JPH10101588A - Production of cycloolefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably producing cyclohexane useful as an intermediate raw material for various polymers or organic raw materials. SOLUTION: A catalyst containing particles consisting essentially of metallic ruthenium which is amorphous or has <=30Å average crystallite diameter and supported on a carrier is used as the catalyst when a partially reducing a monocycic aromatic hydrocarbon with hydrogen in the coexistence of water and at least one zinc compound under neutral or acidic conditions. Since the catalyst activities are extremely stable when producing the cyclohexane by partial reduction of benzene, extremely stable operation can be performed for industrial practicing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a corresponding cycloolefin, particularly cyclohexene, by partially reducing a monocyclic aromatic hydrocarbon. More specifically, the present invention provides an unprecedented method for obtaining cycloolefins with high productivity and stability. Cyclohexenes have high value as intermediate materials for organic chemical products, and are particularly useful as polyamide materials and lysine materials.

[0002]

2. Description of the Related Art As a method for producing cyclohexene, for example, (1) a method using a catalyst composition containing water, an alkali agent and a Group VIII element of the periodic table (Japanese Patent Publication No.
22850), (2) a method 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. 52-3933);
(3) Ruthenium catalyst and Group IA metal of the periodic table, I
A method in which the reaction is carried out in the presence of a neutral or acidic aqueous solution containing a salt of at least one cation selected from Group IA metals and manganese (JP-B-57-7607);
(4) converting a pre-reduced solid catalyst containing at least one of ruthenium and rhodium as a main component into at least one cation selected from the group consisting of Group IA metals, Group IIA metals, manganese, iron and zinc; A method in which a reaction is carried out in the presence of water using a solution previously treated with an aqueous solution containing a salt (Japanese Patent Publication No. 56-3852), (5) at least one selected from the group consisting of iron, cobalt, silver and copper A method in which at least one sulfate selected from the group consisting of lithium, cobalt, iron and zinc is reacted with water using a catalyst in which the above metal and ruthenium are supported on a barium sulfate carrier (Japanese Patent Application Laid-Open No. 61-122232
And (6) a method in which a metal ruthenium crystallite having an average crystallite diameter of 200 ° or less and / or its aggregated particles are used as a hydrogenation catalyst, and the reaction is carried out in the presence of water and at least one zinc compound ( JP-A-61-50
930), (7) a hydrogenation catalyst which is a reduced product of ruthenium preliminarily containing zinc and which has a zinc content of 0.1 to 50% by weight based on ruthenium; A method in which a reaction is carried out under acidic conditions in the presence of a water-soluble zinc compound and water (Japanese Patent Application Laid-Open No. 62-455).
No. 44) has been proposed.

[0003]

However, in these conventional methods, for example, in the above method (1), the reaction system is complicated or the conversion of the raw material is increased in order to improve the selectivity of cyclohexenes. And the reaction rate is significantly suppressed, and furthermore, a significant problem is expected in the corrosion resistance of the reactor. Therefore, in the methods (6) and (7), the selectivity and the yield are considerably improved. However, it is expected that aggregation of the particulate catalysts mainly composed of metal ruthenium occurs, and it is difficult to obtain a stable production method with the lapse of time. However, it is not necessarily economical because the productivity per unit weight of ruthenium, which is an expensive noble metal, decreases. This decrease in the activity of the catalyst over time is not only observed in the ruthenium metal system, but also in the supported catalyst system of (5), for example.

[0004]

Means for Solving the Problems The present inventors have overcome the problem of the decrease in the activity of the known art and have intensively studied a catalyst system having a high activity stability over time. It is. That is, the present invention relates to a process for partially reducing a monocyclic aromatic hydrocarbon with hydrogen under neutral or acidic conditions in the presence of water and at least one zinc compound, as an amorphous or less than 30 ° average crystallite. A method for producing a cycloolefin, characterized by using a catalyst in which particles mainly composed of metal ruthenium having a diameter are supported on a carrier.

Hereinafter, specific embodiments of the present invention will be described. The monocyclic aromatic hydrocarbon in the present invention refers to benzene, toluene, xylenes and lower alkylbenzenes having 4 or less carbon atoms. The purity of the raw material itself does not need to be particularly high, and may include cycloparaffin, lower paraffinic hydrocarbon, and the like. The catalyst used in the present invention is one in which particles composed mainly of metal ruthenium having an amorphous or average crystallite diameter of less than 30 ° are supported on a carrier.

In general, in a catalyst in which a metal is supported on a carrier, the effect of dispersing the metal by supporting the metal, the increase in the reaction amount per catalytic metal amount due to the increase in the reaction active site accompanying the effect, and further, under the reaction conditions. A so-called "physical" effect such as an increase in stability over time can be expected. In this respect, the same applies to the catalyst of the present invention, which is one of the important parts of the present invention. However, in general, amorphous or extremely fine particles of metal are known to have low stability and to be easily aggregated or crystallized.
It is surprising that the activity of the catalyst of the present invention has high stability over time, and it is considered that this suggests that the cause of the decrease in the activity of the present reaction system is other than the aggregation of metals.

