JP2017052717A - Method for producing aromatic compounds - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce aromatic compounds from lignin, in order to realize a society without fossil fuel corresponding to reduction of carbon dioxide emission as well as depletion and price hike of fossil fuel resources, and to diversify carbon resources.SOLUTION: The method for producing aromatic compounds includes a process of decomposing lignin contained in a lignin-containing material in supercritical water at a temperature of 374°C to 500°C and a pressure of 22 MPa to 60 MPa in the presence of a catalyst containing at least one selected from palladium, platinum, ruthenium, and nickel. The lignin-containing material may be a byproduct obtained from a pulp manufacturing process, a residue obtained from a saccharization process, or a residue obtained from a saccharide/alcohol production process by hydrocracking. The catalyst may further contain a carrier such as active charcoal, carbon black, or graphite.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an aromatic compound that decomposes lignin in a lignin-containing material, and more specifically, using supercritical water as a solvent and at least selected from palladium, platinum, ruthenium, and nickel. The present invention relates to a method for efficiently producing an aromatic compound from a lignin-containing material using a catalyst containing one kind.

  In order to reduce carbon dioxide emissions, realize a defossil fuel society that responds to depletion of fossil fuel resources and soaring prices, and diversification of carbon resources, there is a global demand for the production of useful materials from renewable resources. Yes. Since it is possible to produce chemical substitutes for plastics currently made from petroleum, it is required to develop technologies for utilizing biomass, which is a carbon resource. Plant biomass is mainly composed of cellulose, hemicellulose, and lignin. Many conversion reactions of cellulose and hemicellulose contained in herbaceous biomass and woody biomass into chemical raw materials have been reported.

  Non-Patent Document 1 describes a method for producing a sugar alcohol such as sorbitol or xylitol from cellulose or hemicellulose contained in cedar wood flour. However, lignin has poor reactivity and is difficult to convert into a chemical raw material. Patent Document 1 describes a method for producing an aromatic compound such as benzene or toluene by heat-treating lignin in the presence of a metal-supported zeolite. However, in the method for producing an aromatic compound described in Patent Document 1, a large amount of coke is generated.

  Patent Document 2 describes a method of producing phenols by reacting a lignin decomposition product obtained by decomposing a material containing lignin using an iron-containing catalyst and water in a flow reactor. . However, in the method for producing phenols described in Patent Document 2, the raw material is a lignin decomposition product dissolved in a solvent. For this reason, it is difficult to produce phenols using a solid lignin-containing material as a raw material. Further, according to the description of Non-Patent Document 2, in the method for producing phenols described in Patent Document 2, coke is generated on the catalyst.

Japanese Patent Application Laid-Open No. 2011-127022 JP 2014-37354 A

A. Yamaguchi, O .; Sato, N .; Mimura, Y. et al. Hirosaki, H .; Kobayashi, A .; Fukuoka, M .; Shira, Catalysis Communications, 54 (2014) p. 22-26 T. T. Yoshikawa, S .; Shinohara, T .; Yagi, N .; Ryumon, Y. et al. Nakasaka, T .; Tago, T .; Masuda, Applied Catalysis B, 146 (2014) p. 289-297

  The problem to be solved by the present invention is to provide a method for producing an aromatic compound which uses a lignin-containing material in a solid form or in a solution as a raw material and hardly produces coke as a byproduct.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that coke is hardly produced as a by-product in the presence of a catalyst containing at least one selected from palladium, platinum, ruthenium, and nickel. It has been discovered that aromatic compounds can be obtained from lignin-containing materials in critical water.

