Method for producing phenol

Abstract

The object of the present invention is to provide a method for producing phenol using biomass raw materials that can yield phenol in high yield. [Solution] The present invention provides a method for producing phenol, characterized by obtaining phenol by performing two or more dealkylation reactions in the presence of a solid acid catalyst from CNSL, which is mainly composed of cardanol.

Description

[Technical Field]

[0001] The present invention relates to a method for producing phenol. [Background Art]

[0002] Phenol is industrially widely used as a direct raw material for bisphenol A and phenolic resins that are processed into building materials, molds for automobile engines, molds for fireproof panels and electronic parts, heat insulating materials, etc., and is also a raw material for epoxy resins used in paints, adhesives, etc. Therefore, it is one of the substances whose processed products deeply penetrate into daily life.

[0003] The industrial production method of phenol is based on the cumene method, which is a three-stage synthesis reaction using benzene obtained from the purification of petroleum naphtha as a raw material. In the cumene method, under the conditions of an acid catalyst, benzene and propene derived from petroleum are reacted to be converted into cumene, and then auto-oxidized with oxygen to obtain the peroxide intermediate cumene hydroperoxide. Finally, the target phenol is obtained by decomposing the peroxide intermediate in the coexistence of concentrated sulfuric acid. However, in addition to the low energy efficiency by the three-step process, the use of a large amount of organic solvents and a large amount of thermal energy, the use of concentrated sulfuric acid, and the generation of by-products, the large environmental load is also a problem. Therefore, from the viewpoints of environmental protection and greenhouse gas reduction, the development of an environmentally friendly process for producing phenol from biomass resources has become an urgent task.

[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 Unexamined Patent Application Publication No. 2014-37354 [Summary of the Invention] [Problems that the invention aims to solve]

[0006] When plant biomass is thermally decomposed, many decomposition products are generated from cellulose, hemicellulose, lignin, and oils contained in the plant biomass. While these decomposition products include useful organic compounds such as phenol, they also contain many other substances of little practical use. To promote the effective utilization of plant biomass, there is a need for a simple method suitable for industrial applications that enables the extraction of desired organic compounds from plant biomass.

[0007] However, in the method for producing phenols described in Patent Document 1, since the raw material is a lignin decomposition product dissolved in a solvent, the resulting phenol derivative is a mixture of methoxyphenol, alkylphenol, cresol, etc., and the yield of unsubstituted phenol is low.

[0008] Therefore, the object of the present invention is to provide a method for producing phenol using biomass raw materials that can yield phenol in high yield. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the inventors of this invention discovered that the problems of the conventional technology described above can be solved by using CNSL, an organic substance derived from biomass, as a raw material, and thus completed the present invention.

[0010] [1] A method for producing phenol, characterized by obtaining phenol by performing a dealkylation reaction in two or more steps in the presence of a solid acid catalyst from CNSL mainly composed of cardanol. [2] A method for producing phenol according to [1], wherein the reaction substrate from the second step onward in the two or more dealkylation reactions comprises one or more phenols represented by the following formula (1). [ka] (In formula (1), R1, R2, R3, R4, and R5 each independently represent a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, an optionally substituted aryl group having 1 to 15 carbon atoms, an optionally substituted alkenyl group having 1 to 15 carbon atoms, or a saturated or unsaturated cyclic hydrocarbon structure having 1 to 15 carbon atoms formed by the bonding of two of the elements selected from R1, R2, R3, R4, and R5.) [3] A method for producing phenol according to [1] or [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 of the MFI type. [6] A method for producing phenol according to any one of [1] to [5], comprising a hydrogenation step using hydrogen gas on CNSL mainly composed of cardanol, before the first dealkylation step among the two or more dealkylation steps described above. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a method for producing phenol using biomass raw materials that can yield phenol in high yield. [Modes for carrying out the invention]

[0012] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). It should be noted that this embodiment is illustrative for explaining the present invention, and the present invention is not limited to the following content, but can be implemented with various modifications within the scope of its gist.

