Ruthenium catalyst

Abstract

To provide a ruthenium catalyst and a method for producing the same that has high catalytic activity when used for hydrogenation reaction of aromatic compound.SOLUTION: Provided is a ruthenium catalyst for hydrogenating aromatic compound that contains ruthenium, silica-alumina and an alkali metal, and in which the ruthenium / alkali metal mole ratio is in the range of 0.01 or more and less than 1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a ruthenium-supported catalyst for the hydrogenation reaction of aromatic compounds. [Background technology]

[0002] It is known that catalysts containing ruthenium as the active ingredient can be used in the hydrogenation reaction of aromatic compounds.

[0003] Patent Document 1 discloses a method for producing cyclic olefins by reacting monocyclic aromatic hydrocarbons with hydrogen in the presence of a particulate hydrogenation catalyst mainly composed of metallic ruthenium. Patent Document 2 discloses a nuclear hydrogenation catalyst used in a nuclear hydrogenation reaction to hydrogenate at least one of the π bonds of an aromatic ring in an aromatic compound having one or more amino groups bonded to the aromatic ring, the catalyst comprising ruthenium (0 valence) and ruthenium oxide. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-247881 [Patent Document 2] International Publication No. 2018 / 159436 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Conventional ruthenium catalysts have had the problem of insufficient catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0006] Therefore, the present invention aims to provide a ruthenium catalyst that exhibits high catalytic activity when used in the hydrogenation reaction of aromatic compounds. [Means for solving the problem]

[0007] The inventors of the present invention have found that the above problems can be solved by using a ruthenium catalyst for hydrogenating aromatic compounds, which contains ruthenium, silica alumina and an alkali metal and has a ruthenium / alkali metal molar ratio in the range of 0.01 or more and less than 1, and have completed the present invention.

Advantages of the Invention

[0008] According to the present invention, when used in the hydrogenation reaction of aromatic compounds, a ruthenium catalyst with high catalytic activity can be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic diagram of a hydrogen temperature-programmed reduction apparatus. [Figure 2] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the ruthenium catalyst obtained in Example 1. [Figure 3] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the ruthenium catalyst obtained in Example 2. [Figure 4] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the ruthenium catalyst obtained in Example 3. [Figure 5] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the ruthenium catalyst obtained in Comparative Example 1. [Figure 6] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the ruthenium catalyst obtained in Comparative Example 2. [Figure 7] It is a graph showing the hydrogen temperature-programmed reduction spectrum of the silica alumina carrier used in Example 1. [Figure 8] It is a schematic diagram of a toluene hydrogenation test apparatus.

Embodiments for Carrying Out the Invention

[0010] The present invention relates to a ruthenium catalyst for hydrogenating aromatic compounds, which contains ruthenium, silica alumina and an alkali metal and has a ruthenium / alkali metal molar ratio of 1 or less.

[0011] In the present invention, ruthenium is an active component having the catalytic ability to hydrogenate aromatic compounds. Also, silica alumina is a carrier for supporting ruthenium. Further, an alkali metal is a promoter for enhancing the effect of the active component. In the field of catalysts, it is common for the content of the promoter to be less than the content of the active component. In contrast, the present invention is characterized in that the catalyst contains more alkali metal than ruthenium. Thus, the inventors have found that when a ruthenium catalyst containing more alkali metal than ruthenium is used in the hydrogenation reaction of aromatic compounds, its catalytic activity becomes high.

[0012] Hereinafter, the ruthenium catalyst of the present invention (hereinafter also referred to as "the catalyst of the present invention") will be described in detail.

[0013] [Catalyst of the Present Invention] The catalyst of the present invention contains ruthenium. In the present invention, ruthenium is not a metal, and most of it is considered to be contained in the catalyst in the form of an oxide or a specific compound. Also, the content of ruthenium is preferably in the range of 0.01% by mass or more and 5% by mass or less, more preferably in the range of 0.1% by mass or more and 3% by mass or less, and particularly preferably in the range of 1% by mass or more and 2% by mass or less with respect to the total mass of the catalyst. Even though the content of ruthenium in the catalyst of the present invention is small in this way, the catalytic activity when used in the hydrogenation reaction of aromatic compounds becomes high.

