JP5693286B2 - Saccharification method of woody biomass - Google Patents

Description

  The present invention relates to a saccharification method for producing sugar at low cost and efficiency using cellulose or hemicellulose in woody biomass as a raw material, and a method for producing ethanol from sugar derived from the cellulose or hemicellulose.

  Bioethanol has been attracting attention as a carbon-neutral liquid fuel that does not depend on fossil resources, and production technologies targeting various biomass have been demonstrated to date. Among biomass, cellulosic biomass is attracting attention as an energy resource that does not compete with food. It is difficult to say that cellulosic biomass has a highly practical production technique that is very difficult to convert to ethanol as compared to carbohydrate and starchy biomass.

  In particular, woody biomass has high crystallization of cellulose, and lignin consisting of more complicated chemical bonds exists. Therefore, in the case of using woody biomass, a pretreatment method using concentrated sulfuric acid or dilute sulfuric acid treated at high temperature or high pressure has been conventionally studied. However, in these methods, overreaction (overdecomposition) of monosaccharides produced by hydrolysis of cellulose proceeds, the yield of monosaccharides is low, fermentation inhibitors derived from sugars and lignin are produced, equipment There is a general problem of acid corrosion. Furthermore, since a lot of energy is required for production, there is a problem from the viewpoint of life cycle assessment (LCA).

  In recent years, in order to overcome these problems, an enzymatic saccharification method using an enzyme (cellulase) that can be produced at room temperature and normal pressure has attracted attention. Enzymatic saccharification is not only the overreaction of monosaccharides and the production of fermentation inhibitors from sugars and lignin, as seen in concentrated sulfuric acid and dilute sulfuric acid methods, but it is also a reaction near room temperature, and it is highly expected from the viewpoint of LCA. Has been.

  However, it is very difficult to saccharify woody biomass sufficiently efficiently even by a saccharification method using an enzyme. In particular, conifers such as cedar make the enzymatic saccharification more difficult because the density of lignin is higher than that of broad-leaved trees. In addition to the physical properties of the wood itself, the fact that some of the added enzyme (cellulase) is adsorbed on lignin and cannot be attacked to cellulose is also a major reason for the difficulty of enzymatic saccharification of wood. Therefore, in the enzymatic saccharification of woody biomass, a pretreatment method that improves the form of cellulose or lignin in advance and promotes enzymatic saccharification is essential.

  As a typical pretreatment method in the enzymatic saccharification of woody biomass, there can be mentioned a method using hydrothermal treatment and wet mechanochemical (Patent Document 1: JP 2008-104404 A). This method is a pretreatment method in which a finely pulverized wood raw material is softened by high-temperature and high-pressure hydrothermal treatment, and then finely divided using a wet disc mill to improve the enzyme saccharification rate in the subsequent stage. This technology can obtain a high saccharification rate by breaking down the tissue into fine particles of the wood down to the nano level. However, there are problems such as administration energy in hydrothermal treatment and ultrafine grinding, and wear of the ultrafine grinding machine. In particular, in the case of woody waste containing foreign matters such as metal and sand, wear of the pulverizer is promoted, and it is necessary to take appropriate measures for removing foreign matters.

  Moreover, as a pretreatment method in the enzymatic saccharification of woody biomass, there is an alkali cooking method used in pulp production. This is a mixture of alkaline chemicals such as caustic soda to the biomass 5-40% per dry weight, quinone-based cooking aid etc. about 10% per dry weight, and heated to 100 ° C-200 ° C, preferably 140 ° C or higher, It is a method of processing with a pressure cooker for a predetermined time. By this method, lignin in wood can be completely dissolved. The solid content delignified by this alkali digestion is washed with water, and then enzymatically saccharified to monosaccharides such as glucose and xylose by cellulase.

  Patent Document 2: Japanese Patent Application Laid-Open No. 2008-92910 is cited as a prior document of this pretreatment method. In this document, the results of ethanol production using cedar wood are shown. An aqueous solution containing 20% caustic soda per cedar weight is mixed and subjected to alkaline digestion at 170 ° C for 240 minutes (total time 330 minutes after temperature rise). After that, as a result of enzymatic saccharification / fermentation of 210 g (cellulose content 43 g) of the recovered solid content, an ethanol yield of 84% was obtained. However, according to this pretreatment method, a dedicated pressure cooker is required for the alkali digestion reaction, and the reaction time is as long as 60 to 500 minutes, resulting in excessive facilities. In addition, this prior art is based on batch processing, and in order to perform continuous production, there are problems such as a method for supplying wood or a caustic soda solution to the pressure cooker, a pressure cooker temperature, and a pressure control technique.

