JP2018153140A - Method for producing sugar liquid for furfural production raw material and method for producing furfural - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a sugar solution having a high ratio of C5 components in producing a sugar solution for a raw material for producing furfural from a non-edible biomass resource, and to produce furfural from this sugar solution, a sub-furfural. Provided is a method for controlling the reaction to obtain furfural in high yield. SOLUTION: In a method of producing a sugar solution for a raw material for furfural production by reacting a non-edible biomass resource as a raw material in the presence of a solvent with a catalyst in a reaction vessel, in the reaction solution in the reaction vessel. A method for producing a sugar solution for a raw material for furfural production, in which the concentration of hydroxymethylfurfural (HMF) is controlled to 5% by weight to 2% by weight, preferably 50% by weight to 0.5% by weight. A method in which the catalyst contains one or more organic acids of pKa3-5 such as acetic acid, lactic acid or formic acid. [Effect] By controlling the HMF concentration in the reaction solution in the reaction vessel for producing furfural within a predetermined range, the side reaction of furfural can be suppressed. [Selection diagram] None

Description

  The present invention relates to a method for producing a sugar liquid for furfural production raw material from non-edible biomass resources and a method for producing furfural from the produced sugar liquid for furfural production raw material.

  Furfural that can be obtained from non-edible biomass resources can be used as a raw material for the production of furfuryl alcohol and tetrahydrofuran, and can be converted into plant-derived polymer raw materials such as furan resin and PTMG (polytetramethylene ether glycol), respectively. A compound.

  In order to produce furfural from a non-edible biomass resource, the non-edible biomass resource is reacted in the presence of a catalyst in a solvent to obtain a monosaccharide having 5 carbon atoms (such as xylose) and / or a monosaccharide having 5 carbon atoms. To obtain a sugar solution containing polysaccharides (such as xylooligosaccharides) (hereinafter referred to as “C5 sugars”), and hydrolyze the sugars in the sugar solution as shown in the following formula to obtain xylose. And xylulose produced by isomerization of xylose is dehydrated and converted to furfural. As the reaction solvent, water is usually used.

In the hydrolysis reaction for producing a sugar solution containing C5 saccharides from non-edible biomass resources, in addition to C5 saccharides, polysaccharides having 6 or 6 carbon atoms as constituent components (hereinafter referred to as these) This is referred to as “C6 sugar”.
The content ratio of C5 saccharide / C6 saccharide in the sugar solution obtained by the hydrolysis reaction of the non-edible biomass resource is determined to some extent by the non-edible biomass resource to be used. It is preferable that more C5 saccharides are contained in the liquid.

Further, in the process of producing furfural from C5 saccharide, it is important to suppress the side reaction of furfural for improving the yield of furfural.
In particular, when a high-boiling product is generated by a side reaction of furfural, the generated high-boiling product adheres to the inner wall of the reactor and causes troubles such as equipment blockage. It is desirable to suppress it.

  Patent Document 1 describes a technology for hydrolyzing polysaccharide biomass and subjecting the obtained hydrolyzate to ethanol fermentation, reducing the concentration of fermentation inhibitors in the hydrolyzate subjected to fermentation, fermentation As an inhibitor, furfural, hydroxymethylfurfural (HMF), and the like are disclosed. However, Patent Document 1 does not relate to the production of a sugar liquid for furfural production raw material, and there is no description relating to the production of furfural.

  Patent Document 2 describes a composition component and a ratio in a product produced by hydrolysis as a high yield method for chemical hydrolysis of lignocellulose to a monosaccharide. Contains less than 10% by weight furfural, HMF, or levulinic acid In certain embodiments, the hydrolysis product contains less than 5% by weight furfural, HMF, or levulinic acid. The hydrolyzed product contains less than 2.5% by mass of furfural, HMF, or levulinic acid, but there is no description that the HMF concentration is controlled. It is related to the production of fermentation raw materials such as butanol, and is not related to the production of sugar liquid for furfural production raw materials.

  Patent Document 3 describes a method for producing a sugar liquid from a cellulose-containing biomass raw material, and shows the quantitative results of fermentation inhibitors such as HMF. This Patent Document 3 also describes a sugar liquid that is a fermentation raw material. It relates to the production, not the production of the sugar liquid for furfural production raw material.

JP 2005-270056 A Special table 2012-531892 gazette International Publication 2010/67785 Pamphlet

  In the conventional method, the ratio of the C5 saccharide in the saccharide contained in the sugar solution obtained from the non-edible biomass resource is not sufficient, and the side reaction in the production process of furfural has not been sufficiently suppressed. There was a problem that the yield of furfural was low.

  In addition, conventionally, it is known that HMF becomes a fermentation inhibitor when producing sugar liquid as a fermentation raw material from a biomass raw material, and therefore, the HMF concentration is reduced. It has not been known to affect the C5 saccharide / C6 saccharide content ratio or the side reaction of furfural when producing a sugar solution by hydrolysis.

This invention is made | formed in view of the said subject, Comprising: In producing the sugar liquid for furfural manufacturing raw materials from non-edible biomass resources, the method of manufacturing efficiently the sugar liquid with a high C5 saccharide ratio is provided. For the purpose.
Another object of the present invention is to provide a method for producing furfural in a high yield by suppressing side reactions of furfural when producing furfural using the sugar solution for furfural production raw material.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a reaction solution in a reaction tank for producing a sugar solution for furfural production raw material from non-edible biomass resources, and a reaction for producing furfural from this sugar solution. It has been found that the above problems can be solved by controlling the HMF concentration in the liquid within a predetermined concentration range, and the present invention has been completed.
That is, the gist of the present invention resides in the following [1] to [12].

