JP2011224482A - Method for manufacturing methacrylic acid producing catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a catalyst molded object reduced in quality irregularity of a methacrylic acid producing catalyst capable of manufacturing methacrylic acid in high yield by applying gaseous phase catalytic oxidation to methacrolein by molecular oxygen.SOLUTION: The method for manufacturing the methacrylic acid producing catalyst includes a process (1) for manufacturing catalytic component particles containing a catalytic component, a process (2) for mixing the catalytic component particles and a liquid with each other to knead them, a process (3) for primarily molding a kneaded product and a secondary molding process (4) for molding the primarily molded product into a final shape by a piston molding machine. The secondary molding pressure P2 of the process (4) is set to a range of (P1-0.2) to (P1-8) MPaG with respect to the primary molding pressure P1 of the process (3).

Description

  The present invention relates to a catalyst used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen (hereinafter referred to as catalyst for producing methacrylic acid), a production method thereof, and methacrylic acid using this catalyst. The present invention relates to a method for producing an acid.

  As a catalyst component for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen, heteropoly acid compounds represented by phosphomolybdic acid are known. In addition, many methods for forming a pore structure in the catalyst have been proposed in order for this catalyst component to effectively act on the gas phase catalytic oxidation reaction.

  Patent Document 1 discloses a primary molding process for producing a primary molded product by molding a mixture of particles containing a catalyst component and a liquid in a method for producing an unsaturated carboxylic acid production catalyst, and a primary molding process. After that, a method for producing a catalyst having a secondary molding step of molding a primary molded product into a final shape by a piston molding machine has been proposed. Patent Document 2 proposes a method for producing a catalyst for producing an unsaturated carboxylic acid in which the pressure during extrusion molding is 1.5 MPa to 8 MPa. However, when used as an industrial catalyst, there is a demand for a production method that further reduces the quality irregularities of the catalyst molded body.

JP 2003-93882 A JP 11-239724 A

  An object of the present invention is to provide a method for producing a methacrylic acid production catalyst capable of producing methacrylic acid in a high yield by vapor-phase catalytic oxidation of methacrolein with molecular oxygen with little quality irregularity of the catalyst molded body. To do.

The present invention relates to a method for producing a catalyst for producing methacrylic acid comprising at least molybdenum and phosphorus as catalyst components, which is used when producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen.
(1) a step of producing catalyst component particles containing a catalyst component;
(2) mixing and kneading the catalyst component particles and liquid;
(3) a primary molding step of primary molding the kneaded product;
(4) including a secondary molding step of molding the primary molded product into a final shape with a piston molding machine,
In addition, the secondary molding pressure P2 in the step (4) is in the range of (P1-0.2) MPaG to (P1-8) MPaG with respect to the primary molding pressure P1 in the step (3). A feature is a method for producing a catalyst for producing methacrylic acid, and a catalyst for producing methacrylic acid obtained by this method.

  The present invention is also a method for producing methacrylic acid, wherein methacrolein is vapor-phase contact oxidized with molecular oxygen in the presence of the catalyst for producing methacrylic acid.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method with few quality spots of the catalyst molded object of the catalyst for methacrylic acid production which can manufacture methacrylic acid in a high yield by carrying out the gas phase catalytic oxidation of methacrolein with molecular oxygen can be provided.

  The catalyst of the present invention is a catalyst for producing methacrylic acid, which is produced by a production method to be described later. When producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein as a reaction raw material with molecular oxygen. It is used.

  The composition of the catalyst component constituting the catalyst of the present invention can be appropriately selected according to the target catalyst for producing methacrylic acid. The catalyst for producing methacrylic acid, which is the object of the present invention, is not particularly limited as long as it contains at least molybdenum and phosphorus as catalyst components, but preferably has a composition represented by the following formula (A). is there.

_{P a Mo b V c Cu d} X e Y f Z g O h (A)
In the formula (A), P, Mo, V, Cu and O each represent phosphorus, molybdenum, vanadium, copper and oxygen, and X is at least one element selected from the group consisting of arsenic, antimony and tellurium Y is selected from the group consisting of bismuth, germanium, zirconium, silver, selenium, silicon, tungsten, boron, iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum At least one element is represented, and Z represents at least one element selected from the group consisting of potassium, rubidium, and cesium. a, b, c, d, e, f, g, and h represent the atomic ratio of each element. When b = 12, a = 0.1-1, c = 0.01-3, d = 0. 01-2, e is 0-3, f = 0-3, g = 0.01-3, and h is the atomic ratio of oxygen necessary to satisfy the valence of each element.

