JPH0816073B2 - Method for producing cycloolefin - Google Patents

Description

The present invention relates to a method for partially reducing monocyclic aromatic hydrocarbons to produce corresponding cycloolefins, particularly cyclohexenes, with high selectivity and high yield. It is about.

Cyclohexenes are highly valuable as intermediate raw materials for organic chemical industrial products, and are especially important as polyamide raw materials and lysine raw materials.

(Prior Art) As a method for producing such a cyclohexene, for example, (1) a method using a catalyst composition containing water and an alkaline agent and an element of Group VIII of the periodic table (Japanese Patent Publication No. 56-22850), ( 2) A method of using a ruthenium catalyst supported on an oxide of nickel, cobalt, chromium, titanium or zirconium, and using an alcohol or an ester as an additive (Japanese Patent Publication No. 523933), (3) copper, silver, cobalt, Or a method using a ruthenium catalyst containing potassium and water and a phosphate compound (Japanese Patent Publication No. 56-4536), (4) Ruthenium catalyst and Group IA metal, Group II A metal and manganese of the periodic table, A method of reacting in the presence of a neutral or acidic aqueous solution containing at least one selected cation salt (Japanese Patent Publication No. Sho 57-7607);
(5) A solid catalyst containing at least one of ruthenium and rhodium as a main component is a metal of Group IA, Group IIA of the periodic table,
A method of reacting in the presence of water using an aqueous solution containing a salt of at least one cation selected from the group consisting of manganese, iron and zinc (JP-A-51-98).
243), (6) at least one of zinc oxide and zinc hydroxide is added to the reaction system as an activating component using a ruthenium catalyst and reacted (JP-A-59-184138), (7) ) In the presence of water and at least one zinc compound, a method of using a metal ruthenium crystallite having an average crystallite diameter of 200Å or less and / or its agglomerated particles (JP-A-61-50930) is disclosed. Proposed.

(Problems to be Solved by the Invention) However, in these conventionally known methods, in order to increase the selectivity of the target cyclohexenes, it is necessary to significantly suppress the conversion rate of the raw materials, and the reaction rate is extremely high. At present, the yield and productivity of cyclohexenes are small, such as being small, and it is not a practical method for producing cyclohexenes under the present circumstances.

Further, in order for the method for producing such cyclohexenes to be practical, it is necessary and important that the catalyst used in the reaction is capable of continuously maintaining stable activity or selectivity, This is not always sufficient in the conventional technology.

Further, according to a study by the present inventors, for example, Japanese Patent Laid-Open No.
In the case where the metal ruthenium particles proposed in JP-A-50930 are used alone as a catalyst, cycloolefin may be obtained in a relatively high yield, but in the contact portion between the reactor and the reaction liquid, etc. It has been found that there are some cases in which it is difficult to maintain a stable reaction system, such as the catalyst adhering and accumulating or the catalyst itself changing.

(Means for Solving Problems) In order to solve such problems, the present inventors have aimed to improve the yield of cyclohexenes and to obtain a stable catalyst system which is industrially advantageous. The present invention has been made by intensively studying a catalyst system in the partial reduction method of hydrogen, that is, a system comprising other components of the main catalyst.

That is, the present invention, in the coexistence of water in the coexistence of water, the monocyclic aromatic hydrocarbons, when using hydrogenation catalyst particles containing metal ruthenium as a main component having an average crystallite diameter of 200 Å or less, the catalyst, Apart from particles, Ti, Zr, Hf, Nb, T
a, Cr, Fe, Co, Al, Ga, Si at least one metal hydroxide selected from the addition, further in the presence of at least one solid basic zinc salt, neutral or acidic By carrying out the reaction under the conditions, it is a method of producing cycloolefins in a good yield which has never been obtained, and further producing cycloolefin which can be used as a surprisingly stable catalyst system. According to the method of the present invention, it is possible to increase the yield of cycloolefins to 40% or more, and at the same time, the combination of the present invention prevents the hydrogenation catalyst from undergoing various alterations such as aging. It is a very useful method from a practical point of view because it can significantly suppress the change of reaction results due to the progress of various aggregations and the change of average crystallite size.

