JPH0857319A - Method for activating metal oxide catalyst - Google Patents

Abstract

PURPOSE: To further enhance the activity of a metal oxide catalyst contg. Mo and/or V for a vapor phase catalytic oxidation reaction of hydrocarbon through a simple operation by subjecting the catalyst to acid treatment. CONSTITUTION: A metal oxide catalyst contg. Mo and/or V for a vapor phase catalytic oxidation reaction of hydrocarbon is subjected to acid treatment. The atomic ratio of Mo to V in the metal oxide is preferably 0.1-2. The acid treatment is carried out by immersing the catalyst in an about 0.1-50wt.% aq. soln. of an inorg. or org. acid at room temp. to 90 deg.C. After the acid treatment, the catalyst is separated from the acid soln. by a method such as filtration or centrifugal separation. The separated catalyst is usually washed with water in some degree, dried and used as a catalyst. The dried catalyst may be heated at about 100-700 deg.C if necessary before use.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for activating a metal oxide catalyst containing molybdenum and / or vanadium for vapor phase catalytic oxidation of hydrocarbons.

[0002]

2. Description of the Related Art A metal oxide catalyst containing molybdenum and / or vanadium is used to produce various organic compounds by a gas phase catalytic oxidation reaction of hydrocarbons, particularly acrylic acid and maleic anhydride by a partial oxidation reaction of hydrocarbons. It is industrially important for producing an oxygen-containing organic compound such as an acid or a nitrile such as acrylonitrile or methacrylonitrile by a catalytic oxidation reaction of hydrocarbon and ammonia.

There are many known examples of metal oxide catalysts containing molybdenum and / or vanadium. For example, only a catalyst containing Mo as an essential element for the production of nitrile by catalytic oxidation reaction of hydrocarbon alkane and ammonia is used as a Mo-Bi-P-based catalyst (JP-A-48-1).
6887), V-Sb-W based oxides and Mo-Bi-C.
A catalyst obtained by mechanically mixing an e-W-based oxide (Japanese Patent Laid-Open No. Sho 6-62).
4-38051), Mo-Ag-Bi-V based catalyst (JP-A-3-58961), Mo-V-Sn-Bi-P based catalyst (JP-A-4-247060), Mo-Cr-Te.
-Based catalyst (US Pat. No. 5,171,876), Mo and Mn, C
Complex metal oxide catalysts composed of elements such as o
194347), Mo-V-Te based catalysts (JP-A-2-
No. 257, JP-A-5-148212, and JP-A-5-20.
No. 8136), Mo-Cr-Bi based catalyst (Japanese Patent Application No. 4-2).
65192, Japanese Patent Application No. 5-305361), Mo-T
Examples include e-based catalysts (Japanese Patent Application No. 5-309345).

As a catalyst containing vanadium as an essential component but not molybdenum, a V-Sb type catalyst (Japanese Patent Laid-Open No. 47-33783, Japanese Patent Publication No. 50-2301) is used.
No. 6, JP-A-1-268668, and JP-A-2-1806.
37), V-Sb-U-Ni-based catalyst (Japanese Patent Publication No. 47-1)
No. 4371), a V-Sb-WP catalyst (JP-A 2-9).
5439), V-W-Te based catalyst (Japanese Patent Application No. 5-189).
No. 18) and the like are exemplified.

As a method for preparing such a metal-group oxide,
The following two methods are mainly used. The first method is to dry a solution or slurry of water or an organic solvent containing the constituent elements of the metal oxide after preparation, or to adjust the pH of the solution.
To prepare a solid matter, or to carry out a method of recovering the solid matter after synthesizing the target metal oxide by heating and reacting the solution or slurry, and more generally, the obtained solid matter. Is a method of calcination to obtain a catalyst.

The second method is a method in which the oxides of the constituent metal elements of the metal oxide are pulverized and mixed in predetermined amounts, and the mixture is maintained at a high temperature and prepared by a solid-phase reaction.

[0007]

The activity of the catalyst depends largely on its composition. However, in spite of the fact that an excellent catalyst activity can be expected by optimizing the composition of the catalyst, it is often the case that sufficient catalyst activity cannot be expressed due to the preparation method and the like. In particular, in the case of a catalyst composed of the above-mentioned composite metal oxide, there is a problem that the preparation operation is complicated and the expected catalyst activity cannot be obtained with good reproducibility due to subtle changes in the preparation conditions.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention continued to study a method for producing a metal oxide catalyst containing molybdenum and / or vanadium while considering the above problems, and as a result, The present invention has been accomplished by discovering that the catalyst is activated by the acid treatment and that it exhibits excellent performance particularly in the selective gas-phase catalytic oxidation reaction of hydrocarbons.

