Method for producing decomposition product

Abstract

Provided is a method for producing a decomposition product from lignocellulosic biomass, the method comprising a step for heating the lignocellulosic biomass at a temperature of 250°C to 500°C inclusive in the presence of a metal element catalyst. The step is performed in the absence of hydrogen at atmospheric pressure or reduced pressure, and the decomposition product contains at least one selected from the group consisting of an aromatic monomer and a product gas.

Description

Method for producing decomposition products

[0001] The present disclosure relates to methods for producing decomposition products.

[0002] Biomass, especially lignocellulosic biomass, has attracted attention from the viewpoints of preventing global warming and achieving carbon neutrality. Because lignocellulosic biomass is an abundant carbon source, producing carbon compounds from lignocellulosic biomass is important from the viewpoint of biorefinery.

[0003] Patent Document 1 (Japanese Patent Laid-Open Publication No. 2024-27327) discloses a method for obtaining aromatic monomers by decomposing lignin in the presence of a catalyst within a predetermined temperature range.

[0004] Non-Patent Document 1 (Vineet Singh Sikarwar et al. "An overview of advances in biomass gasification" Energy & Environmental Science, 2016, 9, pp. 2939-2977) discloses gasification from biomass (biomass gasification).

[0005] JP 2024-27327 A

[0006] Vineet Singh Sikarwar et al. "An overview of advances in biomass gasification" Energy & Environmental Science, 2016, 9, p2939-2977

[0007] In the method of Patent Document 1, the decomposition is carried out in the presence of hydrogen, and therefore the reaction must be carried out in a closed system.

[0008] According to Non-Patent Document 1, the gasification of woody biomass usually requires a reaction at a high temperature of 700° C. or higher. In addition, there are problems such as equipment malfunctions due to the by-product tar and catalyst deactivation.

[0009] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a method for obtaining decomposition products from lignocellulosic biomass in high yield.

[0010] [1] A method for producing decomposition products from lignocellulosic biomass, comprising a step of heating the lignocellulosic biomass at 250°C or higher and 500°C or lower in the presence of a metal element catalyst, the step being carried out in the absence of hydrogen and under atmospheric pressure or reduced pressure, and the decomposition products comprising at least one selected from the group consisting of aromatic monomers and product gases.

[0011] [2] The method for producing a decomposition product according to [1], wherein the decomposition product contains the aromatic monomer and the product gas.

[0012] [3] The method for producing a decomposition product according to [1] or [2], wherein the decomposition product contains the aromatic monomer and carbon monoxide.

[0013] [4] The method for producing a decomposition product according to any one of [1] to [3], wherein the decomposition product contains the aromatic monomer, carbon monoxide, and hydrogen.

[0014] [5] The method for producing a decomposition product according to any one of [1] to [4], wherein the lignocellulosic biomass is woody biomass.

[0015] [6] The method for producing a decomposition product according to any one of [1] to [5], wherein the metal element catalyst is a palladium catalyst supported on solid carbon.

[0016] According to the present disclosure, a method for obtaining decomposition products from lignocellulosic biomass in high yield can be provided.

[0017] Figure 1 is a schematic diagram showing a reaction pathway for producing decomposition products from lignocellulosic biomass. Figure 2 is a schematic diagram showing an example of an apparatus used in the production method of the present disclosure. Figure 3 is a graph showing an example of the yield of aromatic monomers obtained by decomposition of lignocellulosic biomass. Figure 4 is a graph showing an example of the yield of carbon monoxide and other gases obtained by decomposition of lignocellulosic biomass. Figure 5 is a graph showing an example of the relative composition of carbon monoxide and other gases obtained by decomposition of lignocellulosic biomass.

[0018] Embodiments of the present disclosure are described in detail below. A method for producing decomposition products from lignocellulosic biomass in the present disclosure includes a step of heating lignocellulosic biomass at 250°C or higher and 500°C or lower in the presence of a metal element catalyst. The step is carried out in the absence of hydrogen and under atmospheric pressure or reduced pressure. The decomposition products include at least one selected from the group consisting of aromatic monomers and product gases.

[0019] (Lignocellulosic biomass) Lignocellulosic biomass is biomass whose main component is lignocellulose. Lignocellulose is a component of plant cell walls and contains lignin, cellulose, and hemicellulose. Examples of lignocellulosic biomass include woody biomass, herbaceous biomass, processed products thereof, and waste products thereof.

