JP2008149262A - Method for producing catalyst for unsaturated carboxylic acid synthesis - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a catalyst for unsaturated carboxylic acid synthesis within a short time while keeping the catalytic performance in synthesis of an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, and the like. <P>SOLUTION: The method is for producing an unsaturated carboxylic acid synthesis catalyst to be used at the time of synthesizing an unsaturated carboxylic acid by vapor phase catalytic oxidation of an unsaturated aldehyde with molecular-state oxygen and involves packing a container for firing previously heated at 100°C or higher and lower than 300°C with a catalyst precursor and thereafter carrying out firing in a temperature condition of 300°C or higher and 700°C or lower as the highest temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an unsaturated carboxylic acid synthesis catalyst, and more particularly, to a methacrylic acid synthesis catalyst used for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. Suitable for manufacturing method.

  As a catalyst for producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen, a catalyst mainly containing a heteropolyacid such as molybdophosphoric acid or molybdophosphate is known. Further, it is known that a composite oxide catalyst mainly composed of molybdenum or bismuth is suitable as a catalyst for vapor-phase catalytic oxidation of acrolein to acrylic acid. Many studies have been made on the production methods of these catalysts. In many of them, first, a raw material liquid such as an aqueous solution or an aqueous slurry containing raw materials of each element constituting the catalyst is prepared, and then this is dried and calcined. By doing so, the catalyst is manufactured.

Among these, various investigations have also been made on the firing step. In these catalysts, the maximum value of the calcination temperature is often set to 300 ° C. or more and 700 ° C. or less. For example, Patent Document 1 describes the firing atmosphere and the rate of temperature rise during firing (10 ° C. to 100 ° C./hour), but the method of gradually heating from room temperature requires time for the production of the catalyst, There was a problem that the cost of catalyst production was high. Further, for example, Patent Document 2 describes a gas (air) distribution method during firing, which is based on the premise that the firing container and the reaction container are the same. For example, in the case of this Patent Document 2, it is necessary to stop the production of reactants in the factory for the time required for the firing of the catalyst in operation in an actual factory, and in combination with a method of gradually heating from room temperature. Considering this, the cost of manufacturing the methacrylic acid and acrylic acid becomes higher than simply the high cost of manufacturing the catalyst.
JP 58-61833 A JP 58-67643 A

  Therefore, a method of preheating the firing vessel to 300 ° C. or more and 700 ° C. or less and then filling the catalyst precursor into the firing vessel is also conceivable, but when this method is carried out for the production of an unsaturated carboxylic acid synthesis catalyst, Currently, a catalyst that exhibits a sufficient yield cannot be obtained, and further improvement is desired as a method for producing an industrial catalyst.

  The present invention has been made in view of the above circumstances, and a method for firing and producing an unsaturated carboxylic acid synthesis catalyst in a shorter time while maintaining the catalyst performance in the synthesis of unsaturated carboxylic acid such as methacrylic acid and acrylic acid. The issue is to provide

  As a result of earnestly examining the structure formation process of the catalyst, the present inventors have preliminarily heated the firing container in a temperature range of 100 ° C. or higher and lower than 300 ° C., and then filled with the catalyst precursor, thereby maintaining the catalyst performance. The present inventors have found that an unsaturated carboxylic acid synthesis catalyst can be calcined and produced in a shorter time, and the present invention has been completed. The present invention is particularly suitable for a method for producing a methacrylic acid synthesis catalyst used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein with molecular oxygen, but it is produced through a similar process. This is effective for general unsaturated carboxylic acid synthesis catalysts, and comprises the following requirements [1] to [4].

  [1] A method for producing an unsaturated carboxylic acid synthesis catalyst used for synthesizing an unsaturated carboxylic acid by gas-phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen, wherein the catalyst precursor is preliminarily set to 100 ° C or higher. A method for producing an unsaturated carboxylic acid synthesis catalyst, comprising filling a firing container heated to less than 300 ° C and then firing under a condition where the maximum temperature is 300 ° C to 700 ° C.

  [2] As described in [1] above, a catalyst precursor obtained by preparing an aqueous slurry or an aqueous solution containing all catalyst raw materials and drying a raw material liquid whose pH is adjusted to 3.0 or more and 8.0 or less is used. A method for producing an unsaturated carboxylic acid synthesis catalyst.

  [3] An unsaturated carboxylic acid synthesis catalyst produced by the production method according to [1] or [2].

  [4] A method for producing an unsaturated carboxylic acid, characterized in that the unsaturated aldehyde is subjected to gas phase catalytic oxidation with molecular oxygen using the unsaturated carboxylic acid synthesis catalyst according to [3].