[1] In a method for producing a sugar solution for furfural production raw material by reacting in a reaction vessel in the presence of a solvent using a non-edible biomass resource as a raw material, A method for producing a sugar solution for furfural production raw material, wherein the concentration of hydroxymethylfurfural is controlled to 5 wt ppm or more and 2 wt% or less.
[2] The method for producing a sugar solution for furfural production material according to [1], wherein the concentration of hydroxymethylfurfural in the reaction solution is controlled to be 150 ppm to 0.5% by weight.
[3] The method for producing a sugar liquid for furfural production raw material according to [1] or [2], wherein the catalyst contains an organic acid having a pKa of 3 or more and 5 or less.
[4] The method for producing a sugar liquid for furfural production raw material according to [3], wherein the organic acid is one or more of acetic acid, lactic acid, and formic acid.
[5] The method for producing a sugar liquid for furfural production raw material according to any one of [1] to [4], wherein the solvent is a mixture of water and an organic solvent.
[6] The method for producing a sugar solution for furfural production raw material according to any one of [1] to [5], wherein the non-edible biomass resource is bagasse.
[7] A method of producing a furfural by using a non-edible biomass resource as a raw material to obtain a sugar solution by reacting in a reaction vessel using a catalyst in the presence of a solvent, and reacting the sugar solution in the reaction vessel The method for producing furfural, wherein the concentration of hydroxymethylfurfural in the reaction solution in the reaction vessel is controlled to 5 wt ppm or more and 1.2 wt% or less.
[8] The method for producing furfural according to [7], wherein the concentration of hydroxymethylfurfural in the reaction solution is controlled to 150 wt ppm or more and 0.5 wt% or less.
[9] The method for producing furfural according to [7] or [8], wherein the catalyst contains an organic acid having a pKa of 3 or more and 5 or less.
[10] The method for producing furfural according to any one of [7] to [9], wherein the organic acid is one or more of acetic acid, lactic acid, and formic acid.
[11] The method for producing furfural according to any one of [7] to [10], wherein the solvent is a mixture of water and an organic solvent.
[12] The method for producing furfural according to any one of [7] to [11], wherein the non-edible biomass resource is bagasse.

According to the method for producing a sugar liquid for furfural production raw material of the present invention, by controlling the HMF concentration of the reaction liquid in the reaction tank for producing the sugar liquid for furfural production raw material from non-edible biomass resources within a predetermined range. , The production efficiency of C5 saccharide can be increased, and a sugar solution having a high proportion of C5 saccharide in the saccharide can be obtained, and furfural can be produced in high yield using this sugar solution.
Moreover, according to the method for producing furfural of the present invention, a sugar liquid is obtained from non-edible biomass resources, and the HMF concentration in the reaction liquid in the reaction tank for producing furfural from this sugar liquid is controlled within a predetermined range. Thus, the furfural can be stably produced in a high yield without suppressing the side reaction of the furfural and causing troubles caused by high boiling substances.

  Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

The method for producing a sugar solution for furfural production raw material according to the present invention is a method for producing a sugar solution for furfural production raw material by reacting in a reaction tank in the presence of a solvent using a non-edible biomass resource as a raw material. In the method, the concentration of hydroxymethylfurfural in the reaction solution in the reaction vessel is controlled to 5 ppm by weight or more and 2% by weight or less.
In the method for producing furfural of the present invention, a non-edible biomass resource is used as a raw material, and a sugar solution is obtained by reacting in a reaction vessel using a catalyst in the presence of a solvent, and the sugar solution is reacted in the reaction vessel. In the method for producing furfural, the concentration of hydroxymethylfurfural in the reaction solution in the reaction vessel is controlled to be 5 ppm by weight or more and 1.2% by weight or less.

  In addition, the method for producing furfural from non-edible biomass resources includes a sugar solution production process for obtaining a sugar solution containing C5 saccharide from non-edible biomass resources, and a furfural for obtaining furfural by dehydration reaction of C5 saccharide in the sugar solution. There is a manufacturing process. In the production of furfural, the sugar liquid production process and the furfural production process may be performed in one reactor, or the sugar liquid production process and the furfural production process may be performed in separate reactors. Preferably, the sugar liquid production process and the furfural production process are performed in separate reactors.

<Non-edible biomass resources>
The non-edible biomass resource used in the present invention is not particularly limited as long as it contains a polysaccharide having a saccharide as a constituent component. Specifically, bagasse, switchgrass, napiergrass, Eliansus, Miscanthus, kenaf, Corn stover, corn cob, beet pulp, palm empty fruit bunch, rice straw, straw, rice bran, tree, wood, vegetable oil residue, sasa, bamboo, pulp, waste paper, food waste, seafood residue, livestock waste, etc. . Also, the molasses remaining after the sugar is recovered from the molasses generated in the sugar production process can be used as a non-edible biomass raw material. Among these, bagasse, corn stover, corn cob, and rice straw are preferable from the viewpoint of raw material availability and cost, bagasse and corn cob are more preferable, and bagasse is particularly preferable. Non-edible biomass resources, unlike edible biomass resources, do not compete with edible uses, and are usually discarded or incinerated, so stable supply and effective use of resources are possible. preferable.

  These non-edible biomass resources can be used as they are, or can be used after pretreatment such as acid treatment or hydrothermal treatment. Moreover, these non-edible biomass resources may be used individually by 1 type, and may be used in combination of 2 or more type. In addition, the non-edible biomass resources may be supplied to the reactor in the form of solids such as pulverized particles or powder, or mixed with a solvent such as water and supplied in a slurry state. I do not care.

  The weight average diameter of the non-edible biomass is preferably 0.5 mm or more, more preferably 1 mm or more, and particularly preferably 2 mm or more as the length of the longest part of the grain from the viewpoints of handleability and reaction efficiency. Moreover, 50 mm or less is preferable, 25 mm or less is more preferable, and 10 mm or less is especially preferable.

The weight average diameter of non-edible biomass can be controlled, for example, by adjusting the pulverization conditions in the non-edible biomass pulverizer. That is, when the processing time in non-edible biomass crushing is long, the weight average diameter of the non-edible biomass is reduced. In addition, if the pressure and shear force applied to the non-edible biomass in the non-edible biomass pulverizer are large, the weight average diameter of the non-edible biomass is reduced.
It is also possible to control the weight average diameter of the non-edible biomass by screening the non-edible biomass and selecting the non-edible biomass to be used. That is, when non-edible biomass having a large weight average diameter is selected by sieving, the weight average diameter of non-edible biomass is increased, and conversely, non-edible biomass having a small weight average diameter is selected by sieving. The weight average diameter becomes smaller.

  In addition, in the method of mixing non-edible biomass and a binder and using this as a molded product (pellet) using an extruder, the weight average diameter of the non-edible biomass is controlled by adjusting the extrusion molding conditions. You can also. That is, when the extrusion diameter and the extrusion length in the extruder are increased, the weight average diameter of the non-edible biomass is increased. Conversely, when the extrusion diameter and the extrusion length are decreased, the weight average diameter of the non-edible biomass is decreased.

