JP5130182B2 - Pretreatment method for empty fruit saccharification and method for producing ethanol using the pretreatment method - Google Patents

Description

  The present invention relates to an empty fruit saccharification pretreatment method having a high sugar recovery rate and an ethanol production method using the pretreatment method.

  Research is ongoing to produce bioethanol from cellulosic biomass.

  When ethanol is produced from cellulosic biomass, it is necessary to saccharify the cellulose prior to fermentation. For saccharification, physicochemical hydrolysis with concentrated sulfuric acid or dilute sulfuric acid, dilute sulfuric acid or steam is used. There is a method of hydrolyzing with an enzyme such as cellulase after the treatment.

Empty fruit bunches (EFB: Empty Fruit Bunch) are wastes produced in palm oil production, and are oily coconut bunches (FFB), which are residues obtained by separating oil-rich fruits after cellulosic biomass. are categorized. In the past, most of these empty fruit bunches were only used as fertilizers.
JP 2006-075007 A JP 2007-202518 A

  The present inventors started a saccharification experiment using dilute sulfuric acid and an enzyme to determine whether this empty fruit bunch can be used as an ethanol raw material.

  This empty fruit bunch is more easily decomposed than other cellulosic biomass, and some conditions of the conventional method of using only dilute sulfuric acid or the pretreatment with dilute sulfuric acid before the enzyme are used. Then, it turned out that the recovery rate of sugar falls significantly.

  Furthermore, when research was repeated to increase the sugar recovery rate, the pretreatment temperature was adjusted to 140 ° C. or higher, and the CS (combined severity) value calculated from the treatment temperature, treatment time, and pH was within a specific range. As described above, it was found that a high sugar recovery rate can be obtained by performing saccharification with an enzyme in the latter stage, and the present invention has been completed.

  Then, the subject of this invention is providing the manufacturing method of ethanol using the pre-processing method of empty fruit bunch saccharification, and the pre-processing method.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following invention.

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(Claim 1)
When producing ethanol using empty fruit bunches (EFB) as a raw material, a pretreatment method is performed before saccharification treatment,
Of the parameters consisting of the treatment temperature, pH, and treatment time in the pretreatment reactor, the treatment temperature is adjusted to 140 ° C to 160 ° C, the pH is adjusted with dilute sulfuric acid having a concentration of 0.5% to 5%, and the treatment time. Is adjusted to 5 to 10 minutes, and the pretreatment of the empty fruit bunches previously pulverized to 30 mm or less under the condition that the CS value obtained from the following formula is in the range of 1.75 to 2.06 EFB saccharification pretreatment method characterized by performing.

(Where t is the processing time (minutes), T is the processing temperature (° C.), and Tref is 100 ° C.)

(Claim 2)
When EFB is charged into the pretreatment reactor and pretreatment is performed, high pressure steam is introduced into the pretreatment reactor and a temperature environment of 140 ° C to 160 ° C and a high pressure of 0.25 to 1.0 MPa. environment is formed, after high-temperature and high-pressure treatment, pretreatment methods EFB glycation of claim 1, wherein the performing the operation to lower the stretch pressure in the range of 0.1 to 1 seconds.

(Claim 3)
After performing the pretreatment method according to claim 1 or 2 , solid-liquid separation is performed to separate the liquid component and the solid content,
The liquid component is subjected to solid-liquid separation again after adding an alkaline agent to obtain a C5 sugar solution, and at least a part of the C5 sugar solution is introduced into an ethanol fermentor,
The solid content is introduced into the ethanol fermentation tank with or without enzyme treatment, and in the ethanol fermentation tank, sugar fermentation liberated by pretreatment and enzyme treatment is converted into ethanol by yeast. A method for producing ethanol, comprising:

(Claim 4)
The method for producing ethanol according to claim 3 , wherein an enzyme treatment for saccharifying the solid content and ethanol fermentation are simultaneously performed in the ethanol fermentation tank.

(Claim 5)
The method for producing ethanol according to claim 3 or 4 , wherein the yeast has C5 sugar assimilation ability.

