JP2014092443A - Evaluation method of saccharification performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly evaluate saccharification performance on cellulosic biomass on a cellulosic biomass processing using an alkali solution without actually saccharifying with enzyme.SOLUTION: In the middle of or after a pretreatment process in which cellulosic biomass is contacted to an alkali solution, pyrolysis temperature of the cellulosic biomass is measured, and saccharification performance on a cellulosic biomass processing is evaluated based on the measured pyrolysis temperature.

Description

  The present invention relates to a method for evaluating saccharification performance in which saccharification performance in a saccharification step is evaluated in advance with respect to an alkali treatment performed prior to the saccharification step of cellulosic biomass.

  Cellulosic biomass is being studied as a raw material for biofuels and chemical products. Cellulosic biomass is mainly composed of cellulose, hemicellulose, and lignin. Among them, cellulose is a polysaccharide in which glucose (monosaccharide component) is linked in a chain, and is hydrolyzed by acid, degrading enzyme (cellulase), etc. By doing so, it can be decomposed to glucose which is a monosaccharide component.

  Glucose obtained by decomposing cellulosic biomass can be used as a raw material for alcohol fermentation. In other words, cellulosic biomass is expected to be used as a raw material for bioethanol, which is an alternative to gasoline, and biobutanol, which is an alternative to light oil.

  Moreover, at present, it is said that 95% of the fossil resource-derived synthetic polymer can be produced from glucose with the development of biorefinery technology (Non-patent Document 1). As described above, since most of the biorefinery has glucose as a starting material, efficient production of glucose from plant resources, that is, “saccharification” is the basis of biorefinery.

  Cellulosic biomass is classified into woody and herbaceous, but woody is a biomass that has a large amount of existence and has high energy density and high utility value compared to herbaceous. However, cellulose of woody biomass is highly crystalline with molecular chains firmly bonded by intermolecular hydrogen bonding. In addition, hemicellulose and lignin are surrounded by a complicated three-dimensional network structure around the cellulose molecular chain, and high saccharification performance cannot be obtained even when cellulase, which is a cellulose-degrading enzyme, is allowed to act directly.

  In recent years, pretreatment methods for improving saccharification performance with cellulase have been developed. In particular, a pretreatment method using an alkaline solution such as caustic soda has become a practical stage centering on herbaceous biomass such as rice straw (Patent Document 1).

JP 2009-125050 A

Yoshikuni Teramoto et al. “Bioethanol Production from Lignocellulose: History, Current Status, and New Developments of Wood Saccharification and Biorefinery” January 2008

  However, in order to grasp the saccharification performance in the saccharification process regardless of whether the cellulosic biomass is woody or herbaceous, the biomass after alkali treatment is reacted with cellulase, and the dissolved saccharide is quantified by instrumental analysis such as liquid chromatography. There was a need. This method can grasp reliable performance, but has a problem that it takes a long time to obtain a result, and the cost is high because of using an enzyme.

  Therefore, in view of the above-described circumstances, the present invention provides an evaluation method for quickly grasping saccharification performance without actually saccharifying the cellulose-based biomass when the cellulose-based biomass is treated with an alkaline solution. The purpose is to do.

The present invention that has achieved the above-described object includes the following.
(1) A pretreatment step in which cellulosic biomass is brought into contact with an alkaline solution, and a saccharification step in which the cellulose biomass after the pretreatment step is saccharified with a hydrolase, and in the middle of the pretreatment step or the pretreatment step The evaluation method of saccharification performance which measures the thermal decomposition temperature of the cellulosic biomass after and evaluates the saccharification performance in a saccharification process based on the measured thermal decomposition temperature.
(2) The method for evaluating saccharification performance according to (1), wherein the thermal decomposition temperature is determined based on a TG (Thermogravimetry) curve by differential thermal-thermogravimetric simultaneous measurement analysis.
(3) The method for evaluating saccharification performance according to (1), wherein the cellulosic biomass is neutralized and washed before measuring the thermal decomposition temperature of the cellulosic biomass.

