JP2002095972A - Catalyst for producing methacrylic acid, method for producing the catalyst, and method for producing methacrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for producing methacrylic acid in high yields by oxidizing methacrolein by contact in a vapor phase, a method for producing the catalyst, and a method for producing methacrylic acid by using the catalyst. SOLUTION: There are provided a catalyst for producing methacrylic acid, which is a catalyst for producing methacrylic acid by oxidizing methacrolein by contact in a vapor phase and comprises the components (A, B, and C), provided that the amount of component (B) is 1-100 pts.wt. per 100 pts.wt. molybdenum contained in component A: (A) a solid acid containing at least molybdenum, phosphorus, vanadium, and copper, (B) a compound oxide containing at least molybdenum and zirconium and obtained by heat treatment at 300-800 deg.C; a method for producing the catalyst which comprises heat-treating a mixture of (A with B) at 200-500 deg.C; and a method for producing methacrylic acid which comprises oxidizing methacrolein by contact in a vapor phase in the presence of the 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 gas phase catalytic oxidation of methacrolein. The proposal has been made. Heteropolyacid compounds are a kind of solid acids, and some catalysts in which a heteropolyacid compound and a composite oxide are mixed are known. For example, a binary oxide catalyst comprising a heteropolyacid compound containing at least molybdenum and phosphorus, molybdenum and niobium (Japanese Patent Laid-Open No. 9-313943), a composite oxide containing molybdenum and phosphorus as essential, and sulfuric acid-treated zirconium oxide A catalyst mixed with a strong acid (JP-A-8-47643) can be used.

[0003]

However, none of the catalysts proposed up to now have sufficient reaction results and cannot be said to have sufficient performance as an industrial catalyst, and further improvement is desired.

Accordingly, the present invention provides a catalyst capable of producing methacrylic acid in a high yield by subjecting methacrolein to gas-phase catalytic oxidation.
An object of the present invention is to provide a method for producing the catalyst and a method for producing methacrylic acid using the catalyst.

[0005]

The present invention relates to a catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation, comprising the following components (A) and (B): The catalyst for producing methacrylic acid, wherein the amount of B) is 1 to 100 parts by weight based on 100 parts by weight of molybdenum contained in the component (A). Component (A): a solid acid containing at least molybdenum, phosphorus, vanadium and copper Component (B): a composite oxide containing at least molybdenum and zirconium obtained by heat treatment at 300 to 800 ° C.

The catalyst for producing methacrylic acid is prepared by mixing a mixture of the precursor of the component (A) and the component (B) with 200 to 5 parts.
It can be manufactured by heat treatment at 00 ° C.

The present invention also provides a method for producing methacrylic acid, wherein methacrolein is subjected to gas-phase catalytic oxidation in the presence of the catalyst for producing methacrylic acid.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The component (A) in the catalyst of the present invention comprises:
Specifically, a solid acid containing at least molybdenum, phosphorus, vanadium and copper represented by the following formula (1) is preferable, and among them, a heteropolyacid or a salt thereof (hereinafter, these are referred to as a heteropolyacid compound) is particularly preferable. In _{P a Mo b V c Cu d} X e Y f Z g O h (1) where indicated in the formula, P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen,
X represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, tellurium, silver, selenium, silicon, tungsten and boron;
Y 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 the group consisting of potassium, rubidium, cesium and thallium At least one element selected from the group consisting of: a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when b = 12, a = 0.1 to 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.

The preparation of the solid acid as the component (A) can be carried out by various methods well known in the art, such as a precipitation method and an oxide mixing method. Specifically, using a raw material containing a constituent element of a solid acid, a required amount thereof is appropriately dissolved or suspended in a solvent such as water, and a mixed solution or an aqueous slurry obtained by evaporating to dryness is further dried. Examples of the method include pulverization and molding, if necessary, followed by heat treatment. Component (A)
Is preferably performed after mixing with the component (B) as described later. The heat treatment temperature of the component (A) is 200
To 500 ° C, and particularly preferably 300 to 450 ° C.

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 and the like can be used. As the vanadium raw material, ammonium metavanadate, vanadium pentoxide, vanadium chloride, vanadyl oxalate and the like can be used. As the phosphorus raw material, orthophosphoric acid, metaphosphoric acid, phosphorus 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 be used.

