JP2006199685A - Method for producing cyclohexanone oxime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method with which the selectivity of cyclohexanone oxime is further improved and the cyclohexanone oxime can be produced in higher yield in a continuous ammoximation reaction of cyclohexanone. <P>SOLUTION: The method for production is carried out as follows. A reaction mixture in which a titanosilicate catalyst is dispersed is made to exist in a reactor and the cyclohexanone, hydrogen peroxide and ammonia are fed from a cyclohexanone feed port, a hydrogen peroxide feed port and an ammonia feed port into the reactor, respectively to produce the cyclohexanone oxime by the continuous reaction. In the process, a circulating flow of the reaction mixture is formed and the hydrogen peroxide feed port and ammonia feed port are located in the order mentioned on the downstream side of the circulating flow on the basis of the cyclohexanone feed port. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing cyclohexanone oxime by an ammoximation reaction of cyclohexanone. Cyclohexanone oxime is useful as a raw material for ε-caprolactam.

  As one of the methods for producing cyclohexanone oxime, a method for ammoximation of cyclohexanone with hydrogen peroxide and ammonia in the presence of a titanosilicate catalyst has been proposed (for example, see Patent Documents 1 to 4). This method does not require neutralization of sulfuric acid with ammonia as in the conventional method of oximation with hydroxylamine sulfate, and since it is a solid catalytic reaction, it is easy to separate the product and the catalyst. Has the advantage of

  The ammoximation reaction is advantageously performed in a continuous manner in terms of productivity or operability. For example, in Patent Documents 2 and 3, the reaction is performed while cyclohexanone, hydrogen peroxide and ammonia are supplied to the reactor. It is disclosed that the ammoximation reaction is continuously carried out by extracting the liquid phase of the reaction mixture in which the catalyst in the vessel is dispersed through a filter. Patent Document 4 discloses that the ammoximation reaction is carried out continuously while supplying the catalyst together with the raw material to the reactor.

JP-A-62-59256 JP-A-6-49015 Japanese Patent Laid-Open No. 6-92922 JP 2000-72737 A

  An object of the present invention is to provide a process capable of producing cyclohexanone oxime in a higher yield by further improving the selectivity of cyclohexanone oxime in the continuous ammoximation reaction.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by forming a circulation flow of a reaction mixture in which a catalyst is dispersed in a reactor, and supplying each raw material from a predetermined position. The headline and the present invention were completed. That is, in the present invention, a reaction mixture in which a titanosilicate catalyst is dispersed is present in a reactor, and cyclohexanone, hydrogen peroxide, and ammonia are supplied to the reactor from a cyclohexanone supply port, a hydrogen peroxide supply port, and an ammonia supply port, respectively. Then, a process for producing cyclohexanone oxime by a continuous reaction, wherein the reaction mixture forms a circulating flow, and hydrogen peroxide is supplied to the downstream side of the circulating flow with respect to the cyclohexanone supply port. The method is characterized in that the port and the ammonia supply port are provided in this order.

  According to the present invention, a continuous ammoximation reaction of cyclohexanone can be carried out with high selectivity, and cyclohexanone oxime can be produced in high yield.

  Hereinafter, the present invention will be described in detail. The titanosilicate used in the present invention is a zeolite containing titanium, silicon, and oxygen as elements constituting the skeleton, and the skeleton may be substantially composed of titanium, silicon, and oxygen. Further, other elements may be included as an element constituting the element. As the titanosilicate, those having an atomic ratio of silicon / titanium of 10 to 1000 are preferably used, and the shape thereof may be, for example, fine powder or pellet. Titanosilicate can be prepared, for example, by the method described in JP-A-56-96720.

  Cyclohexanone oxime can be produced by using the above titanosilicate as a catalyst and ammoximation of cyclohexanone with hydrogen peroxide and ammonia in the presence of this catalyst.

  The raw material cyclohexanone may be obtained, for example, by an oxidation reaction of cyclohexane, may be obtained by a hydration or dehydrogenation reaction of cyclohexene, or may be obtained by a hydrogenation reaction of phenol. It may be what was made.