That is, the gist of the present invention is to activate a metal oxide catalyst containing a molybdenum and / or vanadium-containing metal oxide catalyst for vapor-phase catalytic oxidation of hydrocarbons by acid treatment. In the way. Hereinafter, the present invention will be described in detail. The catalyst that can be activated in the present invention is not particularly limited as long as it is a metal oxide catalyst containing molybdenum and / or vanadium as described above, but preferably a metal oxide catalyst containing both molybdenum and vanadium as essential elements. Is. The atomic ratio (V / Mo) of molybdenum atoms to vanadium atoms in the metal oxide is usually 0.01 to 10, preferably 0.1 to 2. The metal oxide usually contains various optional metal components in order to enhance the performance as a catalyst, and the composition thereof is represented by the following empirical formula (1).

[0010]

Embedded image Mo _a V _b X _x O _n (1) (In the formula (1), X is Te, Nb, Ta, W, T.
i, Al, Zr, Cr, Mn, Fe, Ru, Co, R
h, Ni, Pd, Pt, Sb, Bi, B, In and Ce
Represents one or more elements selected from among the following, and when a = 1, b = 0.01-10 x = 0-2.0, and n is the oxidation state of another element. Determined by )

In the above metal oxide catalyst,
A catalyst containing tellurium as an essential component in addition to molybdenum and vanadium is particularly preferable. This molybdenum-vanadium-tellurium catalyst has excellent catalytic activity even in the partial oxidation reaction of alkane, which has low reactivity among hydrocarbons, and by appropriately selecting the conditions of the gas phase catalytic oxidation reaction, acrylonitrile or the like can be obtained. Production of nitriles
-257, JP-A 5-148212, and JP-A 5-2.
No. 08136), and production of α, β-unsaturated carboxylic acids such as acrylic acid (Japanese Patent Application Nos. 5-12616 and 5-1).
No. 53651) or the production of unsaturated carboxylic acid anhydrides such as maleic anhydride (Japanese Patent Application No. 5-17560), and the effect of activation by the acid treatment in the present invention can be obtained. It is especially remarkable. The composition of the molybdenum-vanadium-tellurium metal oxide is represented by the following empirical formula (2).

[0012]

Embedded image Mo _a V _b Te _c Y _y O _n (2) (In the formula (2), Y is Nb, Ta, W, Ti, A
1, Zr, Cr, Mn, Fe, Ru, Co, Rh, N
represents one or more elements selected from i, Pd, Pt, Sb, Bi, B, In and Ce, and when a = 1, b = 0.01 to 1.0, preferably 0.1-0.6, c = 0.01-1.0, preferably 0.05-0.4, y = 0.01-1.0, preferably 0.1-0.6 , And n is determined by the oxidation states of other elements. )

The metal oxides of the above formulas (1) and (2) can be used alone as catalysts, but Si, Al, Zr, Ti,
A mixture containing one or more oxides of alkaline earth metal oxides as a carrier component may be used as a catalyst. For example, the acid treatment of the present invention may be carried out in a mixture containing about 1 to 90% by weight of the carrier component. You may implement.

As the raw material of the metal oxide, molybdenum,
Carboxylic acid salts of vanadium and other optional metal components, carboxylic acid ammonium salts, ammonium halide salts,
Oxides, halides, hydrogen acids, acetylacetonates, alkoxides, halides and the like can be used. The method for preparing the metal oxide is not particularly limited, and as described above, a method of preparing from the solution or slurry of the raw material water of the metal oxide or the organic solvent, and the high temperature solid-phase reaction by mixing the raw material of the metal oxide. There are two main methods of preparation. However, from the viewpoint of obtaining a catalyst having more excellent activity, the former method, particularly the method of preparing an aqueous solution or slurry containing a compound of molybdenum and / or vanadium, followed by drying and calcining is preferable.

The present invention is characterized in that the above metal oxide catalyst containing molybdenum and / or vanadium is acid-treated to further activate the metal oxide catalyst. As the metal oxide catalyst for this acid treatment, not only the metal oxide newly prepared by the above-mentioned method but also the metal oxide whose catalytic activity has been already reduced in the reaction are also targeted. .

