JP2003128615A - Production method of cyclohexanone and/or its ketal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process of a cyclohexanone and/or its ketal from a benzen, capable of reducing generation of a cyclohexane by-produced with a cyclohexene in partial hydrogeneration process of benzen, that can lessen the loads of the subsequent dehydrogeneration process. SOLUTION: The production method of a cyclohexanone and/or its ketal comprises the following consecutive process (1) to (5): (1) a partial hydrogeneration process that partially hyrogenerates benzene under acidic condition, (2) an oxidation reaction process that oxidize the reaction mixture obtained from the process (1), (3) a recovery process that recovers unreacted materials from the reaction liquid after the oxidation reaction process (2), (4) a dehydrogeneration process that obtains benzene from unreacted materials recovered from the process (3), (5) a recirculation process that recirculates the benzene obtained from the process (4). The amount of cyclohexane by- produced with cyclohexene in the process (1) is 24 mol% and less.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing cyclohexanone and / or its ketal from benzene.

[0002]

2. Description of the Related Art Benzene is partially hydrogenated to cyclohexene, and the obtained cyclohexene is oxidized with cyclohexane, which is a by-product, to cyclohexanone. Then, cyclohexanone is removed from the obtained reaction solution, and a reaction mixture containing the remaining cyclohexane is removed. JP-A-56-43227 discloses a method for continuously producing cyclohexanone by performing a dehydrogenation reaction and then returning the obtained benzene to a partial hydrogenation step (the following reaction scheme). Although it is described here that a known method can be used for the partial hydrogenation reaction step, a method of reacting in the presence of an alkaline agent is disclosed as a suitable method, and a reaction product liquid containing 25 to 75 mol% of cyclohexane is disclosed. It is described as suitable to obtain.

[0003]

[Chemical 1]

Cyclohexanone useful as a precursor of caprolactam is obtained by oxidizing cyclohexane in the presence of a catalyst, if necessary, and dehydrogenating the resulting cyclohexanone-cyclohexanol mixture.
It is produced by a method of dehydrogenating cyclohexanol obtained by hydrating cyclohexene. However, in the former method, the reaction products are susceptible to successive oxidation during the oxidation of cyclohexane, so it is necessary to keep the conversion rate at a fairly low level, and it is necessary to circulate a large excess of unreacted cyclohexane. As a result, the process is not high in energy efficiency. Further, in the latter method, the yield of the hydration reaction is not sufficient, when cyclohexene is extracted and separated from a mixture of benzene and cyclohexane having extremely close boiling points, and when a mixture of cyclohexanone-cyclohexanol having a high boiling point is used in an equimolar amount. However, there is a problem that a large amount of energy is consumed when only cyclohexanone is separated from.

[0005]

As described above, an industrial process for reusing benzene obtained by producing cyclohexene from benzene, then oxidizing it to cyclohexanone which is a target product, and further dehydrogenating an unreacted product. Currently, no effective method has been found yet. In particular,
In JP-A-56-43227, alkaline conditions are adopted when partially hydrogenating benzene, and in the obtained reaction product liquid, cyclohexane and cyclohexane are produced as a large amount of 25 mol% or more as a by-product. It was A large amount of cyclohexane generated here needs to be returned to benzene again in the dehydrogenation process as a post-process, and there is a problem that the dehydrogenation process has a heavy load. Therefore, in the partial hydrogenation step, there has been a demand for a method capable of maintaining a large amount of cyclohexene produced and reducing the amount of by-produced cyclohexane as much as possible.

[0006]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a method for reducing the amount of cyclohexane produced as a by-product with cyclohexene in the step of partially hydrogenating benzene, and as a result, under acidic conditions, The present inventors have found that the amount of cyclohexane produced can be reduced by the reaction, and have reached the present invention.

That is, the gist of the present invention is to provide a method for producing cyclohexanone and / or its ketal by partially hydrogenating benzene and then oxidizing the resulting cyclohexene, wherein the following (1) to (5) A method for producing cyclohexanone and / or its ketal, which comprises sequentially passing through a series of steps. (1) Partial hydrogenation of benzene under acidic conditions to obtain a reaction mixture containing cyclohexene as a main component (2) Partial hydrogenation step (2) Oxidizing the reaction mixture obtained in step (1) to cyclohexanone and / or cyclohexanone Step (3) for obtaining ketal Oxidation reaction step (3) Step (4) for recovering unreacted material containing cyclohexane, cyclohexene and benzene from the product liquid after the oxidation reaction in step (2) Dehydrogenation of unreacted material recovered in step (3) Dehydrogenation step (5) to obtain benzene by reusing the benzene obtained in step (4) in the partial hydrogenation step of step (1)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below step by step.

