WO2017221615A1

WO2017221615A1 - Method for producing methacrylic acid production catalyst, method for producing methacrylic acid, and method for producing methacrylic acid ester

Info

Publication number: WO2017221615A1
Application number: PCT/JP2017/019202
Authority: WO
Inventors: 祐太佐藤; 拓朗渡邉; 雄一田川; 加藤　裕樹
Original assignee: 三菱ケミカル株式会社
Priority date: 2016-06-21
Filing date: 2017-05-23
Publication date: 2017-12-28
Also published as: MY186658A; CN109311005A; JP6814140B2; JP2019122960A; JPWO2017221615A1; KR102242609B1; SA518400526B1; KR20190018513A; KR20210006533A; SG11201809651RA

Abstract

Provided is a catalyst that is inexpensive and enables the production of methacrylic acid with high yield. A method for producing a methacrylic acid production catalyst that contains at least phosphorus and molybdenum and can be used in the production of methacrylic acid by the vapor phase catalytic oxidation of methacrolein with molecular oxygen, said method being characterized by comprising the steps of: (a) mixing and kneading a dried catalyst containing a catalyst component with a solvent to produce a kneaded product; (b) molding the kneaded production to produce a molded article; (c) drying the molded article to produce a dried molded article; and (d) firing the dried molded article to produce the catalyst, wherein at least a portion of the dried molded article produced in step (c) is used as at least a portion of the dried catalyst in step (a).

Description

Method for producing catalyst for producing methacrylic acid, method for producing methacrylic acid, and method for producing methacrylic ester

The present invention relates to a method for producing a catalyst for producing methacrylic acid, a method for producing methacrylic acid, and a method for producing a methacrylic acid ester.

Examples of the catalyst used when producing methacrylic acid by gas phase catalytic oxidation of methacrolein include those containing a heteropoly acid such as molybdophosphoric acid or molybdophosphate as a main component. The catalyst is generally produced by preparing a raw material liquid such as an aqueous solution or an aqueous slurry containing each element constituting the catalyst, drying it to obtain a catalyst dry powder, and calcining it. .

For example, Patent Document 1 proposes a method for producing a catalyst in which a dry product of an aqueous solution or an aqueous slurry containing each element constituting the catalyst is kneaded together with a small amount of a kneaded product obtained by previously kneading the dried product, a liquid, and a binder. ing.

Patent Document 2 proposes a method for producing a catalyst in which a catalyst component containing a heteropolyacid is calcined, powder obtained by sieving is mixed with a catalyst material before molding, and molding is performed.

Patent Document 3 proposes a method for producing a catalyst in which a catalyst component containing molybdenum and bismuth is calcined, pulverized is primary molded, the primary molded product is pulverized again, and then secondary molded.

JP 2012-206107 A JP 2009-279555 A Japanese Patent Laid-Open No. 2001-205090

However, all of the catalysts obtained by the methods described in Patent Documents 1 to 3 have insufficient methacrylic acid yields, and further improvements are desired. Moreover, cost reduction of the catalyst is desired. An object of the present invention is to provide a low-cost catalyst having a high methacrylic acid yield, a method for producing methacrylic acid using the catalyst, and a method for producing a methacrylic acid ester.

The above-mentioned problems are solved by the following present inventions [1] to [11].

[1] A method for producing a catalyst for producing methacrylic acid containing at least phosphorus and molybdenum, which is used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(A) a step of mixing and kneading a dried catalyst product containing a catalyst component and a solvent to obtain a kneaded product;
(B) forming the kneaded product to obtain a molded product;
(C) drying the molded product to obtain a molded product after drying;
(D) baking the molded article after drying to obtain a catalyst;
Including
A method for producing a catalyst for methacrylic acid production, wherein at least a part of the molded article after drying obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a).

[2] The method for producing a methacrylic acid production catalyst according to [1], wherein the methacrylic acid production catalyst contains a heteropolyacid compound containing phosphorus and molybdenum.

[3] The method for producing a catalyst for methacrylic acid production according to [2], wherein the heteropolyacid compound has a composition represented by the following formula (I).

