JPH07232071A - Catalyst for preparing nitrile from alkane - Google Patents

Abstract

(57) [Summary] [Structure] A composite oxide containing molybdenum, vanadium, tellurium and, as an optional component, a certain element such as niobium as a main component, and the X-ray diffraction line of the composite oxide is shown below. A catalyst for producing a nitrile from an alkane characterized by showing a peak. [Table 1] Diffraction angle 2θ (°) ───────── 9.0 ± 0.3 22.1 ± 0.3 27.3 ± 0.3 29.2 ± 0.3 35.4 ± 0.3 [Effect] Nitrile can be produced in higher yield than alkane.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to catalysts used to produce nitriles. More particularly, it relates to an improved catalyst for producing nitrile using an alkane as a raw material and a method for producing nitrile using the catalyst. Nitriles such as acrylonitrile and methacrylonitrile are industrially produced as important intermediates for fibers, synthetic resins and synthetic rubbers.

[0002]

2. Description of the Related Art As a method for producing nitrile, conventionally,
The so-called ammoxidation method in which an olefin such as propylene or isobutene is catalytically reacted with ammonia and oxygen in the gas phase at high temperature in the presence of a catalyst is known as the most general method. On the other hand, recently, a method for producing a nitrile by an ammoxidation method using a cheaper alkane such as propane or isobutane as a starting material as a starting material has also been reported.

Most of these methods for oxidation of alkanes are related to catalysts, specifically, Mo-Bi-P.
-O catalyst (Japanese Patent Laid-Open No. 48-16887), V-Sb-
O-based catalyst (JP-A-47-33783, JP-B-50-2)
3016, JP-A-1-268668, JP-A-2-
180637), Sb-U-V-Ni-O type catalyst (Japanese Patent Publication No. 47-14371), Sb-Sn-O type catalyst (Japanese Patent Publication No. 50-28940), V-Sb-W-P-O type. A catalyst (JP-A-2-95439), a catalyst obtained by mechanically mixing a V-Sb-W-O-based oxide and a Bi-Ce-Mo-WO-O-based oxide (JP-A-64-38051). No.), VS
n-Sb-Cu-O-based catalyst (JP-A-4-275266)
No.), Ag-Bi-V-Mo-O-based catalyst (JP-A-3-5)
8961), Sn-V-Mo-Bi-O-based catalyst (JP-A-4-247060), Cr-Mo-Te-MO-based catalyst (US Pat. No. 5,171,876) and the like. There is. In addition, the Applicant has also adopted a Mo-V-Te-Nb-O-based catalyst (JP-A-2-257 and JP-A-4-235153).
No.), a Mo-V-Te-Nb-X-O-based catalyst (Japanese Patent Application Laid-Open No. HEI 5)
-148212), Mo-V having a specific crystal structure
-Te-X-O based catalysts (JP-A-5-208136) are reported.

[0004]

However, none of these methods can sufficiently satisfy the target yield of nitriles. In addition, in order to improve the yield of nitriles, a method of adding a small amount of an organic halide, an inorganic halide, or a sulfur compound to the reaction system, a method of adding water, or the like has been attempted. There is a problem of corrosion of the reactor, and the latter has problems such as generation of a by-product by side reaction and its treatment, which are both difficult in industrial implementation. Further, most of the conventional methods using a catalyst system require an extremely high reaction temperature of about 500 ° C. or higher, which is not advantageous in terms of reactor material, manufacturing cost, and the like.

[0005]

Means for Solving the Problems As a result of various studies on the production method of nitrile using alkane as a raw material, the present inventors have found that molybdenum (Mo), vanadium (V), tellurium (Te) having a specific crystal structure. And in the presence of a complex oxide catalyst composed of certain other elements, the alkane is subjected to a gas phase catalytic reaction with ammonia, thereby eliminating the presence of halide, water, etc. in the reaction system, and 400 to 4
The inventors have found that the target nitrile can be produced with a higher yield than the conventional method at a relatively low temperature of about 50 ° C. and have reached the present invention.

The present invention will be described in detail below. The features of the catalyst of the present invention for producing a nitrile by subjecting an alkane to a gas phase catalytic oxidation reaction with ammonia are due to the following points. Molybdenum, vanadium, tellurium, oxygen, and X
(X is selected from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium. (Elements of at least one species) as constituent components, and the existence ratio of each constituent component to the total of the above constituent components excluding oxygen,

[0007]

0.25 <r _Mo <0.98 0.003 <r _V <0.50 0.003 <r _Te <0.50 0 ≤ r _X <0.50 (however, r _Mo, r _{V ,} r _Te, and r _X each represents a molar fraction of molybdenum, vanadium, tellurium, and X with respect to the sum of the above constituents excluding oxygen). . In the X-ray diffraction line of the complex oxide of, an X-ray diffraction peak is shown at a diffraction angle 2θ shown below.

