JP2806480B2 - Method for producing 2,6-dichlorobenzonitrile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the production of 2,6-dichlorobenzonitrile (hereinafter abbreviated as DBN) by gas-phase catalytic ammoxidation of 2,6-dichlorotoluene. It relates to a manufacturing method.

DBN itself is not only important as a herbicide, but is also widely used as an intermediate for herbicides, intermediates for agricultural and horticultural insecticides, and as intermediates or raw materials for various drugs, dyes, and polymers. Is a very important compound.

(Prior Art) A reaction for converting 2,6-dichlorotoluene to DBN by amooxidation is known. For example, a method of synthesizing DBN by a fluid catalytic reaction using a V-based catalyst (Japanese Patent Publication No. 43-10623), a method of synthesizing using a V-Fe-based catalyst similarly (Japanese Patent Publication No. 43-5386), Method of synthesizing using VP catalyst (JP-A-53-121738)
Etc. are known.

However, these catalyst systems are not satisfactory in terms of the target DBN yield. This is mainly due to the main reaction of the desired ammoxidation,
The combustion of 6-dichlorotoluene causes competitive and considerable side reactions to produce the resulting ammonium chloride.

For the purpose of controlling this side reaction, for example, a method of adding a bromine compound to a reaction system when synthesizing DBN by a fluidized contact reaction using a VP-based catalyst (JP-A-60-67454), and In the case where the V-Fe-Sb system is further required, a method of synthesizing DBN by a fluid catalytic reaction using a catalyst system in which four or more other metal components are combined in addition to the above three components (Japanese Patent Application Laid-Open No. Sho 63) -250357) and the like.

However, the method of adding the third substance to the reaction system as in the former, for example, cannot be said to be economically advantageous in itself,
Further, the problem remains from the viewpoint of contamination of the target DBN with impurities. For example, in order to obtain good results as in the latter case, sometimes a method using a catalyst system combining eight or more metal oxides is not rational due to the economics of the catalyst itself or the method of adjusting the system. It is hard to say.

More generally, such ammoxidation is usually carried out by a fluidized contact reaction, that is, a fluidized bed method, since the side reaction is considered to be increased by local high-temperature heating. The method has a disadvantage that it tends to cause a large-scale equipment configuration and often falls into an unprofitable state depending on a balance with a product.

The use of a fixed bed system can alleviate this kind of problem to some extent. However, it is still desired to develop a sufficiently good catalyst species to compensate for the above-mentioned problem of local heating.

(Problem to be solved by the present invention) The present invention provides a method for producing DBN by an industrially advantageous method, and more specifically, V-Mo-Cr-P
Production of DBN with high yield and high selectivity from ammoxidation of 2,6-dichlorotoluene by using γ-alumina carrying a metal oxide based catalyst and using a molded catalyst whose pore distribution is controlled It provides a way to:

(Means for Solving the Problem) The method for producing DBN according to the present invention is characterized in that when ammoxidation of 2,6-dichlorotoluene with a gas containing ammonia and oxygen, Va, Mob, Crc, Pd, Oe ( Where a, b,
c, d and e indicate atomic ratios, and when a = 1, b = 0.05-10,
c = 0.1 to 30, d = 0.05 to 10, and e represents a number inevitable from other valences. The metal oxide having the composition
-Characterized by using a catalyst which is supported on alumina, and which is molded so that the pore volume of macropores in the range of 500Å to 10μ is maintained at least 0.1 cc / g or more in the pore distribution of the supported material. Things.

The composition of the metal oxide used in the catalyst according to the present invention may be any composition as long as it is within the range shown by the above general formula. Preferably, if a is 1 in the above general formula, b = 0.1 to 1, c = 0.5-3 and d = 0.1-3. (E is also a number necessarily taken from other valences.) As a starting material for each of these components, generally, a catalyst such as an oxide, halide, sulfate, ammonium salt of each metal is prepared. You can choose from the many types that are used when doing so.

For example, to introduce a vanadium component, vanadium pentoxide, ammonium metavanadate, vanadium nitrate, vanadium halides and the like are used.To introduce a molybdenum component, ammonium paramolybdate, ammonium metamolybdate, Molybdenum trioxide, molybdenum halides and the like are used.
In order to introduce a chromium component, for example, ammonium bichromate, ammonium chromate, chromium nitrate, etc. are used, and to introduce a phosphorus component, phosphoric acid, phosphate, hypophosphorous acid, pentoxide, etc. Phosphorus or the like is used.

