JP2020045305A - Methods for producing cellooligosaccharide - Google Patents

Abstract

To provide methods for hydrolyzing plant biomass using a carbon catalyst which allows the production of cellooligosaccharide comprising oligomers of which glucose polymerization degree (G) is 3 or more with high yield and high selectivity.SOLUTION: Disclosed herein is a method for producing cellooligosaccharide, the method comprising: mixing a carbon catalyst and a plant biomass to fill a column (a reaction vessel) as a fixed bed; passing heated water through the column to hydrolyze cellulose in the biomass; and then collecting produced cellooligosaccharaides of which glucose polymerization degree (G) is 3 or more.SELECTED DRAWING: None

Description

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

Cellooligosaccharides are short-chain linear polymers in which glucose is polymerized by β-1,4 bonds, and have functions such as moisturizing properties, suppression of stickiness, imparting of taste, reduction of starch aging, suppression of protein denaturation, and the like. 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 good bacteria in the human digestive tract (Non-patent Document 1). It has been reported that when administered at low concentrations, it acts as an inducer to activate the plant's immune defense ability and improves crop yield (Non-Patent Document 2).
In particular, cellooligosaccharides having a degree of polymerization of glucose of about 3 to 8 exhibit appropriate solubility in water, and are expected to have greater sustainability of the above functions and to impart new functions.

  Currently, cellooligosaccharides used industrially are produced by an enzymatic reaction, but the main component is glucose and dimer cellobiose, and almost no oligomers higher than trimeric cellotriose are contained. JP 2009-189293 A; Patent Document 1).

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

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

  The present inventors have disclosed a method for continuously obtaining mainly glucose as a product by performing a hydrothermal reaction by continuously passing a slurry of vegetable biomass and a carbon catalyst through a reaction solution flowing pipe (particularly, US Pat. JP 2017-109187 A; Patent Document 5). Patent Document 5 produces cellooligosaccharides of G2 or more depending on reaction conditions, but does not disclose the yield and selectivity of oligosaccharides of G3 or more.

  In addition, the present inventors, in a hydrolysis reaction of vegetable biomass using a carbon catalyst, a temperature time in a range of 170 to 230 ° C. in a graph showing a relationship between a reaction temperature (vertical axis) and a reaction time (horizontal axis). It discloses a method for producing a cellooligosaccharide containing an oligomer of G3 to G6 by controlling the product to a specific range so as to cause a hydrothermal reaction (WO 2017/104687 pamphlet; Patent Document 6). .

JP 2009-189293 A International Publication No. 2012/128055 pamphlet JP 2006-320261 A Japanese Patent No. 4604194 JP 2017-109187 A WO 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 comprises an oligomer having a polymerization degree (G) of glucose of 3 or more without performing complicated control as in Patent Document 6. It is an object of the present invention 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 polymerization degree (G) of glucose of 3 or more in a high yield by hydrolysis of cellulose, G3 or more produced by depolymerization of cellulose sequentially is used. We thought that it would be effective to place the oligomer in an environment that would not promptly depolymerize it further (release from the carbon catalyst system). As a result, the heated oligomer is passed through a column (reaction vessel) filled with a mixture of the carbon catalyst and the vegetable biomass as a fixed bed under conditions where the cellulose component becomes an oligomer of G3 or more, whereby the oligomers of G3 or more are produced. The present inventors have found that the aqueous solution containing the solution is released from the catalyst system and that the target cellooligosaccharide can be obtained in high yield (high selectivity), and have completed the present invention.