On the other hand, the component (B) is a composite oxide containing at least molybdenum and zirconium. Particularly, a composite oxide represented by the following formula (2) is preferable. Mo _i Zr _j D _k O _l (2) where, Mo, Zr and O represent molybdenum, zirconium and oxygen, respectively, and D is a group consisting of titanium, vanadium, niobium, bismuth, tungsten, chromium and antimony. At least one element selected from the group consisting of: i, j, k and l represent the atomic ratio of each element. When i = 1, j = 0.05 to 20, k = 0 to 1
0 and 1 is the atomic ratio of oxygen necessary to satisfy the valence of each component. j is particularly preferably from 0.1 to 5, and k is particularly preferably from 0.01 to 5.

The preparation of the composite oxide of the component (B) can be carried out 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 a zirconium raw material and each of the other constituent elements, a required amount thereof is appropriately dissolved or suspended in a solvent such as water to obtain a mixed solution or an aqueous slurry. Examples of the method include drying and heat treatment. 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 temperature of the heat treatment is 300 to 800 ° C., preferably 350 to 800 ° C.
700 ° C. As the atmosphere for the heat treatment, air, nitrogen, or the like is used. The higher the heat treatment temperature, the more the control of the valence of the main component due to electron transfer between the components proceeds, and the lower the heat treatment temperature, the less the melting, decomposition, sublimation, etc. of the oxide. The timing of the heat treatment is preferably before mixing with the component (A) or its precursor. Here, the precursor of the component (A) refers to a mixed solution or an aqueous slurry at the time of preparation and a dried product thereof.

The raw materials used for preparing the composite oxide of the component (B) are not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides and the like of each element can be used in combination. . Examples of the molybdenum raw material include ammonium paramolybdate, molybdenum trioxide, molybdenum dioxide, and the like. Of these, ammonium paramolybdate is preferable. Examples of the zirconium raw material include zirconium hydroxide, zirconium oxide, zirconium tetrachloride, zirconium tetra-iso-propoxide and the like, with zirconium hydroxide being preferred.

The surface area of the composite oxide as the component (B) is preferably 0.5 to 100 m ² / g, and the average particle size is 1 to 1 m ² / g.
00 μm is preferred. The surface area and the average particle size can be adjusted by preparation conditions, drying conditions, heat treatment conditions, and the like.

The catalyst for producing methacrylic acid of the present invention contains the component (A) and the component (B). The amount of the component (B) in the catalyst for producing methacrylic acid of the present invention is 1 to 100 parts by weight of molybdenum contained in the component (A).
100 parts by weight, preferably 5 to 50 parts by weight.

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 kind, properties, addition ratio and the like of the component (B).
As a preferable mixing method, a method of mixing the aqueous slurry which is a precursor of the component (A) with the component (B), the method of mixing the component (A)
And a method of mixing the dried product that is the precursor of the above with the component (B).

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. The dried product may be subjected to the next baking as it is, but it is usually preferable to bake after forming. The molding method is not particularly limited, and for example, various dry and wet molding methods such as tablet molding, 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. At the time of molding, known additives such as graphite and talc may be added in small amounts.

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 450 ° C., the firing time is 0.5 hours or more, preferably 1 hour.
~ 40 hours.

The catalyst of the present invention is for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation. The reaction temperature of this reaction is preferably from 230 to 450 ° C, particularly preferably from 250 to 400 ° C. The reaction pressure is from normal pressure to several atmospheres. The raw material gas for the reaction preferably contains water vapor. Further, the raw material gas for the reaction 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. Air is economical as the molecular oxygen source used in the reaction, but air enriched with pure oxygen can be used if necessary. The molecular oxygen concentration in the source gas is preferably 0.4 to 4 mol, particularly preferably 0.5 to 3 mol, per 1 mol of methacrolein. The source gas may be one obtained by diluting methacrolein and a molecular oxygen source with an inert gas such as nitrogen, water vapor, or carbon gas. The reaction can be carried out in a fixed bed or a fluidized bed.

It is not clear why the methacrylic acid yield of the catalyst for producing methacrylic acid of the present invention is superior to that of the conventional heteropolyacid compound catalyst. However, the present inventors have determined that the component (A) and the component (B) It is presumed that the interaction between the two solids) affects the active site of methacrolein oxidation of component (A), the surrounding structure, and the like, making the component (A) more suitable for methacrolein oxidation.

