JP6319994B2 - Method for producing glucose - Google Patents

Description

  The present invention relates to a method for producing amorphous cellulose from a cellulose-containing raw material.

  In recent years, interest in biomass resources has increased through efforts such as global warming countermeasures and the establishment of a recycling society. Natural cellulose is produced from carbon dioxide and water by photosynthesis of plants, and is an organic resource that exists abundantly on the earth. Therefore, it is expected to be used as a renewable biomass resource. In order to use this natural cellulose as a biomass resource, it is necessary to decompose the cellulose to obtain glucose. However, natural cellulose (type I cellulose) exists in a hard crystalline state and is extremely difficult to be decomposed. Therefore, as described in Patent Document 1, natural cellulose needs to be pretreated by strong acid, high temperature / high pressure, mechanical pulverization, or long-time enzymatic reaction, and a great deal of energy is input. Or need to go through complicated processes.

  Therefore, several methods have been proposed for artificially preparing the crystalline state of natural cellulose into an amorphous state that is easily decomposed. For example, Non-Patent Document 1 describes a method of obtaining amorphous (amorphous) cellulose by pulverizing natural cellulose fibers for a long time with a pulverizer such as a ball mill. Further, Non-Patent Document 2 describes that when a substituent of a cellulose derivative typified by acetate is chemically treated to return to the original hydroxyl group, amorphous cellulose can be obtained in a non-aqueous solvent. .

  On the other hand, Non-Patent Document 3 and Non-Patent Document 4 describe that amorphous cellulose immediately changes to type II crystalline cellulose in air or water containing moisture.

JP-A-10-11001

HERMANS PH, J. Am. Chem. Soc., 1946, VOL.68, P.2547-2552 MANLEY R ST J, JOURNAL OF POLYMER SCIENCE: PART A, 1963, VOL.1, P.1893-1899 WADEHRA I L, JOURNAL OF APPLIED POLYMER SCIENCE, 1965, VOL.9, P.2627-2630 KIMURA M, JOURNAL OF APPLIED POLYMER SCIENCE, 1974, VOL.18, P.3069-3076

  As described in Non-Patent Document 3 and Non-Patent Document 4, amorphous cellulose immediately changes to type II crystalline cellulose in water. Therefore, even if amorphous cellulose is obtained by the method described in Non-Patent Document 1 and Non-Patent Document 2, the amorphous cellulose is hardly decomposed in the treated water when hydrolyzed using an acid or an enzyme II. It changes to the type of crystalline cellulose. Therefore, these amorphous celluloses are unsuitable for the hydrolysis treatment performed in the presence of water and have a problem that they are difficult to be hydrolyzed.

  The present invention has been devised in view of the above-described points, and an object of the present invention is to provide a method for producing amorphous cellulose that can obtain stable amorphous cellulose that is difficult to crystallize in water.

  Another object of the present invention is to provide a new method for preparing a crystalline state of natural cellulose or the like into an amorphous state that is easily decomposed at low energy and low cost.

  Furthermore, another object of the present invention is to provide a method for producing glucose from a cellulose-containing raw material at low energy and low cost.

  In order to solve the above problems, the method for producing amorphous cellulose of the present invention comprises a step of dissolving a crystalline cellulose-containing raw material in a mixed solution composed of amines and an inorganic salt to obtain a cellulose solution, and an alcohol in the cellulose solution. Or the step of regenerating cellulose by adding acetone, wherein the amine is at least one compound selected from the group consisting of ethylenediamine, ammonia and hydrazine, and the inorganic salt is thiocyanate or alkali iodide It is a metal salt.

  A mixed solution consisting of at least one amine compound selected from the group consisting of ethylenediamine, ammonia and hydrazine and an inorganic salt of either a thiocyanate or an alkali metal iodide is under normal temperature and normal pressure conditions. Crystalline cellulose can be dissolved at a high concentration. Therefore, crystalline cellulose that is difficult to dissolve in a normal solvent can be easily made into a solution state. And when solid cellulose is regenerated by adding alcohol or acetone to this cellulose solution, the obtained regenerated cellulose is obtained as amorphous cellulose in an amorphous state. Further, this amorphous cellulose does not change to a crystalline state such as type II cellulose in water or air containing humidity, and stably maintains an amorphous state. Thereby, also in a hydrolysis process, in order to maintain an amorphous state in a process liquid, a hydrolysis reaction is performed efficiently and glucose is obtained in a high ratio. Since these reactions are all performed under normal temperature and normal pressure conditions, they are low energy and low cost.

