid as a hydrogen bond acceptor in a molar ratio of 1 It was mixed under the condition of :2, and the solid-liquid ratio of the lignin and the eutectic solution was 1:9 by mass. The reaction conditions were 120° C. for 1 hour. After completion of the reaction, a first precipitate precipitated by adding ethanol was recovered, and a second precipitate precipitated by adding water to the remaining liquid portion was recovered.

As a result, referring to FIG. 10 , the strong acid hydrolyzed lignin (GS) had a very high yield of the first precipitate. In addition, 13.4% of the second precipitate was recovered when choline chloride was used as a hydrogen bond acceptor, but almost no second precipitate was generated when proline and betaine were used. That is, lignin having miscibility with ethanol was hardly generated.

On the other hand, in Kraft lignin (KR), when choline chloride was used as a hydrogen bond acceptor, the yield of the second precipitate was 51.9%, whereas when proline was used, it was 13.9%, the lowest among the three hydrogen bond acceptors, and betaine was used It was found to be 35.0%.

Features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiments have been described above, these are merely examples and do not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiments may be implemented by modification. And differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (8)

a) reacting the eutectic solution with lignin;
b) adding ethanol to the product of step a) and recovering the first precipitate;
c) recovering a first liquid product excluding the first precipitate;
d) adding water to the first liquid product and recovering a second precipitate; and
e) a method for separating two lignins having different dissolution properties from lignin, comprising the step of recovering a second liquid product excluding the second precipitate. According to claim 1,
The first precipitate comprises lignin insoluble in water and ethanol;
The method of separating two lignins having different dissolution properties from lignin, characterized in that the second precipitate includes lignin that is not soluble in water but is soluble in ethanol. According to claim 1,
In step a), the lignin is strong acid hydrolyzed lignin obtained by hydrolyzing woody biomass with acid, or kraft lignin recovered from black liquor. A method for separating two lignins having different dissolution properties from lignin. According to claim 1,
In step a), the eutectic solution is
a hydrogen bond acceptor comprising at least one selected from the group consisting of choline chloride, proline and betaine; and
Formic acid, acetic acid, propionic acid, lactic acid, glycerol, urea, monoethanolamine, diethanolamine, cocamide MEA and at least one selected from the group consisting of cocamide DEA It is characterized in that the solution is a mixture of a hydrogen bond donor A method for separating two lignins with different dissolution properties from lignin. According to claim 1,
In step a), the eutectic solution is prepared by mixing a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:0.25 to 1:4. A method for separating two lignins having different dissolution properties from lignin. According to claim 1,
A method for separating two lignins having different dissolution properties from lignin, characterized in that in step a), the lignin and the eutectic solution are mixed in a weight ratio of 1:8 to 1:10. According to claim 1,
A method for separating two lignins having different dissolution properties from lignin, characterized in that in step a), the reaction temperature is 60° C. to 120° C., and the reaction time is 1 hour to 6 hours. The method of claim 1,
After the step e), f) removing water and ethanol from the second liquid product and recovering a eutectic solution. A method for separating two lignins having different dissolution properties from lignin.

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