JPH11158084A - Production of cycloolefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce the subject compound useful as a raw material for polyamiides, lysine, etc., in high selectivity and high yield for long period by carrying out a partial hydrogenating reaction of a monocyclic aromatic hydrocarbon with a specific hydrogen in the presence of a ruthenium catalyst, water and a metal sulfate. SOLUTION: A partial hydrogenating reaction of a monocyclic aromatic hydrocarbon (e.g. benzene, toluene or xylene) with hydrogen at <=1 vol. ppb sulfur compound concentration is carried out in the presence of a ruthenium catalyst, water and a metal sulfate (preferably zinc sulfate) to thereby afford a cycloolefin. The sulfur compound concentration is preferably measured by a method for directly introducing the hydrogen into a concentrating tube comprising flowing a measurement gas through a sampling line for >=1 hr under conditions of <=20,000 SV of the concentration tube and then carrying out the measurement in a method for measuring a gas chromatography-solid collecting method. The reactional pressure is preferably 20-70 atm and the reactional temperature is preferably 100-200 deg.C. The method for production is preferably carried out by a continuous reactional manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cycloolefin by hydrogenating a monocyclic aromatic hydrocarbon in the presence of a ruthenium catalyst. Cycloolefins, particularly cyclohexenes, have high value as intermediate materials for organic chemical products, and are particularly useful as polyamide materials, lysine materials, and the like.

[0002]

2. Description of the Related Art Various methods for producing cycloolefins are known, and among them, a method of partially hydrogenating a monocyclic aromatic hydrocarbon using a ruthenium catalyst is the most common method. As a method for improving the yield and yield, there have been reported many results of studies on types of catalyst components and supports, metal salts as additives to the reaction system, and the like.

[0003] Among them, in a reaction system in which water and zinc having a relatively high yield of cycloolefin coexist, for example, (1) a monocyclic aromatic hydrocarbon is mixed with water and at least one zinc compound in an intermediate state. For partial reduction with hydrogen under neutral or acidic conditions, using a catalyst in which particles mainly composed of metal ruthenium having an average crystallite size of 30 to 200 ° are supported on a carrier (Japanese Patent Publication No. 8-80).
No. 25919), (2) in the presence of a ruthenium catalyst,
In producing a cycloolefin by partially hydrogenating a monocyclic aromatic hydrocarbon, at least one of zinc oxide and zinc hydroxide in a reaction system in an amount equal to or less than the saturation solubility is used.
A method in which all seeds are present in a dissolved state (Japanese Patent Publication No.
No. 12331), (3) When partially reducing a monocyclic aromatic hydrocarbon with hydrogen in the presence of water, using hydrogenation catalyst particles mainly composed of metal ruthenium having an average crystallite diameter of 200 ° or less, A method in which a reaction is carried out under neutral or acidic conditions in the presence of at least one kind of solid basic zinc (Japanese Patent Publication No. 8-19012) has been proposed.

[0004] These methods are effective methods because cycloolefins can be directly obtained from a monocyclic aromatic hydrocarbon. However, in such a method using an expensive catalyst of a noble metal element, the point is how high the selectivity and high yield of the cycloolefin as the target of the catalyst can be maintained. Generally, there are various causes for the decrease in the cycloolefin selectivity of the catalyst.For example, in a process for producing cyclohexene by hydrogenating benzene, it is known that one of the causes is a sulfur compound contained in the raw material benzene. ing. For example, Japanese Patent Publication No. 19096/1990 mentions the problem of sulfur in the raw material benzene.
However, even if the problem of sulfur in benzene was solved, the suppression of the selectivity and the yield was not sufficient.

