JP2007130541A - Catalyst for producing methacrylic acid, method for producing the same, and method for producing methacrylic acid - Google Patents

Catalyst for producing methacrylic acid, method for producing the same, and method for producing methacrylic acid Download PDF

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JP2007130541A
JP2007130541A JP2005324617A JP2005324617A JP2007130541A JP 2007130541 A JP2007130541 A JP 2007130541A JP 2005324617 A JP2005324617 A JP 2005324617A JP 2005324617 A JP2005324617 A JP 2005324617A JP 2007130541 A JP2007130541 A JP 2007130541A
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methacrylic acid
catalyst
producing
method
liquid
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JP4961132B2 (en
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Tomomichi Hino
Harumoto Sato
Shigeo Tanaka
Daisuke Yasuda
晴基 佐藤
大介 安田
智道 日野
茂穂 田中
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Mitsubishi Rayon Co Ltd
三菱レイヨン株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/50Improvements relating to the production of products other than chlorine, adipic acid, caprolactam, or chlorodifluoromethane, e.g. bulk or fine chemicals or pharmaceuticals
    • Y02P20/52Improvements relating to the production of products other than chlorine, adipic acid, caprolactam, or chlorodifluoromethane, e.g. bulk or fine chemicals or pharmaceuticals using catalysts, e.g. selective catalysts

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for producing methacrylic acid, which has high catalytic performance; to provide a method for manufacturing the catalyst for producing methacrylic acid by which the catalyst capable of obtaining dried powder excellent in fluidity and high in catalytic performance can be obtained; and to provide a method for producing methacrylic acid in high yield. <P>SOLUTION: The method for producing the catalyst for producing methacrylic acid comprises steps of: concentrating a solution or slurry containing phosphorus and molybdenum to obtain a concentrated liquid; decreasing the viscosity of the concentrated liquid; reconcentrating the viscosity-decreased concentrated liquid; and drying the reconcentrated liquid. The methacrylic acid is produced by subjecting methacrolein to vapor-phase catalytic oxidation of molecular oxygen by using the catalyst for producing methacrylic acid obtained by the method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalyst for producing methacrylic acid for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen, a method for producing the same, and a method for producing methacrylic acid using the catalyst for producing methacrylic acid.

As a methacrylic acid production catalyst for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen, a heteropolyacid catalyst containing molybdenum and phosphorus is known. As a method for producing a catalyst for producing methacrylic acid, for example, the following method has been proposed.
(1) A method for producing a catalyst for methacrylic acid production using 6 to 17 mol of ammonia with respect to 12 mol of molybdenum atoms in the catalyst slurry (Patent Document 1).
(2) A catalyst for methacrylic acid production that prepares a catalyst slurry having a particle size distribution in which the number of particles having a particle diameter of 0.05 to 2.0 μm is 10% or less as the catalyst slurry before concentration Manufacturing method (Patent Document 2).

However, the catalysts obtained by the production methods (1) and (2) are industrial catalysts from the viewpoint of the fluidity of the powdered catalyst obtained by drying and the performance of the molded catalyst obtained by molding the powdered catalyst. As insufficient.
JP 2003-154273 A JP 2005-066476 A

The following may be considered as the reason why there are problems in the fluidity and catalyst performance of the catalyst obtained by the production methods (1) and (2).
For example, the catalyst slurry is prepared as follows. A solution in which a molybdenum compound is dissolved or suspended in a solvent or dispersion (hereinafter referred to as a solvent), a catalyst component element other than molybdenum (excluding oxygen), or a compound in which it is dissolved or suspended in a solvent The mixture is mixed with a liquid B to mix the liquid B with a liquid C in which ammonia and / or an ammonia compound is dissolved or suspended in a solvent to obtain a catalyst slurry.

When the temperature at the time of mixing the B liquid and the C liquid exceeds 80 ° C., the fluidity of the dry powder (hereinafter referred to as dry powder) obtained by drying is improved. descend. In addition, when the temperature when mixing the B liquid and the C liquid is 80 ° C. or lower, the performance of the catalyst should be improved. However, in practice, the fluidity of the dry powder is lowered, and the moldability becomes worse. As a result, the performance of the molded catalyst decreases.
Therefore, there is a demand for a method for producing a catalyst for methacrylic acid production in which a dry powder having good fluidity is obtained and a catalyst having high catalytic performance is obtained.