_{_{_{_{P a Mo b V c X d}}}} Y e O f (I)
(In the formula (I), P, Mo, V and O represent phosphorus, molybdenum, vanadium and oxygen, respectively. X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, copper, silver, selenium, silicon and tungsten. And at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, barium, gallium, lanthanum and boron, and Y is at least selected from the group consisting of potassium, rubidium and cesium A, b, c, d, e, and f represent the atomic ratio of each element, and when b = 12, a = 0.1-3, c = 0.01-3, d = 0 to 3, e = 0.01 to 3, and f is the oxygen atomic ratio necessary to satisfy the valence of the element).

[4] The method for producing a catalyst for methacrylic acid production according to any one of [1] to [3], wherein the drying temperature in the step (c) is 20 ° C. or higher and lower than 200 ° C.

[5] The method for producing a catalyst for methacrylic acid production according to any one of [1] to [4], wherein the firing temperature in the step (d) is 200 ° C. or more and 500 ° C. or less.

[6] When at least a part of the post-drying molded product obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a), after the drying defined by the following formula The method for producing a catalyst for methacrylic acid production according to any one of [1] to [5], wherein the usage rate of the molded product is 0.3% by mass or more and 22.0% by mass or less.

Usage rate of molded product after drying (% by mass) = (α / β) × 100
(In the above formula, α represents the solid mass of the dried product obtained in the step (c), and β represents the total solid mass of the catalyst dry powder).

[7] When using at least part of the dried product obtained in the step (c) as at least part of the dried catalyst product in the step (a), the dried product is pulverized. A method for producing a methacrylic acid production catalyst according to any one of [1] to [6].

[8] The catalyst for methacrylic acid production according to [7], wherein the median diameter of the pulverized product obtained by pulverizing the molded product after drying is 50% or less of the median diameter of the molded product after drying before pulverization. Production method.

[9] The method for producing a catalyst for producing methacrylic acid according to any one of [1] to [8], wherein the molding in the step (b) is extrusion molding.

[10] A catalyst for producing methacrylic acid is produced by the method according to any one of [1] to [9], and methacrolein is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid. A method for producing methacrylic acid for producing methacrylic acid.

[11] A method for producing a methacrylic acid ester obtained by esterifying methacrylic acid produced by the method for producing methacrylic acid according to [10].

According to the present invention, a catalyst can be produced at low cost by effectively using the molded product after drying as a catalyst raw material, and the obtained catalyst exhibits a high methacrylic acid yield. Moreover, the manufacturing method of methacrylic acid using this catalyst and the manufacturing method of methacrylic acid ester can be provided.

[Method for producing catalyst for producing methacrylic acid]
The method for producing a catalyst for producing methacrylic acid (hereinafter also referred to as catalyst) according to the present invention contains at least phosphorus and molybdenum used when producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. It is a manufacturing method of the catalyst for methacrylic acid manufacture, Comprising: The following processes are included.
(A) a step of mixing and kneading a dried catalyst product containing a catalyst component and a solvent to obtain a kneaded product,
(B) forming the kneaded product to obtain a molded product;
(C) a step of drying the molded product to obtain a molded product after drying, and (d) a step of firing the molded product after drying to obtain a catalyst.

In the method according to the present invention, at least a part of the post-drying molded product obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a). As a result, by once kneading the dried molded product once dried with a solvent and applying a shearing force, the pores present in the molded product after drying change, and a pore distribution particularly favorable for methacrylic acid production is formed in the catalyst. I guess that.

The catalyst produced by the method according to the present invention preferably contains a heteropolyacid compound containing phosphorus and molybdenum from the viewpoint of obtaining a high yield of methacrylic acid. The composition of the heteropolyacid compound is not particularly limited as long as it includes at least phosphorus and molybdenum, but it is preferable to have a composition represented by the following formula (I) from the viewpoint of higher methacrylic acid yield.

_{_{_{_{P a Mo b V c X d}}}} Y e O f (I)
In the formula (I), P, Mo, V and O represent phosphorus, molybdenum, vanadium and oxygen, respectively. X is selected from the group consisting of antimony, bismuth, arsenic, germanium, zirconium, tellurium, copper, silver, selenium, silicon, tungsten, iron, zinc, chromium, magnesium, tantalum, cobalt, barium, gallium, lanthanum and boron. At least one element is indicated. Y represents at least one element selected from the group consisting of potassium, rubidium and cesium. a, b, c, d, e and f indicate atomic ratios of the respective elements. When b = 12, a = 0.1 to 3, c = 0.01 to 3, d = 0 to 3, e = 0.01 to 3 and f is the oxygen atom ratio necessary to satisfy the valence of the element. The composition of the catalyst is a value calculated based on the amount of each raw material charged at the time of catalyst preparation.