[0008]

[Table 3] Diffraction angle 2θ (°) ───────── 9.0 ± 0.3 22.1 ± 0.4 27.3 ± 0.4 29.2 ± 0.4 35.4 ± 0.4 The main component of the catalyst of the present invention is the complex oxide described above, and the above element is used as X, but niobium, tantalum, tungsten and titanium are preferable, and particularly preferable are It is niobium. Also, Mo, V, Te,
The particularly preferable ranges of the mole fractions of and are as follows.

[0009]

Equation 4] _{0.25 <r Mo <0.98 0.01 <} r V <0.37 0.005 <r Te <0.27 0.001 <r X <0.35 the composite oxide, Simply satisfying the composition described in is not sufficient as a catalyst, and it is important to have a specific crystal structure. The inventors of the present invention have already disclosed in Japanese Unexamined Patent Publication No.
No. 208136, Mo-having a specific crystal structure
It has been reported that the V-Te-X-O-based composite oxide catalyst is a good catalyst when producing a nitrile from an alkane, but the composite oxide of the present invention is disclosed in JP-A-5-20813.
It has a novel crystal structure different from that defined in No. 6 and is extremely useful as a catalyst for producing a nitrile from an alkane.

An index showing that the complex oxide used as the catalyst of the present invention has a specific crystal structure is a powder X-ray diffraction pattern. The characteristic feature of the X-ray diffraction peak (using Cu-Kα ray as an X-ray source) pattern of the composite oxide is that the following five major diffraction peaks are observed at a specific diffraction angle 2θ.

[0011]

[Table 4] X-ray lattice plane Diffraction angle 2θ (°) Interval median value (A) Relative intensity ────────── ──────────── 9.0 ± 0. 3 9.83 0.5 to 30 22.1 ± 0.3 4.00 100 27.3 ± 0.3 3.27 2 to 150 29.2 ± 0.3 3.06 0.5 to 40 35. 4 ± 0.3 2.54 0.5-40

The X-ray diffraction peak intensity may deviate depending on the measurement conditions of each crystal, but the relative intensity is usually in the above range when the diffraction peak intensity at 2θ = 22.1 ° is 100. Of the above five diffraction peaks, 2θ =
The intensity of the diffraction peaks at 22.1 ° and 27.3 ° is large,
It is particularly preferable that the intensity of the diffraction peak at 27.3 ° is 25 to 140 when the intensity of the diffraction peak at 2θ = 22.1 ° is 100.

As long as the above-mentioned 5 diffraction peaks are recognized, even if there are peaks at 2θ other than the 5 diffraction peaks, there is no problem in the basic crystal structure and they are preferably used in the present invention. You can In particular, Japanese Patent Laid-Open No. 5-208
Even if the catalyst component reported in No. 136 coexists, the reaction can be used without any particular problem. The method for preparing the composite oxide having this specific crystal structure is as follows. For example, when preparing a composite oxide composed of molybdenum, vanadium, tellurium and niobium, first, an aqueous solution containing a predetermined amount of ammonium metavanadate, an aqueous solution of telluric acid, an aqueous solution of niobium ammonium oxalate and ammonium paramolybdate. The salt solution or the slurry is sequentially added in such an amount ratio that the atomic ratio of each metal element becomes a predetermined ratio. At this time, if necessary, an organic acid such as oxalic acid, tartaric acid, or citric acid may be added. The obtained solution or slurry is dried by an evaporation dryness method, a spray drying method, a vacuum drying method, a freeze drying method or the like, and finally the remaining dried product is usually 350 to 700 ° C, preferably 400 to 650 ° C. It is usually fired at a temperature for 0.5 to 30 hours to obtain the target composite oxide. Further, in order to perform the firing efficiently, the above dried product is treated in air or in an atmosphere of an inert gas such as nitrogen or argon before the final firing.
You may heat-decompose at about 0-350 degreeC.

The raw materials for the above complex oxides are not limited to those described above, but may be, for example, MoO ₃ , V ₂ O.
₅ , oxides such as V ₂ O ₃ , TeO ₂ and Nb ₂ O ₅ , MoC
halides such as l ₅ , VCl ₄ , VOCl ₃ , and NbCl ₅ , or oxyhalides, Mo (OC ₂ H ₅ ).
₅ , Nb (OC ₂ H ₅ ) ₅ , VO (OC ₂ H ₅ ) ₃ , alkoxides such as molybdenacetyl acetonate, and organometallic compounds can be widely used.

