JP2007182428A - Method for producing cyclohexanone oxime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce cyclohexanone oxime at a low cost by reducing a catalyst cost in the the ammoximation of the cyclohexanone. <P>SOLUTION: This method for producing the cyclohexanone oxime comprises (1) a process of ammoximating cyclohexanone with hydrogen peroxide and ammonia in the presence of a titanosilicate and a silicon compound other than the titanosilicate, and (2) a process of calcining the titanosilicate used in the process (1) under an atmosphere of an oxygen-containing gas, and using the titanosilicate calcined in the process (2) in the process (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing cyclohexanone oxime by ammoximation of cyclohexanone.

  As a method for producing cyclohexanone oxime, a method is known in which cyclohexanone is ammoximation with hydrogen peroxide and ammonia using titanosilicate as a catalyst (see, for example, Patent Documents 1 to 4). In this ammoximation, since the catalytic activity of titanosilicate usually decreases with time, it is necessary to replace titanosilicate in order to maintain the conversion rate of cyclohexanone at a predetermined value or higher. This may be a problem in terms of catalyst cost. For this reason, for example, Japanese Patent Application Laid-Open No. 2004-83560 (Patent Document 5) proposes that a decrease in the catalytic activity of titanosilicate is suppressed by allowing a silicon compound other than titanosilicate to coexist.

JP-A-62-59256 JP-A-63-130575 JP-A-6-49015 Japanese Patent Laid-Open No. 6-92922 JP 2004-83560 A

  However, it is difficult to completely suppress the decrease in the catalytic activity of titanosilicate, and it is also necessary to replace it, and used titanosilicate is generated as a so-called spent catalyst. Therefore, as a result of intensive studies to further reduce the catalyst cost by activating and reusing this used titanosilicate, the present inventors have found that in the ammoximation, titanosilicate as disclosed in Patent Document 5. When a silicon compound other than the above is coexisted, the catalytic activity of the used titanosilicate is effectively recovered by calcination using an oxygen-containing gas, compared to the case where the silicon compound is not coexisted. As a result, the present invention has been completed.

That is, the present invention
Step (1): Ammoximation of cyclohexanone with hydrogen peroxide and ammonia in the presence of a silicon compound other than titanosilicate and titanosilicate, and Step (2): the titanosilicate used in step (1). The present invention provides a process for producing cyclohexanone oxime, which comprises a step of firing in an atmosphere of an oxygen-containing gas and using the titanosilicate fired in step (2) in step (1).

  ADVANTAGE OF THE INVENTION According to this invention, the catalyst cost in the ammoximation of cyclohexanone can be reduced, and cyclohexanone oxime can be manufactured at low cost.

  Hereinafter, the present invention will be described in detail. The titanosilicate used for the catalyst in the present invention contains titanium, silicon, and oxygen as elements constituting the skeleton, and the skeleton may be substantially composed only of titanium, silicon, and oxygen. Further, other elements may be included as elements constituting the skeleton. As the titanosilicate, those having an atomic ratio of silicon / titanium of 10 to 1000 are suitably used, and the shape thereof may be fine powder, and if necessary, molded into a pellet form using a binder. It may be one that has been made or may be carried on a carrier. Typical examples of titanosilicate include TS-1 (MFI type), TS-2 (MEL type), Ti-MCM-22 (MWW type), Ti-MCM-41, and the like.

  Cyclohexanone oxime is produced by ammoximation of cyclohexanone with hydrogen peroxide and ammonia using the above titanosilicate as a catalyst [step (1)]. This ammoximation can be carried out as a solid catalytic reaction in which the catalyst titanosilicate is dispersed as a solid phase in the reaction mixture. The amount of titanosilicate present in the reaction system is usually 1 to 200 g / L as the weight per volume (solid phase + liquid phase) of the reaction mixture.

  The raw material cyclohexanone may be obtained, for example, by oxidation of cyclohexane, may be obtained by hydration or dehydrogenation of cyclohexene, or may be obtained by hydrogenation of phenol. It may be.