The average crystallite diameter in the present invention is calculated by a general method, that is, by the Scherrer's equation from the spread of the diffraction line width obtained by the X-ray diffraction method. When used as an X-ray source,
It is calculated from the spread of the diffraction line derived from the metal ruthenium crystallite, which has a maximum at a diffraction angle (2θ) of around 44 degrees.
Generally, the lower limit of the crystallite diameter at which a diffraction peak is observed by X-ray diffraction is said to be 20 to 30 °, and the term “amorphous” refers to fine particles having an extremely small crystallite diameter,
I do not know if it is an amorphous state with low crystallinity,
In any case, the term “amorphous” as used herein means a state in which the diffraction peak of ruthenium metal is not observed by the X-ray diffraction method.

In the present invention, the catalyst may be prepared, for example, by dissolving the ruthenium compound in a solvent in which the ruthenium compound is dissolved to form a homogeneous solution, dispersing the desired carrier in the homogeneous solution, and then dissolving the ruthenium compound in the solvent. There is a method in which a reagent that changes to a compound that cannot be introduced is introduced, an insoluble ruthenium compound is deposited, and this is reduced. As the ruthenium compound, for example, a ruthenium halide, a nitrate, or various complexes may be used, and examples of the solvent include water, alcohol, and ethers.

The reduction of the catalyst includes a method of reducing the gas phase or liquid phase with hydrogen and a method of reducing the liquid phase with a reducing reagent such as formalin. In particular, as a method for supporting the amorphous or less than 30 ° metal ruthenium of the present invention, a method of reducing with hydrogen in the gas phase is preferable, for example, a method obtained by a dipping method using a ruthenium chloride solution or an evaporation to dryness method. Is reduced by hydrogen in the gas phase, in addition to ruthenium, the effect of chlorine adsorbed to a considerable extent inhibits the growth of crystallites during reduction, and the amorphous or less than 30 ° metal ruthenium is reduced. May be generated.

In addition, after such a catalyst preparation step or preparation, other metals such as zinc, chromium, manganese,
Cobalt, nickel, iron, copper, and the like may be partially added.
Although various carriers can be used, hydrates of metal compounds or oxides are preferably used. Specifically, for example, oxides or hydrates of zirconium, hafnium, titanium, niobium, tantalum, chromium, iron, cobalt, aluminum, gallium, and silicon. Of course, these composite oxides can also be used, and in particular, ZrO ₂ and HfO ₂ are preferred carriers. As other carriers, metal salts substantially insoluble and stable in the reaction system, and resins such as activated carbon and Teflon can also be used. The supported amount of the metal ruthenium is 0.1 to 20% by weight based on the carrier, and preferably 2 to 10% by weight.
% By weight.

In the present invention, it is necessary that at least one zinc compound is present in the reaction system as a cocatalyst. As a zinc compound, regardless of water solubility or poor water solubility,
Many are available. As the water-soluble zinc compound, a strong acid salt represented by zinc sulfate, zinc chloride, zinc nitrate and the like, a weak acid salt represented by zinc acetate and the like, and various ammonium complexes can be used. . The coexistence of a water-soluble zinc compound has the effect of improving the selectivity of cycloolefins. In the case of a strong acid salt, this effect is more remarkable, and it can be said that zinc sulfate is the most preferable. The strong acid salt of zinc does not need to be dissolved in the reaction system, but is usually used in an aqueous solution concentration range of 1 × 10 ⁻³ wt% to saturation solubility. When an aqueous solution of zinc sulfate is used, the concentration is 0.1%.
More preferably, it is used in a concentration range of 1 to 30% by weight. Further, a basic zinc salt which is a poorly water-soluble zinc compound may be allowed to coexist. Here, the basic zinc salt 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 another negative component.

