JPH1160523A - Production of 1,6-hexanediol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain 1,6-hexanediol in high yield by reaction of a specific compound such as adipic acid with hydrogen in a liquid phase in the presence of a catalyst prepared by bearing ruthenium and tin on a carbonaceous carrier previously treated with an acid. SOLUTION: This 1,6-hexanediol is obtained by hydrogenation of a compound selected from adipic acid, oxycaproic acid and caprolactone in a liquid phase pref. under a pressure of 1-25 Mpa at 100-250 deg.C in the presence of a catalyst prepared by beating ruthenium and tin on a carbonaceous carrier. Specifically, the above catalyst is prepared, for example, by the following process: a carbonaceous carrier (pref. active carbon) is put into a 5-60 wt.% aqueous nitric acid solution pref. at 50-90 deg.C for 10 min or longer to conduct an acid treatment, and the resultant carrier is dried until its moisture content comes to pref. <=1 wt.% and then immersed in a solution prepared by dissolving stock compounds (e.g. mineral acid salts) of the metallic components in a solvent (e.g. water) to effect bearing pref. each 1-20 wt.% of ruthenium and tin and, as necessary, platinum at 0.1-5 wt. times based on the ruthenium on the carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing 1,6-hexanediol by directly hydrogenating adipic acid, caprolactone or the like as a raw material without going through an esterification step. 1,6-hexanediol is useful as a raw material for producing polyurethane, polyester plasticizer, unsaturated polyester, and 1,6-hexanediol diacrylate (Japanese Patent Application Laid-Open No. 62-184640).
JP-A-56-78844, JP-A-5-59306
No. 3-227389).

[0002]

2. Description of the Related Art Conventionally, as a method for producing 1,6-hexanediol, for example, as described in JP-B-53-33567, cyclohexane is oxidized to convert adipic acid or oxycaproic acid. And esterify it with alcohols such as methanol, ethanol and 1,6-hexanediol, and react the resulting ester with hydrogen in the presence of a hydrogenation catalyst to produce 1,6-hexanediol. Methods are known. However, this method has a problem that it has to go through an esterification step and that relatively harsh reaction conditions of high temperature and high pressure must be adopted because a copper-based catalyst is used as a hydrogenation catalyst. Was. As a means for solving this problem, the present inventors have proposed a method for producing 1,6-hexanediol by directly hydrogenating adipic acid, caprolactone, or the like using a catalyst containing ruthenium and tin. No. 9-0488889).

[0003]

According to the hydrogenation method using a catalyst containing ruthenium and tin, the reaction can proceed under mild conditions as compared with the conventional method using a hydrogenation catalyst. It is desirable to further improve the reaction activity and selectivity of the catalyst. The present invention addresses this need.

[0004]

According to the present invention, a compound selected from adipic acid, oxycaproic acid and caprolactone is converted into hydrogen in a liquid phase in the presence of a catalyst having ruthenium and tin supported on a carbonaceous carrier. And producing 1,6-hexanediol by using a catalyst prepared by supporting ruthenium and tin on a carbonaceous carrier previously treated with an acid as a catalyst, thereby obtaining 1,6 in high yield.
-Hexanediol can be produced.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material used for producing 1,6-hexanediol in the present invention is adipic acid, oxycaproic acid or caprolactone. These can be used alone or as a mixture. One of such raw materials
An example is a mixture containing a carboxylic acid having 6 carbon atoms obtained by oxidizing cyclohexane. For example, Tokuho 6-99
As described in Japanese Patent No. 345, a reaction product obtained by oxidizing cyclohexane with molecular oxygen in the presence of an oxidation catalyst contains secondary products such as cyclohexanone and cyclohexanol, which are main products. Raw carboxylic acids can be extracted and separated from the reaction solution to obtain a raw material.

The catalyst used in the present invention is prepared by supporting ruthenium and tin as active components on a carbonaceous carrier. When platinum is supported in addition to ruthenium and tin, the catalytic activity is improved. Activated carbon is preferred as the carbonaceous carrier, but graphite or the like can also be used. In the present invention, the carbonaceous carrier is used in the preparation of the catalyst after having been subjected to a pretreatment in which it is previously treated with an acid. The acid treatment is performed by introducing the carbonaceous carrier into a mineral acid, for example, an aqueous solution of nitric acid, hydrochloric acid, sulfuric acid, perchloric acid, hypochlorous acid, etc., and keeping it at room temperature or under heating for several minutes to several hours. Good. In general, the higher the processing temperature, the more the predetermined effect can be obtained in a shorter processing time. Usually, the acid treatment is performed using an aqueous nitric acid solution at a temperature of 30 to 100 ° C, particularly 50 to 90 ° C.

