JPH0825919B2 - Method for producing cycloolefin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for partially reducing a monocyclic aromatic hydrocarbon to produce corresponding cycloolefins, particularly cyclohexenes. More specifically, the present invention provides a method for obtaining cycloolephins stably with a high selectivity and a high yield, which has never been seen in the production method.

Cyclohexenes are expensive 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) Ruthenium catalyst and periodic table A method of carrying out the reaction in the presence of a neutral or acidic aqueous solution containing a salt of at least one cation selected from Group IA metals, Group IIA metals and manganese (Japanese Patent Publication No.
57-7607), (4) a pre-reduced solid catalyst containing at least one of ruthenium and rhodium as a main component is selected from the group consisting of Group IA metals, Group II A metals, manganese, iron and zinc of the periodic table. A method of carrying out a reaction in the presence of water using a pretreated solution containing an aqueous solution of at least one selected cation salt (Japanese Patent Publication No. 56-3852);
(5) selected from the group consisting of lithium, cobalt, iron and zinc using a catalyst in which at least one metal selected from the group consisting of iron, cobalt, silver and copper and ruthenium are supported on a barium sulfate carrier. And a method of carrying out the reaction in the presence of one or more metal sulfates and water (JP-A-61-
122232), (6) Using a metal ruthenium crystallite having an average crystallite diameter of 200 Å or less and / or its agglomerated particles as a hydrogenation catalyst, the reaction is carried out in the presence of water and at least one zinc compound. Method (JP-A-61-
No. 50930), (7) A reduction product of ruthenium containing zinc in advance as a hydrogenation catalyst, the catalyst having a zinc content of 0.1 to 50% by weight relative to ruthenium is used, and at least one aqueous solution is used. Of reacting under acidic conditions in the presence of a water-soluble zinc compound and water (JP-A-62-45544)
No. gazette) is proposed.

(Problems to be Solved by the Invention) However, in these conventionally known methods, for example, in the above method (1), the reaction system is complicated,
It is not practical such that the conversion rate or reaction rate of the raw material is remarkably suppressed in order to improve the selectivity of cyclohexenes, and further a significant problem is expected in the corrosion resistance of the reaction device.
The methods (2) to (4) are difficult to put into practical use unless they are dramatically improved in terms of selectivity and yield. In the method (5), the yield of cyclohexenes is as high as 30 to 40%, and although it is a considerably improved method, the value is obtained under a high conversion rate, and the selectivity of cyclohexenes is high. It is around 50% at most, and it is difficult to say that it is advantageous from an economic point of view in the present situation that cyclohexanes, which are by-products, are already industrially manufactured at low cost. On the other hand, in the methods (6) and (7),
Significant improvements have been made in selectivity and yield,
Since the fine particles mainly composed of metal ruthenium are used by themselves, it is expected that the particulate catalysts in the reaction system will aggregate with each other, and it will be difficult to obtain a stable production method over time. Due to the reduction of the reaction active sites, the productivity per unit weight of ruthenium, which is an expensive precious metal, becomes low, which is not always economical.

(Means for Solving the Problems) The inventors of the present invention have overcome the problems of the above-mentioned known techniques, and have earnestly studied a catalyst system having high selectivity, high yield and high productivity. It has arrived.

That is, the present invention is that when a monocyclic aromatic hydrocarbon is partially reduced with hydrogen under the coexistence of water and at least one zinc compound under a neutral or acidic condition, an average crystallite diameter of 30 to 200Å is used as a catalyst. A method for producing cycloolefin, which comprises using a catalyst in which particles having a metal ruthenium as a main component and having metal are supported on a carrier.

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

The monocyclic aromatic hydrocarbon in the present invention is 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 it does not matter even if it contains cycloparaffin, a lower paraffin hydrocarbon, or the like.

The catalyst used in the present invention is one in which particles having a metal ruthenium as a main component and having an average crystallite diameter of 30 to 200Å are supported on a carrier.

Generally, in a catalyst in which a metal is supported on a carrier, the dispersion effect of the metal due to the supporting, and the increase in the reaction amount per catalyst metal amount due to the increase in the reaction active points accompanying this,
Furthermore, so-called “physical” effects such as an increase in stability over time under reaction conditions can be expected, and in this respect, the same applies to the catalyst of the present invention.
It is one of the important parts of the present invention.