 Hereinafter, specific embodiments of the present invention will be described.

The monocyclic aromatic hydrocarbon as the raw material of the present invention refers to benzene, toluene, xylenes, and lower alkylbenzenes having an alkyl group having 4 or less carbon atoms.

In the present invention, hydrogenation catalyst particles containing ruthenium metal as a main component and having an average crystallite diameter of 200 Å or less are used. This catalyst is obtained by reducing various ruthenium compounds, or other metal such as zinc or chromium, molybdenum, tungsten, manganese, cobalt, nickel, after the preparation step or preparation thereof.
The main component is ruthenium to which iron, copper, etc. are added. The various ruthenium compounds are not particularly limited, but for example, chlorides, bromides, iodides, nitric acid temperatures, sulfates, hydroxides, oxides, ruthenium reds, or complexes containing various rutheniums are used. As the reduction method, reduction with hydrogen gas or chemical reduction with formalin, sodium borohydride, hydrazine or the like can be performed. In particular, a method of hydrolyzing a ruthenium salt into a hydroxide and reducing the hydroxide is preferably used.

Further, in the method of the present invention, if a reduced product of ruthenium containing zinc in advance is used, the yield of cycloolephine can be further increased and it can be effectively used. Such a catalyst is a reduced product obtained by previously adding a valuable ruthenium compound with a zinc compound and then reducing it, and ruthenium is reduced to a metallic state. Valuable ruthenium compounds that can be used include, for example, salts such as chlorides, nitrates and sulfates, complexes such as ammine complex salts, hydroxides and oxides, but especially trivalent or tetravalent ruthenium compounds are available. It is preferable because it is easy and easy to handle. A wide range of zinc compounds can be used, such as salts such as chlorides, nitrates and sulfates, complexes such as ammine complex salts, hydroxides and oxides.

The zinc content in such a catalyst is 0.1 with respect to ruthenium.
It is adjusted to 50% by weight, preferably 2 to 20% by weight. Therefore, the main constituent of the catalyst is ruthenium, not zinc.

Such a valuable ruthenium compound containing zinc may be obtained as a solid by a general coprecipitation method using a mixed solution of zinc and a compound of ruthenium, or may be obtained in a homogeneous solution state. May be.

As a method of reducing the valuable ruthenium compound containing zinc, a general method of reducing ruthenium can be applied. For example, a method of reducing with hydrogen in the gas phase, a method of reducing with hydrogen or an appropriate chemical reducing agent such as NaBH ₄ or formalin in the liquid phase is preferably applied, and reduction with hydrogen in the gas phase or liquid phase is performed. The method is particularly preferred.

When reducing with hydrogen in the gas phase, it is advisable to avoid extremely high temperature or to dilute hydrogen with other inert gas in order to avoid increasing the crystallite size.
When reducing in the liquid phase, add water or alcohol to
It may be carried out by dispersing a solid of a valuable ruthenium compound containing zinc, or may be carried out in the state of a homogeneous solution. At this time, stirring, heating and the like may be appropriately performed in order to promote the reduction better. Instead of water, an aqueous alkali solution or an appropriate aqueous metal salt solution such as an aqueous alkali metal salt solution may be used.

The hydrogenation catalyst particles as described above are present in the reaction system as crystallites mainly composed of ruthenium and / or aggregated particles thereof, but in order to improve the selectivity and yield of cycloolefins, and further the reaction rate, The average crystallite diameter of the crystallite needs to be 200 Å or less, preferably 150 Å or less, and more preferably 100 Å or less. Here, the average crystallite diameter is calculated by the Scherrer equation from the spread of the diffraction line width obtained by a general method, that is, the X-ray diffraction method. Specifically, when CuKα rays are used as an X-ray source, it is calculated from the spread of the diffraction line having a maximum at a diffraction angle (2θ) of around 44 °.

In the present invention, in addition to the above hydrogenation catalyst particles, a hydroxide of at least one metal selected from Ti, Zr, Hf, Nb, Ta, Cr, Fe, Co, Al, Ga and Si. The reaction is carried out by adding, but hydroxides of Zr and Hf are preferable, and further,
Zr hydroxide is preferred.