  The grinder used for crushing the non-edible biomass is not particularly limited as long as it can make the non-edible biomass to have a smaller weight average diameter. For example, a pulverization process is performed by a shearing action between a stator fixed in a case and a rotating rotor, and an object is inserted between two rotating rolls, and the object is made into small particles by high pressure from the two rolls. There are a high-pressure pulverizing type for pulverizing, a ball mill type in which a metal ball is put in a rotating drum and pulverized by collision or friction with the ball, and various other types.

  In addition, the weight average diameter of non-edible biomass is, for example, as a sieve used, an opening diameter of 10 mm, an opening diameter of 4.76 mm, an opening diameter of 2.0 mm, an opening diameter of 1.0 mm, and an opening diameter of 0.5 mm. , And can be measured by a sieving method using an aperture diameter of 0.42 mm (manufactured by Iida Manufacturing Co., Ltd.).

<C5 sugar>
The C5 saccharide in the sugar solution produced in the present invention is not particularly limited as long as it is derived from non-edible biomass resources and can produce furfural by dehydration reaction.

  Specific examples of the monosaccharide having 5 carbon atoms (pentose) include ribose, lyxose, xylose, arabinose, deoxyribose, xylulose, ribulose and the like. Among these monosaccharides, they are abundant because they are constituents of nature and plants, and xylose and arabinose are preferred, and xylose is more preferred from the viewpoint of availability of raw materials and yield.

  Specific examples of polysaccharides having the above monosaccharides having 5 carbon atoms include disaccharides such as xylobiose and arabinobiose; trisaccharides such as xylotriose and arabinotriose, the above disaccharides and 3 Examples include oligosaccharides such as xylo-oligosaccharides and arabino-oligosaccharides containing saccharides, and polysaccharides such as xylan, araban, and hemicellulose. Among these polysaccharides, xylo-oligosaccharide, xylan, and hemicellulose are preferable from the viewpoint of yield, and xylo-oligosaccharide is particularly preferable. Here, the xylo-oligosaccharide is mainly composed of disaccharides and trisaccharides and further contains 4 to 6 sugars.

In the sugar liquid obtained from non-edible biomass resources, only one kind of these monosaccharides and polysaccharides may be contained, or two or more kinds may be contained.
In the sugar solution, monosaccharides such as glucose and polysaccharides such as glucan having different carbon numbers from C5 saccharides may coexist.

<Production reaction of sugar solution>
The reaction for producing the sugar solution containing the C5 saccharide from the non-edible biomass resource is a reaction for generating a C5 saccharide by hydrolyzing the hemicellulose content in the non-edible biomass resource. This reaction is performed using a reaction solvent and a catalyst from the viewpoint of improving the productivity of C5 saccharide and improving the purity of the obtained C5 saccharide.

  Hereinafter, the production reaction of the sugar solution will be described.

(Non-edible biomass concentration)
In the production reaction of sugar liquid from non-edible biomass resources, the concentration of non-edible biomass contained in the reaction solvent is not particularly limited, but the ratio of non-edible biomass to the solvent is 0.1 to 200% by weight. It is preferably 5 to 40% by weight, more preferably 10 to 30% by weight. If the ratio of non-edible biomass to the solvent is equal to or higher than the above lower limit value, the energy required for solvent separation tends to be low, and further, the capacity of the reaction system can be reduced to reduce the construction cost of the equipment. There is a tendency. When the ratio of non-edible biomass to the solvent is not more than the above upper limit value, side reactions can be suppressed, and the yield of C5 saccharides and further furfural tends to increase, which is preferable.

(catalyst)
The catalyst used in the production reaction of sugar liquid from non-edible biomass resources is not particularly limited as long as it is a catalyst capable of producing C5 saccharides from non-edible biomass, but inorganic such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, etc. Examples thereof include acid catalysts such as acids, carboxylic acids, organic acids such as sulfonic acids, and heteropoly acids. Among these, organic acids are preferable from the viewpoints of stability, corrosivity, waste treatment, and unit price, and carboxylic acids are particularly preferable.

Specific examples of the carboxylic acid include aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, levulinic acid, and lactic acid. Acids; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, aconitic acid, itaconic acid, oxaloacetic acid, fumaric acid, cis-1,2-cyclopentanedicarboxylic acid Acid, trans-1,2-cyclopentanedicarboxylic acid, cis-1,3-cyclopentanedicarboxylic acid, trans-1,3-cyclopentanedicarboxylic acid, cis-1,2-cyclohexanedicarboxylic acid, trans-1,2 -Cyclohexanedicarboxylic acid, cis-1,3-cyclohexanedicarboxylic acid aliphatic dicarboxylic acids such as trans-1,3-cyclohexanedicarboxylic acid, cis-1,4-cyclohexanedicarboxylic acid, trans-1,4-cyclohexanedicarboxylic acid; 1,2,4-cyclohexanetricarboxylic acid, 1,3,4 Aliphatic tricarboxylic acids such as 5-cyclohexanetricarboxylic acid; aromatic carboxylic acids such as benzoic acid and naphthalenecarboxylic acid; phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, hemimellitic acid, melophanoic acid, prenitic acid And aromatic polycarboxylic acids such as pyromellitic acid, benzenepentacarboxylic acid, and mellitic acid; and heterocyclic carboxylic acids such as furancarboxylic acid and furandicarboxylic acid. Moreover, the salt which neutralized at least one part of these acids can also be used.
Among these, formic acid, acetic acid, lactic acid, and levulinic acid, which are acids obtained from non-edible biomass, are preferred, and formic acid, acetic acid, and lactic acid are particularly preferred.

  Particularly from the viewpoint of the yield of C5 saccharide, among the above carboxylic acids, those having an acid dissociation constant pKa of 3 to 5 and particularly 3.0 to 4.6 are preferred. Here, the acid dissociation constant pKa is a value when the dissociation stage is 1. That is, in the case of a carboxylic acid having two or more carboxyl groups, it means the acid dissociation constant pKa when at least one hydrogen ion of two or more carboxyl groups is eliminated. For example, in the case of succinic acid having two carboxyl groups, the pKa is usually 4.19 with a dissociation stage of 1 and 5.48 with a dissociation stage of 2. In this specification, 4.19 with a dissociation stage of 1 is used. It is set as pKa of succinic acid.

  Said carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Specific examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, and the like. Moreover, the salt which neutralized at least one part of these acids can also be used.
Said sulfonic acid may be used individually by 1 type, and may use 2 or more types together.

