JPS5950664B2 - Production method of 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, an unsaturated nitrile is reacted with water in the presence of a composite oxide catalyst that is a combination of an oxide of at least one metal selected from the group consisting of titanium and zirconium and zinc oxide. The present invention relates to a method for producing a saturated amide. 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 (Mn00). Manganese dioxide has relatively high activity and selectivity, but has the disadvantage of short lifetime. Also, JP-A-48-23716
No. 48-39426 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 in order to increase the reaction rate of nitrile, high temperatures of 100°C or higher are required.
Alternatively, since a reaction time of several hours or more is required, side reactions are induced and the yield of amide is reduced. The inventors of the present invention solved the above-mentioned problems and provided an industrially advantageous manufacturing method.As a result of intensive research,
We have discovered that a composite oxide that combines titanium or zirconium oxide with a specific metal oxide is a catalyst that is easy to store and handle, has excellent activity and selectivity, and has a long life.

In other words, it has been shown that a composite oxide, which is a combination of an oxide of at least one metal selected from the group consisting of titanium and zirconium, and zinc oxide has high activity and selectivity in the hydration reaction of unsaturated J-nitrile. Heading, we arrived at the present invention. The "complex oxide" as used in the present invention includes binary oxides, ternary oxides, quaternary oxides, higher multi-component oxides, solid solutions, and non-stoichiometric oxides.

This also includes physical mixtures of single oxides, such as titanium dioxide and zinc oxide. Further, the term "oxide" is defined to include those in an at least partially hydrated state. The composite oxide catalyst used in the present invention can be prepared in any convenient manner that can be adopted for preparing this type of catalyst. As a preparation method, a precipitation method can be preferably employed. That is, a solution of two or more salts of the above-mentioned specific metals, such as sulfates, nitrates, oxyacids, halogenates, organic acid salts, etc., especially an aqueous solution, includes aqueous ammonia, alkali hydroxide, alkali carbonate, etc. as an alkaline substance. A frequently used method is to add a solution, particularly an aqueous solution, of an organic amine or the like to form a precipitate of a corresponding metal hydroxide or hydrated oxide, and to sinter the resulting precipitate at an appropriate temperature. It is also possible to combine each metal in stages. For example, it is possible to first prepare an oxide and then add an alkali to an aqueous solution of a salt of another metal in its presence to precipitate a hydroxide or hydrous oxide. As a method that does not involve precipitation of hydroxides or hydrous oxides, the above-mentioned salts alone or in a mechanical mixture of two or more salts are heated to a temperature high enough to form oxides and thermally decomposed. Methods for obtaining the corresponding oxides are also employed. A mechanochemical method may also be used, which consists of mixing the various oxides already obtained and sufficiently pulverizing the mixture using a ball mill or the like. In this case, it is more effective to perform ball milling in a wet state by adding water. The composite oxide catalyst thus obtained is preferably calcined at a high temperature to stabilize the catalyst structure.

The firing temperature in this case may be appropriately selected depending on the type of metal used or the combination thereof. The firing temperature of the catalyst is particularly preferably in the range of 400°C to 600°C.

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

Therefore, suitable supports such as silica, alumina, silica/alumina, diatomaceous earth, alundum, corundum, activated carbon, naturally occurring silicates, etc. can be supported on 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 relative to the nitrile be present in the reaction system.

This water may be not only free water but also hydration water when the composite 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 alcohols, ketones, amides, sulfoxides, and specific examples include methanol, ethanol, isopropanol, acetone, dimethylformamide, dimethylsulfoxide, formamide, acetamide, and the like. Typical examples of unsaturated nitriles applicable to the present invention include acrylonitrile,
Methacrylonitrile, crotonitrile, β-phenylacrylonitrile, 2-cyano-2-butene, 1-
Examples include cyano-1-octene, 10-undecenonitrile, maleate nitrile, and fumarate nitrile.

The catalyst of the present invention has high amidation reaction activity and selectivity, and has a long life.

In addition, it is easy to store and handle, and even if dissolved oxygen is contained in the reaction feed, it does not adversely affect the activity or selectivity of the catalyst. The present invention provides an excellent method for producing unsaturated amides. Next, the present invention will be explained using Examples, but these Examples do not limit the present invention.

Example 1 Titanium tetrachloride TiCl.

38Og and zinc nitrate (Zn(NO,), 6H,0)
15 g was dissolved in 31 water, and 28% ammonia water was added thereto with vigorous stirring until the pH reached 7.

The formed precipitate was suction filtered and washed twice with 1 ml of water.

The obtained precipitate was dried at 110°C and calcined at 500°C for 6 hours. 5 g of the catalyst prepared by the above method was crushed and placed in a 100 ml flask equipped with a Libitz condenser together with 23 g of a 6.8% (by weight) aqueous solution of acrylonitrile, and the reaction temperature was maintained at about 70°C with stirring under atmospheric pressure. The mixture was refluxed for 5 hours.

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 0.35 g of acrylamide (yield: 16.7%).

No other by-products were detected.

Example 2 Zirconium oxychloride (ZrOCl2.8H20)6
4.4g and zinc nitrate (Zn(NO3)2 ・6H20)
1.9 g was dissolved in 500 ml of water, and 28% ammonia water was added thereto with vigorous stirring until the pH reached 7.

The generated precipitate was suction filtered and washed twice with 1000 cc of water.

The obtained precipitate was dried at 110°C, calcined at 500°C for 6 hours, and then ground. The hydration reaction of atarylonitrile was carried out in the same manner as in Example 1, except that 5 g of the catalyst prepared in the above method was used.

As a result of gas chromatography analysis of the reaction solution, diacrylamide was found to be 0.
．． It was confirmed that 12g (yield 5.7%) was contained.
No other by-products were detected.

Example 3 The catalyst prepared in Example 1 was ground and sieved to give 10
~32 meshes of catalyst particles were obtained.

125 g of the catalyst prepared by the above method was filled into a jacketed glass reaction tube (inner diameter 1.8 cm). 78 reaction tubes
C., and a 5.7% (by weight) acrylonitrile aqueous solution was supplied to the catalyst layer at a flow rate of 40 ml/Hr using a plunger pump. When the composition of the effluent was analyzed by gas chromatography, the concentration of acrylamide was 4.7% (by weight) 5 hours after the start of the reaction. The yield of acrylamide is 61% based on the acrylonitrile fed.
．． It becomes 5 (mol)%. Trace amounts of ethylene cyanohydrin and acrylic acid were detected as byproducts. When the reaction was further continued under the above reaction conditions, there was no change in the yield of acrylamide even after 100 hours, indicating that the catalyst activity was stable and the life was long.

Claims (1)

[Claims] 1. Unsaturated nitrile and water are reacted in the presence of a composite oxide catalyst that is a combination of at least one metal oxide selected from the group consisting of titanium and zirconium and zinc oxide. A method for producing amides.