JPH02138233A - Oxidization of aromatic compound - Google Patents

Abstract

PURPOSE:To continuously produce an oxidized aromatic compound under mild condition in high efficiency while keeping the activity of an oxidation catalyst in high efficiency by oxidizing an aromatic compound with an O2-containing gas in liquid phase in the presence of a specific oxidation catalyst and a specific reduction catalyst. CONSTITUTION:The objective compound such as phenol is produced by (1) adding an aromatic compound such as benzene to a mixed solvent produced by mixing an acid such as sulfuric acid with a solvent such as acetonitrile containing (A) an oxidation catalyst consisting of copper or a copper compound such as cupric sulfate and (B) a reduction catalyst consisting of a compound capable of reducing cupric ion with H2 gas or a reducing compound having the function comparable to H2 gas (e.g., platinum black deposited on platinum) and (2) oxidizing the aromatic compound at normal temperature -200 deg. while passing CO as a reducing gas and air as an O2-containing gas through the solution. The above oxidation process has merits of low facility and running costs and is suitably applicable for industrial operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for oxidizing aromatic compounds, and more particularly to an efficient method for oxidizing aromatic compounds using an oxygen-containing gas such as air.

(Prior Art) Phenols, especially phenol, which can be produced by direct oxidation of aromatic compounds, are very important compounds in the chemical industry. At present, most of this phenol is produced by the cumene process.

By the way, the cumene method is a process that requires a large amount of equipment and consists of multiple reactions such as alkylation, oxidation, and decomposition, and also has the problem of producing acetone in the same mole as phenol as a by-product. The current situation is that we are waiting for the development of alternative technology that requires large and inexpensive equipment.

As an alternative to the cumene method, research has been actively conducted to produce phenol by direct oxidation of benzene. For example, Neck et al. A method for obtaining phenol by oxidizing benzene with oxygen is disclosed (tlsP 3718629).

In addition, Fleszar et al. have disclosed a method for obtaining phenol by adding metallic copper to a benzene sulfuric acid aqueous solution as a catalyst (Rocznlkl Chem, 50 (2)
), 271 (1976)).

Further, at least a part of copper ions or titanium ions is kept at a low valence by electrolytic reduction, and oxygen-containing gas is introduced using this as a catalyst to oxidize benzene to obtain phenol (JP-A No. 80-9889). ), and also discloses a method for obtaining phenol by oxidizing benzene by blowing air under acidic sulfuric acid using a catalyst containing metallic copper and divalent copper ions (Japanese Patent Application Laid-Open No. 6 (1983) (1-1)). fi7
Publication No. 44Q).

In these already disclosed methods, the catalytic active species in the oxidation reaction of benzene, etc. is said to be a monovalent copper ion, and the monovalent copper ion is said to be a monovalent copper ion in the oxidation of aromatic compounds. turns into ion. The reaction is therefore considered to be stoichiometric rather than catalytic with respect to copper ions.

Monovalent copper ions, which contributed as a catalyst to the oxidation of benzene, no longer contribute to the reaction once they become divalent and are deactivated, so long-term continuous reaction cannot be achieved as is. Therefore, techniques for realizing continuous reaction have been devised, such as the method described in the above-mentioned Japanese Patent Application Laid-Open No. 60-9889, and F L
As in the method of Eszar et al., 1! A method of maintaining copper ions at a low valence using extreme reduction has been proposed.

Note that although the latter document suggests the possibility of the existence of methods other than the above-mentioned electrode reducibility for maintaining the low valence of copper ions, it does not include any specific descriptions or examples.

(Problems to be Solved by the Invention) As mentioned above, although there have been various proposals for producing phenol by direct oxidation of benzene in place of the cumene method, these conventionally proposed techniques have not been practical in practice. For example, the catalytic activity is too low or the reaction is essentially stoichiometric between the catalytic components, making it difficult to put it to practical use. Since it also has the disadvantage of high phenol production, there are still many points that need to be improved before it can be used for phenol production on an industrial scale.

