Methods for producing lignin soluble in organic solvents.

Abstract

DEPCT65 The method for producing lignin soluble in organic solvents is an integrated approach. The conditioning process involves pretreating herbaceous biomass using a digestion method. With diluted sulfuric acid, the saccharification step involves the practical operation of saccharification. Modified herbaceous biomass obtained through enzymatic modification, a process... Solid-liquid separation involves the process of separating solids from liquids and removing products from the mixture. Saccharification is obtained in the saccharification step to obtain the residue from saccharification. And the extraction process involves adding organic solvents to the saccharification residue for extraction. Lignin is soluble in organic solvents, where, during the conditioning process, the intensity of the action is affected. The digestion method using dilute sulfuric acid is controlled in such a way that each value of the number... Beta-O-4 bonds, average molecular weight by weight, molecular weight distribution, and number of... The hydroxyl groups of lignin that are soluble in the organic solvent to be obtained will be within the specified range. Predetermined ----------------------------------------------------------- The method for producing lignin soluble in organic solvents is an integrated approach. The initial conditioning procedure involves performing preliminary conditioning on herbaceous biomass using... The method of digestion with dilute sulfuric acid, a saccharification step with pretreatment action. With saccharification of biomass from initially modified herbaceous plants obtained during the modification process. Enzymatic preliminary conditions, a solid-liquid separation process that involves the separation of solids and liquids. The liquid and products from the saccharification process obtained in the saccharification step. To obtain the residue from saccharification, an extraction process is performed by adding organic solvents to the residue. From saccharification to the extraction of lignin soluble in organic solvents, where the adjustment step is performed. Initial conditions, strength of conditioning by diluted sulfuric acid digestion method. It is controlled in such a way that each value of the number of beta-O-4 bonds, the average molecular weight by weight, The distribution of molecular weight and the number of hydroxyl groups of lignin soluble in solvents. The dissolved organic matter to be obtained will be within a predetermined range.

Description

Method for producing organic solvent-soluble lignin

[0001] The present invention relates to a method for producing organic solvent-soluble lignin. This application claims priority to Japanese Patent Application No. 2019-165546 filed on September 11, 2019, the contents of which are incorporated herein by reference.

[0002] In recent years, the use of biomass, which is made from plant resources, has been attracting attention from the perspectives of global warming countermeasures and the effective utilization of waste. Generally, carbohydrates such as sugarcane and starch such as corn are widely used as raw materials for producing compounds such as ethanol from biomass. However, these raw materials were originally used as food or feed, and their long-term use as industrial resources poses the risk of competition with food or feed uses and resulting in a rise in raw material prices.

[0003] Therefore, technological development is underway to utilize non-edible biomass as an energy resource. Cellulose is the most abundant non-edible biomass on Earth, and most of it exists as lignocellulose, a complex of aromatic polymers such as lignin and hemicellulose.

[0004] Ethanol production using lignocellulosic biomass as a feedstock involves a pretreatment process in which the biomass feedstock is thermochemically pretreated; a saccharification process in which the biomass after the pretreatment process is enzymatically treated to produce a saccharified solution; a fermentation process in which a microbial culture solution is added to the saccharified solution obtained in the saccharification process to carry out ethanol fermentation; and a purification process in which ethanol is separated from the fermented solution obtained in the fermentation process by distillation or other methods. This ethanol production process poses a problem: a large amount of fermentation residue is generated because lignin remains as a solid. This fermentation residue is generally disposed of in boilers or through methane fermentation in an attached factory, and is currently not effectively utilized.

[0005] Similarly, in the papermaking process using non-edible biomass as a raw material, lignin-based products (black liquor, lignin sulfonate) are generated as residues, and technologies for their effective utilization have been developed over many years. However, because the lignin is sulfonated or chlorinated during the chemical decomposition process of the biomass, it is difficult to utilize, and most of the lignin is only used as a fuel for boiler heat sources.

[0006] On the other hand, lignin decomposition can produce phenol derivatives and other compounds, which can be used as raw materials for chemical industrial products such as resin raw materials, composite materials, surfactants, etc. Therefore, there is a need for the development of a method for efficiently producing lignin decomposition products.

[0007] Patent Literature 1 discloses a method for producing lignin degradation products by treating lignin-containing biomass with a mixed solvent having a water / alcohol molar ratio of 1 / 1 to 20 / 1. Patent Literature 2 discloses a method for producing low-molecular-weight lignin by heating lignin-containing biomass in a mixed solvent of hydrocarbon and alcohol in the presence of an acid catalyst. Patent Literature 3 discloses a method for producing lignin degradation products by pretreating lignin-containing biomass with a combination of hydrothermal treatment and pulverization, enzymatically saccharifying the pretreated biomass, subjecting the resulting enzymatic saccharification residue to further hydrothermal treatment in an autoclave, obtaining a solid from solid-liquid separation of the treated product, and dissolving the solid in an organic solvent. Patent Literature 4 discloses a method for producing lignin degradation products by enzymatically saccharifying lignin-containing biomass to obtain a saccharification residue, heat-treating the saccharification residue in a mixed solvent containing water and an organic solvent having a solubility in water of 90 g / L or more at 20°C to obtain a heat-treated liquid containing lignin degradation products, and then subjecting the heat-treated liquid to solid-liquid separation to remove insoluble matter.

[0008] Japanese Patent Publication No. 2014-015439 Japanese Patent Publication No. 2016-050200 Japanese Patent Publication No. 2015-157792 Japanese Patent Publication No. 2013-241391

[0009] Lignin contained in biomass raw materials has a complex structure, and its properties change randomly depending on the various conditions in the method for producing lignin degradation products. Therefore, the methods described in Patent Documents 1 to 4, etc., cannot produce lignin with specific properties. Furthermore, no attempt has been made to control the various conditions in the production method in order to obtain lignin with specific properties.

[0010] The present invention has been made in view of the above circumstances, and provides a method for producing organic solvent-soluble lignin having specific properties.

[0011] That is, the present invention includes the following aspects: (1) A method for producing organic-solubilizable lignin, comprising: a pretreatment step of pretreating herbaceous biomass by dilute sulfuric acid cooking, a saccharification step of enzymatically saccharifying the pretreated herbaceous biomass obtained in the pretreatment step, a solid-liquid separation step of obtaining a saccharification residue by solid-liquid separation of the saccharification product obtained in the saccharification step, and an extraction step of adding an organic solvent to the saccharification residue to extract organic-solubilizable lignin, wherein the treatment intensity by the dilute sulfuric acid cooking method is controlled in the pretreatment step so that the β-O-4 bond content, weight-average molecular weight, molecular weight distribution, and hydroxyl group content of the organic-solubilizable lignin obtained are each within a predetermined range. (2) The method for producing organic solvent-soluble lignin according to (1), wherein the intensity of the treatment by the dilute sulfuric acid cooking method is controlled in the pretreatment step so that the content of thioacidolysis monomers in the organic solvent-soluble lignin, as determined by the thioacidolysis method as the content of the β-O-4 bond, is in the range of 95 μmol / g or more and 248 μmol / g or less. (3) The method for producing organic solvent-soluble lignin according to (1), wherein the intensity of the treatment by the dilute sulfuric acid cooking method is controlled in the pretreatment step so that the weight average molecular weight of the organic solvent-soluble lignin, as determined by gel permeation chromatography, is in the range of 2,400 or more and 4,200 or less. (4) The method for producing organic solvent-soluble lignin according to (1), wherein the intensity of the treatment by the dilute sulfuric acid cooking method is controlled in the pretreatment step so that the molecular weight distribution of the organic solvent-soluble lignin, as determined by gel permeation chromatography, is in the range of 1.0 or more and 2.0 or less. (5) The method for producing an organic solvent-soluble lignin according to claim 1, wherein the intensity of the treatment by the dilute sulfuric acid cooking method in the pretreatment step is controlled so that the content of phenolic hydroxyl groups in the organic solvent-soluble lignin, as determined by phosphorylating the hydroxyl groups and quantitating the hydroxyl groups by phosphorus-31 nuclear magnetic resonance spectroscopy, is in the range of 7 mmol / g or more and 32 mmol / g or less, and the content of alcoholic hydroxyl groups is in the range of 6 mmol / g or more and 196 mmol / g or less.(6) In the pretreatment step, the treatment strength by the dilute sulfuric acid cooking method is 1.0 or more and 3.0 or less in terms of CSI represented by the following formula (I). The method for producing organic solvent-soluble lignin according to any one of (1) to (4).