  The usage-amount of hydrogen peroxide is 0.5-3 mol times normally with respect to cyclohexanone, Preferably it is 0.5-1.5 mol times. 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 includes stabilizers such as phosphates such as sodium phosphate, polyphosphates such as sodium pyrophosphate and sodium tripolyphosphate, pyrophosphate, ascorbic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid. It may be added.

  The amount of ammonia used is usually 1 mol times or more, preferably 1.5 mol times or more with respect to cyclohexanone, and is used in excess of hydrogen peroxide so as to remain in the reaction mixture. Is good. Ammonia may be used in a gaseous form, in a liquid form, or as a solution in water or an organic solvent.

  Ammoximation is usually performed using water and / or an organic solvent as a reaction solvent. Examples of the organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, s- Alcohols such as butyl alcohol, t-butyl alcohol and t-amyl alcohol; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; ethers such as tetrahydrofuran, dioxane, diisopropyl ether and t-butyl methyl ether; Can be mentioned.

  In the present invention, in the ammoximation, as disclosed in Patent Document 5, a silicon compound other than titanosilicate (hereinafter sometimes simply referred to as “silicon compound”) coexists with a titanosilicate as a catalyst. By adopting such a prescription, it is possible to suppress a decrease in the catalytic activity of titanosilicate, and in turn reduce the replacement frequency of titanosilicate, thereby reducing the catalyst cost. In addition, the amount of titanosilicate present in the reaction system can be reduced, and the catalyst cost can be reduced from this point.

  The decrease in the catalytic activity of titanosilicate is considered to be caused by the elution of the active site due to elution of silicon or the poisoning of the active site due to the adsorption of impurities. And, the decrease in the catalytic activity of this titanosilicate is suppressed by the coexistence of the silicon compound. By the elution of silicon from the silicon compound, the elution of silicon from the titanosilicate is suppressed correspondingly, It is considered that the adsorption of impurities to the titanosilicate is suppressed by the adsorption of impurities to the silicon compound. Therefore, as the silicon compound, those in which silicon is easily eluted and those in which impurities are easily adsorbed are preferably used. In the case of a solid silicon compound, those having a large surface area and those having a small particle size are preferably used. .

  As the silicon compound, those containing silicon and oxygen, particularly those having a silicon-oxygen bond are preferably used, and examples thereof include silica, silicic acid, silicate, and silicate ester. Here, the silica may be crystalline silica such as silicalite, or amorphous silica such as fumed silica or silica gel. Silicic acid or a salt thereof may be orthosilicic acid or a condensed acid thereof or a salt thereof, and may be crystalline or amorphous, or a metallosilicate other than titanosilicate. It is also possible to use. In addition, tetrasilicate orthosilicate is preferably used as the silicate ester, and the alkyl group usually has 1 to 4 carbon atoms.

  The amount of the silicon compound present in the reaction system is preferably adjusted as appropriate depending on the properties of the silicon compound and the form of introduction into the reaction system. For example, when the solid silicon compound is introduced as it is, or the solid silicon compound is dispersed in an organic solvent or water and introduced as a dispersion liquid such as a sol, the amount of the silicon compound present in the reaction system is titanosilicate. On the other hand, it is usually 0.1 to 20 times by weight, and the silicon compound is preferably dispersed as a solid phase in the reaction mixture. In addition, when the liquid silicon compound is introduced as a solution as it is, or the solid or liquid silicon compound is dissolved in an organic solvent or water, the amount of the silicon compound present in the reaction system is the titanosilicate. On the other hand, it is usually 0.0001 to 0.5 times by weight, and it is preferable not to deposit the silicon compound in the reaction mixture.

  The ammoximation may be carried out batchwise or continuously, but from the viewpoint of productivity and operability, it is preferably carried out continuously. The formulation for introducing the raw materials is appropriately selected. In the case of a batch system, for example, the reactor may be prepared by charging cyclohexanone, ammonia, titanosilicate, a silicon compound and a solvent into the reactor and supplying hydrogen peroxide thereto. The reactor may be charged with cyclohexanone, titanosilicate, silicon compound and solvent, and hydrogen peroxide and ammonia may be supplied thereto, or the reactor may be charged with titanosilicate, silicon compound and solvent, You may carry out by supplying cyclohexanone, hydrogen peroxide, and ammonia here.

