JPS6026045B2 - Method for producing hydrocyanic acid using acetonitrile as raw material - Google Patents

Description

[Detailed description of the invention] The present invention relates to an industrial method for producing hydrocyanic acid.

More specifically, the present invention relates to a method for efficiently producing hydrocyanic acid by ammoxidizing acetonitrile in the presence of a catalyst. It is known that hydrocyanic acid and acetonitrile are created when acrylonitrile is produced by ammoxidizing propylene. Among these created substances, hydrocyanic acid is widely used as an industrial raw material, whereas acetonitrile has low industrial utility value, and a considerable amount of it is currently discarded by incineration, etc. On the other hand, a method for producing hydrocyanic acid using acetonitrile as a raw material is also known.

Therefore, if it were possible to efficiently obtain hydrocyanic acid from the by-product acetonitrile, it would be possible to convert acetonitrile with low utility value into hydrocyanic acid with high utility value, which would be of great industrial significance. Until now, methods for producing hydrocyanic acid from acetonitrile include a method in which a mixture of acetonitrile and air is brought into contact with a composite oxide catalyst of aluminum, phosphorus, copper, molybdenum, bismuth, etc. in the presence of water vapor (West German Patent No. 1,1408
61) and a method in which acetonitrile and hydrogen are reacted in a gas phase at a temperature of about 700°C under non-catalytic conditions (British Patent No. 1,051,404).

However, according to these methods, only the shea/group part of acetonitrile is utilized, and the other parts are discarded unused, so although they are still satisfactory in terms of efficiency, do not have. In addition, a mixture of acetonitrile, ammonia, and air or nitrogen is heated at a temperature of 700 to 800℃.
00qo with an alumina catalyst (West German Patent No. 1,203 241), in the presence of a platinum catalyst or a platinum-alumina catalyst, at a temperature of 700 to 9000
A method for reacting acetonitrile, ammonia, and oxygen in
Page (1960 King)], temperature 11 in the presence of a platinum-based catalyst.
A method for producing hydrocyanic acid and hydrogen by reacting acedonitrile and ammonia at 00 to 1400°C (Japanese Patent Publication No. 481-1)
4560) and the like are also known.

However, these methods require high temperatures for the reaction, require the use of special equipment, and consume a large amount of thermal energy, so they are not industrially advantageous. Furthermore, in the presence of various catalysts, 400 to 60
A method for producing hydrocyanic acid by reacting acetonitrile, ammonia, and oxygen at a relatively low temperature of 0° C. is also known.

For example, a method using a catalyst having a composition of iron, bismuth, molybdenum, and phosphorus (Japanese Patent Publication No. 1656/1983);
Method using a catalyst consisting of iron and arsenic
51), and a method using a catalyst containing antimony and iron as main components (Mochiko Sho 49-33039). However, all of these methods have the drawback of low yields, and cannot be said to be satisfactory as industrial methods. Therefore, there has been a great need in the art for a method for efficiently obtaining hydrocyanic acid from acetonitrile at relatively low temperatures.

The inventors of the present invention conducted extensive research in order to meet these demands, and first determined that molybdenum and iron were mixed at a ratio of 1:0.5 to 1.5.
They found that a catalyst with a composition containing an atomic ratio of The present invention was made based on the findings.

That is, in the present invention, in producing hydrocyanic acid by a gas phase reaction of acetonitrile, ammonia, and oxygen in the presence of a catalyst, the catalyst is of the general formula M○, 2FeXAy (where A is selected from among alkali metals). At least one selected element, x is the number of iron atoms when the number of molybdenum atoms is 12, and has a numerical value in the range of 6 to 18, and y
is the number of atoms of A when the number of atoms of molybdenum is 12, and has a numerical value in the range of 0.01 to 3. The present invention provides a method.

In the catalyst of the present invention, if the number of iron atoms is less than 6 when the number of molybdenum atoms is 12, the activity will be low, and if it exceeds 18, the hydrocyanic acid selectivity will be low, making it impractical.

Therefore, x in the general formula described above must be selected in the range of 6 to 18, preferably in the range of 8 to 15. In the catalyst of the present invention, it is necessary to add 0.01 to 3 atoms of alkali metal when the number of molybdenum atoms is 12.

If this alkali metal is not added, hydrocyanic acid undergoes secondary oxidation, resulting in a decrease in hydrocyanic acid selectivity. However, if the amount added exceeds the above-mentioned range, the activity will be lowered, which is not preferable. The preferred range is 0.1 to 12 molybdenum atoms.
It has two atoms. The catalyst used in the present invention has excellent activity even when used alone, but it can also be used supported on a carrier such as silica gel, quartz, alumina, or the like.