(Process (a))
In the step (a), a dried catalyst material containing a catalyst component and a solvent are mixed and kneaded to obtain a kneaded product. In this step, as described later, at least a part of the molded article after drying obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a).

The dried catalyst product containing the catalyst component can be obtained, for example, by drying a solution or slurry containing the catalyst component (hereinafter also referred to as catalyst raw material solution or slurry). For example, a raw material compound of a catalyst component of a catalyst for methacrylic acid production containing at least phosphorus and molybdenum is dissolved or suspended in an appropriately selected solvent to prepare a catalyst raw material solution or slurry, and the obtained catalyst raw material solution or slurry is A dried catalyst product can be obtained by drying. The method for preparing the catalyst raw material solution or slurry is not particularly limited, and for example, it can be prepared by a precipitation method, an oxide mixing method, or the like.

The raw material compound of the catalyst component used for the preparation of the catalyst raw material solution or slurry is not particularly limited, and nitrate, carbonate, acetate, ammonium salt, oxide, halide, oxo acid, oxo of each constituent element of the catalyst Acid salts and the like can be used alone or in combination of two or more. Examples of the molybdenum source compound include molybdenum oxide such as molybdenum trioxide, and ammonium molybdate such as ammonium paramolybdate and ammonium dimolybdate. Examples of the phosphorus source compound include phosphoric acid, phosphorus pentoxide, and ammonium phosphate. Examples of the vanadium raw material compound include ammonium metavanadate, vanadium pentoxide, and vanadyl oxalate. As the raw material compound of the catalyst component, one kind may be used for each element constituting the catalyst component, or two or more kinds may be used in combination. The compounding ratio of the raw material compounds of the constituent elements of the catalyst is preferably a compounding ratio that satisfies the composition represented by the formula (I).

Examples of the solvent used for preparing the catalyst raw material solution or slurry include water, ethyl alcohol, and acetone. These may use 1 type and may use 2 or more types together. Among these, it is preferable to use water.

The catalyst raw material solution or slurry preferably has a liquid content of 5.0% by mass or less by drying. Various methods can be used as the drying method. For example, an evaporating and drying method, a spray drying method, a drum drying method, an air current drying method and the like can be mentioned. Among these, the spray drying method in which the particle shape of the dried catalyst is uniform is preferable. The model of the dryer used for drying, the temperature during drying, the atmosphere, etc. are not particularly limited, but the drying temperature is preferably in the range of 90 to 500 ° C.

In addition, you may use only the molded article after the drying obtained by the process (c) mentioned later as a catalyst dry substance containing the said catalyst component.

The solvent mixed and kneaded with the catalyst dry product is not particularly limited, but water or an organic solvent is preferable. Examples of the organic solvent include lower alcohols such as methyl alcohol, ethanol, propyl alcohol, butyl alcohol, and isopropanol, acetone, dimethyl ether, diethyl ether, methyl ethyl ketone, and ethyl acetate. One kind of these solvents may be used, or two or more kinds of solvents may be used in combination. The solvent preferably contains at least an organic solvent. The amount of the solvent used is appropriately selected depending on the type of the dried catalyst, the shape of the particles, and the type of the solvent, but is 5.0 to 40.0 relative to the total amount of the dried catalyst and the solvent of 100.0% by mass. It is preferable that it is mass%. Since the amount of the solvent used is 5.0% by mass or more, extrusion molding can be performed more smoothly, so that the particles of the dried catalyst are less likely to be crushed, and the pores effective for reaction in the obtained molded product Tend to increase. On the other hand, when the amount of the solvent used is 40.0% by mass or less, the adhesion during molding is reduced and the handleability is improved. Further, since the molded product becomes denser, the strength of the molded product tends to be improved.