[0020] Examples of woody biomass include broad-leaved trees and coniferous trees. Examples of broad-leaved trees include maple, oak, sawtooth oak, yew, beech, and horse chestnut. Examples of coniferous trees include pine, cedar, cypress, hemlock, Abies sachalinensis, and larch. Coniferous trees are more difficult to decompose than broad-leaved trees. From this perspective, broad-leaved trees are preferred as woody biomass.

[0021] Examples of woody biomass waste and processed materials include bark, branches, fruit bunches, and fruit shells from broad-leaved and coniferous trees. Also, processed materials such as plywood and fiberboard made from broad-leaved and coniferous trees can be used. Also, dismantled parts after use can be used.

[0022] Examples of herbaceous biomass include rice, wheat, sugarcane, pineapple, sugarcane, oil palm, corn, bamboo, and bamboo grass.

[0023] From the viewpoint of ease of decomposition, lignocellulose biomass is preferably pulverized (for example, wood flour).

[0024] (Cracked Products) Cracking products in the present disclosure include aromatic monomers and product gases.

[0025] FIG. 1 is a schematic diagram showing a reaction pathway for producing decomposition products from lignocellulosic biomass. Referring to FIG. 1, lignin contained in lignocellulosic biomass is converted into aromatic compounds having radicals and unsaturated side chains by heating. The converted aromatic compounds are mainly converted into aromatic monomers by the action of a metal catalyst. Meanwhile, cellulose and hemicellulose contained in lignocellulosic biomass are converted into product gases by heating in the presence of a metal catalyst. Cellulose and hemicellulose are polysaccharide components containing many hydroxyl groups, and they also generate active hydrogen species necessary for stabilizing and depolymerizing lignin-derived radicals and aromatic compounds having unsaturated side chains. Therefore, reactions that were previously performed in the presence of hydrogen can now be performed in the absence of hydrogen.

[0026] [Aromatic Monomer] The aromatic monomer refers to an aromatic compound having one aromatic ring. As described above, the aromatic monomer is an aromatic compound as a segment obtained by decomposition of lignin contained in lignocellulosic biomass.

[0027] The aromatic monomer is not particularly limited as long as it is an aromatic compound having one aromatic ring, and examples thereof include aromatic monomers having a syringyl nucleus (S nucleus), aromatic monomers having a guaiacyl nucleus (G nucleus), and aromatic monomers having a catechol nucleus (C nucleus). Examples of aromatic monomers having an S nucleus include syringol (S) (boiling point: 261°C), methyl syringol (Me-S) (boiling point: 268°C), ethyl syringol (Et-S) (boiling point: 273°C), and propyl syringol (Pr-S) (boiling point: 285°C). Examples of aromatic monomers having a G nucleus include guaiacol (G) (boiling point: 205°C), methyl guaiacol (Me-G) (boiling point: 221°C), ethyl guaiacol (Et-G) (boiling point: 221°C), and propyl guaiacol (Pr-G) (boiling point: 264°C). Examples of aromatic monomers having a C nucleus include catechol (boiling point: 245° C.), ethyl catechol (Et-C) (boiling point: 273° C.), etc. These aromatic monomers can be separated into various aromatic monomers by conventional methods.

[0028] [Product Gas] Product gas is obtained by decomposition of cellulose and hemicellulose contained in lignocellulosic biomass.

[0029] The generated gases include, for example, carbon monoxide (CO), carbon dioxide (CO ２ ), hydrocarbon gas, hydrogen (H ２ Examples of hydrocarbon gases include methane gas (CH ４ ), acetylene gas (C ２ H ２ ), ethylene gas (C ２ H ４ ), ethane gas (C ２ H ６ ), propylene gas (C ３ H ６ ), propane gas (C ３ H ８ ) etc.

[0030] In this disclosure, the product gases are primarily CO and H ２ CO and H are produced. ２is expected to be a raw material for petroleum synthesis and methane synthesis, and CO derived from biomass is particularly ２ It is expected that this will lead to a reduction in

[0031] (Step) The method for producing a decomposition product of the present disclosure includes a step of decomposing lignocellulosic biomass in the presence of a metal element catalyst at 250° C. or higher and 500° C. or lower. The step is carried out in the absence of hydrogen and under atmospheric pressure or reduced pressure.

