JPH08259473A - Production of cycloolefin - Google Patents

Abstract

PURPOSE: To efficiently obtain a cycloolefin at a high reaction rate by making high-parity water having high electric conductivity exist in partially reducing a monocyclic aromatic hydrocarbon with hydrogen in the presence of a ruthenium catalyst. CONSTITUTION: A monocyclic aromatic hydrocarbon (e.g. benzene or toluene) is reduced with hydrogen in the presence of a ruthenium catalyst and water having <=1μm/cm, preferably <=0.5μs/cm electric conductivity. Metal ruthenium obtained by reducing a ruthenium compound such as ruthenium chloride is generally used as the ruthenium catalyst. The amount of the water added is preferably 0.1-5 pts.wt. based on 1 pt.wt. of the monocyclic aromatic hydrocarbon. In order to reduce electric conductivity of water, water is passed through a cationic exchange resin or an anionic exchange resin. The partial reduction reaction is preferably carried out at 100-200 deg.C under 0.5-10MPa hydrogen pressure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for partially reducing monocyclic aromatic hydrocarbons to produce cycloolefins, and more particularly to a method for partially reducing benzene to produce cyclohexene. Cyclohexene is widely used as an intermediate raw material for organic chemical industrial products, for example, a polyamide raw material.

[0002]

2. Description of the Related Art Various methods are known for producing cycloolefins, especially cyclohexene. Among them, a method for partially reducing a monocyclic aromatic hydrocarbon with hydrogen in the presence of a ruthenium catalyst and water is known. The most common,
As a method of improving the selectivity and yield of cyclohexene,
Many results have been reported regarding the types of catalyst components and carriers, or metal salts as additives to the reaction system (Japanese Patent Publication No. 56-22850 and Japanese Patent Publication No. 57-1309).
26, JP-B-57-7607, JP-A-61-4022
6, JP-A-62-45544).

[0003]

However, all the conventional methods have some problems, and are not necessarily industrially advantageous methods. In particular, there are problems such that reproducible reaction results cannot always be obtained even if the catalyst and metal salt additive in the reaction system are improved, and the activity of the catalyst is still insufficient.

[0004]

Means for Solving the Problems The present inventors have conducted extensive studies to improve the above-mentioned drawbacks of the prior art and to provide a more industrially advantageous method for producing cycloolefins. It was found that the water purity in the partial reduction reaction sensitively affects the reaction results. Further, they have found that by adopting electric conductivity as an index showing the purity of such water, the reaction results can be improved and stabilized, and the present invention has been accomplished.

That is, the gist of the present invention is to provide a method for producing a cycloolefin in which a monocyclic aromatic hydrocarbon is partially reduced with hydrogen in the presence of a ruthenium catalyst and water. In the presence of a method for producing a cycloolefin which is partially reduced by hydrogen,
A method for producing a cycloolefin is characterized in that water having an electric conductivity of 1 μS / cm or less is used.

The present invention will be described in more detail below. The monocyclic aromatic hydrocarbon used as a raw material in the present invention is benzene, or benzene substituted with a lower alkyl group having about 1 to 4 carbon atoms, such as toluene and xylene.

As the ruthenium catalyst, metal ruthenium obtained by reducing various ruthenium compounds is used. The ruthenium compound is not particularly limited, but for example, chloride, bromide, iodide, nitrate, sulfate, hydroxide, oxide, or a complex containing various kinds of ruthenium can be used. As the reduction method, a catalytic reduction method using hydrogen gas or a chemical reduction method using formalin, sodium borohydride, hydrazine or the like is used. Further, other metals such as zinc, chromium, molybdenum, tungsten, manganese, cobalt, nickel in the reduction preparation step or after preparation of the ruthenium compound,
A material mainly composed of ruthenium obtained by adding iron, copper, gold or the like is used. When using such other metal, the atomic ratio to the ruthenium atom is usually selected in the range of 0.01 to 20, preferably 0.1 to 10.

The ruthenium catalyst may be used alone as ruthenium, or may be used by supporting it on a carrier. Examples of the carrier include silica, alumina, silica-alumina, general metal oxides, complex oxides, hydroxides, sparingly water-soluble metal salts and the like. Examples of the ruthenium loading method include an ion exchange method, an adsorption method, a dipping method, a coprecipitation method, and a dry solidification method. The amount of ruthenium supported is usually 0.
It is 001 to 20% by weight, preferably 0.1 to 10% by weight.

The reaction system of the present invention requires the presence of water. The amount of water added is usually 0.01 to 10 times by weight, preferably 0.1 to 5 times by weight that of the monocyclic aromatic hydrocarbon. If the amount of water is too small or too large, the effect of the presence of water is reduced, and if the amount of water is too large, it is necessary to enlarge the reactor, which is not preferable. An important feature of the present invention is that the electric conductivity of the water supplied to the reaction system is 1 μm.
The point is to use water of S / cm or less, preferably 0.5 μS / cm or less. By using such water, higher catalytic activity is exhibited in the reaction system.

In general, water used industrially is purified to some extent by treating industrial water with an ion exchange resin. However, such industrial water also has an insufficient degree of purification or changes in purity depending on the nature of the raw water and the degree of treatment. However, there are no reports of detailed studies up to the effect of water purity at the industrial water level in reactions such as partial reduction of monocyclic aromatic hydrocarbons that are expected to be carried out on a large scale industrially. However, the remarkable influence on the reaction results at the industrial water level revealed by the present inventors was a totally unexpected phenomenon.