The amount of hydroxide of the metal added is 1 × 10 ^{−4 to} 0.3 times by weight, preferably 1 × 10 ^{−3 to} 0.1 times by weight, in terms of the amount of only the metal, with respect to water.

Such a metal hydroxide is generally obtained by hydrolysis of an aqueous salt solution of the metal or addition of alkali or ammonia. As the metal salt, for example, a wide range of chlorides, bromides, iodides, oxychlorides, nitrates, sulfates, or complexes containing the metal can be used.

The effect obtained by adding such a hydroxide is to suppress the fluctuation of the reaction system due to the adhesion of the hydrogenation catalyst to the reactor surface or the aggregation of the hydrogenation catalyst, and to maintain a stable reaction system. In particular, it has a great effect on the continuous production of cycloolefins over a long period of time. Further, there is an effect of facilitating the handling of the slurry containing the hydrogenation catalyst, for example, apparently diluting or increasing the amount of the hydrogenation catalyst to facilitate the preparation and recovery of the catalyst.

On the other hand, what should be clarified is that when a ruthenium-supported catalyst prepared by supporting ruthenium in such a hydroxide by an ordinary method such as an immersion method, a dry solidification method, or a precipitation method and then reducing it is used as a hydrogenation catalyst. The selectivity of cycloolefins is extremely low as compared with the method of the present invention, and the addition of the hydroxide in the method of the present invention is essentially different from that of the ruthenium-supported catalyst.

In the present invention, the solid basic zinc salt coexisting in the reaction system refers to a zinc salt containing a conjugate base residue of various acids and a hydroxyl group or an oxygen atom which is regarded as a negative component other than this. Specifically, for example, ZnSO ₄・ 1 / 2ZnO, ZnSO ₄・ ZnO ・ H ₂ O,
_{ZnSO 4 · 3ZnO · nH 2 O} (n is 0 ≦ n ≦ 8 number becomes), ZnSO ₄ · ₄
Basic zinc sulfate represented by ZnO ・ 4H ₂ O, ZnF ₂・ 4Zn
(OH) ₂ , ZnO ・ 3ZnCl ₂・ H ₂ O, ZnO ・ ZnCl ₂・ H ₂ O and 1.5H
₂ O, 3ZnO ・ 2ZnCl ₂・ 11H ₂ O, 2ZnO ・ ZnCl ₂・ 11H ₂ O, 2ZnO ・ Zn
Cl ₂・ 4H ₂ O, 5ZnO ・ 2ZnCl ₂・ 26H ₂ O, 5ZnO ・ 5ZnCl ₂・ 8H ₂ O, 3
ZnO ・ ZnCl ₃・ nH ₂ O (n is 2, 3, 4, 5, or 8), 4ZnO ・ ZnCl ₂
・ NH ₂ O (n is 4,6 or 11), 5ZnO ・ ZnCl ₂・ nH ₂ O (n is 6,8)
Or 29), 11ZnO ・ 2ZnCl ₂ , 6ZnO ・ ZnCl ₂・ 6H ₂ O and 10H ₂
O, 8ZnO ・ ZnCl ₂・ 10H ₂ O, 9ZnO ・ ZnCl ₂・ 3H ₂ O and 14H ₂ O,
ZnBr ₂ · 4ZnO · nH ₂ O (n is 10, 13 or 29), ZnBr ₂ · 5ZnO ·
6H ₂ O, ZnBr ₂・ 6ZnO ・ 35H ₂ O, ZnI ₂・ 4Zn (OH) ₂ , ZnI ₂・ 5Zn
Basic zinc halides represented by O ・ 11H ₂ O, ZnI ₂ , 9ZnO ・ 24H ₂ O, 8ZnO ・ N ₂ O ₅ , 4H ₂ O, 4ZnO ・ N ₂ O ₅ , 4H ₂ O, 5Z
Basic zinc nitrate represented by nO ・ N ₂ O ₅・ 5H ₂ O and 6H ₂ O, 5ZnO ・ N ₂ O ₅・ 5H ₂ O, base represented by 4ZnO ・ P ₂ O ₅・ H ₂ O There are acidic zinc phosphate, basic zinc acetate and the like, and particularly basic zinc sulfate and basic zinc chloride give preferable results.