On the other hand, as raw material hydrogen, for example, naphtha,
Those obtained by steam reforming of methane, methanol, etc.
Crude hydrogen, coal gas, coke off gas (CO2) obtained from the dehydrogenation of hydrocarbons such as propane and ethylbenzene
G) is obtained through carbon monoxide reaction, carbon dioxide removal, methanation reaction, hydrogen purified by membrane separation method, adsorption separation method, and other recovered hydrogen such as electrolytic hydrogen. In general use for hydrogenation and hydrogenation reactions, the sulfur compound in the raw material hydrogen is 100%, which is the detection limit of the detection tube method known as a conventional measurement method as hydrogen sulfide.
Volppb or less was considered sufficient.

However, the present inventors have produced a cycloolefin for a long time by partially hydrogenating a monocyclic aromatic hydrocarbon with hydrogen having a hydrogen sulfide concentration of about 100 volppb contained in the raw material hydrogen using a ruthenium catalyst. If so, it has been found that the selectivity of the desired cyclohexene is significantly reduced.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a method for partially hydrogenating a monocyclic aromatic hydrocarbon partially with hydrogen using a ruthenium catalyst and stably maintaining the selectivity and the yield for a long period of time. It is an object of the present invention to provide a production method capable of producing cycloolefin.

[0008]

Means for Solving the Problems We have selected a selectivity,
As a result of intensive studies to determine the cause of the decrease in the yield, it was found that the presence of a trace amount of sulfur compounds contained in the raw material hydrogen poisons the catalyst and significantly impairs the catalytic performance, especially the selectivity to cyclohexene. I found it. This is even at values below the detection limits of known direct analysis techniques, e.g., detector tube methods, absorption spectroscopy, gas chromatography-direct collection, gas chromatography-solids collection, etc. This also indicates that it is not suitable for the partial hydrogenation reaction in the present invention. Further, the correlation between the sulfur concentration in the raw material hydrogen and the decrease in cycloolefin selectivity was pursued by the method described below. In order to stably obtain a high cycloolefin selectivity and high yield for a long time, The concentration of sulfur compounds contained in water is the conventional detection limit of 1.
It was found that 00 volppb was not enough and it was necessary to be 1 volppb or less, and the present invention was reached.

That is, the present invention relates to (1) a method for producing a cycloolefin by partially hydrogenating a monocyclic aromatic hydrocarbon with hydrogen in the presence of a ruthenium catalyst, water and a metal sulfate; A method for producing a cycloolefin, wherein the compound concentration is 1 volppb or less. (2) The cyclocompound according to (1), wherein the sulfur compound concentration is a concentration measured by a method in which the hydrogen is directly introduced into a concentration tube in a gas chromatography-solid collection method. Olefin production method. (3) The concentration of the sulfur compound is determined by the gas chromatography-solid collection method, and the SV of the concentrating tube is 2,000.
The method for producing a cycloolefin according to (2), wherein the concentration is measured in a state of 0 or less. (4) The method according to (2), wherein the concentration of the sulfur compound is a concentration measured after flowing a measurement gas through a sampling line for one hour or more in a gas chromatography-solid collection method. The present invention relates to the method for producing a cycloolefin described in (3).

The monocyclic aromatic hydrocarbon in the present invention is:
Benzene, toluene, xylene, and usually 1-4 carbon atoms
Is benzene substituted with a lower alkyl group. In the present invention, the sulfur compound concentration is 1 volppb or less, preferably 0.3 ppb or less, more preferably 0.1 volpb or less.
Hydrogen of lppb or less is used. Sulfur compound concentration is 1
When the content exceeds volppb, the selectivity and yield of cycloolefin decrease, and when the reaction is carried out for a long time, for example, more than 1400 hours, it becomes difficult to produce a stable cycloolefin.