(1) Partial Hydrogenation Step of Benzene The partial conversion of benzene into cyclohexene of the present invention is characterized by carrying out the reaction under acidic conditions. Here, the acidic conditions are specifically pH 3 to 7, preferably p
H 3.5 to 6.5, more preferably pH 4 to 6.

In the partial hydrogenation reaction, it is preferable to carry out the reaction in 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 that of benzene. Under such conditions, the organic liquid phase (oil phase) containing the raw material and the product as main components and the liquid phase containing water (water phase) will form two phases unless stirring is performed. However, when the ratio of the oil phase and the water phase is extremely large, it becomes difficult to form the two phases and the liquid separation becomes difficult. Also, the effect of water presence is reduced when the amount of water is too small or too large. Furthermore, in the present invention, it is preferable to contain a metal salt compound in water. The metal salt compound is a Group 1 metal, a Group 2 metal, or zinc,
Sulfates, chlorides, acetates of metals such as manganese and cobalt,
Phosphate etc. are illustrated. The amount of the metal salt used is usually 1 × 10 ⁻⁵ to 1 times by weight, preferably 1 × 10 ⁻⁴ to 0.1 times by weight, relative to the water in the reaction system.

It is preferable to use a Group 8 metal catalyst for this reaction. A particularly preferred metal is ruthenium. Examples of the raw material of the catalyst include halides, nitrates, hydroxides, complex compounds, alkoxides and the like. The catalyst may be used in combination with another metal component as a co-catalyst component. By adding a co-catalyst, it is possible to further exert the effect of the present invention. As a promoter component, zinc, iron, cobalt,
Manganese, gold, lanthanum, copper and the like are effective, and zinc is particularly preferable. When a promoter metal is used, the atomic ratio of promoter metal to ruthenium atom is usually 0.01-2.
It is 0, preferably 0.1-10.

The catalyst used is a metal oxide such as silica, alumina, titania or chromina; a composite oxide such as silica-alumina, silica-zirconia or zirconium silicate; a zeolite; activated carbon; a metal such as barium sulfate or calcium sulfate. Salt: A supported type in which a carrier such as a hydroxide or a poorly water-soluble metal salt is supported, or a non-supported type may be used. Among the above carriers, carriers having the following properties can be preferably used. That is, when the pore volume and the pore distribution are measured by the mercury intrusion method, the pore diameter of 75 to
The total pore volume of 100,000 angstroms is 0.2
10 to 10 ml / g, preferably 0.3 to 5 ml / g, and a total pore volume of 75 to 100,000 Å, and a pore volume of usually 250 Å or more. Of 50% or more, preferably 70% or more. Pore diameter is 2
If the proportion of pores having a size of less than 50 angstrom is too large, the selectivity tends to be lowered, which is not preferable.

As a method for activating the catalyst, 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,
In the hydrogen-containing gas atmosphere, there may be mentioned a method of calcination under conditions of usually 80 to 500 ° C., preferably 100 to 450 ° C. for reduction activation.

In the present invention, the catalyst obtained by the above-described method is usually used as a catalyst. By subjecting such a catalyst to the water treatment described below, a catalyst having improved cyclohexene selectivity can be obtained. It is also possible to obtain The water treatment conditions are usually 0.01 to 100 times by weight of the above catalyst (ruthenium reduced product),
It is preferably carried out by immersing in 0.1 to 10 times by weight of water. Also, usually, from normal pressure to under pressure, room temperature to 250
C., preferably room temperature to 200.degree. C., usually 10 minutes or longer, preferably 1 to 20 hours.

The water used in the above contact treatment may be pure water or an aqueous solution containing a metal salt. Further, the catalyst after the water contact treatment is usually dried and then subjected to a re-reduction treatment, particularly a contact treatment in a hydrogen gas atmosphere, whereby a ruthenium catalyst having a higher activity can be obtained.

