Method for producing cycloolefin

Abstract

A method for producing a cycloolefin by subjecting a monocyclic aromatic hydrocarbon to a partial hydrogenation reaction using hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst, said method being characterized in that: the aqueous zinc sulfate solution contains dimethylamine; the partial hydrogenation reaction is carried out with the nitrogen concentration in the aqueous zinc sulfate solution being 0.5-3000 mg / L or the acetic acid concentration in the aqueous zinc sulfate solution being 1 * 10 <-3 >-100 mg / L.

Description

Technical Field

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

[0002] In the past, cycloolefins, especially cyclohexene, have been widely used as intermediate materials for organic chemical industrial products. Various methods are known for producing the cycloolefins, and generally a method of using monocyclic aromatic hydrocarbons as raw materials and performing partial hydrogenation using a ruthenium catalyst is used.

[0003] As a method for improving the yield of cycloolefins, a large number of research techniques have been proposed regarding catalyst components, types of carriers, or metal salts as additives to the reaction system. Among them, the method using a reaction system in which water and zinc coexist has shown a high yield of cycloolefins.

[0004] For example, (1) the following method has been proposed: when partially reducing monocyclic aromatic hydrocarbons using hydrogen in the presence of water, hydrogenation catalyst particles containing metal ruthenium as a main component and having an average crystal diameter of less than 20 nm are used, and the reaction is carried out under neutral or acidic conditions in the coexistence of at least one solid basic zinc salt (excluding basic zinc sulfate) (for example, refer to Patent Document 1).

[0005] In addition, (2) the following method is proposed: when monocyclic aromatic hydrocarbons are partially reduced using hydrogen in the coexistence of water and at least one zinc compound under neutral or acidic conditions, a catalyst is used as a catalyst in which particles containing metallic ruthenium as a main component and having an average crystallite diameter of 3 to 20 nm are supported on a carrier (for example, refer to Patent Document 2).

[0006] Furthermore, (3) as a catalyst for producing cycloolefins, a catalyst having zirconium oxide as a carrier and composed of particles having an average primary particle size in the range of 3 to 50 nm and an average secondary particle size in the range of 0.1 to 30 μm has been proposed (for example, see Patent Document 3).

[0007] When a method for producing cycloolefins using a ruthenium catalyst and monocyclic aromatic hydrocarbons as raw materials and partial reduction with hydrogen is to be implemented industrially, it is necessary to reduce the frequency of catalyst replacement as much as possible, which would hinder efficient production. Therefore, it is preferred to be able to use a long-term catalyst.

[0008] However, it is known that the activity of the catalyst decreases when the catalyst is used for a long time. As the reasons for the decrease in the activity of such catalysts, it is reported that the cause is the physical change (e.g., sintering) of the active point of the catalyst itself caused by the reaction environment (temperature, reaction heat), the accumulation of poisoning substances (e.g., sulfur compounds, heterogeneous metals, etc.), and the interaction between hydrogen and ruthenium.

[0009] For example, regarding poisoning of the catalyst, there are known examples of (1) poisoning caused by sulfur compounds (for example, see Patent Document 4) and (2) poisoning caused by the material of the reactor (for example, see Patent Document 5). Furthermore, there are disclosed methods of (3) removing nickel eluted from the reactor, which is considered a poisoning substance, from the reaction system (for example, see Patent Document 6), (4) suppressing the adverse effects of the chloride ion concentration in the reaction solution (for example, see Patent Document 7), and (5) using a catalyst in which the chloride content in the catalyst is controlled to be 0.04 parts by mass or less relative to 1 part by mass of ruthenium in the reaction system (for example, see Patent Document 8).

[0010] Regarding the regeneration method of the ruthenium catalyst whose activity is reduced due to the interaction between hydrogen and the ruthenium catalyst, the following methods are proposed: a method of contacting the catalyst with oxygen in a liquid phase (for example, see Patent Document 9); a method of maintaining the catalyst at a hydrogen partial pressure lower than the hydrogen partial pressure in the hydrogenation reaction and at a temperature not lower than 50°C lower than the temperature in the hydrogenation reaction (for example, see Patent Document 10); a method having a step of contacting the catalyst with oxygen in a liquid phase and a step of maintaining the catalyst at a hydrogen partial pressure lower than the hydrogen partial pressure in the hydrogenation reaction and at a temperature not lower than 50°C lower than the temperature in the hydrogenation reaction (for example, see Patent Document 11), etc. Furthermore, a method and an apparatus for continuously or intermittently taking out a part of the catalyst in a continuous reaction for regeneration treatment and returning it again to a reactor for partial hydrogenation reaction are proposed (for example, see Patent Document 12).

[0011] In addition, it is known that when a long-term catalyst is used, the selectivity of cycloolefins changes over time. In order to avoid this, a method of reacting while changing the concentration of metal sulfate in the aqueous phase (for example, referring to Patent Document 13) and a method of adding sulfuric acid to the reaction system (for example, referring to Patent Document 14) have been proposed.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent No. 2115581

[0015] Patent Document 2: Japanese Patent No. 2138012

[0016] Patent Document 3: Japanese Patent No. 4777891

[0017] Patent Document 4: Japanese Patent No. 1849859

[0018] Patent Document 5: Japanese Patent No. 2892233

[0019] Patent Document 6: Japanese Patent No. 5254338

[0020] Patent Document 7: Japanese Patent No. 5147053

[0021] Patent Document 8: Japanese Patent No. 3125913

[0022] Patent Document 9: Japanese Patent No. 2634828

[0023] Patent Document 10: Japanese Patent No. 2886563

[0024] Patent Document 11: Japanese Patent No. 3841226

[0025] Patent Document 12: Japanese Patent No. 4397468

[0026] Patent Document 13: Japanese Patent No. 4033980

[0027] Patent Document 14: Japanese Patent No. 4025407 Summary of the invention

[0028] Problem that the invention aims to solve

[0029] However, none of the above-mentioned prior art documents discloses that the nitrogen-containing component contained in the aqueous zinc sulfate solution in the reactor affects the reactivity of the catalyst when a monocyclic aromatic hydrocarbon is partially hydrogenated with hydrogen.

[0030] The nitrogen-containing components are contained in the monocyclic aromatic hydrocarbons and hydrogen, which are the raw materials for producing cycloolefins, and enter the reactor. In addition, the monocyclic aromatic hydrocarbons are recycled through the partial hydrogenation reaction step and the product separation and purification step.

[0031] The nitrogen-containing components derived from the raw materials are not only contained in the basic raw materials for producing monocyclic aromatic hydrocarbons and hydrogen, but also may be mixed in by chemical reagents used in the process of separating and purifying the raw materials, lubricants from equipment, etc., etc. In addition, in the production of cycloolefins, the nitrogen-containing components that enter the reactor through the recycled monocyclic aromatic hydrocarbons are caused by the extractant used in the post-hydrogenation process and the components after the decomposition of the extractant being mixed in the recycled monocyclic aromatic hydrocarbons.

[0032] In the partial hydrogenation reaction of monocyclic aromatic hydrocarbons, as a generally known method, a step of adjusting the reaction conversion rate to increase the production ratio of the target product with high selectivity is performed, and if the reaction conversion rate is low, an operation of recycling the unreacted monocyclic aromatic hydrocarbons and returning them again to the reactor for carrying out the partial hydrogenation reaction is performed.

[0033] At this time, in the process of separating and purifying the partial hydrogenation reaction product and the unreacted monocyclic aromatic hydrocarbons, the extraction solvent and its decomposition products are mixed with the recycled monocyclic aromatic hydrocarbons and enter the partial hydrogenation reaction reactor again.

[0034] As described above, when nitrogen-containing components enter the reactor for partial hydrogenation, they come into contact with the catalyst in the hydrogenation reaction field and further react with the aqueous zinc sulfate solution, which causes a major problem of reducing the partial hydrogenation activity of monocyclic aromatic hydrocarbons and the selectivity of cycloolefins.

[0035] On the other hand, regarding the influence of the amount of nitrogen components in the hydrogenation reaction field on the hydrogenation reaction, there has been no report in the past, and no solution has been proposed.

[0036] Furthermore, none of the above-mentioned prior art documents discloses that, when a monocyclic aromatic hydrocarbon is partially hydrogenated with hydrogen, the concentration of acetic acid in the aqueous zinc sulfate solution in the reactor affects the reactivity of the partial hydrogenation reaction.

[0037] In the partial hydrogenation reaction of monocyclic aromatic hydrocarbons, in order to recover the cycloolefins as the target product with high selectivity and improve the productivity, it is necessary to appropriately adjust the reaction conversion rate of the monocyclic aromatic hydrocarbons. In this case, the unreacted monocyclic aromatic hydrocarbons are usually separated and recovered from the reaction products and recycled to the partial hydrogenation reactor again.

[0038] On the other hand, since the reaction products of the partial hydrogenation reaction, including by-products, have a boiling point close to that of the monocyclic aromatic hydrocarbons serving as the raw materials, a predetermined extractant is used for separation and recovery. Depending on the state of separation and recovery, the extractant and components after decomposition of the extractant may be mixed into the reactor together with the monocyclic aromatic hydrocarbons to be recycled.

[0039] Acetic acid is a decomposition product of dimethylacetamide, which is highly effective in separating and purifying raw monocyclic aromatic hydrocarbons from product cycloolefins and by-product cycloalkanes, and is produced in trace amounts in the separation and recovery column of the partial hydrogenation reaction product. This acetic acid is mixed with the recycled monocyclic aromatic hydrocarbons and enters the subsequent reactor for the partial hydrogenation reaction.

[0040] As described above, when acetic acid enters the reactor for the partial hydrogenation reaction, it acts on the catalyst in the hydrogenation reaction field, thereby causing a problem of reducing the selectivity of cycloolefins.

[0041] Therefore, an object of the present invention is to provide a method for stably producing cycloolefins by suppressing a decrease in the selectivity of cycloolefins in the partial hydrogenation reaction of monocyclic aromatic hydrocarbons.

[0042] Solutions for solving problems

[0043] The present inventors have found that, when subjecting monocyclic aromatic hydrocarbons to partial hydrogenation reaction, by controlling the nitrogen concentration in an aqueous zinc sulfate solution, a decrease in the activity of the catalyst and a decrease in the selectivity in the partial hydrogenation reaction can be significantly suppressed, and that the above-mentioned problems of the prior art can be solved, thereby completing the present invention.

[0044] The present inventors have also found that, when subjecting monocyclic aromatic hydrocarbons to a partial hydrogenation reaction, by controlling the acetic acid concentration in an aqueous zinc sulfate solution to a specific numerical range, a decrease in the selectivity of the catalyst in the partial hydrogenation reaction can be significantly suppressed, and that the above-mentioned problems of the prior art can be solved, thereby completing the present invention.

[0045] That is, the present invention is as follows.

[0046] [1]

[0047] A method for producing cycloolefins, comprising: performing a partial hydrogenation reaction of monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst to produce cycloolefins, wherein the aqueous zinc sulfate solution contains dimethylamine and the nitrogen concentration in the aqueous zinc sulfate solution is 0.5 to 3000 mg / L.

[0048] [2]

[0049] The method for producing cycloolefins according to the above [1], wherein the partial hydrogenation reaction of the monocyclic aromatic hydrocarbons is carried out by replacing a part of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution so that the nitrogen concentration in the zinc sulfate aqueous solution in the presence of the ruthenium catalyst is 0.5 to 3000 mg / L.

[0050] 〔3〕

[0051] The method for producing a cycloolefin according to [1] or [2] above, wherein the nitrogen concentration contained in the monocyclic aromatic compound is 0.003 to 35 mg / L.

[0052] [4]

[0053] The method for producing cycloolefin according to any one of [1] to [3], wherein the ratio of the mass of nitrogen to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution is 5×10 -6 ~8×10 -2 times.

[0054] 〔5〕

[0055] The method for producing cycloolefins according to any one of [1] to [4], wherein the nitrogen concentration in the zinc sulfate aqueous solution is 0.5 to 1500 mg / L, the nitrogen concentration in the monocyclic aromatic hydrocarbon is 0.01 to 16 mg / L, and the ratio of the mass of nitrogen in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is 1×10 -5 ~5×10 -2 times, for partial hydrogenation reaction.

[0056] [6]

[0057] The method for producing cycloolefins according to any one of [1] to [5], wherein the concentration of dimethylamine in the zinc sulfate aqueous solution is 1.7 to 9900 mg / L, the concentration of dimethylamine in the monocyclic aromatic hydrocarbon is 0.01 to 115 mg / L, and the ratio of the mass of dimethylamine in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is 2×10 -5 ~0.26 times.

[0058] 〔7〕

[0059] The method for producing a cycloolefin according to any one of [1] to [6] above, comprising:

[0060] A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution;

[0061] After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound;

[0062] A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and

[0063] The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the above-mentioned reaction step.

[0064] In the reaction step, the content of dimethylamine in the aqueous zinc sulfate solution is controlled to be 40 to 1700 mg / L, and the mass ratio of dimethylamine to the mass of the ruthenium catalyst is controlled to be 8×10 -4 ~6×10 -2 times.

[0065] 〔8〕

[0066] A method for producing cycloolefins, comprising: partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst to produce cycloolefins, wherein the concentration of acetic acid in the aqueous zinc sulfate solution is set to 1×10 -3 ~100mg / L, for partial hydrogenation reaction.

[0067] 〔9〕

[0068] The method for producing cycloolefin according to [8], wherein the concentration of acetic acid in the aqueous zinc sulfate solution containing the ruthenium catalyst is set to 1×10 -3 ~100mg / L, partial hydrogenation of monocyclic aromatic hydrocarbons.

[0069] 〔10〕

[0070] The method for producing cycloolefins according to [8] or [9], wherein the concentration of acetic acid contained in the monocyclic aromatic hydrocarbon is 1×10 -4 ~5mg / L.

[0071]

[11]

[0072] The method for producing cycloolefin according to any one of [8] to

[10] , wherein the ratio of the mass of acetic acid to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution is 3×10 -9 ~2.5×10 -3 times the range.

[0073]

[12]

[0074] The method for producing a cycloolefin according to any one of [8] to

[11] above, comprising:

[0075] A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution;

[0076] After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound;

[0077] A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and

[0078] The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the above-mentioned reaction step.

[0079] In the reaction step, the ratio of the mass of acetic acid in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is controlled to be 1×10 -6 ~5×10 -4 times.

[0080] 〔13〕

[0081] A method for producing cycloolefins according to any one of [1] to

[12] above, wherein the ruthenium catalyst is a ruthenium catalyst containing zirconium oxide, and the method comprises a step of regenerating a part or all of the ruthenium catalyst containing zirconium oxide and reusing the regenerated ruthenium catalyst containing zirconium oxide.

[0082]

[14]

[0083] The method for producing cycloolefin according to any one of [1] to

[13] above, wherein the ruthenium catalyst is a ruthenium catalyst containing zirconium oxide, and the zinc concentration in the ruthenium catalyst containing zirconium oxide is 0.5 to 3.5% by mass.

[0084] 〔15〕

[0085] The method for producing a cycloolefin according to any one of [1] to

[14] , wherein the monocyclic aromatic hydrocarbon includes any one selected from the group consisting of benzene, toluene, and benzene substituted with an alkyl group having 1 to 4 carbon atoms.

[0086]

[16]

[0087] The method for producing cycloolefin according to any one of [1] to [7], wherein the concentration of acetic acid in the aqueous zinc sulfate solution is 1×10 -3 mg / L~100mg / L.

[0088] Effects of the Invention

[0089] According to the present invention, it is possible to effectively suppress a decrease in the selectivity of cycloolefins, thereby stably and efficiently producing cycloolefins over a long period of time. DETAILED DESCRIPTION

[0090] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “this embodiment”) will be described in detail.

[0091] It should be noted that the following embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the gist of the invention.

[0092] [Method for producing cycloolefin]

[0093] The method for producing cycloolefins according to the present embodiment (hereinafter sometimes referred to simply as the present embodiment) relates to a method for producing cycloolefins by partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst.

[0094] In the first embodiment, the aqueous zinc sulfate solution contains dimethylamine, and the nitrogen concentration in the aqueous zinc sulfate solution is set to a predetermined numerical range.

[0095] In the second embodiment, the concentration of acetic acid in the aqueous zinc sulfate solution is set to a predetermined numerical range.

[0096] The methods for producing cycloolefins according to the first and second embodiments are described below.

[0097] [Method for producing cycloolefin according to first embodiment]

[0098] In the first embodiment, the aqueous zinc sulfate solution contains dimethylamine, and the nitrogen concentration in the aqueous zinc sulfate solution is 0.5 to 3000 mg / L.

[0099] According to the first embodiment, the catalyst activity of the partial hydrogenation reaction and the high selectivity of cycloolefins can be maintained, and the catalyst activity and the high selectivity of cycloolefins can be maintained even after the catalyst is regenerated. By stabilizing the catalyst activity and selectivity, the number of complicated operations such as replacing the catalyst and adding unused catalysts can be reduced when producing cycloolefins for a long time, the selectivity of cycloolefins can be effectively suppressed, and cycloolefins can be produced efficiently and stably for a long time.

[0100] (monocyclic aromatic hydrocarbons)

[0101] In the method for producing cycloolefin according to the first embodiment, monocyclic aromatic hydrocarbons are used as a raw material.

