KR102051273B1 - Method for producing catalyst for producing (meth) acrylic acid and method for producing (meth) acrylic acid - Google Patents

Abstract

Provided are a method for producing a catalyst which can reduce the quality nonuniformity of the catalyst molded body of the catalyst for producing (meth) acrylic acid. (1) mixing a catalyst precursor containing a catalyst component with a contact between a liquid and a binder to produce a mixture, (2) molding the mixture to produce a molded body, and (3) heat treating the molded body. At least one of the contact, the mixture, and the molded body is kept at a temperature of 10 ° C. or more for a total of 2 hours or more, after the contact is produced in step (1) and before the molded body is heat-treated in step (3). When the content rate of the mixture calculated from the input amount in the step (1) is α% and the content rate of the mixture just before the molding in the step (2) is β%, The manufacturing method of the catalyst for manufacturing (meth) acrylic acid whose change rate of the content containing rate computed is -10% or more and 10% or less.
% Change in content rate = (α-β) / α × 100 (I)

Description

Method for producing catalyst for producing (meth) acrylic acid and method for producing (meth) acrylic acid

The present invention relates to a method for producing a catalyst for producing (meth) acrylic acid and a method for producing (meth) acrylic acid.

As a catalyst component for producing (meth) acrylic acid by gas phase catalytic oxidation of (meth) acrolein with molecular oxygen, a heteropolyacid compound represented by inmolybdenum acid is known. In addition, a number of methods for forming a pore structure in the catalyst have been proposed in order to make the catalyst component effective in the gas phase catalytic oxidation reaction.

For example, Patent Document 1 includes a primary molding step of primary molding a kneaded product, and a secondary molding step of molding the primary molded product into a final shape with a piston molding machine, and the secondary molding pressure P2 is primary molding. A method for producing a catalyst for methacrylic acid production, which is in the range of (P1-0.2) MPaG to (P1-8) MPaG with respect to pressure P1, has been proposed.

Japanese Patent Publication No. 2011-224482

However, in industrial use, the manufacturing method of the catalyst which can reduce the quality nonuniformity of a catalyst molded object by simpler operation is calculated | required.

An object of this invention is to provide the manufacturing method of the catalyst for (meth) acrylic acid production which can reduce the quality nonuniformity of the catalyst molded object of the catalyst for (meth) acrylic acid production.

The method for producing a catalyst for producing (meth) acrylic acid according to the present invention includes at least molybdenum and phosphorus, which are used when gas-phase catalytic oxidation of (meth) acrolein with molecular oxygen to produce (meth) acrylic acid, as catalyst components. As a manufacturing method of the catalyst for manufacturing (meth) acrylic acid containing,

(1) mixing a catalyst precursor containing the catalyst component with a contact between a liquid and a binder to produce a mixture;

(2) forming a mixture by molding the mixture;

(3) a step of heat-treating the molded body,

At least one of the contact, the mixture, and the molded body is added at a temperature of 10 ° C. or more in the process (1) until the contact is produced and before the heat treatment of the molded body is performed in the process (3). Keep over time,

When the content rate of the mixture calculated from the input amount in the step (1) is α% and the content rate of the mixture just before the molding in the step (2) is β%, the following formula ( The change rate of the liquid content rate computed by I) is -10% or more and 10% or less.

  % Change in content rate = (α-β) / α × 100 (I)

In addition, (alpha) is a moisture content standard based on the moisture content computed by following formula (II) from the mass a of the liquid thrown in at the process (1), and the mass b of the sum total of a catalyst precursor and a binder.

  α = a / (a + b) × 100 (II)

In addition, (beta) is a content rate computed by following formula (III) from the mass c (g) after drying 10g of mixtures just before shaping | molding process (2) at normal pressure and 100 degreeC for 30 minutes.

  β = (10-c) / 10 × 100 (III)

In the method for producing (meth) acrylic acid according to the present invention, a (meth) acrylic acid production catalyst is produced by the above method, and (meth) acrolein is subjected to gas phase catalytic oxidation using molecular oxygen in the presence of the (meth) acrylic acid production catalyst. Let's do it.

According to this invention, the manufacturing method of the catalyst for (meth) acrylic acid production which can reduce the quality nonuniformity of the catalyst molded object of the catalyst for (meth) acrylic acid production can be provided.

[Method of producing catalyst for producing (meth) acrylic acid]

The method for producing a catalyst for producing (meth) acrylic acid according to the present invention includes at least molybdenum and phosphorus, which are used when gas-phase catalytic oxidation of (meth) acrolein with molecular oxygen to produce (meth) acrylic acid, as catalyst components. As a manufacturing method of the catalyst for manufacturing (meth) acrylic acid containing, the following process (1)-process (3) are included.

(1) Process of mixing the catalyst precursor containing the said catalyst component, the contact material of a liquid, and a binder, and manufacturing a mixture.

(2) A step of molding the mixture to produce a molded article.

(3) heat-treating the molded body.

In the method according to the present invention, at least one of the contact, the mixture, and the molded body is produced after the contact is produced in the step (1) and before the heat-treatment of the molded body in the step (3). Is maintained at 10 ° C. or higher for at least 2 hours. In addition, the rate of change (hereinafter also referred to as a rate of change of the content of the content) calculated by the formula (I) is -10% or more and 10% or less. In addition, the change rate of a liquid content rate is a value computed by Formula (I)-Formula (III) mentioned later. By these, in the method which concerns on this invention, the quality nonuniformity of the catalyst molded object of the catalyst for (meth) acrylic acid production can be reduced. Hereinafter, the detail of each process is demonstrated.

(Step (1))

In step (1), a mixture is prepared by mixing a catalyst precursor containing a catalyst component with a contact between a liquid and a binder.

The catalyst precursor comprising the catalyst component is, for example, a mixed solution or slurry containing at least molybdenum and phosphorus by dissolving or suspending the raw material compound of the catalyst component including at least molybdenum and phosphorus in an appropriately selected solvent. Can be prepared and the obtained mixed solution or slurry can be dried.

There is no limitation in particular in the preparation method of the said mixed solution or the said slurry, For example, it can prepare by the precipitation method, the oxide mixing method, etc.

