KR830002448B1 - Process for preparation of benzene-morocorboxylic acid - Google Patents

Abstract

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Description

Method for preparing benzene-monocarboxylic acid

Schematic diagram of the present invention.

The present invention relates to a process for producing benzene-monocarboxylic acid by oxidizing a monoalkyl-benzene compound in a liquid phase with a gas containing oxygen molecules in the presence of a catalyst composed of cobalt and manganese compounds dissolved in the reaction mixture.

Such a method is known from Dutch patent application 7,311,187. According to the method according to Dutch Patent Application No. 7,311,187, the weight ratio of cobalt metal to manganese metal is 99.8: 0.2 or less and the atomic ratio of manganese and cobalt is 1: 466 or more in the absence of practically no lower fatty acids and / or halogen compounds. The benzoic acid is prepared by oxidizing toluene in the presence of cobalt and manganese compounds.

However, this process has the drawback that the selectivity of the reaction for obtaining the desired benzene-monocarboxylic acid is not satisfactory.

The object of the present invention is to remedy this drawback.

Manufacturing method according to the invention is characterized in that the atomic ratio of manganese and cobalt is applied between 1: 500 ~ 1: 100,000. The selectivity of the reaction for obtaining the desired benzene-monocarboxylic acid with a low atomic ratio of manganese: cobalt as described above is superior to the preparation according to Dutch patent application 7,311,187. This is a surprising result.

This is because Dutch Patent Application No. 7,311,187 says that the manganese: cobalt atomic ratio should not be lower than 1: 466, since such a catalyst has no practical improvement compared to a catalyst consisting solely of cobalt compounds. The drawbacks of using only cobalt compounds as catalysts are known from the patent application.

In addition, Dutch Patent Application No. 7,311,187 points out that the atomic ratio of manganese: cobalt is several times higher than that of 1: 466, which is actually better than the atomic ratio of manganese: cobalt in the range of 1: 466.

The most suitable atomic ratio of manganese and cobalt in the production process according to the present invention is between 1: 500 and 1: 10,000, and particularly preferably 1: 600 to 1: 6,000.

Manganese and cobalt compounds are preferably used as salts of the benzene-monocarboxylic acids to be produced.

The metal may also be added, for example, in the form of free metals, salts of aliphatic carboxylic acids having 1 to 20 carbon atoms, oxides, hydroxides, complexes, other organic salts and alcoholates. Salts of benzene-monocarboxylic acids to be prepared depending on the reaction conditions can be readily produced starting from the added material.

The preparation according to the invention starts from a monoalkyl-benzene compound.

In addition to the alkyl group, the monoalkyl benzene compound will contain one or more substituents which are inert depending on the reaction conditions, for example chlorine, bromine, nitro, tertiary alkyl, alkoxy, allyloxy and cyanogen groups.

The preparation according to the invention is very suitable for the oxidation of toluene to benzoic improvement.

For example, benzoic acid is used in the preparation of phenols.

Other preparations in the present invention are made in the absence of practically the aliphatic carboxylic acids and / or halogen compounds used as promoters.

The preparation omits the process of separating and purifying the reaction mixture from aliphatic carboxylic acids and / or halogen compounds used as promoters involving additional processes.

For example, the use of aliphatic carboxylic acids and / or halogen compounds as accelerators is additionally expensive to make a portion of the aliphatic carboxylic acids and / or halogen compounds to be used as accelerators, or the aliphatic carboxyl can be omitted while omitting one step in the manufacturing process. Acid can be regenerated.

In order for the monoalkyl-benzene compound to react with oxygen at a certain time to have the same amount, aliphatic carboxylic acid also takes up space, which requires a larger reactor than the preparation method according to the present invention.

Since aliphatic carboxylic acids are generally stronger acids than benzene-monocarboxylic acids, these aliphatic carboxylic acids cause corrosion problems. Halogen compounds used as promoters are also corrosive compounds.

General reaction conditions in the production process according to the invention are known from the specifications of the publications 13, (11), 173-176- (1964) and Dutch patent application 7,311,187 entitled "Methods for producing hydrocarbons".

The use of the preparation according to the invention may use materials such as, for example, peroxides and aldehydes, to be used as initiators or activators of the reaction.

