WO2005089943A1

WO2005089943A1 - Process for producing composite oxide catalyst

Info

Publication number: WO2005089943A1
Application number: PCT/JP2004/014379
Authority: WO
Inventors: Yoshimune Abe; Isao Teshigahara
Original assignee: Mitsubishi Chemical Corporation
Priority date: 2004-03-23
Filing date: 2004-09-30
Publication date: 2005-09-29
Also published as: CN1697702A; CN100430141C

Abstract

A process for producing a composite oxide catalyst with which an unsaturated aldehyde is catalytically oxidized in a vapor phase with a gas containing molecular oxygen to stably produce the corresponding unsaturated carboxylic acid in high yield over long. The process, which is for producing a composite oxide catalyst represented by the formula Mo12VaXbCucYdCeSifOg (wherein X represents at least one element selected between niobium and tungsten; Y represents at least one element selected from the group consisting of antimony, magnesium, calcium, strontium, barium, and zinc; and a, b, c, d, e, f, and g, which indicate the atomic proportions of the respective elements, are as follows: 0<a≤12, 0≤b≤12, 0<c≤12, 0≤d≤8, 0≤e≤1,000, and 0≤f≤1,000 when the number of molybdenum atoms is 12, and g is the number of oxygen atoms satisfying the oxidized states of the constituent elements excluding silicon and carbon in the formula), comprises uniting source compounds for the respective elements in an aqueous medium system in the presence of an organic acid, drying the resultant aqueous solution or dispersion of the united matter to prepare a powder, molding the powder, and burning the molding.

Description

Specification

Method for producing composite oxide catalyst

Technical field

The present invention provides a composite oxide catalyst for producing a corresponding unsaturated carboxylic acid stably over a long period of time and in a high yield by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas. And a method for producing the same.

Background art

[0002] Conventionally, various catalysts have been proposed for producing unsaturated carboxylic acids such as acrylic acid and methacrylic acid by subjecting unsaturated aldehydes such as acrolein and methacrolein to gas-phase catalytic oxidation with molecular oxygen. I have. From the viewpoint of effective use of unsaturated aldehyde raw materials produced by Olefinka and rationalization of the process in the reaction, these catalysts have a high conversion rate of unsaturated aldehydes and selectivity of unsaturated carboxylic acids as target products. Desired. In this case, for example, the production scale for producing acrylic acid by reacting acrolein is usually carried out on a scale of 3 million tons Z years, so that even if the above conversion and selectivity are improved by 0.1%, it is obtained. The amount of acrylic acid increases significantly at the level of hundreds and thousands of tons. Therefore, the improvement of the catalyst performance such as the conversion and the selectivity will contribute to the effective use of resources and the rationalization of the process, even if it is a slight improvement.

[0003] Conventionally, various proposals have been made with the aim of improving the catalyst performance such as the raw material conversion and selectivity of these reactions. The present applicant has also proposed, for example, Patent Document 1 and the like as a composite oxide catalyst having excellent performance for that purpose. Patent Document 1 discloses that Mo Nb V Cu Si

12 a b o d

C X Y Z O (where X is an alkali metal and Tl force at least one selected element is e f g h 1

Y represents at least one element selected from Mg, Ca, Sr, Ba and Zn, and Z represents W, Ce, Sn, Cr, Mn, Fe, Co, Y, Nd, Sm, Ge and 1 Represents at least one element selected from a, b, c, d, e, f, and g represent the atomic ratio of each element.For molybdenum atom 12, a is 0 <a≤12, 0 <b≤10, 0 <c≤8, 0 <d≤1000, 0 <e≤1000, 0≤f≤2, 0≤g <5, 0≤h <5, i is a number determined by the degree of oxidation of each of the above components excluding Si and C Is a catalyst having a composition having the following formula: [0004] Further, Patent Document 2 discloses that a catalyst used in the same reaction as that applied to an applicant separate from the present applicant has a formula: Mo V Sb ABC (where A is composed of Nb and Ta Selected from the group

12 g h i i k

B is Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Cr, W, Mn, Fe, Ru, Co, Ni or P, and C is Ag , Zn, Ti, Sn, Pb, Cu, As or Se. g and h are 0.01-1.5, respectively, and force hZg = 0.3-1.0, i is 0.001-3.0, J is 0001-0.1, and 0- 0.05) is disclosed.

[0005] However, these conventional composite oxide catalysts exhibit excellent performances, respectively, but have higher performances. [1] Improvement in the conversion of raw material unsaturated aldehydes and unsaturated carboxylic acid selectivity. Is desired.