As the reaction conditions for the partial hydrogenation, the reaction temperature is usually 30 to 500 ° C, preferably 50 to 300 ° C.
More preferably, it is selected from the range of 100 to 250 ° C. If the temperature is too high, the selectivity of cyclohexene will decrease, and if it is too low, the reaction rate will decrease significantly. The hydrogen pressure during the reaction is usually selected from the range of 0.1 to 20 MPa, preferably 0.5 to 10 MPa. 20 MPa
If it exceeds 0.1 MPa, it is industrially disadvantageous. On the other hand, if it is less than 0.1 MPa, the reaction rate is remarkably reduced, which is uneconomical in terms of equipment. As the reaction type, using one tank or two or more reaction tanks, it may be carried out batchwise or continuously, and it is not particularly limited, but it is industrially carried out continuously. The method is preferred.

The partial hydrogenation reaction is usually carried out with an aqueous phase containing water,
It is carried out in a four-phase system consisting of an oil phase containing raw materials and products, a solid phase containing a catalyst present in an aqueous phase, and a gas phase containing hydrogen. In this case, the reaction proceeds with these phases suspended in each other. The reaction liquid obtained by carrying out the above reaction is a mixture of an aqueous phase in which a ruthenium catalyst is dispersed and an oil phase made of an organic substance. The reaction liquid is introduced into an oil / water separator exemplified by a stationary tank, and oil / water separation is performed. Such an oil / water separator may be installed inside the reactor or outside the reactor. The aqueous phase separated in the oil-water separator is preferably recycled to the reaction system and used again in the reaction. On the other hand, the oil phase is introduced into the separation step described below.

By employing the partial hydrogenation method of the present invention, the cyclohexane content in the reaction product liquid after the partial hydrogenation reaction can be set to 24 mol% or less, preferably 22 mol% or less, and further preferably Can be 20 mol% or less. Benzene conversion is at least 2
It can be 0 mol% or more, preferably 25 to 8
It can be 5 mol%, more preferably 30 to 80 mol%. The content of the target product, cyclohexene, in the reaction product solution is at least 20 mol% or more, preferably 25 mol% or more, and more preferably 30 mol% or more.

(2) Cyclohexene Oxidation Step As a method of oxidizing cyclohexene obtained in step (1) to produce cyclohexanone and / or its ketal, known methods can be applied. For example, the Wacker type reaction is a well known example. Oxidation step of the present invention (2)
The catalysts that can be preferably used in (a) are palladium and (b)
It is composed of a component containing at least one metal other than palladium in the groups 8, 9, 10 and 14 of the periodic table and (c) a halogen-containing component. Here, the components (a) to (c) are
In the reaction system, it may exist in any form such as dissociated ions, salts or molecules.

The (a) palladium may be in a divalent to tetravalent form and can be arbitrarily selected from known ones and commercially available ones. For example, palladium halides of organic acids such as halogenated palladium such as palladium chloride and bromide, palladium nitrate, palladium nitrate, palladium acetate, potassium trifluoroacetate, palladium acetylacetonate, etc. Inorganic palladium may be mentioned. In addition, compounds in which a base derived from these metal salts is coordinated, such as [Pd (en) 2] Cl2, [P
d (phen) 2] Cl2, [Pd (CH3CN) 2] Cl2, [Pd (C6H5CN) 2] Cl2, [Pd
(C2O4) 2] 2, [PdCl2 (NH3) 2], [Pd (NO2) 2 (NH3) 2] and the like, but are not limited thereto (here, en: ethylenediamine, phen: 1, Represents 10-phenanthroline). Of these palladium sources, a divalent palladium source is preferably used for the reaction, and a chloride or nitrile compound is preferably used as a compound coordinated with the reaction.

The role of palladium in the catalyst system is expressed by the interaction with iron ions and polyhydric alcohols, and its action state is not always clear. It is essential that palladium expresses its activity by forming an active species with other catalyst components, and it is sufficient if a source of palladium sufficient to induce the essence is present in the system. (B) At least one metal other than palladium in the groups 8, 9, 10, and 14 of the Periodic Table (IUPAC Inorganic Chemistry Nomenclature 1990 Rule) includes iron, cobalt, nickel, ruthenium, and tin. , Preferably iron.

