RU2776481C2 - Catalyst - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a catalyst for the production of unsaturated aldehyde and unsaturated carboxylic acid. A catalyst for the production of acrolein and acrylic acid containing molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe) is described, and in this catalyst the total pore volume (A) in this catalyst for pores having a diameter of 1 mcm or more to 100 mcm or less, is from 0.12 ml/g or more to 0.19 ml/g or less, and the ratio (A/B) of the total pore volume (A) to the total pore volume (B) having a pore diameter from 1 mcm or more to 100 mcm or less in the crushed product is not passing through a Tyler 6 mesh (a sieve with a hole size of 3.36 mm), for the crushed product obtained by grinding the catalyst under the condition of grinding A is from 0.30 or more to 0.87 or less.

EFFECT: achieving an excellent degree of olefin conversion and suitable selectivity for unsaturated aldehyde such as acrolein, and suitable selectivity for unsaturated carboxylic acid such as acrylic acid, in particular, a high selectivity ratio for unsaturated carboxylic acid such as acrylic acid, as well as increased yields of unsaturated aldehyde such as acrolein, and unsaturated carboxylic acid, such as acrylic acid.

5 cl, 3 ex, 1 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] This invention relates to a catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid.

PRIOR ART

[0002] As catalysts for producing an unsaturated aldehyde and an unsaturated carboxylic acid by catalytic gas-phase oxidation of an olefin having 3 or 4 carbon atoms and an oxygen-containing gas, catalysts containing molybdenum as a main component are generally used. Namely, catalysts for use in the production of acrolein and acrylic acid from propylene, and the like. as raw materials, catalysts for use in the production of methacrolein and methacrylic acid from isobutylene, and the like. as starting materials, and methods for their production have been actively and progressively improved from various points of view.

[0003] Methods for producing an unsaturated aldehyde or an unsaturated carboxylic acid include the catalytic gas-phase oxidation of olefins and gases containing oxygen in fixed bed reactors filled with catalysts.

[0004] Such catalysts that are filled in fixed bed reactors have any shape such as a cylindrical shape, an annular shape, a tablet shape, or a spherical shape, and such commonly used catalysts are catalysts obtained by molding powders of catalytically active components or catalysts comprising catalytically active components deposited on inert carriers having the same shape as above.

[0005] Patent Document 1 presents, as a catalyst for oxidizing propylene, a catalyst comprising molybdenum, iron and bismuth and having a certain specific surface area and a certain pore volume. Patent Document 2 describes a catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid in which the pore volume with respect to a certain pore diameter is within a certain range.

DOCUMENTS RELATED TO THE PRIOR ART

PATENT DOCUMENTS

[0006]

Patent Document 1: JP S63-200839 A

Patent Document 2: JP 2017-176931 A

SUMMARY OF THE INVENTION

Technical problem

[0007] However, the catalyst described in Patent Document 1 is insufficient in terms of reaction efficiency, specifically in the catalytic gas-phase oxidation of an olefin such as propylene and an oxygen-containing gas through the use of a catalyst, and cannot achieve high yield levels of unsaturated aldehyde, such as acrolein; and an unsaturated carboxylic acid such as acrylic acid. Moreover, the catalyst has the problem of causing a side reaction occurring in catalytic gas phase oxidation at high temperatures to increase the activity of the catalyst resulting in a greater reduction in yield. In addition, the catalyst is also insufficient in terms of strength, and the catalyst may be pulverized and/or crushed, thereby causing the catalytic gas-phase oxidation reaction to be not stable and efficiently performed for a long period of time.

For the catalyst described in Patent Document 2, it is also possible to improve the yield of unsaturated carboxylic acid and the strength of the catalyst.

[0008] The present invention has been made to solve the above problems. Namely, the object is to provide a catalyst that is excellent in the conversion of an olefin feedstock such as propylene and can selectively produce the desired unsaturated aldehyde and unsaturated carboxylic acid at high yield levels even under the condition of a large amount of feed a starting material, namely, under a high load applied to the catalyst, and which has high strength and can enable stable catalytic gas phase oxidation reaction for a long period of time, as a catalyst for use in catalytic gas phase oxidation of an olefin such as propylene, and gas containing oxygen, and, accordingly, obtaining the corresponding unsaturated aldehyde, such as acrolein, and the corresponding unsaturated carboxylic acid, such as acrylic acid.

