JPH0987209A - Production of cycloolefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a cycloolefin cover a long period of time with regenerated use of catalyst by continuous partial hydrogenation of a monocyclic aromatic hydrocarbon using a reactor made of a specific material through such catalytic process that part of a ruthenium catalyst in the reactor is extracted, put to acid cleaning and then circulated in the reactor. SOLUTION: This cycloolefin is obtained by continuous partial hydrogenation of (D) a monocyclic aromatic hydrocarbon using a reactor with its liquor contact portion made of a nickel-contg. material through such a catalytic process that, in the presence of (A) a ruthenium catalyst, (B) a metal salt and (C) water, at least part of the component A in the reactor is extracted, put to acrid cleaning, and if necessary, washed with water until the washings comes to pH6-7, and also, where appropriate, put to reduction treatment, and then circulated in the reactor.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for partially hydrogenating a monocyclic aromatic hydrocarbon to produce cycloolefins. In particular, it relates to a method for partially hydrogenating benzene to produce cyclohexene. Cyclohexene is a compound useful as an important intermediate material such as a raw material of polyamide such as lactams and dicarboxylic acids, a raw material of lysine, a medicine and an agricultural chemical.

[0002]

2. Description of the Related Art As a method for producing cycloolefins by partial hydrogenation of monocyclic aromatic hydrocarbons, a ruthenium metal is mainly used as a catalyst, and a hydrogenation reaction is generally performed in the presence of water. . As the ruthenium catalyst, a method of using fine metal ruthenium fine particles as they are (Japanese Patent Laid-Open No. 6-58242)
1-50930, JP-A-62-45541, JP-A-62.
-45544), or a method using a catalyst in which ruthenium is supported on a carrier such as silica, alumina, barium sulfate, zirconium silicate (JP-A-57-13092).
6, JP-A-61-40226, JP-A-4-74141
Etc.) and many other proposals have been made. In addition, in the above reaction system, it is generally preferable to allow the presence of a metal salt such as zinc sulfate or cobalt sulfate to increase the selectivity and yield of the corresponding cycloolefin.

Most of the above-mentioned known methods add a metal salt or an additive such as an acid or an alkali to the reaction system. The reason why these additives are required is that, in a reaction system in which no additives are added, the reaction rate is usually improved, but the selectivity of the target cycloolefin is significantly reduced, and therefore it is not industrially suitable. It is thought that this is for judgment.

However, there is a problem that additives such as metal salts show strong corrosiveness in a reaction system, especially in a high temperature aqueous solution, and accelerate deterioration due to wear and loss of a reaction apparatus and a catalyst (Dye and Chemicals, Vol. 31). No. 11, p297-308, 19
1986). Therefore, conventionally, a method of applying nickel coating to the liquid contact portion of the reactor (JP-A-62-67033) or a method of using titanium or zirconium (JP-A-62-67033).
81331), and a method using a nickel-based alloy containing chromium and / or molybdenum (JP-A-6-128177).
Although it has been proposed to apply a generally expensive material to the reactor, problems such as corrosion of the reactor and hydrogen embrittlement must be taken into consideration in the long term.

On the other hand, as a method for regenerating the catalyst deteriorated in this reaction, there are the following known techniques depending on the deterioration factors. Method of alkaline cleaning (Japanese Patent Application No. 3-4121)
6), a method of contacting with oxygen in the liquid phase (JP-A-1-15
9059), a method of reducing the hydrogen partial pressure to retain the catalyst (Japanese Patent Publication No. 3-68453).

[0006]

In a process for producing a cycloolefin, a monocyclic aromatic hydrocarbon is partially reduced with hydrogen in the liquid phase at high temperature and high pressure in the presence of a ruthenium catalyst, water and a metal salt compound. And / or in the case of regenerating a catalyst with reduced selectivity, the known methods described above
Catalyst regeneration is still not sufficient. In particular, austenitic stainless steel, which is considered to be advantageous for hydrogen embrittlement, or nickel-containing material such as Hastelloy steel is used as a material for the apparatus, and cycloolefin is continuously produced in the presence of a metal salt compound. In doing so, there was no detailed study example on the method of regenerating the catalyst deteriorated by the poisoning component derived from the nickel-containing material, and it was an essential subject to establish an effective regeneration method.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to improve these drawbacks of the prior art and to provide an industrially advantageous process for producing cycloolefin. In particular, using a nickel-containing material for the liquid contact part of the device, we did not find an example in which the catalyst life when a metal salt compound was present in the reaction system was examined in detail. Was not known. The present inventors, when using a nickel-containing material as the material of the apparatus, and when a metal salt compound is present in the reaction system and continuously producing cycloolefin over a long period of time, the catalytic activity is A phenomenon was observed that decreased over time. The present invention has been reached by studying an effective regeneration method for a catalyst whose activity has decreased.