  In the case of a continuous type, when using a silicon compound that can be dispersed as a solid phase in the reaction mixture, a predetermined amount of the reaction mixture in which the titanosilicate and the silicon compound are dispersed is retained in the reactor, and cyclohexanone, While supplying hydrogen peroxide, ammonia and a solvent, it is preferable to extract the reaction mixture in the same amount as these raw materials. In this case, the reaction mixture is extracted only through the filter and the liquid phase. The solid phase titanosilicate and the silicon compound are preferably extracted and remain in the reactor. Also, when using a silicon compound that can be dissolved as a solute in the reaction mixture, a predetermined amount of the reaction mixture in which titanosilicate is dispersed is retained in the reactor, and cyclohexanone, hydrogen peroxide, ammonia, silicon While supplying the compound and solvent, it is preferable to extract the reaction mixture in approximately the same amount as these raw materials. At this time, the reaction mixture is extracted only through the filter as in the above. The solid phase titanosilicate should remain in the reactor. In addition, as a reactor, from the viewpoint of preventing decomposition of hydrogen peroxide, a reactor lined with fluororesin or glass or a stainless steel reactor is preferably used.

  The reaction temperature for ammoximation is usually 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and usually 120 ° C. or lower, preferably 110 ° C. or lower, more preferably 100 ° C. or lower. The reaction pressure may be normal pressure, pressurization, or reduced pressure, but in order to increase the amount of ammonia dissolved in the reaction mixture, the reaction is preferably performed under pressure. In this case, nitrogen, helium, etc. The inert gas may be used to adjust the pressure.

  As described above, even if the ammoximation is carried out in the presence of a silicon compound, it is difficult to completely suppress the decrease in the catalytic activity of titanosilicate, and in order to maintain the conversion of cyclohexanone above a predetermined value After all, it is necessary to replace the titanosilicate. Therefore, in the present invention, the used titanosilicate generated by this replacement is activated and reused. Thereby, the catalyst cost can be further reduced.

  Activation of the used titanosilicate is performed by firing in an atmosphere of an oxygen-containing gas [step (2)]. This calcination is not sufficient for the recovery of catalytic activity for used titanosilicate generated by ammoximation in the absence of a silicon compound, but used titanosilicate generated by ammoximation in the presence of a silicon compound. A sufficient catalytic activity recovery effect is exhibited for silicates.

  Air is usually used as the oxygen-containing gas, but pure oxygen may be used. These may be diluted with an inert gas such as nitrogen or carbon dioxide, but in this case, the oxygen concentration is preferably 5% by volume or more. If the firing temperature is too low, it takes a long time, and is usually 250 ° C. or higher, preferably 300 ° C. or higher, and usually 600 ° C. or lower, preferably 550 ° C. or lower. The firing time is appropriately adjusted according to the firing temperature and the like, but is usually about 5 minutes to 10 hours. In addition, although the pressure at the time of baking is arbitrary, what is necessary is just to carry out by a normal pressure normally.

  Firing may be performed batchwise or continuously. In the case of a batch type, it is preferable that a predetermined amount of used titanosilicate is charged in a baking furnace such as an oven and an oxygen-containing gas is circulated therein. In the case of a continuous type, it is preferable to circulate an oxygen-containing gas in a kiln such as a kiln, introduce a used titanosilicate at a predetermined rate, hold it for a predetermined time, and then extract it. .

  When used titanosilicate is mixed with a silicon compound, it may be fired after being separated from the silicon compound, or may be fired together with the silicon compound. Moreover, before baking, if necessary, it may be washed with water or an organic solvent, or may be pre-dried.