Solution

[0009] The inventors of the present invention have made careful studies in order to solve the above problems, and as a result, found that a catalyst can be produced in which the total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less is 0.12 ml/g or more to 0.19 ml/g or less, and the ratio (A/B) of the total pore volume (A) to the total pore volume (B) having a pore diameter of 1 μm or more to 100 µm or less, in the pulverized product not passing through the 6 mesh Tyler sieve, for the pulverized product obtained by grinding the catalyst under a certain condition, is 0.30 or more to 0.87 or less, to thereby provide the possibility of achieving excellent olefin conversion and suitable selectivity for an unsaturated aldehyde such as acrolein and a suitable selectivity for an unsaturated carboxylic acid such as acrylic acid, in particular a high selectivity ratio for unsaturated carboxylic acid such as acrylic acid as well as increased yields of unsaturated aldehyde such as acrolein and unsaturated carboxylic acid such as acrylic acid, even under conditions of high olefin feedstock and high catalyst loading, catalytic gas phase oxidation of an olefin and an oxygen-containing gas through the use of this catalyst, which led to the creation of this invention.

[0010] Namely, the present invention is as follows.

[1] A catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid, in which

the total pore volume (A) in this catalyst for pores having a diameter of 1 µm or more to 100 µm or less is 0.12 ml/g or more to 0.19 ml/g or less, and

the ratio (A/B) of the total pore volume (A) to the total pore volume (B) having a pore diameter of 1 µm or more to 100 µm or less in ground product not passing through a 6 mesh Tyler sieve for ground product, obtained by grinding the catalyst under the grinding condition A is 0.30 or more to 0.87 or less;

Grinding condition A:

one hundred grams of the catalyst is loaded into a drum granulator which comprises a cylindrical body fixed in a vertical position and a disk located horizontally at the lower end of the cylindrical body, and which allows rotational movement and circular movement of the particles by rotating the disk around the center of the cylindrical body, the operation of the disk start at 12 G relative centrifugal acceleration and increase to 130 G relative centrifugal acceleration for 1 minute, and continue disk rotation at 130 G relative centrifugal acceleration for 2 minutes; where

the relative centrifugal acceleration is defined as a numerical value expressed as the ratio of the amount of centrifugal force applied per unit mass of the catalyst to the acceleration due to gravity, and is represented by the following Equation (X):

F=1118 × r × N ² × 10 ^–8 Equation (X) where

F: relative centrifugal acceleration (G),

r: distance (cm) from the center of rotation to the lower end of the cylindrical body,

N: rotation speed (rpm).

[0011]

[2] The catalyst according to [1], where the catalyst contains molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe), and the atomic ratio of molybdenum (Mo), bismuth (Bi ), cobalt (Co), nickel (Ni) and iron (Fe) in the catalyst satisfies the following Formula (1):

Mo _a Bi _b Co _c Ni _d Fe _e (1)

where the values from a to e represent the atomic ratio with respect to each of the elements, and when a=12, the intervals b= 0.5 to 7, c= 0.1 to 10, d= 0.1 to 10 and e = from 0.05 to 5.

[0012]

[3] The catalyst according to [1] or [2], wherein the catalyst contains a carrier.

[4] The catalyst according to any one of [1] to [3], wherein the catalyst has a spherical shape.

[5] A method for producing acrolein and acrylic acid, wherein the method includes the step of performing catalytic gas-phase oxidation of propylene and an oxygen-containing gas using a catalyst according to any one of [1] to [4].

Advantages of the Invention

[0013] The present invention can provide a catalyst which has high catalytic performance, which is excellent in olefin conversion rate even under the condition of high loading applied to the catalyst, and which, in addition, can enable the production of an unsaturated aldehyde such as acrolein, and an unsaturated carboxylic acid such as acrylic acid with high selectivity in suppressing the over-oxidation reaction. In addition, the catalyst according to the present invention has high strength and is less pulverized. As a result, the catalyst can be effectively placed in a dense manner in the reactor, and the catalyst can be used to thereby enable the production of an unsaturated aldehyde such as acrolein and an unsaturated carboxylic acid such as acrylic acid, especially an unsaturated carboxylic acid such as as acrylic acid, with high selectivity over a long period of time from the start of catalytic gas-phase oxidation.

DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described in detail, however, the description of each component provided below are typically illustrative embodiments of the present invention, and the present invention is not intended to be limited to the scope of this disclosure.