[0032] [Metal element catalyst] The metal element catalyst used in this step is not particularly limited as long as it can perform the step. Examples of the metal element catalyst include catalysts containing metal elements such as palladium (Pd), platinum (Pt), and ruthenium (Ru). From the viewpoint of increasing the yield of the mixture, the metal element catalyst is preferably a catalyst supported on solid carbon, and more preferably a palladium catalyst (catalyst containing Pd) supported on solid carbon (Pd / C). Here, solid carbon refers to solid carbon, and from the viewpoint of increasing catalytic activity, porous carbon with a large surface area, such as activated carbon, is preferred.

[0033] [Temperature] The temperature in this step is 250°C or higher and 500°C or lower. From the viewpoint of increasing the yield of decomposition products, particularly the yield of low-boiling-point aromatic monomers, the temperature in this step may be 300°C or higher, or 350°C or higher. Furthermore, from the viewpoint of suppressing thermal degradation of the apparatus and secondary decomposition of the aromatic monomers, the temperature in this step may be 450°C or lower, or 400°C or lower.

[0034] [Time] The time for this step is not particularly limited, but may be 10 minutes or more, 30 minutes or more, or 60 minutes or more from the viewpoint of increasing the yield of the decomposition product. Furthermore, the time for this step may be 180 minutes or less, 150 minutes or less, or 120 minutes or less from the viewpoint of suppressing thermal degradation of the device.

[0035] [Hydrogen] This step is carried out in the absence of hydrogen, under normal pressure or reduced pressure. In this step, aromatic monomers are obtained by decomposition of lignin as described above. It is believed that the decomposition of lignin involves thermal decomposition followed by hydrocracking. Therefore, it is believed that the presence of hydrogen promotes hydrocracking.

[0036] On the other hand, decomposition of lignin in the presence of hydrogen requires a closed system. Carrying out this process in a closed system poses limitations, such as the need to pressurize the hydrogen and the need to use equipment that can be used in closed systems. Furthermore, hydrogen has issues such as being easily ignited, embrittling metal materials, and being expensive.

[0037] As described above, lignocellulosic biomass contains cellulose and hemicellulose, which are polysaccharides containing hydroxyl groups. Because these hydroxyl-containing components are decomposed and function as active hydrogen species, this process can be carried out in the absence of hydrogen. Furthermore, because hydrogen is not present, this process does not need to be carried out in a closed system. In other words, this process is carried out under normal pressure or reduced pressure, eliminating the above-mentioned limitations.

[0038] This step may be carried out in the absence of hydrogen, for example, in an inert atmosphere or in the air, such as in the presence of nitrogen or argon.

[0039] [Solvent] This step may be carried out by immersing the lignocellulosic biomass and the metal element catalyst in a solvent. Examples of the solvent include organic solvents that dissolve the aromatic monomer. From the viewpoint of separation from the aromatic monomer, the organic solvent is preferably one that has a boiling point higher than that of the aromatic monomer, and an aprotic organic solvent is more preferred. Examples of such organic solvents include eicosane (boiling point: 343°C), triacontane (boiling point: 450°C), 1,3-diphenoxybenzene (boiling point: 375°C), and 1,3,5-triphenylbenzene (boiling point: 460°C).

[0040] However, the use of a solvent in this step may lead to a decrease in efficiency, since it is necessary to separate the aromatic monomer from the solvent, and it is necessary to distill and remove the solvent each time this step is carried out, etc. Therefore, even when a solvent is used in this step, it is preferable to reduce the amount used.

[0041] [Apparatus] The apparatus for carrying out this step is not particularly limited as long as it can carry out this step. For example, referring to FIG. 2, apparatus 10 includes a gas bag 1, a reactor 2, and a heating mechanism 3. Lignocellulosic biomass, a metal element catalyst, and, if necessary, a solvent are added to reactor 2, and the mixture is heated by heating mechanism 3 to obtain a decomposition product. The aromatic monomer is contained in the solution obtained by recovering the residue in reactor 2 after completion of the reaction, filtering, and extracting with an organic solvent. The gas product is contained in gas bag 1.

[0042] From the viewpoint of promoting the reaction, a rotor may be placed in the reactor 2 and the contents may be stirred by a magnetic stirrer 4. When this step is carried out in the presence of nitrogen, the reactor 2 may be closed with a lid 5. When this step is carried out in the atmosphere, the reactor 2 may be open.

