JP2005058909A - Production method for catalyst for synthesizing methacrylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst synthesizing methacrylic acid by the gas-phase catalytic oxidation of mathacrolein with molecular oxygen in a high yield, to provide a method for producing the catalyst and to provide a method for producing methacrylic acid by using the catalyst. <P>SOLUTION: The production method for the catalyst for synthesizing methacrylic acid includes a process of mixing a composition (1) represented by the formula (1): Mo<SB>a</SB>P<SB>b</SB>X<SB>c</SB>Y<SB>d</SB>O<SB>e</SB>(1) and/or an aqueous slurry A containing the precursor of the composition with a composition B containing a composite oxide (2) represented by the formula (2): Mo<SB>f</SB>D<SB>g</SB>E<SB>h</SB>O<SB>i</SB>(2). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a catalyst for synthesizing methacrylic acid, a catalyst for synthesizing methacrylic acid, and a method for producing methacrylic acid in which methacrolein is vapor-phase contact oxidized with molecular oxygen.

  As a catalyst for synthesizing methacrylic acid by gas phase catalytic oxidation of methacrolein, it is widely known that a heteropolyacid catalyst containing at least molybdenum and phosphorus as essential components is effective. However, the conventional heteropolyacid catalyst has a problem that the yield of methacrylic acid is not sufficient.

Thus, in recent years, proposals have been made on catalysts containing heteropolyacids and composite oxides containing molybdenum and phosphorus as essential components for catalysts that synthesize methacrylic acid by gas phase catalytic oxidation of methacrolein. For example, Patent Document 1 discloses a process for producing a catalyst in which a heteropolyacid containing solid molybdenum, phosphorus and arsenic and a composite oxide composed of solid copper molybdate and / or silver molybdate are mixed. Document 2 discloses a method for producing a catalyst in which a heteropolyacid powder containing molybdenum and phosphorus and a powder of a multicomponent composite oxide containing molybdenum and at least one element selected from iron, cobalt, nickel and the like are mixed. Has been described.
JP 59-210042 A JP-A-7-267635

  However, the yield of the catalyst for synthesizing methacrylic acid produced by the conventional method is not always sufficient, and the present situation is that further improvement is desired as an industrial catalyst.

  An object of the present invention is to provide a high yield catalyst for synthesizing methacrylic acid by gas phase catalytic oxidation of methacrolein with molecular oxygen, a method for producing the catalyst, and a method for producing methacrylic acid using the catalyst. To do.

  As a result of intensive studies to solve the above problems, the present inventors have found that the catalyst used in the synthesis of methacrylic acid by gas phase catalytic oxidation with molecular oxygen has high catalytic activity and methacrylic acid selectivity. It came to discover the manufacturing method of the catalyst which has this.

  That is, the present invention relates to an aqueous slurry A containing the composition (1) represented by the formula (1) and / or a precursor thereof, and a composition B containing the composite oxide (2) represented by the formula (2). It is a manufacturing method of the catalyst for methacrylic acid synthesis including the process of mixing.

_{Mo a P b X c Y d} O e (1)
(In the formula (1), Mo, P and O represent molybdenum, phosphorus and oxygen, respectively, X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, and Y represents iron, cobalt , Nickel, copper, zinc, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, tungsten, manganese, silver, boron, silicon, aluminum, gallium, germanium, tin, lead, arsenic, antimony, bismuth, niobium, tantalum Represents at least one element selected from the group consisting of zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, where a, b, c, d and e represent the atomic ratio of each element, and a = 12: 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 6, 0 ≦ d ≦ 3 Ri, e is an atomic ratio of oxygen required to satisfy the atomic ratio of the respective components.)

_{Mo f D g E h O i} (2)
(In the formula (2), Mo and O represent molybdenum and oxygen, respectively, and D represents a group consisting of iron, cobalt, nickel, copper, chromium, zinc, ruthenium, rhodium, silver, cadmium, tellurium, rhenium, cerium and lanthanum. E represents at least one element selected from the group consisting of potassium, rubidium, cesium, thallium, magnesium, calcium, strontium, barium, titanium, vanadium, manganese, zirconium, niobium, tantalum, tungsten, aluminum, silicon, phosphorus, gallium , Represents at least one element selected from the group consisting of germanium, arsenic, tin, antimony and bismuth, where f, g, h and i represent the atomic ratio of each element, and when f = 1, 0. 1 ≦ g ≦ 10, 0 ≦ h ≦ 5, i represents each of the above components An atomic ratio of oxygen required to satisfy the atomic ratio.)

