JP2012144441A - Ionic liquid, purification method of the ionic liquid, and treatment method of cellulose-based biomass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ionic liquid with which problems of corrosion of an apparatus and of environmental load are scarcely produced, and in which cellulose-based biomass can be dissolved with a high concentration, the purification method of the ionic liquid, and the treatment method of the cellulose-based biomass using the ionic liquid.SOLUTION: The ionic liquid is composed of a compound represented by general formula ZA(Zmeans a cation, and Ameans an anion), Zhas a quaternary ammonium skeleton with an alkoxyalkyl group or a nitrogen-containing hetero five-membered ring skeleton with an alkoxyalkyl group, and Ahas an amino group. Since the cellulose-based biomass is dissolved with a high concentration when the ionic liquid is used, the ionic liquid is suitable for production of ethanol or the like.

Description

  The present invention relates to an ionic liquid, a method for purifying the ionic liquid, and a method for treating cellulosic biomass using the ionic liquid.

In recent years, the use of biomass, which is renewable energy, has attracted attention from the viewpoint of environmental protection, and in particular, the development of a method for producing ethanol from cellulosic biomass has been promoted. Ethanol is produced by saccharifying cellulosic biomass to produce monosaccharides such as glucose and xylose, and allowing a fermentation enzyme to act on these monosaccharides. In order to obtain monosaccharides from cellulosic biomass in a high yield, it is important to change the cellulosic biomass to a state that facilitates saccharification by pretreatment (such as dissolution of cellulose) during saccharification treatment.
Recently, a technique using an ionic liquid has been proposed as a solvent for easily dissolving cellulose (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

Patent Document 1 describes a technique for regenerating cellulose by dissolving cellulose with an imidazolium-based ionic liquid and mixing the cellulose-containing ionic liquid with water. Further, water, alcohol, and ketone are used as poor solvents for precipitating dissolved cellulose, and a die (die) is used to separate the precipitated cellulose and ionic liquid. In Patent Document 2, cellulose is dissolved using an ionic liquid composed of a quaternary ammonium cation having an alkoxyalkyl group and a halide, a carboxylic acid having 1 to 3 carbon atoms, a perchloric acid or a pseudohalide anion. ing. In Patent Document 3, cellulose is dissolved using an ionic liquid composed of a quaternary ammonium cation having an alkoxyalkyl group and a phosphate anion ((CH ₃ O) (R) PO ₂ ⁻ ).

JP 2005-506401 A WO2007 / 049485 WO2008 / 133269

  The imidazolium-based ionic liquid used in Patent Document 1 generally has a high viscosity, takes time for contact with the object to be processed and subsequent penetration into the object to be processed, and dissolves cellulose in a sufficient concentration. Is difficult. In Patent Documents 2 and 3, it is difficult to sufficiently increase the solubility of cellulose. Furthermore, halogen-containing ionic liquids have problems such as device corrosion and environmental load. Further, no satisfactory method is disclosed for the purification method of the ionic liquid itself.

  An object of the present invention is to provide an ionic liquid capable of dissolving a cellulosic biomass at a high concentration, a method for purifying the ionic liquid, a method for treating the cellulosic biomass, and a cellulose using the ionic liquid, with less problems of device corrosion and environmental load It is in providing the processing method of biomass.

  The present inventors diligently studied to solve the above-mentioned problems, and focused attention on enzyme proteins that exert a catalytic function on cellulose. In order for an enzyme such as cellulase to hydrolyze cellulose, the cellulose and a specific site of the enzyme protein must first come into contact. Therefore, it was expected that the solubility of cellulose would be increased if an ionic liquid having the same partial structure as the functional group such as amino group and carboxyl group of cellulase protein. The present invention has been completed based on such findings.

The ionic liquid of the present invention is an ionic liquid composed of a compound represented by the general formula Z ⁺ A ⁻ (Z ⁺ means a cation and A ⁻ means an anion), and the Z ⁺ is an alkoxyalkyl group. has a nitrogen-containing heterocyclic five-membered ring skeleton having a quaternary ammonium skeleton or an alkoxyalkyl group having the a ^- is characterized by having an amino group.
As the nitrogen-containing hetero five-membered ring skeleton, an imidazolium skeleton is particularly preferable.
According to the present invention, the compound constituting the ionic liquid is composed of a cation having a predetermined quaternary ammonium skeleton or a predetermined nitrogen-containing hetero five-membered ring skeleton and an anion having an amino group. Can be dissolved at a high concentration. Moreover, this compound does not contain a halogen, and there are few problems of corrosion of the apparatus and environmental load.

