JP2994706B2 - Catalyst for producing methacrylic acid and method for producing methacrylic acid using the catalyst - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a catalyst for producing methacrylic acid and a method for producing methacrylic acid using the catalyst, and more particularly to methacrolein, isobutyraldehyde, isobutyric acid or a mixture thereof. To produce methacrylic acid from gas-phase catalytic oxidation reaction or gas-phase catalytic oxidative dehydrogenation reaction, or to produce methacrylic acid by oxidizing a methacrolein-containing mixed gas obtained by oxidizing isobutylene or the like as a starting material. And a method for producing methacrylic acid using the catalyst.

(Prior Art) Various improved catalysts have been proposed for efficiently producing methacrylic acid by a gas phase catalytic oxidation reaction of methacrolein or the like. These improvements mainly relate to the selection of the components constituting the catalyst and the ratio thereof, and some of them relate to the specification of the properties of the catalyst and the method for preparing the catalyst.

Although there have been some proposals regarding the physical properties of the catalyst, such as the specific surface area, pore volume, and pore diameter of the catalyst itself, the resulting catalyst is insufficient in terms of its performance and has been found to be still at a satisfactory level. Not.

For example, JP-A-49-116022 and JP-A-50-37
No. 710, the catalyst specific surface area is 0.01 to ⁵ m ² , respectively.
/ range of g and 0.01 to 50 m ² / g are described as preferable. However, even with a catalyst whose specific surface area is specified in the above range,
The reaction temperature is high, or the selectivity for methacrylic acid is low, and this is not always industrially satisfactory.

Regarding specific surface area and pore volume,
No. -13876 discloses that the specific surface area is 4 to ²⁰ m ² / g, the pore volume is 0.08 to 0.5 ml / g, phosphorus, molybdenum and X (where X is thallium, Periodic Tables IA and II). There is disclosed a method of forming a catalyst having, as an essential component, at least one metal selected from metals) by a tumbling granulator. However, as can be seen from the contents of this publication, the reaction temperature is high and is not satisfactory as an industrial catalyst.

On the other hand, regarding the catalyst preparation method, especially in the case of a molded catalyst,
Since there is a problem that the strength is not sufficiently high and the wear resistance is poor, a supported catalyst has been proposed to solve these problems. For example, JP-A-52-153889, JP-A-53-50116, JP-A-57-32734 and JP-A-57-32734
JP-A-56-37050, JP-A-60-48143 and JP-A-60-48143
JP 59-12758 A discloses such a supported catalyst. However, these publications disclose, as a method for supporting a catalytically active substance, a method in which a precursor thereof is calcined in advance, pulverized and then supported, and a method for specifying physical properties of a carrier or a method for preparing a drug solution. It is only disclosed.

A gas phase catalytic oxidation reaction or a gas phase catalytic oxidative dehydrogenation reaction of methacrolein, isobutyraldehyde or isobutyric acid, or a mixture of two or more thereof, is an exothermic reaction having a remarkably large calorific value. Large heat storage in the active material layer. In particular, in a local abnormal high-temperature portion called a hot spot, not only the yield is reduced due to an excessive oxidation reaction, but also the catalyst life is shortened due to deterioration of the catalyst due to heat load. Therefore, it is desirable to reduce the heat storage in the catalytically active material layer and suppress the sequential reaction of the generated methacrylic acid in order to produce methacrylic acid with high yield and high selectivity. For this purpose, it is necessary to make the catalytically active substance layer thinner.However, the catalytically active substance layer is made inactive by the impregnation-supporting method or the immersion-supporting method that has been used in the conventional preparation of a catalyst for methacrylic acid production. There is a problem that it is difficult to form it on a carrier, or that it is easily peeled off even if it is formed.

Further, as a catalyst for producing methacrylic acid, in the case of its industrial implementation, the catalyst strength and the like become problematic, and a catalyst excellent in abrasion resistance, exfoliation resistance and the like is desirable. However, it is difficult to form a strong catalytically active substance layer by the conventional impregnation-supporting method or immersion-supporting method, and no industrially satisfactory catalyst for producing methacrylic acid has been obtained.

Therefore, the present inventors have conducted various studies to solve the above problems, and as a result, when a specific catalytically active substance is supported on an inert carrier by a baking support method, a strong catalytically active substance layer is formed, and the catalyst strength is excellent. It is possible to form a catalytically active material layer having a specific surface area, pore volume and pore diameter distribution in a specific range according to this loading method,
They have found that a highly active and highly selective catalyst can be prepared with good reproducibility, and have already filed a patent application (Japanese Patent Application No. 1-220380).
Specification).

On the other hand, isobutylene, tert-butanol and methyl
A reaction for producing methacrolein by gas-phase catalytic oxidation of at least one starting compound selected from tert-butyl ether (first-stage reaction) and a reaction for producing methacrylic acid by directly oxidizing this methacrolein-containing mixed gas (second-stage reaction) Reaction) (hereinafter referred to as a “continuous process”), the methacrylic acid production catalyst used in the subsequent reaction is a gas from the preceding reaction (hereinafter, referred to as “continuous process”).
It is known that the activity is suppressed by unreacted raw materials and high-boiling by-products (hereinafter, these are collectively referred to as “impurities”) in the “pre-stage reaction outlet gas”.

Therefore, the catalyst for producing methacrylic acid used for industrial production of methacrylic acid not only exhibits excellent catalytic performance with high activity and high selectivity, but also becomes active due to impurities in the pre-stage reaction outlet gas in the continuous process. Those that are less likely to be suppressed are desirable.