  An object of the present invention is to provide a catalyst for producing methacrylic acid having a high catalytic performance, a method for producing a catalyst for producing methacrylic acid that can provide a dry powder having good fluidity and a catalyst having high catalytic performance, and It is providing the manufacturing method of methacrylic acid which can be manufactured with a yield.

  The method for producing a catalyst for producing methacrylic acid according to the present invention is a method for producing a catalyst containing phosphorus and molybdenum, which is used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen. A step of concentrating a solution or slurry containing molybdenum and molybdenum to obtain a concentrate, a step of reducing the viscosity of the concentrate, a step of re-concentrating the concentrate with reduced viscosity, and a step of drying the re-concentrated concentrate It is characterized by having.

The catalyst for producing methacrylic acid of the present invention is a catalyst produced by the method for producing a catalyst for producing methacrylic acid of the present invention.
The method for producing methacrylic acid according to the present invention comprises using the catalyst for producing methacrylic acid produced by the method for producing a catalyst for producing methacrylic acid according to the present invention and subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen to produce methacrylic acid. It is characterized by manufacturing.

The catalyst for producing methacrylic acid of the present invention has high catalytic performance.
According to the method for producing a catalyst for producing methacrylic acid of the present invention, a dry powder having good fluidity is obtained and a catalyst having high catalytic performance is obtained.
According to the method for producing methacrylic acid of the present invention, methacrylic acid can be produced in high yield.

The catalyst for producing methacrylic acid of the present invention is preferably a composite oxide represented by the composition formula (1).
Mo a P b Cu c V d X e Y f O g (1)

  In the formula, Mo, P, Cu, V and O represent molybdenum, phosphorus, copper, vanadium and oxygen, respectively, and X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium. Y represents iron, cobalt, nickel, zinc, magnesium, calcium, strontium, barium, titanium, chromium, tungsten, manganese, silver, boron, silicon, aluminum, gallium, germanium, tin, lead, arsenic, antimony, bismuth Represents at least one element selected from the group consisting of niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, wherein a, b, c, d, e, f and g are each element Wherein a ≦ 12, 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 3, 0 01 ≦ d ≦ 3,0.01 a ≦ e ≦ 3,0 ≦ f ≦ 3, g is the atomic ratio of oxygen required to satisfy the atomic ratio of the respective elements.

  The catalyst for producing methacrylic acid of the present invention includes, for example, a step of preparing a solution or slurry containing phosphorus and molybdenum (preparation step), a step of concentrating the solution or slurry to obtain a concentrated solution (concentration step), and a concentration step. A step of reducing the viscosity of the liquid (low viscosity step), a step of re-concentrating the concentrated solution with reduced viscosity (re-concentration step), and a step of drying the re-concentrated concentrate to obtain dry powder (drying step) ), And if necessary, a dry powder is molded to obtain a molded product (molding step), and a dry powder or molded product is fired (firing step).

<Preparation process>
A solution or slurry containing phosphorus and molybdenum is a solution A in which a molybdenum compound is dissolved or suspended in a solvent, a compound of an element other than molybdenum (excluding oxygen), or a solution in which it is dissolved or suspended in a solvent. To prepare a B liquid, and the B liquid is mixed with a C liquid in which ammonia and / or an ammonia compound are dissolved or suspended in a solvent.

(Preparation of liquid A)
Liquid A is prepared by dissolving or suspending a molybdenum compound (catalyst raw material) in a solvent. It is preferable that the liquid A does not contain a catalyst component element other than molybdenum (excluding oxygen) or a compound, that is, other catalyst raw materials.
Examples of the molybdenum compound include molybdenum trioxide, molybdic acid, and the like. A molybdenum compound may be used individually by 1 type, and may use 2 or more types together.
As a solvent of A liquid, water is preferable.

The content ratio (mass ratio) of molybdenum and the solvent in the liquid A is usually 1: 0.1 to 1: 100.
The state of the A liquid is not particularly limited, and may be a solution in which the molybdenum compound is completely dissolved in a solvent, or may be a slurry in which a part or all of the molybdenum compound is suspended in the solvent.
Solution A may be usually prepared by stirring at room temperature, but it may be prepared by heating to about 100 ° C. if necessary.

(Preparation of liquid B)
The liquid B is a mixture of a catalyst component element (excluding oxygen) other than molybdenum (catalyst raw material), or a solution or suspension thereof dissolved in a solvent, and the liquid A.
Examples of compounds of catalyst component elements other than molybdenum include nitrates, carbonates and hydroxides of each element.