  The saccharification performance evaluation method according to the present invention can evaluate the saccharification performance quickly and at low cost for the saccharification treatment with an enzyme after contacting the cellulosic biomass with an alkaline solution. Therefore, by applying the present invention, pretreatment using an alkaline solution in a system for producing a constituent monosaccharide using cellulosic biomass, and a system for producing biofuel or biobutanol using the constituent monosaccharide The saccharification process using the cellulosic biomass after the process and the pretreatment process can be optimized quickly and at low cost.

It is a flowchart which shows the manufacture flow of the ethanol manufacturing method shown as an example. It is a characteristic view which shows the result of having analyzed TG-DTA about No. 1 sample prepared in the Example. It is a characteristic view which shows the result of having analyzed TG-DTA about No. 2 sample prepared in the Example. It is a characteristic view which shows the result of having analyzed TG-DTA about No. 3 sample prepared in the Example. It is a characteristic view which shows the result of having analyzed TG-DTA about No. 4 sample prepared in the Example. It is a characteristic view which shows the relationship between the thermal decomposition temperature of the cellulose biomass after a pre-processing, and the saccharification rate of hexose about the cellulosic biomass used in the Example as an example.

Hereinafter, the saccharification performance evaluation method according to the present invention will be described in more detail.
The saccharification performance evaluation method according to the present invention includes a saccharification when performing a pretreatment step of bringing a cellulosic biomass into contact with an alkaline solution and a saccharification step of saccharifying the cellulosic biomass after the pretreatment step with a hydrolase. This is a method for evaluating saccharification performance in the process in advance. The saccharification performance evaluation method according to the present invention particularly measures the pyrolysis temperature of the cellulosic biomass during the pretreatment step or after the pretreatment step. The saccharification performance evaluation method according to the present invention evaluates the saccharification performance in the saccharification step based on the thermal decomposition temperature thus measured.

  Here, the cellulosic biomass is meant to include biomass containing cellulose as a constituent component. Cellulosic biomass is meant to include both herbaceous biomass and woody biomass.

  Herbaceous biomass means a material mainly composed of herbs as a raw material. The herbaceous biomass is not particularly limited, and examples thereof include herbs themselves, a part of herbs, processed herbs, and herb-derived products. More specifically, examples of herbaceous biomass include rice straw, straw, bagasse, bamboo, corn stover, switchgrass, turf, rice husk, various weeds, soybean hulls, and the like. The herbaceous biomass may be composed of one kind of herb or a plurality of kinds of herb. In addition, as herbaceous biomass, you may use the pellet shape | molded by applying desired pressure with respect to the grass which is a raw material.

  The woody biomass is not particularly limited as long as the woody biomass is a woody resource. For example, construction wood, waste packaging materials, logging materials, sawdust, thinned wood, wood chips, rice straw, bark Forest land remnants, unused trees, and backboard. The woody biomass may be composed of one kind of woody resource, or may be composed of a plurality of kinds of woody resources.

  The saccharification performance evaluation method according to the present invention can be applied to, for example, an ethanol production flow from cellulosic biomass shown in FIG. That is, in the ethanol production method shown in FIG. 1, first, biomass is mixed with an aqueous caustic soda solution, and a pretreatment for enzymatic saccharification is performed using physical treatment such as stirring and pulverization. Next, in the ethanol production method shown in FIG. 1, neutralization is performed using acid to a pH suitable for the action of cellulase and ethanol-producing bacteria, followed by solid-liquid separation. In the method for producing ethanol shown in FIG. 1, cellulase and pre-grown ethanol-producing bacteria are charged into the same tank and reacted at a predetermined temperature and pH to proceed with saccharification and fermentation (simultaneously). Saccharification and fermentation). In the ethanol production method shown in FIG. 1, 99.5% high-concentration ethanol can finally be produced by distilling the obtained fermentation broth containing ethanol and then dehydrating it. The saccharification performance evaluation method according to the present invention evaluates the reaction efficiency of a saccharification reaction by cellulase in the above-described simultaneous saccharification and fermentation step.