  On the other hand, as a pretreatment method in enzymatic saccharification of soft cellulose such as rice straw instead of woody biomass, the cut or pulverized soft cellulose is mixed with an aqueous caustic soda solution at room temperature, and the solid content is neutralized. A technique for saccharification is known. For soft celluloses such as rice straw, a high enzymatic saccharification rate can be obtained by this pretreatment method (19th Annual Meeting of the Japan Institute of Energy "Development of bioethanol production process from rice straw"). There was no noticeable effect, and it was necessary to add a very high concentration of caustic soda (2009 Eco-Fuel Practical Use Regional System Demonstration Project Results Report).

JP 2008-104404 A JP 2008-92910 A

  The present invention provides a saccharification method for woody biomass and a method for producing ethanol using woody biomass that can achieve high-yield enzymatic saccharification for woody biomass such as construction waste wood that is difficult to saccharify as described above. The purpose is to do.

  As a result of intensive studies to achieve the above object, the present inventor has shown that the saccharification efficiency in the subsequent enzyme treatment is greatly improved by adding shearing force to the woody biomass in an alkaline solution. As a result, the present invention has been completed.

That is, the present invention includes the following.
(1) A method for saccharification of woody biomass, comprising a step of applying shearing force to woody biomass in an alkaline solution, and a step of saccharifying the solid content with an enzyme thereafter.

  (2) The saccharification method according to (1), wherein a multi-screw extruder is used in the step of applying the shearing force.

  (3) The multi-screw extruder has a plurality of temperature control blocks arranged in series in the axial direction, and sets the processing temperature of the woody biomass flowing in the axial direction for each block (2 ) Saccharification method of the woody biomass described.

  (4) A method for producing ethanol using woody biomass, wherein the sugar component obtained by the saccharification method according to any one of (1) to (3) above is converted into ethanol by an enzyme.

  In the above (1) saccharification method of woody biomass and (4) ethanol production method using woody biomass, construction waste wood is preferably used as the woody biomass. In the above (1) saccharification method of woody biomass and (4) ethanol production method using woody biomass, the woody biomass may use chips that have been crushed to about 2 to 15 mm in advance. preferable.

  Further, in (1) the saccharification method of woody biomass and (4) the method of producing ethanol using woody biomass, after applying shear force to the woody biomass in an alkaline solution, It is preferable that the solid content obtained by the liquid separation treatment is washed, and the washed solid content is subjected to saccharification treatment or ethanol fermentation treatment. Thereby, the inhibitory substance in a saccharification process or ethanol fermentation process can be removed effectively, and saccharification efficiency and fermentation efficiency can be improved more. In addition, when a shearing force is added to the woody biomass in an alkaline solution, the woody biomass becomes a paste. The obtained woody biomass paste may be washed with water or mixed with an acid so as to have a desired pH.

  In the above (1) saccharification method of woody biomass and (4) ethanol production method using woody biomass, saccharification treatment refers to a woody system using an enzyme such as cellulase or a microorganism that produces the enzyme. It means a process of converting polysaccharide components (cellulose and hemicellulose) contained in biomass into monosaccharides. In addition, in the method for producing ethanol using the woody biomass of (4) above, the ethanol fermentation treatment refers to a microorganism capable of synthesizing ethanol using a sugar component such as glucose as a substrate or a sugar component such as glucose as a substrate. It means a process of synthesizing ethanol from a saccharide component obtained by a saccharification process using an enzyme group involved in the ethanol synthesis pathway.

  The present invention provides an efficient method for saccharification of woody biomass and a method for producing ethanol. According to the present saccharification method, not only can the saccharification yields of hemicellulose and cellulose contained in the woody biomass be greatly improved, but also the processing time is short, so that processing with energy saving can be performed. Furthermore, the present invention provides a method for producing ethanol. In this method for producing ethanol, woody biomass can be efficiently converted into energy, which is effective for resource reuse.

It is a figure which shows the basic flow of the saccharification method based on this invention using a twin-screw extruder. It is a figure which shows the basic flow regarding the other form of the saccharification method which concerns on this invention. It is a schematic block diagram of the twin-screw extruder used for the Example.