The raw material hydrogen used in the present invention is, for example,
Conventionally used sulfur compound concentration is 100 volpp
About b hydrogen is desulfurized by using a desulfurizing agent such as zinc oxide, activated carbon, copper oxide, iron oxide, nickel, ruthenium, palladium, aluminum alone or in combination, and the concentration of the contained sulfur compound is adjusted within the range of the present invention. Obtained by:

Concentration of sulfur compound in raw material hydrogen 1 volpp
The value of b or less is a value below the limit of quantification of a conventionally known direct analysis method, for example, a detection tube method, an absorption spectrophotometry method, a gas chromatography method-direct collection method, a gas chromatography method-a solid collection method. Therefore, in the present invention, the sulfur compound concentration in the raw material hydrogen is measured by the following method. In general, gas chromatography-solid collection means that hydrogen gas is collected in a collection bag and then connected to a concentration tube (solid particle layer) cooled with a refrigerant such as liquid oxygen, liquid argon, or liquid nitrogen. By aspirating the amount, the sulfur compound in the collection bag is collected in a concentrating tube. Next, after connecting the concentrating tube to a heating introduction device and a gas chromatograph device, the concentrating tube was heated to 60 ° C.
This is a method in which the temperature is increased by heating to about 2 minutes, and a sulfur compound is introduced into a gas chromatograph for measurement.

On the other hand, the characteristic of the measurement method used in the present invention is that the gas chromatography method-solid collection method
Since the hydrogen containing the sulfur compound is directly introduced and concentrated into the concentration tube without using the collection bag, the loss of the adsorption of the sulfur compound to the collection bag is eliminated. Further, by setting the (concentrated gas flow rate) / (concentrated filler volume) of the concentrating tube, that is, the SV to preferably 20,000 or less, more preferably 6500 or less, the collection efficiency of the concentrating tube becomes high, and Measurement of sulfur compound concentration became possible.

Further, before the measurement, the existing piping shown in FIG.
A sampling gas consisting of 3 / 4B (1), 3 / 4B connection joint (2), needle valve (3), and outlet of Teflon tube (4) is preferably used for at least 1 hour, more preferably at least 24 hours. To make the adsorption of the sulfur compound on the sampling line saturated, and then measure the concentration of the sulfur compound, whereby a more accurate sulfur compound concentration can be obtained.

By using the above measuring method, it has become possible to measure a sulfur compound concentration in hydrogen up to 0.1 volppb. The sulfur compound of the present invention refers to a group of compounds widely known as trace contaminants in the raw material hydrogen, such as hydrogen sulfide (H ₂ S), sulfur dioxide (SO ₂ ), carbonyl sulfide (COS), Carbon disulfide (CS ₂ ), thiols (R
—SH), sulfides (RSR), disulfides (R-SS-R), thiophene, and the like. Note that compounds containing SO ₄ ^2- are not included. R represents a hydrocarbon.

The ruthenium catalyst used in the present invention is a catalyst containing metal ruthenium obtained by previously reducing various ruthenium compounds. Ruthenium compounds include, for example, chlorides, bromides, halides such as iodides, or nitrates, sulfates, hydroxides, or complexes containing various types of ruthenium, such as ruthenium carbonyl complexes, ruthenium acetylacetonato complexes, ruthenocene complexes, ruthenium complexes. Ammine complexes and compounds derived from such complexes can be used. Further, two or more of these ruthenium compounds may be used in combination. As a method for reducing these ruthenium compounds, a catalytic reduction method using hydrogen, carbon monoxide or the like, or a chemical reduction method using formalin, sodium borohydride, hydrazine or the like is used. This reduction may be performed in a gas phase or a liquid phase. Further, before or after the reduction of the ruthenium compound, other metals or metal compounds, for example, zinc, chromium,
Molybdenum, tungsten, manganese, cobalt, nickel, iron, copper, gold, platinum, or the like, or a material mainly containing ruthenium obtained by adding a compound of such a metal may be used. When such a metal or metal compound is used, the atomic ratio to the ruthenium atom is usually 0.1.
001 to 20 are selected. Among them, zinc and a zinc compound are preferable, and the zinc and the zinc compound are preferably added before the reduction of the ruthenium compound.
A content by weight is particularly preferred.

