JPH0216736B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention partially reduces monocyclic aromatic hydrocarbons,
The present invention relates to a method for producing corresponding cycloolefins, particularly cyclohexene, with high selectivity and high yield. Cyclohexenes have high value as intermediate raw materials for organic chemical industrial products, and are especially valuable as raw materials for polyamides,
It is important as a raw material for lysine. (Prior art) As a method for producing such cyclohexanes,
For example, (1) a method using a catalyst composition containing water, an alkaline agent, and a group element of the periodic table (Special Publication No. 56
(2) A method using a ruthenium catalyst supported on an oxide of nickel, cobalt, chromium, titanium or zirconium and using alcohol or ester as an additive (Japanese Patent Publication No. 52-3933
(3) A method using a ruthenium catalyst containing copper, silver, cobalt or potassium, water and a phosphate compound (Japanese Patent Publication No. 56-4536),
(4) Ruthenium catalyst and group A metals of the periodic table,
A method of carrying out a reaction in the presence of a neutral or acidic aqueous solution containing a salt of at least one cation selected from Group A metals, manganese, zinc and ammonia (Japanese Unexamined Patent Publication No. 142536/1983), (5) A solid catalyst containing at least one of ruthenium and rhodium as a main component, a group A metal of the periodic table, a group A metal, manganese,
A method of carrying out a reaction in the presence of water using an aqueous solution containing a salt of at least one cation selected from the group consisting of iron and zinc (Japanese Patent Application Laid-Open No. 1982-98243), ( 6) Using a ruthenium catalyst,
A method has been proposed in which the reaction is carried out by adding at least one of zinc oxide and zinc hydroxide as an activating component to the reaction system (Japanese Patent Laid-Open Publication No. 184138/1983). (Problems to be solved by the invention) However, in these conventionally known methods,
In order to increase the selectivity of the target cyclohexene, it is necessary to significantly suppress the conversion rate of the raw material, and the reaction rate is extremely low.In general, the yield and productivity of cyclohexene are low, making it difficult to use practical cyclohexene. Currently, there is no standard manufacturing method for this. (Means for Solving the Problems) In order to solve the problems, the present inventors, in order to improve the selectivity and yield of cyclohexene,
The present invention was arrived at as a result of intensive studies on hydrogenation catalysts for partial reduction of monocyclic aromatic hydrocarbons. That is, it is a metal ruthenium containing 0.1 to 50% by weight of ruthenium of zinc obtained by reducing a ruthenium compound containing a zinc compound in advance as a hydrogenation catalyst,
and the average crystallite diameter of the metal ruthenium is 200 Å
By using the following unsupported catalyst and carrying out the reaction in the liquid phase under acidic conditions in the coexistence of water and at least one water-soluble zinc compound, we have achieved unprecedentedly excellent selectivity and yield. They discovered that cyclohexanes could be obtained at a relatively low temperature. Hereinafter, specific embodiments of the present invention will be described. The monocyclic aromatic hydrocarbon that is the raw material of the present invention is
Refers to benzene, toluene, xylenes, and lower alkylbenzenes. The hydrogenation catalyst in the present invention is a reduced product of ruthenium containing zinc in advance. More specifically, such a catalyst is a reduced product obtained by pre-containing a zinc compound in a valuable ruthenium compound and then reducing it, in which 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 complexes, hydroxides, and oxides.
A compound of valent or tetravalent ruthenium is preferred because it is easily available and easy to handle. Further, a wide range of zinc compounds can be used, including salts such as chlorides, nitrates, and sulfates, complexes such as ammine complexes, hydroxides, and oxides. It is not necessarily clear why such a catalyst is effective as a catalyst for the production of cycloolefins, but in the process in which valuable ruthenium compounds are reduced to the metallic state, coexisting zinc compounds are used to form cycloolefins. It can be considered that active points that are advantageous to the above are appearing or increasing. The zinc content in the catalyst of the present invention is adjusted to 0.1 to 50% by weight, preferably 2 to 20% by weight, based on ruthenium, which is the main component. Therefore,
The main component of the catalyst is ruthenium, and zinc is not a carrier. Furthermore, in JP-A No. 51-98243, there is a memory that it is better to use a ruthenium catalyst treated with an aqueous solution containing a salt of a zinc cation, but there is no memory as to whether zinc is contained or not. It is also clear that all catalyst treatments are performed on reduced catalysts, which are fundamentally different from the catalysts used in the present invention. The smaller the average crystallite diameter of the reduced product, the more useful the present invention becomes. Specifically, it is desirable that the average crystallite diameter of the reduced product be 200 Å or less, preferably 100 Å or less, in order to improve the selectivity of cycloolefin. The valuable ruthenium compound containing zinc in the present invention may be obtained as a solid by a general coprecipitation method using a mixed solution of zinc and ruthenium compounds, or may be obtained in the form of a homogeneous solution. It's okay. The catalyst of the present invention is prepared by reducing a valuable ruthenium compound containing zinc until ruthenium becomes a metal state. As a reduction method, a general ruthenium reduction method can be applied. can. For example, reduction with hydrogen in the gas phase, hydrogen or a suitable chemical reducing agent in the liquid phase, e.g.