[0021]

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 performed using gas chromatography. The conversion of methacrolein, the selectivity of methacrylic acid to be produced, and the single-stream yield are defined as follows. Conversion of methacrolein (%) = (B / A) × 100 Selectivity of methacrylic acid (%) = (C / B) × 100 Single flow yield of methacrylic acid (%) = (C / A) × 100 Here, 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 generated.

Example 1 (Preparation of Component (B)) Ammonium paramolybdate 1
Zirconium hydroxide 2 in 450 parts of aqueous solution
0.1 part was added, heated to 80 ° C. and kept at that temperature for 3 hours. The obtained slurry was evaporated to dryness while heating and stirring, and then dried at 130 ° C. for 16 hours. The obtained solid was pulverized and then heat-treated at 450 ° C. for 5 hours in the air. Composition other than oxygen of the obtained composite oxide (the same applies hereinafter)
Was Mo ₁ Zr _0.25 . The surface area of the composite oxide was 5.6 m ² / g, and the average particle size was 17.8 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 heated to 60 ° C. Further, 4.6 parts of copper nitrate dissolved in 20 parts of pure water, 2.8 parts of ammonium metavanadate, and cesium nitrate dissolved in 50 parts of pure water.
6 parts and 20 parts of the Mo ₁ Zr _0.25 composite oxide heat-treated at 450 ° C. in air as the component (B) (36.8 parts per 100 parts of molybdenum contained in ammonium paramolybdate as a raw material of the component (A)) And heated to 80 ° C. and maintained for 2 hours. 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 this catalyst other than the Mo—Zr composite oxide, that is, the composition of the component (A) is P _1.6
Mo ₁₂ V _0.5 Cu _0.4 Cs _1.8 .

This catalyst was filled in a reaction tube, and at normal pressure, methacrolein 5%, oxygen 10%, steam 30%, nitrogen 5%
When a mixed gas of 5% (volume%) was passed at a reaction temperature of 285 ° C. and a contact time of 3.6 seconds, the conversion of methacrolein was 83.5%, the selectivity of methacrylic acid was 83.2%, Was 69.5%.

Comparative Example 1 Mo ₁ Zr as Component (B)
Catalyst preparation and reaction were carried out in the same manner as in Example 1 except that _0.25 composite oxide was not added. The results show that the conversion of methacrolein is 82.8% and the selectivity of methacrylic acid is 81.3%.
%, And the single flow yield of methacrylic acid was 67.3%.

Examples 2, 3 and Comparative Example 2 A catalyst was prepared and reacted in the same manner as in Example 1 except for the addition ratio of the component (B), the Mo ₁ Zr _0.25 composite oxide. Table 1 shows the results.

Examples 4 and 5 and Comparative Examples 3, 4, and 5
Catalyst preparation and reaction were carried out in the same manner as in Example 1 except for the heat treatment temperature when preparing the Mo ₁ Zr _0.25 composite oxide as the component (B). Table 1 shows the results. Comparative Example 3
Is a comparative example in which a solid pulverized product obtained by drying at 130 ° C. was used as the component (B) without heat treatment.

Examples 6, 7 and Comparative Example 6 Mo ₁ Z
Mo prepared by changing the amount ratio of ammonium paramolybdate and zirconium hydroxide in place of the r _0.25 composite oxide
Catalyst preparation and reaction were carried out in the same manner as in Example 1 except that Mo-Zr composite oxides having different atomic ratios of Zr and Zr were used as component (B). Table 1 shows the results.

Example 8 53.9 parts of zirconium hydroxide and 105 parts of niobium hydroxide were added to 450 parts of an aqueous solution containing 100 parts of ammonium paramolybdate.
After heating to ° C., it was kept at that temperature for 3 hours. The resulting slurry was evaporated to dryness while heating and stirring, and then heated at 130 ° C for 1 hour.
Dried for 6 hours. The obtained solid was pulverized and then heat-treated at 450 ° C. for 5 hours in the air. Composition other than oxygen of the obtained composite oxide was Mo ₁ Zr _{0.6 7} Nb _1.