In the present invention, the A ^- preferably has a skeleton having a skeleton having an amino group and a carboxyl group or an amino group and a sulfonyl group.
When A ⁻ has not only an amino group but also a carboxyl group or a sulfonyl group, cellulosic biomass can be dissolved at a higher concentration.

The ionic liquid purification method of the present invention is characterized in that the ionic liquid is purified using a mixed solvent of an aprotic polar solvent and a protic polar solvent.
According to this invention, since the ionic liquid is purified using a mixed solvent of an aprotic polar solvent and a protic polar solvent, an ionic liquid having a very high purity can be obtained.
As such an aprotic polar solvent, acetonitrile is preferable, and as the protic polar solvent, methanol is preferable.

  The cellulosic biomass processing method of the present invention is a cellulosic biomass processing method using any of the ionic liquids described above, wherein the cellulosic biomass is dissolved and further mixed with a poor solvent to precipitate the biomass. A dissolution precipitation step, an ionic liquid recovery step of recovering the ionic liquid from the mixed solution of the ionic liquid and the poor solvent, and a saccharification treatment step of saccharifying the precipitated biomass precipitated in the dissolution precipitation step. And

According to this invention, the dissolution and precipitation step is performed as a pretreatment of the saccharification treatment step for saccharifying cellulosic biomass, and the ionic liquid used in the dissolution and precipitation step is recovered and reused. The precipitated biomass obtained by the dissolution and precipitation process has a crystal state that is different from that of the cellulose-based biomass before the process, and is a raw material that is easily saccharified in the saccharification process.
The ionic liquid recovery step is a step of recovering the ionic liquid from the mixed solution of the ionic liquid and the poor solvent used in the dissolution precipitation step. Since the recovered ionic liquid is reused in the dissolution and precipitation step, it can be processed with a small amount of resources, and is excellent in terms of environment and economy.

In this invention, when dissolving the said cellulose biomass, it is preferable to add a cosolvent with an ionic liquid.
According to this invention, since the co-solvent with an ionic liquid is added when the said cellulose biomass is melt | dissolved, it becomes easy to control the viscosity of a cellulose biomass solution. As such a co-solvent, a compound having a lone electron pair is particularly preferable. Examples thereof include dimethyl sulfoxide and 1,3-dimethyl-2-imidazolidinone.

The flowchart which shows the pre-processing method of the biomass concerning one Embodiment of this invention. ¹ H-NMR spectrum of the ionic liquid ([N _221ME ] [Ala]) in Example 1. ¹³ C-NMR spectrum of the ionic liquid ([N _221ME ] [Ala]) in Example 1. FIG. The figure which shows the XRD measurement result of the process cellulose in Example 1, and an unprocessed cellulose. The figure which shows the XRD measurement result of the process cellulose in Example 12, and an unprocessed cellulose. In Example 15, the figure which shows the time-dependent change of the decomposition rate of an ionic liquid ([ _N221ME ] [Ala]) processing cellulose.

Hereinafter, an embodiment of the present invention will be described.
[Ionic liquid]
The ionic liquid of the present invention comprises a compound represented by the general formula Z ⁺ A ⁻ (where Z ⁺ means a cation and A ⁻ means an anion), and the Z ⁺ is a quaternary ammonium having an alkoxyalkyl group. It has a nitrogen-containing heterocyclic five-membered ring skeleton having a skeleton or an alkoxyalkyl group, wherein a ^- has an amino group.
Thus, the ionic liquid of this invention which consists of a compound whose cation part and anion part are a predetermined combination can melt | dissolve cellulosic biomass in high concentration.

  As the quaternary ammonium skeleton having an alkoxyalkyl group, those represented by the following structural formula are suitable.

In the above structural formula, R ¹ to R ⁴ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkoxyalkyl group having 1 to 6 carbon atoms. However, at least one of R ¹ to R ⁴ is an alkoxyalkyl group.

Further, the quaternary ammonium skeleton having the above-described structure is not limited to the quaternary ammonium skeleton having the following cyclic structure.