  The method for producing a catalyst for producing methacrylic acid of the present invention includes (1) a step of producing catalyst component particles containing a catalyst component, (2) a step of mixing and kneading the catalyst component particles and a liquid, and (3 ) A primary molding step of primary molding the kneaded product, (4) a secondary molding step of molding the primary molded product into a final shape with a piston molding machine, and usually (5) drying the molded body and Manufactured through a heat treatment step.

  In the step (1), first, a raw material compound of a catalyst component of a catalyst for producing methacrylic acid is dissolved or suspended in an appropriately selected solvent to prepare a mixed solution or slurry containing at least molybdenum and phosphorus. The method for preparing the mixed solution or slurry is not particularly limited, and examples thereof include known methods such as a precipitation method and an oxide mixing method.

  The catalyst raw material used for the preparation of the mixed solution or slurry is not particularly limited, and it is used in combination with nitrate, carbonate, acetate, ammonium salt, oxide, halide, oxo acid, oxo acid salt, etc. of each constituent element of the catalyst. can do. Examples of the molybdenum raw material include molybdenum oxides such as molybdenum trioxide; and ammonium molybdates 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. The raw material compound of the catalyst component may be used alone or in combination of two or more for each element constituting the catalyst component.

Examples of the solvent to be used include water, ethyl alcohol, acetone and the like, but it is preferable to use water.
The method of drying the mixed solution or slurry thus produced is not particularly limited. For example, a method of drying using a spray dryer, a method of drying using a slurry dryer, or a method of drying using a drum dryer. The method of evaporating to dryness can be applied. In these, since a particle | grain is obtained simultaneously with drying and the shape of the particle | grains obtained is in order, it is preferable to use a spray dryer.

  The drying conditions vary depending on the drying method, but when a spray dryer is used, the dryer inlet hot air temperature is preferably 200 to 400 ° C, more preferably 220 to 370 ° C.

  When using a spray dryer, the average particle size of the obtained dry particles is preferably in the range of 1 to 250 μm. When the average particle size is less than 1 μm, an appropriate pore size necessary for the oxidation reaction by the catalyst in the present invention cannot be obtained, and the yield of the reaction target product may be lowered. On the contrary, when the average particle diameter of the dry particles exceeds 250 μm, the number of contact points between the dry particles per unit volume may decrease, and the mechanical strength of the catalyst may decrease. The average particle diameter of the dry particles is more preferably in the range of 5 to 150 μm. In addition, an average particle diameter means a volume average particle diameter, for example, can be measured with a laser type particle size distribution measuring apparatus.

  Moreover, the contact method of the sprayed droplet and hot air may be any of parallel flow, counter flow, and co-current flow (mixed flow), and in any case, it can be suitably dried.

  The dry particles thus obtained may be heat treated (fired) at 200 to 500 ° C. to obtain fired particles, if necessary. The firing conditions are not particularly limited, but firing is usually performed under a flow of oxygen, air, or nitrogen. The firing time is appropriately set depending on the target catalyst.

The dry particles and the calcined particles containing the catalyst component are collectively referred to as catalyst component particles.
Next, in the step (2), the catalyst component particles (hereinafter also referred to as “particles”) obtained in the step (1) are kneaded at least with a liquid to obtain a kneaded product. The apparatus used for kneading is not particularly limited. For example, a batch-type kneading machine 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. However, the batch method is preferable because kneading can be performed while checking the state of the kneaded product. Moreover, the end point of kneading | mixing can be judged by visual observation or a touch normally.

  The liquid used in the step (2) is not particularly limited as long as it has a function of wetting the particles obtained in the step (1). For example, water, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, etc. Alcohol having 1 to 4 carbon atoms. Of these, ethyl alcohol and propyl alcohol are preferred because the particles do not collapse and easily form pores effective for the oxidation reaction. The alcohol preferably has a high purity, but may contain a small amount of water.

