JP2000080070A - Production of aliphatic nitrile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aliphatic nitrile having a high quality in a high yield at a low cost by reacting an aliphatic carboxylic acid lower alkyl ester with ammonia in the presence of a highly active compound oxide catalyst slightly soluble in the reaction solution. SOLUTION: This method for producing (D) an aliphatic nitrile comprises reacting (A) an aliphatic carboxylic acid lower alkyl ester with (B) ammonia in the presence of (C) a compound oxide catalyst containing titanium oxide as a main component. The component A is preferably a 6-22C carboxylic acid methyl ester, preferably caproic acid methyl ester, caprylic acid methyl ester, etc. The component C is preferably a compound oxide catalyst comprising titanium dioxide and the oxides of one or more elements selected from the group consisting of niobium, zirconium, tantalum, gallium, and germanium. The oxides except the titanium dioxide in the component C are preferably contained in an amount of 1-25 wt.%. The component has high activity at a temperature of <=300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a high-yield and high-quality aliphatic nitrile.

[0002]

BACKGROUND OF THE INVENTION Aliphatic nitriles are generally produced industrially by the reaction of aliphatic carboxylic acids or their derivatives with ammonia. The reaction mode is roughly classified into a gas phase method and a liquid phase method. In the gas phase reaction, Zr, Ta, Ga, In, Sc, Nb, Hf, Fe, Zn
Alternatively, an aliphatic carboxylic acid or a derivative thereof vaporized in advance is mixed with ammonia using a catalyst having a dehydrating action such as an oxide of Sn (JP-A-4-208260), aluminum oxide, silica gel, thorium oxide, and titanium oxide. Up to 600 ° C
A method of contacting at a temperature of However, the gas phase method has a drawback that it requires a relatively high energy cost as compared with the liquid phase method because the raw material is vaporized.

On the other hand, when the reaction is carried out by a liquid phase method, an aliphatic carboxylic acid or a derivative thereof is heated and dissolved in the presence of a catalyst, and ammonia gas is blown into the aliphatic carboxylic acid or a derivative thereof. ing. The catalyst used in this reaction includes an aliphatic carboxylate of cobalt (U.S. Pat. No. 2,493,637), iron or an iron compound (JP-A No.
58-39653), zinc oxide and the like. Such catalysts show high catalytic activity at reaction temperatures below 300 ° C,
Both are soluble in the reaction solution, and require special separation and recovery operations from the reaction product. As a result, the yield of distillation is reduced and the amount of waste is increased, which is not preferable.

An object of the present invention is to provide a reaction between a lower alkyl ester of an aliphatic carboxylic acid and ammonia, which has a high activity at a reaction temperature of 300 ° C. or less and uses a solid catalyst which is hardly soluble in a reaction solution, and is incorporated into a product. It is an object of the present invention to provide a method for inexpensively producing a high-yield and high-quality aliphatic nitrile without dissolution of the catalyst.

[0005]

Means for Solving the Problems The present inventors have found that a composite oxide catalyst containing titanium oxide as a main component has a high catalytic activity even at a reaction temperature of 300 ° C. or less and is a solid which is hardly soluble in a reaction solution. The inventors have found that the present invention has been completed. That is, the present invention is a method for producing an aliphatic nitrile in which a lower alkyl ester of an aliphatic carboxylic acid and ammonia are reacted in the presence of a composite oxide catalyst containing titanium oxide as a main component.

In the present invention, the "composite oxide" is an oxide in which two or more metals coexist inside or on the surface.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The lower alkyl carboxylic acid ester used in the present invention is a straight-chain or branched C6-C6 alkyl ester.
22 saturated or unsaturated aliphatic monocarboxylic acid lower alkyl esters or dicarboxylic acid di-lower alkyl esters. Here, the lower alkyl is an alkyl having 1 to 5 carbon atoms, and specific examples include methyl, ethyl, propyl, and isopropyl, with methyl being particularly preferred.
These aliphatic carboxylic acid lower alkyl esters can be used alone or in combination of two or more.

Specific examples of these lower alkyl esters of aliphatic carboxylic acids include methyl caproate, methyl caprylate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl stearate, methyl arachiate, Methyl behenate, methyl dimethyl octanoate, methyl butyl heptyl nonanoate, methyl hexenoate, methyl octenoate, methyl decenoate, methyl dodecenoate, methyl tetradecenoate, methyl hexadecenoate, methyl octadecenoate, methyl eicosenate, methyl docosenate Dimethyl adipate, dimethyl azelate, dimethyl sebacate, dimethyl decamethylene dicarboxylate, dimethyl hexadecamethylene dicarboxylate, dimethyl octadecamethylene dicarboxylate, and the like.

The catalyst used in the method of the present invention is a composite oxide catalyst containing titanium oxide as a main component, and the titanium oxide is selected from the group consisting of silicon, niobium, zirconium, tantalum, gallium and germanium. A composite oxide catalyst in which oxides of at least two or more elements are composited is preferred, and a composite oxide catalyst in which silica, niobium oxide or zirconium oxide is composited with titanium oxide is particularly preferred. The content of the oxide other than titanium oxide in the composite oxide catalyst of the present invention is preferably from 1 to 25% by weight, more preferably from 1 to 15% by weight, from the viewpoint of obtaining high activity.

The method for preparing the catalyst used in the method of the present invention is not particularly limited, but a method in which titanium oxide and another oxide form a complex, for example, a deposition method, a coprecipitation method, an alkoxide method, an impregnation method The method is used. The firing temperature of the catalyst is not particularly limited, but it is preferable to perform the firing at 500 ° C. or lower. When calcined at a temperature exceeding 500 ° C., the surface area of the catalyst is reduced, and the activity is reduced.