[0015] [Catalyst]

The catalyst according to one embodiment of the present invention is a catalyst for producing an unsaturated aldehyde and an unsaturated carboxylic acid, wherein the total pore volume (A) in the catalyst for pores having a diameter of 1 µm or more to 100 µm or less is 0.12 ml /g or more to 0.19 ml/g or less, and the ratio (A/B) of the total pore volume (A) to the total pore volume (B) for pores having a diameter of 1 μm or more to 100 μm or less, in the non-Tyler 6 mesh pulverized product obtained by pulverizing the catalyst under the pulverizing condition A, is 0.30 or more to 0.87 or less. The ratio (A/B) is preferably 0.50 or more to 0.87 or less, more preferably 0.60 or more to 0.87 or less, even more preferably 0.65 or more to 0.87 or less. The ratio (A/B) may be in this range, thereby not only providing a catalyst that has an excellent feedstock conversion rate in catalytic gas-phase oxidation of an olefin (hereinafter sometimes simply referred to as "conversion rate") and which can enable the production of unsaturated aldehyde and unsaturated carboxylic acid with high selectivity, but also tend to improve catalyst strength and suppress pulverization.

[0016] Hereinafter, the relationship (A/B) will be described in more detail. The total pore volume (A) reflects the volume of each pore near the surface of the catalyst, and the total pore volume (B) reflects the volume of each pore inside the catalyst. In other words, a lower total pore volume (A), along with the fact that it means a higher surface density of the catalyst and giving a higher strength of the catalyst, makes it difficult for the gaseous feed material to reach the inside of the catalyst and causes the catalytically active component present inside catalyst, practically does not contribute to the catalytic reaction, leading to a decrease in the degree of conversion. A larger total pore volume (A), along with indicating a lower catalyst surface density and causing deterioration in catalyst strength, makes it possible for the gaseous feedstock to easily reach the interior of the catalyst and allows efficient use of any catalytically active component present not only near the surface. of the catalyst, but also in the interior of the catalyst, thereby leading to an improvement in the conversion rate.

In the case where the ratio (A/B) is in the specified range, the balance between the degree of conversion of the source material and the strength of the catalyst is optimized.

[0017] Grinding condition A of the catalyst means grinding performed by loading 100 g of catalyst into a drum granulator, which includes a cylindrical body fixed in a vertical position and a disk located horizontally at the lower end of the cylindrical body, and which allows rotational movement and circular movement of particles by rotating the disk around the center of the cylindrical body, starting the functioning of the disk at a relative centrifugal acceleration of 12 G and increasing the acceleration to a relative centrifugal acceleration of 130 G for 1 minute, and continuing to rotate the disk at a relative centrifugal acceleration of 130 G for 2 minutes.

Relative centrifugal acceleration is defined as a numerical value expressed as the ratio of the amount of centrifugal force applied per unit mass of the catalyst to accelerate the force of gravity, and is represented by the following Equation (X):

F=1118 × r × N ² × 10 ^–8 Equation (X) where

F: relative centrifugal acceleration (G),

r: distance (cm) from the center of rotation to the lower end of the cylindrical body,

N: rotation speed (rpm).

[0018] Grinding of the catalyst under grinding condition A is performed, in particular, by loading 100 g of catalyst into a Marmelizer QJ-230T-2 Model, manufactured by DALTON Corporation, (cylinder diameter 23 cm), starting operation at a rotation speed of 300 rpm and accelerating it to a rotation speed of 1000 rpm for 1 minute, and continuing to operate at a rotation speed of 1000 rpm for 2 minutes.

[0019] the Total pore volume can be measured in accordance with the method of mercury intrusion porosimetry. The mercury intrusion porosimetry method is a method that involves subjecting a sample to a decompression treatment at a reduced pressure (50 µm Hg or less) for 10 minutes, and then measuring the resulting mercury intrusion porosimetry curve using an AutoPore IV 9520 Model manufactured by Micromeritics Japan G.K., and determining total pore volume (total pore volume).

In addition, the conversion rate of the starting material (olefin), the selectivity of the unsaturated aldehyde, and the selectivity of the unsaturated carboxylic acid are calculated according to the equations below.

Olefin Conversion (mol %) = (Molar olefin reacted/Molar olefin fed) x 100

Selectivity of unsaturated aldehyde (mole%) = (Molar amount of unsaturated aldehyde produced/Molar amount of olefin reacted) × 100

Selectivity of unsaturated carboxylic acid (mole%) = (Molar amount of unsaturated carboxylic acid produced/Molar amount of olefin reacted) × 100

[0020] The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less is 0.12 ml/g or more to 0.19 ml/g or less, preferably 0.12 ml /g or more to 0.18 ml/g or less, more preferably 0.15 ml/g or more to 0.18 ml/g or less. The total pore volume (A) is the upper limit or less, thereby inhibiting the catalyst from breaking and pulverizing. The total pore volume (A) is the lower limit or more, thereby making it possible to realize in a simple manner high raw material conversion and high unsaturated aldehyde selectivity, high unsaturated carboxylic acid selectivity and high unsaturated carboxylic acid selectivity ratio.