That is, the gist of the present invention is a method for producing a cycloolefin in which a monocyclic aromatic hydrocarbon is continuously partially hydrogenated in the presence of a ruthenium catalyst, a metal salt and water.
A method for producing a cycloolefin characterized in that a nickel-containing material is used for the liquid contact part of the reactor, and at least a part of the catalyst in the reactor is extracted, acid washed and circulated in the reactor. .

The present invention will be described in more detail below. The ruthenium catalyst used in the present invention may be used as it is as the reduced metal particles containing ruthenium, or may be used as a supported catalyst supported on a carrier. Examples of the carrier include silica, alumina, silica-alumina, zeolite, activated carbon, general metal oxides, complex oxides, hydroxides, sparingly water-soluble metal salts and the like. Furthermore, as one of the preferred forms of the above carrier, a carrier obtained by modifying a silica carrier with a transition metal compound, particularly a carrier obtained by modifying zirconia with silica, and a carrier containing a zirconium silicate such as zirconium silicate are exemplified.

The ruthenium catalyst may be ruthenium alone or may contain a promoter metal component. Examples of the promoter metal component include zinc, manganese, iron, cobalt, lanthanum, gold, silver and copper. When using a promoter metal, the atomic ratio of the promoter metal to the ruthenium atom is usually 0.01 to 10, preferably 0.1 to 5.
And When each catalyst component is loaded on the carrier, it is usually used as a catalyst by loading 0.001 to 10% by weight, preferably 0.02 to 5% by weight on the carrier. Preparation of such a catalyst is carried out according to a commonly used method for preparing a supported metal catalyst. As a raw material compound for each metal component of the catalyst, a halide, nitrate, acetate, sulfate of each metal, a complex compound containing each metal, or the like is used. The co-supporting component with ruthenium may be supported on the carrier at the same time as the ruthenium raw material, or may be supported after supporting ruthenium in advance, or after supporting these metals first and then supporting ruthenium afterwards. Good.

As the preparation method, after dipping the carrier in the catalyst component liquid, the solvent is evaporated to evaporate the solvent to fix the active component, and the catalyst active component liquid is sprayed while keeping the carrier dry. Or a known impregnation-supporting method such as a method of immersing the carrier in the liquid of the catalytically active component and then filtering it. Further, as the solvent used when supporting the active ingredient at the time of catalyst preparation, water or alcohol,
Organic solvents such as acetone, tetrahydrofuran, hexane and toluene are used. Of these, water and alcohol are preferable.

The prepared catalyst is used after being reduced and activated. 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. Of these, catalytic reduction with hydrogen gas is preferable, and usually 80 to 500.
The reductive activation is carried out under the condition of ℃, preferably 100 to 450 ℃. If the reduction temperature is lower than 80 ° C, the reduction rate of ruthenium is significantly reduced, and if it is higher than 500 ° C, agglomeration of ruthenium is likely to occur, which causes a decrease in cycloolefin production yield and selectivity.

The present invention uses the above ruthenium catalyst. When the present invention is carried out, the monocyclic aromatic hydrocarbons used as the reaction raw materials are benzene, toluene, xylene, and lower ones having about 1 to 4 carbon atoms. Examples thereof include alkyl group-substituted benzenes. The reaction system of the present invention requires the presence of water. Although the amount of water varies depending on the reaction mode, it is generally 0.01 to 10 times by weight, preferably 0.1 to 5 times by weight of the monocyclic aromatic hydrocarbon. Under these conditions, two phases are formed: an organic liquid phase (oil phase) containing the raw materials and products as main components, and a liquid phase (water phase) containing water. When the ratio between the oil phase and the aqueous phase is extreme, it is difficult to form two phases, and liquid separation is difficult. Further, if the amount of water is too small or too large, the effect of coexistence decreases, and if the amount of water is too large, it is necessary to enlarge the reactor, which is not preferable.

Further, in the reaction system of the present invention, a metal salt is used together as in a conventionally known method. Examples of the type of metal salt include nitrates, chlorides, sulfates, acetates, phosphates and the like of Group 1 metals, Group 2 metals, Group 12 metals of the Periodic Table, or metals such as manganese and cobalt. It is preferable to use zinc in combination. The amount of metal salt used is 1 × usually 10 ⁻⁵ to 1 times by weight, preferably 10 ⁻⁴ to water of the reaction system.
It is 0.1 times the weight. The pH of the aqueous phase of the reaction solution is not particularly limited, but since a high reaction rate can be expected, pH
Is usually about 2 to 7 and preferably acidic or neutral.