  Hydrogen peroxide is usually produced by the so-called anthraquinone method, and is generally commercially available as an aqueous solution having a concentration of 10 to 70% by weight, so that it can be used. Hydrogen peroxide can also be produced by reacting hydrogen and oxygen in an organic solvent in the presence of a solid catalyst supporting metal palladium. When hydrogen peroxide is used in this method, the reaction mixture An organic solvent solution of hydrogen peroxide obtained by separating the catalyst from the catalyst may be used in place of the aqueous hydrogen peroxide solution. The usage-amount of hydrogen peroxide is 0.5-3 mol normally with respect to 1 mol of cyclohexanone, Preferably it is 0.5-1.5 mol. Examples of hydrogen peroxide include phosphates such as sodium phosphate, polyphosphates such as sodium pyrophosphate and sodium tripolyphosphate, pyrophosphate, ascorbic acid, ethylenediaminetetraacetic acid, nitrotriacetic acid, aminotriacetic acid, A stabilizer such as diethylenetriaminepentaacetic acid may be added.

  Ammonia may be used in the form of gas, liquid, or water or an organic solvent solution. The amount of ammonia used is preferably 1 mol or more, more preferably 1.5 mol or more, per 1 mol of cyclohexanone.

  The ammoximation reaction may be carried out in a solvent, and examples of the reaction solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, s-butyl alcohol, t-butyl alcohol, t -Alcohols such as amyl alcohol, water, or a mixed solvent thereof is preferably used.

  The reaction temperature of the ammoximation reaction is usually 50 to 120 ° C, preferably 70 to 100 ° C. The reaction pressure may be normal pressure, but in order to increase the amount of ammonia dissolved in the liquid phase of the reaction mixture, the reaction is preferably performed under pressure. In this case, an inert gas such as nitrogen or helium is used. It may be used to adjust the pressure.

  In the present invention, the ammoximation reaction is carried out continuously. In this continuous reaction, a predetermined amount of a reaction mixture in which a catalyst is dispersed is usually retained in a continuous reactor such as a stirred tank type or a loop type, and in this, cyclohexanone, hydrogen peroxide, ammonia, and a solvent if necessary. The reaction mixture is withdrawn in approximately the same amount as these raw materials while feeding. Here, in extracting the reaction mixture, it is preferable to extract only the liquid phase through a filter or the like so that the catalyst remains in the reactor. When the catalyst is also extracted, it is necessary to supply the catalyst to the reactor. As the catalyst to be supplied, an unused new catalyst is usually used for the reaction, but the recovered catalyst separated from the extracted reaction mixture is used for regeneration treatment, for example, removal of organic substances by firing, etc. After being attached, it can be reused, and a new catalyst and a recovered catalyst may be used in combination.

  Although the catalyst concentration in the reaction mixture depends on the activity and reaction conditions, the weight per volume of the reaction mixture (catalyst + liquid phase) is usually 1 to 100 g / L, preferably 5 to 100 g / L. Preferably it is 10-100 g / L. At the start of the reaction, for example, a catalyst dispersion obtained by dispersing the catalyst in a solvent may be charged into the reactor, and supply of raw materials may be started here, and extraction of the reaction mixture may be started. Further, as the reactor, from the viewpoint of preventing decomposition of hydrogen peroxide, it is preferable to use a glass-lined one or a stainless steel one.

  In the present invention, in the continuous ammoximation reaction, a circulation flow of the reaction mixture in which the catalyst is dispersed in the reactor is formed, and in this, cyclohexanone, hydrogen peroxide and ammonia are respectively supplied to the cyclohexanone supply port, the peroxide. Supply from hydrogen supply port and ammonia supply port. At this time, the positional relationship between the supply ports is such that the hydrogen peroxide supply port and the ammonia supply port are arranged in this order on the downstream side of the circulating flow, that is, in the flow direction, with respect to the cyclohexanone supply port. To do. Thus, by forming a circulation flow of the reaction mixture in which the catalyst is dispersed in the reactor and supplying each raw material in a predetermined positional relationship, side reactions such as cyclohexanone condensation reaction can be suppressed. The selectivity of cyclohexanone oxime can be increased.