The present invention for solving the above-described problems comprises the following technical means.
(1) A method for producing an aromatic compound comprising a step of decomposing lignin in a lignin-containing product in supercritical water in the presence of a catalyst containing at least one selected from palladium, platinum, ruthenium, and nickel.
(2) The method according to (1), wherein the lignin-containing material is biomass.
(3) The lignin-containing material is at least one selected from a by-product obtained in the pulp production process, a residue obtained in the saccharification process, and a residue obtained in the sugar alcohol production process by hydrogenolysis. the method of.
(4) The method according to any one of (1) to (3), wherein the catalyst further comprises at least one carrier selected from activated carbon, carbon black, and graphite.
(5) The method according to (1) to (4), wherein lignin is decomposed at a temperature of 374 ° C to 500 ° C.
(6) The method according to (1) to (5), wherein lignin is decomposed at a pressure of 22 MPa to 60 MPa.

  According to the present invention, an aromatic compound can be obtained from a lignin-containing material with almost no coke as a by-product.

  Hereinafter, the manufacturing method of the aromatic compound of this invention is demonstrated in detail based on embodiment and an Example. A duplicate description will be omitted as appropriate. In addition, when “to” is described between two numerical values to represent a numerical range, the two numerical values are also included in the numerical range.

  The method for producing an aromatic compound according to an embodiment of the present invention includes a step of decomposing lignin in a lignin-containing material in supercritical water in the presence of a catalyst containing at least one selected from palladium, platinum, ruthenium, and nickel. Have. Palladium, platinum, ruthenium, or nickel may be supported on the carrier. Palladium, platinum, ruthenium, or nickel supported on the carrier may be an oxide or hydroxide in addition to the metal.

  The support may be either inorganic or organic as long as it is stable under the reaction conditions, such as activated carbon, carbon black, graphite, zirconia, alumina, silica, zeolite, metal oxide, and composite metal oxide. It can be used as a carrier. Among these, at least one selected from activated carbon, carbon black, and graphite, which has a large specific surface area and is extremely stable under the reaction conditions of the lignin-containing material in supercritical water, is preferable. The catalyst is preferably one in which at least one metal fine particle selected from palladium, platinum, ruthenium and nickel is supported on a carrier, or one in which fine particles mixed with these metals are supported on a carrier, but in addition to these metals For example, the catalyst may contain rare earth elements, transition metals, noble metals, alkaline earth metals, alkali elements, halogen elements and the like.

  The ratio of the mass of these metals to the mass of the support is preferably 0.01% to 40%. This is because it exhibits high activity in the production of aromatic compounds. If the ratio of the mass of these metals to the mass of the support is less than 0.01%, sufficient catalytic activity cannot be obtained, and the amount of aromatic compounds produced is reduced. It becomes larger and the activity per metal atom decreases. The shape of the catalyst of the present embodiment is not particularly limited, and may be any shape such as powder or molded product.

  The catalyst used in the production method of the present embodiment can be prepared, for example, as follows. First, palladium-containing solutions such as palladium chloride, dinitrodiammine palladium and palladium acetate, platinum-containing solutions such as dinitrodiamine platinum, platinum chloride and tetrachloroplatin, ruthenium-containing solutions such as nitrosylruthenium nitrate and ruthenium chloride, or nickel chloride and nitric acid The support is impregnated with a nickel-containing solution such as nickel. Instead of this impregnation, these solutions may be sprayed onto the support. When preparing a catalyst in which these metals are mixed, the mixed solution of metals is impregnated or sprayed, or sequentially impregnated or sprayed. Next, the obtained metal-containing support is sequentially dried, calcined, and reduced to obtain a metal-supported catalyst. Note that the firing step and the reduction step may be omitted.

  Supercritical water is water at a temperature above the critical temperature and at a pressure above the critical pressure. The critical temperature of water is 374 ° C., and the critical pressure of water is 22 MPa. Examples of the lignin-containing material used in the production method of the present embodiment include woody biomass chips such as cedar, cypress, eucalyptus, and acacia, or plant biomass chips such as bagasse, rice straw, empty fruit bunches, and corn. It is done. These biomass contains cellulose and hemicellulose. In order to effectively use cellulose and hemicellulose, the lignin-containing material may be a substance produced as a by-product by processing these biomasses.

