JPS59110639A - Production of aromatic alcohol - Google Patents

Abstract

PURPOSE:The hydrogenation of aromatic hydroperoxide is conducted using a fixed bed of a palladium catalyst of more than 200m<2>/g. Pd surface area to enable stabilized production of the titled substance for a long period of time without palladium leaching away. CONSTITUTION:A catalyst containing palladium with a surface area ranging from 200m<2>/g. Pd, preferably to 350m<2>/g. Pd is used as a fixed bed to carry out the hydrogenation of aromatic peroxides to give the titled compound. The temperature of the hydrogenation reaction is 0-120 deg.C, liquid space velocity is 0.1- 20hr<-1> and the feed of hydrogen is 1-10 times the stoichiometric amount based on the peroxide. The palladium-containing catalyst means any catalyst containing palladium only or additionally carrier that has a strength and particle sizes enough to be used as a fixed bed catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for hydrogen reduction of aromatic hydroperoxides to produce the corresponding aromatic alcohols.

Known methods for producing aromatic alcohols from aromatic hydroperoxides include reduction with an aqueous solution of sulfites and hydrogen reduction in the presence of a hydrogenation catalyst. A method for producing α-cumyl alcohol by hydrogen reduction of cumene hydroperoxide using a catalyst supported on a carrier such as palladium has been shown. Methods for producing aromatic alcohols are known.

This hydrogen reduction reaction of aromatic hydroperoxides is accompanied by a large amount of heat, so in order to prevent side reactions and promote the dissolution of hydrogen so that the reaction proceeds smoothly, we use water such as saturated hydrocarbons or aromatic hydrocarbons with saturated side chains. A solvent that is immiscible with is used.

However, this method of using a solvent has the disadvantage that the activity of the catalyst quickly decreases. Therefore, industrially, the amount of palladium-containing catalyst used is small, the catalyst activity does not decrease for a long time, and the catalyst can be used repeatedly. There is a need for the development of a method that can do this.

As a method to meet this requirement, palladium surface area of 10 to 200n? A method has been proposed in which a tertiary aromatic hydroperoxide is hydrogen-reduced in the presence of a palladium catalyst of /g-Pd to prevent deterioration of the catalyst due to elution of palladium metal supported on a carrier (Japanese Unexamined Patent Application Publication No. 1983-1972).
-167238). However, in this method, it is essential that the palladium surface area is 200 In/g-Pd or less, and if a palladium catalyst with a surface area greater than this value is used, the palladium elution rate will be significantly high and the activity will decline significantly over time. It ends up.

The present inventors have conducted extensive research to overcome the above-mentioned drawbacks of the method for producing aromatic alcohols from aromatic hydroperoxides by hydrogen reduction in the presence of a palladium catalyst, and have found that palladium has a surface area of 20 On? /g-P
We discovered that when a fixed-bed solid-liquid contact reaction is used as a reaction method using a palladium catalyst of d or more, there is surprisingly little elution of palladium, and the desired aromatic alcohol can be obtained more efficiently. Based on this knowledge, we have completed the present invention.

That is, in the present invention, when reducing aromatic hydroperoxide with hydrogen, the palladium surface area is 200 nl'/g-P.
The present invention provides a method for producing an aromatic alcohol, characterized in that the reaction is carried out using a palladium-containing catalyst of d or more as a fixed bed.

The purpose of the method of the present invention is to provide a method for industrially and efficiently producing aromatic alcohols useful as intermediates and solvents for various organic chemicals.

The present invention will be explained in more detail below.

Specific examples of aromatic hydroperoxides to which the method of the present invention is applied include α-phenylethyl hydroperoxide,
Examples include cumene hydroperoxide, cymene hydroperoxide, diisopropylbenzene monohydroperoxide, diisopropylbenzene dihydroperoxide, and aromatic hydroperoxides having 8 or more carbon atoms are preferred. The aromatic hydroperoxide may be dissolved in a suitable solvent, and this solvent is not particularly limited as long as it dissolves the aromatic hydroperoxide.

The aromatic hydroperoxide may also be a mixture with other substances, for example, a mixture of unreacted cumene and tertiary hydroperoxide, which is usually obtained when cumene is oxidized to produce the corresponding hydroperoxide. .

