Method for producing phenol using cnsl

Abstract

To provide a method for producing phenol from a biomass raw material, the method ensuring production of phenol with a high yield.SOLUTION: The present invention provides the use of CNSL whose principal component is cardanol as a feedstock for phenol production. The present invention also provides a method for producing phenol, comprising a dealkylation step in which the CNSL whose principal component is cardanol is dealkylated in the presence of a solid acid catalyst.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing phenol using CNSL (Cashew Nut Shell Liquid). [Background technology]

[0002] Phenol is widely used industrially as a direct raw material for bisphenol A and phenolic resins, which are processed into building materials for homes, molds for automobile engines, fireproof panels, molds for electronic components, and insulation materials.It is also a raw material for epoxy resins, which are used in paints and adhesives, and therefore its processed products are one of the substances that are deeply ingrained in everyday life.

[0003] The industrial production of phenol is based on the cumene process, a three-step synthesis reaction using benzene obtained from the refining of petroleum naphtha. In the cumene process, petroleum-derived benzene and propene are converted to cumene under acid catalysis, which is then autoxidized with oxygen to produce the peroxide intermediate cumene hydroperoxide. Finally, the peroxide intermediate is decomposed in the presence of concentrated sulfuric acid to obtain the desired phenol. However, the three-step process has problems such as low energy efficiency, the use of large amounts of organic solvents and heat energy, the use of concentrated sulfuric acid, the generation of by-products, and a significant environmental impact. Therefore, from the viewpoint of environmental conservation and greenhouse gas reduction, there is an urgent need to develop an environmentally friendly process for producing phenol from biomass resources.

[0004] For example, Patent Document 1 discloses a method for producing phenols by reacting a lignin decomposition product obtained by decomposing a lignin-containing material using an iron-containing catalyst and water in a flow reactor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-37354 Summary of the Invention [Problem to be solved by the invention]

[0006] Pyrolysis of plant biomass produces many decomposition products derived from cellulose, hemicellulose, lignin, oils, and other substances contained in the plant biomass. While these pyrolysis products contain useful organic compounds such as phenols, they also contain many other substances with little utility. To effectively utilize plant biomass, a simple method suitable for industrial application that enables the extraction of desired organic compounds from plant biomass is needed. However, in the method for producing phenols described in Patent Document 1, the raw material is a lignin decomposition product dissolved in a solvent, and therefore the obtained phenol derivative is a mixture of methoxyphenols, alkylphenols, cresols, etc., and the yield of unsubstituted phenol is low.

[0007] Therefore, an object of the present invention is to provide a method for producing phenol using biomass raw materials, which can produce phenol in high yield. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the inventors discovered that the above problems of the conventional technology can be solved by using CNSL, which is a biomass, as a raw material, and thus completed the present invention.

[0009] That is, the present invention is as follows. [1] Use of CNSL, whose main component is cardanol, as a raw material for phenol production. [2] A method for producing phenol, comprising a dealkylation step of dealkylating CNSL, which is mainly composed of cardanol, in the presence of a solid acid catalyst. [3] The method for producing phenol according to [2], wherein the solid acid catalyst is a zeolite. [4] The method for producing phenol according to [3], wherein the silica / alumina ratio (molar ratio) in the zeolite is 1 to 300. [5] The method for producing phenol according to [3] or [4], wherein the zeolite is an MFI type. [6] The method for producing phenol according to any one of [2] to [5], further comprising a hydrogenation step of hydrogenating the CNSL containing cardanol as a main component using hydrogen gas before the dealkylation step. [7] The method for producing phenol according to any one of [2] to [6], wherein the dealkylation reaction is a continuous reaction. [Effects of the Invention]

[0010] According to the present invention, a method for producing phenol using a biomass raw material can be provided, which can produce phenol in a high yield. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to the following content, and various modifications can be made within the scope of the gist thereof.

[0012] [CNSL (biomass feedstock)] CNSL, which is used as a biomass raw material for phenol production in this embodiment, will be described below. Cashews are a naturally occurring tropical plant, and their fruits, called cashew nuts, contain protein and carbohydrates and are used as snacks such as mixed nuts and in cooking. Cashew nuts are a natural fruit, and when harvested as a resource, they are a renewable biomass resource. The CNSL used in this embodiment, which is mainly composed of cardanol, is an oily liquid contained in the shells of cashew nuts, which are inedible parts obtained as a by-product when harvesting natural cashew nuts used for food.