The raw material compound of the catalyst component used for preparation of the said mixed solution or the said slurry is not specifically limited, Nitrate, carbonate, acetate, ammonium salt, oxide, halide, oxo acid, oxo acid salt, etc. of each component of a catalyst May be used alone or in combination of two or more thereof. As a raw material compound of molybdenum, molybdenum oxides, such as molybdenum oxides, such as molybdenum trioxide, ammonium paramolybdate, and ammonium dimolybdate, etc. are mentioned, for example. As a raw material compound of phosphorus, phosphoric acid, phosphorus pentoxide, ammonium phosphate, etc. are mentioned, for example. As a raw material compound of vanadium, ammonium metavanadate, vanadium pentoxide, vanadate oxalate, etc. are mentioned, for example. As a raw material compound of copper, copper nitrate, copper oxide, copper carbonate, copper acetate, etc. are mentioned, for example. 1 type may be used for each element which comprises a catalyst component, and the raw material compound of a catalyst component may be used in combination of 2 or more type. It is preferable that the compounding ratio of the raw material compound of each structural element of a catalyst is a compounding ratio which satisfy | fills the composition represented by Formula (IV) mentioned later.

As a solvent used for preparation of the said mixed solution or slurry, water, ethyl alcohol, acetone, etc. are mentioned, for example. These may use 1 type and may use 2 or more types together. Among these, it is preferable to use water.

The method of drying the mixed solution or the slurry is not particularly limited, and for example, a method of drying using a spray dryer, a method of drying using a slurry dryer, a method of drying using a drum dryer, and evaporating to dryness The method can be applied. Among these, the method of drying using a spray dryer is preferable at the point which particle | grains are obtained simultaneously with drying, and the shape of the particle | grains obtained is a neat spherical form.

Although drying conditions differ according to a drying method, when using a spray dryer, 200-400 degreeC is preferable and, as for a dryer inlet temperature, 220-370 degreeC is more preferable.

When using a spray dryer, it is preferable that the average particle diameter of the catalyst precursor obtained is 1-250 micrometers. By the said average particle diameter being 1 micrometer or more, the pore diameter required for the oxidation reaction of (meth) acrolein can be ensured, and (meth) acrylic acid is obtained by a high yield. When the average particle diameter is 250 µm or less, the number of contact points between the catalyst precursor particles per unit volume does not decrease, and sufficient mechanical strength of the catalyst is obtained. As for the average particle diameter of a catalyst precursor, it is more preferable that it is 5-150 micrometers. In addition, the said average particle diameter means the volume average particle diameter, and is a value measured by a laser particle size distribution measuring apparatus.

In addition, the contact method of the sprayed droplet and hot air may be any of cocurrent flow, counterflow, and coflow flow (mixed flow), and can be suitably dried in any case.

The catalyst precursor thus obtained may be subjected to a heat treatment (firing) at 200 to 500 ° C. as necessary to obtain a fired product. Although baking conditions are not specifically limited, Baking is normally performed under oxygen, air, or nitrogen circulation. In addition, baking time is suitably set according to the target catalyst. Hereinafter, the catalyst precursor which is not baking and the said baking material are integrated, and are represented as a catalyst precursor.

In the present step, the liquid to be mixed with the catalyst precursor containing the catalyst component is not particularly limited as long as it has a function of wetting the catalyst precursor. For example, water, methyl alcohol, ethyl alcohol, propyl alcohol, butyl And alcohols having 1 to 4 carbon atoms such as alcohols. Among these, ethyl alcohol and propyl alcohol are preferable from the viewpoint of the particles that do not collapse the catalyst precursor and easily form pores effective for the oxidation reaction. These may use 1 type and may use 2 or more types together. On the other hand, in the case of using alcohol as the liquid, the alcohol is preferably of high purity, but may contain a small amount of water. In addition, in this invention, a liquid shows a liquid compound on the conditions of normal temperature (5-40 degreeC) and normal pressure (atmospheric pressure (0.1 MPa)).

Although the usage-amount of the said liquid is suitably selected according to the kind and size of the said catalyst precursor, the kind of the said liquid, etc., It is preferable that it is 10-80 mass parts with respect to 100 mass parts of said catalyst precursors. When the amount of the liquid used is 10 parts by mass or more, the extrusion can be performed more smoothly, so that the particles of the catalyst precursor are less likely to be crushed, so that large voids, that is, large pores are formed in the resulting catalyst molded body, and (meth) There exists a tendency for the selectivity of acrylic acid to improve. On the other hand, when the usage-amount of the said liquid is 80 mass parts or less, the adhesiveness at the time of shaping | molding is reduced and handling property improves. In addition, since the catalyst compact becomes denser, there is a tendency that the strength of the catalyst compact increases. As for the usage-amount of the said liquid, it is more preferable that it is 10-60 mass parts with respect to 100 mass parts of said catalyst precursors, and it is more preferable that it is 15-50 mass parts.

The binder is not particularly limited as long as it has a function of adhering the catalyst precursor, and for example, an organic binder or an inorganic binder can be used. As this organic binder, high molecular compounds, such as a polyvinyl alcohol, (alpha) glucan derivative, (beta) glucan derivative, etc. are mentioned, for example. These may use 1 type and may use 2 or more types together.

In the present invention, the α glucan derivative indicates that glucose is bound in an α-type structure among polysaccharides composed of glucose, and examples thereof include derivatives such as α1-4 glucan, α1-6 glucan, and α1-4 / 1-6 glucan. Can be. Specific examples of such α-glucan derivatives include amylose, glycogen, amylopectin, flulan, dextrin, cyclodextrin, and the like. These may use 1 type and may use 2 or more types together.

In the present invention, the β glucan derivative means that glucose is bound to a β-type structure among polysaccharides composed of glucose, and β1-4 glucan, β1-3 glucan, β1-6 glucan, β1-3 / 1-6 glucan and the like. The derivative of can be illustrated. As such a beta glucan derivative, for example, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, carboxymethyl cellulose sodium, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl methyl cellulose, hydroxybutyl Cellulose derivatives such as methyl cellulose, ethyl hydroxyethyl cellulose and hydroxypropyl cellulose; β1-3 glucan such as curdlan, laminaran, paramilon, kalos, pachyman, and scelloglucan. These may use 1 type and may use 2 or more types together.

Although the said organic binder may be used unrefined and refine | purified, it is preferable that content of metal impurity and ignition residue is smaller in order to suppress that catalyst performance falls due to metal or ignition residue as an impurity.

