JP2003320248A - Method for preparing oxidation catalyst and method for manufacturing nitrile using the catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a catalyst in which a selectivity of the corresponding unsaturated acid or unsaturated nitrile is high in a vapor phase catalytic oxidation or a vapor phase catalytic ammoxidation reaction of an alkane. <P>SOLUTION: In the catalyst preparation method, annealing is carried out at a lower temperature than the baking temperature after completion of the baking. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for preparing an oxide catalyst containing at least one element selected from tellurium and antimony, molybdenum, vanadium and niobium, which is used in a gas phase catalytic ammoxidation reaction of propane or isobutane. And a method for producing nitrile using the catalyst.

[0002]

2. Description of the Related Art In recent years, in the production of unsaturated acids or nitriles, alkanes have been used as a starting material instead of alkenes to carry out gas phase catalytic oxidation or gas phase catalytic ammoxidation reactions to obtain the corresponding unsaturated acids or Attention has been focused on methods for producing unsaturated nitriles. For example, Mo-VN
An oxide catalyst containing b-Te is disclosed in JP-A-2-257, JP-A-5-148212, and JP-A-5-208.
No. 136, No. 5-279313, No. 6-228074, No. 6-285372, No. 7-289907, No. 8-573.
No. 19 and Japanese Patent Application Laid-Open No. 8-141401. Further, oxide catalysts containing Mo-V-Nb-Sb are disclosed in JP-A-10-28862 and JP-A-2001.
It is disclosed in Japanese Laid-Open Patent Publication No. 58827.

[0003]

A method for preparing an oxide catalyst containing at least one element selected from tellurium and antimony, molybdenum, vanadium and niobium, which is used in a gas phase catalytic ammoxidation reaction of alkane, comprising: At least one selected from tellurium or antimony
A method for preparing a catalyst in which an aqueous solution containing at least one compound, Mo compound, V compound, and Nb compound is dried and calcined is already known. Regarding calcination, in JP-A-5-208136 and JP-A-6-285372, the calcination temperature and the calcination time are taught, and there is no detailed description. The performance of the catalysts taught in these publications was inadequate. On the other hand, Japanese Patent Laid-Open No. 7-289907 discloses that a fluidized firing furnace or a rotary firing furnace may be used in the firing step, or the firing gas may be allowed to flow in a stationary state. The pre-stage calcination is defined as calcination of the catalyst precursor in the substantial absence of oxygen. Also, the latter firing is
It is defined that the calcined product contacted with oxygen is then calcined again in the substantial absence of oxygen.

In Example 1, about 50 ppm of oxygen was contained in the firing tube.
While flowing a nitrogen gas containing, the material is heated to 600 ° C. and pre-baked for 2 hours. It is described that after cooling to room temperature while flowing nitrogen gas, air at room temperature was allowed to flow for 30 minutes, and then post-calcining was performed at 600 ° C. for 2 hours while flowing nitrogen gas in the same manner as in the pre-calcination to obtain a catalyst. Even with the above method in which the first-stage firing and the second-stage firing have the same temperature, the performance was insufficient. Therefore, an object of the present invention is to improve the calcination method to supply a catalyst with a high selectivity of the target substance during the reaction. Further, the obtained oxide catalyst is used to subject an alkane to a gas phase catalytic oxidation or a gas phase catalytic ammoxidation reaction to produce a corresponding unsaturated acid or unsaturated nitrile with a high selectivity.

[0005]

In order to solve this problem, the present inventors have used at least one or more elements selected from tellurium and antimony used in a gas-phase catalytic oxidation reaction or a gas-phase catalytic ammoxidation reaction of alkanes. ,molybdenum,
As a result of investigating a method for preparing an oxide catalyst containing vanadium and niobium, a method of drying and calcining an aqueous solution containing at least one compound selected from tellurium or antimony, a Mo compound, a V compound, a Nb compound and silica sol is used. Therefore, it was found that excellent performance is exhibited by performing annealing at a temperature lower than the main firing temperature after the completion of the main firing, and the present invention has been completed.