[0012]

[0013] (In formula (I), X is time, Y is temperature, and Z is pH.)

[0014] (7) The method for producing organic-solvent-soluble lignin according to (6), wherein, in the pretreatment step, the CSI is controlled to approach 1.0 in order to increase the content of β-O-4 bonds in the organic-solvent-soluble lignin, and, conversely, the CSI is controlled to approach 3.0 in order to decrease the content of β-O-4 bonds in the organic-solvent-soluble lignin. (8) The method for producing organic-solvent-soluble lignin according to (6), wherein, in the pretreatment step, the CSI is controlled to approach 1.0 in order to decrease the weight-average molecular weight and molecular weight distribution of the organic-solvent-soluble lignin, and, conversely, the CSI is controlled to approach 3.0 in order to increase the weight-average molecular weight and molecular weight distribution of the organic-solvent-soluble lignin. (9) The method for producing an organic-solubilized lignin according to (6), wherein, in the pretreatment step, the CSI is controlled to approach 1.0 in order to increase the hydroxyl group content of the organic-solubilized lignin, and the CSI is controlled to approach 3.0 in order to decrease the hydroxyl group content of the organic-solubilized lignin.

[0015] According to the production method of the above aspect, it is possible to provide a method for producing organic solvent-soluble lignin having specific properties.

[0016] 2A is a graph showing the content of thioacidolysis monomers quantified by the thioacidolysis method for organic solvent-soluble lignin obtained using napier grass pretreated under CSI conditions of 1.27, 1.57, 2.35, and 2.95 in Example 1. FIG. 2B is a chromatogram obtained by measuring by gel permeation chromatography (GPC) the organic solvent-soluble lignin obtained using napier grass pretreated under CSI conditions of 1.27, 1.87, 2.35, 2.65, and 2.95 in Example 1. FIG. 2C is a graph showing the measured weight-average molecular weight of the peak with the highest weight-average molecular weight among the peaks in the chromatogram of FIG. 2A. The hydroxyl groups of the organic solvent-soluble lignin obtained using napier grass pretreated under CSI conditions of 1.27, 1.57, 1.87, 2.35, and 2.95 in Example 1 were phosphorylated to form lignin. ３１ 1 is a graph showing the total content of phenolic hydroxyl groups and alcoholic hydroxyl groups quantified by P-NMR.

[0017] The method for producing organic solvent-soluble lignin according to an embodiment of the present invention (hereinafter sometimes abbreviated as "the production method of the present embodiment") will be described in detail below. In this specification and claims, the meanings of various terms are defined as follows.

[0018] <Herbaceous Biomass> In the production method of this embodiment, herbaceous biomass is used as the raw material. Furthermore, residues generated in the process of producing bioethanol, biobutanol, biochemicals, or the like from cellulose and hemicellulose in herbaceous biomass may be used instead of herbaceous biomass. The herbaceous biomass used as the raw material may be pulverized and may be in any form, such as blocks, chips, or powder. Hereinafter, herbaceous biomass may be simply referred to as "biomass."

[0019] Examples of herbaceous biomass include bamboo, palm tree trunks and empty bunches, palm fruit fibers and seeds, bagasse (sugarcane and high-biomass sugarcane residue), rice straw, wheat straw, corn cobs, stems and leaves, and residues (corn stover, corn cobs, corn hulls), sorghum (including sweet sorghum) residues, and those obtained from grasses such as switchgrass, Erianthus, and Napier grass; and residues generated during the vegetable oil extraction process from energy crops, such as Jatropha seed coats and shells, cashew shells, and energy crops. Among these, herbaceous biomass obtained from grasses is preferred from the standpoint of availability and compatibility with the production method of this embodiment, and bagasse or Napier grass is more preferred.

[0020] <Cellulose and Hemicellulose> In this specification, "cellulose" includes hexose, a six-carbon structural unit. Therefore, when cellulose is hydrolyzed, it produces hexose monosaccharides (e.g., glucose) each consisting of six carbon atoms, and hexose oligosaccharides (e.g., cellobiose) in which multiple such monosaccharides are linked together.

[0021] "Hemicellulose" includes complex polysaccharides such as glucomannan and glucuronoxylan, which are composed of pentoses (C5 sugars) with five carbon units such as xylose, and hexoses (C6 sugars) with six carbon units such as mannose, arabinose, and 4-O-methylglucuronic acid. Thus, when hemicellulose is hydrolyzed, it produces pentose monosaccharides with five carbons, pentose oligosaccharides in which multiple pentose monosaccharides are linked together, hexose monosaccharides with six carbons, hexose oligosaccharides in which multiple hexose monosaccharides are linked together, and oligosaccharides in which multiple pentose and hexose monosaccharides are linked together.

[0022] In general, the composition ratio and amount of monosaccharides or oligosaccharides produced from hemicellulose or cellulose vary depending on the pretreatment method and the type of herbaceous biomass used as a raw material.

[0023] <Lignin> Generally, lignin is a natural polymer that is one of the three main components of herbaceous biomass. Among herbaceous biomass, bagasse contains 5% by mass to 30% by mass of lignin.

[0024] Lignin has a basic skeleton consisting of an aromatic nucleus (benzene nucleus), and is classified into G nucleus, S nucleus, and H nucleus based on its structure. A G nucleus has one methoxy group (-OCH ３ ), where an S nucleus has two methoxy groups at the ortho position, and an H nucleus has no methoxy groups at the ortho position. Lignin in herbaceous biomass such as bagasse contains all of the H nucleus, G nucleus, and S nucleus as basic skeletons. Among lignins derived from woody biomass, lignin derived from coniferous trees has a G nucleus as its basic skeleton, while lignin derived from broad-leaved trees has a G nucleus and an S nucleus as its basic skeleton.

[0025] Lignin has a variety of intermolecular bond types, the most common of which is the β-O-4 bond, an ether bond that accounts for approximately 50 to 70 mol% of all bond types within the lignin molecule. The β-O-4 bond is a bond type represented by the following formula (II) and forms the linear structure of lignin. During the polymerization process of lignin in plant cells, the β-position of the side chain of a monomer and the 4-position of the aromatic nucleus of an adjacent monomer are continuously linked to form a polymer.

