JP2019195807A - Method of producing catalyst for production of methacrylic acid, method of producing methacrylic acid and method of producing methacrylic acid ester - Google Patents

Abstract

To provide a catalyst for production of methacrylic acid, having high methacrylic acid yield.SOLUTION: A method of producing a catalyst for production of methacrylic acid is provided that includes: a step (1) of preparing a catalyst raw material liquid A including Mo, P and V; a step (2) of preparing a catalyst raw material liquid B including a cation raw material; and a step (3) of preparing a liquid including heteropoly acid having a keggin type structure or a salt thereof by adding one of the catalyst raw material liquid A and the catalyst raw material liquid B to the other and mixing them, wherein the formulae (i) and (ii) are satisfied in the step (3). 3.0≤T/(√V)≤13.0 (i) 0.01≤u1≤1.0 (ii), in the formulae (i) and (ii), V represents volume of the catalyst raw material liquid A [m], T represents the number of addition ports for adding the other liquid, u1 represents volume flow rate of the other liquid to be added [L/min.], and u1 represents average when T is 2 or more.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a catalyst for producing methacrylic acid, a method for producing methacrylic acid, and a method for producing a methacrylic ester.

  As a catalyst for producing methacrylic acid used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen, a heteropolyacid catalyst containing molybdenum and phosphorus is known. As such heteropolyacid catalysts, there are proton-type heteropolyacids in which the counter cation is a proton, and heteropolyacid salts in which a part of the proton is substituted with a cation other than the proton. As the heteropolyacid salt, an alkali metal salt whose cation is an alkali metal ion and an ammonium salt whose cation is an ammonium ion are known (hereinafter, the proton-type heteropolyacid is also simply referred to as “heteropolyacid”, (At least one selected from acids and heteropolyacid salts is also simply referred to as “heteropolyacid (salt)”.)

  As a method for producing a methacrylic acid production catalyst, for example, Patent Document 1 discloses a production method of a catalyst for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen, and (i) at least molybdenum. (Iii) preparing a solution or slurry (liquid I) containing phosphorus (P) and vanadium (V); (ii) preparing a solution or slurry (liquid II) containing ammonium root; and (iii) ) Either one of the liquid I or liquid II (PR liquid) is charged into the tank (A tank), and 0.01% of the total area of the liquid surface of the PR liquid charged into the tank A. Adding the other liquid (LA liquid) to a continuous liquid surface area having an area of 10% to prepare an I liquid II liquid mixture, and (iv) a catalyst precursor containing all the catalyst components Drying the solution or slurry containing, Characterized in that it comprises a step of forming, it is disclosed method of manufacturing for producing methacrylic acid catalyst comprising a predetermined atoms at predetermined atomic ratios.

International Publication No. 2005/039760

  However, the catalyst for producing methacrylic acid produced by the method disclosed in Patent Document 1 is not sufficient in yield of methacrylic acid when the catalyst is used for producing methacrylic acid, and further improvement is desired. . An object of the present invention is to provide a catalyst for producing methacrylic acid having a high yield of methacrylic acid.

  The present invention includes the following [1] to [18].

[1] A method for producing a methacrylic acid production catalyst used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(1) preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium;
(2) preparing a catalyst raw material liquid B containing a cation raw material;
(3) The step of adding the other liquid to one of the catalyst raw material liquid A and the catalyst raw material liquid B and mixing to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof. Including
A method for producing a methacrylic acid production catalyst satisfying the following formulas (i) and (ii) in the step (3).

3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u1 ≦ 1.0 (ii)
(In the formulas (i) and (ii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the other liquid, and u1 is the volume flow rate of the other liquid to be added. [L / min.] When T is 2 or more, u1 represents an average value of volume flow rates of the other liquid added from each addition port.

[2] A method for producing a catalyst for producing methacrylic acid used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(1) preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium;
(2) preparing a catalyst raw material liquid B containing a cation raw material;
(3) adding and mixing the catalyst raw material liquid B to the catalyst raw material liquid A to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof, and
A method for producing a methacrylic acid production catalyst satisfying the following formulas (i) and (iii) in the step (3).

3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u2 ≦ 8 (iii)
(In the formulas (i) and (iii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the catalyst raw material liquid B, and u2 is the catalyst raw material liquid B. The flow rate [mol / min] of the cation raw material is shown.When T is 2 or more, u2 represents the average value of the flow rate of the cation raw material of the catalyst raw material liquid B added from each addition port.

  [3] The method for producing a catalyst for producing methacrylic acid according to [1] or [2], wherein T is 2 or more in the formula (i).

  [4] In the step (3), the other liquid is added and mixed in a container satisfying the following formula (iv) containing either the catalyst raw material liquid A or the catalyst raw material liquid B [1] ] The manufacturing method of the catalyst for methacrylic acid manufacture of description.

0.1 ≦ S ³ / W ² ≦ 50 (iv)
(In formula (iv), S represents the surface area [m ² ] of the liquid level of the liquid in the container, and W represents the volume [m ³ ] of the liquid in the container.)

  [5] In the step (3), the catalyst raw material liquid B is added and mixed in a container satisfying the following formula (iv) in which the catalyst raw material liquid A is contained. A method for producing a catalyst.

0.1 ≦ S ³ / W ² ≦ 50 (iv)
(In formula (iv), S represents the surface area [m ² ] of the liquid level of the liquid in the container, and W represents the volume [m ³ ] of the liquid in the container.)

  [6] The method for producing a catalyst for methacrylic acid production according to [4] or [5], wherein, in the step (3), the addition port is disposed above the liquid level of the liquid in the container.

  [7] The method for producing a catalyst for producing methacrylic acid according to [6], which satisfies the following formula (v) in the step (3).

2 ≦ T / S ≦ 100 (v)
(In the formula (v), T has the same meaning as the formula (i), and S has the same meaning as the formula (iv)).

[8] T pieces drawn from the center of the liquid level of the liquid in the container toward the wall surface of the container so as to have a central angle of 360 ° / T in the step (3). When the liquid surface areas divided by the straight lines are Y ₁ to Y _T , _{one of the} addition ports is arranged above each Y _{1 to} Y _T [6] or [7] The manufacturing method of the catalyst for methacrylic acid manufacture as described in any one of.

  [9] In the step (3), the addition port is an upper portion in a circular region drawn by a radius R [m] calculated by the following formula (vi) with the center of the liquid level of the liquid in the container as the center. The manufacturing method of the catalyst for methacrylic acid manufacture in any one of [6] to [8] which does not exist in.