[0014] The catalyst of the present invention contains more alkali metal than ruthenium. Specifically, the molar ratio of ruthenium to alkali metal (ruthenium / alkali metal) is preferably in the range of 0.01 or more and less than 1, preferably in the range of 0.1 or more and 0.5 or less, and particularly preferably in the range of 0.2 or more and 0.4 or less. The catalyst of the present invention, in which the molar ratio of ruthenium to alkali metal is within the above range, exhibits high catalytic activity when used in the hydrogenation reaction of aromatic compounds. The reason for this effect is not entirely clear, but it is thought that the alkali metal, which is largely supported on the silica-alumina surface, has an auxiliary effect of enhancing the catalytic activity of ruthenium, as well as preventing the aggregation of ruthenium. Furthermore, the alkali metal content is preferably in the range of 0.1% to 5% by mass, more preferably in the range of 0.5% to 4% by mass, and particularly preferably in the range of 1% to 2.5% by mass, relative to the total mass of the catalyst. Moreover, the alkali metal is preferably potassium.

[0015] The catalyst of the present invention contains silica-alumina. In the present invention, the silica-alumina is preferably amorphous. Furthermore, the ratio of Si to Al contained in the silica-alumina is preferably in the range of 0.01 to 0.3, more preferably in the range of 0.01 to 0.2, and particularly preferably in the range of 0.01 to 0.1, based on the SiO2 / Al2O3 molar ratio. The catalyst of the present invention containing silica-alumina with a Si to Al ratio within the above range tends to have high catalytic activity when used in the hydrogenation reaction of aromatic compounds. This is thought to be because increasing the Si content strengthens the solid acid that appears on the surface of the silica-alumina, which strongly fixes the alkali metal and enhances the activity of the alkali metal.

[0016] The catalyst of the present invention preferably has two peaks in the range of 50°C to 350°C in the spectrum obtained by the hydrogen-temperature-reducing method. The hydrogen-temperature-reducing method is a method for evaluating the reducing properties of a sample, and specifically involves heating the sample at a constant heating rate while circulating hydrogen and measuring the amount of hydrogen consumed. Having two peaks in the range of 50°C to 350°C in the spectrum obtained by this method suggests that substances with different reducing properties are present in the catalyst. This is because the reducing properties of a substance change depending on the form of the compound, the supported state, etc. If the substances are in the same state, their reducing properties will be the same, and there will be one peak. If there are two peaks, it is considered that there are at least two types of substances with different reducing properties. Furthermore, since silica-alumina (including alkali-supported silica-alumina) does not have a clear peak in this range (50°C to 350°C), it is considered that the peak appearing in this range is a peak derived from ruthenium. The catalyst of the present invention having such peaks exhibits high catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0017] The catalyst of the present invention exhibits a peak height (H) on the high-temperature side of the spectrum obtained by the hydrogen heating reduction method. high ) and the peak that appears on the low-temperature side (H low The ratio of the height of (H high / H low The ratio of these peaks is preferably 0.2 or higher, more preferably 0.3 or higher, and particularly preferably 0.4 or higher. The upper limit is not particularly limited, but for example it may be 5 or less, 4 or less, or 3 or less. Catalysts of the present invention in which the ratio of these peaks falls within the aforementioned range tend to exhibit high catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0018] The catalyst of this invention has a specific surface area of ​​250 m². 2 It is preferable that it be 275m or more / g 2 It is more preferable that it be 300m or more per gram. 2It is particularly preferable that it is above / g. The upper limit is not particularly limited. For example, it may be 500 m 2 / g or less, and may be 400 m 2 / g or less, and may be 350 m 2 / g or less. The catalyst of the present invention having a specific surface area within the above range is likely to have high catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0019] It is preferable that the amount of CO adsorbed per 1 g of ruthenium in the catalyst of the present invention is 120 mL / g or more. The upper limit is not particularly limited. For example, it may be 300 mL / g or less, may be 250 mL / g or less, and may be 200 mL / g or less. CO adsorption is one of the methods for evaluating the surface area of ruthenium. Since CO adsorbs on the surface of ruthenium, it can be understood that if the adsorption amount is large, the surface area of ruthenium is large. And since most of the catalytic reactions occur on the surface of the active component, it is important to quantify the surface area of such an active component. The catalyst of the present invention having the amount of CO adsorbed per 1 g of ruthenium within the above range is likely to have high catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0020] It is preferable that the water content calculated from the weight reduction amount before and after heating for a predetermined time in the catalyst of the present invention is 1% or less, and more preferably 0.7% or less. Although the reason is unclear, the catalyst of the present invention having a water content within the above range is likely to have high catalytic activity when used in the hydrogenation reaction of aromatic compounds.