  In this invention, it is preferable that the said aqueous slurry A contains 0.1-100 mass parts ammonia and / or ammonium ion with respect to 100 mass parts of molybdenum atoms contained in this slurry. Further, the amount of the composite oxide (2) contained in the composition B is preferably 1 to 100 parts by mass with respect to 100 parts by mass of molybdenum atoms contained in the aqueous slurry A.

  A second aspect of the present invention is a catalyst for synthesizing methacrylic acid produced by the above-described method of the present invention, and a composition represented by the formula (1) (1) and a composite represented by the formula (2). A catalyst for synthesizing methacrylic acid containing an oxide (2).

  According to a third aspect of the present invention, there is provided a method for producing methacrylic acid, which comprises using the catalyst for synthesizing methacrylic acid according to the second aspect of the present invention in a method for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen.

  The catalyst obtained by the method of the present invention has an excellent effect of producing methacrylic acid in a high yield in the gas phase catalytic oxidation reaction of methacrolein. This catalyst makes it possible to produce methacrylic acid efficiently, and its industrial value is extremely high.

  In the present invention, the aqueous slurry A contains the composition (1) represented by the formula (1) and / or a precursor thereof.

  In the formula (1), Mo, P and O represent molybdenum, phosphorus and oxygen, respectively, X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, Y represents iron, cobalt, Nickel, copper, zinc, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, tungsten, manganese, silver, boron, silicon, aluminum, gallium, germanium, tin, lead, arsenic, antimony, bismuth, niobium, tantalum, It represents at least one element selected from the group consisting of zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium.

  In the formula (1), a, b, c, d and e represent the atomic ratio of each element. When a = 12, 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 6, 0 ≦ d ≦ 3, and e represents the atomic ratio of oxygen necessary for satisfying the atomic ratio of the respective components.

  Although the preparation method of the aqueous slurry A is not specifically limited, For example, it can prepare by a coprecipitation method etc. Alternatively, a solid obtained by evaporation to dryness, oxide mixing, or the like may be prepared by dispersing in water.

  The raw materials of elements such as molybdenum, phosphorus, X, and Y (hereinafter also referred to as catalyst raw materials) used for preparing the aqueous slurry A are not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides of each element , Halides, oxygen acids and the like can be used in appropriate combinations. For example, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, and the like can be used as the molybdenum source, and phosphoric acid, phosphorus pentoxide, ammonium phosphate, and the like can be used as the phosphorus source.

  In the present invention, the total mass of ammonia and ammonium ions (hereinafter collectively referred to as ammonium roots) contained in the aqueous slurry A is 0.1 to 100 parts by mass of molybdenum atoms contained in the slurry. 100 mass parts is preferable, 1-50 mass parts is more preferable, and 5-30 mass parts is especially preferable. The presence of ammonium roots in the aqueous slurry A can improve the performance of the catalyst obtained after mixing the composition B. The ammonium root is derived from a compound containing an ammonium root such as ammonia, ammonium nitrate, or ammonium carbonate (hereinafter also referred to as an ammonium root raw material) that can be added at the time of slurry preparation even if it is derived from the catalyst raw material. It does not matter.

The composition (1) preferably has a composition represented by the following formula (1 ′).
_{Mo a P b X c Y '} d' Cu i V j O e (1 ')
(Wherein Mo, P, Cu, V and O represent molybdenum, phosphorus, copper, vanadium and oxygen, respectively, X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium; Preferred are potassium and cesium Y 'is iron, cobalt, nickel, zinc, magnesium, calcium, strontium, barium, titanium, chromium, tungsten, manganese, silver, boron, silicon, aluminum, gallium, germanium, tin, lead Represents at least one element selected from the group consisting of arsenic, antimony, bismuth, niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, preferably iron, antimony, arsenic, germanium, cerium A, b, c, d ′, i, j and e represent the atomic ratio of each element, and when a = 12, b is 0.1 ≦ b ≦ 3, preferably 0.5 ≦ b ≦ 3. .01 ≦ c ≦ 6, preferably 0.1 ≦ c ≦ 4 Similarly, d ′ is 0 ≦ d ′ ≦ 2.98, preferably 0 ≦ d ′ ≦ 2.5. 0.01 ≦ i ≦ 2.99, preferably 0.01 ≦ i ≦ 2.Similarly, j is 0.01 ≦ j ≦ 2.99, preferably 0.01 ≦ j ≦ 2. (This is the atomic ratio of oxygen necessary to satisfy the atomic ratio of the above components, where d ′ + i + j is 0.02 ≦ (d ′ + i + j) ≦ 3.)

  The aqueous slurry A may contain an ammonium root raw material in addition to the composition (1) and / or its precursor. Further, a small amount of impurities derived from catalyst raw materials, ammonium root raw materials and the like may be contained.