（式（ｖｉ）中、Ｓは前記式（ｉｖ）と同義である。）。

(In the formula (vi), S has the same meaning as the formula (iv)).

  [10] The method for producing a catalyst for methacrylic acid production according to [1], wherein in the step (3), the catalyst raw material liquid B is added and mixed in a container containing the catalyst raw material liquid A.

[11] The total volume of the catalyst raw material liquid A prepared in the step (1) and the catalyst raw material liquid B prepared in the step (2) is 0.2 m ³ or more. [1] to [10] The manufacturing method of the catalyst for methacrylic acid manufacture in any one of.

  [12] The catalyst for methacrylic acid production according to any one of [1] to [11], wherein the cation raw material is at least one selected from the group consisting of a compound containing an alkali metal and a compound containing an ammonium ion. Production method.

  [13] The catalyst for producing methacrylic acid according to any one of [1] to [12], further comprising a step of drying a liquid containing the heteropolyacid having a Keggin structure or a salt thereof to obtain a catalyst precursor. Production method.

  [14] The method for producing a catalyst for methacrylic acid production according to [13], further comprising a step of heat treating the catalyst precursor.

  [15] The method for producing a catalyst for producing methacrylic acid according to any one of [1] to [14], wherein the catalyst for producing methacrylic acid has an elemental composition represented by the following formula (vii).

_{Mo a P b V c Cu d} A e E f G g O h (vii)
(In the formula (vii), Mo, P, V, Cu and O are element symbols indicating molybdenum, phosphorus, vanadium, copper and oxygen, respectively. A is antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, E represents at least one element selected from the group consisting of selenium, silicon, tungsten and boron, where E is iron, zinc, chromium, magnesium, calcium, strontium, tantalum, cobalt, nickel, manganese, barium, titanium, tin, lead And at least one element selected from the group consisting of niobium, indium, sulfur, palladium, gallium, cerium and lanthanum, wherein G is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium A, b, c, d, e f, g and h represent the atomic ratio of each element, and when a = 12, b = 0.5-3, c = 0.01-3, d = 0.01-2, e = 0-3, f = 0-3, g = 0.01-3, and h is the atomic ratio of oxygen necessary to satisfy the valence of each element.

  [16] A method for producing methacrylic acid, wherein methacrolein is vapor-phase contact oxidized with molecular oxygen in the presence of the catalyst for producing methacrylic acid produced by the method according to any one of [1] to [15].

  [17] A methacrylic acid production catalyst is produced by the method according to any one of [1] to [15], and methacrolein is vapor-phase catalytically oxidized with molecular oxygen in the presence of the methacrylic acid production catalyst. Acid production method.

  [18] A method for producing methacrylic acid ester, which comprises esterifying methacrylic acid produced by the method for producing methacrylic acid according to [16] or [17].

  ADVANTAGE OF THE INVENTION According to this invention, the catalyst for methacrylic acid manufacture with a high methacrylic acid yield can be provided.

[Method for producing catalyst for producing methacrylic acid]
The method for producing a catalyst for producing methacrylic acid according to the present invention is a method for producing a catalyst for producing methacrylic acid, which is used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. The first embodiment of the method includes the following steps (1) to (3).
(1) A step of preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium.
(2) A step of preparing a catalyst raw material liquid B containing a cation raw material.
(3) A step of preparing a liquid containing a heteropolyacid having a Keggin structure or a salt thereof by adding and mixing the other liquid to one of the catalyst raw material liquid A and the catalyst raw material liquid B.

  In the step (3), the following formulas (i) and (ii) are satisfied.

3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u1 ≦ 1.0 (ii)
In the formulas (i) and (ii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the other liquid, u1 is the volume flow rate of the other liquid to be added [ L / min]. In addition, when T is 2 or more, u1 shows the average value of the volume flow rate of the other liquid added from each addition port.

In addition, the second embodiment of the method includes the following steps (1) to (3).
(1) A step of preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium.
(2) A step of preparing a catalyst raw material liquid B containing a cation raw material.
(3) A step of adding the catalyst raw material liquid B to the catalyst raw material liquid A and mixing them to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof.

  In the step (3), the following formulas (i) and (iii) are satisfied.

3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u2 ≦ 8 (iii)
In the formulas (i) and (iii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the catalyst raw material liquid B, u2 is a cation of the catalyst raw material liquid B The flow rate [mol / min] of a raw material is shown. When T is 2 or more, u2 represents an average value of the flow rate of the cation raw material of the catalyst raw material liquid B added from each addition port.

  In the first and second embodiments of the method according to the present invention, including the steps (1) to (3) and satisfying the formulas (i) and (ii) in the step (3), Or the catalyst for methacrylic acid production which can manufacture methacrylic acid with a high yield can be manufactured by satisfy | filling said (i) and (iii). Although the detailed mechanism is not necessarily clarified, it is presumed that catalyst particles effective for improving the methacrylic acid yield are likely to be generated.

  The catalyst for producing methacrylic acid produced by the method according to the present invention contains at least molybdenum, phosphorus and vanadium, but can further contain other elements such as copper in addition to these. The catalyst preferably has an elemental composition represented by the following formula (vii) from the viewpoint of producing methacrylic acid with a high yield.

_{Mo a P b V c Cu d} A e E f G g O h (vii)
In formula (vii), Mo, P, V, Cu and O are element symbols indicating molybdenum, phosphorus, vanadium, copper and oxygen, respectively. A represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron. E is at least selected from the group consisting of iron, zinc, chromium, magnesium, calcium, strontium, tantalum, cobalt, nickel, manganese, barium, titanium, tin, lead, niobium, indium, sulfur, palladium, gallium, cerium and lanthanum One element is shown. G represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g, and h represent the atomic ratio of each element. When a = 12, b = 0.5-3, c = 0.01-3, d = 0. 01 to 2, e = 0 to 3, f = 0 to 3, g = 0.01 to 3, and h is an atomic ratio of oxygen necessary to satisfy the valence of each element. The elemental composition is a value calculated by analyzing a component obtained by dissolving the catalyst in aqueous ammonia by ICP emission spectrometry.

(Process (1))
In the step (1), a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium is prepared. For example, the catalyst raw material liquid A can be obtained by dissolving or suspending a raw material compound of a catalyst component containing molybdenum, phosphorus and vanadium in a solvent using a preparation container. When catalyst raw material liquid A contains at least molybdenum, phosphorus, and vanadium, a methacrylic acid production catalyst with a higher methacrylic acid yield can be produced.