(Problems to be Solved by the Invention) One object of the present invention is to provide a catalyst for producing methacrylic acid which produces methacrylic acid with high yield and high selectivity.

Another object of the present invention is to provide a catalyst for producing methacrylic acid, which exhibits excellent catalytic activity such as high activity and high selectivity even when used in the latter stage reaction of the continuous process, even when the activity in the former stage reaction outlet gas is small. It is to provide.

Another object of the present invention is to provide a catalyst for producing methacrylic acid in which the heat storage in the methacrylic acid production reaction is reduced, the sequential reaction of the produced methacrylic acid is suppressed, and deterioration due to heat load is prevented.

Another object of the present invention is to provide a catalyst for producing methacrylic acid which has excellent mechanical strength such as abrasion resistance and peeling resistance and is suitable for industrial practice.

Another object of the present invention is to provide a method for efficiently producing methacrylic acid using the above catalyst for producing methacrylic acid.

(Means for Solving the Problems) According to the study of the present inventors, when a catalyst for producing methacrylic acid is produced by forming a catalytically active substance layer on an inert carrier, two or more kinds of catalysts having different compositions are previously determined. A catalyst solution or slurry is prepared, these are successively supported on an inert carrier, and if necessary, this operation is repeated to form a multilayered catalytically active substance layer, thereby optimizing the activity and selectivity of the catalyst. At the same time, it has been found that a catalyst excellent in durability can be obtained even if it is used in the latter stage reaction of the continuous process and is less affected by impurities in the outlet gas of the former stage reaction.

That is, one aspect of the present invention is a catalyst for producing methacrylic acid comprising an inert carrier and a catalytically active substance layer supported on the carrier, wherein the catalytically active substance layer has the following formula (1): Mo _{a P b a c B d C e} D f O x (1) ( wherein, Mo is molybdenum, at least one element P is phosphorus, a is selected arsenic, antimony, germanium, bismuth, zirconium, cerium and selenium ,
B is copper, iron, chromium, nickel, manganese, cobalt,
At least one element selected from tin, silver, zinc, palladium, rhodium and tellurium; C is at least one element selected from vanadium, tungsten and niobium; D is selected from alkali metals, alkaline earth metals and thallium At least one element, O represents oxygen, a, b, c, d, e, f and x are each Mo,
Represents the atomic ratio of P, A, B, C, D and O. When a = 12, b = 0.5-4, c = 0-5, d = 0-3, e = 0
-4, f = 0.01-4, and x is a numerical value determined by the oxidation state of each element). A compound containing each elemental component of the oxide represented by (1) is mixed, and further heated, if necessary, to prepare two or more slurries or solutions having different compositions. The present invention relates to a catalyst for producing methacrylic acid, which is formed by spraying the active carrier sequentially and, if necessary, repeating this operation.

Another object of the present invention is to provide a catalyst for producing methacrylic acid, wherein the catalyst for producing methacrylic acid is brought into contact with a raw material gas comprising one or more selected from methacrolein, isobutyraldehyde and isobutyric acid to oxidize the catalyst. It is to provide a manufacturing method.

Another object of the present invention is to provide a method for producing methacrylic acid, which comprises oxidizing a methacrylic acid-producing catalyst by contacting the mixed gas with methacrolein.

 Hereinafter, the present invention will be described in detail.

The catalyst for producing methacrylic acid of the present invention comprises an inert carrier and a multi-layered catalytically active substance layer supported on the carrier. As the inert carrier, silicon carbide, silica, α
-Alumina, silica-alumina, titania, and other commonly used known materials such as refractories can be used. The shape of the inert carrier is not particularly limited, and may be any of a sphere, a pellet, and a ring. In particular, a spherical carrier having a diameter of about 3 to 10 mm,
A pellet-shaped carrier or a ring-shaped carrier having a length of about 10 to 10 mm and a length of about 0.3 to 1.7 times the outer diameter is suitably used.

The catalyst active material layer is made of the oxide represented by the formula (1). This catalytically active substance layer is composed of the elemental components of the oxide of the formula (1), Mo, P, A,
A compound containing B, C, or D is mixed, and further heated, if necessary, to prepare a slurry or a solution. The slurry or the solution is sprayed on an inert carrier, and then dried,
It is formed by firing (in the present invention,
This method of forming the catalytically active material layer is referred to as “baking-supporting method”).

The compound containing each of the above-mentioned elemental components as a starting material for the catalyst is not particularly limited, and any oxide containing each elemental component or a compound which generates an oxide upon firing can be used. Compounds that generate oxides by firing include, for example, hydroxides, metal acids,
Nitrate, carbonate, ammonium salt, acetate, formate and the like can be mentioned.

For example, specific examples of the molybdenum-containing compound include molybdenum trioxide, ammonium paramolybdate, molybdic acid, phosphomolybdic acid, and phosphovanadium molybdate. Specific examples of the phosphorus-containing compound include orthophosphoric acid, metaphosphoric acid, phosphorous acid, primary ammonium phosphate, and secondary ammonium phosphate.

In addition, a compound containing two or more of the above elemental components can also be used.

According to the baking-supporting method of the present invention, first, a compound containing each of the above-mentioned elemental components is added to a medium, mixed, and further heated, if necessary, to prepare a slurry or a solution. As the medium, water is usually used, but organic solvents such as alcohol and acetone can also be used.