The unsaturated carboxylic acid selectivity ratio here means the ratio of the selectivity of the unsaturated carboxylic acid relative to the overall selectivity of the unsaturated aldehyde and the selectivity of the unsaturated carboxylic acid.

[0021] The catalyst preferably includes molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe), and the atomic ratio of molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe) in the catalyst preferably satisfies the following Formula (1):

Mo _a Bi _b Co _c Ni _d Fe _e (1)

where a through e represent the atomic ratio with respect to each of the elements, and when a=12, the intervals b= 0.5 to 7, c= 0.1 to 10, d= 0.1 to 10 and e= from 0.05 to 5 are.

Formula (1) can be satisfied, thereby providing excellent propylene conversion and making it possible to produce an unsaturated aldehyde such as acrolein and an unsaturated carboxylic acid such as acrylic acid with high selectivity.

[0022] In addition, the catalyst preferably includes a carrier. The support is preferably inert to the catalytic gas-phase oxidation reaction of the olefin and the oxygen-containing gas. Examples of the carrier include silica, silicon carbide, alumina, mullite and alundum, and alumina is more preferred. The catalyst may include a support, thereby exhibiting a catalytic function not only on the surface of the catalyst, but also in the interior of the catalyst, and allowing the intended improvements in unsaturated aldehyde selectivity and unsaturated carboxylic acid selectivity.

[0023] The amount of carrier corresponds to such an amount that the ratio of the amount of catalyst component powder to the total amount of catalyst component powder and the amount of carrier (amount of catalyst component powder / (amount of catalyst component powder+amount of carrier)) is usually from 10% to up to 90% by weight, preferably from 30% by weight to 80% by weight. The ratio is in this range, thereby making it possible to obtain a total pore volume (A) of the catalyst easily corresponding to the range of this invention.

[0024] In addition, examples of the shape of the catalyst include an annular shape, a columnar shape, a tablet shape, and a spherical shape, and the spherical shape is preferred. Such a spherical shape may mean not only a geometrically regular spherical shape, but also an elliptical shape, and more preferably a shape close to a regular spherical shape. In the present embodiment, a catalyst whose particles have a ratio of the largest diameter (major axis diameter) to the smallest diameter (minor axis diameter), among three diameters perpendicular to one another, of 2 or less, preferably 1.3 or less, is defined as having spherical shape. The catalyst may have a spherical shape, thereby making it possible to suppress an increase in pressure loss in a dense bed of packed catalyst in a fixed bed reactor.

The ratio of the major axis diameter to the minor axis diameter of the catalyst can be obtained by measuring the major axis diameter and the minor axis diameter with respect to each of 100 catalyst particles with a VM-8040 high-precision two-dimensional measurement device manufactured by KEYENCE CORPORATION, and then measuring the mean value of the diameter along the major axis and the mean value of the diameter along the minor axis to calculate their ratio.

[0025] In addition, the pulverization ratio of the catalyst is preferably 3.0% or less, more preferably 1.0% or less. In the case where the pulverization ratio is in this range, the catalyst can be excellent in terms of strength, and accordingly can be densely packed in the reactor tube of the fixed bed reactor, neither pulverized nor crushed.

The degree of pulverization of the catalyst can be determined by, for example, introducing a funnel (150 mm in diameter in the upper section of the cone, and 25 mm in diameter in the lower section of the cone) into the upper section of an acrylic cylinder (c 66 mm) having a height of 1 m, loading about 20 g of catalyst (powdering sample) through the top section of the funnel cone, dropping it through a cylinder onto a tray located at the bottom of the cylinder, extracting the supplied powdering sample from the tray, sifting the extracted sample with a sieve, having a hole size of 2.36 mm to provide fine particles, measuring the mass (mass of the powder material) of the fine particles, and performing a calculation according to the equation below.

Powdering ratio (%) = (Weight of powder material/Weight of sample for measuring powdering ratio) × 100

[0026] Next, a suitable method for producing a catalyst will be described.

The method for producing the catalyst preferably includes the following two steps.

Stage (a); integrating and heating respective parent compounds of elements including molybdenum, bismuth, cobalt, nickel and iron (hereinafter sometimes referred to as "catalytically active elements") in an aqueous system, thereby providing a powder of the catalytically active component.

Step (b); molding the powder of the catalytically active component obtained in step (a), thereby providing a molded product.

