JP2011010654A - Method for saccharification of biomass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing monosaccharides which is suitable for industrial production of monosaccharides from biomass, with a high reaction efficiency and high yield of reaction products.SOLUTION: There is provided the method for producing monosaccharides by carrying out hydrolysis of polysaccharides. In the method, the hydrolysis is carried out in a reaction system containing a heteropolyacid with at least four valences of anionic valency and water, wherein the content of the heteropolyacid is set at least 150 mass% to the amount of the water.

Description

The present invention relates to a biomass saccharification method. More specifically, the present invention relates to a biomass saccharification method suitably used for biomass saccharification performed by an industrial production facility.

As one of methods for producing monosaccharides, a method for producing monosaccharides by saccharifying biomass (lignocellulose) such as wood is known. Saccharification is the hydrolysis of polysaccharides (cellulose, hemicellulose, etc.) present in biomass to monosaccharides of structural units. Monosaccharides obtained by saccharification of biomass are, for example, for producing bioethanol and the like. Used as a fermentation raw material. Lignocellulose is expected as a source of monosaccharides because it does not compete with food applications.
As a technique for saccharifying lignocellulose, there are a chemical method and an enzymatic method, and an acid catalyst is used in the chemical method. Chemical methods can be broadly divided into a concentrated acid method that dissolves and decomposes cellulose at a low temperature using a concentrated acid aqueous solution, and a dilute acid method that decomposes at a high temperature and high pressure using a low concentration acid aqueous solution. A method using sulfuric acid as a catalyst is also known.

As a method for producing monosaccharides by saccharifying biomass, a method of obtaining glucose by hydrolyzing cellulose, which is a kind of biomass, in the presence of silicotungstic acid (see, for example, Non-Patent Document 1), pseudo-melting, etc. A method for hydrolyzing cellulose to obtain glucose using a cluster acid catalyst in a state (for example, see Patent Document 1) is disclosed.

JP 2008-271787 A (page 1-2)

Kenichiro Arai et al., “Journal of Applied Polymer Science” (USA), 1985, Vol. 30, pp. 3051-3057

As described above, methods for producing cellulose by hydrolyzing cellulose using silicotungstic acid or a cluster acid catalyst have been studied. However, these methods have the following problems. That is, in the method of Non-Patent Document 1, cellulose is hydrolyzed using a silicotungstic acid aqueous solution having a concentration of 50% by mass or less (the ratio of the heteropolyacid to water is 100% by mass or less). There is a problem that the reaction time becomes very long due to low efficiency, or high monosaccharide yield cannot be obtained due to excessive decomposition. Further, in the method of Patent Document 1, cellulose is hydrolyzed using Keggin-type phosphotungstic acid (a heteropolyacid whose anion valence is trivalent). However, a solid catalyst is heated and used at room temperature. Therefore, there is a problem that it is difficult to handle in distribution and industrial use, or that an extremely high catalyst concentration is required. Thus, there was room for a device to be a catalyst that can be suitably used for industrial production in which a polysaccharide is hydrolyzed to produce a monosaccharide.

The present invention has been made in view of the above situation, and has an object to provide a method for producing monosaccharides, which has high reaction efficiency and product yield, and is suitable for industrial production of monosaccharides from biomass. And

In the case of producing monosaccharides by saccharifying biomass, the present inventors can carry out saccharification with high efficiency, have a high yield of monosaccharides, and are suitable for monosaccharides suitable for industrial production. Various production methods were examined, and the concentration and type of heteropolyacid used as a catalyst were noted. Therefore, when the ratio of the heteropolyacid to the water present in the reaction system is adjusted to 150% by mass or more, and the heteropolyacid having a valence of anion of 4 or more is used as the heteropolyacid, a polysaccharide is obtained. It has been found that hydrolysis can be performed in a short time with high efficiency. In addition, when a polysaccharide is hydrolyzed using an acid as a catalyst to produce a monosaccharide, the monosaccharide produced by hydrolysis is further excessively decomposed to produce a decomposition product, which reduces the yield of the monosaccharide. Although it is a cause, when such a specific heteropolyacid is adjusted to a specific concentration and used for hydrolysis, the formation of a hyperdegradation product can also be suppressed, and as a result, it is highly efficient from polysaccharides. It was found that monosaccharides can be produced in a yield. Thus, the inventors have conceived that the above problem can be solved by using a specific heteropolyacid at a specific concentration as a catalyst for saccharifying biomass, and the present invention has been achieved.

That is, the present invention is a method for producing a monosaccharide by hydrolyzing a polysaccharide, wherein the production method includes a heteropolyacid having an anion valence of 4 or more and water, and is present in the reaction system. It is a method for producing monosaccharides comprising a step of hydrolysis in a reaction system in which the ratio of the heteropolyacid to water is 150% by mass or more.
The present invention is described in detail below.

