JP2002306970A - Catalyst for manufacturing methacrylic acid, method for manufacturing the catalyst and method for manufacturing methacrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a catalyst to obtain methacrylic acid with high yield by gas-phase catalytic oxidation of methacrolein, to provide a method for manufacturing the catalyst and to provide a method for manufacturing methacrylic acid by using the above catalyst. SOLUTION: The catalyst for manufacturing methacrylic acid contains a solid acid containing at least molybdenum, phosphorus, vanadium and copper and oxide particles having < 1 μm average particle size and containing at least molybdenum. Methacrylic acid is obtained with high yield by subjecting methacrolein to the gas-phase catalytic oxidation by using the above catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation.
The present invention relates to a method for producing the catalyst and a method for producing methacrylic acid using the catalyst.

[0002]

2. Description of the Related Art It has been known that a heteropolyacid compound represented by phosphomolybdic acid is effective as a catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation. Many proposals have been made. Heteropoly acid compounds are a type of solid acid.

[0003] Some catalysts in which a heteropolyacid compound and a composite oxide are mixed are also known. For example, JP-A-9-313943 discloses a composite oxide catalyst comprising a heteropolyacid compound containing at least molybdenum and phosphorus and a binary oxide comprising molybdenum and niobium. Disclosed is a catalyst comprising a composite oxide essentially containing molybdenum and phosphorus and a solid acid having an acid strength (H0) of -11.93 or less. JP-A-7-267635 discloses that the maximum diameter of a mixed oxide composition to be mixed is> 0 to 20.
JP-A-6-71177 discloses a catalyst in which the maximum diameter of the mixed oxide composition to be mixed is specified to be 0 to 25 μm, preferably 1 to 200 μm.

[0004] However, none of the catalysts proposed so far have sufficient reaction results, especially yields, and further improvement is desired as an industrial catalyst.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a catalyst capable of obtaining methacrylic acid in a high yield by subjecting methacrolein to gas-phase catalytic oxidation, a method for producing the catalyst, and a method for producing methacrylic acid using the catalyst. The purpose is to provide.

[0006]

The above object of the present invention can be solved by the following present invention. (1) A catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation, comprising the following components (A) and (B):

Component (A): a solid acid containing at least molybdenum, phosphorus, vanadium and copper Component (B): an average particle size containing at least molybdenum is 1
2. Oxide particles having a particle diameter of less than μm (2) The catalyst for methacrylic acid production according to (1), wherein a mixture of the precursor of the component (A) and the component (B) is heat-treated at 200 to 500 ° C. Method. (3) A method for producing methacrylic acid, comprising subjecting methacrolein to gas-phase catalytic oxidation in the presence of the catalyst for producing methacrylic acid according to (1).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The methacrylic acid production catalyst of the present invention is a catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation, and comprises the following components (A) and (B). It is characterized by including.

Component (A): a solid acid containing at least molybdenum, phosphorus, vanadium and copper Component (B): an average particle size containing at least molybdenum is 1
Oxide particles smaller than μm Methacrylic acid can be produced in a higher yield by gas phase catalytic oxidation of methacrolein in the presence of such a catalyst as compared with a conventional heteropolyacid compound catalyst. Further, the activity and methacrylic acid selectivity are higher than those of conventional heteropolyacid compound catalysts.

The reason why the catalyst for producing methacrylic acid of the present invention is superior to the conventional heteropolyacid compound catalyst is unknown. However, the present inventor has proposed that the component (A) and the component (B) having a small particle diameter are different. An effective interface between the two solids is formed for the interaction between the two, and the active site of methacrolein oxidation and the surrounding structure are affected, and the redox process, especially the reoxidation process of the heteropolyacid compound, is smoothed. Therefore, it is presumed that it is more suitable for methacrolein oxidation.

The component (A) in the catalyst of the present invention is a solid acid containing at least molybdenum, phosphorus, vanadium and copper. Among them, heteropoly acids or salts thereof (hereinafter, these are referred to as heteropoly acid compounds) are preferred.

The component (A) is specifically represented by the following formula (1)
Are preferred.