(Claim 6)
The method for producing ethanol according to any one of claims 3 to 5 , wherein at least a part of the C5 sugar solution is used for the preliminary culture of the yeast.

(Claim 7)
The ethanol production method according to any one of claims 3 to 5 , wherein at least a part of the C5 sugar solution and POME (Palm Oil Mill Effect) are used for the preliminary culture of the yeast.

  According to the present invention, it is possible to provide a pretreatment method for empty fruit saccharification with a high sugar recovery rate and a method for producing ethanol using empty fruit bunches as raw materials.

  Embodiments of the present invention will be described below.

<Pretreatment>
First, a pretreatment method for empty fruit saccharification according to the present invention (hereinafter referred to as a pretreatment method according to the present invention if necessary) will be described.

  In the pretreatment of the present invention, empty fruit bunches (EFB) are introduced into a pretreatment reactor, and pretreatment is performed under a condition where the CS (Combined safety) value is constant. When performing pretreatment by introducing EFB into the pretreatment reactor, high-pressure steam is introduced into the pretreatment reactor, a temperature environment of 140 ° C. or higher, and 0.25 to 1.0 MPa (gauge pressure). After the high-pressure environment is formed and subjected to the high-temperature and high-pressure treatment, an operation for decreasing the pressure at once is performed in a range of 0.1 to 1 second.

  FIG. 1 shows an example of a pretreatment apparatus. In FIG. 1, 1 is a pretreatment reactor, and 10 is an introduction port for introducing EFB as a raw material. The reactor 1 is not particularly limited as long as it has corrosion resistance and pressure resistance.

  Reference numeral 2 denotes a decompression tank, which is provided with an inlet 20 for introducing a reactant sent from the reactor 1 on the side surface, and the inlet 20 is connected to the lower outlet of the reactor 1 through a connecting pipe 12. Are connected. A steam pipe 13 capable of supplying high-pressure steam is connected to the lower part of the reactor 1. A reactant take-out pipe 21 is connected to the lower part of the vacuum tank 2.

  In order to efficiently perform saccharification, it is preferable that the empty fruit bunch introduced into the reactor 1 as a raw material during the pretreatment is pulverized and crushed to 30 mm or less before the treatment. The crushing treatment means is not particularly limited.

  When performing the pretreatment, first, a predetermined amount of dilute sulfuric acid may be put in a container different from the reactor 1, and the pulverized empty fruit bunches may be put and immersed.

  The weight ratio of dilute sulfuric acid to empty fruit bunches is preferably liquid / solid = 2-10, more preferably 4-6.

  The concentration of dilute sulfuric acid is preferably 0.5 to 5%, more preferably about 1.5 to 2.5%. As for dilute sulfuric acid, if the concentration is higher than this, it is not preferable because the component (mainly hemicellulose) hydrolyzed by pretreatment occurs and the sugar recovery rate decreases.

  After the immersion, excess dilute sulfuric acid is removed from the container, and the empty fruit bunch immersed in the reactor 1 is put into the reactor 1 for heat treatment.

  During the heat treatment, high-pressure steam is supplied from the steam pipe 13 at 140 ° C. or higher.

  The heating time, heating temperature, and pH are adjusted and set so that the CS value obtained by the above formula is in the range of 1.40 to 2.50, more preferably 1.70 to 2.40. Is preferred.

  If this CS value is in the range of 1.40 to 2.50, the sugar recovery rate at the end of the saccharification treatment (total sugar recovery rate) exceeds 70%, and if it is in the range of 1.70 to 2.40, 80. Exhibits excellent effects exceeding%.

  As described above, when EFB is introduced into the pretreatment reactor and pretreatment is performed, high-pressure steam is introduced into the pretreatment reactor, the temperature environment is 140 ° C. or higher, and 0.25 to 1.0 MPa. After the high-pressure environment is formed and the high-temperature and high-pressure treatment is performed, an operation of reducing the pressure at a stretch in a range of 0.1 to 1 second is preferable because saccharification is promoted in the subsequent solid saccharification step.