The polysaccharide used as a reaction raw material in the present invention is not particularly limited as long as it is derived from biomass and is a saccharide formed by polymerizing monosaccharides. Specifically, it preferably contains cellulose, hemicellulose, and starch, more preferably contains cellulose and hemicellulose, and more preferably contains cellulose. Cellulose has a crystalline region due to strong intramolecular and intermolecular hydrogen bonding, and it is difficult to perform acid hydrolysis compared to other polysaccharides contained in biomass. The method for producing a monosaccharide of the present invention exhibits a particularly remarkable effect when such a hydrolysis-resistant cellulose is used as a reaction raw material. That is, according to the method of the present invention, the strong crystal structure of cellulose can be easily broken down to efficiently decompose monosaccharides as structural units.
As the origin of the polysaccharide, those derived from plants and microorganisms are preferable. Specifically, plant-derived lignocellulose such as corn (shaft, panicle), sugarcane (bagasse), palm (empty fruit bunch, stem, leaf) rice, wheat (rice bran), switchgrass (ear), building waste, and It is preferable to use microorganism-derived cellulose such as algae. Polysaccharides such as cellulose may be used after removing impurities such as lignin and salts and purified, or can be used as they are without purification.

The monosaccharide of the target product in the present invention is not particularly limited as long as it is obtained by hydrolyzing the raw material polysaccharide to the monosaccharide of the structural unit. Specifically, glucose, xylose, mannose, galactose , Arabinose, lyxose, fructose, and the like are preferable, glucose, xylose, mannose, galactose, and arabinose are more preferable, and glucose and xylose are more preferable.

The method for producing monosaccharides of the present invention is a step of hydrolyzing in a reaction system in which the ratio of a heteropolyacid having an anion valence of 4 or more to water present in the reaction system is 150% by mass or more. Is included.
The present inventors have discovered that a heteropolyacid having an valence of an anion of 4 or more hydrolyzes cellulose with a higher reaction efficiency than a trivalent heteropolyacid, and the problems in Patent Document 1 as described above are present. It has been found that the use of a tetravalent or higher valent heteropolyacid can solve the problem. Furthermore, by setting the catalyst concentration (ratio of heteropolyacid to water present in the reaction system) to 150% by mass or more, the hydrolysis reaction can be carried out efficiently and with good yield without causing excessive decomposition. It discovered and it discovered that the subject in the nonpatent literature 1 as mentioned above could be solved.
In the present invention, the amount of water present in the reaction system means the total amount of water added for mixing with the crystallization water coordinated to the heteropolyacid, the water derived from the biomass as the reaction raw material, and the heteropolyacid. means.

In the method for producing monosaccharides of the present invention, the ratio of the heteropolyacid having an anion valence of 4 or more to water present in the reaction system is 150% by mass or more. A reaction system in which a heteropoly acid having a valence of 4 or more is high in concentration by setting the ratio of a heteropoly acid having a valence of 4 or more to 150% by mass or more with respect to water present in the reaction Thus, by hydrolyzing the polysaccharide in such a reaction system, it is possible to shorten the reaction time, increase the reaction rate of the polysaccharide, and perform the hydrolysis efficiently. The ratio of the heteropolyacid having a valence of 4 or more to the water present in the reaction system is preferably 200% by mass or more. More preferably, it is 250 mass% or more. Moreover, it is preferable that it is 400 mass% or less.

In the method for producing monosaccharides of the present invention, the catalyst used for biomass saccharification reaction is a heteropolyacid having an anion valence of 4 or more. When a polysaccharide hydrolysis reaction is performed in a reaction system in which the heteropolyacid is adjusted to a high concentration, the reaction time can be shortened and the reaction rate of the polysaccharide can be increased to achieve a highly efficient reaction.

The heteropolyacid having a valence of 4 or more is not particularly limited as long as the valence of the anion is 4 or more, and the metal atom and the heteroatom element species constituting the isopolyacid skeleton of the heteropolyacid are not limited. However, the metal atom constituting the isopolyacid skeleton preferably includes an element belonging to Groups 4 to 6 of the periodic table. More preferably, it contains at least one element selected from the group consisting of tungsten, molybdenum and vanadium. More preferably, it contains tungsten. Moreover, it is preferable that a hetero atom contains the element which belongs to the 9th group and the 13th-15th group of a periodic table. More preferably, it contains at least one element selected from the group consisting of cobalt, boron, silicon, phosphorus, aluminum and gallium. More preferably, it contains cobalt, boron, silicon, aluminum or gallium.
Specific examples of heteropolyacids having a valence of 4 or more are the Keggin type silicotungstic acid, borotungstic acid, cobalt tungstic acid, aluminotungstic acid, gallium tungstic acid, silicomolybdic acid, boromolybdic acid, cobalt Examples thereof include molybdic acid, silicotanadotungstic acid, borovanadotungstic acid, cobalt vanadotungstic acid, caivanadomolybdic acid, borovanadomolybdic acid, cobalt vanadomolybdic acid, and Dawson type phosphotungstic acid. Among these, tungsten is preferably contained, and specifically, Keggin type silicotungstic acid, borotungstic acid, cobalt tungstic acid, aluminotungstic acid, gallium tungstic acid, caivanadotungstic acid, borovanadotungstic acid Cobalt vanad tungstic acid and Dawson type phosphotungstic acid.
In addition, the catalyst used in the method for producing monosaccharides of the present invention may contain one kind of heteropolyacid having a valence of 4 or more, and may contain 2 or more kinds. Moreover, as long as at least 1 type of the heteropoly acid whose valence of the said anion is 4 or more is included, the other catalyst may be included.