[0013] Natural CNSL is a mixture of anacardic acid, cardanol, cardol, and 2-methylcardol, and each component is an organic compound consisting of a phenol moiety and a linear hydrocarbon moiety R, as shown in the following formulas (2) to (5). [ka] The linear hydrocarbon portion R of each component has one of the following structures: There are four types, each with 0, 1, 2, or 3 unsaturated bonds, and an average of two double bonds. R:-(CH2) 14 CH3 -(CH2)7CH=CH(CH2)5CH3 -(CH2)7CH=CHCH2CH=CH(CH2)2CH3 -(CH2)7CH=CHCH2CH=CHCH2CH=CH2 Each of the compounds represented by formulas (2) to (5) may be of one type or of two or more types with different R's.

[0014] The main component of natural CNSL is anacardic acid, as shown in formula (2) above. Such natural CNSL is decarboxylated for industrial use, resulting in cardanol, as shown in formula (3) above, as the main component. The proportions of each component contained in industrial CNSL vary depending on the place of origin, but are generally 70-80% by mass of cardanol (3), 15-25% by mass of cardol (4), and 5% by mass or less of 2-methyl cardol (5). The proportion of cardanol can be increased by distilling industrial CNSL. In this embodiment, the CNSL used as a raw material for phenol production is CNSL containing cardanol represented by the above formula (3) as a main component (i.e., containing 50% by mass or more of cardanol), and from the viewpoint of improving the phenol yield, the content of cardanol in the CNSL is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 80 to 100% by mass. If industrially processed CNSL containing cardanol as the main component, as shown in formula (3), has the desired composition, it can be used as the raw material for phenol production in this embodiment without distillation. Furthermore, even if natural CNSL or industrially processed CNSL is distilled to further increase the proportion of cardanol before use, a method with low separation power (e.g., simple distillation) can be selected, thereby reducing production energy and the cost required for preparing the raw material. In addition, the CNSL used as a raw material for phenol production in this embodiment may be a product in which the unsaturated bonds in the linear hydrocarbon moieties R in the side chains of the components represented by the above formulas (2) to (5) have been hydrogenated (hydrogenated) in advance.

[0015] <Phenol production method> The phenol production method of this embodiment is characterized by including a dealkylation step in which CNSL, which is mainly composed of cardanol, is used as a biomass feedstock and the CNSL is dealkylated in the presence of a solid acid catalyst. As the CNSL containing cardanol as the main component, those described in the above section [CNSL (biomass raw material)] can be used.

[0016] <Dealkylation Step> In the dealkylation step, dealkylation is carried out in the presence of a solid acid catalyst to eliminate the linear hydrocarbon moiety R from each of the components that constitute CNSL and are represented by the above formulas (2) to (5). During this process, cardanol represented by the above formula (3) is dealkylated to obtain phenol. In the phenol production method of this embodiment, the dealkylation reaction is carried out in a heterogeneous catalytic reaction using a solid acid catalyst, which facilitates a continuous flow reaction and allows phenol to be obtained in a high yield. In this specification, the term "solid acid catalyst" refers to an acid catalyst that is insoluble in the reaction solvent for the dealkylation reaction of this embodiment.

[0017] [Solid acid catalyst] The solid acid catalyst is not particularly limited as long as it can produce phenol by dealkylating the linear hydrocarbon portion of the side chain from cardanol in CNSL. Examples of the solid acid catalyst include metal salts of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and boric acid, alkali metal salts, alkaline earth metal salts, and the like; metal salts of sulfonic acids such as p-toluenesulfonic acid, alkali metal salts, alkaline earth metal salts, and the like; acidic cation exchange resins such as Amberlyst, Amberlite, and Diaion; zeolite, Al2O3, TiO2, ZrO2, SiO2-Al2O3, and S Examples include simple metal oxides and complex metal oxides such as iO2-MgO, SiO2-TiO2, Nb2O5, YNbO4, SnO2, In2O3, Ga2O3, WO3, MoO3, Ta2O5, CeO2, Nb2O5-WO3, Nb2O5-MoO3, TiO2-WO3, TiO2-MoO3, SiO2-Nb2O5, SiO2-Ta2O5, SiO2-ZrO2, WO3-ZrO2, and MoO3-ZrO2, clay, sulfuric acid-immobilized catalysts such as sulfated ZrO2, phosphoric acid-immobilized catalysts such as titania and niobia treated with phosphoric acid, and heteropolyacids. In addition, aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, and caproic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, aconitic acid, itaconic acid, oxaloacetic acid, fumaric acid, maleic acid, cyclopentanedicarboxylic acid, and cyclohexanedicarboxylic acid, aliphatic tricarboxylic acids such as cyclohexanetricarboxylic acid, aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, hemimellitic acid, mellophanic acid, prenitic acid, pyromellitic acid, benzenepentacarboxylic acid, and mellitic acid, and hydroxycarboxylic acids such as lactic acid, malic acid, citric acid, and tartaric acid. Salts of alkali metals or alkaline earth metals obtained by neutralizing at least a portion of an organic acid can also be used as solid acid catalysts. Among the above solid acid catalysts, zeolite is particularly preferable. These solid acid catalysts may be used alone or in combination of two or more. When two or more solid acid catalysts are used, the combination is not particularly limited, and each metal may have catalytic activity (co-catalyst), or may improve the catalytic activity of one or more metals (promoter).