  The regenerated titanosilicate thus recovered from the catalytic activity obtained by calcination of the used titanosilicate can be reused in the previous ammoximation [step (1)]. Specifically, it may be used for replenishment when replacing titanosilicate corresponding to a decrease in catalyst activity. For example, when ammoximation is carried out batchwise, use recovered in batches or several batches. What is necessary is just to extract at least a part of the used titanosilicate and supply the regenerated titanosilicate. Also, when performing ammoximation in a continuous manner, a part of the used titanosilicate is extracted from the reaction system at an appropriate interval during operation, and regenerated titanosilicate is replenished, or the operation is stopped. What is necessary is just to extract at least a part of the collected used titanosilicate and supply the regenerated titanosilicate. The extracted used titanosilicate is reused as a recycled titanosilicate after firing. When the silicon compound is extracted together with the used titanosilicate, the silicon compound may be replenished together with the replenishment of the regenerated titanosilicate. At this time, if the regenerated titanosilicate is fired together with the silicon compound, the regenerated titanosilicate and the silicon compound can be replenished by replenishing the fired product. If necessary, new titanosilicate and / or silicon compound may be replenished. The amount of new silicon compound to be replenished is preferably an amount corresponding to the amount of Si discharged out of the reaction system during the reaction. In the continuous reaction, the amount of Si discharged out of the reaction system may be determined based on the amount of the extracted reaction mixture by measuring the Si concentration in the extracted reaction mixture. Further, the amount of new titanosilicate to be replenished may be appropriately determined according to the catalytic activity that is still lowered even when the reaction is performed as described above.

  As for the post-treatment operation of the reaction mixture for ammoximation, a known method can be employed as appropriate. For example, as described in Patent Document 4, by distilling the liquid phase of the reaction mixture, the solvent and the remaining unreacted Ammonia is separated and recovered as a fraction, and a bottomed liquid containing cyclohexanone oxime can be obtained. Subsequently, cyclohexanone oxime is extracted from the bottoms with an organic solvent, and the extract is washed with water if necessary, concentrated, and further distilled if necessary to obtain purified cyclohexanone oxime. And epsilon caprolactam can be manufactured by attaching | subjecting the cyclohexanone oxime obtained in this way to the Beckmann rearrangement in a liquid phase or a gaseous phase.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
(A) Ammoximation with new titanosilicate An autoclave with a capacity of 300 mL lined with fluororesin on the inner surface, 1.5 g of titanosilicate (TS-1) and silica gel [Wakogel B-Wako Pure Chemical Industries, Ltd.] 0] 8 g was charged and dispersed in 100 mL of water-containing t-butyl alcohol (15% by weight of water). In this, 19.6 g / hour of cyclohexanone, 34.8 g / hour of hydrous t-butyl alcohol (15% by weight of water), 6.45 g / hour of ammonia (1.9 mole times of cyclohexanone), and 60 weight % Hydrogen peroxide solution was supplied at a rate of 13.0 g / hr (1.15 mol times cyclohexanone), and the reaction mixture was passed through a filter so that the volume of the reaction mixture in the autoclave was maintained at 100 mL. By extracting the liquid phase, ammoximation was carried out continuously. During this time, the reaction temperature was kept at 95 ° C., and the reaction pressure was kept at 0.35 MPa by pressurizing with helium gas. As a result of analyzing the liquid phase of the reaction mixture extracted from the autoclave 5.5 hours after the start of operation by gas chromatography, the conversion of cyclohexanone was 99.1% and the selectivity for cyclohexanone oxime was 99.5%. Subsequently, while performing timely gas chromatography analysis, the operation was continued until the cyclohexanone conversion rate became 90% or less, and the time from the start of operation to the end of operation was obtained as the operable time. As a result, the operable time was 290 hours. there were.

(A ′) Amoximation by New Titanosilicate In the above (a), the amount of titanosilicate and silica gel used was doubled to carry out ammoximation. That is, the amount of titanosilicate used was changed to 3.0 g, and the amount of silica gel used was changed to 16 g. The driving time was 628 hours.

(B) Calcination of used titanosilicate After filtering the reaction mixture in the autoclave after the operation in (a ′) above, the solid after filtration was washed with hydrous t-butyl alcohol (water 12 wt%), Washed with water. The washed solid was dried in air at 110 ° C. for 8 hours and then calcined at 350 ° C. for 2 hours to recover 15.83 g (recovery rate 83.3%) of a regenerated titanosilicate / silica gel mixture.

