JPS5918384B2 - Method for producing unsaturated amide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for hydrating nitriles to produce the corresponding amides.

More specifically, the present invention relates to a method for producing acrylamide or methacrylamide by reacting acrylonitrile or methacrylonitrile with water using a titanium or zirconium oxide as a catalyst.

A catalytic hydration reaction between a nitrile and water using metallic copper as a catalyst is known.

The disadvantage of metallic copper catalysts is their short lifetime, and a gradual decline in hydration activity is inevitable. Furthermore, the activity is very unstable, and a great deal of effort is required to store and handle the catalyst. On the other hand, various oxides have been proposed as catalysts for the catalytic hydration reaction of nitriles.

For example, US Pat. No. 3,366,639 proposes the use of manganese dioxide (MnO2). Man dioxide: Gan has relatively high activity and selectivity but has the disadvantage of short lifetime. Also, JP-A-48-237
No. 16 proposes a composite oxide catalyst containing iron and zinc, and JP-A-48-39426 proposes a composite oxide catalyst containing nickel and chromium. Although these known composite oxides are easy to store and handle, they have low activity and require high temperature or long reaction conditions to increase the reaction rate of nitrile, causing side reactions and reducing the yield of amide. It has the disadvantage of lowering 5 The present inventors have carried out intensive research in order to solve the above problems and provide an industrially advantageous manufacturing method, and as a result, it has been found that titanium or zirconium oxides have excellent activity and selectivity. ,
The present invention was achieved by discovering that the catalyst has a long life and is easy to store and handle.

The term "oxide" as used in the present invention is defined to include those in an at least partially hydrated state.

The oxide catalyst used in the present invention can be prepared in any convenient manner that can be employed in preparing catalysts of this type.

A precipitation method is preferably employed as a preparation method. That is,
Aqueous ammonia, alkali hydroxide, aqueous ammonia, alkali hydroxide, etc., as an alkaline substance j0 in a solution, especially an aqueous solution, of salts of the metals, such as sulfates, nitrates, oxyacids, halogenates, organic acid salts, etc.
A frequently used method is to add a solution, particularly an aqueous solution, of an alkali carbonate, an organic amine, etc., to form a precipitate of the corresponding metal hydroxide or hydrous oxide, and to sinter the resulting precipitate at an appropriate temperature. A method that does not involve precipitation of hydroxides or hydrous oxides (5) is to heat a single salt or a mechanical mixture of two or more of the above salts to a high enough temperature to form oxides. A method of obtaining the corresponding oxide by decomposition is also adopted.

The oxide catalyst thus obtained is preferably calcined at a high temperature to stabilize the catalyst structure. The firing temperature in that case may be appropriately selected depending on the type of metal used. Generally, it is preferable to heat at a temperature of 110° C. or higher for 30 minutes or longer.

The heating atmosphere should generally avoid reducing properties. Such an oxide catalyst can be used by being supported on a carrier, as is commonly used for catalysts of this type.

Thus, suitable supports such as silica, alumina, silica-alumina, diatomaceous earth, alundum, corundum, activated carbon, naturally occurring silicates, etc. can be combined with the metal compound at any stage of the catalyst preparation process described above. . The hydration reaction of nitrile according to the method of the present invention is usually carried out at a temperature of room temperature to 300°C using the above-mentioned catalyst.
From the viewpoint of increasing the reaction rate and suppressing side reactions, it is particularly preferable to carry out the reaction at a temperature of 40°C to 150°C.

In the hydration reaction of nitrile, it is necessary that at least a stoichiometric amount of water to the nitrile be present in the reaction system.

In addition to free water, this water may also be water of hydration or the like, in which case the oxide catalyst is at least partially hydrated. Although the reaction can be carried out in either a gas phase or a liquid phase, it is usually carried out in a liquid phase.

It is also possible to carry out the reaction under pressure. In order to inhibit polymerization during the reaction, suitable polymerization inhibitors such as hydroquinone, phenothiazine, p-Tert-
Butylcatechol etc. can be added as necessary.

It is also possible to suppress polymerization by dissolving oxygen in the reaction feed solution. In carrying out the method of the present invention, a stable solvent that can withstand use at the reaction temperature can also be used together with water.

Solvents used in the present invention include methanol, ethanol, isopropanol, acetone, dimethylformamide, dimethyl sulfoxide, formamide, acetamide, and the like. Next, the present invention will be explained with examples.
These examples are not intended to limit the invention. Example 1 154 t of a 20% aqueous solution of titanium trichloride (TiCl3) was dissolved in 500 ml of water, and 1.
240 t of 0% strength soda solution were added gradually.

The generated precipitate was suction filtered and washed twice with 1000 cc of water. The obtained precipitate was dried at 110°C, calcined at 450°C for 2 hours, and then ground. Catalyst 5f7 prepared by the above method was added to a 6.8% (by weight) aqueous solution of acrylonitrile in 2
The mixture was placed in a 100 ml flask equipped with a Liebig condenser together with 3y, and refluxed at a reaction temperature of about 70° C. for 5 hours with stirring under atmospheric pressure.

After the reaction, the reaction mixture was filtered to remove the catalyst and analyzed by gas chromatography, and it was confirmed that the filtrate contained 0.28% of acrylamide (yield: 19.7%). Trace amounts of ethylene cyanohydrin and acrylic acid were also detected as byproducts. Example 2 Zirconium oxychloride (ZrOCl2.8H20)0
．． 2 mol was dissolved in 500 ml of water and 16.0 t of 10% strength soda solution was gradually added thereto with vigorous stirring.

The generated precipitate was suction filtered and washed twice with 1000 cc of water. The obtained precipitate was dried at 110°C, calcined at 450°C for 2 hours, and then ground. The hydration reaction of acrylonitrile was carried out in the same manner as in Example 1, except that 5t of the catalyst prepared by the above method was used.

As a result of gas chromatography analysis of the reaction solution, acrylamide was found to be 0.
It was confirmed that 30f7 (yield 19%) was contained. No other by-products were detected. Example 8 20% aqueous solution of titanium trichloride (TiCl3) 1540V
(2 moles as TiCl3) is dissolved in 31 g of water and added to this with vigorous stirring 240 g of 10% strength soda solution.
7fL1 was added gradually.

The formed precipitate was suction filtered and washed twice with 41 portions of water.
The obtained precipitate was dried at 110°C and calcined at 500°C for 2 hours. This was pressure-molded, pulverized, and sieved to obtain catalyst particles of 10 to 32 mesh. Catalyst 125r prepared by the above method was packed into a jacketed glass reaction tube (inner diameter 1.8 CTrL).

The reaction tube was kept at 78°C, and a 5.7% (by weight) acrylonitrile aqueous solution was poured into 40ml/ml using a plunger pump.
It was supplied to the catalyst layer at a flow rate of Hr. When the composition of the effluent was analyzed by gas chromatography, it was found that after the start of the reaction,
After 3 hours, the concentration of acrylamide was 4.2% (by weight). The yield of acrylamide is 55.0 (mol)% based on the supplied acrylonitrile. Trace amounts of ethylene cyanohydrin and acrylic acid were detected as byproducts.
When the reaction was further continued under the above reaction conditions, the acrylamide yield after 100 hours was 50.2 (mol)%.

Claims (1)

[Claims] 1. A method for producing an unsaturated amide, which comprises reacting acrylonitrile or methacrylonitrile with water using a titanium or zirconium oxide as a catalyst.