[0043] (Effects) From the above, the present disclosure is expected to have the following effects: That is, all components contained in lignocellulosic biomass are converted into aromatic monomers, CO, and H ２ The reaction can be converted into useful chemicals such as cellulose acetate, cellulose acetate, and cellulose acetate. By using lignocellulosic biomass as a raw material, the reaction can proceed without the presence of a hydrogen catalyst. Since hydrogen is not required, the reaction can be carried out under normal pressure or reduced pressure, and the products can be volatilized and recovered while the lignocellulosic biomass is continuously introduced.

[0044] Examples are described below. However, the following examples do not limit the scope of the claims. (No. 1) A decomposition apparatus having the configuration shown in Figure 2 was prepared. 100 mg of beech wood flour was prepared as lignocellulosic biomass, and 0.6 g of 1,3-diphenoxybenzene was prepared as a solvent. The beech wood flour and 1,3-diphenoxybenzene were added to a reactor, a rotor was inserted, and the reactor was then filled with nitrogen to create a closed environment. The reactor was heated to 350°C using the heating mechanism, and the mixture was stirred for 30 minutes using a magnetic stirrer, whereby the beech wood flour was decomposed.

[0045] Nitrogen was introduced from the bottom of reactor 2, and the gas remaining in reactor 2 was transferred to gas bag 1 containing neon as an internal standard. The composition and yield of each gas in the gas product were measured by micro gas chromatography. The obtained heat-denatured beech wood flour was filtered and extracted with an ethyl acetate-containing aqueous solution (ethyl acetate:water = 1:1 (volume ratio)) to obtain an ethyl acetate-soluble product, a water-soluble product, and a solid residue. The molecular weight of each aromatic monomer in the ethyl acetate-soluble product was measured by gel permeation chromatography (GPC), and the yield of each aromatic monomer was measured by gas chromatography / mass spectrometry (GC / MS). The results are shown in Tables 2 to 4 and Figures 3 to 5. Table 1 shows the materials and test conditions used in No. 1 and Nos. 2 to 13, which will be described later.

[0046] (No. 2) 25 mg of palladium catalyst supported on solid carbon (Pd / C) (Pd content of the entire catalyst: 5% by mass) (Nacalai Tesque, Inc., Product No. 25910) was prepared as a metal element catalyst. The other points were the same as in No. 1.

[0047] Beech wood flour was decomposed under the same conditions as in Experiment No. 1, except that beech wood flour, 1,3-diphenoxybenzene, and Pd / C were added to the reactor. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as in Experiment No. 1. The results are shown in Tables 2 to 4 and Figures 3 to 5.

[0048] (Nos. 3 to 5) Beech wood flour was decomposed using the same material as No. 2, except that the conditions were changed as shown in Table 1. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as No. 1. The results are shown in Tables 2 to 4 and Figures 3 to 5.

[0049] (No. 6) 100 mg of cedar wood flour (manufactured by Naka Wood Co., Ltd.) was prepared as lignocellulosic biomass. Other than that, decomposition of the cedar wood flour was carried out under the same conditions as in No. 1. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as in No. 1. The results are shown in Tables 2 to 4 and Figures 3 to 5.

[0050] (No. 7) Cedar wood flour was decomposed under the same conditions as No. 2, except that cedar wood flour was used as the lignocellulosic biomass. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as No. 1. The results are shown in Tables 2 to 4 and Figures 3 to 5.

[0051] (Nos. 8 to 10) Cedar wood flour was decomposed using the same materials as No. 7, except that the conditions were changed as shown in Table 1. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as No. 1. The results are shown in Tables 2 to 4 and Figures 3 to 5.

[0052] (No. 11) 25 mg of beech ground lignin (Buna MWL) was prepared as a raw material. Otherwise, the decomposition of Buna MWL was carried out under the same conditions as in No. 2. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as in No. 1. The results are shown in Table 2 and Figure 3.

[0053] (No. 12) 33 mg of ground cedar lignin (cedar MWL) was prepared as the raw material. Other than that, decomposition of cedar MWL was carried out under the same conditions as in No. 2. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as in No. 1. The results are shown in Table 2 and Figure 3. As mentioned above, product gas is obtained by decomposition of cellulose and hemicellulose, so no product gas was obtained from beech MWL or cedar MWL.