The ruthenium catalyst may be used by being supported on a carrier. The carrier is not particularly limited, but may be magnesium, aluminum, silicon, calcium, titanium, vanadium, chromium, manganese, cobalt, iron, nickel, copper, zinc, zirconium, hafnium, tungsten or the like, or such a metal. Oxides, composite oxides, hydroxides, sulfates, poorly water-soluble metal salts,
Alternatively, compounds and mixtures in which two or more such carriers can be chemically or physically combined are exemplified.

The method for supporting ruthenium is not particularly limited, but examples thereof include an adsorption method, an ion exchange method, an immersion method, a coprecipitation method, and a drying method. The amount of ruthenium supported is not particularly limited, but is usually 0.001 to 20% by weight based on the carrier. However, it is preferable that ruthenium is used as it is without being supported on a carrier.

Further, the average crystallite size of the ruthenium catalyst is preferably not more than 200 °, and the measurement of the average crystallite size of the ruthenium catalyst is based on the spread of the ruthenium catalyst used from the spread of the diffraction line width obtained by the X-ray diffraction method.
Is calculated by the following equation. Specifically, it is calculated from the spread of a diffraction line having a maximum at a diffraction angle (2θ) of around 44 ° using CuKα radiation as an X-ray source. The lower limit of the average crystallite diameter is theoretically larger than the crystal unit, and is actually 10 ° or more.

In the reaction system of the present invention, water is present, and its amount varies depending on the reaction mode. However, water may be present in an amount of 0.001 to 100 times by weight based on the starting monocyclic aromatic hydrocarbon used. Although it is possible, if the amount of water is too small, the selectivity of cycloolefin is reduced, and if the amount of water is too large, there are adverse effects such as an increase in the size of the reactor. 0.5 for
It is preferable to coexist up to 20 times by weight.

The concentration of hydrogen ions in the aqueous phase formed by water coexisting with the reaction system, that is, pH, must be acidic or neutral, not higher than 7.0. Furthermore, the present invention requires that the metal sulfate be present, and that the reaction system does not need to be present in its entirety as a solid, and it is preferable that at least a part of the metal sulfate is present in a dissolved state in the aqueous phase present in the reaction system. Is preferred. Examples of the metal sulfate to be present in the reaction system include zinc, iron, nickel, cadmium, gallium, indium, magnesium aluminum, chromium, manganese, cobalt, copper, and the like. It may be a double salt containing a metal sulfate. In particular, it is preferable to use zinc sulfate as the metal sulfate. The amount of the metal sulfate used is 1.0 × 10 4 of water present in the reaction system.
^In particular, when zinc sulfate is used as the metal sulfate, the amount is more preferably 1.0 × 10 ^{−4 to} 0.5 times by weight.

The following metal salts may be present in the reaction system of the present invention as in a conventionally known method. Examples of the kind of the metal salt include Group 1 metals such as lithium, sodium and potassium in the periodic table, and Group 2 metals such as magnesium and calcium (the group numbers are based on the revised IUPAC inorganic chemical nomenclature (198).
9)), or zinc, manganese, cobalt,
Metal nitrates such as copper, cadmium, lead, arsenic, iron, gallium, germanium, vanadium, chromium, silver, gold, platinum, nickel, palladium, barium, aluminum,
Examples include chlorides, oxides, hydroxides, acetates, phosphates, and the like, or a mixture of two or more of them chemically and / or physically. Among them, zinc hydroxide, zinc oxide and the like are exemplified. The addition of a zinc salt is preferred, especially a double salt containing zinc hydroxide, for example, the general formula (ZnSO ₄ ) _m · (Zn (O
H) ₂₎ represented by _n m: _n = 1: the presence of a double salt of 0.01 are preferred. The amount of the metal salt used is not particularly limited as long as the aqueous phase can be kept acidic or neutral, but is usually 1 × 10 ⁻⁵ to 1 × 10 ⁵ times by weight based on the amount of ruthenium used. Wherever it may be,
Regarding the existence form, it is not always necessary that the whole amount is dissolved in the aqueous phase.

