JP2007098345A - Catalyst for methacrylic acid production and its production method, and production method of methacrylic acid using this catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst enabling a production of a methacrylic acid in high yield by a gas phase-catalytic-oxidation of methacrolein with molecular oxygen, its production method, and a production method of the methacrylic acid using the catalyst. <P>SOLUTION: This is the production method of the catalyst to produce the methacrylic acid by the gas phase-catalytic-oxidation of methacrolein, the catalyst having a composition represented by the following formula (1): P<SB>a</SB>Mo<SB>b</SB>V<SB>c</SB>Cu<SB>d</SB>X<SB>e</SB>Y<SB>f</SB>Z<SB>g</SB>O<SB>h</SB>. The method has a process of charging a slurry (II liquid) or solution containing an ammonium radical sign into a tank (A tank) wherein a slurry (I liquid) or solution containing at least molybdenum, phosphorus, and vanadium is present to prepare a mixture of I liquid and II liquid. At that time, from a charge start of the II liquid to the charge finish a charge speed of the II liquid should be controlled to (the standard speed×0.8)-(the standard speed×1.2), and a difference of the highest temperature with the lowest temperature of the solution or the slurry in the A tank should be controlled to 10°C or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a catalyst (hereinafter referred to as a catalyst for producing methacrylic acid) used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen, a catalyst to be produced, and this The present invention relates to a method for producing methacrylic acid using a catalyst.

  Among the conventionally known methods for producing a catalyst for producing methacrylic acid, as a method for producing a mixture of two or more kinds of mixed solutions containing catalyst component elements, for example, Patent Documents 1 to 3 are disclosed. .

  In Patent Document 1, a homogeneous solution containing the fourth component X such as molybdenum, vanadium, phosphorus and antimony is mixed with aqueous ammonia and a homogeneous solution containing other catalyst component elements such as cesium, and this mixed solution is A method for producing a catalyst for methacrylic acid production in which the catalyst is prepared by drying is disclosed. Thereby, the solubility of the fourth component X (especially antimony) is improved, and the catalyst performance is excellent in reproducibility and stability, and a long-life catalyst is obtained.

  In Patent Document 2, a mixing time for mixing a solution or slurry containing an ammonia compound with a solution or slurry containing molybdenum, or a solution or slurry containing potassium or the like mixed with the solution or slurry is set to 0. A method for producing a catalyst for producing methacrylic acid in the range of 1 to 15 minutes is disclosed.

Patent Document 3 discloses that a solution in which all catalyst raw materials are dissolved or suspended in water has an ammonium content in the range of 17 to 100 mol with respect to 12 atoms of molybdenum and a pH of 6.5 to 13. A method for producing an oxidation catalyst in the range is disclosed. The pH is adjusted by adding nitric acid or aqueous ammonia.
JP-A-5-31368 International Publication No. 2004-004900 Pamphlet JP-A-9-290162

  However, a catalyst produced using a conventional catalyst raw material mixing method or pH adjusting method is not necessarily sufficient as an industrial catalyst in terms of methacrylic acid yield, and further improvement in catalyst performance is desired.

  An object of the present invention is to provide a catalyst capable of producing methacrylic acid in a high yield 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. And

The above-mentioned problems of the present invention can be solved by the following present invention.
[1] A method for producing a catalyst having a composition represented by the following formula (1) for producing methacrylic acid by gas phase catalytic oxidation of methacrolein,
(I) preparing a solution or slurry (liquid I) containing at least molybdenum, phosphorus, and vanadium;
(Ii) preparing a solution or slurry (liquid II) containing ammonium roots;
(Iii) charging the II liquid into a tank (A tank) in which the I liquid exists to prepare an I liquid II liquid mixture;
(Iv) using the liquid I and liquid II mixture to obtain a catalyst precursor solution or slurry containing all catalyst components;
(V) drying and calcining the catalyst precursor solution or slurry;
In the step (iii), the charging speed of the liquid II is from a reference speed x 0.8 to a reference speed x 1.2 and from the start of the charging of the liquid II in the tank A. A method for producing a catalyst for methacrylic acid production, characterized in that the difference between the maximum temperature and the minimum temperature of a solution or slurry is controlled to 10 ° C. or less.