In the above structural formula, R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxyl group having 1 to 6 carbon atoms. R ³ to R ⁷ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. . However, the above structural formula includes at least one alkoxyalkyl group.

Examples of the nitrogen-containing hetero five-membered ring skeleton include an imidazolium skeleton, a pyrazolium skeleton, an oxazolium skeleton, a 1,2,3-triazolium skeleton, a 1,2,4-triazolium skeleton, a thiazolium skeleton, and a pyrrolidinium skeleton.
As such a nitrogen-containing hetero five-membered ring skeleton, specifically, those represented by the following structural formula are preferable.

In each structural formula described above, R ¹ and R ² are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxyl group having 1 to 6 carbon atoms. R ³ to R ⁶ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. . However, each structural formula described above includes at least one alkoxyalkyl group.
Among these nitrogen-containing hetero five-membered ring skeletons, an imidazolium skeleton is particularly preferable from the viewpoint of the solubility of cellulosic biomass. Note that the pyrrolidinium skeleton described above is also a quaternary ammonium skeleton.

Examples of such Z ⁺ include N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium ion (hereinafter abbreviated as [N _221ME ]), and 3- (2-methoxy Particularly preferred is ethyl) -1-methylimidazolium ion (hereinafter abbreviated as [MEmim]).

Further, the above A ^- The, from the viewpoint of solubility of the cellulosic biomass, A ^- is preferably has an amino group and a carboxyl group or an amino group and a sulfonyl group. More preferably, A ^- it is desirable to have an amino acid backbone. For example, the following various amino acid anions can be mentioned.

Further, A ⁻ may be an oligopeptide anion in which a plurality of amino acids are peptide-bonded. The three-dimensional structure of the asymmetric center of the amino group in the amino acid does not matter. That is, it may be a racemate that is an R-form, an S-form, or a 1: 1 mixture thereof, or may have any ratio. In addition, regardless of the type of α-amino acid or β-amino acid, an amino group and a carboxyl group or a sulfonic acid group may be present in the same molecule.

Details of the method for producing the above-described ionic liquid of the present invention (compound represented by the general formula Z ⁺ A ⁻ ) will be described in Examples later.
The produced ionic liquid often contains impurities, but the crude ionic liquid can be purified using a mixed solvent of an aprotic polar solvent and a protic polar solvent. Examples of the aprotic polar solvent include acetonitrile, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF) and acetone. Examples of the protic polar solvent include methanol, ethanol and Examples include propanol. As such an aprotic polar solvent, acetonitrile is preferable, and as the protic polar solvent, methanol is preferable. Details of the purification method will be described in the Examples below.

Moreover, when dissolving cellulosic biomass using the ionic liquid of the present invention, it is preferable to add a co-solvent. As the cosolvent, a compound having a lone electron pair is preferable. Examples thereof include dimethyl sulfoxide and 1,3-dimethyl-2-imidazolidinone.
By using such a co-solvent, the viscosity of the cellulosic biomass solution can be controlled, and the stirring power in the cellulosic biomass dissolving step described later can be reduced.

[Production of ethanol from cellulosic biomass]
A method for treating cellulosic biomass (pretreatment) using the above-described ionic liquid of the present invention and further producing ethanol will be described. Basically, the method described in Japanese Patent Application No. 2010-124646 can be applied.
(1. Raw material)
Biomass used as a raw material for ethanol is cellulosic biomass containing hemicellulose and cellulose, specifically, paper resources, woody and herbaceous biomass, and the like. Among these, herbaceous biomass (soft biomass) is preferable. For example, rice, wheat and other strawberries, rice husks, bagasse (sugar cane squeezed), food waste such as okara, energy crops such as weeds and Eliansus Can be illustrated.

(2. Pretreatment process)
In the pretreatment step, the cellulosic biomass is changed to a crystalline state that is easily saccharified in the subsequent saccharification treatment step.
As shown in FIG. 1, the pretreatment process includes a dissolution and precipitation process S1, a first separation process S2, a pulverization process S3, a counter-current contact elution process S4, a second separation process S5, and a distillation process. S6.

(3. Saccharification process)
The precipitated biomass A3 obtained in the second separation step S5 is subjected to enzyme saccharification using an enzyme to convert it into a monosaccharide.
Thereafter, ethanol is produced by fermenting the obtained monosaccharide using a microorganism.

