JP2533908B2 - Method for producing aromatic alcohols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (i) Object of the Invention [Field of Industrial Application] The present invention relates to a method for producing aromatic alcohols. More specifically, the present invention relates to a method for producing aromatic alcohols by reducing hydrogen in the liquid phase of aromatic hydroperoxides in the presence of a hydrogen reduction catalyst.

[Conventional technology]

Aromatic alcohols are useful as intermediates and solvents for various organic chemicals, and industrially they are advantageously produced by reduction of aromatic hydroperoxides. JP-B-39-26961 discloses that cumene hydroperoxide or dicumyl peroxide dissolved in cumene is added to Pd, Ni.
Has been proposed for producing α-cumyl alcohol by reducing with hydrogen in the presence of a hydrogenation catalyst such as Since this reaction is accompanied by heat generation, it is recommended to use a solvent in order to smoothly proceed the reaction and prevent side reactions as much as possible, and a solvent immiscible with water such as hydrocarbons is used as the solvent. ing. However, in a system using the above-mentioned solvent, the catalyst activity lowers unexpectedly rapidly, and therefore a method of using a lower aliphatic alcohol as a solvent is disclosed in JP-A-55-69527.
Proposed in the issue. Further, a method of carrying out the reduction reaction in the coexistence of an amine or a compound capable of being converted to an amine during the hydrogen reduction reaction in order to produce an aromatic alcohol in a high yield is proposed in JP-A-60-174737. Has been done.

[Problems to be solved by the invention]

However, the hydrogen reduction method described in the above publication requires a complicated separation step from the aromatic alcohol to be the product and the aliphatic alcohol or amines having different properties. However, there is a problem in that it is not a method that can be industrially advantageously carried out even if the aromatic alcohol can be produced by hydrogenating.

(Ii) Structure of the Invention [Means for Solving the Problems] The inventors of the present invention have conducted further diligent studies in order to solve the above problems, and as a result, have found that aromatic hydroperoxides can be used as hydrogen reduction catalysts. It was found that high activity can be stably obtained by carrying out the hydrogen reduction reaction with the concentration of the aromatic hydroperoxides supplied to the reaction system when hydrogen is reduced in the liquid phase in the presence of 4% or less. Proposed as a method for producing alcohols.

Then, the present inventors have examined the hydrogen reduction reaction of aromatic hydroperoxides in more detail, and when using a fixed bed flow tube type reactor in which the catalyst separation step is unnecessary, the hydrogen reduction reaction It was found that high activity can be stably obtained by regulating the superficial liquid velocity in the range of 0.10 to 5 cm / sec, and the present invention has been completed.

That is, the method for producing aromatic alcohols of the present invention, when producing aromatic alcohols by hydrogen reducing aromatic hydroperoxides in a liquid phase flow system in the presence of a fixed bed hydrogen reduction catalyst, Such a hydrogen reduction reaction is carried out under the condition that the superficial liquid velocity is 0.10 to 5 cm / sec, and in the above reaction method, the concentration of aromatic hydroperoxides is 4% by weight or less in the reaction system. It is a method characterized by supplying to.

(Detailed Description of the Invention) Aromatic Hydroperoxides The aromatic hydroperoxides to be subjected to the hydrogen reduction reaction of the present invention include, for example, α-phenylethyl hydroperoxide, cumene hydroperoxide, and cymene hydroperoxide. Oxide, m- or p-diisopropylbenzene monohydroperoxide, m
-Or p-diisopropylbenzene dihydroperoxide, isopropylnaphthalene hydroperoxide, etc., or a composition containing at least one of these.

Hydrogen The amount of hydrogen supplied to the hydrogen reduction reaction system in the present invention is
The amount of hydrogen is 1 to 50 times, preferably 1 to 30 times, and most preferably 1 to 20 times the amount of hydrogen required for the hydrogen reduction reaction of the target aromatic hydroperoxides. If too much hydrogen is supplied, it may result in loss, which may result in a huge amount of auxiliary equipment such as hydrogen recovery system and circulation system, and unnecessary side reactions.

Hydrogen reduction catalyst The hydrogen reduction catalyst used in the method for producing aromatic alcohols of the present invention may be one having the hydrogen reduction catalytic ability of aromatic hydroperoxides, for example, platinum group metal such as Pd, Ru or Ni. And the like as a catalyst component. In this type of hydrogen reduction catalyst, the catalyst component is usually supported on a suitable carrier, and the carrier is a heat-resistant inorganic compound carrier, for example, a synthetic gel carrier such as alumina or silica, or diatomaceous earth, or a porous carrier. Examples include natural inorganic carrier such as clay.