The catalyst compound serving as an iron source may be in a divalent or trivalent form. For example, iron (II) chloride, iron (II) chloride
I) and other chlorides, iron bromide (II), iron bromide (III) and other bromides, iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III) and other inorganic substances Acid salt, iron (II) acetate, iron acetate (II
I), iron (II) oxalate, iron (III) oxalate, iron formate,
It can be subjected to the reaction in the form of various salts or coordination compounds such as iron acetylacetone. Similar to palladium, it is essential that iron expresses its activity by forming an active species with other components, and it is sufficient if an iron source sufficient to induce the essence is present in the system.

The catalyst compound serving as a source of cobalt, nickel, ruthenium or tin may be in a divalent, trivalent or tetravalent form. Specifically, these chlorides, halides such as bromide, inorganic acid salts such as sulfates and nitrates, acetates, oxalates, formates, various salts such as acetylacetonato salts,
Coordination compounds are available. When the component (b) is cobalt, nickel, ruthenium or tin, it is preferably further combined with copper.

The main effect of the present invention is such (b)
Although the addition of components causes a remarkable effect of suppressing Pd precipitation, the addition of a copper compound such as CuCl or CuCl2 to this further improves the reaction rate and reduces by-products such as halogenides. As a result, a more advantageous result can be obtained. (C) The halogen is chlorine (Cl) and / or bromine (B).
r), but chloro (Cl) is particularly preferable. Halogen may be present in the reaction system as a counter anion of Pd and / or Fe. Further, a method of supplying to the reaction system as a halogenide of another catalyst component, or a method of supplying it to the reaction system in the form of HCl, HBr, etc. is also possible, but in any case, in the form of ions in the reaction system. Must exist

In the oxidation step (2) of the present invention, cyclohexene is reacted with oxygen and a polyhydric alcohol in a liquid phase in which the above-mentioned catalyst is dissolved to produce cyclohexanone and / or its ketal. The polyhydric alcohol is usually divalent to tetravalent, and among them, diols are preferable. In the case of a diol, it usually has 2 or more carbon atoms, and preferably 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms, in view of price, stability, and easiness of forming acetal or ketal. Diols, specifically, ethylene glycol, 1,3-propanediol, 1,2-dihydroxybutane, 1,2-dihydroxypropane, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1, 2-cyclohexanedimethanol, diethylene glycol, 1,2-transcyclopentanediol, 2,4-pentanediol, styrene glycol, 1,5-dihydroxycyclooctane, 1,4-dihydroxycyclooctane, 2,5-dihydroxynorbornane, 2,6-dihydroxynorbornane, 1,4-dihydroxy-2,3-dimethylbutane, , 5-dihydroxy-2,4-dimethyl pentane, cyclobutane-1,2-dimethanol, cyclohexane-1,3-dimethanol, 1,4-dihydroxy -
2,3-dichlorobutane and 2,5-dihydroxyhexane are preferred. More preferably, ethylene glycol, 1,3-propanediol, 1,2-dihydroxybutane, 1,2-dihydroxypropane, 1,4-butanediol, 1,4-cyclohexanedimethanol,
1,2-cyclohexanedimethanol, diethylene glycol, 1,2-transcyclopentanediol,
2,4-pentanediol and styrene glycol. Of course, these may be used in combination.

In the oxidation step (2) of the present invention, the reaction is preferably carried out in a liquid phase in which the catalyst is dissolved.

In the oxidation step (2) of the present invention, it is necessary to use a gas containing oxygen, but oxygen and an organic compound can form an explosive mixture at a certain temperature, a certain pressure range and a composition range. Therefore, it is necessary to avoid the danger. If the oxygen partial pressure is 0.001 MPa or more, the reaction proceeds, but if the oxygen partial pressure is low, the reaction rate becomes slow and the catalyst tends to be deactivated. In the present invention, the pressure is preferably 0.01 to 10 MPa, more preferably 0.05 to 5 MPa, but a more preferable pressure is selected from the viewpoint of safety and economy.

When the reaction temperature is 0 ° C. or higher, the reaction proceeds, but in the present invention, the temperature dependence of the reaction is large, so a higher temperature is preferable. The reaction temperature is selected in consideration of the conditions for forming an explosive mixture and the increase of by-products due to radical autoxidation, but it is generally 20 ° C to 200 ° C, preferably 4 ° C.
At a temperature of 0 ° to 180 °, an economically significant reaction rate can be obtained. The total pressure of the reaction depends on the oxygen concentration, but may be higher than the liquid phase holding pressure, but is usually 0.1
-20 MPa, preferably 0.1-15 MPa.
The reaction time (residence time) is usually 5 seconds to 20 hours, preferably 10 seconds to 10 hours.

