JP6108559B2 - Method for producing lignin from biomass using lignin-soluble ionic liquid, and method for producing lignin, hemicellulose, and cellulose - Google Patents

Description

  The present invention relates to a method for producing lignin from biomass using a lignin-soluble ionic liquid, and lignin, hemicellulose, and a method for producing cellulose.

  Lignin is a macromolecule with a three-dimensional network structure formed by complex cross-linking of phenylpropanoids with aromatic rings. In wood that contains a lot of lignin, cellulose and lignin form a complex complex. Therefore, it was difficult to extract pure lignin. Conventionally known methods for solubilizing lignin from wood include heating with a phenol solution in sulfuric acid or hydrolysis with subcritical water at 300 ° C. under a high pressure of 22 MPa.

  In recent years, a method using an ionic liquid as a solvent for dissolving lignin has been proposed (Non-patent Document 1). Non-Patent Document 1 describes a method of dissolving bamboo powder with an imidazolium salt ionic liquid.

Nawshad Muhammad et al., Appl Biochem Biotechnol, 2011, 165, 998-1009.

However, the method of heating with a phenol solution in sulfuric acid has problems in terms of cost and safety, and the method of hydrolyzing with subcritical water is a clean method, but it has a large-scale treatment device and has a problem in terms of energy balance. In Non-Patent Document 1, only a small amount is dissolved, and the extraction solvent is a mixed solvent of acetone and water, so there is a concern about the burden on the environment.
The present invention has been made in view of the above circumstances, and provides an ionic liquid having high lignin solubility and a lignin production method for producing lignin from biomass safely and at low cost with a simple apparatus. Is.

According to the present invention, the following chemical formula (1)
(In the formula ^(1), R 1, ^{R 3} may be different also identical, represent an alkyl group, an alkenyl group having 2 to 6 carbon atoms having 1 to 6 carbon atoms, ^{R 2} is one or more It may be substituted, and represents a hydrogen atom, an amino group, a hydroxy group, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group, and Y represents CH ₂ , O, S N represents the number of ring members, n = 1, 2 and X represents an anion derived from an amino acid, and the alkyl group, alkenyl group, and alkoxy group are substituted with halogen, amino group, phenyl A lignin-soluble ionic liquid represented by a group, a cycloalkyl group, an alkoxy group, or a hydroxy group.

  The inventors of the present invention conducted intensive studies on the development of an ionic liquid that dissolves lignin. The imidazolium salt ionic liquid that has been used conventionally has poor solubility of lignin, whereas the chemical formula (1) It was found that lignin can be easily extracted from biomass by using the expressed ionic liquid. Then, it was found that lignin can be produced safely without requiring high-temperature and high-pressure conditions, and the present invention has been completed.

  According to the experiments by the present inventors, the solubility of lignin was higher when pyrrolidinium salt or piperidinium salt was used than when imidazolium salt or ammonium salt was used as the cation. Moreover, it turned out that it becomes an ionic liquid with high lignin solubility by using an amino acid for an anion.

FIG. 1 shows the results of measuring XRD of precipitated lignin and standard lignin obtained in the lignin dissolution experiment of the present invention. FIG. 2 is an experimental example for explaining the method for producing lignin of the present invention. FIG. 3 shows the result of XRD measurement of precipitated lignin obtained by the lignin production method of the present invention, undissolved cellulose and a sample. FIG. 4 shows the results of IR measurement of precipitated lignin and standard lignin obtained by the lignin production method of the present invention. FIG. 5 is an experimental example for explaining the production method of lignin and the method for separating cellulose and hemicellulose of the present invention. FIG. 6 shows the results of measuring XRD and IR of lignin obtained from cedar chips and standard lignin by the lignin production method of the present invention. FIG. 7 shows the results of measurement of XRD and IR of cellulose obtained from cedar chips by the lignin production method of the present invention and standard cellulose. FIG. 8 shows the results of measuring XRD and IR of hemicellulose obtained from cedar chips and cellulose obtained from cedar chips by the lignin production method of the present invention. FIG. 9 shows the results of measuring MALDI-QIT-TOF MS of lignin obtained from cedar chips by the lignin production method of the present invention. FIG. 10 shows the results of measuring MALDI-QIT-TOF MS of lignin obtained from cedar, hinoki and lawan chips by the lignin production method of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail.
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<< 1. Lignin-soluble ionic liquid >>
<< 2. Synthesis of ionic liquid >>
<2-1. Chlorination process>
<2-2. Salt exchange process>
(Ion exchange resin method)
(Silver oxide / methanol method)
<< 3. Lignin production method >>
<3-1. Process (1) Lignin dissolution process>
(biomass)
<3-2. Step (2) Solid-liquid separation step>
(Re-extraction process)
<3-3. Step (3) Lignin Precipitation Step>
<3-4. Cellulose / hemicellulose separation process>
(Process (4) hemicellulose extraction process)
(Step (5) cellulose / hemicellulose separation step)
(Process (6) Cellulose / hemicellulose recovery process)
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<< 1. Lignin-soluble ionic liquid >>
The ionic liquid having lignin solubility is represented by the following chemical formula (1).