However, on the other hand, according to the study by the present inventor, even if the carrier is the same, depending on the state of the supported metal (in the present invention, ruthenium), the influence on the partial reduction reaction, particularly the selectivity and yield of cyclohexenes, It has been found that the influences given are remarkably different, and the supported metal state advantageous for the partial reduction reaction is 30 to 200 Å, preferably 40 to 100 Å, more preferably 40 to 80 Å mainly composed of metallic ruthenium having a crystallite diameter. We have come to the conclusion that it is important to be particles. Here, the average crystallite size is calculated by a general method, that is,
From the spread of the diffraction line width obtained by the X-ray diffraction method, Sche
It is calculated by the formula of rrer, specifically, Ku
When Kα ray is used as an X-ray source, the diffraction angle (2θ)
Calculated from the broadening of the diffraction line originating from the metal ruthenium crystallite, which has a maximum around 44 °.

By providing the supported metal state as described above, it is possible to obtain a catalyst which has the "physical" effect of the above-mentioned carrier catalyst and which is extremely advantageous in the selectivity and yield of the partial reduction reaction. If the average crystallite size is too small, or if metal ruthenium is present in an amorphous state that does not take the form of crystallites, the selectivity of cyclohexenes will be impaired, which is impractical. The reaction amount per amount, that is, the productivity is lowered, and the selectivity is lowered in some cases, so that a part of the advantage as the carrier catalyst is lost, which is not preferable.

As a method for adjusting the catalyst in the method of the present invention, for example, a ruthenium compound is dissolved in a solvent to dissolve the ruthenium compound into a uniform solution, after which a desired carrier is dispersed,
There is a method in which a reagent for converting a ruthenium compound into a compound insoluble in the solvent is introduced to deposit an insoluble ruthenium compound and reduce the insoluble ruthenium compound. As the ruthenium compound, for example, a ruthenium halide, a nitrate, or various complexes may be used, and the solvent may be water, alcohol, ethers, or the like. In particular, a method of using an aqueous ruthenium chloride solution, using an alkali as an insolubilizing reagent, and depositing it mainly on the carrier in the form of ruthenium hydroxide, followed by reduction is such that the raw materials are easily available and the handling is easy. It can be said that this is the preferred method.

Examples of the reduction of the catalyst include a method of reducing with hydrogen in a gas phase or a liquid phase, a method of reducing with a reducing reagent such as formalin in a liquid phase, and a method of reducing with hydrogen in water is preferably used. When reducing with hydrogen in water, it is desirable to carry out at a hydrogen partial pressure of 1 to 200 kg / cm ² G under conditions of 100 to 250 ° C. Further, other metals such as zinc, chromium, manganese, cobalt, nickel, iron and copper may be partially added at or after the preparation stage of such a catalyst.

In the conventional method, which is said to be generally used, for example, in the method of reducing the one obtained by the immersion method using a ruthenium chloride solution or the evaporation dryness method with hydrogen in the gas phase, there are few other than ruthenium. Because of the effect of chlorine adsorbed, the growth of crystallites at the time of reduction is hindered, and the ruthenium metal is significantly sintered depending on the reduction conditions. It is not the preferred method. In addition, the reduction using formalin may be difficult to proceed sufficiently.

Although various carriers can be used, a metal oxide or a hydrate of an oxide is preferably used.
Specifically, for example, zirconium, hafnium, titanium, niobium, tantalum, chromium, iron, cobalt, aluminum, gallium, and oxides of silicon or hydrates of oxides, and the like. Of course, these complex oxides can also be used. In particular, ZrO ₂ and HfO ₂ give favorable results in terms of selectivity and yield of cyclohexenes. As the other carrier, a metal salt that is substantially insoluble and stable in the reaction system, a resin such as activated carbon, or Teflon can be used.

The amount of ruthenium metal supported is 0.1 to 20% by weight, preferably 2 to 10% by weight, based on the carrier.

In the present invention, it is necessary that at least one zinc compound is present in the reaction system as a cocatalyst. Many zinc compounds can be used regardless of whether they are water-soluble or poorly water-soluble. As the water-soluble zinc compound, strong sulfuric acid typified by zinc sulfate, zinc chloride, zinc nitrate, weak acid salts typified by zinc acetate, and various ammonium complexes can be used, but an aqueous solution of strong acid salt is particularly preferable. used. The coexistence of the water-soluble zinc compound has an effect of improving the selectivity of cycloolefins, and in the case of a strong acid salt, this effect is more remarkable, and zinc sulfate is particularly preferable. It is not necessary that all of the strong salt of zinc is dissolved in the reaction system, but it is usually used in the concentration range from 1 × 10 ⁻³ wt% to saturated solubility as the concentration of the aqueous solution. When using a zinc sulfate aqueous solution, it is more preferable to use it in a concentration range of 0.1 to 30% by weight.

Further, a basic zinc salt which is a sparingly water-soluble zinc compound may be allowed to coexist.

Here, the basic zinc salt refers to a salt of zinc containing both a conjugate base residue of various acids and a hydroxyl group or oxygen atom which is regarded as a negative component other than this.