The reaction pressure of the present invention is generally from 10 to 200.
atm, preferably 20 to 70 atm. Further, in the present invention, the reaction temperature is generally 50 to 250 ° C.,
Preferably it is 100-200 degreeC. Although the production method of the present invention can be applied to both the batch reaction system and the continuous reaction system, it is a very effective production method in the continuous reaction system.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on examples and comparative examples. The conversion of benzene, the selectivity and yield of cyclohexene, and the SV value of the condensing tube shown in the following Examples and Comparative Examples are values calculated by the following formula based on the concentration analysis values of the experiment. is there.

[0025]

(Equation 1)

The sulfur compound concentration in hydrogen used in the examples and comparative examples is a value measured by the following method. The measurement of the sulfur compound concentration in the raw material hydrogen gas was performed by sampling according to the method shown in FIG. 3 / 4B connection joint (2) and needle valve (3) (Swagel
ok Co., Ltd. SS-4L), and then using a Teflon tube (4) having an outer diameter of 3 mm, connecting the tip of the needle valve and the inlet of the gas meter (8), and then connecting the needle valve (3). Was gradually opened, and the measurement gas was allowed to flow through the sampling line at a flow rate of SV = 6500 for 24 hours or more.

Next, after cooling the concentrating tube with a refrigerant for 5 minutes or more, the Teflon tube was connected to the inlet of the concentrating tube and the silicon tube was connected to the outlet of the concentrating tube, and the measurement gas was introduced into the concentrating tube.
The introduction rate was set at SV = 6500, the measured gas sampling amount was about 2 liters, and the gas temperature of the gas meter and the sampling gas amount at that time were recorded. Next, the concentrating tube was connected to a heating introduction device, and the sampled gas was introduced into the gas chromatograph. The absolute amount of the sulfur compound was determined from the calibration curve previously obtained for the peak height or peak area obtained by the data processor, and the sulfur compound concentration was calculated from the collected gas amount. The calibration curve was prepared as follows.

As a standard gas generator, a permeator (PD-1B-2) manufactured by Gastech Co., Ltd. was used, and a standard gas of about 0.2 vol ppm was prepared with a permeation tube. Next, this gas was injected into a 2 ml syringe (# 1 manufactured by Hamilton).
002) and previously treated with hydrogen sulfide
0 ml cylinder (304L-HDF4-3 manufactured by Swedish Rock Co., Ltd.)
00-EP). Here, the cylinder previously treated with hydrogen sulfide has been subjected to the following treatment.

Using a SUS cylinder with a mirror-finished surface, the interior of the cylinder is further filled with hydrogen sulfide of about 20 vol.
After flowing for more than 24 hours at 1 ppm, 24
After leaving the inside of the SUS cylinder with the cylinder hydrogen for more than an hour, 1 ml of gas of about 0.2 vol ppm of hydrogen sulfide was collected with a syringe, injected into the SUS cylinder, and diluted with the cylinder hydrogen to about 8 atm. Next, the mixture was concentrated in a concentration tube and introduced into a gas chromatograph. Preparation gas 1 whose peak height obtained by the data processor is 0.2 volppm of hydrogen sulfide
of the peak height when directly injecting
The processing in the cylinder (the above operation) was repeated so as to fall within the range of 0% to 100%.

