JPH02104536A - Production of cyclohexenes and hydrogenation catalyst therefor - Google Patents

Abstract

PURPOSE:To obtain cyclohexenes by the partial hydrogenation of a monocyclic aromatic hydrocarbon with hydrogen in the presence of water using a catalyst produced by supporting a group IVB metal in combination with Ru on hydrotalcites. CONSTITUTION:Cyclohexenes are produced in high selectivity and yield by partially hydrogenating a monocyclic aromatic hydrocarbon (e.g., benzene, chlorobenzene, hydroxybenzene or toluene) at 100-200 deg.C under a hydrogen pressure of 10-100kgf/cm<2> in the presence of water using a catalyst produced by supporting a group IVB metal in combination with Ru on hydrotalcites. The catalyst can be produced by using a carrier consisting of a hydrotalcite of formula I (M<2+> is Mg<2+>, Mn<2+>, Fe<2+>, etc.; M<3+> is Al<3+>, Fe<3+>, etc.; A<n-> is OH<->, F<->, Co, etc.) or a compound of formula II forming a hydrotalcite structure by hydration, supporting Ru ion and a group IVB metal in arbitrary order on the carrier and reducing the product.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for partially hydrogenating monocyclic aromatic hydrocarbons to produce corresponding cyclohexanes with high selectivity and high yield.

Cyclohexenes have high value as intermediate raw materials for organic chemical industrial chemicals, and are particularly important as raw materials for polyamides, lysine, etc.

<Prior art> Conventional methods for producing cyclohexene include dehydration reaction of cyclohexanols, dehydrohalogenation reaction of halogenated cyclohexanes, cracking reaction of cyclohexylarenes, and dehydrogenation or oxidative dehydration of cyclohexanes. Many methods are known, including elementary reactions.

In the production of cyclohexene by partial hydrogenation reaction of aromatic hydrocarbon compounds, it is difficult to obtain cyclohexene in good yield because the generated cyclohexene usually reacts more easily than the raw material aromatic hydrocarbon compound. It is well known that

However, since the starting material for either method is an aromatic hydrocarbon compound, the reaction process can be simplified if cyclohexanes can be obtained in good yield through the partial hydrogenation reaction of the aromatic hydrocarbon compound. It is also preferable from an industrial point of view.

From this point of view, many methods for producing cyclohexene by partial hydrogenation reaction of aromatic hydrocarbon compounds have been proposed, and examples include the following methods.

(1) A method using a catalyst composition containing water, an alkaline agent, and an element of Group I of the periodic table (Japanese Patent Publication No. 56-22850).

(2) A method using a ruthenium catalyst containing copper, silver, cobalt or potassium, water and a phosphate compound (Japanese Patent Publication No. 4536/1983).

(3) A method of partially hydrogenating a metal oxide such as silica or alumina in the presence of a catalyst mainly supporting ruthenium, water and cobalt sulfate (Japanese Unexamined Patent Publication No. 130926/1982).

(4) A method using a ruthenium catalyst supported on oxides of nickel, cobalt, chromium, titanium or zirconium and using alcohol or ester as an additive (Japanese Patent Publication No. 3933/1983).

(5) A method in which a mixed solution of ruthenium glycoxide and ethyl silicate is hydrolyzed and then partially hydrogenated in the presence of water and a ruthenium-silica catalyst prepared by hydrogen reduction at 400°C -155328).

(6) A method of carrying out a reaction using a ruthenium catalyst and adding at least one of zinc oxide and zinc hydroxide to the reaction system as an activating component (Japanese Unexamined Patent Publication No. 184138/1983)
.

(7) A method of partial hydrogenation using a catalyst prepared by reducing ruthenium containing zinc in the coexistence of a water-soluble zinc compound (Japanese Patent Application Laid-open No. 45544/1983).

(8) When carrying out partial hydrogenation using a catalyst in which barium sulfate is used as a carrier and a metal element mainly composed of ruthenium is supported, a type of silicon diacid, titanium dioxide, and aluminum oxide are allowed to coexist in the reaction. How to do (
(Japanese Patent Application Laid-Open No. 62-61935).

<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 keep the conversion rate of the raw material low, and the reaction rate is extremely low. The concentration and productivity of cyclohexene is low.

In addition, coexistence of large amounts of additives may complicate the reaction system or cause problems with equipment corrosion resistance.
The reality is that there is no practical method for producing cyclohexene.

The object of the present invention is to improve the drawbacks of these conventional techniques and to provide an industrially advantageous method for producing cyclohexanes and a catalyst for use in the production.