Heteropolyacids having an valence of 4 or more are H ₅ BW ₁₂ O ₄₀ (Keggin-type borotungstic acid), H ₄ SiW ₁₂ O ₄₀ (Keggin-type silicotungstic acid), H ₆ CoW ₁₂ O ₄₀ (Kegin) type cobalt _tungstate), from H _{5 AlW} 12 _{O 40} (Keggin type aluminosilicate tungstic _{acid), H 5 GaW 12 O 40} ( Keggin type gallium tungstic acid) and _{H 6 P 2 W 18 O 62} ( Dawson-type phosphotungstic acid) It is particularly preferred to include at least one heteropolyacid selected from the group consisting of
Including any compound of H ₅ BW ₁₂ O ₄₀ , H ₄ SiW ₁₂ O ₄₀ , H ₆ CoW ₁₂ O ₄₀ , H ₅ AlW ₁₂ O ₄₀ , H ₅ GaW ₁₂ O ₄₀ , and H ₆ P ₂ W ₁₈ O ₆₂ In the reaction system in which the heteropolyacid is adjusted to a high concentration, the hydrolysis of the polysaccharide can be performed to more efficiently carry out the saccharification reaction of the biomass. Among these, H ₅ BW ₁₂ O _40, H ₄ SiW ₁₂ O ₄₀ , H ₅ AlW ₁₂ O ₄₀ , and H ₅ GaW ₁₂ O ₄₀ are most preferable from the viewpoint of high catalyst performance and ease of handling.

As a method for producing a heteropolyacid having a valence of 4 or more, the catalyst preparation solvent, pH, and preparation temperature in the preparation are appropriately set depending on the type of metal atom or heteroatom constituting the isopolyacid skeleton. However, it is preferable to carry out the preparation at 0 to 95 ° C. using an aqueous solvent or an organic solvent containing water whose pH is set between 0.5 and 12.

The hydrolysis step in the method for producing monosaccharides of the present invention is not particularly limited, and the polysaccharide, the heteropolyacid having an anion valence of 4 or more, and water are mixed with an anion with respect to the water present in the reaction system. First, the form of performing the hydrolysis reaction and mixing the polysaccharide with the heteropolyacid having a valence of 4 or more and the heteropolyacid having a valence of 4 or more are first mixed. Thereafter, the hydrolysis is performed by adding water so that the ratio of the heteropolyacid having a valence of 4 or more to the water existing in the reaction system is 150% by mass or more, an anion First, the heteropolyacid having a valence of 4 or more and water are mixed so that the ratio of the heteropolyacid having a valence of anion of 4 or more to the water present in the reaction system is 150% by mass or more. Then add polysaccharides and hydrolyze First, a suspension solution is prepared by mixing polysaccharide and water, and the proportion of the heteropolyacid having an anion valence of 4 or more with respect to the water present in the reaction system in the suspension solution The form etc. which add this heteropolyacid and hydrolyze it so that it may become 150 mass% or more are mentioned.
Moreover, the manufacturing method of the monosaccharide of this invention may include the other process, as long as such a hydrolysis process is included.

As a form of the hydrolysis step, a heteropolyacid having an anion valence of 4 or more and water, and a ratio of the heteropolyacid having an anion valence of 4 or more to water existing in the reaction system is 150. The form which mixes first so that it may become mass% or more, and then adds a polysaccharide and performs a hydrolysis reaction is preferable. Furthermore, the method for producing a monosaccharide of the present invention includes a step of hydrolyzing using an aqueous solution of a heteropolyacid having a valence of 4 or more of anions, wherein the ratio of the heteropolyacid to water is 150% by mass or more. Is more preferable. When the step of hydrolyzing the polysaccharide is in such a form, there is an advantage that the reaction operation is facilitated because the heteropolyacid that is solid at room temperature can usually be handled as a liquid (aqueous solution). Moreover, since the raw material polysaccharide is generally solid, by making the heteropolyacid into an aqueous solution, it can be rapidly mixed with the polysaccharide even at room temperature, and the reaction can proceed. As described above, the use of a heteropolyacid aqueous solution that is liquid at room temperature is one of the preferred embodiments of the present invention. Depending on the type of heteropolyacid, the amount of water molecules that can be coordinated as crystal water varies, so there is more water in the reaction system than can be coordinated as crystal water depending on the type of heteropolyacid. By adjusting so, it can be set as a solution state at 25 degreeC. That is, an aqueous solution of a heteropolyacid having a valence of 4 or more, which is liquid at normal temperature, contains water in an amount exceeding the amount of crystal water of the heteropolyacid.
Furthermore, the aqueous heteropolyacid solution is preferably in a liquid state that can be evaluated as being completely melted at the reaction temperature. In other words, it is preferable that the reaction temperature is not close to or colloidal with the colloid dispersed in the liquid.

The reaction temperature in the hydrolysis step is preferably 20 to 90 ° C. When the reaction temperature is lower than 20 ° C., the reaction rate is extremely reduced, and there is a possibility that a sufficiently high monosaccharide yield cannot be obtained. On the other hand, when the reaction temperature is higher than 90 ° C., the reaction takes a short time, but the occurrence of overdecomposition of monosaccharides obtained by the hydrolysis reaction increases, and the yield of monosaccharides is increased due to the formation of overdecomposition products. May decrease. As hydrolysis reaction temperature in this invention, More preferably, it is 30-80 degreeC, More preferably, it is 40-70 degreeC.