  The average particle size of the particles of the composition (1) and / or its precursor contained in the aqueous slurry A is preferably in the range of 0.1 to 100 μm.

  In the present invention, the precursor of the composition (1) is in the state of the previous stage having an active site structure showing the selective oxidation ability of methacrolein in the production process of the composition (1), This includes dry matter that has not been fired.

  In the present invention, the composition B includes the composite oxide (2) represented by the formula (2).

  In formula (2), Mo and O represent molybdenum and oxygen, respectively. D is at least one element selected from the group consisting of iron, cobalt, nickel, copper, chromium, zinc, ruthenium, rhodium, silver, cadmium, tellurium, rhenium, cerium and lanthanum, preferably iron, cobalt, Nickel and copper. E is from potassium, rubidium, cesium, thallium, magnesium, calcium, strontium, barium, titanium, vanadium, manganese, zirconium, niobium, tantalum, tungsten, aluminum, silicon, phosphorus, gallium, germanium, arsenic, tin, antimony and bismuth And at least one element selected from the group consisting of potassium, rubidium, cesium, thallium, vanadium, zirconium, and niobium.

  In the formula (2), f, g, h and i represent atomic ratios of the respective elements. When f = 1, 0.1 ≦ g ≦ 10, 0 ≦ h ≦ 5, and i is It represents the atomic ratio of oxygen necessary to satisfy the atomic ratio of the components. When f = 1, g is preferably 0.1 ≦ g ≦ 5, and h is preferably 0 ≦ h ≦ 3.

  The raw materials used for the preparation of the composite oxide (2) are not particularly limited, and nitrates, carbonates, acetates, sulfates, ammonium salts, oxides, halides, oxygen acids, etc. of various elements may be used in appropriate combinations. Can do. For example, as a raw material of molybdenum, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, or the like can be used.

  The method for preparing the composite oxide (2) is not particularly limited. The composite oxide (2) is, for example, fired after dissolving or suspending a molybdenum-containing compound and a D element and / or E element-containing compound in water and mixing them in a wet manner, or mixing powders in a dry manner. Can be manufactured. Specifically, each element-containing compound is wet-mixed, then evaporated to dryness or filtered, and fired. The oxide of each element is mechanically mixed at a predetermined ratio using a crusher or the like. Thereafter, a method of firing and the like can be exemplified. Among these, a method of mixing each element-containing compound in a wet manner is preferable because a composite oxide having a small average particle size and a large surface area can be prepared.

The firing conditions vary depending on the raw materials, composition, and preparation conditions to be used, but cannot be generally stated, but are 300 to 800 ° C., preferably 350 to 600, under an oxygen-containing gas flow such as air and / or an inert gas flow. A method of carrying out at 0.5 ° C. for 0.5 hour or longer, preferably 1 to 40 hours is desirable. The structure of the composite oxide after firing can be confirmed by a powder X-ray diffraction pattern. Examples of the structure of such a composite oxide include Fe ₂ (MoO ₄ ) ₃ (JCPDS number: 31-642), CoMoO ₄ (JCPDS number: 21-868), and the like.

  The preparation method of the composition B is not particularly limited. For example, it is prepared by the same method as the preparation of the composite oxide (2) or by supporting the composite oxide (2) on an inert carrier such as silica or alumina. it can.

  The ratio of the composite oxide (2) contained in the composition B is preferably 10 to 100% by mass, and more preferably 50 to 100% by mass from the viewpoint of the activity and selectivity of the produced catalyst.

  Examples other than the composite oxide (2) contained in the composition B include, for example, a single oxide and / or composite oxide of D element and E element, a composite oxide of D element and E element, and a single oxidation of molybdenum. Thing etc. are mentioned. Further, the composite oxide (2) may be supported on an inert carrier such as silica or alumina to form the composition B.

  The composition B is desirably a powder having an average particle size of 0.1 to 100 μm.

  In the present invention, a method of mixing the aqueous slurry A and the composition B is not particularly limited, but a method of charging the composition B into the aqueous slurry A is preferable. In that case, it is preferable to mix as uniformly as possible, since the conversion of methacrolein is high and a catalyst with a high yield of methacrylic acid can be obtained. The reason why a catalyst with high performance can be obtained in this way is not clear, but by mixing uniformly, a mixture having a small average particle size and a uniform particle size can be obtained, and a methacrolein oxidation reaction is carried out in the mixture. It is estimated that the interface between the effective composition (1) and the composite oxide (2) is more uniformly formed.

