JP6628661B2 - Method for producing catalyst for acrylic acid production, its catalyst, and method for producing acrylic acid using the catalyst - Google Patents

Description

  The present invention relates to a method for producing a catalyst suitable for producing acrylic acid by subjecting acrolein to catalytic gas phase oxidation in the presence of molecular oxygen or a molecular oxygen-containing gas to produce acrylic acid, and an acrylic acid using the catalyst. Related to the manufacture of.

Acrylic acid is industrially important as a raw material for various synthetic resins, paints, and plasticizers, and in recent years, its importance has been particularly increasing as a raw material for water-absorbing resins. Generally, acrylic acid produces acrolein by catalytically oxidizing propylene in the presence of molecular oxygen or a molecular oxygen-containing gas to produce acrolein, and further converts the obtained acrolein to molecular oxygen or a molecular oxygen-containing gas. It is produced by a two-step oxidation method in which catalytic vapor phase oxidation is performed to form acrylic acid in the presence of.
As a catalyst for producing acrylic acid by catalytically oxidizing acrolein in the presence of molecular oxygen or a molecular oxygen-containing gas to produce acrylic acid, a composite oxide catalyst mainly based on molybdenum-vanadium and its oxide Although the production method has been studied, the target catalyst performance such as selectivity and yield of acrylic acid is not always sufficient, and various proposals have been made by various companies for the purpose of improving the catalyst performance.

For example, in Patent Literature 1, in a method for producing a composite oxide catalyst containing at least molybdenum and vanadium used for producing acrylic acid by oxidizing acrolein with molecular oxygen, the catalyst raw materials are mixed and reacted, A production method is disclosed in which a catalyst precursor obtained by evaporation and concentration is steamed and then fired in an air atmosphere.
In Patent Literature 2, a catalyst precursor supply flow is caused to pass through one or more calcination zones at a substantially constant speed, and a gas is passed perpendicularly to a traveling direction. Discloses a production method in which the maximum temporal fluctuation and the local maximum temperature difference (temperature gradient) are controlled to 5 ° C. or less, respectively.
Patent Document 3 discloses a method for producing a MoV-based catalyst including a calcination step of calcining a raw material containing an organic substance to obtain a MoV-based catalyst, wherein the calcination temperature is 200 to 400 ° C and the holding time is 0.5 to 10 hours. A first step of baking, and a second step performed after the first step and baking at a baking temperature of 300 to 450 ° C. and a holding time of 0.5 to 10 hours, wherein the baking temperature of the second step is 1st A manufacturing method is disclosed in which the temperature is 50 ° C. or more higher than the firing temperature in the process.
Patent Document 4 discloses a method for producing an oxide catalyst including a step of supplying a catalyst precursor to a calciner and calcining the catalyst precursor at a temperature equal to or higher than the melting point of the metal oxide of the catalyst constituent element. A production method is disclosed in which the temperature of the body and / or the oxide catalyst is temporarily lowered to a temperature lower than the calcination temperature.

JP-A-5-329371 JP-T-2004-508931 JP 2008-238098 A JP 2009-261990 A

Acrylic acid is currently produced on a scale of millions of tons / year worldwide, and even if 0.1%, an increase in industrial scale yields significant economic benefits. Therefore, further improvement in the yield of acrylic acid and high productivity are demanded as industrially practical catalysts.
Thus, an object of the present invention is to provide a method for producing a catalyst suitable for producing acrylic acid having excellent catalytic performance such as catalytic activity and selectivity when producing acrylic acid from acrolein, the catalyst, and the catalyst. An object of the present invention is to provide a method for producing acrylic acid used.

  The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and found that acrolein containing molybdenum and vanadium as essential components is subjected to catalytic gas phase oxidation in the presence of molecular oxygen or a molecular oxygen-containing gas to form acrylic. The present inventors have found that a method for producing a catalyst for producing an acid, which includes a step of calcining in the presence of superheated steam in the production process, can solve the above problem, and have completed the present invention.