Under the current state of the prior art as described above, the present inventor has conducted intensive research on a method that can efficiently oxidize benzenes, and has developed the present invention.

That is, an object of the present invention is to efficiently maintain the activity of an oxidation catalyst by a novel method in a method of directly oxidizing an aromatic compound with an oxygen-containing gas in a liquid phase in the presence of metallic copper or a copper compound as an oxidation catalyst. An object of the present invention is to provide a method for oxidizing aromatic compounds, which enables highly efficient and continuous production of phenols and benzoquinones.

Another object of the present invention is to provide a novel method for oxidizing aromatic compounds that requires low manufacturing equipment and implementation costs and can be suitably applied to industrial implementation.

(Means for Solving the Problems) Therefore, the feature of the method of the present invention, which was made to achieve the above object, is that in the presence of copper or a copper compound as an oxidation catalyst,
In a method of oxidizing aromatic compounds with oxygen-containing gas in a liquid phase, a reducing catalyst having an activity of reducing divalent copper ions is coexisting with hydrogen gas or a reducing compound with an equivalent function. It's located where I left it. Furthermore, another feature of the method of the present invention is that the amount of oxidation products is increased by coexisting iron or an iron compound as a component of the catalyst in the above-mentioned mixture.

In the method of the present invention, the oxidation catalyst constituting one of the catalysts coexisting and used in a composite manner as described above is not only metal copper, but also various copper compounds can be used. For example, as an example of copper salt, which is a copper compound,
Inorganic acid salts such as copper sulfate, copper chloride, copper perchlorate, or
Examples include organic acid salts such as copper acetate and copper formate.

Copper that can be used as an oxidation catalyst changes from zero valence to monovalent or divalent, which is a higher oxidation state, during the reaction, so it is sufficient as a starting material to have zero valence. Examples of iron or iron compounds include reduced iron (powder), inorganic acid salts such as iron sulfate, iron nitrate, and iron chloride, and organic acid salts such as iron oxalate and iron fumarate. Generally, it is preferable to use the amount in a stoichiometrically equimolar range or less.

The coexistence of iron or iron compounds not only functions as a reduction catalyst as described below, but also participates in the oxidation mechanism of aromatic compounds and increases its activity. Therefore, substances other than iron or iron compounds may be used as reduction catalysts. When using iron or iron, it is preferable to separately add iron or an iron compound so that they coexist.

Next, in the method of the present invention, the reduction catalyst constituting the other of the catalysts used in combination is used to maintain the activity of the oxidation catalyst. Such reduction catalysts include, for example, noble metals and base metals of group I of the periodic table, or compounds thereof; specifically, Pd
, Rh, Pt and other noble metals and their salts, Fe, G
In addition to base metals such as O and their salts, nonmetallic activated carbon, polyaniline, and the like can also be used. Among these, noble metals or noble metal compounds such as noble metal salts are particularly preferably used.

This reduction catalyst is used under the necessary condition that it is effective in maintaining the activity of the oxidation catalyst, and the reaction rate tends to increase as the amount of reduction catalyst increases. It is generally desirable to use a large amount of reducing catalyst within the range necessary to suit the design of the reactor 3 reaction, but for example, the noble metals of group Ⅰ mentioned above are relatively expensive, so using a large amount will increase production costs. will be invited. Therefore, industrially, it is often preferable to use it in a stoichiometrically equimolar amount or less relative to the oxidation catalyst.

In the method of the present invention, it is necessary that the oxidation catalyst and the reduction catalyst used to maintain the activity of the oxidation catalyst coexist in such a manner that they have an effective relationship for the reduction reaction. The catalyst must be in a state where hydrogen gas or a reducing compound having an equivalent function can reduce divalent copper ions in the presence of the reducing catalyst. Therefore, it is necessary that the reduction catalyst and the oxidation catalyst be used in such a manner that they are or can be at least partially adjacent to each other at the atomic level.