Specific examples of the heteropolyacid include phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, phosphovanadmolybdic acid, and caivanadomolybdic acid. Moreover, the salt which neutralized at least one part of these acids can also be used.
Said heteropolyacid may be used individually by 1 type, and may use 2 or more types together.

  Moreover, you may use the said carboxylic acid, sulfonic acid, and heteropoly acid, mixing 2 or more types in arbitrary ratios. The catalyst is preferably separated and recycled for use in the process.

  The amount of catalyst used in the sugar liquid production reaction can be appropriately set based on the type of catalyst and reaction conditions, and is not particularly limited, but is preferably 0.01 to 50% by weight with respect to the solution amount. More preferably 0.5 to 30% by weight, particularly preferably 1 to 20% by weight. Here, the “solution” refers to a reaction solution containing a reaction solvent, a non-edible biomass raw material, and a catalyst described later. When the amount of catalyst is not less than the above lower limit, the reaction rate tends to increase and the productivity of C5 saccharide tends to improve. It is preferable that the amount of catalyst is not more than the above upper limit value because side reactions are suppressed and the selectivity of C5 saccharide tends to be improved.

(Reaction solvent)
The reaction solvent used in the reaction for producing the sugar liquid from the non-edible biomass resource is water or a mixed solvent of water and an organic solvent. That is, the reaction can be performed only with water, but the reaction can also be performed by adding an organic solvent. When an organic solvent is used, the reaction can be carried out with a homogeneous mixed solvent, but an organic solvent that is a two-phase system of an aqueous phase and an organic phase can also be used. The amount of the organic solvent to be used is not particularly limited as long as the gist of the present invention is not impaired, but it is preferably 10 to 5000% by weight, particularly preferably 10 to 1000% by weight with respect to water.

  The organic solvent is not particularly limited, and examples thereof include ethers having 4 to 20 carbon atoms such as tetrahydrofuran; alcohols having 3 to 20 carbon atoms such as 1-propanol and 2-propanol; pentane, hexane, C3-C12 saturated aliphatic hydrocarbons such as cyclohexane, heptane, octane, nonane, decane, dodecane, isododecane; toluene, xylene, diethylbenzene, trimethylbenzene, 1,2,3,4-tetrahydronaphthalene (tetralin) Aromatic hydrocarbons such as 1-methylnaphthalene, phenols such as phenol, p-cresol, o-cresol, m-cresol, 3,4-xylenol, 2,5-xylenol, ethylphenol, γ-butyrolactone, Lactones such as γ-valerolactone, polyethylene Glycols such as polyethylene glycol, glycol ethers such as polyethylene glycol dimethyl ether, and others, sulfolane, isosorbide, isosorbide dimethyl ether, propylene carbonate, and the like.

  Among these, it is preferable that it is a nonpolar solvent in which the aqueous solvent used as a homogeneous mixed solvent with water or the above-mentioned acid catalyst is hard to melt | dissolve. Among these, when the reaction is carried out in a two-phase system, toluene, xylene, diethylbenzene, trimethylbenzene, 1, 2, and 2 are used from the viewpoint of the extraction efficiency of furfural in the two-layer separation described later and the reduction of the amount of organic solvent dissolved in water. Hydrocarbon solvents such as 3,4-tetrahydronaphthalene (tetralin), 1-methylnaphthalene, cyclohexane, isododecane, etc. are preferred, especially toluene, xylene, diethylbenzene, trimethylbenzene, 1,2,3,4-tetrahydronaphthalene (tetralin), Aromatic hydrocarbon solvents such as 1-methylnaphthalene are particularly preferred.

  The organic solvent is preferably a single solvent in consideration of recovery and reuse of the solvent, but two or more kinds may be used.

(HMF concentration in the reaction solution)
In the method for producing a sugar solution for furfural production raw material of the present invention, the hydroxymethylfurfural (HMF) concentration in the reaction solution is controlled to 5 ppm by weight or more and 2% by weight or less. When the HMF concentration in the reaction solution is equal to or higher than the above lower limit, the energy required for the furfural production process due to the reduction of the solvent amount or the easy separation of the C6 sugar component and the C5 sugar component in the C5 sugar extraction step. Cost can be reduced. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to. When the HMF concentration in the reaction solution is not more than the above upper limit, not only the by-product solids due to the polymerization of HMF itself can be reduced, but also a decrease in the furfural yield due to the reaction between HMF and furfural can be avoided. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to. The HMF concentration in the reaction solution is preferably 10 ppm to 1.5% by weight, more preferably 100 ppm to 1.0% by weight, and even more preferably 150 ppm to 0.5% by weight. Particularly preferably, the content is 200 ppm to 0.4% by weight.

The HMF concentration in the reaction solution can be controlled by adjusting the reaction conditions (temperature, time, raw material concentration, catalyst concentration, etc.).
That is, when the reaction temperature is high, the amount of HMF produced increases and the HMF concentration increases, whereas when the reaction temperature is low, the amount of HMF produced decreases and the HMF concentration decreases.
Also, if the reaction time is long, the amount of HMF produced increases and the HMF concentration increases, and conversely, if the reaction time is short, the amount of HMF produced decreases and the HMF concentration decreases.
On the other hand, if the raw material concentration is high, the amount of HMF produced increases and the HMF concentration increases, and conversely if low, the amount of HMF produced decreases and the HMF concentration decreases.
Further, when the catalyst concentration is high, the amount of HMF generated increases and the HMF concentration increases, and conversely, when the catalyst concentration is low, the amount of HMF generated decreases and the HMF concentration decreases.
In addition, if the cellulose content in the non-edible biomass raw material is high, the amount of HMF produced increases and the HMF concentration increases, and conversely if it is low, the amount of HMF produced decreases and the HMF concentration decreases.
Also, if the weight average diameter of the non-edible biomass raw material is small, the amount of HMF generated increases and the HMF concentration increases. Conversely, if the weight average diameter of the non-edible biomass raw material is large, the amount of HMF generated decreases and the HMF concentration is Lower.
Therefore, the HMF concentration in the reaction solution can be adjusted by appropriately adjusting these conditions within the range of the above-mentioned preferable raw material concentration, the weight average diameter of the non-edible biomass raw material, the catalyst concentration, and the preferable reaction conditions described later. It can control to said suitable range.