The slurry or solution has a specific surface area, a pore volume and a pore size distribution of the catalytically active substance layer, in order to control the reproducibility, or ammonium nitrate as a powder binder,
Cellulose, starch, polyvinyl alcohol, stearic acid, and the like may be added, and whiskers and glass fibers may be added to reduce the degree of powdering of the catalyst.

The slurry or solution can be used as it is, but once the slurry or solution is concentrated and dried, the powder obtained by drying, calcining and pulverizing is used by dispersing or dissolving it in water again. You can also.

The solid content of the starting material of the catalyst or the like in the slurry or the solution is usually 50 to 500 g /.

According to the baking-supporting method of the present invention, the slurry or the solution is sprayed on an inert carrier to form a layer. This layer is preferably formed, for example, in a rotary furnace that can be heated from the outside. That is, 100-400 ° C., preferably 100-250
Put the inert carrier in a rotary furnace maintained at ℃, preheat the inert carrier to this temperature, then spray the slurry onto the inert carrier by means such as a sprayer while rotating the rotary furnace to have a uniform thickness Form a layer.

According to the present invention, two or more kinds of slurries or solutions having different compositions are prepared in advance, and these are sequentially sprayed, then dried and fired to form multiple layers of the catalytically active substance. The catalytically active substance layer is composed of a plurality of oxide layers having different compositions.

The term "different in composition" in the present invention includes not only different constituent element components but also different constituent element components but different atomic ratios.

In the catalyst active material layer having the multilayer structure, a layer having a composition that is excellent in terms of catalytic performance but is easily affected by impurities is supported on the inside, and conversely, the adsorptivity of impurities is weak,
A layer having a composition in which the oxidation performance of methacrolein is hardly suppressed by the adsorption of impurities is preferably supported on the surface layer side. This can minimize the influence of impurities in the pre-reaction outlet gas, particularly when used in the post-reaction of a continuous process.

Therefore, the catalyst for producing methacrylic acid having a catalytically active substance layer having a multilayer structure according to the present invention is a methacrylic acid-containing mixed gas containing impurities compared to the catalyst for producing methacrylic acid having a catalytically active substance layer having a single layer structure. Since it exhibits excellent performance in the oxidation of, it can be effectively used especially as a catalyst used in the subsequent reaction of a continuous process.

In addition, all the layers constituting the catalytically active material layer having a multilayer structure in the present invention do not need to have different compositions, and in order to more effectively achieve the above object, or to optimize the catalytic performance, The operation of sequentially spraying two or more kinds of slurries or solutions having different compositions may be repeated once or more times so that a plurality of layers having the same composition may be present.

According to the baking support method of the present invention, finally, after drying the support layer, if necessary, 200 ~ 600 ℃, preferably
By baking at 300 to 500 ° C. in an air stream or a nitrogen stream, a multi-layered catalytically active material layer composed of the oxide represented by the formula (1) is formed.

The drying and baking may be performed for each layer, but may be performed after all the layers are sprayed and formed.

The amount of the catalytically active substance carried on the inert carrier after the calcination is usually 5 to 100 g per 100 ml of the carrier, particularly 10 to 50 g.
Is suitable. If it is less than 5 g, the catalytically active substance layer is too thin and the catalytic activity decreases, while if it is more than 100 g, the catalytically active substance layer becomes too thick to achieve the desired thinning of the present invention.

Among the catalysts for producing methacrylic acid obtained as described above, a catalyst having a specific surface area, a pore volume and a pore diameter distribution of the catalytically active substance layer in the following specific ranges is particularly suitable.

Specific surface area = 1-20 m ² / g Pore volume = 0.1-1 ml / g Pore size distribution = 1-20 μm pores 20-70% 0.5-1 μm pores 20% or less 0.1-0.5 μm The specific surface area of the catalytically active substance layer in the present invention is determined by using a fully automatic surface area measuring device 4-sorb (Yuasa Ionics Co., Ltd.)
And it is 1 to 20 m ² / g, preferably 3 to 15 m ² / g. When the specific surface area is less than 1 m ² / g, the catalytic activity is too low. On the other hand, when the specific surface area exceeds 20 m ² / g, the selectivity of methacrylic acid decreases, which is not preferable.

The pore volume is measured using a mercury intrusion porosimeter (autopore
9200, manufactured by Shimadzu Corporation) and is 0.1 to 1 ml / g, preferably 0.2 to 0.8 ml / g. If the pore volume is less than 0.1 ml / g, the catalytic activity is too low, while 1 ml / g
If it exceeds, not only is the selectivity of methacrylic acid lowered, but also in terms of mechanical strength such as abrasion resistance and peeling resistance, it is not preferable.

The pore size distribution was determined using the same mercury intrusion porosimeter as used in the measurement of the pore volume. 1 to 10 μm
The volume occupied by pores having a pore diameter in the range of 20 to 70%, preferably 25 to 50% of the total pore volume, and 0.5 to 1 μm
The volume occupied by pores having a pore diameter in a range of less than m is 20% or less of the total pore volume, preferably 15% or less, and
The volume occupied by pores having a pore diameter in the range of less than 0.1 to 0.5 μm is 20 to 70%, preferably 40 to 65% of the total pore volume.

Usually, the pores having a small pore diameter have a large contribution to the specific surface area and the pore volume, but it is not sufficient to merely increase the proportion of the pores having a small pore diameter from the viewpoint of the activity and selectivity of methacrylic acid production. In addition, the coexistence of pores having a relatively large diameter of 1 to 10 μm also improves the catalyst performance.