[0018] [[Zeolite]] As used herein, "zeolite" refers to a crystalline substance in which tetrahedral TO4 units (T is a central atom such as Si or Al) are three-dimensionally linked by sharing oxygen atoms to form open, regular micropores. Specific examples of zeolites include silicates (aluminosilicates, gallosilicates, ferrisilicates, titanosilicates, borosilicates, etc.), phosphates (aluminophosphates, gallophosphates, beryllophosphates, etc.), germanates (aluminogermanates, etc.), and arsenates (aluminoarsenates, etc.), which are listed in the Data Collection of the Structure Committee of the International Zeolite Association (hereinafter referred to as "IZA").

[0019] (Zeolite structure) The structure of the zeolite is not particularly limited, but examples thereof include structures represented by AEL, EUO, FAU, FER, LTA, LTL, MEL, MFI, MTT, MWW, MOR, BEA, USY, TON, and WEI in the framework type code (FTC) defined by the IZA. Among these, zeolites having a structure represented by MFI are preferred. By using a zeolite having the above structure, the yield of phenol from CNSL tends to be further improved.

[0020] (Silica / alumina ratio of zeolite) The silica / alumina (SiO2 / Al2O3) molar ratio of the zeolite is preferably in the range of 1 to 300. From the viewpoint of improving the productivity of the zeolite and the phenol yield from CNSL, the silica / alumina molar ratio of the zeolite is more preferably 10 to 250, and further preferably 25 to 230. The silica / alumina molar ratio of a zeolite can be measured by a known method, for example, by completely dissolving the zeolite in an alkaline aqueous solution and analyzing the resulting solution by plasma emission spectroscopy or the like.

[0021] The method for preparing zeolite is not particularly limited, and known methods can be used. Note that the composition of zeolite can be changed by modification such as ion exchange, dealumination, impregnation, or support after hydrothermal synthesis. Commercially available zeolites can also be used. The zeolite may be supported with a metal component having hydrogenation activity (hereinafter, sometimes referred to as a "specific metal component"). The specific metal component is not limited as long as it exhibits hydrogenation ability, and examples thereof include nickel, cobalt, iron, ruthenium, ruthenium, osmium, palladium, platinum, gold, iridium, copper, zinc, silver, molybdenum, tungsten, chromium, manganese, rhenium, and mixtures thereof. The specific metal component can be used alone or in combination of two or more supported on zeolite. When two or more specific metal components are used, there are no particular limitations on the combination, mixing ratio, or form thereof, and the specific metal components can be used in the form of a mixture of individual metals, an alloy, or an intermetallic compound. The shape of the zeolite is not particularly limited, and may be powder or granular. The zeolite can be formed into a molded body by molding it into a shape appropriate for the process of producing phenol from CNSL. The method for molding the zeolite is not particularly limited, and known methods can be used.

[0022] The amount of the solid acid catalyst used does not necessarily have to be the same when a continuous reaction is carried out in a fixed bed reactor, a suspension bed reactor, or the like, but for example, per 100 parts by mass of CNSL, the lower limit is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and still more preferably 0.05 parts by mass or more, while the upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less.