The present invention is described below.
[1] A method for producing a catalyst for producing acrylic acid by subjecting acrolein containing molybdenum and vanadium as essential components to catalytic gas phase oxidation in the presence of molecular oxygen or a gas containing molecular oxygen, comprising superheated steam A method for producing a catalyst for producing acrylic acid, comprising a step of calcining in the presence.
[2] The method for producing a catalyst according to [1], wherein a firing temperature for firing in the presence of the superheated steam is 320 to 420 ° C.
[3] The method for producing a catalyst according to [1] or [2], wherein the step of firing in the presence of superheated steam comprises two or more steps at different firing temperatures.
[4] The step of firing in the presence of superheated steam includes a first step in which the firing temperature is 320 to 400 ° C and a second step in which the firing temperature is 350 to 420 ° C, and the firing temperature in the first step. The method for producing a catalyst according to [3], wherein the calcination temperature in the second step is higher than that in the second step.
[5] The catalyst according to any one of [1] to [4], further including a step of calcining in an atmosphere without superheated steam, separately from the step of calcining in the presence of superheated steam. Production method.
[6] A catalyst for producing acrylic acid obtained by the production method according to any one of [1] to [5].
[7] A method for producing acrylic acid, comprising using the catalyst for producing acrylic acid according to [6].

  According to the present invention, by solving the above problems, it is possible to provide a catalyst that can be stably produced at a high yield over a long period of time when producing acrylic acid by subjecting acrolein to catalytic gas phase oxidation with molecular oxygen. Acrylic acid can be produced in high yield using the catalyst.

Hereinafter, the method for producing the catalyst according to the present invention and the method for producing acrylic acid using the catalyst will be described in detail, but the scope of the present invention is not limited to these descriptions, and the present invention is not limited to the following examples. The present invention can be appropriately modified and implemented without departing from the spirit of the invention.
The catalyst for producing acrylic acid produced by the present invention preferably has a composition of the catalytically active component represented by the following general formula (1).
MoaVbWcAdBeCfDgOh (1)
(Where Mo is molybdenum, V is vanadium, W is tungsten, A is at least one element selected from antimony and tin, B is chromium, manganese, iron, cobalt, nickel, copper, zinc, bismuth, tellurium and At least one element selected from niobium; C is at least one element selected from alkali metals and alkaline earth metals; D is at least one element selected from silicon, aluminum, titanium, zirconium and cerium; Is oxygen, a, b, c, d, e, f, g and h represent the number of atoms of Mo, V, W, A, B, C, D and O, and when a = 12, 2 ≦ b ≦ 14, 0 ≦ c ≦ 10, 0 ≦ d ≦ 5, 0 ≦ e ≦ 12, 0 ≦ f ≦ 5, 0 ≦ g ≦ 50, and h is a numerical value determined by the oxidation state of each element. )
As the above-mentioned catalytically active component, raw materials generally used for this kind of preparation can be used. For example, oxides, hydroxides, ammonium salts, nitrates, carbonates, sulfates, organic acid salts and the like of each element can be used. Or their aqueous solutions and sols, or compounds containing a plurality of elements can also be used.

  A starting material mixture is prepared by dissolving or suspending these starting materials in a solvent such as water (hereinafter sometimes referred to as a “raw material mixture preparation step”). The preparation method at that time is a method of sequentially mixing the above-mentioned starting materials in water, a method of preparing a plurality of aqueous solutions or aqueous slurries according to the types of the starting materials, and a method of sequentially mixing these, and the like. It may be prepared by a generally used method. The order of mixing the starting materials, the temperature, the pressure, the pH and the like are not particularly limited, and can be appropriately selected depending on the starting materials. It is preferable that the pH is controlled within the range of 4 to 10 by appropriately adding a nitrogen-containing compound such as nitric acid, ammonia, ammonium nitrate, and ammonium carbonate.

  Next, the obtained starting material mixture is dried to obtain a dried product (hereinafter sometimes referred to as “raw material mixture drying step”). Specifically, a method of obtaining a powdery dried product using a spray drier, a drum drier, or the like, a block-shaped or flake-shaped dried product which is heated in an air stream using a box-type dryer, a tunnel-type dryer, or the like. And a method in which the starting material mixture is once concentrated, evaporated to dryness to obtain a cake-like solid, and the solid is further subjected to the above heat treatment. When drying is performed using a dryer or the like, the atmosphere may be air, superheated steam, an inert gas, a mixed gas thereof, or the like. In addition, as a drying method under reduced pressure, for example, a block or powdery dried product can be obtained using a vacuum dryer. The drying temperature is not particularly limited, and may be appropriately selected, for example, in the range of 80 to 300 ° C.