That is, by simultaneously adjusting the specific surface area, the pore volume, and the pore size distribution of the catalytically active substance layer to the above specific ranges, the object of the present invention can be more effectively achieved.

According to the baking support method of the present invention, a catalytically active substance layer having such specific ranges of specific surface area, pore volume and pore diameter distribution can be easily formed. further,
According to the baking-supporting method of the present invention, since a catalytically active substance layer having a specific surface area, a pore volume, and a pore size distribution in such a specific range can be formed with good reproducibility, it is possible to produce a catalyst having uniform performance. Become.

When using the catalyst for producing methacrylic acid of the present invention to produce methacrylic acid by vapor-phase oxidation of methacrolein, isobutyraldehyde or isobutyric acid, or a mixture thereof, the apparatus, conditions, and the like for performing the method are particularly limited. There is no. That is, regarding the reaction conditions,
The reaction can be carried out under conditions generally used for producing methacrylic acid by gas phase catalytic oxidation or gas phase catalytic oxidative dehydrogenation.

For example, 1 to 10% by volume of a raw material compound such as methacrolein, isobutyraldehyde or isobutyric acid, molecular oxygen in a range of 1 to 10 times in volume ratio to this raw material compound,
And a mixed gas comprising an inert gas as a diluent, for example, nitrogen, carbon dioxide gas, and steam (particularly, the use of steam suppresses the formation of by-products and is advantageous in improving the yield of the target product). The catalyst for producing methacrylic acid of the present invention may be brought into contact with the catalyst for producing methacrylic acid of the present invention at a space velocity of 100 to 5,000 hr ^-1 (STP) under a pressure of normal pressure to 10 atm in a temperature range of ~ 400 ° C.

In addition, when using methacrolein as a raw material compound, methacrolein does not necessarily need to be pure,
A methacrolein-containing mixed gas obtained by catalytically reacting isobutylene or tert-butanol can also be used. The use of such a gas mixture containing methacrolein is particularly recommended in industrial processes.

In particular, when the catalyst for producing methacrylic acid of the present invention is used in a subsequent reaction of a continuous process, it is less affected by impurities in a gas at the outlet of the former reaction, and thus is suitable as a catalyst used in the latter reaction of the continuous process. is there.

(Effect of the Invention) As described above, the catalyst for producing methacrylic acid of the present invention has a high activity since a catalyst active material layer having a specific composition and a multilayer structure having a specific composition is formed on an inert carrier by a baking support method. Methacrylic acid can be produced with high yield and high selectivity. In particular, by simultaneously adjusting the specific surface area, the pore volume, and the pore size distribution of the catalytically active substance layer to specific ranges, methacrylic acid can be produced with higher yield and higher selectivity.

In the catalyst for producing methacrylic acid of the present invention, the catalytically active substance layer has a multilayer structure composed of a plurality of oxide layers having different compositions, and is excellent in catalytic performance, but is affected by impurities. The layer with the easy composition is placed inside, while the layer with the composition that weakly absorbs the impurities and has the composition that the oxidation performance of methacrolein is hard to be suppressed by the adsorption of the impurities is carried on the surface layer side, especially in the latter stage reaction of the continuous process. When used, methacrylic acid is hardly affected by impurities in the reaction gas at the former stage, and can produce methacrylic acid with high yield and high selectivity similarly to the oxidation reaction from pure methacrolein. Therefore, it is excellent in durability and can exhibit excellent catalytic performance over a long period of time.

In the methacrylic acid production catalyst of the present invention, since the catalytically active substance layer is thinned, heat storage during the methacrylic acid generation reaction can be reduced, thereby suppressing the sequential reaction of the generated methacrylic acid, Deterioration due to heat load can be prevented.

In the catalyst for producing methacrylic acid of the present invention, since the catalytically active substance layer is formed by a baking support method, it is firmly supported on an inert carrier, has high mechanical strength, and has excellent peel resistance. Therefore, it is sufficiently satisfactory for industrial implementation.

The catalyst for producing methacrylic acid of the present invention exhibits its excellent performance for a long time and obtains a high yield and a high selectivity similar to those at the start of the reaction without significantly increasing the reaction temperature even after long use. Can be.

The method for producing the catalyst of the present invention is simple and can be produced with high reproducibility. That is, a catalyst for producing methacrylic acid having a uniform catalytic performance can be produced, and it can be said that the catalyst is industrially extremely excellent due to its excellent reproducibility.

According to the oxidation method of the present invention, methacrylic acid can be efficiently produced using methacrolein, isobutyraldehyde, isobutyric acid or a mixture thereof as a starting material. In particular, oxidation of the methacrolein-containing mixed gas can be efficiently performed.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The conversion, selectivity and single-stream yield are defined as follows.

Example 1 To heated ion-exchanged water 40, 8,830 g of ammonium paramolybdate and 531.4 g of ammonium metavanadate were added, stirred, and dissolved.

123.7 g of arsenous acid and 523.8 g of phosphoric acid (85% by weight)
And then nitric acid (specific gravity 1.38) 4 and cesium nitrate
Add a solution of 812.3 g and 5 ion-exchanged water,
The mixture was heated and stirred to prepare a slurry (a).

A slurry (b) was prepared in the same manner as in the preparation of the slurry (a) except that the amount of phosphoric acid used was changed to 624.7 g.