<Ethanol production method>
FIG. 2 is a flowchart showing the ethanol production method of the present invention.

  Reference numeral 100 denotes a pretreatment step, and the above-described pretreatment method can be adopted.

  Reference numeral 200 denotes a solid-liquid separation step for solid-liquid separation of the pretreatment reaction liquid after the pretreatment step. In the solid-liquid separation step, it is preferable to dehydrate so that the moisture content is lower in order to improve the sugar recovery rate. Examples of the dehydrator used for dehydration include a centrifuge and a filter press. A filter press is preferable in that the rate can be constantly maintained at 50 to 60%, and as a result, it contributes to an improvement in the sugar recovery rate.

  300 is a neutralization step, and the filtrate separated by the dehydrator is adjusted to pH 4-11. The filtrate contains sulfate ions because dilute sulfuric acid is used in the pretreatment. Since sulfate ion may be a fermentation inhibitor, it is preferable to exclude it from the filtrate. In this neutralization step, when an alkali agent such as slaked lime (powder or slurry) is added, the sulfate ions in the liquid produce calcium sulfate (gypsum) and can be separated and removed.

  If the filtrate after pretreatment contains a lot of fermentation inhibitors such as acetic acid, furfural, 5-hydroxymethylfurfural and there is a concern about the effect on fermentation, first add excessive slaked lime to adjust the pH to alkaline. It is preferable to adjust to the side and then lower again to the acidic side to a pH where fermentation is possible.

  If the fermentation inhibitor is not sufficiently removed as described above, the fermentation inhibitor may be removed by further steaming (heating the liquid to remove the low boiling point component).

  The neutralization process in this invention can also provide the acceleration tank for accelerating | stimulating the production | generation of an aggregate other than the neutralization reaction tank which adds and reacts a neutralizing agent. Moreover, in order to use 2 or more types of neutralizing agents in combination, the reaction which carries out addition reaction of each can also be provided separately, for example. For example, sulfate ions can be removed by slaked lime in the former reaction tank, and the pH can be adjusted with an alkaline agent such as caustic soda in the latter reaction tank.

  400 is a solid-liquid separation step for separating a solid component precipitated as gypsum and a liquid component containing C5 sugar (mainly xylose) in the neutralization step. In this solid-liquid separation step, a gravity type precipitation tank may be used, but it is not particularly limited as long as solid-liquid separation can be performed.

  The liquid component subjected to solid-liquid separation contains C6 sugar such as glucose in addition to C5 sugar (xylose). The liquid component separated here is referred to as a monosaccharide liquid.

  500 is a parallel saccharification and fermentation process, which performs enzymatic saccharification of the solid (mainly cellulose content) separated in the solid-liquid separation process 200 and alcohol conversion of the recovered monosaccharide.

  The parallel saccharification and fermentation process 500 includes a parallel saccharification and fermentation tank, and adds enzymes necessary for saccharification and yeast necessary for fermentation.

  The maintenance temperature of the parallel saccharification and fermentation tank is preferably 30 ° C. or higher, and can be raised to around 40 ° C. depending on the heat resistance of the fermentation bacteria.

  The pH may be adjusted to the optimum pH of the yeast and enzyme to be used, but it is usually preferably controlled in the range of 4.0 to 7.0, and more preferably in the range of 4.8 to 5.0.

  The amount of the enzyme added is preferably 5 to 50 FPU (filter paper unit = filter paper disintegration method) per 1 g (dry matter) of the substrate.

  The solid matter concentration in the parallel saccharification and fermentation tank may be in the range of 2 to 30%, preferably 5 to 20%, and more preferably 8 to 15%.

  The liquid used to adjust the solids concentration can be a liquid obtained by solid-liquid separation of the liquid after fermentation, and in that case, the enzyme that remains in the fermentation liquid can be used without waste. preferable.

  As the yeast used for fermentation, it is preferable to use a yeast improved so that C5 sugar can be assimilated. Yeast that assimilate xylose may be susceptible to fermentation inhibition. In this case, a method of adding general yeast having strong resistance to fermentation inhibition and yeast that assimilate xylose at the same time or at different times (about 1 to 2 days) is effective.