The reaction time in the hydrolysis step is preferably 0.1 to 200 hours. When the reaction time is shorter than 0.1 hour, the hydrolysis reaction cannot be completed and the yield of monosaccharides may be lowered. On the other hand, if the reaction time is longer than 200 hours, the monosaccharide obtained by the hydrolysis reaction will be placed in the reaction system for a long time, so that the monosaccharide may be excessively decomposed, There is a risk that the yield of monosaccharides may be reduced due to the formation of overdegraded products. The hydrolysis reaction time in the present invention is more preferably 0.5 to 100 hours, and particularly preferably 1 to 50 hours.

As the yield of the product produced by the hydrolysis step, the total yield of the monosaccharides produced is preferably 40% or more. When the yield is 40% or more, it can be said that the hydrolysis reaction is sufficiently advanced. More preferably, it is 60% or more, More preferably, it is 80% or more.
The yield of the product produced | generated by a hydrolysis process can be calculated | required by performing a quantitative analysis on the following measurement conditions, for example using a high performance liquid chromatography. In addition, the yield of the monosaccharide in this invention is a carbon reference | standard yield (mol%).
Measurement condition:
Column Shodex KC-811 (manufactured by Showa Denko)
Column temperature 50 ° C
Mobile phase Water mobile phase flow rate 1ml / min
Detector RID

In the hydrolysis step, as described above, when the hydrolysis reaction time is lengthened or the hydrolysis reaction temperature is increased, the produced monosaccharide may be excessively decomposed. If the monosaccharide is excessively decomposed, the yield of the monosaccharide is reduced accordingly. Therefore, in the method for producing the monosaccharide of the present invention, the reaction conditions for hydrolysis are set so that the excessive decomposition does not occur. It is desirable. In the method for producing monosaccharides of the present invention, the amount of the hyperdegradation product produced by the hydrolysis step is preferably 10 mol% or less with respect to the monosaccharides of the product. More preferably, it is 5 mol% or less, More preferably, it is 2 mol% or less. Examples of the compound produced by overdegradation include levulinic acid, formic acid, hydroxymethylfurfural, furfural and the like.
The amount of the excessively decomposed product generated by the hydrolysis step can be determined by quantitative analysis using the same high performance liquid chromatography as described above except that UV (214 nm) is used for the detector.

It is preferable that the quantity of the polysaccharide provided to the said hydrolysis process is 0.1-100 mass% with respect to 100 mass% of heteropoly acids which exist in a reaction system. In the method for producing a monosaccharide according to the present invention, even if the amount of polysaccharide is increased, the monosaccharide can be obtained in a high yield. Therefore, the amount of polysaccharide used is set within such a wide range. be able to. In particular, when the amount of polysaccharide used is large, both the amount and yield of the monosaccharide obtained by hydrolysis can be increased, and the monosaccharide can be produced efficiently. More preferably, it is 0.5-50 mass%, More preferably, it is 1-30 mass%.

The amount of the residue remaining after the hydrolysis step is preferably 60% or less with respect to the raw material polysaccharide. If the amount of residue remaining after the hydrolysis step is 60% or less, it can be said that the hydrolysis reaction has sufficiently proceeded. More preferably, it is 40% or less, More preferably, it is 20% or less.

It is preferable that the manufacturing method of the monosaccharide of this invention performs a hydrolysis process, after performing the process which performs at least 1 process among a mercerization process, a mill grinding process, and an acetone mill grinding process.
A mercerization process is processing a polysaccharide with an alkali. As the alkali, sodium hydroxide, ammonia or the like can be used, and sodium hydroxide is preferably used.
The mill pulverization process is a process of pulverizing polysaccharides with a pulverizer. As the pulverizer, a ball mill, a disk mill, a cutter mill, a hammer mill, a roller mill or the like can be used, and a ball mill or a disk mill is preferably used.
Acetone mill pulverization is to perform the above-mentioned mill pulverization in a state where acetone is added as a solvent to a polysaccharide.
By applying any one of mercerization, mill grinding, and acetone mill grinding to the polysaccharide, the intramolecular and intermolecular structures of the polysaccharide are chemically or physically destroyed. For example, when the polysaccharide has a crystal structure, such as cellulose, the above-described treatment can break the crystal structure and reduce the crystallinity. By destroying the intramolecular and intermolecular structures of the polysaccharide such as the crystal structure, the hydrolysis reaction is performed, whereby the reaction is performed more efficiently. In any case, these processes may be performed once or a plurality of times.

The mercerization process, the mill pulverization process and the acetone mill pulverization process may be used alone or in combination of two or more, but preferably in combination of two or more. By carrying out combining 2 or more types, the intramolecular structure and intermolecular structure of a polysaccharide can be destroyed more fully, and the efficiency of a hydrolysis reaction can be improved more.
When the above treatment is performed in combination of two types, the combination is not particularly limited, but it is preferable to combine the mercerization treatment with either the mill grinding treatment or the acetone mill grinding treatment. In this case, it is more preferable to perform milling or acetone milling after the mercerization. More preferably, an acetone mill pulverization treatment is performed after the mercerization treatment.

It is preferable that the crystallinity of the cellulose after performing the step of performing at least one of the mercerization treatment, the mill pulverization treatment, and the acetone mill pulverization treatment is 60% or less. When cellulose having a crystallinity of 60% or less is subjected to the hydrolysis step, the efficiency of the hydrolysis reaction can be further increased. As a crystallinity degree of the cellulose used for a hydrolysis process, More preferably, it is 50% or less, More preferably, it is 40% or less.