In formula (1), R ¹ and R ³ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and R ² is one or more substituted. And represents a hydrogen atom, an amino group, a hydroxy group, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group, and Y represents CH ₂ , O, and S. N represents the number of ring members, n = 1, 2 and X represents an anion derived from amino acid. The alkyl group, alkenyl group, and alkoxy group may have one or more of halogen, amino group, phenyl group, cycloalkyl group, alkoxy group, and hydroxy group as a substituent.

  Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and a halogen, an amino group, a phenyl group, a cycloalkyl group, and an alkoxy group, respectively. Alternatively, one or more hydroxy groups may be substituted.

  Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group, and a 5-hexenyl group. A halogen, an amino group, a phenyl group, and a cycloalkyl group, respectively. In addition, one or more of an alkoxy group or a hydroxy group may be substituted.

  Examples of the halogen include a fluoro group, a chloro group, and a bromo group. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkoxy group include a methoxy group and an ethoxy group.

Among these, as R ¹ and R ³ , a combination of an alkyl group having 1 to 6 carbon atoms and an alkoxyalkyl group is preferable, and a combination of a methyl group and a 2-methoxyethyl group is particularly preferable, and R ² is preferably a hydrogen atom.

Y is preferably CH ₂ and n is preferably n = 1.

  X is a compound having an amino group and a carboxyl group on the same carbon, and examples thereof include L-amino acids and D-amino acids. Among these, L-amino acids are preferable, and lysine and arginine are particularly preferable.

<< 2. Synthesis of ionic liquid >>
The synthesis of the ionic liquid is roughly divided into the following two steps: <2-1. Chlorination step>, <2-2. Synthesized in the salt exchange step>.

<2-1. Chlorination process>
In the chlorination step, a pyrrolidine derivative and a compound having halogen at the terminal are mixed to synthesize a pyrrolidinium salt having halogen as an anion. Specifically, for example, a pyrrolidine derivative and a compound having a halogen at the terminal are placed in a reaction vessel and mixed at 40 to 160 ° C. Mixing may be performed at normal pressure, or may be performed under pressure using a pressure vessel. The reaction vessel is not particularly limited, but glass, Teflon (registered trademark), or the like can be used. The mixing method is not particularly limited, but a stirrer or a shaker may be used.

  The reaction temperature in the chlorination step is 40 to 160 ° C, preferably 60 to 100 ° C. This is because if the temperature of the chlorination step is too low, the reaction does not proceed, and if the temperature is too high, the raw material is vaporized and the ionic liquid is colored. Specifically, this temperature is, for example, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, or 160 ° C., and between any two of the numerical values exemplified here. It may be within the range.

  Although the reaction time of a chlorination process is not specifically limited, For example, it is 6 to 48 hours, Preferably it is 12 to 24 hours. Specifically, this time is, for example, 6, 7, 8, 9, 10, 11, 12, 15, 18, 21, 24, 27, 30, 36, 42, or 48 hours. It may be within the range between any two.

  You may perform the washing | cleaning process which adds a washing | cleaning solvent and wash | cleans after the chlorination process. The washing step is a step performed to remove unreacted substrate. The washing solvent is not particularly limited, and examples thereof include hexane, ethyl acetate, acetonitrile, and mixed solvents thereof, and any solvent that dissolves a substrate and does not dissolve a pyrrolidinium salt having a halogen as an anion may be used.

<2-2. Salt exchange process>
In the salt exchange step, the anionic halogen is exchanged for the target amino acid.
There are two methods of synthesizing the ionic liquid of the above chemical formula (1): (ion exchange resin method) and (silver oxide / methanol method), and the ion exchange resin used is reused in (ion exchange resin method) The cost is low because it is possible, and the (silver oxide / methanol method) has advantages that are suitable for mass synthesis. The products obtained by the (ion exchange resin method) and the (silver oxide / methanol method) are exactly the same, and a synthesis method can be selected according to the situation taking into account the respective advantages.

(Ion exchange resin method)
In the ion exchange resin method, the above <2-1. The pyrrolidinium salt in which the anion is an amino acid is eliminated by passing the pyrrolidinium salt having halogen as an anion obtained in the chlorination step> by exchanging the anion with a hydroxide ion and subsequently reacting with an amino acid. An ionic liquid can be synthesized. Specifically, for example, an aqueous pyrrolidinium salt solution is passed through an ion exchange resin and mixed with an aqueous amino acid solution. Thereafter, water is distilled off. The ion exchange resin is not particularly limited, but may be an anion exchange resin as long as it can exchange an anion from a halogen to a hydroxide ion. Although the reaction vessel is not particularly limited, glass, Teflon, plastic, or the like can be used. The mixing method is not particularly limited, but a stirrer or a shaker may be used.