  In the aqueous slurry A and the composition B, the composite oxide (2) is preferably 1 to 100 parts by mass, more preferably 3 to 50, particularly preferably 5 with respect to 100 parts by mass of molybdenum atoms contained in the aqueous slurry A. It mixes in the ratio which becomes -30 mass parts.

  Usually, the mixture of aqueous slurry A and composition B is dried. Although a drying method is not specifically limited, For example, it can dry using a box-type dryer, a spray dryer, a slurry dryer etc.

  Usually, the obtained dried product is molded. Molding may be performed after firing described below, but is preferably performed before firing. Although a shaping | molding method is not specifically limited, For example, methods, such as tableting shaping | molding, extrusion molding, granulation, a support | carrier, are mentioned. Examples of the carrier in the case of support molding include inert carriers such as silica, alumina, silica / alumina, and silicon carbide.

  In the molding, for the purpose of controlling the specific surface area, pore volume and pore distribution of the molded product or increasing the mechanical strength, for example, inorganic salts such as barium sulfate and ammonium nitrate, lubricants such as graphite, celluloses, etc. Additives such as organic substances such as starch, polyvinyl alcohol and stearic acid, hydroxide sols such as silica sol and alumina, whiskers, glass fibers and carbon fibers may be added as appropriate.

  When the molded body is fired, the firing may be performed before filling the molded body into the reaction tube or in the reaction tube. The firing conditions vary depending on the raw material of the catalyst to be used, the catalyst composition, the preparation conditions, etc., and cannot generally be said, but usually 300 to 500 ° C., preferably under an oxygen-containing gas flow and / or an inert gas flow such as air. Is performed at 300 to 450 ° C. for 0.5 hour or longer, preferably 1 to 40 hours.

  The methacrylic acid synthesis catalyst of the present invention can be produced by the above method. However, the catalyst of the present invention is not limited to the one produced by the method described above, and the composition (1) represented by the formula (1) and the composite oxide (2) represented by the formula (2). As long as it contains. In the catalyst of the present invention, the amount of the composite oxide (2) is preferably 1 to 100 parts by weight, more preferably 3 to 50, particularly preferably 100 parts by weight of molybdenum atoms contained in the composition (1). 5 to 30 parts by mass.

  Next, a method for producing methacrylic acid by subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen using the methacrylic acid synthesis catalyst of the present invention will be described. The source gas brought into contact with the catalyst contains at least methacrolein and molecular oxygen.

  The concentration of methacrolein in the raw material gas can be varied within a wide range, but is preferably 1 to 20% by volume, particularly preferably 3 to 10% by volume. The methacrolein used for the preparation of the raw material gas may contain a small amount of impurities that do not substantially affect the reaction, such as water and lower saturated aldehydes. May be included.

  The molecular oxygen concentration of the source gas is preferably 0.4 to 4 times, more preferably 0.5 to 3 times that of methacrolein. Although it is industrially advantageous to use air as the molecular oxygen source of the source gas, air enriched with pure oxygen can also be used if necessary.

  The source gas is preferably diluted with an inert gas such as nitrogen or carbon dioxide, water vapor or the like.

  The reaction pressure for gas phase catalytic oxidation is from atmospheric pressure to several atmospheres. The reaction temperature is usually 200 to 450 ° C., preferably 250 to 400 ° C. The contact time between the source gas and the catalyst is usually 1.5 to 15 seconds, preferably 2 to 7 seconds.

Hereinafter, the present invention will be described with reference to examples and comparative examples. However, “parts” in Examples and Comparative Examples means parts by mass. Reaction test analysis was performed by gas chromatography. Further, the conversion rate of the raw material methacrolein, the selectivity of the produced methacrylic acid and the yield are defined as follows.
Conversion rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Methacrylic acid single stream yield (%) = (C / A) × 100
Here, A is the number of moles of methacrolein supplied, B is the number of moles of reacted methacrolein, and C is the number of moles of methacrylic acid produced.

[Example 1]
(Preparation of aqueous slurry A)
A solution in which 100 parts of ammonium paramolybdate is dissolved in 200 parts of pure water and 2.8 parts of ammonium metavanadate and 8.2 parts of 85 wt% phosphoric acid are dissolved in 30 parts of pure water, 1.1 parts of copper nitrate A solution prepared by dissolving 30 parts of pure water and a solution of 3.8 parts of iron nitrate in 10 parts of pure water are sequentially added, heated to 90 ° C. with stirring, and maintained for 5 hours while maintaining the liquid temperature at 90 ° C. After heating and stirring, a solution obtained by dissolving 6.4 parts of cesium nitrate in 100 parts of pure water was added thereto to obtain an aqueous slurry A containing the precursor of the composition (1). The particle size distribution of the slurry thus prepared was measured using a laser diffraction particle size distribution device (PRO-7000S manufactured by Seishin Enterprise Co., Ltd.), and the average particle size was 24.7 μm. Moreover, when the ammonia amount contained in the aqueous slurry A was determined by the Kjeldahl method, it was 15.8 parts with respect to 100 parts by mass of molybdenum atoms.