  ADVANTAGE OF THE INVENTION According to this invention, the method of baking and manufacturing the catalyst for unsaturated carboxylic acid synthesis in a shorter time can be provided, maintaining catalyst performance.

  Hereinafter, the present invention will be described in detail.

  The unsaturated carboxylic acid referred to in the present invention is a compound in which a carboxylic acid group is bonded to an unsaturated hydrocarbon, and examples thereof include methacrylic acid and acrylic acid. The unsaturated aldehyde referred to in the present invention is a compound in which an aldehyde group is bonded to an unsaturated hydrocarbon, and examples thereof include methacrolein and acrolein. Unsaturated carboxylic acids can be synthesized by vapor-phase catalytic oxidation of the corresponding unsaturated aldehydes with molecular oxygen.

  The present invention relates to a method for producing an unsaturated carboxylic acid synthesis catalyst used in the synthesis, and the catalyst precursor is charged into a firing container that has been heated to 100 ° C. or more and less than 300 ° C. The catalyst is produced by firing at a maximum value of 300 ° C. or more and 700 ° C. or less.

  The present invention can be used for the production of unsaturated carboxylic acid synthesis catalysts in general, but an aqueous slurry or aqueous solution containing all catalyst raw materials is prepared, and its pH is adjusted to 3.0 or more and 8.0 or less. It is more preferable to use a catalyst precursor obtained by drying the raw material liquid.

  The composition of the unsaturated carboxylic acid synthesis catalyst produced in the present invention is not particularly limited, but preferably has a composition represented by the following formula (1). The catalyst having this elemental composition is particularly suitable as a catalyst for synthesizing methacrylic acid used when synthesizing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen.

Pα ₁ Moα ₂ Vα ₃ Cuα ₄ Xα ₅ Yα ₆ Zα ₇ Oα ₈ (1)
(Wherein P, Mo, V, Cu and O are element symbols indicating phosphorus, molybdenum, vanadium, copper and oxygen, respectively. X is at least selected from the group consisting of arsenic, tellurium, antimony, selenium and silicon. Y represents one element, Y represents at least one element selected from the group consisting of bismuth, zirconium, silver, iron, zinc, chromium, magnesium, cobalt, manganese, barium, cerium, and lanthanum, and Z represents potassium. And at least one element selected from the group consisting of rubidium and cesium, α1 to α8 represent the atomic ratio of each element, and when α2 = 12, α1 = 0.5 to 3, α3 = 0. 01-3, α4 = 0.01-2, α5 = 0.01-3, α6 = 0-3, α7 = 0.01-3, and α8 is necessary to satisfy the valence of each component. Acid It is an atomic ratio.)
When producing the unsaturated carboxylic acid synthesis catalyst of the present invention, preferably, first, a raw material solution containing each element constituting the catalyst so as to have a ratio represented by the above formula (1) is prepared. (Raw material liquid preparation step) Then, this is dried (drying step) to produce a catalyst precursor.

  The method of the raw material liquid preparation step is not particularly limited, but a method of preparing a raw material liquid in a slurry state by adding raw materials of each element to water and heating and stirring at 30 to 100 ° C. is preferable. As for the usage-amount of water, 200-1000 mass parts is preferable with respect to a total of 100 mass parts of the raw material of each element.

  As raw materials for each element, oxides, nitrates, carbonates, ammonium salts and the like of each element can be appropriately selected and used. For example, molybdic acid or molybdenum trioxide is preferable as a raw material of molybdenum, but ammonium paramolybdate or the like can also be used. As a raw material of phosphorus, orthophosphoric acid, phosphorus pentoxide, ammonium phosphate, etc. can be used. As a raw material of vanadium, ammonium metavanadate, divanadium pentoxide, or the like can be used. Moreover, copper nitrate, copper sulfate, copper carbonate, etc. can be used as a raw material of copper.

  When adjusting the pH of the raw material liquid, for example, nitric acid, sulfuric acid, aqueous ammonia, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and the like can be mixed so as to have a desired pH. The pH of the raw material liquid is preferably from 3.0 to 8.0, more preferably from 4.0 to 7.0.

  There is no particular limitation on the preparation scale of the raw material liquid, but a preferable raw material liquid is stably prepared when the amount of the main raw material such as molybdenum used is preferably 100 g to 10 t, more preferably 1 kg to 1 t. can do.