  The raw material compound of the catalyst component is not particularly limited, and nitrates, carbonates, acetates, ammonium salts, oxides, halides, oxoacids, oxoacid salts, etc. of the respective constituent elements of the catalyst may be used alone or in combination of two or more. Can be used in combination. Examples of the molybdenum source compound include molybdenum oxide such as molybdenum trioxide, and ammonium molybdate such as ammonium paramolybdate and ammonium dimolybdate. Examples of the phosphorus source compound include phosphoric acid, phosphorus pentoxide, and ammonium phosphate. Examples of the vanadium raw material compound include ammonium metavanadate, vanadium pentoxide, and vanadyl oxalate. Examples of the raw material compound for copper include copper nitrate, copper oxide, copper carbonate, and copper acetate. As the raw material compound of the catalyst component, one kind may be used for each element constituting the catalyst component, or two or more kinds may be used in combination.

  Examples of the solvent include water, ethyl alcohol, acetone and the like. These may use 1 type and may use 2 or more types together. Among these, it is preferable to use water.

  The catalyst raw material liquid A is preferably prepared by adding a raw material compound of a catalyst component to a solvent using a preparation vessel and stirring while heating. The heating temperature is preferably 80 to 130 ° C, and the lower limit is more preferably 90 ° C or higher. The pH of the catalyst raw material liquid A is preferably 3.0 or less, and more preferably 2.5 or less. Examples of the method of setting the pH of the catalyst raw material liquid A to 3.0 or less include a method of using molybdenum trioxide as a molybdenum raw material, or selecting a raw material compound of the catalyst component so as to contain a large amount of nitrate ions. . Although the density | concentration of the raw material compound of the catalyst component in the catalyst raw material liquid A is not specifically limited, For example, it can be 5-90 mass%.

(Process (2))
In the step (2), a catalyst raw material liquid B containing a cation raw material is prepared. For example, the catalyst raw material liquid B can be obtained by dissolving or suspending the cation raw material in a solvent using a preparation container.

  Here, the “cationic raw material” means a compound containing an alkali metal, a compound containing an alkaline earth metal, a compound containing a transition metal, a compound containing a base metal, and a compound containing nitrogen (including ammonia, ammonium ion or alkylammonium ion). Or at least one selected from the group consisting of nitrogen-containing heterocyclic compounds). Examples of the alkali metal include lithium, sodium, potassium, rubidium, and cesium. Examples of the alkaline earth metal include magnesium, calcium, strontium, and barium. Compounds containing alkali metals, compounds containing alkaline earth metals, compounds containing transition metals, compounds containing base metals include alkali metals, alkaline earth metals, transition metal or base metal nitrates, carbonates, bicarbonates, acetic acids Examples thereof include salts, sulfates, ammonium salts, oxides, hydroxides, halides, oxoacids, oxoacid salts and the like. Examples of the compound containing ammonium ions include ammonium bicarbonate, ammonium carbonate, ammonium nitrate, ammonium phosphate, and ammonium vanadate. Examples of the compound containing an alkylammonium ion include halides or hydroxides such as tetramethylammonium, tetraethylammonium, tetran-propylammonium, tetran-butylammonium, and triethylmethylammonium. Examples of the nitrogen-containing heterocyclic compound include pyridine, piperidine, piperazine, pyrimidine, quinoline, isoquinoline, and alkyl derivatives thereof. These may use 1 type and may use 2 or more types together. Among these, the cation raw material is at least one selected from the group consisting of a compound containing an alkali metal and a compound containing an ammonium ion from the viewpoint of obtaining a methacrylic acid production catalyst having a higher methacrylic acid yield. Is preferred.

  Examples of the solvent include water, ethyl alcohol, acetone and the like. These may use 1 type and may use 2 or more types together. Among these, it is preferable to use water.

  In addition, when using several types as a cation raw material, using a plurality of preparation containers, by dissolving or suspending each cation raw material in a solvent, a plurality of catalysts such as catalyst raw material liquids B1, B2,. The raw material liquid B may be prepared. When the catalyst raw material liquid B is added to the catalyst raw material liquid A, the catalyst raw material liquids B1, B2,... May be added to the catalyst raw material liquid A in any order, or may be added simultaneously. In the first embodiment, when the catalyst raw material liquid A is added to the catalyst raw material liquid B, the catalyst raw material liquid A is added to any one of the catalyst raw material liquids B, and the obtained liquid and another catalyst The raw material liquid B may be mixed, or divided into a plurality of catalyst raw material liquids A such as catalyst raw material liquids A1, A2,... And added to the catalyst raw material liquid B, and then the obtained liquids are mixed. May be. Further, the concentration of the cation raw material in the catalyst raw material liquid B is not particularly limited, but may be, for example, 5 to 90% by mass.

Moreover, when preparing catalyst raw material liquid A and B in the said process (1) and (2), when industrial manufacture is considered, from the viewpoint of manufacturing cost, the catalyst raw material liquid A prepared by the said process (1) and The total volume of the catalyst raw material liquid B prepared in the step (2) is preferably 0.2 m ³ or more, more preferably 0.8 m ³ or more, and 1.5 m ³ or more. More preferably. The upper limit of the volume range is not particularly limited, but can be, for example, 5 m ³ or less.

(Process (3))
In the first embodiment, in step (3), the other liquid is added to and mixed with one of the catalyst raw material liquid A and the catalyst raw material liquid B, and the heteropolyacid having a Keggin type structure or a salt thereof A liquid containing is prepared. That is, the catalyst raw material liquid B is added to and mixed with the catalyst raw material liquid A, or the catalyst raw material liquid A is added and mixed with the catalyst raw material liquid B. In the former case, the catalyst raw material liquid B corresponds to “the other liquid”, and in the latter case, the catalyst raw material liquid A corresponds. Hereinafter, the “other liquid” is also referred to as an additive liquid. In the second embodiment, in the step (3), the catalyst raw material liquid B is added to the catalyst raw material liquid A and mixed to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof. In 1st embodiment, it is necessary to satisfy | fill both the conditions of following formula (i) and (ii) in process (3). Moreover, in 2nd embodiment, it is necessary to satisfy | fill both the conditions of following formula (i) and (iii) in process (3).