In the embodiment described above, the dissolution and precipitation step is performed as a pretreatment of the saccharification treatment step for saccharifying cellulosic biomass, and the ionic liquid used in the dissolution and precipitation step is recovered and reused. Since the precipitated biomass obtained by the dissolution precipitation process is once dissolved by the above-mentioned predetermined ionic liquid, the crystalline state is changed from that of the cellulose-based biomass before the treatment. Therefore, it is a raw material that is easily saccharified in the saccharification treatment step.
In the ionic liquid recovery step, the ionic liquid is recovered from the mixed solution of the ionic liquid and the poor solvent used in the dissolution and precipitation step. Since the recovered ionic liquid is reused in the dissolution and precipitation step, it can be processed with a small amount of resources, and is excellent in economic efficiency. Moreover, since this ionic liquid does not contain halogen, it is excellent in terms of environment.

EXAMPLES Next, although an Example and a reference example are given and this invention is demonstrated in more detail, this invention is not restrict | limited to the description content of these Examples at all.
In the following examples and comparative examples, the following substances were used.
Cellulose: Commercially available microcrystalline cellulose (Avicel manufactured by Merck)
Ionic liquid: Production method is described in each example and comparative example

The structure of the ionic liquid obtained by the method described later was determined by nuclear magnetic resonance spectrum (measured with JNM-500 manufactured by JEOL Ltd., 500 MHz: ¹ H-NMR, 125 MHz: ¹³ C-NMR). . The measurement was performed using deuterated chloroform (CDCl ₃ ), deuterated methanol (CD ₃ OD), or deuterated water (D ₂ O), and indicated by a δ value (ppm) when tetramethylsilane (TMS) was used as an internal standard. Coupling patterns were abbreviated as singlet (s), doublet (d), triplet (t), quartet (q), multiplet (m), broad (br).

[Example 1]
(Manufacture of ionic liquid)
(1) Synthesis of N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium bromide (hereinafter abbreviated as [N _221ME ] [Br])

N, N-dimethyl-N-methylamine (made by ALDRICH) (7.4 g, 85 mmol) and 2-bromomethyl ether (made by Tokyo Chemical Industry) (11.8 g, 85 mmol) were added to an Ar-substituted 100 mL two-necked eggplant flask. , And stirred at 60 ° C. for 24 hours. After standing to cool, it was washed 5 times with hexane (Kanto Chemical) (20 mL) and dried under reduced pressure at 60 ° C. for 3 hours using a vacuum pump (Hitachi SVR16F), and [N _221ME ] [Br] (15.6 g 69 mmol) with a yield of 81 mol%. The analysis results by NMR are as follows.
¹ H-NMR (500 MHz, D ₂ O, ppm)
d = 1.18 (6H, t, J = 6.8Hz), 2.89 (3H, s), 3.26-3.30 (7H, m), 3.37-3.39 (2H, m), 3.74 (2H, m)
¹³ C-NMR (125 MHz, CD ₃ OD, ppm)
d = 8.34,48.63,58.61,59.27,61.29,66.94

(2) Synthesis of alanine = N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium (hereinafter abbreviated as [N _221ME ] [Ala])