(C) Amoximation by regenerated titanosilicate The above (a) except that 9.5 g of the regenerated titanosilicate / silica gel mixture obtained in (b) above was used instead of 1.5 g of titanosilicate and 8 g of silica gel. Ammoximation was performed as described above. The operable time was 321 hours, which was equal to or longer than the operable time (290 hours) in (a) above.

Comparative Example 1
(A) Amoximation by a new titanosilicate Ammoximation was carried out in the same manner as in Example 1 (a) except that silica gel was not used. The driving time was 144 hours.

(A ′) Amoximation by New Titanosilicate In the above (a), the amount of titanosilicate used was doubled to make an amoxime. That is, ammoximation was performed in the same manner as (a) except that the amount of titanosilicate used was changed to 3.0 g. The operating time was 530 hours.

(B) Calcination of used titanosilicate After filtering the reaction mixture in the autoclave after the operation in (a ′) above, the solid after filtration was washed with hydrous t-butyl alcohol (water 12 wt%), Washed with water. The washed solid was dried in air at 110 ° C. for 8 hours and then calcined at 350 ° C. for 2 hours to recover 1.65 g of regenerated titanosilicate (recovery rate 55%).

(C) Amoximation by regenerated titanosilicate Ammoximation was performed in the same manner as (a) except that 1.5 g of regenerated titanosilicate obtained in (b) above was used instead of 1.5 g of titanosilicate. went. The operable time was 86 hours, which was considerably shorter than the operable time (144 hours) in (a) above.

Comparative Example 2
Ammoximation was performed in the same manner as in Example 1 (a) except that 1.5 g of the regenerated titanosilicate obtained in Comparative Example 1 (b) was used instead of 1.5 g of titanosilicate. The operable time was 149 hours, which was considerably shorter than the operable time (290 hours) of Example 1 (a).

Example 2
(A) Amoximation by new titanosilicate The amount of titanosilicate used was changed to 2 g, and instead of 8 g of silica gel, 3 g of fumed silica (CAB-O-SIL M-7D from CABOT) was used. Was ammoximed as in Example 1 (a). The operating time was 466 hours.

(B) Calcination of used titanosilicate The reaction mixture in the autoclave after the operation in (a) above is filtered, and the solid after filtration is washed with water-containing t-butyl alcohol (water 12% by weight), and then water. Washed with. The washed solid was dried in air at 110 ° C. for 8 hours and then calcined at 350 ° C. for 2 hours to recover 2.75 g (recovery rate 55%) of a regenerated titanosilicate / fumed silica mixture.

(C) Amoximation by regenerated titanosilicate In place of 2 g of titanosilicate and 3 g of fumed silica, 2.75 g of the regenerated titanosilicate / fumed silica mixture obtained in (b) and 2.25 g of fumed silica were used. Ammoximation was performed in the same manner as (a) except that it was used. The operating time was 459 hours.

(B-2) Calcination of used titanosilicate After filtering the reaction mixture in the autoclave after the operation in (c) above, the solid after filtration was washed with hydrous t-butyl alcohol (water 12 wt%). And washed with water. The washed solid was dried in air at 110 ° C. for 8 hours and then calcined at 350 ° C. for 2 hours to recover 3.82 g (recovery rate 76.4%) of a regenerated titanosilicate / fumed silica mixture. .

(C-2) Amoximation by regenerated titanosilicate In place of 2 g of titanosilicate and 3 g of fumed silica, 3.82 g of the regenerated titanosilicate / fumed silica mixture obtained in the above (b-2) and fumed silica Ammoximation was performed in the same manner as (a) except that 1.18 g was used. The driving time was 421 hours.

Claims (3)

Step (1): Ammoximation of cyclohexanone with hydrogen peroxide and ammonia in the presence of a silicon compound other than titanosilicate and titanosilicate, and Step (2): the titanosilicate used in step (1). A method for producing cyclohexanone oxime, comprising a step of firing in an atmosphere of an oxygen-containing gas, wherein the titanosilicate fired in step (2) is used in step (1).   The method according to claim 1, wherein the firing is performed at a temperature of 250 ° C. or higher in the step (2). The method according to claim 1 or 2, wherein the silicon compound other than titanosilicate used in step (1) is selected from silica, silicic acid, silicate and silicate ester.