[0013] [CNSL] Biomass raw materials refer to organisms, especially plant bodies such as wood, bamboo, coconut fruits, cashew nut shells, polysaccharides such as cellulose, starch, pullulan, small sugars such as dextrin, sucrose, maltose, monosaccharides such as fructose, glucose, and plant components such as lignin, hemicellulose. Furthermore, for example, wood-based waste in the wood industry and pulp industry, thinned wood, building demolition materials, rice straw, bean pods, bagasse and other agricultural waste, various lignocelluloses, and furthermore, including resource rice, old rice, food industry waste, etc. In this specification, unless otherwise specified, these substances are collectively referred to as biomass. For example, as a phenolic compound derived from biomass, cashew nutshell liquid (CNSL) can be mentioned. CNSL used as a biomass-derived raw material for phenol production in this embodiment will be described below.

[0014] Cashew is a naturally occurring tropical plant. Its fruit, the cashew nut, contains protein and carbohydrates, etc., and is used as food in snacks such as mixed nuts and cooking. Cashew nuts are natural fruits, and when regarded as resources, they are renewable biomass resources.

[0015] CNSL, which is mainly composed of cardanol and used in this embodiment, is an oily liquid contained in the shell of cashew nuts, which is a non-edible part obtained as a by-product when collecting natural cashew nuts used for food.

[0016] Natural CNSL is a mixture of anacardic acid, cardanol, cardol, and 2-methylcardol. Each component is an organic compound composed of a phenol part and a linear hydrocarbon part R as shown by the following formulas (2) to (5).

Chemical formula

[0017] Natural CNSL has anacardic acid represented by the above formula (2) as the main component. Such natural CNSL is decarboxylated for industrial use, and cardanol represented by the above formula (3) becomes the main component. The proportion of each component contained in industrial CNSL varies depending on the production area, etc., but generally, cardanol (3): 70 to 80% by mass, cardol (4): 15 to 25% by mass, 2-methyl cardol (5): 5% by mass or less. The proportion of cardanol can be increased by distilling industrial CNSL.

[0018] The CNSL used as a raw material for phenol production in this embodiment is CNSL having cardanol represented by the above formula (3) as the main component (that is, CNSL containing 50% by mass or more of cardanol). From the viewpoint of improving the phenol yield, the content of cardanol in CNSL is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 80 to 100% by mass.

[0019] If the already industrially processed CNSL, which has cardanol as its main component as shown in formula (3) above, has the desired composition, it can be used as a 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 efficiency (e.g., simple distillation) can be selected, thereby reducing production energy and the cost of preparing the raw materials.

[0020] Furthermore, the CNSL used as a raw material for phenol production in this embodiment may be a product in which the unsaturated bonds of the linear hydrocarbon portion R in the side chains of each component shown in formulas (2) to (5) above have been hydrogenated (hydrogenated) in advance.

[0021] [Method for producing phenol] The method for producing phenol in this embodiment is characterized by using CNSL, which mainly consists of cardanol, as a biomass-derived raw material, and obtaining phenol from the CNSL by a dealkylation reaction in two or more steps in the presence of a solid acid catalyst.

[0022] As a cardanol-based CNSL, those listed under [CNSL] above can be used.

[0023] The above dealkylation reactions, consisting of two or more steps, may be carried out under the same conditions or under different conditions. For example, the reaction conditions for the first step and the reaction conditions for the second and subsequent steps may be the same or different. Furthermore, the solid acid catalyst used in the second and subsequent dealkylation reactions may be the same as the solid acid catalyst used in the first step or a new solid acid catalyst may be used. In addition, the type of solid acid catalyst used in the second and subsequent dealkylation reactions may be the same as the solid acid catalyst used in the first step or a different type.

[0024] (Dealkylation process) In the dealkylation step, dealkylation is performed in the presence of a solid acid catalyst to remove the linear hydrocarbon portion R from each component represented by formulas (2) to (5) that constitute CNSL. At this time, phenol is obtained by dealkylating cardanol represented by formula (3). In the method for producing phenol of this embodiment, phenol can be obtained in high yield by performing the dealkylation reaction in a heterogeneous catalytic reaction using a solid acid catalyst. In this specification, "solid acid catalyst" means an acid catalyst that is insoluble in the reaction solvent of the dealkylation reaction in this embodiment.