  FIG. 1 is a cross-sectional view schematically showing an example of a reaction apparatus used for a continuous ammoximation reaction according to the present invention. That is, in the loop type (donut type) reactor 1, a circulation flow of the reaction mixture as shown by the white arrow is formed by a pump or the like. Then, in this circulating flow, cyclohexanone 2 ′ is supplied from the supply port 2a at the tip through the supply pipe 2, and on the downstream side, hydrogen peroxide 3 ′ passes through the supply pipe 3 and The ammonia 4 ′ is supplied from the supply port 3a at the distal end and further supplied downstream from the supply port 4a through the supply pipe 4. Further, from the outlet 1a provided in the reactor 1, a reaction mixture 1 'having the same amount as that of these feeds is withdrawn. The upstream / downstream relationship between the supply ports 2a, 3a, and 4a is relative. For example, if the hydrogen peroxide supply port 3a is used as a reference, the ammonia supply port 4a is disposed downstream of the supply port 2a. It can be seen that the cyclohexanone supply port 2a is disposed on the downstream side, and if the ammonia supply port 4a is used as a reference, the cyclohexanone supply port 2a is disposed on the downstream side, and further the peroxide is disposed on the downstream side. It can be seen that the hydrogen supply port 3a is arranged.

  FIG. 2 is a longitudinal sectional view schematically showing another example of the reaction apparatus used in the continuous ammoximation reaction according to the present invention. In this example, a stirring tank type reactor 1 is used, and a cylindrical partition wall 5 is provided so as to surround the stirring blade 6 in order to form a circulation flow of the reaction mixture as indicated by an outline arrow therein. ing. That is, due to the rotation of the stirring blade 6, a downward flow of the reaction mixture is formed inside the partition wall 5, that is, in the horizontal central portion in the reactor 1, and outside the partition wall 5, that is, in the horizontal peripheral edge portion in the reactor 1. Then, an upward flow of the reaction mixture is formed, and as a whole, a circulation flow of the reaction mixture composed of the downward flow and the upward flow is formed. As in FIG. 1, cyclohexanone 2 ′ and 2 ′ are supplied from the supply ports 2 a and 2 a through the supply pipes 2 and 2 into the circulating flow, and the liquid depth downstream thereof. The hydrogen peroxide 3 ', 3' is supplied from the supply ports 3a, 3a at the tip of the hydrogen peroxide 3 ', 3' through the supply pipes 3, 3 at a shallow part, and the ammonia 4 at a deep part at the downstream side. ', 4' is supplied from the supply ports 4a, 4a at the front end thereof through the supply pipes 4, 4. Further, from the outlet 1a provided in the reactor 1, a reaction mixture 1 'having the same amount as that of these feeds is withdrawn.

  1 shows an example in which one supply port 2a, 3a, and 4a is provided, and FIG. 2 shows an example in which two supply ports 2a, 3a, and 4a are provided, but the number is arbitrary. For example, a sparger can be used. FIG. 1 shows an example in which one reaction mixture outlet 1a is provided on the downstream side of the hydrogen peroxide supply port 3a and upstream of the ammonia supply port 4a. In FIG. 2, the reaction mixture outlet 1a is provided. However, the position and the number thereof are arbitrary and may be adjusted as appropriate, although one is provided downstream of the ammonia supply port 4a and upstream of the cyclohexanone supply port 2a. Further, although not shown in FIGS. 1 and 2, when a solvent or other component supply port is separately provided, one or a plurality of supply ports may be provided at appropriate positions.

  In order to further improve the selectivity of cyclohexanone oxime, it is desirable that the ammonia concentration in the liquid phase of the reaction mixture be 1% by weight or more. By doing so, the conversion of cyclohexanone can also be improved. The ammonia concentration is preferably 1.5% by weight or more, and usually 10% by weight or less, preferably 5% by weight or less.