In order to evaluate the purity of water, it is ideal to quantify various trace impurities in water to obtain the correlation between the impurities and the catalytic activity, but in reality, it is complicated and is not always realistic. Not a quality control method. Therefore, in the present invention, as an index of water purity, the electrical conductivity of water to be used, which has a large correlation between catalytic activities, is measured. The electric conductivity value is considered to correspond to the amount of ionic impurities in the water, but if the electric conductivity of the water used is 1 μS / cm or less, the trace amount of specific ions in the water is assumed. Even if it exists, it has almost no effect on the catalytic activity.

The method for reducing the electric conductivity of water can be carried out by passing water through a cation exchange resin or an anion exchange resin. Amount of exchange resin used, and
Water having such an electric conductivity can be obtained by appropriately setting the residence time of water. The electric conductivity of water may be measured by using a general electric conductivity measuring device, and usually, it may be measured in accordance with the ultrapure water electric conductivity test method of JIS K0552.

Further, in the reaction system of the present invention, a metal salt may be used in combination as in a conventionally known method. The types of metal salts include metals of Group 1 such as lithium, sodium and potassium in the periodic table, and metals of Group 2 such as magnesium and calcium (the group number is IUPAC Inorganic Chemical Nomenclature Revised Edition (198
9)) or nitrates, chlorides, sulfates, acetates, phosphates and the like of metals such as zinc, manganese and cobalt, and zinc sulfate is particularly preferably used in combination. The amount of the metal salt used is usually 1 × 10 ⁻⁵ to water in the reaction system.
It is about 1 times by weight, preferably about 1 × 10 ^{−4 to} 0.2 times by weight.

As the reaction conditions of the present invention, the reaction temperature is
It is usually 50 to 250 ° C, preferably 100 to 220 ° C. When it exceeds 250 ° C, the selectivity of cycloolefin is lowered, and when it is less than 50 ° C, the reaction rate is remarkably lowered, which is not preferable. The pressure of hydrogen during the reaction is usually 0.1 to 20.
MPa, preferably 0.5 to 10 MPa. When it exceeds 20 MPa, it is industrially disadvantageous, while when it is less than 0.1 MPa, the reaction rate remarkably decreases, which is uneconomical in terms of equipment. The reaction type is not particularly limited and may be a batch type or a continuous type.

The electric conductivity of water used in the present invention means the electric conductivity of pure water newly supplied to the reaction system, and in the batch system, the dissolved oxygen concentration of water charged to the reaction system. In the continuous system, it means the electric conductivity of water newly supplied to the reaction system. Further, when a mixed slurry of water and a catalyst or a metal salt is prepared in advance and the mixed slurry is supplied to the reaction system, the electric conductivity of the raw material water used for the mixed slurry is the subject of the present invention. Needless to say.

[0016]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to the examples as long as the gist thereof is not exceeded. Example 1 Silica was impregnated with zirconium nitrate and then heat-treated at 1000 ° C. to obtain a zirconia-modified silica (weight ratio of ZrO ₂ : Si
O ₂ = 1: 19) was used as a carrier, the ruthenium chloride aqueous solution containing a predetermined amount of ruthenium and the zinc chloride aqueous solution containing a predetermined amount of zinc were mixed with the above carrier, and the mixture was impregnated at 60 ° C. for 1 hour. Water was distilled off with a tarry evaporator and dried. 0.5% R thus obtained
u-0.5% Zn / carrier was reduced and activated in a hydrogen stream at 200 ° C. for 3 hours.

On the other hand, the electric conductivity is about 500 μS at 25 ° C.
/ Cm of unpurified water was purified by an ion exchange resin to have an electric conductivity of 0.22 μS / cm. The electric conductivity of water was measured according to JIS K0552. 150 ml of the above water, 18 g of zinc sulfate heptahydrate, 3.75 g of the above catalyst and 10 parts of benzene were used in a reactor having a reactor inner wall and a stirring blade made of titanium and having an internal volume of 0.5 L.
0 ml was charged. Further, hydrogen gas was introduced at a flow rate of 57 Nl / hr, the reaction pressure was 5.0 MPa, the temperature was 150 ° C., and the partial reduction reaction was performed while performing high-speed stirring. The results of the reaction 40 minutes after the start of the reaction are shown in Table 1 by analyzing the oil phase of the reaction solution by gas chromatography.

Example 2 Unpurified water having an electric conductivity of about 500 μS / cm at 25 ° C. was purified by an ion exchange resin to have an electric conductivity of 0.09 μS / cm. The partial reduction reaction of benzene was carried out by the method described in Example 1 except that such water was used. Shows the reaction results after 40 minutes from the start of the reaction.
It is shown in FIG.

Comparative Example 1 Unpurified water having an electric conductivity of about 500 μS / cm at 25 ° C. was purified by an ion exchange resin to have an electric conductivity of 1.9 μS / cm. Other than using such water,
The partial reduction reaction of benzene was carried out by the method described in Example 1. The reaction results 40 minutes after the start of the reaction are shown in Table 1.

[0020]

[Table 1]

[0021]

INDUSTRIAL APPLICABILITY By the method of the present invention, a cycloolefin can be efficiently produced from a monocyclic aromatic hydrocarbon at a high reaction rate and is industrially useful.

Claims (1)

[Claims] 1. A method for producing a cycloolefin in which a monocyclic aromatic hydrocarbon is partially reduced with hydrogen in the presence of a ruthenium catalyst and water, wherein water having an electric conductivity of 1 μS / cm or less is used. A method for producing a cycloolefin.