Examples of the phosphorus compound include orthophosphoric acid, phosphorus pentoxide, and ammonium phosphate.
Examples of the vanadium compound include vanadium pentoxide and ammonium metavanadate.
Examples of the cesium compound include cesium nitrate, cesium carbonate, and cesium hydroxide.
A catalyst raw material may be used individually by 1 type for each element, and may use 2 or more types together.

  As a mixing method, for example, a method of sequentially adding a compound of a catalyst component element (excluding oxygen) other than molybdenum, or a solution or suspension thereof dissolved in a solvent to a container containing liquid A; other than molybdenum A method of adding solution A to a compound of catalyst component elements (excluding oxygen) or a solution or suspension thereof dissolved in a solvent; solution A and catalyst elements other than molybdenum (excluding oxygen) in a container Examples thereof include a method in which a compound, or a compound dissolved or suspended in a solvent, is poured simultaneously. Mixing is usually carried out with stirring.

  As for the temperature of the solution at the time of mixing, 100 degrees C or less is preferable. Moreover, you may heat-process etc. suitably with respect to the obtained solution or slurry. The temperature of the heat treatment is preferably less than 100 ° C, but may be set to 100 ° C or higher using an autoclave or the like as necessary. The heat treatment time may be determined as appropriate.

(Preparation of liquid C)
Liquid C is prepared by dissolving or suspending ammonia and / or an ammonia compound in a solvent. The liquid C may contain, in addition to ammonia and an ammonia compound, a catalyst component element other than molybdenum (excluding oxygen) unless it is a total amount, but it is preferable not to contain these.

Examples of ammonia and ammonia compounds include ammonia (ammonia water), ammonium carbonate, ammonium hydrogen carbonate, ammonium nitrate, and the like. Ammonia and / or ammonia compounds may be used alone or in combination of two or more.
As a solvent of C liquid, water is preferable.

The content ratio (mass ratio) of ammonia and the ammonia compound in C and the solvent is usually 1: 0.1 to 1: 100.
The state of the liquid C is not particularly limited, and may be a solution in which ammonia and / or an ammonia compound is completely dissolved in a solvent, or may be a slurry in which a part or the whole amount is suspended in the solvent.
The C liquid may be usually prepared by stirring at room temperature, but may be prepared by heating in a temperature range where ammonia does not evaporate as necessary.

(Mixing of B liquid and C liquid)
Liquid B and liquid C are mixed to prepare a solution or slurry containing phosphorus and molybdenum as catalyst precursors.
As a mixing method of the B liquid and the C liquid, for example, a method of adding the C liquid to the container containing the B liquid; a method of adding the B liquid to the container containing the C liquid; and simultaneously pouring the B liquid and the C liquid into the container Methods and the like. Mixing is usually carried out with stirring. In mixing, it is preferable that the liquid B is as uniform as possible.

The mixing ratio of the B liquid and the C liquid is such that a catalyst having a high methacrylic acid yield is obtained, and the amount of ammonia and the ammonia compound in the C liquid is 6 mol with respect to 12 mol of molybdenum atoms in the B liquid. The above is preferable, 7 mol or more is more preferable, 17 mol or less is preferable, and 15 mol or less is more preferable.
The state of the mixed liquid of the B liquid and the C liquid may be a solution or a slurry.
40-80 degreeC is preferable and the temperature in the case of mixing has more preferable 50-75 degreeC. What is necessary is just to determine a heating time suitably.

<Concentration process>
Concentration is an operation of heating a solution or slurry containing phosphorus and molybdenum to volatilize a solvent or the like in the solution or slurry.
Concentration can be performed, for example, by heating a container such as a reaction vessel containing a solution or slurry containing phosphorus and molybdenum using a heat source such as an electric heater or steam. The heating temperature is preferably 50 to 120 ° C, more preferably 90 to 110 ° C.

During the concentration, the viscosity of the concentrated solution is measured, and the concentration is terminated when the viscosity is in the range of 0.5 to 1.3 Pa · s, preferably in the range of 0.6 to 1.0 Pa · s. When the viscosity of the concentrated liquid at the end of concentration is less than 0.5 Pa · s or exceeds 1.3 Pa · s, when a drum dryer is used in the drying process, the recovery rate of the powdered catalyst may deteriorate due to dripping, Not only does it cause problems such as an increase in the water concentration of the powdered catalyst due to insufficient drying, but also the compressibility of the powdered catalyst is high, resulting in poor fluidity. The measurement of the viscosity may be continuous or intermittent, but it is preferable to measure the viscosity intermittently within 5 minutes.
The concentration can be completed by an operation such as covering a container such as a concentration tank so that the water does not volatilize any more.