[0102] Examples of the monocyclic aromatic hydrocarbons include, but are not limited to, benzene, toluene, and xylene, which are benzenes substituted with an alkyl group having 1 to 4 carbon atoms.

[0103] (Hydrogen pressure)

[0104] In the first embodiment, the hydrogen pressure during the partial hydrogenation reaction using hydrogen is usually 1 to 20 MPa, preferably 2 to 7 MPa.

[0105] By setting the hydrogen pressure to be 1 MPa or more, the selectivity of cycloolefins can be fully ensured. In addition, by setting the hydrogen pressure to be 20 MPa or less, the pressure of hydrogen and monocyclic aromatic hydrocarbons supplied to the reactor can be suppressed to a practically preferred level, and efficient operations such as suppressing the load on the equipment associated with the pressure increase and supplying hydrogen and monocyclic aromatic hydrocarbons in accordance with the hydrogen consumption can be performed.

[0106] (Reaction temperature)

[0107] The temperature during the partial hydrogenation reaction is usually 50 to 250°C, preferably 100 to 200°C.

[0108] By setting the reaction temperature to 50° C. or higher, a more sufficient reaction rate can be ensured. By setting the reaction temperature to 250° C. or lower, the growth (sintering) of the average crystallite diameter of ruthenium in the ruthenium catalyst can be suppressed, thereby reducing the decrease in catalyst activity.

[0109] (Ruthenium Catalyst)

[0110] In the first embodiment, the partial hydrogenation reaction of monocyclic aromatic hydrocarbons is carried out in the presence of a ruthenium catalyst.

[0111] The ruthenium catalyst is preferably a catalyst containing metallic ruthenium obtained by reducing various ruthenium compounds in advance.

[0112] The aforementioned ruthenium compound is not limited to the following, and examples thereof include halides such as chlorides, bromides, and iodides, or nitrates, sulfates, hydroxides, or various complexes containing ruthenium such as ruthenium carbonyl complexes, ruthenium acetylacetonate complexes, bis(cyclopentadienyl)ruthenium complexes, ruthenium amine complexes, ruthenium hydride complexes, and compounds derived from the complexes.

[0113] These ruthenium compounds may be used alone or in combination of two or more.

[0114] Examples of the reduction method of these ruthenium compounds include catalytic reduction methods using hydrogen, carbon monoxide, and the like, and chemical reduction methods using formalin, sodium borohydride, potassium borohydride, hydrazine, and the like.

[0115] Among these reduction methods, preferred methods are hydrogen-based catalytic reduction and sodium borohydride-based chemical reduction.

[0116] In the case of catalytic reduction using hydrogen, reduction activation is usually carried out at 50 to 450°C, preferably 100 to 400°C, more preferably 100 to 250°C.

[0117] By making the reduction temperature above 50°C, it is possible to reduce at a practically sufficient speed. In addition, by being below 450°C, the aggregation of ruthenium can be suppressed, and the adverse effects on activity and selectivity can be prevented. It should be noted that the reduction can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase. In addition, in the case of chemical reduction based on sodium borohydride, the reduction temperature is preferably a temperature below 100°C, and is generally preferably 10°C to 80°C.

[0118] In addition, the state of the ruthenium catalyst added during the partial hydrogenation reaction may also be a state of a ruthenium compound that does not contain metallic ruthenium. As the ruthenium compound at this time, a compound such as a hydroxide that does not contain chloride ions is preferred.

[0119] When a ruthenium catalyst that does not contain metallic ruthenium is added during the partial hydrogenation reaction, it is preferred to use a ruthenium hydroxide support in which the above-mentioned ruthenium compound is supported on a support and treated with a base such as sodium hydroxide, or to use a mixture of ruthenium hydroxide and a dispersant obtained by adding a base such as sodium hydroxide to a mixture in which a dispersant and the above-mentioned ruthenium compound are present.

[0120] In addition, as the aforementioned ruthenium compound, a substance mainly composed of ruthenium obtained by adding other metals, metal compounds, such as zinc, chromium, molybdenum, tungsten, manganese, cobalt, nickel, iron, copper, gold, platinum, boron, lanthanum, cerium, etc., or compounds of these metals before or after the reduction of the ruthenium compound can also be used.

[0121] When using the other metals or metal compounds, the atomic ratio relative to the ruthenium atom is generally selected within the range of 0.001 to 20. Among the other metals or metal compounds, zinc and zinc compounds are preferred. Zinc and zinc compounds are preferably added before or during the reduction of the ruthenium compound, and as the amount thereof added, zinc is preferably set to 0.001 to 2 times by mass relative to ruthenium. Furthermore, from the viewpoint of catalyst activity and selectivity of cycloolefins, it is more preferred to use zinc at 0.005 to 1 times by mass relative to ruthenium.

[0122] As a method for preparing such a ruthenium-based catalyst containing other metals or metal compounds, for example: (1) a method in which a carrier is loaded with a ruthenium compound and other metals or metal compounds and then subjected to a reduction treatment; (2) a method in which a base such as sodium hydroxide is added to a solution containing a ruthenium compound and other metals or metal compounds to precipitate the ruthenium compound together with other metals in the form of an insoluble salt, and then the precipitated salt is reduced; (3) an insoluble ruthenium compound is loaded on a carrier as required and the ruthenium compound is reduced in a liquid phase containing other metal compounds; (4) a method in which the ruthenium compound and other metal compounds are both dissolved in the liquid phase and subjected to a reduction treatment, etc.

[0123] In the method for producing cycloolefin according to the first embodiment, a catalyst supported on a carrier can be used as the catalyst.

[0124] The carrier is not particularly limited, and examples thereof include oxides, composite oxides, hydroxides, sparingly water-soluble metal salts of metals such as magnesium, aluminum, silicon, calcium, titanium, vanadium, chromium, manganese, cobalt, iron, nickel, copper, zinc, zirconium, hafnium, tungsten, and boron, or compounds or mixtures thereof formed by chemically or physically combining two or more thereof.

[0125] Among these, zirconium oxide (zirconium dioxide) and zirconium hydroxide are preferred as carriers. In particular, zirconium oxide (zirconium dioxide) is preferred due to its excellent physical stability such as specific surface area under reaction conditions. The average particle size of zirconium oxide is preferably 0.05 to 30 μm, more preferably 0.05 to 10 μm. In addition, the specific surface area is preferably 20 to 200 m 2 / g, and the average pore diameter is preferably between 1 and 50 nm.

[0126] The method for supporting ruthenium on the carrier is not particularly limited, and examples thereof include adsorption method, ion exchange method, impregnation method, coprecipitation method, and dry solidification method.

[0127] The amount of the carrier used is not particularly limited, but is usually 1 to 1000 times by mass relative to ruthenium. In particular, when zirconium oxide (zirconium dioxide) is used as the carrier, it is preferably 1 to 100 times by mass relative to ruthenium, and more preferably 2 to 20 times by mass.

[0128] It should be noted that in the method for producing cycloolefins of the first embodiment, a ruthenium catalyst containing zirconium oxide is preferably used in the partial hydrogenation reaction of monocyclic aromatic hydrocarbons. When a ruthenium catalyst containing zirconium oxide is used, the carrier is zirconium oxide, or, when no carrier is used as described later, zirconium is used as a dispersant, which is oxidized to become zirconium oxide, and forms a catalyst together with ruthenium.

[0129] In addition, when ruthenium is used directly without being supported on a carrier, it is preferred to use oxides, composite oxides, hydroxides, sparingly water-soluble metal salts of metals such as magnesium, aluminum, silicon, calcium, titanium, vanadium, chromium, manganese, cobalt, iron, nickel, copper, zinc, zirconium, hafnium, tungsten, barium, and boron, or compounds or mixtures formed by chemically or physically combining two or more of them as dispersants.

[0130] And then, the average crystallite diameter of the metal ruthenium of the ruthenium catalyst used in the first embodiment is preferably below 20nm.When the average crystallite diameter is below 20nm, the surface area of ​​the catalyst is suitable, and therefore there are enough active sites, and the catalyst activity improves, so it is preferred.In addition, the lower limit of the average crystallite diameter is theoretically a value larger than the crystal unit, and is more than 1nm in practice.

[0131] (Zinc sulfate aqueous solution)

[0132] The partial hydrogenation reaction of monocyclic aromatic hydrocarbons in the method for producing cycloolefins of the first embodiment is carried out in an aqueous zinc sulfate solution. That is, the use of water is a necessary condition. The amount of water varies depending on the reaction form. The amount of water is preferably 0.5 to 20 times by mass relative to the monocyclic aromatic hydrocarbons as raw materials. In this range, the selectivity of cycloolefins can be kept high without making the reactor large-scale. More preferably, it is 1 to 10 times by mass relative to the monocyclic aromatic hydrocarbons used. In either case, it is necessary to have water in the reaction system in an amount that can form a state in which an organic liquid phase (oil phase) with raw materials and products as the main components and water are phase-separated, that is, a state of two liquid phases of oil phase and water phase. It should be noted that the main component mentioned here refers to the component that shows the largest proportion in terms of molar number among the components constituting the liquid phase.

[0133] The reaction system in the first embodiment is carried out in an aqueous zinc sulfate solution. The zinc sulfate needs to be at least partially or entirely dissolved in the aqueous phase.

[0134] <Zinc sulfate and metal sulfates>

[0135] In the production method of the first embodiment, the reaction system may contain other metal sulfates in addition to zinc sulfate.

[0136] Examples of other metal sulfates include sulfates of iron, nickel, cadmium, gallium, indium, magnesium, aluminum, chromium, manganese, cobalt, copper, etc. These may be used in combination of two or more, or may be a double salt containing the metal sulfates.

[0137] From the viewpoint of improving the catalyst activity and the selectivity of cycloolefins, the content of zinc sulfate in the above-mentioned zinc sulfate aqueous solution is preferably 1×10 -3 It is more preferably 0.1 to 1.0 mol / L, and even more preferably 0.4 to 0.9 mol / L.

[0138] It is preferable that the concentration of the metal sulfate other than zinc sulfate is appropriately set according to the type of the metal component.

[0139] <Metal Salt>

[0140] In addition, the following metal salt may be present in the reaction system in the method for producing cycloolefin according to the first embodiment, as in the conventional method.

[0141] As the aforementioned metal salt, there can be listed Group 1 metals such as lithium, sodium, potassium, etc., Group 2 metals such as magnesium and calcium (the group numbering is based on the revised version of IUPAC Inorganic Chemical Nomenclature (1989)), or nitrates, oxides, hydroxides, acetates, phosphates, etc. of metals such as zinc, manganese, cobalt, copper, cadmium, lead, arsenic, iron, gallium, germanium, vanadium, chromium, silver, gold, platinum, nickel, palladium, barium, aluminum, boron, etc., and two or more of them can also be used by chemically and / or physically mixing. Among them, regarding metal chlorides, since the concentration of chloride ions in the aqueous phase will have an adverse effect on the long-term performance of the catalyst, it is not preferred. As metal salts and metal oxides other than chlorides, zinc compounds such as zinc hydroxide and zinc oxide are preferred, and double salts containing zinc hydroxide are particularly preferred, such as the general formula (ZnSO4) m ·(Zn(OH)2) n The double salt shown has m:n=1:0.01 to 1:100.

[0142] The amount of the metal salt used is not particularly limited as long as the aqueous phase is kept acidic or neutral. -5 ~1×10 5 The metal salt can exist at any position in the reaction system and does not necessarily need to be completely dissolved in the aqueous phase.

[0143] <pH of the aqueous phase of the zinc sulfate aqueous solution>

[0144] The pH of the aqueous phase of the zinc sulfate aqueous solution used in the method for producing cycloolefin of the first embodiment is preferably acidic or neutral, 7.0 or less, from the viewpoint of improving the catalyst activity and the selectivity of cycloolefin.

[0145] <Chloride ion concentration>

[0146] In the method for producing cycloolefins of the first embodiment, the chloride ions dissolved in the water of the reaction system may adversely affect the long-term performance of the catalyst as described above. Therefore, the concentration of the chloride ions is preferably 300 mg / L or less. More preferably, it is 200 mg / L or less, and further preferably, it is 100 mg / L or less.

[0147] It should be noted that the chloride ion concentration refers to maintaining the concentration of chlorine Cl2, hypochlorous acid HClO, hypochlorite ion ClO - The free residual chlorine that exists in a state of equilibrium reacts with the ammonium ions in the water to form chloramines, and the combined residual chlorine in the form of Cl - The sum of all chlorine concentrations in the form of chlorine atoms and ions, obtained by adding all chloride ions in the form of

[0148] By setting the chloride ion concentration to 300 mg / L or less, in the first embodiment, it is possible to effectively suppress a decrease in activity and a decrease in cycloolefin selectivity when the ruthenium catalyst is used for a long period of time.

[0149] The reason why the reaction activity and cycloolefin selectivity of the ruthenium catalyst are reduced by the chloride ions dissolved in water is not necessarily clear, but is considered to be as follows.

[0150] If chloride ions are present, ruthenium dissolves in water and causes re-reduction. Thus, the sintering of ruthenium is promoted, causing the activity of the catalyst to decrease. At the same time, the interaction between ruthenium and the coexisting metal or metal compound changes. Since the metal or metal compound has an important effect on the cycloolefin selectivity, it is speculated that the cycloolefin selectivity also decreases.

[0151] In the first embodiment, the concentration of chloride ions dissolved in the aqueous phase containing the ruthenium catalyst can be controlled to 300 mg / L or less by controlling the concentration of chloride ions of each component present in the aqueous phase.

[0152] Specifically, by controlling the chloride ion concentration contained in each of the water, catalyst, dispersant, metal sulfate, metal salt, monocyclic aromatic hydrocarbon, and hydrogen supplied to the reaction system to a certain value or less, the chloride ion concentration dissolved in water can be controlled to 300 mg / L or less.

[0153] In the first embodiment, in addition to supplying monocyclic aromatic hydrocarbons and hydrogen to the reaction field, it is effective to re-supply water in an amount equivalent to the amount of water flowing out of the reaction field together with the reaction solution. The chloride ion content of the re-supplied water is preferably 20 mg / L or less. It is more preferably 10 mg / L or less, and further preferably 5 mg / L or less.

[0154] Examples of a method for controlling the chloride ion content in the resupplied water to fall within the above range include treatment with an ion exchange resin and distillation purification.

[0155] <Electrical Conductivity of Water Supplied to Reaction Field>

[0156] When the conductivity of the water supplied to the reaction field is expressed by a commonly used conductivity, it is preferably 0.5 μS / cm or less, and more preferably 0.3 μS / cm or less, from the viewpoint of maintaining high catalyst activity and selectivity for cycloolefins.

[0157] <Nitrogen Concentration in Aqueous Zinc Sulfate Solution>

[0158] In the method for producing cycloolefin according to the first embodiment, the nitrogen concentration in the aqueous zinc sulfate solution is set to a range of 0.5 to 3000 mg / L.

[0159] It should be noted that the nitrogen concentration in the zinc sulfate aqueous solution refers to the concentration obtained by calculating the content of nitrogen-containing components as the nitrogen atom content. The nitrogen concentration in the zinc sulfate aqueous solution can be measured by the method described in the Examples described below.

[0160] Examples of nitrogen-containing components mixed into the aqueous zinc sulfate solution include: monocyclic aromatic hydrocarbons as raw materials for producing cycloolefins, hydrogen impurities; components generated in the process of separating and purifying the raw materials, chemical reagents used, lubricating oils of equipment, etc.; and components resulting from the mixing of the extractant used in the process of separating and purifying the product through a partial hydrogenation reaction process and decomposition components of the extractant into the recycled monocyclic aromatic hydrocarbons.

[0161] Examples of nitrogen-containing components mixed into the aqueous zinc sulfate solution along with the monocyclic aromatic hydrocarbons and hydrogen as raw materials include monoethanolamine, ammonia, pyrrole, pyridine, quinoline, etc. In addition, examples of extractants and decomposition components of the extractants that enter the reactor through the recycled monocyclic aromatic hydrocarbons include dimethylacetamide and dimethylamine.

[0162] The zinc sulfate aqueous solution used in the method for producing cycloolefin of the first embodiment contains dimethylamine. Further, monoethanolamine, ammonia, and dimethylacetamide can be cited as nitrogen-containing components dissolved in the zinc sulfate aqueous solution.

[0163] In the first embodiment, the influence of the nitrogen concentration in the reaction system for partially hydrogenating monocyclic aromatic hydrocarbons on the reactivity of the partial hydrogenation reaction of monocyclic aromatic hydrocarbons was studied intensively, and as a result, it was found that the nitrogen-containing component reacted with the zinc sulfate aqueous solution, thereby changing the physical properties of the catalyst and affecting the above-mentioned reactivity. Therefore, the nitrogen concentration in the zinc sulfate aqueous solution, the nitrogen concentration in the monocyclic aromatic hydrocarbons, and the ratio of the nitrogen mass to the catalyst mass were controlled.

[0164] In the first embodiment, the total nitrogen concentration in the zinc sulfate aqueous solution is set to a range of 0.5 to 3000 mg / L in consideration of the influence of nitrogen-containing components on the partial hydrogenation reaction of monocyclic aromatic hydrocarbons.

[0165] When the nitrogen concentration in the aqueous zinc sulfate solution is 3000 mg / L or less, a decrease in the reaction activity of the ruthenium catalyst can be suppressed, and a decrease in selectivity can be prevented.