Patent Document 1: JP 2003-200055

Patent Document 2: JP-A-2000-317309

Disclosure of the invention

Problems to be solved by the invention

[0006] The present invention provides a method for producing an unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas to produce a high conversion of the raw material unsaturated aldehyde and a high unsaturated carboxylic acid. A novel method for producing a composite oxide catalyst that provides selectivity and exhibits stable performance over a long period of time.

Means for solving the problem

[0007] The inventor of the present invention has conducted intensive studies to achieve the above object. As a result, a group force consisting of Mo, V, X (Nb and W) which is the same as or similar to Patent Documents 1 and 2 described above was also selected. A composite oxide catalyst containing at least one element), Y (at least one element selected from the group consisting of Sb, Mg, Ca, Sr, Ba and Zn), Cu, Si and C However, when producing this catalyst, the starting compound of each element is integrated in an aqueous medium in the presence of an organic acid, and the obtained integrated product is dried, molded, and calcined to obtain the catalyst performance. It has also been found that the conversion of unsaturated aldehydes is improved, and in particular, the selectivity of the target unsaturated carboxylic acid is improved.

[0008] In the production of the composite oxide catalyst of the present invention, means for integrally integrating a source compound of each element in an aqueous medium in the presence of an organic acid is disclosed in Patent Documents 1 and 2. It is different from the usual method as shown. The organic acid itself is not used in the production process of the catalyst of Patent Document 1. Patent Document 2 uses oxalic acid, which is an organic acid used in the present invention in the catalyst manufacturing process, but has a different composition from the catalyst manufactured by the present invention, which contains Cu as an essential component. In Patent Document 2, such oxalic acid is used to react with niobic acid to form a complex to dissolve water-insoluble niobic acid. It should not be used to integrate the source compound of each component in an aqueous medium.

[0009] In the production method of the present invention, when the source compound of each component of the catalyst is integrated in an aqueous medium in the presence of an organic acid, the organic acid coordinates to each component element constituting the catalyst. As a result, the bonding between the component elements is suppressed, and the characteristics are improved by changing the structure, redox state, and dispersion state of the catalyst component on the carrier of the finally obtained composite oxide catalyst. Things.

The present invention is characterized by the following points.

Formula (1): Mo V X Cu Y C SiO (where Mo is molybdenum, V is vanadium, Cu is copper

12 a b c d e f g

, C is carbon, Si is silicon, O is oxygen, X is at least one element selected from Nb and W, Y is a group consisting of Sb, Mg, Ca, Sr, Ba and Zn At least one element selected from a, b, c, d, e, f and g indicate the atomic ratio of each element, and 0 <a≤12, 0≤b≤12, 0 <c≤12, 0≤d≤8, 0≤e≤ 1000, 0≤f≤1000, and g is a number determined by the number of oxygen atoms necessary to satisfy the acid state of other elements except Si and c in each of the above components). In the manufacture of the composite oxide catalyst represented by the formula, the source compound of each component element is integrated in the presence of an organic acid, and the resulting aqueous solution or dispersion of the integrated product is dried to form a powder. A method for producing a composite oxide catalyst, comprising: preparing a powder of the above, and firing a molded product obtained by molding the powder.

(2) The method for producing a composite oxide catalyst according to the above (1), wherein the organic acid is present in an amount of 0.001 to 1 mol per mol of molybdenum.

(3) The method for producing a composite oxide catalyst according to the above (1) or (2), wherein the organic acid is at least one selected from citric acid, oxalic acid, and malic acid.

(4) The composite oxide catalyst converts the unsaturated aldehyde into a gas phase catalytic acid with a molecular oxygen-containing gas. The method for producing a composite oxide catalyst according to any one of the above (1) to (3), which is a catalyst for producing a corresponding unsaturated carboxylic acid by conversion into a catalyst.

(5) Gas-phase catalytic oxidation of acrolein with a molecular oxygen-containing gas in the presence of the composite oxide catalyst produced by the production method according to any one of (1) to (4) above, and the corresponding atalyl A method for producing an acid.

The invention's effect

According to the present invention, when an unsaturated aldehyde is produced by gas phase catalytic oxidation of an unsaturated aldehyde with a molecular oxygen-containing gas to produce an unsaturated carboxylic acid! Accordingly, there is provided a method for producing a composite oxide catalyst which provides a high conversion rate of a raw material unsaturated aldehyde and a high selectivity of an unsaturated carboxylic acid, and shows stable performance over a long period of time.

