JPH049344A - Production of cyclohexanone and cyclohexanol - Google Patents

Abstract

PURPOSE:To obtain the title compounds in high selectivity esp. for cyclohexanone by liquid phase oxidation of cyclohexane with O2 gas in the presence of a cobalt catalyst with its amount controlled within a specified range. CONSTITUTION:When cyclohexane is to be oxidized in a liquid phase with molecular oxygen or a gas containing the same in the presence of a cobalt catalyst, the concentration of said catalyst is so regulated as to be 0.01-0.1ppm in the final concentration in terms of cobalt (in case the reaction unit is made up of a series of subunits, in the final subunit). Thereby, the objective cyclohexanone and cyclohexanol can be obtained in high selectivity and quality esp. for the cyclohexanone. The oxidation reaction can be carried out in a stable manner, therefore being advantageous.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an industrially advantageous method for producing nclohexanone and cyclohexanol by liquid phase oxidation of nclohexane with molecular oxygen. .

Cyclohexanone and cyclohexanol are used as raw materials for the production of ε-aminocaprolactam.

(Prior art) Chlohexane is oxidized in the liquid phase with molecular oxygen or a gas containing molecular oxygen in the presence of a soluble cobalt salt (0.1 to 1100 p1 as cobalt) as a catalyst to produce chlorhexanone. and cyclohexanol! ! There are known ways to build them. (“Chemical Handbook Applied Handbook” 536
Page (October 15, 1986> Nihon Kagaku Complete Edition First Arrival) (Problems to be Solved by the Invention) However, the conventional method produces a large amount of by-products and the production rate of cyclohexanone is low.

Industrially, a mixture of cyclohexanone and cyclohexanol is mainly used as a raw material for the production of ε-aminocaprolactam. When used in the production of ε-aminocaprolactam, cyclohexanone is required, and cyclohexanol requires a step of dehydrogenating and converting it into cyclohexanone. Therefore, it is preferable that the production rate of cyclohexanone is high.

In view of these circumstances, as a result of intensive study on the method for producing cyclohexanone and cyclohexanol by oxidizing cyclohexane, we found that if the concentration of cobalt catalyst is 11 in the reactor in which the oxidation reaction is carried out, there are two reactors in the reactor. In the case of continuous connection, the maximum concentration is 0.01 pμ in the final reaction device
More than m.

The present invention was completed based on the discovery that cyclohexanone with a high selectivity between cyclohexanone and cyclohexanol, particularly cyclohexanone, and high quality cyclohexanone can be obtained by performing oxidation at a temperature below tpμm.

(Means for solving the problem) That is, in a method for producing cyclohexanone and cyclohexanol by oxidizing cyclohexane with molecular oxygen or a gas containing molecular oxygen in the liquid phase in the presence of a cobalt catalyst, A method for producing cyclohexanone and cyclohexanol, characterized in that the final concentration of the X4 Ruto catalyst is 0.01 pμm or more and less than 0.1 pμm as cobalt.The present invention is the same as the conventional method except for the amount of catalyst used. That is, cyclohexane is mixed in the presence of a cobalt catalyst at a temperature of about 80 to 200°C.
Hydroperoxides and acids of cyclohexanone, cyclohexanol, and cyclohexylhydroberooquinodonate by liquid phase oxidation with molecular oxygen or a gas containing molecular oxygen at a pressure of about 1 to 2 () atm; A reaction mixture containing esters, esters, etc. is obtained.

The cyclohexane is preferably industrially pure cyclohexane, but may contain small amounts of cyclohexanone, cyclohexanol, acids, esters, water, and the like.

Molecular oxygen or gases containing molecular oxygen include oxygen, air, air diluted with an inert gas such as nitrogen, air with oxygen added, and oxygen added to an inert gas such as exhaust gas from an oxidation reaction process. added gas, etc.

The reaction temperature is about 80-200°C, preferably 100-16°C.
It is 0°C. Below about 80°C, the oxidation of cyclohexane is slow, and above about 200°C, the selectivity from cyclohexane to cyclohexanone and cyclohexanol decreases.