As the reaction conditions of the present invention, the reaction temperature is
It is usually selected from the range of 50 to 250 ° C, preferably 100 to 220 ° C. When the temperature is 250 ° C or higher, the selectivity of cycloolefin is lowered, and when the temperature is 50 ° C or lower, the reaction rate is remarkably lowered, which is not preferable. The hydrogen pressure during the reaction is usually selected from the range of 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 and it is uneconomical in terms of equipment.

The effect of the present invention is particularly exerted by continuously carrying out the reaction. The continuous reaction is usually carried out in a state where the liquid phase is suspended by continuously supplying a monocyclic aromatic hydrocarbon and hydrogen to a reaction system in which a catalyst, a metal salt and water are present. Further, a suspension containing the reaction product is continuously taken out from the reaction system, and is separated into an aqueous phase containing the catalyst and an oil phase containing the reaction product, and the oil phase is taken out. The olefin will be refined. The type of the reactor is not particularly limited, and a general reactor such as a reactor having one tank or two or more continuous stirring tanks and a tube reactor can be used. The reaction time, that is, the residence time of the starting monocyclic aromatic hydrocarbon in the reaction system is arbitrary depending on the type of the reactor and the amount of catalyst, but is usually about 5 to 100 minutes.

An example of a method for separating the reaction liquid into an oil phase and an aqueous phase is a method in which an oil / water separation weir is provided in the reactor and only the oil phase is taken out. It is also conceivable to take out a part of the reaction liquid with a liquid circulation pump and supply it to an oil-water separation tank provided outside the reactor to separate it.The aqueous phase containing the separated catalyst is circulated to the reactor. Can be reused. Cycloolefin can be easily purified and recovered from the separated oil phase by a known method such as distillation. Further, at least a part of the catalyst in the aqueous phase may be appropriately extracted, a regeneration operation may be performed as described below, and the regenerated catalyst may be circulated in the reactor.

When the partial hydrogenation source reaction is carried out for a long time under the reaction conditions as described above, the requirements for selecting the material of the wetted portion of the reactor are that hydrogen embrittlement does not occur, high temperature,
It is important to select a material that has sufficient strength even under high pressure, is unlikely to cause corrosion, and has less deterioration in the performance of the catalyst due to the metal components eluted from the material. Use a nickel-containing material for the liquid part.

Further, an important requirement of the present invention is that the catalyst whose activity has been lowered by the above reaction is washed with an acid to reduce the amount of nickel material-derived components accumulated on the catalyst and reuse it. The acid washing method is usually carried out with a catalyst
It can be carried out by washing with an aqueous acid solution of H4 or less. As the acid used, mineral acids such as sulfuric acid, hydrochloric acid and nitric acid are preferably used, and sulfuric acid is particularly preferable. The washing temperature is usually room temperature to 300 ° C, preferably 40 to 100 ° C. Alternatively, the catalyst may be washed with water before the acid washing and then the acid washing.

Next, after washing the catalyst with water after washing with the acid aqueous solution, it is usually desirable to wash with water until the pH of the washing liquid becomes about 6 to 7. By carrying out such water washing, it is possible to prevent the used acidic substance from being mixed into the reaction system and exerting a bad influence on the reaction. Further, it is also suitable to reduce the catalyst after such acid washing and water washing. The reduction is carried out by the above method, but the temperature condition can be lower than the condition for forming the metal ruthenium from the ruthenium raw material, and is usually selected from the room temperature to 500 ° C. The temperature is preferably room temperature to 300 ° C.

The catalyst regeneration method of the present invention can be carried out by extracting a part or all of the metal salt aqueous solution slurry containing the catalyst from the reaction system and performing the above-mentioned acid washing. By increasing the frequency of acid cleaning, it is possible to control the amount of components derived from the nickel-containing material in the catalyst in the reactor to be low. However, when the frequency is excessively increased, it is possible to maintain the catalyst activity at a high level, but there is also a drawback that the cost related to the regeneration treatment industrially increases, and the type of metal salt used, It may be carried out at an appropriate frequency in consideration of the concentration, the type of material used, and the deterioration rate determined from the catalyst performance.

[0022]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. The conversion rate and selectivity shown in Examples and Comparative Examples are defined by the following equations.