The method of preparing the catalyst used in the present invention is not complicated;
It can be prepared by common methods. That is, by dissolving or suspending molybdenum or a compound of molybdenum, iron or a compound of iron, and an alkali metal or its compound in water or an acidic solution, adding a carrier if necessary, dry insertion, firing, and molding. Prepare the catalyst. Calcination of the catalyst gives catalytic activity and selectivity, so 400
~750oo, preferably 500~70pi○. The reaction can be carried out in either a fixed bed or a fluidized bed. The reaction is 300-60 qo, preferably 350-500 qo
A mixed gas consisting of acetonitrile, ammonia, oxygen or an oxygen-containing gas and, if necessary, water vapor or an inert gas is added to the sand for a contact time of 0.2 to 2, preferably 0.
．． This is done by contacting the catalyst for a period of 5 to 5 seconds.

The molar ratio of the mixed gas is 0 for ammonia/acetonitrile.
．． 9-2 preferably <1.0-1. Oxygen/acetonitrile should be in the range of 1 to 2, preferably 1 to 10.

As the reaction pressure, atmospheric pressure to several atmospheres can be used.

Acetonitrile does not need to be pure, and may be in the form of an aqueous solution or one containing some impurities.

Examples will be described below, and the definitions of the acetonitrile reaction rate, hydrocyanic acid selectivity, and hydrocyanic acid yield in the Examples and Comparative Examples are as follows.

Acetonitrile reaction rate (%) - Hydrocyanic acid selectivity (%) - Carbon weight of generated hydrocyanic acid - Carbon weight of reacted acetonitrile x 100 Hydrocyanic acid yield (%) Carbon weight of generated hydrocyanic acid - Carbon weight Carbon weight of acetonitrile x 100Example 13Silica sol containing t% of Si02 Ammonium simolybdate ((N ratio) 6・Mo7Q4・
Add a solution of 19.7% dissolved in water to 33%, and then add ferric nitrate (Fe(N03)3・Group 20)4
5.0 and potassium nitrate (KN03) 0.14 and 50
The solution was dissolved in water that had been heated to a temperature of 50 °C for 50 minutes, and the solution was then allowed to cool to room temperature.

This catalyst raw material slurry was evaporated and solidified, and fired for 2 hours in an electric furnace set at 60 mm.

In this way, the atomic ratio of Mo/Fe/K is 12/12.
/0.15 catalyst was obtained.

This catalyst was filled into a glass reaction tube on the inner diameter 8 side,
After keeping the reaction temperature at 420 qo and passing ammonia gas for 10 minutes, a mixed gas consisting of acetonitrile, ammonia, oxygen, and water vapor in a molar ratio of 1:1.1:1.6:1.0 was diluted with helium to form acetonitrile. A mixed gas having a concentration of 3% by volume was passed through for a contact time of 2 seconds.

The reaction pressure was atmospheric pressure. The results in the above case were as follows. Acetonitrile reaction rate 95.0% Hydrocyanic acid selectivity 68.0% Hydrocyanic acid yield Mo. 6% Comparative Example 1 According to the method described in Example 1, a catalyst obtained by removing only potassium from the catalyst of Example 1 was prepared, and the reaction was carried out using the same reactor as Example 1 and under the same conditions as Example 1. I made him do it.

The results were as follows. Acetonitrile reaction rate 99.0% Hydrocyanic acid selectivity 46.0% Hydrocyanic acid yield 455% Example 2 A catalyst having the composition shown in Table 1 was prepared according to the method described in Example 1, and the same reactor as Example 1 was used. The reaction was carried out using the same gas mixture.

The results are shown in the Example column of Table 2.

Comparative Example 2 The catalyst shown in the Comparative Example column of Table 1 was prepared according to the method described in Example 1, and the reaction was carried out using the same reactor as in Example 1 and passing the same mixed gas.

The results are shown in the Comparative Example column of Table 2. Table 1 Table 2

Claims (1)

[Claims] 1. In producing hydrocyanic acid by a gas phase reaction of acetonitrile, ammonia, and oxygen in the presence of a catalyst,
As a catalyst, the general formula is MO_1_2Fe_xAy (A in the formula is at least one element selected from alkali metals, x is the number of iron atoms when the number of molybdenum atoms is 12, and is in the range of 6 to 18. has a numerical value of y
is the number of atoms of A when the number of atoms of molybdenum is 12, and has a numerical value in the range of 0.01 to 3. Method.