[0026]

[0027] As used herein, the term "water-soluble lignin" refers to lignin that is soluble in water, specifically lignin contained in the liquid component when a saccharification product after a saccharification step, a fermentation product after a fermentation step, and a waste liquid after a purification step are subjected to solid-liquid separation. Water-soluble lignin is presumed to be soluble in water because it has a relatively small number-average molecular weight of approximately 1,000 or less.

[0028] "Water-insoluble lignin" refers to lignin that is insoluble in water, and specifically refers to lignin contained in solid components (i.e., saccharification residue, fermentation residue, and solid residue) obtained by solid-liquid separation of a saccharification product after a saccharification step, a fermentation product after a fermentation step, and a waste liquid after a purification step, which will be described later. Water-insoluble lignin has a relatively large number-average molecular weight of more than 1,000 and not more than 10,000, and is therefore presumed to be insoluble in water.

[0029] The term "saccharification product" as used herein includes a saccharification solution, which is a liquid component, and a saccharification residue, which is a solid component; the saccharification solution contains water-soluble lignin, and the saccharification residue contains water-insoluble lignin. The term "fermentation product" includes a fermentation solution, which is a liquid component, and a fermentation residue, which is a solid component; the fermentation solution contains water-soluble lignin, and the fermentation residue contains water-insoluble lignin. The waste liquid includes a liquid residue, which is a liquid component, and a solid residue, which is a solid component; the liquid residue contains water-soluble lignin, and the solid residue contains water-insoluble lignin.

[0030] "Organic solvent-soluble lignin" refers to lignin that is soluble in an organic solvent. Specifically, it refers to lignin contained in the liquid component when water-insoluble lignin is added to an organic solvent, mixed and stirred, and then solid-liquid separation is performed in the extraction step described below. Since organic solvent-soluble lignin has a number average molecular weight of more than 1,000 and approximately 3,000 or less, it is presumed to be insoluble in water but soluble in organic solvents.

[0031] The term "organic solvent-insoluble lignin" refers to lignin contained in the solid component when water-insoluble lignin is added to an organic solvent, mixed and stirred, and then subjected to solid-liquid separation in the extraction step described below. The organic solvent-insoluble lignin has a relatively large number average molecular weight of more than 3,000 and not more than 10,000, and is therefore presumed to be insoluble in water and organic solvents.

[0032] The number average molecular weight of each lignin can be measured by gel permeation chromatography (GPC).

[0033] <Saccharifying enzymes> In this specification, the term "saccharifying enzymes" includes cellulase that decomposes cellulose, hemicellulase that decomposes hemicellulose, and amylase that decomposes starch.

[0034] The cellulase may be any cellulase that decomposes cellulose into monosaccharides or oligosaccharides such as glucose, and examples thereof include those having at least one activity of endoglucanase (EG), cellobiohydrolase (CBH), and β-glucosidase (BGL). From the viewpoint of enzymatic activity, an enzyme mixture having each of these activities is preferred.

[0035] The hemicellulase may be any enzyme that decomposes hemicellulose into monosaccharides or oligosaccharides such as xylose, and examples thereof include enzymes having at least one of the activities of xylanase, xylosidase, mannanase, galactosidase, glucuronidase, and arabinofuranosidase. From the viewpoint of enzymatic activity, an enzyme mixture having each of these activities is preferred.

[0036] The origin of these saccharifying enzymes such as cellulase and hemicellulase is not limited, and for example, saccharifying enzymes such as cellulase and hemicellulase derived from microorganisms such as those of the genus Trichoderma, Acremonium, Aspergillus, Bacillus, Pseudomonas, Penicillium, Aeromonus, Irpex, Sporotrichum, and Humicola can be used.

[0037] <Method for Producing Organic Solvent-Soluble Lignin> The production method of this embodiment includes the following steps: a pretreatment step of pretreating herbaceous biomass by dilute sulfuric acid cooking; a saccharification step of enzymatically saccharifying the pretreated herbaceous biomass obtained in the pretreatment step; a solid-liquid separation step of obtaining a saccharification residue by solid-liquid separation of the saccharification treatment product obtained in the saccharification step; and an extraction step of adding an organic solvent to the saccharification residue to extract organic solvent-soluble lignin.

[0038] In the production method of this embodiment, in the pretreatment step, the intensity of the treatment by the dilute sulfuric acid cooking method is controlled so that the content of β-O-4 bonds, weight average molecular weight, molecular weight distribution, and hydroxyl group content of the resulting organic solvent-soluble lignin are each within a predetermined range.

[0039] As will be described in the Examples below, the inventors have found that there is a correlation between the intensity of the treatment using the dilute sulfuric acid cooking method in the pretreatment step and the content of β-O-4 bonds, weight-average molecular weight, molecular weight distribution, and hydroxyl group content. In order to obtain organic solvent-soluble lignin in which these properties fall within predetermined ranges, the inventors have completed the present invention by controlling the intensity of the treatment using the dilute sulfuric acid cooking method in the pretreatment step.

[0040] The content of β-O-4 bonds in the organic solvent-soluble lignin obtained by the production method of this embodiment can be expressed as the content of thioacidolysis monomer in the organic solvent-soluble lignin quantified by the thioacidolysis method. According to the production method of this embodiment, it is possible to produce organic solvent-soluble lignin having a thioacidolysis monomer content in the range of 95 μmol / g to 248 μmol / g, preferably 173 μmol / g to 248 μmol / g, and more preferably 201 μmol / g to 248 μmol / g.

[0041] The content of the thioacidolysis monomer can be determined by the thioacidolysis method, and specifically, can be measured using the method shown in the examples below.

[0042] The production method of this embodiment can produce organic solvent-soluble lignin having a weight average molecular weight, as determined by gel permeation chromatography (GPC), in the range of 2400 to 4200. The weight average molecular weight, for which a numerical range is specified here, is the measured value of the weight average molecular weight of the peak with the largest weight average molecular weight among the peaks in a chromatogram obtained by measuring the organic solvent-soluble lignin by GPC, as shown in the examples described later.

[0043] The weight average molecular weight can be determined by GPC, and specifically, can be measured using the method shown in the examples below.

[0044] The production method of this embodiment can produce organic solvent-soluble lignin having a molecular weight distribution, as determined by GPC, in the range of 1.0 to 2.0. The molecular weight distribution, whose numerical range is specified here, is the value obtained by dividing the measured value of the weight average molecular weight Mw of the peak with the largest weight average molecular weight among the peaks in a chromatogram obtained by measuring the organic solvent-soluble lignin by the measured value of the number average molecular weight Mn, as shown in the examples described later.

[0045] The molecular weight distribution can be calculated by measuring the number average molecular weight Mn and the weight average molecular weight Mw by a GPC method and dividing the weight average molecular weight Mw by the number average molecular weight Mn. Specifically, it can be calculated using the method shown in the examples below.

