JP2007020555A - Method for hydrolyzing polysaccharide substance such as cellulose or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the most suitable method for efficiently producing a saccharide such as glucose, etc., from a substance containing polysaccharide such as cellulose, etc., with which pressurized hot water is used as a solvent and corrosion of an apparatus is controlled. <P>SOLUTION: The method for hydrolyzing a polysaccharide substance comprises bringing a substance containing polysaccharide such as cellulose, etc., into contact with pressurized hot water in the presence of an oxidizing agent and selectively and rapidly hydrolyzing the polysaccharide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for converting a polysaccharide-containing substance present in large quantities on the earth into a useful substance such as a monosaccharide in a short time and in a high yield. Furthermore, the present invention uses pressurized hot water as a solvent to selectively and efficiently hydrolyze a polysaccharide substance such as cellulose in a less corrosive environment, and the monosaccharide and monosaccharide are glucose / or oligosaccharide. In a high yield.

Conventional energy and environmental problems due to depletion of fossil resources and global warming are the most serious problems in the 21st century. In order to solve these problems, it is necessary to find abundant organic resources such as petroleum that are environmentally friendly. One of the most promising of these is biomass resources, and the one that makes up this biomass resource and boasts the largest amount on earth is cellulose.

Today, there is a greater expectation for cellulose than ever before. That is, in addition to the use of cellulose as a chemical industrial raw material, various technological developments aimed at the use as an energy resource have attracted attention. Among them, the production of glucose from cellulose is extremely important for the effective use of cellulose, and ethanol production from glucose, fermentation to lactic acid, and conversion to biodegradable polymers such as polylactic acid have received the most attention recently. .

However, there are basically three known methods for producing glucose from cellulose: acid hydrolysis, enzymatic hydrolysis, and recently developed hydrolysis using supercritical water. The method is also difficult to say as an effective method for producing glucose efficiently and in large quantities.

The acid hydrolysis method is divided into a dilute acid method and a concentrated acid method depending on the acid concentration. In the dilute acid method, both temperature and pressure are high, and there are problems such as equipment corrosion due to the added acid and removal of acid from the product. If the acid concentration is suppressed to avoid such inconvenience, the production rate of glucose decreases. There is a drawback. In the concentrated acid method, since the temperature and pressure are low, an inexpensive reactor material, such as glass fiber FRP, can be used, and the yield of glucose is high, but the reaction time is long and economically effective. There is a disadvantage that there is no recovery method.

The enzymatic hydrolysis method is not used as an industrial production technique because the reaction rate is slow and the price of the enzyme is high.

On the other hand, recently, in order to solve the above-mentioned problems, a method has been proposed in which cellulose is hydrolyzed using subcritical or supercritical water to produce oligosaccharide or monosaccharide glucose (Patent Document 1). And 2). This technology utilizes the characteristics of supercritical water and can completely decompose cellulose into oligosaccharides and monosaccharides in a treatment time of seconds or less. However, the yield of glucose was only around 20%. It has been found that this is because the oligosaccharides and monosaccharides produced by hydrolysis are converted into secondary products by various thermal decomposition reactions under high temperature reaction conditions.

In order to solve this cause, the inventors' research experiment has revealed that when the reaction temperature is 350 ° C. or higher, the ionic product of water decreases, so that free radical reactions such as thermal decomposition increase. As a result, the reducing end of the oligosaccharide and glucose are decomposed and converted into a fragmented product such as glycol aldehyde, and the yield of glucose decreases. In order to suppress these side reactions, a method for increasing the pressure has been proposed, but it has been found that the cost of the apparatus increases and the yield of glucose increases only slightly (see Patent Document 1).
JP-A-5-31000 Japanese Patent Laid-Open No. 10-327900

The present invention has been made under these circumstances, and promotes the hydrolysis reaction of polysaccharides, suppresses corrosion of the apparatus, and efficiently produces useful saccharides such as glucose from substances containing polysaccharides such as cellulose. The purpose is to provide a method to do this.

Means to solve the problem

In order to achieve the above object, the present invention relates to a method for hydrolyzing a polysaccharide material, characterized by adding an oxidant to the reaction in the presence of hydrolysis of the polysaccharide material with pressurized hot water.

According to the method for hydrolyzing a polysaccharide substance of the present invention, by adding an oxidant and coexisting, the hydrolysis of the polysaccharide substance is promoted, the corrosion of the apparatus is suppressed, and the yield of hydrolysis products such as glucose is increased. It is the main point that can be remarkably enhanced.

