JP2003010691A - Method for producing catalyst for producing methacrylic acid and method for producing methacrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a catalyst for producing methacrylic acid having high activity and high selectivity. A in the general formula _{(I) P a Mo b V} c X d Y e O f (I) ( wherein, P, Mo, V, O each phosphorus, molybdenum, vanadium, oxygen, X is potassium, rubidium,
Cesium, thallium, etc., Y is copper, arsenic, antimony,
Boron, silver, bismuth, iron, cobalt, lanthanum, cerium, etc., a, b, c, d, e, and f are P, M, respectively.
Represents the atomic ratio of o, V, X, Y, O. When producing a catalyst for the production of methacrylic acid such as a Keggin-type heteropolyacid salt having the composition represented by the following formula), an aqueous solution or an aqueous slurry obtained by mixing catalyst raw materials in water is dried, then molded,
The obtained molded body is placed in an atmosphere having a relative humidity of 10 to 60% for 4 hours.
Treat at 0 to 100 ° C for 0.5 to 10 hours, then bake.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to methacrolein,
The present invention relates to a method for producing a catalyst for producing methacrylic acid, which is used when a methacrylic acid raw material such as isobutyraldehyde, isobutane, and isobutyric acid is subjected to a gas phase catalytic oxidation reaction to produce methacrylic acid.

[0002]

2. Description of the Related Art As a catalyst used for the production of methacrylic acid by vapor-phase catalytic oxidation of methacrolein or the like, it is known that a catalyst composed of heteropolyacid or a salt thereof is effective. Many reports have been made on the structure, physical properties, etc., and manufacturing method. The method for producing the catalyst usually comprises steps such as preparation of a raw material mixture solution, drying, molding, and calcination.
Many studies have been made on the types of additives. For example, JP-A-55-73347 describes a method of adding an organic substance such as cellulose or polyvinyl alcohol, and JP-A-4-368737 discloses an average particle diameter of 0.01 to 10 μm. A method for adding a high molecular weight organic compound such as polymethylmethacrylate is described,
Japanese Patent Laid-Open No. 10-244160 discloses an average particle size of 0.1.
A method of adding powder of carbonic acid compound having a size of ˜100 μm is described.

[0003]

However, the catalyst obtained by the conventional method is not always satisfactory in terms of reaction activity and selectivity in the production of methacrylic acid, and the object of the present invention is to achieve higher activity. And to provide a method for producing a catalyst for producing methacrylic acid having high selectivity.

[0004]

Means for Solving the Problems As a result of earnest studies, the inventors of the present invention have found that in the production of P-Mo-V catalysts, optimization of the molding process as in the conventional method was not sufficient. ,
It was found that a catalyst for producing methacrylic acid having high activity and high selectivity can be produced by subjecting the formed article obtained through the molding step to a specific treatment and then firing, and completed the present invention. Came to do.

That is, the present invention is a method for producing a catalyst for producing methacrylic acid containing phosphorus, molybdenum and vanadium, wherein an aqueous solution or aqueous slurry prepared by mixing catalyst raw materials in water is dried and then molded, The obtained molded body is 40 to 100 ° C. in an atmosphere of 10 to 60% relative humidity.
The method for producing a catalyst for producing methacrylic acid, wherein the catalyst is treated for 0.5 to 10 hours and then calcined. The present invention also relates to a method for producing methacrylic acid using the catalyst thus obtained.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The catalyst for producing methacrylic acid, which is the object of the present invention, is
Containing phosphorus, molybdenum and vanadium,
Preferably, it represents the general formula (I) in _{P a Mo b V c X d} Y e O f (I) ( wherein, P, Mo, V and O represent phosphorus, molybdenum, vanadium and oxygen, X is potassium, Representing at least one element selected from rubidium, cesium and thallium, Y represents at least one element selected from copper, arsenic, antimony, boron, silver, bismuth, iron, cobalt, lanthanum and cerium.
b, c, d, e and f are P, Mo, V, X,
When the atomic ratio of Y and O is represented and b = 12, a,
c, d, and e each independently have a value of 3 or more, which is greater than 0, and f is a value determined by the oxidation state and atomic ratio of each element other than oxygen. ) Consisting of a Keggin-type heteropolyacid salt having the composition shown in FIG. Above all,
Those that require cesium as the X element are preferable, and those that require copper and antimony as the Y element are preferable.