The cylinder previously treated with hydrogen sulfide was filled with hydrogen (manufactured by Teisan) up to about 8 atm. The gas in this is diluted about 1000 times, about 0.2volpp
The gas of b can be prepared. This cylinder was introduced into a concentration tube S (manufactured by Shimadzu) cooled to 5 atm for at least 5 minutes with liquid argon, liquid oxygen, or liquid nitrogen up to 1 atm. The introduction speed at this time is SV
= 6500, a gas meter was attached to the outlet of the concentrating tube, and the introduced amount was read. Next, the concentrating tube was set in a heating and introducing device (FLS-1 manufactured by Shimadzu), and the temperature was raised from the refrigerant temperature to 60 ° C. for 2 minutes and introduced into a gas chromatograph device (14B manufactured by Shimadzu). Simultaneously with the introduction, a data processor (Chromatopack C-R6A manufactured by Shimadzu) was started, and the retention time and peak height or peak area were determined. The concentration in the cylinder was calculated from the amount of the diluted gas and the correct concentration (calculated from the reduction of the permeation tube). The absolute amount of the sulfur compound was calculated from the introduced amount ml and the concentration in the cylinder. The above operation was repeated while changing the amount of the syringe to be collected to 1 ml, 5 ml, and 10 ml to prepare a calibration curve of the peak height or peak area and the absolute amount of concentration.

The gas chromatography conditions and data processor conditions are shown below.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

Example 1 A ruthenium hydride catalyst containing 6% by weight of zinc obtained by reducing ruthenium hydroxide containing zinc hydroxide in advance (average crystal) 10 g, 50 g of zirconia as dispersant
(Average crystallite diameter about 200mm), water 1400ml, ZnSO4.7H
245 g of 2O (special grade manufactured by Wako Pure Chemical Industries, Ltd.) was added to prepare a catalyst slurry.

The autoclave was subjected to a high-order desulfurization using a copper-zinc-aluminum desulfurizing agent, and further Ru / Al ₂ O ₃
The sulfur compound obtained by introduction into the catalyst is 0.1%.
Hydrogen and benzene of 1 volppb or less are introduced, and 30a
A continuous reaction was performed for 1400 hours under the conditions of tm and 150 ° C. During the continuous reaction, the supply amount of benzene was 200 ml / h, the supply amount of hydrogen was 60 liter / h, and the amount of catalyst slurry and product oil containing unreacted benzene was withdrawn from the reactor was 10 ml / h.
It was 00 ml / h. The extracted catalyst slurry was continuously returned to the reactor again. Further, water contained in the extracted product oil was separated by cooling the oil, and returned to the reactor again to prevent the water of the catalyst slurry and the dissolved zinc sulfate from decreasing. In these experiments, the reaction was all carried out under the condition that two liquid phases, an oil phase and an aqueous phase, were present, and the pH in the aqueous phase was all acidic or neutral.

280 ml of the catalyst slurry after the continuous reaction was recovered, charged into an autoclave having an inner volume of 1 liter and coated with Teflon, and the inside gas was sufficiently replaced with hydrogen. After the temperature was raised to 140 ° C. while stirring, the pressure was increased to 50 atm by introducing high-pressure hydrogen. Immediately after the completion of the pressure increase, 140 ml of liquid benzene was injected into the autoclave as a unit, and the reaction pressure was increased to 50 atm while the hydrogen was injected. A batch reaction was performed at 140 ° C. under high-speed stirring. Also, during this batch reaction,
A part of the reaction solution was withdrawn over time, and the composition in the oil was analyzed by gas chromatography. From the analytical values thus obtained, the selectivity of cyclohexene at a benzene conversion of 50% was determined by interpolation. Table 3 shows the results.

As shown in Table 3, the selectivity of cyclohexene was 82% and the yield was 41% at a benzene conversion rate of 50% of the catalyst slurry after continuous reaction for 1400 hours, which was a high selectivity and a high yield. Was.

[0038]

Comparative Example 1 A continuous reaction was carried out under the same conditions as in Example 1 using hydrogen having a sulfur compound concentration of 5 volppb measured by the above-mentioned measuring method. The sulfur compound concentration was 5 volp
Hydrogen as pb was prepared by adding a sulfur compound to hydrogen having a sulfur compound concentration of 0.1 volppb or less used in Example 1.