The method of salt exchange using an ion exchange resin is not particularly limited, but a method of filling a cylindrical or funnel-shaped container with an ion exchange resin and letting it fall naturally or applying pressure thereto, beaker or flask A method of mixing and mixing may be used as long as the anion is exchanged from halogen to hydroxide ion.
Specifically, for example, salt exchange can be performed by filling a glass column with an ion exchange resin and passing a pyrrolidinium salt through natural dropping therethrough.

  The reaction temperature of the ion exchange resin method is −10 to 30 ° C., preferably 0 to 10 ° C. This is because the reaction does not proceed when the temperature of the ion exchange resin method is too low, and the raw material is broken when the temperature is too high. Specifically, this temperature is, for example, −10, −5, 0, 5, 10, 20 or 30 ° C., and may be within a range between any two of the numerical values exemplified here.

  The reaction time of the ion exchange resin method is not particularly limited, but is, for example, 6 to 48 hours, preferably 12 to 24 hours. Specifically, this time is, for example, 6, 7, 8, 9, 10, 11, 12, 15, 18, 21, 24, 27, 30, 36, 42, or 48 hours. It may be within the range between any two.

In the ion exchange resin method, a washing and separating step may be performed after water is distilled off. The washing / separating step is a step performed for removing unreacted substrate. The washing solvent is not particularly limited, and examples thereof include acetonitrile, methanol, acetone, and a mixed solvent thereof. Any solvent that dissolves the pyrrolidinium salt ionic liquid and does not dissolve the substrate may be used.
The separation method is not particularly limited, and for example, a method such as filtration or centrifugation can be used. Examples of the filtration method include natural filtration, vacuum filtration, and pressure filtration.
A pyrrolidinium salt ionic liquid can be obtained by removing the unreacted substrate in the washing and separating step and distilling off the washing solvent.

(Silver oxide / methanol method)
In the silver oxide / methanol method, the above <2-1. The pyrrolidinium salt having halogen as an anion obtained in the chlorination step is reacted in methanol to exchange the anion for methoxide, and then reacted with an amino acid to be eliminated as methanol, and the anion is an amino acid pyrrolidinium salt An ionic liquid can be synthesized. Specifically, for example, pyrrolidinium salt, silver oxide, and methanol are mixed to separate a solid content, an amino acid is mixed into the separated reaction solution, the solid content is separated, and the solvent is distilled off. The reaction vessel is not particularly limited, but glass or Teflon can be used. The mixing method is not particularly limited, but a stirrer or a shaker may be used.

  Although the method of isolate | separating solid content is not specifically limited, For example, methods, such as filtration and centrifugation, can be used. Examples of the filtration method include natural filtration, vacuum filtration, and pressure filtration.

  The reaction temperature in the silver oxide / methanol method is 0 to 50 ° C., preferably 15 to 35 ° C. Specifically, this temperature is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 ° C., and is within a range between any two of the numerical values exemplified here. There may be.

  The reaction time in the silver oxide / methanol method is not particularly limited, but is, for example, 12 to 72 hours, and preferably 24 to 48 hours. This time is specifically, for example, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, or 72 hours, and is within a range between any two of the numerical values exemplified here. There may be.

<< 3. Lignin production method >>
The method for producing lignin according to one embodiment of the present invention comprises (1) mixing ionic liquid and biomass, (2) separating the ionic liquid phase and the residue from the mixed liquid obtained in the step (1), (3 ) A step of adding a lignin precipitation solvent to the ionic liquid phase obtained in the step (2) to precipitate and separate lignin is provided.

<3-1. Process (1) Lignin dissolution process>
In the step (1), the ionic liquid and biomass are mixed and lignin is dissolved in the ionic liquid. Specifically, for example, an ionic liquid and biomass are put into a reaction vessel and mixed at 0 to 120 ° C. Mixing may be performed at normal pressure, or may be performed under reduced pressure or pressurized conditions using a pressure vessel. The reaction vessel is not particularly limited, but glass, Teflon, plastic, or the like can be used. The mixing method is not particularly limited, but a stirrer or a shaker may be used. In step (1), lignin in the biomass is dissolved in the ionic liquid, and cellulose and hemicellulose are not dissolved but remain as a residue.

  The reaction temperature in the lignin dissolution step is 0 to 120 ° C, preferably 20 to 100 ° C. This is because the reaction does not proceed when the temperature of the lignin dissolving step is too low, and the ionic liquid is decomposed when the temperature is too high. Specifically, the temperature of the lignin dissolution step is, for example, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, or 120 ° C, and any of the numerical values exemplified here It may be within a range between the two.

  Although the ionic liquid used in the present invention also dissolves cellulose, the dissolution requires a temperature of 80 ° C. or higher. On the other hand, lignin can be dissolved at 60 ° C to 80 ° C. For this reason, selective extraction of a lignin is attained by adding biomass to the ionic liquid of this invention, and stirring at 80 degrees C or less.

  Although the reaction time of a lignin dissolution process is not specifically limited, For example, it is 0.5 to 24 hours, Preferably it is 6 to 12 hours. This time is specifically 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 18, 21, or 24 hours, for example, It may be within a range between any two of the numerical values exemplified in.