_{P a Mo b V c Cu d} X e Y f Z g O h (1)
(Wherein P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively, X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and Represents at least one element selected from the group consisting of boron, and Y represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, a, b, c, d, e, f, g and h represent the atomic ratio of each element. And when b = 12, a = 0.5-3, c = 0.01-3, d = 0.01-2, e = 0-3, f = 0-0 A g = 0.01 to 3, h is an atomic ratio of oxygen required to satisfy the valence of each component.)
[2] A catalyst for producing methacrylic acid produced by the method according to [1].
[3] A method for producing methacrylic acid, comprising subjecting methacrolein to gas phase catalytic oxidation with molecular oxygen in the presence of the methacrylic acid production catalyst according to [2].

  According to the present invention, it is possible to provide a catalyst capable of producing methacrylic acid in a high yield by vapor-phase catalytic oxidation of methacrolein with molecular oxygen, a method for producing the catalyst, and a method for producing methacrylic acid using the catalyst.

[Catalyst for methacrylic acid production, production method thereof]
The catalyst for producing methacrylic acid according to the present invention is a catalyst used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein, and has a composition represented by the following formula (1).

_{P a Mo b V c Cu d} X e Y f Z g O h (1)
In the formula, P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively, and X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten And Y represents at least one element selected from the group consisting of boron, and Y represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when b = 12, a = 0.5-3, c = 0.01-3, d = 0.01 ˜2, e = 0˜3, f = 0˜3, g = 0.01-3, and h is an atomic ratio of oxygen necessary to satisfy the valence of each component.

And the catalyst for methacrylic acid production which has the above-mentioned composition,
(I) preparing a solution or slurry (liquid I) containing at least molybdenum, phosphorus, and vanadium;
(Ii) preparing a solution or slurry (liquid II) containing ammonium roots;
(Iii) charging the II liquid into a tank (A tank) in which the I liquid exists to prepare an I liquid II liquid mixture;
(Iv) using the liquid I and liquid II mixture to obtain a catalyst precursor solution or slurry containing all catalyst components;
(V) drying and calcining the catalyst precursor solution or slurry;
It manufactures by the method containing. At this time, during the period from the start of charging of the liquid II to the end of charging in the step (iii), the charging speed of the liquid II is a reference speed × 0.8 to a reference speed × 1.2, and in the tank A The difference between the maximum temperature and the minimum temperature of the solution or slurry is controlled to 10 ° C. or lower. By such a method, a catalyst for producing methacrylic acid, which can obtain methacrylic acid in a high yield, is obtained.

  Although the mechanism for improving the performance of the methacrylic acid production catalyst obtained by the above method is not necessarily clear, when preparing the liquid I liquid II liquid mixture, the charging speed of the liquid II is within a certain range, Furthermore, it is presumed that the crystal structure in which methacrylic acid is obtained in a high yield is formed in the obtained catalyst by setting the temperature change during mixing of the liquid I and liquid II within a certain range.

In the present invention, the ammonium root means ammonia (NH ₃ ) that can be ammonium (NH ₄ ⁺ ) or ammonium contained in an ammonium-containing compound such as an ammonium salt.

  Hereinafter, the method for producing the catalyst for producing methacrylic acid of the present invention will be described in more detail.

<Preparation of liquid I>
In the present invention, a solution or slurry (solution I) containing at least molybdenum, phosphorus, and vanadium is prepared (step (i)). The liquid I can be prepared by dissolving or suspending at least molybdenum, phosphorus and vanadium raw materials in a solvent.

  In addition to molybdenum, phosphorus and vanadium, the liquid I may contain copper, the element X, the element Y, the element Z and an ammonium root. However, the amount of the ammonium root contained in the liquid I is not particularly limited, but is preferably 0 to 1.5 mol, more preferably 0 to 1.0 mol with respect to 12 mol of molybdenum. By setting the amount of the ammonium root within this range, a catalyst having a higher methacrylic acid yield can be obtained. The amount of ammonium root contained in the liquid I can be adjusted by the amount of ammonia or ammonium-containing compound used.