[0166] The reason why the concentration of nitrogen dissolved in the aqueous zinc sulfate solution affects the decrease in the reaction activity and selectivity of the ruthenium catalyst is considered to be as follows.

[0167] Most of the nitrogen-containing components entering the reaction field show alkalinity, which causes the salting out of zinc in the aqueous zinc sulfate solution. Since the salted-out zinc acts on the ruthenium catalyst, it modifies the reaction point of the ruthenium catalyst and causes the reaction activity to decrease. In addition, it is also believed that the nitrogen-containing components act as poisoning substances for the ruthenium catalyst and have an effect on the reduction of selectivity. Furthermore, in terms of the stable production of cycloolefins, it is necessary to suppress the reduction of the reaction activity of the ruthenium catalyst, and adopt a method of removing the salted-out zinc that will become the cause of the reduction of the catalyst activity. Specifically, the following method can be implemented: sulfuric acid is added to the reaction field of the aqueous zinc sulfate solution to dissolve the salted-out zinc, thereby suppressing the reduction of the reaction activity. Among them, the added sulfuric acid acts on the ruthenium catalyst, and the reduced activity gradually recovers, but on the other hand, the original ruthenium catalyst itself deteriorates, etc., which gradually affects the reduction of the selectivity.

[0168] As described above, the nitrogen concentration in the aqueous zinc sulfate solution is suppressed to 3000 mg / L or less, preferably suppressed to 1500 mg / L or less, more preferably suppressed to 1000 mg / L or less, and further preferably suppressed to 650 mg / L or less.

[0169] As a method for suppressing the concentration of nitrogen dissolved in the zinc sulfate aqueous solution to 3000 mg / L or less, a method for suppressing the concentration of nitrogen-containing components in the raw materials used for the production of cycloolefins including recycled monocyclic aromatic hydrocarbons is effective.

[0170] It is preferred that the concentration of nitrogen-containing components entering the reactor through the raw materials of monocyclic aromatic hydrocarbons and hydrogen be sufficiently reduced in the raw material purification step. In addition, it is also preferred that the concentration of nitrogen-containing components in the monocyclic aromatic hydrocarbons is reduced by distillation purification during the separation and recovery of the monocyclic aromatic hydrocarbons and the extractant used as the nitrogen-containing components, and / or a nitrogen-containing component removal step be added.

[0171] However, there is a limit to the reduction of the nitrogen concentration in the zinc sulfate aqueous solution. Considering that the scale of the nitrogen-containing component removal equipment becomes larger, the energy load in the operation of the removal equipment becomes larger, and the economic burden also becomes larger, it is preferred to manage the nitrogen concentration in the zinc sulfate aqueous solution to 0.5 mg / L or more. By setting it to 15 mg / L or more, the energy load and economic burden in the operation of the removal equipment can be further suppressed.

[0172] (Partial replacement of zinc sulfate aqueous solution)

[0173] The nitrogen concentration in the zinc sulfate aqueous solution is caused by the nitrogen-containing components entering from the raw materials including the recycled monocyclic aromatic hydrocarbons. On the other hand, the nitrogen-containing components entering are not all accumulated in the zinc sulfate aqueous solution, but a part of them is taken out of the reactor system together with the reaction products. That is, by suppressing the nitrogen-containing components entering the reaction field, the nitrogen concentration in the zinc sulfate aqueous solution can be reduced.

[0174] On the other hand, in order to reduce the amount of nitrogen-containing components entering from the raw materials including the recycled monocyclic aromatic hydrocarbons, it is necessary to increase the load of the purification process of each raw material, increase the nitrogen-containing component removal process, etc. Furthermore, if the nitrogen concentration in the zinc sulfate aqueous solution in the reaction field becomes high, even if the nitrogen-containing components are slowly discharged out of the reactor system together with the reaction products, it takes a long time to reduce the nitrogen concentration in the zinc sulfate aqueous solution. Therefore, a method for reducing the nitrogen concentration in the zinc sulfate aqueous solution in the reaction field was studied, and it was found that it is effective to partially replace a part of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution with a low nitrogen concentration.

[0175] By replacing the zinc sulfate aqueous solution with a new one, the nitrogen concentration in the zinc sulfate aqueous solution that has temporarily increased is reduced, and thus the reactivity that has been reduced due to the influence of the nitrogen concentration is gradually restored. That is, even if the nitrogen concentration in the zinc sulfate aqueous solution temporarily deviates from the appropriate range of 0.5 to 3000 mg / L, by replacing a portion of the zinc sulfate aqueous solution with a new one as described above, the nitrogen concentration can be restored to the above-mentioned appropriate range.

[0176] (Nitrogen concentration in monocyclic aromatic hydrocarbons)

[0177] In the method for producing cycloolefins according to the first embodiment, the nitrogen concentration contained in the monocyclic aromatic hydrocarbons is preferably in the range of 0.003 to 35 mg / L.

[0178] It should be noted that the monocyclic aromatic hydrocarbons in this case include both the monocyclic aromatic hydrocarbons used as raw materials at the beginning of the production process and the monocyclic aromatic hydrocarbons recycled.

[0179] The nitrogen-containing components entering the reaction field from the monocyclic aromatic hydrocarbons as raw materials include components derived from the base raw materials, nitrogen-containing components generated during the separation and purification process, and nitrogen-containing components mixed in via lubricating oils derived from used chemical reagents and equipment.

[0180] In addition, as components entering the reactor through the monocyclic aromatic hydrocarbons that have passed through the partial hydrogenation reaction step and are recycled from the product separation and purification step, there are extractants used in the post-hydrogenation step and components obtained by decomposition of the extractants.

[0181] Nitrogen-containing components are impurities in monocyclic aromatic hydrocarbons, so in order to remove impurities or reduce the amount of impurities, it is necessary to adjust the equipment and operating conditions used for separation and purification. In order to remove nitrogen-containing components with different boiling points by distillation purification, it is required to apply distillation column design and operating conditions based on achieving the target nitrogen concentration in monocyclic aromatic hydrocarbons.

[0182] In addition, as a method for reducing and removing impurities other than distillation purification, there is a need for equipment that can reduce and remove nitrogen-containing components using an adsorbent or extract and remove nitrogen-containing components from monocyclic aromatic hydrocarbons.

[0183] Examples of methods for reducing and removing nitrogen-containing components using an adsorbent include methods using an adsorption tower filled with activated alumina, silica / alumina, montmorillonite, zeolite, or the like as an adsorbent.

[0184] When reducing and removing nitrogen-containing components dissolved in water, it is effective to apply a method using a water scrubber such as a method of immersing monocyclic aromatic hydrocarbons in water.

[0185] Furthermore, when nitrogen-containing components are generated during the purification and recycling of raw materials, it is necessary to study how to suppress the factors that cause the generation, thereby minimizing the mixing of nitrogen-containing components into monocyclic aromatic hydrocarbons. For example, when the nitrogen-containing component is a thermally decomposed substance, a method of lowering the temperature of the generating portion of the nitrogen-containing component, when the nitrogen-containing component is a hydrolysis product, a method of suppressing the mixing of water, etc. are effective.

[0186] By setting the nitrogen concentration in all monocyclic aromatic hydrocarbons entering the reaction field of the zinc sulfate aqueous solution to 35 mg / L or less, it becomes easy to control the nitrogen concentration in the zinc sulfate aqueous solution to 3000 mg / L or less, thereby preventing the reactivity of the partial hydrogenation reaction from decreasing.

[0187] That is, the nitrogen concentration in all monocyclic aromatic hydrocarbons is preferably 35 mg / L or less, more preferably 16 mg / L or less, and further preferably 10 mg / L or less.

[0188] In addition, when the nitrogen concentration in all monocyclic aromatic hydrocarbons is reduced to less than 0.003 mg / L, the cost of equipment for reducing the removal of nitrogen-containing components increases, the operating load for low-concentration management of trace nitrogen-containing components, and the analytical management load become larger. Therefore, the lower limit of the nitrogen concentration in all monocyclic aromatic hydrocarbons is preferably set to 0.003 mg / L or more, and from the viewpoint of reducing the management load, it is more preferably set to 0.01 mg / L or more.

[0189] The nitrogen concentration in the monocyclic aromatic hydrocarbons can be measured by the method described in the Examples below.

[0190] The nitrogen concentration contained in the monocyclic aromatic hydrocarbons can be controlled within the above-mentioned numerical range by carrying out a nitrogen removal step such as purification of the monocyclic aromatic hydrocarbons used as a raw material and distillation purification of the recycled monocyclic aromatic hydrocarbons.

[0191] (Ratio of the mass of nitrogen in the nitrogen-containing component to the mass of the ruthenium catalyst)

[0192] In the method for producing cycloolefins according to the first embodiment, the ratio of the nitrogen-containing component in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst in terms of nitrogen mass is preferably 5×10 -6 ~8×10 -2 More preferably, it is 1×10 -5 ~5×10 -2 times, more preferably 1.5×10 -5 ~3×10 -2 times.

[0193] The ratio of the mass of nitrogen in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst can be calculated by the following method: the zinc sulfate aqueous solution containing the ruthenium catalyst is taken out from the hydrogenation reaction field in a completely mixed state, filtered, washed with water, and dried, the solid ruthenium catalyst is measured, and the nitrogen concentration in the filtrate is measured by the method described in the examples described later, and the masses of the two components are obtained to calculate.

[0194] The ratio of the mass of nitrogen to the mass of the ruthenium catalyst can be controlled within the above numerical range by reducing the nitrogen concentration in the aqueous zinc sulfate solution or adjusting the amount of the ruthenium catalyst added.

[0195] In the first embodiment, a ruthenium catalyst is used as a catalyst for producing cycloolefins by partial hydrogenation of monocyclic aromatic hydrocarbons. Ruthenium plays the role of adsorbing monocyclic aromatic hydrocarbons and hydrogen in an aqueous zinc sulfate solution and desorbing them in the form of cycloolefins. In such an effect, when the nitrogen-containing component enters the aqueous zinc sulfate solution, the zinc in the aqueous zinc sulfate solution solidifies in the form of zinc hydroxide, zinc sulfate and zinc hydroxide complex salt. The zinc hydroxide, zinc sulfate and zinc hydroxide complex salt suppresses the partial hydrogenation reaction in the form of covering the reaction point of ruthenium, resulting in the influence of reducing the reaction activity.

[0196] On the other hand, in order to stably produce cycloolefins, it is necessary to add sulfuric acid to the zinc sulfate aqueous solution to reduce the zinc that is the cause of the reduced activity. By adding sulfuric acid to the reaction field, the reduced activity is gradually restored. On the other hand, in the original catalyst design stage, in addition to the adsorption of monocyclic aromatic hydrocarbons and hydrogen to ruthenium, the zinc in the catalyst that has an effect on the desorption of cycloolefins will also be dissolved by the addition of sulfuric acid, reducing the selectivity for cycloolefins. Therefore, within the range that does not affect the reaction inhibition of the ruthenium catalyst, it is necessary to reduce the ratio of the nitrogen mass to the mass of the ruthenium catalyst.

[0197] From the above viewpoints, the amount of nitrogen-containing components in the zinc sulfate aqueous solution is preferably adjusted so that the ratio of the nitrogen-containing components to the mass of the ruthenium catalyst is 8×10 -2 times or less, more preferably 5×10 -2 times or less, more preferably 3×10 -2 times or less.

[0198] It should be noted that the ratio of the nitrogen-containing component in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst in terms of nitrogen mass is maintained at less than 5×10 -6 When the amount of nitrogen is increased, in terms of raw material purification and separation including recycling, the increase in equipment for reducing and removing nitrogen-containing components, the operating load for low-concentration management of trace nitrogen-containing components, and the load of analytical management are large.

[0199] Furthermore, it is considered that the zinc effect of slight salting out due to the presence of a slight amount of nitrogen-containing components in the zinc sulfate aqueous solution within a range where there is no influence of the decrease in the activity of the ruthenium catalyst and no need to manage the addition of sulfuric acid may also contribute to the stabilization of the selectivity of cycloolefins. Therefore, the ratio of the mass of nitrogen in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is preferably not less than 5×10 -6 times, preferably not less than 1×10 -5 times, preferably not less than 1.5×10 -5 times.

[0200] As described above, in the first embodiment, it is preferred that the nitrogen concentration in the zinc sulfate aqueous solution is set to 0.5 to 1500 mg / L, the nitrogen concentration in the monocyclic aromatic hydrocarbon is set to 0.01 to 16 mg / L, and the ratio of the mass of nitrogen in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is set to 1×10 -5 ~5×10 -2 times, partial hydrogenation of monocyclic aromatic hydrocarbons is carried out to produce cycloolefins.

[0201] As a result, the catalytic activity of the partial hydrogenation reaction of monocyclic aromatic hydrocarbons and the high selectivity of cycloolefins can be maintained, the performance of the ruthenium catalyst can be stabilized, and when cycloolefins are produced for a long time, complicated operations such as replacing the ruthenium catalyst and adding the ruthenium catalyst can be reduced, the decrease in the selectivity of cycloolefins can be effectively suppressed, and cycloolefins can be produced stably and efficiently for a long time.

[0202] (Nitrogen-containing ingredients)

[0203] The nitrogen-containing components showing the nitrogen concentration in the zinc sulfate aqueous solution of the present embodiment are substances that enter the reaction system through recycled monocyclic aromatic hydrocarbons in addition to substances that enter the reaction system through monocyclic aromatic hydrocarbons and hydrogen, which are raw materials for producing cycloolefins.

[0204] Examples of the substance include components such as dimethylamine, dimethylacetamide, monoethanolamine, ammonia, pyrrole, pyridine, and quinoline.

[0205] According to the investigation and research by the present inventors, it is known that among these nitrogen-containing components, dimethylamine is a substance contained in the aqueous zinc sulfate solution in a large amount.

[0206] In the method for producing cycloolefin according to the first embodiment, dimethylamine is contained in the zinc sulfate aqueous solution.

[0207] The dimethylamine is a decomposition product of dimethylacetamide used as an extraction solvent in a product separation and purification step after a partial hydrogenation reaction step.

[0208] Dimethylamine is produced by hydrolysis, thermal decomposition, etc. caused by a small amount of water introduced during the product separation and purification process, and is mixed into the aqueous zinc sulfate solution entering the hydrogenation reaction system while recycling monocyclic aromatic hydrocarbons.

[0209] In addition, when dimethylacetamide is hydrolyzed, acetic acid is generated in addition to dimethylamine. The acetic acid serves as a catalyst for promoting the decomposition of dimethylacetamide, which affects the increase of dimethylamine. Furthermore, the substance that enters the hydrogenation reaction system as dimethylacetamide may also be hydrolyzed in the zinc sulfate aqueous solution to form dimethylamine. Due to such an influence, dimethylamine occupies a large proportion as a nitrogen-containing component contained in the zinc sulfate aqueous solution.

[0210] As described above, in the first embodiment, it is important to manage the concentration of dimethylamine in the aqueous zinc sulfate solution.

[0211] (Concentration of dimethylamine in zinc sulfate aqueous solution)

[0212] In the method for producing cycloolefins according to the first embodiment, the concentration of dimethylamine in the aqueous zinc sulfate solution to which the ruthenium catalyst is added is preferably in the range of 1.7 to 9900 mg / L, more preferably in the range of 1.7 to 4950 mg / L, more preferably in the range of 1.7 to 3300 mg / L, more preferably in the range of 40 to 1700 mg / L, and even more preferably in the range of 80 to 1000 mg / L.

[0213] By setting the concentration of dimethylamine in the zinc sulfate aqueous solution to 1.7 mg / L or more, in addition to the load reduction effect on the device and operation, the effect of maintaining the stability of the ruthenium catalyst performance can be achieved. By setting it to below 9900 mg / L, the effect of suppressing the activity of the ruthenium catalyst and reducing the selectivity of cycloolefins can be achieved.

[0214] The concentration of dimethylamine in the aqueous zinc sulfate solution can be measured by the method described in Examples below.

[0215] The concentration of dimethylamine in the aqueous zinc sulfate solution can be controlled within the above numerical range by adjusting the distillation separation performance of dimethylamine entering the reactor through the recycled monocyclic aromatic hydrocarbons; adjusting the conditions of the equipment for removing the nitrogen component in the monocyclic aromatic hydrocarbons before entering the reactor; adjusting the conditions of the extraction and separation step that serves as the generation source of dimethylamine; and taking the aqueous zinc sulfate solution containing dimethylamine out of the reaction system and replenishing the reactor with a new aqueous zinc sulfate solution.

[0216] (Dimethylamine concentration in monocyclic aromatic hydrocarbons)

[0217] The concentration of dimethylamine in all monocyclic aromatic hydrocarbons entering the reaction field of the aqueous zinc sulfate solution including recycled monocyclic aromatic hydrocarbons is preferably in the range of 0.01 to 115 mg / L, more preferably in the range of 0.04 to 52 mg / L, and even more preferably in the range of 0.04 to 33 mg / L.

[0218] By setting the concentration of dimethylamine in monocyclic aromatic hydrocarbons to 0.01 mg / L or more, in addition to the load reduction effect on the device and operation, the effect of maintaining the stability of the ruthenium catalyst performance can be achieved. By setting it to 115 mg / L or less, the effect of suppressing the increase in the concentration of dimethylamine in the zinc sulfate aqueous solution can be achieved.