In the process of the present invention, the reaction can be carried out batchwise, semi-batchwise, continuously with a suspension bed or in a fixed bed flow system. The reaction temperature is preferably in the range of 180 to 350 ° C, more preferably 250 to 300 ° C. The pressure at the time of the reaction is usually in a slightly pressurized state, but may be normal pressure. The amount of the composite oxide catalyst to be used is preferably 0.1 to 5 times with respect to the lower alkyl ester of the aliphatic carboxylic acid, when the batch is performed by a suspension bed, the batch is half batch, and when the process is performed in a continuous system.
It is 10% by weight, more preferably 0.3 to 3% by weight. When the reaction is carried out in a fixed bed flow system, the average residence time of the reaction mixture in the catalyst layer is preferably from 1 second to 10 minutes.

[0012]

According to the method of the present invention, a highly active complex oxide catalyst which is hardly soluble in the reaction solution is used, so that the catalyst is not dissolved in the product as compared with the conventional method, and the method is excellent. High quality aliphatic nitriles can be produced in high yields, which is of great industrial significance.

[0013]

EXAMPLES Examples 1 to 4 and Comparative Examples 1 to 3 Titanium tetraisopropoxide, tetraethyl orthosilicate and isopropanol as a solvent were charged into a flask such that titanium oxide and silica had the weight ratios shown in Table 1. After the temperature was raised to 80 ° C., 6 mole times of ion-exchanged water was added dropwise to the metal alkoxide with stirring. After dropping,
Stirring was continued at that temperature for 5 hours. The catalyst precursor removed by filtration was washed with ion-exchanged water, filtered, dried at 110 ° C., and calcined at 300 ° C. for 3 hours to obtain a composite oxide catalyst used in the present invention.

Next, 5.0 g of the above composite oxide catalyst and 500 g of methyl stearate were mixed in a four-necked flask equipped with a stirrer, a gas inlet tube, a thermometer and a dehydrator.
A reaction was carried out by introducing 00 ml / min of ammonia gas over 6 hours. The obtained reaction product was subjected to composition analysis by gas chromatography [gas chromatography apparatus: HEWLETT PACKARD Series 5890, column: DB-5 manufactured by J & W (inner diameter × length: 0.53 mm × 15 m)] to measure the amount of nitrile produced. . For comparison, a titanium oxide prepared by repeating the same operation as described above, a single catalyst of silica, or a 95: 5 titanium oxide: silica weight ratio catalyst obtained by physically mixing them was the same. The reaction was performed under the conditions. Table 1 shows the results. In each case where the catalyst of the present invention was used, the progress of the reaction was rapid, and as a result of elemental analysis by ICP emission analysis, titanium and silicon in the reaction product were below the detection limit.

Examples 5-9 Except for using zirconium tetrapropoxide, niobium pentaethoxide, tantalum pentaethoxide, gallium triisopropoxide, or germanium tetraethoxide instead of tetraethyl orthosilicate in the preparation of the catalyst. The same operation as in Example 2 was repeated to obtain a composite oxide catalyst. Using the composite oxide catalyst, a reaction was carried out under the same conditions as in Example 1, and the reaction product was analyzed in the same manner as in Example 1. Table 1 shows the results. The metal element derived from the catalyst in the reaction product was below the detection limit.

Example 10 The weight ratio of titanium oxide to silica prepared in Example 2 was 95:
Using the composite oxide catalyst of No. 5, the reaction was carried out under the same conditions as in Example 1 except that ammonia gas was introduced at a reaction temperature of 300 ° C. for 3 hours. The reaction product was analyzed as in Example 1. Table 1 shows the results. Titanium and silicon in the reaction product were below the detection limit.

[0017]

[Table 1]

Example 11 The weight ratio of titanium oxide to silica prepared in Example 2 was 95:
The reaction was carried out under the same conditions as in Example 1 except that methyl laurate was used instead of methyl stearate using the composite oxide catalyst of No. 5. As a result of analyzing the reaction product in the same manner as in Example 1, the amount of lauronitrile produced was 86.3.
(GC%), and titanium and silicon in the reaction product were below the detection limit.

Example 12 The same operation as in Example 2 was repeated to prepare a powder before firing so that the weight ratio of titanium oxide to silica was 95: 5. The powder was extruded and calcined at 300 ° C. for 3 hours to obtain a molded catalyst. 1.0 g of the catalyst is 10 mm in inner diameter and 500 in length
The central part of a stainless steel cylindrical reaction tube of mm was filled. Ammonia gas 927 mL / hr, methyl stearate 1.2 g / h
It was supplied from the top of the reaction tube at a rate of r, and reacted at 250 ° C. under normal pressure. The obtained reaction product was subjected to gas-liquid separation and dehydration treatment, and then the amount of stearonitrile produced was measured by gas chromatography in the same manner as in Example 1. As a result, 98.9 (GC
%)Met. In addition, titanium and silicon in the reaction product were below the detection limit.

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Claims (3)

[Claims] 1. A method for producing an aliphatic nitrile, comprising reacting an aliphatic carboxylic acid lower alkyl ester with ammonia in the presence of a composite oxide catalyst containing titanium oxide as a main component. 2. The aliphatic nitrile according to claim 1, wherein the oxide combined with the titanium oxide is an oxide of at least one element selected from the group consisting of silicon, niobium, zirconium, tantalum, gallium, and germanium. Manufacturing method. 3. The process for producing an aliphatic nitrile according to claim 1, wherein the aliphatic carboxylic acid lower alkyl ester is a methyl ester of a carboxylic acid having 6 to 22 carbon atoms.