The reaction pressure is about 11-20 at. This pressure is the pressure that keeps the reaction mixture in the liquid phase. Even higher pressures may be used, but there is no particular effect even if the pressure is increased to 2 Qatm or higher.

Reaction time is about 1-120 minutes. If the reaction time is about 1 minute or less, the reaction rate of cyclohexane is small, if the reaction time is about 120 minutes or more, the effect is almost unchanged, and if the reaction time is longer, the selectivity from cyclohexane to cyclohexanone and cyclohexanol decreases.

The format of the oxidation reaction used in the present invention is a batch type, continuous type or semi-batch type.

As the oxidation reactor, a commonly used spherical or cylindrical reactor is used. There may be no special device inside, but there may be a device such as a draft that controls mixing inside, or a device such as a perforated plate that divides the inside into multiple chambers.

There may also be a mechanical stirring device such as a stirring blade.

In a continuous or semi-batch reactor, cyclohexane and molecular oxygen or a gas containing molecular oxygen are supplied either alone or each from one or more points. At that time, the supply port may be configured as a nozzle in order to improve mixing.) The reactor (one tank or two or more tanks may be connected continuously).

In the present invention, the conversion rate of cyclohexane is about 1-15
% is preferable. If it is less than about 1%, a large amount of energy is required to recover unreacted cyclohexane, and if it is more than about 15%, the selectivity from cyclohexane to cyclohexanone and 7-clohexanol becomes low.

The cobalt catalyst is not limited as long as it is a cobalt compound active in oxidizing cyclohexane, including carboxylates, sulfonates, organic phosphates, sulfates, nitrates, phosphates, complexes, and /'% rogenides. , oxides, etc. As carboxylates, acetate, propionate, 2
-Ethylhexanoate, octanoate, naphthenate, etc.; as sulfonate, -toluenesulfonate, dodecylbenzene sulfonate, etc.; as organic phosphate, monododecyl phosphate, didodecyl phosphate, etc. Examples include acid salts. In addition, as a complex, acetylacetone, phthalocyanine i, I, 3-bis (2-thiazolyl imino)
Isoindolines, 1,3-bis(2-pyridylimino)
Examples include complexes such as isoindolines, porphyrins, and bipyridyls.

In the present invention, the final concentration of cobalt catalyst means the concentration of cobalt catalyst in the oxidation reaction apparatus when there is one oxidation reaction apparatus, and when two or more oxidation reaction apparatuses are connected continuously. Cobalt concentration in the final oxidation reactor.

In reality, the cobalt contained in the supplied cyclohexane, the effluent from the previous oxidation reactor, or the effluent from the previous oxidation reactor that has been post-treated, such as by washing with water, and the newly supplied cobalt. The combined concentration of cobalt. The degree of cobalt contained in the supplied cyclohexane or the effluent from the previous oxidation reactor can be measured directly, but it can also be determined indirectly by analyzing the amount of cobalt contained in the waste water from the subsequent water washing process. You can also do that.

The final concentration of the cobalt catalyst used in the present invention is 0.01 pμm or more as cobalt in the reaction mixture. lpμ
less than m. The concentration is 0. When it is higher than lpμm, not only the amount of by-products produced is large, but also the production rate of talohexanone is low. If the concentration is less than 0.01 pμm, the quality of the produced cyclohexanone is poor and it cannot be used as a raw material for the production of ε-aminocaprolactam. The reason for this is not clear, but if the amount of cobalt catalyst is small, the peroxide generated in the oxidation reaction process will not be fully decomposed in the oxidation reaction process, and a large amount of peroxide will remain in the oxidation reaction mixture, resulting in peroxide or peroxide. It is thought that products such as acids changed during post-treatment may not be separated by rectification and may remain in the cyclohexanone, adversely affecting the quality of the cyclohexanone.

After the oxidation reaction, washing with water may be performed to remove impurities such as acids in the oxidation reaction mixture. In addition to water, an aqueous phase after a subsequent alkali treatment or a dilute alkali may be used.