3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u1 ≦ 1.0 (ii)
0.01 ≦ u2 ≦ 8 (iii)
In the formulas (i), (ii) and (iii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the other liquid (the catalyst raw material liquid B), u1 represents the volume flow rate [L / min] of the other liquid to be added, and u2 represents the flow rate [mol / min] of the cation raw material of the catalyst raw material liquid B. The “addition port” is the other liquid (catalyst raw material liquid B) provided for adding the other liquid (catalyst raw material liquid B) to either one of the catalyst raw material liquid A or the catalyst raw material liquid B (catalyst raw material liquid A). It is an outlet of the catalyst raw material liquid B). When T is 2 or more, each of u1 and u2 is an average of the volume flow rate of the other liquid added from each addition port and the flow rate of the cation raw material of the catalyst raw material liquid B added from each addition port. Indicates the value. In addition, when there are a plurality of additive liquids, each needs to satisfy the above conditions. That is, when there are catalyst raw material liquids B1, B2,... As the additive liquid, all the additions of the respective liquids satisfy both the conditions of formulas (i) and (ii), or the formulas (i) and (iii) Both conditions must be met. In addition, in the first embodiment, when there are catalyst raw material liquids A1, A2,... As addition liquids, it is necessary that all the additions of the liquids satisfy both the conditions of formulas (i) and (ii). is there.

By mixing the catalyst raw material liquid A and the catalyst raw material liquid B, a liquid containing a heteropolyacid (salt) having a Keggin structure is obtained. In the formula (i), T / ( ³ √V) is obtained by dividing the number T of the addition ports by the cube root of the volume V of the catalyst raw material liquid A, and the catalyst raw material liquid A and the catalyst raw material liquid B are This affects the contact state of each liquid during mixing. Therefore, it is speculated that by setting T / ( ³ √V) in the specific range in the formula (i), a heteropolyacid (salt) effective for improving the yield of methacrylic acid among the heteropolyacids (salts) is likely to be generated. Is done. The total amount of heteropolyacid (salt) obtained is related to the amount of the catalyst component contained in the catalyst raw material liquid A. The value of T / ⁽³ √V) satisfies ^{3.0 ≦ T / (3 √V)} ≦ 13.0, the lower limit is preferably 4.0 or more, more preferably 5.0 or more, 6.0 or more Is more preferable. The upper limit is preferably 12.0 or less, more preferably 11.0 or less, and even more preferably 9.0 or less.

  The value of T is preferably 2 or more, more preferably 4 or more, and even more preferably 8 or more, from the viewpoint of obtaining a methacrylic acid production catalyst having a higher methacrylic acid yield. Although the upper limit of the range of the value of T is not specifically limited, For example, it can be 20 or less. Examples of the method of setting the value of T to 2 or more include using a pipe having a plurality of holes and using a multiple nozzle having a plurality of discharge ports. The diameter of the addition port is preferably 0.5 to 30 mm, the lower limit is preferably 1 mm or more, and the upper limit is more preferably 10 mm or less.

  In the above formula (ii), the volume flow rate u1 of the additive liquid affects the contact speed of the two liquids when the catalyst raw material liquid A and the catalyst raw material liquid B are mixed. Therefore, it is presumed that by adding the other liquid to either one of the catalyst raw material liquid A and the catalyst raw material liquid B so as to satisfy the formula (ii), catalyst particles effective for improving the methacrylic acid yield are likely to be generated. The The value of u1 satisfies 0.01 ≦ u1 ≦ 1.0, and the lower limit is preferably 0.05 or more, and more preferably 0.1 or more. The upper limit is preferably 0.5 or less, more preferably 0.4 or less, and even more preferably 0.3 or less.

  In the formula (iii), the flow rate u2 of the cation raw material of the catalyst raw material liquid B to be added affects the contact speed between the two liquids when the catalyst raw material liquid A and the catalyst raw material liquid B are mixed. Therefore, it is speculated that by adding the catalyst raw material liquid B to the catalyst raw material liquid A so as to satisfy the formula (iii), catalyst particles effective for improving the methacrylic acid yield are easily generated. The value of u2 satisfies 0.01 ≦ u2 ≦ 8, and the lower limit is preferably 0.1 or more, and more preferably 0.5 or more. The upper limit is preferably 5 or less, more preferably 4 or less, and still more preferably 2 or less.

  In the first embodiment, in step (3), the other liquid is added and mixed in a container satisfying the following formula (iv) containing either one of the catalyst raw material liquid A and the catalyst raw material liquid B. Is preferred. In the second embodiment, in the step (3), it is preferable to add and mix the catalyst raw material liquid B in a container satisfying the following formula (iv) containing the catalyst raw material liquid A.

0.1 ≦ S ³ / W ² ≦ 50 (iv)
In the formula (iv), S represents the surface area [m ² ] of the liquid level of the liquid in the container, and W represents the volume [m ³ ] of the liquid in the container. Here, the “in-container liquid” refers to the catalyst raw material liquid A or the catalyst raw material liquid B contained in the container.

S ³ / W ² is a value related to the shape of the container in which the catalyst raw material liquid A and the catalyst raw material liquid B are mixed. By adjusting the shape of the container in which the catalyst raw material liquid A and the catalyst raw material liquid B are mixed so as to satisfy the formula (iv), the surface area of the liquid surface with respect to the volume of the liquid in the container becomes a preferable range, and a stable stirring state Can be maintained. As for the value of S ³ / W ² , the lower limit is more preferably 0.5 or more, and even more preferably 0.8 or more.

  When the catalyst raw material liquid A and the catalyst raw material liquid B are respectively prepared in the steps (1) and (2) using a preparation container, either one of the catalyst raw material liquid A and the catalyst raw material liquid B (catalyst raw material) Liquid A) may be left in the preparation container as it is, and the other liquid (catalyst raw material liquid B) may be added. In order to satisfy the formula (iv), the liquid A) is transferred to a newly prepared container. An additive solution may be added. Further, a plurality of containers may be used, and the additive liquid may be added to the liquid in the container so as to satisfy the formula (iv) in each container.

The value of S is not particularly limited, but is preferably 0.01m ² ≦ S ≦ 3m ^2, the lower limit is 0.05 m ² or more, the upper limit is 2m ² or less being more preferred. Further, the value of W is not particularly limited, but 0.1 m ³ ≦ W ≦ 4.5 m ³ is preferable, the lower limit is 0.5 m ³ or more, and the upper limit is more preferably 3.0 m ³ or less.

  In the step (3), it is preferable that the addition port is disposed above the liquid level of the liquid in the container. Moreover, it is preferable that the value of T / S satisfy | fills following formula (v).

2 ≦ T / S ≦ 100 (v)
In formula (v), T has the same meaning as in formula (i), and S has the same meaning as in formula (iv). T / S indicates the number of addition ports per unit surface area of the liquid level of the liquid in the container, and a stable stirring state can be maintained by adjusting so as to satisfy the formula (v). As for the value of T / S, the lower limit is more preferably 3 or more, and further preferably 4 or more. The upper limit is more preferably 80 or less, and still more preferably 60 or less.