(biomass)
The biomass is not particularly limited as long as it is a plant-based biomass, and examples thereof include woody or herbaceous plant materials. Examples of this wood-based raw material include thinned wood, wood-processed scrap house waste, etc. is there.

<3-2. Step (2) Solid-liquid separation step>
In the step (2), the ionic liquid phase and the residue are separated from the mixed liquid obtained in the step (1) using various solid-liquid separation methods. The residue has a solid or gel-like shape. The solid-liquid separation method is not particularly limited, and for example, a method such as filtration or centrifugation can be used. Examples of the filtration method include natural filtration, vacuum filtration, and pressure filtration.
Specifically, for example, separation can be performed by removing the ionic liquid separated by centrifugation with a pipette or the like.

(Re-extraction process)
After the solid-liquid separation step, a re-extraction step of separating the ionic liquid from the residue by adding the ionic liquid and performing solid-liquid separation may be performed a plurality of times. The re-extraction step is a step performed to remove the ionic liquid in which lignin is completely dissolved from the residue. The ionic liquid used for the re-extraction is not particularly limited, but preferably the same ionic liquid as that used in the lignin dissolution step is used. As the re-extraction method, for example, a method in which an ionic liquid is added again, mixed with the residue, and separated by centrifugation can be used.
The reaction temperature of the re-extraction step is <3-1. The reaction time is not particularly limited as in the step (1) lignin dissolution step>, but is, for example, 0.5 to 3 hours, preferably 1 to 2 hours. Specifically, this time is, for example, 0.5, 1, 1.5, 2, 2.5, or 3 hours, and may be within a range between any two of the numerical values exemplified here. .

  Note that the re-extraction step is performed in order to improve the extraction efficiency of lignin, and since there is no particularly large yield fluctuation, the re-extraction step can be omitted in a timely manner.

<3-3. Step (3) Lignin Precipitation Step>
In step (3), a lignin precipitation solvent is added to the ionic liquid phase obtained in step (2) to precipitate and separate lignin. The lignin precipitation solvent is not particularly limited, and alcohols such as methanol, ethanol, and propanol, water, and acetone can be used as long as they dissolve ionic liquid and do not dissolve lignin.

The method for separating lignin and ionic liquid is not particularly limited, and for example, methods such as filtration and centrifugation can be used. Examples of the filtration method include natural filtration, vacuum filtration, and pressure filtration.
Specifically, for example, separation can be performed by removing the ionic liquid separated by centrifugation with a pipette or the like.

<3-4. Cellulose / hemicellulose separation process>
In the cellulose / hemicellulose separation step, a basic aqueous solution is added to the residue obtained in step (2) to prepare a mixed solution, and the mixed solution obtained in step (4) is separated into a liquid phase and a residue. Step (5) and a step (6) of recovering hemicellulose from the liquid phase obtained in step (5) and recovering cellulose from the residue obtained in step (5).

(Process (4) hemicellulose extraction process)
In step (4), a basic aqueous solution is added to the residue obtained in step (2) to prepare a mixed solution, and hemicellulose is dissolved in the basic aqueous solution. The basic aqueous solution is not particularly limited, but aqueous solutions of various concentrations of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (CaOH), etc. can be used, dissolving hemicellulose, Any solution that does not dissolve may be used. In particular, a 0.1 M aqueous sodium hydroxide solution is preferred.
Step (4) is <3-1. It can be performed by the same method as in step (1) lignin dissolution step>.

(Step (5) cellulose / hemicellulose separation step)
In step (5), the liquid mixture obtained in step (4) is separated into a liquid phase and a residue using various solid-liquid separation methods. The solid-liquid separation method is <3-2. It can be performed by the same method as in step (2) solid-liquid separation step>.

(Process (6) Cellulose / hemicellulose recovery process)
In step (6), hemicellulose is recovered from the liquid phase obtained in step (5), and cellulose is recovered from the residue obtained in step (5).

  In the method for recovering hemicellulose, hemicellulose can be recovered by drying the liquid phase obtained in step (5), washing with water, and drying again.

  The method for recovering cellulose can purify hemicellulose by washing the residue obtained in step (5) with water and drying it.

  Although the drying method in (Step (6) cellulose / hemicellulose recovery step) is not particularly limited, for example, methods such as natural drying, vacuum drying, and heat drying can be used.

  The water washing method in (Step (6) cellulose / hemicellulose recovery step) is not particularly limited, and for example, a method of stirring with a stirrer or a shaker and removing the aqueous phase with a pipette or the like can be used.

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<< 1. Synthesis of lignin-soluble ionic liquid >>
<1-1. Chlorination process>
<1-2. Salt exchange process>
(Ion exchange resin method)
(Silver oxide / methanol method)
<1-3. Synthesis of various L-amino acid ionic liquids>
<< 2. Lignin dissolution experiment >>
<2-1. Change in solubility due to differences in cations>
<2-2. Change in solubility due to difference in anion>
<< 3. Biomass dissolution experiment >>
<3-1. Cedar chip melting experiment>
<3-2. Comparison with standard products>
<3-3. Lignin / cellulose / hemicellulose separation experiment>
<3-4. Change in solubility due to differences in cations>
<< 4. Recycling ionic liquid >>
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<< 1. Synthesis of lignin-soluble ionic liquid >>
A lignin-soluble ionic liquid was synthesized according to the following method.