That is, the present invention relates to [1] an oxide containing at least one element selected from tellurium and antimony used in a vapor-phase catalytic oxidation reaction or a vapor-phase catalytic ammoxidation reaction of alkane, molybdenum, vanadium and niobium. In the catalyst, at least one compound selected from tellurium and antimony,
A method for preparing an oxide catalyst, characterized in that an aqueous solution containing a Mo compound, a V compound and an Nb compound is dried and calcined, and after the main calcination of the calcination is completed, annealing is performed at a temperature lower than the main calcination temperature. [2] The method for preparing a catalyst according to the above [1], wherein the annealing is performed at a temperature lower than the main calcination temperature by 10 ° C. or more. [3] The method for preparing a catalyst according to any one of the above [1] or [2], wherein the annealing is performed at a temperature lower than the main calcination temperature by 50 ° C. or more. [4] The method for preparing a catalyst according to any one of the above [1] to [3], wherein the oxide catalyst is represented by the following general composition formula (1).

[Formula 2] Mo ₁ V _a Nb _b X _c O _n (1) (In the formula, the component X is at least one element selected from tellurium and antimony, and a, b, c and n are M
o represents the atomic ratio per atom, and a is 0.01 ≦ a ≦
1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and n is a number determined by the valence of the constituent metals. )

[5] The method for preparing a catalyst according to the above [4], wherein the component X is antimony. [6] The above-mentioned "1" to "5", wherein the niobium is made of a niobium-containing liquid having a dicarboxylic acid / niobium compound and a dicarboxylic acid / niobium molar ratio of 1 to 4.
The method for preparing the catalyst according to any one of 1. [7] The oxide catalyst comprises a catalyst-constituting element oxide represented by the general composition formula (1) and silica carrying the oxide, and the content ratio of the silica is the catalyst-constituting element. _{2 in} terms of SiO _{2 based on} the total weight of oxide and silica
The method for preparing an oxide catalyst according to any one of the above "1" to "6", which is supported on 0 to 60% by weight of silica.

[8] When the annealing has a temperature decrease at the annealing stage, the average temperature decrease rate is 2
C./min or less, the above “1” to
[9] A method for preparing a catalyst according to any one of [7], [9] for producing a corresponding unsaturated carboxylic acid or unsaturated nitrile by subjecting propane or isobutane to a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction. A method for producing an unsaturated acid or an unsaturated nitrile, which comprises using the catalyst prepared by the preparation method according to any one of the above "1" to "8". It is about.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The catalyst of the present invention is characterized by containing at least one element selected from tellurium and antimony, molybdenum, vanadium and niobium, and preferably represented by the following formula (1). Formula 3] Mo in _{1 V a Nb b X c O} n (1) ( wherein component X represents at least one element selected from tellurium or antimony, a, b, c, n is M
o represents the atomic ratio per atom, and a is 0.01 ≦ a ≦
1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and n is a number determined by the valence of the constituent metals. ) Further, the atomic ratios a, b, and c per Mo atom are 0.01 ≦ a ≦ 0.5, 0.01 ≦ b ≦ 0.5, and
It is preferable that 0.1 ≦ c ≦ 0.5. Furthermore,
0.2 ≦ a ≦ 0.3, 0.05 ≦ b ≦ 0.2, 0.2 ≦
c ≦ 0.3 is particularly preferable.

The oxide catalyst obtained by the production method of the present invention is preferably a silica-supported catalyst. When the oxide catalyst is a silica-supported catalyst, it has high mechanical strength and is suitable for a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction using a fluidized bed reactor. The content of the silica carrier is preferably 20 to 60% by weight, and more preferably 25 to 60% by weight in terms of SiO ₂ , with respect to the total weight of the silica-supported oxide catalyst composed of the oxide of the catalyst constituent elements and the silica carrier. 55% by weight. The raw materials of the component metals for producing the oxide catalyst of the present invention are not particularly limited, but the following compounds can be used, for example. Mo raw materials, ammonium heptamolybdate _{[(NH 4) 6 Mo 7 O} 24 · 4H 2 O ]
Can be preferably used. As a raw material of V, ammonium metavanadate [NH ₄ VO ₃ ] can be preferably used.

As the raw material of Nb, niobic acid, an inorganic acid salt of niobium and an organic acid salt of niobium can be used. Niobate is particularly good. Niobate is Nb ₂ O ₅ · nH ₂
It is represented by O and is also called niobium hydroxide or niobium oxide hydrate. Furthermore, the molar ratio of dicarboxylic acid / niobium is 1
~ 4, it is preferable to use a Nb raw material liquid having an ammonia / niobium molar ratio of 2 or less. By adjusting the molar ratio of dicarboxylic acid / niobium to the above value, the redox state of the metal constituting the catalyst can be adjusted and the catalyst performance can be made particularly excellent. Further, the dicarboxylic acid is preferably oxalic acid.