[0046] Examples of hydroxyl groups possessed by organic solvent-soluble lignin include various hydroxyl groups such as alcoholic hydroxyl groups (including modified groups of sugars or related compounds) bonded to aliphatic hydrocarbon groups, hydroxyl groups (phenolic hydroxyl groups, etc.) bonded to aromatic hydrocarbon groups, and OH groups at the terminals of carboxy groups. Among these, from the viewpoint of subjecting the obtained organic solvent-soluble lignin to various modifications, it is preferable for the organic solvent-soluble lignin to have a large number of phenolic hydroxyl groups and alcoholic hydroxyl groups. The phenolic hydroxyl groups also include hydroxyl groups bonded to the benzene rings of syringyl and guaiacyl. In the production method of this embodiment, the hydroxyl groups are phosphorylated to obtain the lignin-containing ... ３１ In the production method of this embodiment, it is possible to produce organic solvent-soluble lignin in which the total content of phenolic hydroxyl groups and alcoholic hydroxyl groups in the organic solvent-soluble lignin, as determined by P-NMR spectroscopy ( ), is in the range of 13 mmol / g or more and 228 mmol / g or less. In addition, in the production method of this embodiment, the hydroxyl groups are phosphorylated and then analyzed by phosphorus-31 nuclear magnetic resonance spectroscopy ( ３１It is possible to produce organic solvent-soluble lignin having a phenolic hydroxyl group content in the range of 7 mmol / g or more and 32 mmol / g or less, and an alcoholic hydroxyl group content in the range of 6 mmol / g or more and 196 mmol / g or less, as determined by P-NMR spectroscopy.

[0047] According to the production method of this embodiment, an organic solvent-soluble lignin can be obtained in which the β-O-4 bond content, weight average molecular weight, molecular weight distribution, and hydroxyl group content are within the above-mentioned ranges. Next, each step of the production method of this embodiment will be described in detail below.

[0048] [Pretreatment Step] In the pretreatment step, herbaceous biomass is pretreated by dilute sulfuric acid cooking.

[0049] The dilute sulfuric acid cooking method involves heating and pressurizing in the presence of dilute sulfuric acid. The dilute sulfuric acid used can be added so that the pH of the pretreatment solution containing herbaceous biomass is approximately 0.8 to 6.7.

[0050] In the pretreatment step, lignin undergoes both decomposition and condensation polymerization reactions, resulting in structural changes depending on the pretreatment conditions. Therefore, differences in the pretreatment conditions affect the chemical structure and degree of condensation polymerization of lignin, which in turn affects the ratios of water-soluble and water-insoluble lignin in the liquid fraction (saccharification solution) and solid fraction (saccharification residue) in the solid-liquid separation step, as well as the ratios of organic solvent-soluble and organic solvent-insoluble lignin in the liquid fraction (extract) and solid fraction (extraction residue) in the extraction step.

[0051] Furthermore, the intensity of the pretreatment, i.e., the intensity of decomposition of lignin, cellulose, and hemicellulose, can be controlled by three parameters: temperature, time, and pH. Therefore, the treatment intensity can be evaluated by the combined severity index (CSI) represented by the following formula (I), which uses the above three parameters as variables. The larger the CSI value, the higher the biomass decomposition intensity tends to be, and the smaller the CSI value, the lower the biomass decomposition intensity tends to be. The target decomposition intensity can be achieved by setting the pretreatment conditions so that the CSI, which is the value calculated from formula (I), falls within a predetermined range.

[0052]

[0053] (In formula (I), X is time, Y is temperature, and Z is pH.)

[0054] As shown in the examples described later, there is a correlation between the β-O-4 bond content, weight-average molecular weight, molecular weight distribution, and hydroxyl group content of the resulting organic solvent-soluble lignin and the CSI value. Therefore, the CSI value is controlled to ensure that the β-O-4 bond content, weight-average molecular weight, molecular weight distribution, and hydroxyl group content of the organic solvent-soluble lignin fall within the above-mentioned ranges.

[0055] Furthermore, the larger the CSI value, the higher the biomass decomposition intensity. However, if the CSI value is too large, the content of β-O-4 bonds and the content of hydroxyl groups decrease, the weight-average molecular weight becomes relatively large, and the width of the molecular weight distribution tends to increase, as shown in the examples described below. This is presumably because, as the biomass decomposition intensity increases, the β-O-4 bonds decrease and the side chains increase, the condensation polymerization reaction becomes more important than the decomposition reaction, the molecular weight increases, and denaturation progresses, resulting in a decrease in phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0056] When the content of β-O-4 bonds is to be within a desired range, for example, in order to increase the content of thioacidolysis monomers in organic solvent-soluble lignin quantified by the thioacidolysis method, the CSI value is controlled to be small, whereas in order to decrease the content of the thioacidolysis monomers, the CSI value is controlled to be large.

[0057] When the weight average molecular weight and molecular weight distribution are to be within the desired ranges, for example, the CSI value is controlled to be small in order to decrease the weight average molecular weight and molecular weight distribution of the organic solvent-soluble lignin, while the CSI value is controlled to be large in order to increase the weight average molecular weight and molecular weight distribution of the organic solvent-soluble lignin.

[0058] In order to adjust the content of hydroxyl groups to a desired range, for example, the hydroxyl groups may be phosphorylated. ３１ In order to increase the total content of phenolic hydroxyl groups and alcoholic hydroxyl groups in organic solvent-soluble lignin quantified by P-NMR, the CSI value is controlled to be small, while in order to decrease the total content of phenolic hydroxyl groups and alcoholic hydroxyl groups, the CSI value is controlled to be large.

[0059] For these reasons, in order to produce organic solvent-soluble lignin having a thioacidolysis monomer content of 95 μmol / g or more and 248 μmol / g or less, a weight average molecular weight of 2,400 or more and 4,200 or less, a molecular weight distribution of 1.0 or more and 2.0 or less, and a total content of phenolic hydroxyl groups and alcoholic hydroxyl groups of 13 mmol / g or more and 228 mmol / g or less (specifically, the content of phenolic hydroxyl groups is 7 mmol / g or more and 32 mmol / g or less, and the content of alcoholic hydroxyl groups is 6 mmol / g or more and 196 mmol / g or less), the CSI is preferably 1.0 or more and 3.0 or less, more preferably 1.2 or more and 2.8 or less, even more preferably 1.5 or more and 2.7 or less, and particularly preferably 1.5 or more and 2.5 or less. By having a CSI within the above range, it is possible to produce organic solvent-soluble lignin having a β-O-4 bond content, weight average molecular weight and molecular weight distribution, and a hydroxyl group content within the above ranges.

[0060] In the pretreatment step, specific treatment conditions that result in the above CSI range are preferably a pH of 0.8 or more but less than 1.5, more preferably 0.8 or more but 1.4 or less, and even more preferably 0.8 or more but 1.2 or less.

[0061] The temperature can be, for example, 100°C or higher and 250°C or lower, 120°C or higher and 200°C or lower, or 150°C or higher and 180°C or lower.

[0062] The time can be, for example, 3 minutes or more and 150 minutes or less, 5 minutes or more and 120 minutes or less, 7 minutes or more and 90 minutes or less, or 8 minutes or more and 40 minutes or less.

[0063] The reaction vessel used in the dilute sulfuric acid cooking method is not particularly limited as long as it is a steam supply type, but possible forms of treatment include placing the material in an apparatus that has an acid-resistant heating and pressure device such as an autoclave, or an acid-resistant heating and pressure vessel and is further equipped with a screw feeder so that the material can be treated continuously.

[0064] In the pretreatment step, the biomass may be pulverized using a mill or the like before or after the treatment by the dilute sulfuric acid cooking method.

[0065] [Saccharification Step] In the saccharification step, cellulose and hemicellulose contained in the pretreated herbaceous biomass obtained in the pretreatment step are used as substrates to carry out a saccharification reaction using enzymes.

[0066] The enzymes referred to here are mainly saccharifying enzymes, and those exemplified above as "saccharifying enzymes" can be used.