[0025] In this embodiment, the dealkylation reaction is carried out in two or more steps. The number of dealkylation reactions performed in each step is one. The reaction mechanism for producing alkylphenols and phenols with different carbon chain lengths and hydrocarbon group bonding sites, as shown in formula (1) above, from CNSL, which is mainly composed of cardanol, involves the cracking and dealkylation of the side chains of CNSL to produce free hydrocarbons, phenols, and shorter-chain alkylphenols. These then combine to produce alkylphenols with different carbon chain lengths and hydrocarbon group bonding sites from CNSL. Subsequently, the phenol shown in formula (1) is transalkylated in the first or subsequent steps to obtain further phenols. From the viewpoint of achieving further improvements in phenol yield, this embodiment requires two or more dealkylation steps. Based on the idea of ​​efficiently obtaining phenol in high yield, the dealkylation steps consist of five or fewer steps, preferably four or fewer steps, more preferably three or fewer steps, and particularly preferably two steps.

[0026] When isolating / purifying phenol obtained in the first or subsequent dealkylation steps, the phenol can be recovered by methods such as solvent removal, extraction with an organic solvent after solvent removal, distillation, sublimation, crystallization, or chromatography. The phenol obtained in the first dealkylation step may be isolated and / or purified and recovered after the reaction is complete, or it may be used as a raw material for the second reaction without undergoing isolation and / or purification.

[0027] When used as a raw material for the second step of the reaction without isolation / purification, if the reaction is carried out in a batch manner, the reaction solution after the reaction is completed may be directly introduced into the reactor for the second step, or phenol may be extracted from the reaction solution using a different organic solvent, and the extract may be introduced into the reactor for the other step. If the reaction is carried out in a flow reaction, the reaction solution may be directly passed through the reactor for the other step under the flow reaction process, or the reaction solution may be contacted with a different organic solvent to extract phenol, and then the extract may be introduced into the reactor for the other step. The dealkylation step can also be carried out in combination of batch and flow reactions.

[0028] (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 include alkali metal or alkaline earth metal salts of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and boric acid; alkali metal or alkaline earth metal salts of sulfonic acids such as p-toluenesulfonic acid; acidic cation exchange resins such as Amberlist®, Amberlite®, and Diaion®; zeolites; Al2O3, TiO2, ZrO2, and SiO2. Examples include simple metal oxides and complex metal oxides such as 2-Al2O3, SiO2-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 heteropoly acids. Among the solid acid catalysts mentioned above, zeolites are particularly preferred from the viewpoint of improving phenol yield.

[0029] These solid acid catalysts may be used individually or in combination of two or more types. When using two or more solid acid catalysts, the combination is not particularly limited; they may be composed of metals that each possess catalytic activity (co-catalysts), or they may be composed of metals that enhance the catalytic activity of one or more metals (co-catalysts).

[0030] (Zeolite) In this specification, "zeolite" refers to a crystalline substance in which tetrahedral TO4 units (where T is the central atom, such as Si or Al) are linked three-dimensionally by sharing oxygen atoms, forming open, regular micropores. Specifically, examples of zeolites include silicates (aluminosilicate, gallosilicate, ferricilicate, titanosilicate, borosilicate, etc.), phosphates (aluminophosphate, gallophosphate, berirophosphate, etc.), germanites (aluminogenum salt, etc.), arsenates (aluminoarsenate, etc.), etc., as listed in the structural committee data collection of the International Zeolite Association (IZA).

[0031] (Structure of zeolite) The structure of the zeolite is not particularly limited, but examples include structures represented by AEL, EUO, FER, MEL, MFI, MTT, MWW, MOR, BEA, USY, TON, and WEI in the Framework Type Code (FTC) defined by IZA. Among these, zeolites having the structure represented by MFI are preferred from the viewpoint of improving the phenol yield from CNSL. Using zeolites with the above structure tends to improve the phenol yield from CNSL.

[0032] (Silica / alumina ratio of zeolite) From the viewpoint of improving zeolite productivity and phenol yield from CNSL, the silica / alumina (SiO2 / Al2O3) molar ratio of the zeolite is preferably in the range of 1 to 300. More preferably, the silica / alumina molar ratio of the zeolite is 10 to 250, and even more preferably 25 to 230. The silica / alumina molar ratio of zeolite can be measured by known methods. For example, it can be determined by completely dissolving the zeolite in an alkaline aqueous solution and analyzing the resulting solution using plasma emission spectroscopy or the like.

[0033] The method for preparing the zeolite is not particularly limited, and known methods can be used. Furthermore, the composition of the zeolite can be altered after hydrothermal synthesis by ion exchange, dealuminization, impregnation, or supporting. Commercially available zeolites can also be used.