Furthermore, the liquid divided by T straight lines drawn from the center of the liquid level of the liquid in the container toward the wall surface of the container substantially parallel to the liquid level so that the central angle is 360 ° / T. When the surface regions are Y ₁ to Y _T , respectively, it is more preferable that one of the addition ports is arranged above each Y _{1 to} Y _T. By arranging the addition port in this way, when the catalyst raw material liquid A and the catalyst raw material liquid B are mixed, the contact surfaces of both liquids become more uniform, and the mixed state is stabilized, thereby improving the methacrylic acid yield. Effective catalyst particles can be stably produced. The “center of the liquid level of the liquid in the container” indicates the center of gravity of the liquid level of the liquid in the container. For example, when the liquid level is circular, the center of the circle, and when the liquid level is rectangular, Can be the intersection of diagonal lines. Further, “substantially parallel” means parallel within a range of ± 5 °. In particular, when Z ₁ is a contact point when a perpendicular line is dropped on the liquid level of the liquid in the container from the addition port existing at the top of Y ₁ , 360 ° / T about the center of the liquid level of the liquid in the container the top position of the Z ₁ is rotated moving, it is preferred that all addition port exists.

  In the step (3), the addition port does not exist in the upper part in the circular region drawn by the radius R [m] calculated by the following formula (vi) with the center of the liquid level of the liquid in the container as the center. Is preferred. That is, it is preferable that all of the addition ports exist at the upper part outside the range of the circular region.

式（ｖｉ）中、Ｓは前記式（ｉｖ）と同義である。前記容器内液の液面が円形である場合、下記式（ｖｉ）においてＲは容器内液の液面の半径の１／３となる。添加口をこのように配置することで、触媒原料液Ａと触媒原料液Ｂを混合する際に、両液の接触面がさらに均等となり、混合状態が安定することでメタクリル酸収率向上に有効な触媒粒子を安定して生成することができる。

In formula (vi), S has the same meaning as in formula (iv). When the liquid level of the liquid in the container is circular, R in the following formula (vi) is 1/3 of the radius of the liquid level of the liquid in the container. By arranging the addition port in this way, when the catalyst raw material liquid A and the catalyst raw material liquid B are mixed, the contact surfaces of the two liquids become more uniform, and the mixed state is stable, which is effective for improving the methacrylic acid yield. Can produce stable catalyst particles.

  In the first embodiment, in the step (3), it is preferable to add and mix the catalyst raw material liquid B into the container containing the catalyst raw material liquid A. It is presumed that catalyst particles that are more effective in improving the yield of methacrylic acid are more likely to be produced by mixing a catalyst raw material solution containing a cation raw material as an additive solution.

The liquid obtained in the step (3) contains a heteropolyacid having a Keggin structure or a salt thereof. When the liquid contains a heteropolyacid having a Keggin-type structure or a salt thereof, the produced catalyst particles can be stably present without change, and thus a catalyst having a high methacrylic acid yield can be obtained. In addition, it can confirm that the said liquid contains the heteropoly acid which has a Keggin type structure, or its salt by measuring what dried the said liquid by infrared absorption analysis. When a heteropolyacid having a Keggin structure or a salt thereof is included, the obtained infrared absorption spectrum has characteristic peaks in the vicinity of 1060, 960, 870, and 780 cm ⁻¹ .

  The pH of the liquid obtained in the step (3) is preferably 3.0 or less, and more preferably 2.5 or less. When the pH is 3.0 or less, a liquid containing a heteropolyacid having a Keggin structure or a salt thereof can be easily obtained. Examples of the method of adjusting the pH to 3.0 or less include a method of previously adjusting the pH of the catalyst raw material liquid A to be low.

(Drying process)
The method according to the present invention preferably includes a step of drying the liquid containing the heteropolyacid having a Keggin structure obtained in the step (3) or a salt thereof to obtain a catalyst precursor. Conditions such as the drying method and drying temperature of the liquid are not particularly limited, and can be appropriately selected depending on the desired shape and size of the dried product. Examples of the drying method include a drying method using a box-type dryer, a drum drying method, an airflow drying method, an evaporation to dryness method, and a spray drying method. A drying temperature can be 120-500 degreeC, for example, a minimum is 140 degreeC or more, and an upper limit is 400 degrees C or less. Drying can be performed until the liquid is dried.

(Molding process)
The method which concerns on this invention may implement the process of shape | molding the said catalyst precursor obtained at the said drying process before the heat treatment process mentioned later. The molding method is not particularly limited, and a known dry or wet molding method can be applied. For example, tableting molding, press molding, extrusion molding, granulation molding and the like can be mentioned. 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 addition, it is preferable to form the catalyst precursor alone without adding a carrier or a binder to the catalyst precursor at the time of molding, but if necessary, known additives such as graphite and talc, organic substances, and inorganic substances are used. A known binder may be added. Hereinafter, the catalyst precursor obtained by the drying step and the molded product of the catalyst precursor obtained by the molding step are collectively referred to as a catalyst precursor.

(Heat treatment process)
The method according to the present invention preferably includes a step of heat-treating the catalyst precursor. For example, the catalyst precursor can be heat-treated under the flow of at least one of air and inert gas. The heat treatment is preferably performed under a flow of oxygen-containing gas such as air. The “inert gas” refers to a gas that does not decrease the catalytic activity, and examples thereof include nitrogen, carbon dioxide gas, helium, and argon. These may use 1 type and may mix and use 2 or more types. The shape of the heat treatment container is not particularly limited, but it is preferable to use a tubular heat treatment container having a cross-sectional area of 2 square centimeters or more and 100 square centimeters or less. The heat treatment temperature is preferably 300 ° C. or higher and 700 ° C. or lower, the lower limit is 320 ° C. or higher, and the upper limit is more preferably 450 ° C. or lower.

  The methacrylic acid production catalyst thus obtained preferably contains a heteropolyacid having a Keggin structure or a salt thereof from the viewpoint of higher yield of methacrylic acid. The inclusion of a heteropolyacid having a Keggin structure or a salt thereof can be confirmed by measurement by infrared absorption analysis as described above.