[0219] The concentration of dimethylamine in the monocyclic aromatic hydrocarbons can be measured by the method described in the Examples below.

[0220] The concentration of dimethylamine in monocyclic aromatic hydrocarbons can be controlled within the above numerical range by adjusting the conditions for separation and purification of monocyclic aromatic hydrocarbons, the conditions for dimethylamine removal equipment, and the conditions for the extraction and separation step that is the source of dimethylamine.

[0221] (Ratio of the mass of dimethylamine to the mass of ruthenium catalyst)

[0222] Furthermore, the ratio of the mass of dimethylamine in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is preferably 2×10 -5 ~0.26 times, more preferably 4×10 -5 The range is 5×10 -5 ~0.1 times, more preferably 8×10 -4 ~6×10 -2 times, more preferably 1×10 -3 ~4×10 -2 times the range.

[0223] By setting the ratio of the mass of dimethylamine to the mass of the ruthenium catalyst to 2×10 -5 By setting the catalyst pressure to 0.26 times or more, in addition to the load reduction effect on the device and operation, the performance of the ruthenium catalyst can be kept stable. By setting the catalyst pressure to 0.26 times or less, the activity of the ruthenium catalyst and the selectivity of cycloolefins can be stabilized.

[0224] The ratio of the mass of dimethylamine to the mass of the ruthenium catalyst can be measured by the method described in Examples below.

[0225] The ratio of the mass of dimethylamine to the mass of the ruthenium catalyst can be controlled within the above numerical range by reducing the amount of dimethylamine in the aqueous zinc sulfate solution or adjusting the amount of the ruthenium catalyst added.

[0226] (Acetic acid concentration in zinc sulfate aqueous solution)

[0227] In the method for producing cycloolefins according to the first embodiment, it is preferred that the concentration of acetic acid in the aqueous zinc sulfate solution be 1×10 -3 The range is from 100mg / L to 200mg / L.

[0228] Acetic acid is subjected to a partial hydrogenation reaction step and product separation, followed by a purification step of monocyclic aromatic hydrocarbons for recycling, and the monocyclic aromatic hydrocarbons recycled enter the reactor.

[0229] The reaction liquid subjected to the partial hydrogenation reaction contains partially hydrogenated cycloolefins, completely hydrogenated cycloalkanes, and unreacted monocyclic aromatic hydrocarbons. In order to separate the reaction liquid, dimethylacetamide, which is a known extractant, is used. When dimethylacetamide is used as the extractant, acetic acid is generated as a decomposition product and cannot be sufficiently separated in the purification step of the recycled monocyclic aromatic hydrocarbons. In this case, the acetic acid is mixed into the reaction field of the partial hydrogenation together with the recycled monocyclic aromatic hydrocarbons.

[0230] By setting the acetic acid concentration in the zinc sulfate aqueous solution as the reaction site to 100 mg / L or less, it is possible to suppress a decrease in the reaction selectivity of the catalyst. The acetic acid concentration in the zinc sulfate aqueous solution is preferably 75 mg / L or less, more preferably 50 mg / L or less.

[0231] The effect of acetic acid on the reaction selectivity of the catalyst is believed to have an adverse effect on the adsorption and desorption of monocyclic aromatic hydrocarbons and cycloolefins as raw materials on the catalyst. In the reaction field, monocyclic aromatic hydrocarbons dissolved in the aqueous phase of the zinc sulfate aqueous solution are partially hydrogenated on the catalyst to become cycloolefins and detach from the catalyst. The presence of acetic acid is believed to have the following effects: the acetic acid modifies the catalyst surface and promotes the reaction of monocyclic aromatic hydrocarbons in the oil phase, resulting in an increase in cycloalkanes, and in the aqueous phase, the reaction product is difficult to detach from the catalyst surface until it is converted from cycloolefins to cycloalkanes.

[0232] The acetic acid concentration in the aqueous zinc sulfate solution can be measured by the method described in Examples below.

[0233] The acetic acid concentration in the aqueous zinc sulfate solution can be measured by ion chromatography (IC).

[0234] As a method of controlling the acetic acid concentration in the zinc sulfate aqueous solution to 100 mg / L or less, there is a method of suppressing the acetic acid concentration contained in the recycled monocyclic aromatic hydrocarbons to be low.

[0235] In the separation of the recycled monocyclic aromatic hydrocarbons and the extractant, it is effective to reduce the concentration of acetic acid in the recycled monocyclic aromatic hydrocarbons by appropriately setting the distillation purification conditions. In addition, since acetic acid is a decomposition product of dimethylacetamide used as the extractant, it is effective to prevent water that promotes decomposition from entering the extraction and separation step in which dimethylacetamide is present, or to prevent the temperature in the separation step from increasing excessively.

[0236] However, there is a practical limit to the reduction of the acetic acid concentration in the zinc sulfate aqueous solution. According to the load of the purification and separation equipment and the load of the operating conditions, the acetic acid concentration in the zinc sulfate aqueous solution is preferably controlled to 1×10 -3 mg / L or more, and further, if 1×10 -2mg / L or above, management becomes easy.

[0237] In the first embodiment, acetic acid in the aqueous zinc sulfate solution is introduced from the raw materials including the recycled monocyclic aromatic hydrocarbons, but not all of the introduced acetic acid is accumulated in the aqueous zinc sulfate solution, and a portion of the acetic acid is taken out of the reactor system together with the reaction product. That is, by reducing the amount of acetic acid introduced into the reaction field, the concentration of acetic acid in the aqueous zinc sulfate solution can be reduced.

[0238] On the other hand, in order to reduce the acetic acid entering from the raw materials including the recycled monocyclic aromatic hydrocarbons, it is necessary to increase the load of the separation and purification process of the recycled monocyclic aromatic hydrocarbons and to suppress the decomposition of dimethylacetamide as an extractant. Furthermore, it takes time to gradually discharge the acetic acid that has temporarily entered the zinc sulfate aqueous solution together with the reaction product to reduce the amount of acetic acid. Therefore, as a method for reducing the acetic acid concentration in the zinc sulfate aqueous solution in the reaction field, a method of replacing a part of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution that does not contain acetic acid is effective.

[0239] By replacing the zinc sulfate aqueous solution with a new one, the acetic acid concentration in the zinc sulfate aqueous solution that temporarily increased was reduced, thereby recovering the reactivity that was reduced due to the influence of acetic acid. That is, even if the acetic acid concentration in the zinc sulfate aqueous solution temporarily deviated from 1×10 -3 The appropriate range of acetic acid concentration is 100 mg / L to 200 mg / L. The acetic acid concentration can be returned to the above appropriate range by the above replacement operation.

[0240] (Acetic acid concentration contained in monocyclic aromatic hydrocarbons)

[0241] In the method for producing cycloolefins according to the first embodiment, it is preferred that the concentration of acetic acid contained in the monocyclic aromatic hydrocarbons be 1×10 -4 The range is ~5mg / L.

[0242] It should be noted that the monocyclic aromatic hydrocarbons in this case include both the monocyclic aromatic hydrocarbons used initially in the production process and the monocyclic aromatic hydrocarbons recycled.

[0243] Acetic acid in monocyclic aromatic hydrocarbons can be reduced by suppressing its generation in the extraction and separation process, removing or reducing the generated substances as impurities of monocyclic aromatic hydrocarbons, separation and purification, reduction and removal using adsorbents, water washing treatment of monocyclic aromatic hydrocarbons, etc., and can be controlled to the above-mentioned numerical range.

[0244] By limiting the acetic acid concentration in the monocyclic aromatic hydrocarbons to 5 mg / L or less, the rate at which the acetic acid concentration in the aqueous zinc sulfate solution gradually increases can be suppressed, thereby preventing a decrease in the performance of the partial hydrogenation reaction.

[0245] That is, the acetic acid concentration in the monocyclic aromatic hydrocarbons is preferably 5 mg / L or less, more preferably 3 mg / L or less, and even more preferably 1.5 mg / L or less.

[0246] On the other hand, the concentration of acetic acid in the monocyclic aromatic hydrocarbons is reduced to less than 1×10 -4 mg / L, the operation load for reducing and removing acetic acid, low concentration management, and analysis management load increase, so the lower limit is preferably set to 1×10 -4 mg / L or more, by setting it to 1×10 -3 mg / L or above, the operating load and analysis load of separation and purification can be reduced.

[0247] The acetic acid concentration contained in the monocyclic aromatic hydrocarbons is determined by adding water to the aromatic hydrocarbon sample to be measured, concentrating and extracting, and measuring the extracted water by ion chromatography. Samples with a concentration of 1 mg / L or more can be analyzed using gas chromatography (GC).

[0248] (Ratio of the mass of acetic acid to the mass of ruthenium catalyst)

[0249] In the method for producing cycloolefins according to the first embodiment, it is preferred that the ratio of the mass of acetic acid to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution be 3×10 -9 ~2.5×10 -3 More preferably, it is 1×10 -8 ~2×10 -3 times, more preferably 1×10 -7 ~1.5×10 -3 times, more preferably 1×10 -6 ~5×10 -4 times, more preferably 3×10 -6 ~5×10 -4 The ratio of the mass of acetic acid in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst can be calculated as the ratio of the amount of acetic acid in the zinc sulfate aqueous solution (mg / L) to the total solid catalyst concentration in the reaction solution (mg / L).

[0250] In the first embodiment, a ruthenium catalyst is used as a catalyst for producing cycloolefins by partial hydrogenation of monocyclic aromatic hydrocarbons.

[0251] Ruthenium has the function of adsorbing monocyclic aromatic hydrocarbons and hydrogen in the aqueous zinc sulfate solution and desorbing them in the form of cycloolefins. In such a function, if acetic acid enters the aqueous zinc sulfate solution, the reactivity of the ruthenium catalyst will be suppressed. Therefore, the amount of acetic acid is preferably within a range that does not affect the reaction inhibition of the ruthenium catalyst, and the acetic acid concentration in the aqueous zinc sulfate solution as acetic acid present in the reaction field, the acetic acid concentration contained in the recycled monocyclic aromatic hydrocarbons, and the acetic acid concentration relative to the catalyst are preferably managed. It should be noted that when the acetic acid concentration in the aqueous zinc sulfate solution and the acetic acid concentration relative to the catalyst rise above the preferred range, if the acetic acid concentration returns to the preferred range by replacing the aqueous zinc sulfate solution in the reaction field, the reactivity of the ruthenium catalyst can be restored.

[0252] (Preferred Mode of the Method for Producing Cycloolefin in the First Embodiment)

[0253] The method for producing cycloolefin in the first embodiment comprises:

[0254] A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution;

[0255] After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound;

[0256] A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and

[0257] The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the above-mentioned reaction step.

[0258] In the reaction step, the content of dimethylamine in the aqueous zinc sulfate solution is preferably controlled to be 40 to 1700 mg / L, and the mass ratio of dimethylamine to the mass of the ruthenium catalyst is controlled to be 8×10 -4 ~6×10 -2 times.

[0259] Thus, the catalyst activity of the partial hydrogenation reaction and the high selectivity of cycloolefins can be maintained, and the catalyst activity and the high selectivity of cycloolefins can be maintained even after the catalyst is regenerated. By stabilizing the catalyst activity, the number of complicated operations such as replacing the catalyst and adding unused catalysts can be reduced when producing cycloolefins for a long time, the selectivity of cycloolefins can be effectively suppressed, and cycloolefins can be produced efficiently and stably for a long time.

[0260] The content of dimethylamine in the aqueous zinc sulfate solution can be controlled within the above numerical range by adjusting the distillation separation performance of dimethylamine entering the reactor through the recycled monocyclic aromatic hydrocarbons; adjusting the conditions of the equipment for removing the nitrogen component in the monocyclic aromatic hydrocarbons before entering the reactor; adjusting the conditions of the extraction and separation step that serves as the generation source of dimethylamine; and taking the aqueous zinc sulfate solution containing dimethylamine out of the reaction system and replenishing the reactor with a new aqueous zinc sulfate solution.

[0261] The amount of water contacted in the water washing step is preferably 0.05 to 0.8 times by volume, more preferably 0.08 to 0.6 times by volume, based on the monocyclic aromatic hydrocarbon.

[0262] The ratio of the mass of dimethylamine to the mass of the ruthenium catalyst can be controlled within the above numerical range by reducing the amount of dimethylamine in the aqueous zinc sulfate solution or adjusting the amount of the ruthenium catalyst added.

[0263] [Method for producing cycloolefin according to the second embodiment]

[0264] The method for producing cycloolefins according to the second embodiment (hereinafter sometimes referred to as the present embodiment) is a method for producing cycloolefins by partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst.

[0265] In the second embodiment, the concentration of acetic acid in the zinc sulfate aqueous solution is set to 1×10 -3 ~100mg / L, for partial hydrogenation reaction.

[0266] According to the second embodiment, the catalyst activity of the partial hydrogenation reaction and the high selectivity of cycloolefins can be maintained, and the catalyst activity and the high selectivity of cycloolefins can be maintained even after the catalyst is regenerated. By stabilizing the catalyst performance, the number of complicated operations such as replacing the catalyst and adding unused catalysts can be reduced when producing cycloolefins for a long time, the selectivity of cycloolefins can be effectively suppressed, and cycloolefins can be produced efficiently and stably for a long time.

[0267] (monocyclic aromatic hydrocarbons)

[0268] In the method for producing cycloolefin according to the second embodiment, monocyclic aromatic hydrocarbons are used as a raw material.

[0269] Examples of the monocyclic aromatic hydrocarbon include, but are not limited to, benzene, toluene, and xylene, which are benzenes substituted with an alkyl group having 1 to 4 carbon atoms, and the same ones as those in the first embodiment can be used.

[0270] (Hydrogen pressure)

[0271] In the second embodiment, from the same viewpoint as in the first embodiment, the hydrogen pressure during the partial hydrogenation reaction using hydrogen is usually 1 to 20 MPa, preferably 2 to 7 MPa.

[0272] (Reaction temperature)

[0273] The temperature during the partial hydrogenation reaction is usually 50 to 250°C, preferably 100 to 200°C, from the same viewpoint as in the first embodiment.

[0274] (Ruthenium Catalyst)

[0275] In the second embodiment, the partial hydrogenation reaction of monocyclic aromatic hydrocarbons is carried out in the presence of a ruthenium catalyst.

[0276] The ruthenium catalyst is preferably a catalyst containing metallic ruthenium obtained by reducing various ruthenium compounds in advance, and the same ruthenium catalyst as used in the first embodiment can be used.

[0277] (Zinc sulfate aqueous solution)

[0278] The partial hydrogenation reaction of monocyclic aromatic hydrocarbons in the method for producing cycloolefins of the second embodiment is carried out in an aqueous zinc sulfate solution. As the aqueous zinc sulfate solution, the same material as the aqueous zinc sulfate solution used in the first embodiment can be used. It should be noted that in the second embodiment, the acetic acid concentration in the aqueous zinc sulfate solution is limited to a predetermined numerical range. The acetic acid concentration will be described later.

[0279] <Acetic acid concentration in zinc sulfate aqueous solution>

[0280] In the method for producing cycloolefins according to the second embodiment, the concentration of acetic acid in the aqueous zinc sulfate solution is set to 1×10 -3 The range is from 100mg / L to 200mg / L.

[0281] Acetic acid enters the reactor through monocyclic aromatic hydrocarbons as raw materials, and in particular, monocyclic aromatic hydrocarbons that have been recycled through a partial hydrogenation reaction step, separation from products, and a subsequent purification step of monocyclic aromatic hydrocarbons for recycling enter the reactor.

[0282] The reaction liquid subjected to the partial hydrogenation reaction contains partially hydrogenated cycloolefins, completely hydrogenated cycloalkanes, and unreacted monocyclic aromatic hydrocarbons. In order to separate the reaction liquid, dimethylacetamide, which is a known extractant, is used. When dimethylacetamide is used as the extractant, acetic acid is generated as a decomposition product and cannot be fully separated in the purification step of the recycled monocyclic aromatic hydrocarbons. In this case, acetic acid is mixed into the reaction field of the partial hydrogenation together with the recycled monocyclic aromatic hydrocarbons.

[0283] By setting the acetic acid concentration in the zinc sulfate aqueous solution as the reaction site to 100 mg / L or less, it is possible to suppress a decrease in the reaction selectivity of the catalyst. The acetic acid concentration in the zinc sulfate aqueous solution is preferably 75 mg / L or less, more preferably 50 mg / L or less.

[0284] The effect of acetic acid on the reaction selectivity of the catalyst is believed to have an adverse effect on the adsorption and desorption of monocyclic aromatic hydrocarbons and cycloolefins as raw materials on the catalyst. In the hydrogenation reaction field, monocyclic aromatic hydrocarbons dissolved in the aqueous phase of the zinc sulfate aqueous solution are partially hydrogenated on the catalyst to become cycloolefins and detach from the catalyst. The presence of acetic acid is believed to have the following effects: the aforementioned acetic acid modifies the catalyst surface to promote the reaction of monocyclic aromatic hydrocarbons in the oil phase, resulting in an increase in cycloalkanes, and in the aqueous phase, the reaction product is difficult to detach from the catalyst surface until it is converted from cycloolefins to cycloalkanes.

[0285] The acetic acid concentration in the aqueous zinc sulfate solution can be measured by the method described in Examples below.

[0286] The acetic acid concentration in the aqueous zinc sulfate solution can be measured by ion chromatography (IC).