Hereinafter, the present invention will be described in detail.
The saccharification method of woody biomass according to the present invention (hereinafter also referred to as “the saccharification method”) is highly efficient in the subsequent enzymatic saccharification treatment by pretreatment of applying shearing force to the woody biomass in an alkaline solution. Can produce sugar. Here, the means for applying the shearing force to the woody biomass in the alkaline solution is not particularly limited, and examples thereof include a multi-screw extruder. A multi-screw extruder is a device that generates a shearing force inside a cylinder (between a charging port and a discharge port (extrusion port)) by rotating a plurality of screws in the cylinder. In addition, as a multi-screw extruder, although the twin-screw extruder which has two screws is typically known, the apparatus provided with three or more screws may be sufficient. The multi-screw extruder may be a type in which the axes of a plurality of screws are parallel, or may be a type in which a plurality of screw shafts of a conical type are obliquely crossed. Furthermore, as a multi-screw extruder, the flight in a plurality of screws may be either a meshing type or a non-meshing type, and the screw rotation direction may be either the same direction or a different direction.

  As an example, FIG. 1 shows a basic flow of the present saccharification method using a twin screw extruder. In this saccharification method, first, woody biomass as a raw material is prepared. In the present saccharification method, the woody biomass used as a raw material is not particularly limited, but wood chips roughly pulverized to about 2 to 15 mm can be used, for example. Here, the particle size means an average particle size. The coarse pulverization of the woody biomass is not particularly limited, and can be performed using, for example, a refiner or a wood pulverizer. After coarse pulverization, it is preferable to remove metal such as nails using a magnetic separator or remove sand due to a difference in specific gravity.

  The woody biomass used as a raw material is not particularly limited as long as it is a wood resource.For example, construction waste wood, waste packing materials, logging materials, sawdust, thinned wood, wood chips, rice straw, bark, forest land residual materials, Examples include unused trees and backboards. The woody biomass may be composed of one kind of woody resource, or may be composed of a plurality of kinds of woody resources. Further, the woody biomass may contain some impurities such as nails and preservative sugars in addition to the wood resources.

  An aqueous solution based on any alkali can be used as the aqueous alkali solution mixed with the woody biomass. For example, sodium hydroxide (caustic soda), slaked lime, quick lime (calcium hydroxide aqueous solution), and the like can be used. Moreover, the aqueous alkali solution used can be pH 9.5 to 13.5, preferably pH 10 to 13, more preferably pH 11 to 12.5. In addition, when using a twin-screw extruder, it is desirable to use caustic soda or potassium hydroxide. When caustic soda or potassium hydroxide is used as the alkaline solution, scale generation inside the twin screw extruder can be suppressed. The addition amount of the alkaline solution is, for example, 2 to 30% by weight ratio per dry wood weight, and desirably 5 to 20%. The mixing ratio of the aqueous solution containing a predetermined amount of the alkali agent and the dry wood is preferably 5-30 wood weight with respect to 100 solution volume.

  Further, the woody biomass and the alkaline solution may be independently fed into a twin screw extruder, or may be fed into a twin screw extruder after being mixed in advance.

  The twin screw extruder shown in FIG. 1 has a structure in which two screws rotate in the same direction. Each screw is equipped with a bit, and the wood-based biomass (wood chips) that is input is continuously sheared in an alkaline solution while being extruded in the axial direction. Furthermore, the kneading of the aqueous alkali solution and the woody biomass is repeated by using the twin screw extruder.

  As shown in FIG. 1, it is preferable to use a twin screw extruder in which heater blocks (temperature control blocks) that can be heated or cooled in the axial direction are arranged in series. That is, it is preferable that the step of applying a shearing force to the woody biomass in an alkaline solution is performed at a predetermined temperature. In particular, the twin-screw extruder shown in FIG. 1 can set the temperature for each block. For example, the temperature at the inlet and outlet can be set to 20 ° C., and the temperature at the center can be set to 100 to 200 ° C. In addition, the processing time in a twin-screw extruder is 5 to 60 minutes, desirably about 10 to 20 minutes. In the pretreatment by alkali cooking shown in the prior art, the reaction takes 60 to 500 minutes. Therefore, this method can greatly reduce the processing time required for the preprocessing.

