JP2014023484A - Method for manufacturing sugar from herbaceous biomass or woody biomass and method for manufacturing ethanol from sugar produced therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing sugar at a low cost, using cellulose or hemicellulose obtained from a herbaceous biomass or a woody biomass as a raw material, and a method for manufacturing ethanol at a low cost from the sugar manufactured therewith.SOLUTION: In the method for manufacturing sugar or ethanol from a herbaceous biomass or a woody biomass, a herbaceous biomass or a woody biomass undergoes an alkali treatment with an alkali solution, and then the treated liquid undergoes a solid-liquid separation and is separated into an alkali solution and a solid component. The separated alkali solution is supplied with additional alkali and reused in the alkali treatment step, allowing the alkali solution to be reused repeatedly in the alkali treatment.

Description

  The present invention relates to a method for producing sugar at low cost using cellulose or hemicellulose in herbaceous biomass or woody biomass as a raw material, and a method for producing ethanol at low cost from the produced sugar.

  In recent years, bioethanol has attracted attention as a carbon-neutral liquid fuel that does not depend on fossil resources, and ethanol production technologies for various biomass have been proposed.

  When ethanol is produced from cellulose in biomass, cellulose and hemicellulose contained in biomass are hydrolyzed to saccharify into monosaccharides and oligosaccharides.

  As a saccharification method for cellulose and hemicellulose contained in herbaceous / woody biomass, an enzymatic method is known. In the enzymatic method, it is necessary for the enzyme to act effectively on cellulose and hemicellulose contained in the herbaceous and woody biomass, and in order for the enzyme to act effectively, It is known that an alkaline treatment is applied to herbaceous / woody biomass prior to enzymatic hydrolysis.

  For example, JP 2012-85544 A (Patent Document 1) discloses that pellets of herbaceous biomass such as rice straw are pelletized so that the amount of pellets of herbaceous biomass relative to the amount of alkaline solution is 5% to 20%. The mixed herbaceous biomass is mixed with an alkali solution such as sodium hydroxide, subjected to alkali treatment, and after a predetermined time, neutralized by adding an acid such as sulfuric acid to the alkaline solution containing the herbaceous biomass, Cellulase enzyme treatment is applied to neutralized herbaceous biomass to decompose cellulose in herbaceous biomass to monosaccharides with cellulase, and ethanol is fermented using the resulting sugar as raw material to produce ethanol A method for producing sugar and producing ethanol using the produced biomass as a raw material is disclosed.

  In JP 2012-85544 A (Patent Document 1), prior to neutralization of an alkaline solution with an acid, the alkaline solution is solid-liquid separated to recover a solid component, and then the solid component is converted into an acidic solution. It is possible to neutralize the alkali impregnated in the herbaceous biomass by immersing it in and to produce ethanol by simultaneous fermentation of cellulase-producing bacteria and ethanol-fermenting bacteria using the herbaceous biomass after alkali treatment as a raw material It is disclosed that it may be.

JP 2012-85544 A

  However, as described in Japanese Patent Application Laid-Open No. 2012-85544 (Patent Document 1), in the case where a herbaceous biomass is alkali-treated using sodium hydroxide prior to saccharification, a large amount of sodium hydroxide is used. Is necessary and inevitably increases the cost.

  In addition, when recovering solid components by solid-liquid separation of the alkali solution after alkali treatment, useful substances such as lignin that can be made into fuel and oligosaccharides that can be used in the production of ethanol are eluted in the alkali solution. Therefore, when separately collecting lignin, oligosaccharides, etc. from an alkaline solution, it is necessary to concentrate the solution to collect lignin, and to collect oligosaccharides requires high-cost methods such as membrane separation. There was a problem of up.

  There was a similar problem with woody biomass.

  Therefore, the present invention provides a method for producing sugar at low cost using cellulose or hemicellulose in herbaceous biomass or woody biomass as a raw material, and a method for producing ethanol at low cost from the produced sugar. It is for the purpose.

  Such an object of the present invention is to process a herbaceous biomass or a woody biomass using an alkaline solution, and subject the alkali-treated solution to a solid-liquid separation into an alkaline solution and a solid component. It is achieved by a method for producing sugar or ethanol from herbaceous biomass or woody biomass characterized in that it is supplemented with an alkaline substance, recycled to an alkaline treatment step, and repeatedly used for alkaline treatment.

  According to the present invention, the separated alkaline solution is replenished with an alkaline substance and repeatedly used for alkali treatment of herbaceous biomass or woody biomass, so the amount of alkaline substance used is greatly reduced. The cost for producing sugar or ethanol from herbaceous biomass or woody biomass can be greatly reduced.