Therefore, both catalysts can also be used in a form in which one or both of the oxidation catalyst and the reduction catalyst are supported on a suitable carrier, as long as the above conditions are satisfied as necessary and sufficient conditions. Examples of carriers that can be used include silica, alumina, magnesia, and composite oxides thereof. The method of supporting the catalyst components on these carriers is not particularly limited, and may be either a method of supporting all the catalyst components at the same time or a method of supporting the catalyst components in multiple stages.

The reaction of the process according to the invention is carried out in the liquid phase. As the solvent, the raw aromatic compound itself may be used as a solvent, or other suitable solvents may be used. Examples of solvents that can be used include water, acetonitrile, and benzene. Nitriles such as nitrile,
Amides such as acetamide, N,N-dimethylformamide, ketones such as acetone and methyl ethyl ketone, saturated hydrocarbons such as hexane and cyclohexane, esters such as ethyl acetate, methanol, ethanol,
Examples include alcohols such as tertiary-butanol and carbonates such as propylene carbonate, and any one of these or a mixture of two or more thereof can be used as a solvent. In particular, by adding a compound having a coordination effect such as acetonitrile, monovalent copper ions generated during the reaction can be stabilized. Furthermore, the reaction can be carried out by adding an acid to the reaction raw materials, and examples of such added acids include inorganic acids such as sulfuric acid, nitric acid, and phosphoric acid, and organic acids such as acetic acid and formic acid. can.

Typically, in the reaction of the present invention, a catalyst and a raw material are added to the above solvent, an oxygen-containing gas is blown into a reaction mixture consisting of the solvent, a catalyst, and a raw material, and hydrogen gas is introduced into the reaction mixture. Continuously by blowing into the reaction mixture a compound equivalent to hydrogen in terms of reducing properties to the oxidation catalyst (hereinafter, these may be collectively referred to as "hydrogen, etc.") in the presence of a reducing catalyst. It is carried out in a regular manner. However, the reaction is not limited to the above reaction format, and the reaction mixture containing the catalyst may be reduced using hydrogen or the like, and then the aromatic compound may be oxidized using an oxygen-containing gas, which may be carried out alternately in the same reactor. Alternatively, a reactor for reducing the oxidation catalyst with hydrogen or the like,
A separate reactor may be used to oxidize the aromatic compound with an oxygen-containing gas.

Hydrogen etc. used in the reaction of the method of the present invention include:
Examples include hydrogen gas, -carbon oxide, and olefin.

The oxygen-containing gas is not particularly limited as long as it contains oxygen, but air is preferably used industrially.

The reaction temperature is not particularly limited as long as the aromatic compound as a raw material is in a liquid phase during the reaction, and when the reaction temperature is raised to increase the reaction rate, the reaction may be carried out under pressure. The practical temperature range is often room temperature to 200°C, preferably room temperature to 175°C.

Examples of aromatic compounds to be oxidized by the method of the present invention include compounds having at least one benzene ring or polycyclic compounds, which also have one or more hydrogen atoms bonded to the ring. However, there is no problem even if it is substituted with a substituent such as an alkyl group or a hydroxyl group. Representative examples of such aromatic compounds include benzene, naphthalene, toluene, and phenol. . It is also possible to use mixed raw materials of these compounds depending on the purpose.

(Effects of the Invention) According to the method of the present invention, an aromatic compound is oxidized by an oxygen-containing gas in a liquid phase in the presence of metallic copper or a copper compound as an oxidation catalyst, and the oxidation catalyst is Since the activity is efficiently maintained, it is possible to oxidize aromatic compounds efficiently and continuously under mild reaction conditions.

Furthermore, the method of the present invention requires less manufacturing equipment and implementation costs than the conventional cumene method, etc., and has the advantage that it can be particularly suitably applied to industrial implementation.

(Example) The present invention will be specifically explained below using an actual bI example.
It goes without saying that the present invention is not limited to these examples.

Example 1 1.5 g of activated carbon (manufactured by Katayama Kogyo) was used as a reduction catalyst, 10 mmoR/Il of cupric sulfate was used as an oxidation catalyst as a copper salt,
were used as catalysts.