Pellet carrier made of silicon carbide (outer diameter 6 mm, length
6.0mm) 1,600ml is placed in a stainless steel drum with an internal volume of 20 which can be heated from the outside, preheated to 120-200 ° C, and while rotating the drum, the slurry (a) and then the slurry (b) It was sprayed on to form a carrier layer.

The carrier on which the support layer was formed was calcined at 400 ° C. for 3 hours in a stream of air to form a catalytically active substance layer, thereby obtaining a catalyst (1).

The supported amount of the catalytically active substance layer in the catalyst (1) (hereinafter, the same as oxide) was 20 g per 100 ml of the carrier. The oxide composition (atomic ratio excluding oxygen, the same _applies hereinafter) of the slurry (a) after drying and firing is Mo ₁₂ P _1.09 V _1.09 Cs _1.0 As _0.3 , and the slurry (b) after drying and firing The oxide composition was Mo ₁₂ P _1.3 V _1.09 Cs _1.0 As _0.3 .

The following composition obtained by charging 1,500 ml of the above catalyst (1) into a steel reactor having an inner diameter of 25.4 mm and subjecting isobutylene to gas-phase catalytic oxidation in the presence of a Mo—Co—W—Fe oxide-based multi-component catalyst: Methacrolein 3.5 (% by volume) Isobutylene 0.04 Methacrylic acid + acetic acid 0.24 Water vapor 20 Oxygen 9 Others (mainly nitrogen) A mixed gas of 67.22 is introduced, reaction temperature 300 ℃, space velocity 1,200hr
^The oxidation reaction was performed at ^-1 (STP). Table 1 shows the results.

Example 2 An oxidation reaction was performed in the same manner as in Example 1 except that the proportions of isobutylene and other components (mainly nitrogen) in the mixed gas used for the oxidation reaction were changed to 0.08% by volume and 67.18% by volume, respectively. Was done. Table 1 shows the results.

Example 2 was conducted in order to investigate the influence on the catalyst used in the subsequent reaction of unreacted isobutylene. The mixing was conducted in the same manner as in Example 1 except that the content of unreacted isobutylene in the prereaction outlet gas was increased. Gas is used.

The catalyst (1) has a relatively small decrease in activity even when the isobutylene content in the methacrolein-containing gas mixture is increased. From these results, it is understood that the catalyst (1) is very stable against changes in the pre-reaction conditions in a continuous process and is suitable as an industrial catalyst.

Example 3 A catalyst was prepared in the same manner as in Example 1 except that 1,600 ml of a ring-shaped carrier made of silicon carbide (outer diameter 6 mm, length 5 mm, through-hole inner diameter 3 mm) was used in place of the pellet-shaped carrier. (2) was prepared.

The composition of the catalytically active substance layer of this catalyst (2) is the same as in Example 1, and the amount of the catalytically active substance carried is 20 g per 100 ml of the carrier.
Met.

Hereinafter, an oxidation reaction was performed in the same manner as in Example 1 except that the catalyst (2) was used instead of the catalyst (1), and that a gas having the following average gas composition was used as a raw material gas. Table 1 shows the results.

Methacrolein 3.5 (% by volume) Isobutylene 0.08 Methacrylic acid + acetic acid 0.24 Water vapor 20 Oxygen 9 Others (mainly nitrogen) 67.18 According to the results of Example 3, when the shape of the support was changed from pellet to ring, catalyst (2) It is understood that the use of a dual support layer as described above significantly reduces the decrease in the activity considered to be caused by the remaining isobutylene.

Example 4 4,770 g of ammonium molybdate was dissolved in 18 water.

Separately, 259.6 g of 85% orthophosphoric acid was diluted with 1,350 ml of water, and 163.3 g of copper nitrate and 111.4 g of arsenous acid were dissolved in the diluted solution. The mixture was added to the above aqueous solution of ammonium molybdate, stirred sufficiently while heating, and aged. went.

Separately, 259.6 g of 85% orthophosphoric acid was diluted with 1,350 ml of water, 204.8 g of vanadium pentoxide was added thereto, and the water was evaporated while heating and stirring to obtain a yellow complex. This complex was added to the above reaction precipitate of phosphorus, molybdenum, copper and arsenic, and finally 126.3 g of potassium hydroxide was added to water 1,
A solution dissolved in 350 ml was added to prepare a slurry (c).

A slurry (d) was prepared in the same manner as in the preparation of the slurry (c) except that the amounts of copper nitrate and potassium hydroxide were changed to 54.4 g and 189.5 g, respectively.

In Example 1, a ring-shaped carrier made of α-alumina (outer diameter 6 mm, length 5 mm, through-hole inner diameter 3 mm) was used instead of the pellet-shaped carrier, and the slurry (c) was first used, and then the slurry (d) was used. Was carried out in the same manner as in Example 1 except that the catalyst (3) was sequentially loaded.

The amount of the catalytically active substance supported on the catalyst (3) is
The weight was 20 g per 0 ml.

The oxide composition after drying and firing the slurry (C) is Mo ₁₂ P ₂ Cu _0.3 K ₁ V ₁ As _0.5 , and the oxide composition after drying and firing the slurry (D) is Mo ₁₂ P ₂ Cu _0.1 K _1.5 V ₁ As _0.5 .

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (3) was used instead of the catalyst (2). Table 2 shows the results.