<1-1. Chlorination process>
A chlorination reaction represented by the following chemical formula (2) was performed.
The two-necked eggplant flask was purged with argon, 14.4 ml of 1-methylpyrrolidine was weighed, 13.6 ml of 2-bromoethyl methyl ether was added dropwise, and the mixture was stirred at 80 ° C. for 24 hours with a magnetic stirrer (500 rpm). After stirring, the mixture was washed with a hexane / ethyl acetate mixed solvent (7/1), the unreacted substrate and the hexane / ethyl acetate mixed solvent were distilled off, and dried under reduced pressure to give 1- (2-methoxyethyl)- 1-methylpyrrolidinium bromide was obtained with a yield of 98%.

<1-2. Salt exchange process>
Using an ion exchange method and a silver oxide / methanol method, a salt exchange reaction from bromide to amino acid was performed for the anion represented by the following chemical formula (3) and chemical formula (4), respectively. The reaction conditions are as follows.

(Ion exchange resin method)
<1-1. After passing 1.5 g of an aqueous solution (water: 10 ml) of 1- (2-methoxyethyl) -1-methylpyrrolidinium bromide obtained in the chlorination step> through an ion exchange resin (manufactured by Organo Corporation: Amberlite IRA400CL) The solution was dropped into an aqueous lysine solution (lysine: 1.17 g, water: 50 ml) at 0 ° C. and stirred for 24 hours with a magnetic stirrer (500 rpm). Water was distilled off, washed once with a mixed solvent of acetonitrile / methanol (9/1), and filtered. Thereafter, the acetonitrile / methanol mixed solvent was distilled off, followed by drying under reduced pressure to obtain N-methyl-N- (2-methoxyethyl) pyrrolidinium lysine ([P _1ME ] [Lys]) in a yield of 96%. . The results of measurement of NMR and IR are as follows.
¹ H NMR (500 MHz, ppm, CD ₃ OD, J = Hz) 1.35-1.45 (6H, m), 2.17 (4H, s), 2.58 (2H, t, J = 6.9Hz), 3.25 (1H, t , J = 1.8), 3.30 (2H, br), 3.35 (2H, br), 3.38 (3H, s), 3.53-3.56 (8H, m), 3.77 (2H, s); ¹³ C NMR (125 MHz, (ppm, CD ₃ OD, J = Hz) 182.49, 67.63, 66.31, 64.40, 59.21, 57.61, 49.34, 42.46, 36.62, 33.94, 24.31, 22.43; IR (neat, cm ^-1 ) 3347, 3279, 2930, 2856, 2815, 2063, 1582, 1462, 1396, 1123, 1038

(Silver oxide / methanol method)
<1-1. 30.8 g of 1- (2-methoxyethyl) -1-methylpyrrolidinium bromide obtained in the chlorination step> and 50 ml of methanol were mixed, and 25.6 g of silver (I) oxide was added over 1 hour. For 24 hours with a magnetic stirrer (500 rpm). The reaction solution was filtered, and the residue was washed with 50 ml of methanol to obtain a filtrate washing solution. To this filtrate, 23.9 g of (L) -α-lysine was added at room temperature over 15 minutes, and stirred at room temperature for 48 hours with a magnetic stirrer (500 rpm). The suspended solid was separated by filtration, and the filtrate was concentrated and dried to obtain 70.0 g of a concentrate. Toluene was added to the concentrate, and the filtrate was concentrated to dryness under reduced pressure to obtain _{35.8 g of} N-methyl-N- (2-methoxyethyl) pyrrolidinium lysine ([P _1ME ] [Lys]) at a yield of 91%. Got in.

<Synthesis of 1-3.20 types of L-amino acid ionic liquids>
Table 1 shows the results of synthesizing ionic liquids using 20 types of L-amino acids by the same synthesis method as the above (ion exchange resin method).
From Table 1, it can be seen that ionic liquids can be synthesized in good yield with all amino acids. Here, the cationic N-methyl-N- (2-methoxyethyl) _{pyrrolidinium} is expressed as [P _1ME ], and the anionic amino acid is described in three letters.

<< 2. Lignin dissolution experiment >>
To 1 g of ionic liquid ([P _1ME ] [Lys]), 0.05 g of standard lignin (lignin, alkali: 471003-100G manufactured by ALDRICH) is weighed into a vial tube to give a 5 wt% mixed solution at room temperature for 5 hours. It stirred with the magnetic stirrer (500 rpm), and it was visually confirming whether it melt | dissolved, and if it melt | dissolved, 0.05g of lignins were added further and the solubility was investigated. When it was confirmed that it did not dissolve at room temperature, the temperature was raised successively to 60 ° C. and 100 ° C. to examine the solubility. The mixture was stirred at 60 ° C. and 100 ° C. for 1 hour.
When it was confirmed that it did not dissolve even at 100 ° C., it was diluted with ethanol to precipitate lignin, and centrifuged at 3500 rpm for 5 minutes to separate the ionic liquid and lignin.