In the method of the present invention, the concentration of aromatic hydroperoxide in the solvent or mixture is appropriately determined depending on the type of aromatic hydroperoxide and the reaction conditions of the hydrogen reduction reaction, but is generally about 1 to 90% by weight. Defined by range.

The palladium-containing catalyst used in the present invention is one in which palladium is supported on a carrier such as activated carbon, alumina, carborundum, titania, silica-alumina, or silica, in addition to palladium itself, and is generally required as a fixed bed catalyst. Any material may be used as long as it has strength and particle size. Such a palladium-containing catalyst has a palladium surface area of 200 m/
It is necessary to be g-Pd. This allows the catalyst to have extremely high activity and a long life. Furthermore, it is possible to sufficiently deal with increases in load due to changes in operating conditions. Furthermore, palladium elution is reduced even during long-term continuous operation. That is, efficient reduction with good conversion rate and selectivity is possible. Note that the surface area of palladium (hereinafter abbreviated as MSA) mentioned here is measured by a -carbon oxide adsorption method.

When the MSA is less than 200♂/g-Pd, it becomes impossible to cope with load fluctuations due to fluctuations in operating conditions, and the conversion rate decreases. In addition, the amount of palladium eluted increases and the activity decreases over time. On the other hand, the upper limit of MSA is not particularly limited, but is preferably up to 350 rrl/g-Pd.

Such a radium-containing catalyst with an MSA of 200 d/g-Pd or more may have an average particle size of 0.5 to 2.
An example is a carrier in which approximately 0.1 to 2% by weight of radium is supported.

The palladium-containing catalyst may also contain other noble metal compounds such as platinum, rhodium, ruthenium, etc. as co-catalysts. Note that the surface area of palladium can be adjusted according to a conventional method.

As a reactor for forming the fixed bed of the palladium-containing catalyst, a known fixed bed reactor such as a multi-tubular reactor or a single-tubular reactor can be used.

In the present invention, the optimal range of reaction conditions for hydrogen reduction is determined depending on the type of aromatic hydroperoxide, but the reaction temperature is preferably 0 to 120°C. Below 0°C, the reaction progresses slowly and industrially requires cooling means other than industrial water.
If the temperature exceeds .degree. C., the self-decomposition reaction of the aromatic hydroperoxide is likely to be accelerated, resulting in an increase in by-products.

For other reaction conditions, the reaction temperature is between 0 and 5°F.
/cat G, the amount of reaction liquid is 0.1 to 20 hr-1 in liquid standard hourly space velocity (LH3V) to the catalyst, and the amount of water ice gas supplied is 1 to 10 stoichiometric amount to aromatic hydroperoxide. About double the amount is preferable.

Thus, the present invention provides palladium with a surface area of 200 nI/g.
- A fixed bed reactor packed with a palladium-containing catalyst of Pd or higher is used, whereby the corresponding aromatic alcohol can be obtained almost quantitatively by the hydrogen reduction reaction of the aromatic hydroperoxide, and the catalyst can be used for a long time. It has an excellent effect of not losing its activity even with time reactions.

In addition, palladium elution, loss due to catalyst abrasion, and deterioration, which were disadvantages of conventional suspension methods, are not observed over a long period of time, and there is no need for catalyst separation or recovery such as static separation or filtration. , aromatic alcohol can be produced stably and continuously for a long period of time.

Next, the present invention will be explained in more detail based on examples. In addition, the compositional analysis in the examples was carried out by iodometry for aromatic hydroperoxides, and by liquid chromatography for other aromatic alcohols.

Example 1 The reactor was equipped with a liquid flow inlet and a gas outlet with an inner diameter of 4 mm at the top and a gas inlet with an inner diameter of 4 mm at the bottom, and a metal sintered plate for gas dispersion at the bottom of the cylinder. with an inner diameter of 25 m and a length of 600 mm with a liquid outlet formed just above it.
A stainless steel cylindrical reactor equipped with a thermometer and a pressure gauge was used. The reaction cylinder of this reactor is equipped with a jacket, allowing cooling water to pass therethrough. In addition, a 100-mesh stainless steel gilt copper plate is provided at the liquid outlet to prevent the catalyst from flowing out.