[0012] In particular, the conversion rate of acrolein per catalyst unit is improved, the selectivity of acrylic acid for the catalyst is improved, and the activity of V-complex oxidation for efficiently performing the gas phase catalytic oxidation reaction of acrolein is improved. Product catalyst can be manufactured.

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The composite oxide catalyst produced by the present invention is represented by the above formula. In the above formula, X, Y, a, b, c, d, e, f, and g are respectively as described above. Especially preferred are 0.l≤a≤6, 0.l≤b≤6, 0.l≤c≤6, 0.01≤d≤6, 5≤e≤500, 5≤f≤ 500.

[0014] Such a composite oxide catalyst of the present invention is produced by integrating a source compound of each catalyst component constituting the above formula in the presence of an organic acid. Here, the term "source compound of each catalyst component" means that the source compound of each catalyst component element is mixed in an aqueous medium system, preferably an aqueous solution or an aqueous dispersion, and optionally mixed. Aging treatment. (A) a method of collectively mixing the above-mentioned source compounds, (mouth) a method of collectively mixing the above-mentioned source compounds and further aging treatment, (c) a method of each of the above-mentioned source compounds (2) Stepwise mixing of each of the above source compounds · Repeating the aging treatment and Z or vigorous (a) Method combining (1) It is included in the integration of the source compound of each catalyst component element in the aqueous medium system. [0015] As described in the Chemical Dictionary (Kyoritsu Shuppan), the term "aging" refers to "treatment of industrial raw materials or semi-finished products under specific conditions such as fixed time and constant temperature." Operation to obtain and increase the required physical properties and chemical properties or to advance a predetermined reaction ”. In the present invention, the above-mentioned constant time preferably refers to a range of 1 minute to 24 hours, and the constant temperature preferably ranges from room temperature to 200 ° C. In addition, in the above integration, not only the source compound of each element constituting the catalyst but also a carrier material such as alumina, silica, and a heat-resistant oxide may be included as a target of such an integration. it can.

As the organic acid to be present when the source compounds of the respective elements constituting the powerful catalyst of the present invention are integrated, an organic acid having a property of being easily soluble in water can be used. Among them, citric acid, oxalic acid and malic acid are preferably at least one selected from the group. The amount of the organic acid is preferably 0.001 to 1 mol, more preferably 0.01 to 0.5 mol, per mol of mol. When the amount of the organic acid is less than 0.001 mol, no improvement in the catalytic performance is observed.On the contrary, when the amount of the organic acid is more than 1 mol, the catalytic performance deteriorates, which is preferable. Absent.

[0017] The source compound of each component of the composite oxide catalyst of the present invention is not particularly limited as long as it is water-soluble or hardly water-soluble, as long as it is a compound that becomes an oxidized product by firing, excluding the silicon carbide compound. Absent. Specific examples of the compound include halides, sulfates, nitrates, ammonium salts, oxides, carboxylate salts, ammonium carboxylate salts, ammonium halide salts, ammonium hydroxide salts, hydrogen acids, and acetyl acetonate of each component. And alkoxides. Specific examples of the raw material compounds of silicon and carbon include green silicon carbide and black silicon carbide, and silicon carbide is preferably a fine powder. As the raw material compound, a compound containing each component alone may be used, or a raw material compound containing two or more components may be used.

[0018] Preferred specific embodiments of the production method of the present invention will be described in order. First, an aqueous solution or aqueous dispersion of the above-mentioned source compound of the catalyst constituent element component is prepared. In the present invention, these aqueous solutions or aqueous dispersions are also referred to as slurry solutions. The slurry solution can be obtained by uniformly mixing the source compound of each component with water. The use ratio of the raw material compound of each component in the slurry solution is determined by the above formula based on the atomic ratio of each catalyst constituent element. May be in the range shown in FIG. The organic acid is preferably added at the stage after dissolving Mo and V, even if the organic acid can be added after or during the preparation of the slurry solution.

[0019] The amount of water in the slurry solution is not particularly limited as long as the raw material compounds of the respective components can be completely dissolved or uniformly dispersed. However, the subsequent drying method, drying temperature, and drying are performed. What is necessary is just to determine suitably considering drying conditions, such as time. The amount of water is usually 100 to 2,000 parts by weight based on 100 parts by weight of the total amount of the starting material. If the amount of water is less than the above-mentioned predetermined amount, the compound may not be completely dissolved or may not be mixed uniformly. Also, if the amount of water is large, there is a risk that the energy cost during the heat treatment will increase. Through mixing and stirring in the preparation process of the slurry solution, the integration of each element constituting the catalyst proceeds. However, in order to further promote the integration, the temperature is preferably room temperature to 200 ° C., particularly preferably 70 to 200 ° C. The aging treatment is preferably performed at 100 ° C, preferably for 1 minute to 24 hours, particularly preferably for 30 minutes to 6 hours.