  Furthermore, when applying a shearing force in an alkaline solution to woody biomass, when using a multi-screw extruder, it is possible to continuously process woody biomass by securing a predetermined residence time inside. It becomes. On the other hand, in the pretreatment by alkali digestion shown in the prior art, wood and alkali are mixed in a pressure cooker and the treatment is performed at a predetermined temperature and pressure. As a result, particularly in the present invention, when a multi-screw extruder is used, the efficiency of the woody biomass pretreatment process can be greatly improved.

  As described above, the wood biomass and the alkaline aqueous solution are repeatedly kneaded by the treatment of applying shear force to the wood biomass in the alkaline solution, and the wood biomass can be pasted. Thereafter, as shown in FIG. 1, the pasted woody biomass may be washed with water as necessary, or may be neutralized with an acid aqueous solution to the optimum pH of cellulase. Next, after solid-liquid separation is performed and a wood paste (woody biomass) that is a solid content is recovered, cellulase and / or cellulase-producing bacteria are added to saccharify. Details of the solid-liquid separation step and the saccharification treatment step will be described later.

  In this saccharification method, as shown in FIG. 2, after pulverizing the woody biomass, a shearing force may be applied in an alkaline solution. The finely pulverized woody biomass has a particle size of, for example, 1 mm or less, desirably 0.5 mm or less. Examples of the fine pulverization treatment include a treatment of adding mechanical action such as compression force, friction force, cutting force, shear force, and impact force to the woody biomass chip that has been charged. More specifically, examples of the fine pulverizer include a twist mill, a sawdust making machine, a cut mill, and a hammer mill. A twist mill is a device that has a mechanism that compresses and kneads coarsely pulverized woody biomass chips with a single screw and crushes them with a disk at the tip, and applies compressive and frictional forces to the woody biomass chips. It can be finely pulverized by loading. The sawdust making machine is an apparatus having a mechanism for installing woody biomass on a stage and cutting wood with a cylindrical rotating body with a blade edge. The cut mill is a device having a mechanism for crushing woody biomass chips between a triangular bladed rotating body and a fixed blade attached to an outer cylinder, and applies a shearing force to the woody biomass chips. Can be finely pulverized. A hammer mill is a device that has a mechanism to finely pulverize woody biomass chips with a swing hammer that rotates inside an outer cylinder with an impact plate, and applies impact force, friction force and shearing force to the woody biomass chips. It can be pulverized by adding.

  In the saccharification method shown in FIG. 2, first, foreign materials such as metal and sand are removed from construction waste wood that has been secondarily pulverized to about 15 mm or less by sieving, magnetic separation, wind separation or the like. Thereafter, the construction waste wood crushed by the pulverizer is collected and kneaded with an alkaline aqueous solution by a twin screw extruder. The obtained wood paste is washed with water with a horizontal belt or the like and neutralized with an aqueous acid solution, and then the recovered solid content is subjected to enzymatic saccharification with cellulase and ethanol fermentation with fermenting microorganisms such as yeast. According to this production flow example, ethanol can be continuously produced from construction waste wood, and not only the production facility becomes compact compared to batch processing, but also an increase in production amount can be expected.

  Moreover, in the saccharification method shown to FIG. 1 and 2, the oxidizing agent which produces | generates active oxygen may be contained in the alkaline solution which mixes wood type biomass. That is, the woody biomass is preferably treated with an oxidizing agent before the saccharification treatment. Although it does not specifically limit as an oxidizing agent, For example, hydrogen peroxide, persulfate, percarbonate, peracetate, ozone, sodium peroxide, etc. can be used. When hydrogen peroxide is used as the oxidizing agent, the amount is preferably 1 to 10% per dry wood weight, and can be set according to the target wood species (coniferous, hardwood, pruned). it can. Further, the treatment with the oxidizing agent may be a method of mixing in an alkaline solution as described above, or spraying woody biomass after applying a shearing force in the alkaline solution.

Following the solid-liquid separation step , the liquid and solid components are separated. Specifically, as shown in FIG. 2, the pasty woody biomass extruded from the twin-screw extruder is washed with water simultaneously with solid-liquid separation by a horizontal belt or the like. The woody biomass washed with water then moves to a neutralization step for neutralizing the contained alkali, and is adjusted to a predetermined pH with an acid such as sulfuric acid. Note that the solid-liquid separation treatment is not limited to the one using the apparatus shown in FIG. 2, and can be performed by any method known in the art as described above. In addition, the liquid component recovered by the solid-liquid separation process may be subjected to wastewater treatment or may be reused.