FIG. 1 shows the results of XRD measurement of the precipitated lignin and comparing the pattern with a standard lignin (lignin, alkali: 471003-100G manufactured by ALDRICH).
As is clear from the results of FIG. 1, it was found that the structure of lignin did not change before and after dissolution.

<2-1. Change in solubility due to differences in cations>
Above << 1. Synthesis of Lignin-Soluble Ionic Liquid >> Five types of ionic liquids represented by the following chemical formula (5) were synthesized by changing the substrate by the same synthesis method as in >>. N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium alanine ([N _221ME ] [Ala]) was synthesized using diethylmethylamine as a substrate, and N, N-diethyl-N- Methyl-N- (2- (methylthio) ethyl) ammonium alanine ([N _221MTE ] [Ala]) was synthesized using diethylmethylamine and 2-chloroethylmethyl sulfide as substrates and N, N-diethyl-2 -Methoxy-N- (2-methoxyethyl) ethaneammonium alanine ([N22 _{(ME) 2} ] [Ala]) was synthesized using diethyl (2-methoxyethyl) amine as the substrate, and N-ethyl-2 -Methoxy-N, N-bis (2-methoxyethyl) ethaneammonium alanine ([N _{2 (ME) 3} ] [Ala]) is ethyl bis ( 2- (methoxyethyl) amine was synthesized using 3- (2-methoxyethyl) -1-methylimidazolium alanine ([(2-ME) mim] [Ala]) using 1-methylimidazole as a substrate And synthesized.

[P _1ME ] [Ala] synthesized in the above <1-3.20 kinds of L-amino acid ionic liquids> and the five ionic liquids represented by the chemical formula (5) are described in the above << 2. Table 2 shows the results of examining the solubility of lignin in the same manner as in the lignin dissolution experiment >>.
From the results in Table 2, it was found that [P _1ME ] [Ala] dissolves lignin most.

Furthermore, [P _1ME ] [Lys] synthesized in the above <1-3.20 kinds of L-amino acid ionic liquid> and N-methyl-N- (2-methoxyethyl) represented by the chemical formula (6) For piperidinium lysine ([Py _1ME ] [Lys]), the above << 2. Table 3 shows the results of examining the solubility of lignin by the same operation as lignin dissolution experiment >>. N-methyl-N- (2-methoxyethyl) piperidinium lysine ([Py _1ME ] [Lys]) uses N-methyl piperidine as a substrate, and <1-1. It was synthesized by a method similar to the chlorination step> and (ion exchange resin method).
From the results in Table 3, it was found that both [P _1ME ] [Lys] and [Py _1ME ] [Lys] exhibit high lignin solubility.

<2-2. Change in solubility due to difference in anion>
Table 4 shows the results of a lignin dissolution experiment using 20 types of ionic liquids synthesized in <1-3.20 types of L-amino acid ionic liquids> described above.
From the results in Table 4, it was found that lignin was most dissolved in lysine and arginine, and then dissolved well in phenylalanine and tyrosine. From these results, lysine and arginine have an amino group at the terminal, and this amino group forms a hydrogen bond between lignin and cellulose, and it seems that the effect of peeling lignin from cellulose is high. Phenylalanine and tyrosine both have a benzene ring, and it seems that lignin is easily compatible with ionic liquids and has high solubility due to the stacking interaction between the benzene ring and the benzene ring of lignin.

<< 3. Biomass dissolution experiment >>
As shown in FIG. 2, the above << 1. Synthesis experiment of biomass was performed using N-methyl-N- (2-methoxyethyl) pyrrolidinium lysine ([P _1ME ] [Lys]) synthesized by synthesis of lignin-soluble ionic liquid >>. Cedar chips were used as biomass, and sawdust was used to cut cedar boards with a saw.

<3-1. Cedar chip melting experiment>
_Cereal chips (0.1 g) were _{weighed in} 1 g of ionic liquid ([P _1ME ] [Lys]) in a Spitz tube to _{prepare a} mixed solution, and stirred at 60 ° C. for 12 hours. Subsequently, after centrifuging, the ionic liquid layer was recovered. Further, 0.3 g of ionic liquid was added to the Spitz tube, and the operation of stirring at 60 ° C. for 1 hour, centrifugation, and recovery of the ionic liquid layer was performed twice. The collected ionic liquid layer was diluted with ethanol to precipitate lignin. Subsequently, the lignin was separated by centrifugation, dried under vacuum, and the mass was measured.

  In the cedar chip dissolution experiment, 16 wt% lignin per cedar chip was successfully recovered. Since cedar contains about 20% lignin, it was found that almost all can be recovered.