<Pretreatment process>
Here, the alkaline solution used in the pretreatment step means an aqueous solution of hydroxide of alkali metal or alkaline earth metal (synonymous with the Group 2 element in the present invention). That is, the hydroxide contained in the alkaline solution includes lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, water Examples include strontium oxide, barium hydroxide, and radium hydroxide. Among these, it is preferable to use sodium hydroxide, potassium hydroxide, or calcium hydroxide from the influence of inhibition in the subsequent fermentation process. In particular, sodium hydroxide is preferably used from the viewpoint of drug cost and solubility in water.

  When using herbaceous biomass as cellulosic biomass, the pH of the alkaline aqueous solution can be 9.5 to 13.5, preferably 10 to 13, and more preferably 11 to 12.5. preferable. The herbaceous biomass amount (feed amount) with respect to the alkaline solution amount is not particularly limited, but is, for example, 5 to 20%, desirably 10 to 15%, based on the dry weight of the herbaceous biomass.

  When the herbaceous biomass is pelletized, the pellet is swelled in about 1 minute after being put into the alkaline solution, and then uniformly dispersed by mild agitation. In contrast, herbaceous biomass that has not been pelletized, for example, roll herbaceous biomass, can be swollen by being immersed in an alkaline solution and sufficiently stirred. Therefore, when the herbaceous biomass is pelletized, the amount of herbaceous biomass charged into the alkaline solution can be greatly increased, and the energy required for stirring can be reduced.

  The temperature conditions for the alkali treatment may be, for example, from room temperature to 160 ° C., preferably from room temperature to 121 ° C., for example, 80 ° C. The retention time can be set depending on the temperature of the alkali treatment and the shape of the herbaceous biomass, but when the herbaceous biomass is pelletized, the alkali solution only needs to penetrate sufficiently, and is generally in the range of 15 minutes to 24 hours. For example, in the case of an alkaline solution at 80 ° C., the time is about 6 hours.

  In the pretreatment step, the herbaceous biomass is infiltrated into the alkaline solution and then neutralized by adding an acid such as sulfuric acid. The pH after adding the acid to the alkaline solution is preferably a pH suitable for the enzyme treatment described later. Note that the solid component may be recovered by solid-liquid separation before neutralization with an acid, and then the alkali impregnated in the herbaceous biomass may be neutralized by immersing the solid component in an acidic solution.

  On the other hand, when using woody biomass as the cellulosic biomass, it is preferable to employ a method of applying a shearing force to the woody biomass in an alkaline solution. The means for applying a shearing force to the woody biomass in an 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. At this time, although it does not specifically limit as woody biomass used as a raw material, For example, the wood chip coarsely ground to about 2-15 mm can be used. 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.

  When using woody biomass as cellulosic biomass, the pH of the alkaline aqueous solution can be 9.5 to 13.5, preferably 10 to 13, and more preferably pH 11 to 12.5. preferable. In addition, when using a twin screw extruder, it is desirable to use sodium hydroxide or potassium hydroxide. When sodium hydroxide or potassium hydroxide is used as the alkaline solution, scale generation in 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 to 50 wood weight with respect to 100 solution volume.

  Note that the woody biomass and the alkali solution may be independently fed into a twin-screw extruder, or may be fed into a twin-screw extruder after being mixed in advance. In other words, adding shear force to woody biomass in an alkaline solution means that an alkali solution is added while applying a shearing force to the woody biomass, and the shearing force is applied with woody biomass being added to the alkali solution. It means both forms of loading.

  Moreover, it is preferable to isolate | separate into a liquid component and solid content, after adding a shear force in an alkaline solution with respect to wood type biomass at a pre-processing process. Specifically, the pasty woody biomass extruded from a twin screw extruder or the like 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. The solid-liquid separation process can be performed by any method known in this technical field. In addition, the liquid component recovered by the solid-liquid separation process may be subjected to wastewater treatment or may be reused.

