JP3016419B2 - Method for producing glucose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for pretreating a cellulosic substance and a novel method for producing glucose from the pretreated material.

[0002]

2. Description of the Related Art Conventionally, there are an acid saccharification method and an enzymatic saccharification method as a method for producing glucose using a cellulosic material as a raw material, but none of them is industrially practiced. The acid saccharification method of a cellulosic substance is a dilute acid saccharification method of saccharifying a cellulosic substance using a dilute acid at a high temperature (200 ° C. or higher),
A method of saccharifying a cellulosic substance with concentrated sulfuric acid or the like is known.However, any of these methods hydrolyzes the cellulosic substance under extreme conditions. A decomposition reaction occurs, the saccharification rate is as low as about 50%, and it is necessary to remove decomposed products of glucose from the saccharified solution. In addition, there are various problems in using a saccharified solution as a carbon source for fermentation without removing the decomposed product of glucose.

On the other hand, the enzymatic saccharification method can saccharify a cellulosic substance under mild conditions, but has a problem that the saccharification reaction speed is slow and a sufficient saccharification requires a long time. Further, there is a problem that the titer of a commercially available enzyme used for saccharification is low, and a sufficient amount of the enzyme is required for sufficient saccharification, so that the cost of the enzyme used is increased.

In order to improve such a problem, various techniques as described below have been proposed. (1) Japanese Patent Application Laid-Open No. 54-160755: Cellulose material is dissolved in cadoxene or a metal chelate caustic swelling solvent, and then the cellulose material is pretreated and recovered from the solvent. Dilute sulfuric acid is used for hydrolysis of the recovered material. Is used. (2) Japanese Patent Publication No. 57-53801; treating cellulose as a raw material in a mixed solution of concentrated hydrochloric acid and concentrated sulfuric acid to process the cellulose into cellulose which is easily decomposed into cellulase.

(3) JP-B-59-53040: A cellulose acetylation reaction is carried out in order to destroy the fine structure of cellulose, and cellulose is hydrolyzed using mineral acids and acetic acid as catalysts. (4) JP-A-2-295492; a cellulase is used for the hydrolysis reaction of cellulase, which is a cell having high reactivity and is selected from cellulose. (5) Japanese Patent Publication No. 8-2312; a wet pulp obtained by digesting a raw material containing natural lignocellulose and not drying after the digestion is converted into cellooligosaccharide and glucose produced during partial decomposition by the action of cellulase. The partial decomposition is advanced while continuously removing the reaction system from the outside by an ultrafiltration membrane.

[0006]

However, these techniques have the following problems. In the method (1), a heavy metal is used, and the reaction temperature is as high as 100 to 200 ° C. In the method (2), the cost of recovering the acid-resistant apparatus and the mixed acid becomes a problem. The method (3) requires an acetylation reaction, and has a problem that an acetylated derivative is mixed into the final product. In the method (4), it is necessary to selectively separate parenchyma cells, which are highly reactive cellulose-containing fibers. The method (5) requires a digester other than a paper maker, and the cooking cost is a problem. Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing glucose capable of mass-producing glucose at low cost.

[0007]

The above object is achieved by the present invention described below. That is, the present invention relates to amorphous cellulose or cellooligo obtained by vigorously stirring at a temperature of 30 to 60 ° C. in a state where a cellulose-based material is dissolved and / or swollen in phosphoric acid having a concentration of 70% by weight or more. A method for producing glucose, which comprises decomposing sugar with cellulase.

In general, a cellulosic substance has a crystalline portion and an amorphous portion, and the enzymatic hydrolysis reaction of the cellulosic material is easier in the latter than in the former. The former is considered to have a slow hydrolysis rate because of strong intramolecular and intermolecular hydrogen bonds.

According to the present invention, a cellulose-based material is dissolved and / or swelled in high-concentration phosphoric acid and stirred vigorously, whereby the synergistic effect of the chemical action of phosphoric acid and the physical action of stirring is used to produce cellulose. The cellulose-based material can be easily converted to amorphous cellulose or cellooligosaccharide by reducing the ratio of the crystallized portion of the system-based material to the maximum.

In this state, the reaction efficiency of cellulase is improved by allowing cellulase, which is a cellulolytic enzyme, to act, the amount of enzyme used for saccharification of cellulose can be reduced, and the reaction time required for saccharification can be shortened. As a result, the production cost of glucose can be significantly reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments of the present invention. Examples of the cellulosic substance used as a raw material in the present invention include agricultural waste such as old newspaper, magazine, corrugated cardboard, waste office paper, wood quality (wood chips, waste material), rice hull, bamboo, bagasse, straw, corn cob and the like. , Linters, cotton, pulp and waste pulp discharged from paper manufacturers. Among the above-mentioned cellulosic substances, particularly preferred in the present invention are old newspaper, linter, cotton and pulp.