Reaction Mode As the reaction mode in the method for producing aromatic alcohols of the present invention, a fixed bed liquid phase flow tube reactor can be used in any mode. The flow of the liquid containing the aromatic hydroperoxides may be either upward flow or downward flow.

Superficial liquid linear velocity The superficial linear velocity of the raw material liquid containing the aromatic hydroperoxides to be subjected to the hydrogen reduction reaction of the present invention is 0.10 to 5 cm /
Sec, preferably 0.10-4 cm / sec, most preferably 0.10-3c
It is necessary to regulate in the range of m / sec. If the superficial liquid velocity is less than 0.10 cm / sec, stable activity cannot be obtained, and problems such as deterioration of hydrogenation catalyst efficiency occur.
In addition, when the superficial liquid velocity is higher than 5 cm / sec, there arises a problem that ΔP of the catalyst layer becomes large, and stable activity cannot be obtained.

Solvent As a solvent for diluting the aromatic hydroperoxides in the method for producing an aromatic alcohol of the present invention,
Any substance capable of dissolving the aromatic hydroperoxides and the aromatic alcohols which are the products may be used, and examples thereof include aliphatic hydrocarbons, aromatic hydrocarbons and aromatic alcohols. For example, in the case of cumene hydroperoxide, cumene exists as a solvent in the production process of cumene hydroperoxide, and cumene can be used as a solvent as it is, or the product of hydrogenated cumene hydroperoxide can be used as a solvent. It is also a good method to circulate mill alcohol as a solvent.

Concentration of aromatic hydroperoxides In the hydrogen reduction reaction in the method for producing aromatic alcohols of the present invention, the concentration of aromatic hydroperoxides in the raw material liquid supplied to the reactor is 4% by weight or less, preferably 0.01 wt% to 4 wt%, most preferably 0.1
It is necessary to regulate the content within the range of not less than 4% by weight. If the concentration exceeds 4% by weight, heat generation is large, a reaction temperature is not stable, high activity cannot be obtained, and side reactions easily occur.

Reaction temperature The hydrogen reduction reaction in the method for producing aromatic alcohols of the present invention is usually carried out at 0 to 150 ° C, preferably 10 to 120 ° C. If the reaction temperature is too high, side reactions such as a decomposition reaction of the aromatic hydroperoxides become violent, which is not preferable. Further, if the reaction temperature is too low, a problem such as a slow reaction rate occurs.

Reaction Pressure The total pressure of the hydrogen reduction reaction in the method for producing an aromatic alcohol of the present invention is usually atmospheric pressure to under pressure, preferably atmospheric pressure to 50 kg / cm ² G, and most preferably atmospheric pressure to 30 kg / cm ² G. Is. Since the hydrogen reduction reaction of aromatic hydroperoxides proceeds easily, even if the reaction pressure is increased more than necessary, the construction cost of the device is only increased and it is wasteful. Problems such as hydrogen reduction reaction occur.

[Examples, etc.]

The catalyst production examples, examples, and comparative examples will be described in more detail below. The percentages given in these examples are by weight unless otherwise stated.

Example of catalyst production The concentration of γ-alumina molded into a 3 mmφ × 3 mm cylindrical shape was
It was impregnated with a 0.6% by weight aqueous solution of palladium chloride and dried at 110 ° C. for one day.

The dried product is then stored under a stream of hydrogen at a temperature of 400 ° C for 16
After the time reduction treatment, a hydrogen reduction catalyst having a composition of Pd (0.3%) / γ-Al ₂ O ₃ was obtained.

Example 1 A stainless reaction tube having an inner diameter of 12.7 mm equipped with a thermometer protection tube having an outer diameter of 4 mm was charged with 25 ml of the catalyst prepared according to the catalyst production example.
Was filled. The catalyst layer inlet temperature was set to 45 ° C and the
% Cumene hydroperoxide (hereinafter sometimes abbreviated as CHP) -cumene solution 1.6 l / h, hydrogen 16 l / h,
The reaction pressure was 7.5 kg / cm ² G. The superficial liquid velocity at this time was 0.39 cm / sec. The reaction rate of CHP 8 hours after supplying the CHP / cumene solution was 5.4 mol / kg catalyst · hour.