Specifically, ZnSO ₄・ 1 / 2ZnO, ZnSO ₄・ ZnO ・ H ₂ O (ZnSO 4
₄・ Zn (OH) ₂ or Zn ₂ (OH ₂ ) SO ₄ ), ZnSO ₄・ 3ZnO, Z
nSO ₄ / 3ZnO / 3H ₂ O (ZnSO ₄ / 3Zn (OH) ₂ ), ZnSO ₄ / 3Zn
O ・ 6H ₂ O, ZnSO ₄ / 3ZnO / 7H ₂ O, ZnSO ₄ / 3ZnO / 8H ₂ O, ZnS
Basic zinc sulphate typified by O ₄・ 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・ 4
H 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・ 4
H 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 ・ ZnCl ₂・ 6H ₂ O,
10H ₂ O, 8ZnO ・ ZnCl ₂・ 10H ₂ O, 9ZnO ・ ZnCl ₂・ 3H ₂ O, 14H
₂ O, ZnBr ₂ · 4 ZnO · 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 , basic zinc halides such as ZnI ₂ , 5ZnO, 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, 5ZnO ・ N ₂ O ₅・ 5H ₂ O and 6H ₂ O, 5ZnO ・ N ₂
O ₅ · 5H ₂ O basic zinc nitrate represented by like, and further,
There are basic zinc acetate and the like, and basic zinc sulfate and basic zinc chloride are preferably used, and basic zinc sulfate is particularly preferable.

When such a basic zinc salt is used, the hydrogenation catalyst contains 1 × 10 ⁻⁴ to 1 times the weight of zinc, preferably 1 × 10 ^4.
The reaction is carried out in the coexistence of ^{-3 to} 0.5 times by weight. In particular, sharing zinc sulfate with basic zinc sulfate is advantageous in increasing the selectivity and yield of the reaction.

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 preferable 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 coexistence of an extremely large amount of water so as to form a homogeneous phase under reaction conditions. Reduces the effect, and too much water also necessitates a larger reactor, so 0.5 is practical.
It is desirable to coexist with about 20 times by weight.

In addition, when using water, various metal salt aqueous solutions such as known methods, for example, Group IA metal of the periodic table or
A strong aqueous solution of a Group IIA metal salt may be used in combination.

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 lowered, which is not preferable. Preferably the pH of the aqueous phase is 0.5 to less than 7, more preferably 2 to 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 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 ° C
Range. The reaction time may be appropriately selected by setting a substantial target value for the selectivity and yield of the desired cyclohexene, and is not particularly limited, but is usually several seconds to several hours.

(Effects of the Invention) According to the present invention, cycloolefin can be obtained with high selectivity and yield, and a stable catalyst system can be obtained.
It 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.

Example 1 <Preparation of catalyst> RuCl ₃ 3H ₂ O 1.3 g was dissolved in 300 ml of water to prepare a ruthenium chloride homogeneous solution. Put 10 g of commercially available zirconium oxide powder into this, disperse under strong stirring, and then add 1N NaO.
Add 30 ml of H aqueous solution and continue stirring for 2 hours.
An insoluble ruthenium compound consisting of u (OH) ₃ was deposited on zirconium oxide. After washing this with water several times,
Disperse it again in 500 ml of water, and charge it in the autoclave 1 with Teflon coating on the inner surface.
Reduced to 60 kg / cm ² G with hydrogen at ℃ for 24 hours,
% / ZrO ₂ supported catalyst was obtained. When this was analyzed by X-ray diffraction, the average crystallite diameter of metallic ruthenium was about 53Å. Also, for confirmation, the catalyst was dried and observed with a transmission electron microscope at a magnification of about 120,000.
It was clearly observed that the metal ruthenium particles (crystallites) of Å were supported on the carrier alone or in a state where they were partially aggregated. Most of the individual crystallites were identifiable even in the agglomerated part.

<Partial reduction reaction> Next, 1.5 g of the catalyst obtained above, 50 g of ZnSO ₄ .7H ₂ O, 280 of water
1 ml volume with Teflon coating on the inner surface
The autoclave was charged with nitrogen,
Then, after replacing with hydrogen, the temperature was raised to 145 ° C with stirring.
Then, pressurize 140 ml of benzene together with hydrogen to a total pressure of 5
A partial reduction reaction of benzene was carried out under strong stirring while maintaining the reaction temperature at 145 ° C. at 0 kg / cm ² G, a part of the content was extracted with time, and the oil phase was analyzed by gas chromatography. As a result, at a reaction time of 30 minutes, a benzene conversion rate of 35.0%, a cyclohexene selectivity of 81.2%, a cyclohexene yield of 27.4%, and a reaction time of 60 minutes were 61.0% and 70.5%, respectively.
% And 43.0%. The by-product was cyclohexane. It is obvious that this is far superior to cyclohexene selectivity and yield in comparison with (1) to (5) described in the prior art. On the other hand, the benzene reaction amount per unit weight of ruthenium in this example is based on the time for obtaining a benzene conversion rate of 60%,
Approximately 1,020 g / g-ruthenium · hour, which is comparable to cyclohexene selectivity and yield described in the above-mentioned conventional techniques (6) and (7), and the activity is greatly improved. Obviously, it is also more practical when the stability of the supported catalyst is taken into consideration.