Amberlite IRA400CL (manufactured by Organo Corporation) (50 mL) is packed into a 200 mL column, activated with 1M sodium hydroxide (manufactured by Wako Pure Chemical Industries) aqueous solution (170 mL), washed with deionized water, It was converted to [N _221ME ] [OH] through a solution of [N _221ME ] [Br] (2.26 g, 10 mmol) synthesized in 1) in deionized water (15 ml). A solution of alanine (ALDRICHI) (0.89 g, 10 mmol) in deionized water (60 mL) was prepared in a 200 mL eggplant flask, and [N _221ME ] [OH] was _added dropwise at 0 ° C. to this aqueous solution, and at 19 ° C. for 19 hours. After stirring, the solution was concentrated under reduced pressure, filtered through Celite, and washed with a mixed solution of acetonitrile (manufactured by Wako Pure Chemical Industries): methanol (manufactured by Wako Pure Chemical Industries, Ltd.) (9: 1). The filtrate was freeze-dried with a freeze dryer (freezone 1 (7740020) manufactured by LABCONCO), and then dried at 50 ° C. under reduced pressure for 5 hours using a vacuum pump (SVR16F manufactured by Hitachi), and [N _221ME ] [Ala] (2.24 g 9.6 mmol) was obtained with a yield of 96 mol%. The structure of the produced [N _221ME ] [Ala] was confirmed by NMR. The results are shown in FIGS. Each peak has the following values.
¹ H-NMR (500 MHz, D ₂ O, ppm)
d = 1.09 (3H, d, J = 7.5Hz), 1.17 (6H, t, J = 7.4Hz), 2.93 (2H, brs), 3.18 (1H, q, J = 6.9Hz), 3.25 (6H, s ), 3.27 (4H, q, J = 7.5Hz), 3.37 (2H, t, J = 5.1Hz), 3.72-3.73 (2H, m)
¹³ C-NMR (125 MHz, CD ₃ OD, ppm)
d = 8.28,22.04,53.02,58.52,59.26,61.22,66.94,183.23
Alanine has an asymmetric center. Although the synthesis method of L-form was described, the synthesis method is the same for D-form and racemate.
(3) Purification of [N _221ME ] [Ala] As described above, alanine was allowed to act on [N _221ME ] [OH] to exchange the counter anion with alanine, followed by concentration under reduced pressure, and the precipitate was filtered through Celite. Except for this, [N _221ME ] [Ala] can be obtained by washing the celite layer with a mixed solution of acetonitrile (manufactured by Wako Pure Chemical _Industries ): methanol (manufactured by Wako Pure Chemical _Industries ) (9: 1). At this time, it is important to wash with a mixture of acetonitrile: methanol (9: 1). Ordinary ionic liquids are washed with ether, hexane, or ethyl acetate. However, the purity of [N _221ME ] [Ala] cannot be increased by these non-aqueous organic solvent washings. Therefore, when searching for a mixed solvent for washing, a mixed solvent of acetonitrile and methanol gave a good result. With acetonitrile alone, [N _221ME ] [Ala] is difficult to dissolve, resulting in a decrease in yield. When the methanol ratio is increased, alanine as a counter anion is removed, and when washed with methanol alone, alanine precipitates in the methanol solution. Therefore, when the mixing ratio of acetonitrile and methanol was changed from (10: 0 to 0:10), the optimum mixing ratio of the mixed solvent for washing [N _221ME ] [Ala] was acetonitrile: methanol (9: 1 ) For quaternary ammonium salt ionic liquids with amino acids as counter anions, this mixed solvent gave good results in most cases, but it is necessary to select the optimal ratio of acetonitrile and methanol at the right time depending on the type of counter anion and counter cation. .

(Cellulose dissolution test)
1 g of ionic liquid ([N _221ME ] [Ala]) was placed in a sample tube bottle, a stirrer was placed, and the mixture was stirred at room temperature (25 ° C.) with a high torque low speed stirrer (DC-300RM manufactured by ASONE). When 30 mg (3 mass%) of microcrystalline cellulose (Avicel manufactured by Merck) was added to this liquid and dissolution was confirmed by visual observation, it was insoluble. Therefore, the solution was heated to 60 ° C., dissolution was confirmed, and Avicel was further added until it could not be dissolved (60 mg in total). Next, the temperature was raised to 100 ° C., and Avicel was further added until it was not dissolved (60 mg) (120 mg in total).
Table 1 shows the solubility (mass%) of cellulose at each temperature. The solubility is the number of g of cellulose dissolved in 100 g of ionic liquid expressed in%.

(Structural analysis of regenerated cellulose)
After cooling the cellulose solution obtained above, it was diluted with water to precipitate cellulose. The precipitated cellulose was collected by filtration, washed with water, dried under reduced pressure using a vacuum pump (Hitachi SVR16F), and the change in crystal structure was examined by XRD measurement (Ultima IV, manufactured by Rigaku Corporation).
In FIG. 4, the result of the XRD measurement is compared and shown for the cellulose after the dissolution / precipitation treatment and the untreated cellulose.
The aqueous solution of the ionic liquid was concentrated under reduced pressure with an evaporator, treated with activated carbon as an acetone solution, removed water using a vacuum pump (Hitachi SVR16F), and then used again for cellulose treatment. It was able to be used for dissolving cellulose with good reproducibility 5 times or more.