[0054] (No. 13) 100 mg of cellulose (Avicel®) was prepared. Otherwise, cellulose decomposition was carried out under the same conditions as in No. 2. The composition and yield of each gas in the gas product, as well as the molecular weight and yield of each aromatic monomer in the ethyl acetate solution, were measured using the same methods as in No. 1. The results are shown in Tables 3 and 4 and Figures 4 and 5. As mentioned above, aromatic monomers are obtained by decomposition of lignin, so aromatic monomers were not obtained from cellulose.

[0055] In Table 2, aromatic monomers are derived from the benzene rings of lignin contained in lignocellulosic biomass. In Tables 3 and 4, product gases are derived from carbon in cellulose and hemicellulose contained in lignocellulosic biomass. In Table 2, "DHSA" represents dihydrosinapyl alcohol, "IS" represents 4-propenylsyringol, "VS" represents syringaldehyde, "DHCA" represents dihydroconiferyl alcohol, "EG" represents eugenol, "IG" represents trans-isoeugenol, "Cis-IG" represents cis-isoeugenol, and "VG" represents vanillin.

[0056]

[0057]

[0058]

[0059]

[0060] In No. 1, the yield of aromatic monomers, which are cracked products, and the product gas (CO) was lower than in Nos. 2 to 5. In addition, compared with Nos. 2 to 5, the yield of H ２ Almost no production was observed.

[0061] In Nos. 2 and 3, the yields of aromatic monomers, which are cracked products, and the product gas (CO) were higher in No. 3 than in No. 2. ２ The production rate of No. 3 was also higher than that of No. 2.

[0062] In Nos. 4 and 5, the yield of aromatic monomers, which are cracked products, was higher in No. 4 than in No. 5, and the yield of product gas (CO) and H ２ The production rate of No. 5 was higher than that of No. 4.

[0063] In No. 6, the yield of aromatic monomers, which are cracked products, and the product gas (CO) was lower than in Nos. 7 to 10. In addition, compared with Nos. 7 to 10, the yield of H ２ Almost no production was observed.

[0064] In Nos. 7 and 8, the yield of aromatic monomers, which are decomposition products, was higher in No. 8 than in No. 7. In addition, the yield of product gas (CO) and H ２ There was almost no difference in the production rate.

[0065] There was almost no difference in the yield of aromatic monomers, which were decomposition products, between Nos. 9 and 10. In addition, the yield of product gas (CO) and H ２ The production rate of No. 10 was higher than that of No. 9.

[0066] The yields of aromatic monomers and product gas (CO), which are decomposition products, were lower in Nos. 1 and 6, which did not use a metal element catalyst, than in Nos. 2 to 5 and Nos. 7 to 10. This is thought to be because the decomposition of lignin, cellulose, and hemicellulose did not progress.

[0067] No product gas was obtained in Nos. 11 and 12. Product gas is obtained by the decomposition of cellulose and hemicellulose, so it is thought that it was not obtained from beech MWL or cedar MWL. Furthermore, no aromatic monomers were obtained in No. 13. Aromatic monomers are obtained by the decomposition of lignin, so it is thought that they were not obtained from cellulose.

[0068] The above examples confirmed that the method for producing cracked products of the present disclosure makes it possible to obtain aromatic monomers and product gas (CO) in high yields.

[0069] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0070] 1 gas bag, 2 reactor, 3 heating mechanism, 4 magnetic stirrer, 5 lid, 10 apparatus.

Claims

1. A method for producing decomposition products from lignocellulosic biomass, comprising a step of heating the lignocellulosic biomass at 250°C or higher and 500°C or lower in the presence of a metal element catalyst, the step being carried out in the absence of hydrogen and under atmospheric pressure or reduced pressure, and the decomposition products comprising at least one selected from the group consisting of aromatic monomers and product gases.

2. The method for producing a decomposition product according to claim 1, wherein the decomposition product comprises the aromatic monomer and the product gas.

3. The method for producing a decomposition product according to claim 1 or 2, wherein the decomposition product comprises the aromatic monomer and carbon monoxide.

4. A method for producing a decomposition product according to any one of claims 1 to 3, wherein the decomposition product comprises the aromatic monomer, carbon monoxide, and hydrogen.

5. A method for producing a decomposition product according to any one of claims 1 to 4, wherein the lignocellulosic biomass is woody biomass.

6. A method for producing a decomposition product according to any one of claims 1 to 5, wherein the metal element catalyst is a palladium catalyst supported on solid carbon.

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