That is, the present invention relates to the following methods for producing cellooligosaccharides [1] to [7].
[1] Heated water is allowed to flow through a reaction vessel filled with a mixture of a carbon catalyst and a vegetable biomass as a fixed bed to hydrolyze cellulose in the biomass to obtain a cellooligosaccharide having a degree of polymerization of glucose of 3 or more. A method for producing a cellooligosaccharide, comprising:
[2] The method for producing cellooligosaccharides according to the above item 1, wherein the temperature of the heated water is 180 to 240 ° C and the reaction residence time is 20 to 600 seconds.
[3] The method for producing a cellooligosaccharide according to the above item 1 or 2, wherein the linear velocity (LV) of the heated water is 0.4 to 5.0 m / Hr and the space velocity (SV) is 5 to 100 / Hr.
[4] The method for producing a cellooligosaccharide according to any one of the above items 1 to 3, wherein a mixture obtained by previously mixing and simultaneously pulverizing the carbon catalyst and the plant biomass raw material is used as a fixed bed.
[5] The method according to any one of items 1 to 4, wherein the carbon catalyst is one or more carbon catalysts selected from the group consisting of alkali-activated activated carbon, steam-activated activated carbon, drug-activated activated carbon, and mesoporous carbon. A method for producing cellooligosaccharide.
[6] The method for producing a cellooligosaccharide according to any one of the above items 1 to 5, wherein the carbon catalyst is a carbon catalyst subjected to an air oxidation treatment.
[7] The method for producing a cellooligosaccharide according to any one of the above items 1 to 6, wherein a mixture obtained by further mixing silica with the carbon catalyst and the plant biomass is used as a fixed bed.

  ADVANTAGE OF THE INVENTION According to this invention, cellooligosaccharide containing the oligomer whose glucose degree of polymerization is 3 or more can be manufactured with high yield and high selectivity from vegetable biomass using a carbon catalyst.

The outline of the reaction system (experimental apparatus) used in the examples is shown.

  Hereinafter, preferred embodiments of the method of the present invention will be described. The embodiments described below are representative examples of the present invention, and the present invention is not limited thereto, and the scope of the present invention should not be construed as being narrow.

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

Vegetable biomass may be used after being subjected to purification treatment or not. As those that have been refined, alkaline sulphite, alkaline sulphite sulphate, neutral sulphite sulphate, alkaline sodium sulphide sulphate, ammonia sulphate, etc., then solid-liquid separation and washing with water, then delignification treatment Those containing cellulose are exemplified. Furthermore, cellulose prepared industrially may be used.
Vegetable biomass may contain ash, such as silicon, aluminum, calcium, magnesium, potassium, and sodium, derived from raw materials as impurities.

  Vegetable biomass may be dry or wet, crystalline or non-crystalline. It is desirable to grind the plant biomass prior to the reaction. The pulverization increases the contact with the carbon catalyst and promotes the hydrolysis reaction. Therefore, it is preferable that the shape and size of the plant biomass be suitable for pulverization. Examples of such a shape and size include a powder having a particle size of 20 to 1000 μm.

[Carbon catalyst]
The carbon catalyst is not particularly limited as long as it can catalyze the hydrolysis of vegetable biomass, and is typically a β-1,4 glycosidic bond between glucose forming cellulose as a main component. A carbon material having an activity of hydrolyzing a glycoside bond to be formed is preferable.

  Examples of the carbon material include activated carbon, carbon black, graphite, and air-oxidized wood powder. 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 that the reactivity is improved by increasing the contact area with the substrate, and in terms of promoting acid hydrolysis by expressing acid sites, A carbon material having a functional group such as a phenolic hydroxyl group, a carboxyl group, a sulfo group, and a phosphate group on its surface is preferable.

  As porous carbon materials having functional groups on the surface, wood materials such as coconut husk, eucalyptus, bamboo, pine, walnut gala, bagasse, coke, phenol, etc., are heated at high temperatures using gases such as steam, carbon dioxide, air, etc. Activated carbon prepared by a treatment method (physical method) or a high-temperature treatment method using a chemical such as alkali or zinc chloride (chemical method) is exemplified. Further, there may also be mentioned a carbon material obtained by uniformly heating a woody material or activated carbon in the presence of air (air oxidation treatment).

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

[Pulverization of vegetable biomass]
Cellulose, which is a main component of plant biomass, exhibits crystallinity in which two or more cellulose molecules are bonded by hydrogen bonds. In the present invention, such a cellulose having crystallinity can be used as a raw material as it is, but it is preferable to use a cellulose whose crystallinity has been reduced by performing a crystallinity reduction treatment. The cellulose having reduced crystallinity may be one having partially reduced crystallinity or one having been completely or almost completely eliminated. The type of the crystallinity reduction treatment is not particularly limited, but is preferably a crystallinity reduction treatment capable of at least partially generating single-chain cellulose molecules by cutting the hydrogen bond. By using a cellulose containing at least partially a single-chain cellulose molecule as a raw material, the efficiency of hydrolysis can be significantly improved.