  In addition, according to the present invention, the alkaline substance used for the alkali treatment is solid-liquid separated and repeatedly used for the alkali treatment, so that the amount of acid used for neutralizing the solid component separated by solid-liquid separation is reduced. It is possible to reduce the cost for producing sugar or ethanol from herbaceous biomass or woody biomass.

  In a preferred embodiment of the present invention, a method for producing sugar or ethanol from herbaceous biomass or woody biomass comprises acidifying an alkaline solution recycled to an alkali treatment step over a predetermined number of times to precipitate lignin, It is configured to separate.

  Lignin, oligosaccharides, etc. are eluted in the alkaline solution used for the alkaline treatment of herbaceous biomass or woody biomass. The more frequently the alkaline solution is recycled to alkaline treatment, the more lignin, oligosaccharide, etc. in the alkaline solution. The concentration of becomes higher. Lignin can be used as a fuel, and oligosaccharide can be used as a raw material for ethanol production by microorganisms such as yeast by breaking down into monosaccharides. However, when lignin is present, the oligosaccharide cannot be decomposed by cellulase into a monosaccharide that can be easily used by microorganisms such as yeast. An acid is added to an alkaline solution used for alkali treatment of biomass or woody biomass over a predetermined number of times to adjust the pH to 6 or less, acid-insoluble lignin is precipitated and separated, and lignin is recovered.

  In a further preferred embodiment of the present invention, the oligosaccharide eluted after separation of the precipitated lignin is supplied to a saccharification tank to which the enzyme is supplied to monosaccharide the oligosaccharide, and the resulting monosaccharide Is fed to a fermentor in which yeast is present and fermented to produce ethanol, or fed to a simultaneous saccharification and fermenter in which enzyme and yeast are present to be monosaccharified and fermented to produce ethanol It is configured as follows.

  In the present invention, the alkaline substance is not particularly limited, and other alkaline substances such as sodium hydroxide and calcium hydroxide can be used.

  According to the present invention, a method for producing sugar at low cost using cellulose or hemicellulose in herbaceous / woody biomass as a raw material and a method for producing ethanol at low cost from the produced sugar are provided. Is possible.

FIG. 1 is a schematic diagram showing the steps of a method for producing ethanol using herbaceous / woody biomass as a raw material according to a preferred embodiment of the present invention. FIG. 2 is a schematic view showing the steps of a method for producing ethanol using herbaceous / woody biomass as another raw material according to another preferred embodiment of the present invention.

  As shown in FIG. 1, in an ethanol production method according to a preferred embodiment of the present invention in which ethanol is produced using herbaceous biomass as a raw material, rice straw is placed in an alkaline treatment tank 1 containing a sodium hydroxide solution. Plant biomass such as is added and immersed in sodium hydroxide solution. At this time, as disclosed in Japanese Unexamined Patent Publication No. 2012-85544 (Patent Document 1), plant biomass such as rice straw may be pelletized and immersed in a sodium hydroxide solution.

  The pH of the sodium hydroxide solution is pH 9.5 to 13.5, preferably pH 10 to 13, and more preferably pH 11 to 12.5.

  The alkali treatment with the sodium hydroxide solution is performed at a temperature of normal temperature to 160 ° C., preferably normal temperature to 120 ° C.

  In the alkali treatment, hydrogen peroxide may be injected as an oxidizing agent. As the oxidizing agent, for example, persulfate, percarbonate, peracetate, ozone, sodium peroxide and the like can be used in addition to hydrogen peroxide.

  When the alkali treatment is completed, the sodium hydroxide solution containing the herbaceous biomass is sent to the first solid-liquid separator 2 and separated into a sodium hydroxide solution and a solid component which are liquid components.

  The sodium hydroxide solution separated from the solid component is guided to the first recycle pipe 3 and recycled to the alkali treatment tank 1 by the first recycle pipe 3. The concentration of the sodium hydroxide solution solid-liquid separated by the solid-liquid separator 2 is lower than the concentration of the sodium hydroxide solution necessary for performing the alkali treatment in the alkali treatment tank 1, and only the amount contained in the solid component So the amount of alkali itself is small. An alkali replenishment unit 4 for replenishing sodium hydroxide and water to the sodium hydroxide solution flowing through the first recycle pipe 3 is provided so that the sodium hydroxide solution has a predetermined concentration and amount.

