JP3353345B2 - Nitrile manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a nitrile. More specifically, the present invention relates to a method for producing an improved nitrile using alkane as a raw material.

[0002]

2. Description of the Related Art Nitriles such as acrylonitrile and methacrylonitrile are industrially produced as important intermediates such as fibers, synthetic resins and synthetic rubbers. Is known as the most common method in which an olefin is subjected to a catalytic reaction at a high temperature in the gas phase with ammonia and oxygen in the presence of a catalyst.

On the other hand, due to the price difference between propane and propylene, or the price difference between isobutane and isobutene, a lower alkane such as propane or isobutane is used as a starting material, and ammonia and oxygen are added in the presence of a catalyst. There has been increasing interest in the development of a method for producing acrylonitrile and methacrylonitrile by a so-called ammoxidation reaction method in which a gas is brought into contact with a gas in the gas phase. As an example of these reports, Mo-Bi-PO catalysts (JP-A-48-16)
887), V-Sb-O-based catalysts (JP-A-47-337)
No. 83, Japanese Patent Publication No. 50-23016, Japanese Patent Laid-Open No. 1-268
No. 668), Sb-UV-Ni-O-based catalyst (Japanese Patent Publication No. Sho 4).
No. 7-14371), a Sb-Sn-O-based catalyst (Japanese Patent Publication No. Sho 5)
No. 0-28940), a V-Sb-W-PO-based catalyst (JP-A-2-95439), a V-Sb-WO-based oxide and a Bi-Ce-Mo-WO-based oxide. Catalyst obtained by mechanically mixing (JP-A-64-38051), Mo-V-Nb
-Te-O-based catalysts (JP-A-2-257) and the like.

[0004]

However, none of these methods can sufficiently satisfy the yield of the desired nitrile. Further, in order to improve the yield of nitriles, a small amount of organic halide,
A method of adding an inorganic halide, or a sulfur compound, or a method of adding water has been attempted,
The former has a problem of corrosion of the reaction apparatus, and the latter has a problem of generation of by-products by a side reaction and treatment thereof, and both have problems in industrial implementation.

[0005]

The present inventors have conducted various studies on a method for producing a nitrile using an alkane as a raw material, and have found that niobium (Nb) and / or tantalum (Ta),
Chromium (Cr), molybdenum (Mo), bismuth (B
i) and by reacting the alkane with ammonia in the gas phase in the presence of an oxide composed of a certain kind of metal, whereby the yield is higher than that of the conventional method without the presence of halides or water in the reaction system. The present inventors have found that the desired nitrile can be produced at a high rate, and have achieved the present invention.

Hereinafter, the present invention will be described in detail. Gist of the present invention, empirical formula alkanes _{X a Cr b Mo c Bi d} Y e O n (1) in (Equation (1), X is Nb and / or Ta, Y
Are Te, In, W, Ti, Al, Zr, Mn, Fe, R
represents one or more elements selected from u, Co, Rh, Ni, Pd, Pt, Sb, Bi, and Ce, and when a = 10, b = 0.5 to 5 c = 0 0.2-5 d = 0.2-5 e = 0-5 n is determined by the oxidation state of other elements. A) a gas phase catalytic oxidation reaction with ammonia in the presence of the oxide represented by the formula (1).

In the oxide of the formula (1) used here,
X is particularly preferably Nb, and Y need not necessarily be present. Further, as a coefficient of the equation (1), a =
When b = 0.8, b = 0.8-3, c = 0.3-1, d
= 0.3 to 1 and e = 0 to 1 are particularly preferred. It is not clear why the oxide of the formula (1) works favorably in the production of nitriles from alkanes, but it is said that it works effectively in the alkane dehydrogenation process, which is the most difficult stage for this reaction. Presumed.

To obtain the above-mentioned oxide, its preparation
As a method, for example, Nb_a Cr _bMo_cBi_dO_n
In the case of, a predetermined amount of ammonium paramolybdate
An aqueous solution of bismuth nitrate in an aqueous solution containing
Aqueous solution of niobium ammonium salt, aqueous solution of chromium nitrate
In such an amount that the atomic ratio of each metal element is the specified ratio
Evaporation to dryness, spray drying, vacuum drying
Etc., and finally the remaining dried product is usually 350 to 7
At a temperature of 00 ° C, preferably 400-650 ° C, usually
Bake for 0.5-30 hours, preferably 1-10 hours
Make the target oxide.