  The positional relationship of the cyclohexanone supply port, the hydrogen peroxide supply port, and the ammonia supply port with respect to the circulation flow of the reaction mixture is as described above, and further, the positional relationship of the reaction mixture with respect to the liquid depth direction, that is, the vertical direction. As shown in FIG. 2, among the cyclohexanone supply port, the hydrogen peroxide supply port, and the ammonia supply port, it is preferable to provide the ammonia supply port at the bottom and provide the hydrogen peroxide supply at the top. At this time, the cyclohexanone supply port may be provided at an intermediate position between the ammonia supply port and the hydrogen peroxide supply port, for example, as shown in FIG.

  For the post-treatment operation of the obtained reaction mixture, a known method can be appropriately employed. For example, as described in Patent Document 3, after concentrating the liquid phase of the reaction mixture, cyclohexanone oxime is removed from this concentrate. Cyclohexanone oxime can be separated by extracting with an organic solvent and then concentrating the extract again.

  Examples of the present invention will be described below, but the present invention is not limited thereto. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Cyclohexanone and cyclohexanone oxime were analyzed by gas chromatography, and the conversion of cyclohexanone, the selectivity of cyclohexanone oxime, and the yield of cyclohexanone oxime were calculated based on the analysis results.

Example 1
The reactor used in this example is as shown schematically in FIG. That is, in a stirred tank reactor 1 made of SUS316, 6.83 parts of cyclohexanone 2 ′, 4.44 parts of 60% hydrogen peroxide 3 ′, and 2.23 parts of ammonia 4 ′ were respectively used. While supplying from the supply ports 2a, 3a and 4a and further supplying 23.6 parts of water-containing t-butyl alcohol (water 12%), the liquid phase 1 ′ of the reaction mixture was passed through the filter from the discharge port 1a. By extracting, a continuous reaction was performed under conditions of a temperature of 85 ° C., a pressure of 0.35 MPa (absolute pressure), and a residence time of 1.5 hours. During this time, titanosilicate (manufactured by Polymeri Europa) was present in the reaction mixture in the reactor 1 at a concentration of 30 g / L. As a result of analyzing the liquid phase 1 ′ of the reaction mixture extracted 20 hours after the start of the reaction, the conversion of cyclohexanone was 99.8%, the selectivity of cyclohexanone oxime was 99.4%, and the yield of cyclohexanone oxime was 99. 2%. The ammonia concentration was 2%.

It is sectional drawing which shows typically the example of the reaction apparatus used for this invention. It is a longitudinal cross-sectional view which shows typically another example of the reaction apparatus used for this invention.

Explanation of symbols

1 …… Reactor,
2 …… Cyclohexanone supply pipe,
3 ... Hydrogen peroxide supply pipe,
4 ... Ammonia supply pipe,
1a: Reaction mixture outlet,
2a ... cyclohexanone supply port,
3a ... Hydrogen peroxide supply port,
4a ... ammonia supply port,
1 '... reaction mixture,
2 '... cyclohexanone,
3 '... hydrogen peroxide,
4 '... ammonia,
5 ...
6: Stirring blade.

Claims (3)

  A reaction mixture in which a titanosilicate catalyst is dispersed is present in the reactor, and cyclohexanone, hydrogen peroxide, and ammonia are supplied from the cyclohexanone supply port, the hydrogen peroxide supply port, and the ammonia supply port to the continuous reaction. The reaction mixture forms a circulating flow, and a hydrogen peroxide supply port and an ammonia supply port are provided downstream of the circulation flow with respect to the cyclohexanone supply port. A method characterized by being provided in this order.   The process according to claim 1, wherein the ammonia concentration in the liquid phase of the reaction mixture is 1% by weight or more. The method according to claim 1 or 2, wherein among the cyclohexanone supply port, the hydrogen peroxide supply port, and the ammonia supply port, the ammonia supply port is provided at the lowermost portion and the hydrogen peroxide supply port is provided at the uppermost portion.

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