These basic zinc salts can generally be obtained by appropriately treating an aqueous solution of zinc salt. For example, it can be obtained as a solid by using an aqueous solution of zinc salt as a mother liquor and allowing a suitable alkaline agent to act thereon, and further by heating. In addition, a mixture of various basic zinc salts may be obtained by adding zinc hydroxide or zinc oxide to an aqueous solution of a strong acid salt of zinc and boiling the mixture. It may also be obtained by appropriately treating metallic zinc.

To make these coexist as a solid in the reaction system,
It is preferred that one or a mixture of these be mixed with the ruthenium catalyst in the form of powder or be added separately to the reaction system.

In the method of the present invention, these basic zinc salts must coexist in an insoluble state. The solubility of a basic zinc salt in an aqueous solution is generally a negligible amount when the aqueous solution is neutral, but it increases as the pH of the aqueous solution decreases, so the amount added to the reaction system depends on the pH of the aqueous solution. It is preferable to decide in consideration. However, due to the adsorptive power of the ruthenium catalyst used in the present invention, the basic zinc salt can often coexist as a solid on the catalyst even if the addition amount is less than the saturated solubility in the reaction system.

Such a solid basic zinc salt can be directly separated from the reaction system together with the hydrogenation catalyst and directly confirmed as a solid by X-ray diffraction, fluorescent X-ray, X-ray photoelectron spectroscopy and the like. As a method for quantifying the coexisting amount of the solid basic zinc salt, a method of dissolving and measuring the separated solid together with the hydrogenation catalyst is preferably used.

Specifically, after the catalyst slurry is allowed to settle out of the reaction solution, the supernatant liquid is removed, and the insoluble basic zinc salt is dissolved in the remaining slurry or in the solid obtained by passing the slurry in the reaction solution. It can be determined by adding a liquid to be obtained, for example, concentrated hydrochloric acid, and by performing a fixed amount of zinc ion which is usually analyzed. Also, for the purpose of removing the influence of ions coexisting in the reaction system on the analysis, in some cases, the slurry or the passed solid matter is washed with water such that the dissolved amount of the insoluble basic zinc salt is negligible. After that, concentrated hydrochloric acid or the like may be added to quantify zinc ions.

In the present invention, such a solid basic zinc salt is made to coexist with the hydrogenation catalyst in an amount of 1 × 10 ⁻⁴ to 1 times by weight, preferably 1 × 10 ^{−3 to} 0.5 times by weight in terms of zinc only. To react. If the coexisting amount is too small, the effect of improving the selectivity and yield of cycloolefin is dilute, and if the coexisting amount is too large, the reaction rate decreases and, as a result, a large amount of hydrogenation catalyst is required. It is difficult to become an advantageous reaction system.

Thus, the coexistence of the solid basic zinc salt can increase the selectivity and the yield of cycloolefin. Furthermore, since the reaction temperature range in which equivalent high selectivity and high yield can be maintained is expanded, and cycloolefin can be obtained in good yield even at relatively low temperature, the degree of freedom in selecting reaction conditions is expanded, and Will be extremely valuable.

Thus, it is not always clear why coexistence of a basic zinc salt improves the selectivity and yield of cycloolefin, but the coexisting insoluble basic zinc salt is adsorbed on the hydrogenation catalyst. It is considered that an active site advantageous for the production of cycloolefin is revealed.

On the other hand, the addition of the metal hydroxide and the coexistence of solid basic zinc in the present invention exert a surprising effect on the stability of the catalyst as described below.

In general, the use of a fine metal catalyst is different from the catalyst in which the metal is supported on a carrier, and secondary coagulation or sintering often progresses in the reaction system, resulting in a difficulty in sustainability as a stable catalyst system. is there. This also applies to the metal ruthenium catalyst used in the method of the present invention,
From the standpoint of practicality, avoiding the progress of secondary agglomeration and sintering is a necessary technique. It was revealed that the coexistence of the solid basic zinc salt in the present invention surprisingly also has the effect of suppressing the change of the catalyst due to such secondary aggregation and sintering.