  Substances produced as a by-product of processing biomass include by-products obtained in the pulp production process, that is, by-products mainly composed of lignin obtained in the pulp production process for using, for example, cellulose of woody biomass as pulp. The product, the residue mainly composed of lignin obtained in the saccharification process of biomass containing cellulose, and the lignin obtained in the sugar alcohol production process such as sorbitol and xylitol by hydrogenolysis of cellulose and hemicellulose in the biomass Residue. Examples of the reactor used in the production method of the present embodiment include a batch type, a fixed bed flow type, and a fluid bed flow type reactor, but there is no particular limitation.

  The manufacturing method of this embodiment is performed in the following procedures. First, a catalyst, water, and a raw material lignin-containing material are placed in a reactor. At this time, the inside of the reactor may be filled with nitrogen, helium, argon, methane, carbon dioxide or the like. Next, it heats and pressurizes so that the inside of a reactor may become predetermined temperature and pressure. And the lignin in a lignin containing material decomposes | disassembles and an aromatic compound produces | generates by maintaining the inside of a reactor at this predetermined temperature and pressure. The predetermined temperature is, for example, 374 ° C. to 500 ° C., and preferably 374 ° C. to 420 ° C. Even if lignin is decomposed at a temperature exceeding 500 ° C., an aromatic compound is obtained, but energy consumption increases.

  Further, the predetermined pressure is, for example, 22 MPa to 60 MPa, and preferably 22 MPa to 40 MPa. Even if lignin is decomposed under a pressure exceeding 60 MPa, an aromatic compound can be obtained, but the production cost of the reactor increases. Examples of the aromatic compound obtained by decomposing lignin include benzene, phenol, ethylbenzene, propylbenzene, dibenzyl, p-cresol, m-cresol, 4-ethylphenol, and 3-ethylphenol.

  The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples. Note that “%” is “mass%” unless otherwise specified.

Example 1 (Preparation of 4% Pt / C catalyst)
A dinitrodiamine platinum aqueous solution (manufactured by Furuya Metal Co., Ltd.) and carbon black (BP2000, manufactured by Cabot Corporation) were mixed to obtain a slurry so that the amount of platinum supported was 4% of the catalyst. This slurry was stirred for 12 hours, water was evaporated by a rotary evaporator, and then dried by a dryer at 100 ° C. for 10 hours to obtain a powder. This powder was subjected to reduction treatment under conditions of 400 ° C. for 2 hours under flowing hydrogen to obtain a 4% Pt / C catalyst.

Example 2 (Preparation of 3% Ru · 1% Pt / C catalyst)
A mixed solution of a ruthenium nitrate aqueous solution (manufactured by Strem Chemicals) and a dinitrodiamine platinum aqueous solution (manufactured by Furuya Metal Co., Ltd.), carbon black, so that the ruthenium loading is 3% of the catalyst and the platinum loading is 1% of the catalyst. (BP2000, manufactured by Cabot Corporation) was mixed to obtain a slurry. This slurry was stirred for 12 hours, water was evaporated by a rotary evaporator, and then dried by a dryer at 100 ° C. for 10 hours to obtain a powder. This powder was subjected to reduction treatment under conditions of 400 ° C. for 2 hours under a hydrogen flow to obtain a 3% Ru · 1% Pt / C catalyst.

Example 3 (Preparation of 2.5 Pt · 2.5% Pd / C catalyst)
A dinitrodiamine platinum aqueous solution (Fluya Metal Co., Ltd.) and palladium chloride (Wako Pure Chemical Industries, Ltd.) were used so that the ruthenium loading was 2.5% of the catalyst and the palladium loading was 2.5% of the catalyst. The mixed solution was mixed with high surface area graphite (HSAG300, manufactured by TIMCAL) or activated carbon (manufactured by Wako Pure Chemical Industries) to obtain a slurry. This slurry was stirred for 12 hours, water was evaporated by a rotary evaporator, and then dried by a dryer at 100 ° C. for 10 hours to obtain a powder. This powder was reduced under conditions of 400 ° C. for 2 hours under hydrogen flow to obtain 2.5% Pt · 2.5% Pd / graphite and 2.5% Pt · 2.5% Pd / activated carbon. .