  The above embodiment is an example in which saccharification and fermentation are performed simultaneously, but a method of performing saccharification and fermentation separately may be used.

  In this case, the enzyme saccharification reaction conditions are preferably a solid content concentration of 10 to 30%, a temperature of 40 to 50 ° C., and a residence time of 1 to 3 days.

  Reference numeral 600 denotes a yeast preculture process. It is preferable to use a sugar (C5 sugar) obtained by the process as a sugar source.

  Since the yeast to be used can assimilate xylose, a monosaccharide liquid containing a large amount of xylose (a liquid obtained by neutralizing the pretreatment filtrate) is used. If necessary, those containing sugar, molasses, etc. can be used.

  It is also preferable to use waste liquid (POME) discharged from the palm mill as a nutrient source such as nitrogen. The above-mentioned molasses often contains some nutrients.

  Examples of the medium component ratio include 10% molasses, 50% POME, and 40% diluted water. Moreover, the substance containing a nutrient component can also be used as a culture medium component. Examples thereof include corn steep liquor (CSL), ammonium sulfate, phosphoric acid, urea and the like.

  700 is a distillation process, in which ethanol is separated and recovered from a liquid containing a large amount of solids.

  The distillation step generally includes a mash tower for separating and recovering distilled components, a rectifying tower for concentrating and recovering ethanol from the distilled components obtained in the mash tower.

  As the performance of distillation, the ethanol concentration after concentration in the mash column is often about 40%, and the ethanol concentration after concentration in the rectification column is often designed at about 80%.

  Furthermore, the water is removed from the high-concentration ethanol obtained by distillation, and dehydration and concentration is performed so that the ethanol product has a target concentration (for example, 99.5% or more).

  800 is a solid-liquid separation process, in which the residual liquid discharged from the mash tower is subjected to solid-liquid separation (filter press), the liquid is transferred to a wastewater treatment system and processed, and one solid content is used as fuel. Can do.

  As shown in FIG. 3, the solid-liquid separation process 800 is performed after fermentation and before the distillation process 700, and a part of the solid-liquid separated liquid is used for adjusting the solid concentration in the parallel saccharification and fermentation process 500. You can also

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

Example 1
1.93% dilute sulfuric acid was put in a container, and an empty fruit bunch pulverized to 30 mm or less was put therein and immersed in dilute sulfuric acid for 1 hour. After soaking, suction filtration was performed to remove excess moisture (water content 70%).

  200 to 300 g of the soaked empty fruit bunch obtained was put into the reactor. The reactor was sealed, and the steam was heated to 140 ° C. from the bottom. After maintaining the reaction time (5 minutes) from the time when the temperature reached, the lower valve of the reactor was opened, discharged to a vacuum tank, cooled and depressurized, and recovered.

  Under this pretreatment condition, the value of CS was 1.47.

After completion of the pretreatment, solid-liquid separation was performed by suction filtration, and the weight and sugar concentration of the liquid component were measured.
The solid content was subjected to enzymatic saccharification after measuring the weight.

Enzymatic saccharification was measured in a 200 ml flask to a solid content concentration of 2%, and citrate buffer (0.05 M, pH 5) was added so that the total amount was 100 ml.
400 FPU of cellulase was added, and the mixture was reacted at 45 ° C. for 72 hours while stirring with a shaker.

  As a blank, the inactivated enzyme was similarly added to a 200 ml flask prepared in the same manner.

  Pretreatment and saccharification were performed in this way, and the pretreatment saccharification rate, enzyme saccharification rate, and total sugar recovery rate were determined by the following calculation method. A biochemistry analyzer 2700 manufactured by YSI was used for analysis of xylose and glucose.