[0034] The shape of the zeolite is not particularly limited and may be in powder or granular form. The zeolite can be molded into a shape suitable for the phenol production process from CNSL. The method for molding the zeolite is not particularly limited and known methods can be used.

[0035] The amount of solid acid catalyst used is not limited to fixed-bed reactors, suspension-bed reactors, or continuous flow reactors when a continuous reaction is carried out, 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 even 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 even more preferably 10 parts by mass or less.

[0036] As the solvent used in the dealkylation reaction, an organic solvent can be used, as is commonly done. The organic solvent may be used alone or in combination of two or more types.

[0037] The organic solvent is not particularly limited as long as it does not inhibit the reaction that produces phenol by dealkylating the linear hydrocarbon portion of the side chain from cardanol in CNSL, but examples include 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, Ketones with 4 to 20 carbon atoms, such as 5-decanone, 2-undecanone, 4-undecanone, 3-dodecanone, 2-tridecanone, 2-tetradecanone, 4-tetradecanone, 2-pentadecanone, 3-pentadecanone, 7-pentadecanone, 2-hexadecanone, 3-hexadecanone, 4-hexadecanone, 6-hexadecanone, 2-heptadecanone, 4-heptadecanone, 9-heptadecanone, 3-octadecanone, acetophenone, etc.; ethyl acetate, acetate Esters such as propyl acetate and butyl acetate; aliphatic alcohols such as methanol, ethanol, propyl alcohol, and isopropyl alcohol; aliphatic polyhydric alcohols such as propylene glycol, octanediol, 1,3-butanediol, ethylene glycol, polyethylene glycol, glycerin, and D-sorbitol; aromatic aliphatic alcohols such as benzyl alcohol; phenols such as phenol, o-cresol, m-cresol, p-cresol, tert-butylphenol, 2,4-dimethylphenol, and 2,6-dimethylphenol; saturated aliphatic hydrocarbon compounds with 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; lactones such as γ-butyrolactone and γ-valerolactone;Examples include halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, tetrachloroethane, and hexachloroethane, as well as dimethylacetamide, N,N-dimethylformamide, N-methylmorpholine, N-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, hexamethyltriamide, tetramethylurea, dimethyl sulfoxide, sulfolane, isosorbide, propylene carbonate, and mixtures thereof. Among these organic solvents, it is preferable that at least one is selected from the group consisting of ketones, esters, alcohols, phenols, lactones, aromatic hydrocarbons, halogenated hydrocarbons, and saturated aliphatic hydrocarbon compounds.

[0038] From the viewpoint of appropriately controlling the reaction, including reaction temperature, reaction pressure, and the amount of by-products produced, the boiling point of the organic solvent used is preferably 70°C or higher and 150°C or lower. The lower limit of the boiling point is more preferably 75°C or higher, and even more preferably 80°C or higher. The upper limit is 150°C or lower, even more preferably 145°C or lower, and particularly preferably 140°C or lower.

[0039] (Reaction type, reactor) Both batch and flow reactions can be used for the dealkylation of the linear hydrocarbon portion of the side chain from cardanol in CNSL. In the flow reaction, both fixed-bed flow and stirred-tank flow reactions are possible. The description herein does not preclude changes to the reaction conditions that can be easily adjusted by those skilled in the art.

[0040] (Reaction temperature) There are no particular restrictions on the reaction temperature, but it may be 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 increase the yield of phenol. Conversely, a reaction temperature of 350°C or lower tends to further suppress the formation of by-products and reduce catalyst degradation.

[0041] (Reaction pressure) Regarding the reaction pressure, while high pressure is advantageous for the reaction equilibrium of the dealkylation reaction in this embodiment, high pressure increases equipment costs when implementing the reaction industrially. Therefore, it is preferably atmospheric pressure or higher and 10.0 MPa or lower, and more preferably atmospheric pressure or higher and 8.0 MPa or lower. Here, atmospheric pressure is the same as atmospheric pressure.

[0042] (Reaction time) The reaction time is not particularly limited. In the case of a batch system, 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. However, this does not apply to the reaction time in the case of a flow system.

[0043] (Adding water) The amount of water added 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, per 100 parts by mass of CNSL, while 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 keeping the amount of water added within the above range, sufficient catalytic activity can be obtained by suppressing coking.