[0023] As the solvent used in the dealkylation reaction, an organic solvent can be used as is commonly used. The organic solvent may be used alone or in combination of two or more kinds. The organic solvent is not particularly limited as long as it does not inhibit the reaction of producing phenol by dealkylating the linear hydrocarbon portion of the side chain from cardanol in CNSL. Examples of suitable organic solvents include diethyl ether, tetrahydrofuran (THF), tetrahydropyran, dipropyl ether, diisopropyl ether, methyl tert-butyl ether, butyl ether, pentyl ether, hexyl ether, octyl ether, nonyl ether, decyl ether, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether. ethers having 4 to 20 carbon atoms, such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclohexanone, 4-methyl-2-pentanone, 2-heptanone, 5-methyl-2-hexanone, 2,4-dimethylpentanone, 5-nonanone, 4-decanone, 5-decanone, 2-undecanone, 4-undecanone, 3-dodecanone, 2-tridecanone, 2-tetradecanone, 4-tetradecanone, 2-pentadecanone, and 3-pentadecanone Ketones having 4 to 20 carbon atoms, such as 7-pentadecanone, 2-hexadecanone, 3-hexadecanone, 4-hexadecanone, 6-hexadecanone, 2-heptadecanone, 4-heptadecanone, 9-heptadecanone, 3-octadecanone, and acetophenone; esters, such as ethyl acetate, propyl acetate, and butyl acetate; aliphatic alcohols, such as methanol, ethanol, propyl alcohol, and isopropyl alcohol; propylene glycol, octanediol, 1,3-butanediol, ethylene glycol, polyethylene glycol, glycerin, and D-sorbitol. aliphatic polyhydric alcohols such as ethanol, and aromatic aliphatic alcohols such as benzyl alcohol; phenols such as phenol, o-cresol, m-cresol, p-cresol, t-butylphenol, 2,4-dimethylphenol, and 2,6-dimethylphenol; saturated aliphatic hydrocarbon compounds having 3 to 12 carbon atoms such as pentane, hexane, cyclohexane, heptane, octane, nonane, decane, dodecane, and isododecane; aromatic hydrocarbons such as toluene, xylene, trimethylbenzene, 1,2,3,4-tetrahydronaphthalene, and 1-methylnaphthalene;Examples of suitable solvents include lactones such as γ-butyrolactone and γ-valerolactone; halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, tetrachloroethane, and hexachloroethane; and dimethylacetamide, N,N-dimethylformamide, N-methylmorpholine, N-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, tetramethylurea, dimethyl sulfoxide, sulfolane, isosorbide, isosorbide dimethyl ether, propylene carbonate, and mixtures thereof. Among these organic solvents, at least one selected from the group consisting of ethers, ketones, esters, alcohols, phenols, lactones, aromatic hydrocarbons, halogenated hydrocarbons, and saturated aliphatic hydrocarbon compounds is preferred.

[0024] (substrate concentration) The substrate concentration of the dealkylation reaction, i.e., the concentration of CNSL in the reaction system, is not particularly limited, but is preferably 0.1% by mass or more and 20.0% by mass or less, more preferably 0.5% by mass or more and 15.0% by mass or less, and even more preferably 1.0% by mass or more and 10.0% by mass or less. A substrate concentration of 0.1% by mass or more can increase the phenol production efficiency, while a substrate concentration of 20.0% by mass or less can further suppress the production of by-products and tend to suppress catalyst deterioration.

[0025] (Reaction type, reactor) The reaction method for dealkylating the linear hydrocarbon moiety in the side chain from cardanol in CNSL can be either a batch method or a flow method. In the flow method, either a flow method (fixed-bed flow method) reaction method or a stirred tank flow method is possible, but the flow method is preferred from the viewpoint of enabling continuous production of phenol. The description in this specification does not preclude changes to the reaction conditions to the extent that those skilled in the art can easily adjust them.

[0026] [Batch type] (Reaction temperature) The reaction temperature is not particularly limited, but may be, for example, in the range of 150°C to 350°C, 160°C to 340°C, or 170°C to 330°C. A reaction temperature of 150°C or higher tends to improve the reaction rate and further increase the yield of phenol. Furthermore, a reaction temperature of 350°C or lower tends to further suppress the generation of by-products and to suppress catalyst deterioration.

[0027] (reaction pressure) Regarding the reaction pressure, a high pressure is advantageous in terms of the reaction equilibrium of the dealkylation reaction of this embodiment, but a high pressure increases the equipment costs, etc., when carried out industrially, so the reaction pressure is preferably from atmospheric pressure to 10.0 MPa, more preferably from 0.1 MPa to 8.0 MPa. Here, atmospheric pressure means a pressure equal to atmospheric pressure.

[0028] (Reaction time) The reaction time is not particularly limited. For example, the lower limit may be 30 minutes or more, preferably 1 hour or more, and the upper limit may be 24 hours or less, preferably 12 hours or less.

[0029] (Addition of water) The amount of water added, relative to 100 parts by mass of CNSL, is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 1 part by mass or more, and the upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. By setting the amount of water added within the above range, sufficient catalytic activity can be obtained by suppressing coking.