In addition to cobalt and manganese compounds, other metal compounds dissolved in the reaction mixture are, for example, magnesium, copper, strontium, zinc, cadmium, mercury, aluminum, lead, tin, antimony, bismuth, silver, nickel iron, rubidium, cesium May be present as promoters such as hafnium, titanium, gallium, tungsten, platinum, chromium, vanadium and especially zirconium.

The oxidation process uses a gas containing oxygen molecules. Examples of gases that can be used are air, oxygen rich air, nitrogen diluted air, pure oxygen, ozone and mixtures of these gases.

If the liquid phase is maintained in the reaction system during the reaction, the temperature and pressure are not critical, and the temperature is between 390 and 500 K and between 200 and 2,000 Kpa.

Especially, temperature is 400 ~ 460K and pressure is 300 ~ 800Kpa.

The preparation according to the invention can be carried out in a batch-wise and continuous manner.

The present invention will be apparent from the accompanying reaction design drawings.

Liquid toluene is supplied to the oxidation reactor 1 through line 2 and air is supplied through line 3.

The toluene is a dissolved catalyst and contains 10 to 1000 ppm by weight of cobaltous acetate.

Toluene in the reactor 1 is oxidized in a liquid phase having a temperature of 412 to 438 K and a pressure of 300 to 1,000 Kpa.

The reactor exhaust gas is fed to the condenser 5 via line 4. Uncondensed gas exits through line 6, and the condensed gas is fed to separator 8 via line 7 where it is separated into an organic layer and an aqueous layer.

This aqueous layer is removed via line 9.

This glass layer is returned to the oxidation reactor 1 via line 10. The liquid oxidation mixture is fed from the oxidation reactor 1 to the distillation column 12 via line 11.

In the distillation column 12 all components boil at a lower temperature than benzoic acid are distilled and removed through line 14 with benzoic acid.

The upper layer product is mainly composed of toluene, which is returned to the oxidation reactor 1 after the whole or small amount of benzaldehyde is recovered by distillation.

The bottom product is fed to distillation column 15 via line 13, where all remaining benzoic acid is boiled to a high temperature and distilled off from a product called tar.

The invention will be clearly illustrated by the following examples and comparative experiments.

Example 1

In the continuous oxidation reactor 1, toluene is oxidized in a liquid phase with oxygen from air having a temperature of 433 K and a pressure of 500 Kpa in the presence of 80 ppm by weight of cobalt (added as acetate).

The reaction mixture contains manganese (also added as acetate) having a manganese: cobalt atomic ratio of 1: 3,300.

In the distillation column 12, each component and benzoic acid boiling at a lower temperature than benzoic acid are distilled off under atmospheric pressure from the lower portion of the reactor 1.

The bottom product of the distillation column 12 is continuously distilled under atmospheric pressure in the distillation column 15 until all benzoic acid is completely removed from the reaction product.

Under these conditions, 913 moles of benzoic acid were recovered for 1000 moles of toluene fed to the reactor.

Example 2

The process of the example is repeated so that the atomic ratio of manganese: cobalt is 1: 1,000.

Under these conditions, 913 moles of benzoic acid were recovered for 1,000 moles of toluene fed to the reactor.

Comparative Experiment A

The process of Example 1 was repeated so that the atomic ratio of manganese: cobalt might be 1:67.

Under these conditions, only 908 moles of benzoic acid were recovered for 1,000 moles of toluene fed to the reactor.

Comparative Experiment Example B

The process of Example 2 is repeated without any manganese in the reaction mixture.

Under these conditions, only 909 moles of benzoic acid were recovered for 1,000 moles of toluene fed to the reactor. In this experiment, a cobalt concentration of 80 ppm by weight may be used. A cobalt concentration of 10-1,000 ppm by weight may also be used.

The manganese content is preferably at least 0.01 ppm by weight.

Claims (1)

In preparing a benzene-monocarboxylic acid by oxidation of a monoalkyl-benzene compound in the presence of a catalyst composed of cobalt and manganese compounds dissolved in a reaction mixture in a liquid phase with a gas containing oxygen molecules, the atomic ratio of manganese to cobalt is 1 : 500-1: A method for producing benzene-monocarboxylic acid, characterized by using a catalyst which becomes 100,000.

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