Next, the aqueous solution or the aqueous dispersion is dried to form a powder. The drying is not particularly limited as long as the aqueous solution or the aqueous dispersion can be sufficiently dried and a powder can be obtained, and examples thereof include drum drying, freeze drying, and spray drying. Spray drying is a method that can be preferably applied to the present invention because it can be dried to a homogeneous powder state in a short time in an aqueous solution or aqueous dispersion.

[0021] The drying temperature varies depending on the concentration of the slurry solution and the like, and is usually 90 to 200 ° C, preferably 130 to 170 ° C. The particle size of the powder obtained by vigorous drying is preferably 10-200 / zm. For this reason, the powder can optionally be dried and then powdered.

[0022] The powder obtained by the drying is molded as follows. The molding method is not particularly limited. Preferably, the molding is performed using a binder. Preferred binders are selected from silica, graphite and crystalline cellulose as well as group forces. The solder can be used in an amount of preferably about 110 to 50 parts by weight based on 100 parts by weight of the powder. In addition, if necessary, inorganic fibers such as ceramics fibers and whiskers can be used as a material for improving the mechanical strength of the catalyst particles. However, potassium titanate whiskers and basic magnesium carbonate whiskers Fibers that react with such catalyst components are not preferred. Ceramic fibers are particularly preferred for improving strength. The amount of these fibers used is preferably 1 to 30 parts by weight based on 100 parts by weight of the powder. The above-mentioned molding aid is usually used by being previously mixed with a powder.

The powder mixed with a molding aid such as a binder is molded by a method such as (A) tablet molding, (B) extrusion molding, and (C) a spherical or other shape supporting molding method. The shape of the molded body is preferably selected to be an appropriate shape such as a sphere, a column, or a ring. The molded product thus formed is then calcined to obtain a composite catalyst. The sintering temperature can be usually 250-500 ° C, preferably 300-420 ° C, and the sintering time is 150 hours. The calcination can be performed in an atmosphere in the presence of an inert gas or molecular oxygen. When the firing temperature is too low, the molybdenum element may be lost due to sublimation if the thermal diffusion of the element is too high.

[0024] Means for producing a corresponding unsaturated carboxylic acid by using a catalyst produced according to the present invention and subjecting an unsaturated aldehyde to gas-phase oxidation using molecular oxygen or a gas containing molecular oxygen, according to existing methods. It can be done by a method. For example, the reaction is carried out using a fixed-bed tube reactor. In this case, the reaction can be carried out under a condition generally used for this type of reaction, whether it is a single flow method or a recycling method through a reactor.

[0025] For example, mixing of acrolein with 1-15% by volume, molecular oxygen 0.5-25% by volume, water vapor 0-40% by volume, and inert gas such as nitrogen and carbon dioxide 20-80% by volume. The gas is applied to the catalyst layer filled in each reaction zone of each reaction tube having an inner diameter of preferably 15 to 50 mm at 250 to 450 ° C and under 0.1 MPa pressure and space velocity (SV) 300 to 5000 hr- ¹ Introduced in. In the present invention, it is also possible to operate under a high load reaction condition, for example, a condition of a higher raw material gas degree or a high space velocity in order to increase productivity. By virtue of the catalyst produced by the present invention, acrylic acid can be produced with high selectivity and high yield.

Example

[0026] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, it is needless to say that the present invention should not be construed as being limited to these Examples. The night bath used in the examples is a salt bath in which a reaction tube is placed in a heat medium which also has a nitrate power of an alkali metal and reacts.The heat medium is melted at 200 ° C or higher and used up to 400 ° C. It is possible and has good heat removal efficiency, so it is a reaction bath suitable for an oxidation reaction that generates a large amount of heat.

The acrolein conversion, acrylic acid selectivity, and acrylic acid yield are defined by the following formulas.