In the present invention, first, the above-mentioned cellulosic substance is added to high-concentration phosphoric acid to dissolve and / or swell. As the high-concentration phosphoric acid to be used, 70% by weight or more of phosphoric acid is preferable, and 81 to 85% by weight or 92 to 97% by weight of phosphoric acid is suitable for the purpose of the present invention. The amount of the cellulosic substance added to the high concentration phosphoric acid is preferably in the range of about 5 to 20 parts by weight per 100 parts by weight of high concentration phosphoric acid. If the amount of the cellulosic substance is less than the above range, the economic efficiency is poor and the cost of recovering phosphoric acid is high. In addition, the viscosity of the phosphoric acid solution is low due to the low concentration of the cellulosic substance, and the shearing action at the time of stirring the mixture is insufficient, and the physical action is insufficient. On the other hand, if the addition amount of the cellulosic material exceeds the above range, it is difficult to liquefy the mixture, and it is also difficult to vigorously agitate, so that uniform amorphization or cellooligosaccharification of the cellulosic material takes a short time. I can't get it.

The stirring of the cellulosic substance added to the phosphoric acid is preferably performed at a temperature of about 30 to 60 ° C. for about 1 to 4 hours. At this time, the strong stirring of the mixture is
For example, for example, phosphoric acid at a concentration of 70% by weight,
Although the viscosity is about 10 centistokes (23 ° C.), 20 parts by weight of a cellulosic substance is added to 100 parts by weight of this phosphoric acid aqueous solution, and a connecting motor is used at 150 to 600 kW using a pulper used in a deinking process of waste paper. Means stirring while heating at the above temperature at a rotor rotation speed of 600 to 1000 RPM. Immediately after the addition of the cellulosic substance, the rotor (rotation speed) is kept low because the viscosity (viscosity) in the pulper is high, and the rotation of the rotor is increased if the viscosity (viscosity) in the pulper decreases while observing the progress.

In the present invention, glucose is produced by decomposing the amorphous cellulose or cellooligosaccharide obtained as described above with cellulase, but the reaction mixture cannot be hydrolyzed by cellulase as it is. After recovering the amorphous cellulose or cellooligosaccharide from the reaction mixture, enzymatic degradation with cellulase is performed.

As a method for recovering the above-mentioned amorphous cellulose or cellooligosaccharide from a high-concentration phosphoric acid solution, the following method can be mentioned. (1) The high-concentration phosphoric acid solution of amorphous cellulose or cellooligosaccharide is allowed to stand for 24 hours, and then the upper 80% by weight phosphoric acid solution is recovered and reused for pretreatment of the cellulosic substance. The remaining 20% by weight phosphoric acid solution is poured into distilled water with vigorous stirring. If the concentration of the amorphous cellulose or cellooligosaccharide is low, the precipitate becomes a gel, and if the concentration is high, it precipitates in a string, fibrous, or particulate form.In some cases, a fibrous form is obtained. During the treatment or after the pretreatment, the concentration of the amorphous cellulose or cellooligosaccharide in the reaction mixture is adjusted.

After the precipitation, the amorphous cellulose or cellooligosaccharide is recovered on a G3 glass filter after washing with distilled water. On the other hand, the filtrate is neutralized with calcium carbonate and the precipitated phosphate is removed by a G3 glass filter. Amorphous cellulose or cellooligosaccharide having a low molecular weight is dissolved in the filtrate. The above-obtained amorphous cellulose or cellooligosaccharide and the above-mentioned filtrate from which phosphate has been removed are combined to form a slurry solution, which is used for the subsequent saccharification reaction.

(2) After leaving the high-concentration phosphoric acid solution of the amorphous cellulose or cellooligosaccharide for 24 hours, the phosphoric acid solution is poured into distilled water with vigorous stirring. If the concentration of the amorphous cellulose or cellooligosaccharide is low, the precipitate becomes a gel, and if the concentration is high, it precipitates in a string, fibrous, or particulate form.In some cases, a fibrous form is obtained. During the treatment or after the pretreatment, the concentration of the amorphous cellulose or cellooligosaccharide in the reaction mixture is adjusted. This diluted phosphoric acid aqueous solution is a slurry solution containing precipitated amorphous cellulose or cellooligosaccharide and water-soluble low-molecular-weight amorphous cellulose or cellooligosaccharide. Phosphoric acid is extracted and removed from the slurry solution with n-butanol. The slurry solution from which phosphoric acid has been removed is used for the subsequent saccharification reaction.