<Low viscosity process>
As a method for reducing the viscosity of the concentrate, for example, there are a method of cooling the concentrate and maintaining the state, a method of adding a solvent, and the like. When the specific gravity of the concentrate is suitable for the subsequent steps, the former method is preferable because there is no change in the specific gravity in the low viscosity step. On the other hand, when the specific gravity of the concentrate is higher than a suitable specific gravity, the latter method can be adopted. The specific gravity of the concentrated liquid whose viscosity has been reduced affects the specific gravity of a concentrated liquid (hereinafter referred to as a reconcentrated liquid) obtained in a reconcentration step described later. The viscosity and specific gravity of the re-concentrated liquid may affect the fluidity of the dry powder obtained in the drying step, and the method for reducing the viscosity is selected in consideration of these conditions.
In the case of the former method, the cooling temperature should just be lower than the temperature of a concentration process, and 50-80 degreeC is preferable. Examples of the cooling method include a method of flowing water to the outside of the container containing the concentrated liquid. The holding time is preferably 0.5 to 24 hours, and more preferably 2 to 5 hours.

<Reconcentration process>
The re-concentration can be performed by the same method as the above-described concentration step. The temperature of the concentrate at the time of re-concentration and the viscosity of the re-concentrate at the end of re-concentration may be in the same range as in the above-described concentration step. Further, the specific gravity of the re-concentrate is preferably 1.4~2.0 × 10 3 kg / m 3 , more preferably 1.5~1.9 × 10 3 kg / m 3 .
The end of the reconcentration can be performed by an operation such as covering a vessel such as a reaction tank so that the moisture does not volatilize any more.

<Drying process>
Examples of drying methods include various methods such as drum drying, airflow drying, evaporation to dryness, and spray drying. The dryer used for drying is not particularly limited. In the present invention, a drum drying method using a drum dryer is preferred.
Drying conditions such as drying temperature and time are not particularly limited. A dry powder can be obtained by appropriately changing the drying conditions.

In this way, a dry powder with good fluidity is obtained. The fluidity can be evaluated by the degree of compression. The degree of compression is preferably 40 or less when tableting is performed.
The degree of compression (hereinafter referred to as C p ) is an index representing the fluidity of the powder, and the mass of the powder after gently filling the container with a fixed volume and scraping off the overflowed portion. Loosely packed bulk density (hereinafter referred to as ρ a ) obtained from the ratio to the volume of the powder, and gently filling the powder in a fixed volume container, and tapping the container filled with the powder up and down From a difference in bulk density (hereinafter referred to as ρ p ) of dense packing obtained from a ratio of the mass of the powder after scraping off the overflowed portion after a certain tapping and the volume of the powder, as follows. The larger this value, the lower the fluidity of the powder.
C p = (ρ p −ρ a ) / ρ p × 100

<Molding process>
The dried powder may be pulverized if necessary and then directly fired without forming, but is usually fired after being formed into a molded product.
Examples of the molding method include known dry or wet molding methods. It is preferable to mold without including a carrier such as silica. Examples of the molding method include tableting molding, press molding, extrusion molding, granulation molding and the like.
The shape of the molded product is not particularly limited, and examples thereof include a columnar shape, a ring shape, and a spherical shape.
In molding, a small amount of known additives such as graphite and talc may be added.

<Baking process>
The dried powder or molded product is fired to obtain a catalyst for producing methacrylic acid. The fired dry powder is appropriately formed by the method described in the above forming step.
As the firing method and firing conditions, known treatment methods and conditions may be applied. Firing varies depending on the catalyst raw material used, catalyst composition, preparation method, etc., but is usually 200 to 500 ° C., preferably 300 to 450 ° C. under an oxygen-containing gas flow such as air and / or an inert gas flow. 0.5 hours or more, preferably 1 to 40 hours. Here, the inert gas refers to a gas that does not decrease the reaction activity of the catalyst, and specifically includes nitrogen, carbon dioxide, helium, argon, and the like.

<Method for producing methacrylic acid>
Next, the manufacturing method of methacrylic acid of this invention is demonstrated.
The method for producing methacrylic acid of the present invention is a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the methacrylic acid production catalyst of the present invention obtained as described above. .
The reaction is usually carried out in a fixed bed. Further, the catalyst layer may be one layer or two or more layers. The catalyst for producing methacrylic acid may be supported on a carrier, or may be a mixture of other additive components.