  In the present embodiment, sodium hydroxide solution recycled to the alkali treatment tank 1 is added to the sodium hydroxide solution used for the alkali treatment separated by the first solid-liquid separator 2 by the alkali replenishment unit 4. Sodium hydroxide is replenished so that the concentration and amount are equal to the concentration and amount of sodium hydroxide required for performing alkali treatment in the alkali treatment tank 1.

  Thus, in this embodiment, the sodium hydroxide solution used for the alkali treatment is separated from the solid components by the first solid-liquid separation device 2 and recycled to the alkali treatment tank 1. It is only necessary to replenish sodium hydroxide and water in an amount that is less than the concentration and amount of sodium hydroxide necessary for the treatment tank 1 with the alkali replenishment unit 4, and therefore the consumption of sodium hydroxide can be greatly reduced. It is possible to achieve a significant reduction in manufacturing costs.

  On the other hand, the solid component that has been solid-liquid separated by the first solid-liquid separation device 2 is sent to the pH adjustment tank 5.

  In the pH adjustment tank 5, sulfuric acid and supplementary water are added to the solid components to adjust the pH of the solution. In the present embodiment, the sodium hydroxide solution separated by solid-liquid separation by the first solid-liquid separation device 2 is recycled to the alkali treatment tank 1 via the first recycling pipe 3. What is sent is a solid component from which most of the sodium hydroxide solution has been separated by the first solid-liquid separation device 2, and therefore the amount of sodium hydroxide sent to the pH adjusting tank 5 is larger than that of the prior art. Therefore, the amount of sulfuric acid supplied to the pH adjusting tank 5 can be reduced. Here, since the pH most suitable for the decomposition of cellulase is 4.6, it is preferable to adjust the pH of the solid component to 4.6 by the pH adjusting tank 5. The pH may be in the range of 4-5.

  The solution whose pH is adjusted to 4.6, for example, by the pH adjusting tank 5 is sent to the second solid-liquid separator 6.

  The liquid component separated into solid and liquid by the second solid-liquid separation device 6 is recycled to the pH adjusting tank 5 through the second recycle pipe 7.

  The solid component separated by the second solid-liquid separation device 6 is sent to the simultaneous saccharification and fermentation tank 8.

  The solid component sent to the simultaneous saccharification and fermentation tank 8 is supplied with cellulase including at least one of endoglucanase, cellobiohydrase, and betaglucosidase as an enzyme, and as yeast, for example, Saccharomyces cerevisiae. Thus, vegetation biomass is saccharified to produce ethanol.

  Thereby, it becomes possible to reduce the production cost of sugar and ethanol using herbaceous biomass as a raw material.

  As shown in FIG. 2, the method for producing ethanol using herbaceous / woody biomass as another raw material according to another preferred embodiment of the present invention is the same as the preferred embodiment of the present invention shown in FIG. In addition, the sodium hydroxide solution containing the herbaceous biomass that has been subjected to the alkali treatment in the alkali treatment tank 1 is sent to the first solid-liquid separation device 2, and the sodium hydroxide solution separated from the solid components by the solid-liquid separation is the first. Then, the alkali replenishing unit 4 replenishes sodium hydroxide and water and recycles them to the alkali treatment tank 1.

  As shown in FIG. 2, in this embodiment, a bypass pipe 10 branches from the first recycle pipe 3 on the upstream side of the alkali replenishment unit 4 and is connected to the pH adjustment tank 11. A first gate member 12 is provided at a branch portion of the bypass pipe 10 of the first recycle pipe 3, and the sodium hydroxide solution separated from the solid component by the solid-liquid separator 2 is selectively used. It is configured so that it can be sent to the pH adjustment tank 11 via the alkali treatment tank 1 or the bypass pipe 10.

  The pH adjustment tank 11 is connected to a lignin separation tank 13, and the lignin separation tank 13 is further selectively connected to the simultaneous saccharification and fermentation tank 8 and the polysaccharide decomposition tank 15 by a second gate member 14. The polysaccharide decomposition tank 15 is configured to be supplied with cellulase containing at least one of endoglucanase, cellobiohydrase, and betaglucosidase. The simultaneous saccharification and fermentation tank 8 includes, for example, endoglucanase, cellobiohydride as enzymes. A cellulase containing at least one of a lase and a beta glucosidase is supplied, and for example, Saccharomyces cerevisiae is supplied as yeast.