More specifically, ZnSO ₄ .1 / 2ZnO, ZnSO ₄ .Zn
_{O · H 2 O (ZnSO 4} · Zn (OH) 2 or _{Zn 2 (OH) 2 SO 4} ), ZnSO 4
・ 3ZnO, 3H ₂ O (ZnSO ₄・ 3Zn (OH) ₂ ), ZnSO ₄・ 3ZnO ・ 6H
₂ O, ZnSO ₄ 3ZnO 7H ₂ O, ZnSO ₄ 3ZnO 8H ₂ O, ZnSO ₄
・ Basic zinc sulfate represented by 4ZnO ・ 4H ₂ O (ZnSO ₄・ 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
· 4H 2 O, 5ZnO · 2ZnCl} 2 · 26H 2 O, 5ZnO · 5ZnCl 2 · 8H 2 O,
3ZnO ・ ZnCl ₂・ 2H ₂ O, 4H ₂ O, 3H ₂ O, 5H ₂ O, 8H ₂ O, 4ZnO ・ ZnCl
_{2 · 4H 2 O, 6H 2} O, 11H 2 O, 9ZnO · 2ZnCl 2 · 12H 2 O, 5ZnO ·
ZnCl ₂・ 6H ₂ O, 8H ₂ O, 29H ₂ O, 11ZnO ・ 2ZnCl ₂ , 6ZnO ・ Zn
_{Cl 2 · 6H 2 O, 10H} 2 O, 8ZnO · ZnCl 2 · 10H 2 O, 9ZnO · ZnCl
_{2 · 3H 2 O, 14H 2} O, ZnBr 2 · 4ZnO · nH 2 0 (n is 10,13,29
_{), ZnBr 2 · 5ZnO · 6H} 2 O, ZnBr 2 · 6ZnO · 35H 2 O, ZnI 2
_{· 4Zn (OH) 2, ZnI} 2 · 5ZnO · 11H 2 O, ZnI 2 · 9ZnO · 24H 2 O
Basic zinc halide represented by 8ZnO ・ N ₂ O ₅・
_{4H 2 O, 4ZnO · N 2} O 5 · 4H 2 O, 5ZnO · N 2 0 5 · 5H 2 O and 6H
₂ O, basic zinc nitrate represented by like _{5ZnO · N 2 O 5 · 5H} 2 O, further, include basic zinc acetate, basic zinc sulfate, basic zinc chloride is preferably used, basic Zinc sulfate is particularly preferred.

When such a basic zinc salt is used, the reaction is carried out in the presence of 1 × 10 ^-4 to 1 times by weight, preferably 1 × 10 ^{-3 to} 0.5 times by weight of zinc relative to the hydrogenation catalyst. . In particular, sharing zinc sulfate and basic zinc sulfate is advantageous in increasing the selectivity and yield of the reaction. In the present invention, the presence of water is essential. 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 based on a generally used monocyclic aromatic hydrocarbon. It is preferable that the organic liquid phase to be formed and the liquid phase containing water form two phases, and the coexistence of a very small amount of water or the coexistence of a very large amount of water so as to be a homogeneous phase under the reaction conditions The effect is reduced, and if the amount of water is too large, the size of the reactor needs to be increased.

In using water, various metal salt aqueous solutions, for example, an aqueous solution of a strong acid salt of a Group IA metal or a Group IIA metal may be used in a known manner. In the present invention, the existing aqueous phase is maintained under neutral or acidic conditions to carry out the reaction. When the aqueous phase becomes alkaline, the reaction rate is particularly remarkably reduced, which is not preferable. Preferably, the pH of the aqueous phase is between 0.5 and less than 7, more preferably between 2 and 6.5.

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 method. The reaction conditions are appropriately selected depending on the type and amount of the catalyst and additives to be used, and usually, the hydrogen pressure is 1 to 200 kg / cm ² G, preferably 10 to 1 kg / cm ² G.
00 kg / cm ² G, and the reaction temperature is from room temperature to 250
° C, preferably in the range of 100-200 ° C. Also,
The reaction time may be selected as appropriate, by setting a substantial target value of the selectivity and yield of the target cyclohexene, and is not particularly limited, but is usually several seconds to several hours.

[0016]

The present invention will be described below with reference to examples. It should be noted that the present invention is not limited to these examples unless it exceeds the gist.

EXAMPLE 1 0.52 g of RuCl ₃ .3H ₂ O was dissolved in 300 ml of water to prepare a homogeneous ruthenium chloride solution. 10 g of hafnium oxide powder was added thereto to prepare a dispersion, which was charged into a rotary evaporator, and water was evaporated to dryness while maintaining the temperature at 60 ° C. under reduced pressure. Next, this catalyst was reduced in a hydrogen stream at 160 ° C. for 3 hours to obtain a 2% Ru / HfO ₂ catalyst. Observation of the resulting catalyst by X-ray diffraction revealed that the average crystallite size of the metal ruthenium was much smaller than 30 ° and could not be calculated.

Next, using this catalyst, a partial reduction reaction of benzene was carried out under the following conditions. 2.0 g catalyst, ZnSO ₄
・ 50 g of 7H ₂ O and 280 ml of water were charged into an autoclave having an inner surface of 1 liter and coated with Teflon, and the inside of the autoclave was replaced with nitrogen and then with hydrogen.
40 ml of hydrogen was injected together with hydrogen to a total pressure of 50 kg / cm ² G, and a partial reduction reaction of benzene was carried out with vigorous stirring while maintaining the reaction temperature at 145 ° C., and a part of the content was withdrawn with time to remove the oil phase. Analyzed by gas chromatography. As a result, the conversion rate of benzene, the selectivity of cyclohexene, and the yield of cyclohexene were 40.5% in the order of 30 minutes,
38.2%, 15.5%, 70.4% in 60 minutes, 21.
2% and 14.9%.

