JP2018111055A - Modification method of vegetable system biomass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reaction product suitable for fuel less in the content of alkaline-alkaline earth metal of becoming a factor of a clinker.SOLUTION: In a modification method of vegetable system biomass, a method having hot water treatment is provided for reducing alkaline and alkaline earth metal in a reaction product of separating, decomposing or carbonizing at least any of hemicellulose, cellulose and lignin by contacting powder type vegetable system biomass with hot water of the reaction temperature of 150-400°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for reforming plant biomass.

  Patent Document 1 discloses a fuel that uses plant-based biomass fiber such as EFB fiber as a raw material, has excellent transport efficiency, has a high calorific value, and can be used as a partial substitute fuel for coal in a coal-fired power generation facility. It is described to provide a solid fuel and a method for producing the same. The fuel in Patent Document 1 is a biomass solid fuel obtained by pressure-molding a semi-carbonized biomass obtained by heating a plant biomass fiber while heating, and 18 to 26% by mass of fixed carbon on an air-dry basis. The volatile content is 65 to 75 mass%, the ash content is 3 to 6 mass%, the water content is 8 to 16 mass%, and the high heating value is 18 to 21 MJ / kg on an air-dry basis. The pulverized plant biomass fiber is heated at 200 to 290 ° C. in an atmosphere having an oxygen concentration of 5% by volume or less and semi-carbonized, and the obtained semi-carbonized biomass is pulverized in the presence of water or water vapor. Manufactured by pressure molding while heating.

  Patent document 2 aims to provide a bamboo fiber composite resin composition that is lighter than conventional glass fiber reinforced resins and has excellent strength. A bamboo fiber composite resin composition characterized in that it is mixed with ˜70 mass% is described.

Japanese Patent Laying-Open No. 2015-229751 JP 2013-245346 A

  One of the problems in using plant biomass as a fuel for combustion is that clinker generated by combustion needs to be removed from a combustion furnace or the like. The clinker is ash or debris adhering to the furnace wall of the combustion furnace, which prevents the flow of combustion air and prevents heat exchange in the boiler, and deteriorates the performance.

  One embodiment of the present invention is a method for modifying plant-based biomass. In this modification method, the alkali in the reaction product obtained by bringing powdered plant biomass into contact with hot water having a reaction temperature of 150 to 400 ° C. to separate, decompose, or carbonize at least one of hemicellulose, cellulose, and lignin, and Has hot water treatment to reduce alkaline earth metals. The clinker is considered to grow by melting ash in an incombustible material such as alkali metal or alkaline earth metal. Therefore, by reducing the alkali and alkaline earth metal that cause clinker by hydrothermal treatment, it is possible to provide a fuel that is a vegetable fuel that uses plant biomass as a raw material and that is difficult to produce clinker.

The flowchart which shows the manufacturing method of the fuel containing the hot-water process (hydrothermal treatment) which reforms plant biomass, and the manufacturing method of carbide. The table | surface which shows the chemical component composition of each sample. The block diagram which shows the outline | summary of a hydrothermal treatment apparatus. The graph which shows the production | generation behavior of a solubilizate. An example of the sugar analysis result of a solubilizate. The table | surface which shows the chemical component composition of a residue yield (reaction product yield) and a residue (reaction product). The graph which shows the collection rate of the solubilized product of Mosouchiku. The table | surface which shows the result of having quantified the alkali (Na, K) and alkaline-earth (Mg, Fe) metal density | concentration in a residue (reaction product). The table | surface which shows the yield and specific surface area of the product which carbonized the reaction product (hydrothermal-treatment residue) of Mosouchiku.

  FIG. 1 shows a method for producing fuel or producing carbide using plant-based biomass. The method for producing a plant-based fuel includes a step 1 for pulverizing plant-based biomass and a step 2 for performing hydrothermal treatment to reform the pulverized plant-based biomass. The method for producing carbide includes step 3 of further carbonizing the reaction product subjected to the hydrothermal treatment. The plant biomass as a raw material includes at least one of woody biomass, agricultural waste biomass, and bamboo. Examples of the woody biomass include woody biomass including cedar and cypress, and may include building waste, forest land residue, and the like. Agricultural waste biomass includes herbaceous biomass such as rice straw, rice husk, and wheat straw. All are cellulosic biomass, which is a raw material for biomaterials such as combustion fuel, other biomass fuels, and carbon fiber.