In step (a), it is preferable to further mix and knead a molding aid in addition to the catalyst dried product containing the catalyst component and the solvent. Although it does not specifically limit as a shaping | molding adjuvant, A graphite, diatomaceous earth, glass fiber, ceramic fiber, an organic binder, etc. are mentioned. Among these, an organic binder is preferable as the molding aid. As the organic binder, cellulose is preferable, and examples thereof include methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and hydroxybutyl methyl cellulose. These may be used alone or in combination of two or more. The amount of the molding aid used is appropriately selected depending on the type of the catalyst dried product, the shape of the particles, and the type of the solvent. From the viewpoint of the moldability of the kneaded product and the strength of the molded product, the total amount of the catalyst dried product is 100. The content is preferably 0.05 to 15% by mass with respect to 0% by mass.

In step (a), the dried catalyst and the solvent are mixed and then kneaded. Thereby, a kneaded material is obtained. By kneading before the step (b) described later, it is possible to control the pore size to a pore size effective for the reaction.

Kneading can be performed using a kneading apparatus. The kneading apparatus is not particularly limited, and a batch type kneader using a double-arm type stirring blade, a continuous kneading machine such as a shaft rotation reciprocating type or a self-cleaning type can be used. From the viewpoint of confirming the above, a batch-type kneader is preferable. Moreover, the end point of kneading | mixing is a time of mixing until it will be in the state which can be shape | molded, and it is usually judged by time, visual observation, or a touch.

(Process (b))
In the step (b), the kneaded product is molded to obtain a molded product. It does not specifically limit as a shaping | molding method, Rolling granulation, tableting shaping | molding, extrusion molding, etc. are mentioned. Among these, extrusion molding is preferable from the viewpoint of maintaining the pore diameter effective in the reaction formed in the kneading in the step (a). When performing extrusion molding, an auger type extrusion molding machine, a piston type extrusion molding machine, or the like can be used. The shape of the molded product is not particularly limited, and examples thereof include a ring shape, a columnar shape, a honeycomb shape, and a star shape.

(Process (c))
In the step (c), the molded product is dried to obtain a molded product after drying. In the step (c), drying means holding at a temperature of 20 ° C. or higher and lower than 200 ° C. to remove the solvent component contained in the molded product. The drying method is not particularly limited, and a generally known drying method is arbitrarily used. The drying conditions are not particularly limited, and may be an air atmosphere or a nitrogen atmosphere. About drying temperature, the range of 50 to 180 degreeC is preferable, and the range of 80 to 150 degreeC is more preferable.

(Use of molded product after drying as dried catalyst in step (a))
In the present invention, in the step (a), at least a part of the post-drying molded product obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a). At this time, once dried, the molded product after drying is kneaded with a solvent and a shear force is applied to change the pores present in the molded product after drying. It is thought that it is formed.

Use of the post-drying molded product defined by the following formula when using at least a part of the post-drying molded product obtained in the step (c) as at least a part of the dried catalyst product of the step (a) The rate is preferably 0.3% by mass or more and 22.0% by mass or less.

Usage rate of molded product after drying (% by mass) = (α / β) × 100
Here, α is the solid content mass of the post-drying molded product obtained in the step (c), and β is the total solid mass of the catalyst dry powder. Solid content mass shows the mass in a state whose liquid content is 5.0 mass% or less.

It is considered that a pore distribution particularly preferable for methacrylic acid production is formed when the usage rate of the molded product after drying is 0.3% by mass or more. Moreover, when the usage rate of the molded product after drying is 22.0% by mass or less, the moldability in the step (b) is improved, and the mechanical strength of the obtained molded product is improved. The use rate of the molded product after drying is more preferably 0.7% by mass or more and 20.0% by mass or less, and further preferably 5.0% by mass or more and 18.0% by mass or less. In the present invention, the post-drying molded product usage rate may be 100.0% by mass.

When using at least a part of the molded product after drying obtained in the step (c) as at least a part of the dried catalyst product in the step (a), the molded product after drying is pulverized and used. It is preferable. The moldability in the said process (b) can be improved by grind | pulverizing the molded article after the said drying previously, and mixing in the state which made the particle size small. The method for pulverizing the molded product after drying is not particularly limited, and a pulverizer, a pulverizer, a fine pulverizer, and the like can be used, but the pulverized pulverized product can have a smaller particle size. Is preferably used.