Means for Solving the Problems In order to solve the problems, the present inventors have proposed a method for improving the selectivity and yield of cyclohexenes in the partial hydrogenation reaction of monocyclic aromatic hydrocarbons. After extensive research, we discovered that a catalyst prepared by adsorbing ruthenium ions to hydrotalcites and/or compounds that form a hydrotalcite structure upon hydration and reducing the adsorbed ions would give good results, and we proposed this earlier. did. As a result of repeated studies aimed at further improving catalyst performance, the present inventors found that the newly discovered catalyst system improved the selectivity and yield of cyclohexenes, and arrived at the present invention.

That is, the present invention provides a method for producing cyclohexanes by partially hydrogenating a monocyclic aromatic hydrocarbon with hydrogen in the presence of water, in which at least 1 fi or more selected from group IV B elements of the periodic table is used. Provided is a method for producing cyclohexenes, characterized in that a catalyst prepared by compositely supporting a metal together with ruthenium on hydrotalcites and/or a compound that forms a hydrotalcite structure upon hydration is used.

Further, the present invention provides a compound in which at least one metal selected from group IVB elements of the periodic table is supported together with ruthenium on hydrotalcites and/or a compound that forms a hydrotalcite structure upon hydration. Provided is a hydrogenation catalyst characterized by the following.

The configuration of the present invention will be explained in detail below.

Benzenes, toluenes, xylenes, and lower alkylbenzenes are used as monocyclic aromatic hydrocarbons to be used as raw materials in the present invention.

Specific examples include benzene, chlorobenzene, droxybenzene, methoxybenzene, toluene, chlorotoluene, cresol, xylene, xylenol, and cyclohexylbenzene.

The catalyst of the present invention is prepared as follows to carry out a partial hydrogenation reaction of monocyclic aromatic hydrocarbons, and cyclohexene is produced using this catalyst.

That is, ruthenium ions are first adsorbed and supported on hydrotalcites, and then at least one or more metal ions selected from the group IVB elements of the periodic table, such as titanium, zirconium, or hafnium, are supported in a composite manner. , and then reduce it to prepare a partial hydrogenation catalyst. At this time, the elements of group IVB of the periodic table may be supported on the hydrotalcites first, and then the ruthenium ions may be adsorbed and supported, and the order of supporting is not limited.

In the present invention, the carrier used for the catalyst is not particularly limited as long as it is a hydrotalcite or a compound that forms a hydrotalcite structure upon hydration.

Preferred are hydrotalcites represented by the following formula 0, and compounds having a structure represented by the formula (2), which form a hydrotalcite structure by hydration with an oxide solid solution obtained by firing these.

...■ Here, M": Mg2°, Mn", Fe'°, Co", N
Divalent metals such as i'', Cu'', Zn'', or mixtures thereof M'': A1'', Fe'', Cr'', Co'', In''
Trivalent metals such as An-2OH-, F-, Cbi, Br-1NO, -1co
, '-, SO4''-, CHs COO-, an n-valent anion such as oxalate ion, salicylate ion, or a mixture thereof or a mixture.

The ruthenium ion to be adsorbed or supported on the hydrotalcites may be any valuable ruthenium compound. Ruthenium compounds that can be used include, for example, salts such as chlorides, bromides, nitrates, and sulfates, and complexes such as acetylacetonate complexes and ammine complexes, but trivalent or tetravalent ruthenium compounds are particularly easy to obtain. It is also preferred because it is easy to handle.

In the present invention, the amount of ruthenium ions adsorbed or supported on the hydrotalcites is adjusted to 0.01 to 1% by weight based on the hydrotalcites. If the adsorption amount is less than 0.01% by weight, a large amount of catalyst must be prepared, which is not economical. On the other hand, it is also not economical to adsorb more ruthenium than the required amount.

In the present invention, the group IVB elements of the periodic table, such as chlorine, zirconium, or hafnium, which are compositely supported in combination with ruthenium, are valuable compounds.
Examples of the form of the compound that can be used include water-soluble salts such as chlorides, bromides, nitrates, sulfates, and complexes such as acetylacetonate complexes and ammine complexes.

When a compound such as titanium, zirconium, or hafnium is combined with ruthenium, it may be used alone or in combination of multiple compounds.
It ranges from 0.05 to 10, preferably from 0.1 to 5.

The ruthenium ions adsorbed and supported on hydrotalcites and at least one metal ion selected from the group IVB elements of the periodic table, such as titanium, zirconium, or hafnium, are reduced to a metallic state. It is converted into a metal salt selected from ruthenium, titanium, zirconium, or hafnium.

Prior to this reduction treatment, heat treatment can be carried out if necessary. The temperature required for heat treatment is 300-700℃
A range of is preferred.