As the raw material of the above catalyst, a compound containing each element contained in the above catalyst, such as oxo acid, oxo acid salt, oxide, nitrate, carbonate, hydroxide, halide, etc., of each element is usually used. Is used in a proportion that satisfies the desired atomic ratio. For example, as a compound containing phosphorus,
Phosphoric acid, phosphate, etc. are used. As the compound containing molybdenum, molybdic acid, molybdate, molybdenum oxide, molybdenum chloride, etc. are used. As the compound containing vanadium, vanadic acid, vanadate, oxidation Vanadium, vanadium chloride, etc. are used. When the catalyst contains the X element in the above general formula (I), oxides, nitrates, carbonates, hydroxides, halides and the like are used as the compound containing the X element, and the catalyst is the above general formula (I When the Y element in I) is included, as the compound containing the Y element, oxo acid, oxo acid salt, nitrate, carbonate, hydroxide, halide or the like is used. When the composition of the general formula (I) is used, each element other than oxygen in the general formula (I) satisfies the above-mentioned proportions of a, b, c, d and e in the general formula (I). The compound may be used.

An aqueous solution or aqueous slurry is obtained by mixing these catalyst raw materials in water, and the aqueous solution or aqueous slurry is preferably treated at 80 ° C. or higher for 1 hour or longer. Further, the aqueous solution or the aqueous slurry preferably contains ammonium root.

A Dawson-type heteropolyacid salt molded article can be obtained by molding the above aqueous solution or aqueous slurry after drying. Drying can be carried out using a kneader, a box dryer, a drum-type aeration dryer, a spray dryer, a flash dryer, or the like. The dried product obtained by drying is usually formed into a ring shape, a pellet shape, a spherical shape, a cylindrical shape or the like by tableting molding, extrusion molding or the like. At this time, in order to increase the strength, the dried material is mixed with inorganic fibers such as ceramic fibers and glass fibers,
It is preferably subjected to molding.

Further, it is preferable that the molded body contains 10% by weight or more of ammonium nitrate. In order to do so, the amount of ammonium root contained in the catalyst raw material and ammonium nitrate produced from nitrate root is taken into consideration. Then, a necessary amount of ammonium nitrate or a compound that produces ammonium nitrate such as nitric acid or ammonia may be added at the time of preparing the above-mentioned aqueous solution or aqueous slurry, or may be added to the dried product at the time of molding. The content of ammonium nitrate in the molded product is more preferably 15% by weight or more, and preferably 40% by weight or less from the viewpoint of the strength of the catalyst.

The obtained molded product is subjected to relative humidity of 10 to 60%.
Under an atmosphere of 40 to 100 ° C. for 0.5 to 10 hours. The treatment may be performed, for example, in a temperature-controlled or humidity-controlled tank, or may be performed by blowing a temperature-controlled or humidity-controlled gas onto the molded body. Air is usually used as the atmospheric gas for the treatment, but an inert gas such as nitrogen may be used. The molded product after this treatment usually contains 0.5 to 5% by weight of water.

If the relative humidity during the above treatment is too low, the selectivity of the catalyst obtained is not sufficient, and if it is too high, the activity of the catalyst obtained is not sufficient, and the strength of the molded body after the treatment is not sufficient. , The handling becomes worse. Further, even if the treatment temperature is too low or too high, the selectivity of the obtained catalyst is not sufficient. Furthermore, if the treatment time is too long, the activity of the obtained catalyst is not sufficient, and if it is too short, the selectivity of the obtained catalyst is not sufficient.

The catalyst is obtained by calcining the molded body after the above treatment, and the calcining is carried out, for example, in air at 350 to 40.
It may be performed at 0 ° C. or at 400 to 500 ° C. in an inert gas such as nitrogen. In addition, after firing in an inert gas, 400 ° C in air if necessary.
Firing may be performed below. By the above firing, the amount of oxygen (O) as a chemical component constituting the catalyst becomes an amount determined by the oxidation state and atomic ratio of each element other than oxygen in the catalyst.

