JP2011206044A - Method of saccharifying cellulose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of saccharifying cellulose which is capable of increasing the conversion ratio of cellulose, the yield ratio of saccharides, and the selectivity ratio of saccharides, while reducing excessive decomposition of saccharides due to a pressurized hydrothermal treatment, and which is capable of increasing the content rate of glucose in the saccharides.SOLUTION: The method of saccharifying cellulose by hydrolyzation includes bringing a raw material containing cellulose into contact with an aqueous solution containing inorganic acid, heat-treating and a pressure-treating the mixture, and obtaining an aqueous solution containing water soluble oligosaccharide or glucose.

Description

  The present invention relates to a cellulose saccharification method. More specifically, the present invention relates to a method for saccharifying cellulose by hardly hydrolyzing a cellulosic polysaccharide that is promising as biomass and generating almost no excessively decomposed product.

  In recent years, saccharides obtained by saccharifying woody biomass have attracted attention as raw materials for producing useful substances such as ethanol and polylactic acid. Cellulose contained in woody biomass is a polysaccharide in which 1000 or more glucoses are connected by β-glycoside bonds. By hydrolyzing cellulose, in addition to glucose, which is a monosaccharide, water-soluble oligosaccharides (cellooligosaccharides) in which 2 to 6 glucoses are connected can be obtained. Among these water-soluble saccharides, glucose is useful for production of ethanol and lactic acid by fermentation using microorganisms, and therefore, a saccharification technique capable of efficiently producing glucose from cellulose is desired.

Conventional methods for saccharifying cellulose include a thermal decomposition method, an enzymatic reaction method in which hydrolysis is performed by an enzymatic reaction, and a pressurized hydrothermal method in which hydrolysis is performed with an aqueous solution in a supercritical or subcritical state (for example, Patent Document 1). Are known.
The thermal decomposition method is a method in which cellulose molecular chains are cleaved by thermal energy, and cellulose can be reduced in molecular weight. However, since it is a thermal reaction, the selectivity of the reaction is poor and the yield of glucose is low.

  The enzyme reaction method is a method of treating with cellulose hydrolase called cellulase, and is characterized by being able to be treated under mild reaction conditions (room temperature to 50 ° C.). In recent years, many domestic and overseas manufacturers have made efforts to develop new cellulases using gene manipulation technology. However, in general, cellulase itself is expensive, and it takes a long time of several days to one week to completely hydrolyze high molecular weight cellulose, which is a raw material, to glucose, resulting in poor productivity. . This is presumably because the reaction with cellulase becomes a solid-liquid reaction because the cellulose is in a solid state and is crystalline, and the reaction rate is low. For these reasons, a route for converting a glucose solution obtained from a cellulose raw material by an enzyme reaction method to ethanol by fermentation then has a significant problem in terms of cost.

  On the other hand, the use of supercritical water and subcritical water has the following advantages. That is, it is known that water in a subcritical state has an increased ionic product, behaves as an acidic aqueous solution, and can hydrolyze cellulose. For example, according to Patent Document 1, glucose can be obtained from cellulose in a yield of 20% or more by using supercritical water or subcritical water. However, if the hydrolysis conditions are too high, the produced glucose undergoes a thermal decomposition reaction, and the yield decreases. Furthermore, it is known that the production of furfurals that are inhibitors of the ethanol fermentation process is also increased.

  Patent Document 2 proposes a method that combines the advantages of the above two methods. That is, this is a method in which cellulose is temporarily solubilized with supercritical water or subcritical water, and hydrolysis is performed with cellulase while the reaction product is dissolved in the solution. This reports the highest yield of 74.3% glucose production. However, this yield is a record of an enzyme treatment time of 5 days (50 ° C.) and does not necessarily lead to a reduction in enzyme saccharification time. Moreover, considering that the supercritical water treatment, which is a pretreatment, is a flow type of slurry, and that the reaction conditions are 320 to 500 ° C. and the pressure is 20 to 50 MPa, the equipment cost and energy cost are low. This is expected, and it seems that the reality is low as a mass production device.