For adjusting each of these components in the present invention, a general method often used for adjusting such a metal oxide catalyst can be applied. For example, a vanadium compound is dissolved in water, a phosphorus compound is added thereto, and an aqueous solution of a chromium compound and a molybdenum compound is further added to homogenize the mixture. Next, it is obtained by evaporating it to dryness, baking it and performing necessary molding.

An important point of the present invention lies in the pore distribution of the catalyst thus molded.

Industrial catalysts usually used for gas-phase catalytic reactions such as ammoxidation, to prevent their strength deterioration,
If a fixed bed system is adopted, it is molded and used in order to avoid pressure loss, and various types of silica, alumina, zeolite and the like are considered to be suitable for the carrier used at that time. Although there are various types of carriers having the pore distribution characteristics required in the present invention, the activity is maintained or enhanced after being molded, and as described above, it is preferable that the carrier be sufficiently used even in a fixed bed system. Γ-alumina is desirable as a carrier for exhibiting catalytic activity.

Any kind of γ-alumina can be used, but it is preferable to use γ-alumina finer than 200 mesh in order to impregnate each metal component for adjustment.

The loading ratio of each metal component on γ-alumina was determined based on the amount of V ₂ O ₅ supported on the basis of vanadium as the main catalyst.
Al ratio of ₂ O ₃ may be within a range of about _{1~30 (V 2 O 5 wt /} Al 2 O 3 wt)% , but preferably _{2~20 (V 2 O 5 wt /} Al 2 O ₃ wt)
% Range.

The metal oxide-γ-alumina catalyst adjusted in this manner is subjected to molding in order to give it strength, in which case if necessary, bentonite, alumina sol,
It is also possible to add a binder such as silica sol.

The molding method is generally a method such as extrusion molding, compression molding, tablet molding or formation with a marmellaizer, but the pore distribution characteristics required by the present invention, that is, 500 to 10
The pore volume of macropores in the μ range is at least 0.1 cc /
Excessive compression to mold to keep the above g, or tablet is undesirable, extrusion or molding by Marumerizer, or 15 kg / cm ² or less tabletting molding method for molding by tableting pressure etc. Is preferred.

The pore volume of this macro poise required by the present invention complements the main reaction (ammoxidation) mainly performed in micro poise and meso poise, and simultaneously the side reaction (combustion due to excessive reaction heat accumulation) performed in the same pore. As a result, it is indispensable to reduce the reaction of by-producing ammonium chloride). The present invention is carried out by introducing a gas containing 2,6-dichlorotoluene, ammonia and oxygen into a reactor filled with a shaped catalyst having pore distribution characteristics thus adjusted.

These introduced gases may include nitrogen and other inert gases such as water vapor, carbon dioxide, carbon monoxide, and the like, and it is economically desirable to use air as the oxygen-containing gas.

The concentration of 2,6-dichlorotoluene in the introduced gas is 0.5 to 15
Although it may be within the range of mol%, preferably 1 to 7 mol%
Range. Similarly, the molar ratio of 2,6-dichlorotoluene to ammonia and oxygen in the gas may be 2,6-dichlorotoluene: ammonia: oxygen = 1: 1 to 10: 1.5 to 10, but is preferably 1: 1.5-7: 2-7.

The reaction temperature may be 300 to 600 ° C., preferably 320 to 420
It is in the range of ° C.

The reaction can be carried out under any of normal pressure, increased pressure and reduced pressure, but is preferably carried out within a range from normal pressure to 3 kg / cm ² G. The contact time may be 0.5 to 50 seconds, preferably 2 to 25 seconds, based on the gas volume under the conditions in which the reaction is carried out.

The reaction may be carried out in a fixed bed system or a fluidized bed system, but as described above, the fixed bed system is preferable in order to make use of the characteristics of the present catalyst.

(Effect of the Invention) The V-Mo-Cr-P-based / γ-alumina-supported catalyst of the present invention has an ammoxidation for producing DBN from 2,6-dichlorotoluene based on its catalyst composition and its pore distribution characteristics. Expresses excellent activity and selectivity. Therefore, by using the catalyst of the present invention, DBN which is an industrially important compound can be obtained in a high yield, and it can be carried out industrially more advantageously than the conventional method.

Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited by this.

The conversion of 2,6-dichlorotoluene, the yield of DBN, the selectivity of DBN, and the by-product rate of ammonium chloride described in the following Examples were calculated according to the following definitions.