[Method for producing methacrylic acid]
In the method for producing methacrylic acid according to the present invention, methacrylic acid is produced by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the catalyst for producing methacrylic acid produced by the method according to the present invention. Further, in the method for producing methacrylic acid according to the present invention, a catalyst for producing methacrylic acid is produced by the method according to the present invention, and methacrolein is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid. To produce methacrylic acid. According to these methods, methacrylic acid can be produced with high yield. Specifically, methacrylic acid can be produced by bringing a raw material gas containing methacrolein and molecular oxygen into contact with the catalyst for producing methacrylic acid according to the present invention. This reaction can be carried out in a fixed bed. The catalyst layer may be one layer or two or more layers. The catalyst for producing methacrylic acid may be supported on a carrier and may contain other additives. The concentration of methacrolein in the raw material gas is not particularly limited, but is preferably 1 to 20% by volume, the lower limit is 3% by volume or more, and the upper limit is more preferably 10% by volume or less. The methacrolein may contain a small amount of impurities such as lower saturated aldehydes that do not substantially affect this reaction. The concentration of molecular oxygen in the raw material gas is preferably 0.4 to 4 mol per mol of methacrolein, the lower limit is 0.5 mol or more, and the upper limit is more preferably 3 mol or less. As the molecular oxygen source, air is preferable from the viewpoint of economy, but 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 molecular oxygen with an inert gas such as nitrogen or carbon dioxide. Further, water vapor may be added to the source gas. By performing the reaction in the presence of water vapor, methacrylic acid can be obtained in a higher yield. The concentration of water vapor in the raw material gas is preferably 0.1 to 50% by volume, the lower limit is preferably 1% by volume or more, and the upper limit is more preferably 40% by volume or less. The contact time between the raw material gas and the catalyst for producing methacrylic acid is preferably 1.5 to 15 seconds, the lower limit is preferably 2 seconds or more, and the upper limit is more preferably 5 seconds or less. The reaction pressure is preferably 0.1 MPa (G) to 1.0 MPa (G). Note that (G) means a gauge pressure. The reaction temperature is preferably 200 to 450 ° C, the lower limit is 250 ° C or higher, and the upper limit is more preferably 400 ° C or lower.

[Method for producing methacrylate ester]
In the method for producing a methacrylic acid ester according to the present invention, methacrylic acid produced by the method according to the present invention is esterified. According to this method, a methacrylic acid ester can be obtained using methacrylic acid obtained by gas phase catalytic oxidation of methacrolein. Examples of the alcohol to be reacted with methacrylic acid include methanol, ethanol, isopropanol, n-butanol, and isobutanol. Examples of the resulting methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. The reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The reaction temperature is preferably 50 to 200 ° C.

  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 molar ratio of the elemental composition of the catalyst was calculated by analyzing the component in which the catalyst was dissolved in aqueous ammonia by ICP emission spectrometry. The analysis of the raw material gas and the product was performed using gas chromatography. From the results of gas chromatography, the conversion rate of methacrolein, the selectivity of methacrylic acid to be produced, and the single flow yield of methacrylic acid were determined by the following formula.

Conversion rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Methacrylic acid single yield = (C / A) × 100
In the formula, A represents the carbon number of the supplied methacrolein, B represents the carbon number of the reacted methacrolein, and C represents the carbon number of the produced methacrylic acid.

  U2 was calculated as the product of the molar concentration [mol / L] of the catalyst raw material liquid B and u1.

[Example 1]
In 400 parts of pure water, 100 parts of molybdenum trioxide, 7.5 parts of ammonium metavanadate, 11.4 parts of 85 mass% phosphoric acid aqueous solution, and 7.0 parts of copper (II) nitrate trihydrate were dissolved. While stirring this, the temperature was raised to 95 ° C., and the mixture was stirred for 2 hours while maintaining the liquid temperature at 95 ° C. to obtain catalyst raw material liquid A. The pH of the catalyst raw material liquid A was 2.1. On the other hand, 15.7 parts of cesium bicarbonate was dissolved in 20 parts of pure water to obtain catalyst raw material liquid B1. Further, 20.0 parts of ammonium bicarbonate was dissolved in 20 parts of pure water to obtain catalyst raw material liquid B2. The total volume of the catalyst raw material liquid A, the catalyst raw material liquid B1, and the catalyst raw material liquid B2 was 2.1 m ³ .

While keeping the temperature of the catalyst raw material liquid A in the vessel at 95 ° C., the catalyst raw material liquid A was added using a rotary blade stirrer, and the catalyst raw material liquid B1 was added and stirred for 15 minutes. Thereafter, the catalyst raw material liquid B2 was added and stirred for 15 minutes. In addition, when adding catalyst raw material liquids B1 and B2, T = 10, S = 1.54 m ² , V = 1.9 m ³ , S ³ / W ² = 1.01, T / ( ³ √V) = 8.1, T / S = 6.5, u1 = 0.20 L / min. Regarding u2, the catalyst raw material liquid B1 was 0.62 mol / min and the catalyst raw material liquid B2 was 1.40 mol / min. Further, a ring-shaped pipe having a radius of 3 × (√ (S / π)) / 7 [m] in which addition ports having a diameter of 2 mm are provided at equal intervals, and the center of the ring-shaped pipe is the level of the liquid in the container. so as to be positioned on top of the center, also the upper to the addition port of the region Y ₁ to Y ₁₀ is arranged to be disposed one each. Catalyst raw material liquids B1 and B2 were sequentially added from the addition port of the ring-shaped pipe. The resulting slurry contained a heteropolyacid having a Keggin structure or a salt thereof. Thereafter, the slurry was spray-dried to obtain a catalyst precursor.

The catalyst precursor was molded and placed in a cylindrical quartz glass baking vessel having an inner diameter of 3 cm. The catalyst for methacrylic acid production was prepared by heating at 10 ° C./h under air flow and heat treating at 380 ° C. for 2 hours. The resulting catalyst for methacrylic acid production had a Keggin type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 .

  The catalyst for producing methacrylic acid was filled in a reaction tube, and a raw material gas consisting of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor and 55% by volume of nitrogen was circulated and reacted at a reaction temperature of 300 ° C. . The product was collected and analyzed by gas chromatography to calculate the methacrylic acid yield. The results are shown in Table 1.