[0028] Akurorein conversion (mol ^_0/0) = 100 X (moles of reacted Akurorein) / (number of moles of the supplied Akurorein)

Acrylic acid selectivity (mol%) = 100 X (number of moles of acrylic acid generated) Z (number of moles of acrolein subjected to transfer)

Acrylic acid yield (mol ^_0/0) = 100 X (acrylic acid mol number generated) Z (Akurore Inmoru number of supplied)

Example 1

A composite metal oxide in which the empirical formula of the constituents excluding oxygen is Mo V Nb Cu Si C

12 2.4 1 2 200 200

Was prepared as follows.

First, 1446 ml of pure water was heated to 80 ° C, and 207 g of ammonium paramolybdate, 27.5 g of ammonium ammonium metavanadate, and 12.Og of citrate were dissolved therein while stirring sequentially. To this aqueous solution, an aqueous solution of copper sulfate in which 48.6 g of copper sulfate was dissolved in 204 ml of pure water was added, and 19.3 g of niobium hydroxide was further added and stirred to obtain a slurry solution.

[0030] To this slurry solution, 782 g of silicon carbide powder was added and thoroughly stirred and mixed. The slurry was heated to 130 ° C and dried. 1.5% by weight of graphite was added thereto and mixed, and the mixture was molded by a small tableting machine. The mixture was calcined in a baking furnace at 380 ° C. for 3 hours in a nitrogen stream to obtain an insect medium.

[0031] In order to evaluate the obtained catalyst, 0.3 g of a powder crushed and sized to 20-28 mesh was filled in a U-shaped reaction tube having an inner diameter of 4 mm, and the reaction tube was heated in a night game bath ( Temperature: 288 ° C), and a composition gas (acrolein 5% by volume, oxygen 8% by volume, steam 15% by volume and nitrogen gas 72% by volume) was introduced into the reaction tube, and SV (space velocity; unit) The flow rate of the raw material gas per hour (the apparent volume of the filled catalyst) was reacted at 14900 Zhr- ¹ . As a result of the reaction, acrolein conversion ratio was 99.0%, acrylic acid selectivity was 98.6%, and acrylic acid yield was 97.6%.

Example 2 A composite metal oxide in which the empirical formula of the constituents excluding oxygen is Mo V Nb Cu Si C

12 2.4 1 2 200 200

Was prepared as follows.

First, 1446 ml of pure water was heated to 80 ° C, and then dissolved while stirring 207 g of ammonium paramolybdate, 27.5 g of ammonium metavanadate, and 12.Og of oxalic acid sequentially. To this, an aqueous solution of copper sulfate in which 48.6 g of copper sulfate was dissolved in 204 ml of pure water was added, and 19.3 g of niobium hydroxide was added and stirred to obtain a slurry solution.

[0033] To this slurry solution, 782 g of silicon carbide powder was added and thoroughly stirred and mixed. The slurry was heated to 130 ° C and dried. 1.5% by weight of graphite was added thereto and mixed, and the mixture was molded by a small tableting machine. The mixture was calcined in a baking furnace at 380 ° C. for 3 hours in a nitrogen stream to obtain an insect medium.

[0034] In order to evaluate the obtained catalyst, 0.3 g of a powder crushed and sized to 20-28 mesh was charged into a U-shaped reaction tube having an inner diameter of 4 mm, and the reaction tube was heated in a night game bath ( Temperature: 290 ° C), and a composition gas (acrolein 5% by volume, oxygen 8% by volume, steam 15% by volume, nitrogen gas 72% by volume) is introduced into the reaction tube, and SV (space velocity; unit) The raw material gas flow rate per hour (the apparent volume of the filled catalyst) was reacted at 14900 Zhr- ¹ .

[0035] As a result of the reaction, the acrolein conversion ratio was 99.0%, the selectivity for acrylic acid was 97.2%, and the yield of atalylic acid was 96.2%.

Example 3

A composite metal whose empirical formula for the components other than oxygen is Mo V Nb W Cu Sb Si C

12 2.4 1 0.5 2 1 200 200

An acidified product was prepared as follows.

First, 1446 ml of pure water was heated to 80 ° C, and on the other hand, 201 g of ammonium paramolybdate, 26.7 g of ammonium ammonium metavanadate, 12.Og of citrate, and ammonium ammonium metatungstate 11.9 g of antimony trioxide was added thereto, and an aqueous copper sulfate solution obtained by dissolving 47.3 g of copper sulfate in 204 ml of pure water was added thereto. 18.7 g of niobium was added and stirred to obtain a slurry solution.