Example 5 553.8 g of 85% phosphoric acid was added to an aqueous solution in which 5,088 g of ammonium molybdate was dissolved in pure water 10, then an aqueous solution in which 936.2 g of cesium nitrate was dissolved in 3.6 of water was added, and 582.6 g of bismuth nitrate and antimony pentoxide were further added. 194.3 g was added as powder, and finally, 120.1 g of chromic anhydride and 133.
An aqueous solution prepared by dissolving 2 g in 3.6 was added to obtain a slurry (e).

A slurry (f) was prepared in the same manner as in the preparation of the slurry (e) except that the amount of antimony pentoxide used was changed to 19.4 g.

Next, in Example 1, a spherical carrier (outer diameter: 6 mm) made of silicon carbide was used in place of the pellet-like carrier, and the slurry (e) was first baked and then the slurry (f) was sequentially baked and carried. A catalyst (4) was prepared in the same manner as in Example 1.

The supported amount of the catalytically active substance layer in the catalyst (4) is:
The amount was 20 g per 100 ml of the carrier. The oxide composition after drying and firing the slurry (e) is Mo ₁₂ P ₂ Bi _0.5 Sb _0.5 Cs _2.0 Cr _0.5 Se _0.5 , and the oxide composition after drying and firing the slurry (Mo) is Mo ₁₂ P ₂ Bi _0.5 Sb _0.05 Cs _2.0 Cr _0.5 Se _0.5 .

Hereinafter, an oxidation reaction was performed in the same manner as in Example 3 except that the catalyst (4) was used instead of the catalyst (2). Table 2 shows the results.

Example 6 Molybdenum trioxide 4,802 g, vanadium pentoxide 252.8 g,
Copper oxide 44.2g, iron oxide 44.4g, tin oxide 41.9g and 85%
320.5 g of orthophosphoric acid was dispersed in ion-exchanged water 40. After heating and stirring the mixture for about 3 hours, 15.6 g of potassium hydroxide was added, and the mixture was refluxed under boiling for about 3 hours to obtain a slurry (g).
Was prepared.

In the preparation of this slurry (g), the amount of vanadium pentoxide and orthophosphoric acid used was 303.4 g and
A slurry (h) was prepared in the same manner except that the amount was changed to 384.6 g.

Next, in Example 1, a ring-shaped carrier (outer diameter 6 mm, length 5 mm,
A catalyst (5) was prepared in the same manner as in Example 1, except that the slurry (g) and the slurry (h) were sequentially carried first, using a through-hole having an inner diameter of 3 mm.

The supported amount of the catalytically active substance in the catalyst (5) was 20 g per 100 ml of the carrier. The oxide composition after drying and firing the slurry (g) is Mo ₁₂ P ₁ V ₁ K _0.1 Cu _0.2 Fe _0.2 Sn _0.1 , and the oxide composition after drying and firing the slurry (h) is M ₁₂ P _1.2 V _1.2 K _0.1 Cu _0.2 Fe _0.2 Sn _0.1 .

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (5) was used instead of the catalyst (2). Table 2 shows the results.

Example 7 In the slurry (a) of Example 1, the catalyst preparation scale was halved, and 272.3 g of barium nitrate was used instead of cesium nitrate.
Slurry (R) in the same manner as in Example 1 except that
Was prepared.

In preparing this slurry (li), a slurry (nu) was prepared in the same manner except that the amounts of arsenous acid and barium nitrate used were changed to 20.6 g and 435.7 g, respectively.

Next, in Example 1, a pellet-shaped carrier made of α-alumina (outer diameter 6 mm, length 6 mm) was used instead of the pellet-shaped carrier made of silicon carbide.
Example 1 except that the slurry
Catalyst (6) was prepared in the same manner as described above.

The supported amount of the catalytically active substance in the catalyst (6) was 20 g per 100 ml of the carrier. The oxide composition after drying and calcining the slurry (li) is Mo ₁₂ P _1.09 V _1.09 Ba _0.5 As _0.3 , and the oxide composition after drying and calcining the slurry (nu) is Mo ₁₂ P _1.09 V _1.09 Ba _0.8 As It was _0.1 .

Hereinafter, an oxidation reaction was performed in the same manner as in Example 3 except that the catalyst (6) was used instead of the catalyst (2). Table 2 shows the results.

Example 8 A slurry was prepared in the same manner as in Example 1 except that 810.7 g of cesium nitrate and 130.7 g of germanium oxide, 222.7 g of zirconium nitrate, and 121.3 g of cobalt nitrate were added.

In preparing this slurry (ヲ), a slurry (ヲ) was prepared in the same manner except that the amounts of cesium nitrate and zirconium nitrate were changed to 1,218.5 g and 334.1 g, respectively.

Next, in Example 1, a ring-shaped carrier made of α-alumina instead of the pellet-shaped carrier (outer diameter: 6 mm, length: 5 m)
m, through-hole inner diameter 3 mm)
Next, a catalyst (7) was prepared in the same manner as in Example 1 except that the operation of sequentially supporting the slurry (ヲ) was repeated twice.

The supported amount of the catalytically active substance in the catalyst (7) was 20 g per 100 ml of the carrier. The oxide composition of the slurry (ル) after drying and firing was Mo ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.0 Ge _0.3 Zr _0.2 Co _0.1 , and the oxide composition of the slurry (ヲ) after drying and firing was Mo. ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.5 Ge _0.3 Zr _0.3 Co _0.1

Hereinafter, an oxidation reaction was performed in the same manner as in Example 3 except that the catalyst (7) was used instead of the catalyst (2). Table 2 shows the results.

Example 9 A slurry (wa) was prepared in the same manner as in Example 1 except that 819.5 g of cesium nitrate and 199.5 g of tellurium dioxide, 239.2 g of manganese nitrate, and 242.3 g of nickel nitrate were added.

