JP3790080B2 - Catalyst for synthesizing methacrolein and methacrylic acid, and method for producing methacrolein and methacrylic acid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst for synthesizing methacrolein and methacrylic acid containing at least molybdenum and bismuth, and a method for producing methacrolein and methacrylic acid.
[0002]
[Prior art]
Isobutylene, tertiary butanol, methyl tertiary butyl ether and the like are used as raw materials for the synthesis method of methacrolein and methacrylic acid using a catalyst containing at least molybdenum and bismuth. In general, the methacrolein and methacrylic acid synthesis reaction using such raw materials is performed in a high-temperature gas phase using a fixed bed reactor. When using a fixed bed reactor, the catalyst is usually shaped to a certain size or more.
[0003]
Numerous proposals have been made regarding a method for producing a catalyst used for synthesizing methacrolein and methacrylic acid from isobutylene or tertiary butanol, particularly a molding method. For example, Japanese Patent Laid-Open No. 58-98143 discloses a method in which a nitrogen-containing organic compound is added to and mixed with the catalyst powder and then molded, and Japanese Patent Laid-Open No. 4-4048 has a method in which starch and the like are added to and mixed with the catalyst powder. In the method of molding, Japanese Patent Laid-Open No. 5-23596 discloses a method of adding a polymer organic compound having an average particle size of 0.01 to 10 μm to the catalyst powder and then molding, and in Japanese Patent Laid-Open No. 9-52053. In addition, a method is described in which silica sol and inorganic fibers are added to and mixed with catalyst powder and then molded.
[0004]
[Problems to be solved by the invention]
However, the catalysts obtained by these methods are still insufficient in terms of catalytic activity and target product selectivity as industrial catalysts, and further improvements are desired.
[0005]
Accordingly, an object of the present invention is to provide a catalyst for synthesizing methacrolein and methacrylic acid having excellent catalytic activity and selectivity for methacrolein and methacrylic acid, and a method for producing methacrolein and methacrylic acid using the catalyst. is there.
[0006]
[Means for Solving the Problems]
The present invention was obtained by pulverizing a primary molded product obtained by drying a mixed solution or an aqueous slurry containing at least molybdenum and bismuth and then primary-molding a powdery fired product obtained by firing the obtained dried product. It is a catalyst for synthesizing methacrolein and methacrylic acid produced by secondary molding of a pulverized product of a primary molded product. The present invention also provides a method for producing methacrolein and methacrylic acid, which uses the above-mentioned catalyst for synthesizing methacrolein and methacrylic acid.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The methacrolein and methacrylic acid synthesis catalyst of the present invention is not particularly limited as long as it is a composite oxide containing molybdenum and bismuth as essential components, preferably the following formula (1),
Mo _a Bi _b Fe _c A _d X _e Y _f Z _g O _h (1)
(Wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, A is nickel and / or cobalt, X is selected from the group consisting of magnesium, zinc, chromium, manganese, tin and lead) At least one element, Y is phosphorus, boron, sulfur, tellurium, silicon, germanium, cerium, niobium, titanium, zirconium, tungsten and antimony, Z is potassium, sodium Represents at least one element selected from the group consisting of rubidium, cesium and thallium, where a, b, c, d, e, f, g and h represent the atomic ratio of each element, and a = 12 When 0.1 ≦ b ≦ 5, 0.1 ≦ c ≦ 5, 1 ≦ d ≦ 12, 0 ≦ e ≦ 10, 0 ≦ f ≦ 10, 0.01 ≦ g ≦ In it, h is the atomic ratio of oxygen required to satisfy the valence of each element.)
It has a composition represented by these.
[0008]
In the production of a catalyst for synthesizing methacrolein and methacrylic acid, the method for obtaining a dried product is not particularly limited as long as it does not involve significant uneven distribution of components via a mixed solution or aqueous slurry containing at least molybdenum and bismuth. Various methods such as a coprecipitation method, an evaporation to dryness method, and an oxide mixing method, which are known from US Pat.
[0009]
The raw material used for the preparation of the mixed solution or aqueous slurry containing at least molybdenum and bismuth is not particularly limited, and it is possible to use a combination of nitrate, carbonate, acetate, ammonium salt, oxide, halide, etc. of each element. it can. For example, ammonium paramolybdate, molybdenum trioxide, molybdic acid, molybdenum chloride, etc. can be used as the molybdenum raw material.