The median diameter of a pulverized product obtained by pulverizing the molded product after drying (hereinafter also referred to as pulverized product after dried) is preferably 50% or less of the median diameter of the molded product after drying before pulverization. 40% or less, more preferably 20% or less. When the median diameter of the pulverized molded product after drying is 50% or less of the median diameter of the molded product after drying before pulverization, the moldability in the step (b) is improved. The lower limit of the range of the median diameter ratio is not particularly limited, but may be 5% or more, for example.

Here, the median diameter is a value obtained by a sieving method. Specifically, after sieving 50 g of a sample using a sieve and a saucer having openings of 4750 μm, 4000 μm, 3350 μm, 2800 μm, 2000 μm, 1180 μm, 600 μm, 212 μm, and 106 μm, each sieve is formed on a sieve The mass of the remaining particles is measured. From the fine powder side, the opening of the sieve with an integrated mass ratio of 50% or more is x ₁ μm, the opening of the sieve that is one step larger than x ₁ μm is x ₂ μm, and the mass ratio from the tray to the sieve of x ₁ μm When the integration is Q ₁ % and the mass ratio from the saucer to the X ₂ μm sieve is Q ₂ %, the median diameter is calculated by the following formulas (II) and (III).

Median diameter = 10 ^Z (II)
Z = log (x ₂ ) + (log (x ₁ ) −log (x ₂ )) × (50−Q ₂ ) / (Q ₁ −Q ₂ ) (III).

(Process (d))
In step (d), the molded article after drying is fired to obtain a catalyst. In the present invention, calcination refers to a process in which a catalytic active point is expressed by heat treatment at 200 ° C. or more and 500 ° C. or less. The firing conditions are not particularly limited, but firing is preferably performed under the flow of an oxygen-containing gas such as air or under an inert gas flow. Here, the inert gas refers to a gas that does not decrease the catalytic activity, and examples thereof include nitrogen, carbon dioxide gas, helium, and argon. These may use 1 type and may mix and use 2 or more types. The firing temperature is preferably 250 ° C. or higher and 450 ° C. or lower.

[Method for producing methacrylic acid]
The method for producing methacrylic acid according to the present invention comprises producing a methacrylic acid production catalyst by the method according to the present invention, and subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen in the presence of the methacrylic acid production catalyst. A method for producing an acid. According to this method, methacrylic acid can be produced with high yield.

It is preferable to use a raw material gas containing methacrolein and molecular oxygen as the raw material. The concentration of methacrolein in the raw material gas when the raw material gas is brought into contact with the catalyst obtained by the method according to the present invention can be varied in a wide range, but is preferably 1 to 20% by volume, and preferably 3 to 10% by volume. More preferred. The molecular oxygen concentration in the raw material gas is preferably 0.5 to 4.0 moles, more preferably 1.0 to 3.0 moles per mole of methacrolein.

The raw material gas may be diluted by adding an inert gas such as nitrogen or carbon dioxide. The source gas preferably contains water vapor. By performing the reaction in the presence of water, methacrylic acid can be produced in a higher yield. The concentration of water vapor in the raw material gas is preferably 0.1 to 50.0% by volume, more preferably 1.0 to 40.0% by volume. The reaction pressure is preferably atmospheric pressure (atmospheric pressure) to 5 atmospheres. The reaction temperature is preferably 230 to 500 ° C, more preferably 250 to 400 ° C.

[Method for producing methacrylate ester]
In the method for producing a methacrylic acid ester according to the present invention, methacrylic acid obtained by the method according to the present invention is esterified. According to this method, a methacrylic acid ester can be obtained using methacrylic acid obtained from methacrolein. Examples of the alcohol to be reacted with methacrylic acid include methanol, ethanol, isopropanol, n-butanol, isobutanol and the like. Examples of the resulting methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. The reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The reaction temperature is preferably 50 to 200 ° C.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. “Parts” in Examples and Comparative Examples means parts by mass. The molar ratio of the catalyst composition was calculated based on the charged amount of each raw material at the time of catalyst preparation. Quantitative analysis of raw material gas and products in the production of methacrylic acid was performed using gas chromatography. In addition, the reaction rate of methacrolein, the selectivity of the methacrylic acid to produce | generate, and the single flow yield of methacrylic acid are defined as follows.