As the acid treatment method, the metal oxide catalyst is subjected to contact treatment with an acid solution. For example, the metal oxide catalyst is immersed in an aqueous solution of an inorganic acid or an organic acid of about 0.1 to 50% by weight at room temperature to 90 ° C. In some cases, the metal oxide catalyst may be crushed before the acid treatment. As the inorganic acid used for the acid treatment,
Hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and boric acid are effective.
Examples of the organic acid include an aliphatic carboxylic acid having 1 to 12 carbon atoms and an aromatic carboxylic acid. Particularly, an aliphatic polycarboxylic acid such as oxalic acid, citric acid, tartaric acid, malonic acid, succinic acid, and maleic acid is used. Basic acids are effective. These acids may be used alone or in a mixture of plural kinds.

Although the details of the reason why the catalyst is further activated by this acid treatment are not clear, the acid treatment changes the chemical state of the surface or the inside of the catalyst, or causes a side reaction which is not preferable for the reaction. It is presumed that the causative component is dissolved and removed, physical properties such as surface area are improved, or a surface advantageous for reaction activity and selectivity appears.

After the acid treatment, the metal oxide catalyst is separated from the acid solution by a method such as filtration or centrifugation. Then, the metal oxide catalyst is usually washed to some extent with water, then dried and used as a catalyst. Moreover, you may use as a catalyst, after heat-processing in about 100-700 degreeC as needed. The metal oxide catalyst containing molybdenum and / or vanadium activated by the above method is used for producing an organic compound by vapor-phase catalytic oxidation reaction of hydrocarbon. The gas-phase catalytic oxidation reaction of hydrocarbon in the present invention is a reaction of a hydrocarbon with oxygen in a gas-phase catalytic reaction, and includes a reaction in which ammonia or water vapor is present in the reaction system in addition to oxygen. It is applied to the production of various organic compounds such as oxygen-containing organic compounds, dehydrogenated organic compounds and nitriles. The conditions of use of the activated catalyst in the present invention may be the same as the reaction conditions already known in each catalyst system, and compared with the case of using a non-activated catalyst, the target production The product can be obtained with higher selectivity and higher yield.

The hydrocarbon as the reaction raw material has 3 to 10 carbon atoms.
Examples thereof include about 8 alkanes or alkenes, aromatic hydrocarbons having about 6 to 12 carbon atoms, and the like. As an example of the reaction, production of nitrile by gas phase catalytic oxidation reaction of alkene or alkane and ammonia (for example, production of acrylonitrile from propylene or propane and ammonia,
Production of acrylonitrile from isobutene or isobutane and ammonia) Production of unsaturated aldehydes and unsaturated carboxylic acids by partial oxidation reaction of alkanes or alkenes (for example, production of acrolein or acrylic acid from propane or propylene, methacrolein from isobutane or isobutene) Rhein, production of methacrylic acid), oxidative dehydrogenation of saturated carboxylic acid (eg, production of methacrylic acid from isobutyric acid), oxidative dehydrogenation of hydrocarbon (eg, production of butadiene from butene), various hydrocarbons Production of an acid anhydride by a partial oxidation reaction (for example, production of phthalic anhydride from naphthalene or xylene, production of maleic anhydride from butane or butene), and the like.

Further, the conditions for the vapor phase catalytic oxidation reaction of hydrocarbons in the molybdenum-vanadium-tellurium catalyst represented by the above formula (2), which has a particularly remarkable effect in the activation method of the present invention, will be described. The catalyst is usually 500 ° C. in comparison with other metal oxide catalysts for gas phase catalytic oxidation reaction.
It has the characteristic that the partial oxidation activity of alkane is high even at the following relatively low temperatures. In the gas phase catalytic oxidation reaction using the catalyst, the reaction temperature is 300 to 500 ° C., preferably about 350 to 450 ° C., and the gas space velocity SV in the gas phase reaction is 100 to 10,000 hr ⁻¹ , preferably 300 to It is in the range of 6000 hr ^-1 , and the reaction can usually be carried out under atmospheric pressure, but it may be under elevated pressure or reduced pressure. . Further, as a diluent gas for adjusting the space velocity and the oxygen partial pressure, an inert gas such as nitrogen, argon or helium can be used. Although a fixed bed, a fluidized bed, or the like can be adopted as the reaction system, the reaction temperature is easier to control in the fluidized bed system because it is an exothermic reaction.