[0010]
In the present invention, a method for drying a mixed solution or an aqueous slurry containing a catalyst component such as molybdenum is not particularly limited, and a general-purpose box-type dryer, spray dryer, drum dryer, slurry dryer, or the like can be used. In the present invention, the term “drying” means that the water content is reduced from the mixed solution or aqueous slurry to make it substantially solid, and the moisture content of the dried product obtained by drying is not particularly limited. Moreover, it does not specifically limit about the shape of the dried material immediately after drying, For example, powder shape, block shape, etc. are mentioned.
[0011]
In the present invention, the firing temperature when firing the dried product is not particularly limited, but is preferably in the range of 400 to 600 ° C. when not firing the secondary molded product, and 200 to 200 when firing the secondary molded product. 350 ° C. is preferred. Also, the firing time is not particularly limited, but if it is too short, a good catalyst cannot be obtained. Therefore, it is preferable to fire for at least one hour.
[0012]
In the present invention, since the powdered fired product needs to be primary-molded, if the dried product is not powdered or is not properly sized, it is pulverized appropriately. Equalize to powder. The method for making the powder is not particularly limited, and generally a general pulverization method using various pulverizers is applied. The size of the powdered fired product is not particularly limited as long as it does not hinder primary molding described later, but it is preferable that there is no size that cannot pass through a sieve having a nominal size of 1 mm. Here, the nominal dimension refers to the length of one side of the mesh of the sieve.
[0013]
The method for primary molding of the powdered fired product thus obtained is not particularly limited as long as it is a method for obtaining a molded product from the powdered material. For example, various methods such as tableting molding, extrusion molding, granulation, etc. The molding method can be applied. Further, at the time of molding, for the purpose of controlling the specific surface area, pore volume and pore distribution of the molded product with good reproducibility and increasing mechanical strength, for example, inorganic salts such as barium sulfate and ammonium nitrate, Conventionally known additives such as lubricants such as graphite, organic substances such as celluloses, starch, polyvinyl alcohol and stearic acid, hydroxide sols such as silica sol and alumina sol, whiskers, glass fibers, and inorganic fibers such as carbon fibers are calcined. You may add suitably with respect to a thing. In addition, the shape of a primary molded product is not specifically limited, For example, arbitrary shapes, such as spherical shape, column shape, ring shape (cylindrical shape), plate shape, are mentioned. Although the magnitude | size of a primary molded product is not specifically limited, The magnitude | size which cannot pass the sieve of a nominal dimension 2mm is preferable.
[0014]
In the present invention, the method for pulverizing the primary molded product is not particularly limited, but generally, general pulverization methods using various pulverizers are applied. The size of the pulverized product of the primary molded product is not particularly limited as long as there is no hindrance to the secondary molding described later, but a size that does not pass through a sieve having a nominal size of 2 mm is preferable.
[0015]
In the present invention, it is important to secondary-mold at least the pulverized product of the primary molded product, and secondary molding is performed by mixing the pulverized product of the primary molded product with the powdered fired product. Is preferred.
[0016]
A sieve having a nominal size of 1 mm is used for a pulverized product of a primary molded product to be secondarily formed, and a pulverized product of at least a primary molded product such as a mixture of a pulverized product of a primary molded product and a powdered fired product. It is preferable that 5% by mass or more of the pulverized product having a size that cannot pass through the resin is contained, and it is particularly preferable that 10% by mass or more is contained.
[0017]
By subjecting the pulverized product of the primary molded product to secondary molding, a preferable pore structure is expressed in the final catalyst, and a catalyst having excellent catalytic activity and selectivity for methacrolein and methacrylic acid can be obtained. When the powdered fired product is mixed with the pulverized product of the primary molded product, the ratio of the pulverized product of the primary molded product in the mixture is preferably 10% by mass or more, and particularly preferably 20% by mass or more.
[0018]
The method of secondary molding is not particularly limited, and various molding methods can be applied as in the primary molding, but the same molding method as the primary molding method is preferable. Moreover, you may mix and shape | mold an additive similarly to the case of primary shaping | molding. The shape of the secondary molded product is not particularly limited, but the same shape as the primary molded product is preferable.
[0019]
The obtained secondary molded article is preferably fired at a temperature in the range of 400 to 600 ° C. The calcination time is not particularly limited, but if it is too short, a good catalyst may not be obtained.