The catalyst obtained as described above has excellent activity and selectivity as a catalyst for producing methacrylic acid,
Methacrylic acid can be produced in high yield by catalytically oxidizing a raw material compound such as methacrolein, isobutyraldehyde, isobutane, and isobutyric acid with molecular oxygen using the catalyst. The production is usually carried out by charging a fixed bed multitubular reactor with a catalyst and passing a raw material gas containing a raw material compound and oxygen through the reactor, but a reaction type such as a fluidized bed or a moving bed is adopted. Is also possible. Air is usually used as the oxygen source, and nitrogen, carbon dioxide, carbon monoxide, steam or the like can be used as the raw material compound in the raw material gas and a gas (diluting gas) other than oxygen.

For example, when methacrolein is used as a raw material, the concentration of methacrolein in the raw material gas is usually 1 to 1.
0% by volume, molar ratio of oxygen to methacrolein 1-
5, space velocity 500-5000h ^-1 (standard state standard),
Reaction temperature 250-350 ° C, reaction pressure 0.1-0.3M
It is performed under the condition of Pa. When isobutane is used as a raw material, the concentration of isobutane in the raw material gas is 1 to 85% by volume, the molar ratio of oxygen to isobutane is 0.05 to 4, the space velocity is 400 to 5000 h ^-1 (standard state standard), the reaction temperature is 250 to It is carried out under the conditions of 400 ° C. and a reaction pressure of 0.1 to 1.0 MPa.

[0016]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto.

Examples 1-5, Comparative Examples 1-6 224 kg of ion-exchanged water heated to 40 ° C., 38.2 kg of cesium nitrate, 10.2 kg of copper (II) nitrate trihydrate,
85% by weight phosphoric acid 24.2 kg and 70% by weight nitric acid 2
5.2 kg was dissolved (this is referred to as solution A). 40 ° C
After 297 kg of ammonium molybdate tetrahydrate was dissolved in 330 kg of ion-exchanged water heated to 1, 8.19 kg of ammonium metavanadate was suspended (this is referred to as solution B). Solution A was added dropwise to solution B with stirring, 10.2 kg of antimony trioxide was added, and the mixture was stirred in a sealed container at 120 ° C. for 17 hours. The pH of the obtained slurry was 6.3.

The slurry was dried using a spray dryer. The content of ammonium nitrate in the obtained dry powder was 12% by weight. Add 100 parts by weight of this dry powder to a ceramic fiber [Toshiba Monoflux Co., Ltd.
FIBERFRAX (RFC400-SL] 4 parts by weight, ammonium nitrate 13 parts by weight and ion-exchanged water 1
0 part by weight was added and kneaded, and extrusion-molded into a cylindrical shape having a diameter of 5 mm and a height of 5 mm.

This molded product was treated at the relative humidity and temperature shown in Table 1 for the time shown in Table 1. The content of ammonium nitrate in the molded body after the treatment was 18% by weight. This molded body was heated in an air stream at 250 ° C. for 3 hours, in a nitrogen stream at 435 ° C. for 3 hours, then in an air stream at 390 ° C.
It was calcined at 3 ° C. for 3 hours to obtain a catalyst. The catalyst, P _{1. 5}
It has a composition of Mo ₁₂ V _0.5 Cs _1.4 Cu _0.3 Sb _0.5 , and oxygen (O) exists corresponding to this composition. In Comparative Example 2, the molded product after treatment was low in strength and poor in handleability, so that it could not be subjected to firing and a catalyst could not be obtained.

9 ml of this catalyst was filled in a glass reaction tube having an inner diameter of 15 mm, 4% by volume of methacrolein and 12% of oxygen.
A raw material gas having a composition of vol.%, Steam 16 vol.%, And the balance nitrogen was passed through a reaction tube at a space velocity (standard state standard) of 670 h ⁻¹ to carry out an oxidation reaction of methacrolein at a temperature of 290 ° C. As a result, the methacrolein conversion rate, methacrylic acid selectivity and methacrylic acid yield were as shown in Table 1.