As the reduction method, a general ruthenium reduction method can be applied. For example, reduction with hydrogen in the gas phase or reduction with hydrogen or an appropriate chemical reducing agent such as NaBH4 or formalin in the liquid phase is possible; preferable.

The method of the present invention requires the coexistence of water. The amount of water varies depending on the reaction type, but generally it can be present in an amount of 0.1 to 50 times the weight of the monocyclic aromatic hydrocarbon used. However, the amount of water must be such that under the reaction conditions, an organic phase containing raw materials and products as main components and an aqueous phase form two liquid phases.

The coexistence of a very small amount of water that forms a homogeneous phase under the reaction conditions, or the coexistence of a significantly large amount of water, reduces the effectiveness of water.

Moreover, if the amount of water is too large, it becomes necessary to enlarge the reactor, which is not economical. Therefore, practically 0.5
It is desirable to coexist ~10 times by weight.

In the method of the present invention, an alkaline aqueous solution can be used in place of water if necessary. The pH of the alkaline aqueous solution need only be 7 or more, and the alkali concentration can be, for example, up to 10% in sodium hydroxide solution.

The partial hydrogenation reaction in the method of the present invention is usually carried out continuously or batchwise by a liquid phase suspension method, but it can also be carried out by a fixed bed method.

The reaction conditions are appropriately selected depending on the type of hydrotalcite used for catalyst preparation and the amount of adsorbed and supported ruthenium, but usually the hydrogen pressure is 1 to 200 kg f /
cm', preferably 10 to 100 kgf/cm
The range is 2. The incubation temperature is in the range of 50 to 250°C, preferably ioo to 200°C. The reaction time is appropriately selected depending on the selectivity and yield of the target cyclohexene. Usually a few minutes to a few hours.

The catalyst of the present invention contains at least one element selected from group IVB elements of the periodic table, such as titanium, zirconium, or hafnium, in hydrotalcites and/or compounds that form a hydrotalcite structure upon hydration. It is a catalyst in which a metal and ruthenium are supported in a composite manner, and the ruthenium ion and at least one metal ion selected from titanium, zirconium, hafnium, etc. are highly dispersed on the carrier, and the support on the support is highly dispersed. Or, since ruthenium and at least one metal selected from hafnium etc. enter into the crystal lattice of hydrotalcites, ruthenium and titanium,
It exhibits strong interaction with at least 1211 or more metals selected from zirconium, hafnium, etc., and exhibits high catalytic performance.

Therefore, if a partial hydrogenation reaction of monocyclic aromatic hydrocarbons is carried out using this catalyst, cyclohexene can be obtained with unprecedentedly high selectivity and yield.

<Examples> The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

(Example 1) 8 3 units equipped with a stirrer, reflux condenser, and solid powder inlet
RuC15/XH2 in a 00mj2 separable flask
0.50 g (Ru content ca, 45%) and 200 mJl of ion-exchanged water were charged. While stirring the contents of the flask in a nitrogen stream at room temperature, hydrotalcite (composition ZnO5
7.8%, Al2O3 10.6%, CO2 5.0%)5
．． 0g was added all at once. Stirring was performed for 4 hours at room temperature. The temperature was further raised to 80°C and stirring was continued for 4 hours.

When the adsorption of ruthenium onto hydrotalcite was completed, the brown color of ruthenium trichloride dissolved in water completely disappeared, confirming that ruthenium had been adsorbed.

Hydrotalcite with ruthenium adsorbed was separated into solid and liquid using a centrifugal sedimentator. The obtained solid was air-dried under a nitrogen stream to obtain a hydrotalcite catalyst precursor 5.48 in which ruthenium was adsorbed and supported.

1.0 g of the precursor was taken and dispersed in 50 mJZ of ion-exchanged water. While stirring the dispersion, add 20%
of TiC1, 0.128 g of aqueous solution in 50 m of ion-exchanged water
A solution dissolved in jZ was added at room temperature. 4 at room temperature
The mixture was stirred for an hour, then the temperature was further raised to 80° C., and stirring was continued for 4 hours. The hydrotalcite carrying a composite of ruthenium and titanium is again separated into solid and liquid using a centrifugal sedimentation machine.
Furthermore, the obtained solid was air-dried under a nitrogen stream.

In this way, 1.1 g of a catalyst precursor in which 4.3% of ruthenium and 0.8% of titanium were supported on hydrotalcite was prepared.

Take 0.5g of this precursor and add 30mJ of hydrogen at 150℃ and normal pressure! /min for 7 hours to carry out gas phase reduction treatment and complete the catalyst for partial hydrogenation reaction.