Pretreatment Saccharification Rate Amount of sugar obtained by pretreatment (A) = (Amount of filtrate after pretreatment) × (sugar concentration (xylose, glucose))
Pretreatment saccharification rate = (A) / (absolutely dried raw material solids)

Enzymatic saccharification rate Amount of sugar obtained by enzymatic saccharification (B) = (sugar released by enzymatic saccharification)-(blank sugar)
Enzyme saccharification rate = (B) / (solid dry raw material after pretreatment)

Total sugar recovery rate Total sugar recovery rate = (A + B) / (absolutely dried raw material solids) x (raw material utilization component ratio (75%))

  The results of evaluation are shown in Table 1 and FIG.

Examples 2-4
The treatment was performed and evaluated in the same manner as in Example 1 except that the acid concentration, treatment temperature, and treatment time shown in Table 1 were used. The results are shown in Table 1 and FIG.

Comparative Examples 1 and 2
The treatment was performed and evaluated in the same manner as in Example 1 except that the acid concentration, treatment temperature, and treatment time shown in Table 1 were used. The results are shown in Table 1 and FIG.

The figure which shows an example of a pre-processing apparatus Flow chart showing the ethanol production method of the present invention The flowchart which shows another aspect of the ethanol manufacturing method of this invention Graph showing pretreatment saccharification rate, enzyme saccharification rate, and total sugar recovery rate in Examples and Comparative Examples

Explanation of symbols

1: Pretreatment reactor 10: Input port 11: Discharge port 12: Connecting tube 13: Steam tube 2: Depressurization tank 20: Inlet port 21: Reactant take-out tube 100: Pretreatment step 200: Solid-liquid separation step 300: Medium Japanese process 400: Solid-liquid separation process 500: Parallel saccharification and fermentation process 600: Yeast pre-culture process 700: Distillation process 800: Solid-liquid separation process

Claims (7)

When producing ethanol using empty fruit bunches (EFB) as a raw material, a pretreatment method is performed before saccharification treatment,
Of the parameters consisting of the treatment temperature, pH, and treatment time in the pretreatment reactor, the treatment temperature is adjusted to 140 ° C to 160 ° C, the pH is adjusted with dilute sulfuric acid having a concentration of 0.5% to 5%, and the treatment time. Is adjusted to 5 to 10 minutes, and the pretreatment of the empty fruit bunches previously pulverized to 30 mm or less under the condition that the CS value obtained from the following formula is in the range of 1.75 to 2.06 EFB saccharification pretreatment method characterized by performing.

(Where t is the processing time (minutes), T is the processing temperature (° C.), and Tref is 100 ° C.) When EFB is charged into the pretreatment reactor and pretreatment is performed, high pressure steam is introduced into the pretreatment reactor and a temperature environment of 140 ° C to 160 ° C and a high pressure of 0.25 to 1.0 MPa. 2. The pretreatment method for EFB saccharification according to claim 1, wherein after the environment is formed and subjected to the high-temperature and high-pressure treatment, an operation of lowering the pressure at a stretch in a range of 0.1 to 1 second is performed. After performing the pretreatment method according to claim 1 or 2, solid-liquid separation is performed to separate the liquid component and the solid content,
The liquid component is subjected to solid-liquid separation again after adding an alkaline agent to obtain a C5 sugar solution, and at least a part of the C5 sugar solution is introduced into an ethanol fermentor,
The solid content is introduced into the ethanol fermentation tank with or without enzyme treatment, and in the ethanol fermentation tank, sugar fermentation liberated by pretreatment and enzyme treatment is converted into ethanol by yeast. A method for producing ethanol, comprising: The method for producing ethanol according to claim 3, wherein an enzyme treatment for saccharifying the solid content and ethanol fermentation are simultaneously performed in the ethanol fermentation tank. The method for producing ethanol according to claim 3 or 4, wherein the yeast has C5 sugar assimilation ability. The method for producing ethanol according to any one of claims 3 to 5, wherein at least a part of the C5 sugar solution is used for the preliminary culture of the yeast. In pre-culture of the yeast, at least a part of the C5 sugar solution and POME (Palm Oi
The method for producing ethanol according to any one of claims 3 to 5, wherein 1 Mill Effect) is used.

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