The concentration of (a) palladium as a catalyst is 0.001 wt% or more and 10 w as [Pd2 +] based on the total weight of the reaction solution.
t% or less, preferably 0.01 wt% or more and 5 wt%
It is the following. Under high-concentration conditions, the concentration dependence of the reaction rate behaves differently than under low-concentration conditions, and the catalyst efficiency tends to deteriorate, so an efficient concentration is selected from an economical point of view.

(B) The concentration of at least one metal M other than palladium in the groups 8, 9, 10 and 14 of the periodic table can be described by (a) the relative concentration with respect to palladium. That is, usually, 0.1 <[M] / [Pd] <100 (molar ratio), and preferably 0.1 <[M] / [Pd] <10 (molar ratio). At concentrations lower than this, the reaction rate tends to decrease, and the effect of suppressing Pd precipitation, which is the main effect of the metal (b), tends to decrease. If a large amount is added, the reaction itself is not hindered, but the amount dissolved in the reaction system tends to be limited.

(C) The relative concentration of halogen with respect to Pd is usually in the range of 1 <[Cl and / or Br] / [Pd] <100 (molar ratio), preferably 0.3 <[Cl and / or Br]. / [Pd] <50. In a situation where the halogen concentration is high, there is a concern that the water in the reactor may corrode the material of the reactor. Therefore, the halogen concentration should be selected so that the catalyst system functions in a region as low as possible. In addition, a component containing a halogen derived from the catalyst system may be formed in a part of the by-product, and in this case, the continuously or regularly consumed halogen is replenished in the form of, for example, a metal salt. Better

The amount of polyhydric alcohols present in the reaction system may be a theoretical amount (1 mol) with respect to the olefin, but in the present invention, it is preferable to use it as a reaction solvent. Usually, it is 1 vol% or more and 99 vol% or less, preferably 5 vol% or more and 99 vol% or less with respect to the entire reaction volume. Further, the polyhydric alcohol is usually 1 to 100 mol, preferably 2 to 50 mol, based on the olefin. The amount of olefins present in the reaction system is 1 vol% or more and 99 vol%
The following can be selected, preferably in the range of 1 vol% or more and 50 vol% or less.

In the oxidation step (2) of the present invention, it is possible to add another component to enhance the activity and reactivity. For example, additives having an effect of promoting the oxidation reaction, such as copper compounds, alkalis, alkaline earths and rare earths may be added. Further, a method of suppressing a side reaction by adding a radical trapping agent may be adopted. Among the reactions of the oxidation step (2) of the present invention, particularly in the industrial process that is produced in large quantities such as the method for producing cyclohexanone from cyclohexene, even if the amount of impurities is small, the mass balance of the entire process is taken into consideration. , Some require efficient separation. For example, impurities such as cyclohexenone, cyclohexenol, chlorocyclohexanone, cyclohexenone ketal which are particularly difficult to separate and which may adversely affect the product should be suppressed as much as possible.

The reaction type of the oxidation step (2) of the present invention can be carried out according to a general oxidation reaction. When each component of the catalyst exists in a solution state, it is also possible to bring the olefins into contact with the gas containing oxygen for a specific reaction time in a batch reactor to allow the oxidation reaction to proceed. It is also possible to continuously supply the containing gas and olefins to proceed the oxidation reaction. On the other hand, when the catalyst component of the present invention is immobilized, the above-mentioned liquid phase reaction can be used, or the fixed bed is filled with the catalyst to obtain the corresponding olefins and oxygen in the liquid phase state. A so-called trickle bed method of supplying can be adopted.

Oxygen is supplied by a method in which a gas containing oxygen is made into fine bubbles by a stirring blade, and further, a baffle plate is provided inside the reactor to make the oxygen gas into fine bubbles, and the system is operated at a linear velocity higher than that of the nozzle. A method effective for dissolving oxygen in the reaction solution system can be adopted by a method of spraying into the inside. (Treatment after oxidation reaction) In the reaction product solution after the oxidation reaction,
Cyclohexene, the product cyclohexanone and / or
Alternatively, the ketal, the catalyst component and the polyhydric alcohol are contained. When the reaction product liquid is under pressure, the pressure may be released to some extent to lower the pressure. When the boiling points of the olefin and cyclohexanone and / or its ketal in the reaction product liquid are very different from those of the polyhydric alcohol solvent and have low boiling points, those low boiling point components (olefin and cyclohexanone and / or its ketal) are directly fed from the reaction product liquid. Can be separated by distillation. A polyhydric alcohol solution containing a catalyst component obtained as a bottom product of distillation is
It can be recycled to the oxidation reaction step.