(Glucose concentration in the reaction solution)
In the method for producing a sugar liquid for furfural production raw material of the present invention, the glucose concentration in the reaction liquid is not particularly limited, but is preferably 5 ppm by weight to 10% by weight, more preferably 10 ppm by weight to 5% by weight. More preferably, it is 100 wt ppm or more and 2 wt% or less, and particularly preferably 150 wt ppm or more and 1 wt% or less. If the glucose concentration in the reaction solution is not less than the above lower limit, the energy required for the furfural production process due to the reduction of the solvent amount or the easy separation of the C6 sugar component and the C5 sugar component in the C5 sugar extraction step Cost can be reduced. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to. When the glucose concentration in the reaction solution is not more than the above upper limit value, not only the by-product solids due to the polymerization of glucose itself can be reduced, but also a decrease in the furfural yield due to the reaction between glucose and furfural can be avoided. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to.

The glucose concentration in the reaction solution can be controlled by adjusting the reaction conditions (temperature, time, saccharide concentration, catalyst concentration, etc.).
That is, when the reaction temperature is high, the amount of glucose produced increases and the glucose concentration increases, whereas when the reaction temperature is low, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, if the reaction time is long, the amount of glucose produced increases and the glucose concentration increases. Conversely, if the reaction time is short, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, when the saccharide concentration is high, the amount of glucose produced increases and the glucose concentration increases, whereas when it is low, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, when the catalyst concentration is high, the glucose production amount increases and the glucose concentration becomes high. Conversely, when the catalyst concentration is low, the glucose production amount decreases and the glucose concentration becomes low.
Therefore, the glucose concentration in the reaction solution can be controlled within the above-mentioned preferable range by appropriately adjusting these conditions within the above-mentioned preferable saccharide concentration, catalyst concentration and the following preferable reaction conditions. .

(Lignin concentration in the reaction solution)
In the method for producing a sugar solution for furfural production raw material of the present invention, it is preferable to control the lignin concentration in the reaction solution to 0.1 wt% or more and 15 wt% or less. If the lignin concentration in the reaction solution is equal to or higher than the above lower limit, the energy required for the furfural production process due to the reduction of the solvent amount or the easy separation of the C6 sugar component and the C5 sugar component in the C5 sugar extraction step Cost can be reduced. When the lignin concentration in the reaction solution is not more than the above upper limit, not only the by-product solids due to polymerization of lignin itself can be reduced, but also a decrease in furfural yield due to the reaction between lignin and furfural can be avoided. The lignin concentration in the reaction solution is more preferably 0.5 wt% or more and 10 wt% or less, and further preferably 0.7 wt% or more and 5 wt% or less.

The lignin concentration of the reaction solution can be controlled by adjusting the reaction conditions (temperature, time, raw material concentration, catalyst concentration, etc.).
That is, when the reaction temperature is high, the amount of lignin produced increases and the lignin concentration increases, and conversely, when the reaction temperature is low, the amount of lignin produced decreases and the lignin concentration decreases.
Also, if the reaction time is long, the amount of lignin produced increases and the lignin concentration increases, and conversely, if the reaction time is short, the amount of lignin produced decreases and the lignin concentration decreases.
On the other hand, when the raw material concentration is high, the amount of lignin produced increases and the lignin concentration increases, and conversely when it is low, the amount of lignin produced decreases and the lignin concentration decreases.
On the other hand, when the catalyst concentration is high, the amount of lignin produced increases and the lignin concentration increases, whereas when the catalyst concentration is low, the amount of lignin produced decreases and the lignin concentration decreases.

(Reaction conditions)
Although the reaction temperature of the sugar liquid production reaction is not particularly limited, specifically, it is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 140 ° C. or higher, and 250 ° C. or lower. More preferably, it is 230 degrees C or less, Most preferably, it is 210 degrees C or less. When the reaction temperature is equal to or higher than the above lower limit, the progress of the reaction tends to be accelerated, and the productivity of C5 saccharide production is improved. It is preferable for the reaction temperature to be equal to or lower than the above upper limit value because there is a tendency to suppress the sequential reaction and decomposition of C5 saccharide and improve the yield of C5 saccharide.

  The heating method is not particularly limited, but a method of raising the temperature of the reaction solution with a heat exchanger, a method of heating water or a solvent, a method of directly introducing steam or a pressurized heating solution into the reaction solution, etc. are preferable, and heat energy is efficient. From the standpoint of use, a method of heating using a liquid in a process having a high temperature is particularly preferable.

  The reaction time of the sugar liquid production reaction varies depending on the amount and type of raw materials and catalyst used, and the reaction temperature, but is specifically preferably 0.02 hours or more, more preferably 0.1 hours or more, and particularly preferably 0.8. It is 2 hours or more, preferably 8 hours or less, more preferably 4 hours or less, and particularly preferably 2 hours or less. When the reaction time is not less than the above lower limit, the progress of the reaction is promoted and the yield of C5 saccharide tends to be improved, and when the reaction time is not more than the above upper limit, decomposition of C5 saccharide or sequential reaction It is preferable because it tends to suppress C5 and improve the yield of C5 saccharide.

  The preferable range of the reaction pressure varies depending on the reaction temperature, but is preferably 0.1 to 5.0 MPaG, more preferably 0.5 to 3.0 MPaG, and particularly preferably 1.0 to 2.5 MPaG.

(Reaction format)
The reaction mode of the sugar liquid production reaction is not particularly limited, and may be a batch type, a semi-batch type, a continuous type, or a combination of these. From the viewpoint of improving productivity, semi-batch reaction and continuous reaction are preferable, and from the viewpoint of easy operation, batch reaction is preferable. Moreover, a rotary reactor is preferable from the viewpoint of solid-liquid contact. One reactor may be used, or a plurality of reactors may be combined.

(Solid-liquid separation)
The solid-liquid separation method for separating the reaction residue of non-edible biomass resources from the reaction liquid after the production reaction of the sugar liquid is not particularly limited, but filter press, belt filter, screw press, roll press, conveyor dryer, oliver filter, precoat Filters, disk filters, belt presses, Gina centrifugal separators, rotary pressure dehydrators, multiple disk dehydrators, hollow fiber membrane filtration devices, cross-flow centrifugal filtration dehydrators, etc. can be preferably used. Filter presses, belt filters A roll press is more preferable, and a roll press is particularly preferable. Solid-liquid separation may be performed after the production of the sugar liquid, may be performed after the production of furfural by dehydration reaction, or may be performed during the production of the sugar liquid or furfural.