Reaction rate (%) of methacrolein (MAL) = (B / A) × 100
Methacrylic acid (MAA) selectivity (%) = (C / B) × 100
Single flow yield (%) of methacrylic acid (MAA) = (C / A) × 100
Here, A is the number of moles of methacrolein supplied, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced.

The falling powder rate, which is an index of mechanical strength, was measured by the following method. After drying, 100 g of the molded product is dropped from the upper opening of a stainless steel cylinder having an inner diameter of 27.5 mm and a length of 6 m that is installed so that the longitudinal direction is vertical and the lower opening is closed with a stainless steel plate. And filled into a cylinder. Of the molded product after drying that was recovered by opening the lower opening, the weight of the molded product that did not pass through a sieve having an opening of 1 mm was defined as Dg, and the falling powder rate was calculated by the following formula. The smaller the falling powder rate, the higher the mechanical strength, and the higher the falling powder rate, the lower the mechanical strength. In addition, the fall powdering rate in an Example is an average value of the fall powdering rate measured with respect to each after-drying molded product, after manufacturing the molded product after drying 10 times on the same conditions.

Falling powder rate (%) = {(100−D) / 100} × 100.

[Example 1]
1000 parts of molybdenum trioxide, 54 parts of ammonium metavanadate, 67 parts of 85 mass% phosphoric acid aqueous solution and 11 parts of copper nitrate are dissolved in 4000 parts of pure water, and the temperature is raised to 95 ° C. while stirring, and the liquid temperature is 95. The mixture was stirred for 3 hours while maintaining the temperature. After cooling to 90 ° C., a solution prepared by dissolving 135 parts of cesium nitrate and 6 parts of potassium nitrate in 200 parts of pure water was added and stirred for 15 minutes while stirring using a rotary blade stirrer. Next, a solution obtained by dissolving 92 parts of ammonium carbonate in 200 parts of pure water was added, and the mixture was further stirred for 20 minutes. This catalyst raw material slurry was dried using a spray drier so that the liquid content was 5.0% by mass or less, and a dried catalyst A was obtained. 25 parts of hydroxypropylcellulose was added to 500 parts of the dried catalyst A thus obtained, and dry mixed. 40 parts of pure water and 60 parts of ethanol were mixed here and kneaded until it became clay-like with a kneader, and kneaded material A was obtained. Thereafter, the irregularly kneaded product A was extruded using a piston-type extruder having a cylinder and an 8-hole die to obtain a molded product A having a median diameter of 4359 μm. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. The molded product A was dried at 105 ° C. for 2 hours under a nitrogen atmosphere to reduce the liquid content to 5.0% by mass or less, and a molded product A was obtained after drying. This dried molded product A was pulverized using a shear type crusher to obtain a pulverized molded product after drying having a median diameter of 498 μm.

497.5 parts of the dried catalyst product A obtained previously, 24.87 parts of hydroxypropylcellulose, and 2.63 parts of the pulverized product after drying were dry mixed. The dried catalyst A and the pulverized product after drying correspond to the dried catalyst B. That is, the pulverized product after drying was used as part of the dried catalyst B. 40 parts of pure water and 60 parts of ethanol were mixed with the obtained mixture and kneaded until it became clay-like with a kneader to obtain a kneaded product B. Thereafter, the irregularly shaped kneaded product B was extruded using a piston-type extruder having a cylinder to obtain a molded product B having a median diameter of 4365 μm. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. The molded product B was dried at 105 ° C. for 2 hours in a nitrogen atmosphere, and a molded product B was obtained after drying. As a result of measuring the falling powder rate of the molded product B after drying, it was 0.28%. Subsequently, the obtained molded article B after drying was calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst. The composition of this catalyst (excluding oxygen atoms) was P ₁ Mo ₁₂ V _0.8 Cu _0.1 Cs _1.2 K _0.1 .