  A method of physically breaking hydrogen bonds between cellulose molecules includes, for example, a pulverization treatment. The pulverizing means is not particularly limited as long as it has a function of pulverizing. For example, the pulverizing apparatus may be either a dry type or a wet type, and the pulverizing system of the apparatus may be either a batch type or a continuous type. Further, any crushing force of the device such as impact, compression, shear, friction and the like can be used.

  Apparatuses used for the pulverizing process include rolling ball mills such as pot mills, tube mills, and conical mills, vibrating ball mills such as circular vibrating mills, rotating vibrating mills, centrifugal mills, stirring tank mills, annular mills, flow mills, and tower mills. Agitation mills such as pulverizers, swirling type jet mills, collision type jet mills, fluidized bed type jet mills, jet type pulverizers such as wet type jet mills, crushers (crushers), shearing mills such as ang mills, mortars , Impact mills such as colloid mills such as stone, hammer mills, cage mills, pin mills, disintegrators, screen mills, turbo mills, centrifugal classifier mills, and other types of mills that employ rotation and revolution. Planetary ball mills 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 the contact between the substrate and the catalyst is rate-determining. It is effective to carry out mixing and simultaneous pulverization.
The simultaneous pulverization can serve as a pre-treatment for reducing the crystallinity of the substrate in addition to the mixing. From that viewpoint, the crushing device used is preferably a rolling ball mill, a vibrating ball mill, a stirring mill, or a planetary ball mill, which is used in a pretreatment for lowering the crystallinity of the substrate, and is classified into a pot mill and a stirring mill classified as a rolling ball mill. A stirred tank mill and a planetary ball mill are more preferable. Furthermore, since the bulky raw material obtained by simultaneously pulverizing the solid catalyst and the solid substrate tends to have higher reactivity, a compressive force such that the pulverized material of the solid catalyst and the pulverized material of the solid substrate bite into each other. It is more preferable to use a rolling ball mill, a stirring mill, or a planetary ball mill, which strongly adds to the temperature.

The raw material obtained by simultaneously pulverizing the substrate and the solid substrate obtained by separately pulverizing the substrate has an average particle diameter after the fine pulverization (cumulative median diameter (median diameter): the cumulative curve obtained by assuming the total volume of the powder group as 100%). The particle diameter (D50) at the point of 50% is 1 to 100 μm, preferably 1 to 30 μm, more preferably 1 to 20 μm, from the viewpoint of further increasing the reactivity.
When the raw material to be pulverized has a large particle size, it is preferable to perform a preliminary pulverization before the pulverization in order to perform the pulverization efficiently. Preliminary pulverization processing includes, for example, a shredder, a jaw crusher, a gyre crusher, a cone crusher, a hammer crusher, a roll crusher, a rough crusher such as a roll mill, a stamp mill, an edge runner, a cutting / shear mill, a rod mill, a self-crushing mill and It can be carried out using a medium crusher such as a roller mill. The processing time of the raw material is not particularly limited as long as the raw material is uniformly pulverized after the processing.

  The ratio of the carbon catalyst to the solid substrate is not particularly limited in both the case where the substrate is crushed individually and the case where the substrate and the catalyst are crushed 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, still more preferably 5 to 30 parts by mass, and more preferably 10 to 30 parts by mass, based on 100 parts by mass of the solid substrate. 20 parts by weight are particularly preferred.

[Mixing of silica]
When the pulverized carbon catalyst and the solid substrate are charged into a reaction vessel, it is preferable to mix them with silica and fill them. Since the pulverized carbon catalyst and the solid substrate are fine powders, if they are directly charged into the reaction vessel, the flow of water in the reaction vessel is hindered. By mixing and filling the silica with the carbon catalyst and the solid substrate, a flow path of water in the reaction vessel is secured, and a decrease in pressure in the reaction vessel can be reduced. The type of silica used is not particularly limited, and crystalline silica such as quartz or non-crystalline silica may be used.