<Furfural production reaction>
The furfural production reaction carried out in the present invention is a reaction for producing a furfural by dehydrating the C5 saccharide in the sugar solution obtained by the sugar solution production reaction in the presence of a catalyst. This dehydration reaction is preferably performed using a reaction solvent and a catalyst from the viewpoint of improving the productivity of furfural and improving the purity of the obtained furfural.

(C5 sugar concentration in sugar solution)
The concentration of C5 saccharide in the sugar liquid for furfural production raw material manufactured according to the above-described method for producing the sugar liquid for furfural production raw material of the present invention and subjected to a dehydration reaction for production of furfural is not particularly limited. It is preferable that it is 0.1-50 weight% in the ratio of C5 saccharides with respect to the reaction solvent of this, More preferably, it is 1-30 weight%, More preferably, it is 2-10 weight%. When the content of the C5 saccharide in the sugar solution is not less than the above lower limit value, the energy required for separation of furfural and the solvent tends to be low after the dehydration reaction, and the capacity of the reaction system is further reduced. Construction costs tend to be reduced. When the C5 saccharide concentration is not more than the above upper limit, side reactions can be suppressed, and the yield of furfural tends to increase, which is preferable.

(catalyst)
The catalyst used in the furfural production reaction of the present invention is not particularly limited as long as it is an acid catalyst capable of producing furfural from C5 saccharides, and is the same as the catalyst used in the above-mentioned sugar liquid production reaction from non-edible biomass resources. The preferred catalyst is the same as in the above-mentioned reaction for producing a sugar solution from non-edible biomass resources.

  The amount of catalyst used in the furfural production reaction can be appropriately set based on the type of catalyst and reaction conditions, and is not particularly limited, but is preferably 0.01 to 50% by weight with respect to the solution amount. More preferably, it is 0.05-30 weight%, Most preferably, it is 0.1-10 weight%. Here, the “solution” refers to a reaction solution containing a reaction solvent, a C5 saccharide, and a catalyst described later. When the amount of catalyst is not less than the lower limit, the reaction rate tends to increase and the furfural productivity tends to improve. Further, since furfural has a property of polymerizing under acidic conditions, it is preferable that the amount of catalyst is not more than the above-mentioned upper limit because side reactions are suppressed and the selectivity of furfural tends to be improved.

(Reaction solvent)
The reaction solvent used in the furfural production reaction is preferably water or a mixed solvent of water and an organic solvent. That is, as in the sugar liquid production reaction from non-edible biomass resources, it is possible to perform the reaction only with water, but it is also possible to perform the reaction by adding an organic solvent. From the viewpoint of cost advantage, it is preferable to use only water as the reaction solvent, and from the viewpoint of improving the yield of furfural, it is preferable to use water and an organic solvent as the reaction solvent.

  Although the reaction can be carried out with a homogeneous mixed solvent by adding an organic solvent, it suppresses the polymerization and decomposition reaction of furfural and improves the yield of furfural. It is preferable to use it. The amount of the organic solvent to be used is not particularly limited as long as the gist of the present invention is not impaired, but it is preferably 10 to 500% by weight, particularly preferably 10 to 200% by weight with respect to water.

The organic solvent to be used is not particularly limited, but any of the organic solvents described above as the organic solvent used in the sugar liquid production reaction from non-edible biomass resources can be used, and the same applies to suitable organic solvents. is there.
Also in the production reaction of furfural, the organic solvent is preferably a single solvent in consideration of solvent recovery and reuse, but two or more kinds may be used.

(HMF concentration in the reaction solution)
In the method for producing furfural of the present invention, the concentration of hydroxymethylfurfural (HMF) in the reaction solution is controlled to 5 ppm by weight or more and 1.2% by weight or less. When the HMF concentration in the reaction solution is equal to or higher than the above lower limit, the C5 saccharide / C6 saccharide content ratio in the obtained sugar solution can be increased, and a sugar solution having a high C5 saccharide content can be obtained. The furfural yield can be improved using the sugar solution. When the HMF concentration in the reaction solution is not more than the above upper limit, not only the by-product solids due to the polymerization of HMF itself can be reduced, but also a decrease in the furfural yield due to the reaction between HMF and furfural can be avoided. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to. The HMF concentration in the reaction solution is preferably 10 wt ppm or more and XX wt% or less, more preferably 100 wt ppm or more and 1.0 wt% or less, and further preferably 150 wt ppm or more and 0.5 wt% or less. Particularly preferably, the content is 200 ppm to 0.4% by weight.

The HMF concentration in the reaction solution can be controlled by adjusting the reaction conditions (temperature, time, saccharide concentration, catalyst concentration, etc.).
That is, when the reaction temperature is high, the amount of HMF produced increases and the HMF concentration increases, whereas when the reaction temperature is low, the amount of HMF produced decreases and the HMF concentration decreases.
Also, if the reaction time is long, the amount of HMF produced increases and the HMF concentration increases, and conversely, if the reaction time is short, the amount of HMF produced decreases and the HMF concentration decreases.
On the other hand, if the saccharide concentration is high, the amount of HMF produced increases and the HMF concentration increases, whereas if it is low, the amount of HMF produced decreases and the HMF concentration decreases.
Further, when the catalyst concentration is high, the amount of HMF generated increases and the HMF concentration increases, and conversely, when the catalyst concentration is low, the amount of HMF generated decreases and the HMF concentration decreases.
In addition, if the cellulose content in the non-edible biomass raw material is high, the amount of HMF produced increases and the HMF concentration increases, and conversely if it is low, the amount of HMF produced decreases and the HMF concentration decreases.
On the other hand, if the non-edible biomass weight average diameter is small, the HMF production amount increases and the HMF concentration increases, and conversely if the non-edible biomass weight average diameter is large, the HMF production amount decreases and the HMF concentration decreases.
Accordingly, the HMF concentration in the reaction solution can be controlled within the above-mentioned preferable range by appropriately adjusting these conditions within the above-mentioned preferable saccharide concentration, catalyst concentration and the following preferable reaction conditions. .