The polysaccharide substances targeted by the means of the present invention include hemicellulose, starch, chitin, chitosan and the like, lignocellulose and agricultural products containing these substances, as well as cellulose, which is a representative example of polysaccharides.

Although the oligosaccharide and / or monosaccharide can be produced by the method for hydrolyzing a polysaccharide substance of the present invention, it is preferable to produce a monosaccharide, particularly glucose in the present invention.

The oxidizing agent used in the hydrolysis method of the present invention preferably has an oxidation potential of 0 to 2 volts.

Further, the oxidizing agent is preferably one or more substances selected from silver, copper, ferric [Fe + 3], and a tin salt compound.

The silver, copper, ferric and tin salt compounds are preferably sulfates, nitrates, hydrochlorides and acetates.

Further, the oxidizing agent may be one or more substances selected from the group consisting of fluorine, chlorine, bromine and iodine.

The treatment temperature for hydrolysis is preferably in the range of 100 to 500 ° C., and the treatment pressure is preferably in the range of saturated vapor pressure to 50 MPa.

The invention's effect

As an effect of the present invention, two or more oxidizing agents can coexist in the pressurized hot water, which is very effective in reducing the required amount of oxidizing agent and improving the hydrolysis reaction rate.

In the present invention, by adding an oxidizing agent, side reactions can be suppressed, the yield can be increased, and a high effect not found in previous prior applications can be obtained.
There are three known methods for producing glucose from cellulose that have been performed so far, and the effects thereof will be described below.
(1) Glucose is produced by hydrolyzing cellulose using concentrated sulfuric acid (concentrated sulfuric acid method). However, this concentrated sulfuric acid method has been pointed out to be problematic in the treatment of sulfuric acid.
(2) Hydrolysis is performed using dilute sulfuric acid (0.1% or the like) at a temperature higher than (1) above (around 200 ° C.) (diluted sulfuric acid method). However, in this dilute sulfuric acid method, problems such as corrosion of sulfuric acid on equipment have been pointed out.
(3) The cellulose is decomposed using subcritical or supercritical water at 200 ° C. or higher without using an acid (supercritical water decomposition). However, this supercritical water splitting has many side reactions, and it has been pointed out that the yield is low.
Therefore, the present invention in which an oxidizing agent is added can exhibit an unprecedented effect.

The present invention provides a method of hydrolyzing a polysaccharide substance such as cellulose in the presence of an oxidizing agent using pressurized hot water to convert it into oligosaccharides and / or monosaccharides.

The theoretical basis for the action and effect of the oxidizing agent in the pressurized hot water has not yet been elucidated, but it is considered that the glucoside bond in the pressurized hot water is easily cleaved by the action of the oxidizing agent.

The polysaccharide substance that can be used in the present invention is not particularly limited, but is a natural polysaccharide such as cellulose, hemicellulose, starch, chitin, and chitosan. For example, wood, bamboo, kenaf, bagasse, rice straw, etc., which are lignocellulosic resources, and wood fibers, wood chips, veneer scraps, pulps, waste paper, etc., rice, wheat, corn Cereals such as potatoes, potatoes and sweet potatoes such as sweet potatoes, and biomass materials contained in general household waste. Among them, cellulose and cellulose-containing materials such as wood, pulp, and waste paper are more preferable from the viewpoint of the abundance of raw materials. Cellulose is also preferable in that a by-product derived from a non-sugar component such as lignin is hardly generated in the reaction product, and the separation step can be omitted. Although the form of these polysaccharide substances is not particularly limited, it is preferable to grind into a powder form in consideration of the processing speed and the uniformity of the processing.

According to the method of the present invention, polysaccharides such as cellulose can be converted into oligosaccharides and / or monosaccharides with high efficiency. Among them, glucose is a method for producing glucose, and many chemicals and polymer materials are used as glucose. It is also particularly preferable because it is also a raw material for bioenergy and the like.

The oxidizing agent is not particularly limited, but an oxidizing potential in the range of 0 to 2.0 volts is preferable. When the oxidation potential is 0 or less, the reaction promoting effect is low, and when the oxidation potential is 2 or more, the oxidation reaction is too intense and the amount of by-products tends to increase.

Specifically, the oxidizing agent is preferably one or more substances selected from silver, copper, ferric [Fe + 3], and a tin salt compound. As these salt compounds, sulfates, nitrates, hydrochlorides and the like are suitable.