[0044] (Dealkylation reaction from the second step onward) In the method for producing phenol according to this embodiment, it is preferable that the reaction substrate from the second step onward in a dealkylation reaction consisting of two or more steps contains one or more phenols represented by the following formula (1). [ka] In formula (1), R1, R2, R3, R4, and R5 each independently represent a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, an optionally substituted aryl group having 1 to 15 carbon atoms, an optionally substituted alkenyl group having 1 to 15 carbon atoms, or a saturated or unsaturated cyclic hydrocarbon structure having 1 to 15 carbon atoms formed by the bonding of two of the elements selected from R1, R2, R3, R4, and R5.

[0045] In formula (1) above, R1, R2, R3, R4, and R5 are each independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, an optionally substituted aryl group having 1 to 15 carbon atoms, an optionally substituted alkenyl group having 1 to 15 carbon atoms, or a saturated or unsaturated cyclic hydrocarbon structure having 1 to 15 carbon atoms formed by bonding two of these groups together, selected from R1, R2, R3, R4, and R5. From the viewpoint of being an intermediate or target product in the dealkylation reaction of CNSL, it is preferable that R1, R2, R3, R4, and R5 are a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, an optionally substituted aryl group having 1 to 15 carbon atoms, or a saturated or unsaturated cyclic hydrocarbon structure having 1 to 15 carbon atoms formed by bonding two of these groups together.

[0046] Examples of phenols represented by formula (1) above include phenol, cresol, ethylphenol, n-propylphenol, i-propylphenol, n-butylphenol, i-butylphenol, sec-butylphenol, tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, decylphenol, undecylphenol, dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, cardanol, dimethylphenol, ethylmethylphenol, diethylphenol, methylvinylphenol, ethylvinylphenol, methyl n-propylphenol, ethyl n-propylphenol, di-n-propylphenol, n-butylmethylphenol, n-butylethylphenol, di-n-butylphenol, allylmethylphenol, allylethylphenol, allyl n-butylphenol, allyl n-propylphenol, indanol, naphthol, and their respective isomers such as chain isomers, positional isomers, and geometric isomers, but are not limited to these examples as long as they fit the above formula (1). The phenol in formula (1) above may be used alone or in combination of two or more types.

[0047] (Hydrogenation (hydrogen addition) process) In the method for producing phenol according to this embodiment, the raw material CNSL may undergo a hydrogenation step using hydrogen gas to remove the unsaturated bonds (double bonds) in the linear hydrocarbon portion of the side chains of each component before the first dealkylation step in a two-step or more dealkylation reaction. By removing the unsaturated bonds from the four components of cardanol analogs, which have different numbers of unsaturated bonds in their side chains, by hydrogenation, the yield of phenol can be significantly improved.

[0048] There are no particular limitations on the method for hydrogenating (hydrogenating) CNSL; conventional methods can be used.

[0049] 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 include catalysts containing a metal element having catalytic hydrogenation ability (hereinafter sometimes referred to as "specific metal component") as an active ingredient.

[0050] Examples of specific metallic components include nickel, cobalt, iron, ruthenium, rhodium, osmium, palladium, platinum, gold, iridium, copper, zinc, silver, molybdenum, tungsten, chromium, manganese, rhenium, and mixtures thereof.

[0051] This specific metallic component may be in a metallic state or a cationic state, as long as it exhibits hydrogenation ability. Among these, the metallic state is sometimes preferred due to its high hydrogenation ability and high stability under a reducing atmosphere.

[0052] Specific metal components can be used individually or in combination of two or more, contained within a solid catalyst. Furthermore, when using two or more specific metal components, there are no particular restrictions on their combination, mixing ratio, or form; they can be used as mixtures of individual metals, or in the form of alloys or intermetallic compounds.

[0053] There are no particular restrictions on the raw materials for these specific metal components; those used as raw materials when preparing catalysts by conventionally known methods can be employed. Examples of such raw materials include hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, ammine complexes, and carbonyl complexes of each metal element. These may be used individually or in combination of two or more.

[0054] The hydrogenation catalyst used in this embodiment may also use a specific metal component 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 a specific metal component, and sponge catalysts prepared by forming an alloy of a specific metal component such as nickel, copper, iron, or cobalt with a metal such as aluminum, zinc, or silicon, and then leaching all or part of the metal such as aluminum, zinc, or silicon with an acid or alkali.