[0021] The catalyst of the present invention is preferably in the form of a molded body, and more preferably in the form of a pellet. The pellet shape is preferably similar to a columnar shape, and can take shapes such as cylindrical, three-leaf, or four-leaf. The catalyst of the present invention is particularly preferably four-leaf. A four-leaf molded body tends to have a larger external surface area compared to a cylindrical molded body, and tends to have higher catalytic activity when used in the hydrogenation reaction of aromatic compounds. When the catalyst of the present invention is a molded body with a shape similar to a columnar shape, its diameter is preferably 1.5 mm or less, and more preferably less than 1.4 mm. The external surface area can be increased by reducing the diameter of the molded body. Note that this diameter refers to the major axis of the bottom surface of the molded body. Furthermore, its strength is preferably 30 N or more. The higher the strength, the less likely cracking or powdering will occur when the catalyst is packed into a reactor or the like. There is no particular upper limit, but for example, it may be 200 N or less, 150 N or less, or 100 N or less. In this invention, the strength of the molded article refers to the strength at which it breaks when a certain force is applied. However, depending on the shape of the molded article, the ease of breakage may differ depending on the direction in which the force is applied. Therefore, in this invention, the strength refers to the strength when the force is applied in the direction in which it is most likely to break.

[0022] The catalyst of the present invention can be used in a wide range of reactions that hydrogenate aromatic compounds. For example, it can be suitably used in the reaction described in Patent Document 1 for synthesizing cyclic olefins by reacting monocyclic aromatic hydrocarbons with hydrogen. It can also be used in the nuclear hydrogenation reaction described in Patent Document 2, in which at least one π bond of an aromatic ring of an aromatic compound having one or more amino groups bonded to the aromatic ring is hydrogenated. The catalyst of the present invention is particularly suitable as a catalyst for such nuclear hydrogenation reactions of aromatic compounds.

[0023] The catalyst of the present invention can be manufactured using a manufacturing method that includes, for example, an alkali metal support preparation step of supporting an alkali on silica alumina to obtain an alkali metal support, and an active component support step of contacting an acid solution in which ruthenium is dissolved with the alkali metal support to obtain a ruthenium catalyst.

[0024] In this manufacturing method, an alkali metal is pre-supported on silica-alumina, and an acidic solution containing ruthenium is brought into contact with it to cause a neutralization reaction on the surface of the silica-alumina. Through this neutralization reaction, the ruthenium that was dissolved in the acidic solution precipitates on the surface of the silica-alumina as a ruthenium compound. By using this manufacturing method, the alkali metal can be uniformly dispersed on the surface of the silica-alumina while supporting ruthenium, thereby further enhancing the effect of the catalyst of the present invention.

[0025] The manufacturing method will be described in detail below, but the method for producing the catalyst of the present invention is not limited to this method.

[0026] [Alkali metal support preparation process] This manufacturing method includes a carrier preparation step in which an alkali metal is supported on silica-alumina to obtain an alkali metal-supported carrier. In the manufacturing method of the present invention, it is important to support the alkali metal on the silica-alumina carrier before supporting ruthenium on it.

[0027] The silica-alumina may be commercially available silica-alumina, or it may be silica-alumina prepared by mixing silica sol and alumina sol. The silica-alumina is preferably amorphous. Furthermore, the ratio of Si to Al in the silica-alumina, calculated as the SiO2 / Al2O3 molar ratio, is preferably in the range of 0.01 to 0.3, more preferably in the range of 0.01 to 0.2, and particularly preferably in the range of 0.01 to 0.1. In addition, the specific surface area of ​​the silica-alumina is 250 m². 2 It is preferable that it be 275m or more / g 2 It is more preferable that it be 300m or more per gram. 2 It is particularly preferable that the amount be 1 / g or more. There is no particular upper limit, but for example, 500m 2 It may be less than / g, and 400m 2 It may be less than / g, and 350m 2 It may be less than / g.