A method of reduction using NaBH ₄ or formalin is preferably applied, and a method of reduction using hydrogen in the gas phase or liquid phase is particularly preferable. In the method of reduction with hydrogen in the gas phase, in order to avoid an increase in the crystallite size, it is recommended to avoid extremely high temperatures or dilute the hydrogen with another inert gas. Further, when the reduction is carried out in a liquid phase, it may be carried out by dispersing a solid valuable ruthenium compound containing zinc in water or alcohol, or it may be carried out in the form of a homogeneous solution. At this time, stirring, heating, etc. may be carried out appropriately in order to make the reduction proceed better. Furthermore, instead of water, an aqueous alkaline solution or an appropriate aqueous metal salt solution, such as an aqueous alkali metal salt solution, may be used. Here, the crystallite diameter of the catalyst is calculated by a general method, that is, from the spread of the diffraction line width obtained by the X-ray diffraction method, using the Scherrer formula. Specifically, when CuKα rays are used as an X-ray source, it is calculated from the spread of diffraction lines that have a maximum around 44° in terms of diffraction angle (2θ). As mentioned above, the average crystallite diameter is 200 Å or less, preferably 100 Å or less, and the lower limit is larger than the theoretical crystal unit, and is realistically 10 Å or more. In the present invention, the coexistence of water is necessary. The amount of water varies depending on the reaction type, but it is 0.01 to 0.01 for commonly used monocyclic aromatic hydrocarbons.
Can coexist 100 times by weight. However, under the reaction conditions, it is preferable that two phases be formed: an organic liquid phase mainly composed of raw materials and products, and a liquid phase containing water, and a very small amount of water should be formed to form a homogeneous phase under the reaction conditions. The coexistence of water, or the coexistence of an extremely large amount of water, will reduce the effectiveness, and if the amount of water is too large, it will be necessary to enlarge the reactor. It is desirable that they coexist. The present invention requires the presence of at least one water-soluble zinc compound in addition to the hydrogenation catalyst and water. Here, water-soluble zinc compounds include various salts, such as weak acid salts such as carbonates and acetates, hydrochlorides,
Strong acid salts such as nitrates and sulfates are used. Zinc oxide and zinc hydroxide are also effectively used.
The amount used is 1× relative to the water present during the reaction.
10 ⁻⁵ to 0.3 times by weight, preferably 1×10 ⁻⁴ to 0.1 times by weight. It is not particularly necessary that the entire amount of the zinc compound used during the reaction be dissolved. For example, Japanese Patent Application Laid-Open No. 142536/1984 describes a zinc compound that coexists in water, but a catalyst supporting ruthenium or rhodium is used, and the present invention is different from the catalyst. The difference itself and the lower the selectivity of cycloolefin, the greater the difference from the present invention. Further, an example in which at least one of zinc oxide and zinc hydroxide is added (Japanese Unexamined Patent Publication No. 184138/1983)
This method is also different from the present invention, as the catalyst used is different and it is said that it is preferable to conduct the process under alkaline conditions. In addition to the water-soluble zinc compound, various metals such as group A elements of the periodic table, salts of group A elements, manganese, cobalt, copper, etc. can be added to the reaction system, as in the known methods that have already been proposed. They may coexist. Further, in the present invention, preferable results are obtained by reacting the coexisting aqueous phase under acidic conditions. If the aqueous phase is made neutral or alkaline, the reaction rate will drop significantly, making it difficult to provide a practical production method. Further, to make it acidic, ordinary acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid, etc. may be added. In particular, sulfuric acid is extremely effective in increasing the reaction rate. The pH of the aqueous phase thus introduced into the reaction system is from 0.5 to less than 7.0, preferably from 2 to 6.5. The partial reduction reaction in the method of the present invention is usually carried out continuously or batchwise using a liquid phase suspension method.
A stationary phase method can also be used. The reaction conditions are
Although it is selected appropriately depending on the type and amount of the catalyst and additives used, the hydrogen pressure is usually 1 to 200 Kg/cm ² G,
Preferably it is in the range of 10 to 100 Kg/cm ² G, and the reaction temperature is in the range of room temperature to 250°C, preferably 100 to 200°C. In addition, the reaction time may be selected as appropriate by determining the selectivity of the target cyclohexene and the actual target value of the yield, and there is no particular restriction.
Usually it takes a few seconds to a few hours. (Effects of the Invention) According to the present invention, cycloolefin can be obtained with unprecedentedly high selectivity and yield, and is of extremely high value industrially. (Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 5.0 g of ruthenium chloride (RuCl _{3.3H 2} O) and 13.0 g of zinc chloride were dissolved in 500 ml of water, stirred, and 70 ml of 30% caustic soda aqueous solution was instantly added thereto, and the mixture was heated to 80°C. Stirring was continued for 2 hours. After cooling and standing, the black precipitate that settles out is decanted with 1N NaOH aqueous solution.
Washed twice. This black precipitate is mostly Zn
Ru(OH) ₃ containing (OH) ₂ , some of which existed in the form of chloride. 5% of this black precipitate
After dispersing the solution in 500 ml of caustic soda aqueous solution and charging it into an autoclave with an inner volume of 1 and whose inner surface was coated with Teflon, the total pressure was reduced to 50 ml with hydrogen.
Kg/cm ² G and reduced at 150° C. for 12 hours. After cooling,
The obtained black powder was reduced to 30% under an argon atmosphere.
After washing with an aqueous NaOH solution and further washing with water, this was vacuum dried to obtain 2.3 g of a black hydrogenation catalyst. When this catalyst was analyzed by X-ray diffraction, crystal growth was observed, and the average crystallite diameter was 55 Å.
On the other hand, the zinc content relative to ruthenium in this catalyst was determined by fluorescent X-ray method and was found to be 7.4% by weight. Next, partial reduction of benzene was performed using this catalyst. 0.4g of the above catalyst, 320ml of water, 14.4g of ZnSO ₄ 7H ₂ O
and 80 ml of benzene were charged into an autoclave with an inner volume of 1 and whose inner surface was coated with Teflon, and after the temperature was raised to 150°C, hydrogen was injected under pressure to bring the total pressure to 50.
Kg/cm ² G, and the reaction was carried out under high speed stirring. This reaction solution was extracted over time and the composition of the oil phase was analyzed by gas chromatography. The results are shown below.