[0055] Furthermore, in order to further improve the activity, selectivity, and physical properties of the catalyst, compounds of one or more elements selected from the group consisting of alkali metal elements such as lithium, sodium, potassium, rubidium, and cesium; alkaline earth metal elements such as magnesium, calcium, strontium, and barium; halogen elements such as fluorine, chlorine, bromine, and iodine; and auxiliary additive elements such as aluminum, gallium, germanium, silicon, lead, bismuth, tin, tellurium, and antimony (hereinafter sometimes referred to as "specific additive components") may be added to the catalyst together with the specified metal components mentioned above.

[0056] There are no particular restrictions on the raw materials for these specific additive components; those used as raw materials when preparing catalysts by conventionally known methods can be employed. Examples of such raw materials include hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, and ammine complexes of each metal element. These may be used individually or in combination of two or more.

[0057] Furthermore, there are no particular restrictions on the method of adding specific additives, nor on the ratio of specific additives to specific metal components.

[0058] In the hydrogenation catalyst used in this embodiment, a combination of a specific metal component and a nonmetallic substance may also be used. Examples of nonmetallic substances include, for example, elemental elements, carbides, nitrides, oxides, hydroxides, sulfates, carbonates, and phosphates (hereinafter sometimes referred to as "specific nonmetallic components"). Specific examples 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, porophosphate, magnesium phosphate, calcium phosphate, strontium phosphate, apatite hydroxide (calcium hydroxyphosphate), apatite chloride, apatite fluoride, calcium sulfate, barium sulfate, and barium carbonate. Specific nonmetallic components may be used individually or in combination of two or more. There are no particular restrictions on the combinations, mixing ratios, or forms when using two or more types together; they can be used in the form of mixtures of individual compounds, complex compounds, or double salts. From an industrial standpoint, specific nonmetallic components that can be obtained simply and inexpensively are preferred.

[0059] As a hydrogenation catalyst, a specific metal component may be used alone, or a specific metal component may be used in combination with a specific nonmetal component, and in some cases, a specific additive component may also be included in addition to these.

[0060] There are no particular restrictions on the method for producing the hydrogenation catalyst, and conventionally known methods can be used. Examples include impregnating a specific metal component raw material compound onto a specific non-metal component (supporting method), dissolving a specific metal component raw material compound and a specific non-metal component raw material compound together in a suitable solvent and then simultaneously precipitating them using an alkaline compound or the like (coprecipitation method), and mixing and homogenizing a specific metal component raw material compound and a specific non-metal component in an appropriate ratio (kneading method).

[0061] Furthermore, there are no particular restrictions on the metal content or shape of the hydrogenation catalyst. It may be in powder form or molded form, and there are no particular restrictions on the shape or molding method if it is molded. For example, spherical products, compressed tablets, extruded products, and crushed versions thereof can be appropriately selected and used.

[0062] The metal content in a hydrogenation catalyst is not particularly limited, but in terms of mass percentage converted to metal, the lower limit may be 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and the upper limit may be 50% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the catalyst. By keeping the metal content within the above range, sufficient catalytic activity can be obtained. In the following descriptions of catalysts, the values ​​indicated as mass% represent the metal content relative to the total mass of the catalyst.

[0063] The amount of hydrogenation catalyst used 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, per 100 parts by mass of CNSL, 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.

[0064] The hydrogen gas pressure is not particularly limited and can, for example, be carried out under pressurized hydrogen gas conditions. The hydrogen gas pressure during the hydrogenation reaction may have a lower limit of 0.1 MPa or more, preferably 0.3 MPa or more, more preferably 0.4 MPa or more, and an upper limit of 15 MPa or less, preferably 20 MPa or less, more preferably 5 MPa or less, and even more preferably 3 MPa or less.

[0065] Generally, increasing the reaction pressure promotes the supply of hydrogen to the hydrogenation catalyst, thereby improving the reaction rate. On the other hand, carrying out the reaction at high pressure requires specially designed reactors and other equipment with enhanced pressure resistance, and the increased hydrogenation capacity may lead to the progression of hydrocracking.

[0066] Examples of reaction solvents include water, hydrocarbons, esters, ethers, and alcohols, which may be used individually or in combination of two or more.

[0067] 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, 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.