P _a Mo _b V _c Cu _d X _e Y _f Z _g O _h (1) wherein P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively. ,
X represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, tellurium, silver, selenium, silicon, tungsten and boron;
Represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum, and Z represents a group consisting of potassium, rubidium, cesium and thallium. Shows at least one selected element. a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when b = 12, a = 0.1-3, c =
0.01-3, d = 0.01-3, e = 0-3, f = 0
And g = 0.01-3, and h is the atomic ratio of oxygen necessary to satisfy the valence of each component.

The solid acid of the component (A) can be prepared by various methods such as a precipitation method and an oxide mixing method which are well known in the art. Specifically, a raw material containing a constituent element of a solid acid is used, and a required amount thereof is appropriately dissolved or suspended in a solvent such as water, and the obtained mixed solution or aqueous slurry is evaporated to dryness. A method obtained by pulverizing and molding and then heat-treating can be exemplified. As described later, the heat treatment of the component (A) is preferably performed after mixing with the component (B). The heat treatment temperature of the component (A) is 200 to
500 ° C is preferable, and particularly preferably 300 to 450 ° C. The heat treatment of the component (A) is preferably performed under a flow of oxygen, a flow of air, or a flow of nitrogen. The heat treatment time is not particularly limited, but is usually preferably about 1 to 40 hours.

The raw materials used for preparing the component (A) are not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides and the like of each element can be used in combination. For example, as a molybdenum raw material, ammonium paramolybdate, molybdenum trioxide,
Molybdic acid, molybdenum chloride, or the like can be used. As the vanadium raw material, ammonium metavanadate, vanadium pentoxide, vanadium chloride, vanadyl oxalate, or the like can be used. As the phosphorus raw material, orthophosphoric acid, metaphosphoric acid, diphosphorus pentoxide, pyrophosphoric acid, ammonium phosphate and the like can be used. As a copper raw material, copper nitrate, copper sulfate, cuprous chloride, cupric chloride and the like can be used. Further, as a raw material of molybdenum and phosphorus, a heteropoly acid (salt) such as phosphomolybdic acid and ammonium phosphomolybdate can also be used.

On the other hand, the component (B) in the catalyst of the present invention is an oxide particle containing at least molybdenum and having an average particle size of less than 1 μm.

The component (B) is particularly preferably an oxide particle represented by the following formula (2).

Mo _i D _{j Ok} (2) wherein Mo and O represent molybdenum and oxygen, respectively, and D is bismuth, vanadium, tungsten, iron, cobalt, chromium, nickel, antimony, tantalum, zirconium. And at least one element selected from the group consisting of niobium, niobium, titanium, aluminum and silicon. i, j and k represent the atomic ratio of each element, and when i = 1, j = 0 to 20; and k is the atomic ratio of oxygen necessary to satisfy the valence of each component. Since a high methacrylic acid yield can be obtained, j is preferably 0.1 or more, particularly preferably 0.2 or more, and is preferably 10 or less, particularly preferably 3 or less. D is preferably one or more of bismuth, vanadium and zirconium.

The average particle size of the oxide of the component (B) is less than 1 μm, and a high methacrylic acid yield can be obtained.
It is preferably at most 0.1 μm, particularly preferably at most 0.1 μm.
Here, the average particle diameter is represented by a particle diameter when the cumulative percentage in the particle diameter accumulation curve becomes 50%, that is, a median diameter.

By optimizing the preparation conditions and drying conditions of the oxide and adjusting the particle size of the slurry and the particle size of the dry powder,
An oxide having the desired average particle size is obtained. For example, a sol-gel method, an alkoxide hydrolysis method, a gas phase reaction method, or the like can be used. It is also effective to grind the slurry or dry powder using a homogenizer or a grinder.

The preparation of the oxide of the component (B) can be performed by various methods such as a well-known precipitation method and an oxide mixing method. Specifically, using a molybdenum raw material and a raw material containing each of the other constituent elements, a required amount thereof is appropriately dissolved or suspended in a solvent such as water, and the obtained mixed solution or aqueous slurry is dried and heat-treated. A method can be exemplified. Various methods can be used for drying the mixed solution or the aqueous slurry, and examples thereof include an evaporation to dryness method, a spray drying method, a drum drying method, and a flash drying method.