The mixing amount of silica is preferably from 1: 0.1 to 1:10 in mass ratio (carbon catalyst + solid substrate: silica) to the total amount of the carbon catalyst and the solid substrate, and preferably 1: 0.5. An amount of １ ： 1: 5 is more preferable, and an amount of ０．７1: 0.7-1: 2 is more preferable.
The method of mixing the silica is not particularly limited, and examples thereof include a method in which the simultaneously ground carbon catalyst and the solid substrate are placed in a vial, silica is added, and the mixture is mixed with a spatula until the silica is uniformly dispersed.
The substance to be mixed with the carbon catalyst and the solid substrate is not limited to silica, and another inert particulate substance may be used. As a substance that substitutes for silica, for example, zirconia, stainless steel, glass beads, and the like can be given.

[Hydrolysis reaction]
The hydrolysis reaction to produce cellooligosaccharides containing an oligomer having a degree of polymerization of glucose of 3 or more using plant biomass as a substrate is preferably carried out by simultaneously grinding the solid substrate and the carbon catalyst to form a solid substrate on the surface of the carbon catalyst. The reaction mixture is filled in the state of the adsorbed mixture. More preferably, the co-ground solid substrate and carbon catalyst are charged to the reaction vessel in a mixture with silica. The reaction vessel is attached to a (semi-fluid) reaction system as outlined in FIG.

The heating unit 3 is a device that circulates heated water through the reaction vessel 4 and performs a hydrolysis reaction. The hydrolysis reaction can be performed under the conditions described below.
The cooling unit 6 is a device that cools the cellooligosaccharide-containing aqueous solution flowing out of the heating unit.
The pressure of the back pressure regulator 5 is preferably 0.7 to 50 MPa, more preferably 0.8 to 30 MPa, and still more preferably 1 to 15 MPa.

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

  By the hydrolysis reaction of the present invention, cellooligosaccharides having a degree of polymerization (G) of 3 or more are produced. The degree of polymerization (G) of the resulting oligosaccharide may be, for example, 3 to 15, 5 to 14, or 7 to 13. Preferably it is 3-10, More preferably, it is 4-9, Still more preferably, it is 5-8. When the degree of polymerization (G) of the oligosaccharide is in the range of 3 to 10, the solubility in water is high and the oligosaccharide is easily collected.

  Hereinafter, the conditions under which cellulose is mainly hydrolyzed into cellooligosaccharides of G3 or more will be described in detail.

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

The temperature of the heated water flowing through the fixed bed is 170 to 250 ° C, preferably 180 to 240 ° C. The temperature of the heating water is more preferably 180 ° C to 230 ° C, further 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. For example, a reaction vessel and a flow path connected to the reaction vessel can be heated by a heater.

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

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

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

  The time during which the heated water stays in the reaction vessel (hereinafter, referred to as “reaction stay time”) is preferably from 20 to 600 seconds. The reaction residence time is more preferably 20 to 400 seconds, further preferably 30 to 300 seconds, and particularly preferably 30 to 100 seconds.

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

Note that the true density ρ _S can be obtained by the following method. A certain amount of the mixture of the sample and silica is placed in a measuring cylinder, and water is added until the water level is higher than the upper surface of the solid. The mass (g) of the added water is divided by the density (1 g / cm ³ ) of the water to determine the volume (cm ³ ) of the added water, and the true density ρ _S (g / cm ³ ) is calculated by the following equation. 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, the method may include a step of filtering a cellooligosaccharide-containing aqueous solution, a step of fractionating cellooligosaccharides, a step of purifying cellooligosaccharides, and the like.

  Hereinafter, the effects of the present invention will be made clearer by examples. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications without departing from the scope of the invention.

(1) Solid substrate As a solid substrate, avicel (crystalline fine powdered cellulose manufactured by Merck) that had been pulverized by the following method (3) was used.

