JPH1180057A - Production of phenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phenol by contacting a benzenemonocarboxylic acid with oxygen-containing gas and steam, with reduced generation of tar as a by-product at enhanced selectivity to the phenol. SOLUTION: A phenol is obtained by contacting a benzenemonocarboxylic acid with an oxygen-containing gas A and steam S in the presence of a catalyst containing a copper compound in liquid phase at 200-260 deg.C, wherein the oxygen- containing gas A is jetted into the reaction liquid from a lower part of the liquid phase using, for example, a jet pump 5 so as to be fine bubbles having an average bubble size of 100 μm or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing phenols by oxidizing, decarboxylating and hydrolyzing benzenemonocarboxylic acids such as benzoic acid.

[0002]

2. Description of the Related Art A method for producing phenols by oxidizing, decarboxylating and hydrolyzing benzenemonocarboxylic acid or a salt, ester or anhydride thereof in a liquid phase in the presence of a catalyst containing a copper compound has hitherto been known. Are known. It is also well known that the use of a magnesium compound together with a copper compound as a catalyst enables phenyl benzoate and its hydrolysis product phenol to be obtained with high selectivity. It is also known to use a compound of manganese or a rare earth metal together with a copper compound to increase the selectivity (Japanese Patent Publication No. 2-10812).

[0003] Such a method for producing phenols has a drawback in that a large amount of tar-like by-products (hereinafter referred to as tar) is produced. In order to prevent the formation of tar, JP-B-39-11210 states that it is important to select the material of the reaction vessel, shorten the residence time of the phenol produced in the reactor, and uniformly heat the reaction vessel. JP-A-57-40430 states that by controlling the ratio of magnesium to copper used as a catalyst, the production of tar can be reduced. Furthermore,
JP-A-58-32836 discloses that a compound of copper and manganese and a lanthanum compound are used as catalysts.
It is said that the selectivity of phenol or phenyl benzoate can be increased.

Japanese Patent Publication No. Sho 51-33098 discloses a dry method in which the reaction is divided into two, and only the oxygen-containing gas is blown in the first reactor and the oxygen-containing gas and steam are blown in the second reactor. It has been suggested that phenol can be obtained with relatively high selectivity.

[0005] However, this dry method has the disadvantage that the equipment and operation are complicated in that a plurality of reactors are required. On the other hand, a method of producing phenol by oxidation, decarboxylation and hydrolysis in one reactor, that is, a wet method is simple and industrially advantageous. As for the wet method, although the above-mentioned improvement has been proposed, it cannot be said that the prevention of tar by-products is sufficient, and a higher phenol selectivity is required.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a method for preparing phenols by contacting an oxygen-containing gas with water vapor in the liquid phase of a benzenemonocarboxylic acid or a salt, ester or anhydride thereof in the presence of a catalyst containing a copper compound. In manufacturing
It is intended to reduce the amount of by-products of tar, that is, to increase the selectivity of phenols from benzenemonocarboxylic acids.

[0007]

As a result of the investigation, the present inventors have found that the contact between the oxygen-containing gas and the reaction solution has a great effect on the by-product of tar, and at the same time, have determined the average diameter of the bubbles of the oxygen-containing gas. It has been found that when the content is below a certain value, the amount of by-products of tar is remarkably reduced, and the present invention has been achieved.

That is, the present invention provides a method for preparing a benzene monocarboxylic acid or a salt, ester or anhydride thereof in a liquid phase.
In producing a phenol by contacting an oxygen-containing gas with water vapor at 200 to 260 ° C. in the presence of a catalyst containing a copper compound, the oxygen-containing gas is mixed with the lower liquid phase so as to form fine bubbles having an average bubble diameter of 100 μm or less. This is a method for producing phenols, wherein the phenol is spouted into a reaction solution.
Further, the present invention relates to the method for producing phenols, wherein a reaction liquid is jetted at a high speed from a nozzle of a jet pump installed at a lower part of a liquid phase, and an oxygen-containing gas is sucked in from the periphery thereof and jetted into the reaction liquid. is there. The catalyst preferably contains a copper compound and a magnesium compound.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of benzenemonocarboxylic acids include benzoic acid, toluic acid, nitrobenzoic acid, phenylbenzoic acid, dimethylbenzoic acid, and the like, from which phenol, cresol, nitrophenol, phenylphenol, and xylenol can be obtained, respectively. Although phenol can be obtained from benzoic acid, it is most important industrially.

The copper compound used as the catalyst may be any compound that dissolves in the reaction solution under the reaction conditions, and examples thereof include copper benzoate, cuprous oxide, cupric oxide, and metallic copper. Examples of the compound used together with the copper compound include compounds such as magnesium, sodium, potassium, cobalt, tin, manganese, and rare earth metals, and preferably include a magnesium compound. The magnesium compound may be any compound that dissolves in the reaction solution as described above, and examples thereof include magnesium benzoate and magnesium oxide.