[0023]

[Equation 1]

Example 1 (Production of catalyst) Zirconium oxynitrate dihydrate 0.8
Silica (Fuji Silysia Chemical, trade name: CARIACT-Q-
50) 8.0 g was added, and after dipping at room temperature, water was distilled off and the residue was dried. Next, it was calcined at 1000 ° C. for 4 hours under air flow to prepare a silica carrier modified with 5% by weight of zirconia with respect to silica.

The above-mentioned zirconia-modified silica carrier was added to an aqueous solution containing a predetermined amount of ruthenium chloride and zinc chloride, immersed at 60 ° C. for 1 hour, water was distilled off and dried. Furthermore, in a hydrogen stream, it is activated by reducing at 200 ° C. for 3 hours, and ruthenium and zinc are added to the carrier at about 0.5 each.
A catalyst supporting wt% was obtained.

(Partial Hydrogenation Reaction of Benzene) Nickel-chromium-molybdenum steel was used in the liquid contact part, and 250 ml of water was placed in a continuous flow reactor having an oil-water separation tank and an internal volume of 1 L.
30 g of zinc sulfate heptahydrate and 24 g of the above catalyst were charged.
Further, hydrogen gas was introduced, the reaction pressure was 5.0 MPa, the temperature was 150 ° C., benzene was supplied at 300 ml / Hr, and the partial hydrogenation reaction was continuously performed while performing high-speed stirring. The residence time of benzene is 35 minutes. During the reaction, the reaction solution oil phase was continuously withdrawn from the oil / water separation tank and analyzed by gas chromatography. 3 hours after the start of the reaction, 87.
Table 1 shows the benzene conversion rate and cyclohexene selectivity after 5 hours.

[0027]

[Table 1]

(Catalyst washing) After 87.5 hours, the entire amount of catalyst slurry was extracted from the reactor. After filtering off the catalyst,
The catalyst was resuspended in pure water. Further, the catalyst was filtered off, and the zinc content of the filtrate was measured by ICP emission spectroscopy. Suspension in pure water and filtration of the catalyst were repeated until the zinc concentration of the filtrate was 1 ppm or less. On the other hand, when the concentration of the metal component derived from the material in the zinc sulfate aqueous solution excluding the catalyst was taken out from the reactor and measured by ICP emission spectrometry, 33.3 ppm of nickel and 1.4 ppm of iron were detected.

Next, the catalyst after washing with water was charged into a 1N sulfuric acid aqueous solution and stirred at room temperature for 1 hour. After washing with sulfuric acid, the catalyst was thoroughly washed with water, and then the catalyst was dried. When the contents of nickel and iron in the catalyst were measured by a fluorescent X-ray method, both were found to be 0.002 with respect to 1 part by weight of ruthenium.
It was less than or equal to parts by weight.

(Evaluation of Regenerated Catalyst in Batch Reaction) The catalyst washed with sulfuric acid and washed with water was reduced at 100 ° C. in a hydrogen stream. In a titanium autoclave with an internal volume of 0.5 L,
150 ml of 6% zinc sulfate aqueous solution, 2.5 above regenerated catalyst
g, 100 ml of benzene were charged, the reaction temperature was 150 ° C,
57 Nl / Hr of hydrogen under a reaction pressure of 5.0 MPa
And stirred at a rotation speed of 1000 rpm to carry out a partial hydrogenation reaction of benzene. The reaction results 75 minutes after the start of the reaction are shown in Table 2.

Comparative Example 1 The reacted catalyst obtained in Example 1 was washed with water in the same manner. The performance of such a catalyst was evaluated by the batch reaction method described in Example 1 except that such a catalyst was used. The reaction results 150 minutes after the start of the reaction are shown in Table 2.

[0032]

[Table 2]

[0033]

According to the present invention, a deteriorated catalyst can be appropriately and effectively regenerated, and a cycloolefin can be stably produced from a monocyclic aromatic hydrocarbon over a long period of time.

Claims (3)

[Claims] 1. A ruthenium catalyst containing a monocyclic aromatic hydrocarbon,
In the method for producing a cycloolefin in which partial hydrogenation is continuously carried out in the presence of a metal salt and water, a nickel-containing material is used in the liquid contact part of the reactor, and at least a part of the catalyst in the reactor is withdrawn, A method for producing a cycloolefin, which comprises washing with an acid and circulating it in a reactor. 2. The method according to claim 1, wherein after the acid washing, the catalyst washed with water until the washing water has a pH of 6 to 7 is circulated in the reactor. 3. The method according to claim 1, wherein after the acid washing, the washing water is washed with water until the pH of the washing water becomes 6 to 7, and then the reduced catalyst is circulated in the reactor.