[0020]
The reaction conditions for producing methacrolein and methacrylic acid using the catalyst thus obtained vary depending on the reaction raw materials and reaction methods used, but cannot be generally stated, but conventionally known reaction conditions are It can be applied as it is. Examples of the reaction raw material used include isobutylene, tertiary butanol, and methyl tertiary butyl ether.
[0021]
For example, the reaction conditions for producing methacrolein and methacrylic acid by charging the catalyst for synthesizing methacrolein and methacrylic acid of the present invention into a fixed bed reactor and subjecting isobutylene to gas phase catalytic oxidation with molecular oxygen are as follows. It is. The concentration of isobutylene in the raw material gas is usually 1 to 20% by volume, preferably 3 to 10% by volume. Although it is industrially advantageous to use air as the molecular oxygen source, air enriched with pure oxygen can also be used if necessary. The amount of oxygen in the raw material gas is preferably 0.5 to 3 mol with respect to 1 mol of isobutylene. The source gas is preferably diluted with an inert gas, water vapor or the like. The reaction pressure is normal to several atmospheres. The reaction temperature is preferably in the range of 300 to 450 ° C.
[0022]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples. “Parts” in Examples and Comparative Examples means parts by mass. Analysis of reaction products and the like was performed using gas chromatography. Moreover, the reaction rate of isobutylene, the selectivity of the produced methacrolein and methacrylic acid, and the yield were calculated by the following equations.
Reaction rate of isobutylene (%) = B / A × 100
Selectivity of methacrolein (%) = C / B × 100
Methacrylic acid selectivity (%) = D / B × 100
Yield of methacrolein and methacrylic acid (%) = (C + D) / A × 100
Here, A is the number of moles of isobutylene supplied, B is the number of moles of reacted isobutylene, C is the number of moles of methacrolein produced, and D is the number of moles of methacrylic acid produced.
[0023]
[Example 1]
To 1000 parts of water, 500 parts of ammonium paramolybdate, 18.5 parts of ammonium paratungstate, 18.4 parts of cesium nitrate and 354.5 parts of 20% by mass silica sol were added and heated and stirred (liquid A). Separately, 250 parts of 60% by mass nitric acid was added to 850 parts of water to make it uniform, and then 57.2 parts of bismuth nitrate was added and dissolved. To this, 238.4 parts of ferric nitrate, 4.7 parts of chromium nitrate, 411.8 parts of nickel nitrate and 60.5 parts of magnesium nitrate were sequentially added and dissolved (solution B). After liquid B was added to liquid A to form a slurry, 34.4 parts of antimony trioxide was added and stirred with heating to evaporate most of the water.
[0024]
The obtained cake-like product was dried at 120 ° C. and then baked at 500 ° C. for 6 hours. Subsequently, the cake-like product was powdered using a drag mill so that there was no size that could not pass through a sieve having a nominal size of 1 mm. A powdery fired product was obtained.
[0025]
A part of the obtained powdered fired product was set aside for use in secondary molding, and after adding 2 parts of graphite to 100 parts of the remaining powdered fired product, the outer diameter was measured by a tableting machine. Primary molding was performed in a ring shape of 5 mm, an inner diameter of 2 mm, and a length of 5 mm. The obtained primary molded product was pulverized using a jaw crusher so that there was no size that could not pass through a sieve having a nominal size of 2 mm.
[0026]
40 parts of the pulverized product of the primary molded product thus obtained and 60 parts of the powdered fired product that had been set aside were mixed to obtain a mixture for secondary molding. The proportion of the pulverized product of the primary molded product that did not pass through a sieve having a nominal size of 1 mm in this mixture was 21% by mass.
[0027]
After adding 1 part of graphite to 100 parts of this mixture, it was secondarily formed into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 5 mm by a tableting machine, and methacrolein and a catalyst for synthesizing methacrylic acid. Obtained. The composition of elements other than oxygen in the obtained catalyst was Mo ₁₂ Bi _0.5 Fe _2.5 Ni ₆ Mg ₁ Cr _0.05 W _0.3 Sb ₁ Si ₅ Cs _0.4 .
[0028]
This catalyst was charged into a fixed bed reaction tube, and a raw material gas consisting of 5% by volume of isobutylene, 12% by volume of oxygen, 10% by volume of water vapor and 73% by volume of nitrogen was passed at a reaction temperature of 360 ° C. and a contact time of 3.6 seconds. When methacrolein and methacrylic acid were produced, the reaction rate of isobutylene was 96.3%, the selectivity of methacrolein was 86.9%, the selectivity of methacrylic acid was 5.2%, and the yield of methacrolein and methacrylic acid was 88.7. %Met.