Examples of the inorganic binder include inert carriers such as inorganic fibers such as silica, alumina, silica-alumina, silicon carbide, titania, magnesia, graphite, diatomaceous earth, ceramic balls, stainless steel, glass fibers, ceramic fibers, and carbon fibers. Can be mentioned. These may use 1 type and may use 2 or more types together. In addition, the organic binder and the inorganic binder may be mixed and used.

Although the usage-amount of the said binder is suitably selected according to the kind and size of the said catalyst precursor, the kind of the said liquid, etc., It is preferable that it is 0.05-15 mass parts with respect to 100 mass parts of said catalyst precursors, It is more preferable that it is 0.1-10 mass parts, It is more preferable that it is 1-8 mass parts.

The method of contacting and mixing the catalyst precursor, the liquid and the binder is not particularly limited. Specifically, a method of dry mixing the catalyst precursor and the binder, a method of contacting and mixing the liquid, a method of dissolving or dispersing the binder in the liquid, a method of contacting and mixing the catalyst precursor, and the like will be exemplified. Can be. Among these, dry mixing of the catalyst precursor and the binder and a method of bringing the liquid into contact with each other are preferred. When using the binder which can be obtained in the state melt | dissolved or disperse | distributed to the said liquid, what is necessary is just to adjust the quantity of the liquid newly added in order to mix with the said catalyst according to the quantity of the said liquid.

In this process, a contact material is obtained by making a catalyst precursor contact a liquid, and a binder, and shows the thing before mixing. In addition, mixing in this process is an operation which mixes the mix | blended material together, and includes kneading | mixing. Kneading is an operation to mix and homogenize by mixing the blended materials together. In this step, it is preferable to obtain a mixture by injecting the catalyst precursor, the liquid, and the binder into a kneader, and kneading the contact.

A kneading machine is not specifically limited, For example, a batch kneading machine provided with a twin stirring blade, continuous kneading machines, such as an axial rotation reciprocating type and a self-cleaning type, can be used. However, a batch kneader is preferable at the point that kneading can be performed while checking the kneaded material state. In addition, the end point of kneading | mixing shall be the time of mixing until it becomes a state which can be extrusion-molded.

(Step (2))

In step (2), the mixture is molded to produce a molded body. The shaping | molding method of the said mixture is not specifically limited, For example, methods, such as extrusion molding, tablet shaping | molding, rolling granulation, are mentioned. Among these, extrusion molding is preferable from the viewpoint of less disintegration of the catalyst precursor particles and easy porosity effective for reaction. An extrusion molding machine can be used for the said extrusion molding, For example, a self-cleaning, a plunger-type extrusion molding machine, etc. can be used. Among these, since the dough suitable for the said mixture can be easily added and the performance of the catalyst obtained is stabilized, it is preferable to use a plunger type extrusion machine. There is no restriction | limiting in particular as a shape of a molded object, For example, it can be set as shapes, such as a ring shape, a column shape, a star shape.

(Step (3))

In step (3), the molded body is heat treated. For example, after the molded product is dried to obtain a catalyst molded product, the catalyst molded product can be fired to obtain a catalyst for producing (meth) acrylic acid. A drying method is not specifically limited, For example, methods, such as hot air drying, far-infrared drying and microwave drying, can be used. Drying conditions can be suitably selected as long as it can be made into the target moisture content, and it can dry at 100 degrees C or less, for example. Although baking conditions are not specifically limited, As baking temperature, 200-600 degreeC is preferable and 200-500 degreeC is more preferable. For example, it can bake for 1 to 24 hours at 300-450 degreeC. Moreover, you may perform drying and baking continuously.

(Cure)

In the method according to the present invention, at least one of the contact, the mixture, and the molded body is produced after the contact is produced in the step (1) and before the heat-treatment of the molded body in the step (3). Is maintained at 10 ° C. or higher for at least 2 hours. On the other hand, in this specification, it may be called curing to hold | maintain at predetermined temperature and predetermined temperature, and the object may be called the curing body. While the curing may be in a state of moving, changing in shape, or in stationary state, it is preferable that the state of the state is in the state of moving or stationary. In the present invention, after the contact is produced in the step (1) and before the heat-treatment of the molded body in the step (3), the curing is cured at 10 ° C or more for a total of 2 hours or more. It has been found that the quality nonuniformity of the catalyst molded body can be reduced.

The curing is carried out after the contact is produced in the step (1) and before the heat treatment of the molded body in the step (3). After the said contact material is manufactured in the said process (1), it shows from the time when the catalyst precursor containing the said catalyst component, the said liquid, and the said binder contacted. In addition, in the said process (3), until before heat processing the said molded object, it shows until the time point just before heat-processing the said molded object. If it is in this range, the said curing may be performed at any time.

The temperature of the curing agent in the curing is 10 ° C or more, preferably 15 ° C or more, more preferably 20 ° C or more, and even more preferably 25 ° C or more. When the said temperature is 10 degreeC or more, the quality nonuniformity of a catalyst molded object will become small. Moreover, although there is no restriction | limiting in particular in the upper limit of the said temperature, 40 degrees C or less is preferable and 35 degrees C or less is more preferable. When the said temperature is 40 degrees C or less, there exists a tendency for the intensity | strength of a catalyst to improve. Although the reason of the quality nonuniformity of a catalyst molded object being small by the temperature of the curing body in curing being 10 degreeC or more is not elucidated, since the dispersion of a catalyst precursor and a binder to the liquid advances moderately and it is settled to some extent, It is estimated that the dispersion nonuniformity in a mixture becomes small and the density nonuniformity at the time of shaping | molding reduces. On the other hand, the reason why the strength of the catalyst tends to be improved when the temperature of the curing agent in curing is 40 ° C. or lower is not clear. However, when the temperature exceeds 40 ° C., the dispersion of the catalyst precursor into the liquid proceeds excessively and the catalyst Since the particle | grains of a precursor fall large, it is guessed because the adhesive effect by a binder may become small. On the other hand, when the said temperature changes in the range of 10 degreeC or more during curing, the said temperature is made after manufacturing the said contact material in the said process (1), and before heat-processing the said molded object in the said process (3). During, the average temperature of the amniotic fluid is shown. In this case, it is preferable that the maximum temperature of the said changing temperature is 40 degreeC.