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

(3) Mixed and crushed raw materials 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 crusher (Fritsch P-6, alumina balls) was used. The pulverization treatment was performed at 500 rpm for 1 hour. Then, it was sieved to 150 μm or less. The obtained raw material is hereinafter abbreviated as a mixed and crushed raw material.
In Comparative Example 1, the pulverization was performed in the same manner as in Examples 1 to 4, except that the pulverization time was 2 hours.
In Comparative Examples 2 to 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 obtained cellooligosaccharide-containing aqueous solution was subjected to high performance liquid chromatography 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 formula for calculating the yield is shown below.
Product yield (%) = {(amount of carbon in target component) / (amount of carbon in added cellulose)} × 100

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

Example 1
0.175 g of the vacuum-dried mixed and crushed raw material was placed in a vial, and the same mass of silica (Fuji Silysia Chemical Ltd., CARiACT Q30, particle size: 75 to 150 μm) was added. The mixture was mixed with a spatula until the silica was uniformly dispersed to obtain a mixture of the mixed and ground raw material / silica. One end of a reaction vessel (5.15 cm long, 0.39 cm inside diameter (prepared by cutting a Swagelok tube having an outside diameter of 0.25 inch)) is closed with quartz wool, and the above mixed ground material / silica mixture is entirely used as a reaction vessel. Was filled. After closing the other end of the reaction vessel with quartz wool, it was attached to a hydrolysis reaction system.
After installing the reaction vessel, the pressure of the reaction system was set to 3 MPa by a back pressure regulator (Swagelok, KPB1N0G422P20000). Next, the HPLC pump was started, and the flow rate of water was set at 0.75 mL / min. The pressure in the reaction system slowly increased to 3 MPa, and this state was maintained for another 20 minutes after the liquid started flowing out of the outlet of the reaction system. Then, the power of the heater (Asahi Rika Seisakusho, ceramic electric tube furnace, ARF-30KC) was turned on, and the temperature was set to 180 ° C. This time was set to 0 min, and the collection of the cellooligosaccharide-containing aqueous solution was started.
When the collection time was 40 minutes, the collection of the cellooligosaccharide-containing aqueous solution was completed. The collected cellooligosaccharide-containing aqueous solution (30 mL) was subjected to HPLC analysis after filtration, and the yield of the product was calculated. 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, a flow reaction of a mixed slurry of a catalyst and a substrate was performed. Table 2 shows the reaction conditions and results.

Comparative Example 2:
A batch stirring reaction of the catalyst and the substrate was performed according to the description of Comparative Example 1 of Patent Document 6. Table 2 shows the reaction conditions and results.

Comparative Example 3:
A batch stirring reaction of the catalyst and the substrate was performed as described in Example 1 of Patent Document 6. 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 in Comparative Example 2. Table 2 shows the reaction conditions and results.

Comparative Example 4:
A batch stirring reaction of the catalyst and the substrate was performed as described in Example 3 of Patent Document 6. The reaction conditions were the same as Comparative Example 2 except that the reaction temperature was 190 ° C. and the reaction time was 5 minutes. Table 2 shows the reaction conditions and results.

Comparative Example 5:
A batch stirring reaction of the catalyst and the substrate was performed as described in Example 4 of Patent Document 6. 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. Table 2 shows the reaction conditions and results.

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

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

Claims (7)

  Heating water is passed through a reaction vessel filled with a mixture of a carbon catalyst and a plant biomass as a fixed bed to hydrolyze cellulose in the biomass, thereby obtaining a cellooligosaccharide having a degree of polymerization of glucose of 3 or more. A method for producing cellooligosaccharides.   The method for producing cellooligosaccharide according to claim 1, wherein the temperature of the heated water is 180 to 240 ° C and the reaction residence time is 20 to 600 seconds.   The method for producing a cellooligosaccharide according to claim 1 or 2, wherein the linear velocity (LV) of the heated water is 0.4 to 5.0 m / Hr, and the space velocity (SV) is 5 to 100 / Hr.   The method for producing cellooligosaccharides according to any one of claims 1 to 3, wherein a mixture obtained by previously mixing and simultaneously pulverizing the carbon catalyst and the plant biomass raw material is used as a fixed bed.   The cellooligosaccharide according to any one of claims 1 to 4, wherein the carbon catalyst is at least one carbon catalyst selected from the group consisting of alkali-activated activated carbon, steam-activated activated carbon, drug-activated activated carbon, and mesoporous carbon. Manufacturing method.   The method for producing a cellooligosaccharide according to any one of claims 1 to 5, wherein the carbon catalyst is a carbon catalyst subjected to an air oxidation treatment.   The method for producing cellooligosaccharides according to any one of claims 1 to 6, wherein a mixture obtained by further mixing silica with the carbon catalyst and the plant biomass is used as a fixed bed.

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