As a raw material of Sb, diantimony trioxide [Sb ₂ O ₃ ] is preferable. Further, in order to improve the dissolution rate of Sb in the aqueous solvent, it is preferable to use Sb ₂ O ₃ having an average particle size of 1 μm or less. As a raw material of Te, telluric acid [H ₆ TeO ₆ ] is preferable. As a raw material for the carrier silica, silica sol can be preferably used. The catalyst of the present invention can be prepared, for example, through the following three steps of raw material preparation, drying and calcination.

(Raw material mixing step) Using the above-mentioned raw materials,
A raw material preparation liquid is obtained. An example is shown below. Ammonium heptamolybdate, ammonium metavanadate, and diantimony trioxide are added to water and heated to 70 ° C. or higher to prepare a mixed solution (A). Telluric acid may be used instead of diantimony trioxide, or may be used simultaneously. At this time, the inside of the container may be a nitrogen atmosphere. Niobic acid and oxalic acid are heated and stirred in water to prepare a niobium-containing liquid (B ₀ ). As the containing liquid (B ₀ ), the containing liquid obtained by the method taught in JP-A No. 11-253801 can be used. Further, hydrogen peroxide and diantimony trioxide are added to at least a part of the contained liquid (B ₀ ) to prepare a niobium mixed liquid (B). At this time, H ₂ O ₂ / Nb (molar ratio) is preferably 0.5 to 20, particularly preferably 1 to 10, and Sb / Nb
The (molar ratio) is preferably 0 to 5, particularly preferably 0.01 to 2. Oxalic acid may be added to the mixed solution (B).

The mixed solution (A), the mixed solution (B) and the containing solution (B ₀ ) are suitably mixed in accordance with the desired composition to obtain a raw material preparation liquid. At this time, it usually becomes a slurry. When the ammoxidation catalyst of the present invention is a silica-supported catalyst, the raw material preparation liquid is prepared so as to contain silica sol.
Silica sol can be added as appropriate. Also, the component X
When antimony is used as above, it is preferable to add hydrogen peroxide to the mixed solution (A) or a solution containing the components of the mixed solution (A) in the process of preparation. At this time, H ₂ O ₂ / Sb
The (molar ratio) is preferably 0.01 to 5, and particularly preferably 1 to 3.
At this time, it is preferable to continue stirring at 30 ° C to 70 ° C for 30 minutes to 2 hours.

(Drying Step) The raw material mixed solution obtained in the raw material mixing step is dried by a spray drying method to obtain a dry powder. It is considered that the dry powder is mainly a mixture of raw materials. For the atomization in the spray drying method, a centrifugal system, a two-fluid nozzle system or a high pressure nozzle system can be adopted.
As the dry heat source, air heated by steam, an electric heater or the like can be used. The dryer inlet temperature of hot air is preferably 150 to 300 ° C.

(Calcination step) The oxide powder is obtained by subjecting the dry powder obtained in the drying step to calcination. It is considered that the oxide catalyst is a composite oxide containing at least one element selected from tellurium and antimony, molybdenum, vanadium, and niobium. The firing can be carried out in an atmosphere of an inert gas substantially free of oxygen such as nitrogen gas, argon gas and helium gas, preferably in a fluidized firing furnace or a rotary kiln while circulating an inert gas. .
If necessary, the inert gas may contain a trace amount of oxygen.

If the dry powder is allowed to stand and is baked, it will not be evenly baked and the performance will be deteriorated, and it may cause cracks and cracks. The amount of inert gas flowing is 1 kg of dry powder
Per 50 to 2000 Nl / Hr, preferably 50 to 1500 Nl / Hr. In the case of a continuous flow system using a rotary kiln, dry powder 1 kg / hr
Per 50 to 2000 Nl / Hr, preferably 50 to 1500 Nl / Hr. At this time, the inert gas and the dry powder may be counter-currently or co-currently flowed, but considering the gas component produced from the dry powder and the air mixed in a small amount together with the dry powder, countercurrent contact is preferable.