[0068] The reaction time for 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, usually 24 hours or less, preferably 12 hours or less, and more preferably 5 hours or less. However, this does not apply when the hydrogenation reaction is carried out continuously.

[0069] The reactor used in the hydrogenation reaction is not particularly limited, but for example, a high-pressure reactor capable of high-pressure reactions can be used. A continuous reactor can also be used, in which case the catalyst is packed into the reactor and the reaction is carried out by flowing the raw material liquid and hydrogen gas through it. In the case of a continuous reactor, the catalyst separation process is unnecessary, and a continuous reactor is preferable for mass production. [Examples]

[0070] 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 unless it exceeds the essence of the invention.

[0071] [Phenol Yield (Gas Chromatography Analytical Conditions)] The yield of phenol in the examples and comparative examples was calculated as an area percentage by analyzing the obtained products by gas chromatography (hereinafter also referred to as "GC"). The GC analysis conditions were as follows: Equipment: GC-2010 (manufactured by Shimadzu Corporation) Column: DB-5 (manufactured by Agilent Technologies) Length 30m x Inner diameter 0.25mm x Film thickness 1.0μm Column temperature: Adjust to 50°C, hold at 50°C for 5 minutes, increase temperature to 325°C at a rate of 10°C / min, hold at 325°C for 2 minutes and 30 seconds. Injection temperature: 350℃ Carrier gas: Helium gas Detector: Flame ionization detector (FID)

[0072] [Example 1 and Comparative Example 1] 1 g of CNSL (Cardwright NX-2026) was dissolved in 8.64 g of toluene, and 0.36 g of water was added. To this solution, 0.5 g of MFI-80 (Zeolyst CBV8014) was added, and the dealkylation reaction was carried out in a batch manner with stirring at a reaction temperature of 300 °C, a reaction time of 2 hours, a reaction pressure of 4 MPa, and under a nitrogen atmosphere. The phenol yield at the first step of the obtained product was determined. This yield was used as the yield for Comparative Example 1. Subsequently, using the obtained product, 4.0 g of toluene and 0.5 g of MFI-80 (CBV8014, manufactured by Zeolyst) were added in the same manner, and the dealkylation reaction was carried out with stirring at a reaction temperature of 300°C, a reaction time of 2 hours, a reaction pressure of 4 MPa, and under a nitrogen atmosphere, and the phenol yield was determined. The results of each measurement are shown in Table 1.

[0073] [Example 2] 2.5 g of CNSL (Cardwright NX-2026) was dissolved in 2.5 g of toluene. In the presence of 0.125 g (5 parts by mass per 100 parts by mass of CNSL) of Ru / Al2O3 as a hydrogenation catalyst (Ru content in the hydrogenation catalyst was 5% by mass), 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 (Shimadzu GC-2010) was 99.3%. Subsequently, a two-step dealkylation reaction was carried out using hydrogenated CNSL in the same manner as in Example 1. The results of each measurement are shown in Table 1.

[0074] [Table 1] [Industrial applicability]

[0075] According to the manufacturing method of the present invention, phenol can be obtained in high yield from CNSL, which is a biomass raw material and mainly consists of cardanol. Therefore, it is expected to be a phenol production process that can replace existing petrochemical processes.

Claims

1. A method for producing phenol, characterized by obtaining phenol by performing a dealkylation reaction in two or more steps in the presence of a solid acid catalyst from CNSL mainly composed of cardanol.

2. The method for producing phenol according to claim 1, wherein the reaction substrate used in the second and subsequent steps of the two or more dealkylation reactions includes one or more phenols represented by the following formula (1). 【Chemistry 1】 (In formula (1), R １ , R ２ , R ３ , R ４ , R ５ each independently represents a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms which may be substituted, an aryl group having 1 to 15 carbon atoms which may be substituted, an alkenyl group having 1 to 15 carbon atoms which may be substituted, or a saturated or unsaturated cyclic hydrocarbon structure having 1 to 15 carbon atoms in which two selected from R １ , R ２ , R ３ , R ４ , R ５ are bonded to each other.)

3. The method for producing phenol according to claim 1 or 2, wherein the solid acid catalyst is a zeolite.

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

6. A method for producing phenol according to claim 1 or 2, wherein, among the two or more dealkylation reactions described above, a hydrogenation step is included in which the cardanol-based CNSL is hydrogenated using hydrogen gas before the first dealkylation reaction.

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