When the boiling points of the olefin and cyclohexanone and / or its ketal are higher than those of the polyhydric alcohol solvent,
An extraction solvent such as an organic solvent which forms a two-phase with a polyhydric alcohol is added, and two phases are separated by extraction, and an extraction solvent phase containing olefin and cyclohexanone and / or its ketal and a polyhydric alcohol phase containing a catalyst component. And separate. The olefin and cyclohexanone and / or its ketal can then be recovered from the extraction solvent phase and then the cyclohexanone and / or its ketal can be removed by distillation separation. The polyhydric alcohol phase containing the catalyst component can be recycled to the oxidation reaction step. During the two-phase separation, if a trace amount of the catalyst component is mixed in the extraction solvent side containing olefin and cyclohexanone and / or its ketal, the extraction solvent phase should be extracted twice or more with a polyhydric alcohol solvent. By this, the residual amount of the catalyst component in the extraction solvent phase can be reduced to a negligible level. Also, after the first two-phase separation, a method of separating the olefin and cyclohexanone and / or its ketal from the extraction solvent phase by distillation, increasing the residual catalyst concentration in the extraction solvent phase to some extent, and then performing the extraction operation again. Is also possible.

(3) Unreacted Product Recovery Step As described above, after separating the mixed solution containing the olefin and cyclohexanone and / or its ketal from the product solution after the oxidation reaction, the target product cyclohexanone is further distilled. And / or its ketal and other unreacted substances, specifically, unreacted substances containing cyclohexane, cyclohexene and benzene are recovered. The unreacted material containing cyclohexane, cyclohexene and benzene has a lower boiling point than the target product cyclohexanone and / or its ketal, and thus can be separated by ordinary distillation. The cyclohexanone and / or its ketal obtained in the present invention is converted into the corresponding ketones and / or aldehydes by a hydrolysis reaction in the presence of water and an acid. The acid used in this case is hydrochloric acid,
Mineral acids such as sulfuric acid, nitric acid and phosphoric acid, polyacids such as heteropolyacid, ion exchange resins, solid acids such as zeolite and clay can be used. Water and polyhydric alcohols are recovered from the obtained reaction product liquid rich in aldehates and / or ketones, and the desired aldehats and ketones are separated and purified to obtain the desired aldehats. Ketones can be obtained efficiently.

The cyclohexanone and / or its ketal obtained in the present invention can be efficiently converted into the corresponding alcohols by hydrogenation reaction in the presence of water, a hydrogen source and a hydrogenation catalyst. it can. Examples of the hydrogen source include hydrogen, formalin, and sodium borohydride (NaBH4). Examples of the hydrogenation catalyst include Raney Ni, Raney Co, oxides containing Cu-Cr, and Pd, Pt, Ru, etc. Examples thereof include a catalyst in which a group metal is supported on various carriers, a complex catalyst having a group 8 metal such as Ru, Pt, or Pd as a central metal. From the reaction product liquid rich in alcohols obtained by the hydrogenation reaction, water or the alcohol forming cyclohexanone and / or its ketal is recovered, and the target alcohol is separated and purified to obtain the target. Alcohols can be obtained efficiently.

(4) Dehydrogenation step The unreacted material containing cyclohexane and cyclohexene recovered in step (3) is supplied to the dehydrogenation step without separating each component in advance and converted into benzene. Here, the content of cyclohexane in the unreacted material used for dehydrogenation is preferably 37.5 mol% or less. As a dehydrogenation method, in the presence of a catalyst, cyclohexane is usually passed under gas phase conditions to convert it into benzene. A method for producing benzenes from cyclohexanes is widely known, and for example, USP No. 3,326,994, USP
No. 4,366,091, USP No. 4,08
3,883, etc. Of these, USP
No. According to the method of US Pat. No. 4,083,883, benzenes are produced by dehydrogenating cyclohexanes under a gas phase reaction condition using a catalyst obtained by combining platinum, rhodium and nickel on alumina. You can