Example-2 The same operation as in Example-1 was performed except that the supply rate of the 3.3% CHP / cumene solution was 6.0 l / hour and the hydrogen supply rate was 60 l / hour. The superficial liquid velocity at this time was 1.46 cm / sec. The reaction rate of CHP 8 hours after supplying the CHP / cumene solution was 6.8 mol / kg catalyst · hour.

Example-3 The same operation as in Example-1 was performed except that the CHP / cumene solution supply rate was 12 l / hour and the hydrogen supply rate was 120 l / hour. The superficial liquid velocity at this time was 2.92 cm / sec. The reaction rate of CHP 8 hours after the CHP / cumene solution was supplied was 6.7 mol / kg catalyst.hour.

Comparative Example-1 Using a stainless steel reaction tube having an inner diameter of 30 mm equipped with a thermometer protection tube having an outer diameter of 6 mm, the feed rate of 3.5% CHP / cumene solution was 1.0 l / hr, and the hydrogen feed rate was 10 l / hr. The same operation as in Example 1 was performed except that the above was performed. The superficial linear velocity at this time was 0.04 cm / sec. 8 after supplying CHP and cumene solution
The reaction rate of CHP at the hour was only 0.9 mol / kg catalyst / hour.

Comparative Example-2 The same operation as in Example-1 was performed except that the supply rate of the 3.5% CHP / cumene solution was 24 l / hour and the hydrogen supply rate was 240 l / hour, but the ΔP of the catalyst layer was large. Stable operation was impossible. The superficial liquid velocity at this time is 5.84 cm /
It was seconds.

Example-4 500 ml of the catalyst prepared according to the catalyst production example was filled in a stainless reaction tube having an inner diameter of 27.2 mm equipped with a thermometer protection tube having an outer diameter of 6 mm. The catalyst layer inlet temperature was set to 45 ° C, and CHP3.5
%, Cumyl alcohol 77.0%, cumene 19.5% liquid 2.4 l / h, hydrogen 24 l / h, reaction pressure 5 kg / cm ² G
Continuously supplied. The superficial liquid velocity at this time is 0.12 cm /
It was seconds. 8 hours after supply, CHP conversion rate is 99.8%, 20
The conversion rates on day 1 and day 150 were 99.7% and 99.9%, respectively, and stable activity was obtained. Further, the yield of cumyl alcohol based on the supplied CHP was 99% in all cases.

Example-5 The same operation as in Example-4 was performed except that the catalyst layer was 100 ml. 2nd day, 20th day, 120
The CHP conversion rates on the day were 60.3%, 59.5% and 59.7%, respectively, and stable activity was obtained.

Comparative Example-3 CHP 3.3%, cumyl alcohol 20.5%, cumene 76.2%
The same operation as in Example-5 was performed, except that the liquid having the composition of (1) was supplied at a rate of 800 ml / hour and the hydrogen was supplied at a rate of 8 l / hour. The superficial liquid velocity at this time was 0.04 cm / sec. After feeding the raw material liquid 2
The CHP conversion rate on the day was 64.5%, but the conversion rates on the 20th and 120th days were 58.0% and 38.2%, respectively, indicating a decrease in activity.

〔The invention's effect〕

According to the production method of the present invention, aromatic hydroperoxides can be stably hydrogen-reduced with a high conversion rate, and corresponding aromatic alcohols can be produced with a high selectivity.

Front page continuation (72) Inventor Tatsuro Ashizawa 17 Towada, Kamisu-cho, Kashima-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd. Kashima Plant (56) Reference JP 59-16843 (JP, A) JP 61-130249 (JP, A) JP-A-59-110639 (JP, A) JP-A-58-159433 (JP, A) JP-B-45-13928 (JP, B1)

Claims (2)

(57) [Claims] 1. When producing aromatic alcohols by reducing aromatic hydroperoxides with hydrogen in a liquid phase flow system in the presence of a fixed bed hydrogen reduction catalyst, a superficial liquid line of the hydrogen reduction reaction. A process for producing an aromatic alcohol, which is carried out under a condition of a speed of 0.10 to 5 cm / sec. 2. The method for producing aromatic alcohols according to claim 1, wherein the aromatic hydroperoxides are supplied to the reaction system at a concentration of 4% by weight or less.