This molybdenum-vanadium-tellurium catalyst is effective for the production of nitrile by the vapor-phase catalytic oxidation reaction of alkane and ammonia, especially for the production of acrylonitrile from propane. In this reaction, the ratio of oxygen supplied to the reaction system is important with respect to the selectivity of acrylonitrile to be produced, and oxygen is preferably 0.2 to propane.
It shows a high acrylonitrile selectivity in the range of up to 4 molar times. Further, the ratio of ammonia to be supplied to the reaction is particularly preferably in the range of 0.5 to 3 times the molar amount of propane.

By using the same molybdenum-vanadium-tellurium catalyst, a vapor phase catalytic oxidation reaction of propane can be performed to obtain acrylic acid in high yield. Although propane and an oxygen-containing gas are used as the reaction raw material gas, it is preferable to use steam, and the steam can further improve the selectivity of acrylic acid. The molar fraction of the raw material gas is preferably (propane) :( oxygen) :( steam) = 1: (1-5) :( 5-40).

[0023]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. The propane conversion (%), acrylonitrile selectivity (%), and acrylonitrile yield (%) in the following Examples and Comparative Examples are shown by the following formulas, respectively.

[0024]

## EQU1 ## Propane conversion (%) = (moles of consumed propane / moles of propane fed) × 100 Acrylonitrile selectivity (%) = (moles of acrylonitrile produced / moles of consumed propane) × 100 Acrylonitrile yield (%) = (mol acrylonitrile produced / mol propane fed) × 100

[0025] was prepared in Comparative Example 1 empirical formula _{Mo 1 V 0.3 Te 0.23 Nb 0.18} O n and a mixture of SiO ₂ (weight ratio 70:30) was as follows. 22.7 L of warm water, 5.5 ammonium paramolybdate salt
2 kg, ammonium metavanadate 1.10 kg,
Telluric acid (1.65 kg) was dissolved to prepare a uniform aqueous solution. Furthermore, silica sol with silica content of 20% by weight 15k
g and 8.55 kg of an ammonium niobium oxalate aqueous solution having a niobium concentration of 0.659 mol / kg were mixed,
A slurry was prepared. This slurry was supplied to a spray dryer at a rate of about 120 ml / min to remove water while supplying heated air and dried. At this time, the temperature of the central part of the spray dryer was about 160 ° C. After heat-treating the dried product at about 300 ° C. until the smell of ammonia disappears,
Firing was performed at 600 ° C. for 2 hours in a nitrogen stream.

Metal oxide 0.7 prepared as described above
g into a reactor, reaction temperature 410 ° C., space velocity SV
Was fixed at 880 hr ^-1 , and gas was supplied at a molar ratio of propane: ammonia: air = 1: 1.2: 15 to carry out a gas phase catalytic oxidation reaction. The reaction results are shown in Table 1.

Example 1 100 g of an aqueous 10 wt% oxalic acid solution was heated to 50 ° C.,
Here, Mo1V0.3Te0.23 prepared in Comparative Example 1
Mixture of Nb0.18On and SiO2 (weight ratio 70: 3
0) Add 10 g and stir at 50 ° C. for 1.5
Held for hours. After allowing to cool to room temperature, solids were separated by filtration from the liquid. Transfer this solid to another container and add 1 part of deionized water.
00 ml was added, and the mixture was stirred at room temperature for 5 minutes and filtered. Furthermore, this washing operation was repeated 3 times. After drying at room temperature, it was baked at 600 ° C. for 2 hours in a nitrogen stream. Using the metal oxide treated as above, propane and ammonia were subjected to a gas phase catalytic oxidation reaction under the same conditions as in Comparative Example 1. The reaction results are shown in Table 1.

Comparative Example 2  Empirical formula Mo₁V_0.24Te_0.23Nb_0.12O_nAnd SiO₂A mixture of
Compound (weight ratio 50:50) was prepared as follows. Hot water
3019 ml of ammonium paramolybdate 80
8.6 g, ammonium metavanadate 128.6
g and telluric acid 241.9 g are dissolved to prepare a uniform aqueous solution.
Made. Furthermore, silica sol 5 having a silica content of 20 wt%
000 g, and the concentration of niobium is 0.435 mol / k
1268 g of an aqueous solution of ammonium niobium oxalate is mixed.
And a slurry was prepared. This slurry is about 120m
Feed the spray dryer at a rate of 1 / min to heat the air.
Water was removed while being supplied, and the product was dried. At this time, spray drying
The temperature in the center of the machine was about 160 ° C.