[0030] [Flow type (fixed bed flow type)] (Weight space velocity (WHSV)) The weight hourly space velocity (WHSV) is the weight of the raw material flowing per hour relative to the weight of the catalyst packed in the reactor, and can be calculated using the following formula. WHSV[h -1 ] = Weight of raw material flowing per hour [g / h] / Catalyst filling weight [g] The WHSV can be adjusted appropriately based on the balance between productivity, catalyst life, and reaction yield. WHSV is preferably 0.1 to 5.0 h -1 More preferably, it is 0.3 to 4.5 hours. -1 More preferably, it is 0.5 to 4.0 h -1 WHSV is 0.1h -1 This reduces the amount of catalyst required to obtain a certain production amount, and allows the reactor to be made compact. -1 When the CNSL conversion rate is equal to or less than 100%, the phenol yield tends to be improved. The conversion rate of CNSL is the ratio ((ab) / a×100) of the total mass (a) of CNSL added to the reaction system up to the time of measurement minus the mass (b) of CNSL remaining in the reaction system at the time of measurement to the total mass (a).

[0031] (Reaction temperature) The reaction temperature is not particularly limited, but is preferably in the range of 270°C or higher and 350°C or lower. A reaction temperature of 270°C or higher tends to improve the reaction rate and further improve the phenol yield. Furthermore, a reaction temperature of 350°C or lower tends to further suppress the production of by-products and to suppress catalyst deterioration.

[0032] (reaction pressure) Although a higher pressure is advantageous in terms of the reaction equilibrium of the dealkylation reaction of this embodiment, a higher pressure increases the equipment costs and the like when the reaction is carried out industrially. Therefore, the reaction pressure is preferably from atmospheric pressure to 10 MPa, more preferably from atmospheric pressure to 8 MPa. Here, atmospheric pressure means a pressure equal to atmospheric pressure.

[0033] (Reaction time) The reaction time is not particularly limited. For example, the lower limit may be 30 minutes or more, or 1 hour or more, and the upper limit may be 24 hours or less, or 12 hours or less, but is not limited thereto.

[0034] (Addition of water) The amount of water added is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of CNSL. The upper limit is not particularly limited, and may be, for example, 1000 parts by mass or less. By adding water, sufficient catalytic activity can be obtained by suppressing coking.

[0035] [Hydrogenation (hydrogen addition) process] In the phenol production method of this embodiment, the raw material CNSL may be subjected to a hydrogenation step in which unsaturated bonds (double bonds) in the linear hydrocarbon moieties in the side chains of each component are hydrogenated (hydrogenated) using hydrogen gas, and then the CNSL may be subjected to the dealkylation step. Among the four cardanol analogue components with different numbers of unsaturated bonds in the side chains, removing the unsaturated bonds by hydrogenation can significantly improve the phenol yield. The reason why the phenol yield is improved by hydrogenating the unsaturated bonds in the side chains of cardanol is that when cardanol is used as a substrate, competition occurs in the dealkylation of the side chains, leading to Brønsted acid-catalyzed decomposition of the unsaturated bonds in the side chains, followed by the generation of polycyclic phenols through cyclization of short-chain alkylphenols and the blockage of catalyst pores due to coke generation from the cleaved unsaturated alkyl chains. However, hydrogenating the unsaturated bonds in the side chains can suppress the occurrence of these phenomena.

[0036] The method for hydrogenating (hydrogenating) CNSL is not particularly limited, and any conventional method can be used. The hydrogenation of CNSL is preferably carried out in the presence of a catalyst. The hydrogenation catalyst used in this embodiment is not particularly limited, but examples thereof include a catalyst containing a metal element (specific metal component) having catalytic hydrogenation ability as an active ingredient.

[0037] Examples of the specific metal component include nickel, cobalt, iron, ruthenium, ruthenium, osmium, palladium, platinum, gold, iridium, copper, zinc, silver, molybdenum, tungsten, chromium, manganese, rhenium, and mixtures thereof. The specific metal component may be in a metallic state or a cationic state as long as it exhibits hydrogenation ability, and among these, the metallic state may be preferred in some cases due to its high hydrogenation ability and high stability under a reducing atmosphere. The specific metal component can be used alone or in combination of two or more types contained in the solid catalyst. When two or more specific metal components are used, there are no particular limitations on the combination, mixing ratio, or form thereof, and the specific metal components can be used in the form of a mixture of individual metals, an alloy, or an intermetallic compound. The raw materials for these specific metal components are not particularly limited, and those used as raw materials when preparing catalysts by conventionally known methods can be used. Examples of such raw materials include hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, ammine complexes, and carbonyl complexes of the respective metal elements. These may be used alone or in combination of two or more.