More specifically, using a catalyst in which a platinum group metal is supported on a porous carrier, cyclohexanes are circulated under gas phase conditions to be converted into benzenes.
In this case, the platinum group metal is platinum, palladium, rhodium, ruthenium or the like. The catalyst uses these two
It is adjusted by combining at least one kind and further adding nickel or the like. The porous carrier for supporting the metal is a refractory inorganic oxide such as alumina, titania, zirconia, etc., but alumina is particularly preferable. Reaction temperature is 3
The pressure is in the range of 70 to 650 ° C and the pressure is in the range of 0.1 to 10 atm. LHSV is ¹ to 40 Hr ^-1 . The molar ratio of hydrogen to hydrocarbon is preferably in the range of 1: 1 to 20: 1.

In this case, cyclohexene coexists in cyclohexane, but since cyclohexene is converted to benzene under a dehydrogenation catalyst, the raw materials used can be effectively utilized.

(5) Benzene Recycle Step The benzene obtained in step (4) is recycled to the partial hydrogenation step of step (1). The benzene obtained in (4) and part or all of the hydrogen produced in the dehydrogenation step are recycled to the partial hydrogenation step of step (1). The gas generated in (4) is directly or after removing liquid entrained components other than hydrogen gas using a condenser / cooler, compressed by a compressor, and circulated to step (1).

[0043]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1. (Step (1): Partial Hydrogenation Reaction of Benzene) A hydrogenation reaction catalyst was prepared as follows. A 5 wt% zirconia-modified silica carrier was prepared by impregnating a silica carrier with an aqueous solution of zirconium oxynitrate, and then evaporating and drying the solidified product and firing it at 1000 ° C. for 4 hours in an air stream. This carrier was impregnated with an aqueous solution of ruthenium chloride and zinc chloride, evaporated to dryness, and reduced at 200 ° C. for 3 hours in a hydrogen stream to give a hydrogenation reaction catalyst Ru—Zn (0.5-
0.5 wt%) / ZrO2 (5 wt%)-SiO2 was obtained. The hydrogenation reaction was performed according to the process flow shown in FIG. Benzene as a raw material was supplied from a new supply line 1, and recycled benzene was supplied from a line 2 to a hydrogenation reactor R1 to carry out a reaction. The hydrogenation conditions are: hydrogen pressure 5.0 MPa, reaction temperature 15
The composition in the reaction solution was 38 wt% benzene,
6 wt% zinc sulfate aqueous solution 59 wt%, catalyst concentration 3 wt%
It went in%. The reaction results were such that the conversion of benzene was 61%, the selectivity of cyclohexene was 72%, and the content of cyclohexane in the obtained reaction mixture was 17 mol%. (Step (2): Oxidation reaction step) The reaction mixture (organic phase) of the partial hydrogenation reaction was supplied to the oxidation reactor R2 via line 3. Oxidation reaction conditions were an oxygen pressure of 0.7 MPa and a reaction temperature of 70 ° C., and the composition of the reaction solution was 40 wt% of a mixture of benzene, cyclohexene and cyclohexane, and 60 wt% of ethylene glycol. As a catalyst, 0.15 mmol of P was added to 1 g of cyclohexene.
d (CH3CN) 2Cl2, CuCl2, FeCl3 were fed to the reactor. The reaction results were 70% conversion with respect to cyclohexene and 95% in terms of the total selectivity of cyclohexanone and cyclohexanone ethylene glycol ketal. (Step (3): Unreacted Material Recovery Step) The oxidation reaction product liquid obtained in the step (3) was sent to the separator D1 through the line 4. In the separator D1, the product liquid is vertically separated into two phases, the lower phase is composed of a catalyst and ethylene glycol, and the upper phase is an organic phase containing cyclohexane, cyclohexene, benzene, cyclohexanone, and cyclohexanone ethylene glycol ketal. The phase containing the catalyst and ethylene glycol was returned to the oxidation reactor R2 via line 5 for reuse. The organic phase separated in the separator D1 was sent via line 6 to the distillation column D2. As the effluent of the distillation column D2, benzene, cyclohexene, and cyclohexane were obtained, and the effluent was supplied to the dehydrogenation reactor R3 via the line 7. Cyclohexanone and cyclohexanone ethylene glycol ketal were obtained from the distillation residue of the distillation column D2. The distillation residue of the distillation column D2 was introduced into the hydrolysis reactor R4 through the line 8 and water was added through the line 9 to hydrolyze the ketal into cyclohexanone. Further, the reaction product liquid was supplied to the distillation column D3 via the line 10, and the target product cyclohexanone could be obtained as the effluent from the line 11. Also, ethylene glycol produced in the hydrolysis reactor R4 was obtained as a distillation residue, which was obtained in line 12
Was sent to the oxidation reactor R2 for reuse. (Step (4): Dehydrogenation Step) The composition of the effluent liquid introduced from the distillation column D2 to the dehydrogenation reactor R3 is benzene 5
7 mol%, cyclohexene was 19 mol%, and cyclohexane was 24 mol%. The reaction was carried out at 400 ° C. using aluminum oxide carrying 0.5 wt% of platinum as a catalyst. As a result, cyclohexane and cyclohexene were almost quantitatively converted into benzene. The obtained benzene was returned to the partial hydrogenation reactor R1 via line 2 and reused. On the other hand, the hydrogen generated by the dehydrogenation reaction and separated by cooling was compressed and then returned as the raw material hydrogen in the partial hydrogenation step.