[0067] The saccharification temperature is preferably 45° C. or higher and 70° C. or lower, more preferably 45° C. or higher and 55° C. or lower, and particularly preferably 50° C. The saccharification time is preferably 12 hours or higher and 120 hours or lower, more preferably 24 hours or higher and 96 hours or lower, and even more preferably 24 hours or higher and 72 hours or lower.

[0068] The saccharification step can be carried out using any known saccharification apparatus without any particular limitations. Specific examples include agitation type, aeration agitation type, bubble column type, fluidized bed type, and packed bed type saccharification apparatus. Furthermore, the saccharification apparatus may be equipped with a temperature control device, such as a hot water circulating jacket, on the outside of the apparatus to maintain a constant temperature inside the apparatus.

[0069] [Solid-liquid separation step] In the solid-liquid separation step, the saccharification treatment product obtained in the saccharification step is subjected to solid-liquid separation to separate the saccharification solution, which is a liquid fraction, from a saccharification residue, which is a solid fraction, to obtain a saccharification residue. This saccharification residue contains water-insoluble lignin.

[0070] As a method for solid-liquid separation, any known method capable of separating solids and liquids can be used, and examples thereof include, but are not limited to, filtration using a filter, a vibrating sieve, or the like, centrifugation, and separation using a screw press.

[0071] The saccharified solution obtained in the solid-liquid separation step may be purified by removing impurities from the saccharified solution and sold as refined molasses, or may be used to produce useful components produced by microbial fermentation, the details of which will be described later.

[0072] [Extraction Step] In the extraction step, an organic solvent is added to the saccharification residue obtained in the solid-liquid separation step to extract organic solvent-soluble lignin.

[0073] The organic solvent preferably has affinity (hydrophilicity) for water. From the viewpoint of improving the extractability of organic solvent-soluble lignin, the solubility in water at 20°C is preferably 90 g / L or more, more preferably 100 g / L or more, and even more preferably 120 g / L or more.

[0074] Furthermore, from the viewpoint of improving the extraction rate of organic solvent-soluble lignin, the organic solvent preferably has an SP value of 8 or more and 23 or less, more preferably 8 or more and 16 or less, and even more preferably 9 or more and 15 or less.

[0075] Here, the term "SP value" refers to the solubility parameter (SP value), and is the value δ [(cal / cm ]] calculated based on the following Fedors formula using the Fedors method (see Reference 1: "Fedors RF, "A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids", Polymer Engineering and Science, Vol. 14, No. 2, pp. 147-154, 1974"). ３ ) １／２ ] and is calculated from the square root of the ratio of the sum of the vaporization energies (Δei) of the atoms or atomic groups in the chemical structure of the compound to the sum of the molar volumes (Δvi).

[0076] Fedors' formula: δ = (ΣΔei / ΣΔvi) １／２

[0077] Specific examples of such organic solvents include alcohols, nitriles, ethers, and ketones. These organic solvents may be used alone or in combination of two or more.

[0078] Examples of alcohols include methanol, ethanol, diethylene glycol, n-propanol, isopropanol, 2-butanol, isobutanol, and t-butyl alcohol.

[0079] An example of the nitriles is acetonitrile.

[0080] Examples of ethers include dioxane and tetrahydrofuran (THF).

[0081] Examples of ketones include acetone and methyl ethyl ketone.

[0082] Among these, methanol, ethanol, THF, or acetone is preferred as the organic solvent because it provides an excellent extraction rate of organic solvent-soluble lignin, and acetone is more preferred. These organic solvents have low solubility for biomass saccharification products such as glucose and xylose, and furthermore do not dissolve cellulose, hemicellulose, etc., so that lignin can be efficiently extracted.

[0083] In addition, a mixed solvent of an organic solvent and water can be used in the extraction step. The ratio of water to the organic solvent is preferably more than 0 / 100 and not more than 40 / 60 by mass, more preferably 10 / 90 or more and not more than 40 / 60, and even more preferably 20 / 80 or more and not more than 40 / 60. When the ratio is within the above range, the organic solvent-soluble lignin can be extracted more efficiently.

[0084] Furthermore, when a mixed solvent of an organic solvent and water is used, the water also contains the moisture contained in the saccharification residue. For example, by adding approximately 4 to 5 parts by mass of an organic solvent (preferably acetone or ethanol) having a concentration of 90% by mass to 1 part by mass of saccharification residue having a moisture content of 60% by mass, extraction can be performed under conditions where the ratio of water to organic solvent falls within the above range.

[0085] For example, the saccharification residue and the organic solvent are mixed and stirred to dissolve the organic solvent-soluble lignin in the organic solvent. The extraction step can be performed using a known extraction apparatus, such as a Rotocell extractor.

[0086] The amount of solvent (organic solvent or mixed solvent of organic solvent and water) added can be, by mass ratio, 2 to 40 times, 2 to 30 times, 2 to 20 times, or 5 to 15 times the dry mass of the saccharification residue, but is not limited thereto.

[0087] The extraction time (the time for mixing and stirring the saccharification residue with the organic solvent) can be, for example, but is not limited to, 30 minutes or more and 240 minutes or less. Furthermore, the temperature conditions during the extraction process until the organic solvent-soluble lignin is dissolved in the organic solvent and an extract is obtained can be mild, at or below the boiling point of the organic solvent used, for example, at room temperature (specifically, approximately 15°C to 35°C). Other conditions, such as the stirring speed, can be appropriately set depending on the amounts of saccharification residue and organic solvent mixed.

[0088] Next, the stirred solution is subjected to solid-liquid separation to obtain an extract containing organic solvent-soluble lignin. Examples of the solid-liquid separation method include the same methods as those exemplified in the "solid-liquid separation step" above. The organic solvent-soluble lignin contained in the extract is obtained as powdered organic solvent-soluble lignin by removing the organic solvent using a known method, such as a distillation column. In this case, the removed organic solvent is preferably recovered by cooling and concentrating using a condenser, and then reused.

[0089] [Other Steps] The manufacturing method of this embodiment may further include other steps in addition to the steps described above.

[0090] The production method of this embodiment may further include a fermentation step after the saccharification step. In the fermentation step, microorganisms are added to the saccharified solution obtained in the saccharification step, and a fermentation reaction is carried out while stirring. In the fermentation reaction, the microorganisms ingest monosaccharides and oligosaccharides, such as glucose and xylose, in the saccharified solution, thereby producing useful components different from organic solvent-soluble lignin.

[0091] The production method of this embodiment may further include a fermentation step after the saccharification step and before the solid-liquid separation step. In this case, in the fermentation step, microorganisms are added to the saccharification product (saccharified solution and saccharification residue) obtained in the saccharification step, and a fermentation reaction is carried out while stirring. In the solid-liquid separation step, the fermentation product obtained in the fermentation step is subjected to solid-liquid separation to obtain a fermentation residue. In the extraction step, an organic solvent is added to the fermentation residue to extract organic-solubilized lignin. The structural alteration of lignin (changes in chemical structure and degree of polycondensation) is hardly affected except in the above pretreatment step, and lignin is resistant to decomposition. Therefore, it is presumed that the physical properties and yield of the resulting organic-solubilized lignin are hardly affected even after the fermentation step and the purification step described below. Therefore, the fermentation residue separated from the fermentation product obtained after the fermentation step and the solid residue separated from the waste liquid obtained after the purification step can be used as the raw material for extraction of organic-solubilized lignin, similar to the above saccharification residue.