[0028] The silica-alumina may be in the form of a molded body, more preferably in the form of a pellet, and particularly preferably in the form of a four-leaf clover, which tends to increase the outer surface area. Furthermore, its diameter is preferably 1.5 mm or less, and more preferably less than 1.4 mm.

[0029] Any alkali metal compound containing an alkali metal that dissolves in a solvent and exhibits basic properties can be used; these are conventionally known compounds. For example, conventionally known alkali metal compounds such as alkali metal hydroxides and alkali metal carbonates can be used. More specifically, it is preferable to use at least one selected from sodium carbonate and potassium carbonate.

[0030] Methods for supporting alkali metals on silica-alumina can be conventionally known. For example, methods such as physically mixing silica-alumina with a compound containing an alkali metal, immersing silica-alumina in a solution containing an alkali metal, and spray-supporting a solution containing an alkali metal onto silica-alumina can be used. From the viewpoint of uniformly supporting the alkali metal on silica-alumina, methods of immersing silica-alumina in an alkaline solution or spray-supporting an alkaline solution onto silica-alumina are preferred. In these methods, the alkali metal is supported on the silica-alumina together with the solvent contained in the solution, so it is preferable to remove the solvent by drying using conventionally known methods.

[0031] It is preferable that the amount of alkali metal supported is greater than the amount of ruthenium supported in the process described later. Specifically, the molar ratio of the amount of ruthenium supported to the amount of alkali supported on the carrier (ruthenium / alkali metal) is in the range of 0.01 or more and less than 1, preferably in the range of 0.01 or more and less than 1, more preferably in the range of 0.1 or more and 0.5 or less, and particularly preferably in the range of 0.2 or more and 0.4 or less.

[0032] [Active ingredient loading process] The manufacturing method of the present invention includes a ruthenium loading step in which a ruthenium catalyst is obtained by contacting an acid solution in which ruthenium is dissolved with an alkali metal supported carrier. In this step, ruthenium is supported on silica alumina by a neutralization reaction between the alkali metal contained in the alkali metal supported carrier and the acid solution containing ruthenium.

[0033] Acid solutions containing ruthenium can be prepared by conventionally known methods. A common method involves dissolving a ruthenium salt in water and adjusting the pH to less than 7 if necessary. Alternatively, an acid solution can be prepared by dissolving ruthenium metal or a compound in an acid. The pH of the ruthenium-containing acid solution is preferably less than 7, more preferably less than 5, and particularly preferably less than 3.

[0034] Ruthenium salts that can be used are conventionally known ones such as ruthenium nitrate and ruthenium chloride. More specifically, it is preferable to use ruthenium chloride.

[0035] Conventional methods can be used to contact an alkali-supported carrier with an acidic solution containing dissolved ruthenium. For example, methods such as immersing the alkali-supported carrier in an alkaline solution, or spraying the alkaline solution onto the alkali-supported carrier, can be used.

[0036] If any solvent derived from the acid solution remains in the ruthenium catalyst obtained in this process, it can be removed by drying at a temperature of 200°C or lower.

[0037] The ruthenium catalyst obtained in this process may contain residual ruthenium salts that have not reacted with the alkali metal supported on the surface of the silica-alumina support. In such cases, it is advisable to complete the reaction using an alkaline solution with a pH of 8 or higher. For example, a method of immersing such a ruthenium catalyst in an alkaline solution can be used.

[0038] The ruthenium catalyst obtained in this process may be washed as necessary to remove salts produced by the neutralization reaction. For example, the ruthenium catalyst obtained in this process can be suspended in deionized water, pure water, etc. However, the alkali metals contained in the catalyst of the present invention are difficult to remove by washing, possibly because they are strongly fixed to the silica-alumina support.

[0039] In this manufacturing method, it is preferable that a calcination step in which the ruthenium catalyst is calcined in air at a temperature exceeding 200°C is not included after the active ingredient loading step. Calcining the ruthenium catalyst at a temperature exceeding 200°C changes the morphology of the ruthenium compound produced by the neutralization reaction, which alters the profile in the hydrogen temperature-induced reduction method.