The concentration of the aqueous nitric acid solution is preferably 1 to 75% by weight, particularly preferably 5 to 60% by weight. The time required for the treatment varies depending on the temperature, but when the treatment is carried out at around 90 ° C., it is preferable to carry out the treatment for at least 1 minute, usually 10 minutes or more. The upper limit of the processing time is not limited, and usually about one hour is sufficient. However, if desired, the processing may be performed for a longer time. The reason why a high-performance catalyst can be obtained by treating the carbonaceous carrier with an acid and then using it for catalyst preparation is unknown, but impurities in the carbonaceous carrier that adversely affect the catalytic performance are removed or the carbonaceous carrier is removed. It is presumed that phenomena such as the provision of oxygen-containing functional groups have occurred.

The acid-treated carbonaceous carrier is sufficiently washed with water to remove the adhering acid, and then used in the preparation of the catalyst. Before that, the carbonaceous carrier is preferably dried until the water content becomes 7% by weight or less. The lower the water content is, the better the moisture content is 5% by weight or less, especially
It is preferable to dry until it becomes not more than% by weight. The drying method is optional, but for example, heating to 100 ° C. or higher under a flow of a drying gas such as air or nitrogen, or heating to 50 ° C. or higher under a reduced pressure of 10 mmHg or less. The water content is measured as a weight loss in a range from room temperature to 185 ° C. in TG-DTA measurement. It is not clear why reducing the water content of the carbonaceous carrier to 7% by weight or less has a favorable effect on the catalytic performance. However, drying changes the surface state of the carbonaceous carrier, thereby causing the form of the active ingredient to be supported. It is thought that the change occurs in the distribution and the distribution.

The loading of the active ingredient on the carbonaceous carrier after the above-mentioned acid treatment and drying treatment can be carried out by any method commonly used for preparing a supported catalyst, such as a dipping method, an ion exchange method, and an impregnation method. . Among them, particularly convenient is the immersion method. When the immersion method is used, the raw material compound of the metal component to be supported is dissolved in a solvent, for example, water to form an aqueous solution of the metal compound, and the carbonaceous carrier that has been subjected to the above-described acid treatment and drying treatment is immersed in the solution to form a carrier. A metal component is supported. There is no particular limitation on the order in which the metal components are supported on the carrier,
All metal components may be supported simultaneously, or each component may be supported individually. If desired, each component may be carried in a plurality of times.

As a raw material compound of each metal component used in the preparation of the catalyst, mineral salts such as nitrates, sulfates, hydrochlorides and the like are usually used depending on the preparation method of the catalyst. In addition, organic acid salts such as acetates, hydroxides, oxides, organic metal compounds and complex salts can also be used.
After the metal component is supported on the support, it is dried, and then, if desired, calcined and reduced to obtain a catalyst. Drying is usually 200 ° C
At the following temperature, the pressure may be maintained under reduced pressure or a dry gas such as air may be passed. In the case where the loading of the metal component is performed in a plurality of times, it is preferable to dry each time the loading is performed. The sintering may be performed usually at a temperature of 100 to 600 ° C. while passing air, nitrogen or the like. Further, the reduction may be performed by either liquid phase reduction or gas phase reduction. Usually, gas-phase reduction is carried out at 100 to 600 ° C, preferably 200 to 500 ° C, using hydrogen, methanol or the like as a reducing gas. The supported amount of ruthenium and tin is 0.5 to 50% by weight, preferably 1 to 20% by weight, as a metal, based on the carrier. Platinum is preferably present in an amount of 0.1 to 5 times the weight of ruthenium. In the case of preparing a catalyst containing platinum, first, ruthenium and tin are supported on a carrier and dried,
It is preferable to carry out a reduction treatment and then carry platinum thereon.

In the present invention, hydrogenation of adipic acid or the like is performed in a liquid phase using the above-mentioned catalyst in which ruthenium and tin are supported on a carbonaceous carrier. The reaction can be carried out without a solvent, but is usually carried out in a solvent. Usable solvents include water, alcohols such as methanol and ethanol, ethers such as tetrahydrofuran and dioxane, and hydrocarbons such as hexane and decalin. Preferably, an aqueous solvent such as water or hydrated methanol is used. The hydrogenation reaction is usually performed at a temperature of 50 to 350 ° C, preferably 100 to 250 ° C, and 0.1 to 30 MPa,
It is preferably performed under a pressure of 1 to 25 MPa. The reaction may be carried out either continuously or batchwise, and the reaction type may be any of a liquid phase suspension reaction and a fixed bed flow reaction. 1,6-hexanediol is recovered from the reaction product liquid by an appropriate means such as distillation. Unreacted raw materials and reaction intermediates in the reaction solution, for example, esters of 1,6-hexanediol and raw materials, can be recovered and reused as reaction raw materials.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. In the following, “%” indicates “% by weight” unless otherwise indicated. In the reaction results, the conversion of the raw material was calculated from the measured value of the acid value, and the yield of 1,6-hexanediol was calculated from the analysis value of gas chromatography.