  The amount of the liquid used in the step (2) is appropriately selected depending on the type and size of the particles, the type of the liquid, etc., but is usually 10 with respect to 100 parts by mass of the particles obtained in the step (1). ~ 80 parts by mass. When the amount of liquid used is increased, extrusion molding can be performed more smoothly, so that the particles are less likely to be crushed, and there is a tendency that large voids, that is, large pores are formed in the dried and baked molded article and the selectivity of methacrylic acid is improved. is there. Therefore, the amount of the liquid used is preferably 40 parts by mass or more, more preferably 45 parts by mass or more with respect to 100 parts by mass of the particles. On the other hand, when the amount of liquid used is small, adhesion during molding is reduced and handling is improved. Further, when the amount of liquid used is reduced, the strength of the molded product tends to be improved because the molded product becomes denser. Accordingly, the amount of liquid used is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, with respect to 100 parts by mass of the particles.

  In the step (2), it is preferable to add a molding aid such as an organic binder to the mixture of the catalyst component particles and the liquid because the strength is improved. Examples of such an organic binder include polymer compounds such as polyvinyl alcohol, α-glucan derivatives, and β-glucan derivatives.

  In the present invention, an α-glucan derivative refers to a polysaccharide composed of glucose in which glucose is bound in an α-type structure, and α1-4 glucan, α1-6 glucan, α1-4 / 1-6 glucan. And the like.

  Examples of such α-glucan derivatives include amylose, glycogen, amylopectin, pullulan, dextrin, cyclodextrin and the like.

  In the present invention, a β-glucan derivative refers to a polysaccharide composed of glucose in which glucose is bound in a β-type structure. Β1-4 glucan, β1-3 glucan, β1-6 glucan, β1-3 Derivatives such as / 1-6 glucan can be exemplified.

  Examples of such β-glucan derivatives include celluloses such as methylcellulose, ethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxybutylmethylcellulose, ethylhydroxyethylcellulose, and hydroxypropylcellulose. Derivatives, curdlan, laminaran, paramylon, callose, pakiman, β1-3 glucan such as scleroglucan and the like can be mentioned.

  The organic binder may be used as it is, or may be used after purification, but it is preferable that the metal as an impurity and the ignition residue are less because the catalyst performance may be deteriorated.

The amount of the organic binder used is appropriately selected depending on the type and size of the particles, the type of the liquid, etc., but usually 0.05 to 15 parts by mass with respect to 100 parts by mass of the particles obtained in the step (1) Preferably, it is 0.1-10 mass parts. As the amount of the organic binder added increases, the moldability tends to improve, and as the amount decreases, the removal of the organic binder by heat treatment after molding becomes easier.
The method for mixing the particles, liquid and organic binder is not particularly limited. Specific examples include a method of mixing a mixture of particles and an organic binder with a liquid, a method of mixing a solution obtained by dissolving or dispersing an organic binder in a liquid, and a method of mixing particles. A method of mixing a liquid obtained by dry mixing an organic binder and a liquid is preferable.

  In the present invention, conventionally known silica, alumina, silica-alumina, silicon carbide, titania, magnesia, inorganic compounds such as graphite and diatomaceous earth, glass fibers, ceramic balls and stainless steel, ceramic fibers and carbon fibers, etc. An inert carrier such as inorganic fiber can be added. The addition may be performed when kneading in the step (2).

  Next, in the primary molding step (3), the kneaded product obtained in the step (2) is molded into a primary molded product by an apparatus such as a screw extruder, a press extruder, or a press machine.

The primary molding pressure P1 in the step (3) is not particularly limited, but is preferably 0.5 MPaG to 15 MPaG, and more preferably 1 MPaG to 12 MPaG.
In the present invention, the molding pressure is an average value of pressure applied to the extruder during press molding or extrusion molding. The molding pressure is an average value when the pressure molding is stabilized after the press molding or extrusion molding is started, and does not include the pressure during the period when the molding immediately after the operation of the apparatus is not started.
The molding pressure can be measured, for example, by inserting a pressure sensor into the cylinder part of the extruder. For example, the notation that the molding pressure is 2 MPaG indicates that the gauge pressure of the molding pressure measured by a pressure sensor or the like is 2 MPa.

  If the primary molding pressure is, for example, molding by a press, it can be easily changed by changing the set pressure. In the case of a screw molding machine, it can be adjusted by the length of the discharge nozzle of the primary molded product. It is desirable to perform primary molding with a press machine from the viewpoint that the molding pressure can be easily controlled and the pores are less blocked by the collapse of the catalyst particles.

