JPS5817189B2 - 3- Cyanopyridine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to 2-methyl-5-ethylpyridine (hereinafter MEP).
This invention relates to a method for producing 3-cyanopyridine (hereinafter abbreviated as CP) by an ammoxidation reaction of 3-cyanopyridine (hereinafter abbreviated as CP).

CP is a member of the vitamin B group and is a useful substance in the fields of medicines such as prevention and treatment of pellagra, feed additives, food additives, etc. Nicotinic acid amide, a raw material for the synthesis of nicotinic acid, and other industrial uses. It is a useful substance, and it has been known that it can be produced by the ammoxidation reaction of β-picoline, lutidine or MEP.

For example, in a method using β-picoline as a raw material, vanadium-molybten-phosphorus, vanadium-chromium, molybdenum-bismuth-phosphorus, nitrogen-silver or iron, vanadium-molybten-phosphorus,
The use of various catalysts containing silver or iron, vanadium-tin, molten vanadium-molybdenum, etc. as active ingredients has been proposed, and catalysts containing vanadium-tin and vanadium-titanium as active ingredients are particularly effective. has been done.

Although these methods can obtain fairly good results in terms of yield of CP, β-picoline used as a raw material is relatively expensive, and it is more advantageous to use MEP as a raw material for industrial production methods. be.

In this latter method, a large amount of 2,5-dicyanopyridine (hereinafter abbreviated as DCP) is produced in addition to CP, and in a normal ammoxidation reaction, DCP is rather the main product.

When producing nicotinic acid and nicotinic acid amide from these products, a decarboxylation step of isocincomeronic acid from DCP is required, which complicates the process, so industrially only CP can be selectively produced. is desired.

Conventionally, many catalysts have been proposed as catalysts for the ammoxidation reaction of MEP, such as vanadium or vanadium-based catalysts in which vanadium is combined with various metal oxides. It is said that the catalyst is particularly effective, but according to the knowledge of the present inventors, the selectivity of CP in the ammoxidation reaction of MEP greatly depends on the type of catalyst to be used and the reaction conditions. For example, even if the catalyst is conventionally considered to be effective, catalysts that combine vanadium and antimony, iron, tin, titanium, molybdenum, etc., are mainly DCP or 5-
If ethyl-2-cyanopyridine is produced or the reaction system becomes unstable, or if the preparation method and reaction conditions are incorrect even if the catalyst components are appropriately selected, problems may occur. It was recognized that the objectives of the period could not be achieved.

The present invention was achieved as a result of various studies regarding a method that can be industrially advantageously implemented by improving the selectivity of CP in the ammoxidation reaction of MEP. It is characterized by its preparation method and reaction conditions.

That is, in the present invention, in the presence of a catalyst obtained by supporting vanadium-zircon as an active ingredient on an inert carrier with a surface area of 50 m''/g or less and calcining it at a temperature of 600°C or less, 20 to 80% of vanadium is added to the reaction system. While introducing water in the capacity section, M
It is characterized by reacting EP with ammonia and oxygen at a temperature of 300 to 500°C, thereby forming DCP and 5
- Suppresses the formation of ethyl-2-cyanopyridine, etc., and CP
The object of the present invention is to provide an industrially advantageous method capable of producing with high selectivity.

To explain the present invention in more detail, the catalyst to be used has vanadium-zircon as an active component, and the carrier is a highly active carrier with a large surface area such as activated carbon, silica, or aluminosilicate, or the catalyst is a carrier with a catalytic active component. When used as is in the form of oxide without using M
Because ΔH of the ammoxidation reaction of EP is large, it becomes difficult to control the reaction and there is a risk of runaway. Therefore, in the present invention, the surface area is 52 m2/g or less, preferably 10 m
/g or less, such as α-alumina, silicon carbide, etc., is used.

The amount of the active ingredient supported is 1 to 15% by weight as vanadium pentoxide (V2O5), and the atomic ratio of bare zircon to vanadium is preferably 1:1, usually in the range of 0.1 to 10.

The catalyst is a catalyst in which the above-mentioned active components are usually in the form of oxides (v205.V
2O5-Zrn0m or Vp-Zrq-Or) is uniformly dispersed and supported on the carrier, but as a preparation method, for example, a vanadium compound such as vanadium pentoxide or vanadyl oxalate, a salt or oxyacid of zircon, etc. It can be obtained by dissolving an aqueous solution of water, a mineral acid or an organic acid in a suitable solvent, adding a carrier thereto, mixing thoroughly, and then evaporating to dryness. Any conventional method may be applied.

Calcination of the catalyst is an essential requirement in the present invention, and the active ingredient is uniformly supported and is heated in advance at a temperature of 600°C or lower, preferably 350 to 550°C, with air circulation for usually about 3 to 10 hours. Requires heat treatment.

Note that if the firing temperature is too high, the desired activity will not be realized and DCP will mainly be produced, so care must be taken.

In addition to the use of a specific catalyst, the reaction conditions are also an important requirement in the present invention, and 20 to 80 volumes of water are required to be introduced into the reaction system.

DC if no or too little water is added.
It is observed that a large amount of P is produced, and as the proportion of water in the reaction gas increases, the amount of DCP produced decreases, and the amount of CP produced tends to increase.

However, if too large a quantity is used, the effect decreases, perhaps because it affects the concentration of other reaction components, especially ammonia.
The yield of P decreases.

Regarding the ammonia concentration, the higher the ammonia concentration, the better the CP yield, but it is usually appropriate to carry out the ammonia concentration in the range of 1 to 30 volumes.

Further, although the MEP concentration is usually quite low, in the present invention it is in the range of 0.1 to 5% by volume.

The remainder is air or nitrogen. The concentration of oxygen is CP
It has a great effect on the yield of MEP, and it is desirable to use it in a molar ratio of 20 or less, preferably in a range of 7 to 15 molar ratio to MEP.

The reaction temperature is interrelated with the space velocity (SV), MEP concentration, etc., and the temperature at which the highest yield is obtained varies slightly depending on the type of catalyst to be used, but the optimum temperature in the present invention is 300 to 500'. C range, preferably 320-470
It is ℃.

In this case, S■ is suitably about 500 to 10,000.

The present invention will be explained in more detail below with reference to Examples, but in order to facilitate understanding of the present invention, these are intended to unify conditions and show typical examples. Needless to say, it is not necessarily limited to these.

Example 5 1.8 g of vanadium oxide was dissolved in a 30% oxalic acid aqueous solution, and an aqueous solution of zirconyl nitrate was added to the solution so that the atomic ratio of zirconyl nitrate to vanadium was 1:1.
1mm α-alumina (surface area 1m2/g or less) 36g
The mixture was evaporated to dryness on a hot water bath with occasional stirring, heated to 450°C in an electric furnace, and calcined for about 4 hours under air circulation to prepare a catalyst.

The reaction was carried out by filling 10 ml of the above catalyst into an old stainless steel tube with an inner diameter of 10 mm and heating it to a predetermined temperature. The results are shown below.

Claims (1)

[Claims] 1 Surface area 5 with vanadium and zircon as active ingredients
Supported on an inert carrier of 0 m2/9 or less and 600
In the presence of a catalyst obtained by calcination at a temperature below °C, 2-methyl-5,-ethylpyridine, ammonia, and oxygen are mixed at 30% by volume while introducing 20 to 80% by volume of water into the reaction system.
3, characterized in that the reaction is carried out at a temperature of 0 to 500°C.
- Method for producing cyanopyridine.