The raw material used for preparing the component (B) is not particularly limited, and it is possible to use a combination of nitrates, carbonates, acetates, oxalates, ammonium salts, oxides, halides and the like of each element. it can. Examples of the molybdenum raw material include ammonium paramolybdate, molybdenum trioxide, molybdenum dioxide, molybdic acid, molybdenum chloride, and the like. Of these, ammonium paramolybdate is preferable.

The component (B) can be subjected to a heat treatment if necessary. As the atmosphere for the heat treatment, air, nitrogen, or the like is preferably used. The higher the heat treatment temperature, the more the valence of the main component is controlled by electron transfer between the components, and the lower the heat treatment temperature, the less the melting, decomposition, sublimation, etc. of the oxide. The heat treatment is usually performed at 300 to 800 ° C for 1 to 50.
It is preferable to perform for a time. The heat treatment is preferably performed before mixing with the component (A) or a precursor thereof. Here, the precursor of the component (A) refers to the component (A)
It refers to a mixed solution or an aqueous slurry at the time of preparation and a dried product thereof.

The catalyst for producing methacrylic acid of the present invention contains the above-mentioned components (A) and (B). The amount of the component (B) in the catalyst of the present invention is such that the effect of the addition of the component (B) is sufficiently exerted.
1 part by weight or more, preferably 5 parts by weight or more, more preferably 100 parts by weight or less, particularly preferably 70 parts by weight or less, based on 100 parts by weight of molybdenum (element) used for the preparation of

The catalyst of the present invention comprises a component (A) and a component (B).
Are mixed with each other, and the component (A) and the component (B) are present as separate particles in the catalyst. This component (B) is a particle having an average particle diameter of less than 1 μm.

The catalyst of the present invention is obtained by mixing the above-mentioned component (A) or a precursor thereof and the above-mentioned component (B), and calcining the mixture, preferably heat-treating the mixture at 200 to 500 ° C.

In the production of the catalyst for producing methacrylic acid of the present invention, the method of mixing the component (A) or its precursor with the component (B) is not particularly limited, and the component (A) or its precursor to be mixed, In addition, it can be appropriately selected depending on the type, properties, addition ratio and the like of the component (B). In particular, a method of mixing the aqueous slurry that is the precursor of the component (A) with the component (B), and a method of mixing the dried product that is the precursor of the component (A) with the component (B) are preferable. afterwards,
Even if the preparation of component (A) proceeds, the amount and state of component (B) do not change under normal preparation conditions. In addition, even if the preparation method is such that the component (B) changes, the final catalyst may satisfy the conditions of the present invention. Whichever method is used to mix the component (A) and the component (B), it is preferable that the components are uniformly and sufficiently mixed.

In the case of mixing the aqueous slurry, which is the precursor of the component (A), with the component (B), various methods can be used for drying the mixture depending on the state of the mixture. For example, an evaporation to dryness method, a spray drying method, a drum drying method, a flash drying method and the like can be used. This dried product may be subjected to the next baking as it is,
Usually, it is preferable to fire after molding.

The method for molding the catalyst is not particularly limited, and various dry and wet molding methods such as tableting, press molding, extrusion molding and granulation molding can be applied. The shape of the molded body is not particularly limited, and an optimum shape can be selected from, for example, spheres, cylinders, pellets, rings, and the like in consideration of the type and conditions of the reactor. In molding, known additives, for example, graphite,
A small amount of talc or the like may be added.

The method for calcining the molded article thus obtained is not particularly limited, and the same known method and conditions as those for calcining the heteropolyacid compound catalyst for producing methacrylic acid can be applied. Optimum conditions for firing vary depending on the raw materials used, the composition, the preparation method, and the like. Usually, the atmosphere is under a flow of an oxygen-containing gas such as air and / or under a flow of an inert gas, and the firing temperature is 200 to 500 ° C, preferably 300 ℃
At or above 450 ° C., the firing time is at least 0.5 hour, preferably at least 1 hour or at most 40 hours.

