JP2010136646A - Method for producing saccharide from bark raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve energy efficiency in a saccharification step by controlling the water content and the drying temperature of bark raw material in a saccharification of bark being an unused woody biomass. <P>SOLUTION: The method for producing a saccharide from a bark raw material includes saccharifying a bark raw material having a water content of ≥10%. The method for producing a saccharide from a bark raw material includes adjusting the water content of a bark raw material to 10-40% in a drying step for heat-treating the bark raw material at 40-100°C and saccharifying the bark raw material. The saccharification is acid saccharification in which the bark raw material immersed in an acidic aqueous solution in the method for producing a saccharide from a bark raw material. The saccharification is enzymatic saccharification with an enzyme in the method for producing the saccharide from a bark raw material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing saccharides using bark as a raw material for producing saccharides.

In recent years, as a measure against global warming, reduction of carbon dioxide emissions has been urged. For this purpose, conversion from fossil fuel energy to biomass energy is effective.
As shown in many books (see Non-Patent Documents 1 to 4), there are various methods for producing biomass energy such as pyrolysis, gasification, and anaerobic fermentation of biomass. A method for obtaining ethanol by fermenting contained sugars has been widely studied. Ethanol is widely available as a liquid fuel, and industrial production of ethanol for fuel using corn and sugarcane as a raw material has already been put into practical use.

However, the use of food resources such as corn and sugarcane as a raw material for ethanol for fuel has caused various social problems such as price increases due to competition with food demand.
Therefore, woody biomass derived from trees that does not compete with these demands, agricultural biomass such as bagasse and rice husk, and cellulose-based materials such as waste paper and pulp are expected as raw materials for biomass energy.

  A tree is divided into an inner xylem and an outer bark with a formation layer where cell division is active as a boundary. The bark accounts for about 10 to 15% of the total tree weight, and the bark has a relatively low lignin content compared to the xylem and is soft and rich in soluble components. In addition, the bark is divided into an outer bark of dead tissue and an inner bark of living tissue.

The outer bark mainly consists of pericytes or cork layers, which protects the wood tissue from mechanical damage and reduces fluctuations in temperature and humidity.
The inner bark consists of mentor elements, parenchyma cells and thick-walled cells. The mentor elements have the function of transporting liquids and nutrients. . Thick wall cells function as a supporting tissue, are observed in layers like the xylem rings, and are differentiated into bast fibers and scleroids by shape.

Bark tissue is roughly divided into fine substances including fibers, cork cells, and parenchyma cells. Bark fibers are chemically similar to xylem fibers and are composed of cellulose, hemicellulose and lignin. A fine substance containing cork cells and parenchyma contains a large amount of extracted components, and the cork cell walls are rich in suberins and the fine substance fraction is rich in polyphenols. Thus, bark, unlike xylem, contains many useful soluble components, the amount of which reaches 20-40% of the dry mass, and the fiber fraction has the same fiber as xylem. Has excellent properties.
However, bark is not used in timber applications and can be returned to the soil as a fertilizer in the plantation along with branches and roots to reduce pulp quality when pulping in the papermaking process, even if slightly mixed. It is an unused biomass that has been peeled and incinerated at a lumber mill or chip factory and has not been effectively used. Therefore, it is particularly promising as a raw material for bioethanol.

  In order to produce useful substances such as ethanol and organic acids from the bark, it is necessary to extract sugar from the bark and perform microbial conversion by fermentation. For this purpose, a saccharification step is required in which lignin, which is a hardly decomposable polymer that forms a complex with saccharides, is removed, and lignocellulose present in the plant body is hydrolyzed to form glucose as a monosaccharide. is there.

  Currently, acid saccharification methods (such as Patent Documents 1 and 2) and enzymatic saccharification methods (such as Patent Documents 3 and 4) are basically known as methods for producing monosaccharides from lignocellulose. Even if it is a method, research is performed from various viewpoints in order to produce saccharides with the lowest possible energy consumption and high yield. Reducing the energy costs required for saccharification is extremely important to enable the replacement of fossil fuels with biomass energy, and various methods are being studied for this purpose, including pretreatment of bark raw materials. is there.