Of these, the raw materials for oxides are limited to those described above.
Instead of ammonium paramolybdate
MoO_Three, MoCl_FiveIs used, bismuth nitrate
Bi instead of_TwoO_Three, Bi (OH)_Three, BiCl_Three,
Bismuth nitrate oxide, bismuth acetate, etc. are used.
NbCl instead of niobium ammonium salt_Five, Nb _Two
O_Five, Niobate, etc. are used, and C is used instead of chromium nitrate.
rCl_Three, CrCl_Two, CrO, Cr_TwoO_Three, Cr
O_Three, Cr (OH)_Two, Cr (OH)_Three・ NH_TwoO etc.
Can be used.

Although these oxides can be used alone,
It can also be used with known carriers such as silica, alumina, titania, aluminosilicate, diatomaceous earth and the like. Further, it is molded into an appropriate shape and particle size according to the scale and system of the reaction. In the method of the present invention, a nitrile is produced by subjecting an alkane to a gas-phase catalytic oxidation reaction with ammonia in the presence of the above-mentioned oxide.

In the present invention, the raw material alkane includes
There is no particular limitation, for example, methane, ethane,
Propane, butane, isobutane, pentane, hexane,
Heptane, cyclohexane and the like can be mentioned, and in view of industrial use of the obtained nitrile, it is preferable to use a lower alkane having 1 to 4 carbon atoms, particularly propane and isobutane.

Although the details of the mechanism of the oxidation reaction in the present invention are not clear, the oxidation reaction is carried out by oxygen atoms present in the above-described oxide or oxygen present in the supply gas. When oxygen is present in the supply gas, the oxygen may be pure oxygen gas, but since purity is not particularly required, it is generally economical to use an oxygen-containing gas such as air. When oxygen is not present in the feed gas, an alkane-ammonia mixed gas and an oxygen-containing gas are alternately supplied to prevent reduction deterioration of oxides, or by using a moving bed type reactor, A method in which the oxide is continuously fed to an oxidation regenerator and regenerated and used is preferred.

In the case where propane is used as the alkane and air is used as the oxygen source, the present invention will be described in more detail. In the reactor system, any of a fixed bed, a fluidized bed, and the like can be adopted. The fluidized bed system makes it easier to control the reaction temperature. The proportion of air supplied to the reaction is important with respect to the selectivity of the acrylonitrile formed, the air usually being no more than 25 mole times relative to propane,
In particular, the range of 1 to 15 times the molar amount indicates a high acrylonitrile selectivity.

The ratio of ammonium donated to the reaction is 0.2 to 5 times the molar amount of propane, particularly 0.5
A range of 3 to 3 times the molar amount is preferred. This reaction is usually carried out under atmospheric pressure, but can also be carried out under low pressure or low pressure. In the method of the present invention, for example,
It can be carried out at 400 to 570 ° C, and particularly preferably at about 450 to 520 ° C. The gas space velocity SV in the gas phase reaction, 100～10000H ^-1, preferably in the range of 300~2000h ^-1. In addition,
As a diluent gas for adjusting space velocity and oxygen partial pressure,
An inert gas such as nitrogen, argon, or helium can be used. When propane is subjected to an ammoxidation reaction by the method of the present invention, carbon monoxide, carbon dioxide, acetonitrile, hydrocyanic acid, and the like are produced as by-products in addition to acrylonitrile, but the amount produced is extremely small.

[0015]

According to the method of the present invention, the use of a novel oxide makes it possible to produce a desired nitrile in a high yield without the presence of a halide or water in the reaction system. it can.

[0016]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples unless it exceeds the gist. The conversion (%) in the following Examples and Comparative Examples,
The selectivity (%) and the yield (%) are represented by the following formulas, respectively.

[0017]

## EQU1 ## Conversion of alkane (%) = (moles of alkane consumed / moles of supplied alkane) × 100 Selectivity of target nitrile (%) = (moles of target nitrile formed / moles of alkane consumed) × 100 Yield (%) of target nitrile = (moles of target nitrile to be produced / moles of alkane supplied) × 100

[0018] was prepared in Example 1 empirical composition _{Nb 10 Cr 2 Mo 0.48 Bi 0.4} O n (50 wt%) / oxides having a silica (50 wt%) as follows. To 16.45 g of 20 wt% silica sol, 0.96 ml of a 4 wt% aqueous ammonia solution of ammonium paramolybdate having a molybdenum concentration of 1 mol / l was added with stirring, followed by 5 mol of 1 mol / l bismuth nitrate as bismuth. 0.80 ml of aqueous nitric acid solution was added. Next, 20 ml of a 1 mol / l niobium ammonium oxalate aqueous solution as niobium and 4 ml of a 1 mol / l aqueous solution of chromium nitrate as chromium were sequentially added, and the mixture was heated to dryness with stirring until no NO ₂ was generated.
The obtained solid was molded to a diameter of 7 mm and a thickness of 3 mm using a tablet molding machine, baked at 550 ° C. for 2 hours under air flow, and then pulverized into 16 to 24 mesh granules.