In addition to the above-mentioned salt compounds, halogen elements such as fluorine, chlorine, bromine, and iodine are also effective.

Among them, ferric chloride, silver nitrate, copper chloride, or iodine is more preferable because the hydrolysis reaction promoting effect is particularly large.

Although the said oxidizing agent may be used individually by 1 type, you may use 2 or more types together.

The amount of the oxidant added varies depending on the type of oxidant, the reaction temperature, the molecular weight of the polysaccharide substance, and the degree of crystallinity, but 0.001 to 20 parts by weight is added to 100 parts by weight of the saccharide substance. preferable. 0.05-10 weight part is more preferable. When the addition amount is 0.001 part by weight or less, a sufficient effect tends not to be obtained, but when it is 20 parts by weight or more, there is a tendency that by-products increase.

In the present invention, when a polysaccharide or a polysaccharide-containing substance is hydrolyzed using pressurized hot water in the presence of an oxidizing agent and converted to an oligosaccharide or / and a monosaccharide, the method and apparatus are particularly suitable. There is no restriction | limiting, It can apply with a well-known method and apparatus. For example, a batch-type reaction method in which a polysaccharide substance, water, and an oxidizing agent are placed in an autoclave reactor and heated to react, or a fixed-bed reactor is filled with a polysaccharide substance, which contains a predetermined amount of an oxidizing agent. A fixed bed type reaction method in which pressurized hot water is continuously passed through to hydrolyze the polysaccharide and the produced reaction product flows out of the system together with the hot water, a slurry made of polysaccharide material, oxidizing agent, water, etc. For example, a flow-type reaction method in which the gas is continuously passed through the reactor. Among them, when a flow reaction method is used, the reaction time can be easily controlled, which is more preferable.

In the pressurized hot water treatment, the amount of pressurized hot water used for the polysaccharide substance is not particularly limited, and may be appropriately selected depending on the treatment method and apparatus. For example, in the case of a batch type processing apparatus, the pressurized hot water is 100 to 10,000 parts by weight with respect to 100 parts by weight of the polysaccharide, and in the case of a flow type processing apparatus, the pressurized hot water is 100 parts by weight of the polysaccharide. 300 to 10,000 parts by weight is preferred.

The pressurized hot water used in the present invention is used in a temperature range of 100 to 500 ° C. and a pressure saturated vapor pressure to 100 MPa. In this case, water in the range of temperature: 180 to 350 ° C. and pressure: saturated vapor pressure to 50 MPa is more preferable. If the temperature and pressure are too low, the hydrolysis reaction rate of the polysaccharide is low and the production efficiency is low. If the temperature and pressure are too high, the reaction control is difficult and the yield tends to decrease.

The reaction time of the polysaccharide material in pressurized hot water varies depending on the reaction equipment, reaction temperature, molecular weight and crystallinity of the polysaccharide material, and the type and amount of oxidant used. If pressurized hot water is in the range of 250 to 350 ° C, it is about 0.2 to 300 seconds. However, when a fixed bed reactor through which hot water is circulated is used, it is necessary to pass water for several minutes in order to drive out the water-soluble component out of the reaction system. When a batch type reactor is used, the reaction time may be longer because the heating time to a predetermined temperature depends on the size of the reactor.

The reaction liquid flowing out from the reactor is preferably cooled immediately in order to suppress secondary decomposition of water-soluble components such as glucose and oligosaccharide contained therein.

FIG. 1 is a schematic explanatory view showing an example of using an autoclave reactor configured to carry out the present invention. FIG. 2 shows an experimental flow chat for carrying out the present invention. After adding a polysaccharide substance such as cellulose, an oxidizing agent and distilled water in a predetermined amount to an autoclave and treating with ultrasonic waves for 10 minutes, the mouth is closed, put in a 250 ° C. oil bath and after a predetermined treatment time, The reaction is stopped by removing the autoclave from the oil bath and allowing it to enter the cooling water on the left.

The reaction mixture taken out from the autoclave is separated into unreacted residues, that is, a water-insoluble part and a water-soluble part by filtration or the like, and the residue of the water-insoluble part is dried, and then the yield is determined.

On the other hand, the product was identified and quantitatively analyzed by high performance liquid chromatograph (HPLC) for the water-soluble part. Thereby, the yield of each product can be determined.

The inner temperature of the above autoclave reaches the reaction temperature faster as the oil bath temperature is higher, and reaches 250 ° C. in about 16 minutes in an oil bath at 250 ° C.