[Example 2]
The total volume of the catalyst raw material liquid A, the catalyst raw material liquid B1 and the catalyst raw material liquid B2 is 0.10 m ³ , T = 4, S = 0.196 m ² , V = 0.088 m ³ , S ³ / W ² = 0. 97, T / ( ³ √V) = 9.0, T / S = 20.4, u1 = 0.03 L / min, and _one addition port is arranged above each of the regions Y _{1 to} Y ₄ As described above, a ring-shaped pipe having a radius of 3 × (√ (S / π)) / 5 [m] in which addition ports having a diameter of 2 mm are provided at equal intervals was used. Moreover, about u2 at this time, catalyst raw material liquid B1 was 0.09 mol / min, and catalyst raw material liquid B2 was 0.21 mol / min. Except for these, a slurry was obtained in the same manner as in Example 1. The resulting slurry contained a heteropolyacid having a Keggin structure or a salt thereof. Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Keggin type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

[Example 3]
^{T = 13, S = 1.54m 2} , V = 1.9m 3, S 3 / W 2 = 1.01, T / (3 √V) = 10.5, T / S = 8.4, u1 = change to 0.26 L / min, area _{Y 1} Oite radius 5 × from the center of the liquid surface of the solution inside the container (√ (S / π)) / 7 [m] any addition port on top of or more regions Arranged. Moreover, about u2 at this time, catalyst raw material liquid B1 was 0.80 mol / min, and catalyst raw material liquid B2 was 1.83 mol / min. Except for these, a slurry was obtained in the same manner as in Example 1. The resulting slurry contained a heteropolyacid having a Keggin structure or a salt thereof. Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Keggin type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

[Comparative Example 1]
The total volume of the catalyst raw material liquid A, the catalyst raw material liquid B1 and the catalyst raw material liquid B2 is 0.0014 m ³ , T = 1, S = 0.0177 m ² , V = 0.003 m ³ , S ³ / W ² = 3. ^{28, T / (3 √V)} = 9.2, T / S = 56.5, u1 = change in 1.41L / min, 4 × from the center of the liquid surface of the solution inside the container (√ (S / π )) The addition port was arranged at the upper part of the position of / 5 [m]. Moreover, about u2 at this time, catalyst raw material liquid B1 was 4.35 mol / min, and catalyst raw material liquid B2 was 9.90 mol / min. Except for these, a slurry was obtained in the same manner as in Example 1. The resulting slurry contained a heteropolyacid having a Keggin structure or a salt thereof. Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Keggin type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

[Comparative Example 2]
The total volume of the catalyst raw material liquid A, the catalyst raw material liquid B1 and the catalyst raw material liquid B2 is 0.00048 m ³ , T = 1, S = 0.00785 m ² , V = 0.00043 m ³ , S ³ / W ² = 2. ^{62, T / (3 √V)} = 13.2, T / S = 127.4, u1 = change in 0.07 L / min, 2 × from the center of the liquid surface of the solution inside the container (√ (S / π )) The addition port was arranged at the upper part of the position of / 5 [m]. Moreover, about u2 at this time, catalyst raw material liquid B1 was 0.22 mol / min, and catalyst raw material liquid B2 was 0.49 mol / min. Except for these, a slurry was obtained in the same manner as in Example 1. The resulting slurry contained a heteropolyacid having a Keggin structure or a salt thereof. Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Keggin type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

[Comparative Example 3]
In 400 parts of pure water, 100 parts of molybdenum trioxide, 7.5 parts of ammonium metavanadate, and 11.4 parts of 85 mass% phosphoric acid aqueous solution were dissolved. While stirring this, the temperature was raised to 95 ° C., and the mixture was stirred for 2 hours while maintaining the liquid temperature at 95 ° C. to prepare catalyst raw material liquid A. The pH of the catalyst raw material liquid A was 6.9. On the other hand, 15.8 parts of cesium nitrate was dissolved in 20 parts of pure water to prepare catalyst raw material liquid B1. Further, 40.0 parts of 30% by mass of ammonia water was dissolved in 20 parts of pure water to prepare catalyst raw material liquid B2. Further, 7.0 parts of copper (II) nitrate trihydrate was dissolved in 40 parts of pure water to prepare catalyst raw material liquid B3. The total volume of the catalyst raw material liquid A and the catalyst raw material liquids B1 to B3 was 2.3 m ³ .

  While the temperature of the catalyst raw material liquid A in the vessel was cooled to 50 ° C. and maintained, the catalyst raw material liquid A was added using a rotary blade stirrer, and the catalyst raw material liquid B1 was added and stirred for 15 minutes. Thereafter, the catalyst raw material liquid B2 was added and stirred for 15 minutes. Further, catalyst raw material liquid B3 was added. Catalyst raw materials B1 to B3 were added in the same manner as in Example 3. Further, regarding u2, the catalyst raw material liquid B1 was 0.80 mol / min, the catalyst raw material liquid B2 was 2.87 mol / min, and the catalyst raw material liquid B3 was 0.18 mol / min. The resulting slurry contained a heteropolyacid having a Dawson structure or a salt thereof.

Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Dawson type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

[Comparative Example 4]
In the same manner as in Comparative Example 3, catalyst raw material liquids A and B1 to B3 were prepared. While the temperature of the catalyst raw material liquid A in the vessel was cooled to 50 ° C. and maintained, the catalyst raw material liquid A was added using a rotary blade stirrer, and the catalyst raw material liquid B1 was added and stirred for 15 minutes. Thereafter, the catalyst raw material liquid B2 was added and stirred for 15 minutes. Further, catalyst raw material liquid B3 was added. Catalyst raw materials B1 to B3 were added in the same manner as in Example 1. Further, regarding u2, the catalyst raw material liquid B1 was 0.62 mol / min, the catalyst raw material liquid B2 was 2.21 mol / min, and the catalyst raw material liquid B3 was 0.14 mol / min. The resulting slurry contained a heteropolyacid having a Dawson structure or a salt thereof.

Thereafter, a catalyst for producing methacrylic acid was prepared in the same manner as in Example 1. The resulting catalyst for methacrylic acid production had a Dawson type structure. Moreover, elemental compositions other than oxygen of the obtained catalyst for methacrylic acid production were Mo ₁₂ P _1.7 V _1.1 Cu _0.5 Cs _1.4 . Further, methacrylic acid was produced in the same manner as in Example 1 except that the methacrylic acid production catalyst was used. The results are shown in Table 1.

In Examples 1, 2 and 3, in the range of T / values of and u1 and u2 of ⁽³ √V) is the present invention, it was confirmed yield of high catalyst. In addition, in Example 3, the addition port was arrange | positioned only in the upper part of area | region Y1, and it became a catalyst with a somewhat low yield compared with Example 1 and 2. FIG. Further, since the value of u2 of Comparative Example 1, u1 and catalyst raw material solution B2 is the value of Comparative Example 2 T / ⁽³ √V) is outside the scope of the present invention, respectively, yield compared with Example Was low. Moreover, in Comparative Examples 3 and 4, since the obtained slurry did not contain a heteropolyacid having a Keggin structure or a salt thereof, the yield was low as compared with Examples. In addition, a methacrylic acid ester can be obtained by esterifying the methacrylic acid obtained in the present Example.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2006-161888 for which it applied on August 22, 2016, and takes in those the indications of all here.

  Although the present invention has been described with reference to the exemplary embodiments and examples, the present invention is not limited to the above exemplary embodiments and examples. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  The catalyst for producing methacrylic acid obtained by the method according to the present invention is industrially useful because it can produce methacrylic acid in a high yield.