Although the method of controlling the temperature of the curing body in curing is not specifically limited, For example, adjusting the air-conditioning temperature of the room to cure, adjusting the jacket temperature of the container to cure, the temperature-controlled gas in the container to cure By a method such as circulation, a method of controlling the temperature of the environment around the sheep body within the range of the curing temperature can be applied.

In this invention, curing time is 2 hours or more in total. When curing time is 2 hours or more in total, the quality nonuniformity of a catalyst molded object can be reduced. On the other hand, for example, when the contact is cured for 1.5 hours and the mixture for 1.5 hours, the total is 3 hours, so the curing time satisfies the requirement of 2 hours or more in total. It is preferable that it is 2.5 hours or more, and, as for the sum total of curing time, it is more preferable that it is 3 hours or more. Although the upper limit of the total of curing time does not have a restriction | limiting in particular, 48 hours or less are preferable, 36 hours or less are more preferable, 30 hours or less are more preferable. When the total of curing time is 48 hours or less, the strength of the catalyst tends to be improved. The reason why the quality nonuniformity of the catalyst molded body becomes small when the total curing time is 2 hours or more is not elucidated. However, when the mixture is cured, dispersion of the catalyst precursor and the binder into the liquid proceeds to a certain level. Therefore, it is estimated that the dispersion nonuniformity in a mixture becomes small and the density nonuniformity at the time of shaping | molding reduces. On the other hand, the reason why the strength of the catalyst tends to be improved when the total of the curing time is 48 hours or less is not clear, but when the total of the curing time exceeds 48 hours, the dispersion of the catalyst precursor into the liquid proceeds excessively. Since the particle | grains of a precursor fall large, it is guessed because the adhesive effect by a binder may become small. In addition, curing may be performed continuously for 2 hours or more, may be performed intermittently, and the total time may be 2 hours or more.

(Rate of change of content)

In the method according to the present invention, the rate of change of the liquid content rate calculated by the formula (I) is -10% or more and 10% or less, preferably 0% or more and 10% or less, more preferably 0% or more and 9% or less. , 0% or more and 8% or less are more preferable, and 1% or more and 5% or less are particularly preferable. Since the viscosity nonuniformity in a mixture becomes small because the rate of change of a liquid content rate is -10% or more and 10% or less, the quality nonuniformity of a catalyst molded object becomes small. In addition, the change rate of a liquid content rate is a value computed by Formula (I)-Formula (III) mentioned later.

(Return process)

In the method which concerns on this invention, at least 1 conveyance process can be included between each process of the said process (1)-the said process (3). In this invention, conveyance is to move the manufactured goods manufactured by each process to the next process. For example, the method according to the present invention may include the conveying step between the step (1) and the step (2), in which case, for example, the mixture obtained in the step (1) is conveyed to the molding machine. And the said process (2) can be performed. During conveyance, conveyance may be interrupted temporarily and the operation | fixing of a manufactured goods may be included. In addition, operations such as changing the form of the manufactured product may be included. For example, when conveying the said mixture obtained at the said process (1) as mentioned above, operations, such as disintegration and preforming, are included in order to make it easy to input into the said molding machine in the said process (2). You may also

A conveying method is not specifically limited, For example, conveyance by manual labor and conveyance by a conveying machine are mentioned, but conveyance by a conveying machine is preferable from a viewpoint that a work load can be reduced and productivity is high.

As a conveyer, a screw conveyer, a belt conveyer, a chain conveyer, a roller conveyer, a vibration conveyer, an extrusion conveyer, a drop conveyer, etc. are mentioned, for example. Moreover, it is preferable that the said conveying machine has a structure which suppresses evaporation of a liquid from a viewpoint of controlling the change rate of the said liquid content rate in the range of -10% or more and 10% or less.

When carrying out said curing in a conveyance process, the environment around a nutrient body is adjusted by adjusting the air-conditioning temperature of the room which conveys, adjusting the jacket temperature of a conveyer, and circulating the gas controlled by the temperature in a conveyer, etc. The method of controlling the temperature of in the range of the said curing temperature is applicable.

The catalyst for producing (meth) acrylic acid produced by the method according to the present invention is used when gas-phase catalytic oxidation of (meth) acrolein with molecular oxygen to produce (meth) acrylic acid. The (meth) acrylic acid production catalyst is not particularly limited as long as it contains at least molybdenum and phosphorus as catalyst components.

The methacrylic acid production catalyst for producing methacrylic acid by gas phase catalytic oxidation of methacrolein is preferably a complex oxide having a composition represented by the following formula (IV) from the viewpoint of activity and selectivity.

P _a Mo _b V _c Cu _d X _e Y _f Z _g O _h (IV)

In formula (IV), P, Mo, V, Cu, and O represent phosphorus, molybdenum, vanadium, copper, and oxygen, respectively. X represents at least one element selected from the group consisting of arsenic, antimony and tellurium. Y is at least 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 One type of element is shown. 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 ratios of each element, and when b = 12, a = 0.1-3, c = 0.01-3, d = 0.01-2, e is 0-3, f = 0-3, g = 0.01-3, h is the atomic ratio of oxygen required to satisfy the valence of each said element.

The acrylic acid production catalyst for producing acrylic acid by gas phase catalytic oxidation of acrolein is preferably a complex oxide having a composition represented by the following formula (V) from the viewpoint of activity and selectivity.

P _i Mo _j V _k A _l X ² _m Y ² _n O _o (V)

In formula (V), P, Mo, V, and O represent phosphorus, molybdenum, vanadium, and oxygen, respectively. A represents at least one element selected from the group consisting of iron, cobalt, chromium, aluminum and strontium. X ² represents at least one element selected from the group consisting of germanium, boron, arsenic, selenium, silver, silicon, sodium, tellurium, lithium, antimony, potassium and barium. Y ² represents at least one element selected from the group consisting of magnesium, titanium, manganese, copper, zinc, zirconium, niobium, tungsten, tantalum, calcium, tin and bismuth. i, j, k, l, m, n and o represent the atomic ratio of each element, and when j = 12, i = 0.01-10, k = 0.01-6, l = 0-5, m = 0- It is 10 and n = 0-5, n is the atomic ratio of oxygen required to satisfy the valence of each said component.

[Method for producing (meth) acrylic acid]

In the method for producing (meth) acrylic acid according to the present invention, a (meth) acrylic acid production catalyst is produced by the above method, and (meth) acrolein is subjected to gas phase catalytic oxidation using molecular oxygen in the presence of the (meth) acrylic acid production catalyst. Let's do it.