Saccharification treatment step In this step, cellulose and hemicellulose in the woody biomass are saccharified to monosaccharides such as glucose, mannose, galactose, xylose, and arabinose by subjecting the obtained woody biomass to cellulase enzyme treatment. The cellulase used is not particularly limited as long as it can efficiently saccharify cellulose. For example, the cellulase may be derived from plants or animals, and may be chemically modified or produced by genetic recombination. In addition, although the temperature, time, and quantity which make cellulase react depend on the kind of cellulase, those skilled in the art can select suitably according to the kind of cellulase to be used.

  Alternatively, by culturing cellulase-producing bacteria using treated woody biomass as a raw material, cellulose and hemicellulose can be decomposed to monosaccharides by cellulase to obtain a secondary sugar solution. Such cellulase producing bacteria are known in the art, e.g. Aspergillus niger, A. foetidus, Alternaria alternata, Chaetomium thermophile, C. globosus, Fusarium solani, Irpex lacteus, Neurospora crassa, Cellulomonas fimi, C. uda, Erwinia chrysanthemi, Pseudomonas fluorescence, Streptmyces flavogriseus, etc. are mentioned, for example, "Cellulose resources-Technological development for advanced use and its basics", Tetsuo Koshijima, Japan Society for Publishing Press, 1991.

  In addition to the cellulase enzyme treatment as described above, it is also possible to produce ethanol by simultaneous fermentation of cellulase-producing bacteria and ethanol-fermenting bacteria using the treated woody biomass as a raw material.

  In this invention, since the process which adds a shear force in an alkaline solution with respect to wood type biomass is passed, a monosaccharide can be obtained with a high yield from the hemicellulose and cellulose contained in the wood type biomass after a process. The produced monosaccharide can be used as a biorefinery as a fermentation raw material for microorganisms capable of producing ethanol, butanol and other chemical raw materials. In addition, by further enzymatic treatment of glucose obtained by saccharification of woody biomass, it is a refreshing agent D-sorbitol, a sweetener D-fructose, an osmotic pressure regulator mannitol, a feed additive Useful substances such as mannose and other foods and pharmaceuticals can also be produced.

Production of ethanol Ethanol can be produced by performing ethanol fermentation using the sugar obtained in the above-described saccharification step as a raw material. The sugar component obtained in the above saccharification step may contain both cellulose-derived sugar and hemicellulose-derived sugar. Examples of saccharides derived from hemicellulose include pentoses such as xylose and arabinose and hexoses such as glucose, galactose and mannose. The sugar derived from cellulose is glucose hexose. In particular, hexose can be easily converted to ethanol by yeast or the like, and pentose can be converted to ethanol according to an ethanol production method known in the art.

  Ethanol fermentation of hexose can be carried out using yeast or bacteria having a gene necessary for ethanol production by genetic recombination according to an ethanol production method known in the art. Ethanol fermentation of pentoses, for example, genetically modified Escherichia coli in which both pentose and hexoses are assimilated, but that does not produce ethanol, a gene derived from a microorganism that produces ethanol, and ethanol fermentation It can be carried out by using a genetically modified bacterium in which a pentose metabolic gene is introduced into a sexual Zymomonas bacterium (for example, JP-T-5-502366 and JP-A-6-504436) ). Alternatively, a method in which pentose and hexose are fermented with ethanol to recover ethanol and carbon dioxide may be used (Japanese Patent Laid-Open No. 2006-111593).

  Those skilled in the art can appropriately set conditions for ethanol fermentation according to the type of sugar used as a raw material, the type of ethanol-fermenting bacteria used, and the like. Ethanol fermentation may be performed separately for each of the primary sugar solution and the secondary sugar solution, or a mixture of both.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited to these Examples.

[Comparative Example 1]
In this comparative example, in order to compare with the saccharification rate achieved in the examples described later, the woody biomass was pulverized and then pretreated with an alkaline solution, and the saccharification rate by the pretreatment was measured.

  First, a 10 mm square cedar chip was used as a raw material. This was finely pulverized by three types of dry pulverizers (Earth Technica Hammer Mill TSX type, Unotex Twist Mill, Hosokawa Micron ACM Pulverizer). Earth Technica Hammer Mill Model TSX is a hammer mill type, which was pulverized at a hammer rotation speed of 3000 rpm and recovered 3 mm under cedar wood that passed 3 mm mesh. The Uenotex twist mill was pulverized by compression and mashing in a mortar-type disk, and the treated cedar was collected. Hosokawa Micron's ACM Pulverizer is a hammer mill type equipped with a crushing rotor and a classification rotor. Fine pulverization was possible depending on the number of rotations of the classification rotor. Cedar materials were finely pulverized at rotation speeds of 1000, 1500, 2000, 3000, and 4000 rpm, and cedar materials treated at each rotation number were collected.