0.5 g of the obtained catalyst was added to 160 g of a 1% NaOH aqueous solution.
and contents Ji 500 m along with 40 g of benzene
After charging the autoclave into a ft titanium autoclave and replacing the gas with nitrogen, the temperature was started to rise. When the inner water of the autoclave reached 150°C, hydrogen was added to 35 kg f.
/cm2. As the hydrogenation reaction progresses, the pressure decreases, so replenish hydrogen from time to time.
The pressure was maintained at "kgf/cm".

After 50 minutes of reaction, a portion of the reaction mixture was extracted, the oil phase and the water phase were separated, and the oil phase was analyzed by gas chromatography. As a result, the benzene conversion rate was 21.0%.
The reaction result was a cyclohexene yield of 16.6% (selectivity 79.0%).

The reaction was further continued, and the reaction was stopped when 90 minutes had elapsed. The autoclave was cooled and the contents removed. The oil phase and the aqueous phase were separated, and the oil phase was analyzed by gas chromatography. As a result, the benzene conversion rate was 44.
2%, cyclohexene yield 2962% (selectivity 66.0
%) reaction results.

(Comparative Example 1) Catalyst precursor obtained in Example 1 (at a stage in which only ruthenium was supported on hydrotalcite) 0.5
After subjecting g to gas phase reduction treatment with hydrogen in the same manner as in Example 1,
A partial hydrogenation reaction of benzene was carried out. As a result of analyzing a sample during the reaction time of 60 minutes and a reaction mixture when the reaction was stopped after 140 minutes, the following reaction results were obtained.

Reaction Benzene Cyclohexene (Selectivity) Time Conversion rate Yield 140 40.9 24.7 (60
, 3) (Example 2) Zirconium was supported on 1.0 g of the precursor obtained in Example 1 in the same manner as in Example 1.

The amounts of ruthenium and zirconium supported on the catalyst precursor were 4.3% and 0.8%, respectively.

Using 0.5 g of the obtained catalyst precursor, the same gas phase reduction pretreatment and benzene partial hydrogenation reaction as in Example 1 were performed, and the following reaction results were obtained.

Reaction Benzene Cyclohexene (Selectivity) Time Conversion rate Yield (Example 3) Catalyst precursor obtained in Example 1 1. Hafnium was supported on Og in the same manner as in Example 1.

The amounts of ruthenium and zirconium supported on the catalytic precursor are 4.3% and 0.8%, respectively.

Using 0.5 g of the obtained catalyst precursor, the same gas phase reduction pretreatment and benzene partial hydrogenation reaction as in Example 1 were performed, and the following reaction results were obtained.

Reaction Benzene Cyclohexene (Selectivity) Time Conversion Rate Yield (Example 4) The same procedure as in Example 1 was carried out except that the amount of titanium supported was changed to 1.6%.

The following reaction results were obtained.

Reaction Benzene Cyclohexene (Selectivity) Time Conversion Rate Yield (Example 5) The same procedure as in Example 1 was carried out except that the amount of titanium supported was changed to 2.4%.

The following reaction results were obtained.

Reaction Benzene Cyclohexene (Selectivity) Time Conversion rate Yield Regarding the experimental data of Examples 1 to 3 and Comparative Example 1, the relationship between benzene conversion rate and cyclohexene selectivity was
Shown in the figure.

From Figure 1, it can be seen that a catalyst system in which ruthenium and a metal selected from group B elements of the periodic table such as titanium, zirconium, and hafnium are supported on hydrotalcite is superior to a catalyst system in which only ruthenium is supported. Illustrated.
Note that in the figure, the expressions such as Ru/HT represent catalysts in which ruthenium or the like is supported on a hydrotalcite carrier.

<Effects of the Invention> The production method of the present invention uses a catalyst in which at least one metal selected from group IVB elements of the periodic table is supported in combination with ruthenium on hydrotalcites, etc.
Monocyclic aromatic hydrocarbons are partially hydrogenated with high conversion, and cyclohexene can be obtained with high selectivity and yield.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between benzene conversion rate and cyclohexene selectivity.

Claims (2)

[Claims] (1) In a method for producing cyclohexanes by partially hydrogenating monocyclic aromatic hydrocarbons with hydrogen in the presence of water, at least one metal selected from group IVB elements of the periodic table is added together with ruthenium. A method for producing cyclohexanes, which comprises using a catalyst prepared by compositely supporting hydrotalcites and/or a compound that forms a hydrotalcite structure upon hydration. (2) At least one metal selected from group IVB elements of the periodic table is supported in combination with ruthenium on hydrotalcites and/or a compound that forms a hydrotalcite structure upon hydration. Hydrogenation catalyst for