Example 1 Preparation of catalyst; activated carbon (CX-2 manufactured by Mitsubishi Chemical Corporation; particle size: 10)
２０20 mesh) in a 50% aqueous nitric acid solution at 95 ° C., 3
After heating for an hour, the mixture was filtered. After washing with water, 2mmH
The resultant was dried at 80 ° C. for 5 hours under a reduced pressure of 5 g. Activated carbon obtained
Was 0.95%. 5N-HCl aqueous solution
3.6 ml of RuCl_Three・ 3H_Two1.578 g of O,
H _TwoPtCl₆・ 6H_Two0.258 g of O, SnCl_Two
・ 2H_Two0.95 g of O was added and dissolved. This mixed solution
8.55 g of the above activated carbon was added to the mixture. To evaporator
At 60 ° C. under a reduced pressure of 25 mmHg.
Then, it was dried at 150 ° C. for 2 hours under flowing argon. Next
In a hydrogen stream at 450 ° C. for 2 hours, and 6% Ru-1
% Pt-5% Sn / activated carbon catalyst was obtained.

Reaction: In a 200 ml induction-stirring autoclave, 8.5 g of adipic acid and 11.5 of caprolactone were added.
g, water 80 g and the above catalyst 4 g were charged under an argon atmosphere. The temperature was raised to 220 ° C under a hydrogen pressure of 1 MPa,
When the temperature reached 20 ° C., the reaction was started by injecting hydrogen to 10 MPa. After reacting at a constant pressure for 4 hours, the reaction solution was extracted. The conversion rate of the raw materials and the yield of 1,6-hexanediol were determined for the reaction solution. as a result,
The conversion was 95.9%, and the yield of 1,6-hexanediol was 79.6 mol%. A pseudo first-order reaction rate constant at a reaction time of 1 hour was calculated from the amount of absorbed hydrogen to be 0.37 / hr.

Comparative Example 1 A catalyst was prepared in the same manner as in Example 1 except that the treatment of the activated carbon with the aqueous nitric acid solution was not performed. The water content of the catalyst was 0.95%. The reaction was carried out in exactly the same manner as in Example 1 except that this catalyst was used. As a result, the conversion was 77.2%, and the yield of 1,6-hexanediol was 34.0 mol%. The pseudo-first-order rate constant was 0.23 / hr.

Example 2 In the preparation of the catalyst of Example 1, drying under reduced pressure after washing with water was performed for 2 m.
When the temperature was changed to 5 hours at room temperature under reduced pressure of mHg, the water content of the obtained activated carbon was 7.79%. Except that this activated carbon was used, 6% Ru-1 was used in exactly the same manner as in Example 1.
% Pt-5% Sn / activated carbon catalyst was prepared. The reaction was carried out in exactly the same manner as in Example 1 except that this catalyst was used. As a result, the conversion was 87.9%, and the yield of 1,6-hexanediol was 57.6 mol%. The pseudo-first-order reaction rate constant was 0.31 / hr.

Claims (5)

[Claims] 1. A compound selected from adipic acid, oxycaproic acid and caprolactone, which is reacted with hydrogen in a liquid phase in the presence of a catalyst in which ruthenium and tin are supported on a carbonaceous carrier to give 1,6-hexanediol. , Wherein a catalyst prepared by supporting ruthenium and tin on a carbonaceous support previously treated with an acid is used. 2. A water content of 7% by weight after pre-treatment with an acid.
Characterized by using a catalyst prepared by supporting ruthenium and tin on a carbonaceous carrier dried to the following,
The method for producing 1,6-hexanediol according to claim 1. 3. The 1,6-hexanediol according to claim 1, wherein the carbonaceous carrier is obtained by treating activated carbon with nitric acid and then drying it until the water content becomes 7% by weight or less. Manufacturing method. 4. The catalyst according to claim 1, wherein the catalyst comprises platinum on a carbonaceous carrier in addition to ruthenium and tin.
A method for producing 1,6-hexanediol according to any one of claims 1 to 3. 5. The reaction is carried out in an aqueous medium at a temperature of 50-35.
The method according to any one of claims 1 to 4, wherein the reaction is performed under the conditions of 0 ° C and a pressure of 0.1 to 30 MPa.
-A method for producing hexanediol.