The dried product was heat-treated at about 300 ° C. until the smell of ammonia disappeared, and then the dried product was heated at 600 ° C. in a nitrogen stream for 2 hours.
Burned for hours. Metal oxide prepared as described above 1.
0 g was charged into a reactor, reaction temperature was 410 ° C., space velocity S
V was fixed at 440 hr ^-1 , and propane: ammonia:
Gas was supplied at a molar ratio of air = 1: 1.2: 15 to carry out a gas phase catalytic oxidation reaction. The reaction results are shown in Table 1.

Example 2 100 g of a 5 wt% oxalic acid aqueous solution was heated to 50 ° C., and the Mo ₁ V _0.24 Te _0.23 Nb _0.12 prepared in Comparative Example 2 was added thereto.
O _n and a mixture of SiO ₂ (weight ratio 50:50) 10 g was added, while stirring, and held for 1.5 hours to 50 ° C..
After allowing to cool to room temperature, solids were separated by filtration from the liquid. The solid was transferred to another container, 100 ml of deionized water was added, the mixture was stirred at room temperature for 5 minutes, and filtered. Furthermore, this washing operation was repeated 3 times. After drying at room temperature, it was baked at 600 ° C. for 2 hours in a nitrogen stream. Using the metal oxide treated as described above, propane and ammonia were subjected to a gas phase catalytic oxidation reaction under the same conditions as in Comparative Example 1. The reaction results are shown in Table 1.

Example 3 Treatment with an oxalic acid aqueous solution was carried out in the same manner as in Example 2, but propane was treated under the same conditions as in Example 2 without firing in a nitrogen stream after the treatment and drying. Gas-phase catalytic oxidation reaction with ammonia was carried out. The reaction results are shown in Table 1. Example 4 The same treatment as in Example 2 was carried out except that the temperature of the oxalic acid aqueous solution in Example 2 was changed to 80 ° C., and the vapor phase catalytic oxidation reaction of propane and ammonia was carried out under the same conditions as in Example 2. It was The reaction results are shown in Table 1.

Example 5 100 g of a 5 wt% citric acid aqueous solution was heated to 70 ° C., 10 g of the metal oxide prepared in Comparative Example 2 was added thereto, and the mixture was kept at 70 ° C. for 1.5 hours while stirring. . After allowing to cool to room temperature, solids were separated by filtration from the liquid. The solid was transferred to another container, 100 ml of deionized water was added, the mixture was stirred at room temperature for 5 minutes, and filtered. In addition, this washing operation
Repeated times. After drying at room temperature, 600 in a nitrogen stream
Calcination was carried out for 2 hours. Using the metal oxide treated as described above, propane and ammonia were subjected to a vapor phase catalytic oxidation reaction under the same conditions as in Example 2. The reaction results are shown in Table 1.

Example 6 To 100 g of a 5 wt% tartaric acid aqueous solution, 10 g of the metal oxide prepared in Comparative Example 2 was added, and the mixture was stirred at room temperature for 2 hours.
Hold for 0 hours. After allowing to cool to room temperature, solids were separated by filtration from the liquid. The solid was transferred to another container, 100 ml of deionized water was added, the mixture was stirred at room temperature for 5 minutes, and filtered. Furthermore, this washing operation was repeated 3 times. After drying at room temperature, it was baked at 600 ° C. for 2 hours in a nitrogen stream. Using the metal oxide treated as described above, propane and ammonia were subjected to a vapor phase catalytic oxidation reaction under the same conditions as in Example 2. The reaction results are shown in Table 1. Example 7 5 wt% instead of the 5 wt% aqueous citric acid solution of Example 5
The same treatment as in Example 5 was carried out except that an aqueous hydrochloric acid solution was used, and a vapor phase catalytic oxidation reaction of propane and ammonia was performed under the same conditions as in Example 5. The reaction results are shown in Table 1.

Example 8 5 wt% instead of the 5 wt% citric acid aqueous solution of Example 5
The same treatment as in Example 5 was performed except that the phosphoric acid aqueous solution was used, and the vapor phase catalytic oxidation reaction of propane and ammonia was performed under the same conditions as in Example 5. The reaction results are shown in Table 1. Comparative Example 3 Instead of the 5 wt% oxalic acid aqueous solution of Example 2, warm water 10 was used.
The same treatment as in Example 2 was carried out except that 0 g was used, and the vapor phase catalytic oxidation reaction of propane and ammonia was carried out under the same conditions as in Example 2. The reaction results are shown in Table 1.