This catalyst is filled in a reaction tube, and a reaction is performed through a mixed gas consisting of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of steam and 55% by volume of nitrogen at a reaction temperature of 300 ° C. and a contact time of 3.4 seconds. Went. As a result, the methacrolein reaction rate was 32.5%, the methacrylic acid selectivity was 92.2%, and the methacrylic acid single stream yield was 30.0%. The results are shown in Table 1. In Table 1, the number of clogged die holes in extrusion molding for 1 hour in continuous is the number of clogged die holes in extrusion molding of kneaded product B in Examples 1 to 8 and Comparative Example 2, and the kneaded product in Comparative Example 1. The number of clogged die holes in the extrusion molding of A is shown.

[Comparative Example 1]
In Example 1, the pulverization of the molded product A after drying and the pulverized product of the molded product after drying were not performed. That is, the molded product A after drying in Example 1 was calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst, and the reaction was performed. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product A after drying, it was 0.12%. The results are shown in Table 1.

[Example 2]
Example 1 except that the mixed amount of the catalyst dried product A, hydroxypropyl cellulose, and the pulverized product after drying was changed to 495 parts, 24.75 parts, and 5.25 parts, respectively. After drying by the method, a molded product B was produced. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.16%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 3]
Example 1 except that the mixed amount of the catalyst dried product A, hydroxypropyl cellulose, and the pulverized product after drying was changed to 485 parts, 24.25 parts, and 15.75 parts, respectively. After drying by the method, a molded product B was produced. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.11%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 4]
Dried in the same manner as in Example 1 except that the mixed amount of the dried catalyst A, hydroxypropylcellulose, and the pulverized product after drying was changed to 420 parts, 21 parts, and 84 parts, respectively. Post-molded product B was manufactured. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.24%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 5]
Dried in the same manner as in Example 1 except that the mixed amount of the dried catalyst A, hydroxypropylcellulose, and the pulverized product after drying was changed to 400 parts, 20 parts, and 105 parts, respectively. Post-molded product B was manufactured. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.29%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 6]
Example 1 except that the mixed amount of the catalyst dried product A, hydroxypropyl cellulose, and the pulverized product after drying was changed to 385 parts, 19.25 parts, and 120.75 parts, respectively. After drying by the method, a molded product B was produced. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.48%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 7]
Dried in the same manner as in Example 1 except that the mixed amount of the dried catalyst A, hydroxypropylcellulose, and the pulverized product after drying was changed to 0 parts, 0 parts, and 525 parts, respectively. Post-molded product B was manufactured. At this time, the clogging of the die in the extrusion molding for 1 hour was 1 hole. Moreover, it was 0.36% as a result of measuring the fall powdering rate of the obtained molded product B after drying. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Example 8]
A dried product B was produced in the same manner as in Example 1 except that the median diameter of the pulverized product after drying was changed to 2366 μm. At this time, the clogging of the die in the extrusion molding for 1 hour was 2 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.28%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

[Comparative Example 2]
After drying, the molded product A was fired for 5 hours under air flow to obtain a fired molded product. The fired molded product was pulverized using a shear type crusher to obtain a pulverized fired molded product having a median diameter of 498 μm. The same method as in Example 1 except that the mixing amounts of the dried catalyst A, hydroxypropyl cellulose, and the pulverized product of the fired molded article were changed to 485 parts, 24.25 parts, and 15.75 parts, respectively. After drying, a molded product B was produced. At this time, the clogging of the die in the extrusion molding for 1 hour was 0 holes. Moreover, as a result of measuring the fall powdering rate of the obtained molded product B after drying, it was 0.37%. Using this molded product B after drying, a catalyst was produced in the same manner as in Example 1 and reacted. The results are shown in Table 1.

In Examples where the molded product was pulverized after drying and a part of the molded product was mixed with the catalyst dried product, both were compared with Comparative Example 1 where mixing of the molded product after drying and the dried catalyst product was not performed. Methacrylic acid could be produced with high yield. Further, Comparative Example 2 in which not the molded product after drying but the fired molded product was pulverized and a part thereof was mixed with the catalyst dried product had a low methacrylic acid yield compared to the Examples, and a part of the molded product after drying was obtained. It was found that the methacrylic acid yield was improved by mixing with the dried catalyst. In Examples 1 to 5 in which the usage rate of the molded product after drying was 0.3% by mass or more and 22.0% by mass or less, a particularly high methacrylic acid yield was shown. On the other hand, it was found that Example 6 in which the usage rate of the molded product after drying exceeded 22.0% by mass had a higher fall powdering rate and lower mechanical strength than Examples 1-5. In Example 7 where the usage rate of the molded product after drying was 100%, although the yield of methacrylic acid was high, clogging of the die holes in extrusion molding occurred. From the viewpoint of moldability as compared with Examples 1 to 5 It became an inferior catalyst. In Example 8, the ratio of the median diameter of the pulverized product after drying to the pre-grinding product exceeds 50%, clogging of the die holes in extrusion molding occurs, and the moldability is higher than that of Example 1. From this viewpoint, the catalyst was inferior.