(Preparation of composition B)
A solution prepared by dissolving 100 parts of ammonium paramolybdate in 300 parts of pure water, 164.8 parts of cobalt nitrate in 200 parts of pure water, and a solution of 11.0 parts of cesium nitrate in 30 parts of pure water are heated and stirred. The mixture was heated to 90 ° C. with stirring, stirred for 2 hours while maintaining the liquid temperature at 90 ° C., and then the mixture was evaporated to dryness while stirring with heating. The obtained solid was dried at 130 ° C. and pulverized, and the obtained powder was calcined at 500 ° C. for 3 hours. The composition excluding oxygen atoms in the composition B thus obtained was Mo ₁ Co ₁ Cs _0.1 . Composition B was confirmed by powder X-ray structural analysis to have a complex oxide structure represented by CoMoO ₄ and the remainder being mainly Cs ₂ O. Moreover, the average particle diameter of the composition B containing 88.6% by mass of the composite oxide (2) was 4.2 μm.

(Mixing process)
14.1 parts of the composition B containing 88.6% by mass of the composite oxide (2) produced by the above method was added to the aqueous slurry A containing the composition (1) precursor produced by the above method. The amount of the composite oxide (2) contained in the composition B at this time was 23 parts relative to 100 parts of molybdenum atoms contained in the aqueous slurry A.

  The obtained liquid was evaporated to dryness while stirring with heating, and then dried at 130 ° C. for 16 hours, and the obtained dried product was pulverized. 3 parts of graphite was added to 100 parts of the obtained powder, and then formed into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm by a tableting machine.

The obtained molded product was calcined at 380 ° C. for 5 hours under air flow to obtain a catalyst. The composition excluding oxygen atoms of the composition (1) contained in the catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , and the composition excluding oxygen atoms of the composite oxide (2). Was Mo ₁ Co ₁ . This catalyst contained 23 parts of complex oxide (2) with respect to 100 parts of molybdenum atoms in composition (1).

  This catalyst is filled into a fixed bed tube type reaction tube, and a mixed gas of 5% methacrolein, 10% oxygen, 30% water vapor, 55% nitrogen (volume%) is passed at a reaction temperature of 290 ° C. and a contact time of 3.6 seconds. It was. The reaction results are shown in Table 1.

[Example 2]
In Example 1, a catalyst was produced in the same manner as in Example 1 except that the amount of the composition B was changed from 14.1 parts to 28.8 parts, and methacrolein was oxidized. The amount of the composite oxide (2) contained in the composition B at this time was 47 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A. The composition excluding oxygen atoms of the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , oxygen atoms of the composite oxide (2) The composition excluding was Mo ₁ Co ₁ . This catalyst contained 47 parts of complex oxide (2) with respect to 100 parts of molybdenum atoms in composition (1). The reaction results are shown in Table 1.

[Example 3]
In Example 1, a catalyst was produced in the same manner as in Example 1 except that the amount of the composition B was changed from 14.1 parts to 2.5 parts, and an oxidation reaction of methacrolein was performed. The amount of the composite oxide (2) contained in the composition B at this time was 4 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A. The composition excluding oxygen atoms of the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , oxygen atoms of the composite oxide (2) The composition excluding was Mo ₁ Co ₁ . This catalyst contained 4 parts of the composite oxide (2) with respect to 100 parts of molybdenum atoms in the composition (1). The reaction results are shown in Table 1.

[Example 4]
In Example 1, a catalyst was produced in the same manner as in Example 1 except that the amount of the composition B was changed from 14.1 parts to 0.43 parts, and an oxidation reaction of methacrolein was performed. The amount of the composite oxide (2) contained in the composition B at this time was 0.7 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A. The composition excluding oxygen atoms of the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , oxygen atoms of the composite oxide (2) The composition excluding was Mo ₁ Co ₁ . This catalyst contained 0.7 part of the composite oxide (2) with respect to 100 parts of molybdenum atoms in the composition (1). The reaction results are shown in Table 1.