In the present invention, it is possible to carry out the pre-stage firing before the main firing. The first-stage firing is carried out under an inert gas flow at 250 ° C to 450 ° C, preferably 300 ° C to 400 ° C.
It means holding once at ℃. The holding time is preferably 30 minutes or more and 3 to 8 hours. Further, the pre-stage firing may be divided into several stages. In the case of continuous flow type firing, air may be mixed with the dry powder, but there is no problem if the inert gas is passed in a counterflow. The main calcination refers to holding at the highest temperature in the process of calcination to obtain a catalyst. The main firing is 450 ° C. to 700 ° C. in the absence of oxygen,
It can be preferably carried out at 550 ° C to 670 ° C. The firing time is 0.1 hours or more, preferably 0.5 to 2
0 hours, particularly preferably 1 to 8 hours. In the case of continuous flow type calcination, if the former calcination is finished and the main calcination is carried out again, air may be mixed with the powder calcinated in the former stage, but if the inert gas is circulated in countercurrent no problem.

Annealing refers to holding at a temperature lower than in the main firing after the main firing is completed. Usually, the temperature is lower than the main calcination temperature by 5 ° C or more, preferably lower than the main calcination temperature by 10 ° C or higher, more preferably lower than the main calcination temperature by 30 ° C or higher, and particularly preferably 50 ° C lower than the main calcination temperature. The above is performed at a low temperature. The holding time is 0.
5 hours or more, preferably 1 hour or more, more preferably 3
It is at least hours, particularly preferably at least 10 hours. The temperature decrease rate from the main calcination stage to the annealing stage is 0.01
~ 1000 ° C / min, preferably 0.05-100
C / min, more preferably 0.1-50 C / min,
Particularly preferably, it is 0.5 to 10 ° C./min.

Annealing is usually held at a constant temperature, but may vary. Further, the main firing temperature may be temporarily exceeded. On the other hand, when there is a temperature decrease in the annealing stage, the average temperature decrease rate is 5 ° C / min.
Or less, preferably 2 ° C./min or less, more preferably 1
C / min or less. The main calcination and the annealing may be continuously performed, or the main calcination may be once completed and then annealed again. The firing can be repeated. Further, the main firing and the annealing may be combined and repeated. In addition, after the main calcination is finished, it may be cooled to 300 ° C. or lower, and then the main calcined powder may be annealed after contact with air.

Annealing can be carried out in the absence of oxygen. If necessary, the inert gas may contain a trace amount of oxygen. In the case of continuous flow-type firing, when main firing is finished and annealing is performed again, air may be mixed with the finely fired powder, but it is a problem if the inert gas is passed in countercurrent. Absent. The alkane is subjected to a gas phase catalytic oxidation or a gas phase catalytic ammoxidation reaction in the presence of the oxide catalyst thus produced to produce a corresponding unsaturated acid or unsaturated nitrile.

The feed materials for the alkane and ammonia do not necessarily have to be highly pure, and may have a purity of 90% by weight or more. Air, oxygen-enriched air or pure oxygen can be used as the supply oxygen source. Further, helium, argon, carbon dioxide gas, steam, nitrogen or the like may be supplied as a diluent gas. The vapor phase catalytic oxidation of alkane can be performed under the following conditions. The molar ratio of oxygen supplied to the reaction to alkane is 0.1 to 6, preferably 0.5 to 4. The reaction temperature is 300 ° C to 500 ° C, preferably 35 ° C.
It is 0 ° C to 450 ° C. Reaction pressure is 5 × 10 ^{4 to} 5 × 1
It is 0 ⁵ Pa, preferably 1 × 10 ^{5 to} 3 × 10 ⁵ Pa.

The contact time is 0.1 to 10 (sec · g / c
c), preferably 0.5 to 5 (sec · g / cc). In the present invention, the contact time is determined by the following equation. Contact time (sec · g / cc) = (W / F) × 273 /
(273 + T) Here, W = filled catalyst amount (g) F = raw material mixed gas flow rate (Ncc / sec) in standard state (0 ° C., 1.013 × 10 ⁵ Pa) T = reaction temperature (° C.)