The obtained dried product is sent to a subsequent molding process through a pulverizing process and a classification process for obtaining a powder having an appropriate particle size, if necessary. The particle size of the powder of the dried product at that time is not particularly limited, but is preferably 500 μm or less, preferably 200 μm or less, and more preferably 100 μm or less from the viewpoint of excellent moldability.
In the molding step of forming a dried product (hereinafter sometimes simply referred to as “molding step”), the molding method may be a tableting molding machine or an extrusion molding machine, or a certain shape. And a granulation method supported on any inert carrier. Alternatively, it can be produced by an evaporation to dryness method in which the starting material mixture is used in a liquid form without drying, and is absorbed or applied to a desired carrier while being heated over a long period of time and dried and supported. Further, after the dried product obtained in the raw material mixture liquid drying step is calcined in the presence of superheated steam, which will be described later, it can be produced as a molded body or a carrier by a general molding method or a granulation method. . Among these, in particular, a centrifugal flow coating method described in JP-A-63-200839 and a granulation method in which the particles are supported on an inert carrier by using a rocking mixer method described in JP-A-2004-136267 are described. preferable.

In the case of a molding method using a tableting machine or an extrusion molding machine, the shape is not particularly limited, and may be any shape such as a sphere, a column, a ring, and an irregular shape. Of course, in the case of a spherical shape, the shape need not be a true sphere, but may be a substantially spherical shape, and the same applies to a cylindrical shape and a ring shape.
As an inert carrier that can be used in the case of a granulation method or an evaporation to dryness method, alumina, silica, silica-alumina, titania, magnesia, steatite, cordierite, silica-magnesia, silicon carbide, silicon nitride, zeolite, etc. No. The shape is not particularly limited, and a known shape such as a sphere, a column, or a ring can be used.

In the above-mentioned molding step, a molding aid and a binder for improving the moldability of the dried product, a pore-forming agent for forming an appropriate pore in the catalyst, and the like, are generally used for the purpose of producing these catalysts. (Hereinafter, sometimes referred to as "auxiliary substance"), and among them, it is preferable to use a binder in the granulation method.
In addition to the auxiliary substance, a reinforcing agent can be used for the purpose of improving the mechanical strength of the catalyst. Specific examples include silica, alumina, ceramic fibers, glass fibers, carbon fibers, mineral fibers, metal fibers, various whiskers such as silicon carbide and silicon nitride, which are generally known as reinforcing agents, and the like. The crystal structure may be polycrystalline, single crystalline or amorphous, but polycrystalline or single crystalline is desirable. Further, a plurality of reinforcing agents having different fiber diameters, fiber lengths, materials, and the like may be used according to the shape and mechanical strength of the catalyst. The reinforcing agent may be added to the starting material mixture, or may be blended during the molding step.
Further, the molded body or the support after the molding step may be dried using a drier, hot air or the like before a firing step described later.

  In the present invention, firing in the presence of superheated steam is important. Although the cause is not clear, by firing in the presence of superheated steam, undesirable by-products such as carbon monoxide, carbon dioxide, and acetic acid are reduced, and undesired by-products on the catalyst surface are generated. It is considered that the number of reaction points to be performed decreased.

  The firing in the presence of the superheated steam (hereinafter sometimes referred to as “superheated steam firing”) can be carried out by various methods without any particular limitation. For example, the dried product obtained in the raw material mixture drying step, the formed body or the support obtained in the forming step (hereinafter, also referred to as “catalyst precursor”) may be directly contacted with superheated steam and fired. Alternatively, the catalyst precursor may be placed in a container or the like and then calcined in the presence of superheated steam. When filling the container, the shape of the container to be filled is not limited, and a lid or the like may be used.

  The concentration of the superheated steam is preferably 10% or more, more preferably 50% or more, and more preferably 90% or more. When the superheated steam concentration is not 100%, there is no limitation on gas species other than superheated steam, but it is preferable to use a general inert gas such as nitrogen, argon, krypton, and helium.

The firing furnace is not particularly limited, and a generally used box-type firing furnace or a tunnel-type firing furnace may be used, and it can be processed in the presence of superheated steam, such as a flow type, a closed type, and a circulation type. If there is, it is not limited.
The firing temperature of the superheated steam firing is from 320 to 420 ° C, preferably from 350 to 410 ° C. The firing time is preferably from 1 to 24 hours, more preferably from 1 to 10 hours.