The method for producing monosaccharides of the present invention has the above-described configuration, has high reaction efficiency, and can effectively suppress the excessive decomposition of monosaccharides produced by hydrolysis. Is a production method that can be suitably used for industrial production of monosaccharides from biomass.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

In the following examples and comparative examples, measurements were performed as follows.
(1) Crystallinity of cellulose ¹³ C-NMR measurement of cellulose was performed using a CP-MAS ¹³ C-NMR (Cross-Polarization Magic-Angle-Spinning ¹³ C Nuclear Magnetic Resonance) apparatus. ^{In 13} C-NMR, the C-4 position of a glucose unit in the crystalline region of cellulose (hereinafter referred to as crystal C4) and the C-4 position of the glucose unit in the amorphous region (hereinafter referred to as amorphous C4). And have a different chemical shift. That is, crystal C4 has a chemical shift of 86-92 ppm, whereas amorphous C4 has a chemical shift of 79-86 ppm. From this, the crystallinity degree of the cellulose was calculated | required using the following formula.
(Crystallinity of cellulose (%)) =
(Peak area of peak derived from crystal C4) / {(Peak area of peak derived from crystal C4) + (Peak area of peak derived from amorphous C4)} × 100
(2) Carbon yield (CB)
The carbon yield was calculated by dividing the total amount of carbon of the product (including all saccharides and by-products) generated by the reaction and the carbon residue of the reaction residue by the amount of carbon of the raw polysaccharide used for hydrolysis.
(3) Proton concentration of acid catalyst The proton concentration of the acid catalyst was calculated from the concentration of the acid catalyst and the proton valence. The acid catalyst was calculated assuming that it was totally dissociated.
(4) Quantitative analysis of reaction products Quantitative analysis was performed on glucose, cellobiose and xylose using high performance liquid chromatography.
Measurement condition:
Column Shodex KC-811 (manufactured by Showa Denko)
Column temperature 50 ° C
Mobile phase Water mobile phase flow rate 1ml / min
Detector RID

(Catalyst Preparation Example 1)
Preparation of H ₅ BW ₁₂ O _{40 After} preparing the potassium salt, H ₅ BW ₁₂ O ₄₀ was prepared by cation exchange. That is, 100 g of Na ₂ WO ₄ .2H ₂ O, 150 g of H ₃ BO ₃ and 450 mL of water were added to a beaker, and the mixture was heated in a water bath at about 70 ° C. to evaporate water until the solution reached about 300 mL. The solution was bathed in ice, and the precipitated H ₃ BO ₃ was filtered off. 70 g of H ₃ BO ₃ was added to the filtrate, heated at about 70 ° C. in a water bath, and concentrated until the liquid volume became 150 mL. Further, the solution was bathed again, and the precipitated H ₃ BO ₃ was filtered off. 10 mL of concentrated hydrochloric acid was added to the filtrate, and H ₃ BO ₃ was completely precipitated in an ice bath. Subsequently, 30 mL of an aqueous potassium chloride solution (concentration: 10 g / 30 mL) was added to the filtrate and stirred for 15 minutes, and the produced white solid was separated by filtration. A white solid was dissolved in an aqueous nitric acid solution adjusted to pH 2, and the solution was allowed to stand in a refrigerator for recrystallization. White needle crystals were sucked and dried to obtain K ₅ BW ₁₂ O ₄₀ in a yield of 10-30% (tungsten base yield).
Subsequently, the potassium salt was converted to the acid form by cation exchange. 20.0 g of K ₅ BW ₁₂ O ₄₀ and 70 mL of water were added to a beaker and heated to 45 ° C. to dissolve K ₅ BW ₁₂ O ₄₀ . The solution was placed in a separatory funnel and 100 mL of diethyl ether was added thereto. While stirring the separatory funnel, about 45 mL of concentrated sulfuric acid was added. Then, it came to be divided into three layers, and the lowermost layer was separated and ether was evaporated. 5 mL of water was added to the obtained white solid to dissolve the solid, and then the water was evaporated. Further, 70 mL of water was added to the obtained white solid to dissolve the solid. The same operation was repeated again from the addition of diethyl ether, and finally 16 g of a white solid was obtained (yield 80%). The white solid was H ₅ BW ₁₂ O ₄₀ · 21H ₂ O.

(Catalyst preparation example 2)
Preparation of H ₆ P ₂ W ₁₈ O ₆₂ (Sawami Shikata et al., “Journal of Molecular Catalysis A: Chemical” (Netherlands), 1995, Vol. 100, No. 1-3, pp. 49-59).

(Catalyst Preparation Example 3)
Preparation of H ₆ CoW ₁₂ O ₄₀ First, a potassium salt was prepared and then converted to the acid form. That is, 99 g of Na ₂ WO ₄ .2H ₂ O was first dissolved in 200 ml of pure water, 20 ml of acetic acid was added, and the mixture was heated to about 80 ° C. At the dissolved separately from 12.5g of cobalt acetate ₍₂₎ · 4H 2 O of 63 ml _{H 2} O, the solution was prepared by adding acetic acid 3 drops (about 0.3 g). This was added to the aqueous Na ₂ WO ₄ solution over about 20 hours (using a reflux tower). Furthermore, when 150 ml of warm water (about 50 ° C.) added with 65 g of KCl was added, green microcrystals were formed. After the solution was allowed to stand at room temperature, the crystals were filtered off. The crystals were dissolved in a heated 0.5% acetic acid solution (about 50 ° C.), and the undissolved solid was removed. When the filtrate was left in the refrigerator, green crystals were obtained. Further, when the green crystals were dissolved in 1M HCl, a blue solution was obtained, and the undissolved solid was filtered off. The filtrate was evaporated using a water bath at about 80 ° C. When the blue fibrous crystals started to precipitate, the evaporation was stopped and the solution was bathed in an ice bath. Blue fibrous crystals were obtained with a yield of about 10%. Cation exchange was performed in the same manner as H ₅ BW ₁₂ O ₄₀ . The obtained solid was H ₆ CoW ₁₂ O ₄₀ · 13H ₂ O.