[Table] The by-product was cyclohexane. Example 2 The black precipitate before reduction was dried in an Ar stream and then reduced with hydrogen in the gas phase. Average crystallite diameter is 61
Å, the zinc content relative to ruthenium was 8.5% by weight. The reaction was carried out in the same manner as in Example 1 except that this catalyst was used. The results are shown below.

[Table] Example 3 Dissolve 1.56 g of ruthenium chloride (RuCl _{3.3H 2} O) and 0.26 g of zinc sulfate (ZnSO _{4.7H 2} O) in 500 ml of water.
Stir and add 0.9 g of sodium borohydride to this.
Dissolved in 100ml of water to reduce, wash,
After drying, 0.6 g of hydrogenation catalyst was obtained. Zinc content relative to ruthenium is 2.6% by weight, average crystallite size is 40
It was Å. A reaction was carried out in the same manner as in Example 1 using this hydrogenation catalyst. The results are shown below.

[Table] Comparative Example 1 Ruthenium metal manufactured by Engelhard Japan Co., Ltd. (average crystallite diameter of 5000 Å or more) 0.5 as a hydrogenation catalyst
The same operation as in Example 1 was performed except that g was used. The results are shown below.

[Table] The effectiveness of the hydrogenation catalyst in the process of the invention is clear. Comparative Example 2 Metal ruthenium with an average crystallite diameter of 59 Å was prepared in the same manner as in Example 1 without using zinc chloride during catalyst preparation, and the reaction was carried out in the same manner as in Example 1, except that this was used as a hydrogenation catalyst. Ta. The results are shown below.

[Table] This clearly shows the superiority of the catalyst in the method of the present invention among catalysts having approximately the same average crystallite diameter. Comparative Example 3 4.0 g of a hydrogenation catalyst in which ruthenium was supported by a normal liquid phase adsorption and support method using an aqueous ruthenium chloride solution and zinc oxide powder, and then reduced with hydrogen to allow zinc oxide to support 1% by weight of metallic ruthenium.
The reaction was carried out in the same manner as in Example 1, except that . The results are shown below.

[Table] It is clear from this that the metal ruthenium catalyst using zinc as a carrier and the catalyst of the present invention are significantly different. Examples 4 to 9 Table 1 shows the results of reactions similar to those in Example 1 carried out in various aqueous solutions by varying the crystallite diameter of the metal ruthenium used as the hydrogenation catalyst and the zinc content.

[Table] As shown above, it can be seen that cycloolefins can be obtained with extremely high selectivity and yield.

Claims (1)

[Claims] 1 monocyclic aromatic hydrocarbon in water and at least 1
During partial reduction with hydrogen in the liquid phase under acidic conditions in the coexistence of a water-soluble zinc compound, the hydrogenation catalyst converts the zinc obtained by reducing the ruthenium compound containing the zinc compound in advance to ruthenium. 1. A method for producing a cycloolefin, comprising using an unsupported catalyst containing 0.1 to 50% by weight of metallic ruthenium and having an average crystallite diameter of 200 Å or less.