  In the method for producing amorphous cellulose of the present invention, it is also preferable that the amine is ethylenediamine and the inorganic salt is an alkali metal thiocyanate. As the mixed solution for dissolving the crystalline cellulose, suitable components are selected that are high in safety, low in cost, and easy to handle.

  Furthermore, in the method for producing amorphous cellulose of the present invention, it is also preferable that the ratio of water contained in alcohol or acetone added to the cellulose solution is 5% or less. In regenerating the cellulose in the cellulose solution as amorphous cellulose, a suitable coagulant is selected. The higher the purity of the alcohol or acetone and the smaller the proportion of water contained in these, the more the cellulose is regenerated in the amorphous state.

  Moreover, the manufacturing method of glucose of this invention is obtained by hydrolyzing the amorphous cellulose of this invention with an acid or a cellulase. The amorphous cellulose obtained in the present invention does not change to the crystalline state during the hydrolysis treatment, and maintains an amorphous state. Therefore, the amorphous cellulose can be easily decomposed by acid or cellulase to efficiently produce glucose. it can.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the amorphous cellulose which has the following outstanding effects can be provided.
(1) A stable amorphous cellulose that is difficult to crystallize in water can be obtained from a crystalline cellulose-containing raw material.
(2) All steps up to the preparation of the solvent for dissolving crystalline cellulose (amines / inorganic salt mixed solution), the dissolution of the cellulose-containing raw material, and the regeneration of the amorphous cellulose can be performed under normal temperature and normal pressure conditions. Therefore, amorphous cellulose can be obtained with low energy and low cost.
(3) Since the obtained amorphous cellulose stably maintains an amorphous state, it is easily hydrolyzed. Therefore, glucose can be produced from a crystalline cellulose-containing raw material with low energy and low cost.

It is a flowchart which shows roughly the manufacturing method of the amorphous cellulose which concerns on embodiment of this invention. 2 is a polarizing micrograph showing the state of dissolution of type I crystalline cellulose in an ethylenediamine / sodium thiocyanate mixed solution in Example 1. FIG. In Example 2, (a) X-ray diffraction graph of cellulose regenerated with methanol, (b) X-ray diffraction graph of cellulose regenerated with water. 3 is an X-ray diffraction graph showing a change with time of regenerated cellulose in water in Example 3. FIG. 6 is a CP / MAS solid state NMR chart showing the change with time of regenerated cellulose in water in Example 3. It is an X-ray diffraction graph when the regenerated cellulose obtained from the LiCl / DMAc mixed solution in the comparative example is left in water for 3 days. 6 is an X-ray diffraction graph of regenerated cellulose obtained with 99% ethanol, 95% ethanol and water in Example 5. FIG. 6 is a CP / MAS solid state NMR chart of regenerated cellulose obtained with 99% ethanol, 95% ethanol and water in Example 5. FIG. 6 is an HPLC chart of a water-soluble part of regenerated cellulose in Example 6.

  First, the method for producing amorphous cellulose of the present invention will be described with reference to FIG. The method for producing amorphous cellulose according to the embodiment of the present invention includes a step S0 for preparing an amine / inorganic salt mixed solution, a step S1 for dissolving a cellulose-containing raw material in the mixed solution, and a step for regenerating solid cellulose from the cellulose solution. It is roughly composed of S2.