  There is no particular limitation on the method of the drying step of drying such a raw material liquid to obtain a catalyst precursor, and examples thereof include an evaporating and drying method, a spray drying method, a drum drying method, and an air current drying method. There is no restriction | limiting in particular in the kind of drying machine used for drying, a model, the temperature at the time of drying, atmosphere, etc. For example, the conditions etc. which dry at 100-180 degreeC by air atmosphere for 0.1 to 20 hours are mentioned. Since the physical properties such as fluidity and moldability of the catalyst precursor can be controlled by changing the drying conditions, it is preferable to set conditions according to the purpose.

  Subsequently, the catalyst for unsaturated carboxylic acid synthesis is manufactured by performing the baking process which bakes the catalyst precursor obtained by drying in this way at the maximum temperature of 300-700 degreeC. Prior to the firing step, a forming step for forming the catalyst precursor may be performed as necessary.

  There is no particular limitation on the method of the molding step at that time, and known dry and wet molding methods can be applied. Examples thereof include tableting molding, press molding, extrusion molding, granulation molding and the like. The shape of the molded product is not particularly limited, and examples thereof include a columnar shape, a ring shape, and a spherical shape. Further, at the time of molding, it is preferable to mold only the catalyst precursor without adding a carrier or the like to the catalyst precursor, but a known additive such as graphite or talc may be added if necessary.

  There is no restriction | limiting in particular in the atmosphere in a baking process, Usually, it bakes under oxygen containing gas circulation, such as air, or inert gas circulation. Here, the inert gas refers to a gas that does not decrease the catalytic activity, and examples thereof include nitrogen, carbon dioxide, helium, and argon.

  In performing the firing step, the firing container for the catalyst precursor is heated in advance. The temperature is the maximum value of the wall surface temperature of the portion in contact with the catalyst precursor in the firing container and is 100 ° C. or higher and lower than 300 ° C., but is preferably 180 ° C. or higher and lower than 250 ° C. Even if the temperature at the time of preheating the firing container is less than 100 ° C., there is no problem in the production of the catalyst, but the effect of shortening the firing time is small. When the temperature at which the firing container is heated in advance is 300 ° C. or higher, the activity of the catalyst decreases. The mechanism for reducing the catalyst activity is not always clear, but there is a possibility that the crystallinity of the catalyst increases when the catalyst precursor is heated rapidly.

  The rate of temperature rise when the catalyst precursor firing vessel is preheated is not particularly limited, but in principle, the faster the temperature rise rate, the higher the effect of shortening the firing time. However, depending on the temperature control mechanism, if the heating rate is too high, it may take time to stably control the firing container to the target heating temperature. It is desirable. When the catalyst is continuously produced a plurality of times in the same firing container, it is more preferable that the catalyst is continuously produced in a state where the temperature of the container is lowered to a temperature of 100 ° C. or higher and lower than 300 ° C.

  The highest firing temperature needs to be 300 ° C. or higher and 700 ° C. or lower, and more preferably 320 ° C. or higher and 450 ° C. or lower. The rate of temperature rise for shifting from the temperature at which the firing container is preheated to the maximum value of the firing temperature is preferably 0.1 ° C./hour or more and 100 ° C./hour or less, preferably 1 ° C./hour or more and 10 ° C. / Hour or less is more preferable. It is preferable to hold the temperature for 1 hour to 40 hours at the maximum firing temperature.

  When the unsaturated carboxylic acid synthesis catalyst thus produced is brought into contact with an unsaturated aldehyde such as methacrolein and a raw material gas containing molecular oxygen, the unsaturated aldehyde is oxidized in a gas phase by molecular oxygen, and the unsaturated aldehyde is oxidized. Saturated carboxylic acid (methacrylic acid when methacrolein is used) is obtained.

  Here, regarding the oxidation of the unsaturated aldehyde, the concentration of the unsaturated aldehyde in the raw material gas is not limited and can be set to any concentration, but 1 to 20% by volume is suitable, and 3 to 10% by volume is particularly preferable. 0.5-4 mol is preferable with respect to 1 mol of unsaturated aldehydes, and, as for the molecular oxygen concentration in source gas, More preferably, it is 1-3 mol. In addition, an inert gas such as nitrogen or carbon dioxide may be added to the raw material gas for dilution, or water vapor may be added. The reaction pressure is usually set within a range from normal pressure to several hundred kPa. The reaction temperature is usually set within the range of 230 to 450 ° C, and from the point of unsaturated carboxylic acid yield, 250 to 400 ° C is preferable.