As described above, in the conventional method for obtaining glucose by hydrolyzing cellulose, restrictions on the reaction yield, cost, and production equipment are large, and drastic improvement has been demanded for practical use.
In recent years, attempts have been made to conduct a hydrolysis reaction of cellulose in the presence of an oxidizing agent.
For example, in Patent Document 3, in order to reduce the molecular weight of cellulose, first, pretreatment is performed at 50 to 150 ° C. with an acid hydrate containing an oxidizing substance, and then the solution is adjusted to be acidic and the conditions are 100 to 200 ° C. Shows how to perform the hydrolysis. This is because the hydroxyl group of cellulose is partially oxidized by the above pretreatment to weaken the cohesive force between the cellulose chains and solubilize the cellulose. By applying this treatment, subsequent hydrolysis with dilute acid Is going to be promoted. Certainly, only 0.9% of cellulose is solubilized in a system that does not use an oxidizing agent, but a maximum solubilization rate of 66.7% is achieved by using this method. However, the glucose yield is as low as 30.3% at the maximum, and has not reached the practical level.
Moreover, in patent document 4, hydrolysis is accelerated | stimulated by making polysaccharides, such as a cellulose, contact with pressurized hot water in presence of oxidizing agents, such as a metal salt, and it can convert rapidly into an oligosaccharide or a monosaccharide. It is shown. According to this method, glucose was produced from crystalline cellulose in a yield of 30 to 40% at a reaction temperature of 250 ° C. However, there is a problem that 5-HMF (5-hydroxymethylfurfural), which is a sugar decomposition product and an inhibitor of fermentation, is produced in a yield of about 5 to 9%.

JP-A-5-31000 JP 2001-95594 A JP 2006-320261 A JP 2007-20555 A

  Thus, in the saccharification methods other than the enzyme reaction method of the conventional method, there is a problem that the conversion from cellulose to saccharide is low and the glucose content in the converted saccharide is further low. In addition, there is a problem in that water-insoluble aggregates and saccharide hyperdegradation products are generated as by-products. On the other hand, in addition to the problem of enzyme cost, the enzyme reaction method has an essential problem that it takes a long time for enzyme saccharification unless an appropriate pretreatment is used. If supercritical water / subcritical water treatment is applied as a pretreatment, the final glucose yield may exceed 70%. However, the reaction conditions for pretreatment are severe and the device must be devised. There is a problem that becomes high.

  The present invention has been made in view of the above circumstances, and while reducing the excessive decomposition of saccharides by pressurized hot water treatment, the conversion rate of cellulose, the yield of saccharides, and the selectivity of saccharides can be increased. Furthermore, it aims at providing the cellulose saccharification method which can raise the glucose content rate in this saccharide | sugar.

The cellulose saccharification method according to claim 1 of the present invention is a method for hydrolyzing cellulose to saccharify, wherein a raw material containing cellulose and an aqueous solution containing an inorganic acid are brought into contact with each other and subjected to heat treatment and pressure treatment. Thus, an aqueous solution containing a water-soluble oligosaccharide or glucose is obtained.
The cellulose saccharification method according to claim 2 of the present invention is characterized in that in claim 1, the inorganic acid is phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, or oxo acid of chlorine.
The cellulose saccharification method according to claim 3 of the present invention is characterized in that, in claim 2, the oxo acid of chlorine is perchloric acid.
The cellulose saccharification method according to claim 4 of the present invention is characterized in that, in any one of claims 1 to 3, the heat treatment is in a temperature range of 100 ° C to 200 ° C.
The cellulose saccharification method according to claim 5 of the present invention is characterized in that, in any one of claims 1 to 4, the pressure treatment is in a pressure range of 0.5 MPa to 15 MPa.
The cellulose saccharification method according to claim 6 of the present invention is the aqueous solution containing the operation for contacting, the heat treatment and the pressure treatment, and the water-soluble oligosaccharide or glucose in any one of claims 1 to 5. It is characterized in that the operation for obtaining is performed simultaneously and continuously.

  According to the cellulose saccharification method of the present invention, it is possible to increase the conversion rate of cellulose, the yield of saccharides, and the selectivity of saccharides while reducing the excessive decomposition of saccharides by pressurized hot water treatment. The glucose content in can be increased. The obtained high-purity glucose is useful as a raw material for ethanol fermentation or lactic acid fermentation.

It is an example of the apparatus which can be used for the cellulose saccharification method of this invention.

The present invention will be described in detail below.
The cellulose saccharification method of the present invention is a method for saccharifying cellulose by saccharification, in which a raw material containing cellulose and an aqueous solution containing an inorganic acid are brought into contact (contacting operation), and heat treatment and pressure treatment are performed. (Heat treatment and pressure treatment), a method for obtaining an aqueous solution containing water-soluble oligosaccharides or glucose (operation for obtaining a product).