[0038] The hydrogenation catalyst used in this embodiment may use a specific metal component as the metal component either alone or in combination with a metal that does not have catalytic hydrogenation ability. Examples include catalysts such as palladium black and platinum black, which are composed of fine metal powder of the specific metal component, and sponge catalysts, which are prepared by forming an alloy from the specific metal component, aluminum, and a small amount of additive, and then leaching all or part of the aluminum.

[0039] In order to further improve the activity, selectivity, physical properties, etc. of the catalyst, compounds of one or more elements selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium as alkali metal elements, magnesium, calcium, strontium, and barium as alkaline earth metal elements, fluorine, chlorine, bromine, and iodine as halogen elements, and aluminum, gallium, germanium, silicon, lead, bismuth, tin, tellurium, and antimony as auxiliary additive elements (hereinafter, sometimes referred to as "specific additive components") can also be added to the catalyst together with the specific metal components described above. The raw materials for these specific additive components are not particularly limited, and those used as raw materials when preparing catalysts by conventionally known methods can be used. Examples of such raw materials include hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, and ammine complexes of the respective metal elements. These may be used alone or in combination of two or more. There are also no particular limitations on the method of adding the specific additive component and the ratio of the specific additive component to the specific metal component.

[0040] In the hydrogenation catalyst used in this embodiment, the specific metal component may be combined with a non-metallic substance. Examples of the non-metallic substance include, for example, elemental substances, carbides, nitrides, oxides, hydroxides, sulfates, carbonates, and phosphates (hereinafter, sometimes referred to as "specific non-metallic components"). Specific examples thereof include graphite, diamond, activated carbon, silicon carbide, silicon nitride, aluminum nitride, boron nitride, boron oxide, aluminum oxide (alumina), silicon oxide (silica), titanium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, cerium oxide, yttrium oxide, niobium oxide, magnesium silicate, calcium silicate, magnesium aluminate, calcium aluminate, zinc oxide, chromium oxide, aluminosilicate, aluminosilicophosphate, aluminophosphate, polyphosphate, magnesium phosphate, calcium phosphate, strontium phosphate, hydroxyapatite (calcium hydroxyphosphate), apatite chloride, apatite fluoride, calcium sulfate, barium sulfate, and barium carbonate. One specific nonmetallic component may be used alone, or two or more may be used in combination. When two or more kinds are used in combination, the combination, mixing ratio, and form are not particularly limited, and they can be used in the form of a mixture of individual compounds, a composite compound, a double salt, etc. From the viewpoint of industrial use, the specific non-metallic component that can be obtained easily and inexpensively is preferred.

[0041] As the hydrogenation catalyst, a specific metal component may be used alone, or a specific metal component and a specific non-metal component may be used in combination, and in some cases, a specific additive component may be contained in addition to these.

[0042] The method for producing the hydrogenation catalyst is not particularly limited, and a conventionally known method can be used. Examples thereof include a method of impregnating a raw material compound of a specific metal component onto a specific nonmetallic component (support method), a method of dissolving a raw material compound of a specific metal component and a raw material compound of a specific nonmetallic component together in an appropriate solvent and then simultaneously precipitating them using an alkali compound or the like (coprecipitation method), and a method of uniformly mixing a raw material compound of a specific metal component and a specific nonmetallic component in an appropriate ratio (kneading method). Furthermore, there are no particular limitations on the metal content and shape of the hydrogenation catalyst. The shape may be powder or molded, and there are no particular limitations on the shape and molding method when molded. For example, spherical products, tablet-molded products, extrusion-molded products, and shapes obtained by crushing these products to an appropriate size can be appropriately selected and used.

[0043] The metal content in the hydrogenation catalyst is not particularly limited, but the lower limit, expressed as a mass percentage converted to metal, relative to the total mass of the catalyst may be 0.1 mass% or more, preferably 0.5 mass% or more, more preferably 1 mass% or more, and the upper limit may be 50 mass% or less, preferably 20 mass% or less, more preferably 10 mass% or less. By keeping the metal content within the above range, sufficient catalytic activity can be obtained. In the following description of the catalyst, the value written as mass% indicates the metal content relative to the total mass of the catalyst.

[0044] The lower limit of the amount of the hydrogenation catalyst used, relative to 100 parts by mass of CNSL, is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 1 part by mass or more, while the upper limit is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less.