In preparing the slurry (W), a slurry (F) was prepared in the same manner except that the amounts of ammonium metavanadate, manganese nitrate, and nickel nitrate were changed to 633.8 g, 358.8 g, and 363.5 g, respectively.

Next, in Example 1, a pellet-shaped carrier made of silica-alumina (outer diameter 6 mm, length 6 mm) was used instead of the pellet-shaped carrier made of silicon carbide. 2) The operation of sequentially carrying
Contact (8) was prepared in the same manner as in Example 1 except that the procedure was repeated twice.

The supported amount of the catalytically active substance in this catalyst (8) was 20 g per 100 ml of the carrier. The oxide composition after drying and firing the slurry (W) is Mo ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.0 Te _0.3 Mn _0.2 Ni _0.2 , and the oxide composition after drying and firing the slurry (F) is Mo ₁₂ P _1.09 As _0.3 V _1.3 Cs _1.0 Te _0.3 Mn _0.3 Ni _0.3 .

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (8) was used instead of the catalyst (2). Table 2 shows the results.

Example 10 A slurry (Y) was prepared in the same manner as in Example 1, except that 812.8 g of cesium nitrate and 562.8 g of ammonium tungstate, 247.9 g of zinc nitrate and 70.8 g of silver nitrate were added.

In the preparation of this slurry (Y), cesium nitrate,
A slurry (ta) was prepared in the same manner except that the amounts of ammonium tungstate and silver nitrate were changed to 1,056.0 g, 225.1 g and 35.4 g, respectively.

Next, in Example 1, a ring-shaped carrier made of silica-alumina (outer diameter 6 mm, length 5 mm, through-hole inner diameter 3 mm) was used in place of the pellet-shaped carrier, and the slurry (Y) was first used, The operation of sequentially supporting the slurry (ta)
A catalyst (9) was prepared in the same manner as in Example 1 except that the procedure was repeated twice.

The supported amount of the catalytically active substance in the catalyst (9) was 20 g per 100 ml of the carrier. The oxide composition of the slurry (Y) after drying and firing was Mo ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.0 W _0.5 Zn _0.2 Ag _0.1 , and the oxide composition after drying and firing of the slurry (TA) was Mo ₁₂ P _1.09 AS _0.3 V _1.09 Cs _1.3 W _0.2 Zn _0.2 Ag _0.05 .

Hereinafter, an oxidation reaction was performed in the same manner as in Example 3 except that the catalyst (9) was used instead of the catalyst (2). Table 2 shows the results.

Example 11 A slurry was prepared in the same manner as in Example 1 except that 552.3 g of thallium nitrate, 166.1 g of niobium pentoxide, 441.0 g of strontium nitrate and 96.0 g of palladium nitrate were added together with 812.3 g of cesium nitrate. Prepared.

In preparing this slurry (re), the amounts of arsenous acid, thallium nitrate and strontium nitrate used were each 8
A slurry (so) was prepared in the same manner except that the amounts were changed to 2.5 g, 721.5 g, and 617.4 g.

Next, in Example 1, a spherical carrier (outer diameter: 6 mm) made of silicon carbide was used instead of the pellet-shaped carrier, and the operation of sequentially supporting the slurry (d) and then the slurry (d) was performed in three steps. A catalyst (10) was prepared in the same manner as in Example 1 except that the procedure was repeated twice.

The supported amount of the catalytically active substance in this catalyst (10) was 20 g per 100 ml of the carrier. The oxide composition of the slurry (d) after drying and firing was Mo ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.0 Tl _0.5 Sr _0.5 Nb _0.3 Pb _0.1 . The composition was Mo ₁₂ P _1.09 As _0.2 V _1.09 Cs _1.0 Tl _0.8 Sr _0.7 Nb _0.3 Pd _0.1 .

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (10) was used instead of the catalyst (2). Table 2 shows the results.

Example 12 A slurry was prepared in the same manner as in Example 1 except that, in addition to 812.3 g of cesium nitrate, 307.2 g of rubidium nitrate, 196.8 g of calcium nitrate and 135.4 g of rhodium nitrate were added.

In preparing this slurry, the amount of rubidium nitrate and calcium nitrate used was 553.0 g and
A slurry (d) was prepared in the same manner except that the amount was changed to 393.6 g.

Next, in Example 1, a ring-shaped carrier (outer diameter 6 mm, length 5 mm,
First, slurry (tu) is used
Next, a catalyst (11) was prepared in the same manner as in Example 1 except that the operation of sequentially supporting the slurry (d) was repeated three times.

The supported amount of the catalytically active substance in the catalyst (11) was 20 g per 100 ml of the carrier, and the oxide composition after drying and calcining the slurry (tu) was Mo ₁₂ P _1.09 As _0.3 V _1.09 Cs _1.0 Rb _0.5 Ca _0.2 a Rh _0.1, drying of the slurry (ne) oxide composition after firing was _{Mo 12 P 1.09 As 0.3 V 1.09} Cs 1.0 Rb 0.9 Ca 0.4 Rh 0.1.

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (11) was used instead of the catalyst (2). Table 2 shows the results.

Example 13 4,320 g of molybdenum trioxide, 227.4 g of vanadium pentoxide and 432.5 g of 85% orthophosphoric acid were added to water 15 and heated under reflux for 24 hours. 215.1 g of powdered cerium oxide, 379.2 g of potassium nitrate and 39.8 g of powdered copper oxide were added thereto to prepare a slurry (Na).