[Example 5]
(Preparation of aqueous slurry A ′)
In Example 1, an aqueous slurry A ′ containing the composition (1 ′) precursor was added in the same manner as in Example 1 except that 97.1 parts of 29% by mass ammonia water was added during preparation of the composition (1) precursor slurry. Prepared. The aqueous slurry A ′ contained 31.1 parts of ammonia with respect to 100 parts by mass of molybdenum atoms. The average particle size of the aqueous slurry A ′ was 28.6 μm.

(Mixing process)
In Example 1, a catalyst was produced in the same manner as in Example 1 except that the aqueous slurry A was changed to the aqueous slurry A ′ containing the composition (1 ′) precursor, and methacrolein was oxidized. The amount of the composite oxide (2) contained in the composition B at this time was 23 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A ′. The composition excluding oxygen atoms of the composition (1 ′) contained in the obtained catalyst was Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , oxygen of the composite oxide (2). The composition excluding atoms was Mo ₁ Co ₁ . This catalyst contained 23 parts of the composite oxide (2) with respect to 100 parts of molybdenum atoms in the composition (1 ′). The reaction results are shown in Table 1.

[Example 6]
(Preparation of aqueous slurry A ″)
The aqueous slurry A containing the composition (1) precursor obtained in Example 1 was evaporated to dryness while heating and stirring. The obtained solid was dried at 130 ° C. for 16 hours, pulverized, and calcined at 380 ° C. for 5 hours to obtain a composition (1 ″). The total amount of the composition (1 ″) thus obtained was put into 200 parts of pure water to obtain an aqueous slurry A ″. The aqueous slurry A ″ contained 0.04 part of ammonia with respect to 100 parts by weight of molybdenum. The average particle size of the aqueous slurry A ″ was 22.5 μm.

(Mixing process)
In Example 1, except that the aqueous slurry A was changed to the aqueous slurry A ″ containing the composition (1 ″), a catalyst was produced in the same manner as in Example 1, and an oxidation reaction of methacrolein was performed. The amount of the composite oxide (2) contained in the composition B at this time was 23 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A ″. The composition excluding oxygen atoms of the composition (1 ″) contained in the obtained catalyst was Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , composite oxide (2). The composition excluding oxygen atoms was Mo ₁ Co ₁ . This catalyst contained 23 parts of complex oxide (2) with respect to 100 parts of molybdenum atoms in the composition (1 ″). The reaction results are shown in Table 1.

[Example 7]
(Preparation of composition B ′)
A solution prepared by dissolving 100 parts of ammonium paramolybdate in 300 parts of pure water and 164.7 parts of nickel nitrate in 200 parts of pure water was added with heating and stirring, and this was heated to 90 ° C. while stirring. The mixture was stirred for 2 hours while maintaining at 90 ° C., and then the mixture was evaporated to dryness with heating and stirring. The obtained solid was dried at 130 ° C. and pulverized, and the obtained powder was calcined at 500 ° C. for 3 hours. The composition excluding oxygen atoms of the composition B ′ thus obtained was Mo ₁ Ni ₁ . The compositions B 'was confirmed to have a composite oxide structure represented by NiMoO ₄ from the powder X-ray structure analysis. Further, the average particle size of the composition B ′ containing 100% by mass of the composite oxide (2 ′) was 3.7 μm.

(Mixing process)
A catalyst was produced in the same manner as in Example 1 except that the composition B was changed to the composition B ′ composed only of the composite oxide (2 ′) in Example 1, and an oxidation reaction of methacrolein was performed. The amount of the composite oxide (2 ′) contained in the composition B ′ at this time was 18 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A. The composition excluding oxygen atoms of the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , oxygen of the composite oxide (2 ′). The composition excluding atoms was Mo ₁ Ni ₁ . This catalyst contained 18 parts of the composite oxide (2 ′) with respect to 100 parts of molybdenum atoms in the composition (1). The reaction results are shown in Table 1.

[Example 8]
(Preparation of composition B '')
A solution prepared by dissolving 100 parts of ammonium paramolybdate in 300 parts of pure water and 228.8 parts of iron nitrate in 200 parts of pure water was added with heating and stirring, and this was heated to 90 ° C. while stirring. The mixture was stirred for 2 hours while maintaining at 90 ° C., and then the mixture was evaporated to dryness with heating and stirring. The obtained solid was dried at 130 ° C. and pulverized, and the obtained powder was calcined at 500 ° C. for 3 hours. The composition excluding oxygen atoms of the composition B ″ thus obtained was Mo ₁ Fe ₁ . Composition B '' was confirmed by powder X-ray structural analysis to have a complex oxide structure represented by Fe ₂ (MoO ₄ ) ₃ with the remainder being mainly Fe ₂ O ₃ . Further, the average particle size of the composition B ″ containing 88% by mass of the composite oxide (2 ″) was 4.5 μm.