  The firing step of superheated steam firing may be performed in two or more steps having different firing temperatures. When performing the calcination in two or more steps, the first step in which the calcination temperature is 320 to 400 ° C, preferably 320 to 380 ° C, and the second step in which the calcination temperature is 350 to 420 ° C, preferably 380 to 410 ° C In a preferred embodiment, the firing temperature in the second step is higher than the firing temperature in the first step. The firing time of the superheated steam firing is preferably 1 to 24 hours in each step, and more preferably 1 to 10 hours. The heating rate in the process is preferably 0.1 ° C./min or more and 20 ° C./min or less, more preferably 1 ° C./min or more and 15 ° C./min or less. If the heating rate is 15 ° C./min or more, ammonia and the like are rapidly exothermicly decomposed, and the performance tends to decrease due to thermal deterioration of the catalyst due to the heat generation.

  Further, in the baking step of the superheated steam baking, it is preferable to perform the baking continuously without taking out the charged catalyst precursor when moving to the next step having a different baking temperature, for example, the first step and the second step described above. There may be a temperature lowering process once.

  In addition to the above-described superheated steam firing, a step of firing under conditions in which superheated steam is not introduced, that is, in an atmosphere in which no superheated steam is present (hereinafter, sometimes referred to as “another firing step”) may be included. The separate firing step may be performed before and / or after the superheated steam firing, or may be performed between each step of the superheated steam firing, but is preferably performed before and / or after the superheated steam firing. More preferably, it is performed before the superheated steam calcination. The firing temperature in the separate firing step is 320 to 420 ° C, preferably 350 to 410 ° C, and the firing time is preferably 1 to 24 hours, and more preferably 1 to 10 hours. The atmosphere without superheated steam is not particularly limited as long as superheated steam is not introduced, and examples thereof include an air atmosphere, a general inert gas atmosphere such as nitrogen, argon, krypton, and helium, and a mixed gas atmosphere thereof. . Further, the rate of temperature rise in the separate firing step is preferably 0.1 ° C./min or more and 20 ° C./min or less, more preferably 1 ° C./min or more and 15 ° C./min or less.

  There is no particular limitation on the reactor used for producing acrylic acid by subjecting acrolein to catalytic gas-phase oxidation with molecular oxygen using the catalyst for producing acrylic acid of the present invention, and there are no particular restrictions on the reactor. Both a vessel and a moving bed reactor can be used, but a fixed bed reactor is usually used.

  When the catalyst is charged into the reactor, it is not necessary to use a single catalyst.For example, a plurality of catalysts having different activities are used, and these are charged in the order of different activities, or a part of the catalyst is deactivated. It may be diluted with a carrier or the like.

The reaction conditions in the present invention are not particularly limited, and any conditions generally used for this type of reaction can be used. For example, 1 to 15% by volume, preferably 4 to 12% by volume of acrolein, 0.5 to 25% by volume, preferably 2 to 20% by volume of molecular oxygen, 0 to 30% by volume, preferably 0 to A mixed gas consisting of ２５25% by volume of water vapor and the balance of an inert gas such as nitrogen under a pressure of 0.1 to 1.0 MPa in a temperature range of 200 to 400 ° C. under a pressure of 300 to 8,000 h ⁻¹ (STP). What is necessary is just to contact an oxidation catalyst at space velocity.

  As the reaction gas, not only a mixed gas composed of acrolein, molecular oxygen and an inert gas, but also a mixed gas containing acrolein obtained by a dehydration reaction of glycerin or an oxidation reaction of propylene can be used. Air or oxygen can be added to the mixed gas as needed.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. In the following, “parts by mass” may be referred to as “parts” for convenience. Acrolein conversion, acrylic acid selectivity, and acrylic acid yield in Examples and Comparative Examples were determined by the following equations.
Acrolein conversion (mol%)
= (Mol number of reacted acrolein) / (mol number of supplied acrolein) × 100
Acrylic acid selectivity (mol%)
= (Mol number of acrylic acid generated) / (mol number of reacted acrolein) × 100
Acrylic acid yield (mol%)
= (Mol number of generated acrylic acid) / (mol number of supplied acrolein) × 100

