JPH07188082A - Production of phenol - Google Patents

Abstract

PURPOSE:To provide a method for producing phenol in a high yield using a catalyst having high activity and selectivity. CONSTITUTION:The characteristic of this method for producing phenol comprises subjecting cyclohexanone to dehydrogenation reaction in the presence of a catalyst consisting of magnesium oxide, palladium element and an alkali metal fluoride.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing phenol, which is widely used as a synthetic intermediate for synthetic resins, surfactants, pharmaceuticals and the like.

[0002]

2. Description of the Related Art Conventionally, various methods have been known as a method for producing phenol. Cumene is oxidized with oxygen to synthesize cumene hydroperoxide, and the cumene hydroperoxide is decomposed with an acid. Thus, the cumene method for producing phenol and acetone is mainly used. However, this cumene method has a feature that acetone is co-produced, and since the supply of acetone is becoming excessive in recent years, development of a method for producing phenol without by-product of acetone is desired.

A dehydrogenation reaction of cyclohexanone is known as a method for producing phenol which does not produce acetone as a by-product. As a catalyst for the dehydrogenation reaction of cyclohexanone,
For example, U.S. Pat. No. 3,580,970, nickel, those Group VIII metal and tin, such as platinum supported on a carrier, or, Journal of Catalysis, 50, 419 (1977) , the palladium or inorganic nickel and tin Those supported at the same time on a carrier are disclosed. However, all of these catalysts have problems in activity, selectivity, catalyst life, etc., and improvements have been desired.

[0004]

OBJECT OF THE INVENTION The object of the present invention is to solve the above problems and to provide a method for producing phenol in a high yield using a catalyst having high activity and selectivity.

[0005]

TECHNICAL FIELD The present invention relates to a method for producing phenol, which comprises subjecting cyclohexanone to a dehydrogenation reaction in the presence of a catalyst comprising magnesium oxide, elemental palladium and an alkali metal fluoride. It is a thing.

The catalyst composed of magnesium oxide, elemental palladium, and alkali metal fluoride used in the present invention is
It can be prepared by subjecting a mixture of magnesium oxide, a compound of elemental palladium, and an alkali metal fluoride to heat treatment.

The magnesium oxide is not particularly limited, and magnesium oxide obtained by thermally decomposing magnesium carbonate, basic magnesium carbonate, magnesium hydroxide or the like, or industrial magnesia can be used, but in the present invention, , Especially BET specific surface area of 5 to 17
High-purity ultrafine powder single crystal magnesium oxide having a specific surface area of 0 m ² / g (specific surface area diameter of 0.01 to 0.2 μm) and a purity of 99.9% or more can be preferably used.

Such high-purity ultrafine single crystal magnesium oxide is synthesized by the method disclosed in Japanese Examined Patent Publication No. 2-289, that is, a method of oxidizing magnesium vapor and an oxygen-containing gas in a turbulent diffusion state. You can BET
It is also possible to produce magnesium oxide having a specific surface area of more than 170 m ² / g, which is also useful in the present invention, but the production cost becomes extremely high, and the handling of ordinary powder becomes difficult. Therefore, the practicality is low at present. On the other hand, if the specific surface area is less than 5 m ² / g, the catalytic activity will decrease, which is not preferable.

As the compound of the palladium element, acetylacetonato salt of palladium, nitrate, acetate, carbonyl compound and the like are used. Of these, palladium nitrate and acetate are preferable.

As the alkali metal fluoride, for example,
Lithium fluoride, sodium fluoride, potassium fluoride,
Rubidium fluoride or the like is used. Of these, sodium fluoride and potassium fluoride are preferable.

The content of palladium element in the catalyst is preferably 0.05 to 10 wt% with respect to magnesium oxide, and 0.01 to
1 wt% is more preferable. If the amount is less than the lower limit, sufficient catalytic activity cannot be obtained, and if the amount exceeds the upper limit, metal sintering tends to be observed, which lowers the activity and is economically disadvantageous.

The content of alkali metal fluoride in the catalyst is
1 to 10 wt% is preferable for magnesium oxide, and 2
~ 5 wt% is more preferred. Above the upper limit, uniform loading becomes difficult.