Claims (18)

A method for producing a catalyst for producing methacrylic acid used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(1) preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium;
(2) preparing a catalyst raw material liquid B containing a cation raw material;
(3) The step of adding the other liquid to one of the catalyst raw material liquid A and the catalyst raw material liquid B and mixing to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof. Including
A method for producing a methacrylic acid production catalyst satisfying the following formulas (i) and (ii) in the step (3).
3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u1 ≦ 1.0 (ii)
(In the formulas (i) and (ii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the other liquid, and u1 is the volume flow rate of the other liquid to be added. [L / min.] When T is 2 or more, u1 represents an average value of the volume flow rate of the other liquid added from each addition port. A method for producing a catalyst for producing methacrylic acid used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen,
(1) preparing a catalyst raw material liquid A containing at least molybdenum, phosphorus and vanadium;
(2) preparing a catalyst raw material liquid B containing a cation raw material;
(3) adding and mixing the catalyst raw material liquid B to the catalyst raw material liquid A to prepare a liquid containing a heteropolyacid having a Keggin structure or a salt thereof, and
A method for producing a methacrylic acid production catalyst satisfying the following formulas (i) and (iii) in the step (3).
3.0 ≦ T / ( ³ √V) ≦ 13.0 (i)
0.01 ≦ u2 ≦ 8 (iii)
(In the formulas (i) and (iii), V is the volume [m ³ ] of the catalyst raw material liquid A, T is the number of addition ports for adding the catalyst raw material liquid B, and u2 is the catalyst raw material liquid B. The flow rate [mol / min] of the cation raw material is shown.When T is 2 or more, u2 represents the average value of the flow rate of the cation raw material of the catalyst raw material liquid B added from each addition port.   In the said formula (i), T is 2 or more, The manufacturing method of the catalyst for methacrylic acid production of Claim 1 or 2. The said process (3) WHEREIN: The other liquid is added and mixed in the container which satisfy | fills following formula (iv) in which any one of the said catalyst raw material liquid A and the said catalyst raw material liquid B entered. Of producing a catalyst for producing methacrylic acid.
0.1 ≦ S ³ / W ² ≦ 50 (iv)
(In the formula (iv), S represents the surface area [m ² ] of the liquid level of the liquid in the container, and W represents the volume [m ³ ] of the liquid in the container.) The production of the catalyst for methacrylic acid production according to claim 2, wherein in the step (3), the catalyst raw material liquid B is added and mixed in a container satisfying the following formula (iv) containing the catalyst raw material liquid A. Method.
0.1 ≦ S ³ / W ² ≦ 50 (iv)
(In the formula (iv), S represents the surface area [m ² ] of the liquid level of the liquid in the container, and W represents the volume [m ³ ] of the liquid in the container.)   The method for producing a catalyst for methacrylic acid production according to claim 4 or 5, wherein, in the step (3), the addition port is arranged above the liquid level of the liquid in the container. In the said process (3), the manufacturing method of the catalyst for methacrylic acid manufacture of Claim 6 which satisfy | fills following formula (v).
2 ≦ T / S ≦ 100 (v)
(In formula (v), T has the same meaning as in formula (i), and S has the same meaning as in formula (iv).) In the step (3), T straight lines drawn from the center of the liquid level of the liquid in the container toward the wall surface of the container so as to have a central angle of 360 ° / T and substantially parallel to the liquid level. 8. The methacrylic acid according to claim 6, wherein each of the liquid level regions to be divided is defined as Y ₁ to Y _T, and each of the addition ports is arranged above each Y _{1 to} Y _T. A method for producing a catalyst for production. In the step (3), the addition port does not exist in the upper part in the circular region drawn by the radius R [m] calculated by the following formula (vi) with the center of the liquid level of the liquid in the container as the center. The manufacturing method of the catalyst for methacrylic acid manufacture of any one of Claim 6 to 8.

(In formula (vi), S has the same meaning as in formula (iv)).   The method for producing a catalyst for methacrylic acid production according to claim 1, wherein in the step (3), the catalyst raw material liquid B is added and mixed in a container containing the catalyst raw material liquid A. The total volume of the catalyst raw material liquid A prepared in the step (1) and the catalyst raw material liquid B prepared in the step (2) is 0.2 m ³ or more. The manufacturing method of the catalyst for methacrylic acid manufacture as described in any one of.   The method for producing a catalyst for methacrylic acid production according to any one of claims 1 to 11, wherein the cation raw material is at least one selected from the group consisting of a compound containing an alkali metal and a compound containing an ammonium ion.   Furthermore, the manufacturing method of the catalyst for methacrylic acid manufacture of any one of Claim 1 to 12 including the process of drying the liquid containing the heteropoly acid which has the said Keggin type structure, or its salt, and obtaining a catalyst precursor.   Furthermore, the manufacturing method of the catalyst for methacrylic acid manufacture of Claim 13 including the process of heat-processing the said catalyst precursor. The method for producing a catalyst for methacrylic acid production according to any one of claims 1 to 14, wherein the catalyst for methacrylic acid production has an elemental composition represented by the following formula (vii).
_{Mo a P b V c Cu d} A e E f G g O h (vii)
(In the formula (vii), Mo, P, V, Cu and O are element symbols indicating molybdenum, phosphorus, vanadium, copper and oxygen, respectively. A is antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, E represents at least one element selected from the group consisting of selenium, silicon, tungsten and boron, where E is iron, zinc, chromium, magnesium, calcium, strontium, tantalum, cobalt, nickel, manganese, barium, titanium, tin, lead And at least one element selected from the group consisting of niobium, indium, sulfur, palladium, gallium, cerium and lanthanum, wherein G is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium A, b, c, d, e f, g and h represent the atomic ratio of each element, and when a = 12, b = 0.5-3, c = 0.01-3, d = 0.01-2, e = 0-3, f = 0-3, g = 0.01-3, and h is the atomic ratio of oxygen necessary to satisfy the valence of each element.)   A method for producing methacrylic acid, comprising subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen in the presence of the catalyst for producing methacrylic acid produced by the method according to any one of claims 1 to 15.   Production of methacrylic acid by producing a methacrylic acid production catalyst by the method according to any one of claims 1 to 15, and subjecting methacrolein to vapor phase catalytic oxidation with molecular oxygen in the presence of the methacrylic acid production catalyst. Method.   The manufacturing method of the methacrylic acid ester which esterifies the methacrylic acid manufactured by the manufacturing method of methacrylic acid of Claim 16 or 17.