Gas phase catalytic ammoxidation of alkanes can be carried out under the following conditions. The molar ratio of oxygen supplied to the reaction to alkane is 0.1 to 6, preferably 0.5 to 4. The molar ratio of ammonia fed to the reaction to alkane is 0.3 to 1.5, preferably 0.6 to 1.2. The reaction temperature is 350 ° C to 500 ° C, preferably 380
C to 470C. Reaction pressure is 5 × 10 ^{4 to} 5 × 10 ⁵
Pa, preferably 1 × 10 ^{5 to} 3 × 10 ⁵ Pa. The contact time is 0.1 to 10 (sec · g / cc), preferably 0.5 to 5 (sec · g / cc). As a reaction system, a conventional system such as a fixed bed, a fluidized bed or a moving bed can be adopted, but a fluidized bed reactor which can easily remove reaction heat is preferable.
Further, the reaction of the present invention may be a single flow type or a recycle type.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The oxide catalyst obtained by the production method of the present invention will be described below with reference to a catalyst preparation example and an acrylonitrile production example by a gas phase catalytic ammoxidation reaction of propane. The results of the ammoxidation reaction of propane were evaluated based on the results of analysis of the reaction gas using the propane conversion rate and acrylonitrile selectivity defined by the following equations as indexes. Propane conversion rate (%) = (number of moles of reacted propane)
/ (Mol number of propane supplied) × 100 acrylonitrile selectivity (%) = (mol number of acrylonitrile produced) / (mol number of reacted propane) × 1
00

(Preparation of Niobium-Containing Liquid) JP-A-11-25
A niobium-containing liquid was prepared by the following method in accordance with Japanese Patent No. 3801. 11700 g of water was mixed with 1700 g of niobic acid containing 80.2% by weight as Nb ₂ O ₅ and 6560 g of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O]. The charged oxalic acid / niobium molar ratio was 5.08, and the charged niobium concentration was 0.525 (mol-Nb / Kg-liquid). This mixed solution was heated and stirred at 95 ° C. for 1 hour to obtain an aqueous solution in which niobium was dissolved. The aqueous solution was allowed to stand and cooled with ice, and then the solid was filtered off by suction filtration to obtain a uniform niobium-containing liquid. The oxalic acid / niobium molar ratio of this niobium-containing liquid was 2.40 according to the following analysis.

10 g of this niobium-containing liquid was precisely weighed in a crucible, dried overnight at 95 ° C., and then heat-treated at 600 ° C. for 1 hour.
0.853 g of Nb ₂ O ₅ was obtained. From this result, the niobium concentration was 0.642 (mol-Nb / Kg-solution).
3 g of this niobium-containing liquid was precisely weighed in a 300 ml glass beaker, 200 ml of hot water at about 80 ° C. was added, and subsequently 10 ml of 1: 1 sulfuric acid was added. While maintaining the solution temperature at 70 ° C. on a hot stirrer, with stirring, 1/4
Titrated with normal KMnO ₄ . The end point was a point where a faint light pink color due to KMnO ₄ continued for about 30 seconds or longer. The concentration of oxalic acid was calculated from the titer according to the following formula,
It was 1.540 (mol-oxalic acid / Kg). 2KMnO ₄ + 3H ₂ SO ₄ + 5H ₂ C ₂ O ₄ → K ₂ SO ₄ +2
MnSO ₄ + 10CO ₂ + 8H ₂ O The obtained niobium-containing solution was used as a niobium-containing solution (B ₀ ) in the following catalyst preparation.

[0029]

Example 1 (Preparation of catalyst) The composition formula was Mo ₁ V
Was prepared oxide catalyst represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2 as follows. Water 49
60 g of ammonium heptamolybdate [(NH ₄ ) ₆
Mo ₇ O ₂₄ · 4H ₂ O] was 904.0g, 137.8g of ammonium metavanadate [NH ₄ VO _3], adding 164.2g of diantimony trioxide [Sb ₂ O _3], a nitrogen gas into the container Circulate and stir at 90 ° C for 2 hours 30
Mixing liquid A-1 was obtained by heating for a minute. To 638.0 g of the niobium-containing liquid (B ₀ ), 92.9 g of hydrogen peroxide containing 30 wt% as H ₂ O ₂ was added, and 37.3 g of diantimony trioxide [Sb ₂ O ₃ ] was added little by little. In addition,
Mixing liquid B-1 was prepared by stirring and mixing at room temperature for 10 minutes. After cooling the obtained solution A-1 to 70 ° C., SiO
Silica sol 1960 containing 30.6 wt% as ₂
g, and then 235.1 g of hydrogen peroxide containing 30 wt% as H ₂ O ₂ was added, and stirring was continued at 45 ° C. for 1 hour. Next, the mixed liquid B-1 was added to obtain a raw material preparation liquid.