  As a raw material used for preparation of I liquid, it can select from compounds, such as an oxide of each said element, nitrate, carbonate, ammonium salt, and can be used suitably. For example, the molybdenum compound is preferably a compound not containing ammonium, such as molybdenum trioxide and molybdic acid, but various ammonium molybdates such as ammonium paramolybdate, ammonium dimolybdate, and ammonium tetramolybdate are also 10 mass% or less. Can be used. As the phosphorus compound, orthophosphoric acid, phosphorus pentoxide, ammonium phosphate and the like can be used. As the vanadium compound, vanadium pentoxide, ammonium metavanadate, or the like can be used. Furthermore, heteropolyacids such as phosphomolybdic acid, molybdovanadolinic acid, and ammonium phosphomolybdate can also be used as the compound of phosphorus, molybdenum, and vanadium. These compounds may use 1 type with respect to each element, or may use 2 or more types together.

  Examples of the solvent used for preparing the liquid I include water, ethyl alcohol, acetone and the like, but it is preferable to use water. The amount of the solvent used for preparing the liquid I is not particularly limited, but the mass ratio of the molybdenum compound and the solvent used for preparing the liquid I is preferably 1: 0.1 to 1: 100, and 1: 0. 5 to 1:50 is more preferable. When the amount of the solvent is within this range, a catalyst with a higher methacrylic acid yield can be obtained.

  The liquid I can be prepared by mixing the above compound used as a raw material with a solvent and stirring or dissolving it at room temperature to form a solution or slurry. In general, it is preferable to prepare by heating and stirring. The temperature during stirring is preferably 80 ° C. or higher, and more preferably 90 ° C. or higher. The temperature during stirring is preferably 150 ° C. or lower, and more preferably 130 ° C. or lower. When the heating temperature is in such a range, a more active catalyst can be obtained. The stirring time is preferably 0.5 hours or more, and more preferably 1 hour or more. Further, the stirring time is preferably 24 hours or less, and more preferably 12 hours or less. When the stirring time is within such a range, the above compound can be easily dissolved or suspended, whereby the reaction between the raw materials can be sufficiently advanced.

  When the element Z is contained in the liquid I, the compound of the element Z is mixed with a solvent to prepare a solution or slurry (sometimes referred to as liquid III). It is preferable to add to a solution or slurry containing the above elements (at least molybdenum, phosphorus, and vanadium). At this time, the temperature of the mixed solution or slurry is preferably 80 ° C. or less, and more preferably 30 to 70 ° C. Note that cesium is preferably used as the element Z because a particularly excellent effect can be obtained. Examples of the cesium compound used as the raw material include cesium nitrate, cesium carbonate, and cesium hydroxide. The cesium compound may be used alone or in combination of two or more.

<Preparation of solution II>
In this invention, the solution or slurry (II liquid) containing an ammonium root is prepared (process (ii)). The II solution can be prepared by dissolving or suspending a compound containing an ammonium root in a solvent.

  The II liquid may contain phosphorus, molybdenum, vanadium, copper, element X, element Y, and element Z in addition to the compound containing an ammonium root, but it is preferable that these are not substantially contained.

  The amount of the ammonium root contained in the II liquid is not particularly limited, but it is preferably 6 mol or more, more preferably 7 mol or more with respect to 12 mol of molybdenum contained in the I liquid. Further, the amount of ammonium root contained in the II solution is preferably 17 mol or less, more preferably 15 mol or less, with respect to 12 mol of molybdenum contained in the I solution. When the amount of the ammonium root is within this range, a catalyst having a higher methacrylic acid yield can be obtained.

  Ammonia and ammonium salts are mentioned as a compound containing the ammonium root used for preparation of II liquid. Specifically, ammonia (ammonia water), ammonium carbonate, ammonium hydrogen carbonate, ammonium nitrate and the like can be exemplified. The compound containing an ammonium root may be used alone or in combination of two or more.