(Preparation of amine / inorganic salt mixed solution)
First, step S0 for preparing the amine / inorganic salt mixed solution shown in FIG. 1 will be described. In the present invention, the mixed solution composed of amines and inorganic salts is a non-aqueous solution and can be obtained by dissolving inorganic salts in liquid amines. Examples of amines include ethylenediamine, ammonia, and hydrazine, and these may be used in appropriate combination. On the other hand, as the inorganic salt to be dissolved in the above-described amines, thiocyanate or alkali metal iodide salt is preferable, and specifically, although not particularly limited, sodium thiocyanate, potassium thiocyanate, lithium thiocyanate, thiocyanic acid. Ammonium, sodium iodide, potassium iodide, etc. are mentioned. The amount of the inorganic salt to be dissolved in the liquid amine is not particularly limited, but from the viewpoint of increasing the solubility of cellulose as the concentration of the inorganic salt is higher, it is preferably 70% or more of the amount that becomes a saturated solution. It is more preferably 90% or more of the amount to be a solution, and further preferably an amount to be a substantially saturated solution. Ethylenediamine and hydrazine are liquid at room temperature, but ammonia is a gas at room temperature. Therefore, ammonia is cooled to about −80 ° C. below the melting point to form a liquid and dissolved to dissolve the inorganic salt. Is obtained. Once the inorganic salt is dissolved, the ammonia / inorganic salt mixed solution maintains a liquid state even at room temperature and is stable.

  As a mixed solution composed of the above-described amines and inorganic salts, it is highly safe, the mixed solution can be easily prepared under normal temperature and normal pressure conditions, and from the viewpoint of excellent solubility of cellulose, ethylenediamine and A mixed solution comprising an alkali metal thiocyanate is preferred. As an alkali metal thiocyanate, sodium thiocyanate or potassium thiocyanate is preferably used. As an example, 100 g of an ethylenediamine / sodium thiocyanate mixed solution obtained by mixing 45 parts by weight of sodium thiocyanate with 55 parts by weight of ethylenediamine is about 16 g of type I cellulose (DP210, crystallinity 0.78). Can be dissolved.

  As will be described later, in the process of producing the amorphous cellulose of the present invention, it is important to reduce the moisture contained in the mixed solution as much as possible. Therefore, it is preferable that amines and inorganic salts that are raw materials of the mixed solution are those containing as little water as possible, and that the equipment used for the preparation is well dried. Further, the mixed solution obtained by the preparation is preferably sealed so that moisture in the air does not dissolve.

(Dissolution of cellulose-containing raw materials)
Next, step S1 for dissolving the cellulose-containing raw material in the mixed solution will be described. In this step, the cellulose-containing raw material is added to and dissolved in the amine / inorganic salt mixed solution prepared as described above. The kind of cellulose of the crystalline cellulose-containing raw material is not particularly limited, and the mixed solution of the present invention is not only natural cellulose (I-type cellulose) but also regenerated cellulose (II-type or III-type cellulose) obtained by artificial preparation. It also exhibits an excellent dissolving action.

  Furthermore, the cellulose-containing raw material used in the present invention is not particularly limited as long as it contains crystalline cellulose, and may be a biomass resource containing cellulose in addition to those isolated as cellulose. Examples of biomass resources are usually cultivated crops such as rice, wheat, corn, beet and sugarcane, rice straw, rice husk, wheat straw, wheat husk, corn stover, beet pulp, bagasse, wood chips, thinned wood and waste paper Then, what is discarded is listed. When these biomass resources are used as a cellulose-containing raw material, it is preferable that pretreatment such as shredding treatment, hydrothermal treatment, or defibration treatment is performed.

  When cellulose in a cellulose-containing material is dissolved in a mixed solution of amines / inorganic salts, the cellulose-containing material is added to the mixed solution, and then stirred with a stirrer or shaken with a shaker. It is preferable to dissolve while promoting diffusion into the mixed solution. Highly concentrated cellulose solutions exhibit very viscous properties. The time required for dissolution of cellulose varies depending on the concentration of cellulose. For example, when obtaining a cellulose solution of less than 5%, it takes about 4 to 5 hours, and when obtaining a cellulose solution of about 10%, 3 If it is about a day, the cellulose is completely dissolved.

  Unlike the conventional reaction system in which the cellulose is dissolved by heating the solvent, the dissolution of the cellulose-containing raw material in the amine / inorganic salt mixed solution in the present invention is performed at room temperature and normal pressure of 15 to 25 ° C. Made under mild conditions. Therefore, it is possible to obtain a cellulose solution without incurring molecular weight reduction due to unnecessary cleavage or decomposition of the cellulose molecular chain caused by heating, etc., and since neither a heating device nor heat energy is required, low cost and low energy A cellulose solution can be obtained. In the present invention, in order to promote dissolution of cellulose, it is possible to heat or pressurize a mixed solution of amines / inorganic salts as necessary.