[0045] The hydrogen gas pressure is not particularly limited, and the reaction can be carried out under pressurized hydrogen gas conditions. The hydrogen gas pressure during the hydrogenation reaction may be, for example, 0.1 MPa or more at its lower limit, preferably 0.3 MPa or more, and more preferably 0.4 MPa or more at its upper limit, preferably 15 MPa or less, preferably 20 MPa or less, more preferably 5 MPa or less, and even more preferably 3 MPa or less. Generally, increasing the reaction pressure promotes the supply of hydrogen to the hydrogenation catalyst and improves the reaction rate. However, carrying out the reaction at high pressure requires special equipment such as a reactor with enhanced pressure resistance, and the increased hydrogenation capacity may lead to hydrocracking. Examples of the reaction solvent include water, hydrocarbons, esters, ethers, and alcohols, and these may be used alone or in combination of two or more.

[0046] (Reaction temperature) The reaction temperature in the hydrogenation reaction is not particularly limited, but for example, the lower limit may be 20°C or higher, preferably 50°C or higher, and more preferably 90°C or higher, and the upper limit may be 350°C or lower, preferably 250°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower.

[0047] (Reaction time) The reaction time of the hydrogenation reaction is not particularly limited. It is usually 30 minutes or more, preferably 1 hour or more, more preferably 3 hours or more, and usually 24 hours or less, preferably 12 hours or less, more preferably 5 hours or less. However, when the hydrogenation reaction is carried out continuously, the reaction time is not limited to this.

[0048] (Reaction Apparatus) The reactor used in the hydrogenation reaction is not particularly limited, and for example, a high-pressure reactor capable of high-pressure reaction can be used. A continuous reactor can also be used, and the reaction can be carried out by filling the reactor with a catalyst and circulating the raw material liquid and hydrogen gas. In the case of a continuous reactor, a catalyst separation step is not required, and a continuous reactor is preferable for mass production.

[0049] [Phenol recovery method] The phenol obtained in the dealkylation step may be recovered after isolation and / or purification after completion of the reaction, or may be used as a raw material in a production step of another compound without undergoing isolation and / or purification steps. When the phenol is used as a raw material for another step without isolation / purification, if the reaction is carried out as a batch reaction, the reaction solution after completion of the reaction may be introduced directly into the reactor for the other step, or phenol may be extracted from the reaction solution after completion of the reaction using a different organic solvent and the extract may be introduced into the reactor for the other step. Also, if the reaction is carried out as a flow reaction, the reaction solution may be passed directly through the reactor for the other step in a flow reaction process, or the reaction solution may be contacted with a different organic solvent to extract phenol, and the extract may be introduced into the reactor for the other step.

[0050] On the other hand, when isolating / purifying the phenol obtained in the dealkylation step, the phenol can be recovered by, for example, a solvent distillation method, a method of extracting with an organic solvent after solvent distillation, a distillation method, a sublimation method, a crystallization method, or a chromatography method. [Example]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0052] [Phenol yield (analysis conditions for gas chromatography)] The yield of phenol in the examples and comparative examples was calculated as an area percentage by analyzing the obtained product by gas chromatography (hereinafter also referred to as "GC"). The analytical conditions for GC are as follows: Device: GC-2025 (Shimadzu Corporation) Column: DB-5ms (Agilent Technologies) Length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 μm Column temperature: Adjust to 50°C, hold at 50°C for 5 minutes, increase to 325°C at 10°C / min, hold at 325°C for 2 minutes 30 seconds Injection temperature: 350℃ Carrier gas: Helium gas Detector: Flame ionization detector (FID)

[0053] [CNSL conversion rate] A portion of the reaction solution in each example was collected as a sample, and the concentration of CNSL remaining in the sample was measured using GC to determine the mass (b) of CNSL remaining in the reaction solution.The conversion rate (%) was calculated using this mass (b) and the total mass (a) of CNSL added up to the time the sample was collected using the formula (ab) / a×100.The GC analysis conditions were as follows: Device: GC-2025 (Shimadzu Corporation) Column: DB-5ms (Agilent Technologies) Length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 μm Column temperature: Adjust to 50°C, hold at 50°C for 5 minutes, increase to 325°C at 10°C / min, hold at 325°C for 2 minutes 30 seconds Injection temperature: 350℃ Carrier gas: Helium gas Detector: Flame ionization detector (FID)

[0054] (batch type) [Examples B1 to B8 and Comparative Example B1] 1 g of CNSL ("NX-2026" manufactured by Cardrite) was dissolved in 8.64 g of toluene, and 0.36 g of water was added. 0.5 g of catalyst was added to this solution, and the dealkylation reaction was carried out in a batchwise manner under stirring at a reaction temperature of 300°C, a reaction time of 2 hours, a reaction pressure of 4 MPa, and a nitrogen atmosphere. The phenol yield was determined for the resulting product. The type of solid acid catalyst used in each example is as shown in Table 1 (however, the silicalite used in Comparative Example 1 is not a solid acid catalyst as defined in this specification). The measurement results are shown in Table 1.