This application claims priority based on Japanese Patent Application No. 2016-122583 filed on June 21, 2016, the entire disclosure of which is incorporated herein.

Although the present invention has been described with reference to the exemplary embodiments and examples, the present invention is not limited to the above exemplary embodiments and examples. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

Claims

A method for producing a catalyst for producing methacrylic acid containing at least phosphorus and molybdenum, which is used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(A) a step of mixing and kneading a dried catalyst product containing a catalyst component and a solvent to obtain a kneaded product;
(B) forming the kneaded product to obtain a molded product;
(C) drying the molded product to obtain a molded product after drying;
(D) baking the molded article after drying to obtain a catalyst;
Including
A method for producing a catalyst for methacrylic acid production, wherein at least a part of the molded article after drying obtained in the step (c) is used as at least a part of the dried catalyst product in the step (a).
The method for producing a methacrylic acid production catalyst according to claim 1, wherein the methacrylic acid production catalyst contains a heteropolyacid compound containing phosphorus and molybdenum.
The method for producing a catalyst for methacrylic acid production according to claim 2, wherein the heteropolyacid compound has a composition represented by the following formula (I).
P a Mo b V c X d Y e O f (I)
(In the formula (I), P, Mo, V and O represent phosphorus, molybdenum, vanadium and oxygen, respectively. X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, copper, silver, selenium, silicon and tungsten. And at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, barium, gallium, lanthanum and boron, and Y is at least selected from the group consisting of potassium, rubidium and cesium A, b, c, d, e, and f represent the atomic ratio of each element, and when b = 12, a = 0.1-3, c = 0.01-3, d = 0 to 3, e = 0.01 to 3, and f is an oxygen atomic ratio necessary to satisfy the valence of the element.)
The method for producing a catalyst for methacrylic acid production according to any one of claims 1 to 3, wherein a drying temperature in the step (c) is 20 ° C or higher and lower than 200 ° C.
The method for producing a catalyst for producing methacrylic acid according to any one of claims 1 to 4, wherein the firing temperature in the step (d) is 200 ° C or higher and 500 ° C or lower.
Use of the post-drying molded product defined by the following formula when using at least a part of the post-drying molded product obtained in the step (c) as at least a part of the dried catalyst product of the step (a) The method for producing a catalyst for methacrylic acid production according to any one of claims 1 to 5, wherein the rate is 0.3 mass% or more and 22.0 mass% or less.
Usage rate of molded product after drying (% by mass) = (α / β) × 100
(In the above formula, α represents the solid mass of the molded article after drying obtained in the step (c), and β represents the total solid mass of the catalyst dry powder.)
When using at least a part of the molded product after drying obtained in the step (c) as at least a part of the dried catalyst product in the step (a), the molded product after drying is pulverized and used. The manufacturing method of the catalyst for methacrylic acid manufacture of any one of Claim 1 to 6.
The method for producing a catalyst for methacrylic acid production according to claim 7, wherein the median diameter of the pulverized product obtained by pulverizing the molded product after drying is 50% or less of the median diameter of the molded product after drying before pulverization.
The method for producing a catalyst for methacrylic acid production according to any one of claims 1 to 8, wherein the molding in the step (b) is extrusion molding.
A catalyst for producing methacrylic acid is produced by the method according to any one of claims 1 to 9, and methacrolein is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid to obtain methacrylic acid. A method for producing methacrylic acid to be produced.
The manufacturing method of the methacrylic acid ester which esterifies the methacrylic acid manufactured by the manufacturing method of the methacrylic acid of Claim 10.