The composite oxide thus obtained can be used alone as a solid catalyst, but it is a well-known carrier such as silica, alumina, titania or aluminosilicate.
It can also be used with gluten, diatomaceous earth, zirconia and the like. Further, it is molded into an appropriate shape and particle size depending on the scale of reaction, method, and the like. Nitriles can be efficiently produced by subjecting an alkane to a gas phase catalytic oxidation reaction with ammonia in the presence of the above-mentioned catalyst. The reactor system is not particularly limited, and a fluidized bed, fixed bed, moving bed or the like can be adopted.

The alkane as a raw material is not particularly limited, and examples thereof include methane, ethane, propane, n-butane, isobutane, pentane, hexane, heptane, cyclohexane, and the like. Considering this, it is preferable to use a lower alkane having 1 to 4 carbon atoms, particularly propane or butane. Although the details of the oxidation reaction mechanism in the present invention are not clear, it is carried out by oxygen atoms present in the above oxides or molecular oxygen present in the feed gas. When molecular oxygen is present in the feed gas, the molecular 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. Alkane, a mixed gas of ammonia and an oxygen-containing gas is usually used as the supply gas, but a mixed gas of an alkane and ammonia and an oxygen-containing gas may be alternately supplied.

Further, substantially molecular oxygen is less than the stoichiometric amount for converting the alkane to the nitrile, and in some cases,
It is also possible to carry out a gas phase catalytic reaction using only alkane and ammonia as feed gases without the presence of molecular oxygen. In such a case, it is preferable that a part of the catalyst is appropriately withdrawn from the reaction zone, the catalyst is fed into an oxidation regenerator, and after regeneration, the catalyst is re-supplied to the reaction zone. Examples of the method for regenerating the catalyst include a method in which an oxidizing gas such as oxygen, air, or nitric oxide is passed through the catalyst in the regenerator at 300 to 600 ° C.

The present invention will be described in more detail in the case where propane is used as the alkane and air is used as the oxygen source. The ratio of air supplied to the reaction is important with respect to the selectivity of acrylonitrile to be produced, and air usually has a high acrylonitrile selectivity in the range of 25 mol times or less, particularly 1 to 18 mol times. Also,
The proportion of total ammonia supplied to the reaction is preferably in the range of 0.2 to 5 times by mole, particularly 0.5 to 3 times by mole, with respect to propane. The reaction is usually carried out under atmospheric pressure, but it may be carried out under pressure or under reduced pressure. For other alkanes, the composition of the feed gas is selected according to the case of propane.

In the present invention, the reaction temperature is lower than that in the conventional ammoxidation reaction of alkane, for example, 36.
It can be carried out at 0 to 480 ° C, particularly preferably at about 380 to 460 ° C. Even at such a low temperature, nitriles can be produced in a higher yield than conventional techniques. The gas space velocity SV in the gas phase reaction is usually 100 to 10,000 h ⁻¹ , preferably 3
The range is from 00 to 2000 h ^-1 . As a diluent gas for adjusting the space velocity and the oxygen partial pressure, a gas inert to the reaction such as nitrogen, argon or helium can be used.

[0020]

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

[0021]

[Formula 5] Alkane conversion rate (%) = (mol number of consumed alkane / mol number of supplied alkane) × 100 Selectivity of target nitrile (%) = (mol number of nitrile for production / mol number of consumed alkane) × 100 Yield (%) of target nitrile = (mol number of nitrile for production / mol number of alkane supplied) × 100

Example 1 A catalyst having the empirical formula Mo ₁ V _0.19 Te _0.12 Nb _0.04 O _n was prepared as follows. 78.9 g of ammonium paramolybdate (tetrahydrate), 9.94 g of metavanadate ammonium salt, and 12.3 g of telluric acid were dissolved in 325 ml of warm water to prepare a uniform aqueous solution. Next, a slurry was prepared by mixing 39.2 g of an aqueous solution of ammonium niobium oxalate having a niobium concentration of 0.456 mol / kg. The slurry was heat-treated to remove water and obtain a solid. 30 times until the solid smells of ammonia
After heat treatment at 0 ° C., firing was performed at 600 ° C. for 2 hours in a nitrogen stream. The powder X-ray diffraction measurement (X-ray source: Cu-Kα ray) of the oxide thus obtained was carried out, and the main diffraction line peak intensities thereof are shown in Table 1.