  Moreover, in the process of producing the amorphous cellulose of the present invention, it is important to reduce the moisture contained in the cellulose solution as much as possible. Therefore, it is preferable to prepare the cellulose-containing material so that it is thoroughly dried and contains as little water as possible. Moreover, it is preferable to use what was dried well also about the instrument used for melt | dissolution. Furthermore, the obtained cellulose solution is preferably sealed so that moisture in the air does not dissolve.

(Regeneration of cellulose)
Next, step S2 for regenerating solid cellulose from the cellulose solution will be described. Amorphous solid cellulose is regenerated by adding a coagulant to the cellulose solution obtained by dissolving cellulose in a mixed solution of amines / inorganic salts. Examples of the coagulant include ketones such as acetone and methyl ethyl ketone, alcohols such as methanol, ethanol and propanol, and esters such as methyl acetate. Among these, it is particularly preferable to use alcohol such as methanol, ethanol and propanol or acetone as a coagulant from the viewpoint of high safety, low cost and easy handling. The amount of the coagulant added is 3 to 20 parts by weight, preferably 5 to 15 parts by weight of the coagulant per 1 part by weight of the cellulose solution, so that the cellulose in the mixed solution is amorphous. Regenerated as cellulose. Specifically, although not particularly limited, amorphous cellulose is regenerated by pouring a 10-fold amount of a coagulant such as alcohol into the cellulose solution under normal temperature and normal pressure conditions and stirring vigorously.

  The amorphous cellulose obtained in this way is very stable and does not crystallize when left in the air as well as in the air, and can maintain an amorphous state. Therefore, it is efficiently decomposed in the hydrolysis treatment, and a hydrolyzate can be easily obtained.

  Further, as described in the step S0 for preparing the amine / inorganic salt mixed solution and the step S1 for dissolving the cellulose-containing raw material in the mixed solution, the step for producing the amorphous cellulose of the present invention is included in the reaction system. It is important to minimize the amount of moisture that is generated. The reason is that when water is contained in the reaction system, it is regenerated as solid cellulose in a state where crystallization has progressed. For this reason, it is preferable to use a coagulant having a high purity with a low water content. Specifically, the proportion of moisture contained in the coagulant, that is, alcohol or acetone, is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. When water is used as the coagulant, it is regenerated only as completely crystallized type II cellulose.

  The amorphous cellulose of the present invention has a unique property that once it is obtained as amorphous cellulose, it remains amorphous even when immersed in water and is stable against moisture. Conventionally, amorphous cellulose could be obtained by adding a coagulant to a cellulose solution, but the obtained amorphous cellulose is known to rapidly crystallize in air or water to form type II cellulose. It was. The amorphous cellulose obtained in the present invention is stable in water, and therefore maintains an amorphous state that is easily hydrolyzed in water. Therefore, it can be efficiently decomposed in acid hydrolysis treatment such as sulfuric acid or hydrochloric acid or enzyme hydrolysis treatment such as cellulase. Therefore, it is possible to efficiently obtain the target glucose.

  Furthermore, for the used solution after finishing this step S2 and regenerating the amorphous cellulose, the coagulant component such as alcohol or acetone and the amine / inorganic salt mixed solution can be separated by distillation, It can be used. For example, when cellulose is dissolved in a mixed solution of ethylenediamine / sodium thiocyanate and amorphous cellulose is regenerated with methanol, it is separated into amorphous cellulose and filtrate by filtration, and the filtrate is heated to lower the boiling point. Methanol (about 65 ° C.) evaporates first. When the boiling point of the filtrate reaches 105 ° C., when the heating is stopped and the temperature is lowered to room temperature, the residual liquid again exhibits cellulose dissolving power as an ethylenediamine / sodium thiocyanate mixed solution. As described above, the mixed solution and the coagulant used in the present invention can be recycled by a simple operation, have a low environmental load, and are excellent in terms of economy.

  Hereinafter, the present invention will be described in detail with reference to examples.