(Mixing process)
A catalyst was produced in the same manner as in Example 1 except that the composition B was changed to the composition B ″ containing 88% by mass of the composite oxide (2 ″) in Example 1, and the oxidation reaction of methacrolein was performed. went. The amount of the composite oxide (2 ″) contained in the composition B ″ at this time was 14 parts with respect to 100 parts of molybdenum atoms contained in the aqueous slurry A. The composition excluding oxygen atoms in the composition (1) contained in the obtained catalyst was Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , composite oxide (2 ″). The composition excluding oxygen atoms was Mo ₁ Fe _0.67 . This catalyst contained 14 parts of complex oxide (2 ″) per 100 parts of molybdenum atoms in composition (1). The reaction results are shown in Table 1.

[Comparative Example 1]
In Example 1, a catalyst was produced in the same manner as in Example 1 except that only the aqueous slurry A was used without using the composition B, and an oxidation reaction of methacrolein was performed. The composition excluding oxygen atoms in the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ and is represented by the above formula (2). The composite oxide (2) to be produced was not contained. The reaction results are shown in Table 1.

[Comparative Example 2]
The aqueous slurry A containing the composition (1) precursor obtained in Example 1 was evaporated to dryness while heating and stirring. The obtained solid was dried at 130 ° C. for 16 hours and then pulverized to obtain a dried product containing the composition (1) precursor. The obtained dried product contained 12.4 parts of ammonia with respect to 100 parts by mass of molybdenum atoms. After the dried product was dispersed in pure water, the particle size distribution was measured. The average particle size was 24.7 μm.

After dry-mixing the total amount of the dry matter containing the composition (1) produced by the above method and 12.5 parts of the composition B consisting only of the composite oxide (2) using a cracker, the same as in Example 1 Then, the catalyst was produced by molding and firing, and methacrolein oxidation reaction was performed. The composition excluding oxygen atoms in the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ , and the composition of the composite oxide (2) The composition excluding oxygen atoms was Mo ₁ Co ₁ . This catalyst contained 23 parts of complex oxide (2) with respect to 100 parts of molybdenum atoms in composition (1). The reaction results are shown in Table 1.

[Comparative Example 3]
In the production process of the composition B in Example 1, the powder obtained after drying was not fired at 500 ° C. for 3 hours to obtain a composition B ′ ″. A catalyst was produced in the same manner as in Example 1 except that 12.5 parts of the composition B ′ ″ thus obtained was added to the aqueous slurry A containing the composition (1) precursor, and oxidation of methacrolein was performed. Reaction was performed. At this time, the composite oxide (2 ′ ″) was not contained in the composition B ′ ″. The composition excluding oxygen atoms in the composition (1) contained in the obtained catalyst is Mo ₁₂ P _1.5 V _0.5 Cu _0.1 Fe _0.2 Cs ₁ and is represented by the above formula (2). The composite oxide (2) to be produced was not contained. The reaction results are shown in Table 1.

[Example 9]
(Preparation of aqueous slurry A ''')
To 400 parts of pure water, 100 parts of molybdenum trioxide, 7.3 parts of 85% by weight phosphoric acid, 4.7 parts of vanadium pentoxide, 0.9 parts of copper oxide and 0.2 parts of iron oxide are added and refluxed for 5 hours. Stir. After cooling the obtained liquid mixture to 50 degreeC, 37.4 parts of 29 mass% ammonia water was dripped, and it stirred for 15 minutes. Next, a solution obtained by dissolving 9.0 parts of cesium nitrate in 30 parts of pure water was added dropwise and stirred for 15 minutes to obtain an aqueous slurry A ′ ″ containing the composition (1 ′ ″) precursor. The average particle size of the aqueous slurry A ′ ″ was 12.7 μm. The aqueous slurry A ′ ″ contained 16.3 parts of ammonia with respect to 100 parts by mass of molybdenum atoms in the slurry.

(Preparation of composition B ″ ″)
A solution prepared by dissolving 100 parts of ammonium paramolybdate in 300 parts of pure water, 164.7 parts of nickel nitrate in 200 parts of pure water, and 2.48 parts of antimony trioxide are added with heating and stirring. The mixture was heated to 90 ° C. and stirred for 2 hours while maintaining the liquid temperature at 90 ° C., and then the mixture was evaporated to dryness while heating and stirring. The obtained solid was dried at 130 ° C. and pulverized, and the obtained powder was calcined at 500 ° C. for 3 hours. The composition excluding oxygen atoms of the composition B ″ ″ thus obtained was Mo ₁ Ni ₁ Sb _0.03 . In addition, it was confirmed that the composition B ″ ″ had a composite oxide structure represented by NiMoO ₄ from the powder X-ray structural analysis, and the remainder was Sb ₂ O ₅ . In addition, the average particle size of the composition B ″ ″ containing 95.7% by mass of the composite oxide (2 ″ ″) was 4.1 μm.