[0044]

By adopting the series of processes of the present invention, the amount of cyclohexane produced in the process can be reduced, the load of the dehydrogenation step can be reduced, and the industrial utility value is high.

[Brief description of drawings]

FIG. 1 is a diagram showing a series of processes according to an embodiment of the present invention.

[Explanation of symbols]

R1: Partial hydrogenation reactor R2: Oxidation reactor R3: Dehydrogenation reactor R4: hydrolysis reactor D1: Separator D2: Distillation column D3: Distillation column 1-11: Line

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahiko Takewaki             1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa             Mitsubishi Chemical Corporation Yokohama Research Institute F-term (reference) 4C022 FA02                 4H006 AA02 AB84 AC11 AC12 AC44                       BA05 BA07 BA09 BA10 BA11                       BA18 BA19 BA22 BA23 BA25                       BA26 BA30 BA37 BA55 BA66                       BC16 BC31 BC40 BD40 BD52                       BD70 BD84 BE20 BE30                 4H039 CA40 CA41 CA42 CA62 CB10                       CC10 CC50 CH10

Claims (7)

[Claims] 1. A method for producing cyclohexanone and / or its ketal by partially hydrogenating benzene and then oxidizing the resulting cyclohexene,
A process for producing cyclohexanone and / or its ketal, which comprises sequentially passing through a series of steps (1) to (5) below. (1) Partial hydrogenation of benzene under acidic conditions to obtain a reaction mixture containing cyclohexene as a main component (2) Partial hydrogenation step (2) Oxidizing the reaction mixture obtained in step (1) to cyclohexanone and / or cyclohexanone Step (3) for obtaining ketal Oxidation reaction step (3) Step (4) for recovering unreacted material containing cyclohexane, cyclohexene and benzene from the product liquid after the oxidation reaction in step (2) Dehydrogenation of unreacted material recovered in step (3) Dehydrogenation step (5) to obtain benzene by reusing the benzene obtained in step (4) in the partial hydrogenation step of step (1) 2. The cyclohexane content of the reaction mixture obtained in the partial hydrogenation step of step (1) is 24 m.
The method for producing cyclohexanone and / or its ketal according to claim 1, which is at most ol%. 3. The content of cyclohexane in the unreacted material used for dehydrogenation in step (4) is 37.5 mol%.
The method for producing cyclohexanone and / or its ketal according to claim 1 or 2, which is as follows. 4. The method for producing cyclohexanone and / or its ketal according to claim 1, wherein the acidic conditions in the partial hydrogenation step of step (1) are pH 3-7. 5. The oxidation reaction step of step (2), in the presence of a polyhydric alcohol, (a) palladium as a catalyst,
The cyclohexanone according to any one of claims 1 to 4, wherein the reaction is carried out in the presence of (b) at least one metal other than palladium in Group 8, 9, 10, and 14 of the periodic table, and (c) halogen. And / or a method for producing the ketal thereof. 6. The method for producing cyclohexanone and / or its ketal according to claim 5, which further contains copper as a catalyst. 7. A method for producing a ketone and / or an aldehyde by hydrolyzing cyclohexanone and / or its ketal obtained by the method according to any one of claims 1 to 6 in the presence of an acid catalyst.