Addition of hydroxides of metals selected from Ti, Zr, Hf, Nb, Ta, Cr, Fe, Co, Al, Ga, Si also has the same effect, and hydroxides of these metals and solid basic zinc The synergistic effect of the combined use of salts can make the catalyst and the reaction system extremely stable.

When the hydrogenation catalyst used in the present invention is kept under the reaction conditions in the absence of the solid basic zinc salt and the hydroxide of the above metal, the secondary aggregation of the catalyst further proceeds.

In the catalyst in which the secondary aggregation further progresses, the dispersibility of the catalyst particles in the aqueous phase is significantly deteriorated. In an aggregate in such a state, diffusion of hydrogen and benzene into the metal ruthenium in the aggregate becomes difficult, especially diffusion of hydrogen, and it is difficult to supply a sufficient amount necessary for the reaction onto the catalyst. It is not possible to obtain a satisfactory reaction state. In particular, when the supply of hydrogen onto the catalyst is insufficient, the reaction rate decreases and side reactions increase remarkably. Further, the diffusion of cycloolefin produced by the reaction to the outside of the reaction field or the diffusion of the existing aggregates is slowed down, the hydrogenation reaction further proceeds, and the side reaction to cycloalkane increases.
Such a change in the aggregation state can also be directly observed by an electron microscope.

Similarly, when the hydrogenation catalyst used in the present invention is kept under reaction conditions for a long time in the absence of a solid basic zinc salt and a hydroxide of the metal, the metal ruthenium obtained by an X-ray diffraction method is obtained. It has been found that the average crystallite size of is increased. Such an increase in the average crystallite size with time leads to a decrease in the surface area of the catalyst, and in particular the reaction rate decreases with time, making it difficult to control a stable reaction over a long period of time.
This tendency shows that when the hydrogenation catalyst concentration and the reaction temperature are increased,
It becomes even more remarkable. For example, when trying to carry out this reaction by increasing the productivity of cycloolephine per reactor volume, it means that it becomes more difficult to maintain the stability of the reaction. Not preferable. Clearly, it is desirable that such catalyst changes be as small as possible. For the first time, it has been found that the combined use of the hydroxide and the basic zinc salt used in the present invention makes it possible to obtain a situation in which the above-described increase in the average crystallite diameter of ruthenium metal can be substantially ignored.

Furthermore, in the present invention, Zr and hydroxide are used as hydroxides.
It was found that when Hf hydroxide is used and basic zinc sulfate is used as the basic zinc salt, the stabilizing effect on the hydrogenation catalyst as described above is particularly high.

Although the mechanism by which the stabilization of the reaction system according to the present invention is expressed is not clear, the solid basic zinc salt is present on the surface of the hydrogenation catalyst or hydroxide, and the property of the surface is changed. It is believed that Ti, Zr, Hf, Nb, T
The coexistence of at least one hydroxide selected from a, Cr, Fe, Co, Al, Ga, and Si greatly suppresses the collision of hydrogenation catalysts with each other, reducing the surface area and increasing the crystallite size. It is considered that the secondary aggregation of the catalyst, which causes the indirect cause, is further suppressed.

As described above, the extremely stable reaction system first achieved by the combination of the method of the present invention can be said to be extremely valuable from a practical and industrial point of view.

The present invention requires the presence of water. Although the amount of water varies depending on the reaction mode, it can be present in an amount of 0.01 to 100 times by weight with respect to a commonly used monocyclic aromatic hydrocarbon, but under the reaction conditions, the raw materials and products are mainly used. It is necessary that an organic liquid phase as a component and a liquid phase containing water form two phases, and coexistence of a very small amount of water or a very large amount of water so as to form a homogeneous phase under reaction conditions. Presence reduces the effect, and too much water also requires the reactor to be large, so it is practically 0.
It is desirable to coexist 5 to 20 times by weight.

Further, in the present invention, a preferable cycloolefin selectivity and yield can be obtained by using an aqueous solution of a metal salt as in a conventionally known method instead of water. Metal salts include Group IA metals of the periodic table, I
Group IA metals, Group II B metals, manganese (for example, Japanese Patent Publication Sho 57
-7607), nitrates such as cobalt, chlorides, sulfates, acetates, phosphates, etc. are used, but salts of Group IA metals, Group IIA metals and zinc are preferred, and further,
Strong acid salts such as chlorides and sulfates are preferred.