(Catalyst Preparation Example 4)
Preliminary reports of preparation of H ₅ AlW ₁₂ O ₄₀ (IA Weinstock et al., “Journal of the American Chemical Society” (USA), 1999, 121 Volume, No. 19, pp.4608-4617).

(Catalyst Preparation Example 5)
Previous report on preparation of H ₅ GaW ₁₂ O ₄₀ (KM Sundaram et al., “Inorganic Chemistry” (USA), 2006, Vol. 45, No. 3, pp. 958-960).

Example 1
When untreated cellulose is used, 5 g of Keggin silicotungstic acid (H ₄ SiW ₁₂ O ₄₀ · 22H ₂ O, having a tetravalent heteropolyacid anion; manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) containing water of crystallization and 1 ml of water To prepare a heteropolyacid aqueous solution A (concentration of pure heteropolyacid: 73%, water concentration of crystal water and added water: 27%, ratio of heteropolyacid to water: 270%, liquid at room temperature , Proton concentration: 2.7M). To the prepared heteropolyacid aqueous solution, 40 mg of untreated cellulose (manufactured by Sigma-Aldrich; powder, average particle size: 20 microns, crystallinity: 64 ± 4%) was added and stirred at 60 ° C. for 48 A time hydrolysis reaction was performed.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 2)
When cellulose pulverized was used, untreated cellulose was pulverized with a ball mill for 4 days to obtain treated cellulose 1. The crystallinity of the treated cellulose 1 was 36 ± 6%.
A hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 1 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 3)
In the case of using cellulose that has been mercerized after milling, untreated cellulose is milled in the same manner as in Example 2, and further immersed in a 14% aqueous sodium hydroxide solution at room temperature for 24 hours. After performing the chemical treatment, the treated cellulose 2 was obtained through neutralization, washing, and drying steps. The crystallinity of the treated cellulose 2 was 47 ± 10%.
The hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 2 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

Example 4
In the case of using cellulose that has been mercerized and then milled, untreated cellulose is treated in the same manner as in Example 3, except that the order of mercerizing and milling is reversed from Example 3. As a result, treated cellulose 3 was obtained. The crystallinity of the treated cellulose 3 was 28 ± 6%.
A hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 3 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 5)
When cellulose that has been subjected to mercerization and then subjected to acetone mill pulverization is used, untreated cellulose is subjected to mercerization in the same manner as in Example 3, and further pulverized with acetone mill according to a previous report (Japanese Patent Laid-Open No. 07-41502). Treatment was performed to obtain treated cellulose 4. The crystallinity of the treated cellulose 4 was 20 ± 7%.
A hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 4 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 6)
In the case of using mercerized cellulose, untreated cellulose was subjected to mercerization in the same manner as in Example 3 to obtain treated cellulose 5. The crystallinity of the treated cellulose 5 was 63 ± 3%.
The hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 5 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 7)
In the case of using acetone mill pulverized cellulose, untreated cellulose was subjected to acetone mill pulverization in the same manner as in Example 5 to obtain treated cellulose 6.
A hydrolysis reaction was performed in the same manner as in Example 1 except that the treated cellulose 6 was used as the cellulose added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Example 8)
When dry starch (crystallinity: 0%) was used The hydrolysis reaction was performed in the same manner as in Example 1 except that dry starch was used as a sample to be added to the heteropolyacid aqueous solution.
The yield of the obtained product and the amount of residue were as shown in Table 1.

(Comparative Example 1)
In the case of reaction for 48 hours using 13 wt% H ₂ SO ₄ as a catalyst, 40 mg of treated cellulose 3 subjected to milling treatment after mercerization treatment was added to 13 wt% H ₂ SO ₄ (proton concentration: 2.7 M). The mixture was mixed with 2 ml and subjected to a hydrolysis reaction at 60 ° C. for 48 hours while stirring.
The yield of the obtained product and the amount of residue were as shown in Table 2.

(Comparative Example 2)
When the reaction was carried out for 96 hours using 13 wt% H ₂ SO ₄ as the catalyst, the hydrolysis reaction was carried out in the same manner as in Comparative Example 1 except that the hydrolysis reaction time was 96 hours.
The yield of the obtained product and the amount of residue were as shown in Table 2.

(Comparative Example 3)
When the reaction was performed for 48 hours using 30 wt% H ₂ SO ₄ as the catalyst, the hydrolysis reaction was performed in the same manner as in Comparative Example 1 except that 30 wt% H ₂ SO ₄ (proton concentration: 6.2 M) was used as the catalyst. Went.
The yield of the obtained product and the amount of residue were as shown in Table 2.