The gas phase contact oxidation can be performed in a fixed phase. The structure of the catalyst layer is not particularly limited, and may be a dilution layer containing only a catalyst, a dilution layer containing an inert carrier, a single layer, or a mixed layer composed of a plurality of layers.

It is preferable to use the raw material gas containing (meth) acrolein and molecular oxygen as a raw material. 1 volume% or more is preferable and, as for the (meth) acrolein concentration in this source gas, 3 volume% or more is more preferable. Moreover, 20 volume% or less is preferable and, as for this (meth) acrolein concentration, 10 volume% or less is more preferable. 0.4 mol or more is preferable with respect to 1 mol of (meth) acrolein, and, as for the molecular oxygen concentration in this source gas, 0.5 mol or more is more preferable. Moreover, 4 mol or less is preferable with respect to 1 mol of (meth) acrolein, and, as for this molecular oxygen concentration, 3 mol or less is more preferable. As the molecular oxygen source, it is economical to use air, but if necessary, air enriched with pure oxygen can also be used.

It is preferable that the said source gas contains water (water vapor) other than (meth) acrolein and molecular oxygen. By carrying out the reaction in the presence of water, (meth) acrylic acid is obtained in a higher yield. 0.1 volume% or more is preferable and, as for the density | concentration of the water vapor in the said source gas, 1 volume% or more is more preferable. Moreover, 50 volume% or less is preferable, and, as for the said density | concentration, 40 volume% or less is more preferable. The source gas may contain a small amount of impurities such as lower saturated aldehyde, but the amount is preferably as small as possible. In addition, the said source gas may contain inert gas, such as nitrogen and a carbon dioxide gas.

The reaction pressure is preferably atmospheric pressure (atmospheric pressure) to 5 atmospheres. 230 degreeC or more is preferable and 250 degreeC or more of reaction temperature is more preferable. Moreover, 450 degrees C or less is preferable, and 400 degrees C or less of reaction temperature is more preferable.

The flow rate of the said source gas is not specifically limited, It can set suitably so that it may become an appropriate contact time. 1.5 second or more is preferable and, as for this contact time, 2 second or more is more preferable. Moreover, 15 second or less is preferable and, as for the said contact time, 10 second or less is more preferable.

Example

Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these Examples. In addition, "part" shows a "mass part."

(Standard deviation of filling density)

The quality nonuniformity of a catalyst molded object was manufactured 10 times on the same conditions, and the packing density of each catalyst molded object was measured, and it judged from the standard deviation of this packing density. The packing density was filled with the measuring cylinder with an internal diameter of 27 mm to the scale of 100 mL, and it calculated from the mass B by the following formula.

  Packing density (g / L) = B × 10.

Falling eruption rate

The drop differentiation rate which is an index of mechanical strength was measured by the following method. 100 g of the catalyst molded body was dropped and filled in the cylinder from the upper opening of the stainless steel cylinder of inner diameter 27.5 mm and 6 m in length whose lower opening was closed by the plate made of stainless steel. The drop differentiation rate was computed by the following formula using the mass of the thing which does not pass the sieve of 1 mm of eye size among the catalyst molded objects which opened and collect | recovered the lower opening part. The smaller the drop differentiation rate is, the higher the mechanical strength is, and the larger is the lower the mechanical strength. In addition, the fall differentiation rate in Table 1 is an average value of the fall differentiation rate which manufactured the catalyst molded object 10 times on the same conditions, and measured about each catalyst molded object.

  Drop eruption rate (%) = {(100-C) / 100} × 100.

(Rate of change of content)

The rate of change of the content ratio was calculated by the following formula (I).

  % Change in content rate = (α-β) / α × 100 (I)

In said Formula (I), (alpha) is a moisture content rate computed by following formula (II) from the mass a of the liquid thrown in at the process (1), and the mass b of the sum total of a catalyst precursor and a binder.

  α = a / (a + b) × 100 (II)

In addition, (beta) is a content rate computed by following formula (III) from the mass c (g) after drying 10g of mixtures just before shaping | molding process (2) at normal pressure and 100 degreeC for 30 minutes.

  β = (10-c) / 10 × 100 (III).

Example 1

1000 parts of molybdenum trioxide, 34 parts of ammonium metavanadate, 80 parts of 85 mass% phosphoric acid aqueous solution, and 7 parts of copper nitrate were dissolved in 4,000 parts of pure water, and the temperature was raised to 95 ° C while stirring, while maintaining the liquid temperature at 95 ° C. It stirred for 3 hours. After cooling to 90 degreeC, the solution which melt | dissolved 124 parts of cesium bicarbonates in 200 parts of pure waters was added, stirring using a rotorcraft stirrer, and stirred for 15 minutes. Next, the solution which melt | dissolved 92 parts of ammonium carbonates in 200 parts of pure waters was added, and it stirred for 20 minutes. The mixed slurry containing the raw material compound of the catalyst component obtained as mentioned above was dried on the conditions of the dryer inlet temperature of 300 degreeC, and the rotating disk for slurry spraying 18,000 rpm using the cocurrent spray dryer, and obtained the catalyst precursor. The average particle diameter of this catalyst precursor was 25 micrometers.

To 100 parts of the catalyst precursor, 5 parts of hydroxypropyl cellulose and 20 parts of ethyl alcohol were introduced into a batch kneader having double sigma blades so that the content of the mixture calculated from the charged amount was 16.0%. The mixture was kneaded until the contact became clay and a mixture was obtained.

The mixture was introduced into a tank equipped with a screw conveyer at the bottom thereof, and the lid was covered with an inlet to seal it. Subsequently, the said mixture was discharged to the said screw conveyer, and it conveyed to the plunger-type extrusion molding machine. This plunger type extrusion machine is provided with 14 die | dyes which have 14 openings of 5.5 mm (phi) concentrically, and the inner diameter of this plunger type extrusion machine is 120 mm (phi). The quantity of the said mixture conveyed by the said screw conveyer is the quantity which is extruded once by the said plunger-type extrusion molding machine, and the remaining mixture was hold | maintained in the tank.

Here, while conveying the said mixture to the said screw conveyer, the said mixture was hardened at 25 degreeC for 3 hours. At this time, the temperature of the positron was controlled to 25 degreeC by adjusting the temperature of the jacket of the said tank provided with the said screw conveyer to 25 degreeC.