The catalyst of the present invention is for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation.
The methacrylic acid yield of the catalyst for producing methacrylic acid of the present invention is superior to that of a conventional heteropolyacid compound catalyst.

The reaction for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation may be carried out in the same manner as in the case of using a usual heteropolyacid compound catalyst. The reaction temperature of this reaction is preferably 230 to 450 ° C, particularly 250 ° C.
~ 400 ° C is preferred. The reaction pressure is preferably from normal pressure to several atmospheres. The contact time is preferably from 1.5 to 8.0 seconds.

The concentration of methacrolein in the raw material gas can be varied in a wide range, but is preferably 1 to 20%, particularly preferably 3 to 10% by volume. The raw material gas may contain a small amount of impurities such as a lower saturated aldehyde derived from the raw material methacrolein, and these impurities do not substantially adversely affect the reaction.

As the molecular oxygen source used for the reaction, air is economical, but if necessary, air enriched with pure oxygen can be used. The molecular oxygen concentration in the raw material gas is 0.4 to 4 mol, especially 0.1 mol per 1 mol of methacrolein.
5 to 3 moles are preferred.

The source gas may be a gas obtained by diluting methacrolein and a molecular oxygen source with an inert gas such as nitrogen, steam, or carbon gas.

It is preferable that the raw material gas for the reaction contains water vapor. Performing the reaction in the presence of water results in high methacrylic acid selectivity. The concentration of water vapor in the raw material gas is preferably 3 to 45% by volume, particularly preferably 5 to 40%.

The reaction can be carried out in a fixed bed or in a fluidized bed.

[0038]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the examples.

"Parts" in the following Examples and Comparative Examples are parts by weight, and the analysis of the raw material gas and the product was carried out by using gas chromatography (GC-8A, manufactured by Shimadzu Corporation). In addition, the oxide composition and the catalyst composition were determined from the charged amounts of the raw materials. The average particle size was measured using a laser diffraction particle size distribution analyzer (PRO-7000S manufactured by Seishin Enterprise) after dispersing the oxide powder in pure water.

The reaction rate of methacrolein, the selectivity of methacrylic acid produced and the single-stream yield are defined as follows.

Reaction rate of methacrolein (%) = (B / A) × 100 Selectivity of methacrylic acid (%) = (C / B) × 100 Single-stream yield of methacrylic acid (%) = (C / A) ) × 100 where A is the number of moles of supplied methacrolein, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced. [Example 1] (Preparation of component (B)) 137.4 parts of bismuth nitrate was suspended in 300 parts of pure water, heated to 60 ° C with stirring, and nitric acid was slowly added until the bismuth nitrate was completely dissolved. It was dropped. This solution is added to ammonium paramolybdate 10
The solution was added to 300 parts of an aqueous solution containing 0 parts, and stirring was continued for 1 hour. Thereafter, 29% by weight aqueous ammonia was added until the pH reached 3. Then, the deposited precipitate was separated by suction filtration to obtain a yellow-white solid. The obtained solid is heated at 130 ° C. for 1 hour.
After drying for 6 hours, the obtained solid was pulverized and then heat-treated at 450 ° C. for 5 hours under air.

The composition of the obtained composite oxide other than oxygen (the same applies hereinafter) was Mo ₁ Bi _0.5 . The average particle size of this composite oxide was 0.5 μm. (Preparation of catalyst) To 100 parts of ammonium paramolybdate dissolved in 150 parts of pure water, 8.7 parts of 85% by weight phosphoric acid was added, and the mixture was heated to 60 ° C. Further, 5.7 parts of copper nitrate dissolved in 20 parts of pure water and 2.8 parts of ammonium metavanadate were used.
Parts, 13.8 parts of cesium nitrate dissolved in 50 parts of pure water, and Mo ₁ Bi _0.5 having an average particle diameter of 0.5 μm as the component (B).
10 parts of the composite oxide was added, and the temperature was raised to 80 ° C. and maintained for 2 hours. The resulting slurry was evaporated to dryness while heating and stirring,
The obtained solid was dried at 130 ° C. for 16 hours. It was pulverized after pressure molding, fractionated from 10 to 20 mesh portions, and calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst.

