JPS58157741A - Production of cyclohexanone - Google Patents

Abstract

PURPOSE:In the production of cyclohexanone by dehydrogenation of cyclohexanol, a copper chromite supporting a specific amount of potassium is used as a catalyst to increase the yield, inhibiting the formation of by-products for a long period of time. CONSTITUTION:A copper chromite is heat treated at 650-900 deg.C and dipped in an aqueous solution of potassium nitrate or potassium carbonate so that 0.01- 0.5wt%, preferably 0.02-0.4wt%, calculated as potassium, of a potassium compound is included, then the product is calcined at 300-500 deg.C, preferably 330- 450 deg.C, and reductively treated using hydrogen or a hydrogen gas diluted with an inert gas such as nitrogen or argon at 100-500 deg.C, preferably 150-400 deg.C to give copper chromite catalyst in which the atomic ratio of copper to chromium is 8/2-2/8. The resultant catalyst is used to effect dehydrogenation of cyclohexanol to give the objective compound.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cyclohexanone.

Cyclohexanone is usually produced by dehydrogenating cyclohexanol in the presence of a catalyst, but this reaction tends to produce large amounts of by-products such as phenol. Therefore, it is necessary to select a catalyst for use in this reaction that not only has high activity but also produces low levels of by-products. However, when a steel-chromium catalyst, which is a typical conventionally known catalyst, is used, although the catalytic activity is high, the production of a considerable amount of by-products is still unavoidable.

The present applicant has previously proposed a method for improving the drawbacks of copper-chromium catalysts.

(Japanese Unexamined Patent Publication No. 36-20J+/No.) This proposal uses a catalyst obtained by heating a copper-chromium oxide at a specific temperature and then reducing it, which improves its activity as a catalyst and Although a considerable effect on the production rate of by-products can be obtained, it is still not sufficient, and there is still room for further improvement in terms of activity and catalyst life.

In view of the above circumstances, the present inventors conducted various studies to further improve the above-mentioned copper-chromium catalyst.
The present invention was created by discovering that when a chromium-based catalyst is used in the dehydrogenation reaction of cyclohexanol, the reaction content is further improved. In the method for producing cyclohexanone, as a catalyst, (1) heat-treating a copper-chromium oxide at a temperature of 450-900°C; (2) immersing the oxide in a water bath solution of potassium nitrate or potassium carbonate to convert the oxide into potassium; 0.0 / -0
, 3% by weight of the potassium compound is deposited, ■ 300-! The atomic ratio of copper nichrome obtained by firing at a temperature of r00℃ and reduction treatment is g:2 ~
The present invention relates to a method for producing cyclohexanone characterized by using a copper-chromium catalyst with λ: g.

The present invention will be explained in detail below.

The present invention is a method for producing cyclohexanone by dehydrogenating cyclohexanol in the presence of a catalyst, but the cyclohexanol used as a raw material may be obtained by any production method, and is usually obtained by liquid phase air oxidation of cyclohexane. Alternatively, cyclohexanol obtained by hydrogenation reaction of phenol is used.

In the present invention, a copper-chromium catalyst obtained by treating a copper-chromium oxide by the method described below is used, and the ratio of copper dichrome in the copper-chromium catalyst is in the range of: 2 to 1:1 as an atomic ratio.
g, preferably 7:3 to 3 nia. If the chromium content is too low, the durability of the catalyst will be poor, and if it is too high, the catalytic activity will be poor.

The copper-chromium oxide used in the preparation of the catalyst can be easily obtained by, for example, the known methods shown in (1) to (3) below.

■ Water-soluble compounds of copper and chromium, specifically inorganic salts such as nitrates, sulfates, chlorides, formates, acetates,
An aqueous solution with a predetermined copper-nichrome ratio is prepared using an organic salt such as oxalate, and this is combined with caustic soda, a caustic alkali such as caustic potash, soda carbonate, an alkali carbonate such as potassium carbonate, aqueous ammonia, and ammonium carbonate. Copper-chromium hydroxide is precipitated by mixing with a precipitant such as
It is fired at a temperature of about SθO°C.

■ An aqueous solution of a copper salt is added to an aqueous solution of a dichromate such as sodium dichromate or ammonium dichromate with aqueous ammonia, and the resulting precipitate is dried and calcined in the same manner as in (■) above. .

(2) Dip chromium oxide in an aqueous solution of copper salt to adhere the copper salt to the chromium oxide, and dry and bake in the same manner as in (2) above.

■ Immerse oxidized steel in an aqueous solution of chromium salt to adhere the chromium salt to the oxidized steel, dry as in above ■,
Fire.

(2) Copper hydroxide and chromium hydroxide are prepared separately according to the method (2) above, and the hydroxides are mixed and dried and fired in the same manner as in (2) above.