[Example 1]
1. Dissolution of cellulose in amines / inorganic salt mixed solution According to the formulation shown in Table 1, an inorganic salt was added to the amines and mixed to prepare an amine / inorganic salt mixed solution. About the ammonia / ammonium thiocyanate mixed solution of the mixing | blending C, ammonia gas was once cooled to -80 degreeC, it was set as the liquid, and it obtained by dissolving ammonium thiocyanate with respect to the liquid. Other mixed solutions were obtained by dissolving inorganic salts in amines at room temperature. The inorganic salt is mixed with the amines so as to become a substantially saturated solution under 25 ° C. conditions. Each type I crystalline cellulose (Whatman CC41 microcrystalline cellulose, DP210, crystallinity 0.78) is dissolved in the prepared amines / inorganic salt mixed solutions of Formulations A to F, and the solubility under the condition of 25 ° C. Was measured. The results are shown in Table 1.

  According to the results in Table 1, a mixed liquid composed of an amine such as ethylenediamine, hydrazine or ammonia and an inorganic salt such as a thiocynate or an alkali metal iodide has a high concentration of type I crystalline cellulose at room temperature. It was found that it could be dissolved.

  Next, 100 g of an amine / inorganic salt (ethylenediamine / sodium thiocyanate) mixed solution of Formulation A in Table 1 is placed in a high-density polyethylene bag, and type I crystalline cellulose (Whatman CC41 microcrystalline) 7 g of cellulose, DP210, crystallinity 0.78) was added. After sealing the bag mouth, the solution was stirred by shaking the bag at room temperature to dissolve the cellulose. Immediately after adding the cellulose, 4 hours after the addition, 48 hours after the addition, and 3 days after the addition (complete dissolution), a part of the mixed solution was taken, and dissolution of the cellulose was observed using a polarizing microscope under crossed Nicols. The results are shown in FIG. FIG. 2 is a polarization micrograph taken at each time after the start of dissolution. According to this, after 4 hours from the start of dissolution, the amount of cellulose crystals observed is remarkably reduced, and after 48 hours, almost no solid matter is confirmed, and it is recognized that most of the crystals are dissolved. As a result, in the amine / inorganic salt mixed solution of the present invention, even when a relatively large amount of crystalline cellulose is added so that the cellulose concentration becomes 6.5% by weight, rapid dissolution is performed at room temperature. It was confirmed that it could be completely dissolved in about 2 to 3 days.

[Example 2]
2. Regeneration of solid cellulose from amine / inorganic salt mixed solution (1)
About 1 L of methanol (reagent grade 1, 99.5%) was added to and stirred with 107 g of a cellulose solution obtained by dissolving 7 g of crystalline cellulose in 100 g of an ethylenediamine / sodium thiocyanate mixed solution obtained in the same manner as in Example 1. Then, the dissolved cellulose was coagulated in a gel form. The obtained cellulose gel was washed with a large amount of methanol and vacuum-dried to obtain regenerated cellulose. On the other hand, for comparison, regenerated cellulose was obtained in the same manner as above except that water was used instead of methanol to regenerate solid cellulose. The solid structure of these regenerated celluloses was analyzed by wide angle X-ray diffraction. The results are shown in FIG.

  3A shows an X-ray diffraction graph of cellulose regenerated with methanol, and FIG. 3B shows an X-ray diffraction graph of cellulose regenerated with water. According to this graph, in the cellulose regenerated with water, diffraction peaks derived from the lattice plane of type II cellulose clearly appear at around 12 °, 20 ° and 22 ° (FIG. 3B). It can be seen that it has a mold structure. On the other hand, no diffraction peak was observed in the cellulose regenerated with methanol (FIG. 3A), and it was found that the cellulose was amorphous (amorphous). From this result, when cellulose dissolved in amine / inorganic salt mixed solution is regenerated by coagulation with water, it takes a type II structure, whereas when coagulated with alcohol, it has an amorphous structure. I found out that

[Example 3]
3. Behavior of regenerated cellulose in water The cellulose regenerated with methanol obtained in Example 2 was finely pulverized and then left in water. A part was taken out after 1 day, 1 week, and 3 weeks after being left to dry, and then the solid structure was analyzed by X-ray diffraction and CP / MAS solid state NMR. The result of X-ray diffraction is shown in FIG. 4, and the result of NMR is shown in FIG.