  Examples of the solvent used for preparing the II solution include water, ethyl alcohol, acetone, and the like, but it is preferable to use water. The amount of the solvent used for the preparation of the II solution is not particularly limited, but the mass ratio of the compound containing the ammonium root used for the preparation of the II solution and the solvent is preferably 1: 0.1 to 1: 100. : 0.5 to 1:50 is more preferable. When the amount of the solvent is within this range, a catalyst with a higher methacrylic acid yield can be obtained.

  The II solution can be prepared by adding a compound containing an ammonium root to a solvent and stirring or dissolving at room temperature to form a solution or slurry. If necessary, it can be prepared by heating to about 80 ° C. However, when aqueous ammonia is used as the compound containing an ammonium root, such a preparation step is not necessarily required because water as a solvent is included.

<Preparation of liquid mixture of liquid I and liquid II>
In this invention, the said II liquid is thrown into the tank (A tank) in which the said I liquid exists, and I liquid II liquid mixed liquid is prepared (process (iii)). That is, the prepared I liquid is put into the A tank, and then the II liquid is put into the A tank to mix both liquids. When the liquid I is prepared in the tank A, the liquid II may be put into the tank A as it is.

  When the liquid II is introduced into the A tank and mixed with the liquid I, the present inventors not only include the liquid II charging time but also the liquid II charging speed and the liquid in the tank A at the time of liquid II charging. It has been found that the temperature of the slurry has a great influence on the performance of the produced catalyst, and that a catalyst having a particularly high methacrylic acid yield can be obtained by keeping them constant. In Patent Document 2, no consideration is given to the control of the charging speed of the II liquid and the temperature of the solution or slurry at the time of charging the II liquid. Does not satisfy the specified input speed and temperature conditions. This is particularly remarkable when the charging time is 15 minutes or longer.

  As the time (throwing time) for charging the II liquid into the A tank, for example, a time in the range of 0.1 to 60 minutes is set in advance. The charging time is preferably 5 minutes or longer, more preferably 10 minutes or longer. The charging time is preferably 30 minutes or less, more preferably 25 minutes or less. In addition, "injection time" is the total time it takes to add the entire amount of the II liquid into the A tank. When the II liquid is dropped into the A tank, it represents the dripping time. Agitation time is not included. Moreover, when dividing | segmenting II liquid and dividing | segmenting and mixing in multiple times, the total of each injection | pouring time is represented, and the time between each injection | pouring is not included.

  In the present invention, the charging speed of the II liquid is controlled to the reference speed × 0.8 to the reference speed × 1.2 from the start of the charging of the II liquid to the end of the charging. The control range of the charging speed is more preferably a reference speed × 0.9 to a reference speed × 1.1. Here, the “reference speed” is a value obtained by dividing the total mass of the liquid II by the actual charging time. In the present invention, the charging speed of the II liquid is controlled as needed so that the charging speed (instantaneous value) of the II liquid during the charging of the II liquid falls within the above range with respect to the reference speed. Here, the charging speed (instantaneous value) is an average value of a period (measurement span) of 1/20 of the charging time. Therefore, even if the input speed temporarily deviates from the above range within the measurement span, it is only necessary to enter the above range as the average value of the measurement span.

  In actual operation, for example, a target charging time and a target speed that are used as a guide are temporarily set, and the charging speed (instantaneous value) of the II liquid during the II liquid charging is within the above range with respect to the target speed. A method of controlling the charging speed of the II liquid as needed is mentioned. Here, the “target speed” is a value obtained by dividing the total mass of the liquid II by the target charging time. In this example, the reference speed is calculated after the completion of injection, and when looking back, the injection speed of the liquid II only needs to be within the above range. Even if the target speed is not set, the liquid II is introduced by controlling so that the fluctuation range of the introduction speed is reduced. As a result, if the introduction speed is within the above-mentioned reference speed range, it is still I do not care.