[0287] As a method for suppressing the acetic acid concentration in the zinc sulfate aqueous solution to 100 mg / L or less, there is a method of suppressing the acetic acid concentration contained in the recycled monocyclic aromatic hydrocarbons to be low.

[0288] In the separation process of the recycled monocyclic aromatic hydrocarbons and the extractant, it is effective to reduce the concentration of acetic acid in the recycled monocyclic aromatic hydrocarbons by appropriately setting the distillation purification conditions. In addition, in order to reduce the acetic acid generated in the distillation purification, it is also effective to apply the following methods: a method of using a purification tower for dimethylacetamide as an extractant and discharging acetic acid from the extraction and separation process to the outside of the system together with other impurities; a method of using a water washing tower to reduce acetic acid in the recycled monocyclic aromatic hydrocarbons. Furthermore, since acetic acid is a decomposition product of dimethylacetamide used as an extractant, it is also effective to prevent water that promotes decomposition from entering the extraction and separation process where dimethylacetamide is present and to devise a method to prevent the temperature in the separation process from rising excessively.

[0289] However, there is a practical limit to the reduction of the acetic acid concentration in the zinc sulfate aqueous solution. According to the load of the purification and separation equipment and the load of the operating conditions, the acetic acid concentration in the zinc sulfate aqueous solution is preferably controlled to 1×10 -3 mg / L or more, and further, if 1×10 -2 mg / L or above, management becomes easy.

[0290] (Partial replacement of zinc sulfate aqueous solution)

[0291] In the first embodiment, acetic acid in the aqueous zinc sulfate solution is introduced from the raw materials including the recycled monocyclic aromatic hydrocarbons, but the introduced acetic acid is not entirely accumulated in the aqueous zinc sulfate solution, but a portion of it is taken out of the reactor system together with the reaction product. That is, by reducing the amount of acetic acid introduced into the reaction field, the concentration of acetic acid in the aqueous zinc sulfate solution can be reduced.

[0292] On the other hand, in order to reduce the acetic acid entering from the raw materials including the recycled monocyclic aromatic hydrocarbons, it is necessary to increase the load of the separation and purification process of the recycled monocyclic aromatic hydrocarbons and to suppress the decomposition of dimethylacetamide as an extractant. Furthermore, it takes time to gradually reduce the acetic acid that temporarily enters the zinc sulfate aqueous solution together with the reaction products. Therefore, as a method for reducing the acetic acid concentration in the zinc sulfate aqueous solution in the reaction field, it is effective to replace part of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution, that is, a zinc sulfate aqueous solution that does not contain acetic acid.

[0293] By replacing the zinc sulfate aqueous solution with a new one, the acetic acid concentration in the zinc sulfate aqueous solution that temporarily increased was reduced, thereby recovering the reactivity that was reduced due to the influence of acetic acid. That is, even if the acetic acid concentration in the zinc sulfate aqueous solution temporarily deviated from 1×10 -3 The appropriate range of acetic acid concentration is 100 mg / L to 200 mg / L. The acetic acid concentration can be returned to the above appropriate range by the above replacement operation.

[0294] (Acetic acid concentration contained in monocyclic aromatic hydrocarbons)

[0295] In the method for producing cycloolefins according to the second embodiment, it is preferred that the concentration of acetic acid contained in the monocyclic aromatic hydrocarbons be 1×10 -4 The range is ~5mg / L.

[0296] It should be noted that the monocyclic aromatic hydrocarbons in this case include both the monocyclic aromatic hydrocarbons used initially in the production process and the monocyclic aromatic hydrocarbons recycled.

[0297] Acetic acid in monocyclic aromatic hydrocarbons can be reduced by suppressing its generation in the extraction and separation process of recycled monocyclic aromatic hydrocarbons, removing or reducing the generated acetic acid as an impurity of monocyclic aromatic hydrocarbons, separation and purification, reduction and removal using an adsorbent, water washing treatment of monocyclic aromatic hydrocarbons, etc., and can be controlled to the above-mentioned numerical range.

[0298] By limiting the acetic acid concentration in the monocyclic aromatic hydrocarbons to 5 mg / L or less, the acetic acid concentration in the aqueous zinc sulfate solution in the presence of a ruthenium catalyst can be prevented from gradually increasing, and the acetic acid concentration in the aqueous zinc sulfate solution can be set to 100 mg / L or less, thereby preventing the performance of the partial hydrogenation reaction from being reduced.

[0299] That is, the acetic acid concentration in the monocyclic aromatic hydrocarbons is preferably 5 mg / L or less, more preferably 3 mg / L or less, and even more preferably 1.5 mg / L or less.

[0300] On the other hand, the concentration of acetic acid in the monocyclic aromatic hydrocarbons is reduced to less than 1×10 -4 mg / L, the load for reducing and removing acetic acid, the operation load for low concentration management, and the load for analytical management become large, so it is preferable to set the lower limit value to 1×10 -4 mg / L or more, by setting it to 1×10 -3 mg / L or above, the operating load and analysis load of separation and purification can be further reduced.

[0301] The acetic acid concentration in the monocyclic aromatic hydrocarbons can be measured by the method described in the Examples below.

[0302] (Ratio of acetic acid mass to ruthenium catalyst mass)

[0303] In the method for producing cycloolefins according to the second embodiment, a ruthenium catalyst is used as a catalyst for producing cycloolefins by partial hydrogenation of monocyclic aromatic hydrocarbons.

[0304] In the second embodiment, the ratio of the mass of acetic acid to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution is preferably set to 3×10 -9 ~2.5×10 -3 More preferably, it is 1×10 -8 ~2×10 -3 times, more preferably 1×10 -7 ~1.5×10 -3 times, and more preferably 1×10 -6 ~5×10 -4 times.

[0305] The ratio of the mass of acetic acid to the mass of the ruthenium catalyst can be calculated by the method described in Examples below.

[0306] The partial hydrogenation reaction of monocyclic aromatic hydrocarbons is carried out by adsorbing monocyclic aromatic hydrocarbons and hydrogen in a zinc sulfate aqueous solution on a ruthenium catalyst to form cycloolefins, which are then separated from the catalyst. In such a reaction, if acetic acid enters the zinc sulfate aqueous solution, the adsorption and desorption characteristics of the ruthenium catalyst are inhibited, and the reactivity gradually decreases.

[0307] Therefore, the acetic acid concentration in the zinc sulfate aqueous solution is preferably within a range that does not affect the reaction inhibition of the ruthenium catalyst, and the acetic acid concentration in the zinc sulfate aqueous solution serving as the reaction field, the acetic acid concentration contained in the recycled monocyclic aromatic hydrocarbons, and the ratio of the acetic acid mass to the ruthenium catalyst mass need to be managed.

[0308] It should be noted that when the acetic acid concentration in the zinc sulfate aqueous solution and the ratio of the mass of acetic acid to the mass of the ruthenium catalyst are above the preferred range, the reactivity of the ruthenium catalyst can be restored by replacing the zinc sulfate aqueous solution in the reaction field to return to the preferred range.

[0309] (Preferred embodiment of the method for producing cycloolefin in the second embodiment)

[0310] The method for producing cycloolefin in the second embodiment comprises:

[0311] A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution;

[0312] After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound;

[0313] A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and

[0314] The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the above-mentioned reaction step.

[0315] In the reaction step, the ratio of the mass of acetic acid in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is preferably controlled to be 1×10 -6 ~5×10 -4 times.

[0316] Thus, the catalyst activity of the partial hydrogenation reaction and the high selectivity of cycloolefins can be maintained, and the catalyst activity and the high selectivity of cycloolefins can be maintained even after the catalyst is regenerated. By stabilizing the catalyst activity, the number of complicated operations such as replacing the catalyst and adding unused catalysts can be reduced when producing cycloolefins for a long time, the selectivity of cycloolefins can be effectively suppressed, and cycloolefins can be produced efficiently and stably for a long time.

[0317] The amount of water contacted in the water washing step is preferably 0.05 to 0.8 times by volume, more preferably 0.08 to 0.6 times by volume, based on the monocyclic aromatic hydrocarbon.

[0318] The ratio of the mass of acetic acid to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution can be controlled within the above numerical range by replacing the zinc sulfate aqueous solution in the reaction field.

[0319] [Regeneration of ruthenium catalyst]

[0320] In the methods for producing cycloolefins according to the first and second embodiments, part or all of the ruthenium catalyst may be regenerated and reused.

[0321] By regenerating a part or all of the ruthenium catalyst and reusing it, it is possible to suppress a decrease in the activity of the catalyst and the selectivity for cycloolefins.

[0322] By regenerating part or all of the ruthenium catalyst, it is possible to remove substances that become poisoning components on the catalyst reaction surface, and it is possible to regenerate the activity of the catalyst that has changed after use.

[0323] It should be noted that, from the viewpoint of improving the regeneration efficiency and extending the catalyst life, the ruthenium catalyst to be regenerated is particularly preferably a ruthenium catalyst containing zirconium oxide.

[0324] In the first and second embodiments of the method for producing cycloolefins, the substances whose amount in the aqueous zinc sulfate solution needs to be controlled include nitrogen-containing components, particularly dimethylamine, and acetic acid. These are believed to be involved in the production of substances that reduce the reaction performance and may poison and deteriorate the catalytic reaction surface.

[0325] In particular, when the partial hydrogenation reaction of monocyclic aromatic hydrocarbons is continuously carried out, the substance that poisons or deteriorates the ruthenium catalyst present in the zinc sulfate aqueous solution tends to be firmly bound to the surface of the ruthenium catalyst over time and is difficult to be separated and removed. In addition, the aggregation of the ruthenium catalyst component is also gradually advanced. If the substance that poisons or deteriorates is present, it tends to be absorbed into the aggregation of the ruthenium catalyst component and become increasingly difficult to be separated and removed from the catalyst surface.

[0326] By regenerating the catalyst, the substances that are firmly bound to the catalyst surface and cause the catalyst poisoning or deterioration as mentioned above can be detached and removed, the aggregation of the catalyst can be suppressed, the aggregated catalyst components can be redispersed, and the substances that cause the catalyst poisoning or deterioration can be separated from the catalyst surface, thereby suppressing the reduction in the activity of the catalyst and the selectivity of cycloolefins.

[0327] The amount of the regenerated ruthenium catalyst may be all or part thereof, and may be appropriately selected according to the production line. In addition, the catalyst regeneration method may be implemented intermittently or continuously.

[0328] Regenerating the entire catalyst has the following advantages.

[0329] That is, when the reaction is carried out in a batch mode, it is preferable to regenerate the entire amount and to understand in advance in a basic experiment the relationship between the regeneration conditions and the activity and cycloolefin selectivity of the catalyst after regeneration, thereby making it easy to control the activity and the aforementioned selectivity of the catalyst after regeneration.

[0330] On the other hand, regenerating a part of the catalyst has the following advantages.

[0331] When a part of the catalyst is regenerated, the regenerated catalyst and the unregenerated catalyst are mixed and reused. With regard to the activity of the catalyst and the cycloolefin selectivity, it is preferred that the optimum amount of hydrogen and metal ions are adsorbed on ruthenium. By mixing the catalyst that has been subjected to a treatment such as regeneration, which is accompanied by a rapid change on ruthenium, with the catalyst that has not been subjected to regeneration, a state in which hydrogen and metal ions are adsorbed on ruthenium can be formed relatively gently, which is preferred from the viewpoint of being able to maintain a good balance between the activity and the cycloolefin selectivity during long-term catalyst use.

[0332] It should be noted that the aforementioned part refers to, in the case of manufacturing cycloolefins by intermittent reaction, preferably 5% to 80% by mass of the catalyst used in the reaction. More preferably 10% to 60% by mass. In addition, as the amount of catalyst regenerated in a continuous reaction, it actually varies according to the degree of reduction in catalyst performance per unit time. For example, preferably 5% to 80% by mass of the entire catalyst is regenerated within 24 hours. More preferably 10% to 60% by mass.

[0333] The method of taking out a part or all of the catalyst from the continuous reaction, regenerating it, and returning it to the reactor for the partial hydrogenation reaction is not particularly limited. For example, in the case of the continuous reaction, there is a method of temporarily stopping the continuous reaction and removing the oil phase, regenerating the entire liquid phase containing the catalyst, and then restarting the partial hydrogenation reaction. Alternatively, the continuous reaction may be not stopped, while the liquid phase containing the catalyst is partially taken out and regenerated, and then refilled into the reactor for the partial hydrogenation reaction.

[0334] As an apparatus and operation method for continuously taking out a liquid phase containing a catalyst and performing regeneration treatment and refilling, there can be cited the method disclosed in Japanese Patent No. 4397468 and an apparatus including a partial hydrogenation reactor, a jacketed cooler, and a jacketed active activator.

[0335] As a method for regenerating the ruthenium catalyst, a known method can be used.

[0336] For example, there can be mentioned: (1) a method of contacting the catalyst with oxygen in a liquid phase; and (2) a method of maintaining the catalyst at a hydrogen partial pressure lower than that in the hydrogenation reaction and at a temperature not lower than 50° C. lower than that in the partial hydrogenation reaction.

[0337] In the first method (1) of contacting the catalyst with oxygen in a liquid phase, the liquid phase can be a state in which the ruthenium catalyst is dispersed in a slurry in a suitable liquid. The amount of the liquid can be small, but at least the surface of the catalyst needs to be covered with the liquid. The liquid used can be any liquid that does not adversely affect the ruthenium catalyst or its carrier, and is preferably water.

[0338] As the oxygen source when the catalyst is contacted with oxygen in the liquid phase, a gas containing molecular oxygen such as oxygen gas or air, or a compound that generates nascent oxygen such as hydrogen peroxide can be used. Oxygen gas can be used directly, but it is preferred to use it diluted with an appropriate inert gas because it is easy to operate.

[0339] The oxygen concentration of the liquid phase is usually 1×10 -7 ~1NmL / mL, preferably 1×10 -5 When the oxygen concentration is within this range, the treatment time can be relatively short, and irreversible changes caused by rapid oxidation of ruthenium on the catalyst surface can be prevented.

[0340] Oxygen can be directly supplied to the liquid phase in the slurry state. The most preferred method for supplying oxygen is to disperse the ruthenium catalyst in water and supply a gas containing oxygen to the dispersion. This method is simple to operate and is therefore preferred.

[0341] The operation of recovering the activity of the ruthenium catalyst can be carried out under reduced pressure, normal pressure or increased pressure.

[0342] The liquid phase may be pressurized in order to increase the oxygen concentration.

[0343] The operating temperature for contacting the catalyst with oxygen can be set in the range of 0 to 300°C, preferably 30 to 200°C, and more preferably 50 to 150°C.

[0344] The operation time may be appropriately determined depending on the degree of activity reduction of the catalyst to be treated and the target degree of activity recovery, and is usually several minutes to several days.

[0345] The second method (2) of regenerating the catalyst by maintaining it at a hydrogen partial pressure lower than that in the hydrogenation reaction and at a temperature not lower than 50°C lower than that in the partial hydrogenation reaction can be carried out in either the gas phase or the liquid phase.

[0346] The hydrogen partial pressure may be lower than the hydrogen partial pressure in the partial hydrogenation reaction, but if the difference between the two hydrogen partial pressures is small, a long time may be required for activity recovery. Therefore, it is preferably set to a pressure of 1 / 2 or less of the hydrogen partial pressure in the partial hydrogenation reaction, and more preferably set to a pressure of zero or close to zero.

[0347] The operating temperature of the catalyst is maintained at a temperature not lower than 50° C. lower than the temperature during the partial hydrogenation reaction, preferably not lower than 40° C. lower, and more preferably not lower than 30° C. lower. The operating temperature may be higher than the temperature during the partial hydrogenation reaction, but if it is too high, irreversible changes may occur in the active sites of the catalyst, so it is preferred to select an upper limit of the operating temperature that is suitable for the characteristics of the catalyst.

[0348] Regarding the fine particles of the ruthenium catalyst used in the first and second embodiments, from the viewpoint of preventing physical denaturation of the catalyst, the catalyst is preferably maintained at a temperature not exceeding 250°C, more preferably not exceeding 200°C. On the other hand, when the temperature is lower than 50°C lower than the temperature during the hydrogenation reaction, a significantly long treatment time is sometimes required to restore the activity. The retention time can be appropriately selected according to the degree of activity reduction of the catalyst to be treated and the degree of activity recovery as the target, and is generally a few minutes to a few days.

[0349] In the case of combining the above-mentioned two methods for regenerating the ruthenium catalyst (1) and (2), either method may be implemented first. Preferably, the method of contacting the catalyst with oxygen in the liquid phase of the above-mentioned (1) is first performed. In order to perform the operation of the activity recovery, it is preferred to separate and remove organic matter coexisting with the catalyst from the partial hydrogenation reaction from the ruthenium catalyst in advance. Here, the organic matter coexisting with the catalyst refers to monocyclic aromatic hydrocarbons, reaction products, by-products or impurities of the raw material.

[0350] The ruthenium catalyst whose activity has been restored is appropriately washed and dried to be in a preferred form and then reused in the partial hydrogenation reaction of monocyclic aromatic hydrocarbons.