[Examples 2 to 11]
Various ionic liquids with different anions or cations were produced in the same manner as in Example 1, and the solubility of cellulose at each temperature was measured. The results are shown in Table 1. In addition, the ionic liquid of Example 11 is an imidazolium ion ([MEmim]) whose cation contains an alkoxyalkyl group.

[Example 12]
_Take 1.0 g of ionic liquid ([N _221ME ] [Ala]) and 0.17 g of microcrystalline cellulose (Avicel) in a sample tube bottle, place in an oil bath at 120 ° C., and stir timely while confirming dissolution visually. And dissolved. The cellulose solubility in the ionic liquid was 17% by mass, and it was confirmed that the cellulose was dissolved at a high concentration.
After cooling, water was added and the precipitated cellulose was dried at 105 ° C. Changes in crystal structure of the dried cellulose were examined in the same manner as in Example 1 by XRD measurement (Ultima IV, manufactured by Rigaku Corporation).
FIG. 5 shows a comparison of XRD measurement results for the cellulose after the dissolution / precipitation treatment and the untreated cellulose.

[Example 13]
_Take 1.0 g of ionic liquid ([N _221ME ] [Ala]), 1.0 g of dimethyl sulfoxide (made by ALDRICH) and 0.17 g of microcrystalline cellulose (Avicel) in a sample tube bottle, and place in an oil bath at 110 ° C. Then, the mixture was dissolved with stirring for an hour and a half. The dissolution of cellulose was confirmed visually. The solubility of cellulose in the ionic liquid was 17% by mass. Since dimethyl sulfoxide was added as a co-solvent, the viscosity of the solution could be reduced.

[Example 14]
₁₁₀ g of ionic liquid ([N _221ME ] [Ala]), 1.1 g of 1,3-dimethyl-2-imidazolidinone (manufactured by ALDRICH) and 0.17 g of microcrystalline cellulose (Avicel) are placed in a sample tube. The mixture was placed in an oil bath at 0 ° C. and dissolved while stirring for an hour and a half. The dissolution of cellulose was confirmed visually. The solubility of cellulose in the ionic liquid was 17% by mass. Since 1,3-dimethyl-2-imidazolidinone was added as a cosolvent, the viscosity of the solution could be reduced.

[Example 15]
(Enzymatic saccharification of [N _221ME ] [Ala] _-treated cellulose)
An ionic liquid ([N _221ME ] [Ala]) (5.0 g) and microcrystalline cellulose (Avicel) (0.9 g) were placed in a 50 cc eggplant flask and dissolved at 120 ° C. for 2 hours with stirring. Thereafter, 5 g of water was added and the precipitated cellulose was pulverized and washed with warm water at 90 ° C. The precipitated cellulose after washing was filtered, and a part was used as a sample for enzymatic saccharification.
After dissolution by ionic liquid ([N _221ME ] [Ala]), 348 mg of the re-deposited product was placed in a vial (inner diameter 2.5 cm, height 4.5 cm, made of glass), and further 3330 μL of 50 mM sodium acetate A buffer (pH 5.0) and 3.76 mg / mL Accelerase Duet (manufactured by Genencor) were added and sealed. This vial was floated in a 50 ° C. constant temperature bath NTT-2200 (manufactured by EYELA), and an enzyme reaction was performed. In addition, since the cellulose content contained in a recrystallized substance is 17.24 mass%, the preparation density | concentration as a cellulose is 1.5 mass%.
In order to measure the change over time in the decomposition rate, after each reaction time, the vial was thoroughly stirred to make the solution uniform, and 250 μL was weighed into a 1.5 mL microtube. This was boiled for 30 minutes to stop the enzyme reaction. After centrifugation, the supernatant was appropriately diluted, 50 μL of the solution was added to a 96-well microplate, and 200 μL of an attached reagent of Glucose CII Test Wako (manufactured by Wako) was further added. After standing at room temperature for 30 minutes, absorbance at 505 nm was measured using a microplate reader SUNRISE Rainbow Thermo (manufactured by Wako). In addition, the standard curve was computed from the glucose solution prepared in the range from 0 g / mL to 375 g / mL. The decomposition rate was calculated with the amount of glucose converted from the amount of cellulose contained before the reaction as 100% by mass. The results are shown in FIG.

[Comparative Example 1]
N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium chloride (abbreviated as [N _221ME ] [Cl]) was synthesized as a compound for ionic liquid. Specifically, it is as follows.