The said mixture after hardening was extrusion-molded by the said plunger-type extrusion molding machine at the plunger moving speed of 100 mm / min. The extrudate discharged | emitted from the said die was cut | disconnected by rotating the piano wire at 375 rpm in the die surface, and the molded object was obtained.

The catalyst compact was obtained by heat-processing the said molded object at 90 degreeC for 12 hours with a hot air dryer. Moreover, the catalyst molded object was produced similarly about the mixture which remained in the tank, and the standard deviation of packing density and the fall differentiation rate were measured about these. Table 1 shows the content of the mixture calculated from the charged amount, the content of the mixture just before molding, the rate of change of the content, the standard deviation of the packing density, and the drop differentiation rate. On the other hand, the composition of the catalyst except oxygen obtained when calcining the catalyst molded body is P _1.2 Mo ₁₂ V _0.5 Cu _0.05 Cs _1.1 .

Example 2

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing time was changed to 25 hours. The results are shown in Table 1.

Example 3

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing time was changed to 47 hours. The results are shown in Table 1.

Example 4

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing time was changed to 61 hours. The results are shown in Table 1.

Example 5

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing time was changed to 25 hours and the curing temperature was changed to 50 ° C. The results are shown in Table 1.

Example 6

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing temperature was changed to 30 ° C. and the conveyor was changed to a belt conveyor conveyor. The results are shown in Table 1.

Comparative Example 1

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing time was changed to 1 hour. The results are shown in Table 1.

Comparative Example 2

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing temperature was changed to 7 ° C. The results are shown in Table 1.

Comparative Example 3

After putting a mixture into the tank provided with a screw conveyer in the lower part, the catalyst molded object was produced and evaluated similarly to Example 1 except not having closed and not cap | covering the inlet. The results are shown in Table 1.

Example 7

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the curing temperature was changed to 30 ° C. and the mixture was discharged into a poly bag without being used for a conveyer and conveyed to a plunger-type extrusion molding machine by a manpower. . The results are shown in Table 1. On the other hand, in the method of Example 7, the quality nonuniformity of the catalyst molded body was reduced, but since the extraction was carried out by manpower and conveyed, the workload was large and it required three times as many workers compared with the case using a conveyer.

Example 8

A catalyst molded body was produced and evaluated in the same manner as in Example 1 except that the amount of ethyl alcohol used at the time of mixing was changed to 24 parts. The results are shown in Table 1.

[Comparative Example 4]

A catalyst molded body was produced and evaluated in the same manner as in Example 8 except that the curing time was changed to 1 hour. The results are shown in Table 1.

Example 9

1000 parts of molybdenum trioxide, 80 parts of 85 mass% phosphoric acid aqueous solution, 42 parts of vanadium pentoxide, 9 parts of copper oxides, and 2 parts of iron oxides are dissolved, and the temperature is raised to 95 ° C while stirring, and the liquid temperature is brought to 95 ° C. It stirred for 3 hours, maintaining. After cooling this liquid to 50 degreeC, 374 parts of 29 mass% ammonia water were dripped, and it stirred for 15 minutes. Next, the solution which melt | dissolved 102 parts of cesium nitrates in 30 parts of pure waters was dripped, and it stirred for 15 minutes. The mixed slurry containing the raw material compound of the catalyst component obtained as mentioned above was dried on the conditions of the dryer inlet temperature of 300 degreeC, and the rotating disk for slurry spraying 18,000 rpm using the cocurrent spray dryer, and obtained the catalyst precursor. The average particle diameter of this catalyst precursor was 30 micrometers.

To 100 parts of the catalyst precursor, 5 parts of hydroxypropyl cellulose and 30 parts of isopropyl alcohol were added to a batch kneader having double sigma blades so that the content of the mixture calculated from the charged amount was 22.2%. Contact was knead | mixed until the contact became clay phase, and the mixture was obtained.

The mixture was introduced into a tank equipped with a screw conveyer at the bottom thereof, and the lid was covered with an inlet to seal it. Subsequently, the said mixture was discharged to the said screw conveyer, and it conveyed to the plunger-type extrusion molding machine. This plunger type extrusion machine is provided with 14 die | dyes which have 14 openings of 5.5 mm (phi) concentrically, and the inner diameter of this plunger type extrusion machine is 120 mm (phi). The quantity of the said mixture conveyed by the said screw conveyer is the quantity which is extruded once by the said plunger-type extrusion molding machine, and the remaining mixture was hold | maintained in the tank.

Here, while conveying the said mixture to the said screw conveyer, the said mixture was hardened at 25 degreeC for 3 hours. At this time, the temperature of the positron was controlled to 25 degreeC by adjusting the temperature of the jacket of the said tank provided with the said screw conveyer to 25 degreeC.

The said mixture after hardening was extrusion-molded by the said plunger-type extrusion molding machine at the plunger moving speed of 100 mm / min. The extrudate discharged | emitted from the said die was cut | disconnected by rotating the piano wire at 375 rpm in the die surface, and the molded object was obtained.

The catalyst compact was obtained by heat-processing the said molded object at 90 degreeC for 12 hours with a hot air dryer. Moreover, the catalyst molded object was produced similarly about the mixture which remained in the tank, and the standard deviation of packing density and the fall differentiation rate were measured about these. Table 1 shows the content of the mixture calculated from the charged amount, the content of the mixture just before molding, the rate of change of the content, the standard deviation of the packing density, and the drop differentiation rate. On the other hand, the composition of the catalyst except oxygen obtained when the catalyst compact is fired is P _1.2 Mo ₁₂ V _0.8 Cu _0.2 Fe _0.05 Cs _0.9 .

[Comparative Example 5]

A catalyst molded body was produced and evaluated in the same manner as in Example 9 except that the curing time was changed to 1 hour. The results are shown in Table 1.

Example 10

With respect to 100 parts of the catalyst precursor obtained in the same procedure as in Example 1, 5 parts of hydroxypropyl cellulose and 20 parts of ethyl alcohol were arranged with a double sigma blade so that the content of the mixture calculated from the charged amount was 16.0%. After putting into a kneader of a formula and making contact, the contact was cured at 25 degreeC for 1.5 hours. At this time, by adjusting the temperature of the jacket of the kneader to 25 ° C, the temperature of the positron was controlled to 25 ° C. The said contact body after hardening was kneaded until it became clay form with the said kneader, and the mixture was obtained.