JP 2004-89016 A JP 2005-229822 A JP 2008-521396 A JP 2005-168335 A Edited by The Wood Society of Japan, “Wood Biomass Utilization Technology” p19-61, Bunnendo Publishing, July 1997 Hideaki Yukawa et al. “Latest Biomass Energy Utilization”, Chapter II-1, CMC Publishing, August 2001 Keisuke Iizuka et al. “Latest Technology of Wood Chemicals” p6-34, published by CMC, October 2001 Funaoka et al. “New Development of Woody Organic Resources” Chapter 5-2, CMC Publishing, published in January 2005 Fukui Sakuzo “Quantitative method for reducing sugars” p49-52, published by Academic Publishing Center, October 1990

  The subject in this invention makes it a subject to improve the energy efficiency in a saccharification process process by controlling the moisture content and drying temperature of a bark raw material in the saccharification process of the bark which is unused woody biomass.

The present invention for achieving the above object includes the following inventions.
That is, the first of the present invention is a method for producing a saccharide from a bark raw material by saccharifying a bark raw material having a water content of 10% or more.

  The second of the present invention is a method for producing a saccharide from the bark raw material according to the first of the present invention, wherein the water content is adjusted to 10 to 40% by a drying step of heat-treating the bark raw material at 40 to 100 ° C. It is.

  A third aspect of the present invention is a method for producing a saccharide from the bark raw material according to the first or second aspect of the present invention, wherein the saccharification treatment is an acid saccharification treatment in which the raw material bark is immersed in an acidic aqueous solution.

  4th of this invention is a method of manufacturing saccharide | sugar from the bark raw material of this invention 1 or 2 whose said saccharification process is the enzyme saccharification process by an enzyme.

  By this invention, it becomes possible to reduce the energy cost of the process which obtains the composition used as a biochemical raw material and energy resource useful by the saccharification process of the bark which is unused woody biomass.

Hereinafter, the present invention will be described in more detail.
The tree species of the bark used in the present invention is not particularly limited, and any of broadleaf trees such as Eucalyptus and Acacia, and conifers such as Pine and Genus can be used.

In the present invention, saccharides are produced using a bark raw material having a water content of 10% or more.
In the present invention, the moisture content of the bark raw material to be subjected to the saccharification step may be arbitrary as long as it is 10% or more. However, if the moisture content is high, the raw material becomes heavy and the transportation energy cost becomes high. In addition, the amount of moisture can be reduced. Furthermore, when the acid saccharification treatment is performed, if the water content is high, the amount of chemicals required increases, and therefore, it is preferably 40% or less. Further, when the enzymatic saccharification treatment is performed, if the moisture content is low, the pretreatment effect due to crushing or the like may be reduced, so that it is preferably 30% or more.

In the present invention, the moisture content of the bark was calculated by the following formula 1.
<Formula 1> Moisture content (%) = (mass before drying−dry mass) ÷ mass before drying × 100

  Moreover, in this invention, when drying a bark raw material, it is desirable that the temperature of a drying process is 40-100 degreeC. When dried at 100 ° C. or higher, the bark is cured, so that the amount of power used for saccharification increases and the sugar yield decreases. In the present invention, the most preferable drying temperature is 60 to 80 ° C.

In the present invention, the saccharification treatment of the bark raw material adjusted to a moisture content of 10% or more as described above is performed.
In addition, the bark raw material can be crushed before the saccharification treatment in order to obtain a particle size that allows efficient saccharification. The machine used for the crushing process is not particularly limited as long as the bark can be crushed or defibrated, but a refiner, a crusher, a disaggregator, or the like can be used.

  When lignocellulose, which is the main component of the bark raw material, is saccharified, saccharification that decomposes cellulose into glucose, which is a monosaccharide, is an important stage. Basically, acid saccharification and enzymatic saccharification methods are well known as methods for producing monosaccharides from lignocellulose, but in the present invention, any conventional method can be applied. .

  The acid used in the acid saccharification treatment can be a mineral acid such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, an organic acid such as trifluoroacetic acid, or a mixture of these acids.

  The sugar solution obtained in the present invention contains cellulose and hemicellulose, which are polysaccharides derived from woody biomass, and various monosaccharides such as glucose and xylose. These sugars are microbially converted to alcohols and organic acids in the fermentation process.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example. In each Example shown below,% is based on mass unless otherwise specified.
For the measurement of sugar concentration, the phenol sulfuric acid method (Non-patent Document 5) was used. The influence of the moisture content of the raw material on the saccharification process was evaluated by the amount of electric power required for the crushing process and the sugar yield of the sugar solution obtained by crushing / enzymatic saccharification process and acid saccharification process.