A reactor was filled with 0.5 ml of the oxide thus obtained, and the reaction temperature was 500 ° C. and the space velocity SV was 50.
0 h ⁻¹ , propane: ammonia: air = 1:
A gas was supplied at a molar ratio of 1.2: 15 to perform a gas phase catalytic oxidation reaction. The conversion of propane was 49.3%, the selectivity for acrylonitrile was 34.7%, and the yield of acrylonitrile was 17.1%.

Example 2 A reactor was filled with 0.5 ml of the fixed material obtained as in Example 1, and the reaction temperature was 500 ° C. and the space velocity SV was 500 hours.
^-1 and propane: ammonia: air = 1: 1.
A gas was supplied at a molar ratio of 2:15 to perform a gas phase contact reaction. The conversion of propane was 45.5%, the selectivity for acrylonitrile was 35.6%, and the yield of acrylonitrile was 1
6.2%.

Example 3 A reactor was charged with 0.5 ml of the solid obtained as in Example 1, and the reaction temperature was 500 ° C. and the space velocity SV was 500 hours.
^-1 and propane: ammonia: air = 1: 1.
A gas was supplied at a molar ratio of 2:10 to perform a gas phase contact reaction. The conversion of propane was 51.5%, the selectivity for acrylonitrile was 27.0%, and the yield of acrylonitrile was 1
It was 3.9%.

Example 4 An oxide was prepared in the same manner as in Example 1 except that the amount of the aqueous solution of ammonium paramolybdate used was 1.92 ml. The empirical composition of the obtained oxide had a _{Nb 10 Cr 2 Mo 0.95 Bi 0.4} O n (50 wt%) / silica (50 wt%). Using the solid thus obtained, propane, ammonia and air were supplied under the same conditions as in Example 1 to perform a gas phase catalytic oxidation reaction at a reaction temperature of 510 ° C. As a result, the conversion of propane was 31.9%, and the selectivity of acrylonitrile was 48.
The yield of acrylonitrile was 6%, and the yield of acrylonitrile was 15.5%.

Example 5 Using the solid obtained as in Example 4, propane, ammonia and air were supplied under the same conditions as in Example 2 to conduct a gas phase catalytic oxidation reaction at a reaction temperature of 500 ° C. Done.
As a result, the conversion of propane was 28.6%, the selectivity for acrylonitrile was 50.0%, and the yield of acrylonitrile was 14.3%.

Example 6 An oxide was prepared in the same manner as in Example 1 except that the amount of the aqueous niobium ammonium oxalate used in Example 1 was changed to 18 ml, and 4 ml of a 0.5 mol / l aqueous solution of tantalum oxalate was added as tantalum. Was prepared. The experimental composition of the obtained oxide was Nb ₃ Ta ₁ Cr ₂ Mo _0.48 Bi.
_0.4 O _n (50 wt%) was / silica (50 wt%). Example 1 was prepared using the solid thus obtained.
Supply propane, ammonia and air under the same conditions as
A gas phase catalytic oxidation reaction was performed at a reaction temperature of 510 ° C. As a result, the conversion of propane was 68.6%, the selectivity of acrylonitrile was 21.6%, and the yield of acrylonitrile was 1
It was 4.8%.

Example 7 Using the solid obtained as in Example 6, propane, ammonia and air were supplied under the same conditions as in Example 2 to conduct a gas phase catalytic oxidation reaction at a reaction temperature of 500 ° C. Done.
As a result, the conversion of propane was 67.7%, the selectivity for acrylonitrile was 17.3%, and the yield of acrylonitrile was 11.7%.

Example 8 Experimental composition in Example 1 Nb ₁₀ Cr ₂ Mo _0.48 Bi
_0.4 the composition ratio between O _n becomes oxide and silica 80 wt% /
The amount of silica sol used was set and adjusted so as to be 20% by weight. Using the solid thus obtained, propane, ammonia and air were supplied under the same conditions as in Example 1 to perform a gas phase catalytic oxidation reaction at a reaction temperature of 510 ° C. As a result, the conversion of propane was 36.2%, the selectivity for acrylonitrile was 41.2%, and the yield of acrylonitrile was 14.9%.

Example 9 Using the solid obtained as in Example 8, propane, ammonia and air were supplied under the same conditions as in Example 2 to conduct a gas phase catalytic oxidation reaction at a reaction temperature of 500 ° C. Done.
As a result, the conversion of propane was 32.8%, the selectivity for acrylonitrile was 40.5%, and the yield of acrylonitrile was 13.3%.