(Glucose concentration in the reaction solution)
In the method for producing furfural of the present invention, the glucose concentration in the reaction solution is not particularly limited, but is preferably 5 ppm by weight to 10% by weight, more preferably 10 ppm by weight to 5% by weight, Preferably they are 100 weight ppm or more and 2 weight% or less, Especially preferably, they are 150 weightppm or more and 1 weight% or less. If the glucose concentration in the reaction solution is equal to or higher than the above lower limit, the C5 saccharide / C6 saccharide content ratio in the resulting sugar solution can be increased, and a sugar solution having a high C5 saccharide content can be obtained. The furfural yield can be improved using the sugar solution. When the glucose concentration in the reaction solution is not more than the above upper limit value, not only the by-product solids due to the polymerization of glucose itself can be reduced, but also a decrease in the furfural yield due to the reaction between glucose and furfural can be avoided. Moreover, since the C5 saccharide / C6 saccharide content ratio in the obtained sugar liquid can be increased and a sugar liquid with a high C5 sugar content can be obtained, the furfural yield is improved using the sugar liquid. be able to.

The glucose concentration in the reaction solution can be controlled by adjusting the reaction conditions (temperature, time, saccharide concentration, catalyst concentration, etc.).
That is, when the reaction temperature is high, the amount of glucose produced increases and the glucose concentration increases, whereas when the reaction temperature is low, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, if the reaction time is long, the amount of glucose produced increases and the glucose concentration increases. Conversely, if the reaction time is short, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, when the saccharide concentration is high, the amount of glucose produced increases and the glucose concentration increases, whereas when it is low, the amount of glucose produced decreases and the glucose concentration decreases.
On the other hand, when the catalyst concentration is high, the glucose production amount increases and the glucose concentration becomes high. Conversely, when the catalyst concentration is low, the glucose production amount decreases and the glucose concentration becomes low.
Therefore, the glucose concentration in the reaction solution can be controlled within the above-mentioned preferable range by appropriately adjusting these conditions within the above-mentioned preferable saccharide concentration, catalyst concentration and the following preferable reaction conditions. .

(Reaction conditions)
Although the reaction temperature of the furfural production reaction is not particularly limited, specifically, it is preferably 100 ° C or higher, more preferably 120 ° C or higher, further preferably 160 ° C or higher, and preferably 250 ° C or lower. More preferably, it is 230 degrees C or less, Most preferably, it is 210 degrees C or less. When the reaction temperature is equal to or higher than the lower limit, the reaction rate tends to increase, and the furfural productivity is improved. It is preferable for the reaction temperature to be equal to or lower than the above upper limit value because the decomposition and polymerization of furfural and raw sugar are suppressed and the yield of furfural tends to be improved.

  The reaction time of the furfural production reaction varies depending on the sugar solution composition, the amount and type of catalyst used, and the reaction temperature. Specifically, it is preferably 0.02 hours or more, more preferably 0.1 hours or more, and particularly preferably 0. .5 hours or more, preferably 5 hours or less, more preferably 2 hours or less. When the reaction time is not less than the above lower limit, the progress of the reaction is promoted, and the conversion tends to improve the furfural yield. When the reaction time is not more than the above upper limit, the furfural is reduced. It is preferable because it tends to suppress decomposition and polymerization and improve the yield of furfural.

  The preferable range of the reaction pressure varies depending on the reaction temperature, but is preferably 0.1 to 5.0 MPaG, more preferably 0.5 to 3.0 MPaG, and particularly preferably 1.0 to 2.5 MPaG.

(Reaction format)
The reaction form of the furfural production reaction is not particularly limited, and may be a batch type, a semi-batch type, a continuous type, or a combination of these. From the viewpoint of improving productivity, semi-batch reaction and continuous reaction are preferable, and from the viewpoint of easy operation, batch reaction is preferable. In the continuous reaction, a continuous tube reactor or a continuous tank reactor can be used. Moreover, the reactive distillation system which distills while producing the furfural which is a reaction product may be used. For example, as described in International Publication No. 2013/102027, a method for continuously extracting a mixture of furfural and water using a furfural production reactor as a reactive distillation format, or as described in International Publication No. 2012/115706. Alternatively, a method of continuously extracting furfural from the aqueous phase using an organic solvent can be used. In the case of the reactive distillation method, it may be carried out at reduced pressure or at normal pressure. One reactor may be used, or a plurality of reactors may be combined.

(Furfural collection)
In order to recover furfural from the reaction liquid containing furfural obtained by the dehydration reaction of C5 saccharide in the sugar liquid as described above, this dehydration is usually performed when an organic solvent that separates from water is used. The reaction solution is separated into two layers, an organic layer containing furfural and an aqueous layer, and then the furfural contained in the organic layer is purified by distillation separation to obtain a product furfural. When only water or a solvent that forms a uniform layer with water is used, a furfural product is obtained by purifying the reaction solution containing furfural by distillation separation or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.

  In the following Examples, moisture analysis was performed using the Karl Fischer method (measured by CA-21 manufactured by Mitsubishi Chemical). Analysis of the amount of hydroxymethylfurfural (HMF) in the reaction solution, the amount of furfural (FRL) in the crude furfural, and the amount of hydroxymethylfurfural (HMF) was performed by gas chromatography (GC), and the area percentage was calculated. The value obtained by subtracting the water concentration from 100% by weight was calculated, and the remaining weight% was calculated by the area percentage of each component of the gas chromatography.

Further, the content of each sugar (xylose, xylooligosaccharide) in the sugar solution was analyzed by the high performance liquid chromatograph LC-20AD system (manufactured by Shimadzu Corporation) (LC) under the following conditions.
Column: Shodex Sugar KS-801 300 μm × 8.0 mm and Shodex Sugar KS-802 300 μm × 8.0 mm connected Mobile phase: water 0.7 mL 80 ° C.

[Example 1]
<Manufacture of sugar solution>
A 100 mL microautoclave was charged with 12.0 g of bagasse, 46.2 g of demineralized water as a reaction solvent, and 1.8 g of lactic acid as a catalyst. The container was sealed, and the internal space was replaced with nitrogen. While stirring the contents, the temperature was raised to 170 ° C., and the reaction was carried out by heating and stirring at 170 ° C. and 0.5 MPaG for 10 minutes.