  Table 1 shows the results of pulverization of cedar wood pulverized by each pulverizer and conditions. The median particle size distribution (D50) was 500 μm for the Earth Technica hammer mill TSX type, and 509 μm for the Uenotex twist mill. On the other hand, in the ACM pulverizer manufactured by Hosokawa Micron, the faster the speed of the classification rotor, the smaller the D50, and the result was that it was pulverized to 76 μm at 4000 rpm. In addition, as a result of examining the classification rate of 500 μm or less in the cedar after pulverization, when it was processed with a Hosokawa Micron ACM pulverizer at a classification rotor rotational speed of 4000 rpm, most of the powder became 500 μm or less fine powder.

  Using the above pulverizers and cedar materials pulverized under each condition, pretreatment with an alkaline solution was performed. Table 2 shows the conditions for pretreatment with an alkaline solution. Caustic soda was used as the alkali, and the amount added was 20% per dry weight of each crushed cedar. Further, the dry cedar weight (hereinafter referred to as slurry concentration) with respect to the volume of the caustic soda aqueous solution was set to 15%. The reaction temperature was room temperature or 130 ° C. treatment using an autoclave, stirring was continued for 18 hours in the room temperature system, and high-temperature and high-pressure treatment was performed for 15 minutes in the 130 ° C. treatment system.

  Thereafter, the cedar after the pretreatment was recovered with a centrifuge, and the solid content was sufficiently washed with 200 mM citrate buffer (pH 4.8). Thereafter, enzymatic saccharification was performed under the conditions shown in Table 3. The cellulase used was Accelerase Duet manufactured by Genencor, and the amount added was unified to 15 FPU / g per dry cedar weight after neutralization [cellulase enzyme activity that produces 10.8 mg of glucose from filter paper in 60 minutes. 1FPU = 10.8 mg / h saccharification rate].

  As a result of the saccharification test using the enzyme described above, the results of measuring the saccharification rates of 6 monosaccharide and 5 monosaccharide are shown in Table 4 and Table 5, respectively. In addition, the saccharification rate described in each table indicates that each monosaccharide in the cedar wood after neutralization (6 monosaccharides: glucose constituting cellulose, glucose constituting hemicellulose, sum of glucose, mannose and galactose, 5 monosaccharides; constituting hemicellulose The ratio of each monosaccharide detected in the solution after saccharification is shown with respect to the sum of xylose and arabinose.

  As shown in Tables 4 and 5, the enzymatic saccharification rate of both 6 monosaccharides and 5 monosaccharides was improved under the conditions of alkaline pretreatment at 130 ° C. at high temperature and high pressure, compared to the case of alkaline pretreatment at room temperature. did. However, the saccharification rate of 6 monosaccharides was 15% or less, and the saccharification rate of 5 monosaccharides was 33% or less. Thus, it became clear that a high saccharification rate could not be obtained even if the cedar wood was pulverized and then mixed with an alkaline solution under high temperature and high pressure.

[Example 1]
In this example, pretreatment such as applying shear force in an alkaline solution to woody biomass was performed, and the saccharification rate was measured.

  The 10 mm square cedar chips used in Comparative Example 1 were coarsely pulverized, and 2 mm under cedar wood that passed through a 2 mm mesh sieve was used as a raw material. A 2 mm under cedar and an aqueous caustic soda solution were mixed so that the slurry concentration was 15% and the caustic soda addition amount per dry cedar weight was 20%.

  Then, the twin screw extruder which consists of a screw with a diameter of 25 mm shown in FIG. 3 was used. The clearance between the screw and the casing is 0.5 mm. In addition, six heater blocks ((1) to (6) in the figure) were installed in the axial direction and set to a predetermined reaction temperature. Cedar and alkaline aqueous solution were continuously charged from the hopper portion of the twin-screw extruder shown in FIG. The rotation speed of the screw was set so that the residence time of cedar wood was 15 minutes.