  Specifically, an adjustment valve is installed in the middle of the pipe connected from the II liquid preparation tank (B tank) to the A tank, and the charging speed of the II liquid is checked while the II liquid is being charged into the A tank. However, if necessary, the opening rate of the adjusting valve may be adjusted to control the charging speed of the II liquid. This adjustment valve may be an automatic control valve or a manual valve. Further, instead of the adjustment valve, a metering pump may be used to control the charging speed of the II liquid.

  The effect of controlling the charging speed of the II liquid increases as the amount of the II liquid to be input increases. Specifically, a larger effect is obtained when the volume of the II liquid exceeds 10 L. This is because when the II liquid is supplied from the head tank, the difference between the liquid level height at the start and end of the addition increases as the amount of the liquid increases. .

  Further, the temperature of the II liquid to be added and the temperature of the solution or slurry in the tank A may be normal temperature or may be heated. The temperature of the solution or slurry in the tank A is preferably 100 ° C. or lower, and more preferably 80 ° C. or lower. Further, the temperature of the II solution to be added is preferably 80 ° C. or less, and more preferably 40 ° C. or less. By preparing a liquid mixture of liquid I and liquid II at a liquid temperature in such a range, a more active catalyst can be obtained. Moreover, 5 degreeC or more is preferable and, as for the temperature of the solution or slurry in A tank, 30 degreeC or more is more preferable. Further, the temperature of the II liquid to be added is preferably 1 ° C. or higher, and more preferably 5 ° C. or higher.

  However, in the present invention, the difference between the maximum temperature and the minimum temperature of the solution or slurry in the tank A is controlled to 10 ° C. or less from the start of the input of the II liquid to the end of the input. The temperature control range is preferably 9 ° C. or less, more preferably 6 ° C. or less, and particularly preferably 3 ° C. or less.

  Specifically, a temperature adjustment jacket, an internal coil, an external heat exchanger, and the like may be installed in the A tank and the temperature of the solution or slurry in the A tank may be controlled. In addition, considering the mass ratio of liquid I and liquid II, the charging speed of liquid II, the heat generated during mixing, the heat dissipating property of tank A, etc. Alternatively, the temperature of the liquid I and liquid II may be set. The temperature of the solution or slurry in tank A is measured at a representative position. When there is almost no temperature difference depending on the position, the temperature measured at an appropriate place is adopted, and when there is a temperature difference, the average value of the temperatures measured at a plurality of places is adopted.

Moreover, it is preferable that the solution or slurry in the A tank is stirred when the II liquid is introduced into the A tank. Its agitation power is preferably in a 0.01~3.5kW / m ^3, and more preferably to 0.05~3kW / m ^3.

<Preparation of catalyst precursor solution or slurry>
In the present invention, a catalyst precursor solution or slurry containing all catalyst components is obtained using the liquid mixture I and liquid II (step (iv)). The catalyst precursor solution or slurry can be prepared by dissolving or suspending the remaining raw materials in the liquid mixture I and liquid II. If necessary, an additional solvent may be added. In addition, what is necessary is just to use it as a catalyst precursor solution or a slurry as it is, when all the catalyst components are already contained in the liquid I liquid II liquid mixture.

<Drying / Baking>
In the present invention, the catalyst precursor solution or slurry is dried and calcined (step (v)) to obtain a target methacrylic acid production catalyst.

  First, the catalyst precursor solution or slurry is dried to obtain a dried catalyst precursor. The method for drying the catalyst precursor solution or slurry is not particularly limited, and various methods can be used. For example, an evaporative drying method, a spray drying method, a drum drying method, an air current drying method, or the like can be used. The model of the dryer used for drying, the temperature and time during drying, etc. are not particularly limited, and a dried catalyst precursor according to the purpose can be obtained by appropriately changing the drying conditions.

  A catalyst for methacrylic acid production can be obtained by pulverizing the dried product of the catalyst precursor thus obtained, if necessary, followed by firing. Firing may be performed after the dried catalyst precursor has been formed in advance, or may be performed without forming the dried catalyst precursor. Usually, it is preferable to prepare a molded product of a dried catalyst precursor and calcine it to obtain a catalyst for producing methacrylic acid.