  Here, lignin, oligosaccharides and the like are eluted in the sodium hydroxide solution, and the concentration of lignin and oligosaccharide in the sodium hydroxide solution is determined by the water solid-liquid separated by the first solid-liquid separator 2. The higher the number of recycled sodium oxide solutions, the higher. Oligosaccharides can be decomposed into monosaccharides that can be easily used by microorganisms such as yeast by enzymes and used as raw materials for ethanol production. However, if lignin is present, oligosaccharides that are polysaccharides can be used by microorganisms such as yeast. It cannot be decomposed into monosaccharides that are easy to form, or used as a raw material for ethanol production. On the other hand, lignin can be used as a fuel and has an alkali-soluble property but does not dissolve in an acid.

  Therefore, in this embodiment, when the number of times of recycling the sodium hydroxide solution separated from the solid component into the alkali treatment tank 1 by the first solid-liquid separation device 2 reaches N times, for example, 10 times, The sodium hydroxide solution separated from the solid component by the first solid-liquid separation device 2 is sent to the pH adjusting tank 11 by the member 15, and an acid such as sulfuric acid is supplied to the pH adjusting tank 11 to adjust the pH. The sodium hydroxide solution sent to the tank 11 is acidified, for example, its pH is adjusted to 4.6 which is a pH suitable for cellulase degradation.

  As a result, lignin dissolved in the sodium hydroxide solution is precipitated. The solution containing the precipitated lignin is sent to the lignin separation tank 13, and the lignin is separated from the solution by filter filtration or centrifugation (not shown). The lignin separated from the solution is dried or used as a fuel as it is.

  On the other hand, the solution from which lignin has been separated and removed is selectively sent to the simultaneous saccharification and fermentation tank 8 or the polysaccharide decomposition tank 15 by the gate member 14. Since the solution from which lignin has been separated and removed contains high-concentration oligosaccharides, it is supplied to the simultaneous saccharification and fermentation tank 8 and solid components separated by the second solid-liquid separation device 6 together with the raw material of ethanol. In addition, as an enzyme, for example, it is supplied to a polysaccharide decomposition tank 15 to which cellulase containing at least one of endoglucanase, cellobiohydrase, and betaglucosidase is supplied, and is used by microorganisms such as yeast. It can be broken down into easy monosaccharides.

  According to this embodiment, as in the embodiment shown in FIG. 1, the sodium hydroxide solution separated from the solid component by the first solid-liquid separation device 2 is guided to the first recycling pipe 3, Since sodium hydroxide is replenished by the alkali replenishment unit 4 and recycled to the alkali treatment tank 1, the production cost of sugar and ethanol using herbaceous biomass as a raw material can be greatly reduced.

  Furthermore, according to this embodiment, as in the embodiment shown in FIG. 1, the sodium hydroxide solution separated by solid-liquid separation by the first solid-liquid separation device 2 passes through the first recycling pipe 3. Since it is recycled to the alkali treatment tank 1, it is the solid component from which most of the sodium hydroxide solution has been separated by the first solid-liquid separation device 2, so that the pH is adjusted. Therefore, the amount of sulfuric acid supplied to the pH adjustment tank 5 can be reduced.

  Further, the concentration of lignin and oligosaccharide in the sodium hydroxide solution separated from the solid component by the first solid-liquid separator 2 and led to the first recycle pipe 3 is determined by the first solid-liquid separator. In this embodiment, the number of recyclings of the sodium hydroxide solution into the alkaline treatment tank 1 is N times, for example, 10 times. By the first gate member 12, the aqueous sodium hydroxide solution is guided to the pH adjusting tank 11 through the bypass pipe 10. Here, the oligosaccharide eluted in the sodium hydroxide solution can be decomposed by enzymes into monosaccharides that can be easily used by microorganisms such as yeast, or can be used as a raw material for ethanol production. These oligosaccharides cannot be decomposed into monosaccharides that can be easily used by microorganisms such as yeast, nor can they be used as raw materials for ethanol production. Therefore, in the present embodiment, sulfuric acid is supplied to the solution from which the lignin and oligosaccharide eluted in the pH adjusting tank 11 are eluted, so that it is acidic, for example, the pH is a pH suitable for cellulase decomposition 4 As a result, acid-insoluble lignin is precipitated, and the oligosaccharide and lignin are separated to form a solution containing the oligosaccharide at a high concentration and supplied to the simultaneous saccharification and fermentation tank 8. In addition to the solid components separated by solid-liquid separation by the second solid-liquid separation device 6, it can be used as a raw material for ethanol, or as an enzyme, for example, at least one of endoglucanase, cellobiohydrase, and beta-glucosidase. It can be supplied to the polysaccharide decomposition tank 15 to which the cellulase is supplied, and decomposed into monosaccharides that can be easily used by microorganisms such as yeast. Therefore, according to this embodiment, ethanol is produced from the sodium hydroxide solution separated from the solid components by the first solid-liquid separation device 2, or decomposed into monosaccharides that can be easily used by microorganisms such as yeast. Since the oligosaccharide that can be recovered is used as a raw material for producing sugar or ethanol, it is possible to produce sugar and produce ethanol at low cost.