<Example 1>
After collecting the bark of Eucalyptus globulus (water content 62%), the amount of electric power and the sugar yield of each of the enzymatic saccharification treatment and the acid saccharification treatment were measured by the following methods to evaluate the saccharification efficiency.
a) Enzymatic saccharification treatment After cutting the bark into 40 mm square sections, add 600 g by dryness and add sodium hydroxide and pure water to a total of 3000 g and 10% alkaline solution including the moisture contained in the bark. After the mixture is heated at 120 ° C. for 1 hour using an autoclave, the bark is separated from the alkaline solution using a sieve, and the clearance is 1 mm using a refiner (manufactured by Kumagai Riki Kogyo). Crushing treatment was performed. The refiner power required for breaking the bark was measured using a power accumulator. The required power was calculated as the power consumed by actually cutting the bark minus the power required for idling. The idling power is defined as the power required to operate the refiner without crushing the bark.
Next, enzymatic saccharification was performed at 30 ° C. and a reaction time of 20 hours with the following reaction solution composition. The sugar concentration after the enzymatic saccharification treatment was measured by the phenol-sulfuric acid method, and the sugar yield was calculated by the following formula 2.

[Reaction solution composition]
5% Bark 5% Cellulase (GC220 Danisco)
50 mM phosphate buffer (pH 4.5)
<Formula 2> Sugar yield (%) = (total sugar amount after saccharification treatment / dry weight of bark used) × 100

b) Acid saccharification treatment After cutting the bark into sections of about 20 mm square, 5 g equivalent was put into a plastic beaker by absolute drying, and 100 ml of 70% sulfuric acid was added and stirred at 20 ° C. for 18 hours. The sugar concentration of the liquid was measured in the same manner as above to calculate the sugar yield.

<Example 2>
Evaluation was performed in the same manner as in Example 1 except that eucalyptus / globula bark was subjected to a saccharification treatment after a drying temperature of 60 ° C. and a water content of 30%.

<Example 3>
Evaluation was performed in the same manner as in Example 1 except that eucalyptus / globula bark was subjected to a saccharification treatment after a drying temperature of 60 ° C. and a moisture content of 15%.

<Comparative Example 1>
Evaluation was performed in the same manner as in Example 1 except that eucalyptus / globula bark was subjected to a saccharification treatment after a moisture content of 5% at a drying temperature of 60 ° C.
The results of the electric energy and sugar yield in Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

  When Examples 1 to 3 were compared with Comparative Example 1, an increase in power consumption and a decrease in sugar yield were observed in the comparative examples. That is, it was suggested that the saccharification efficiency is improved by setting the moisture content of the bark to 10% or more in the saccharification treatment of the bark.

<Example 4>
Evaluation was performed in the same manner as in Example 1 except that the eucalyptus / globula bark used in Example 1 was subjected to a saccharification treatment at a drying temperature of 80 ° C. and a moisture content of 15%.

<Example 5>
Evaluation was performed in the same manner as in Example 1 except that the bark of Eucalyptus globulus used in Example 1 was subjected to a saccharification treatment after a moisture content of 15% at a drying temperature of 120 ° C.
The results of Examples 3 to 5 are shown in Table 2 above.

  When Examples 3 and 4 were compared with Example 5, the amount of power increased in Example 5. In addition, the sugar yield was slightly reduced, suggesting that the treatment cost was improved by lowering the drying temperature to 100 ° C. or lower in the bark drying process.

  INDUSTRIAL APPLICABILITY The present invention can be widely used in the biomass chemical industry by improving sugar yield and power cost by controlling moisture content and drying temperature in the process of producing a sugar solution for fermentation from bark which is a biomass raw material. .

Claims (4)

  A method for producing a saccharide from a bark raw material, characterized by saccharifying a bark raw material having a water content of 10% or more.   The method for producing a saccharide from the bark raw material according to claim 1, wherein the bark raw material is saccharified after a moisture content of 10 to 40% by a drying process in which the bark raw material is heat-treated at 40 to 100 ° C.   The method for producing a saccharide from a bark raw material according to claim 1 or 2, wherein the saccharification treatment is an acid saccharification treatment in which the raw material bark is immersed in an acidic aqueous solution.   The method for producing a saccharide from a bark raw material according to claim 1 or 2, wherein the saccharification treatment is an enzymatic saccharification treatment with an enzyme.