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Measurement method or evaluation method] Various measurements and evaluations were performed as follows:

[0041] [1] Compositional analysis (Ru, K, Si, and Al) A complete aqueous solution of the sample was prepared, diluted with water to the appropriate concentration, and then the content of ruthenium, potassium, silicon, and aluminum was measured using an ICP emission spectrometer (Agilent Technologies, Inc., 730ICP-OES, inductively coupled plasma emission spectroscopy).

[0042] [2] Hydrogen temperature rise reduction measurement Hydrogen reduction was measured using the hydrogen reduction heating apparatus shown in Figure 1 under the following conditions. In the hydrogen reduction heating apparatus, the sample is placed in a sample tube in the heating furnace, a mixed gas is introduced into the sample tube, and the exhaust gas discharged from the sample tube is measured with a thermal conductivity detector to obtain the hydrogen reduction spectrum. The hydrogen reduction spectra of the ruthenium catalysts obtained in Examples 1-3 and Comparative Examples 1-2 are shown in Figures 2-6, respectively. The hydrogen reduction spectrum of the silica-alumina support used in Example 1 is shown in Figure 7. <Sample pretreatment> If the sample is a molded body, grind the sample in a mortar and then use a sieve to sizing it to a size of 355 μm to 710 μm. If the sample is a powder, first mold it into a body using a hydraulic press or similar machine, and then sizing it using the method described above. <Hydrogen heating and reduction conditions> Sample filling amount: 0.10g Heating rate: 10°C / min. Gas composition: H2 is 10 Vol%, N2 is balanced Gas flow rate: 30 mL / min.

[0043] [3] CO adsorption The samples were measured under the following measurement conditions and procedure. <Measurement conditions> Equipment: Metal dispersion analyzer BEC-METAL-1 (manufactured by Microtrac-Bell Co., Ltd.) Method: Pulse method Pretreatment: 250°C, 3 hours (under hydrogen flow) Sample mass: 0.05g

[0044] [4] Specific surface area measurement The samples were measured under the following measurement conditions and procedure. <Measurement conditions> Device: MacsorbHM model-1220 (manufactured by Mountec Co., Ltd.) Method: Nitrogen adsorption method (BET 1-point method) Pretreatment: 250°C, 40 minutes (under nitrogen flow) Sample mass: 0.1g <Measurement Procedure> The sample was placed in a measurement cell and pretreated under the conditions described above. Then, the sample was maintained at liquid nitrogen temperature in a nitrogen mixed gas stream of 30v% nitrogen / 70v% helium to allow nitrogen to equilibrium adsorb onto the sample. Next, the sample temperature was gradually increased to room temperature while the mixed gas flowed through it. The amount of nitrogen desorbed during this time was detected, and the specific surface area was calculated from the amount of desorbed nitrogen.

[0045] [5] Intensity measurement The intensity of the sample was measured under the following conditions. Measurement device: Crushing strength meter (Shimadzu Corporation, AG-X plus 5KN) Number of measurements: 30 (The average intensity per pellet was used as the intensity). Measurement direction: The thinnest surface (the surface with the lowest strength) was measured in the longitudinal, transverse, and length directions.

[0046] [6] [Moisture content measurement] The sample was left to stand in a 110°C incubator for 3 hours, and the weight loss during this time was calculated as water content.

[0047] [7] Activity evaluation Using the toluene hydrogenation test apparatus shown in Figure 8, toluene (TOL) was hydrogenated under the following conditions, and the methylcyclohexane (MCH) content in the reaction effluent was calculated from the resulting chart using the following formula. In the toluene hydrogenation test apparatus, the sample is placed in the reactor, a mixed gas is introduced into the reactor, and the exhaust gas discharged from the reactor is measured using gas chromatography (flame ionization detector) to obtain the chart. MCH content (%) = Area of ​​peaks attributed to MCH / (Area of ​​peaks attributed to MCH + Area of ​​peaks attributed to TOL) × 100 <Equipment conditions> Reactor: Glass tube (inner diameter 15mmΦ) Drain cover: SUS304 (50 mesh) <Hydrogen heating and reduction conditions> Sample filling amount: 0.10g Gas composition: H2 10.0 NL / h, N2 7.0 NL / h, TOL 0.34 NL / h Base temperature: 70℃ <Gas Chromatography Analysis Conditions> Equipment: J-Science Lab GC7000F FID Column: Bentone34+DIDP / Uniport KA(60-80)2m Column temperature: 75℃ Injection temperature: 100℃ Carrier gas: N2 at 25 mL / min