  In addition, according to this embodiment, lignin that prevents production of monosaccharides and ethanol using oligosaccharide as a raw material is supplied to sulfuric acid in the pH adjustment tank 11, and the pH of the solution in the pH adjustment tank 11 is increased. Is adjusted to 4.6 and separated as fuel, so that it is possible to suppress consumption of earth resources.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the said embodiment, although explanation is added about herbaceous biomass, it is not necessarily required that biomass is herbaceous, and sugar and ethanol are manufactured similarly using woody biomass. You can also.

  Moreover, in the said embodiment, in the pH processing tank 5, a solid-liquid is isolate | separated by the 2nd solid-liquid separator 6 in the solution adjusted pH, and a liquid component is passed through the 2nd recycle pipe 7, Although it is comprised so that it may recycle to pH processing tank 5, it is not necessarily required to carry out solid-liquid separation of the solution in which pH was adjusted, and to recycle a liquid ingredient to pH processing tank 5, You may make it supply the solution in which pH was adjusted to the simultaneous saccharification fermenter 8 directly.

  Further, in the embodiment shown in FIG. 1, the solid component from which the liquid component has been separated by the second solid-liquid separation device 6 is an enzyme, for example, at least one of endoglucanase, cellobiohydrase, and beta-glucosidase. Is supplied to a simultaneous saccharification and fermentation tank 8 to which, for example, Saccharomyces cerevisiae is supplied, and saccharified, and ethanol is produced from the resulting sugar. Instead of the simultaneous saccharification and fermentation tank 8, the solid component from which the liquid component has been separated by the second solid-liquid separation device 6 is supplied to a saccharification tank to which enzymes are supplied, and saccharification is performed. You may make it produce | generate ethanol by supplying to the fermenter supplied. Similarly, in the embodiment shown in FIG. 2, the solution in which the pH is adjusted and the lignin is separated is supplied to the saccharification tank 15 to which the enzyme is supplied, saccharified, or supplied by the enzyme and yeast. Is supplied to the simultaneous saccharification and fermentation tank 8 and saccharified, and the resulting sugar is fermented to produce ethanol, but yeast is supplied instead of the simultaneous saccharification and fermentation tank 8. A fermenter may be provided, and the sugar produced in the saccharification tank 15 may be sent to the fermenter and fermented to produce ethanol.

  Further, in the above embodiment, sodium hydroxide is used as the alkaline substance, but it is not always necessary to use sodium hydroxide. Instead of sodium hydroxide, other alkalis such as calcium hydroxide are used. Substances can be used.

  Furthermore, in the above embodiment, sulfuric acid is used as the acid, but it is not always necessary to use sulfuric acid, and other acids may be used instead of sulfuric acid.

DESCRIPTION OF SYMBOLS 1 Alkali processing tank 2 1st solid-liquid separator 3 1st recycle pipe 4 Alkali replenishment part 5 pH adjustment tank 5
6 Second solid-liquid separator 7 Second recycling pipe 8 Simultaneous saccharification and fermentation tank 10 Bypass pipe 11 pH adjustment tank 12 First gate member 13 Lignin separation tank 14 Second gate member 15 Polysaccharide decomposition tank

Claims (3)

Herbaceous biomass or woody biomass is alkali-treated with an alkali solution, the alkali-treated solution is solid-liquid separated into an alkali solution and a solid component, and the separated alkali solution is supplemented with an alkali substance, A method for producing sugar or ethanol from herbaceous biomass or woody biomass, which is recycled to an alkali treatment step and repeatedly used for alkali treatment. The sugar solution or ethanol is produced from the herbaceous biomass or the woody biomass according to claim 1, wherein the alkaline solution recycled to the alkali treatment step is acidified for a predetermined number of times to precipitate and separate lignin. how to. The precipitated lignin is separated, the oligosaccharide in the alkaline solution is recovered, supplied to the saccharification tank to which the enzyme is supplied, the oligosaccharide is monosaccharided, and the resulting monosaccharide is fed to the yeast. It is fed to a tank and fermented to produce ethanol, or fed to a simultaneous saccharification and fermentation tank to which enzymes and yeast are fed, and saccharified and fermented to produce ethanol. A method for producing sugar or ethanol from the herbaceous biomass or woody biomass according to claim 2.

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