<3-2. Comparison with standard products>
<3-1. The results of measuring the XRD of the precipitated lignin obtained in Cedar Chip Dissolution Experiment> and the undissolved residue are shown in FIG.
From the results shown in FIG. 3, the precipitated lignin does not have a sharp peak like that of a standard cellulose (Avicel PH-101: 11365 manufactured by Fluka), and is similar to a standard lignin (lignin, alkaline: 471003-100G manufactured by ALDRICH). I found out. The residue of undissolved residue was found to have a peak with a pattern similar to that of standard cellulose (Avicel PH-101: 11365 manufactured by Fluka), and the residue of undissolved was found to be type I cellulose.

In addition, <3-1. FIG. 4 shows the results of IR measurement of the precipitated lignin obtained in the cedar chip dissolution experiment.
From the results of FIG. 4, it can be seen that the pattern of IR is similar between precipitated lignin and standard lignin (lignin, alkali: 471003-100G manufactured by ALDRICH).

From the results of FIG. 3 and FIG. 4, by conducting a dissolution experiment using an ionic liquid ([P _1ME ] [Lys]), only lignin can be extracted from the cedar chips, and lignin is removed from the undissolved residue. It was found to be cellulose.

<3-3. Lignin / cellulose / hemicellulose separation experiment>
As shown in FIG. 5, the above <3-1. In the same manner as in the cedar chip dissolution experiment, the amount was increased 10 times to separate 0.131 g of lignin. Residue D remaining in the test tube after centrifugation was washed three times with water, and hemicellulose was extracted with a 0.1 M aqueous sodium solution solution to obtain extract F. The obtained extract F was vacuum-dried, washed with water, and vacuum-dried again to obtain 0.093 g of hemicellulose. Furthermore, 0.665g of cellulose was obtained by wash | cleaning the residue E which remained after extracting hemicellulose from the residue D 3 times with water, and performing vacuum drying.

  <3-3. The results of measuring XRD and IR of lignin, cellulose, and hemicellulose obtained in <Lignin / cellulose / hemicellulose separation experiment> are shown in FIG. 6, FIG. 7, and FIG.

From the results of FIG. 6, it can be seen that the XRD and IR patterns of the obtained lignin and the standard lignin (lignin, alkali: 471003-100G from ALDRICH) are similar. Similarly, it can be seen from the results of FIG. 7 that the XRD and IR patterns of the obtained cellulose and the standard cellulose (Avicel PH-101: 11365 manufactured by Fluka) are similar.
Moreover, from the result of FIG. 8, it can be seen that the obtained cellulose and hemicellulose have greatly different XRD and IR patterns.

From the results of FIG. 6, FIG. 7, and FIG. 8, it was found that by separating lignin, cellulose, and hemicellulose using an ionic liquid ([P _1ME ] [Lys]), the three components can be separated cleanly.

  <3-3. FIG. 9 shows the result of MALDI-QIT-TOF MS measurement of lignin obtained in the lignin / cellulose / hemicellulose separation experiment>.

  From the results of FIG. 9, it can be seen that the molecular weight of the obtained lignin is 21 kilodaltons, and that it is possible to separate the lignin structure with almost no destruction by using the method of the present invention. .

  <3-1. Cedar chip melting experiment> Using hinoki and lawan instead of cedar as biomass, separating lignin from each, and measuring MALDI-QIT-TOF MS of lignin obtained from cedar, hinoki and lawan The results are shown in FIG.

  From the results of FIG. 10, the lignin obtained from cedar and cypress is composed of two polymers of m / z = 196 + 197 × n and m / z = 110 + 197 × n, and the lignin obtained from Lauan is m / z = 196 + 197 × It can be seen that it is composed of n single polymers.

<3-4. Change in solubility due to differences in cations>
For the three ionic liquids with different cations, the above <3-1. Table 5 shows the results of examining the solubility of lignin by the same operation as in the cedar chip dissolution experiment>.
The ionic liquid used is <1-1. It was synthesized by changing the substrate in the same manner as in the chlorination step> and (ion exchange resin method). N-methyl-N- (2-methoxyethyl) piperidinium lysine ([Py _1ME ] [Lys]) was synthesized using N-methyl piperidine as a substrate, and N, N-diethyl-N-methyl-N -(2- _Methoxyethyl ) ammonium lysine ([N _221ME ] [Lys]) was synthesized using diethylmethylamine as a substrate.

As is clear from the results in Table 5, it was found that [P _1ME ] has higher lignin solubility than [Py _1ME ] and [N _221ME ].

<< 4. Recycling ionic liquid >>
<3-1. In the cedar chip dissolution experiment>, ethanol was distilled off from the ionic liquid separated from lignin, and vacuum drying was performed to regenerate the ionic liquid.
This regenerated ionic liquid is again <3-1. When used as a solvent in the cedar chip dissolution experiment>, it was found that lignin was dissolved in the same amount as when it was first used.

Performing this reproduction, <3-1. It can be seen that the amount of lignin dissolved does not change at all even if the operation used as a solvent in the cedar chip dissolution experiment> is repeated 5 times, and the ionic liquid [P _1ME ] [Lys] is reused many times by performing regeneration treatment. Was found to be possible.