Example 4 (Preparation of 20% Ni / C catalyst)
A nickel chloride (manufactured by Wako Pure Chemical Industries, Ltd.) aqueous solution and carbon black (BP2000, manufactured by Cabot Corporation) were mixed to obtain a slurry so that the amount of nickel supported was 20% of the catalyst. This slurry was stirred for 12 hours, water was evaporated by a rotary evaporator, and then dried by a dryer at 100 ° C. for 10 hours to obtain a powder. This powder was reduced under conditions of 400 ° C. for 2 hours under hydrogen flow to obtain a 20% Ni / C catalyst.

Example 5 (Aromatic compound production from cedar, 4% Pt / C catalyst)
First, in a stainless steel reactor having an internal volume of 100 cm ³ , 0.3 g of 4% Pt / C catalyst, 0.324 g of cedar and 40 mL of water were placed, and the air in the reactor was replaced with hydrogen. Introduced. This cedar was composed of 41% cellulose, 25% hemicellulose, and 33% lignin, and was pulverized by a ball mill for 48 hours. Next, the reactor was heated at 190 ° C. for 16 hours to produce sugar alcohol by hydrogenolysis of cedar.

  Then, after cooling the reactor, it was separated into a liquid containing a water-soluble product and a solid containing mainly unreacted catalyst and cedar by filtration. By this reaction, cellulose and hemicellulose in cedar reacted to produce sugar alcohols shown in Table 1. The main component of the unreacted cedar contained in the solid, that is, the residue obtained in the sugar alcohol production process by hydrogenolysis of cellulose and hemicellulose was lignin.

Next, this solid substance is put into a stainless steel batch reactor having an internal volume of 6 cm ³ , and water is introduced into the reactor so that the amount of water is 3 mL together with the moisture contained in the solid substance. The air in the vessel was replaced with argon. And this reactor was heated up to 400 degreeC using the molten salt bath. The pressure in the reactor at this time was 37 MPa. And the reactor was heated at 400 degreeC for 1 hour, the lignin in this residue was decomposed | disassembled, and the aromatic compound was manufactured. Then, after the reactor was cooled with water, the product and solids in the reactor were recovered with tetrahydrofuran, and separated into a liquid containing a tetrahydrofuran-soluble product and a solid containing a catalyst as a main component by filtration.

  Next, this liquid was analyzed by gas chromatography (GC-FID). The results are shown in Table 1. The numerical values in Table 1 are the mass (mg) of sugar alcohol or aromatic compound obtained from 1 g of cedar which is raw material biomass. Aromatic compounds such as phenol, benzene, ethylbenzene, propylbenzene, and dibenzyl were obtained from the residue obtained during the sugar alcohol production process by hydrogenolysis of cellulose and hemicellulose. The solid containing the catalyst as a main component was dried and reused in Example 6 below.

  As shown in Example 5 of Table 1, by treating cedar and 4% Pt / C in the presence of hydrogen at 190 ° C. for 16 hours, sugar alcohols such as sorbitol were produced from cellulose and hemicellulose in cedar. Aromatic compounds such as benzene, phenol, ethylbenzene, propylbenzene, and dibenzyl were produced by decomposing the remaining lignin in supercritical water at 400 ° C. in the presence of 4% Pt / C catalyst.

Example 6 (Aromatic compound production from cedar, reuse of 4% Pt / C catalyst)
As in Example 5, except that a solid substance mainly composed of the catalyst recovered in Example 5 was used as a catalyst for sugar alcohol production reaction by hydrogenolysis of cellulose and hemicellulose and decomposition reaction of lignin. An aromatic compound was produced from cedar. The results are shown in Table 1. As shown in Example 6 of Table 1, this catalyst could be used repeatedly by adding new cedar as a raw material. It has been found that useful chemicals can be produced from cellulose, hemicellulose, and lignin, which are all components of cedar.