(2) Copper and chromium salts are mixed and calcined at a temperature of about λθθ to 5θ0°C according to a conventional catalyst preparation method.

■ Mix oxidized steel and chromium oxide.

In the present invention, the copper-chromium oxide obtained by the above method is first heat-treated, and the temperature is 6Sθ to 90θ.
℃, preferably 700 to tSO ℃. If the heat treatment temperature is too low, a catalyst with few side reactions cannot be obtained; on the other hand, if the heat treatment temperature is too high, a catalyst with high activity and durability cannot be obtained.

Heat treatment is usually performed until the specific surface area of the copper-chromium oxide is 0. !
;-20tr? 7 g, preferably / ~ /! r
rr? / g. The time required for this is, for example, 8°C for 30 hours, preferably 7 to 20 hours. Further, although the heat treatment is usually carried out in an oxygen-containing gas such as air, it may also be carried out in an inert gas such as nitrogen.

After the heat treatment, the pot-chromium oxide is then subjected to a potassium deposition treatment.

For the potassium adhesion treatment, the pre-8d oxide is immersed in a dilute aqueous solution of potassium nitrate or potassium carbonate, usually about a few percent, for several hours to several hours, usually at room temperature, and then subjected to F treatment using a conventional method.
It is carried out by drying at a temperature of about 70 to 730°C.

The amount of potassium attached is the amount of potassium nitrate or potassium carbonate attached to the oxide after the filtration or drying.
o, oi~o, t 11 as potassium for oxide
The amount of L is preferably θ, O to θ, lI, Ik.

If the amount of potassium deposited is less than the above range, the desired effect cannot be obtained, and if it is more than the above range, the activity of the resulting catalyst will be reduced.

Thus, the copper-chromium oxide subjected to the potassium deposition treatment is then heated to a temperature of 30θ to SθO°C, preferably 330-
The baking process is usually carried out for /-20 hours in a warm summer temperature of 1'& θ°C. If this firing temperature is too low or too high, the effect of supporting potassium will not be exhibited, which is not preferable.

The copper-chromium based oxide after the calcination treatment is finally subjected to a reduction treatment to obtain the potassium-supported copper-chromium based catalyst of the present invention. The reduction treatment can be carried out by well-known means using, for example, hydrogen, carbon oxide, methanol, formalin, or the like. Usually hydrogen or nitrogen, argon,
Using hydrogen diluted with an inert gas such as carbon dioxide, 1
It is preferable to carry out the reduction treatment at a temperature of about 0θ to Sθθ°C, preferably about 15θ to 0°C, until heat generation accompanying the reduction is no longer observed.

The copper-chromium catalyst of the present invention may be used as a powder or after being molded by tabletting, extrusion, or rolling force. Shaping can be carried out at any stage of the catalyst preparation described above.

Further, in the present invention, the catalyst component may contain other metals such as sodium, calcium, barium, zinc, manganese, etc., but the total amount of copper and chromium in the catalyst is 30% as metal. It is desirable that the amount is at least 1% by weight, preferably at least 10% by weight. If the total amount of copper and chromium is too small, the effect of the heat treatment will not be sufficiently manifested, and the catalyst will not be able to satisfy both activity and suppression of side reactions.

In the present invention, a specific amount of potassium is supported on the copper-chromium oxide, but in the present invention, apart from the potassium that is supported later, potassium is supported in the copper-chromium oxide used for catalyst preparation. There is no problem even if it contains.

The dehydrogenation reaction of cyclohexanol in the present invention is usually carried out in a gas phase, using a catalyst as a fixed bed or a fluidized bed, but industrially it is preferable to adopt a fixed bed system.

The reaction temperature is 200 to yoo°C, preferably 8-+25O to 3! rθ°C, particularly preferably 2A; 0 to 30
It is 0°C. If the reaction temperature is too low, the conversion rate will be infertile. On the other hand, if the conversion ratio is high, the conversion rate will increase, but side reactions will increase, which is not favorable. The reaction pressure is not particularly limited and can be applied from reduced pressure to increased pressure, but it is usually best to choose a pressure around normal pressure.

The feed rate of the raw material cyclohexanol is determined by the liquid hourly space velocity (L
H8V) and 0. /-/00 hr-', preferably 0. A: It is best to choose -20hr-18 degrees. Further, the raw material cyclohexanol may be diluted with an inert gas such as nitrogen or steam before being supplied.

The method of the present invention is industrially extremely advantageous because cyclohexanone can be produced in high yield with few by-products, especially over a long period of time.

EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example/ (Preparation of catalyst) Sodium dichromate ysog was dissolved in 2 t of demineralized water, and 2 g of aqueous ammonia 'I! After adding rOmt,
In addition, copper nitrate 72311. Manganese nitrate g i/1
1 and barium nitrate26. /g dissolved in 5 t of demineralized water was added under stirring to form a precipitate. The generated precipitate was filtered, washed with water, dried at 110°C for 3 hours, and then calcined at a temperature of 3θθ°C for 6 hours to obtain an atomic ratio of copper nichrome: manganese: barium of 3θ:3θ:3.
A copper-chromium oxide of :/ was obtained.

This copper-chromium oxide was formed into a cylindrical tablet (height: 6 mm, diameter: 6%) by tableting, and then heat treated in air at a temperature of 7° C. for 2 hours. It was immersed in a wt% potassium nitrate aqueous solution at room temperature for 20 hours. Then, the copper-chromium oxide was centrifuged and placed in air for 70 minutes.
The granules S- were dried at a temperature of 100°C for 10 hours, fired at a temperature of 100°C for 1 hour, and then crushed to a size of about J,y% diameter. 'Xn stainless steel tubular reactor was filled with a mixed gas of H2S VDl % and N293 vol 1% at a rate of 3017 hr at 110 °C for 6 hours, and then /zao-;tso
The catalyst of the present invention was obtained by circulating the mixture at a temperature of 0.degree. C. for a certain period of time and performing a reduction treatment.

The amount of potassium supported in the catalyst obtained in this way is
0.0 as potassium for copper and chrono in terms of oxides. / 9 wt% was rare.

(Dehydrogenation reaction of cyclohexanol) A dehydrogenation reaction of cyclohexanol was carried out using the catalyst obtained as described above. The inlet temperature of the tubular reactor filled with the catalyst was maintained at 0°C and the outlet temperature at 2SO°C, and preheated and vaporized crude cyclohexanol (cyclohexanol g Owt%, cyclohexanone g Owt%) was added to the reactor.
wt%, other components/, 2 wt%) to LH8V
, 20 hr-', and the reactor internal pressure was 0.3
! ; K9/cF! Continuous reactions were carried out at G.

The cyclohexanol conversion rate after an hour from the start of the reaction was determined by analyzing the reaction product in a gas chromatography chamber, and the results are shown in Table 1.
I got 5.

Examples 2 to 3 In the method of Example//, by changing the amount of potassium nitrate used in the catalyst preparation step, the catalyst before potassium loading was adjusted as shown in Table 7, and the same as Example// was carried out. A test was conducted using a large force, and the results shown in the first article were obtained.

Example In the method of Example/, a potassium carbonate water bath was used in place of the potassium nitrate aqueous solution in the catalyst preparation process. Using L, a test was conducted in the same manner as in Example/, and 814
/The results shown in the table were obtained.

Comparative Example/Example/In the method of Example/, immersion in a potassium nitrate aqueous bath solution was omitted in the catalyst preparation step, and a test was conducted in the same manner as in Example/, and the results shown in Table 1 were obtained.

12- Table 1 (Note) Amount of K supported The content as potassium relative to the sum of copper oxide and chromium oxide in the catalyst before reduction treatment is shown.

Example S In the catalyst preparation process of Example /, the potassium-supported copper-chromium oxide lIt after the calcination treatment was filled into a stainless steel tubular reactor with an inner diameter of 32% and a length of 6 m without pulverization. , H,3VOI% and N2? A reduction treatment was carried out by flowing a mixed gas of VOI% at a rate of 3-0 O1/hr at a temperature of 1 gθ°C for 2 hours and at a temperature of /gO to 0°C for 5 hours.

Next, the inlet and outlet temperatures of the reactor were maintained at 270° C., and crude cyclohexanol similar to that in Example/was preheated and vaporized as required.
Continuous reaction was carried out by feeding at a rate of hr-'.

The cyclohexanol conversion rate p, xlIθ hours after the start of the reaction was determined in the same manner as in Example 1, and the results shown in Table 2 were obtained.

Comparative Example U In the method on the left of Example 2, using a catalyst that was not immersed with an aqueous potassium nitrate solution in the preparation step of the catalyst, a test was conducted in the same manner as in Example 2, and the results are shown in Table 2. I got it.

Table 2 1] 5- 285-

Claims (1)

[Claims] (1) In the method of producing cyclohexanone by dehydrogenating cyclohexanol, as a catalyst: (1) heat treatment of a copper-chromium oxide at a temperature of 650 to 000C, (2) immersion treatment in an aqueous solution of potassium nitrate or potassium carbonate. 0.07 to 0-A as potassium to oxide
The atomic ratio of copper nichrome obtained by depositing iM% of the potassium compound, (1) firing at a temperature of 300 to 500°C, and (2) reduction treatment is such that the atomic ratio of copper nichrome is from g:2 to
T: A method for producing cyclohexanone characterized by using which copper-chromium catalyst.