<Saccharification process>
In this step, the cellulosic biomass after the pretreatment step described above is subjected to cellulase enzyme treatment, whereby cellulose in the cellulosic biomass is decomposed to glucose by cellulase. In this step, hemicellulose contained in cellulosic biomass may be saccharified to monosaccharides such as mannose, galactose, xylose, and arabinose. The cellulase used is not particularly limited as long as it can saccharify cellulose to hexose. The cellulase used is preferably one that can further saccharify hemicellulose to hexose and pentose. 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 fermenting cellulase-producing bacteria using cellulosic biomass neutralized after alkali treatment as a raw material, it is possible to decompose cellulose in the biomass 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 cellulosic enzyme treatment of the cellulosic biomass after alkali treatment as described above, the cellulosic biomass after the alkali treatment may be used as a raw material for simultaneous fermentation of cellulase-producing bacteria and ethanol-fermenting bacteria to produce ethanol. Is possible.

  The monosaccharides produced in this step 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 cellulosic 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.

<Ethanol production process>
Ethanol can be produced by performing ethanol fermentation using the sugar obtained in the above 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.

<Evaluation process>
The saccharification performance in the saccharification process described above can be evaluated by the level of saccharification rate. That is, if the amount of monosaccharide obtained by the saccharification process is high with respect to the amount of the cellulose-based biomass added (that is, if the saccharification rate is high), it can be evaluated that the saccharification process has excellent saccharification performance. Conversely, if the amount of monosaccharide obtained by the saccharification process is low with respect to the amount of cellulosic biomass input (that is, if the effect rate is low), it can be evaluated that the saccharification process is inferior in saccharification performance. Here, the saccharification rate is not particularly limited, but can be shown as a ratio of cellulose or hemicellulose in the biomass converted to monosaccharides by the action of cellulase, 100 × (total amount of monosaccharides in the solution after saccharification) / (Total amount of monosaccharides comprised in the biomass before saccharification).

  It can be said that the pre-processing process mentioned above is a process for improving the saccharification performance in a saccharification process. That is, various conditions in the pretreatment process, such as pH of the alkaline solution, treatment time, treatment temperature, stirring conditions, shearing force conditions, etc., are set to improve saccharification performance.

  In this evaluation process, the improvement effect of the saccharification performance by the pretreatment process can be evaluated predictively without going through the saccharification process. Specifically, in this evaluation process, the thermal decomposition temperature of the cellulosic biomass after the pretreatment process is measured, and the saccharification performance is evaluated based on the measured thermal decomposition temperature. More specifically, since there is a negative correlation between the pyrolysis temperature and the saccharification rate in the cellulosic biomass after the pretreatment step, it is evaluated that the saccharification performance is high if the pyrolysis temperature is low, and conversely the above heat It can be evaluated that the saccharification performance is poor if the decomposition temperature is high.

  Here, the pyrolysis temperature of the cellulosic biomass is not particularly limited. For example, differential thermal-thermogravimetric simultaneous analysis (TG-DTA analysis) thermogravimetric gas chromatographic mass analysis (TG-GC / MS) ) Etc., and can be measured based on a TG (Thermogravimetry) curve.

  By applying the present invention, it is possible to quickly predict the enzyme saccharification promoting effect of the pretreatment process, and to provide information that contributes to the determination of performing the saccharification process and the simultaneous saccharification and fermentation process. As a result, the annual operating rate of sugar production plants and ethanol production plants using cellulosic biomass as raw materials will be improved, and as a result, the amount of wastewater and waste generated will be reduced, which will ensure stable production and cost reduction. Can be expected.