  The molding method is not particularly limited, and various known dry and wet molding methods can be applied. Although it can be molded using a carrier such as silica, a method of molding without using a carrier is usually preferred. Specific examples of the molding method include tableting molding, press molding, extrusion molding, granulation molding and the like. The shape of the molded product is not particularly limited, and for example, a desired shape such as a columnar shape, a ring shape, or a spherical shape can be selected. In molding, a small amount of known additives such as graphite and talc may be added.

  The firing method and firing conditions of the dried catalyst precursor or the molded product thereof are not particularly limited, and known firing methods and firing conditions can be applied. The optimum conditions for calcination vary depending on the catalyst raw material used, the catalyst composition, the preparation method, etc., but usually the calcination temperature is 200 to 500 ° C., preferably 300 to 450 under an oxygen-containing gas flow such as air or an inert gas flow. The baking time is 0.5 hour or more at 1 ° C., preferably 1 to 40 hours. Here, the inert gas means a gas that does not decrease the reaction activity of the catalyst. Specific examples of such a gas include nitrogen, carbon dioxide, helium, and argon.

[Method for producing methacrylic acid]
Next, the manufacturing method of methacrylic acid of this invention is demonstrated.

  The method for producing methacrylic acid according to the present invention is a method for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the catalyst of the present invention obtained as described above.

  In the method for producing methacrylic acid of the present invention, a raw material gas containing methacrolein and molecular oxygen is brought into contact with a catalyst. The methacrolein concentration in the raw material gas can be varied within a wide range. Usually, the methacrolein concentration is 1 to 20% by volume, particularly 3 to 10% by volume. The source gas may contain a small amount of impurities such as lower saturated aldehyde, but the amount is preferably as small as possible.

  The source gas contains molecular oxygen, but it is economical to use air as the molecular oxygen source. If desired, air or the like enriched with pure oxygen can be used. The molecular oxygen in the raw material gas is usually 0.4 to 4 mol, preferably 0.5 to 3 mol, per 1 mol of methacrolein.

  The source gas preferably contains water vapor. The water vapor concentration in the raw material gas is usually 0.1 to 50% by volume, and preferably 1 to 40% by volume. When the reaction is carried out in the presence of water vapor, methacrylic acid can be obtained in a higher yield. The source gas may contain an inert gas such as nitrogen or carbon dioxide.

  The gas phase catalytic reaction of methacrolein is usually carried out in a fixed bed. The catalyst layer may be one layer or two or more layers. The catalyst may be supported on a carrier, or may be a mixture of other additive components.

  The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature can usually be selected in the range of 230 to 450 ° C, and particularly preferably 250 to 400 ° C. The flow rate of the source gas is not particularly limited, but it is usually preferable to set the flow rate so that the contact time is 1.5 to 15 seconds, and particularly preferably 2 to 5 seconds.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

  The composition of the catalyst was determined from the charged amount of the catalyst raw material. Moreover, the analysis of the raw material gas and the reaction product in the production of methacrylic acid was performed using gas chromatography.

Based on the obtained analysis results, methacrolein conversion rate (may be referred to as MAL conversion rate), generated methacrylic acid selectivity (may be referred to as MAA selectivity), methacrylic acid single stream yield ( The MAA yield may be expressed by the following formula.
Conversion rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Single flow yield of methacrylic acid (%) = (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]
(Manufacture of catalyst)
100 kg of pure water was poured into a tank-type reaction tank (A tank) with a diameter of 650 mm and an internal volume of 250 L at room temperature, and stirred with paddles with two-stage blades, and 50 kg of molybdenum trioxide and 85 mass% phosphoric acid aqueous solution 3 .67 kg, 2.03 kg of ammonium metavanadate, 0.70 kg of copper nitrate dissolved in 6.10 kg of pure water and a solution of 0.58 kg of ferric nitrate dissolved in 2.50 kg of pure water were added to 98 ° C. After heating, the mixture was heated and stirred at 98 ° C. for 5 hours. After 5 hours, the mixture was cooled to 70 ° C., and the resulting mixture was designated as Liquid I.