Next, the present invention will be described in more detail with reference to Example 1 and Example 2. However, the present invention is not limited to these examples.
Hereinafter, the results of actual processing using the apparatus of FIG. 1 and the flow chat of FIG. The volume of the autoclave used for this experiment is 75 cm ³ .

Microcrystalline cellulose (Avicel, 2 g), distilled water (68 ml) and copper chloride 0.05, 0.1, 0.15 wt% were placed in a 75 ml autoclave, the mouth was closed, and ultrasonically treated for 10 minutes. Thereafter, the treatment was performed in an oil bath at 250 ° C. with treatment times changed by 16, 18, and 19.5 minutes. The analysis results are shown in Table 1, FIG. 3 and FIG. As a result, under the processing conditions of a temperature of 250 ° C. and a time of 18 seconds, the glucose yield was maximized when the amount of copper chloride added was in the range of 0.05 to 0.1%.

In place of copper chloride, FeCl 3, CuSO 4, AgNO 3, AgCl, SnCl 4 and iodine were added from 0.02 to 0.15%, and the cellulose was treated under exactly the same conditions and procedures as in Example 1. The processing results of the obtained reaction liquid are shown in Table 1, FIG. 3 and FIG. Compared with Example 1, it can be said that the dependency of the amount and amount of glucose produced is similar.

Next, the case where it compares in the Example of this invention is shown below.
In Comparative Example 2, cellulose was treated under exactly the same conditions and procedures as Example 1 except that no oxidizing agent was used. The analysis results of the obtained reaction liquid are shown in Table 1 and FIG. Compared to the result of the same treatment time of 18 minutes in Example 1, when no oxidizing agent was added, the amount of glucose produced was only 3.5%, and the unreacted cellulose residue was about 85%. It was.

Table 2 shows the results of treating cellulose under the same treatment conditions as in Example 1 by adding a salt compound having low or no oxidizability. Compared to Table 1, the addition of salt compounds such as Ca, Mg, Zn and Fe2 did not promote hydrolysis and increase the amount of glucose produced.

The presence of an oxidizing agent by the method for hydrolyzing polysaccharide materials of the present invention promotes the hydrolysis of cellulose, reduces the corrosion of the reactor seen in the case of acid hydrolysis, and uses this method industrially. Thus, saccharides such as glucose can be obtained in high yield. Table 1 shows the influence of the oxidizing agent on the yield of the cellulose reaction product. Table 2 shows the yield of the reaction product of cellulose in the presence of a salt compound that is a non-oxidizing agent.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic explanatory drawing which shows the example of an apparatus comprised in order to implement this invention. The experiment flow chat of implementation of this invention. It is a graph which shows the influence of reaction time with respect to the yield of the reaction product of a cellulose in presence of an oxidizing agent. It is a graph which shows the influence of the oxidizing agent addition amount with respect to the yield of the reaction product of a cellulose in presence of an oxidizing agent.

Claims (8)

When hydrolyzing a polysaccharide substance with pressurized hot water, an oxidizing agent should be added and coexisted in the reaction system at a processing temperature in the range of 100 to 500 ° C. and a processing pressure in the range of saturated vapor pressure to 50 MPa. A method for hydrolyzing a polysaccharide material. The method for hydrolyzing a polysaccharide substance according to claim 1, wherein the polysaccharide substance to be hydrolyzed is cellulose, hemicellulose, starch, chitin or a substance containing at least one of them. The method for hydrolyzing a polysaccharide substance according to claim 1 or 2, which aims to produce monosaccharides and / or oligosaccharides. The method for hydrolyzing a polysaccharide substance according to claim 3, wherein the monosaccharide is glucose. The method for hydrolyzing a polysaccharide substance according to claim 1, wherein the oxidizing agent has an oxidation potential of 0 to 2 volts. The method for hydrolyzing a polysaccharide substance according to claim 1, wherein the oxidizing agent is at least one substance selected from silver, copper, ferric iron [Fe + 3], and a salt compound of tin. The method for hydrolyzing a polysaccharide substance according to claim 6, wherein the silver, copper, ferric [Fe + 3], tin salt compound, and the like are sulfate, nitrate, hydrochloride, and acetate. The method for hydrolyzing a polysaccharide substance according to claim 1, wherein the oxidizing agent is one or more substances selected from the group consisting of fluorine, chlorine, bromine and iodine.

Images