  The process (step 1) for pulverizing the plant-based biomass is a powdered form in order to increase the contact efficiency between the plant-based biomass and the hot water in the hydrothermal process (step 2). The maximum length (diameter, particle size, or representative length) of the powdered plant biomass is preferably 5 mm, more preferably 2 to 3 mm, and even more preferably 1 mm. The particle diameter is further desirably 0.5 mm or less.

  The hot water treatment (Step 2) is a treatment for modifying the plant biomass, and the powdery plant biomass is brought into contact with hot water having a reaction temperature of 150 to 400 ° C. The reaction temperature may be in a supercritical range, but is desirably a subcritical range in which liquid hot water is stably present, that is, 374 ° C. or lower. By contacting with hot water at the reaction temperature, hemicellulose is almost separated or decomposed from the plant biomass as a raw material and removed from the reaction product as a residue, and lignin and cellulose are partially separated or decomposed. However, the proportion (% by weight) in the reaction product as a residue increases. The reaction product may be carbonized or semi-carbonized.

  The inventors have found that, in the course of this hydrothermal treatment, not only hemicellulose is removed, but also alkali and alkaline earth metals that cause ash (clinker) are reduced. That is, it has been found that in the hydrothermal treatment (step 2), a residue having a low content of alkali and alkaline earth metal can be obtained as a reaction product, and plant biomass can be modified. Therefore, this hydrothermal treatment (step 2) is a treatment for reducing alkali and alkaline earth metal in the reaction product obtained by separating, decomposing or carbonizing at least one of hemicellulose, cellulose and lignin.

  Desirably, the hot water is in a liquid state pressurized to a saturated vapor pressure at least at the reaction temperature. Liquid hot water, that is, pressurized hot water, has a larger contact area between the hot water and the plant biomass that is the raw material, and has a greater effect of reducing alkali and alkaline earth metals.

  An example of pressurized hot water is hot water (saturated water) having a substantially saturated vapor pressure of 150 to 220 ° C. For example, 220 ° C., hot water of 2.3 to 2.5 MPa, 150 ° C., hot water of 0.5 to 1.0 MPa. By bringing pressurized hot water under these conditions into contact with plant biomass, alkali / alkaline earth metals can be efficiently removed from the cellulose while preventing elution of the cellulose in the raw material. For this reason, the ratio of the alkali / alkaline earth metal to the cellulose of the residue (reaction product) can be reduced. In addition, hemicellulose can be separated and removed almost completely, and the ratio of hemicellulose to cellulose can be reduced. On the other hand, elution and separation of lignin are not so much, and the ratio of alkali / alkaline earth metal can be reduced while leaving lignin having a high combustion temperature. For this reason, the fuel suitable for combustion can be provided using plant biomass.

  The hydrothermal treatment (step 2) may be any of batch, semi-batch and continuous, but in order to remove the components eluted in the hot water from the reaction product as a residue, the reaction product It is desirable to perform solid-liquid separation at a reaction temperature to separate the water from hot water. Therefore, the semi-batch system or the continuous system is preferable to the batch system.

  Since the alkali / alkaline earth metal in the reaction product can be reduced by the hydrothermal treatment (step 2), this reaction product is suitable as a fuel for combustion. Also, in the production of other forms of biofuel such as ethanol, if the presence of alkali / alkaline earth metal becomes an obstacle, the reaction product modified by this hydrothermal treatment can be used as a raw material. it can. The fuel (plant-based fuel) produced by the hydrothermal treatment from plant-based biomass does not substantially contain hemicellulose, and the ratio (weight ratio A / C) of alkali / alkaline earth metal A to cellulose C is 0. 2 or less fuel can be provided. The weight ratio A / C may be 0.17 or less. More specifically, a plant fuel having a total maximum content of alkali / alkaline earth metal of 5% (weight%) or less can be provided.

  In particular, a fuel using bamboo as a raw material can provide a fuel having a smaller content of alkali / alkaline earth metal. Biofuel made from bamboo may have a weight ratio A / C of 0.01 or less, or 0.006 or less. More specifically, it is a plant-based fuel that uses bamboo as a raw material, and has a total maximum content of 0.5% for alkali and alkaline earth metals.

  The reaction product (residue) in which the content of alkali / alkaline earth metal is reduced by the hydrothermal treatment (step 2) can be used as a raw material for carbide. An example of the carbonization treatment (Step 3) is to carbonize the reaction product at 500 to 900 ° C. under an inert gas. The carbide raw material is pretreated so as to remove hemicellulose and alkali / alkaline earth metal in a state where cellulose and lignin remain by hydrothermal treatment (step 2), and can provide a carbide having a high cellulose content. .