The composition of the catalyst other than the Mo—Bi composite oxide, that is, the composition of the component (A) was P _1.6 Mo ₁₂ V _0.5 C
u _0.5 Cs _1.5 . The amount of component (B) was 18.4 parts by weight based on 100 parts by weight of molybdenum used for preparing component (A).

This catalyst was charged into a reaction tube, and methacrolein 5%, oxygen 10%, steam 20% and nitrogen 65%
(Volume%) was passed at normal pressure, at a reaction temperature of 290 ° C., and for a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography. Table 1 shows the catalyst composition and the reaction results. Example 2 A catalyst was prepared and reacted in the same manner as in Example 1, except that 10 parts of a Mo ₁ Bi _0.5 composite oxide having an average particle size of 0.9 μm was used as the component (B). The amount of component (B) was 18.4 parts by weight based on 100 parts by weight of molybdenum used for preparing component (A). Table 1 shows the catalyst composition and the reaction results. Example 3 A catalyst was prepared and reacted in the same manner as in Example 1 except that 30 parts of a Mo ₁ Bi _0.5 composite oxide having an average particle size of 0.5 μm was used as the component (B). The amount of component (B) depends on the amount of molybdenum 1 used in the preparation of component (A).
It was 55.2 parts by weight based on 00 parts by weight. Table 1 shows the catalyst composition and the reaction results. Example 4 A catalyst was prepared and reacted in the same manner as in Example 1 except that 50 parts of a Mo ₁ Bi _0.5 composite oxide having an average particle size of 0.5 μm was used as the component (B). The amount of component (B) depends on the amount of molybdenum 1 used in the preparation of component (A).
It was 92.0 parts by weight based on 00 parts by weight. Table 1 shows the catalyst composition and the reaction results. Example 5 8.7 parts of 85% by weight phosphoric acid was added to 100 parts of ammonium paramolybdate dissolved in 150 parts of pure water, and the mixture was heated to 60 ° C. Further, 4.6 parts of copper nitrate dissolved in 20 parts of pure water and 2.8 parts of ammonium metavanadate were used.
And 16.6 parts of cesium nitrate dissolved in 50 parts of pure water, and the mixture was heated to 80 ° C. and kept for 2 hours. The resulting slurry was evaporated to dryness while heating and stirring, and the resulting solid was
After drying at 0 ° C. for 16 hours, the mixture was ground. The dry powder thus obtained was used as component (A).

The composition of the component (A) is P _1.6 Mo ₁₂ V _0.5 C
u _0.4 Cs _1.8 .

A total of 105 parts of this component (A) was mixed with 10 parts of a Mo ₁ Bi _0.5 composite oxide having an average particle diameter of 0.5 μm used in Example 1 as a component (B) using a mortar. did. The resulting mixed powder was subjected to pressure molding and then pulverized. A 10 to 20 mesh portion was fractionated and calcined at 380 ° C. for 5 hours in an air stream to obtain a catalyst. The amount of the component (B) was 18.4 parts by weight based on 100 parts by weight of the molybdenum used for preparing the component (A).

Then, a reaction was carried out in the same manner as in Example 1 using this catalyst. Table 1 shows the catalyst composition and the reaction results. Comparative Example 1 A catalyst preparation and a reaction were carried out in the same manner as in Example 1 except that 10 parts of a Mo ₁ Bi _0.5 composite oxide having an average particle size of 7.1 μm was used as the component (B). The amount of component (B) depends on the amount of molybdenum 1 used in the preparation of component (A).
It was 18.4 parts by weight based on 00 parts by weight. Table 1 shows the catalyst composition and the reaction results. [Example 6] (Preparation of component (B)) Ammonium metavanadate 6
6.3 parts are suspended in 300 parts of pure water, and 60 parts are stirred.
Heated to ° C. Thereafter, oxalic acid powder was added until the ammonium metavanadate was completely dissolved and the solution turned dark green, and the mixture was heated and stirred at 70 ° C. for 1 hour. This solution is
The solution was added to 300 parts of an aqueous solution containing 100 parts of ammonium paramolybdate, and heated and stirred at 70 ° C. for 1.5 hours. Then, the solution was evaporated to dryness to obtain a black-brown solid. The obtained solid was dried at 130 ° C. for 16 hours, pulverized, and heat-treated at 450 ° C. in air for 5 hours.