A slurry (La) was prepared in the same manner as in the preparation of the slurry (Na) except that the amounts of cerium oxide and copper oxide used were changed to 43.0 g and 19.9 g, respectively.

Next, in Example 1, an operation in which a pellet-shaped carrier made of α-alumina was used instead of the pellet-shaped carrier made of silicon carbide, and the slurry (Na) was first supported, and then the slurry (La) was successively supported. Except repeating 3 times, it carried out similarly to Example 1, and prepared catalyst (12).

In the catalyst (12), the amount of the catalytically active substance
The oxide composition after drying and firing the slurry (Na) is 20 g per 100 ml, and the oxide composition after drying and firing the slurry (La) is Mo ₁₂ V ₁ P _1.5 K _1.5 Cu _0.2 Ce _0.5 Mo ₁₂ V ₁ P _1.5 K _1.5 Cu _0.1 Ce _0.1 .

Thereafter, an oxidation reaction was carried out in the same manner as in Example 3 except that the catalyst (12) was used instead of the catalyst (2). Table 2 shows the results.

Example 14 Using the catalyst (1) obtained in Example 1, a continuous reaction was performed for 4,000 hours under the same conditions as in Example 3. Although the reaction initiation temperature was 300 ° C, raising the reaction temperature by 7 ° C was sufficient to obtain almost the same conversion of methacrolein after 4,000 hours as at the start of the reaction. The reaction results after 4,000 hours were as follows: reaction temperature 307 ° C, methacrolein conversion 84.4%,
Methacrylic acid selectivity was 86.7%.

Example 15 Using the catalyst (1) obtained in Example 1, an oxidative dehydrogenation reaction of isobutyraldehyde was performed.

That is, 1,500 ml of the catalyst (1) was charged into a steel reaction tube having a diameter of 25.4 mm, and a mixed gas of isobutyraldehyde: oxygen: water vapor: nitrogen = 5.0: 12.5: 10.0: 72.5 (volume ratio) was used at a space velocity of 800 hr ^-1. (STP) and reacted at a temperature of 290 ° C. Table 3 shows the results.

Example 16 Using the catalyst (1) obtained in Example 1, an oxidative dehydrogenation reaction of isobutyric acid was performed.

That is, 1,500 ml of the catalyst (1) was charged into a steel reactor having a diameter of 25.4 mm, and isobutyric acid: oxygen: steam: nitrogen = 5.0:
A mixed gas of 10.0: 10.0: 75.0 (volume ratio) with a space velocity of 2,000h
It was introduced at r ^-1 (STP) and reacted at a temperature of 290 ° C. Table 4 shows the results.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI // C07B 61/00 300 C07B 61/00 300 (72) Inventor Yukio Aoki 992, Nishioki, Akihama-ku, Aboshi-ku, Himeji-shi, Hyogo Nippon Shokubai Examiner in the Catalysts Research Laboratory, Chemical Industry Co., Ltd. Yoshihisa Seki (56) References JP-A-48-28416 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 21/00- 38/74 C07B 6/00 300

Claims (5)

(57) [Claims] 1. A catalyst for producing methacrylic acid comprising an inert carrier and a catalytically active material layer supported on the carrier, wherein the catalytically active material layer has the following formula (1): MO _{a Pb} A _{c B d C e D f O} x (1) ( wherein, Mo is molybdenum, P is phosphorus, at least one element a is selected arsenic, antimony, germanium, bismuth, zirconium, cerium and selenium,
B is copper, iron, chromium, nickel, manganese, cobalt,
At least one element selected from tin, silver, zinc, palladium, rhodium and tellurium; C is at least one element selected from vanadium, tungsten and niobium; D is selected from alkali metals, alkaline earth metals and thallium At least one element, O represents oxygen, a, b, c, d, e, f and x are each Mo,
Represents the atomic ratio of P, A, B, C, D and O. When a = 12, b = 0.5-4, c = 0-5, d = 0-3, e = 0
-4, f = 0.01-4, and x is a numerical value determined by the oxidation state of each element). A compound containing each elemental component of the oxide represented by the formula (1) is mixed, and further heated, if necessary, to prepare two or more slurries or solutions having different compositions. A catalyst for producing methacrylic acid, which is formed by spraying sequentially on an inert carrier and repeating this operation as necessary. 2. The catalyst active substance layer has the following characteristics: specific surface area = 1 to ²⁰ m ² / g, pore volume = 0.1 to 1 ml / g, pore diameter distribution = 1 to 10 μm pores 20 to 70% 0.5 The catalyst for producing methacrylic acid according to claim 1, wherein the catalyst has 20% or less of pores in a range of from 0.1 to less than 1 µm and 20 to 70% of pores in a range of from 0.1 to less than 0.5 µm (volume ratio to the total pore volume). 3. A methacrylic acid characterized by contacting a raw material gas comprising one or more selected from methacrolein, isobutyraldehyde and isobutyric acid with the catalyst for producing methacrylic acid according to (1). Method for producing acid. 4. A method for producing methacrylic acid, comprising oxidizing a catalyst for producing methacrylic acid according to (1) by bringing a mixed gas containing methacrolein into contact with the catalyst. 5. The methacrolein-containing gas mixture is obtained by catalytically oxidizing one or more source gases selected from isobutylene, tert-butanol and methyl tert-butyl ether. The method for producing methacrylic acid according to item (4).