Here, the cellulose saccharification method of the present invention does not necessarily have to be performed in the order of contact operation, heat treatment and pressure treatment, and operation for obtaining a product, but heat treatment and pressure treatment, contact operation and production. You may perform in order of the operation which obtains a thing, You may perform the operation which makes it contact, the heat processing and pressurization process, and the operation which obtains a product simultaneously and continuously. Moreover, the cellulose saccharification method of this invention may have operations or processes other than the operation to contact, a heat processing and pressurization process, and the operation to obtain a product.
In addition, when performing in order of heat processing and pressurization processing, operation to contact, and operation which obtains a product, what carried out heat processing and pressurization processing of the above-mentioned raw material and the aqueous solution containing the above-mentioned inorganic acid individually, cooling and decompression Without causing the cellulose saccharification reaction to be brought into contact with each other to obtain a product.

The raw material in the present invention is not particularly limited as long as it is a material containing cellulose, and examples thereof include agricultural products such as cotton, rice and wheat straw, wood chips, waste paper, and fibers mainly composed of cotton.
From the viewpoint of increasing the conversion rate from cellulose to saccharides, it is preferable that the raw materials contain as little impurities as possible to inhibit the saccharification reaction. That is, the higher the cellulose content in the raw material of the present invention, the better. More specifically, for example, cotton (cotton) is preferable because it is inexpensive and can be obtained in large quantities. From the same viewpoint, the raw material is preferably composed mainly of cotton, and for example, discarded clothing is preferred. Moreover, the cellulose crystal powder etc. which can purchase a commercial item can also be used. These are preferably pulverized.

As the inorganic acid in the contacting operation of the present invention, for example, phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, or chlorine oxo acid is preferable. When these inorganic acids are used, the conversion rate of cellulose can be further increased.
The inorganic acid is preferably an acid that releases more protons that contribute to the hydrolysis reaction of cellulose. Of the oxoacids of hydrochloric acid, sulfuric acid, nitric acid, and chlorine exemplified as the inorganic acid, hydrochloric acid, nitric acid, chlorine Are more preferred, and chlorine oxoacids are particularly preferred.

When the inorganic acid is phosphoric acid, hydrochloric acid, sulfuric acid, or nitric acid, the normality (N) of these inorganic acids is preferably 0.005 to 1.0 N, although it depends on the amount of cellulose contained in the raw material. 0.005-0.50N is more preferable, and 0.005-0.25N is more preferable.
The conversion rate of a cellulose can fully be raised as it is more than the lower limit of the said range. Moreover, the production | generation of the excessive decomposition product of saccharides can be suppressed as it is below the upper limit of the said range.
The pH of the aqueous solution prepared to the above concentration is usually around pH 1.

The oxo acid of chlorine in the contacting operation of the present invention is not particularly limited. For example, perchloric acid (HClO ₄ ), chloric acid (HClO ₃ ), chlorous acid (HClO ₂ ), hypochlorous acid (HClO) Etc. Among these, perchloric acid or chloric acid is preferable.
Perchloric acid or chloric acid is relatively stable even in an aqueous solution, and has an advantage that the concentration in the aqueous solution can be easily controlled.

Perchloric acid is ionized in an aqueous solution to generate oxonium ions (H ₃ O ⁺ ) and perchlorate ions (ClO ₄ ⁻ ).
In terms of reaction mechanism, (1) the hydroxyl group of cellulose is partially oxidized by the action of perchlorate ions, so that the hydrogen bonds between cellulose chains are weakened and the crystalline state is loosened. This alleviates steric hindrance around the 1,4-glycoside bond. (2) The oxonium ion that is a reactive species easily approaches a 1,4-glycoside bond, and an acid hydrolysis reaction occurs. (3) The saccharification reaction in which glucose is generated via the water-soluble oligosaccharide proceeds promptly. ,it is conceivable that.

The chlorine oxo acid concentration in the aqueous solution containing chlorine oxo acid is preferably 0.01 to 1.0 mol / L, depending on the amount of cellulose contained in the raw material, and preferably 0.05 to 0.5 mol / L. L is more preferable, and 0.08 to 0.25 mol / L is more preferable.
A cellulose can be efficiently saccharified as it is more than the lower limit of the said range. Moreover, the production | generation of the excessive decomposition product of saccharides can be suppressed as it is below the upper limit of the said range.
The pH of the aqueous solution prepared to the above concentration is usually around pH 1.