Example Mosouchiku (produced in Chiba Prefecture), rice straw (produced in Fukuoka Prefecture), and rice husk (produced in Fukuoka Prefecture) were pulverized to 0.5 mm or less by a wheelie mill to prepare a sample (Step 1). The pulverizer and particle size are not limited to this, but the particle size is preferably pulverized under 2 to 3 mm in consideration of contact with water. The chemical component composition of each sample (raw material) was performed according to the NREL method, and the results were as shown in FIG.

  For the hydrothermal treatment (hydrothermal treatment, step 2), a semi-batch type hydrothermal reactor 10 equipped with a percolator reactor (extraction vessel) 16 having an internal volume of 30 mL was used. FIG. 3 shows an outline of the hydrothermal treatment apparatus 10 used in this experiment. The hydrothermal treatment apparatus 10 includes a pure water tank 11, a high-pressure pump (NP-KX-500 manufactured by Japan Precision Science Co., Ltd.) 12, a heat exchanger 14, a tubular extraction container 16, a cooler 18, and a back pressure valve (manufactured by 6000 psi TESCOM). 20, the collection | recovery part 19, and the piping 13 which connects these. The extraction container 16 was capped with a mantle heater (manufactured by Otsuka Denki Co., Ltd.) 17 connected to a temperature controller (manufactured by T-550 Iuchi) 17a to control the temperature in the extraction container 16 to be constant. The pressure in the extraction container 16 was controlled by the back pressure valve 20.

  The heat exchanger 14 has a stainless steel container placed in a mantle heater 15 filled with a salt 15e having a ratio of potassium nitrate: sodium nitrite: sodium nitrate of 53: 40: 7, into which a 1/4 inch stainless steel tube is filled. The system was heated by passing pressurized water through the tube. The mantle heater 15 includes a base heater 15a, a throwing heater 15b, and a temperature controller 15c. The 1/4 inch SUS316 pipe 13 was also used for connection of each part. The hydrothermal treatment apparatus 10 includes a nitrogen supply system 21 for replacement.

  The hydrothermal treatment apparatus 10 is a semi-batch method, and a batch of samples is filled in the extraction vessel 16 and extraction is performed in a predetermined time or cycle while flowing hot water. The method of hydrothermal treatment (hydrothermal treatment) is not limited to this. The hydrothermal treatment apparatus may be a batch type or a continuous type. However, it is necessary to be able to perform solid-liquid separation at the reaction temperature without cooling even in the case of treatment with a batch or continuous hydrothermal treatment apparatus.

  10 g of the powder of each sample was put in the extraction container 16, and both ends were capped with a stainless sintered filter having a pore diameter of 20 μm, and then connected to the hydrothermal treatment apparatus 10. The treatment conditions were a hot water temperature of 200 ° C., a water flow rate of 15 mL / min, and a pressure of 2.5 MPa. The temperature was raised while passing hot water, and the target temperature was reached in about 10 minutes. Then, after processing for about 40 minutes, the temperature was cooled for about 10 minutes.

  About the collect | recovered solubilized liquid, Brix value was measured using the saccharimeter over time, and also it used for HPLC and HPAE-PAD analysis. The solubilized product is collected at intervals of 10 minutes (1 fraction, a total of 6 fractions), and a portion is dried at 105 ° C. until it reaches a constant weight, and weighed. Solute yield) was calculated. The total amount of residue in the reactor (reaction product) was transferred to a beaker with a known dry weight, dried at 105 ° C. until a constant weight was obtained, and weighed to calculate the yield based on the dry weight.

  This processing condition is an example, and the temperature, pressure, and flow rate are not limited thereto. However, the pressure is preferably equal to or higher than the saturated vapor pressure of the reaction temperature in order to contact the sample in a fluid state. Further, in order to promote the removal of hemicellulose and alkali / alkaline earth metal without promoting the elution of lignin and cellulose, hot water having a pressure close to the saturated vapor pressure, for example, within 110% of the saturated vapor pressure, is used. (Substantially saturated water) is desirable.

  Next, the Moso bamboo raw material and the hydrothermal treatment residue (reaction product) were carbonized (Step 3). Specifically, 2.0 g of each was weighed in a magnetic boat, transferred to a tubular electric furnace, and held at 600 ° C. and 800 ° C. for 1 hour under a nitrogen stream (200 mL / min). After cooling to room temperature and weighing, a carbide was obtained. The obtained carbide was measured for specific surface area by the BET method.