When producing methacrylic acid using the methacrylic acid production catalyst of the present invention, a raw material gas containing methacrolein and molecular oxygen is brought into contact with the catalyst.
The methacrolein concentration in the raw material gas can be varied within a wide range, preferably 1 to 20% by volume, particularly preferably 3 to 10% by volume.
The molecular oxygen concentration in the raw material gas is preferably 0.4 to 4 mol, particularly preferably 0.5 to 3 mol, relative to 1 mol of methacrolein.
As the molecular oxygen source, air is preferable from the viewpoint of economy. If necessary, a gas enriched with molecular oxygen by adding pure oxygen to air may be used.

The source gas may be obtained by diluting methacrolein and a molecular oxygen source with an inert gas such as nitrogen or carbon dioxide.
Water vapor may be added to the source gas. By performing the reaction in the presence of water, methacrylic acid can be obtained in a higher yield. The concentration of water vapor in the raw material gas is preferably from 0.1 to 50% by volume, particularly preferably from 1 to 40% by volume.
The source gas may contain a small amount of impurities such as a lower saturated aldehyde, but the amount is preferably as small as possible.

The contact time between the raw material gas and the catalyst for producing methacrylic acid is preferably 1.5 to 15 seconds, and more preferably 2 to 5 seconds.
The reaction pressure is preferably from atmospheric pressure to several atmospheres.
The reaction temperature is preferably 230 to 450 ° C, particularly preferably 250 to 400 ° C.

  In the method for producing a catalyst for producing methacrylic acid according to the present invention described above, after concentrating a solution or slurry containing phosphorus and molybdenum, it is once cooled and held to lower the viscosity of the concentrate, and then cooled. Since it is heated and concentrated again until the viscosity becomes the same level as before holding, a dry powder with more excellent fluidity can be obtained. As a result, problems related to powder transportation such as hopper bridge formation are solved, and powder mixing into molds for tableting and press molding can be easily performed in a short time. Is obtained in a high yield. Therefore, the methacrylic acid production catalyst obtained by the production method of the present invention has a high yield of methacrylic acid. Moreover, by using this catalyst, methacrylic acid can be obtained in high yield.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to these Examples.
“Parts” in Examples and Comparative Examples means parts by mass.
The catalyst composition was determined from the raw material charge of the catalyst component.

The reaction raw material gas and the product were analyzed using gas chromatography.
From the results of gas chromatography, methacrolein conversion, methacrylic acid selectivity, and single flow yield of methacrylic acid were determined by the following equations.
Conversion rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Single flow yield of methacrylic acid (%) = (C / A) × 100
In the formula, A is the number of moles of methacrolein supplied, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced.

The degree of compression C p was measured using a multi-tester MT-1001 type (manufactured by Seishin Enterprise Co., Ltd.). The measurement was carried out by dropping powder into a 100 (cc) cell container through a funnel and filling it, then scraping off the overflowed part, and determining the bulk density of the loose filling from the mass of the filled powder and the volume of the cell container ( ρ a ), and after dropping powder into a 100 (cc) cell container through a funnel and filling it, tapping stroke 18 (mm), tapping speed 1 (times / second) and tapping 180 times Then, the portion overflowing from the cell was scraped, and the bulk density (ρ p ) of the closely packed powder was obtained from the mass of the filled powder and the volume of the cell container, and C p was obtained from the following equation.
C p = (ρ p −ρ a ) / ρ p × 100
The viscosity (Pa · s) of the slurry was measured using a B-type viscometer after a part of the slurry was sampled and sufficiently stirred so that the solid content was not separated.
The specific gravity (kg / m 3 ) of the slurry was calculated by sampling a part of the slurry, measuring the volume (m 3 ) and mass (kg), and dividing the mass by the volume.
The moisture content of the dry powder was measured using a ket moisture meter.

[Example 1]
(Preparation process)
Liquid A was obtained by adding 100 parts of molybdenum trioxide to 400 parts of pure water.
7.3 parts of 85 mass% phosphoric acid aqueous solution, 4.2 parts of vanadium pentoxide, 0.9 part of copper oxide, and 0.2 part of iron oxide were added to A liquid, and it stirred under recirculation | reflux for 5 hours. After cooling this solution to 50 ° C., a solution prepared by dissolving 9.0 parts of cesium nitrate in 30 parts of pure water was added dropwise and stirred for 15 minutes to obtain a solution B.
While maintaining the B liquid at 50 ° C., 37.4 parts of 29 mass% aqueous ammonia (C liquid) was added dropwise thereto, followed by stirring for 15 minutes to obtain an aqueous slurry.