  The operation method for contacting is not particularly limited. A method of stirring the raw material containing cellulose and the aqueous solution containing the inorganic acid to obtain a mixture may be employed, or the aqueous solution may be allowed to flow and contact with the raw material when it is allowed to stand. good. For example, when the cellulose saccharification apparatus shown in FIG. 1 is used, an appropriate amount of the raw material is charged into the reaction tank 2, and the aqueous solution 5 containing the inorganic acid charged into the storage tank 4 is pumped through the pump 6 and the liquid feeding pipe 7. By feeding the liquid into the reaction tank 2, the mixture 8 can be obtained by mixing the raw material and the aqueous solution 5 in the reaction tank 2.

In the heat treatment and pressure treatment of the present invention, a method for heat-treating the raw material and an aqueous solution containing an inorganic acid is not particularly limited. For example, when the cellulose saccharification apparatus 1 shown in FIG. 1 is used, the mixture 8 in the reaction tank 2 can be heat-treated at a predetermined temperature by the heating unit 10 provided to heat the entire reaction tank 2.
Moreover, in the preheating part 11 provided in the middle of the liquid feeding pipe | tube 7, the mixture 8 is heat-processed by sending the aqueous solution 5 previously heated to predetermined temperature to the reaction tank 2, and adding to the raw material or the mixture 8. It is also possible to do.
As a heat source in the heating part 10 or the preheating part 11, a well-known thing using a heater (electric heater) or a boiler can be used.

The temperature range of the heat treatment is preferably 100 to 200 ° C, more preferably 160 to 190 ° C, and further preferably 175 to 185 ° C.
When it is at least the lower limit of the above range, the conversion from cellulose to saccharide can be increased, and the glucose content in the saccharide can be increased.
When the amount is not more than the upper limit of the above range, excessive decomposition of saccharides can be reduced or suppressed. Moreover, since the burning of the cellulose of a raw material and the production | generation of a tar-like substance can be reduced or suppressed, a raw material can be added sequentially and the saccharification reaction can be performed continuously, without wash | cleaning the reaction tank 2. FIG.

Here, in the specification of the present invention, the conversion rate of cellulose refers to the ratio of the mass of reacted cellulose to the mass of cellulose contained in the raw material. Moreover, the yield of saccharide means the ratio of the mass of the saccharide obtained by saccharification reaction with respect to the mass of the cellulose contained in a raw material. Moreover, the selectivity of saccharide means the ratio of the mass of the saccharide obtained by saccharification reaction with respect to the mass of the said reacted cellulose.
The cellulose saccharification method of the present invention produces water-soluble oligosaccharide and / or glucose. In the present invention, the water-soluble oligosaccharide obtained by hydrolyzing cellulose refers to a water-soluble cellooligosaccharide having a molecular structure in which about 2 to 20 molecules of glucose are condensed and connected. Cellulase may be added to the reaction product obtained in the present invention.

In the heat treatment and pressure treatment of the present invention, the method for pressure treatment of the raw material and the aqueous solution containing an inorganic acid is not particularly limited. For example, when the cellulose saccharification apparatus 1 shown in FIG. 1 is used, since the back pressure valve 13 is provided in the liquid feeding pipe 12 on the downstream side of the reaction tank 2, the aqueous solution 5 is supplied to the reaction tank via the pump 6 and the liquid feeding pipe 7. By sending the solution to 2, the inside of the reaction tank 2 can be increased to a predetermined pressure.
In addition, a pressure treatment for increasing the reaction tank 2 to the vapor pressure of the aqueous solution 5 can be performed by performing a heat treatment with the heating unit 10 in a state where the reaction tank 2 is sealed.

The pressure range of the pressure treatment is preferably 0.5 MPa to 15 MPa, more preferably 5 MPa to 13 MPa.
When it is at least the lower limit of the above range, the conversion from cellulose to saccharide can be increased, and the glucose content in the saccharide can be increased.
Moreover, the excessive decomposition of saccharide | sugar can be reduced or suppressed as it is below the upper limit of the said range.

As described above, by subjecting the raw material and the aqueous solution containing the inorganic acid to contact (mixture) by heat treatment and pressure treatment, the saccharification reaction of cellulose in the mixture by the inorganic acid is promoted, Efficient conversion of cellulose to saccharide occurs to produce water-soluble oligosaccharides and / or glucose.
The time for the heat treatment and the pressure treatment varies depending on the combination of the amount ratio of the raw material and the aqueous solution containing the inorganic acid, the temperature of the heat treatment, and the temperature of the pressure treatment, but in the temperature range and the pressure range. If so, cellulose contained in the raw material can be efficiently saccharified in about 0.5 to 60 minutes.

  In the operation for obtaining the product of the present invention, the method for obtaining an aqueous solution containing a water-soluble oligosaccharide or glucose is not particularly limited. For example, when the cellulose saccharification apparatus 1 shown in FIG. 1 is used, an unreacted raw material and generated water-soluble oligosaccharide and / or glucose are contained in the reaction tank 2 that has undergone the contacting operation and the heat treatment and pressure treatment. There is an aqueous solution containing. At this time, when the aqueous solution 5 containing the inorganic acid is fed from the storage tank 4 through the pump 6 and the liquid feeding pipe 7 to the reaction tank 2, the reaction tank 2 is filled with the back pressure valve 13 provided downstream of the reaction tank 2. The aqueous solution containing the product in the reaction vessel 2 can be separated from the unreacted raw material and extracted from the discharge port 14 to the recovery vessel 15 while maintaining the pressure at a predetermined value. At this time, the unreacted raw material is prevented from flowing out to the discharge port 14 by the filter 16 provided on the downstream side of the reaction tank 2. Similarly, a filter 16 is provided on the upstream side of the reaction tank 2 to prevent the unreacted raw material and the mixture 8 from flowing backward. The aqueous solution containing the product extracted through the filter 16 on the downstream side of the reaction tank 2 is cooled by the cooling unit 18. Thereby, it can prevent that a product is kept at high temperature unnecessarily and is overdecomposed. The cooling method is not particularly limited, and a known method using a reciprocating compressor or the like can be applied.

The aqueous solution 17 containing the product extracted into the recovery tank 15 is an acidic solution (usually around pH 1) because it contains the inorganic acid. If the product is left in the acidic solution for a long time, the product may be decomposed. Therefore, the aqueous solution 17 containing the product is preferably neutral. As a neutralization method, a known method using NaOH, slaked lime, soda ash or the like may be used.
The product in the aqueous solution 17 containing the product can be analyzed and identified by a known method such as HPLC or MS.

  When the cellulose saccharification apparatus 1 as shown in FIG. 1 is used, the raw material and the aqueous solution 5 containing the inorganic acid are mixed, and for the reaction tank 2 in which the heat treatment and the pressure treatment are performed, Furthermore, the aqueous solution 17 containing the said water-soluble oligosaccharide or glucose can be obtained from the reaction tank 2 by flowing out through the filter while introducing the aqueous solution 5. That is, for example, by using the cellulose saccharification apparatus 1 shown in FIG. 1, a continuous cellulose saccharification method in which the contact operation, the heat treatment and the pressure treatment, and the operation for obtaining the product are performed simultaneously and continuously. It can be carried out.

  More specifically, a new aqueous solution 5 containing an inorganic acid is pumped up from the storage tank 4 with a pump 6, heated in the preheating unit 11, and then sent to the reaction tank 2 to perform a pressure treatment, Heat treatment by the heating unit 10 is performed. At the same time, the aqueous solution 17 containing the product obtained by hydrolyzing cellulose is discharged from the reaction tank 2 through the filter 16 while controlling the back pressure valve 13 to maintain the pressure in the reaction tank 2 at a predetermined level. Thus, it can be recovered from the discharge port 14.

  Further, in FIG. 1, only one reaction tank 2 is provided, but by providing two reaction tanks 2 and 2 ′ in parallel downstream of the preheating unit 11, the cellulose saccharification reaction is performed in one reaction tank 2. At the time, when the other reaction tank 2 'is temporarily removed from the line by switching the valve or the like and refilled with the raw material, and the reaction tank 2' is connected to the line again, the reaction tank 2 'is filled with the raw material. In addition, the cellulose saccharification reaction in the cellulose saccharification apparatus 1 can be continued. According to this continuous method, the operation of contacting, the heat treatment and the pressure treatment, and the operation of obtaining the product can be performed simultaneously and continuously.

When the continuous system is used as described above, the product does not stay in the reaction tank 2 for a long time (for example, more than 1 hour), so that it is possible to reduce or suppress the product from being excessively decomposed. . On the other hand, in the case of a so-called batch system instead of a continuous system, the operation for contacting, the heat treatment and the pressure treatment, and the operation for obtaining the product are sequentially performed. The time required increases, and the saccharide produced at the initial stage of the saccharification reaction may be exposed to heat treatment and pressure treatment more than necessary, resulting in a high rate of excessive decomposition. As a by-product generated by the excessive decomposition, for example, 5-hydroxymethylfurfural (5-HMF) can be mentioned.
Therefore, the cellulose saccharification method of the present invention is preferably the continuous method from the viewpoint of reducing or suppressing the excessive decomposition of the product saccharide.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

[Example 1]
Using the cellulose saccharification apparatus 1 shown in FIG. 1, cellulose saccharification contained in cotton was performed in a continuous manner.
First, 12.0 g of raw material cotton was charged into the reaction tank 2, and after adding pure water into the apparatus path, a sufficient amount of perchloric acid aqueous solution prepared to 0.1 mol / L was charged into the storage tank 4. The aqueous perchloric acid solution is fed by a pump 6 at 12 ml / min, and fed to the reaction tank 2 through the liquid feeding pipe 7 to obtain a mixture 8, and the back pressure valve 13 is controlled to control the inside of the reaction tank 2. The pressure was 10 MPa. Then, the heating part 10 and the preheating part 11 were controlled so that the inside of a reaction tank might be 180 degreeC, and the heating was started. The ratio of the length and diameter of the reaction tank 2 (hereinafter referred to as L / D) was 1. The filter 16 used had a mesh size of 25 μm.
After reaching the set temperature, the aqueous solution 17 containing the product was fractionated from the outlet 14 every 5 minutes and recovered as a total of 60 ml of sample solution.
As a result of the experiment, the mass of cotton remaining after the saccharification reaction was 3.83 g, and the mass of cotton (cellulose) reacted by this experiment was 8.17 g (mass before starting the reaction 12.0 g-3.83 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 68.1%.
Moreover, the product contained in the obtained sample solutions 1 to 6 was analyzed using HPLC. Table 1 shows the yields of saccharides, aldehydes, furans, and organic acids (weight ratio of raw material to product).

As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 8.17 g (12.0 g × 68.1%), and the selectivity of the reacted cellulose that became a saccharide was almost 100%. Met. Furthermore, the ratios of glucose and cellobiose with respect to the total mass of the water-soluble oligosaccharide and glucose were 96.9% by mass and 3.1% by mass, respectively, and most of the obtained sugar was glucose. Since the obtained product has an extremely high glucose content, it can be used as it is as a raw material for fermentation without any enzyme treatment with cellulase.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

[Example 2]
The experiment was performed in the same manner as in Example 1 except that the weight of the raw material cotton used was 10.0 g, the temperature of the heat treatment was 240 ° C., the pressure of the pressure treatment was 7 MPa, and the mesh size of the filter was changed to 7 μm. (Yield results from HPLC measurements are shown in Table 2).

As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 0.20 g, and the mass of the cotton (cellulose) reacted by this experiment was 9.80 g (mass before reaction start: 10.0 g-0.20 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 98.0%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 7.65 g (10.0 g × 76.5%), and the selectivity of the reacted cellulose that became a saccharide was about 78. 1%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 93.8% by mass.
The yield of overdecomposed product was 18.4%.
Further, when the cotton remaining after the saccharification reaction was visually observed, the color was dark brown, and charring and adhesion of tar-like substances were observed.

[Example 3]
The experiment was performed in the same manner as in Example 1 except that the temperature of the heat treatment was 260 ° C., the pressure of the pressure treatment was 5 MPa, the filter mesh size was 1 μm, and the flow rate of the pump was 8 ml / min. The results of the yield from HPLC measurement are shown in Table 3).
After obtaining the sample solution 13, sampling was stopped because the filter was clogged.

As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 0.91 g, and the mass of the cotton (cellulose) reacted by this experiment was 11.09 g (mass before starting the reaction 12.0 g-0.91 g). . Therefore, the conversion rate of cellulose (what percentage of raw material cellulose reacted) was 92.4%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 2.46 g (12.0 g × 20.5%), and the selectivity of the reacted cellulose that became a saccharide was about 22. 2%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 93.6% by mass.
The yield of overdecomposed product was 27.5%.
Further, when the cotton remaining after the saccharification reaction was visually observed, the color was dark brown, and charring and adhesion of tar-like substances were observed.

[Comparative Example 1]
Distilled water is used in place of the perchloric acid aqueous solution, the raw material cotton mass is 10.0 g, the temperature of the heat treatment is 200 ° C., the pressure of the pressure treatment is 7 MPa, the mesh size of the filter is 7 μm, The experiment was performed in the same manner as in Example 1 except that the flow rate was changed to 4 ml / min (the results of yield from HPLC measurement are shown in Table 4).

As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 9.15 g, and the mass of the cotton (cellulose) reacted by this experiment was 0.85 g (mass before reaction start: 10.0 g-9.15 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 8.5%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 0.04 g (10.0 g × 0.4%), and the selectivity of the reacted cellulose that became a saccharide was about 4. 7%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 8.8% by mass.
The yield of overdecomposed product was 7.3%.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

  From the above results, the cellulose saccharification methods of Examples 1 to 3 according to the present invention have a cellulose conversion rate, a yield of saccharides (water-soluble oligosaccharides and glucose), and a saccharide selectivity compared to the method of Comparative Example 1. Further, it was confirmed that the glucose content in the saccharide was high.

[Example 4]
Example 1 except that the raw material cotton is 10.0 g, the pressure of the pressure treatment is 5 MPa, the pump flow rate is 8 ml / min, the filter mesh size is 7 μm, and the L / D is 0.5. (The results of the yield from HPLC measurement are shown in Table 5).

As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 5.02 g, and the mass of the cotton (cellulose) reacted by this experiment was 4.98 g (mass before reaction start: 10.0 g-5.02 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 49.8%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 4.80 g (10.0 g × 48.0%), and the selectivity of the reacted cellulose that became a saccharide was about 96. 4%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 95.2% by mass.
The yield of overdecomposed product was 0.0% by mass.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

[Example 5]
Example 1 except that 0.1 mol / L perchloric acid was changed to 0.1 mol / L hydrochloric acid, the mesh size of the filter was changed to 7 μm, and L / D was 2.0. (The results of the yield from HPLC measurement are shown in Table 6).

As a result of the experiment, the mass of cotton remaining after the saccharification reaction was 6.68 g, and the mass of the cotton (cellulose) reacted by this experiment was 5.32 g (mass before starting the reaction 12.0 g-6.68 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 44.3%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 3.23 g (12.0 g × 26.9%), and the selectivity of the reacted cellulose that became a saccharide was about 60. 7%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 95.8% by mass.
The yield of overdecomposed product was 0.0% by mass.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

[Example 6]
The 0.1 mol / L perchloric acid was changed to 0.005 mol / L (0.01 N) sulfuric acid, and the weight of the raw material cotton used was 8.0 g, the pressure of the pressure treatment was 7 MPa, The experiment was performed in the same manner as in Example 1 except that the flow rate was changed to 8 ml / min, the mesh size of the filter was changed to 7 μm, and the L / D was set to 2.0 (the result of yield from HPLC measurement is shown in Table 7). To show).

As a result of the experiment, the mass of cotton remaining after the saccharification reaction was 6.38 g, and the mass of the cotton (cellulose) reacted by this experiment was 1.62 g (mass before reaction start: 8.0 g-6.38 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 20.3%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 1.30 g (8.0 g × 16.21%), and the selectivity of the reacted cellulose that became a saccharide was about 80. 2%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 54.3% by mass.
The yield of overdecomposed product was 0.0% by mass.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

[Example 7]
The 0.1 mol / L perchloric acid was changed to 0.05 mol / L nitric acid, the mass of the raw material cotton used was 8.0 g, the pressure of the pressure treatment was 5 MPa, and the mesh size of the filter was 7 μm. Except for the change, the experiment was performed in the same manner as in Example 1 (results of yield from HPLC measurement are shown in Table 8).

As a result of the experiment, the mass of cotton remaining after the saccharification reaction was 4.84 g, and the mass of cotton (cellulose) reacted by this experiment was 3.16 g (mass pre-reaction mass of 8.0 g-4.84 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 39.5%.
As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 2.37 g (8.0 g × 29.59%), and the selectivity of the reacted cellulose that became a saccharide was about 75. 0%. Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 87.7% by mass.
The yield of overdecomposed product was 0.0% by mass.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

  From the above results, the cellulose saccharification methods of Examples 4 to 7 according to the present invention have a cellulose conversion rate, a yield of saccharides (water-soluble oligosaccharide and glucose), and a saccharide selectivity compared to the method of Comparative Example 1. It is clear that the glucose content in the saccharide is also high.