  Conventionally, in order to confirm the effect of improving the saccharification performance by the pretreatment process, a part of the sample after the pretreatment process is collected, and cellulase is actually acted on the collected sample (solid content) to advance the enzymatic saccharification. After the passage of time, the saccharified solution was collected and filtered, and then it was necessary to quantitatively analyze the monosaccharides in the saccharified solution by liquid chromatography. Since it takes at least about 4 days to proceed with this series of evaluation procedures, it was difficult to predict the performance before starting the saccharification process and the simultaneous saccharification and fermentation process at the scale of the manufacturing plant.

  Here, when the enzyme saccharification promoting effect by the pretreatment step is low, simultaneous saccharification and fermentation is not successful, and cellulase, which is an expensive drug, and pre-cultured ethanol-producing bacteria are wasted. In addition, by pulling out slurry, cleaning tanks and piping, and sterilizing to start up the plant, the operation rate of the entire plant decreases, and the annual ethanol production volume decreases. Become. In particular, when construction waste wood or pruned wood, which is a waste system, is used as a raw material, since the quality is not constant as compared with virgin wood, the above problems are likely to occur.

  According to the evaluation method of the present invention, since saccharification performance in the saccharification step can be evaluated before the saccharification step is performed, it is possible to avoid wasting cellulase and ethanol-producing bacteria. Furthermore, according to the evaluation method according to the present invention, since the saccharification performance in the saccharification step can be evaluated before the saccharification step is performed, it is possible to achieve excellent productivity without reducing the operation rate of the entire manufacturing plant. it can. Furthermore, according to the evaluation method according to the present invention, it is predictive regardless of the type of cellulosic biomass used as a raw material (for example, waste type such as construction waste wood or pruned wood or virgin wood). Since the saccharification performance can be evaluated, the above problems can be reliably avoided.

  As an example, after the pretreatment step, the pyrolysis temperature of the cellulosic biomass is measured based on a TG curve by TG-DTA analysis. When the measured thermal decomposition temperature is below a threshold value, it can be judged that the saccharification performance in the subsequent saccharification process is excellent. Here, the threshold is not particularly limited, but the saccharification rate calculated from the amount of cellulose contained in the cellulosic biomass and the amount of glucose produced, and the thermal decomposition temperature of the cellulosic biomass after pretreatment, From this, a correlation diagram can be prepared, and based on the correlation diagram, the thermal decomposition temperature at which the target saccharification rate is obtained can be determined as a threshold value. As an example, when the pyrolysis temperature of the cellulosic biomass after pretreatment is 320 ° C. or less, the saccharification rate of hexose is 50% or more. Moreover, when the thermal decomposition temperature of the cellulosic biomass after pretreatment is 262 ° C. or lower, the saccharification rate of hexose is 70% or higher. Therefore, when the target value of the saccharification rate is 50%, the threshold value of the thermal decomposition temperature can be 320 ° C., and when the target value of the saccharification rate is 70%, the threshold value of the thermal decomposition temperature is set to 262 ° C. Can do.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the technical scope of this invention is not limited to a following example.

[Example 1]
In this example, first, Toshiba Machine Co., Ltd. TEM-58SS-10 (screw diameter 57.2mm, L / D41.4, clearance between screw and cylinder 0.4mm) was used as a twin screw extruder, An alkali treatment was performed. In the twin screw extruder, two screws are built in the cylinder of the twin screw extruder, and in order to provide a mechanism such as kneading, shearing, and returning in the axial direction of the screw, the screw is used in units such as kneeling and reverse. Can be configured freely. The reaction temperature can be set up to 200 ° C. for each unit by a barrel outside the screw installed in the axial direction. Inside the cylinder, the two screws rotate in the same direction, so that a shearing force can be continuously applied to the input raw material.

  In this example, construction waste wood preliminarily ground to 2 mm under NaOH aqueous solution was mixed to form a slurry. This was continuously introduced into a twin screw extruder having a maximum set temperature of 110 ° C. Table 1 shows the alkali treatment conditions for construction waste wood using a twin-screw extruder.

  A portion of construction waste wood slurry treated with alkali under each experimental condition was thoroughly washed with distilled water and 200 mM citrate buffer (pH 4.4), and the solid content was recovered by solid-liquid separation. The test was conducted.