If the method of this invention is used, it will become possible to isolate | separate biomass which had not so much utility value, such as a thinning material, a timber processing waste, a house waste material, into a lignin component and a cellulose component until now. In addition, since the ionic liquid, the used solvent, etc. can be recovered and reused with little loss, clean lignin production without waste is possible.
Lignin can be used as a raw material for polymers, pharmaceuticals, and fragrances, and since almost all lignin is removed, undissolved cellulose can be used as pulp.

Claims (11)

(1) The following chemical formula (1)

(In the formula ^(1), R 1, ^{R 3} may be different also identical, represent an alkyl group, an alkenyl group having 2 to 6 carbon atoms having 1 to 6 carbon atoms, ^{R 2} is one or more It may be substituted, and represents a hydrogen atom, an amino group, a hydroxy group, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group, and Y represents CH ₂ , O, S N represents the number of ring members, n = 1, 2 and X represents an anion derived from an amino acid, and the alkyl group, alkenyl group, and alkoxy group are substituted with halogen, amino group, phenyl A lignin-soluble ionic liquid represented by a group, a cycloalkyl group, an alkoxy group or a hydroxy group or a biomass group, and a biomass are mixed at 20 to 80 ° C. to prepare a mixed solution,
(2) The mixed liquid obtained in the step (1) is separated into an ionic liquid phase and a residue,
(3) A method for producing lignin, comprising a step of adding a solvent to the ionic liquid phase obtained in the step (2), precipitating lignin, separating and recovering the lignin. The method for producing lignin according to claim 1, wherein X is an anion derived from an L-amino acid. The method for producing lignin according to claim 1 or 2, wherein X is an anion derived from L-lysine or L-arginine. The R ¹ and R ³ are an alkyl group having 1 to 6 carbon atoms and an alkoxyalkyl group, the R ² is a hydrogen atom, Y is CH ₂ , and n is 1. The manufacturing method of lignin as described in any one of -3. The R ¹ and R ³ are a methyl group and a 2-methoxyethyl group, the R ² is a hydrogen atom, Y is CH ₂ , and n is 1. 5. The manufacturing method of the lignin as described in any one. The method for producing lignin according to any one of claims 1 to 5, wherein in the step (2), the method for separating the residue is filtration or centrifugation. After the step (2) and before the step (3), the ionic liquid is further added to the residue obtained in the step (2), and from the residue obtained in the step (2). The method for producing lignin according to any one of claims 1 to 6, comprising a step of separating the ionic liquid a plurality of times. In the said process (3), the said solvent is water, alcohol, and acetone, The manufacturing method of the lignin as described in any one of Claims 1-7. The method for producing lignin according to claim 8, wherein in the step (3), the alcohol is methanol, ethanol, or propanol. (1) The following chemical formula (1)
(In the formula ^(1), R 1, ^{R 3} may be different also identical, represent an alkyl group, an alkenyl group having 2 to 6 carbon atoms having 1 to 6 carbon atoms, ^{R 2} is one or more It may be substituted, and represents a hydrogen atom, an amino group, a hydroxy group, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group, and Y represents CH ₂ , O, S N represents the number of ring members, n = 1, 2 and X represents an anion derived from an amino acid, and the alkyl group, alkenyl group, and alkoxy group are substituted with halogen, amino group, phenyl A lignin-soluble ionic liquid represented by a group, a cycloalkyl group, an alkoxy group or a hydroxy group or a biomass group, and a biomass are mixed at 20 to 80 ° C. to prepare a mixed solution,
(2) The mixed liquid obtained in the step (1) is separated into an ionic liquid phase and a residue,
(4) The residue obtained in the step (2) is mixed with a basic aqueous solution to prepare a mixed solution,
(5) The mixed liquid obtained in the step (4) is separated into a liquid phase and a residue,
(6) the step (5) Bei El hemicellulose Ru the times Osamusu step from the liquid phase obtained in, hemicellulose manufacturing method. (1) The following chemical formula (1)
(In formula (1), R ¹ , R ³ May be the same or different and each represents an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms; ² May be one or more substituted, and represents a hydrogen atom, an amino group, a hydroxy group, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group, and Y is CH ₂ , O, and S, n corresponds to the number of ring members, n = 1, 2, and X represents an anion derived from an amino acid. The alkyl group, alkenyl group, and alkoxy group may have one or more of halogen, amino group, phenyl group, cycloalkyl group, alkoxy group, and hydroxy group as a substituent. ) Lignin-soluble ionic liquid and biomass expressed at 20 to 80 ° C. to produce a mixed solution,
(2) The mixed liquid obtained in the step (1) is separated into an ionic liquid phase and a residue,
(4) The residue obtained in the step (2) is mixed with a basic aqueous solution to prepare a mixed solution,
(5) The mixed liquid obtained in the step (4) is separated into a liquid phase and a residue,
(6) A method for producing cellulose, comprising a step of recovering cellulose from the residue obtained in the step (5).