  In the method for producing an unsaturated carboxylic acid synthesis catalyst described above, when the catalyst precursor is calcined, the calcining vessel is preheated to 100 ° C. or more and less than 300 ° C. Can be manufactured. When the firing container and the reaction container are the same, the production cost of the reactant can be further reduced by increasing the operational efficiency of the factory.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely regarding the oxidation of methacrolein, this invention is not limited to these Examples. Further, “parts” in the following examples and comparative examples are parts by mass.

The analysis of the raw material gas and the product was performed using gas chromatography. In addition, the reaction rate of methacrolein, the selectivity of the methacrylic acid to produce | generate, and a single flow yield are defined as follows.
Reaction rate of methacrolein (%) = (B / A) × 100
Methacrylic acid selectivity (%) = (C / B) × 100
Single stream 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]
(1) Raw material liquid preparation step (Preparation of liquid A)
To 200 parts of pure water, 100 parts of molybdenum trioxide, 6.67 parts of 85 mass% phosphoric acid aqueous solution, 3.39 parts of ammonium metavanadate, and 9.59 parts of 60 mass% arsenic acid aqueous solution were added, and the mixture was refluxed at 100 ° C. Liquid A was prepared by stirring for a period of time. The amount of ammonium contained in the A liquid was 0.5 mol with respect to 12 mol of molybdenum atoms contained in the A liquid.

(Preparation of liquid B)
Liquid B was prepared by dissolving 10.10 parts of cesium bicarbonate in 28.43 parts of pure water at 50 ° C.

(Preparation of liquid C)
The liquid C was 41.34 parts of 25% by mass aqueous ammonia. The amount of ammonium contained in the C liquid was 10.5 mol with respect to 12 mol of molybdenum atoms contained in the A liquid.

(Mixture of liquid A, liquid B, liquid C)
After cooling A liquid to 70 degreeC, B liquid was mixed with A liquid, stirring, and it stirred for 10 minutes, and prepared AB mixed liquid. Subsequently, C liquid was gradually added over 10 minutes to this AB mixed liquid, stirring AB mixed liquid. After mixing the liquid C, the mixture was stirred and held at 50 ° C. for 60 minutes to prepare an ABC liquid mixture.

  While stirring the thus-obtained ABC mixed liquid at a liquid temperature of 50 ° C., 2.10 parts of cupric nitrate and 0.47 part of ferric nitrate were added to 9.80 parts of pure water. A solution dissolved in was added to obtain a slurry. The pH of this slurry was measured and found to be 6.5.

(2) Drying Step This slurry was heated to 101 ° C., evaporated to dryness with stirring, and further dried at 130 ° C. for 16 hours to obtain a catalyst precursor.

(3) Molding step The obtained catalyst precursor was molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm with a tableting machine.

(4) Firing step A cylindrical quartz glass firing container having an inner diameter of 3 cm was heated in advance to 200 ° C., and a molded catalyst precursor was placed therein. Under an air flow, the temperature was increased at 60 ° C./hour for 3 hours, and the mixture was calcined at 380 ° C. for 5 hours to obtain a catalyst for producing methacrylic acid. The composition (other than oxygen) of the obtained catalyst is as follows.
P _1.0 Mo ₁₂ V _0.5 As _0.7 Cu _0.15 Fe _0.02 Cs _0.9
This catalyst was filled in a reaction tube, and methacrylic acid was produced by gas phase catalytic oxidation under the following conditions. The results are shown in Table 1.