[0037] To this slurry solution, 761 g of silicon carbide powder was added and thoroughly stirred and mixed. The slurry was heated to 130 ° C and dried. 1.5% by weight of graphite is added to the mixture, mixed and molded by a small tableting machine, which is baked in a baking furnace at 380 ° C for 3 hours in a nitrogen stream. Was used as an insect medium.

[0038] In order to evaluate the obtained catalyst, 0.3 g of pulverized and sized to 20-28 mesh was filled in a U-shaped reaction tube having an inner diameter of 4 mm, and the reaction tube was heated in a night game bath ( Temperature: 290 ° C), and a composition gas (acrolein 5% by volume, oxygen 8% by volume, steam 15% by volume, nitrogen gas 72% by volume) is introduced into the reaction tube, and SV (space velocity; unit) The raw material gas flow rate per hour (the apparent volume of the filled catalyst) was reacted at 14900 Zhr- ¹ .

[0039] As a result of the reaction, the acrolein conversion rate was 99.0%, the selectivity for acrylic acid was 98.7%, and the yield of atalylic acid was 97.7%.

[0040] Comparative example

12 2.4 1 2 200 200

Was prepared as follows.

First, 1446 ml of pure water was heated to 80 ° C., and 207 g of ammonium paramolybdate and 27.5 g of ammonium metavanadate were dissolved while stirring sequentially. To this was added an aqueous solution of copper sulfate obtained by dissolving 48.6 g of copper sulfate in 204 ml of pure water, and 19.3 g of hydroxy hydroxide was further added and stirred to obtain a slurry solution.

[0041] To this slurry solution, 782 g of silicon carbide powder was added, and thoroughly stirred and mixed. The slurry was heated to 130 ° C and dried. 1.5% by weight of graphite was added thereto and mixed, and the mixture was molded by a small tableting machine. The mixture was calcined in a baking furnace at 380 ° C. for 3 hours in a nitrogen stream to obtain an insect medium.

[0042] The reactivity of the obtained catalyst was evaluated under exactly the same conditions as in the examples. As a result of the reaction, the conversion of acrolein was 99.0%, the selectivity for acrylic acid was 97.0%, and the yield of acrylic acid was 96.0% at a temperature of one bath of nita at 296 ° C.

[0043] As described above, in the comparative example in which the organic acid was not added, the acrylic acid selectivity was low, and the result was 1.6% lower than that in Example 1.

On the other hand, in Examples 1, 2 and 3 in which an organic acid was added, the acrolein conversion, the acrylic acid selectivity and the acrylic acid yield were all excellent, and the gas phase contact of acrolein was excellent. The oxidation reaction was performed efficiently.

Industrial applicability The catalyst produced by the method of the present invention is used for producing a corresponding unsaturated carboxylic acid in a high yield by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas. Manufactured unsaturated carboxylic acids such as acrylic acid are widely used as raw materials for various chemicals, monomers for general-purpose resins, monomers for functional resins such as water-absorbing resins, flocculants, thickeners, etc. Used for

Claims

The scope of the claims

[1] Formula: Mo V X Cu Y C SiO

12 a b c d e f g

(Wherein, X represents at least one element selected from Nb and W, Y represents at least one element selected from the group consisting of Sb, Mg, Ca, Sr, Ba and Zn, a, b, c, d, e, f and g indicate the atomic ratio of each element, 0 <a≤12, 0≤b≤12, 0 <c≤12, 0≤d≤8, 0≤e≤1000, G satisfies 0≤f≤1000, and g is the number of oxygen atoms required to satisfy the oxidized state of the other elements excluding Si and C among the above component elements) In preparing the catalyst, the source compounds of the respective component elements are integrated in the presence of an organic acid in an aqueous medium system, and the resulting aqueous solution or dispersion of the integrated product is dried and molded. And calcination.

[2] The method for producing a composite oxide catalyst according to claim 1, wherein the organic acid is present in an amount of 0.001 to 1 mol per mol of molybdenum.

3. The method for producing a composite oxide catalyst according to claim 1, wherein the organic acid is at least one selected from the group consisting of citric acid, oxalic acid, and malic acid.

[4] The composite oxide catalyst according to any one of [13] to [13], wherein the composite oxide catalyst is a catalyst for producing a corresponding unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gaseous contact with a molecular oxygen-containing gas. A method for producing the composite oxide catalyst according to the above.

[5] The corresponding acrylic acid is produced by subjecting acrolein to gas-phase catalytic oxidation with a molecular oxygen-containing gas in the presence of the composite oxide catalyst produced by the production method according to any one of claims 14 to 14. Method.