(Mixing process)
In Example 1, the aqueous slurry A was changed to an aqueous slurry A ′ ″ containing the composition (1 ′ ″) precursor, and 14.1 parts of composition B was changed to 12.5 parts of composition B ″ ″. A catalyst was produced in the same manner as in Example 1 except that the mixing was carried out and the methacrolein was oxidized. The composition excluding oxygen atoms in the composition (1 ′ ″) contained in the obtained catalyst is Mo ₁₂ P _1.1 V _0.9 Cu _0.2 Fe _0.05 Cs _0.8 , and is a composite oxidation The composition excluding oxygen atoms of the product (2 ″ ″) was Mo ₁ Ni ₁ . This catalyst contained 18 parts of complex oxide (2 ″ ″) per 100 parts of molybdenum atoms in the composition (1 ″ ′). The reaction results are shown in Table 1.

[Comparative Example 4]
In Example 9, a catalyst was produced in the same manner as in Example 9 except that only the aqueous slurry A ′ ″ was used without using the composition B ″ ″, and an oxidation reaction of methacrolein was performed. The composition excluding oxygen atoms in the composition (1 ′ ″) contained in the obtained catalyst is Mo ₁₂ P _1.1 V _0.9 Cu _0.2 Fe _0.05 Cs _0.8 , The composite oxide (2) represented by (2) was not included. The reaction results are shown in Table 1.

Claims (7)

A step of mixing the aqueous slurry A containing the composition (1) represented by the formula (1) and / or its precursor and the composition B containing the composite oxide (2) represented by the formula (2). A process for producing a catalyst for synthesizing methacrylic acid.
_{Mo a P b X c Y d} O e (1)
(In the formula (1), Mo, P and O represent molybdenum, phosphorus and oxygen, respectively, X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, and Y represents iron, cobalt , Nickel, copper, zinc, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, tungsten, manganese, silver, boron, silicon, aluminum, gallium, germanium, tin, lead, arsenic, antimony, bismuth, niobium, tantalum Represents at least one element selected from the group consisting of zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium, where a, b, c, d and e represent the atomic ratio of each element, and a = 12: 0.1 ≦ b ≦ 3, 0.01 ≦ c ≦ 6, 0 ≦ d ≦ 3 Ri, e is an atomic ratio of oxygen required to satisfy the atomic ratio of the respective components.)
_{Mo f D g E h O i} (2)
(In the formula (2), Mo and O represent molybdenum and oxygen, respectively, and D represents a group consisting of iron, cobalt, nickel, copper, chromium, zinc, ruthenium, rhodium, silver, cadmium, tellurium, rhenium, cerium and lanthanum. E represents at least one element selected from the group consisting of potassium, rubidium, cesium, thallium, magnesium, calcium, strontium, barium, titanium, vanadium, manganese, zirconium, niobium, tantalum, tungsten, aluminum, silicon, phosphorus, gallium , Represents at least one element selected from the group consisting of germanium, arsenic, tin, antimony and bismuth, where f, g, h and i represent the atomic ratio of each element, and when f = 1, 0. 1 ≦ g ≦ 10, 0 ≦ h ≦ 5, i represents each of the above components An atomic ratio of oxygen required to satisfy the atomic ratio.)   The catalyst for synthesizing methacrylic acid according to claim 1, wherein the total mass of ammonia and ammonium ions contained in the aqueous slurry A is 0.1 to 100 parts by mass with respect to 100 parts by mass of molybdenum atoms contained in the aqueous slurry A. Production method.   The methacryl of Claim 1 or 2 whose mass of the said complex oxide (2) contained in the said composition B is 1-100 mass parts with respect to 100 mass parts of molybdenum atoms contained in the said aqueous slurry A. A method for producing a catalyst for acid synthesis.   A catalyst for synthesizing methacrylic acid produced by the method according to any one of claims 1 to 3.   A catalyst for synthesizing methacrylic acid comprising the composition (1) represented by the formula (1) and the composite oxide (2) represented by the formula (2).   The catalyst for synthesizing methacrylic acid according to claim 5, wherein the composite oxide (2) represented by the formula (2) is 1 to 100 parts by mass with respect to 100 parts by mass of molybdenum atoms contained in the composition (1). . A method for producing methacrylic acid, comprising using the catalyst for synthesizing methacrylic acid according to any one of claims 4 to 6 in a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen.