JP7191313B2 - Method for producing cellooligosaccharide - Google Patents

Description

The present invention relates to a method for producing cellooligosaccharides. More specifically, the present invention relates to a method for selectively producing cellooligosaccharides containing oligomers having a glucose polymerization degree (G) of 3 or more by hydrolyzing plant biomass using a carbon catalyst.

Cellooligosaccharides are short-chain linear polymers in which glucose is β-1,4-linked and polymerized. It is widely used as an additive in the cosmetics industry. For example, cellooligosaccharides are effective in preventing lifestyle-related diseases such as diabetes and obesity by stimulating the growth of beneficial bacteria in the human digestive system (Non-Patent Document 1). It has been reported that when administered at a low concentration, it acts as an inducer that activates the immune defense ability of plants and improves the yield of crops (Non-Patent Document 2).
In particular, cellooligosaccharides with a degree of polymerization of glucose of about 3 to 8 exhibit moderate solubility in water, and are expected to increase the durability of the above-mentioned functions and provide new functionalities.

Cellooligosaccharides currently used industrially are produced by an enzymatic reaction, but the main components are glucose and dimeric cellobiose, and they contain almost no oligomers higher than trimeric cellotriose (especially Japanese Patent Application Laid-Open No. 2009-189293; Patent Document 1).

Cellooligosaccharide production techniques other than enzymatic methods include a hydrothermal treatment method (International Publication No. 2012/128055 pamphlet (US9284614B2); Patent Document 2, etc.), a hydrothermal treatment method using oxidized water containing hypochlorous acid (JP 2006- No. 320261 and Patent Document 3) are known, but cellooligosaccharides are treated as an intermediate product in the process of decomposing cellulose into glucose, and specific data such as yield are not disclosed. That is, a method for industrially efficiently producing an oligomer having a glucose polymerization degree of 3 or more has not been established, and a cellooligosaccharide containing an oligomer having a glucose polymerization degree (G) of 3 or more that is not currently industrially produced. is desired to establish a production method that can be obtained in a high yield.

As a technique related to the present invention, a method of producing sugars by hydrolyzing raw materials such as biomass containing cellulose using a solid catalyst that hydrolyzes cellulose has been proposed.
In Japanese Patent No. 4604194 (Patent Document 4), as a method for efficiently hydrolyzing cellulose to obtain glucose, an activated carbon solid having an acidic functional group or a basic functional group that catalyzes the hydrolysis reaction of cellulose is disclosed. A catalytic method is disclosed, but the production of cellooligosaccharides is not described.

The present inventors have disclosed a method of continuously obtaining mainly glucose as a product by continuously passing a slurry of plant biomass and a carbon catalyst through a reaction liquid flow tube to cause a hydrothermal reaction (especially Japanese Patent Laid-Open No. 2017-109187; Patent Document 5). In Patent Document 5, depending on the reaction conditions, G2 or higher cellooligosaccharides are produced, but the yield and selectivity for G3 or higher oligosaccharides are not disclosed.

In the hydrolysis reaction of plant biomass using a carbon catalyst, the present inventors also found that the temperature time in the range of 170 to 230 ° C. in the graph showing the relationship between the reaction temperature (vertical axis) and the reaction time (horizontal axis) discloses a method for producing cellooligosaccharides containing oligomers of G3 to G6 by controlling the product to a specific range and performing a hydrothermal reaction (International Publication No. 2017/104687 pamphlet; Patent Document 6). .

JP 2009-189293 A International Publication No. 2012/128055 Pamphlet Japanese Patent Application Laid-Open No. 2006-320261 Japanese Patent No. 4604194 JP 2017-109187 A International Publication No. 2017/104687 Pamphlet

Polym. Int. , 66, 1227 (2017) Plant Physiol. , 173, 2383 (2017)

An object of the present invention is to provide a method for hydrolyzing plant biomass using a carbon catalyst, which contains an oligomer having a glucose polymerization degree (G) of 3 or more without performing complicated control as in Patent Document 6. An object of the present invention is to provide a method for producing cellooligosaccharides with high yield and high selectivity.

The present inventors have found that in order to selectively obtain an oligomer having a degree of polymerization (G) of glucose of 3 or more at a high yield by hydrolysis of cellulose, G3 or more produced by sequential depolymerization of cellulose We considered that it would be effective to quickly put the oligomer in an environment where it would not depolymerize any more (to release it from the carbon catalyst system), and conducted extensive research. As a result, a column (reaction vessel) filled with a mixture of carbon catalyst and plant biomass as a fixed bed is circulated with heated water under conditions where the cellulose component becomes an oligomer of G3 or higher, and the produced oligomer of G3 or higher is produced. The present inventors have found that the aqueous solution containing the catalyst is released from the catalyst system and the target cellooligosaccharide can be obtained in high yield (high selectivity), leading to the completion of the present invention.

That is, the present invention relates to the following methods for producing cellooligosaccharides [1] to [7].
[1] Heated water is passed through a reaction vessel filled with a mixture of a carbon catalyst and plant biomass as a fixed bed to hydrolyze cellulose in the biomass to obtain cellooligosaccharides having a glucose polymerization degree of 3 or higher. A method for producing cellooligosaccharide, characterized by:
[2] The method for producing cellooligosaccharide according to the above item 1, wherein the temperature of the heating water is 180 to 240°C and the reaction residence time is 20 to 600 seconds.
[3] The method for producing cellooligosaccharide according to the above item 1 or 2, wherein the heated water has a linear velocity (LV) of 0.4 to 5.0 m/Hr and a space velocity (SV) of 5 to 100/Hr.
[4] The method for producing cellooligosaccharide according to any one of [1] to [3] above, wherein the carbon catalyst and the plant biomass raw material are mixed in advance and pulverized at the same time, and the mixture is used as a fixed bed.
[5] The carbon catalyst according to any one of the preceding items 1 to 4, wherein the carbon catalyst is one or more selected from the group consisting of alkali-activated activated carbon, steam-activated activated carbon, chemical-activated activated carbon, and mesoporous carbon. A method for producing a cellooligosaccharide.
[6] The method for producing cellooligosaccharide according to any one of [1] to [5] above, wherein the carbon catalyst is an air-oxidized carbon catalyst.
[7] The method for producing cellooligosaccharide according to any one of the above items 1 to 6, wherein a mixture of the carbon catalyst and the plant biomass further mixed with silica is used as a fixed bed.

According to the present invention, cellooligosaccharides containing oligomers having a degree of polymerization of glucose of 3 or more can be produced from plant biomass with high yield and high selectivity using a carbon catalyst.

An outline of a reaction system (experimental apparatus) used in Examples is shown.

Preferred embodiments of the method of the present invention are described below. It should be noted that the embodiments described below are representative examples of the present invention, and the present invention is not limited to them, and the scope of the present invention should not be construed narrowly.

[Plant biomass (solid substrate)]
Biomass generally refers to "renewable organic resources derived from living organisms excluding fossil resources", but "vegetable biomass" (hereinafter sometimes referred to as solid substrate) used in the present invention. is biomass mainly containing cellulose and hemicellulose, such as rice straw, wheat straw, sugar cane straw, rice husk, bagasse, hardwood, bamboo, softwood, kenaf, furniture waste, construction waste, waste paper, and food residue.

The plant biomass may be purified or not purified. Refined materials are subjected to alkali steaming, alkaline sulfite steaming, neutral sulfite steaming, alkaline sodium sulfide steaming, ammonia steaming, etc., followed by solid-liquid separation and washing with water for delignification. Examples include those containing cellulose. Further, industrially prepared cellulose or the like may be used.
Plant biomass may contain ash such as silicon, aluminum, calcium, magnesium, potassium, and sodium derived from raw materials as impurities.

Plant biomass can be dry or wet, and can be crystalline or amorphous. It is desirable to pulverize the plant biomass prior to the reaction. The pulverization increases the contact with the carbon catalyst and promotes the hydrolysis reaction. Therefore, the shape and size of the plant biomass are preferably suitable for pulverization. As such a shape and size, for example, powder having a particle size of 20 to 1000 μm can be mentioned.

[Carbon catalyst]
The carbon catalyst is not particularly limited as long as it can catalyze the hydrolysis of plant biomass, but is typified by β-1,4 glycosidic bonds between glucose forming cellulose, which is the main component. A carbon material having the activity of hydrolyzing the glycosidic bond that is formed is preferred.

Carbon materials include, for example, activated carbon, carbon black, graphite, and air-oxidized wood flour. These carbon materials may be used alone or in combination of two or more. The shape of the carbon material is preferably porous and/or fine particles in terms of improving reactivity by increasing the contact area with the substrate, and in terms of promoting hydrolysis by developing acid sites. A carbon material having a functional group such as a phenolic hydroxyl group, a carboxyl group, a sulfo group, or a phosphoric acid group on its surface is preferred.

Examples of porous carbon materials having functional groups on their surfaces include woody materials such as coconut shells, eucalyptus, bamboo, pine, walnut shells, and bagasse, coke, phenol, etc., which are treated at high temperatures using gases such as water vapor, carbon dioxide, and air. Activated carbon prepared by a method of treatment (physical method) or a method of high-temperature treatment using chemicals such as alkali and zinc chloride (chemical method) can be mentioned. Furthermore, carbon materials obtained by uniformly heating wood materials and activated carbon in the presence of air (air oxidation treatment) are also included.

It is preferable to use steam-activated activated carbon, chemical-activated activated carbon, air-oxidized wood flour, air-oxidized steam-activated activated carbon, and air-oxidized chemical-activated activated carbon from the viewpoint of high yield of oligosaccharides with a degree of polymerization higher than cellotriose.

[Pulverization of plant biomass]
Cellulose, which is the main component of plant biomass, exhibits crystallinity when two or more cellulose molecules are bound by hydrogen bonding. In the present invention, cellulose having such crystallinity can be used as it is as a raw material, but it is preferable to use cellulose whose crystallinity has been reduced by subjecting it to a crystallinity-reducing treatment. The cellulose with reduced crystallinity may be one in which crystallinity has been partially reduced, or crystallinity has been completely or almost completely eliminated. The type of crystallinity-reducing treatment is not particularly limited, but a crystallinity-reducing treatment capable of breaking the hydrogen bonds and at least partially generating single-stranded cellulose molecules is preferred. By using cellulose as a raw material that contains at least partially single-stranded cellulose molecules, the efficiency of hydrolysis can be greatly improved.

Examples of methods for physically breaking hydrogen bonds between cellulose molecules include pulverization. The pulverizing means is not particularly limited as long as it has a function of pulverizing. For example, the system of the pulverizing apparatus may be either dry or wet, and the pulverizing system of the apparatus may be either batch type or continuous type. Additionally, the comminution force of the device can be anything from impact, compression, shear, friction, and the like.

Equipment used for pulverization includes rolling ball mills such as pot mills, tube mills, and conical mills, vibration ball mills such as circular vibrating mills, orbital vibrating mills, and centrifugal mills, agitation tank mills, annular mills, circulation mills, and tower types. Stirring mills such as pulverizers, jet pulverizers such as swirling jet mills, impingement type jet mills, fluidized bed jet mills, wet type jet mills, mills (grinders), shear mills such as ong mills, mortars , colloid mills such as stone mills, hammer mills, cage mills, pin mills, disintegrators, screen mills, turbo mills, centrifugal classifier mills, and other types of crushers that employ rotation and revolution motion. A planetary ball mill and the like can be mentioned.

The reaction of hydrolyzing plant biomass using a carbon catalyst is a reaction between a solid substrate and a solid catalyst, and contact between the substrate and the catalyst is rate-limiting. Mixing and pulverizing at the same time is effective.
In addition to mixing, the simultaneous milling treatment can serve as a pretreatment to reduce the crystallinity of the substrate. From that point of view, the grinding equipment to be used is preferably a rolling ball mill, a vibrating ball mill, a stirring mill, or a planetary ball mill, which are used for pretreatment to reduce the crystallinity of the substrate. Stirred tank mills and planetary ball mills are more preferred. Furthermore, since a raw material with a high bulk density obtained by simultaneous pulverization of the solid catalyst and the solid substrate tends to have higher reactivity, the crushed solid catalyst and the pulverized solid substrate are forced to bite into each other. It is more preferable to use a tumbling ball mill, a stirring mill, or a planetary ball mill to which a strong force is applied.

The average particle diameter after fine pulverization (cumulative median diameter (median diameter): The cumulative curve obtained by setting the total volume of the powder group as 100% is The particle diameter (D50) at the 50% point is 1 to 100 μm, preferably 1 to 30 μm, more preferably 1 to 20 μm, from the viewpoint of further enhancing reactivity.
If the raw material to be pulverized has a large particle size, it is preferable to perform a preliminary pulverization treatment before fine pulverization in order to perform pulverization efficiently. Preliminary crushing processes include, for example, coarse crushers such as shredders, jaw crushers, gyratory crushers, cone crushers, hammer crushers, roll crushers, and roll mills, stamp mills, edge runners, cutting and shearing mills, rod mills, autogenous crushers and It can be carried out using a medium grinder such as a roller mill. The treatment time of the raw material is not particularly limited as long as the raw material is uniformly pulverized after the treatment.

The ratio of the carbon catalyst to the solid substrate is not particularly limited either when the substrate is separately pulverized or when the substrate and the catalyst are pulverized simultaneously, but the hydrolysis efficiency during the reaction, the substrate after the reaction From the viewpoint of residue reduction and recovery rate of produced sugar, the carbon catalyst is preferably 1 to 100 parts by mass, more preferably 2 to 50 parts by mass, even more preferably 5 to 30 parts by mass, with respect to 100 parts by mass of the solid substrate. 20 parts by weight is particularly preferred.

[Mixing of silica]
When the pulverized carbon catalyst and solid substrate are packed into the reaction vessel, it is preferable to mix them with silica before packing. Since the pulverized carbon catalyst and solid substrate are fine powders, if they are directly filled into the reaction vessel, the flow of water in the reaction vessel is impeded. By mixing silica with the carbon catalyst and the solid substrate and filling them, the flow path of water in the reaction vessel can be ensured, and the pressure drop in the reaction vessel can be alleviated. The type of silica to be used is not particularly limited, and crystalline silica such as quartz may be used, or amorphous silica may be used.

The amount of silica to be mixed with respect to the total amount of the carbon catalyst and the solid substrate is preferably such that the mass ratio (carbon catalyst + solid substrate: silica) is 1:0.1 to 1:10, preferably 1:0.5. An amount of 1:5 is more preferred, and an amount of 1:0.7 to 1:2 is even more preferred.
The method of mixing silica is not particularly limited, but for example, a method of putting the co-pulverized carbon catalyst and solid substrate into a vial, adding silica, and mixing with a spatula until the silica is uniformly dispersed can be mentioned.
The substance to be mixed with the carbon catalyst and solid substrate is not limited to silica, and other inert particulate substances may be used. Substitutes for silica include, for example, zirconia, stainless steel, and glass beads.

[Hydrolysis reaction]
The hydrolysis reaction of using plant biomass as a substrate to produce cellooligosaccharides containing oligomers with a degree of polymerization of glucose of 3 or higher is carried out by simultaneously pulverizing the solid substrate and the carbon catalyst as described above, preferably with the solid substrate on the surface of the carbon catalyst. Fill the reaction vessel with the adsorbed mixture. More preferably, the co-milled solid substrate and carbon catalyst are charged into the reaction vessel in the form of a mixture mixed with silica. This reaction vessel is attached to the (semifluidic) reaction system shown schematically in FIG.

The heating unit 3 is a device that causes heated water to flow through the reaction vessel 4 to perform a hydrolysis reaction. A hydrolysis reaction can be performed under the conditions described later.
The cooling unit 6 is a device for cooling the cellooligosaccharide-containing aqueous solution flowing out from the heating unit.
The pressure of the back pressure regulator 5 is preferably 0.7-50 MPa, more preferably 0.8-30 MPa, and even more preferably 1-15 MPa.

Heated water is passed through the reaction vessel under the condition that the cellulose in the biomass is mainly hydrolyzed to cellooligosaccharides of G3 or higher. G3 or higher cellooligosaccharides produced in the reaction exit the reaction vessel system in a state of being dissolved in heated water (thus, to be released from the catalyst system). Therefore, cellooligosaccharides of G3 or higher can be obtained in a stable yield.

Cellooligosaccharides having a degree of polymerization (G) of 3 or more are produced by the hydrolysis reaction of the present invention. The degree of polymerization (G) of the resulting oligosaccharide may be, for example, 3-15, 5-14, or 7-13. It is preferably 3-10, more preferably 4-9, still more preferably 5-8. When the degree of polymerization (G) of the oligosaccharide is within the range of 3 to 10, the solubility in water is high and the recovery is easy.

The conditions under which cellulose is mainly hydrolyzed to cellooligosaccharides of G3 or higher will be described in detail below.

The reaction vessel used for the hydrolysis reaction is not particularly limited, and commercially available tubes can be used, for example. As for the size of the tube, the length and inner diameter can be appropriately selected and used according to the purpose. Assuming that the length of the reaction vessel is L and the inner diameter is D, the ratio (L/D) between the length L and the inner diameter D is preferably 1-100, more preferably 2-50, and even more preferably 3-30.
The method of filling the reaction vessel with the solid substrate and the carbon catalyst is not particularly limited, but as described above, a mixture of the solid substrate, carbon catalyst and silica can be prepared in advance and filled into the reaction vessel. The filling rate of these mixtures in the reaction vessel is preferably 80-100%, more preferably 90-100%, and even more preferably 95-100%.

The temperature of the heated water passed through the fixed bed is 170-250°C, preferably 180-240°C. The temperature of the heating water is more preferably 180°C to 230°C, still more preferably 190°C to 220°C, and particularly preferably 190°C to 210°C.
The method of heating the water flowing through the fixed bed is not particularly limited, but for example, the reaction vessel and the flow path before connecting to the reaction vessel can be heated by a heater.

The linear velocity (LV) of heated water flowing through the fixed bed is preferably 0.4 to 5.0 m/Hr. Linear velocity (LV) is more preferably 0.5 to 4.5 m/Hr, still more preferably 0.8 to 4.0 m/Hr, particularly preferably 2.0 to 4.0 m/Hr.
Linear velocity (LV) can be calculated by the following formula.
LV (m/Hr) = {(flow rate (cm ³ /min))/(cross-sectional area of reaction vessel (cm ² ))} x 60/100

The space velocity (SV) of the heated water flowing through the fixed bed is preferably 5 to 100/Hr. Space velocity (SV) is more preferably 10 to 90/Hr, still more preferably 20 to 80/Hr, particularly preferably 50 to 80/Hr.
Space velocity (SV) can be calculated by the following formula.
SV (1/Hr)={(flow rate (cm ³ /min))/(volume of reaction vessel (cm ³ ))}×60

Note that hydrolysis is affected by pH. In the present invention, the hydrolysis reaction can be carried out under conditions of pH 2 to 9. Preferably, heated water is passed directly through the reaction vessel without adjusting the pH.

The residence time of the heated water in the reaction vessel (hereinafter referred to as "reaction residence time") is preferably 20 to 600 seconds. The reaction residence time is more preferably 20 to 400 seconds, still more preferably 30 to 300 seconds, particularly preferably 30 to 100 seconds.

The reaction residence time can be calculated by the following formula.
(Reaction residence time (seconds)) = {(Vol _R -Vol _S )/(flow rate (cm ³ /min))} x 60
Here, Vol _R indicates the volume of the reaction vessel (cm ³ ) and Vol _S indicates the volume of the sample (cm ³ ). Vol _S can be calculated by the following formula.
Vol _S = Wt _S /ρ _S
Here, Wt _S indicates the mass (g) of the sample-silica mixture, and ρ _S indicates the true density (g/cm ³ ) of the sample-silica mixture.

Note that the true density ρ _S can be obtained by the following method. A volume of the sample-silica mixture is placed in a graduated cylinder and water is added until the water level is higher than the top surface of the solid. The volume of added water (cm ³ ) is obtained by dividing the mass (g) of added water by the density of water (1 g/cm ³ ), and the true density ρ _S (g/cm ³ ) is calculated by the following formula. can do.
ρ _S = (mass of mixture (g))/{(volume measured in graduated cylinder (cm ³ ))−(volume of added water (cm ³ ))}

The method for producing cellooligosaccharides of the present invention may further include other steps. For example, it can include a step of filtering a cellooligosaccharide-containing aqueous solution, a step of fractionating cellooligosaccharide, a step of purifying cellooligosaccharide, and the like.

Hereinafter, the effects of the present invention will be made clearer by way of examples. It should be noted that the present invention is not limited to the following examples, and can be modified as appropriate without changing the gist of the invention.

(1) Solid Substrate As the solid substrate, Avicel (crystalline fine powder cellulose manufactured by Merck) was pulverized by the following method (3) and used.

(2) Carbon Catalyst In Comparative Examples 2 to 5, BA50 (manufactured by Ajinomoto Fine-Techno Co., Inc.), which is steam-activated carbon, was pulverized by the following method (3) as the carbon catalyst. In Examples 1 to 4 and Comparative Example 1, BA50 was heated in an electric furnace at 425° C. for 10 hours to be air-oxidized (hereinafter abbreviated as air-oxidized BA50). used after being pulverized with

(3) Mixed pulverized raw material In Examples 1 to 4, 5.00 g of Avicel as a solid substrate and 0.771 g of air-oxidized BA50 as a carbon catalyst were mixed, and a planetary ball mill pulverizer (Fritsch P-6, alumina balls) was used to The pulverization treatment was performed at 500 rpm for 1 hour. After that, it was sieved to 150 μm or less. The obtained raw material is hereinafter abbreviated as mixed pulverized raw material.
In Comparative Example 1, pulverization was performed in the same manner as in Examples 1 to 4, except that the pulverization time was set to 2 hours.
In Comparative Examples 2-5, 10.00 g of Avicel as a solid substrate and 1.54 g of BA50 as a carbon catalyst were mixed and ball-milled at 60 rpm for 48 hours.

[Quantification of product]
The resulting cellooligosaccharide-containing aqueous solution was subjected to a high-performance liquid chromatograph manufactured by Shimadzu Corporation (column: Shodex (registered trademark) SH-1011, mobile phase: water 0.5 mL/min, column temperature: 50°C, detection: differential Glucose, cellobiose (G2), and cellooligosaccharides of G3 or higher were quantitatively analyzed by refractive index). The yield calculation formula is shown below.
Product yield (%) = {(substance amount of carbon in target component)/(substance amount of carbon in added cellulose)} x 100

[Calculation of linear velocity (LV), space velocity (SV), and reaction residence time]
Linear velocity (LV), space velocity (SV) and reaction residence time were calculated based on the formulas described in the specification. The reaction residence time is calculated with the true density ρ _S of 1.68 g/cm ³ .

Example 1:
0.175 g of the vacuum-dried mixed pulverized raw material was placed in a vial, and the same mass of silica (CARiACT Q30, Fuji Silysia Chemical Co., Ltd., particle size 75-150 μm) was added. The mixture was mixed with a spatula until the silica was uniformly dispersed to obtain a mixed pulverized raw material/silica mixture. The reaction vessel (5.15 cm long, 0.39 cm ID (made by cutting 0.25 inch OD Swagelok tubing)) was plugged at one end with quartz wool and all of the above mixed ground stock/silica mixture was placed in the reaction vessel. filled to After closing the other end of the reaction vessel with quartz wool, it was attached to the hydrolysis reaction system.
After mounting the reaction vessel, the pressure of the reaction system was set to 3 MPa with a back pressure regulator (Swagelok, KPB1N0G422P20000). Then the HPLC pump was started and the water flow rate was set to 0.75 mL/min. The pressure of the reaction system slowly increased to 3 MPa and was maintained for another 20 minutes after the liquid began to flow out of the outlet of the reaction system. After that, the heater (Asahi Rika Seisakusho, Ceramic Electric Tubular Furnace, ARF-30KC) was turned on and the temperature was set to 180°C. This time was defined as a recovery time of 0 minutes, and recovery of the cellooligosaccharide-containing aqueous solution was started.
Collection of the cellooligosaccharide-containing aqueous solution was terminated at the point of collection time of 40 minutes. The collected cellooligosaccharide-containing aqueous solution (30 mL) was filtered and then subjected to HPLC analysis to calculate the yield of the product. Table 1 shows the results.

Example 2:
The reaction was carried out in the same manner as in Example 1, except that the temperature of the heated water passing through the fixed bed (reaction temperature) was changed from 180°C in Example 1 to 200°C. Table 1 shows the results.

Example 3:
The reaction was carried out in the same manner as in Example 1, except that the temperature of the heated water passing through the fixed bed (reaction temperature) was changed from 180°C in Example 1 to 220°C. Table 1 shows the results.

Example 4:
The reaction was carried out in the same manner as in Example 1, except that the temperature of the heated water passing through the fixed bed (reaction temperature) was changed from 180°C in Example 1 to 240°C. Table 1 shows the results.

Comparative Example 1:
According to the description of Example 1 of Patent Document 5, the flow reaction of the mixed slurry of catalyst and substrate was carried out. Reaction conditions and results are shown in Table 2.

Comparative Example 2:
According to the description of Comparative Example 1 of Patent Document 6, a batch stirring reaction of the catalyst and the substrate was carried out. Reaction conditions and results are shown in Table 2.

Comparative Example 3:
A batch stirred reaction of catalyst and substrate was carried out as described in Example 1 of US Pat. The reaction conditions were the same as in Comparative Example 2, except that the reaction temperature was 200° C. and the reaction time was 3 minutes. Reaction conditions and results are shown in Table 2.

Comparative Example 4:
A batch stirred reaction of catalyst and substrate was carried out as described in Example 3 of US Pat. The reaction conditions were the same as in Comparative Example 2, except that the reaction temperature was 190° C. and the reaction time was 5 minutes. Reaction conditions and results are shown in Table 2.

Comparative Example 5:
A batch stirring reaction of catalyst and substrate was carried out as described in Example 4 of US Pat. The reaction conditions were the same as in Comparative Example 2, except that the reaction temperature was 180° C. and the reaction time was 20 minutes. Reaction conditions and results are shown in Table 2.

INDUSTRIAL APPLICABILITY According to the present invention, oligosaccharides of G3 or higher useful in the food and cosmetic industries can be produced with high yield and high selectivity by hydrolysis reaction of plant biomass using a carbon catalyst.

1 water 2 pump 3 heating unit 4 reaction vessel (cellulose/catalyst fixed bed)
5 Back pressure regulator 6 Cooling unit 7 Cellooligosaccharide-containing aqueous solution

Claims (5)

Heated water is passed through a reaction vessel filled with a mixture of carbon catalyst and plant biomass, and silica is further mixed as a fixed bed to hydrolyze the cellulose in the biomass, and the resulting glucose has a degree of polymerization of 3 or more. Characterized by obtaining cellooligosaccharides ,
The temperature of the heating water is 180 to 240° C., the reaction residence time is 20 to 600 seconds,
The heated water has a linear velocity (LV) of 0.4 to 5.0 m/Hr and a space velocity (SV) of 5 to 100/Hr.
A method for producing cellooligosaccharide. 2. The method for producing cellooligosaccharide according to claim 1, wherein the mixture of the carbon catalyst and the plant biomass is a mixture obtained by pre-mixing the carbon catalyst and the plant biomass raw material and pulverizing them simultaneously. The method for producing cellooligosaccharide according to claim 2, wherein the plant biomass raw material is powder having a particle size of 20 to 1000 µm. The cellooligosaccharide according to any one of claims 1 to 3 , wherein the carbon catalyst is one or more carbon catalysts selected from the group consisting of alkali-activated activated carbon, steam-activated activated carbon, chemical-activated activated carbon, and mesoporous carbon. manufacturing method. The method for producing cellooligosaccharide according to any one of claims 1 to 4 , wherein the carbon catalyst is an air-oxidized carbon catalyst.

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