Example 9
When H ₅ BW ₁₂ O ₄₀ is used as a catalyst 5 g of borotungstic acid (H ₅ BW ₁₂ O ₄₀ · 21H ₂ O having a pentavalent heteropolyacid anion) containing water of crystallization and 1 ml of water are mixed, An acid aqueous solution B was prepared (concentration of pure heteropolyacid: 74%, water concentration of crystal water and added water: 26%, ratio of heteropolyacid to water: 280%, liquid at room temperature). A hydrolysis reaction was performed in the same manner as in Example 4 except that the prepared heteropolyacid aqueous solution B was used.
The yield of the obtained product and the amount of residue were as shown in Table 3.

(Example 10)
When H ₆ P ₂ W ₁₈ O ₆₂ is used as a catalyst 5 g of Dawson-type phosphotungstic acid (H ₆ P ₂ W ₁₈ O ₆₂ · nH ₂ O, having a hexavalent heteropolyacid anion) containing water of crystallization and 1 ml of water And a heteropolyacid aqueous solution C was prepared. A hydrolysis reaction was performed in the same manner as in Example 4 except that the prepared heteropolyacid aqueous solution C was used.
The yield of the obtained product and the amount of residue were as shown in Table 3.

(Comparative Example 4)
When using H ₃ PW ₁₂ O ₄₀ as a catalyst 5 g of Keggin type phosphotungstic acid containing water of crystallization (having H ₃ PW ₁₂ O ₄₀ · 22H ₂ O, trivalent heteropolyacid anion; manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) And 1 ml of water were mixed to prepare a heteropolyacid aqueous solution D (concentration of pure heteropolyacid: 73%, water concentration of crystal water and added water: 27%, ratio of heteropolyacid to water: 270% Liquid at room temperature). A hydrolysis reaction was performed in the same manner as in Example 4 except that the prepared heteropolyacid aqueous solution D was used.
The yield of the obtained product and the amount of residue were as shown in Table 3.

(Example 11)
When the reaction was performed at 60 ° C. for 120 hours, the hydrolysis reaction was performed in the same manner as in Example 1 except that the hydrolysis reaction time was 120 hours.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 12)
When the reaction was carried out at 70 ° C. for 48 hours, the hydrolysis reaction was carried out in the same manner as in Example 1 except that the hydrolysis reaction temperature was changed to 70 ° C.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 13)
When the reaction was carried out at 70 ° C. for 120 hours, the hydrolysis reaction was carried out in the same manner as in Example 1 except that the hydrolysis reaction temperature was 70 ° C. and the hydrolysis reaction time was 120 hours.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 14)
When the reaction was carried out at 90 ° C. for 120 hours, the hydrolysis reaction was carried out in the same manner as in Example 1 except that the hydrolysis reaction temperature was 90 ° C. and the hydrolysis reaction time was 120 hours.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 15)
When the reaction was carried out at 100 ° C. for 48 hours, the hydrolysis reaction was carried out in the same manner as in Example 1 except that the hydrolysis reaction temperature was 100 ° C.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 16)
When the reaction was carried out at 100 ° C. for 120 hours, the hydrolysis reaction was carried out in the same manner as in Example 1 except that the hydrolysis reaction temperature was 100 ° C. and the hydrolysis reaction time was 120 hours.
The yield of the obtained glucose and levulinic acid and the amount of the residue were as shown in Table 4.

(Example 17)
When the reaction was carried out at 60 ° C. for 8 hours, the hydrolysis reaction was carried out in the same manner as in Example 9 except that the hydrolysis reaction time was 8 hours.
The yield of the obtained product and the amount of residue were as shown in Table 5.

(Example 18)
When the reaction was carried out at 60 ° C. for 16 hours The hydrolysis reaction was carried out in the same manner as in Example 9 except that the hydrolysis reaction time was 16 hours.
The yield of the obtained product and the amount of residue were as shown in Table 5.

(Example 19)
When the reaction was carried out at 60 ° C. for 24 hours, the hydrolysis reaction was carried out in the same manner as in Example 9 except that the hydrolysis reaction time was 24 hours.
The yield of the obtained product and the amount of residue were as shown in Table 5.

(Example 20)
5 g of cobalt tungstic acid (H ₆ CoW ₁₂ O ₄₀ · 13H ₂ O, having a hexavalent heteropolyacid anion) containing water of crystallization and 1 ml of water were mixed to prepare a heteropolyacid aqueous solution E Concentration: 77%, water concentration of crystal water and added water: 23%, ratio of heteropolyacid to water: 340%, liquid at room temperature). The hydrolysis reaction was carried out in the same manner as in Example 4 except that the prepared heteropolyacid aqueous solution E was used, except that the reaction time was changed to 8 hours. The yield of the obtained product and the amount of residue were as shown in Table 5.

(Comparative Example 5, Examples 21 to 25)
A cellulose hydrolysis reaction was performed using the heteropolyacids shown in Table 6. As the raw material cellulose, cellulose (treated cellulose 3) that was milled and then milled was used. In addition, the heteropolyacid should be prepared so that the heteropolyacid anion concentration is 0.7M (concentration of pure heteropolyacid: 75%, water concentration: 25%, ratio of heteropolyacid to water: 300%, liquid at room temperature). Prepared and used. The reaction was carried out by mixing 2 ml of a 0.7M heteropolyacid aqueous solution and 100 mg of the treated cellulose 3 and stirring and heating at 60 ° C. for 24 hours. The yield of the obtained product and the amount of residue were as shown in Table 6.