0.5 g of the above catalyst was charged into a fixed bed flow type reactor, the reaction temperature was 420 ° C., and the space velocity S of the total amount of gas was S.
V was fixed at 940 h ⁻¹ and gas was supplied at a molar ratio of propane: ammonia: air = 1: 1.2: 15 to carry out a gas phase catalytic reaction. The results are shown in Table-2. Example 2

The amount of telluric acid used in Example 1 was 1
An empirical formula Mo was obtained in the same manner as in Example 1 except that 5.4 g was used.
The catalyst having a _{1 V 0.19 Te 0.15 Nb 0.04 O} n was prepared.
Table 1 shows the main diffraction line peak intensities in the powder X-ray diffraction measurement of the oxide thus obtained. Using the above catalyst, the gas phase catalytic reaction of propane was carried out under the same conditions as in Example 1 except that the reaction temperature in Example 1 was 400 ° C. The results are shown in Table-2.

Example 3 A catalyst having the empirical formula Mo ₁ V _0.3 Te _0.12 O _n was prepared as follows. Dissolving 78.9 g of ammonium paramolybdate (tetrahydrate), 15.7 g of ammonium metavanadate, and 12.3 g of telluric acid in 325 ml of warm water,
A homogeneous aqueous solution was prepared. Water was removed by heating this aqueous solution to obtain a solid. This solid was heat-treated at 300 ° C. until the smell of ammonia disappeared, and then calcined in a nitrogen stream at 600 ° C. for 2 hours. Table 1 shows the main diffraction line peak intensities in the powder X-ray diffraction measurement of the oxide thus obtained. 0.5 g of the catalyst thus obtained was charged into a fixed bed flow type reactor, the reaction temperature was 430 ° C., the space velocity SV of the total amount of gas was fixed at 1000 h ⁻¹ , and propane: ammonia: air = 1: Gas was supplied at a molar ratio of 1.2: 15 to carry out a gas phase catalytic reaction. The results are shown in Table-2.
Shown in.

[0026]

[Table 5]

[0027]

[Table 6]

[0028]

EFFECTS OF THE INVENTION According to the method of the present invention, by using a novel complex oxide catalyst using alkane as a raw material, it is possible to prevent the presence of halide, water and the like in the reaction system, and to compare at about 400 to 450 ° C. The target nitrile can be produced in high yield at extremely low temperature.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Kiyono, 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryoh Kasei Co., Ltd. (72) Inventor Kei Inumaru, 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Ryokasei Co., Ltd.

Claims (4)

[Claims] 1. A catalyst for producing a nitrile from an alkane satisfying the following conditions: Molybdenum, vanadium, tellurium, oxygen, and X
(X is selected from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium. The ratio of each constituent component to the total of the above constituent components excluding oxygen is 0.25 <r _Mo <0.98 0.003 <r _V <0. 50 0.003 <r _Te <0.50 0 ≤ r _X <0.50 (where r _Mo, r _V, r _Te, and r _X are the respective constituents relative to the total of the above constituents excluding oxygen). Molybdenum, vanadium, tellurium and X mole fractions relative to the total)) as the main component. In the X-ray diffraction line of the complex oxide of, an X-ray diffraction peak is shown at a diffraction angle 2θ shown below. [Table 1] Diffraction angle 2θ (°) ───────── 9.0 ± 0.3 22.1 ± 0.3 27.3 ± 0.3 29.2 ± 0.3 35.4 ± 0.3 2. The X-ray diffraction line of the complex oxide has a diffraction peak intensity of 1 at a diffraction angle 2θ (°) = 22.1 ± 0.3.
2. The catalyst according to claim 1, wherein the intensity of the diffraction peak at 27.3 ± 0.3 when measured as 00 is 25 to 140. 3. A method for producing a nitrile, which comprises subjecting an alkane to a gas phase catalytic oxidation reaction with ammonia in the presence of a catalyst satisfying the following conditions: Molybdenum, vanadium, tellurium, oxygen, and X
(X is selected from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium. The proportion of each constituent component relative to the total of the above constituent components excluding oxygen is 0.25 <r _Mo <0.98 0.003 <r _V <0. 50 0.003 <r _Te <0.50 0 ≤ r _X <0.50 (where r _Mo, r _V, r _Te, and r _X are the respective constituents relative to the total of the above constituents excluding oxygen). Molybdenum, vanadium, tellurium and X mole fractions relative to the total)) as the main component. In the X-ray diffraction line of the complex oxide of, an X-ray diffraction peak is shown at a diffraction angle 2θ shown below. [Table 2] Diffraction angle 2θ (°) ───────── 9.0 ± 0.3 22.1 ± 0.3 27.3 ± 0.3 29.2 ± 0.3 35.4 ± 0.3 4. The X-ray diffraction line of the complex oxide has a diffraction peak intensity of 1 at a diffraction angle 2θ (°) = 22.1 ± 0.3.
The intensity of the diffraction peak of 27.3 ± 0.3 when set to 00 is 25 to 140, The manufacturing method of the nitrile of Claim 3 characterized by the above-mentioned.