The amount of the copper compound may be about 0.1 to 5% by weight in terms of metallic copper in the reaction solution. Other compounds can be present as a part of the catalyst component, and the amount of addition in that case can be in the range known in the above-mentioned publications. For example, the compound of magnesium is about 1 to 10 times as much as copper in terms of metal magnesium.

Known conditions can be employed for the reaction temperature and the reaction pressure. When benzoic acid is used as a raw material, the reaction temperature needs to be higher than the melting point of benzoic acid and lower than the boiling point, but is in the range of 200 to 260 ° C. The reaction pressure may be at least the pressure required to maintain the liquid phase at the above temperature, but is from normal pressure to 3 kg / cm ² · G
Good degree.

The reaction is carried out by bringing an oxygen-containing gas and water vapor into contact with the reaction solution. The oxygen-containing gas is ejected from the lower part of the liquid phase into the reaction solution so as to form fine bubbles having an average bubble diameter of 100 μm or less. is important. By setting the average bubble diameter to 100 μm or less, preferably 50 μm or less, the contact efficiency with the reaction solution is improved, and oxygen is consumed at an early stage. Therefore, not only the oxygen concentration in the discharged exhaust gas is reduced, but also the oxygen concentration in the upper layer of the reaction solution in equilibrium with the oxygen concentration.

According to the findings of the present inventors, it has been found that the rate of tar formation is proportional to the square of the oxygen concentration in the liquid, and proportional to the square of the phenol concentration in the liquid. . Therefore, for example, halving the oxygen concentration in the liquid can reduce the amount of tar generated to about 1/4, and reducing the average bubble diameter to 100 μm or less is extremely effective in preventing tar generation. is there.

As the oxygen-containing gas, besides air, circulating gas, circulating gas diluted air, oxygen gas or oxygen-enriched air can be used, but air is preferred. When air is used, the concentration of oxygen in the exhaust gas is about 10 ± several% according to a normal jetting method, for example, a method of jetting from a fine tube, but is lower than 5% or less, preferably 3% or less. It is advantageous to do so. The most effective way to reduce the oxygen concentration is to reduce the average bubble diameter. However, the control of the amount of the oxygen-containing gas charged and the position of the jet is also involved.

The charge amount of the oxygen-containing gas may be in a known range, but it is necessary that the amount be more than the amount at which the copper compound reduced during the reaction can be oxidized into a divalent copper compound. Preferably, it is not less than the theoretical amount and not more than twice the amount. If added in excess, the reaction of unreacted oxygen gas reacting with phenol to produce by-product tar increases. In addition, the ejection position of the oxygen-containing gas is
It must be at the lower part of the liquid phase of the reactor, and preferably at the lower part than the position where the steam is jetted.

The method for ejecting the oxygen-containing gas is not limited as long as the average bubble diameter can be reduced to 100 μm or less, but a method using a jet pump is effective. This is a method in which a reaction liquid is jetted at a high speed from a nozzle of a jet pump installed in a lower part of a liquid phase, an oxygen-containing gas is sucked in from around the jet, and jetted into the reaction liquid. Known jet pumps such as those described in Chemical Engineering Handbook can be used as such a jet pump. For example, a multi-stage ejector described in JP-A-62-117895 is also suitable. Can be used for

Referring to FIG. 1, an example of a jet pump will be described. A reaction liquid Q is jetted to a nozzle 1 of a jet pump by a circulation pump, and the obtained jet is blown into the center of a venturi nozzle 2 to generate a vacuum around the nozzle. Inhales oxygen-containing gas A supplied from outside,
Inject it into the next nozzle 3 by jet,
The reaction liquid Q is sucked from the surroundings, and the gas is jetted into the reaction liquid in a state where the gas is dispersed in the liquid as fine bubbles. Here, the ejector of this jet pump has two stages, but it is needless to say that the ejector may be one stage or three or more stages. The diameter of the bubble can be controlled by adjusting the shape of the nozzle, the speed of the jet, and the like.

An example of the installation of the jet pump will be described with reference to FIG. 2. A plurality of jet pumps 5 are provided below the reactor 4, and pipes and pumps for circulating the reaction liquid are provided outside (see FIG. 2). (Not shown), and an oxygen-containing gas supply pipe 6 is connected to the jet pump from outside. Although it is advantageous to provide a plurality of jet pumps 5 for efficiently stirring the reaction liquid, one jet pump 5 may be provided.