(Example 26)
Similar to Example 22 (using H ₅ BW ₁₂ O ₄₀ ), but using a heteropoly acid aqueous solution prepared by adjusting the concentration of H ₅ BW ₁₂ O ₄₀ to 0.6 M (ratio of heteropoly acid to water: 180%) The hydrolysis reaction was performed. The yield of the obtained product and the amount of the residue are as shown in Table 7, and a high yield was obtained.

(Comparative Example 6)
In the same manner as in Example 22, the hydrolysis reaction was performed using a heteropolyacid aqueous solution prepared by adjusting the concentration of H ₅ BW ₁₂ O ₄₀ to 0.4 M (ratio of heteropolyacid to water: 100%). The yield of the obtained product and the amount of residue were as shown in Table 7, and the yield was low.

(Examples 27 and 28)
As in Example 22, except that the amount of cellulose used in the reaction was changed to 200 mg or 500 mg as shown in Table 8, the hydrolysis reaction was performed. The yield of the obtained product and the amount of residue were as shown in Table 8.

These results are shown in Tables 1 to 8 below.
Abbreviations in Tables 1 to 5 are as follows.
Cello: Cellobiose Glu: Glucose Xyl: Xylose Total: Cellobiose, glucose, xylose CB: Carbon yield [H ⁺ ]: Acid proton concentration LA: Levulinic acid The abbreviations in Tables 6 to 8 are as follows: .
Cello: Cellobiose Glu: Glucose Total: Cellobiose, glucose total CB: Carbon yield

From the results in Table 1, the yield of hydrolyzed product is higher when hydrolyzed with silicotungstic acid as a catalyst using pretreated cellulose than untreated cellulose. all right. Furthermore, when a hydrolysis reaction is carried out by changing the cellulose pretreatment method, it is best to carry out an acetone mill pulverization treatment after a mercerization treatment as a pretreatment before carrying out the hydrolysis step. Was found (Examples 1 to 7).
Moreover, when dry starch was used as a reaction raw material, even if a hydrolysis reaction was carried out in the same manner as in Example 1, it was possible to convert almost all the contained polysaccharides into monosaccharides (Example 8).
From the results shown in Table 2, when hydrolytic reaction was performed using sulfuric acid having various concentrations (Comparative Examples 1 to 3), silicotungstic acid was used as a catalyst even if the hydrolysis reaction was performed for a long time. However, it was found that the hydrolysis product was obtained in a higher yield.
From the results of Tables 3, 5 and 6, among the heteropolyacids, when the hydrolysis reaction was carried out using a high-concentration aqueous solution using a heteropolyacid having an valence of 4 or more as a catalyst, hydrolysis was performed. It was found that the product was obtained in high yield (Examples 4, 9, 10, 20, 21-25 and Comparative Examples 4, 5). For example, even with the same phosphotungstic acid, the yield of the hydrolysis product is higher in Example 10 in which the valence of the anion is 6 than in Comparative Example 4 in which the valence of the anion is trivalent. It is significantly higher, showing a markedly superior effect in the present invention. In addition, among the heteropolyacids, it was confirmed that the hydrolyzed product was obtained in a much higher yield when silicotungstic acid was used than when phosphotungstic acid was used, and the difference was remarkable. (Examples 4 and 10).
From the results of Table 4 and Table 5, when the hydrolysis reaction temperature is increased, levulinic acid, which is a hyperdegradation product, is produced (Examples 11, 11 to 16), and when the hydrolysis reaction time is increased, the hydrolysis product is produced. (Example 9, 17-19) was confirmed to increase.
From the result of Table 7, by making the ratio of the heteropolyacid with respect to water of a heteropolyacid aqueous solution 150 mass% or more, compared with the case where it is less than 150 mass%, a hydrolysis product is obtained in a very high yield. It was confirmed that it can be obtained.
From the results of Table 8, it was found that according to the method of the present invention, the hydrolysis product can be obtained in a high yield even if the amount of cellulose to be subjected to the hydrolysis reaction is increased.
In the above-mentioned examples, examples in which cellulose is hydrolyzed using some heteropolyacids having an anion valence of 4 or more are shown. If it is an acid, it can be said that the present invention can be applied in various forms disclosed in the present specification by the same mechanism, and can exhibit advantageous effects.

Claims (4)

A method for producing monosaccharides by hydrolyzing polysaccharides,
The production method includes a heteropolyacid having a valence of an anion of 4 or more and water, and the ratio of the heteropolyacid to water present in the reaction system is 150% by mass or more. The manufacturing method of the monosaccharide characterized by including the process of hydrolyzing. The said manufacturing method includes the process of hydrolyzing using the aqueous solution of the heteropoly acid whose valence of an anion is 4 or more whose ratio of the heteropoly acid with respect to water is 150 mass% or more. The manufacturing method of the monosaccharide of description. The said manufacturing method performs a hydrolysis process after performing the process which performs at least 1 process among a mercerization process, a mill pulverization process, and an acetone mill pulverization process, It is characterized by the above-mentioned. A method for producing monosaccharides. Heteropolyacids having a valence of 4 or more are H ₅ BW ₁₂ O ₄₀ , H ₄ SiW ₁₂ O ₄₀ , H ₆ CoW ₁₂ O ₄₀ , H ₅ AlW ₁₂ O ₄₀ , H ₅ GaW ₁₂ O ₄₀ and H _The method for producing a monosaccharide according to claim 1, comprising at least one heteropolyacid selected from the group consisting of ₆ P ₂ W ₁₈ O ₆₂ .