<Example 1>
[Catalyst preparation]
While heating and stirring 1000 parts of pure water, 100 parts of ammonium paramolybdate, 23.2 parts of ammonium metavanadate, and 16.6 parts of ammonium paratungstate were dissolved therein. Separately, 19.4 parts of copper nitrate were dissolved while heating and stirring 100 parts of pure water. The resulting two solutions were mixed, and 6.2 parts of antimony trioxide and 9.7 parts of aluminum oxide were added to obtain a starting material mixture. After the starting material mixture was spray-dried, the obtained dried product was sieved to 250 μm or less to obtain a powder of a catalyst precursor. An α-alumina spherical carrier having an average particle size of 4 mm is charged into a centrifugal fluidized coating apparatus, and then the carrier is impregnated with pure water. After that, the catalyst precursor powder is supported on the carrier and dried with hot air at about 90 ° C. Thus, a carrier was obtained. A part of the obtained carrier is put in a crucible, superheated steam is introduced into the furnace from room temperature by a spray nozzle in a box-type firing furnace, the temperature is raised at 2 ° C./min, and the catalyst is fired at 380 ° C. for 7 hours. 1 was obtained.
The loading ratio of this catalyst 1 was 30% by mass, and the composition of metal elements excluding oxygen was as follows.
Catalyst composition: Mo ₁₂ V _4.3 Sb _0.8 W _1.2 Cu _1.6 Al _3.6
The loading was determined by the following equation.
Loading ratio (mass%) = (mass (g) of supported catalyst powder) / (mass (g) of carrier used) × 100

[Oxidation reaction]
A SUS U-shaped reaction tube having a total length of 300 mm and an inner diameter of 18 mm is filled with the catalyst 1 so that the layer length becomes 100 mm, and a mixed gas of 2% by volume of acrolein, 3% by volume of oxygen, 10% by volume of steam and 85% by volume of nitrogen is used. Was introduced at a space velocity of 5000 hr ^-1 (STP) to perform an acrolein oxidation reaction. The reaction temperature was adjusted so that the conversion of acrolein was about 93.5%. Table 1 shows the results of the reaction.

<Example 2>
In Example 1, a part of the obtained support was put into a crucible, superheated steam was introduced into the furnace from room temperature by a spray nozzle in a box-type firing furnace, and the temperature was raised at 2 ° C./min. A catalyst 2 was obtained in the same manner as in Example 1 except that the calcination was performed for an hour. The loading rate of the catalyst 2 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. An acrolein oxidation reaction was carried out using Catalyst 2 in the same manner as in Example 1. Table 1 shows the results.

<Example 3>
In Example 1, a part of the obtained carrier was put into a crucible, superheated steam was introduced into the furnace from room temperature by a spray nozzle in a box-type firing furnace, and the temperature was raised at 15 ° C./min. After calcining at 370 ° C. for 3 hours, the temperature was increased with superheated steam at 19 ° C./min, and the catalyst was prepared in the same manner as in Example 1 except that calcining was performed at 400 ° C. for 5 hours as a second step. The loading ratio of the catalyst 3 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. Using catalyst 3, an acrolein oxidation reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

<Example 4>
In Example 1, a part of the obtained carrier was put into a crucible, superheated steam was introduced into the furnace from a room temperature by a spray nozzle in a box-type firing furnace, and the temperature was raised at 2 ° C./min. After calcination for an hour, a catalyst 4 was prepared in the same manner as in Example 1 except that calcination was performed at 390 ° C. for 5 hours in an N ₂ atmosphere as a separate calcination step. The loading ratio of the catalyst 4 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. Using catalyst 4, an acrolein oxidation reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

<Example 5>
In Example 1, a part of the obtained carrier was put into a crucible, superheated steam was introduced into the furnace from room temperature by a spray nozzle in a box-type firing furnace, and the temperature was raised at 2 ° C./min. After calcination for an hour, a catalyst 5 was prepared in the same manner as in Example 1 except that calcination was performed at 380 ° C. for 5 hours in an atmosphere of 10% O _{2 and} 90% N ₂ as a separate calcination step. The loading rate of this catalyst 5 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. Using catalyst 5, an acrolein oxidation reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

<Example 6>
In Example 1, a part of the obtained support was put in a crucible, and as a separate firing step, the temperature was raised from room temperature to 2 ° C./min from room temperature in a N ₂ atmosphere in a box type firing furnace, followed by firing at 330 ° C. for 3 hours. Thereafter, a catalyst 6 was prepared in the same manner as in Example 1 except that superheated steam was introduced into the furnace through a spray nozzle and calcined at 380 ° C. for 7 hours. The loading ratio of the catalyst 6 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. An acrolein oxidation reaction was carried out using Catalyst 6 in the same manner as in Example 1. Table 1 shows the results.