[Example 8]
Using the cellulose saccharification apparatus 1 shown in FIG. 1, cellulose saccharification contained in cotton was performed in a continuous manner.
First, 10.0 g of cotton as a raw material was charged into the reaction tank 2, pure water was filled in the apparatus path, and a sufficient amount of a 0.77N aqueous solution of phosphoric acid (H ₃ PO ₄ ) was charged into the storage tank 4. The aqueous phosphoric acid solution is fed by the pump 6 at 6 ml / min, and fed to the reaction tank 2 through the liquid feeding pipe 7 to obtain a mixture 8, and the back pressure valve 13 is controlled to control the pressure in the reaction tank 2. Was 10 MPa. Then, the heating part 10 and the preheating part 11 were controlled so that the inside of a reaction tank might be 180 degreeC, and the heating was started. The ratio of the length and diameter of the reaction tank 2 (hereinafter referred to as L / D) was 2. The filter 16 used had a mesh size of 7 μm.
After reaching the set temperature, the sample solution of the aqueous solution 17 containing the product was collected from the outlet 14 for 60 minutes.

As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 5.78 g, and the mass of the cotton (cellulose) reacted by this experiment was 4.22 g (mass before reaction start: 10.0 g-5.78 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 42.2%.
Moreover, the product contained in the obtained sample solution was analyzed using HPLC. Table 9 shows the yields of saccharides, aldehydes, furans, and organic acids (raw material to product weight ratio%).

As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 3.11 g (10.0 g × 31.1%), and the selectivity of the reacted cellulose that became a saccharide was 73.7. % (3.11 g ÷ 4.22 g). Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 78.8% (2.45 g ÷ 3.11 g), and most of the obtained sugar was glucose.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

[Example 9]
It carried out similarly to Example 8 except having changed heating temperature into 200 degreeC.
As a result of the experiment, the mass of the cotton remaining after the saccharification reaction was 5.23 g, and the mass of the cotton (cellulose) reacted in this experiment was 4.77 g (mass before reaction start: 10.0 g-5.23 g). . Therefore, the conversion rate of cellulose (what percentage of the raw material cellulose reacted) was 47.7%.
Moreover, the product contained in the obtained sample solution was analyzed using HPLC. Table 10 shows the yields of saccharides, aldehydes, furans, and organic acids (raw material to product weight ratio%).

As a result of HPLC analysis, the total mass of the obtained water-soluble oligosaccharide and glucose was 3.26 g (10.0 g × 32.6%), and the selectivity of the reacted cellulose that became a saccharide was 68.3. % (3.26 g ÷ 4.77 g). Furthermore, the ratio of glucose to the total mass of the water-soluble oligosaccharide and glucose was 85.3% (2.78 g ÷ 3.26 g), and most of the obtained sugar was glucose.
In addition, when the cotton remaining after the saccharification reaction was visually observed, the color was pale yellowish white, and no burning or tar-like substance was observed.

  The cellulose saccharification method of the present invention can be widely used for producing saccharides from raw materials containing cellulose.

DESCRIPTION OF SYMBOLS 1 ... Cellulose saccharification apparatus, 2 ... Reaction tank, 4 ... Storage tank, 5 ... Aqueous solution, 6 ... Pump, 7 ... Liquid feeding pipe, 8 ... Mixture, 10 ... Heating part, 11 ... Preheating part, 12 ... Liquid feeding pipe, DESCRIPTION OF SYMBOLS 13 ... Back pressure valve, 14 ... Discharge port, 15 ... Collection tank, 16 ... Filter, 17 ... Aqueous solution containing a product, 18 ... Cooling part.

Claims (6)

A method of hydrolyzing cellulose to saccharify,
Contacting a raw material containing cellulose and an aqueous solution containing an inorganic acid,
A cellulose saccharification method characterized by obtaining a water-soluble oligosaccharide or an aqueous solution containing glucose by heat treatment and pressure treatment.   The cellulose saccharification method according to claim 1, wherein the inorganic acid is phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, or chlorine oxo acid.   The cellulose saccharification method according to claim 2, wherein the oxo acid of chlorine is perchloric acid.   The cellulose saccharification method according to any one of claims 1 to 3, wherein the heat treatment is in a temperature range of 100C to 200C.   The cellulose saccharification method according to any one of claims 1 to 4, wherein the pressure treatment is in a pressure range of 0.5 MPa to 15 MPa.   The operation for obtaining the aqueous solution containing the water-soluble oligosaccharide or glucose and the operation for contacting, the heat treatment and the pressure treatment, and the water-soluble oligosaccharide or glucose are performed simultaneously and continuously. The cellulose saccharification method according to 1.

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