  The shape of the primary molded product is not particularly limited, but the shape of the primary molded product is a cylindrical shape having a diameter of 0.5 to 1 times the cylinder diameter of a piston molding machine that performs secondary molding. Is preferred. As for the diameter of the cylindrical primary molded product, the smaller the diameter, the easier it is to fill the piston molding machine with the primary molded product. Air becomes difficult to enter, and the load on the catalyst particles is reduced. Further, since the volume in the cylinder can be used effectively, there is an advantage that the number of times of primary molding and secondary molding can be reduced when the same amount of molded product is manufactured, and productivity is improved. In this range, the larger the primary molding diameter is, the more the mechanical load on the catalyst particles is reduced. Therefore, in particular, a cylindrical shape having a diameter of 0.8 times or more and less than 1 time the cylinder diameter of the piston molding machine is preferable.

  Next, in the secondary molding step (4), the obtained primary molded product is secondarily molded by a piston molding machine and molded into a final shape. Piston molding reduces bending during extrusion and improves product yield. In addition, since excessive kneading does not occur during extrusion as compared with the case of molding using a screw extruder or the like, the pores are not blocked by the collapse of the catalyst particles, and the selectivity is improved.

  Compared to the case where an irregularly shaped kneaded product is directly extruded into a final shape without performing primary molding (with a piston extruder or the like), a uniform molded body is obtained with less excess air being mixed. It is preferable from the point obtained.

  The secondary molding pressure P2 in the step (4) of the present invention is in the range of (P1-0.2) MPaG to (P1-8) MPaG with respect to the primary molding pressure P1 in the step (3). . When the secondary molding pressure P2 exceeds (P1−0.2) MPaG, the pores between the catalyst particles are blocked and the selectivity of methacrylic acid is lowered. If the secondary molding pressure P2 is smaller than (P1-8) MPaG, excess air is often mixed and a uniform molded product cannot be formed, and the final catalyst bulk density is lowered, leading to the reaction tube. This is not preferable from the viewpoint of reducing the amount of filling. Therefore, the secondary molding pressure P2 in the step (4) is in the range of (P1-0.2) MPaG to (P1-8) MPaG, and (P1-0.5) MPaG to (P1-6) MPaG is preferable.

  The secondary molding pressure P2 in the step (4) is not particularly limited, but is preferably 0.5 MPaG to 5 MPaG, and more preferably 1 MPaG to 4 MPaG.

In addition, the shape of the catalyst molded body obtained by extrusion molding in the secondary molding is not particularly limited, and can be molded into an arbitrary shape such as a ring shape, a columnar shape, or a star shape.
The secondary molding pressure can be adjusted by the amount of liquid used in the step (2), the extrusion speed, the die opening ratio (ratio of the area of the die opening to the cross-sectional area of the cylinder), and the like. In other words, the secondary molding pressure increases as the amount of liquid used in the step (2) decreases, the extrusion discharge rate increases, and the die opening ratio decreases, and conversely, in the step (2). The smaller the amount of liquid used, the lower the extrusion discharge speed, and the larger the die opening ratio, the smaller.

  Next, in the step (5), the catalyst molded body obtained in the step (4) is dried and fired to obtain a catalyst (product). The drying method is not particularly limited, and for example, generally known methods such as hot air drying, humidity drying, far-infrared drying, or microwave drying can be arbitrarily used. The drying conditions can be appropriately selected as long as the desired moisture content can be achieved.

  The firing conditions are not particularly limited, and known firing conditions can be applied. Usually, it is performed in a temperature range of 200 to 600 ° C. Usually, the calcination can be performed at a temperature of 200 to 500 ° C., preferably 300 to 450 ° C. for 1 to 24 hours.

  Next, the manufacturing method of methacrylic acid of this invention is demonstrated. The method for producing methacrylic acid of the present invention is a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the methacrylic acid production catalyst obtained as described above.

  The gas phase catalytic oxidation reaction is performed in a fixed bed. The catalyst layer is not particularly limited, and may be an undiluted layer containing only a catalyst, a diluted layer containing an inert carrier, or a single layer or a mixed layer composed of a plurality of layers.

In the reaction, it is preferable to use a source gas containing methacrolein and molecular oxygen.
The concentration of methacrolein in the raw material gas can be varied within a wide range, but is preferably 1% by volume or more, and more preferably 3% by volume or more. Moreover, 20 volume% or less is preferable and 10 volume% or less is more preferable.