[0092] The microorganism used in the fermentation step is not particularly limited as long as it can produce a useful component different from the target organic solvent-soluble lignin. Specific examples include yeast and bacteria, and genetically modified microorganisms are also preferably used. A genetically modified microorganism is a microorganism that does not have an enzyme gene necessary for conversion into a useful component different from the target organic solvent-soluble lignin, such as alcohol, by introducing these genes into the microorganism using genetic engineering techniques, thereby enabling the production of a useful component different from the target organic solvent-soluble lignin, such as alcohol. An example of a genetically modified microorganism is genetically modified Escherichia coli capable of alcohol fermentation. Among these, yeast is preferred as the microorganism used in the production method of this embodiment.

[0093] The microorganisms may be used as a culture solution containing the microorganisms as is, or may be used appropriately in the form of a culture solution concentrated by centrifugation, a dried state, etc. The amount of the microorganisms to be used may be calculated based on the growth rate of the microorganisms, the size of the fermentation apparatus, the amount of saccharified solution to be used for fermentation, etc.

[0094] In particular, in the fermentation step, it is preferable to use yeast as the microorganism to ferment the saccharification product to produce alcohol such as ethanol as a useful component different from organic solvent-soluble lignin.

[0095] The fermentation step may be carried out appropriately based on conventional techniques, and for example, the fermentation temperature is preferably 25° C. or higher and 50° C. or lower, more preferably 28° C. or higher and 35° C. or lower, and particularly preferably 32° C. The fermentation time is preferably 24 hours or higher and 120 hours or lower, more preferably 24 hours or higher and 96 hours or lower, and even more preferably 24 hours or higher and 72 hours or lower.

[0096] The fermentation step can be carried out using any known fermentation apparatus without any particular limitations. Specific examples include, but are not limited to, fermentation apparatuses of agitation type, aeration agitation type, bubble column type, fluidized bed type, and packed bed type. Furthermore, the fermentation apparatus may be equipped with a temperature control device such as a hot water circulating jacket on the outside of the apparatus to maintain a constant temperature inside the apparatus.

[0097] The production method of this embodiment may further include a purification step after the fermentation step. In the purification step, useful components other than the organic solvent-soluble lignin are extracted from the fermentation product obtained in the fermentation step.

[0098] The production method of this embodiment may further include a purification step after the fermentation step and before the solid-liquid separation step. In this case, the purification step extracts useful components other than organic solvent-soluble lignin from the fermentation product obtained in the fermentation step. As a result, after the useful components other than organic solvent-soluble lignin are extracted, a waste liquid is discharged. The waste liquid contains water-soluble lignin and water-insoluble lignin. In the solid-liquid separation step, the waste liquid obtained in the purification step is subjected to solid-liquid separation to obtain a solid residue in the waste liquid. Furthermore, in the extraction step, an organic solvent is added to the solid residue to extract organic solvent-soluble lignin. As described above, the structural alteration of lignin (changes in chemical structure and degree of polycondensation) is hardly affected by processes other than the pretreatment process, and lignin is resistant to decomposition. Therefore, it is presumed that the physical properties and yield of the resulting organic solvent-soluble lignin are hardly affected by the purification step. Therefore, the solid residue separated from the waste liquid obtained after the purification step can be used as a raw material for extraction of organic solvent-soluble lignin, similar to the saccharification residue.

[0099] The useful components other than organic solvent-soluble lignin refer to compounds produced by microorganisms such as yeast ingesting monosaccharides and oligosaccharides obtained by decomposing herbaceous biomass. Specific examples of useful components include alcohols such as ethanol, butanol, 1,3-propanediol, 1,4-butanediol, and glycerol; organic acids such as pyruvic acid, succinic acid, malic acid, itaconic acid, citric acid, and lactic acid; nucleosides such as inosinic acid and guanosine; nucleotides such as inosinic acid and guanylic acid; and diamine compounds such as cadaverine. When the compound obtained by fermentation is a monomer such as lactic acid, it may be converted into a polymer by polymerization. Among these, ethanol is a preferred useful component produced by the fermentation process described above.

[0100] Examples of purification methods include distilling the fermentation liquid (distillation) when the herbaceous biomass compound is an alcohol. Furthermore, examples of purification methods include ion exchange and adsorption / removal of foreign matter using activated carbon when the herbaceous biomass compound is an amino acid. Among these, it is preferred to use yeast as the microorganism in the fermentation step to ferment the saccharification product to produce alcohol such as ethanol as a useful component, and then, in the purification step, to extract the alcohol such as ethanol from the fermentation product by distillation.

[0101] <Uses of Organic Solvent-Soluble Lignin> The organic solvent-soluble lignin obtained by the production method of this embodiment has phenolic hydroxyl groups, and therefore can be subjected to various modifications. For example, an epoxy resin can be obtained by addition reaction of organic solvent-soluble lignin with an epihalogenohydrin (e.g., epichlorohydrin, etc.). Furthermore, a urethane resin can be obtained by reacting organic solvent-soluble lignin with an isocyanate compound. Furthermore, a phenolic resin can be obtained by curing organic solvent-soluble lignin using hexamine as a curing agent. Because organic solvent-soluble lignin contains an aromatic skeleton, it can be used as a raw material with excellent mechanical properties such as fire resistance, heat resistance, and hardness. These various resins can be used as electrical substrate materials, heat-resistant plastic materials, etc. Furthermore, because organic solvent-soluble lignin has excellent dispersibility, it can also be used as a surfactant by modifying it with a long-chain hydrocarbon group, etc.

[0102] Generally, the specifications required for raw materials for chemical synthesis are: (1) little steric hindrance (having many linear chain structures); (2) relatively low molecular weight; and (3) many hydroxyl groups. As described above, the organic solvent-soluble lignin obtained by the production method of this embodiment has a β-O-4 bond content, weight average molecular weight and molecular weight distribution, and a hydroxyl group content within predetermined ranges, making it possible to provide lignin that meets the above specifications.

[0103] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0104] [Example 1] (Condition study of dilute sulfuric acid cooking method) Using napier grass, which is herbaceous biomass, dilute sulfuric acid cooking was carried out under the conditions shown in Table 1. Specifically, the dilute sulfuric acid cooking treatment was carried out by adding dilute sulfuric acid to napier grass so as to achieve the following pH conditions, and then using a steam-supply type pressurized pretreatment device.

[0105]

[0106] In Table 1, the CSI (Combined Severity Index) is a value calculated using the following formula (I) with the temperature, pH, and treatment time, which are parameters of the conditions for the dilute sulfuric acid cooking method, as variables. The larger the CSI value, the higher the decomposition strength of lignin, and the smaller the CSI value, the lower the decomposition strength of lignin.

[0107]

[0108] (In formula (I), X is time, Y is temperature, and Z is pH.)

[0109] The napier grass pretreated under each of the above conditions was subjected to saccharification treatment by adding saccharifying enzymes (cellulase and hemicellulase) to obtain a saccharified product, which was then filtered to obtain a saccharification residue.

[0110] (Extraction of Organic Solvent-Soluble Lignin) Next, the saccharification residue obtained in the above process was dried to obtain a dried saccharification residue. This dried saccharification residue was used to extract organic solvent-soluble lignin. First, 1 g of the dried saccharification residue was added to 40 mL (31.1 g) of acetone and stirred at room temperature (20°C) for 30 minutes, followed by solid-liquid separation using a centrifuge to obtain an extract and an extraction residue. The extract and the extraction residue were each dried to obtain a dried extract and a dried extraction residue.