  That is, enzymatic saccharification with cellulase was performed based on the conditions shown in Table 2 using the solid content after alkali treatment.

  The cellulase used in this example was Accelerase Duet manufactured by Danisco, and the amount added was unified to 15 FPU / g per dry solid weight (1FPU is the amount of enzyme required to produce 1 μmol / min reducing sugar from cellulose). The amount of C6 sugar (glucose, mannose and galactose) and C5 sugar (xylose and arabinose) is determined by filtering the slurry after enzymatic saccharification and quantifying each monosaccharide contained in the obtained filtrate by HPLC. It was.

  Table 3 shows enzyme saccharification rates obtained by the above alkali treatment and enzyme saccharification. As a result, the enzymatic saccharification rate obtained under each alkali treatment condition showed a high C5 saccharification rate of 89% or more, but the C6 saccharification rate varied from 54 to 70%. .

In this example, the thermal decomposition temperature was measured for the slurry treated with alkali under the conditions shown in Table 1. Specifically, the slurry after the alkali treatment was separated so as to be about 5 g-dry per dry weight, mixed with 100 mL of 200 mM citrate buffer (pH 4.4), and then used with a suction filter. After recovering the solid content, washing and filtration were further performed while successively adding distilled water, and the obtained solid content was used for TG-DTA analysis. A thermal analyzer TG-DTA8120 (Rigaku) was used for the TG-DTA analysis. The measurement was performed under the condition of raising the temperature from room temperature to 510 ° C. at a rate of 20 ° C./min in an N ₂ atmosphere (150 mL / min). The TG-DTA charts for the samples No. 1 to 4 are shown in FIGS. 2 to 5, the TG curve continues to decrease to over 100 ° C. immediately after the start of analysis, and once reaches a steady state at about 150 ° C. This is a decrease in weight due to evaporation of moisture because the sample used for analysis contained moisture. Furthermore, a decrease in the TG curve was also observed at 150 ° C to 350 ° C. This is thought to be due to a decrease in the weight of a part of the sample due to thermal decomposition. When the thermal decomposition temperature here was calculated | required with the analysis software of the analyzer, the thermal decomposition temperature was 293.2 degreeC, 262.0 degreeC, 262.4 degreeC, and 321.2 degreeC about the sample of No.1-No.4.

  FIG. 6 shows the relationship between the result of measuring the thermal decomposition temperature and the C6 saccharification rate shown in Table 3. As shown in FIG. 6, it was found that there is a high negative correlation between the thermal decomposition temperature of the cellulosic biomass after alkali treatment and the saccharification rate of hexose (R2 = 0.9514). From the results of this Example, it was revealed that saccharification performance in the saccharification step after alkali treatment can be evaluated with high accuracy based on the thermal decomposition temperature of the cellulose biomass after the alkali treatment of the cellulosic biomass.

  Regarding the above findings, when cellulosic biomass is composed of lignin, hemicellulose, and cellulose, part of the lignin is eliminated by alkali treatment, and high-crystalline cellulose is reduced in molecular weight and low crystallization. It is thought that the physical characteristics have changed greatly.

Claims (3)

A pretreatment step of bringing the cellulosic biomass into contact with an alkaline solution, and a saccharification step of saccharifying the cellulosic biomass after the pretreatment step with a hydrolase,
The evaluation method of saccharification performance which measures the thermal decomposition temperature of the cellulosic biomass in the middle of the said pretreatment process or after the said pretreatment process, and evaluates the saccharification performance in a saccharification process based on the measured thermal decomposition temperature.   2. The method for evaluating saccharification performance according to claim 1, wherein the thermal decomposition temperature is determined based on a TG (Thermogravimetry) curve by differential thermal-thermogravimetric simultaneous measurement analysis.   The method for evaluating saccharification performance according to claim 1, wherein the cellulosic biomass is neutralized and washed before measuring the thermal decomposition temperature of the cellulosic biomass.

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