<Example 7>
In Example 1, a part of the obtained support was put into a crucible, and as a separate firing step, the temperature was raised from room temperature in a box-type firing furnace at room temperature at an O ₂ concentration of 10% and an N ₂ concentration of 90% at 2 ° C./min. After calcining at 350 ° C. for 3 hours, a catalyst 7 was prepared in the same manner as in Example 1 except that superheated steam was introduced into the furnace through a spray nozzle and calcined at 390 ° C. for 5 hours. The loading ratio of this catalyst 7 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. Using catalyst 7, an acrolein oxidation reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

<Example 8>
In Example 1, a part of the obtained support was put into a crucible, and as a separate firing step, the temperature was raised from room temperature in a box-type firing furnace at room temperature at an O ₂ concentration of 10% and an N ₂ concentration of 90% at 2 ° C./min. After calcination at 380 ° C. for 3 hours, a catalyst 8 was prepared in the same manner as in Example 1 except that superheated steam was introduced into the furnace through a spray nozzle and calcined at 410 ° C. for 1 hour. The loading ratio of the catalyst 8 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. Using catalyst 8, an acrolein oxidation reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 1>
In Example 1, placed in a portion of the resulting carrier in the crucible, O ₂ concentration of 10% from room temperature in a box sintering furnace in place of the superheated steam calcination at N ₂ concentration 90% rise at 2 ° C. / min Catalyst 9 was obtained in the same manner as in Example 1, except that the mixture was heated and calcined at 380 ° C for 5 hours. The loading ratio of the catalyst 9 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. An acrolein oxidation reaction was carried out using Catalyst 9 in the same manner as in Example 1. Table 1 shows the results.

<Comparative Example 2>
In Example 1, a part of the obtained support was put into a crucible, and instead of superheated steam firing, a box-type firing furnace was used at room temperature at an O ₂ concentration of 10% and an N ₂ concentration of 90% at 2 ° C./min. Catalyst 10 was obtained in the same manner as in Example 1, except that the temperature was raised, and the mixture was calcined at 330 ° C. for 5 hours, and the temperature was further changed and calcined at 390 ° C. for 4 hours. The loading ratio of the catalyst 10 and the metal element composition of the catalytically active component excluding oxygen were the same as those of the catalyst 1. An acrolein oxidation reaction was carried out in the same manner as in Example 1 using the catalyst 10. Table 1 shows the results.

Claims (6)

A method for producing a catalyst for producing acrylic acid by catalytic vapor phase oxidation of acrolein containing molybdenum and vanadium as essential components in the presence of molecular oxygen or a molecular oxygen-containing gas, in the presence of superheated steam A method for producing a catalyst for producing acrylic acid, comprising a step of calcining in an atmosphere without superheated steam, separately from the step of calcining and the step of further calcining in the presence of superheated steam .   The method for producing a catalyst according to claim 1, wherein a firing temperature for firing in the presence of the superheated steam is 320 to 420 ° C.   The method for producing a catalyst according to claim 1 or 2, wherein the step of firing in the presence of superheated steam comprises two or more steps at different firing temperatures.   The step of firing in the presence of superheated steam includes a first step in which the firing temperature is 320 to 400 ° C and a second step in which the firing temperature is 350 to 420 ° C, with respect to the firing temperature in the first step. The method for producing a catalyst according to claim 3, wherein the calcination temperature in the second step is higher. 2. The process of firing in the presence of superheated steam, wherein an inert gas is used as a gas other than the superheated steam when the superheated steam concentration is 50% or more and the superheated steam concentration is not 100%. A method for producing a catalyst according to any one of claims 1 to 4. A method for producing acrylic acid, comprising using the catalyst for producing acrylic acid obtained by the production method according to claim 1 .