Further, in the present invention, preferable results can be obtained by using a strong acid salt of zinc, especially an aqueous solution of zinc sulfate, instead of water.

Such zinc sulfate aqueous solution can be used at a concentration from 0.01% by weight to saturated solubility, but preferably 0.1 to 3
It is recommended to use 0% by weight.

Further, in the reaction system of the present invention, it is necessary that the reaction be performed in an aqueous solution in a neutral or acidic state. When the aqueous phase is made alkaline, the reaction rate is remarkably reduced, and it is difficult to obtain a realistic method for producing cycloolefins. Further, in order to make it acidic, ordinary acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid and phosphoric acid may be added. The pH of the aqueous solution thus introduced into the reaction system is 0.5 to 7 or less, preferably 2 to 6.5.

In the reaction system of the present invention, insoluble basic zinc sulfate must be present in the reaction solution. Therefore, although it depends on the amount of the insoluble basic zinc sulfate coexisting and the amount of the aqueous solution, it is preferable that the reaction system is carried out from a slightly alkaline to acidic state. More preferably, it is carried out in a neutral to acidic state.

The partial reduction reaction in the method of the present invention is usually carried out continuously or batchwise by a liquid phase suspension method, but can also be carried out by a stationary phase system. The reaction conditions are appropriately selected depending on the type and amount of the catalyst and additives used, but usually the hydrogen pressure is in the range of 1 to 200 Kg / cm ² G, preferably 10 to 100 Kg / cm ² G, The reaction temperature is room temperature to 250 ° C, preferably 100 to 200
It is in the range of ° C. The reaction time may be appropriately selected by determining a substantial target value of the selectivity and yield of the desired cyclohexenes and is appropriately selected, but is usually several seconds to several hours.

(Effects of the Invention) According to the present invention, cycloolephin can be obtained with a high selectivity and yield which have never been obtained, and a stable catalyst system is obtained, which is extremely valuable industrially.

(Examples) Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 A caustic soda aqueous solution was added to the zirconium oxychloride aqueous solution, the obtained white solid was filtered, washed with water until filtration of chlorine ions was no longer detected, and zirconium hydroxide was obtained.

Using this zirconium hydroxide as zirconium, 2.0 g, R
0.5 g of metal ruthenium catalyst (average crystallite size 50 Å) obtained by reducing u (OH) ₃ in water with pressurized hydrogen, 100 mg of the basic zinc salt shown in Table 1 as zinc, and 280 ml of water.
Was charged into an autoclave made of titanium with an internal volume of 1,
Replace with hydrogen under stirring and heat up to 150 ° C, then 140 ml of benzene
Pressurize, and keep hydrogen at a total pressure of 50 Kg / cm ² G,
The hydrogenation reaction was carried out at 50 ° C for a predetermined time. Table 1 shows the result of rapid cooling after the reaction and analysis of the organic layer by gas chromatography. The by-product was cyclohexane.

Further, in Examples 1 to 3, after the reaction was completed, the reactor was opened and observed, and in any case, the catalyst and zirconium hydroxide were well dispersed and no aggregation was observed.
No catalyst adhered to the titanium wall.

Comparative Example 1 A reaction was carried out for 30 minutes in the same manner as in Example 1 except that 0.05 g of a metal ruthenium catalyst (average crystallite size 50 Å) was used and zirconium hydroxide and a basic zinc salt were not used. The conversion of benzene is 66.1% and the selectivity of cyclohexene is 2.
The yield was 3% and the cyclohexene yield was 1.5%.

After the reaction was completed, the reactor was opened and observed. As a result, agglomeration of the catalyst was observed, and the catalyst adhered to the titanium wall surface.