The slurry solution as described above is preferably adjusted to pH
Adjust to about 4-6. The concentration of the slurry solution is about 5
A range of 15% by weight is preferred. Cellulase, which is a cellulolytic enzyme, is added to the slurry solution. The addition amount of cellulase is preferably in the range of about 1 to 15 parts by weight per 100 parts by weight of the solid content of the slurry solution.If the amount of cellulase is too small, the hydrolysis of amorphous cellulose or cellooligosaccharide is insufficient, On the other hand, too much cellulase is uneconomical. As the cellulase used in the present invention, any commercially available cellulase can be used.

The slurry solution to which cellulase was added was added to about 2
By stirring at a temperature of 0 to 60 ° C. for about 0.5 to 12 hours, amorphous cellulose or cellooligosaccharide is hydrolyzed and converted into glucose. Glucose from the aqueous glucose solution is separated according to a conventional method. By the above reaction, about 60 to 80 parts by weight of glucose is obtained per 100 parts by weight of the cellulosic material as the raw material, although it varies depending on the type of the cellulosic material used as the raw material. About 80 to 100 parts by weight of glucose is obtained per 100 parts by weight of crystalline cellulose or cellooligosaccharide.

[0020]

Next, examples of the method for producing glucose according to the present invention will be described. Example 1 100 g of an 85% phosphoric acid aqueous solution was added to 10 g of a commercially available cellulose powder (manufactured by Toyo Filter Paper, filter paper powder), and the mixture was stirred for 2 to 4 hours while maintaining the temperature at 40 ° C., and left overnight. The 80% phosphoric acid solution was removed from the upper end of the stirring vessel, and the remaining 20 g of the phosphoric acid solution was poured into distilled water with vigorous stirring. The precipitated amorphous cellulose or cellooligosaccharide was collected on a G3 glass filter after washing with distilled water. On the other hand, the filtrate was neutralized with calcium carbonate and the precipitated phosphate was removed with a G3 glass filter.

The amorphous cellulose or cellooligosaccharide thus obtained is combined with the filtrate from which the phosphate has been removed (the filtrate contains low-molecular-weight amorphous cellulose or cellooligosaccharide dissolved in water). (Containing sugar) to form a slurry solution, and the slurry solution was adjusted to pH 4.5 with an acetate buffer. Amorphous cellulose or cellooligosaccharide in the slurry solution was hydrolyzed by adding 0.5 g of a commercially available cellulase (origin of Tricoderma viride) to the slurry solution and stirring for 30 minutes. After the hydrolysis reaction solution was filtered through, for example, an ultrafiltration membrane, the filtrate was concentrated under reduced pressure to obtain 6.5 g of glucose.

Example 2 100 g of an 85% phosphoric acid aqueous solution was added to 10 g of commercially available cellulose powder (manufactured by Toyo Roshi Kaisha, filter paper powder), and the mixture was stirred for 2 to 4 hours while maintaining the temperature at 40 ° C., and allowed to stand overnight. The phosphoric acid solution was poured into distilled water with vigorous stirring. The diluted phosphoric acid aqueous solution contains water-insoluble amorphous cellulose or cellooligosaccharide and low molecular weight amorphous cellulose or cellooligosaccharide dissolved in water. Phosphoric acid is extracted and removed from this slurry solution with n-butanol. The phosphoric acid-removed slurry solution was adjusted to pH 5.5 using an acetate buffer.
Was adjusted. Amorphous cellulose or cellooligosaccharide in the slurry solution was hydrolyzed by adding 0.5 g of a commercially available cellulase (origin of Tricoderma viride) to the slurry solution and stirring for 30 minutes. After the hydrolysis reaction solution was filtered through, for example, an ultrafiltration membrane, the filtrate was concentrated under reduced pressure to obtain 8.5 g of glucose.

[0023]

According to the present invention as described above, there is provided a method for producing glucose which solves the problems of the prior art and enables mass production of glucose at low cost.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-42244 (JP, A) US Patent 3,542,580 (US, A) Science and Culture, vol. 50, no. 19, p265-266, 1984 (58) Field surveyed (Int. Cl. ⁷ , DB name) C08B 15/00

Claims (1)

(57) [Claims] (1) A cellulosic material having a concentration of 70% by weight or more.
30 to 6 in a state of being dissolved and / or swollen in phosphoric acid
A method for producing glucose, comprising decomposing amorphous cellulose or cellooligosaccharide obtained by vigorous stirring at a temperature of 0 ° C. with cellulase.