[0048] [Example 1] 100g silica-alumina support (four-leaf clover shape, SiO2 / Al2O3 = 0.05, specific surface area: 302m²) 2 The alkali metal-supported carrier was obtained by immersing the ruthenium ( / g) in 250 mL of an aqueous solution containing 8% by mass potassium carbonate, and then drying it at 130°C for 14 hours. Using an aqueous solution of ruthenium chloride with a ruthenium concentration of 50 g / L (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., product name: Ru(4) chloride solution, pH 2 or less), the ruthenium was spray-supported at room temperature so that 2% by mass of ruthenium was supported relative to the mass of the alkali metal carrier. After standing in air for more than 1 hour, it was further immersed in an aqueous solution containing 0.5% by mass potassium carbonate. The potassium carbonate aqueous solution was removed, followed by washing with pure water. Finally, it was dried at 130°C for 14 hours to obtain the ruthenium catalyst. The obtained ruthenium catalyst was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0049] [Example 2] A ruthenium catalyst was obtained in the same manner as in Example 1, except that the ruthenium chloride aqueous solution used in Example 1 was replaced with a ruthenium chloride aqueous solution with a ruthenium concentration of 100 g / L (manufactured by Kojima Chemical Co., Ltd., product name: Ruthenium Chloride Solution, pH 2 or less, trivalent). The obtained ruthenium catalyst was subjected to the aforementioned measurements and evaluations. The results are shown in Table 1.

[0050] [Example 3] 100g silica-alumina support (four-leaf clover shape, SiO2 / Al2O3 = 0.05, specific surface area: 302m²) 2 A ruthenium aqueous solution with a ruthenium concentration of 50 g / L (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., product name: Ru(4) chloride solution, pH 2 or less) was spray-loaded onto the support at room temperature so that 2% by mass of Ru was supported relative to the mass of the support. After standing in air for more than 1 hour, it was further immersed in a 10% by mass potassium carbonate aqueous solution. From there, the ruthenium catalyst was obtained by the same method as in Example 1. The obtained ruthenium catalyst was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0051] [Comparative Example 1] The silica-alumina support of Example 1 was replaced with a γ-alumina support (manufactured by JGC Catalysts & Chemicals, cylindrical shape, SiO2 / Al2O3=0, specific surface area 200 m²). 2 A ruthenium catalyst was obtained in the same manner as in Example 1, except that the ratio was changed to / g). The obtained ruthenium catalyst was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0052] [Comparative Example 2] The silica-alumina support of Example 2 was replaced with a γ-alumina support (manufactured by JGC Catalysts & Chemicals, cylindrical shape, SiO2 / Al2O3=0, specific surface area 200 m²). 2 A ruthenium catalyst was obtained in the same manner as in Example 2, except that the ratio was changed to / g). The obtained ruthenium catalyst was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0053] [Table 1]

Claims

1. It contains ruthenium, silica alumina, and alkali metals. The ruthenium / alkali metal molar ratio is in the range of 0.01 or higher and less than 1. The silica-alumina is amorphous, The ratio of Si to Al is in the range of 0.01 or more and 0.3 or less, when expressed as the SiO₂ / Al₂O₃ molar ratio. A ruthenium catalyst for hydrogenating monocyclic aromatic hydrocarbons.

2. The ruthenium catalyst according to claim 1, wherein the alkali metal is potassium.

3. The ruthenium catalyst according to claim 2, wherein the ruthenium / alkali metal molar ratio is in the range of 0.1 or more and 0.5 or less.

4. The ruthenium catalyst according to claim 2, wherein the alkali metal content is in the range of 0.5% by mass or more and 4% by mass or less.

5. A ruthenium catalyst according to any one of claims 1 to 4, wherein the spectrum obtained by the hydrogen temperature-reducing method has two peaks in the range of 50°C or higher and 350°C or lower.

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