[0351] By removing part or all of the ruthenium catalyst and only performing a regeneration treatment, the cycloolefin activity and selectivity of the catalyst in which performance reduction is observed can be restored to some extent, but sometimes not necessarily fully. By maintaining the concentration of the nitrogen-containing component dissolved in the zinc sulfate aqueous solution, especially dimethylamine, and the concentration of acetic acid within an appropriate range on the basis of the regeneration treatment of the ruthenium catalyst, the activity of the ruthenium catalyst and the reduction of the cycloolefin selectivity can be effectively suppressed. In addition, since the regeneration performance of the ruthenium catalyst can be improved, high catalytic activity and cycloolefin selectivity can be maintained after the regeneration treatment.

[0352] Regarding the mechanism of suppressing catalyst degradation by maintaining the concentration of nitrogen-containing components, especially dimethylamine and acetic acid, within an appropriate range on the basis of the regeneration treatment of the ruthenium catalyst, it is believed that if the concentration of each component exceeds the appropriate range and becomes high, it is difficult to separate and remove the nitrogen-containing components and acetic acid from the catalyst surface during the regeneration treatment of the catalyst. In addition, it is also believed that the poisoning substances temporarily separated from the catalyst surface by the regeneration treatment of the catalyst will be adsorbed on the catalyst surface again, and the reaction performance will be reduced again.

[0353] That is, in terms of removing part or all of the ruthenium catalyst for regeneration, the nitrogen-containing component dissolved in the zinc sulfate aqueous solution is preferably in the range of 0.5 to 3000 mg / L, the dimethylamine is preferably in the range of 1.7 to 9900 mg / L, and the acetic acid concentration is preferably 1×10 -3 The range is from 100mg / L to 200mg / L.

[0354] By maintaining the concentration of each component within an appropriate range, poisoning substances adsorbed on the ruthenium catalyst and substances that cause it to deteriorate can be easily detached and removed from the surface of the aforementioned catalyst, thereby achieving the effect of suppressing not only short-term but also long-term reduction in catalyst activity and selectivity.

[0355] [Zinc concentration in ruthenium catalyst containing zirconium oxide]

[0356] In the first and second embodiments, the concentration of zinc in the ruthenium catalyst is preferably maintained in the range of 0.5 to 3.5 mass %, more preferably 0.5 to 2.5 mass %, and even more preferably 0.5 to 1.8 mass %.

[0357] The zinc concentration in the ruthenium catalyst can be measured by the method described in the examples below.

[0358] When the zinc concentration is within the above numerical range, a zirconium oxide-containing ruthenium catalyst is particularly preferred from the viewpoint of improving the stability of the zinc concentration during the reaction and stabilizing the reactivity of the catalyst.

[0359] The nitrogen-containing components, dimethylacetamide and dimethylamine that enter the reaction field of the zinc sulfate aqueous solution are alkaline, and when they enter the zinc sulfate aqueous solution, they will cause zinc salting out. The salted zinc will cover the reaction sites of the ruthenium catalyst and reduce the reaction activity.

[0360] As a method for removing zinc that is the cause of the decrease in catalytic activity, sulfuric acid is added to a zinc sulfate aqueous solution to dissolve the salted zinc, thereby suppressing the decrease in activity. In addition, by regenerating the catalyst, the zinc adsorbed on the ruthenium surface can also be reduced, thereby suppressing the decrease in catalytic activity.

[0361] On the other hand, adding sulfuric acid to the aqueous zinc sulfate solution and regenerating the catalyst also serves to reduce the amount of zinc in the catalyst, which has the effect of improving the selectivity.

[0362] From the above viewpoints, in the first and second embodiments, the concentration of zinc in the ruthenium catalyst solid component is preferably within the above range.

[0363] If the zinc concentration is less than 0.5 mass %, the selectivity of cycloolefins decreases. If it exceeds 3.5 mass %, the activity decreases, and the reaction inhibition effect due to the excessively high zinc concentration is manifested, and the selectivity of cycloolefins tends to decrease.

[0364] That is, from the viewpoint of stably maintaining the activity of the catalyst and the selectivity of cycloolefins, in the reaction field where the nitrogen-containing component, dimethylacetamide and dimethylamine enter the aqueous zinc sulfate solution, it is preferred to appropriately manage the zinc concentration contained in the ruthenium catalyst when sulfuric acid is added and the catalyst is regenerated.

[0365] Example

[0366] The present embodiment will be described in further detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0367] The evaluation methods of various physical properties are as follows.

[0368] [First embodiment]

[0369] (Nitrogen concentration in zinc sulfate aqueous solution, nitrogen concentration in monocyclic aromatic hydrocarbons, ratio of nitrogen mass to mass of zirconium oxide-containing ruthenium catalyst)

[0370] The nitrogen concentrations in the aqueous zinc sulfate solution and the monocyclic aromatic hydrocarbons were measured by chemiluminescence using a TS-2100V total nitrogen automatic analyzer manufactured by Nitto Seiko Analytical Science Co., Ltd. (formerly Mitsubishi Chemical Analytical Science Co., Ltd.).

[0371] The ratio of the mass of nitrogen to the mass of the ruthenium catalyst containing zirconium oxide is obtained as the ratio of the mass concentration of total nitrogen in the aqueous zinc sulfate solution to the mass concentration of the total solid catalyst (total nitrogen concentration in the aqueous zinc sulfate solution / mass concentration of the total solid catalyst in the aqueous zinc sulfate solution). Specifically, the reaction solution, the aqueous zinc sulfate solution, and the ruthenium catalyst containing zirconium oxide are taken out from the reaction system in a completely mixed state, and the total nitrogen concentration in the aqueous zinc sulfate solution is measured using the above-mentioned analysis device. The mass concentration of the ruthenium catalyst containing zirconium oxide is filtered and dried and obtained as the solid content concentration in the aqueous zinc sulfate solution, thereby calculating the ratio of the mass of nitrogen to the mass of the ruthenium catalyst containing zirconium oxide.

[0372] (Dimethylamine concentration in aqueous zinc sulfate solution, dimethylamine concentration in monocyclic aromatic hydrocarbons, ratio of the mass of dimethylamine to the mass of the zirconium oxide-containing ruthenium catalyst)

[0373] The concentration of dimethylamine in the aqueous zinc sulfate solution was measured using an IC-2010 ion chromatograph manufactured by Tosoh Techno-System.

[0374] The concentration of dimethylamine in the monocyclic aromatic hydrocarbons was measured using a gas chromatograph (GC-2014) equipped with a FID detector manufactured by Shimadzu Corporation.

[0375] In addition, the ratio of the mass of dimethylamine to the mass of the zirconium oxide-containing ruthenium catalyst is calculated in the same manner as the method for calculating the nitrogen concentration relative to the catalyst, based on the measured concentration of dimethylamine in the zinc sulfate aqueous solution taken out from the reaction system and the solid content concentration of the zirconium oxide-containing ruthenium catalyst.

[0376] (Zinc concentration in ruthenium catalyst containing zirconium oxide)

[0377] The zinc concentration in the zirconium oxide-containing ruthenium catalyst was measured using a ZSX Primus II fluorescence analyzer manufactured by Rigaku Corporation.

[0378] In the analysis of a small amount of sample, the ruthenium catalyst containing zirconium oxide is dissolved using hydrochloric acid for measuring harmful metals, and the concentration of zinc dissolved in the solution is measured using an ICP device SPS3520UV-DD manufactured by Hitachi High-Technologies.

[0379] (Average crystallite diameter of ruthenium)

[0380] The average crystallite diameter of ruthenium was determined by the Scherrer equation based on the expansion of the diffraction peak of ruthenium metal at a diffraction angle (2θ) of 44° obtained by an XRD-6100 X-ray diffractometer manufactured by Shimadzu Corporation.

[0381] (Benzene conversion and cyclohexene selectivity)

[0382] A catalyst and hydrogen were added to a 1L autoclave reactor, the temperature and hydrogen pressure were set, and a predetermined amount of benzene as a monocyclic aromatic hydrocarbon was added all at once. The reaction was evaluated in a batch manner at the predetermined reaction temperature and hydrogen pressure.

[0383] The intermittent reaction is also called batch reaction, which is a method in which an aqueous zinc sulfate solution containing a catalyst is put into an autoclave, and the raw material benzene is added once at the beginning of the reaction based on the setting of specified temperature, pressure and time, and the entire amount is recovered after the reaction is completed.

[0384] After benzene was added, a portion of the reaction liquid was taken out and analyzed using a gas chromatograph with an FID detector (GC-2014 manufactured by Shimadzu Corporation). Based on the experimental concentration analysis values, the reaction conversion rate and selectivity over time were calculated using the following calculation formulas (1) and (2), and the selectivity of 50% conversion was calculated by plotting the analysis data.

[0385] In addition, on the other hand, a reaction evaluation based on a continuous flow method was performed in which a catalyst was added to a 4L continuous tank reactor (CSTR), benzene and hydrogen were continuously added, and the reaction process was observed. The reaction based on the continuous flow method is a method in which the raw material benzene is continuously added to the reactor and the reaction product is continuously taken out from the reactor, and the reaction can be continuously carried out under certain conditions for a long time. In addition to temperature, pressure, and catalyst amount, the benzene conversion rate can also be adjusted by controlling the benzene flow rate, and the selectivity of cyclohexene at this time can be obtained.

[0386] In this example, the benzene conversion rate was set to approximately 50%. In the same manner as in the intermittent method, analysis was performed using a gas chromatograph with an FID detector (GC-2014 manufactured by Shimadzu Corporation). Based on the experimental concentration analysis values, the benzene conversion rate and the selectivity for cyclohexene were calculated using the following calculation formulas (1) and (2).

[0387] It should be noted that the reaction performance in the continuous tank reactor is theoretically lower than the reaction selectivity obtained with the batch reactor, but because the production efficiency is high, industrial production is carried out in the continuous tank reaction form. Because the respective evaluation values ​​are different, the embodiments of the batch evaluation are summarized in Table 1, and the embodiments based on the continuous circulation mode are summarized in Table 2.

[0388]

[0389] [Example 1-1]

[0390] (Preparation of Catalyst)

[0391] In 500mL of distilled water heated to 80°C, 20g of ruthenium chloride hydrate (containing 40% by mass of ruthenium) and 8g of zinc chloride were added and dissolved while stirring. 100mL of 5N sodium hydroxide aqueous solution was added thereto, and stirring was continued for 2 hours at 80°C to obtain a solid of black precipitation. The liquid containing the above-mentioned solid was cooled and filtered, and the recovered solid was put into 500mL of 1N sodium hydroxide aqueous solution, and the alkali cleaning and filtering operations were repeated 3 times. Thereafter, 500mL of distilled water was further used to repeatedly wash and filter 5 times. Next, the above-mentioned solid was added to a measuring cylinder prepared in advance with an aqueous zinc sulfate solution, and 500mL of liquid adjusted to a zinc sulfate concentration of 0.62mol / L was prepared and put into a 1L autoclave. 45g of zirconium oxide powder was further added, a 1L autoclave was set up, and the temperature and pressure were increased while stirring, and a reduction treatment was performed for 5 hours with hydrogen 5Mpa at a temperature of 150°C.

[0392] Then, the 1L autoclave was cooled, and the liquid containing the reduced ruthenium catalyst containing zirconium oxide was taken out into a beaker, and after standing, the supernatant was removed by decantation. Distilled water was further added, stirred, and allowed to stand, and the decantation and supernatant exchange operations were repeated 5 times to obtain 52.8 g of the wet ruthenium catalyst containing zirconium oxide in terms of dry mass.

[0393] The average crystallite diameter of ruthenium in the zirconium oxide-containing ruthenium catalyst was 4.6 nm.

[0394] (Partial Hydrogenation of Benzene)

[0395] 280 mL of a liquid containing 12 g of the zirconium oxide-containing ruthenium catalyst in terms of dry mass and adjusted to a dimethylamine concentration of 45 mg / L and a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0396] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0397] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0398] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0399] In addition, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the mass of nitrogen to the mass of the zirconium oxide-containing ruthenium catalyst fed, and the concentration of zinc contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0400] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0401] [Example 1-2]

[0402] 280 mL of a liquid containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 1-1 above in terms of dry mass and 1.15 g of 40% by mass dimethylamine and adjusted to a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0403] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0404] Next, the autoclave was cooled, depressurized, and opened, 0.52 g of 96 mass % sulfuric acid was added, hydrogen was again pressed into the mixture, and the mixture was stirred at 145° C. and a total pressure of 5 MPa for 1 hour. After the pressure of the autoclave was temporarily reduced to 3 MPa, 140 mL of benzene was pressed into the mixture together with hydrogen, and the mixture was reacted while being stirred at a high speed at a total pressure of 5 MPa.

[0405] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0406] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass to the catalyst mass charged, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0407] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0408] [Examples 1-3]

[0409] 280 mL of a liquid containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 1-1 above in terms of dry mass and 3.03 g of 40 mass % dimethylamine and adjusted to a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0410] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0411] Next, the autoclave was cooled, depressurized, and opened, and 1.5 g of 96 mass % sulfuric acid was added, and hydrogen was again pressed into the autoclave. After stirring at 145° C. and a total pressure of 5 MPa for 1 hour, the pressure of the autoclave was temporarily reduced to 3 MPa, and 140 mL of benzene was pressed into the autoclave together with hydrogen, and the mixture was reacted while stirring at a high speed at a total pressure of 5 MPa.

[0412] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0413] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass to the catalyst mass charged, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0414] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0415] [Examples 1-4]

[0416] 280 mL of a liquid containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 1-1 above in terms of dry mass and 6.08 g of 40% by mass dimethylamine and adjusted to a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0417] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0418] Next, the autoclave was cooled, depressurized, and opened, and 2.81 g of 96 mass % sulfuric acid was added, and hydrogen was again pressed into the autoclave. After stirring at 145° C. and a total pressure of 5 MPa for 1 hour, the pressure of the autoclave was temporarily reduced to 3 MPa, and 140 mL of benzene was pressed into the autoclave together with hydrogen, and the reaction was carried out while stirring at a high speed at a total pressure of 5 MPa.

[0419] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0420] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass to the catalyst mass charged, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0421] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0422] [Comparative Example 1-1]

[0423] 53.1 g of the zirconium oxide-containing ruthenium catalyst prepared in the same manner as in Example 1-1 was recovered in terms of dry mass.

[0424] 280 mL of a liquid containing 12 g of the zirconium oxide-containing ruthenium catalyst and 19.56 g of 40 mass % dimethylamine and adjusted to a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0425] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0426] Next, the autoclave was cooled, depressurized, and opened, and 8.73 g of 96 mass % sulfuric acid was added, and hydrogen was again pressed into the mixture. After stirring at 145° C. and a total pressure of 5 MPa for 1 hour, the pressure of the autoclave was temporarily reduced to 3 MPa, and 140 mL of benzene was pressed into the mixture together with hydrogen, and the mixture was reacted while stirring at a high speed at a total pressure of 5 MPa.

[0427] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0428] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass to the catalyst mass charged, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0429] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0430] [Comparative Example 1-2]

[0431] The zirconium oxide-containing ruthenium catalyst and the reaction liquid reacted in the above-mentioned Examples 1-4 are taken out from the autoclave, and the aromatic hydrocarbon components in the reaction liquid are removed. Then, nitrogen gas is introduced into the catalyst slurry to treat it to a level where the odor of aromatic hydrocarbons is no longer detectable.

[0432] 240 mL of the catalyst slurry was collected in a completely mixed state, 10.67 g of 40% by mass dimethylamine was added, and the mixture was placed in a 1 L autoclave.

[0433] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0434] Next, the autoclave was cooled, depressurized, and opened, 4.71 g of 96 mass % sulfuric acid was added, hydrogen was again pressed into the mixture, and the mixture was stirred at 145° C. and a total pressure of 5 MPa for 1 hour. After the pressure of the autoclave was temporarily reduced to 3 MPa, 120 mL of benzene was pressed into the mixture together with hydrogen, and the mixture was reacted while being stirred at a high speed at a total pressure of 5 MPa.

[0435] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0436] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0437] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0438] [Comparative Examples 1-3]

[0439] The zirconium oxide-containing ruthenium catalyst and the reaction liquid in the above-mentioned Comparative Example 1-2 were taken out from the autoclave, and the aromatic hydrocarbon components in the reaction liquid were removed. Furthermore, nitrogen gas was introduced into the catalyst slurry to treat it to a level where the odor of aromatic hydrocarbons was no longer detectable.

[0440] 220 mL of the catalyst slurry was collected in a completely mixed state, 0.061 g of 96 mass % sulfuric acid was added, and the mixture was placed in a 1 L autoclave.

[0441] Hydrogen was again injected, and the mixture was stirred at 145°C and a total pressure of 5 MPa for 1 hour. The pressure in the autoclave was temporarily reduced to 3 MPa, and 110 mL of benzene was injected together with hydrogen, and the mixture was reacted at a total pressure of 5 MPa while being stirred at high speed.

[0442] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0443] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0444] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0445] [Examples 1-5]

[0446] The zirconium oxide-containing ruthenium catalyst and the reaction liquid in the above-mentioned Comparative Example 1-1 were taken out from the autoclave, and the aromatic hydrocarbon components in the reaction liquid were removed. Furthermore, nitrogen gas was passed through the catalyst slurry to treat it to a level where the odor of aromatic hydrocarbons was no longer detectable.

[0447] 240 mL of the catalyst slurry was taken in a completely mixed state, and after standing to allow the catalyst solid component to settle, 140 mL of the supernatant was removed, and 0.62 mol / L zinc sulfate aqueous solution was added again to make the volume 280 mL.