  In FIG. 4, it shows about the production | generation behavior of a solubilizate. Although a slight difference was observed between the samples, about 15 wt% of the raw material in fraction (1), about 25 wt% in fraction (2), and about 5 wt% in fraction (3) were solubilized. That is, 90% or more of the solubilized product has been produced so far by passing three fractions for 30 minutes.

  FIG. 5 shows an FPAE-PAD chromatogram of a 200 ° C. solubilized product of Moso bamboo as an example of the sugar analysis result of the solubilized product. It was confirmed that the solubilized product was mainly composed of xylose and xylooligosaccharide, which are hydrolysates of hemicellulose xylan. Similar analysis results were obtained for lysates of other samples.

  FIG. 6 shows the residue yield (reaction product yield) and the chemical component composition of the residue (reaction product). Residual yield was highest at rice husks of 56.1 wt%, followed by Moso bamboo 45.3 wt% and rice straw 40.2 wt%. Such a difference in yield is considered not only in the difference in the component composition of the raw material shown in FIG. 2, but also in the decomposition rate of the component. Therefore, the component composition of the treatment residue was examined and compared with the raw material. Looking at the main components, hemicellulose, cellulose and lignin, hemicellulose disappeared completely from the residue, and as a result, the concentration (content rate) of cellulose that was hardly decomposed was 1.7 to It became 2.0 times. The lignin concentration was reduced by 50% for rice straw and 35% for rice husk, compared to the raw material, but almost no change was observed for Moso bamboo. From the results of this experiment, the solubilization rate of lignin was calculated to be 78.5 wt% of rice straw, 63.2 wt% of rice husk, and 57.2 wt% of moso-chiku. .

  Furthermore, it was found that the alkali / alkaline earth metal contained in the residue (reaction product) was also reduced. When compared with content, Mosouchiku decreased 1.6 wt% to 0.4 wt%, and rice straw decreased 16.1 wt% to 10.4 wt%. In rice husks, 20.4 wt% increased in content rate to 24.5 wt%, but the reason is that hemicellulose was removed. Therefore, when the ratio of the weight percentage of alkali / alkaline earth metal (A) to the weight percentage of cellulose (C) is taken, A / C decreases from 0.038 to 0.0057 in Moso bamboo, 0.45 is reduced to 0.16, and 0.65 is reduced to 0.47 in rice husk.

  Therefore, for plant biomass such as bamboo with a relatively low content of alkali / alkaline earth metal, the content of alkali / alkaline earth metal is reduced to 0.5 by hydrothermal treatment (hydrothermal treatment, step 2). The clinker is hardly generated as a combustion fuel, and a fuel that is easy to burn can be provided. Moreover, the content rate of lignin with a high combustion temperature is also high enough, and the product derived from plant biomass suitable for the fuel for combustion can be provided.

  In addition, as a ratio of cellulose to cellulose, the ratio of alkali / alkaline earth metal (A / C) can be reduced to 0.01 or less, and further to 0.006 or less. It can be seen that plant-based biomass suitable as a raw material for biofuel and also suitable as a raw material for obtaining a functional material derived from plants such as bamboo fiber can be provided as a reaction product.

  For raw materials with a high alkali / alkaline earth metal content, such as rice husks, this treatment time has not reduced significantly, but by changing the hot water conditions or extending the treatment time, alkali / alkaline earths There is a possibility that the metal content can be further reduced. The same is true for rice straw. In this experiment, the content of alkali / alkaline earth metal was reduced to 10.4 wt%, and the clinker burned by changing the hot water conditions or extending the treatment time. There is a possibility that the content of alkali / alkaline earth metal can be reduced to 5 wt%, which is considered to be hardly hindered.

  As for rice straw, the ratio of alkali to alkaline earth metal (A / C) can be reduced to 0.2 or less, and further to 0.17 or less as the ratio of cellulose to cellulose. It can be seen that a product having a high cellulose content can be provided.

  FIG. 7 shows the collection rate of the solubilized product of Moso bamboo. As shown in this figure, by performing a total of 60 minutes (6 fractions) including heating and cooling, the production of the lysate was almost completed, and the cumulative lysate yield at this time was 50 It reached 5 wt%. The yield of the residue in the extraction container (reaction product) was 45.3 wt% on average of the results of three experiments.