(Reaction conditions)
Reaction gas: 5% by volume of methacrolein, 10% by volume of oxygen, 30% by volume of water vapor, 55% by volume of nitrogen Reaction temperature: 290 ° C.
Reaction pressure: 101 kPa
Contact time: 3.6 seconds [Example 2]
200 parts of pure water, 100 parts of molybdenum trioxide, 6.67 parts of 85 mass% phosphoric acid aqueous solution, 7.59 parts of 70.9 mass% vanadyl oxalate aqueous solution, 2.10 parts of cupric nitrate, ferric nitrate 0.47 parts and 3.70 parts of tellurium oxide were added, and an A-B-C mixture was prepared in the same manner as in Example 1 except that liquid A was prepared by stirring for 5 hours under reflux at 100 ° C. Then, a catalyst for methacrylic acid production was produced using the ABC mixed liquid (slurry) as a raw material liquid. In addition, it was 5.5 when the pH of the slurry containing a catalyst precursor was measured before the drying process. The composition (other than oxygen) of the obtained catalyst is as follows.
P _1.0 Mo ₁₂ V _0.5 Te _0.4 Cu _0.15 Fe _0.02 Cs _0.9
The catalyst was filled in a reaction tube, and methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Example 3]
200 parts of pure water, 100 parts of molybdenum trioxide, 6.67 parts of 85 mass% phosphoric acid aqueous solution, 7.59 parts of 70.9 mass% vanadyl oxalate aqueous solution, 2.10 parts of cupric nitrate, 2. 49 parts and 3.38 parts of antimony trioxide were added, and an A-B-C mixture was prepared in the same manner as in Example 1 except that A liquid was prepared by stirring for 5 hours under reflux at 100 ° C. The catalyst for methacrylic acid manufacture was manufactured using the ABC mixed liquid (slurry) as a raw material liquid. In addition, it was 6.4 when pH of the slurry containing a catalyst precursor was measured before the drying process. The composition (other than oxygen) of the obtained catalyst is as follows.
P _1.0 Mo ₁₂ V _0.5 Sb _0.4 Cu _0.15 Fe _0.02 Cs _0.9
The catalyst was filled in a reaction tube, and methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, (1) the raw material solution preparation step to (3) the molding step were carried out, and the molded catalyst precursor was put at room temperature (25 ° C.) without preheating the firing container in the firing step. Under an air flow, the temperature was increased at 60 ° C./hour for 6 hours, and calcined at 380 ° C. for 5 hours to obtain a catalyst. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
In Example 2, (1) the raw material liquid preparation step to (3) the molding step were performed, and the molded catalyst precursor was put at room temperature (25 ° C.) without heating the firing container in advance in the firing step. Under an air flow, the temperature was increased at 60 ° C./hour for 6 hours, and calcined at 380 ° C. for 5 hours to obtain a catalyst. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
In Example 3, (1) the raw material liquid preparation step to (3) the molding step were performed, and the molded catalyst precursor was put at room temperature (25 ° C.) without heating the firing container in advance in the firing step. Under an air flow, the temperature was increased at 60 ° C./hour for 6 hours, and calcined at 380 ° C. for 5 hours to obtain a catalyst. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
In Example 1, (1) the raw material liquid preparation step to (3) the molding step were carried out, and the calcining vessel was heated to 320 ° C. in advance in the calcining step, and the molded catalyst precursor was added. The catalyst was obtained by heating at 60 ° C./hour for 1 hour under air flow, raising the temperature at 380 ° C. for 5 hours. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
In Example 2, (1) the raw material solution preparation step to (3) the molding step were carried out, and the calcining vessel was heated to 320 ° C. in advance in the calcining step, and the molded catalyst precursor was added. The catalyst was obtained by heating at 60 ° C./hour for 1 hour under air flow, raising the temperature at 380 ° C. for 5 hours. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

[Comparative Example 6]
In Example 3, (1) the raw material solution preparation step to (3) the molding step were carried out, and the calcining vessel was heated to 320 ° C. in advance in the calcining step, and the molded catalyst precursor was added. The catalyst was obtained by heating at 60 ° C./hour for 1 hour under air flow, raising the temperature at 380 ° C. for 5 hours. Using this catalyst, methacrylic acid was produced by gas phase catalytic oxidation under the same conditions as in Example 1. The results are shown in Table 1.

  As shown in Table 1, when the catalyst for synthesizing methacrylic acid obtained in each example was used, methacrylic acid was obtained in a yield equivalent to that of Comparative Examples 1 to 3 having a long calcination time despite shortening the calcination time. I was able to manufacture it. On the other hand, in Comparative Examples 4 to 6 in which the temperature for preheating the baking container was too high, the methacrylic acid yield was lower than in Examples 1 to 3.

Claims (4)

  A method for producing an unsaturated carboxylic acid synthesis catalyst used for synthesizing an unsaturated carboxylic acid by vapor-phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen, wherein the catalyst precursor is preliminarily 100 ° C or higher and lower than 300 ° C. A method for producing an unsaturated carboxylic acid synthesis catalyst, comprising filling a calcining container heated to a temperature and calcining under a condition where the maximum temperature is 300 ° C. or higher and 700 ° C. or lower.   The unsaturated carboxylic acid according to claim 1, wherein a catalyst precursor obtained by preparing an aqueous slurry or an aqueous solution containing all catalyst raw materials and drying the raw material liquid whose pH is adjusted to 3.0 or more and 8.0 or less is used. A method for producing a catalyst for acid synthesis.   An unsaturated carboxylic acid synthesis catalyst produced by the production method according to claim 1.   A method for producing an unsaturated carboxylic acid, characterized in that an unsaturated aldehyde is subjected to gas phase catalytic oxidation with molecular oxygen using the unsaturated carboxylic acid synthesis catalyst according to claim 3.