N, N-dimethyl-N-methylamine (8.8 g, 100 mmol) and 2-chloroethyl methyl ether (manufactured by Tokyo Kasei) (9.5 g, 100 mmol) were added to an Ar-substituted 100 ml two-necked eggplant flask. After 37 hours, N, N-dimethyl-N-methylamine (4.4 g, 50 mmol) was added, and after 109 hours, N, N-dimethyl-N-methylamine (4.4 g, 50 mmol) was added. In addition, the mixture was stirred at 60 ° C. for a total of 161 hours. After standing to cool, it was washed 5 times with hexane (20 ml), dried under reduced pressure at 60 ° C. for 3 hours using a vacuum pump (Hitachi SVR16F), and [N _221ME ] [Cl] (1.6 g, 8.9 mmol). Was obtained in a yield of 9 mol%. The analysis results by NMR are as follows.
¹ H NMR (500 MHz, D ₂ O, ppm)
d = 1.17 (6H, t, J = 7.5Hz), 2.88 (3H, s), 3.25-3.29 (7H, m), 3.35-3.37 (2H, m), 3.24 (2H, m)
¹³ C NMR (125 MHz, CD ₃ OD, ppm)
d = 8.27,49.17,58.53,59.24,61.21,66.92
For the ionic liquid ([N _221ME ] [Cl]) obtained by the above method, the solubility (mass%) of cellulose at each temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
In the same manner as in Example 1, each ionic liquid composed of N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium bromide ([N _221ME ] [Br]) synthesized in Example 1 was used. The solubility (mass%) of cellulose at temperature was measured. The results are shown in Table 1.

[Comparative Example 3]
N, N-diethyl-N- (2-methoxyethyl) -N-methylammonium propionate (abbreviated as [N _221ME ] [OPr]) was synthesized as an ionic liquid compound. Specifically, it is as follows.

Amberlite IRA400CL (manufactured by Organo Co., Ltd.) (35 mL) is packed in a 100 mL column, activated with 1 M sodium hydroxide (manufactured by Wako Pure Chemical _Industries ) aqueous solution (120 mL), washed with deionized water, and [N _221ME ] [Br] (1.5 g, 6.63 mmol) was converted to [N _221ME ] [OH] through a solution of deionized water (10 mL). Under an air atmosphere, propionic acid (0.639 g, 8.62 mmol) and demineralized water (3 mL) were added to a 100 mL two-necked eggplant flask, and the mixture was stirred at room temperature for 19 hours. After concentration under reduced pressure, the mixture was filtered through Celite and washed with ethyl acetate (5 mL × 5 times) and ether (5 mL × 5 times). It was dried at 60 ° C. under reduced pressure for 3 hours to _obtain [N _221ME ] [OPr] (1.21 g, 5.5 mmol) as a pale yellow solid in a yield of 82 mol%.
For the ionic liquid ([N _221ME ] [[OPr]) obtained by the above method, the solubility (mass%) of cellulose at each temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
As the ionic liquid compound, a compound was synthesized in which the cation portion was (2-methoxyethyl) tributylphosphonium (abbreviated as [P _444ME ]) and the anion portion was alanine. Specifically, it is as follows.

Amberlite IRA400CL (manufactured by Organo Co., Ltd.) (25 mL) is packed in a 100 mL column, activated with 1M sodium hydroxide (manufactured by Wako Pure Chemical _Industries ) aqueous solution (100 mL), washed with deionized water, and [P _444ME ] [Br] (1.02 g, 3.0 mmol) was converted to [ _P444ME ] [OH] through a solution of deionized water (10 mL). In an air atmosphere, alanine (0.347 g, 3.90 mmol) and demineralized water (3 ml) were added to a 100 mL two-necked eggplant flask and stirred at room temperature for 19 hours. After concentration under reduced pressure, celite filtration was performed, and 10 mL of acetonitrile-methanol (9: 1) mixture was added, followed by celite filtration. It was dried at 60 ° C. under reduced pressure for 3 hours to _obtain [P _444ME ] [Ala] (1.996 g, 2.84 mmol) as a pale yellow oil in a yield of 95 mol%.
About [ _P444ME ] [Ala], the solubility (mass%) of cellulose at each temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
As a compound for an ionic liquid, a compound having a cation moiety of N- (2-methoxyethyl) pyridinium) (abbreviated as [P _yME ]) and an anion moiety of alanine was synthesized. Specifically, it is as follows.