[0055] [Example B9 and Example B12] 1 g of CNSL ("NX-2026" manufactured by Cardrite Co., Ltd.) was dissolved in 9 g of toluene, and in the presence of 50 mg (5 parts by mass relative to 100 parts by mass of CNSL) of Ru / C (Ru content in the hydrogenation catalyst: 5% by mass) as a hydrogenation catalyst, hydrogen gas was injected at 1 MPa and nitrogen gas at 3 MPa in an autoclave, and the hydrogenation reaction was carried out at 260°C for 2 hours. The hydrogenation rate (hydrogenation rate) calculated using a gas chromatography with a flame ionization detector (GC-FID) ("GC-2010" manufactured by Shimadzu Corporation) was 72.3%. Thereafter, the hydrogenated CNSL was used to carry out a dealkylation reaction in the same manner as in Example B1. The types of solid acid catalysts used in each example are as shown in Table 1. The measurement results are shown in Table 1.

[0056] [Examples B10, B11 and B13] 2.5 g of CNSL ("NX-2026" manufactured by Cardrite Co., Ltd.) was dissolved in 2.5 g of toluene, and in the presence of 0.125 g (5 parts by mass relative to 100 parts by mass of CNSL) of Ru / Al2O3 (Ru content in the hydrogenation catalyst: 5% by mass) as a hydrogenation catalyst, hydrogen gas was injected at 1 MPa in an autoclave, and the hydrogenation reaction was carried out at 80°C for 1 hour. The hydrogenation rate calculated using GC-FID ("GC-2010" manufactured by Shimadzu Corporation) was 99.3%. Thereafter, the hydrogenated CNSL was used to carry out a dealkylation reaction in the same manner as in Example B1. The types of solid acid catalysts used in each example are as shown in Table 1. The measurement results are shown in Table 1.

[0057] [Table 1]

[0058] In Example B11, the dealkylation reaction was carried out using a 10% by mass toluene solution of hydrogenated CNSL. However, when the concentration of hydrogenated CNSL was changed to 5%, 2%, or 1% by mass and the dealkylation reaction was carried out in the same manner as in Example B11, the phenol yields were 55.6%, 66.4%, and 64.3%, respectively.

[0059] (flow type) [Examples F1 to F5] A 52.8 mg amount of the solid acid catalyst shown in Table 2 was loaded into a flow reactor, and a dealkylation reaction was carried out in a flow reactor under the following conditions. The phenol yield and CNSL conversion rate were determined for the resulting product. The measurement results are shown in Table 2. (Reaction conditions) Temperature (reactor): 300℃ Pressure (reactor): Atmospheric pressure ·Flow rate (nitrogen): 25mL / min ·Flow rate (raw material solution): 83.33μL / min ·Flow rate (water): 5.152μL / min ·Raw material concentration: 5.0% by mass (WHSV: 4.1h -1 ), 2.5% by mass (WHSV:2.1h -1 ), or 1.0 mass% (WHSV: 0.8h -1 )

[0060] [Table 2] [Industrial Applicability]

[0061] According to the production method of the present invention, phenol can be obtained in high yield from CNSL, which is a biomass raw material and contains cardanol as its main component, and therefore the method is expected to serve as a phenol production process that can replace existing petrochemical processes.

Claims

1. Use of CNSL, which is primarily composed of cardanol, as a raw material for phenol production.

2. A method for producing phenol, comprising a dealkylation step of dealkylating CNSL, which is mainly composed of cardanol, in the presence of a solid acid catalyst.

3. The method for producing phenol according to claim 2, wherein the solid acid catalyst is a zeolite.

4. 4. The method for producing phenol according to claim 3, wherein the silica / alumina ratio (molar ratio) in the zeolite is 1 to 300.

5. 4. The method for producing phenol according to claim 3, wherein the zeolite is of the MFI type.

6. The method for producing phenol according to any one of claims 2 to 5, further comprising a hydrogenation step of hydrogenating the CNSL containing cardanol as a main component using hydrogen gas prior to the dealkylation step.

7. The method for producing phenol according to any one of claims 2 to 5, wherein the dealkylation reaction is a continuous reaction.

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