A catalyst preparation and a reaction were carried out in the same manner as in Example 1 except that the Mo ₁ Zr _0.67 Nb ₁ composite oxide was used as the component (B) instead of the Mo ₁ Zr _0.25 composite oxide. Table 1 shows the results.

Example 9 To 100 parts of ammonium paramolybdate dissolved in 150 parts of pure water was added 8.7 parts of 85% by weight phosphoric acid, and the mixture was heated to 60 ° C. Further, 4.6 parts of copper nitrate dissolved in 20 parts of pure water, 2.8 parts of ammonium metavanadate, and cesium nitrate dissolved in 50 parts of pure water.
6 parts were added, and the obtained slurry was evaporated to dryness while heating and stirring. The obtained solid was dried at 130 ° C. for 16 hours and pulverized. The dried product thus obtained was used as component (A). 100 parts of this component (A) and Mo ₁ as component (B)
They were mixed in a mortar (18.4 parts per 100 parts of molybdenum contained in the component (A)) 10 parts powder of Zr _{0.2 5} composite oxide. The obtained mixed powder is pulverized after pressure molding,
A mesh of 0 to 20 meshes is fractionated and 38
What was calcined at 0 ° C. for 5 hours was used as a catalyst. A reaction was carried out in the same manner as in Example 1 using this catalyst. Table 1 shows the results.

Comparative Example 7 In place of the Mo ₁ Zr _0.25 composite oxide, ammonium paramolybdate was added at 500 ° C. for 3 hours.
A mixture of 10 parts of molybdenum trioxide prepared by heat treatment for one hour and 1.7 parts of zirconium oxide prepared by heat treatment of zirconium hydroxide at 500 ° C. for three hours was used.
Catalyst preparation and reaction were carried out in the same manner as in Example 1 except that the powder pulverized to 4.2 μm was used as the component (B). Table 1 shows the results.

[0033]

[Table 1] T: heat treatment temperature W: weight of component (B) based on 100 parts by weight of molybdenum contained in component (A)

[0034]

According to the present invention, methacrylic acid can be produced in a high yield by oxidizing methacrolein in the gas phase using the catalyst for producing methacrylic acid of the present invention. Further, according to the method for producing a catalyst for producing methacrylic acid of the present invention, such a high-performance catalyst can be produced.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Motomu Ohkita 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory F-term (reference) 4G069 AA03 AA08 BA45A BB06A BB06B BC03A BC05A BC06A BC06B BC10A BC13A BC17A BC19A BC23A BC24A BC25A BC26A BC27A BC31A BC31B BC32A BC35A BC42A BC43A BC51A BC51B BC54A BC54B BC55B BC56A BC58A BC59A BC59B BC60A BC62A BC66A BC67A BD03A BD05A BD07A12 BA12 BA13 BA02 BA06 BA14 BA15 BA19 BA33 BA35 BS10 4H039 CA65 CC30

Claims (5)

[Claims] 1. A catalyst for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation, comprising the following components (A) and (B), wherein the amount of the component (B) is as follows: 1) to 100 parts by weight of molybdenum contained in
A catalyst for producing methacrylic acid, which is 100 parts by weight. Component (A): a solid acid containing at least molybdenum, phosphorus, vanadium and copper Component (B): a composite oxide containing at least molybdenum and zirconium obtained by heat treatment at 300 to 800 ° C. 2. 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,
Represents molybdenum, vanadium, copper and oxygen, where X is antimony, bismuth, arsenic, germanium, tellurium,
Y represents at least one element selected from the group consisting of silver, selenium, silicon, tungsten and boron, and Y is a 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 an atomic ratio of oxygen necessary to satisfy the valence of each component. ) 3. The catalyst for producing methacrylic acid according to claim 1, wherein the component (B) is a composite oxide represented by the following formula (2). Mo _i Zr _j D _k O _l (2) (wherein, Mo, Zr and O represent molybdenum, zirconium and oxygen, respectively, and D is selected from the group consisting of titanium, vanadium, niobium, bismuth, tungsten, chromium and antimony. I, j, k, and l represent the atomic ratio of each element, and when i = 1, j = 0.05 to 20, k = 0 to 10, and l is It 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 a mixture of the precursor of the component (A) and the component (B) is heat-treated at 200 to 500 ° C. Manufacturing method. 5. 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.