[0111] (Physical Properties of Organic Solvent-Soluble Lignin) Various physical properties of the organic solvent-soluble lignin contained in the dried extract were examined.

[0112] (1) β-O-4 Bond Content The β-O-4 bond content in organic solvent-soluble lignin was measured using the thioacidolysis method. In the thioacidolysis method, β-O-4 bonds are cleaved to generate decomposition products containing thioacidolysis monomers consisting of syringyl and guaiacyl. The decomposition products are analyzed to quantify the β-O-4 bonds in the lignin. That is, the thioacidolysis monomer content is quantified as the β-O-4 bond content. Specifically, 5 mg of each sample was first added to a dioxane / ethanethiol (9:1) solution and heated at 100°C for 4 hours. The heated solution was then neutralized with sodium bicarbonate, hydrochloric acid was added to precipitate sodium chloride, and the solution was filtered to remove sodium. Methylene chloride was added to the filtrate, and the monomers were extracted into the methylene chloride phase. The resulting extract was concentrated. A pyridine solution of N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) as a silylating agent was added to the concentrated solution, and the mixture was stirred at room temperature for 30 to 60 minutes to prepare a derivatized sample. The derivatized sample was measured by gas chromatography-mass spectrometry (GC-MS) under the measurement conditions shown below, and the content of thioacidolysis monomers consisting of syringyl (S) and guaiacyl (G) was calculated. The results are shown in Figure 1. In Figure 1, "Thioacidolysis S+G" refers to the content (μmol / g) of thioacidolysis monomers consisting of syringyl (S) and guaiacyl (G).

[0113] (Measurement conditions) GC / MS device: Shimadzu GCMS-QP2010SE Column: DB-5MS column (30 m × 0.25 mm, id, 0.25 μm film thickness) Column temperature: 170°C for 3 min, heated to 280°C at 2°C / min, and held for 30 min Column flow rate: 1.0 mL / min Injection port temperature: 250°C Injection method: Split method Ion source temperature: 200°C Interface temperature: 250°C Ionization method: EI Sample amount: 1.0 μL

[0114] As shown in Figure 1, an increase in CSI tends to decrease the thioacidolysis monomer content, i.e., the content of β-O-4 bonds. This is presumably due to the fact that the increased intensity of the dilute sulfuric acid cooking process decomposes the linear structure and increases the number of side chains. Furthermore, when the CSI is in the range of 1.27 to 2.95, the thioacidolysis monomer content of organic solvent-soluble lignin, as quantified by the thioacidolysis method as the content of β-O-4 bonds, was 95 μmol / g to 248 μmol / g. These results suggest that controlling the CSI is effective in obtaining organic solvent-soluble lignin with a specific range of thioacidolysis monomer content, i.e., the content of β-O-4 bonds.

[0115] (2) Weight-average molecular weight and molecular weight distribution As samples, organic solvent-soluble lignin obtained from Napier grass pretreated under conditions of CSI of 1.27, 1.87, 2.36, 2.66, and 2.95 was used. The weight-average molecular weight Mw and number-average molecular weight Mn of the organic solvent-soluble lignin were measured by GPC under the measurement conditions shown below. The molecular weight distribution Mw / Mn was obtained by dividing the weight-average molecular weight Mw by the obtained number-average molecular weight Mn.

[0116] (Measurement conditions) Apparatus: Shimadzu Prominence system Column: Tosoh Corporation, TSKgel Supermultipore HZ-M 4.6 mm x 150 mm, triple column Carrier: Tetrahydrofuran (THF, stabilizer-free) Detection method: UV 280 nm, absorbance Sample concentration: 4 mg / mL Flow rate: 0.35 mL / min Column temperature: 40°C

[0117] Figure 2A shows chromatograms obtained by gel permeation chromatography of organic solvent-soluble lignin obtained from napier grass pretreated under conditions of CSI values ​​of 1.27, 1.87, 2.36, 2.66, and 2.95. The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) for each peak in each chromatogram shown in Figure 2A are shown in Table 2 below.

[0118]

[0119] FIG. 2B is a graph showing the measured values ​​of the weight-average molecular weight of the peak with the largest weight-average molecular weight (peak 1 in Table 2 above) among the peaks in the chromatogram shown in FIG. 2A.

[0120] 2A and 2B, as the CSI increases, the weight-average molecular weight increases, the width of the molecular weight distribution increases, and the proportion of organic solvent-soluble lignin with a low molecular weight of about 200 or less decreases relative to the total organic solvent-soluble lignin. Furthermore, when the CSI is in the range of 1.27 to 2.95, the measured weight-average molecular weight of the peak with the largest weight-average molecular weight Mw among the peaks in the chromatogram shown in FIG. 2A is 2453 to 4151, and the molecular weight distribution Mw / Mn is 1.32 to 1.86. These results suggest that controlling the CSI is effective in obtaining organic solvent-soluble lignin with a weight-average molecular weight and molecular weight distribution within a specific range.

[0121] (3) Hydroxyl group content As samples, organic solvent-soluble lignin obtained from napier grass pretreated under conditions of CSI of 1.27, 1.57, 2.36, and 2.95 was used. The hydroxyl group content in the organic solvent-soluble lignin was measured by phosphorylating the hydroxyl groups and then analyzing them with phosphorus-31 nuclear magnetic resonance spectroscopy ( ３１ The content of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane was quantified by P-NMR spectroscopy. Specifically, 25 mg of organic solvent-soluble lignin was mixed with 115 mg (100 μL: excess amount) of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane, 0.5 mg of Tris(2,4-pentanedionato)-chromium(III), and 1.14 mg of N-hydroxy-1,8-naphthalimide as an internal standard, and the mixture was reacted at 25° C. (room temperature) for 180 minutes. The resulting reaction solution was used as a sample. ３１ P-NMR was performed. ３１ The P-NMR measurement conditions are as follows: ３１Of the hydroxyl groups quantified by P-NMR, the content of phenolic hydroxyl groups (including hydroxyl groups bonded to the benzene rings of syringyl and guaiacyl) and alcoholic hydroxyl groups, as well as the total content of these hydroxyl groups, were calculated. The results are shown in Table 3 and Figure 3.

[0122] (Measurement conditions) Measurement device: JEOL JNM-LA400MK Observation frequency: 400 MHz Number of accumulations: 4096 Measurement temperature: 16°C (room temperature) Solvent used: Pyridine-d-chloroform mixture (mass ratio 8:5)

[0123]

[0124] As can be seen from Figure 3, as the CSI increases, the total content of phenolic hydroxyl groups (including hydroxyl groups bonded to the benzene rings of syringyl and guaiacyl) and alcoholic hydroxyl groups tends to decrease. This is presumably due to the fact that the lignin degeneration progresses as the treatment intensity using the dilute sulfuric acid cooking method increases, resulting in a decrease in the hydroxyl group content. In addition, when the CSI is in the range of 1.27 to 2.95, the hydroxyl group content is ３１ The content of phenolic hydroxyl groups (including hydroxyl groups bonded to the benzene rings of syringyl and guaiacyl) in the organic solvent-soluble lignin, as determined by P-NMR, was 7.03 mmol / g or more and 31.24 mmol / g or less. The content of alcoholic hydroxyl groups was 6.04 mmol / g or more and 195.7 mmol / g or less. These results suggest that controlling CSI is effective in obtaining organic solvent-soluble lignin with a specific range of hydroxyl group content, particularly the total content of phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0125] According to the production method of this embodiment, organic solvent-soluble lignin having specific properties can be produced.