In FIG. 2, steam S is supplied from a dispersion pipe 7. The supply position of the water vapor is not particularly limited as long as it is in the liquid phase, but it is preferable that the position is above the oxygen-containing gas ejection position, for example, near the middle of the liquid phase. By doing so, the hydrolysis reaction mainly takes place in the liquid phase above the middle part, and it is possible to reduce the contact between the phenols and oxygen produced here as much as possible, thereby preventing the formation of tar. The supply amount of steam is 5 to the generated phenols.
It is in the range of ５０50 times mol.

The reaction can be carried out by any method, whether batch or continuous. When the reaction is performed continuously, an operation of continuously or intermittently extracting a part of the reaction solution from the reactor and removing tar is performed. Such an operation can be performed by a method described in the above-mentioned publication or the like. Further, the produced phenol flows out of the reactor together with the exhaust gas, and is condensed and recovered.

[0022]

EXAMPLES Example 1 Hereinafter, the present invention will be described with reference to examples. As a reactor,
A cylindrical reactor having a capacity of 2 liters having a raw material inlet 9, a gas inlet and a gas outlet 8 at an upper part, and a liquid outlet, a liquid inlet and an air inlet at a lower part was used. Water vapor is ejected from the gas introduction hole in the upper part of the reactor from the dispersion pipe 7 which reaches almost the middle layer of the liquid phase, and gas flowing out from the gas exhaust hole and gas containing low boiling point substances such as phenol and benzoic acid. The matter was discharged out of the system, and the condensed benzoic acid was returned to the system. A jet pump having the structure shown in FIG. 1 is disposed at the bottom of the reactor, and a circulation pump is provided between the lower liquid outlet and the liquid inlet, and the liquid extracted by the circulation pump is jetted from the nozzle of the jet pump. At the same time, the air supplied from the air inlet is sucked in so that the liquid containing the air that has become fine bubbles is ejected from the lower part of the liquid phase.

The reactor was charged with 100 g of benzoic acid, 5 g of magnesium oxide, and 2 g of cuprous oxide, and was heated to a temperature of 240 g.
C., and the reaction was carried out by supplying air from a jet pump and steam from a dispersion tube. During the reaction, 70Nl /
hr, steam at 100 g / hr, benzoic acid at 112.6
The resulting phenol was discharged together with the exhaust gas while supplying at g / hr. The average bubble diameter of the air ejected from the jet pump was about 10 μm, and the oxygen concentration in the exhaust gas was about 2%.

After a lapse of 5 hours, the reaction was stopped, and the phenol that had flowed out, benzoic acid, phenol, phenyl benzoate, and tar remaining in the reactor were measured and analyzed to determine the phenol selectivity and tar by-product rate. The phenol selectivity was 88.7% and the tar by-product rate was 3.2 wt%. In the calculation of phenol selectivity, phenyl benzoate was calculated as phenol.

COMPARATIVE EXAMPLE 1 In Example 1, air was jetted out of a dispersing tube arranged below the liquid phase together with water vapor without using a jet pump.
The reaction was carried out in the same manner except that stirring was added. The average bubble diameter of the ejected air was about 1 mm, and the oxygen concentration in the exhaust gas was about 7%. After a lapse of 5 hours, the reaction was stopped, and the phenol selectivity and tar by-product rate were determined in the same manner as in Example 1. The phenol selectivity was 72.0.
%, By-product by-product rate = 17.7 wt%.

[0026]

According to the production method of the present invention, by-products of tar can be reduced from benzenemonocarboxylic acids, and phenols can be obtained with high selectivity.

[Brief description of the drawings]

Fig. 1 Conceptual diagram of jet pump

FIG. 2 is a conceptual diagram of a reactor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Venturi nozzle 3 Nozzle 4 Reactor 5 Jet pump 6 Oxygen-containing gas supply pipe

Continuing on the front page (72) Noboru Daito Inventor at 46 Nippon Steel Chemical Co., Ltd. at 46, Hama, Nakahara-san, Ogata, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture

Claims (3)

[Claims] 1. A benzene monocarboxylic acid or a salt thereof,
In producing a phenol by contacting an oxygen-containing gas with water vapor at 200 to 260 ° C. in the presence of a catalyst containing a copper compound in the liquid phase of an ester or an anhydride, the oxygen-containing gas has an average bubble diameter of 100 μm or less. A method for producing phenols, which comprises squirting into a reaction solution from a lower part of a liquid phase so as to form fine bubbles. 2. The phenols according to claim 1, wherein the reaction liquid is jetted at a high speed from a nozzle of a jet pump installed at a lower part of the liquid phase, and an oxygen-containing gas is sucked in from the periphery thereof and jetted into the reaction liquid. Manufacturing method. 3. The method for producing phenols according to claim 1, wherein the catalyst comprises a copper compound and a magnesium compound.