  From the X-ray diffraction graph of FIG. 4, one day after immersion in water, diffraction peaks appear very weakly around 12 °, 20 ° and 22 ° derived from the crystal lattice plane of type II cellulose. The change in the shape of the diffraction peak ceased, and crystallization did not proceed any further after one or three weeks. Further, according to the NMR chart of FIG. 5, a signal shape change is observed at a position corresponding to the C4 resonance signal peculiar to type II cellulose one day after immersion in water, but after three weeks. However, the signal shape did not change any more. From these results, it was found that the amorphous regenerated cellulose obtained by the present invention did not crystallize in water for a long time and maintained amorphous.

[Example 4]
4). Regeneration of solid cellulose from amine / inorganic salt mixed solution (2)
Each regeneration was performed in the same manner as in Example 2 except that ethanol, butanol, 2-propanol, and acetone (all of which use reagent grades) were used instead of methanol used in Example 2, respectively. Cellulose was obtained. Thereafter, as in Example 2 above, the solid structure of each regenerated cellulose obtained was analyzed by X-ray diffraction and CP / MAS solid state NMR, and the behavior of each regenerated cellulose in water was as in Example 3. Examined. As a result, like the cellulose regenerated with methanol in Example 2 and Example 3, each regenerated cellulose obtained in this example has an amorphous structure, does not crystallize in water for a long time, and remains amorphous. I understood it.

[Comparative example]
5. Behavior of Regenerated Cellulose Obtained from LiCl / DMAc Mixed Solution in Water Regenerated cellulose obtained from LiCl / DMAc mixed solution is assumed to be amorphous and amorphous cellulose. Therefore, a test for confirming the stability of amorphous cellulose obtained from this LiCl / DMAc mixed solution in water was performed as follows. In 92 g of dimethylacetamide, 8.0 g of lithium chloride was dissolved with stirring at room temperature to prepare a LiCl / DMAc mixed solution. 7 g of type I crystalline cellulose (Whatman CC41 microcrystalline cellulose, DP210, crystallinity 0.78) was dissolved in 100 g of a LiCl / DMAc mixed solution heated to 80 ° C. About 1 L of room temperature methanol (reagent grade 1, 99.5%) was added to 107 g of this cellulose solution and stirred to coagulate the dissolved cellulose in a gel form. The obtained cellulose gel was washed with a large amount of methanol and vacuum-dried to obtain regenerated cellulose. The regenerated cellulose was pulverized and left in water. The solid structure was analyzed by X-ray diffraction after taking out 3 days after standing and drying. The results are shown in FIG.

  From the X-ray diffraction graph of FIG. 6, a diffraction peak is not observed immediately after regeneration and exists as amorphous cellulose, but after 3 days of immersion in water, 12 ° derived from the crystal lattice plane of type II cellulose, Diffraction peaks appeared at around 20 ° and 22 °, indicating a change to type II cellulose. From these results, it was found that the regenerated cellulose obtained from the LiCl / DMAc mixed solution quickly crystallized in water and changed to type II cellulose.

[Example 5]
6). Effect of Water on Regeneration of Solid Cellulose Similar to Example 2 except that solid cellulose was regenerated using 99 v / v% ethanol and 95 v / v% ethanol, respectively, instead of methanol used in Example 2. Thus, each regenerated cellulose was obtained. In the same manner as in Example 2, the solid structure of each regenerated cellulose obtained was analyzed by X-ray diffraction and CP / MAS solid state NMR. The result of X-ray diffraction is shown in FIG. 7, and the result of NMR is shown in FIG.

  From the X-ray diffraction graph of FIG. 7, in cellulose regenerated with 95% ethanol, diffraction peaks appear weakly around 12 °, 20 ° and 22 ° derived from the crystal lattice plane of type II cellulose, and the amorphous structure It was found to take an intermediate structure of type II structure. Further, according to the NMR chart of FIG. 8, it was found that a signal shape slightly appears at a position corresponding to a C4 resonance signal peculiar to type II cellulose. From these results, it was found that when cellulose is regenerated, the more moisture there is, the more stable solid cellulose that maintains the amorphous structure can be obtained.