  The molecular oxygen concentration in the raw material gas is preferably 0.4 mol or more, more preferably 0.5 mol or more with respect to 1 mol of methacrolein. Moreover, 4 mol or less is preferable with respect to 1 mol of methacrolein, and 3 mol or less is more preferable. Although it is economical to use air as the molecular oxygen source, air or the like enriched with pure oxygen can also be used if necessary.

  The source gas preferably contains water (water vapor) in addition to methacrolein and molecular oxygen. By performing the reaction in the presence of water, methacrylic acid can be obtained in a higher yield. The concentration of water vapor in the raw material gas is preferably 0.1% by volume or more, and more preferably 1% by volume or more. Moreover, 50 volume% or less is preferable and 40 volume% or less is more preferable. The source gas may contain a small amount of impurities such as a lower saturated aldehyde, but the amount is preferably as small as possible. Moreover, inert gas, such as nitrogen and a carbon dioxide gas, may be included.

  The reaction pressure of the gas phase catalytic oxidation reaction is preferably from normal pressure (atmospheric pressure) to 5 atm. The reaction temperature is preferably 230 ° C. or higher, more preferably 250 ° C. or higher. Moreover, 450 degrees C or less is preferable and 400 degrees C or less is more preferable.

  The flow rate of the raw material gas is not particularly limited, and can be appropriately set so as to have an appropriate contact time. The contact time is preferably 1.5 seconds or longer, and more preferably 2 seconds or longer. Moreover, 15 seconds or less are preferable and 10 seconds or less are more preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these Examples. The “parts” in the following examples and comparative examples are parts by mass.

The analysis of the raw material gas and the product was performed using gas chromatography. In addition, the reaction rate of methacrolein, the selectivity of the methacrylic acid to produce | generate, and a single flow yield are defined as follows.
Reaction rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Methacrylic acid yield (%) = (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 primary molding pressure and the secondary molding pressure were measured by inserting a pressure sensor into the cylinder part of a press or an extruder.
Further, the quality irregularity of the catalyst molded body was judged 30 times from the standard deviation of the filling density of each molded product after being molded 30 times under the same molding conditions. The filling density was calculated from the mass X of 100 ml of the compact in a measuring cylinder having an inner diameter of 27 mm as follows.
Packing density (g / L) = X × 10
If the standard deviation of the packing density was 8 or less, the variation in the packing length when filling the reaction tube was small, and therefore, it was judged that the quality unevenness of the catalyst molded body was small.

Example 1
In 400 parts of pure water, 100 parts of molybdenum trioxide, 3.4 parts of ammonium metavanadate, 8.0 parts of 85 mass% phosphoric acid aqueous solution and 1.4 parts of copper nitrate were dissolved, and the temperature was raised to 95 ° C. while stirring. The mixture was warmed and stirred for 3 hours while maintaining the liquid temperature at 95 ° C. After cooling to 40 ° C., a solution obtained by dissolving 13.5 parts of cesium bicarbonate in 20 parts of pure water was added and stirred for 15 minutes while stirring using a rotary blade stirrer. Next, a solution obtained by dissolving 10.7 parts of ammonium nitrate in 20 parts of pure water was added and further stirred for 20 minutes.

  The mixed slurry containing the raw material compound of the catalyst component obtained as described above was dried under the conditions of a dryer inlet temperature of 300 ° C. and a slurry spraying rotary disk of 18,000 rpm using a co-current spray dryer.

  100 parts of the dry particles thus obtained were mixed with 4 parts of hydroxypropylmethylcellulose and 50 parts of ethyl alcohol and kneaded with a kneader until it became a clay. Next, this irregular kneaded product was formed into a cylindrical shape having a diameter of 45 mm and a length of 280 mm using a hydraulic press. The pressure of primary molding by a press machine was 2.2 MPaG.

  Next, this primary molded product was extruded using a piston-type extrusion molding machine having a cylinder with a diameter of 50 mm and a length of 300 mm to obtain a cylindrical molded body having an outer diameter of 5.5 mm and an average length of 5.5 mm. It was.

This molded body was dried at 60 ° C. for 16 hours, and then heat-treated at 380 ° C. for 15 hours under air flow to obtain a catalyst. The elemental composition other than oxygen (hereinafter the same) of the obtained catalyst was as follows.
Mo ₁₂ V _0.5 P _1.2 Cu _0.1 Cs _1.2

  This catalyst is filled in a reaction tube, and a raw material gas of 5% by volume of methacrolein, 10% by volume of oxygen, 10% by volume of water vapor and 75% by volume of nitrogen is passed at a reaction temperature of 280 ° C. and a contact time of 3.5 seconds. Rain-phase catalytic oxidation reaction was performed. The product was collected and analyzed by gas chromatography to determine methacrolein reaction rate, methacrylic acid selectivity, and methacrylic acid yield. The results are shown in Table 1.