Solvent: 0.1N H2SO4 and acetonitrile, 9=1
A mixture of 10 mR and 2 volumes was used.

1 ml of benzene was added to the solvent to which the above catalyst had been added, and the mixture was reacted at 25° C. for 6 hours while blowing carbon monoxide as a reducing gas and air as an oxygen-containing gas.

When the product was analyzed by high performance liquid chromatography, it was found to be 0. Phenol in OIB7mtaol/IL was confirmed.

Example 2 Platinum with platinum black was used as a reduction catalyst. The platinum with platinum black used in this example was prepared by dissolving 1.0 g of chloroplatinic acid 6-eternal hydrate in 26.38 ml of water, adding 0.0045 g of lead acetate, and adding a small amount of hydrochloric acid. A plating solution was prepared by fixing a coiled platinum wire and a counter electrode in the plating solution at a distance of 2 cm, and performing electroplating in this state.

The oxidation catalyst is cupric sulfate 10 mmoJ2/ as a copper salt.
II.

was used; the solvent was 0. IN HzSO4 and acetonitrile 9:1
10 mj of the mixture with a volume ratio of ! Using.

Add 5 m of sodium chloride to the solvent to which the above catalyst was added.
moJl/It was added thereto, 1 m of benzene was added thereto, and the mixture was reacted for 2 hours while blowing hydrogen as a reducing gas and air as an oxygen-containing gas.

As a result of analyzing the product, 1.5951rnal/It
of phenol was confirmed.

Examples 3 to 5 Platinum with platinum black was used as a reduction catalyst. This platinum with platinum black in this example was prepared using a chloroplatinic acid solution of 1.501rnl (Pt1.931mm) containing a small amount of hydrochloric acid.
ol/IL), formalin (35%) 2.825
After cooling to about -1θ℃ and stirring vigorously, add KOH solution (50%) while keeping the temperature below 5℃.
．． 911 m and Q were added dropwise little by little, and the platinum black precipitate was filtered, thoroughly washed with water, and dried to obtain a solution.

As an oxidation catalyst, cupric sulfate lOmmof/ as a copper salt is used.
jl was used.

Solvent: 0.1N H2SO4 and acetonitrile 9:1
A mixture with a volume ratio of 10II+1 was used.

10 mg and 20 mg of the above platinum black, respectively.
Add 3 m of benzene to each solvent to which 1 g of 30II was added.
N was added, hydrogen and air were blown into the mixture, and the mixture was reacted for 1 hour. The results are shown in Table 1 below.

Table 1 Example 6 As a reduction catalyst, 5 g of mordenite (TSZ60ONAE; manufactured by Tosoh Corporation) ion-exchanged with copper ions was reduced with hydrogen at 250°C for 3 hours (copper loading rate: 5).
]wt%), and as the oxidation catalyst, cupric sulfate (10 mmoffi/It) was used as a copper salt.

The solvent is 0.1N)+2504 and acetonitrile at 9:
A mixture with a volume ratio of 1 was used in 10+n stores.

Add 1 raI of benzene to the solvent containing the above catalyst, and blow in hydrogen and air! , and reacted for 5 hours.

As a result of product analysis, the amount of phenol produced was 0.13% m
It was ol/It.

Example 7 Zeolite with platinum black was used as a reduction catalyst. This platinum black-coated zeolite in this example was prepared by dissolving 1.0 g of chloroplatinic acid hexahydrate in 15 ml of water, and adding zeolite (Zeolon-900-Na; manufactured by Two-Tone) to the solution.
Add 37.28g and further add formalin (35g) at room temperature.
%) was added for 6 m, and then a 50% caustic soda solution was gradually added in a bed. The obtained platinum black-coated zeolite was thoroughly washed with water and dried at 110°C. The platinum loading rate of the zeolite was set to 1 wt zero.