The composition of the obtained composite oxide was Mo ₁ V _1.0
Met. The average particle size of the composite oxide is 0.1 μm.
m. (Catalyst preparation) Molybdenum trioxide 100 in 400 parts of pure water
Part, 85 parts by weight of phosphoric acid 8.0 parts, ammonium metavanadate 1.6 parts, copper nitrate 4.2 parts, iron nitrate 2.3 parts and Mo ₁ V having an average particle diameter of 0.1 μm as the component (B). 20 parts of _1.0 composite oxide was added, and the mixture was stirred at 80 ° C. under reflux for 5 hours. After cooling to 50 ° C., 36.0 parts of 29% by weight ammonia water was added dropwise and stirred for 15 minutes. Thereafter, 13.5 parts of cesium nitrate dissolved in 50 parts of pure water were added, and 15
Minutes. The obtained slurry was evaporated to dryness while heating and stirring, and the obtained solid was dried at 130 ° C. for 16 hours. It was pulverized after pressure molding, fractionated from 10 to 20 mesh portions, and calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst.

A group other than the Mo-V composite oxide of this catalyst
Composition, that is, the composition of component (A) is P _1.2Mo₁₂V_0.3C
u_0.3Fe_0.1Cs_1.2Met. Also, the amount of component (B)
Is 100 parts by weight of molybdenum used for preparing the component (A)
Was 30.0 parts by weight.

Then, a reaction was carried out in the same manner as in Example 1 using this catalyst. Table 1 shows the catalyst composition and the reaction results. Comparative Example 2 A catalyst was prepared and reacted in the same manner as in Example 6, except that 20 parts of a Mo ₁ V _1.0 composite oxide having an average particle size of 5.6 μm was used as the component (B). Component (B)
Was 30.0 parts by weight based on 100 parts by weight of molybdenum used for preparing the component (A). Table 1 shows the catalyst composition and the reaction results. Example 7 Dissolve 91.26 parts of zirconium oxide chloride in 400 parts of pure water, and add ammonium paramolybdate 10
0 parts were mixed with an aqueous solution dissolved in 300 parts of pure water. 29% by weight aqueous ammonia was added to the solution until the pH became 9, and stirring was continued for 1 hour. Thereafter, the stirring was stopped, and the mixture was allowed to stand until the deposited precipitate completely settled, and then the supernatant was removed by decantation. Then, the precipitate was separated by suction filtration and sufficiently washed with pure water to obtain a white solid. The obtained solid was dried at 130 ° C. for 16 hours, pulverized, and heat-treated at 450 ° C. in air for 5 hours.

The composition of the obtained composite oxide is Mo ₁ Zr
_0.5 . The composite oxide has an average particle size of 0.1.
It was 8 μm. (Catalyst preparation) Molybdenum trioxide 100 in 400 parts of pure water
Parts, 9.3 parts of 85% by weight phosphoric acid, 2.7 parts of 60% by weight arsenic acid
, 7.4 parts of vanadium pentoxide, 1.8 parts of copper oxide and 5 parts of a Mo ₁ Zr _0.5 composite oxide having an average particle diameter of 0.8 μm, which is the component (B), and stirred at 80 ° C. under reflux for 4 hours. did.
After cooling to 50 ° C., 15.7 parts of cesium bicarbonate dissolved in 50 parts of pure water and 10.6 parts of ammonium nitrate dissolved in 50 parts of pure water were added dropwise and stirred for 15 minutes. The obtained slurry was evaporated to dryness while heating and stirring, and the obtained solid was dried at 130 ° C. for 16 hours. It was pulverized after pressure molding, fractionated from 10 to 20 mesh portions, and calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst.