The mixture was introduced into a tank equipped with a screw conveyer at the bottom thereof, and the lid was covered with an inlet to seal it. Subsequently, the said mixture was discharged to the said screw conveyer, and it conveyed to the plunger-type extrusion molding machine. This plunger type extrusion machine is provided with 14 die | dyes which have 14 openings of 5.5 mm (phi) concentrically, and the inner diameter of this plunger type extrusion machine is 120 mm (phi). The quantity of the said mixture conveyed by the said screw conveyer is the quantity which is extruded once by the said plunger-type extrusion molding machine, and the remaining mixture was hold | maintained in the tank.

Here, while conveying the said mixture to the said screw conveyer, the said mixture was hardened at 25 degreeC for 1.5 hours. At this time, the temperature of the positron was controlled to 25 degreeC by adjusting the temperature of the jacket of the said tank provided with the said screw conveyer to 25 degreeC.

A catalyst molded body was produced and evaluated by extrusion molding and heat treatment in the same procedure as in Example 1 using the mixture after curing. The results are shown in Table 1.

Example 11

With respect to 100 parts of the catalyst precursor obtained in the same procedure as in Example 1, 5 parts of hydroxypropyl cellulose and 20 parts of ethyl alcohol were arranged with a double sigma blade so that the content of the mixture calculated from the charged amount was 16.0%. After putting into a kneader of a formula and making contact, the contact was cured at 25 degreeC for 3 hours. At this time, by adjusting the temperature of the jacket of the kneader to 25 ° C, the temperature of the positron was controlled to 25 ° C. The said contact body after hardening was kneaded until it became clay form with the said kneader, and the mixture was obtained.

The mixture was introduced into a tank equipped with a screw conveyer at the bottom thereof, and the lid was covered with an inlet to seal it. Subsequently, the said mixture was discharged to the said screw conveyer, and it conveyed to the plunger-type extrusion molding machine. This plunger type extrusion machine is provided with 14 die | dyes which have 14 openings of 5.5 mm (phi) concentrically, and the inner diameter of this plunger type extrusion machine is 120 mm (phi). The quantity of the said mixture conveyed by the said screw conveyer is the quantity which is extruded once by the said plunger-type extrusion molding machine, and the remaining mixture was hold | maintained in the tank.

The catalyst compact was manufactured and evaluated by extrusion molding and heat processing in the same procedure as Example 1 using the said mixture. The results are shown in Table 1.

Reference Example 1

To 1000 parts of pure water, 500 parts of ammonium paramolybdate, 12.4 parts of ammonium paratungstate, 2.3 parts of potassium nitrate, 27.5 parts of antimony trioxide, and 66.0 parts of bismuth trioxide were added and stirred by heating (A solution). Separately, 114.4 parts of ferric nitrate, 274.7 parts of cobalt nitrate, and 35.1 parts of zinc nitrate were sequentially added to 1,000 parts of pure water and dissolved (B solution). Subsequently, B liquid was added to A liquid to make an aqueous slurry. The mixed slurry containing the raw material compound of the catalyst component obtained as mentioned above was dried on the conditions of the dryer inlet temperature of 250 degreeC, and the rotating disk for slurry spraying 13,000 rpm using the cocurrent spray dryer, and obtained the catalyst precursor. The average particle diameter of this catalyst precursor was 46 micrometers.

To 100 parts of the catalyst precursor, 5 parts of hydroxypropyl cellulose and 30 parts of pure water were charged into a batch kneader having double sigma blades and brought into contact with each other so that the content of the mixture calculated from the charged amount was 22.2%. The contact was kneaded until it became clay, and a mixture was obtained.

The mixture was introduced into a tank equipped with a screw conveyer at the bottom thereof, and the lid was covered with an inlet to seal it. Subsequently, the said mixture was discharged to the said screw conveyer, and it conveyed to the plunger-type extrusion molding machine. This plunger type extrusion machine is provided with 14 die | dyes which have 14 openings of 5.5 mm (phi) concentrically, and the inner diameter of this plunger type extrusion machine is 120 mm (phi). The quantity of the said mixture conveyed by the said screw conveyer is the quantity which is extruded once by the said plunger-type extrusion molding machine, and the remaining mixture was hold | maintained in the tank.

Here, while conveying the said mixture to the said screw conveyer, the said mixture was hardened at 25 degreeC for 7 hours. At this time, the temperature of the positron was controlled to 25 degreeC by adjusting the temperature of the jacket of the said tank provided with the said screw conveyer to 25 degreeC.

The said mixture after hardening was extrusion-molded by the said plunger-type extrusion molding machine at the plunger moving speed of 100 mm / min. The extrudate discharged | emitted from the said die was cut | disconnected by rotating the piano wire at 375 rpm in the die surface, and the molded object was obtained.

The catalyst compact was obtained by heat-processing the said molded object at 90 degreeC for 12 hours with a hot air dryer. Moreover, the catalyst molded object was produced similarly about the mixture which remained in the tank, and the standard deviation of packing density and the fall differentiation rate were measured about these. Table 1 shows the content of the mixture calculated from the charged amount, the content of the mixture just before molding, the rate of change of the content, the standard deviation of the packing density, and the drop differentiation rate. On the other hand, the composition of the catalyst except oxygen obtained when calcining the catalyst molded body is Mo ₁₂ W _0.2 Bi _1.2 Fe _1.2 Sb _0.8 Co _4.0 Zn _0.5 K _0.1 .

Reference Example 2

Except having changed the curing time into 1 hour, it carried out similarly to the reference example 1, and manufactured and evaluated the catalyst molded object. The results are shown in Table 1.

In Examples 1 to 11 in which the rate of change in curing time, curing temperature, and the content of the liquid content was within the range of the present invention, the standard deviation of packing density was lower than that of Comparative Examples 1 to 5, and the quality nonuniformity of the catalyst molded body was reduced. Confirmed. In addition, in Example 4 in which the curing time exceeds 48 hours, and Example 5 in which the curing temperature exceeds 40 ° C, the standard deviation of the packing density is slightly higher than that of Examples 1 to 3, and the drop differentiation rate is high. It was confirmed that a catalyst having a low mechanical strength was produced, and it was found that there were optimum ranges for curing time and curing temperature, respectively. Moreover, even if the sum total of curing time and curing temperature are the same, Example 10 which performs some or all of the curing with respect to the contact material of process (1) compared with Example 1 which hardens with respect to a mixture in a conveyance process. And 11, the standard deviation of packing density was slightly high, and it turned out that the quality nonuniformity of a catalyst molded object can be reduced more by hardening in a conveyance process. On the other hand, from the reference examples 1 and 2, when phosphorus is not included as a catalyst component, even if the rate of change in curing time, curing temperature, and content rate is within the scope of the present invention, the effect of reducing the quality nonuniformity of the catalyst molded body is not obtained. I could see that not.