2.0g of this platinum black zeolite and 10IIIio of cupric sulfate! l/i was used as a catalyst, and the solvent was 0.1N H2SO4 and acetonitrile at 9 =
10 m and Q of the mixture at a volume ratio of 1 were used.

When 1 ml of benzene was added to the solvent containing the above catalyst, hydrogen and air were blown into the solvent, and the reaction was allowed to proceed for 1 hour, 0.945 mmol of phenol was produced! / J2, hydroquinone 0.387 ma+offi/Il was produced.

Example 8 Palladium chloride 0.1 mmol/fl and cupric sulfate 10 mIIol/i were used as catalysts. IN(DH
It was placed in solvent 1011142, which was a mixture of NO3 and acetonitrile in a volume ratio of 9:1.

When 1 ml of benzene was added to this solvent, hydrogen and air were blown into the solvent, and the reaction was carried out for 1 hour, 0.8 Dl of phenol was added.
mmomata/I was generated.

Example 9 2 g of silica gel, 0.1 m of palladium chloride in distilled water
Add the momata and stir while heating. 2 mmof of cupric sulfate was added thereto, and the mixture was dried with sufficient stirring to prepare a catalyst. The catalyst thus prepared was placed in 20+nJj of benzene, and hydrogen and air were simultaneously supplied to cause a reaction. The amount of phenol produced 3 hours after the start of the reaction was 3!1.3Pmo
It was a cross.

Example 10 The reaction was carried out in the same manner as in Example 9 except that hydrogen and air were alternately supplied every 30 minutes.

The results up to 6 hours after the start of the reaction are shown in Table 2 below.

Table 2 Example 11 A reaction was carried out in exactly the same manner as in Example 9, except that 1.0 g of acetic acid was added to the reaction solution of Example 9. After starting the reaction 1
The amount of phenol produced at the hour was 83 μmO.

Example 12 A two-step loading method was used in which 2 g of silica gel was loaded with 0.1 mmoM of palladium chloride, and after drying, 2 mmou of cupric sulfate was loaded on it. The reaction was carried out in exactly the same manner as in Example 10, except that 1 liter of catalyst was used. 3 hours after the start of the reaction, 35 μmofi of phenol was produced.

Example 13 The reaction was carried out in the same manner as in Example 9 except that the amount of palladium chloride supported was 0.2 mmofi. The amount of phenol produced 1 hour after the start of the reaction was 50PIIlo9. Met.

Example 14 The reaction was carried out in exactly the same manner as in Example 9 except that chloroplatinic acid was used instead of palladium chloride. Reaction start 10
The amount of phenol produced after minutes was 4.4μmo! It was l.

Example 15 10 g of silica gel, 0.5 palladium chloride in distilled water
mmoll and 10 mmoll of cupric acetate were added and dried with sufficient stirring to prepare a catalyst. The catalyst thus prepared was added to 100 ml of benzene, 10 g of acetic acid was added, and after reduction under 3 atm of hydrogen for 2 hours, the reaction was carried out under 3 atm of oxygen for 1 hour.
9 μmoJl and 114 μmol of benzoquinone were produced.

Example 16 10m of benzene! 1 was dissolved in cyclohexane, and 2.34 g of a catalyst prepared in exactly the same manner as in Example 9 was added thereto. Add 2 hydrogen to the reaction solution containing this catalyst.
After supplying the mixture for an hour, air was further supplied for 1 hour to carry out the oxidation reaction of benzene, and as a result, 19.4 μmofi of phenol was produced.

Example 17 The reaction was carried out in exactly the same manner as in Example 16, except that a solution of 16 mmol of naphthalene dissolved in 20 J of cyclohexane was used, and 0.53 μm02 of α-naphthol was produced.

Comparative Example 1 A reaction was carried out in exactly the same manner as in Example 9 except that palladium chloride was not used in Example 9, and no formation of phenol was observed.

Comparative Example 2 Example 9 except that cupric sulfate was not used in Example 9
When the reaction was carried out in exactly the same manner as above, no formation of phenol was observed.