Example 7 (Aromatic compound production from bagasse, 4% Pt / C catalyst)
An aromatic compound was produced from bagasse in the same manner as in Example 5 except that the cedar of Example 5 was changed to bagasse. This bagasse was composed of 37% cellulose, 31% hemicellulose, and 22% lignin, and was crushed by a ball mill for 48 hours. The results are shown in Table 2.

  As shown in Example 7 of Table 2, bagasse and 4% Pt / C were treated in the presence of hydrogen at 190 ° C. for 16 hours to produce sugar alcohols such as sorbitol from cellulose and hemicellulose in the bagasse. Aromatic compounds such as benzene, phenol, ethylbenzene, propylbenzene, and dibenzyl were produced by decomposing the remaining lignin in supercritical water at 400 ° C. in the presence of 4% Pt / C catalyst.

Example 8 (Aromatic compound production from bagasse, reuse of 4% Pt / C catalyst)
As in Example 7, except that the solids mainly composed of the catalyst recovered in Example 7 were used as the catalyst for the sugar alcohol production reaction by hydrogenolysis of cellulose and hemicellulose and the decomposition reaction of lignin. An aromatic compound was produced from bagasse. The results are shown in Table 2.

Example 9 (Aromatic compound production from bagasse, reuse of catalyst)
As a catalyst for the saccharification reaction of cellulose and hemicellulose, and the decomposition reaction of lignin, a solid material mainly composed of the catalyst recovered in Example 8 was used as in Example 7 to produce aromatics from bagasse. The compound was prepared. The results are shown in Table 2. As shown in Example 8 and Example 9 in Table 2, this catalyst could be used repeatedly by adding new bagasse as a raw material. Moreover, it turned out that a useful chemical substance can be manufactured from cellulose, hemicellulose, and lignin which are all the components of bagasse which is herbaceous biomass similarly to cedar which is woody biomass.

Example 10 (Aromatic compound production from cedar, 3% Ru · 1% Pt / C catalyst)
Similar to Example 5, except that 0.3 g of the 4% Pt / C catalyst in Example 5 was changed to 0.2 g of 3% Ru · 1% Pt / C catalyst. The compound was prepared. The results are shown in Table 3.

  As shown in Example 10 of Table 3, by treating cedar and 3% Ru · 1% Pt / C in the presence of hydrogen at 190 ° C. for 16 hours, sugar alcohols such as sorbitol are converted from cellulose and hemicellulose in cedar. Generated. In Example 10, compared with Example 5, many sugar alcohols produced | generated. Aromatic compounds such as benzene, phenol, ethylbenzene, propylbenzene, and dibenzyl were produced by decomposing the remaining lignin in supercritical water at 400 ° C. in the presence of 3% Ru · 1% Pt / C.

Example 11 (Aromatic compound production from cedar, 20% Ni / C catalyst)
An aromatic compound was produced from cedar in the same manner as in Example 5 except that 0.3 g of the 4% Pt / C catalyst in Example 5 was changed to 0.3 g of 20% Ni / C catalyst. The results are shown in Table 3. As shown in Example 11 in Table 3, cedar and 20% Ni / C were treated in the presence of hydrogen at 190 ° C. for 16 hours to produce sugar alcohols such as sorbitol from cellulose and hemicellulose in the cedar. Aromatic compounds such as phenol, p-cresol, m-cresol, 4-ethylphenol, and 3-ethylphenol are decomposed in supercritical water at 400 ° C. in the presence of 20% Ni / C. Generated. When a 20% Ni / C catalyst was used, many aromatic compounds having a phenolic hydroxyl group such as phenol were obtained.

Example 12 (Production of direct aromatic compound from cedar, 4% Pt / C catalyst)
First, 0.2 g of 4% Pt / C catalyst, 0.2 g of cedar, and 3 mL of water were placed in a stainless batch reactor having an internal volume of 6 cm ³ , and the air in the reactor was replaced with argon. The cedar, which is a raw material containing lignin, was composed of 41% cellulose, 25% hemicellulose, and 33% lignin, and was pulverized by a ball mill for 48 hours. The reactor was then heated to 400 ° C. using a molten salt bath. The pressure in the reactor at this time was 37 MPa.