[0018]

EXAMPLE ₂ 0.52 g of RuCl ₃ .3H ₂ O was dissolved in 300 ml of water, 10 g of Al ₂ O ₃ powder was added thereto, and 1 g of the powder was stirred.
After holding for a long time, most of ruthenium was adsorbed.
After washing with water, ruthenium was reduced in the same manner as in Example 1 to obtain a 2% Ru / Al ₂ O ₃ supported catalyst. According to the observation by X-ray diffraction, the average crystallite diameter of the metal ruthenium was so small that it could not be calculated. Next, a partial reduction reaction of benzene was performed in the same manner as in Example 1 except that 1.5 g of this catalyst was used. As a result, the conversion rate of benzene, the selectivity of cyclohexene, and the yield of cyclohexene were 37 37 .0
%, 26.8%, 9.9%, 71.6% for 60 minutes, 1
7.3% and 12.4%.

[0019]

Example 3 Example 1 except that benzene was not charged.
The catalyst slurry was stewed under hydrogen for 200 hours under the same charge composition and conditions. After that, temporarily increase the pressure to 3
The pressure was reduced to 0 kg / cm ² G, 140 ml of benzene was injected together with hydrogen, the total pressure was again adjusted to 50 kg / cm ² G, and the reaction temperature was reduced to 14 kg / cm ² G.
A partial reduction reaction of benzene was performed while maintaining the temperature at 5 ° C. As a result, the benzene conversion rate, cyclohexene selectivity, and cyclohexene yield were 40%, 38
%, 15.2%, 70% in 60 minutes, 21.5%, 15.
1%. This indicates that the catalyst of the present invention is extremely stable to the boiling treatment in the same hydrogen as the reaction conditions. Further, the catalyst after the reaction was taken out, and the ruthenium crystallite diameter was measured by X-ray diffraction. The value was still extremely smaller than 30 ° and nearly amorphous. This result indicates that the catalyst of the present invention hardly causes ruthenium aggregation under the reaction conditions.

[0020]

Comparative Example 1 1.3 g of RuCl ₃ .3H ₂ O was dissolved in 300 ml of water to obtain a homogeneous ruthenium chloride solution. This put a hafnium oxide powder 10 g, it is dispersed under strong stirring, followed by addition of aqueous NaOH 30ml of 1N, continuously stirred for 2 h, mainly deposited insoluble ruthenium compounds consisting of Ru (OH) ₃ in hafnium oxide Was. This was washed several times with water, then dispersed again in 500 ml of water, charged into a 1 liter autoclave having an inner surface coated with Teflon, and heated at 160 ° C. and hydrogen to 60 kg / cm ² G at 24 kg / cm ² G.
Time reduction was performed to obtain a 5% Ru / HfO ₂ supported catalyst. The average crystallite size of metal ruthenium in this catalyst was about 58 °.

Using 1.5 g of this catalyst, a partial reduction reaction of benzene was carried out under exactly the same conditions as in Example 1. As a result, the benzene conversion rate, cyclohexene selectivity, and cyclohexene yield were 37.1%, 7
9.6%, 29.5%, 63.3%, 60.
0% and 44.3%. Using 1.5 g of this catalyst, a stew treatment under hydrogen and a reaction evaluation were carried out under exactly the same conditions as in Example 3. As a result, the conversion rate of benzene, the selectivity of cyclohexene, and the yield of cyclohexene were 30%, 80%, 24% in a reaction time of 30 minutes, and 51%, 7% in 60 minutes.
4% and 37.7%. The average crystallite size of the metal ruthenium of the catalyst after the reaction was 80 °, indicating that the agglomeration had progressed.

[0022]

According to the present invention, since the catalytic activity is extremely stable when cyclohexene is produced by partial reduction of benzene, an extremely stable operation is possible in industrial practice.

Claims (3)

[Claims] When a monocyclic aromatic hydrocarbon is partially reduced with hydrogen under neutral or acidic conditions in the presence of water and at least one zinc compound, the catalyst is amorphous or has an average crystallite size of less than 30 °. A method for producing a cycloolefin, comprising using a catalyst in which particles containing metal ruthenium as a main component having the above are supported on a carrier. 2. The method according to claim 1, wherein the carrier is ZrO ₂ or HfO _2.
The method described in. 3. The method according to claim 1, wherein the supported amount of the metal ruthenium is 2 to 10% by weight with respect to the carrier.