Example 5, Comparative Example 5 100 parts by weight of the dry powder obtained by the same method as in Example 1 was mixed with ceramic fiber [Toshiba Monoflux Co., Ltd.].
FIBERFRAX (RFC400-SL] 4 parts by weight, ammonium nitrate 5 parts by weight and ion-exchanged water 10
Parts by weight were added and kneaded, and extrusion-molded into a cylindrical shape having a diameter of 5 mm and a height of 5 mm. This molded product was treated at the relative humidity and temperature shown in Table 2 for the time shown in Table 2, then in an air stream at 250 ° C. for 3 hours, and in a nitrogen stream at 435 ° C. for 3 hours.
Firing for 3 hours at 390 ° C in an air stream,
A catalyst was obtained. Using this catalyst, the oxidation reaction of methacrolein was carried out in the same manner as in Example 1. as a result,
The methacrolein conversion rate, methacrylic acid selectivity and methacrylic acid yield were as shown in Table 2.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, a catalyst for producing methacrylic acid which is excellent in activity and selectivity can be produced, and methacrylic acid can be produced in high yield using the catalyst.

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[Procedure amendment]

[Submission date] August 26, 2002 (2002.8.2)
6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiaki Ui             Sumitomo Chemical 5-1, Soukai-cho, Niihama-shi, Ehime             Industry Co., Ltd. (72) Inventor Koichi Nagai             Sumitomo Chemical 5-1, Soukai-cho, Niihama-shi, Ehime             Industry Co., Ltd. F term (reference) 4G069 AA02 AA08 BB01C BB07A                       BB07B BC03A BC05A BC06A                       BC06B BC16A BC25A BC26A                       BC26B BC27A BC31A BC31B                       BC32A BC42A BC43A BC54A                       BC54B BC59A BC59B BC66A                       BC67A BD01C BD02C BD03A                       BD07A BD07B CB17 EA02Y                       EB18Y FA01 FB09 FB29                       FB57 FB67 FC04 FC07 FC08                 4H006 AC46 BA02 BA05 BA08 BA12                       BA13 BA14 BA19 BA20 BA27                       BA30 BA31 BA35 BA75 BA81                       BC13 BE30                 4H039 CA65 CC30

Claims (4)

[Claims] 1. A method of producing a catalyst for producing methacrylic acid containing phosphorus, molybdenum and vanadium, which comprises drying an aqueous solution or an aqueous slurry prepared by mixing catalyst raw materials in water, and then shaping the resulting solution. Relative humidity 10-6
A method for producing a catalyst for producing methacrylic acid, which comprises treating at 40 to 100 ° C. for 0.5 to 10 hours in a 0% atmosphere, and then calcining. 2. A methacrylate catalyst for producing general formula _{(I) P a Mo b V} c X d Y e O f (I) ( wherein, P, Mo, V and O respectively phosphorus, molybdenum, vanadium and Represents oxygen, X represents at least one element selected from potassium, rubidium, cesium and thallium, and Y represents at least one element selected from copper, arsenic, antimony, boron, silver, bismuth, iron, cobalt, lanthanum and cerium. Represents an element, a,
b, c, d, e and f are P, Mo, V, X,
When the atomic ratio of Y and O is represented and b = 12, a,
c, d, and e each independently have a value of 3 or more, which is greater than 0, and f is a value determined by the oxidation state and atomic ratio of each element other than oxygen. The production method according to claim 1, which comprises a Keggin-type heteropolyacid salt having the composition shown in (1). 3. The method according to claim 1, wherein ammonium nitrate is present in an amount of 10% by weight or more in a molded body obtained by drying and molding an aqueous solution or an aqueous slurry. 4. An aqueous solution or an aqueous slurry prepared by mixing catalyst raw materials containing phosphorus, molybdenum and vanadium in water is dried and then molded, and the molded body obtained is subjected to an atmosphere of relative humidity of 10 to 60%. 0.5 ~ at 40-100 ° C
Using a catalyst obtained by treating for 10 hours and then calcining,
A method for producing a catalyst for producing methacrylic acid, which comprises subjecting methacrolein, isobutyraldehyde, isobutane or isobutyric acid to a gas phase catalytic oxidation reaction in the presence of this catalyst.