Claims

DEPCT651. A method for the production of organic solvent-soluble lignin, which consists of: a pretreatment step involving the pretreatment of herbaceous biomass using dilute sulfuric acid digestion; a saccharification step involving the saccharification of the pretreatment-converted herbaceous biomass obtained in the enzymatic pretreatment step; a solid-liquid separation step involving the solid-liquid separation of the saccharification product obtained in the saccharification step to obtain the saccharification residue; and an extraction step involving the addition of organic solvents to the saccharification residue to extract organic solvent-soluble lignin, where in the pretreatment step, the intensity of the dilute sulfuric acid digestion process is controlled in such a way that each value of the number of beta-O-4 bonds, average molecular weight by weight, molecular weight distribution, and the number of hydroxyl groups of the organic solvent-soluble lignin to be obtained are within a predetermined range, and in the pretreatment step,1. The treatment intensity by the dilute sulfuric acid digestion method is 1.0 or greater and 3.0 or less in terms of CSI, which is expressed by equation (I), CSI=logXxexp{(Y-100) / 14.75}-Z(I) (in equation (I), X represents time, Y represents temperature, and Z represents pH).

2. The method for the production of organic solvent-soluble lignin according to claim 1, where in the pretreatment step, the treatment intensity by the dilute sulfuric acid digestion method is controlled in such a way that the number of monomers from thioacidolysis of organic solvent-soluble lignin quantified by the thioacidolysis method as the number of bonds (beta-O-4) will be in the range of 95 µmol / g or greater and 248 µmol / g or less.

3. The method for the production of organic solvent-soluble lignin according to claim 1, where in the pretreatment step,The intensity of the digestion by the dilute sulfuric acid digestion method is controlled in such a way that the weight-average molecular weight of the lignin soluble in organic solvent quantified by the gel permeation chromatography method is in the range of 2400 or more and 4200 or less.

4. The method for the production of lignin soluble in organic solvents according to claim 1, where in the pretreatment step, the intensity of the digestion by the dilute sulfuric acid digestion method is controlled in such a way that the distribution of the molecular weight of the lignin soluble in organic solvent quantified by the gel permeation chromatography method is in the range of 1.0 or more and 2.0 or less.

5. The method for the production of lignin soluble in organic solvents according to claim 1, where in the pretreatment step,The intensity of the digestion by the dilute sulfuric acid method was controlled such that the number of phenolic hydroxyl groups of organic solvent-soluble lignin, quantified by hydroxyl phosphorylation using phosphorus-31 nuclear magnetic resonance spectroscopy, was in the range of 7 mmol / g or more and 32 mmol / g or less, and the number of alcoholic hydroxyl groups was in the range of 6 mmol / g or more and 196 mmol / g or less, as the number of hydroxyl groups was 6. Methods for the production of organic solvent-soluble lignin according to one of claims 1 through 5, in which, during the conditioning step, CSI is controlled to be close to 1.0 to increase the number of beta-O-4 bonds of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to decrease the number of beta-O-4 bonds of organic solvent-soluble lignin.CSI is controlled to be close to 1.0 to reduce the weight-average molecular weight and molecular weight distribution of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to increase the weight-average molecular weight and molecular weight distribution of organic solvent-soluble lignin.

8. Methods for the production of organic solvent-soluble lignin according to one of the claims 1 through 5, where in the conditioning step, CSI is controlled to be close to 1.0 to increase the number of hydroxyl groups of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to decrease the number of hydroxyl groups of organic solvent-soluble lignin. ----------------------------------------------------------- 1. Methods for the production of organic solvent-soluble lignin,This process consists of: a preliminary conditioning step where the pre-conditioning of herbaceous biomass is performed using dilute sulfuric acid digestion; a saccharification step where the pre-conditioning of the herbaceous biomass obtained in the enzymatic preliminary conditioning step is performed; a solid-liquid separation step where the solid-liquid separation of the saccharification product obtained in the saccharification step is performed to obtain the saccharification residue; and an extraction step where organic solvents are added to the saccharification residue to extract organic solvent-soluble lignin. In the preliminary conditioning step, the conditioning strength by dilute sulfuric acid digestion is controlled in such a way that each value of the number of beta-O-4 bonds, average molecular weight, molecular weight distribution, and the number of hydroxyl groups of the organic solvent-soluble lignin to be obtained are within a predetermined range.

1. The strength of conditioning by the dilute sulfuric acid digestion method is 1.0 or greater and 3.0 or less in terms of CSI, which is expressed by Equation (I), CSI = logX x exp {(Y-100) / 14.75} - Z (I) (in Equation (I), X represents time, Y represents temperature, and Z represents pH).

2. The method for the production of organic solvent-soluble lignin according to claim 1, where in the preliminary conditioning step, the strength of conditioning by the dilute sulfuric acid digestion method is controlled in such a way that the number of monomers from thioacidolysis of organic solvent-soluble lignin quantified by the thioacidolysis method as the number of beta-O-4 bonds is in the range of 95 µmol / g or greater and 248 µmol / g or less.

3. The method for the production of organic solvent-soluble lignin according to claim 1, where in the preliminary conditioning step,The conditioning strength by the dilute sulfuric acid digestion method is controlled in such a way that the average molecular weight by weight of lignin soluble in organic solvents, quantified by the gel permeation chromatography method, is in the range of 2400 or more and 4200 or less.

4. The method for the production of lignin soluble in organic solvents according to claim 1, where in the preliminary conditioning step, the conditioning strength by the dilute sulfuric acid digestion method is controlled in such a way that the distribution of molecular weights of lignin soluble in organic solvents, quantified by the gel permeation chromatography method, is in the range of 1.0 or more and 2.0 or less.

5. The method for the production of lignin soluble in organic solvents according to claim 1, where in the preliminary conditioning step,The strength of conditioning by dilute sulfuric acid digestion was controlled such that the number of tenelic hydroxyl groups of organic solvent-soluble lignin, quantified by hydroxyl phosphorylation using phosphorus-31 nuclear magnetic resonance spectroscopy, was in the range of 7 mmol / g or more and 32 mmol / g or less, and the number of alcoholic hydroxyl groups was in the range of 6 mmol / g or more and 196 mmol / g or less, as the number of hydroxyl groups 6. Methods for the production of organic solvent-soluble lignin according to one of Claims 1 through 5, in which, in the initial conditioning step, CSI is controlled to be close to 1.0 to increase the number of beta-O-4 bonds of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to decrease the number of beta-O-4 bonds of organic solvent-soluble lignin.

7. Methods for the production of organic solvent-soluble lignin according to one of Claims 1 through 5, in which, in the initial conditioning step,CSI is controlled to be close to 1.0 to reduce the average weight-of-weight (AWM) and the MWM distribution of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to increase the average weight-of-weight (AWM) and the MWM distribution of organic solvent-soluble lignin.

8. Methods for the production of organic solvent-soluble lignin according to one of the claims 1 through 5, where in the pretreatment step, CSI is controlled to be close to 1.0 to increase the number of hydroxyl groups of organic solvent-soluble lignin, and CSI is controlled to be close to 3.0 to decrease the number of hydroxyl groups of organic solvent-soluble lignin;