[0448] Next, the catalyst slurry was stirred for 5 minutes, allowed to stand to allow the catalyst solid component to settle, 180 mL of the supernatant was removed, and 0.62 mol / L aqueous zinc sulfate solution was added to adjust the volume to 280 mL. This operation was repeated twice.

[0449] Then, 280 mL of the treated catalyst slurry was put into a 1 L autoclave, and the interior of the autoclave was replaced with hydrogen while stirring. After the temperature was raised to 145°C, hydrogen was further pressed in and maintained at a total pressure of 5 MPa for 22 hours to pretreat the catalyst.

[0450] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0451] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0452] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the nitrogen concentration in the aqueous zinc sulfate solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0453] The respective analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 1 below.

[0454] [Table 1]

[0455]

[0456] [Examples 1-6]

[0457] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 1-1 and having a zinc sulfate concentration of 0.62 mol / L was added to a continuous tank reactor.

[0458] This continuous tank type reactor has an oil-water separation tank as an auxiliary tank, and a Teflon (registered trademark) coating is applied to the inner surface.

[0459] Next, benzene containing 0.1 mg / L of dimethylamine was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0460] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0461] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0462] 22 hours after the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0463] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0464] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0465] [Examples 1-7]

[0466] The reaction of Example 1-6 was continued. After 116 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were obtained based on the results of gas chromatography analysis of the composition of the liquid phase. As a result, the reaction results were 45.7% benzene conversion rate and 78.8% cyclohexene selectivity.

[0467] Since the benzene conversion rate was low relative to the reaction result of the reaction time of 22 hours, the benzene supply rate was reduced based on a benzene conversion rate of 50%, and after ensuring a stabilization time of 2 hours, the reaction liquid was collected again to determine the reaction result.

[0468] In addition, the catalyst slurry was collected and the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration in the zirconium oxide-containing ruthenium catalyst were measured.

[0469] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0470] [Examples 1-8]

[0471] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 1-1 and adjusted to a zinc sulfate concentration of 0.62 mol / L was added to a continuous tank reactor.

[0472] Next, benzene containing 10 mg / L of dimethylamine was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0473] 20 hours after the start of the reaction, 0.3 g of 96 mass % sulfuric acid was added to the reactor through the supply line of make-up water in the reaction system. After 22 hours, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were calculated based on the results of gas chromatography analysis of the composition of the liquid phase.

[0474] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0475] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0476] [Examples 1-9]

[0477] The reaction of the aforementioned Example 1-8 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the aforementioned Example 1-8, was added to the continuous tank reactor.

[0478] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0479] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 70° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0480] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0481] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0482] Note that 0.41 g of 96 mass % sulfuric acid was added to the catalyst slurry subjected to the activity recovery operation and the mixture was returned to the reactor.

[0483] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0484] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0485] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0486] [Examples 1-10]

[0487] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 1-1 and adjusted to a zinc sulfate concentration of 0.62 mol / L was added to a continuous tank reactor.

[0488] Next, benzene containing 50 mg / L of dimethylamine was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0489] 20 hours after the start of the reaction, 1.5 g of 96% by mass sulfuric acid was added to the reactor through the water supply line in the reaction system. 22 hours later, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were calculated based on the results of gas chromatography analysis of the composition of the liquid phase.

[0490] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0491] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0492] [Examples 1-11]

[0493] The reaction of the aforementioned Example 1-10 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the aforementioned Example 1-10, was added to the tank circulation reactor.

[0494] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0495] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 70° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0496] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0497] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0498] Note that 2.1 g of 96 mass % sulfuric acid was added to the catalyst slurry subjected to the activity recovery operation, and the mixture was returned to the reactor.

[0499] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene and the reaction selectivity were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0500] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0501] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0502] [Examples 1-12]

[0503] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 1-1 and adjusted to a zinc sulfate concentration of 0.62 mol / L was added to a continuous tank reactor.

[0504] Next, benzene containing 100 mg / L of dimethylamine was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0505] 20 hours after the start of the reaction, 3 g of 96 mass % sulfuric acid was added to the reactor through the feed water supply line in the reaction system. 22 hours later, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were calculated based on the results of gas chromatography analysis of the composition of the liquid phase.

[0506] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0507] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0508] [Examples 1-13]

[0509] The reaction of Example 1-12 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the above-mentioned Example 1-10, was added to the continuous tank reactor.

[0510] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0511] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 50° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0512] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0513] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0514] It should be noted that 4 g of 96 mass % sulfuric acid was added to the catalyst slurry subjected to the activity recovery operation and returned to the reactor.

[0515] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0516] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0517] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0518] [Comparative Examples 1-4]

[0519] The reaction of the above-mentioned Example 1-13 was continued, 400 mL of the catalyst slurry containing the reaction solution was taken out, and 400 mL of the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0520] Note that 3.26 g of 96 mass % sulfuric acid was added to the catalyst slurry subjected to the activity recovery operation, and the mixture was returned to the reactor.

[0521] After 310 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0522] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0523] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0524] [Comparative Examples 1-5]

[0525] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 1-1 and adjusted to a zinc sulfate concentration of 0.62 mol / L was added to a continuous tank reactor.

[0526] Next, benzene containing 200 mg / L of dimethylamine was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0527] 24 hours after the start of the reaction, 600 mL of catalyst slurry containing the reaction solution was taken out from the continuous tank reactor, and 400 mL of catalyst slurry containing zinc sulfate, which was the same as that initially charged in Example 1-1, was charged into the continuous tank reactor.

[0528] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0529] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 50° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0530] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0531] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0532] The operation of adding 8.1 g of 96 mass % sulfuric acid to the catalyst slurry subjected to the activity recovery operation and returning the mixture to the reactor was performed three times in total.

[0533] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0534] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0535] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0536] [Examples 1-14]

[0537] The reaction of Comparative Example 1-5 was continued, and 120 hours after the reaction was started, the reaction mixture was switched to benzene containing 0.1 mg / L dimethylamine. Furthermore, 400 mL of the catalyst slurry containing the reaction solution was taken out, and 400 mL of the slurry after the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0538] It should be noted that the catalyst slurry returned to the reactor after 120 hours of reaction start was treated until the slurry with nitrogen concentration mixed in the liquid taken out from the reactor was not detected. Specifically, the slurry was treated to the extent that the peculiar smell of the aromatic hydrocarbon component was not felt in the same way as in Comparative Example 1-5, and the nitrogen treatment containing oxygen was carried out. Then, decantation, supernatant removal and the operation of adding a newly made 0.62mol / L aqueous zinc sulfate solution were repeatedly performed at room temperature to reduce the nitrogen concentration. Then, 400mL of the treated catalyst slurry was heated to 140°C, the pressure in the system was maintained at 0.5MPa under a hydrogen atmosphere and stirred for 4 hours to ensure that the catalyst slurry with the recovery operation was used when the catalyst was put into use.

[0539] After 310 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0540] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the tank reactor, and the catalyst slurry was taken to measure the nitrogen concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0541] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 2 below.

[0542] [Table 2]

[0543]

[0544] [Second embodiment]

[0545] (Acetic acid concentration)

[0546] <Acetic acid concentration in zinc sulfate aqueous solution>

[0547] The acetic acid concentration in the aqueous zinc sulfate solution was measured using an IC-2010 ion chromatograph manufactured by Tosoh Techno-System.

[0548] When the acetic acid concentration is 1 mg / L or less, the acetic acid concentration is determined by subtracting the amount of acetic acid dissolved in the monocyclic aromatic hydrocarbons and the reaction solution and not remaining in the aqueous zinc sulfate solution from the amount of acetic acid introduced into the aqueous zinc sulfate solution.

[0549] Specifically, it is calculated by the following formula.

[0550] (Amount of acetic acid in the zinc sulfate aqueous solution) = (Amount of acetic acid entering the zinc sulfate aqueous solution) - (Amount of acetic acid taken out of the zinc sulfate aqueous solution)

[0551] In the above formula, (the amount of acetic acid introduced into the aqueous zinc sulfate solution) refers to the amount of acetic acid in monocyclic aromatic hydrocarbons such as benzene as a raw material.

[0552] In addition, (the amount of acetic acid taken out from the aqueous zinc sulfate solution) means the amount of acetic acid in the oil phase (monocyclic aromatic hydrocarbon reaction liquid) after the reaction.

[0553] <Concentration of acetic acid in monocyclic aromatic hydrocarbons and reaction solution of monocyclic aromatic hydrocarbons (oil phase after reaction)>

[0554] The monocyclic aromatic hydrocarbons (benzene) and the acetic acid concentration in the reaction solution of the monocyclic aromatic hydrocarbons were measured using a GC-2014 gas chromatograph manufactured by Shimadzu Corporation.

[0555] When the concentration of monocyclic aromatic hydrocarbons and acetic acid in the reaction solution was 0.5 ppm or less, water was added to the measurement sample to perform extraction and concentration, and the measurement sample was analyzed based on a calibration curve based on the distribution ratio.

[0556] (Ratio of the mass of acetic acid to the mass of the ruthenium catalyst containing zirconium oxide)

[0557] The ratio of the mass of acetic acid to the mass of the zirconium oxide-containing ruthenium catalyst was determined as the ratio of the acetic acid concentration (mg / L) in the aqueous zinc sulfate solution to the total solid catalyst concentration (mg / L) in the reaction solution.

[0558] Specifically, the reaction solution, the zinc sulfate aqueous solution, and the catalyst were taken out from the reaction system in a completely mixed state, left to stand for separation, and the acetic acid concentration in the zinc sulfate aqueous solution was measured using the above-mentioned analysis device. The catalyst was filtered and dried to obtain the solid content concentration in the zinc sulfate aqueous solution, thereby calculating the ratio of the mass of acetic acid to the mass of the catalyst.

[0559] (Zinc concentration in catalyst solid component)

[0560] The zinc concentration in the catalyst solid component was measured using a ZSX Primus II fluorescence analyzer manufactured by Rigaku Corporation.

[0561] When analyzing a small amount of sample, the catalyst solid component is dissolved using hydrochloric acid for measuring harmful metals, and the concentration of zinc dissolved in the solution is measured using an ICP device SPS3520UV-DD manufactured by Hitachi High-Technologies.

[0562] (Average crystallite diameter of ruthenium)

[0563] The average crystallite diameter of ruthenium was determined by the Scherrer equation based on the expansion of the diffraction peak of ruthenium metal at a diffraction angle (2θ) of 44° obtained by an XRD-6100 X-ray diffractometer manufactured by Shimadzu Corporation.

[0564] (Benzene conversion and cyclohexene selectivity)

[0565] A catalyst and hydrogen were added to a 1L autoclave reactor, the temperature and hydrogen pressure were set, and a predetermined amount of benzene as a monocyclic aromatic hydrocarbon was added all at once. The reaction was evaluated in a batch manner at the predetermined reaction temperature and hydrogen pressure.

[0566] The reaction based on the intermittent method is also called a batch reaction, in which an aqueous solution of zinc sulfate containing a catalyst is placed in an autoclave, and the raw material benzene is added once at the beginning of the reaction under the setting of a predetermined temperature, pressure, and time, and the entire amount is recovered after the reaction is completed. After the benzene is added, a portion of the reaction liquid is taken out, and analyzed by using a gas chromatograph with an FID detector (GC-2014 manufactured by Shimadzu Corporation). Based on the experimental concentration analysis value, the reaction conversion rate and selectivity over time are obtained by the calculation formulas (1) and (2) shown below, and the selectivity of 50% conversion rate is obtained by plotting the analysis data.

[0567] In addition, a reaction evaluation based on a flow method was performed in which a catalyst was added to a 4L tank reactor, benzene and hydrogen were continuously added, and the reaction process was observed. The reaction based on the flow method is a method in which the raw material benzene is continuously added to the reactor and the reaction product is continuously taken out from the reactor. The reaction can be continuously carried out under certain conditions for a long time. In addition to temperature, pressure, and catalyst amount, the benzene conversion rate can also be adjusted by controlling the benzene flow rate, and the selectivity of cyclohexene at this time can be obtained.

[0568] In this example, the benzene conversion rate was set to approximately 50%. In the same manner as in the intermittent method, analysis was performed using a gas chromatograph with an FID detector (GC-2014 manufactured by Shimadzu Corporation). Based on the experimental concentration analysis values, the benzene conversion rate and the selectivity for cyclohexene were calculated using the following calculation formulas (3) and (4).

[0569] It should be noted that the reaction performance in the continuous tank reactor is theoretically lower than the reaction selectivity obtained with the batch reactor, but because the production efficiency is high, industrial production is carried out in the continuous tank reaction form. Because the respective evaluation values ​​are different, the embodiments of the batch evaluation are summarized in Table 3, and the embodiments based on the continuous circulation mode are summarized in Table 4.

[0570]

[0571] [Example 2-1]

[0572] (Preparation of Catalyst)

[0573] In 500mL of distilled water heated to 80°C, 20g of ruthenium chloride hydrate (containing 40% ruthenium by mass) and 8g of zinc chloride were added and dissolved while stirring. 100mL of 5N sodium hydroxide aqueous solution was added thereto, and stirring was continued for 2 hours at 80°C to obtain a solid black precipitate. The liquid containing the solid was cooled and filtered, and the recovered solid was put into 500mL of 1N sodium hydroxide aqueous solution, and the alkali cleaning and filtering operations were repeated 3 times. Thereafter, 500mL of distilled water was further used for washing and filtering 5 times. Next, the solid was added to a measuring cylinder prepared in advance with an aqueous zinc sulfate solution, and 500mL of liquid adjusted to a zinc sulfate concentration of 0.62mol / L was prepared and put into a 1L autoclave. 45g of zirconium oxide powder was further added, a 1L autoclave was set up, and the temperature and pressure were increased while stirring, and a reduction treatment was carried out for 5 hours with hydrogen 5Mpa at a temperature of 150°C.

[0574] Then, the 1L autoclave was cooled, and the liquid containing the reduced ruthenium catalyst containing zirconium oxide was taken out into a beaker, and after standing, the supernatant was removed by decantation. Distilled water was further added, stirred, and allowed to stand, and the decantation and supernatant exchange operations were repeated 5 times, and 53.1g of the wet ruthenium catalyst containing zirconium oxide was taken in terms of dry mass.

[0575] The average crystallite diameter of ruthenium in the zirconium oxide-containing ruthenium catalyst was 5.1 nm.

[0576] (Partial Hydrogenation of Benzene)

[0577] 280 mL of a liquid containing a catalyst slurry containing 12 g of the zirconium oxide-containing ruthenium catalyst in terms of dry mass and adjusted to an acetic acid concentration of 5 mg / L and a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0578] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0579] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0580] During the reaction, the reaction liquid was taken out from the autoclave at regular intervals, and the composition of the liquid phase was analyzed by gas chromatography to determine the conversion rate of benzene and the selectivity of cyclohexene. In addition, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid to the mass of the zirconium oxide-containing ruthenium catalyst added, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0581] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0582] [Example 2-2]

[0583] 280 mL of a catalyst slurry containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 2-1 in terms of dry mass and adjusted to an acetic acid concentration of 80 mg / L and a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0584] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0585] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0586] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0587] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the aqueous zinc sulfate solution, the ratio of the mass of acetic acid to the mass of the charged catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0588] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0589] [Comparative Example 2-1]

[0590] 280 mL of a liquid containing a catalyst slurry containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 2-1 above in terms of dry mass and adjusted to an acetic acid concentration of 120 mg / L and a zinc sulfate concentration was placed in a 1 L autoclave.

[0591] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0592] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0593] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0594] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the aqueous zinc sulfate solution, the ratio of the mass of acetic acid to the mass of the charged catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0595] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0596] [Comparative Example 2-2]

[0597] 280 mL of a catalyst slurry containing 12 g of the zirconium oxide-containing ruthenium catalyst prepared in Example 2-1 in terms of dry mass and adjusted to an acetic acid concentration of 230 mg / L and a zinc sulfate concentration of 0.62 mol / L was placed in a 1 L autoclave.

[0598] The interior of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressurized and maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0599] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0600] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0601] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the aqueous zinc sulfate solution, the ratio of the mass of acetic acid to the mass of the charged catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0602] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0603] [Comparative Example 2-3]

[0604] The zirconium oxide-containing ruthenium catalyst and reaction liquid reacted in the aforementioned Example 2-2 were taken out from the autoclave, and the aromatic hydrocarbon components in the reaction liquid were removed. Furthermore, nitrogen gas was introduced into the catalyst slurry to treat it to a level where the odor of aromatic hydrocarbons was no longer detectable.

[0605] 240 mL of the above catalyst slurry was taken in a completely mixed state, and 10 mL of an aqueous solution prepared separately and adjusted to a concentration of 2.01 g / L of acetic acid and 0.62 mol / L of zinc sulfate was added, and the mixture was put into a 1 L autoclave. The inside of the autoclave was replaced with hydrogen while stirring, and after the temperature was raised to 145° C., hydrogen was further pressed into the autoclave, and the reaction was maintained at a total pressure of 5 MPa for 22 hours to perform pre-reaction treatment of the catalyst slurry.