Amberlite IRA400CL (manufactured by Organo Corporation) (25 mL) is packed in a 100 mL column, activated with 1M aqueous sodium hydroxide (manufactured by Wako Pure Chemical _Industries ) aqueous solution (100 mL), washed with deionized water, and [P _yME ] [Br444] (0.654 g, 3.0 mmol) was converted to [ _P444ME ] [OH] through a solution of deionized water (10 mL). In an air atmosphere, alanine (0.437 g, 3.90 mmol) and demineralized water (3 ml) were added to a 100 mL two-necked eggplant flask and stirred at room temperature for 19 hours. After concentration under reduced pressure, celite filtration was performed, and 10 mL of acetonitrile-methanol (9: 1) mixed solution was added, followed by celite filtration. The _resultant was dried at 60 ° C. under reduced pressure for 3 hours to _obtain [P _yME ] [Ala] (0.629 g, 2.78 mmol) as a black oil in a yield of 93 mol%.
For [P _yME ] [Ala], the solubility (mass%) of cellulose at each temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

[Evaluation results]
In each of the examples, since an ionic liquid composed of a predetermined cation and a predetermined anion is used, the solubility of cellulose is high. Moreover, it does not contain halogen, and there are few problems of corrosion and environmental load of the device. Therefore, it can be understood that the use of the ionic liquid of the present invention is suitable for pretreatment of cellulosic biomass.
On the other hand, in Comparative Example 1, since the structure of the ionic liquid contains halogen, corrosion of the apparatus and environmental load become problems. Moreover, all of the ionic liquids of Comparative Examples 2 to 5 have low cellulose solubility, and it is difficult to pretreat cellulosic biomass.

  INDUSTRIAL APPLICABILITY The present invention can be used for the production of fuels, chemicals and the like using cellulosic biomass as a raw material.

S1 ... Dissolution Precipitation Step S2 ... First Separation Step S3 ... Grinding Step S4 ... Countercurrent Contact Type Elution Step S5 ... Second Separation Step S6 ... Distillation Step A1 ... Cellulosic Biomass A2 ... Precipitated Biomass A3 ... Precipitated Biomass B1 ... Ionic liquid B2 ... Regenerated ionic liquid C1 ... First poor solvent C2 ... Regenerated poor solvent D1 ... Second poor solvent D2 ... Ionic liquid-containing poor solvent

Claims (8)

An ionic liquid comprising a compound represented by the general formula Z ⁺ A ⁻ (Z ⁺ means a cation and A ⁻ means an anion),
Z ⁺ has a quaternary ammonium skeleton having an alkoxyalkyl group or a nitrogen-containing hetero five-membered ring skeleton having an alkoxyalkyl group,
Wherein A ^- is an ionic liquid characterized by having an amino group. The ionic liquid according to claim 1,
Wherein A ^- ionic liquid characterized by having a backbone with a skeleton having an amino group and a carboxyl group or an amino group and a sulfonyl group. In the ionic liquid according to claim 1 or 2,
An ionic liquid, wherein the nitrogen-containing hetero five-membered ring skeleton is an imidazolium skeleton. A method for purifying an ionic liquid according to any one of claims 1 to 3,
Purifying the ionic liquid using a mixed solvent of an aprotic polar solvent and a protic polar solvent. In the purification method of the ionic liquid according to claim 4,
The method for purifying an ionic liquid, wherein the aprotic polar solvent is acetonitrile and the protic polar solvent is methanol. A cellulosic biomass processing method using the ionic liquid according to any one of claims 1 to 3,
A dissolution precipitation step of dissolving the cellulosic biomass and further mixing a poor solvent to precipitate the biomass;
An ionic liquid recovery step of recovering the ionic liquid from a mixed solution of the ionic liquid and the poor solvent;
And a saccharification treatment step of saccharifying the deposited biomass deposited in the dissolution precipitation step. It is a processing method of the cellulosic biomass according to claim 6,
A method for treating cellulosic biomass, comprising adding a co-solvent with an ionic liquid when dissolving the cellulosic biomass. It is a processing method of the cellulosic biomass according to claim 7,
The method for treating cellulosic biomass, wherein the co-solvent comprises a compound having a lone pair of electrons.