Further, after the oxidation reaction, metal treatment or the like may be performed by a known method in order to decompose the cyclohexyl hydroperoxide in the oxidation reaction mixture into cyclohexanone and cyclohexanol. That is, the oxidation reaction mixture can be made of cobalt catalysts such as those exemplified as cobalt catalysts used in the oxidation reaction step, iron, Nitsukenope vanadium, chromium, molybdenum,
In the presence of catalytic metal compounds such as salts and complexes of ruthenium, manganese, etc. 0.01 to 1100 pp, the temperature is about 80 to 2
By treatment at 00°C and a pressure of about 1-2 (latm), all or part of the cyclohexyl hydroperoxide decomposes into cyclohexanone and cyclohexanol.

According to the present invention, after the oxidation reaction, the oxidation reaction mixture may be treated with an alkali. That is, the reaction mixture in the oxidation reaction step is heated in the presence of alkali metals such as sodium and potassium, hydroxides of alkaline earth metals such as magnesium and calcium, carbonates, bicarbonates, etc., and alkalis such as ammonia. is about 80-200℃, pressure is about 1-20at
By treating under m, acids and the like in the reaction mixture in the oxidation reaction step are neutralized and esters and the like are saponified.

After the oxidation reaction and the above-mentioned post-treatment, unreacted cyclohexane is removed from the reaction mixture by distillation or the like to obtain a mixture of clohexanone and cyclohexanol.

(Effects of the Invention) According to the method of the present invention, the selectivity of cyclohexanone and cyclohexanol, particularly the selectivity of cyclohexanone, is high, the oxidation reaction can be performed stably, and high-quality cyclohexanone can be obtained.

(Example) In order to specifically explain the method of the present invention in detail, Examples will be given and explained below, but the present invention is not limited thereto.

Note that the selectivity used in the description is a value calculated from the number of moles of each component using the following formula.

In addition, the pH value used for quality evaluation of a mixture of cyclohexanone and cyclohexanol is as follows: 5 g of a mixture of cyclohexanone and cyclohexanol is mixed with water/methanol (1/
1) This is the value measured at room temperature of the pH of the solution dissolved in 95 ml. If this value is small, the quality of cyclohexanone obtained by rectification will be poor due to the high content of acidic impurities.

Example 1 An oxidation reaction was carried out using an SUS autoclave with an internal volume of 1 liter and equipped with a gas introduction tube, a reflux condenser, and a water separator. As the first oxidation reaction, cyclohexane 5.
56 mol of cyclohexanone, 0.01 mol of cyclohexanone, and 0.32 pμm of cobalt octoate were charged as cobalt to the entire charging solution. While stirring at 500 rpm, nitrogen was flowed at a flow rate of 75 pl hours and the temperature was raised to 140°C. Oxygen-nitrogen mixed gas (oxygen: 5v).

1%) and the reaction was carried out for 1 hour. After that, the oxygen-nitrogen mixed gas was changed back to nitrogen, and after cooling to room temperature, 2w
The oxidation reaction mixture was obtained by washing twice with t% water.

As a second oxidation reaction, the same operation was repeated by charging the first oxidation reaction mixture and cobalt octoate of 0.24 pμm as cobalt into the oxidation reaction apparatus.

Furthermore, as a third oxidation reaction, the second oxidation reaction mixture was charged into the oxidation reactor, and the same operation was repeated. Although no cobalt catalyst was added, the cobalt contained in the second oxidation reaction mixture made the charged mixture 0. It contained O3 pμm of cobalt. The resulting oxidation reaction mixture contained 1.10% by weight of cyclohexyl hydroperoxide.

The oxidation reaction mixture was treated with an alkali in a conventional manner, and cyclohexane was distilled off to obtain a mixture of cyclohexanone and cyclohexanol. The pH value of the resulting mixture was 7.
It was 0. In addition, the conversion rate of cyclohexane was 5.9 m
o1%, the selectivity of cyclohexanone and cyclohexanol was 71.7m01%, and the production ratio of cyclohexanone was 0.74.

Example 2 In the first and second oxidation reactions, cobalt was 0.32 pμm and 0.32 pμm, respectively. The same operation as in Example 1 was carried out except that cobalt octoate of O8 pμm was charged. In the third oxidation reaction, no cobalt catalyst was charged, but due to the cobalt contained in the second oxidation reaction mixture, the charged reaction mixture was reduced to zero. It contained O2 pμm of cobalt. The oxidation reaction mixture contained 1.45% by weight of cyclohequine hydroperoxide. The pH value of the mixture of cyclohexanone and cyclohexanol obtained from the oxidation reaction mixture was 6.9.