[0606] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0607] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0608] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the aqueous zinc sulfate solution, the ratio of the mass of acetic acid to the mass of the charged catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0609] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0610] [Example 2-3]

[0611] The zirconium oxide-containing ruthenium catalyst and the reaction liquid in the above-mentioned Comparative Example 2-2 were taken out from the autoclave, and the aromatic hydrocarbon components in the reaction liquid were removed. Furthermore, nitrogen gas was passed through the catalyst slurry to treat it to a level where the odor of aromatic hydrocarbons was no longer detectable.

[0612] 240 mL of the catalyst slurry was taken in a completely mixed state, and after standing to allow the catalyst solid component to settle, 140 mL of the supernatant was removed, and 0.62 mol / L zinc sulfate aqueous solution was added again to make the volume 280 mL.

[0613] Next, the catalyst slurry was stirred for 5 minutes, allowed to stand to allow the catalyst solid component to settle, 180 mL of the supernatant was removed, and 0.62 mol / L aqueous zinc sulfate solution was added to adjust the volume to 280 mL. This operation was repeated twice.

[0614] Then, 280 mL of the treated catalyst slurry was put into a 1 L autoclave, and the interior of the autoclave was replaced with hydrogen while stirring. After the temperature was raised to 145°C, hydrogen was further pressed in and maintained at a total pressure of 5 MPa for 22 hours to pretreat the catalyst.

[0615] Next, the pressure in the autoclave was temporarily reduced to 3 MPa, and then 140 mL of benzene was injected together with hydrogen, and the reaction was allowed to proceed under high-speed stirring at a total pressure of 5 MPa.

[0616] The benzene conversion rate and the cyclohexene selectivity were determined from the results of taking out the reaction liquid over time and analyzing the composition of the liquid phase by gas chromatography.

[0617] Furthermore, the reactants and catalyst slurry after the reaction were taken out from the autoclave, and the acetic acid concentration in the aqueous zinc sulfate solution, the ratio of the mass of acetic acid to the mass of the charged catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst were measured.

[0618] The analytical values ​​and the selectivity of cyclohexene when the benzene conversion rate was 50% are shown in Table 3 below.

[0619] [Table 3]

[0620]

[0621] [Example 2-4]

[0622] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mol / L was charged into a continuous tank reactor.

[0623] This continuous tank type reactor has an oil-water separation tank as an auxiliary tank, and a Teflon (registered trademark) coating is applied to the inner surface.

[0624] Next, benzene, in which acetic acid was adjusted to 0.01 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0625] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0626] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0627] 22 hours after the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0628] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0629] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0630] [Example 2-5]

[0631] The reaction of the aforementioned Example 2-4 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the tank-type circulation reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the aforementioned Example 2-4, was added to the continuous tank-type reactor.

[0632] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0633] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 70° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0634] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0635] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0636] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0637] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0638] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0639] [Example 2-6]

[0640] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mol / L was charged into a continuous tank reactor.

[0641] Next, benzene, in which acetic acid was adjusted to 0.5 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0642] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0643] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0644] After 22 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the reaction selectivity was determined from the results of analyzing the composition of the liquid phase by gas chromatography.

[0645] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0646] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0647] [Example 2-7]

[0648] The reaction of the above-mentioned Example 2-6 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the above-mentioned Example 2-4, was added to the continuous tank reactor.

[0649] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0650] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 70° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0651] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0652] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0653] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0654] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0655] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0656] [Example 2-8]

[0657] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mol / L was charged into a continuous tank reactor.

[0658] Next, benzene, in which acetic acid was adjusted to 1 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0659] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0660] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0661] 22 hours after the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0662] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0663] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0664] [Example 2-9]

[0665] The reaction of the aforementioned Example 2-8 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the aforementioned Example 2-8, was added to the continuous tank reactor.

[0666] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0667] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 50° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0668] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0669] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0670] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0671] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0672] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0673] [Example 2-10]

[0674] 1200 mL of a liquid containing 50 g (in terms of dry mass) of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mol / L was charged into a continuous tank reactor.

[0675] Next, benzene, in which acetic acid was adjusted to 4 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0676] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0677] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0678] 20 hours after the start of the reaction, 0.55 g of 96 mass % sulfuric acid was added to the reactor through the water supply line in the reaction system. 22 hours later, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were calculated based on the results of gas chromatography analysis of the composition of the liquid phase.

[0679] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0680] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0681] [Comparative Example 2-4]

[0682] 1200 mL of a liquid containing 50 g, in terms of dry mass, of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mg / L was charged into a continuous tank reactor.

[0683] Next, benzene, in which acetic acid was adjusted to 6 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0684] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0685] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0686] 22 hours after the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0687] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0688] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0689] [Comparative Example 2-5]

[0690] The reaction of the comparative example 2-4 was continued. 24 hours after the start of the reaction, 600 mL of the catalyst slurry containing the reaction solution was taken out from the continuous tank reactor. On the other hand, 400 mL of the catalyst slurry containing zinc sulfate, which was the same as the material initially added in the above-mentioned Example 2-8, was added to the continuous tank reactor.

[0691] The aromatic hydrocarbon components were removed from the catalyst slurry containing the reaction solution, and nitrogen was then passed through the catalyst slurry to treat the slurry to such an extent that the odor of aromatic hydrocarbons could no longer be detected.

[0692] Next, the mixture was brought into contact with nitrogen gas containing 7% by volume of oxygen at 50° C. for 1 hour, and then replaced with nitrogen gas and further replaced with hydrogen gas.

[0693] Then, the temperature was raised to 140° C., and stirring was performed for 4 hours while the pressure in the system was maintained at 0.5 MPa in a hydrogen atmosphere, and a recovery operation of the catalyst activity was performed using the entire amount of the catalyst slurry.

[0694] While the reaction was continued, 400 mL of the catalyst slurry was taken out from the reactor as described above as catalyst slurry and the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0695] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0696] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0697] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0698] [Comparative Example 2-6]

[0699] 1200 mL of a liquid containing 50 g, in terms of dry mass, of a zirconium oxide-containing ruthenium catalyst prepared by the same method as in Example 2-1 and having a zinc sulfate concentration of 0.62 mg / L was charged into a continuous tank reactor.

[0700] Next, benzene, in which acetic acid was adjusted to 10 mg / L in advance, was supplied to the continuous tank reactor at 145° C. and 5 MPa under hydrogen pressure at a rate of 1.2 L / hr to continuously carry out a partial hydrogenation reaction of benzene.

[0701] At this time, water was supplied so that the composition of the aqueous phase containing the zirconium oxide-containing ruthenium catalyst in the reaction system was always constant, and the reaction product containing benzene, cyclohexene and cyclohexane was continuously taken out from the oil-water separation tank.

[0702] The volume ratio of the water phase to the oil phase in the reactor was water phase:oil phase=2:1, which was kept constant.

[0703] 22 hours after the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0704] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the mass of acetic acid in the reactor to the mass of the catalyst, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0705] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0706] [Example 2-11]

[0707] The reaction of Comparative Example 2-6 was continued, and 24 hours after the reaction started, the reaction mixture was switched to benzene with an acetic acid concentration of 0.01 mg / L. Furthermore, 400 mL of the catalyst slurry containing the reaction solution was taken out, and 400 mL of the slurry subjected to the catalyst activity recovery operation was returned to the reactor, and this operation was continued at a frequency of once a day.

[0708] It should be noted that the catalyst slurry returned to the reactor 24 hours after the start of the reaction was treated until the concentration of acetic acid mixed in the liquid taken out from the reactor was no longer detected. Specifically, the slurry was treated in the same manner as in Comparative Example 5 until the odor of the aromatic hydrocarbon component was no longer detectable, and then contacted with nitrogen containing 7% by volume of oxygen at 50° C. for 1 hour. Then, decantation, removal of the supernatant, and addition of a freshly prepared 0.62 mol / L aqueous zinc sulfate solution were repeated at room temperature to reduce the acetic acid concentration.

[0709] Then, 400 mL of the catalyst slurry subjected to the nitrogen and hydrogen substitution treatment was heated to 140°C, and the pressure in the system was maintained at 0.5 MPa under a hydrogen atmosphere and stirred for 4 hours to obtain the catalyst slurry subjected to the recovery operation and used for catalyst loading.

[0710] After 118 hours from the start of the reaction, the reaction liquid discharged from the oil-water separation tank was collected, and the conversion rate of benzene and the selectivity of cyclohexene were determined based on the results of analyzing the composition of the liquid phase by gas chromatography.

[0711] In addition, the reaction liquid was continuously sampled from the catalyst sampling line installed in the continuous tank reactor, and the catalyst slurry was taken to measure the acetic acid concentration in the zinc sulfate aqueous solution, the ratio of the nitrogen mass in the reactor to the catalyst mass, and the zinc concentration contained in the zirconium oxide-containing ruthenium catalyst.

[0712] The respective analysis values, as well as the conversion rate of benzene and the selectivity of cyclohexene are shown in Table 4 below.

[0713] [Table 4]

[0714]

[0715] [Example 3-1]

[0716] In this embodiment, after the partial hydrogenation reaction of benzene, an extraction step is performed in which cyclohexene and cyclohexane obtained in the reaction are extracted and separated from unreacted benzene using dimethylacetamide as an extractant. Furthermore, in the step of recovering benzene from the mixed solution of the extractant and unreacted benzene and returning the washed benzene to the reactor again, the following operation is performed: by washing benzene with water as described above, dimethylamine and acetic acid, which are decomposition products of dimethylacetamide, generated in the extraction step are reduced, and the dimethylamine and acetic acid are circulated and reused in the partial hydrogenation reaction.

[0717] In order to accelerate the reproduction of the state of the bottom of the benzene recovery column for recovering dimethylacetamide and unreacted benzene, 600 g of dimethylacetamide containing 5.027 g of water and 1.795 g of acetic acid was placed in a 1 L autoclave and overheated at 200° C. for 42 hours.

[0718] 400 g of the treated liquid was taken, 1 kg of benzene was added, and vacuum distillation was performed at 80° C. and 80 kPa. After 3 hours of vacuum distillation, 170 g of the initial distillation was recovered, and benzene was added to the recovered liquid to make 35 kg to prepare a benzene adjustment liquid equivalent to the top of the benzene recovery tower.

[0719] The components of the benzene adjusted liquid were analyzed and found to contain 46.9 mg / L of dimethylamine and 8.31 mg / L of acetic acid.

[0720] A water washing test apparatus with a pipe outer diameter of 150 mm and a height of 1000 mm having a 500 mm packed layer of 5 / 8 inch outer diameter ball rings in the center was used to perform water washing with the benzene adjusting liquid while controlling the liquid temperature to a constant 40°C.

[0721] Water was fed downward from the four nozzles provided at the upper part of the water washing test device at a total of 11.0 L / hr. On the other hand, the benzene adjustment liquid was fed upward from the four nozzles provided at the lower part of the device at a total of 20.7 L / hr, so that 0.53 times the volume of water relative to benzene was brought into contact with benzene, and then the washing water was taken out from the lower part of the water washing test device, and 32.0 kg of washed benzene was recovered from the upper part of the water washing test device.

[0722] The components of benzene after washing were analyzed, and the results showed that dimethylamine was 6.45 mg / L and acetic acid was 0.82 mg / L.

[0723] Next, using the benzene washed with water as described above, the partial hydrogenation reaction of benzene was continuously carried out in the same manner as in Example 1-6 under other conditions.

[0724] 20 hours after the start of the reaction, 0.2 g of 96% by mass sulfuric acid was added to the reactor through the supply line for make-up water in the reaction system. 22 hours later, the reaction liquid discharged from the oil-water separation tank was collected. According to the results of gas chromatography analysis of the composition of the liquid phase, the benzene conversion rate was 50.6% and the cyclohexene selectivity was 75.4%.

[0725] In addition, the reaction solution was sampled from the catalyst sampling line installed in the continuous tank reactor to obtain catalyst slurry. It was confirmed that the dimethylamine concentration in the zinc sulfate aqueous solution was 137 mg / L, the nitrogen concentration was 51 mg / L, the acetic acid concentration was 17 mg / L, and the mass ratio of dimethylamine to the catalyst mass in the reactor was 3.2×10 -3 times, and the nitrogen mass ratio is 1.2×10 -3 times, and the mass ratio of acetic acid is 4.2×10 -4 In addition, the zinc concentration contained in the catalyst was measured and found to be 1.26 mass %.

[0726] This application is based on Japanese Patent Application (Japanese Patent Application No. 2022-125754) and Japanese Patent Application (Japanese Patent Application No. 2022-125785) filed with the Japan Patent Office on August 5, 2022, the contents of which are incorporated into this specification as a reference.

[0727] Industrial Applicability

[0728] The present invention has industrial applicability as a method for producing cycloolefins which suppresses a decrease in the selectivity of cycloolefins and produces cycloolefins efficiently and with high selectivity for a long period of time.

Claims

1. A method for producing cycloolefins, which comprises partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst to produce cycloolefins, wherein: The zinc sulfate aqueous solution contains dimethylamine, The nitrogen concentration in the zinc sulfate aqueous solution is 0.5 to 3000 mg / L.

2. The method for producing cycloolefin according to claim 1, wherein A partial hydrogenation reaction of the monocyclic aromatic hydrocarbons is performed by replacing a portion of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution so that the nitrogen concentration in the zinc sulfate aqueous solution containing the ruthenium catalyst is set to 0.5 to 3000 mg / L.

3. The method for producing cycloolefin according to claim 1 or 2, wherein The nitrogen concentration of the monocyclic aromatic hydrocarbons is 0.003 to 35 mg / L.

4. The method for producing cycloolefin according to claim 1 or 2, wherein The ratio of the mass of nitrogen to the mass of the ruthenium catalyst in the zinc sulfate aqueous solution is 5×10 -6 ~8×10 -2 times.

5. The method for producing cycloolefin according to claim 1 or 2, wherein The nitrogen concentration in the zinc sulfate aqueous solution is set to 0.5 to 1500 mg / L, the nitrogen concentration in the monocyclic aromatic hydrocarbon is set to 0.01 to 16 mg / L, and the ratio of the mass of nitrogen in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is set to 1×10 -5 ~5×10 -2 times, for partial hydrogenation reaction.

6. The method for producing cycloolefin according to claim 1 or 2, wherein The concentration of dimethylamine in the zinc sulfate aqueous solution is 1.7 to 9900 mg / L, The concentration of dimethylamine in the monocyclic aromatic hydrocarbon is 0.01 to 115 mg / L. The ratio of the mass of dimethylamine in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is 2×10 -5 ~0.26 times.

7. The method for producing cycloolefin according to claim 1 or 2, comprising: A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution; After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound; A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the reaction step. In the reaction step, the content of dimethylamine in the zinc sulfate aqueous solution is controlled to be 40 to 1700 mg / L, and the mass ratio of dimethylamine to the mass of the ruthenium catalyst is controlled to be 8×10 -4 ~6×10 -2 times.

8. A method for producing cycloolefins, which comprises partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in an aqueous zinc sulfate solution in the presence of a ruthenium catalyst, wherein: The concentration of acetic acid in the zinc sulfate aqueous solution was set to 1×10 -3 ~100mg / L, for partial hydrogenation reaction.

9. The method for producing cycloolefin according to claim 8, wherein By replacing part of the zinc sulfate aqueous solution with a new zinc sulfate aqueous solution, the acetic acid concentration in the zinc sulfate aqueous solution containing the ruthenium catalyst was set to 1×10 -3 ~100mg / L, partial hydrogenation of monocyclic aromatic hydrocarbons.

10. The method for producing cycloolefin according to claim 8 or 9, wherein The concentration of acetic acid contained in the monocyclic aromatic hydrocarbon is 1×10 -4 ~5mg / L.

11. The method for producing cycloolefin according to claim 8 or 9, wherein The ratio of the mass of acetic acid in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is 3×10 -9 ~2.5×10 -3 times the range.

12. The method for producing cycloolefin according to claim 8 or 9, comprising: A reaction step of partially hydrogenating the monocyclic aromatic hydrocarbon using hydrogen in the aqueous zinc sulfate solution; After the reaction step, an extraction step of extracting the unreacted monocyclic aromatic hydrocarbons using a solvent containing a nitrogen-containing compound; A washing step of contacting the extracted monocyclic aromatic hydrocarbons with 0.05 to 1 volume times of water; and The monocyclic aromatic hydrocarbons after washing with water are supplied to the circulation step of the reaction step. In the reaction step, the ratio of the mass of acetic acid in the zinc sulfate aqueous solution to the mass of the ruthenium catalyst is controlled to be 1×10 -6 ~5×10 -4 times.

13. The method for producing cycloolefin according to claim 1 or 8, wherein The ruthenium catalyst is a ruthenium catalyst containing zirconium oxide, The production method includes a step of regenerating a part or all of the zirconium oxide-containing ruthenium catalyst, and reusing the regenerated zirconium oxide-containing ruthenium catalyst.

14. The method for producing cycloolefin according to claim 1 or 8, wherein The ruthenium catalyst is a ruthenium catalyst containing zirconium oxide, The zinc concentration in the zirconium oxide-containing ruthenium catalyst is 0.5 to 3.5% by mass.

15. The method for producing cycloolefin according to claim 1 or 8, wherein The monocyclic aromatic hydrocarbon includes any one selected from the group consisting of benzene, toluene, and benzene substituted with an alkyl group having 1 to 4 carbon atoms.

16. The method for producing cycloolefin according to claim 1, wherein The concentration of acetic acid in the zinc sulfate aqueous solution is 1×10 -3 mg / L~100mg / L.

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