  The solid content was recovered from the cedar paste extruded from the twin screw extruder using a centrifuge, and thoroughly washed with 200 mM citrate buffer (pH 4.8). Thereafter, enzymatic saccharification was performed under the conditions shown in Table 3 of Comparative Example 1. The cellulase used was Genencor Accelerase, and the amount added was unified to 15 FPU / g per dry cedar weight after neutralization.

  The results of the saccharification rate measured in this example are shown in Table 6. As can be seen from Table 6, the saccharification rate of 6 monosaccharides was 51.1%, and the saccharification rate of 5 monosaccharides was 100%, and an extremely high saccharification rate was achieved as compared with the pretreatment carried out in Comparative Example 1.

[Example 2]
In this example, the relationship between the temperature condition and the saccharification rate when a shearing force was applied to a woody biomass in an alkaline solution was examined.

  The cedar wood under 2 mm used in Example 1 was used as a raw material, mixed with an alkaline aqueous solution, and processed with a twin screw extruder. The slurry concentration in the alkali pretreatment and the caustic soda addition amount per dry cedar weight were the same as in Example 1 (slurry concentration 15%, caustic soda addition amount per dry cedar weight 20%). As shown in Table 7, patterns A to E were set. (1) to (6) in Table 7 correspond to (1) to (6) in FIG. The residence time of cedar wood in the twin screw extruder was unified to 15 minutes.

  Solid content was recovered from the cedar paste obtained at each set temperature with a centrifuge. However, under the condition of the maximum temperature of 200 ° C. shown in Pattern E, the wood was solubilized and could not be recovered sufficiently. For other conditions, the collected solid was sufficiently washed with 200 mM citrate buffer (pH 4.8). Thereafter, enzymatic saccharification was performed under the conditions shown in Table 3 of Comparative Example 1. The cellulase used was Accelerase Duet manufactured by Genencor Corporation, and the addition amount was unified to 15 FPU / g per dry cedar weight after neutralization.

  Table 8 shows the results of enzyme saccharification rate of cedar wood pretreated with alkali at each set temperature pattern in a twin screw extruder. The enzyme saccharification rate changed according to the temperature pattern of the twin screw extruder. In particular, the pattern C conditions with a maximum temperature of 130 ° C. in a twin screw extruder showed high saccharification rates for both 6 monosaccharides and 5 monosaccharides.

Example 3
In this example, actual construction waste plywood was used as the woody biomass. First, in this example, an actual construction waste plywood from which foreign matters such as nails and sand were removed in advance was prepared. This construction waste plywood was coarsely pulverized in the same manner as in Example 1 to produce construction waste wood of 2 mm under which passed through a sieve with 2 mm openings. This was mixed with three types of aqueous solutions of caustic soda (15% caustic soda weight per dry construction waste plywood weight: 5%, 10%, 20%) so that the slurry concentration was 15%.

  Each slurry was introduced into the same twin screw extruder as in Example 1. In addition, the set temperature of the twin-screw extruder was the same as that in FIG. 3 shown in Example 1 for all three types of slurry, and the residence time of the construction waste plywood in the twin-screw extruder was 15 minutes.

  The solid content was recovered from the construction waste plywood paste obtained in each setting with a centrifuge, and the solid content was thoroughly washed with 200 mM citrate buffer (pH 4.8). Thereafter, enzymatic saccharification was performed under the conditions shown in Table 3 of Comparative Example 1. The cellulase used was Accelerase Duet manufactured by Genencor Corporation, and the addition amount was unified to 15 FPU / g per dry cedar weight after neutralization.

  Table 9 shows the results of enzyme saccharification rates of construction waste plywood treated with alkali with each caustic soda addition amount. For both 6 and 5 monosaccharides, the highest enzymatic saccharification rate was achieved at a caustic soda addition rate of 20% per dry construction waste plywood weight.

  The present invention provides an inexpensive and efficient method for saccharification of woody biomass. According to the present saccharification method, not only can the saccharification yields of hemicellulose and cellulose contained in the woody biomass be greatly improved, but also the processing time is short, so that processing with energy saving can be performed.

Claims (1)

A bit mounted on the screw of the multi-screw extruder in an alkaline solution for coarsely pulverized woody biomass using a multi-screw extruder having a plurality of temperature control blocks arranged in series in the axial direction by a step of pasting the woody biomass by adding shearing force, subsequent and a step of the paste is solid collected and saccharification by enzyme, the temperature of the central portion of the plurality of temperature adjustment block A method for saccharification of woody biomass, characterized in that the temperature is 60 to 130 ° C.

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