  Into a tank type reaction tank (B tank) having a diameter of 200 mm and an internal volume of 40 L installed above the tank A, 20 kg of 25 mass% ammonia water (II liquid) was charged at room temperature.

Next, the target charging time of the II liquid was set to 25 minutes (target speed: 0.80 kg / min), and the II liquid in the B tank was charged into the A tank, thereby mixing the I liquid and the II liquid. The charging speed of the II liquid was controlled so as to reach the target speed by an automatic control valve installed in the middle of the charging pipe. As a result, the introduction of the II liquid was completed in 25 minutes and 30 seconds (reference speed: 0.78 kg / min). From the start of charging of the II liquid to the end of charging, the charging speed of the II liquid could be controlled within the range of standard speed × 0.90 to standard speed × 1.10. During the addition of the liquid II, the slurry in the tank A was stirred at a stirring power of 1.1 kW / m ³ . Moreover, temperature control was performed with the temperature control jacket installed in A tank. The difference (temperature change width) between the maximum temperature and the minimum temperature of the slurry in the tank A was 3 ° C. from the start of the II liquid input to the end of the addition. In this way, a liquid mixture I and liquid II, which was a catalyst precursor slurry, was obtained.

The catalyst precursor slurry was heated to 101 ° C. and evaporated to dryness with stirring. The obtained solid was dried at 130 ° C. for 16 hours, molded into a ring shape with an outer diameter of 5 mmφ, an inner diameter of 1 mmφ, and a height of 4 mm by a tableting machine, and then calcined at 380 ° C. for 12 hours under air flow. A catalyst was obtained. The composition of the obtained catalyst (other than oxygen) was P _1.1 Mo ₁₂ V _0.6 Cu _0.1 Fe _0.05 Cs _1.3 .

(Production of methacrylic acid)
This catalyst is filled in a reaction tube, and a mixed gas of 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor, and 55% by volume of nitrogen is used as a raw material gas. The gas phase catalytic oxidation reaction of methacrolein was performed in 6 seconds. The results of this reaction are shown in Table 1.

[Example 2]
The adjustment of the II liquid charging speed is performed with a manual valve installed in the middle of the charging pipe, 0.94 kg / min (target speed × 1.18) for 5 minutes after the start of charging, and 0.88 kg / min (10 minutes after that). The catalyst was produced in the same manner as in Example 1, except that the target speed was 1.10), and then controlled to 0.65 kg / min (target speed × 0.82) until the end of charging. As a result, the introduction of the liquid II was completed in 24 minutes (reference speed: 0.83 kg / min). The charging speed of the liquid II was as follows: reference speed × 1.17 to 1.19 for 5 minutes from the start of charging, reference speed × 1.09 to 1.13 for 10 minutes thereafter, and reference speed × 0. Control was possible within the range of 80 to 0.83. From the start of liquid II charging to the end of charging, the temperature change width of the slurry in tank A was 7 ° C.

  Using the obtained catalyst, methacrylic acid was produced in the same manner as in Example 1. The results of this reaction are shown in Table 1.

[Comparative Example 1]
The adjustment of the II liquid charging speed is performed with a manual valve installed in the middle of the charging pipe, 1.19 kg / min (target speed × 1.49) for 9 minutes from the start of charging, and 0.96 kg / min (5 minutes after that). The catalyst was produced in the same manner as in Example 1 except that the target speed was 1.20), and was controlled to 0.40 kg / min (target speed × 0.50) until the end of the charging. As a result, the introduction of the II liquid was completed in 23 minutes (reference speed: 0.87 kg / min). The charging speed of the liquid II was the reference speed × 1.48 to 1.51 for 9 minutes from the start of charging, the reference speed × 1.18 to 1.21 for 5 minutes thereafter, and the reference speed × 0. It became in the range of 49-0.52. From the start of charging of the II liquid to the end of charging, the temperature change width of the slurry in the tank A was 12 ° C.