2N loaded with 0.5% by weight of palladium in the above reactor
Palladium surface area (MSA) in an alumina sphere with a diameter of 295
180m of m7g-Pd was filled. Nitrogen gas was introduced into the reactor through the gas inlet, and cumene was introduced into the reactor through the liquid inlet. After keeping the pressure constant at 3"/a+t a, the nitrogen gas was switched to hydrogen gas, and the cumene was replaced with cumene hydrochloride. Peroxide (25.5% by weight cumene solution)
I switched to In a steady state, the feed molar specific force of H2/cumene hydroperoxide is 2.5, and the cumene solution of cumene hydroperoxide (hereinafter abbreviated as CHP) is LH8V.
2. It was continuously fed at a rate of Ohr.

The reaction temperature is the hot spot part (hereinafter abbreviated as TH8)
The amount of cooling water in the jacket was adjusted so that the temperature was 65°C or less to stabilize the reaction. 5 hours after the start of the reaction, TH
A sample was taken from the liquid outlet at 863° C., and as a result of analysis, almost no CHP was detected, and dimethylphenyl carbinol (hereinafter abbreviated as DMP C) was produced almost quantitatively. CHP conversion rate 99.8 mol%, DMPC
Selectivity selectivity 1 layer 0 Example 2 Gas inlet at the top, liquid gas mixed phase outlet at the bottom,
A cylindrical reactor similar to that of Example 1 was used, except that a gas-liquid dispersion plate was provided in the upper part of the cylinder, and a 100-mesh stainless wire mesh was attached to the lower part as a support for the catalyst. In this reactor, 200 mt of a palladium MSA307m7g-Pd catalyst was placed in an activated carbon molded article (1 mmφ x 4 pieces) supporting 0.5% by weight of palladium.
Filled.

A CHP-cumene solution with a CHP concentration of 8.0% by weight was added to this reactor at a rate of 500 mt/hr (LH8V 2.5
hr') and hydrogen at a rate of 1 2.6 Nl
-/hr (Hz/CHp molar ratio, 2.5). The reaction pressure is 3”9/crti G
operation was continued without cooling water being passed through the jacket.

5 hours after the start of the reaction, TH8 was at 74°C, and a sample was taken from the liquid outlet and analyzed, and the CHP conversion rate was 99.6 mol%.
, a DMPC selectivity of 99.7 mol% was obtained. After 24 hours of continued operation under the same conditions, the CHP conversion rate was 99.9 mol, the DMPC selectivity was 99.9 mol, and the
Even after 20 hours, the CHP conversion rate was 99.9 mol/D.
The MPC selectivity was 99.9 molti, and no decrease in activity was observed.

As a result of analyzing the amount of palladium supported on the catalyst after 720 hours of operation, it was found that the amount was 0.47% by weight, which was almost the same as that in the initial state.

Example 3 The catalyst was made by supporting 0.5 wt% palladium on alumina having a diameter of 2.0 mm, and the MSA of palladium was 296 ni/g.
The reaction was carried out in the same manner as in Example 2, except that the reactor was changed to -Pd. TH8 temperature 65~
It was operated for 720 hours at 78°C, and the CHP conversion rate was 9.
9.5-99.9 molti, DMPC selectivity 99.6-9
A result of 9.9 molti was obtained, and no decrease in activity was observed during this period.

Further, as in Example 2, the amount of palladium supported on the catalyst after use was analyzed, and it was found to be 0.46% by weight, which was almost the same as that in the initial state.

Comparative Example A reaction was carried out in exactly the same manner as in Example 2, except that as a catalyst, a 2.0 mm diameter alumina supported with 0.5 wt% palladium and an MSA of 114 d/g-Pd was used. However, TH8 was in the range of 50 to 60°C.

After continuous operation for 720 hours after the start of the reaction, samples were periodically collected from the liquid outlet and analyzed, and the CHP conversion rate was 88.
．． 5-92.0 molti, DMPC selectivity 99.6-99
．． 8 molti, indicating a low CHP conversion rate. Furthermore, when we analyzed the amount of palladium supported on the catalyst after use, we found that
A weight loss of 0.41% by weight and 9% was observed.

Patent applicant Mitsui Toatsu Chemical Co., Ltd. Agent Patent Attorney Ii 1) Toshizo

Claims (1)

[Claims] A method for producing an aromatic alcohol, which comprises using a palladium-containing catalyst having a palladium surface area of 200 d/g-Pd or more as a fixed bed in hydrogen reduction of an aromatic hydroperoxide.