This application claims the priority based on Japanese Patent Application No. 2015-234745 for which it applied on December 1, 2015, and uses the whole of this indication here.

As mentioned above, although this invention was demonstrated with reference to embodiment and an Example, this invention is not limited to the said embodiment and Example. Various changes which can be understood by those skilled in the art can be made to the structure and details of the present invention within the scope of the present invention.

Claims (12)

A method for producing a catalyst for producing (meth) acrylic acid comprising at least molybdenum and phosphorus as a catalyst component, which is used when gaseous catalytic contact oxidation of (meth) acrolein with molecular oxygen to produce (meth) acrylic acid,
(1) mixing a catalyst precursor containing the catalyst component with a contact between a liquid and a binder to produce a mixture;
(2) forming a mixture by molding the mixture;
(3) a step of heat-treating the molded body,
At least one of the contact and the mixture is held at a temperature of 10 ° C. or more for a total of 2 hours or more after the contact is produced in the step (1) and before the molding is formed in the step (2). and,
When the content rate of the mixture calculated from the input amount in the step (1) is α% and the content rate of the mixture just before the molding in the step (2) is β%, the following formula ( A method for producing a catalyst for producing (meth) acrylic acid, wherein the rate of change of the content of the liquid content calculated by I) is from -10% to 10%.
% Change in content rate = (α-β) / α × 100 (I)
In addition, (alpha) is a moisture content rate based on the moisture content computed by following formula (II) from the mass a of the liquid thrown in at the process (1), and the mass b of the sum total of a catalyst precursor and a binder.
α = a / (a + b) × 100 (II)
In addition, (beta) is a content rate computed by following formula (III) from the mass c (g) after drying 10g of mixtures just before shaping | molding process (2) at normal pressure and 100 degreeC for 30 minutes.
β = (10-c) / 10 × 100 (III) The method of claim 1,
A method for producing a catalyst for producing (meth) acrylic acid, wherein a rate of change of the content of the liquid content calculated by the formula (I) is 0% or more and 10% or less. The method according to claim 1 or 2,
After the said contact is manufactured in the said process (1), and until it forms the said molded object in the said process (2), at least one of the said contact and said mixture is 10 hours or more in total for 2 hours or more 48 The manufacturing method of the catalyst for manufacturing (meth) acrylic acid hold | maintains below time. The method according to claim 1 or 2,
After the said contact is manufactured in the said process (1), and until it forms the said molded object in the said process (2), at least one of the said contact and said mixture is 10 degreeC or more and 40 degrees C or less in total 2 The manufacturing method of the catalyst for manufacturing (meth) acrylic acid hold | maintains more than time. The method according to claim 1 or 2,
The manufacturing method of the catalyst for (meth) acrylic acid production containing at least 1 conveyance process between each process of the said process (1)-the said process (3). The method of claim 5,
The manufacturing method of the catalyst for (meth) acrylic acid manufacturing containing the said conveyance process between the said process (1) and the said process (2). The method of claim 5,
The manufacturing method of the catalyst for (meth) acrylic acid manufacturing which performs the said conveyance process with a conveying machine. The method of claim 7, wherein
(Meth) acrylic acid which conveys by a screw conveyer, a belt conveyer conveyer, a chain conveyer conveyer, a roller conveyer conveyer, a vibrating conveyer, an extrusion conveyer, or a drop conveyer in the said conveyance process. Method for producing a catalyst for production. The method according to claim 1 or 2,
The manufacturing method of the catalyst for (meth) acrylic acid production in the said process (2) which shape | molds the said mixture using an extrusion molding machine. The method according to claim 1 or 2,
The manufacturing method of the catalyst for manufacturing (meth) acrylic acid whose said (mat) acrylic acid manufacturing catalyst is a composite oxide which has a composition represented by following formula (IV).
P _a Mo _b V _c Cu _d X _e Y _f Z _g O _h (IV)
(In formula (IV), P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively. X is at least one selected from the group consisting of arsenic, antimony and tellurium. Y represents bismuth, germanium, zirconium, silver, selenium, silicon, tungsten, boron, iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium, and lanthanum At least one element selected from the group 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 are each When the atom ratio of an element is represented and b = 12, a = 0.1-3, c = 0.01-3, d = 0.01-2, e are 0-3, f = 0-3, g = 0.01-3, h is the atomic ratio of oxygen necessary to satisfy the valence of each of the above elements.) The method according to claim 1 or 2,
A method for producing a catalyst for producing (meth) acrylic acid, wherein the acrylic acid production catalyst is a composite oxide having a composition represented by the following formula (V).
P _i Mo _j V _k A _l X ² _m Y ² _n O _o (V)
(In formula (V), P, Mo, V and O represent phosphorus, molybdenum, vanadium and oxygen, respectively. A is at least one element selected from the group consisting of iron, cobalt, chromium, aluminum and strontium. represents a. X ² is germanium, boron, arsenic, selenium, silver, represents at least one element selected from silicon, sodium, tellurium, lithium, antimony, the group consisting of potassium and barium. Y ² is magnesium At least one element selected from the group consisting of, titanium, manganese, copper, zinc, zirconium, niobium, tungsten, tantalum, calcium, tin and bismuth i, j, k, l, m, n And o represents the atomic ratio of each element, and when j = 12, i = 0.01-10, k = 0.01-6, l = 0-5, m = 0-10, n = 0-5, o is Is the atomic ratio of oxygen necessary to satisfy the valence of each of the above components.) A catalyst for producing (meth) acrylic acid is prepared by the method for producing a catalyst for producing (meth) acrylic acid according to claim 1 or 2, and (meth) acrolein is prepared by molecular oxygen in the presence of the catalyst for producing (meth) acrylic acid. A process for producing (meth) acrylic acid for gas phase contact oxidation.