[0035] was prepared in Comparative Example 4 the empirical formula _{Mo 1 V 0.3 Te 0.23 Nb 0.12} O n and a mixture of SiO ₂ (weight ratio 50:50) as follows. Hot water 1
To 6.3 L, ammonium paramolybdate 3.94
kg, ammonium metavanadate 0.784 kg,
Telluric acid (1.18 kg) was dissolved to prepare a uniform aqueous solution. Furthermore, silica sol having a silica content of 20 wt% 25k
g, and 6.16 kg of an aqueous solution of ammonium niobium oxalate having a niobium concentration of 0.435 mol / kg were mixed to prepare a slurry. About 120 ml of this slurry
It was supplied to a spray dryer at a rate of 1 / min to remove moisture while supplying heated air and dried. At this time, the temperature of the central part of the spray dryer was about 160 ° C.

The dried product was heat-treated at about 300 ° C. until the smell of ammonia disappeared, and then the dried product was heated at 600 ° C. in a nitrogen stream for 2 hours.
Burned for hours. Metal oxide prepared as described above 1.
0 g was charged into a reactor, reaction temperature was 410 ° C., space velocity S
V was fixed at 440 hr ^-1 , and propane: ammonia:
Gas was supplied at a molar ratio of air = 1: 1.2: 15 to carry out a gas phase catalytic oxidation reaction. The reaction results are shown in Table 1.

Example 9 100 g of a 5 wt% oxalic acid aqueous solution was heated to 65 ° C., and the Mo ₁ V _0.3 Te _0.23 Nb _0.12 O prepared in Comparative Example 4 was added thereto.
10 g of a mixture of _n and SiO ₂ (weight ratio 50:50) was added, and the mixture was kept at 65 ° C. for 1.5 hours while stirring.
After allowing to cool to room temperature, solids were separated by filtration from the liquid. The solid was transferred to another container, 100 ml of deionized water was added, the mixture was stirred at room temperature for 5 minutes, and filtered. Furthermore, this washing operation was repeated 3 times. After drying at room temperature, it was baked at 600 ° C. for 2 hours in a nitrogen stream. Using the metal oxide treated as described above, propane and ammonia were subjected to a gas phase catalytic oxidation reaction under the same conditions as in Comparative Example 4. The reaction results are shown in Table 1.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION According to the present invention, the metal oxide catalyst effective for the gas phase catalytic oxidation reaction of hydrocarbons can be further activated, and therefore acrylonitrile useful as an industrial raw material,
Acrylic acid, maleic anhydride, etc. can be produced in high yield.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Reference number within the agency FI Technical display location B01J 23/652 23/88 Z 27/057 Z 38/60 C07C 253/24 255/08 9357-4H // C07B 61/00 300 (72) Inventor Toru Ogoshi 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Co., Ltd.

Claims (6)

[Claims] 1. A method for activating a metal oxide catalyst, which comprises subjecting a metal oxide catalyst containing molybdenum and / or vanadium for a gas phase catalytic oxidation reaction of hydrocarbon to an acid treatment. 2. The metal oxide catalyst containing molybdenum and / or vanadium is obtained by drying and calcining an aqueous solution or slurry containing a compound of molybdenum and / or vanadium. 1. A method for activating a metal oxide catalyst according to 1. 3. The method for activating a metal oxide catalyst according to claim 1, wherein the acid treatment is performed with an organic acid. 4. The method for activating a metal oxide catalyst according to claim 1, wherein the metal oxide catalyst is represented by the following empirical formula (1). Embedded image Mo _a V _b X _x O _n (1) (In the formula (1), X is Te, Nb, Ta, W, T.
i, Al, Zr, Cr, Mn, Fe, Ru, Co, R
h, Ni, Pd, Pt, Sb, Bi, B, In and Ce
Represents one or more elements selected from among the following, and when a = 1, b = 0.01-10 x = 0-2.0, and n is the oxidation state of another element. Determined by ) 5. The method for activating a metal oxide catalyst according to claim 1, wherein the metal oxide catalyst is represented by the following empirical formula (2). Embedded image Mo _a V _b Te _c Y _y O _n (2) (In the formula (2), Y is Nb, Ta, W, Ti, A
1, Zr, Cr, Mn, Fe, Ru, Co, Rh, N
Represents one or more elements selected from i, Pd, Pt, Sb, Bi, B, In and Ce, and when a = 1, b = 0.01 to 1.0 c = 0 0.01 to 1.0 y = 0.01 to 1.0, and n is determined by the oxidation states of other elements. ) 6. The metal according to claim 1, wherein the metal oxide catalyst is a catalyst for producing acrylonitrile from propane by a gas phase catalytic oxidation reaction in the presence of ammonia. Method for activating oxide catalyst.