The obtained raw material preparation liquid was supplied to a centrifugal spray dryer and dried to obtain a fine spherical dry powder. The dryer inlet temperature was 210 ° C and the outlet temperature was 120 ° C. The above operation was repeated four times, and the dried powder was collected and fired. 480 g of the obtained dry powder was filled in a SUS baking tube having a diameter of 3 inches, and the temperature was raised to 370 ° C. in 1 hour while rotating the tube under a nitrogen gas flow of 5.0 NL / min, and at 370 ° C. It was pre-baked for 4 hours. Continuing,
The temperature was raised to 640 ° C. in 1 hour, and main firing was performed at 640 ° C. for 2 hours. Continuing, up to 370 ℃, approx. 1.2 ℃ / min
The temperature was lowered at a temperature lowering rate of, and the catalyst was obtained by annealing at 370 ° C. for 12 hours.

(Propane ammoxidation reaction) Inner diameter 25 m
m of Vycor glass fluidized bed type reaction tube was filled with 45 g of the obtained catalyst, and the reaction temperature was 440 ° C. and the reaction pressure was normal pressure. Propane: ammonia: oxygen: helium = 1: 1.
A mixed gas having a molar ratio of 0.6: 1.5: 5.6 is supplied,
The feed rate was adjusted so that the propane conversion was 50%. At this time, the acrylonitrile selectivity was 68.3%.

[0032]

[Comparative Example 1] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, except that no annealing in Example 1 was calcined in the same manner as in Example 1. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 66.4%.

[0033]

[Example 2] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, it was fired in the same manner as in Example 1 except that annealing at 470 ° C. instead of 370 ° C.. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 68.9%.

[0034]

[Example 3] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, it was fired in the same manner as in Example 1 except that annealing at 520 ° C. instead of 370 ° C.. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 69.1%.

[0035]

[Example 4] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, it was fired in the same manner as in Example 1 except that annealing at 570 ° C. instead of 370 ° C.. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 68.9%.

[0036]

[Example 5] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, except that 3 hours annealing at 520 ° C. instead of 12 hours at 370 ° C. as in Example 1 Baked. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 68.5%.

[0037]

[Example 6] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, except 24 hours of annealing at 520 ° C. instead of 12 hours at 370 ° C. as in Example 1 Baked. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 69.3%.

[0038]

[Example 7] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 1 represented by the _{0.23 Nb 0.08 Sb 0.27 O n /45.0wt%-SiO} 2, except that 48 hours annealing at 520 ° C. instead of 12 hours at 370 ° C. as in Example 1 Baked. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 69.2%.

[0039]

[Embodiment 8] (Preparation of catalyst) The composition formula is Mo ₁ V.
Was prepared oxide catalyst represented by the _{0.19 Nb 0.07 Sb 0.24 O n /45.0wt%-SiO} 2 as follows. Water 42
84 g of ammonium heptamolybdate [(NH ₄ ) ₆
Mo ₇ O ₂₄ · 4H ₂ O] was 945.1g, 119.0g of ammonium metavanadate [NH ₄ VO _3], adding 148.2g of diantimony trioxide [Sb ₂ O _3], a nitrogen gas into the container Circulate and stir at 90 ° C for 2 hours 30
Mixing liquid A-2 was obtained by heating for a minute.

583.6 g of the niobium-containing liquid (B ₀ ) was added with H ₂
85% hydrogen peroxide solution containing 30 wt% as O ₂ .
0 g was added, and diantimony trioxide [Sb was added little by little.
₂ O ₃ ] was added thereto, and the mixture was stirred and mixed at room temperature for 10 minutes to prepare a mixed solution B-2. The resulting solution A-2 was 7
After cooling to 0 ° C., 1960 g of silica sol containing 30.6 wt% as SiO ₂ was added, and 218.5 g of hydrogen peroxide solution containing 30 wt% as H ₂ O ₂ was further added and stirred at 45 ° C. for 1 hour. Continued. Next, mixed solution B-2
Was added to obtain a raw material preparation liquid. The obtained raw material preparation liquid,
The powder was supplied to a centrifugal spray dryer and dried to obtain a fine spherical dry powder. The dryer inlet temperature was 210 ° C and the outlet temperature was 120 ° C.