[0029]
[Example 2]
As a result of carrying out in the same manner as in Example 1 except that 3 parts of the pulverized product of the primary molded product and 97 parts of the powdered fired product were mixed to obtain a mixture for secondary molding, the reaction rate of isobutylene was 96. The selectivity of methacrolein was 86.8%, the selectivity of methacrylic acid was 5.1%, and the yield of methacrolein and methacrylic acid was 88.3%. At this time, the ratio of the pulverized product of the primary molded product that cannot pass through a sieve having a nominal size of 1 mm in the mixture for secondary molding was 2% by mass.
[0030]
[Comparative Example 1]
As a result of carrying out in the same manner as in Example 1 except that the primary molded product was used for the production of methacrolein and methacrylic acid as a catalyst for synthesizing methacrolein and methacrylic acid without performing secondary molding, the reaction rate of isobutylene was 96.0%. The selectivity of methacrolein was 86.7%, the selectivity of methacrylic acid was 5.0%, and the yield of methacrolein and methacrylic acid was 88.0%.
[0031]
[Example 3]
To 1000 parts of water, 500 parts of ammonium paramolybdate, 18.5 parts of ammonium paratungstate, 27.5 parts of antimony trioxide, 14.3 parts of potassium nitrate and 496.3 parts of 20% by mass silica sol were added and stirred with heating (Liquid C). ). Separately, 250 parts of 60% by mass nitric acid was added to 850 parts of water to make it uniform, and then 57.2 parts of bismuth nitrate was added and dissolved. To this, 228.8 parts of ferric nitrate, 480.7 parts of cobalt nitrate and 70.2 parts of zinc nitrate were sequentially added and dissolved (solution D). Liquid D was added to liquid C to obtain a slurry.
[0032]
The obtained slurry was dried by a co-current type spray dryer under the conditions of a dryer inlet temperature of 400 ° C. and a slurry spray rotating disk of 20000 rpm. The obtained dried product was fired at 300 ° C. using a rotary kiln to obtain a powdery fired product. In addition, the particle diameter of this powdery baked product was in the range of 1 to 200 μm.
[0033]
A part of the obtained powdery fired product is set aside for use in secondary molding, and after adding 3 parts of glass fiber to 100 parts of the remaining powdery fired product, the tableting machine is used to Primary molding was performed in a ring shape having a diameter of 5 mm, an inner diameter of 2 mm, and a length of 3 mm. The primary molded product thus obtained was pulverized using a jaw crusher so that there was no size that could not pass through a sieve having a nominal size of 2 mm.
[0034]
60 parts of the pulverized product of the primary molded product thus obtained and 40 parts of the powdered fired product that had been set aside were mixed to obtain a mixture for secondary molding. The ratio of the pulverized product of the primary molded product that does not pass through a sieve having a nominal size of 1 mm in this mixture was 31% by mass.
[0035]
This mixture was secondarily molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a length of 3 mm using a tableting machine to obtain a secondary molded product. The secondary molded product was calcined at 500 ° C. for 5 hours under air flow to obtain methacrolein and a catalyst for synthesizing methacrylic acid. The composition of elements other than oxygen in this catalyst was Mo ₁₂ Bi _0.5 Fe _2.4 Co ₇ Zn ₁ Cr _0.05 Sb _0.8 Si ₇ W _0.3 K _0.6 .
[0036]
When this catalyst was packed in a fixed bed reaction tube and methacrolein and methacrylic acid were produced under the same reaction conditions as in Example 1, the reaction rate of isobutylene was 97.2%, the selectivity of methacrolein was 87.6%, methacrylic acid The selectivity for methacrolein and methacrylic acid was 89.0%.
[0037]
[Comparative Example 2]
As a result of carrying out in the same manner as in Example 3 except that the primary molded product was calcined without performing secondary molding, the reaction rate of isobutylene was 96.6%, the selectivity of methacrolein was 87.3%, and the selectivity of methacrylic acid was 3. The yield of methacrolein and methacrylic acid was 88.0%.