In the examples, the description of oxygen in the catalyst and metal oxide composition is omitted because it is a value naturally determined from the valence of other elements.

Example 1 200 g of ammonium metavanadate was suspended in 4 l of pure water.
Heated to 80 ° C. To this, 50 g of oxalic acid was added little by little to make a completely homogeneous solution. Next, ammonium chromate, previously dissolved in 200 g of 85% phosphoric acid and 3 pure waters,
Similarly, 90 g of ammonium molybdate dissolved in the pure water of No. 2 was added, respectively, to obtain a homogeneous solution with stirring.
To this solution, 2600 g of active γ-alumina finer than 200 mesh was added and stirred at 80 ° C. for 2 hours to sufficiently impregnate the metal component. After evaporating this to dryness, 500 ℃ in air stream
For 5 hours. Bentonite was added as a binder at a ratio of 3 (wt / wt) to the calcined catalyst 7,
Kneaded with an appropriate amount of water and hydroxyethyl cellulose. This was extruded to 3 mmφ × 3 to 7 mm, and then calcined at 500 ° C. for 5 hours in an air stream to obtain a desired catalyst.

The loading of the catalyst thus obtained is 6%, and the composition is
V ₁ , Mo _0.3 , Cr ₁ , and P _0.7 . The pore distribution of this catalyst was measured by a mercury intrusion method using a pore sizer.
The pore volume of macropoise in the range of 0Å to 10μ is 0.13cc /
The value of g is shown.

The catalyst was placed in a fixed-bed reactor having an inner diameter of 1 inch and a bed length of 44 inches.
cm (about 200 g) and the reactor was immersed in an alumina fluidized bath to maintain the temperature at 340-350 ° C.

2,6-dichlorotoluene, 2.8 mol%, ammonia 11.2
A mixed gas containing mol%, 11.2 mol% of oxygen, and 74.8 mol% of nitrogen was introduced into the reactor, and the reaction was performed while adjusting the fluidized bath so that the maximum temperature in the catalyst layer did not exceed 360 ° C. At this time,
The superficial linear velocity was kept at 4.1 cm / sec and the contact time was kept at 10.7 sec.

Thereafter, the addition ratio of 2,6-dichlorotoluene was 95.1%,
The yield of BN was 85%, the selectivity was 90.1%, and the by-product rate was 9.9%.

Comparative Example 1. A catalyst prepared and kneaded in the same manner as in Example 1 was subjected to tableting pressure of 30 kg / c.
It was tableted to 3 mmφ × 3 mm in m ² .

After calcination in the same manner, when the pore distribution of this catalyst was measured, the pore volume of macropores in the range of 500Å to 10μ was
It showed a value of 0.06 cc / g. When the reaction was carried out under the same conditions as in Example 1 using this catalyst, the conversion of 2,6-dichlorotoluene was 96.9%, the yield of DBN was 77.8%, and the selectivity was 80.
The by-product rate was 51.2%.

Example 2 Same as Example 1 except that the superficial linear velocity was changed to 8.3 cm / sec, the contact time was changed to 5.3 seconds, and the maximum temperature in the catalyst layer was not exceeded 380 ° C. The reaction was carried out. As a result, the conversion of 2,6-dichlorotoluene was 90.2
8, DBN yield 79.5%, selectivity 88.5%, by-product rate 11.4
Met.

Examples 3 to 5 The reaction was carried out in the same manner as in Example 1 except that the catalyst was adjusted by changing the atomic ratio of V: P or Mo. The results, including macropore pore volume, are shown in Table-I.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-67454 (JP, A) JP-A-63-250357 (JP, A) JP-A-53-121738 (JP, A) 21243 (JP, B1) JP-B-45-5386 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 255/50 C07C 253/28

Claims (1)

(57) [Claims] (1) When ammoxidation of 2,6-dichlorotoluene with a gas containing ammonia and oxygen, VaMo
bCrcPdOe (where a, b, c, d, and e indicate an atomic ratio, and a
= 1, b = 0.05-10, c = 0.1-30, d = 0.05-10,
e indicates a number necessarily taken from other valences. ) A metal oxide catalyst having the following composition is supported on γ-alumina, and the pore distribution of the supported material is 500Å to 1
The pore volume of macropoise in the range of 0μ is at least 0.1
A method for producing 2,6-dichlorobenzonitrile, characterized by using a catalyst molded to maintain cc / g or more.