[Example 6]
7). Degradability of regenerated cellulose (1)
A test was conducted to compare the degradability of the cellulose regenerated with methanol obtained in Example 2 with natural type I crystalline cellulose. 0.5 g of finely pulverized regenerated cellulose obtained in Example 2 was added to 30 mL of dilute sulfuric acid having a concentration of 70%, followed by hydrolysis at 10 ° C. for 1 hour. After 1 hour, the dilute sulfuric acid solution was filtered to collect the residue, washed and dried, and then its weight was measured to determine the weight of the water-insoluble part. Further, the dilute sulfuric acid solution was neutralized with calcium hydroxide, and the produced calcium sulfate salt was removed by filtration, and then the solvent was removed using an evaporator. The weight of the solid content obtained after removing the solvent was measured and used as the weight of the water-soluble part. Further, a part of the solid content consisting of this water-soluble part was taken and dissolved in water, and the decomposition state of the regenerated cellulose was confirmed by HPLC analysis. On the other hand, as a comparative example, instead of the regenerated cellulose obtained in Example 2, type I crystalline cellulose (Whatman CC41 microcrystalline cellulose, DP210, crystallinity 0.78) was used, and hydrolysis similar to the above was performed. A test was conducted. The results are shown in Table 2. Moreover, the HPLC spectrum chart of a water soluble part is shown in FIG.

  According to Table 2, for the amorphous regenerated cellulose, the total value of the water-soluble part and the water-insoluble part is less than 50%. This is because the cellulose decomposed by sulfuric acid is further decomposed excessively. This is considered to be due to volatilization during the decomposition reaction with sulfuric acid and during the distillation with an evaporator. Therefore, most of the amorphous regenerated cellulose obtained in the present invention is considered to have been hydrolyzed by sulfuric acid. On the other hand, it was shown that 67% of residue of type I natural cellulose remains and is hardly hydrolyzed. Furthermore, according to the HPLC spectrum of the water-soluble part in FIG. 9, it was found that the amorphous regenerated cellulose of the present invention was efficiently decomposed to monosaccharide glucose. Therefore, from these results, it was shown that the amorphous regenerated cellulose obtained according to the present invention has higher degradability and glucose can be obtained more efficiently than type I natural cellulose.

[Example 7]
8). Degradability of regenerated cellulose (2)
0.5 g of finely pulverized regenerated cellulose obtained in Example 2 was added to 30 mL of an acetic acid buffer having a pH of 4.8, and Asp. 300 FPU of niger-derived cellulase was added, and an enzymatic degradation reaction was performed at 50 ° C. for 5 days. After 5 days, the buffer was filtered to collect the residue, washed, dried, and the weight of the enzyme used was subtracted from the weight to obtain the weight of the water-insoluble part. Further, the filtered buffer was diluted to 100 mL, and the glucose concentration contained therein was quantified by HPLC, and converted to the weight of the water-soluble part. On the other hand, as a comparative example, the same enzymatic decomposition test as described above was performed using type I crystalline cellulose (Whatman CC41 microcrystalline cellulose, DP210, crystallinity 0.78). The results are shown in Table 3.

  According to Table 3, also in the enzymatic degradation reaction, it was shown that the amorphous regenerated cellulose obtained according to the present invention was more than twice as degradable as natural type I cellulose.

  The present invention is not limited to the above-described embodiments or examples, and various design changes within the scope not departing from the gist of the invention described in the claims are also included in the technical scope. .

Claims (3)

A step of dissolving a crystalline cellulose-containing raw material in a mixed solution composed of amines and an inorganic salt to obtain a cellulose solution;
Adding cellulose or acetone having a water content of 5% or less to the cellulose solution to regenerate cellulose to obtain amorphous cellulose;
Hydrolyzing the amorphous cellulose with an acid or cellulase,
The amine is at least one compound selected from the group consisting of ethylenediamine, ammonia and hydrazine;
Wherein the inorganic salt is Ri thiocyanate or alkali metal iodide salt der,
The method for producing glucose , wherein the amorphous cellulose maintains an amorphous state even when immersed in water for at least one week . The method for producing glucose according to claim 1, wherein the amine is ethylenediamine, and the inorganic salt is an alkali metal thiocyanate. The method for producing glucose according to claim 1 or 2, wherein a ratio of water contained in alcohol or acetone added to the cellulose solution is 1% or less.