(Example 2)
In Example 1, a catalyst was produced in the same manner as in Example 1 except that the primary molding pressure was changed to 4.0 MPaG, and a gas phase catalytic oxidation reaction of methacrolein was performed. The results are shown in Table 1.

(Example 3)
In Example 1, except that the primary molding pressure was changed to 10.0 MPaG, a catalyst was produced in the same manner as in Example 1, and a gas phase catalytic oxidation reaction of methacrolein was performed. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, except that the primary molding pressure was changed to 2.0 MPaG, a catalyst was produced in the same manner as in Example 1, and a gas phase catalytic oxidation reaction of methacrolein was performed. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, except that the primary molding pressure was changed to 12.0 MPaG, a catalyst was produced in the same manner as in Example 1, and a gas phase catalytic oxidation reaction of methacrolein was performed. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, a catalyst was produced in the same manner as in Example 1 except that primary molding with a press was not performed, and methacrolein was subjected to a gas phase catalytic oxidation reaction. The results are shown in Table 1.

(Comparative Example 4)
In Example 1, the catalyst was produced in the same manner as in Example 1 except that the primary molding was changed to a screw type extrusion molding machine and the extrusion pressure was 1.0 MPaG, and the gas phase catalytic oxidation reaction of methacrolein was performed. It was. The results are shown in Table 1.

Example 4
In Example 1, the catalyst was produced in the same manner as in Example 1 except that the amount of ethyl alcohol mixed was changed to 55 parts and the primary molding pressure was changed to 3.0 MPaG, and vapor phase catalytic oxidation of methacrolein. Reaction was performed. The results are shown in Table 1.

(Comparative Example 5)
In Example 4, a catalyst was produced in the same manner as in Example 1 except that the primary molding pressure was changed to 1.0 MPaG, and methacrolein was subjected to a gas phase catalytic oxidation reaction. The results are shown in Table 1.

(Example 5)
In Example 1, the catalyst was produced in the same manner as in Example 1 except that the amount of ethyl alcohol mixed was changed to 40 parts and the primary molding pressure was changed to 5.5 MPaG, and gas phase catalytic oxidation of methacrolein. Reaction was performed. The results are shown in Table 1.

(Comparative Example 6)
In Example 5, a catalyst was produced in the same manner as in Example 1 except that the primary molding pressure was changed to 1.0 MPaG, and a gas phase catalytic oxidation reaction of methacrolein was performed. The results are shown in Table 1.

  As is clear from Table 1, in the examples, the quality of the catalyst molded body was small, and the yield of the reaction product was high.

  On the other hand, in Comparative Examples 1, 3, 4, 5, and 6, the quality unevenness of the catalyst molded body was larger than in the Examples, and in Comparative Example 2, the yield of the target reaction product was low.

Claims (6)

In a method for producing a methacrylic acid production catalyst containing at least molybdenum and phosphorus as catalyst components, which is used in producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(1) a step of producing catalyst component particles containing a catalyst component;
(2) mixing and kneading the catalyst component particles and liquid;
(3) a primary molding step of primary molding the kneaded product;
(4) including a secondary molding step of molding the primary molded product into a final shape with a piston molding machine,
The secondary molding pressure P2 in the step (4) is in the range of (P1-0.2) MPaG to (P1-8) MPaG with respect to the primary molding pressure P1 in the step (3). A method for producing a methacrylic acid production catalyst.   The manufacturing method of the catalyst for methacrylic acid production of Claim 1 which performs primary shaping | molding with a press.   The method for producing a catalyst for methacrylic acid production according to claim 1 or 2, wherein the secondary molding pressure P2 is 0.5 MPaG to 5 MPaG.   The method for producing a methacrylic acid production catalyst according to any one of claims 1 to 3, wherein the liquid is one or more selected from the group consisting of water and an alcohol having 1 to 4 carbon atoms.   The catalyst for methacrylic acid manufacture manufactured by the manufacturing method in any one of Claims 1-4.   A method for producing methacrylic acid, comprising subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid according to claim 5.