[0028] Comparative Example 1 empirical composition _{Nb 10 Cr 1 Te 1 O n} (50 wt%) / silica oxide having a (50 wt%) was prepared as follows. 20 ml of a 1 mol / l ammonium niobium oxalate aqueous solution as niobium, 2 ml of a 1 mol / l chromium nitrate aqueous solution as chromium, and 0.1 mol / l aqueous solution of telluric acid as tellurium are added to 16.05 g of 20 wt% silica sol. NO _{2 with} stirring
The mixture was heated to dryness until the generation of the residue disappeared. The obtained solid was molded to a diameter of 7 mm and a thickness of 3 mm using a tablet molding machine, baked at 550 ° C. for 2 hours under an air flow, and then pulverized into 16 to 24 mesh granules.

A reactor was filled with 0.5 ml of the oxide thus obtained, and propane, ammonia and air were supplied under the same conditions as in Example 2, and a gas phase catalytic oxidation reaction was carried out at a reaction temperature of 500 ° C. Done. The conversion of propane is 44.3%,
The selectivity for acrylonitrile was 10.9%, and the yield of acrylonitrile was 4.8%.

Comparative Example 2 The amount of the chromium nitrate aqueous solution used in Comparative Example 1 was 4 ml,
Comparative Example except that the amount of silica sol used was 15.72 g
1 and the experimental composition Nb_TenCr_TwoTe ₁O
_nOxidation with (50% by weight) / silica (50% by weight)
I got something. 0.5 ml of the oxide thus obtained is reacted
And propane and ammonia under the same conditions as in Example 2.
Near-air supply, gas phase contact acid at reaction temperature 500 ℃
The reaction was carried out. The conversion of propane was 42.4%,
Acrylonitrile selectivity 10.6%, acrylonitrile
The yield of toluene was 4.5%.

Comparative Example 3 The amount of the chromium nitrate aqueous solution used in Comparative Example 1 was 6 ml.
Comparative Example except that the amount of silica sol used was 14.29 g.
1 and the experimental composition Nb_TenCr_ThreeTe ₁O
_nOxidation with (50% by weight) / silica (50% by weight)
I got something. 0.5 ml of the oxide thus obtained is reacted
And propane and ammonia under the same conditions as in Example 2.
Near-air supply, gas phase contact acid at reaction temperature 500 ℃
The reaction was carried out. The conversion of propane was 40.9%,
6.1% selectivity for acrylonitrile, acrylonitrile
Was 2.5%.

Comparative Example 4 The same procedure as in Example 1 was repeated except that ammonium paramolybdate was not used and the amount of silica sol used was 16.22 g, and the experimental composition was Nb ₁₀ Cr ₂ Bi _0.4 O.
An oxide having _n (50% by weight) / silica (50% by weight) was obtained. 0.5 ml of the oxide thus obtained was charged into a reactor, and propane, ammonia and air were supplied under the same conditions as in Example 2 to perform a gas phase catalytic oxidation reaction at a reaction temperature of 500 ° C. The conversion of propane was 37.9%, the selectivity for acrylonitrile was 6.6%, and the yield of acrylonitrile was 2.5%.

[0033] without the use of bismuth nitrate in Comparative Example 5 Comparative Example 1, the amount of silica sol as 15.98 g, prepared like in Example 1, empirical composition _{Nb 10 Cr 2 Mo 0.48 O n} (50 wt% )
/ Oxide with silica (50% by weight) was obtained. 0.5 ml of the oxide thus obtained was charged into a reactor, and propane, ammonia and air were supplied under the same conditions as in Example 2 to perform a gas phase catalytic oxidation reaction at a reaction temperature of 500 ° C. The conversion of propane was 32.9%, the selectivity of acrylonitrile was 17.3%, and the yield of acrylonitrile was 5.
7%.

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ identification code FI // C07B 61/00 300 B01J 23/84 301X (58) Field surveyed (Int.Cl. ⁷ , DB name) C07C 255/08 C07C 253/24 C07B 61/00 300 B01J 23/31 B01J 23/84-23/88

Claims (1)

(57) [Claims] Experiment 1. A alkane formula _{X a Cr b Mo c Bi d} Y e O n (1) in (Equation (1), X is Nb and / or Ta, Y
Are Te, In, W, Ti, Al, Zr, Mn, Fe, R
represents one or more elements selected from u, Co, Rh, Ni, Pd, Pt, Sb, Bi, and Ce, and when a = 10, b = 0.5 to 5 c = 0 0.2-5 d = 0.2-5 e = 0-5 n is determined by the oxidation state of other elements. A) producing a nitrile by subjecting it to a gas phase catalytic oxidation reaction with ammonia in the presence of an oxide represented by