  FIG. 8 shows a result of quantifying the alkali (Na, K) and alkaline earth (Mg, Fe) metal concentrations in the residue (reaction product) after collecting the dry residues together. Measurement of alkali and alkaline earth metal concentrations was performed as follows. In the former, about 3 g of the dried residue was placed in a 50 ml Falcon tube, 50 mL of 1% hydrochloric acid was added, and the mixture was extracted by shaking (at room temperature for 3 hours) and then filtered using filter paper. As for the latter, nitric acid and perchloric acid were added to 1 g of the residue, and wet ashing was performed (about 200 ° C. in a 300 ml tall beaker). Nitric acid and perchloric acid were stripped to dryness, dissolved in 50 ml Falcon tube with 1% hydrochloric acid, filled up with the same solution as appropriate, and analyzed by ICP emission spectrometry (Thermo). As shown in the analysis results, the concentrations of Na, K, Ca and Mg per 100 mg in the raw materials were 3, 566, 15 and 48 mg, respectively, but the hydrothermal residue was reduced to 1, 1, 2 and 0 mg. did.

  FIG. 9 shows the yield and specific surface area values of a product obtained by carbonizing a reaction product (hydrothermal treatment residue) of Moso bamboo at 600 ° C. and 800 ° C. for 1 hour. For comparison, the same experiment was performed for untreated raw materials, and the results are shown in FIG. Regarding the yield, the hydrothermal residue was lower in each condition. The specific surface area increased as the carbonization temperature increased, but almost no difference was observed between the samples. However, as described above, hemicellulose is completely eluted from the reaction product, and there is a possibility that the charcoal properties may be different, which is being verified.

  In plant biomass, the moisture content of the raw material is high, and the thermochemical reaction under gas phase conditions such as the semi-carbonization method is problematic from the viewpoint of energy balance due to the latent heat of evaporation of a large amount of water contained in the raw material. It was. On the other hand, hydrothermal treatment performed under high-temperature and high-pressure and liquid water does not require a drying process because the reaction is performed in the liquid phase, and generally uses plant biomass, which is often wet, as a raw material. Is considered energetically effective. In the pressurized hot water treatment method described above, it was found that hemicellulose was solubilized in its entirety regardless of the raw material, and further, alkaline and alkaline earth metals were eluted and decreased. On the other hand, since most of the cellulose was not solubilized and was recovered in the reaction product as a residue, it was found that the concentration could be increased to 1.7 to 2.0 compared to the raw material. This is considered very beneficial for cellulose utilization. Further, it was found that the lignin solubilization rate largely varies depending on the raw material, but remains in the reaction product at a sufficient ratio.

  The solubilized product is a low molecular weight product derived from hemicellulose xylan centering on xylose and xylooligosaccharide, suggesting the possibility of use as various functional foods and chemical raw materials.

DESCRIPTION OF SYMBOLS 10 Hydrothermal processing apparatus, 11 Pure water tank, 12 High pressure pump 14 Heat exchanger, 16 Tube extraction container, 18 Cooler, 20 Back pressure valve

Claims (10)

A method for modifying plant biomass,
The alkali and alkaline earth metal in the reaction product obtained by contacting the powdery plant biomass with hot water having a reaction temperature of 150 to 400 ° C. to separate, decompose, or carbonize at least one of hemicellulose, cellulose, and lignin. A method having reduced hydrothermal treatment. In claim 1,
The method, wherein the hot water is in a liquid state pressurized to at least a saturated vapor pressure at the reaction temperature. In claim 1 or 2,
The hot water treatment is any one of batch, semi-batch, and continuous, and includes performing solid-liquid separation for separating the reaction product from the hot water at the reaction temperature. In any of claims 1 to 3,
The plant biomass includes at least one of woody biomass, agricultural waste biomass, and bamboo. In any of claims 1 to 4,
The maximum length of the powdery plant biomass is 5 mm. A method for producing a plant fuel,
A method comprising reforming plant biomass for combustion by the reforming method according to any one of claims 1 to 5, and using the reaction product as a fuel. A method for producing carbide, comprising:
Reforming the plant biomass for carbonization by the reforming method according to any one of claims 1 to 5,
Carbonizing the reaction product at 500-900 ° C. under an inert gas. A plant fuel,
A plant fuel having a maximum content of alkali and alkaline earth metal of 5% or less. In claim 8,
The plant fuel is made from bamboo and has a maximum content of alkali and alkaline earth metal of 0.5%. A carbide raw material made from bamboo,
A carbide raw material having a total maximum content of alkali and alkaline earth metal of 0.5%.

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