(Concentration process)
The aqueous slurry was heated to 101 ° C. and concentration was started with stirring. When the viscosity of the aqueous slurry reached 0.70 Pa · s, the heating was stopped, and the container containing the aqueous slurry was capped so that no more water vaporized. The time it took to concentrate was 2 hours. The specific gravity of the concentrate was 1.56 × 10 3 kg / m 3 .

(Low viscosity process)
The aqueous slurry (concentrated liquid) concentrated with the container kept on the lid was cooled to 70 ° C. and held in this state for 2 hours. The viscosity of the concentrated liquid after holding was 0.40 Pa · s.

(Re-concentration process)
After removing the lid of the container, the concentrate was heated to 101 ° C. and reconcentration was started while stirring. During the concentration, the temperature was kept at 101 ° C., and the heating was stopped when the viscosity of the concentrated liquid reached 0.70 Pa · s, and the container containing the concentrated liquid was capped so that no more water was volatilized. The time required for reconcentration was 0.5 hours. The specific gravity of the concentrate was 1.64 × 10 3 kg / m 3 .

(Drying process)
The concentrated liquid was dried with a drum dryer at 120 ° C. to obtain a dry powder. The moisture content of the dry powder was 1.0% by mass. The degree of compression is shown in Table 1.

(Molding process)
After adding 2 parts of graphite to 100 parts of the dry powder, it was molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm with a tableting machine. The dry powder had good fluidity and good moldability.

(Baking process)
The obtained molded product was calcined at 380 ° C. for 6 hours under air flow to obtain a catalyst for producing methacrylic acid. The resulting catalyst composition (however, oxygen was omitted; the same applies hereinafter) was Mo 12 P 1.5 Cu 0.15 V 0.6 Cs 0.9 As 0.7 Fe 0.02 .

(Production of methacrylic acid)
A catalyst for producing methacrylic acid is packed in a reaction tube, and a mixed gas of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor, and 55% by volume of nitrogen is subjected to a reaction temperature of 290 ° C. and a contact time of 3.6 at normal pressure. The reaction was conducted in seconds. The reaction results are shown in Table 1.

[Comparative Example 1]
A catalyst for methacrylic acid production was produced in the same manner as in Example 1 except that the viscosity reduction step and the reconcentration step were not conducted, and methacrylic acid was produced. The results are shown in Table 1. The dry powder had poor fluidity and poor moldability. Moreover, the yield of methacrylic acid was also poor compared with Example 1.

[Comparative Example 2]
Except that the mixing temperature of the liquid B and the liquid C was 85 ° C. and the fluidity of the dried powder was improved thereby, the viscosity reduction step and the reconcentration step were not performed. Thus, a catalyst for producing methacrylic acid was produced, and methacrylic acid was produced. The results are shown in Table 1. The time for concentration was 2.5 hours. Although the dry powder had good fluidity and good moldability, the yield of methacrylic acid was worse than that of Example 1.

The catalyst for producing methacrylic acid of the present invention is excellent in fluidity when powdered and has high catalytic performance, and is useful for producing methacrylic acid.

Claims (3)

  1. A method for producing a catalyst containing phosphorus and molybdenum, which is used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
    Concentrating a solution or slurry containing phosphorus and molybdenum to obtain a concentrate;
    Reducing the viscosity of the concentrate;
    Re-concentrating the concentrated liquid having a reduced viscosity;
    And a step of drying the re-concentrated concentrate.
  2.   A catalyst for producing methacrylic acid produced by the method for producing a catalyst for producing methacrylic acid according to claim 1.
  3. A method for producing methacrylic acid, which comprises producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen using the catalyst for producing methacrylic acid produced by the method for producing a catalyst for producing methacrylic acid according to claim 1. .
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007229561A (en) * 2006-02-28 2007-09-13 Mitsubishi Rayon Co Ltd Molybdenum oxide, catalyst, method for manufacturing the catalyst and method for producing (meth)acrylic acid or the like
JP2010142687A (en) * 2008-12-16 2010-07-01 Mitsubishi Rayon Co Ltd Method of manufacturing catalyst for synthesizing unsaturated carboxylic acid

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