Also, the conversion rate of cyclohexane was 5.3 mo1%, and the selectivity of cyclohexanone and cyclohexanol was 1t71.
The production ratio of cyclohexanone was 0.83.

Example 3 In the first, second, and third oxidation reactions, cobalt was 0.15 pμm and 0.15 pμm, respectively. O8 pμm, 0.
Except that 07pl)m of cobalt octoate was added.
The same operation as in Example 1 was performed. In the third oxidation reaction, the charged reaction mixture contained 0.09 pμm of cobalt due to the cobalt contained in the second oxidation reaction mixture.

The oxidation reaction mixture contains 0
．． It contained 72% by weight. The pH value of the mixture of cyclohexanone and cyclohexanol obtained from the oxidation reaction mixture was 7.5.

In addition, the conversion rate of cyclohexane was 5.9 mo1%, and the selectivity of cyclohexanone and cyclohexanol was 71.6.
mo1%, and the production ratio of cyclohexanone was 0.74.

Example 4 In the first, second and third oxidation reactions, cobalt was Q47 pμm, 0.07 pμm, and 0.07 pμm, respectively.
The same operation as in Example 1 was carried out except that cobalt octoate of O7 pμm was charged. In the third oxidation reaction, the charged reaction mixture contained 0.09 p1)m of cobalt due to the cobalt contained in the second oxidation reaction mixture.

The oxidation reaction mixture is / clohequine hydroperoxide 0
It contained 82% by weight. The OpH value of the mixture of cyclohexanone and cyclohexanol obtained from the oxidation reaction mixture was 7.5.

In addition, the conversion rate of cyclohexane was 5.9 mo1%, and the selectivity of cyclohexanone and cyclohexanol was 71.5.
mo1%, and the production ratio of cyclohexanone was 0.72.

Comparative Example 1 In the first and second oxidation reactions, cobalt was 0.17 pμm and 0.17 pμm, respectively. The same operation as in Example 1 was carried out except that cobalt octoate of O7 pμm was charged. Since no cobalt catalyst was charged in the third oxidation reaction, the amount of cobalt contained in the second oxidation reaction mixture was 0.007p.
Only μm of cobalt was contained.

The oxidation reaction mixture is 1
．． It contained 64% by weight. Since the pH value of the mixture of cyclohexanone and cyclohexanol obtained from the oxidation reaction mixture was 53, the cyclohexanone obtained by rectification cannot be used as a raw material for the production of ε-aminocabrolactum.

Also, the conversion rate of cyclohexane was 6.0 mo1%, and the selectivity of cyclohexanone and cyclohexanol was 1t71.
1mol%, and the production ratio of cyclohexanone was 0.84.

Comparative Example 2 0.32 p μm and 0.24 pμ of cobalt in the first, second and third oxidation reactions, respectively.
The same operation as in Example 1 was performed except that cobalt octoate of 0.18 pμm and 0.18 pμm was charged. In the third oxidation reaction, the charged reaction mixture contained 20 pμm of cobalt due to the cobalt contained in the second oxidation reaction mixture.

The oxidation reaction mixture contains 0
．． It contained 59% by weight. The pH value of the mixture of cyclohexanone and cyclohexanol obtained from the oxidation reaction mixture was 75.

Further, the conversion rate of cyclohexane was 5.9mo]%, and the selectivity of cyclohexanone and cyclohexanol was t71.
Omo was 1%, and the production rate of cyclohexanone was 0.68.

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Claims (1)

[Claims] 1. In a method for producing cyclohexanone and cyclohexanol by oxidizing cyclohexane with molecular oxygen or a gas containing molecular oxygen in the liquid phase in the presence of a cobalt catalyst, the final concentration of the cobalt catalyst is 0 as cobalt.
．． A method for producing cyclohexanone and cyclohexanol, characterized in that the particle size is 0.01 pμm or more and less than 0.1 pμm.