  And the reactor was heated at 400 degreeC for 1 hour, the lignin in cedar was decomposed | disassembled, and the aromatic compound was manufactured. Next, after the reactor was cooled with water, the product and solids in the reactor were collected with tetrahydrofuran, and separated into a liquid and a solid containing a tetrahydrofuran-soluble product by filtration. And this liquid was analyzed by gas chromatography (GC-FID). The results are shown in Table 4. Aromatic compounds such as phenol, benzene, ethylbenzene, and propylbenzene were obtained from cedar.

  As shown in Example 12 of Table 4, phenol, p-cresol, m-cresol, 4-ethylphenol, by treating cedar in supercritical water at 400 ° C. in the presence of 4% Pt / C catalyst, And aromatic compounds such as 3-ethylphenol were produced. By using cedar as a raw material, the amount of phenol produced was increased compared to Example 5. In addition, many aromatic compounds having a phenolic hydroxyl group such as cresol and ethylphenol were produced.

Example 13 (Production of direct aromatic compound from cedar, 3% Ru · 1% Pt / C catalyst)
An aromatic compound was produced from cedar in the same manner as in Example 12, except that the 4% Pt / C catalyst in Example 12 was changed to a 3% Ru · 1% Pt / C catalyst. The results are shown in Table 4. As shown in Example 13 of Table 4, it was found that an aromatic compound was produced from cedar in the presence of 3% Ru · 1% Pt / C catalyst.

Example 14 (Production of aromatic compounds directly from bagasse, 4% Pt / C catalyst)
An aromatic compound was produced from bagasse in the same manner as in Example 12, except that the cedar of Example 12 was changed to bagasse. The results are shown in Table 4.

Example 15 (Production of aromatic compounds directly from bagasse, 3% Ru1% Pt / C catalyst)
An aromatic compound was produced from bagasse in the same manner as in Example 14 except that the 4% Pt / C catalyst in Example 14 was changed to a 3% Ru · 1% Pt / C catalyst. The results are shown in Table 4. As shown in Example 14 and Example 15 in Table 4, it was found that an aromatic compound was produced even when the raw material was bagasse.

Examples 16 to 20 and Comparative Example 1 (Aromatic compound production from organosolv lignin)
First, a stainless steel batch reactor having an internal volume of 6 cm ³ was charged with 0.1 g of the catalyst shown in Table 5, organosolv lignin (manufactured by Aldrich), and 3 mL of water, and the air in the reactor was replaced with argon. . The reactor was then heated to 400 ° C. using a molten salt bath. The pressure in the reactor at this time was 37 MPa. And the reactor was heated at 400 degreeC for 1 hour, the organosolv lignin was decomposed | disassembled and the aromatic compound was manufactured.

  Next, after the reactor was cooled with water, the product and solids in the reactor were collected with tetrahydrofuran, and separated into a liquid and a solid containing a tetrahydrofuran-soluble product by filtration. And this liquid was analyzed by gas chromatography (GC-FID). The results are shown in Table 5. From organosolv lignin, aromatic compounds such as phenol, p-cresol, m-cresol, 4-ethylphenol, and 3-ethylphenol were obtained.

  As shown in Example 16 to Example 20 in Table 5, by decomposing organosolv lignin in supercritical water at 400 ° C. in the presence of a catalyst containing at least one of palladium, platinum, and ruthenium, phenol, p Aromatic compounds such as -cresol, m-cresol, 4-ethylphenol, and 3-ethylphenol were produced. In Comparative Example 1, an aromatic compound was produced without using a catalyst, but the obtained aromatic compound was remarkably few. As shown in Example 18 of Table 5, the most phenol was produced when 2.5% Pt · 2.5% Pd / graphite was used.