The composition of the catalyst other than the Mo—Zr composite oxide, that is, the composition of the component (A) was P _1.4 Mo ₁₂ V _0.7 A
s _0.2 Cu _0.4 Cs _1.4 . The amount of component (B) was 7.5 parts by weight based on 100 parts by weight of molybdenum used for preparing component (A).

Then, a reaction was carried out in the same manner as in Example 1 using this catalyst. Table 1 shows the catalyst composition and the reaction results. Comparative Example 3 A catalyst was prepared and reacted in the same manner as in Example 7, except that 5 parts of a Mo ₁ Zr _0.5 composite oxide having an average particle size of 9.8 μm was used as the component (B). Component (B)
Was 7.5 parts by weight based on 100 parts by weight of molybdenum used for preparing the component (A). Table 1 shows the catalyst composition,
The reaction results are shown.

[0054]

[Table 1]

It can be seen that the examples using the catalyst of the present invention have higher single-stream yields of methacrylic acid than the comparative examples.

[0056]

Industrial Applicability According to the present invention, there is provided a catalyst capable of obtaining methacrylic acid in a high yield by subjecting methacrolein to gas phase catalytic oxidation, a method for producing the catalyst, and a method for producing methacrylic acid using the catalyst. Can be.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Naito 20-1 Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Mohammed 20-1 Miyukicho, Otake City, Hiroshima Prefecture No. F-term in the Central Research Laboratory of Mitsubishi Rayon Co., Ltd. (Reference) 4G069 AA02 AA08 BA45 BA45A BB06A BB06B BC03A BC05A BC06A BC06B BC19A BC23A BC25A BC25B BC26A BC27A BC31A BC31B BC32A BC51A BC51B BC54A BC54BBC10ABD59 EA01X EA01Y EA02X EA02Y EB18Y FB09 4H006 AA02 AC46 BA02 BA05 BA10 BA12 BA13 BA14 BA18 BA35 BA81 BB61 BB62 BC10 BC11 BC19 BC32 BS10 4H039 CA65 CC30

Claims (6)

[Claims] 1. A catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation, comprising the following components (A) and (B): Component (A): a solid acid containing at least molybdenum, phosphorus, vanadium and copper Component (B): an average particle size containing at least molybdenum is 1
Oxide particles smaller than μm 2. The amount of the component (B) is equal to the content of the component (A).
1 to 100 parts by weight of molybdenum used for the preparation of
The catalyst for producing methacrylic acid according to claim 1, which is 00 parts by weight. 3. The catalyst for producing methacrylic acid according to claim 1, wherein the component (A) is a solid acid represented by the following formula (1). _{P a Mo b V c Cu d} X e Y f Z g O h (1) ( wherein, P, Mo, V, Cu and O, respectively phosphorus,
X represents molybdenum, vanadium, copper and oxygen, X represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron, and Y represents At least one selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum
Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when b = 12, a = 0.1
-3, c = 0.01-3, d = 0.01-3, e = 0
3, f = 0 to 3, g = 0.01 to 3, and h is the atomic ratio of oxygen necessary to satisfy the valence of each component. ) 4. The catalyst for producing methacrylic acid according to claim 1, wherein the component (B) is an oxide particle represented by the following formula (2). Mo _i D _{j Ok} (2) (wherein, Mo and O represent molybdenum and oxygen, respectively, and D is bismuth, vanadium, tungsten,
It represents at least one element selected from the group consisting of iron, cobalt, chromium, nickel, antimony, tantalum, zirconium, niobium, titanium, aluminum and silicon. i, j and k represent the atomic ratio of each element, and i
When = 1, j = 0 to 20, and k is the atomic ratio of oxygen necessary to satisfy the valence of each component. ) 5. The catalyst for producing methacrylic acid according to claim 1, wherein a mixture of the precursor of the component (A) and the component (B) is heat-treated at 200 to 500 ° C. Manufacturing method. 6. A method for producing methacrylic acid, comprising subjecting methacrolein to gas-phase catalytic oxidation in the presence of the catalyst for producing methacrylic acid according to claim 1.