[0038]
[Example 4]
A powdery fired product was obtained in the same manner as in Example 3. A part of the obtained powdered fired product is set aside for use in secondary molding, and 3 parts of methylcellulose and 30 parts of water are added to 100 parts of the remaining powdered fired product, followed by kneading. Subsequently, it was molded into a ring shape having an outer diameter of 6 mm, an inner diameter of 3 mm, and a length of 5 mm by a piston type extrusion molding machine, and this was dried at 105 ° C. for 2 hours by a dryer to obtain a primary molded product. The primary molded product thus obtained was pulverized using a jaw crusher so that there was no size that could not pass through a sieve having a nominal size of 2 mm.
[0039]
25 parts of the pulverized product of the primary molded product thus obtained and 75 parts of the powdered fired product that had been set aside were mixed to obtain a mixture for secondary molding. The ratio of the pulverized product of the primary molded product that does not pass through a sieve having a nominal size of 1 mm in this mixture was 11% by mass.
[0040]
After adding 3 parts of methylcellulose and 30 parts of water to 100 parts of this mixture, kneading is carried out, followed by molding into a ring shape having an outer diameter of 6 mm, an inner diameter of 3 mm, and a length of 5 mm by a piston type extruder. This was dried in a dryer at 105 ° C. for 2 hours to obtain a secondary molded product. This secondary molded product was calcined at 500 ° C. for 5 hours under air flow to obtain methacrolein and a catalyst for synthesizing methacrylic acid. The composition of elements other than oxygen in this catalyst was Mo ₁₂ Bi _0.5 Fe _2.4 Co ₇ Zn ₁ Cr _0.05 Sb _0.8 Si ₇ W _0.3 K _0.6 .
[0041]
When this catalyst was packed in a fixed bed reaction tube and methacrolein and methacrylic acid were produced under the same reaction conditions as in Example 1, the reaction rate of isobutylene was 97.1%, the selectivity of methacrolein was 87.6%, methacrylic acid The selectivity was 4.1% for methacrolein and the yield of methacrylic acid was 89.0%.
[0042]
【The invention's effect】
The catalyst for synthesizing methacrolein and methacrylic acid of the present invention is excellent in catalytic activity and selectivity of methacrolein and methacrylic acid, and by using this catalyst, methacrolein and methacrylic acid can be produced with high yield. .

Claims (6)

  A primary molded product obtained by drying a mixed solution or aqueous slurry containing at least molybdenum and bismuth, and then firing the resulting dried product to obtain a primary product (however, the performance deteriorates when used in the reaction) And the catalyst for synthesizing methacrolein and methacrylic acid produced by secondary molding of the pulverized product of the obtained primary molded product.   Secondary molding is performed by mixing a pulverized product of a primary product with a mixed solution or aqueous slurry containing at least molybdenum and bismuth, and then mixing the powdered fired product obtained by firing the resulting dried product. The catalyst for synthesizing methacrolein and methacrylic acid according to claim 1.   The catalyst for synthesizing methacrolein and methacrylic acid according to claim 1 or 2, characterized in that the secondary molded product is calcined at a temperature in the range of 400 to 600 ° C.   4. The methacrolein and methacrylic acid composition according to claim 1, wherein a secondary molded product containing 5% by mass or more of a pulverized product of a primary molded product having a size not passing through a sieve having a nominal size of 1 mm is contained. Catalyst. The catalyst for synthesizing methacrolein and methacrylic acid according to claim 1, wherein the catalyst for synthesizing methacrolein and methacrylic acid is a composite oxide having a composition represented by the following formula (1).
_{Mo a Bi b Fe c A d} X e Y f Z g O h (1)
(Wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, A is nickel and / or cobalt, X is selected from the group consisting of magnesium, zinc, chromium, manganese, tin and lead) At least one element, Y is phosphorus, boron, sulfur, tellurium, silicon, germanium, cerium, niobium, titanium, zirconium, tungsten and antimony, and Z is potassium, sodium Represents at least one element selected from the group consisting of rubidium, cesium and thallium, wherein a, b, c, d, e, f, g and h represent the atomic ratio of each element, and a = 12 In this case, 0.1 ≦ b ≦ 5, 0.1 ≦ c ≦ 5, 1 ≦ d ≦ 12, 0 ≦ e ≦ 10, 0 ≦ f ≦ 10, 0.01 ≦ g ≦ In it, h is the atomic ratio of oxygen required to satisfy the valence of each element.)   A method for producing methacrolein and methacrylic acid, wherein the catalyst for synthesizing methacrolein and methacrylic acid according to claim 1 is used.