  Using the obtained catalyst, methacrylic acid was produced in the same manner as in Example 1. The results of this reaction are shown in Table 1.

[Comparative Example 2]
A catalyst was produced in the same manner as in Comparative Example 1 except that the temperature adjustment of the tank A was strengthened by increasing the amount of water through the jacket. From the start of charging of the II liquid to the end of charging, the temperature change width of the slurry in the tank A was 9 ° C.

  Using the obtained catalyst, methacrylic acid was produced in the same manner as in Example 1. The results of this reaction are shown in Table 1.

[Comparative Example 3]
A catalyst was produced in the same manner as in Example 1 except that the temperature of the tank A was not adjusted. As a result, II liquid charging was completed in 25 minutes (reference speed: 0.80 kg / min). From the start of charging of the II liquid to the end of charging, the charging speed of the II liquid could be controlled within the range of standard speed × 0.90 to standard speed × 1.10. Further, the temperature change width of the slurry in the tank A was 18 ° C. from the start of the II liquid charging to the end of the charging.

  Using the obtained catalyst, methacrylic acid was produced in the same manner as in Example 1. The results of this reaction are shown in Table 1.

[Comparative Example 4]
A catalyst was produced in the same manner as in Example 1 except that the opening of the manual valve installed in the middle of the charging pipe was kept constant during the II liquid charging. In addition, the opening degree of the manual valve was determined in advance so that the charging time was 25 minutes by conducting a charging test using the II liquid. As a result, II liquid charging was completed in 25 minutes (reference speed: 0.80 kg / min). Reference speed x 1.19 to 1.28 for 5 minutes from the start of charging, reference speed x 0.84 to 1.16 for 15 minutes thereafter, and reference speed x 0.72 to 0. 20 from 20 minutes to the end of charging. 81. Further, the temperature change width of the slurry in the tank A was 13 ° C. from the start of the II liquid charging to the end of the charging.

  Using the obtained catalyst, methacrylic acid was produced in the same manner as in Example 1. The results of this reaction are shown in Table 1.

  The method for producing a catalyst for producing methacrylic acid according to the present invention and the catalyst produced thereby are suitable for the method for producing methacrylic acid in which methacrolein is subjected to gas phase catalytic oxidation with molecular oxygen, including the method for producing methacrylic acid according to the present invention. Can be used for

Claims (3)

A method for producing a catalyst for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein having a composition represented by the following formula (1):
(I) preparing a solution or slurry (liquid I) containing at least molybdenum, phosphorus, and vanadium;
(Ii) preparing a solution or slurry (liquid II) containing ammonium roots;
(Iii) charging the II liquid into a tank (A tank) in which the I liquid exists to prepare an I liquid II liquid mixture;
(Iv) using the liquid I and liquid II mixture to obtain a catalyst precursor solution or slurry containing all catalyst components;
(V) drying and calcining the catalyst precursor solution or slurry;
In the step (iii), the charging speed of the liquid II is from a reference speed x 0.8 to a reference speed x 1.2 and from the start of the charging of the liquid II in the tank A. A method for producing a catalyst for methacrylic acid production, characterized in that the difference between the maximum temperature and the minimum temperature of a solution or slurry is controlled to 10 ° C. or less.
_{P a Mo b V c Cu d} X e Y f Z g O h (1)
(Wherein P, Mo, V, Cu and O represent phosphorus, molybdenum, vanadium, copper and oxygen, respectively, X represents antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and Represents at least one element selected from the group consisting of boron, and Y represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, a, b, c, d, e, f, g and h represent the atomic ratio of each element. And when b = 12, a = 0.5-3, c = 0.01-3, d = 0.01-2, e = 0-3, f = 0-0 A g = 0.01 to 3, h is an atomic ratio of oxygen required to satisfy the valence of each component.)   A catalyst for producing methacrylic acid produced by the method according to claim 1. 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 according to claim 2.