Examples 20 to 23, Comparative Examples 1 to 4 (type of raw material lignin and decomposition time)
First, 0.15 g of 5% Pd / C (manufactured by Wako Pure Chemical Industries, Ltd.) catalyst, organosolv lignin (manufactured by Aldrich) or dealkalized lignin (Tokyo Kasei) in a stainless steel batch reactor having an internal volume of 6 cm ^3. 0.1 g of Kogyo Co., Ltd. and 3 mL of water were added, and the air in the reactor was replaced with argon. The reactor was then heated to 400 ° C. using a molten salt bath. The pressure in the reactor at this time was 37 MPa. The reactor was heated at 400 ° C. for 1 hour or 2 hours to decompose lignin and produce an aromatic compound.

  Next, after the reactor was cooled with water, the product and solids in the reactor were collected with tetrahydrofuran, and separated into a liquid and a solid containing a tetrahydrofuran-soluble product by filtration. And this liquid was analyzed by gas chromatography (GC-FID). The results are shown in Example 20 to Example 23 in Table 6. A variety of aromatic compounds such as phenol, p-cresol, m-cresol, 4-ethylphenol, and 3-ethylphenol were obtained from various lignins. Moreover, the experiment which manufactured the aromatic compound without using the 5% Pd / C catalyst used in Example 20- Example 23 was made into Comparative Example 1- Comparative Example 4, respectively, and the liquid containing a tetrahydrofuran soluble product was gas. Analyzed by chromatography (GC-FID). The results are shown in Comparative Examples 1 to 4 in Table 6.

  As shown in Example 20 to Example 23 of Table 6, by decomposing organosolv lignin or dealkalized lignin in supercritical water at 400 ° C. in the presence of 5% Pd / C catalyst, phenol, p-cresol, Aromatic compounds such as m-cresol, 4-ethylphenol, and 3-ethylphenol were produced. From Example 20 and Example 22, when organosolv lignin was used as a raw material, the amount of aromatic compounds produced increased when the reaction time was 2 hours compared to when the reaction time was 1 hour. Moreover, from Example 21 and Example 23, when dealkal lignin was used as a raw material, the production amount of the aromatic compound hardly changed between the reaction time of 1 hour and 2 hours. Furthermore, as shown in Comparative Example 1 to Comparative Example 4 in Table 6, when the aromatic compound was produced without using the catalyst, compared with the case where the 5% Pd / C catalyst of Example 20 to Example 23 was used. Thus, the obtained aromatic compound was remarkably small.

  According to the method for producing an aromatic compound of the present invention, an aromatic compound can be efficiently obtained from a lignin-containing material. In addition, sugar alcohol can be produced from cellulose and hemicellulose contained in woody biomass and herbaceous biomass, and an aromatic compound can be produced from lignin contained in the residue. Furthermore, according to the method for producing an aromatic compound of the present invention, the catalyst can be reused. The method for producing an aromatic compound of the present invention can be used as a very useful technique in various fields such as the chemical industry, the petrochemical industry, the pharmaceutical industry, and the effective use of biomass. .

Claims (6)

  A method for producing an aromatic compound, comprising a step of decomposing lignin in a lignin-containing material in supercritical water in the presence of a catalyst containing at least one selected from palladium, platinum, ruthenium, and nickel.   The method for producing an aromatic compound according to claim 1, wherein the lignin-containing material is biomass.   The fragrance according to claim 2, wherein the lignin-containing material is at least one selected from a by-product obtained in a pulp production process, a residue obtained in a saccharification process, and a residue obtained in a sugar alcohol production process by hydrogenolysis. Group compound production method.   The method for producing an aromatic compound according to any one of claims 1 to 3, wherein the catalyst further contains at least one support selected from activated carbon, carbon black, and graphite.   The method for producing an aromatic compound according to any one of claims 1 to 4, wherein lignin is decomposed at a temperature of 374C to 500C.   The method for producing an aromatic compound according to any one of claims 1 to 5, wherein lignin is decomposed at a pressure of 22 MPa to 60 MPa.