The above operation was repeated twice, and dry powder was collected and fired. Diameter 480g of the obtained dry powder 480g
5.0 NL / min filled in inch SUS firing tube
Under nitrogen gas flow, the temperature was raised to 370 ° C. in 1 hour while rotating the tube, and pre-baking was performed at 370 ° C. for 4 hours. Then, it heated up to 640 degreeC in 1 hour, and main-baked at 640 degreeC for 2 hours. Continue to about 1.2 ℃ / up to 520 ℃
The temperature was decreased at a temperature decrease rate of min, and annealing was performed at 520 ° C. for 12 hours to obtain a catalyst. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 69.3%.

[0042]

[Comparative Example 2] (Preparation of catalyst) The composition formula was Mo ₁ V.
With dry powder of Example 8 represented by _{0.19 Nb 0.07 Sb 0.24 O n /45.0wt%-SiO} 2, except that no annealing in Example 8 was calcined in the same manner as in Example 8. (Propane ammoxidation reaction) Using the obtained catalyst,
When the reaction was carried out in the same manner as in Example 1, the propane conversion was 50% and the acrylonitrile selectivity was 67.8%.

[0043]

INDUSTRIAL APPLICABILITY In a method for producing an oxide catalyst used for vapor phase catalytic oxidation or vapor phase catalytic ammoxidation of alkane, it is possible to prepare a catalyst having a high selectivity of a target substance at the time of reaction. Also,
The catalyst prepared according to the present invention can produce a target compound with high selectivity in a gas phase catalytic oxidation or a gas phase catalytic ammoxidation reaction of an alkane.

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Claims (9)

[Claims] 1. An aqueous solution containing at least one element selected from tellurium and antimony used for vapor-phase catalytic oxidation reaction or vapor-phase catalytic ammoxidation reaction of alkane, molybdenum, vanadium and niobium is dried and calcined,
A method for preparing an oxide catalyst, characterized in that annealing is performed at a temperature lower than the main calcination temperature after completion of the main calcination in the calcination. 2. The annealing is performed at a temperature higher than the firing temperature of 10 times.
The method for preparing a catalyst according to claim 1, wherein the method is carried out at a temperature lower than 0 ° C. 3. The annealing is performed at a temperature higher than the firing temperature of 50.
3. The method for preparing a catalyst according to claim 1 or 2, which is performed at a temperature lower than or equal to ℃. 4. The method for preparing a catalyst according to any one of claims 1 to 3, wherein the oxide catalyst is represented by the following general composition formula (1). Formula 1] Mo in _{1 V a Nb b X c O} n (1) ( wherein component X represents at least one element selected from tellurium or antimony, a, b, c, n is M
o represents the atomic ratio per atom, and a is 0.01 ≦ a ≦
1, b is 0.01 ≦ b ≦ 1, c is 0.01 ≦ c ≦ 1, and n is a number determined by the valence of the constituent metals. ) 5. The method for preparing a catalyst according to claim 4, wherein the component X is antimony. 6. The niobium contains a compound of dicarboxylic acid and niobium, and a niobium-containing liquid having a dicarboxylic acid / niobium molar ratio of 1 to 4 is used as a raw material.
6. The method for preparing the catalyst according to any one of 5 above. 7. The oxide composition according to the above general composition formula (1)
Which is composed of a catalyst-constituting element oxide represented by and silica supporting the same, and the content of the silica is SiO _{2 with} respect to the total weight of the catalyst-constituting element oxide and the silica.
The method for preparing an oxide catalyst according to claim 1, wherein the oxide catalyst is supported on 20 to 60% by weight of silica. 8. If the annealing has a temperature decrease in the annealing stage, the average temperature decrease rate is 2 ° C. /
It is below min, The preparation method of the oxide catalyst of any one of Claims 1-7 characterized by the above-mentioned. 9. The method according to claim 1, wherein propane or isobutane is subjected to a gas phase catalytic oxidation reaction or a gas phase catalytic ammoxidation reaction to produce a corresponding unsaturated carboxylic acid or unsaturated nitrile. A method for producing an unsaturated acid or an unsaturated nitrile, which comprises using the catalyst prepared by the preparation method.