Example 18 A reduction catalyst prepared by supporting palladium chloride (1,1 mmoQ on 1 g of silica gel, drying, and hydrogen reduction at room temperature for 2 hours (palladium support rate twt!I;), and an oxidation catalyst containing cupric acetate 1 mno father was used.

The solution is acetonitrile, water, and acetic acid at 6.5.6.5°8.
A solution of 20+n51 in which biphenyl lQmmo was dissolved in a mixture at a volume ratio of 20+n51 was used.

Hydrogen and air were alternately supplied every 20 minutes to the reaction solution to which the catalyst had been added.

Two hours after the start of the reaction, 13.3 μm of 0-phenylphenol and 11.6 μm of m, p
-Phenylphenol was produced.

Example 19 A reaction was carried out in exactly the same manner as in Example 18, except that the amount of silica gel was 2 g, 10 mmou of naphthalene was dissolved in 20+++Jj, and hydrogen was supplied for 20 minutes and air was supplied for 3 hours. .92 μmol, 0.7071 L of 2-naphthol, and 8.75 L of 1,4-naphthoquinone were produced.

Example 20 Palladium chloride 0.05 mmo to 1 g of silica gel, Q.

1 mmoJl of cupric sulfate was supported, and after drying, hydrogen reduction was performed at room temperature for 2 hours to reduce palladium.

After supplying hydrogen for 2 hours to the reaction solution to which the above catalyst was added,
Furthermore, the reaction was carried out in exactly the same manner as in Example 19 except that air was supplied for 24 hours.
2μff1of, 2-naphthol 0.51pmo, Q,
3.46 JLrnol of 1,4-naphthoquinone was produced.

Example 21 Same catalyst as Example 20 1. (Exactly the same as Example 2o except that 1 g of silica gel supported 0.1 mmol of palladium chloride and hydrogen-reduced catalyst was added to 186 g, hydrogen was supplied for 1 hour, and then air was supplied for 22 hours. When the reaction was carried out, 1-naphthol 1
4.87 μmoL 2-naphthol 0, 90pm
ol! , 5.88 μmO of 1,4-naphthoquinone was produced.

Example 22 2 g silica gel, 0.1 m palladium chloride in distilled water
A catalyst was prepared by adding moJl and 0.5 mmof cupric acetate and drying with thorough stirring.

Add this catalyst to 20mR of benzene, and add 1g of acetic acid.
was added, reduced in the presence of hydrogen gas for 2 hours, and reacted for 1 hour by blowing in air. As a result, phenol 22.3μ
The production of benzoquinone 5.3 well mofi was confirmed.

Example 23 Iron sulfate (111) 0.015 as catalyst component of Example 22
A catalyst was prepared in the same manner except that mmo-mata was added. This catalyst was mixed with 20m9 of benzene. In addition, 1 g of acetic acid was added and exposed for 30 minutes. Then, 0.4 g of acetonitrile was added.
ml was added, and after being exposed to light for 30 minutes in the presence of hydrogen gas, air was blown in and reacted for 1 hour. As a result, 27.8 μmo of phenol and 18.9 μmo of benzoquinone were added.
The production of 1 was confirmed.

Example 24 In Example 23, iron sulfate (II+) was added to 0.05μ
A catalyst was prepared in exactly the same manner except that the mol was used, and as a result of the reaction, it was confirmed that 32.9 μmoi of phenol and 30.9 ILmol of benzoquinone were produced.

1 snake 4′? S

Claims (1)

[Scope of Claims] 1. A method of oxidizing an aromatic compound with an oxygen-containing gas in the presence of copper or a copper compound as an oxidation catalyst in a liquid phase using hydrogen gas or a reducing compound having an equivalent function. A method for oxidizing an aromatic compound, which comprises coexisting a reducing catalyst having an activity of reducing divalent copper ions. 2. A method for oxidizing an aromatic compound as set forth in claim 1, characterized in that iron powder or an iron compound is present as a component of the catalyst.