The catalyst slurry after the continuous reaction for 1400 hours was recovered, and a batch reaction was carried out.
Selectivity of cyclohexene at 0% 77%, yield 3
It was reduced to 8.5%. Table 3 shows the results.

[0040]

Comparative Example 2 A continuous reaction was carried out under the same conditions as in Example 1 using hydrogen having a sulfur compound concentration of 100 volppb as measured by the above-mentioned measuring method. Incidentally, when the sulfur compound concentration is 100
As the hydrogen as volppb, hydrogen before the high-order desulfurization treatment used in Example 1 was used. As a result of collecting the catalyst slurry after the continuous reaction for 1400 hours and performing a batch reaction, the selectivity of cyclohexene at a benzene conversion rate of 50% was 60%.
% And the yield was 30%. Table 3 shows the results.
Shown in

[0041]

Example 2 A continuous reaction was carried out under the same conditions as in Example 1 using hydrogen having a sulfur compound concentration of 0.2 volppb measured by the above-mentioned method. The sulfur compound concentration was 0.2
Hydrogen which is volppb was prepared by adding a sulfur compound to hydrogen having a sulfur compound concentration of 0.1 volppb or less used in Example 1.

As a result of collecting the catalyst slurry after the continuous reaction for 1400 hours and performing a batch reaction, the benzene conversion rate was 5%.
82% selectivity of cyclohexene at 0%, yield 41
% And high selectivity and high yield were maintained. Table 3 shows the results.
Shown in

[0043]

Example 3 A continuous reaction was carried out under the same conditions as in Example 1 using hydrogen having a sulfur compound concentration of 1 volppb measured by the above measuring method. The sulfur compound concentration is 1 volp
Hydrogen as pb was prepared by adding a sulfur compound to hydrogen having a sulfur compound concentration of 0.1 volppb or less used in Example 1.

As a result of recovering the catalyst slurry after the continuous reaction for 1400 hours and performing a batch reaction, the benzene conversion rate was 5%.
81% cyclohexene selectivity at 0%, yield 4
High selectivity and high yield of 0.5% were maintained. Table 3 shows the results.

[0045]

[Table 3]

[0046]

According to the method of the present invention, it is possible to produce cycloolefins stably for a long period of time without reducing the selectivity and yield, without the catalyst system of the partial hydrogenation reaction being poisoned by sulfur. it can.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for measuring a sulfur compound concentration used in the present invention.

FIG. 2 is a graph showing the relationship between the concentration of sulfur compounds in raw material hydrogen and the selectivity of cyclohexene obtained in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 1 Existing piping 3 / 4B 2 3 / 4B Connection joint 3 Needle valve 4 Teflon tube 5 Concentrator tube 6 Refrigerant 7 Silicon tube 8 Gas meter 9 Atmospheric vent

Claims (4)

[Claims] 1. A method for producing a cycloolefin by subjecting a monocyclic aromatic hydrocarbon to partial hydrogenation reaction with hydrogen in the presence of a ruthenium catalyst, water and metal sulfate, wherein the hydrogen used has a sulfur compound concentration of 1 volppb or less. A method for producing a cycloolefin. 2. The method according to claim 1, wherein the concentration of the sulfur compound is a concentration measured by a method of directly introducing the hydrogen into a concentration tube in a measurement method of gas chromatography-solid collection method. A method for producing a cycloolefin. 3. The method according to claim 2, wherein the sulfur compound concentration is a concentration measured when the SV of the concentrating tube is 20,000 or less in a gas chromatography-solid collection method. The method for producing the cycloolefin described above. 4. The method according to claim 1, wherein the concentration of the sulfur compound is a concentration measured after flowing a measurement gas through a sampling line for at least one hour in a gas chromatography-solid collection method. 4. The method for producing a cycloolefin according to 2 or 3.