The catalyst used in the present invention can be prepared by a conventionally known catalyst preparation method such as an impregnation method or an ion exchange method.

For example, it can be prepared by the following method. First,
A solution of a palladium element compound in water, acetone, alcohol or the like and a solution of an alkali metal fluoride in water, acetone, alcohol or the like are impregnated into magnesium oxide that has been calcined in advance and dried. The impregnation of the palladium element compound and the arali metal fluoride may be carried out separately and sequentially, but it is preferable to carry out the impregnation simultaneously using a mixed solution. Then, the impregnated material is prepared by heat treatment at a temperature of 350 to 550 ° C.

The catalyst thus prepared is charged into a reaction vessel, reduction treatment with hydrogen is carried out at a temperature of 300 to 450 ° C. for activation, and then cyclohexanone is circulated to carry out a dehydrogenation reaction. The reaction vessel is not particularly limited, but for example, a fixed bed flow reactor can be preferably used.
The reaction temperature is usually 300 to 450 ° C, preferably 350 to 400
℃. The reaction pressure is not particularly limited and may be normal pressure or increased pressure.

The form of the catalyst is not particularly limited, and it is possible to use a powder or a powder obtained by compression-molding the powder. The used catalyst can be reused by recalcining. The re-baking can be performed by heat treatment at a temperature of 350 to 550 ° C.

[0017]

EXAMPLES The present invention will be described more concretely with reference to the following examples.

Example 1 High-purity ultrafine single crystal pre-calcined at 550 ° C. in a mixed solution of a solution of 0.005 g of palladium nitrate in 100 mL of acetone and a solution of 0.04 g of potassium fluoride in 100 mL of ethanol. Magnesium oxide (BET specific surface area 131m ²
/ g, purity 99.98% or more) 2.00 g was dispersed, and this was dried under reduced pressure and baked at 350 ° C for 2 hours. At this time, the addition amount of each component was 0.1 wt% and 2.0 wt% with respect to magnesium oxide as a salt of palladium and potassium fluoride as a salt, respectively.

The obtained Pd / KF / MgO catalyst was charged as a powder into an atmospheric fixed bed flow reactor, and reduction treatment with hydrogen was carried out at 350 ° C. for 2 hours. Then, cyclohexanone was supplied at LHSV = 3.0 to carry out the reaction. Hydrogen gas was passed as a carrier gas at 330 mL / min. The product at that time was analyzed by gas chromatography, and the results of investigating the changes with time of the conversion rate and the selectivity are shown in Table 1.

[0020]

[Table 1]

Conversion (conv. (%)) And selectivity (s) in the table
el (%)) was calculated by the following formulas. Conversion (conv. (%)) = (AB) / A Selectivity (sel (%)) = C / (AB) A: amount of supplied cyclohexanone B: amount of recovered cyclohexanone C: amount of recovered phenol

Comparative Example 1 In place of the Pd / KF / MgO catalyst, palladium element was added in an amount of 0.1.
Example 1 was repeated except that a Pd / MgO catalyst containing 1 wt% and containing no KF was used. The results are shown in Table 2.

[0023]

[Table 2]

Example 2 The same procedure as in Example 1 was carried out except that the catalyst shown in Example 1 was molded by a tablet molding machine and crushed and used as a catalyst having a particle size of 1 mm to 760 μm. . The results are shown in Table 3.

[0025]

[Table 3]

Example 3 The procedure of Example 1 was repeated, except that the catalyst used in the reaction of Example 2 was recalcined in air at 420 ° C. for 6 hours. The results are shown in Table 4.

[0027]

[Table 4]

[0028]

INDUSTRIAL APPLICABILITY According to the present invention, by using a catalyst composed of palladium, magnesium oxide and alkali metal fluoride, which has high activity and selectivity in dehydrogenating cyclohexanone to produce phenol, a high yield can be obtained. Phenol can be produced. Furthermore, by re-calcining the used catalyst in the air, the initial activity can be restored, and the catalyst can be repeatedly used, which is a great industrial advantage.

Claims (1)

[Claims] 1. A method for producing phenol, which comprises subjecting cyclohexanone to a dehydrogenation reaction in the presence of a catalyst comprising magnesium oxide, elemental palladium, and an alkali metal fluoride.