Example 2 A catalyst was prepared and reacted in the same manner as in Example 1 except that hafnium oxide powder was used instead of zirconium oxide. Benzene conversion, cyclohexene selectivity, and cyclohexene yield were 37.1% and 7
9.6%, 29.5%, 63.3%, 70.0%, 44.3% after 60 minutes.

The average crystallite diameter of the metal ruthenium in this catalyst is about
It was 58Å.

Examples 3 to 7 The reaction was carried out in the same manner as in Example 1 except that the amount of ruthenium supported at the time of catalyst preparation and the supported reduction conditions were variously changed to change the amount of catalyst used in the partial reduction reaction.
Table 1 shows the results.

Comparative Example 1 0.52 g of RuCl ₃ .3H ₂ O was dissolved in 300 ml of water to give a uniform solution of ruthenium chloride. To this was added 10 g of the same hafnium oxide powder as used in Examples 2 and 7 to give a dispersion liquid, which was placed in 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 steam flow at 160 ° C. for 3 hours to obtain a Ru2% / HfO ₂ catalyst. This preparation method is a commonly used method. When the obtained catalyst was observed by X-ray diffraction, the average crystallite diameter of ruthenium metal was as small as 30 Å, and it was almost impossible to calculate.

Then, a partial reduction reaction of benzene was carried out in the same manner as in Example 7 except that 2.0 g of this catalyst was used. The benzene conversion rate, cyclohexene selectivity and cyclohexene yield were determined in order at a reaction time of 30 minutes. 40.5%, 38.2%, 15.5%, 60
Minutes were 70.4%, 21.2% and 14.9%.

Comparative Example 2 0.52 g of RuCl ₃ .3H ₂ O was dissolved in 300 ml of water, and Al ₂ O was added to the solution.
_When 10 g of ₃ powders were put and kept for 1 hour under stirring, most of ruthenium was adsorbed. After washing this with water, ruthenium was reduced in the same manner as in Comparative Example 1, and Ru2
% / Al ₂ O ₃ supported catalyst was obtained. In observation by X-ray diffraction,
The average crystallite size of ruthenium metal was too small to be calculated.

Next, when a partial reduction reaction of benzene was carried out in the same manner as in Example 1 except that 1.5 g of this catalyst was used, the benzene conversion rate, cyclohexene selectivity, and cyclohexene yield were
Reaction time 30 minutes, 37.0%, 26.8%, 9.9%, 60 minutes 7
It was 1.6%, 17.3% and 12.4%.

Comparative Example 3 2% Ru / HfO ₂ was prepared by the same procedure except that the reducing conditions in Comparative Example 1 in a hydrogen stream were changed to 500 ° C. for 4 hours. When the obtained catalyst was observed by X-ray diffraction, the average crystallite size of metallic ruthenium was 500Å.

Since this catalyst has high activity, the catalytic amount was set to 1 g and the partial reduction reaction of benzene was carried out in the same manner as in Example 7. As a result, the conversion of benzene was 50%, the selectivity for cyclohexene was 40%, and the yield was 20% after 30 minutes of reaction. Also,
After 60 minutes of reaction time, the benzene conversion was 75%, the cyclohexene selectivity was 25%, and the cyclohexene yield was 18.8%.

Example 8 A partial reduction reaction of benzene was carried out in the same manner as in Example 1 except that 3.0 g of the same catalyst as in Example 1 was used and 30 mg of basic zinc sulfate ZnSO ₄ .4Zn (OH) ₂ was further added as a cocatalyst. As a result, the benzene conversion rate, cyclohexene selectivity, and cyclohexene yield were 37.5% in order at a reaction time of 30 minutes.
%, 82.5%, 30.9%, 62.4%, 75.8%, 47.3% in 60 minutes.

Claims (3)

[Claims] 1. A catalyst for the partial reduction of monocyclic aromatic hydrocarbons with hydrogen in the presence of water and at least one zinc compound under neutral or acidic conditions.
A method for producing cycloolefin, which comprises using a catalyst in which particles having a mean crystallite diameter of Å and having ruthenium metal as a main component are supported on a carrier. 2. The method according to claim 1, wherein the carrier is ZrO ₂ or HfO ₂ . 3. The amount of metal ruthenium supported is 2 to the carrier.
A method according to claim 1 which is 10% by weight.