After completion of the reaction, the mixture is allowed to cool to room temperature while maintaining stirring, and after the entire amount of the reaction solution in the autoclave has been recovered, the bagasse residue is separated from the reaction solution by solid-liquid separation, and the number of carbons in the resulting separation solution (sugar solution) The content of 5 monosaccharides (xylose) and polysaccharides containing 5 monosaccharides (xylooligosaccharides) were determined by LC analysis. Moreover, the amount of FRL in the sugar solution was determined by GC analysis, and the weight ratio (percentage) of furfural was calculated as the bagasse-based FRL yield.
The amount of xylan in the bagasse was calculated by detergent analysis. Bagasse was fractionated into cellulose, hemicellulose, and lignin, and the amount of hemicellulose obtained was calculated as the amount of xylan. Since 25 g of hemicellulose was contained in 100 g of bagasse, the amount of xylan in 100 g of bagasse was 25 g.
The C5 yield was calculated by the following formula using xylan as a (C ₅ H ₈ O ₄ ) _n unit. Here, the yield is a yield converted per monocyclic ring having 5 carbon atoms.
C5 yield (%) =
((Amount of xylose after reaction (mol) + Xylooligosaccharide after reaction (mol) + Furfural after reaction (mol)) / Amount of charged sugar (xylan) (mol)) × 100
These results are shown in Table 1.

[Example 2]
In the production of the sugar liquid in Example 1, everything was carried out in the same manner except that the temperature was raised to 190 ° C. and heated and stirred at 190 ° C. for 30 minutes. The results are shown in Table 1.

[Example 3]
The production of the sugar solution in Example 2 was performed in the same manner except that bagasse was 15.0 g and lactic acid was 13.3 g. The results are shown in Table 1.

[Example 4]
In the production of the sugar liquid in Example 1, everything was carried out in the same manner except that the temperature was raised to 190 ° C. and heated and stirred at 190 ° C. for 4 hours. The results are shown in Table 1.

[Comparative Example 1]
The production of the sugar solution in Example 1 was performed in the same manner except that bagasse was changed to 0.6 g and demineralized water was changed to 57.6 g. The results are shown in Table 1.

[Comparative Example 2]
The production of the sugar liquid in Example 4 was performed in the same manner except that 1.2 g of HMF was added to the raw material. The results are shown in Table 1.

  From Table 1, it can be seen that the C5 component yield of the obtained sugar liquid can be increased by setting the HMF concentration in the reaction liquid within the specified range of the present invention.

<Manufacture of furfural>
[Example 5]
25 g of the sugar solution obtained in Example 1 and 25 g of tetralin were placed in a 100 mL microautoclave and the container was sealed, and then the internal space was replaced with nitrogen. While stirring the contents, the temperature was raised to 190 ° C., and the reaction was carried out by heating and stirring at 190 ° C. and 0.96 MPaG for 15 minutes.
After completion of the reaction, the mixture was allowed to cool to room temperature while maintaining stirring, and the entire reaction solution in the autoclave was recovered, and this was used as crude furfural.

The amount of HMF in the reaction raw material before heating and stirring was analyzed by gas chromatography (GC), and was calculated by area percentage. The results are shown in Table 2.
Moreover, the amount of FRL in the crude furfural after the reaction was measured, and the weight ratio (percentage) of furfural with respect to the charged bagasse amount (converted as the amount of bagasse subjected to the dehydration reaction) was calculated as the FRL yield. The results are shown in Table 2.

[Example 6]
The production of furfural in Example 5 was carried out in the same manner except that the sugar solution used was the sugar solution obtained in Example 2. The results are shown in Table 2.

[Example 7]
The production of furfural in Example 5 was carried out in the same manner except that the sugar solution used was the sugar solution obtained in Example 3. The results are shown in Table 2.

[Example 8]
The production of furfural in Example 5 was carried out in the same manner except that the sugar solution used was the sugar solution obtained in Example 4. The results are shown in Table 2.

[Comparative Example 3]
The production of furfural in Example 5 was carried out in the same manner except that the sugar solution used was the sugar solution obtained in Comparative Example 1. The results are shown in Table 2.

[Comparative Example 4]
The production of furfural in Example 5 was carried out in the same manner except that the sugar solution used was the sugar solution obtained in Comparative Example 2. The results are shown in Table 2.

  From the comparison between Examples 5 to 8 and Comparative Examples 3 and 4 in Table 2, it can be seen that furfural can be produced with a high furfural yield by setting the HMF concentration in the reaction solution within a predetermined range.

Claims (12)

  In a method for producing a sugar solution for furfural production raw material by reacting in a reaction vessel in the presence of a solvent using a non-edible biomass resource as a raw material, hydroxymethylfurfural in the reaction solution in the reaction vessel The manufacturing method of the sugar liquid for furfural manufacturing raw materials which controls the density | concentration of 5 weight ppm or more and 2 weight% or less.   The manufacturing method of the sugar liquid for furfural manufacturing raw materials of Claim 1 which controls to control the density | concentration of the hydroxymethylfurfural in the said reaction liquid to 150 weight ppm or more and 0.5 weight% or less.   The manufacturing method of the sugar liquid for furfural manufacturing raw materials of Claim 1 or 2 with which the said catalyst contains the organic acid of pKa3-5.   The manufacturing method of the sugar liquid for furfural manufacturing raw materials in any one of Claims 1-3 whose said organic acid is any 1 type, or 2 or more types of acetic acid, lactic acid, and formic acid.   The manufacturing method of the sugar liquid for furfural manufacturing raw materials in any one of Claims 1-4 whose said solvent is a mixture of water and an organic solvent.   The manufacturing method of the sugar liquid for furfural manufacturing raw materials in any one of Claims 1-5 whose said non-edible biomass resource is bagasse.   In the method of producing a furfural by using a non-edible biomass resource as a raw material to obtain a sugar solution by reacting in a reaction vessel using a catalyst in the presence of a solvent, and reacting the sugar solution in the reaction vessel. The manufacturing method of a furfural which controls the density | concentration of the hydroxymethylfurfural in the reaction liquid in a reaction tank to 5 weight ppm or more and 1.2 weight% or less.   The method for producing furfural according to claim 7, wherein the concentration of hydroxymethylfurfural in the reaction solution is controlled to 150 wtppm or more and 0.5 wt% or less.   The method for producing furfural according to claim 7 or 8, wherein the catalyst contains an organic acid having a pKa of 3 or more and 5 or less.   The method for producing furfural according to any one of claims 7 to 9, wherein the organic acid is one or more of acetic acid, lactic acid, and formic acid.   The manufacturing method of the furfural in any one of Claims 7-10 whose said solvent is a mixture of water and an organic solvent.   The method for producing furfural according to any one of claims 7 to 11, wherein the non-edible biomass resource is bagasse.