Examples 4 to 13 2.0 g of hydroxide shown in Table 2 as metal, 0.5 g of metal ruthenium catalyst (average crystallite size 50Å), and basic zinc salt
30 mg of ZnSO ₄ .3Zn (OH) ₂ as zinc and 280 ml of a 10% zinc sulfate aqueous solution were charged into an autoclave made of titanium and having an internal volume of 1 and reacted in the same manner as in Example 1 for 60 minutes.
Table 2 shows the results.

However, in the case of hafnium hydroxide, hafnium oxychloride, and in the case of other hydroxides, chlorides were prepared by hydrolysis and washing with water.

Comparative Examples 2 and 3 The hydroxide shown in Table 3 was loaded with 1% of RuCl ₃ as Ru,
Ru reduction catalyst reduced with sodium borohydride
As a result, 0.05 g and 280 ml of a 10% zinc sulfate aqueous solution were charged into an autoclave made of titanium and having an inner volume of 1 and reacted in the same manner as in Example 1 for 30 minutes. The results are shown in Table 3.

Example 14 The same operation as in Example 4 was carried out except that 0.5 g of a reduced product of ruthenium containing zinc in advance (zinc content 5.6%, average crystallite size 65Å) was used as a catalyst, and the reaction was carried out for 60 minutes. . The benzene conversion was 57.2%, the cyclohexene selectivity was 81.8%, and the cyclohexene yield was 46.8%.

Example 15 The same catalyst as in Example 1 (average crystallite size 50Å) 1.5 g, hydroxide as metal 7.0 g, ZnSO ₄ .3Zn (OH) ₂ as zinc
0.6 g and 150 ml of 10% zinc sulfate aqueous solution were charged into an autoclave with an internal volume of 400 ml, the inner surface of which was Teflon coated, and the total pressure was adjusted to 50 kg / cm ² G with hydrogen and kept at 160 ° C for 200 hours with high speed stirring did. After the slurry was collected and washed, the average crystallite size of the catalytic metal ruthenium was measured by the X-ray diffraction method. As a result, it was 55 Å or less when any of the hydroxides was used, showing almost no change.

Next, using 1/3 of the slurry recovered to which zirconium hydroxide was added as a hydroxide and adjusting the liquid composition such as additives so that the same conditions as in Example 4 were carried out, the reaction was carried out. There was almost no change in speed or selectivity.

Comparative Example 4 When the same operation as in Example 15 was carried out except that hydroxide and ZnSO ₄ .3Zn (OH) ₂ were not used, the recovered catalyst metal ruthenium had an average crystallite size of 91Å. It was

When 1/3 of the recovered material was used to carry out the reaction by adjusting the liquid composition such as additives so that the conditions were the same as in Example 4, the reaction rate was reduced to about half of that in Example.

It is clear from Example 15 and Comparative Example 4 that the catalyst system in the method of the present invention is extremely stable.

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Claims (6)

[Claims] Claims: 1. When partially reducing monocyclic aromatic hydrocarbons with hydrogen in the coexistence of water, hydrogenation catalyst particles containing ruthenium metal having an average crystallite diameter of 200 Å or less as a main component are used, and the catalyst particles are used. Apart from Ti, Zr, Hf, Nb, Ta, Cr, Fe, Co, A
Characterized by adding a hydroxide of at least one metal selected from l, Ga and Si, and performing the reaction under neutral or acidic conditions in the presence of at least one solid basic zinc salt. And a method for producing a cycloolefin. 2. The method for producing a cycloolefin according to claim 1, wherein the hydrogenation catalyst is a reduced product of ruthenium containing zinc in advance. 3. The method for producing a cycloolefin according to claim 2, wherein the content of zinc in the hydrogenation catalyst is 0.1 to 50% by weight with respect to ruthenium as a main component. 4. The cyclone according to claim 1, wherein the amount of the hydroxide of the metal to be added is 1 × 10 ^{−4 to} 0.3 times the weight of water in terms of the amount of only the metal. A method for producing an olefin. 5. The cyclone according to claim 1, wherein the amount of the coexisting solid basic zinc salt is 1 × 10 ^{−4 to} I times the weight of the hydrogenation catalyst in terms of zinc only. A method for producing an olefin. 6. The method for producing a cycloolefin according to claim 1, wherein the reaction is carried out in the presence of an aqueous zinc sulfate solution.