[0027] Combining the respective catalyst element precursors including molybdenum, bismuth, cobalt, nickel and iron in an aqueous system in step (a), meaning that aqueous solutions or aqueous dispersions of the respective catalyst element precursors are mixed together simultaneously or in steps manner and then subjected to an aging treatment. Namely, the following methods (a1) to (a5) are used, and all methods are included in the concept of combining the respective starting compounds of catalytically active elements in an aqueous system.

(a1) A method comprising co-simultaneous mixing of the respective starting compounds

(a2) A method comprising co-simultaneously mixing respective starting compounds and subjecting the compounds to an aging treatment

(a3) A method comprising stepwise mixing of the respective starting compounds

(a4) A method comprising repeating a cycle comprising mixing appropriate starting compounds in a stepwise manner and subjecting the compounds to an aging treatment

(a5) Method where (a1) through (a4) are combined

Aging here refers to "an operation involving the processing of an industrial starting material or a partially processed product under certain conditions for a certain time, a certain temperature, or the like, to achieve and improve the desired physical properties or chemical properties, or to progress a predetermined reaction" (Kagaku Daijiten (Encyclopaedia Chimica), Kyoritsu Shuppan Co., Ltd.). In the present invention, the specific time refers to the range from 10 minutes to 24 hours, and the specific temperature refers to the range from room temperature to the boiling point of each of the aqueous solutions or each of the aqueous dispersions.

[0028] The heating in step (a) refers to a heat treatment to form a composite metal oxide from individual metal oxides of the respective catalytically active element precursors, to form a complex metal oxide from a composite compound obtained by combining the respective precursor compounds of the catalytically active elements, to form the resulting composite metal oxide; or the like. Heating is optionally performed only once. Namely, the heating may be performed arbitrarily between and/or during the respective steps collectively shown above as steps (a1) to (a5), or may be additionally performed after such a plurality, if necessary. The heating temperature is usually in the range from 200°C to 600°C.

Drying, grinding, etc. may optionally be additionally performed before or after and/or during the combination and heating.

[0029] Examples of the starting molybdenum (Mo) compound include ammonium paramolybdate, molybdenum trioxide, molybdic acid, ammonium phosphomolybdate, and phosphomolybdic acid.

[0030] Examples of the starting bismuth compound (Bi) include bismuth chloride, bismuth nitrate, bismuth oxide, and bismuth subcarbonate. The amount of feedstock bismuth compound loaded is preferably such that the resulting catalyst satisfies Formula (1), where b=0.5 to 7, more preferably b=0.7 to 5.0, even more preferably b=1.0 to 4 ,9, for a=12. The range b may be as above, whereby the catalyst is allowed to have high conversion, unsaturated aldehyde selectivity, unsaturated carboxylic acid selectivity, and unsaturated carboxylic acid selectivity ratio.

[0031] Examples of the parent compound of cobalt (Co) include cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt carbonate and cobalt acetate. The amount of feed cobalt compound loaded is preferably such that the resulting catalyst satisfies Formula (1) where c=0.1 to 10, more preferably c=0.3 to 5.0, even more preferably c=0.5 to 3 ,0, for a=12. The range c may be as above, whereby the catalyst is allowed to have high values of conversion, unsaturated aldehyde selectivity, unsaturated carboxylic acid selectivity, and unsaturated carboxylic acid selectivity ratio.

[0032] Examples of the starting nickel compound (Ni) include nickel nitrate, nickel sulfate, nickel chloride, nickel carbonate, and nickel acetate. The amount of nickel feedstock loaded is preferably such that the resulting catalyst satisfies Formula (1) where d=0.1 to 10, more preferably d=0.3 to 8, even more preferably d=0.5 to 5, with a=12. The range d may be as above, whereby the catalyst is allowed to have high values of conversion, unsaturated aldehyde selectivity, unsaturated carboxylic acid selectivity, and unsaturated carboxylic acid selectivity ratio.

[0033] Examples of the starting compound of iron (Fe) include iron nitrate, ferrous sulfate, ferric chloride, and ferric acetate. The amount of starting iron compound loaded is preferably such that the resulting catalyst satisfies Formula (1), where e=0.05 to 5, more preferably e=0.1 to 3, even more preferably e=0.2 to 2, with a=12. The range e may be as above, whereby the catalyst is allowed to have high values of conversion, unsaturated aldehyde selectivity, unsaturated carboxylic acid selectivity, and unsaturated carboxylic acid selectivity ratio.

[0034] The catalyst preferably further comprises sodium (Na), potassium (K), and silicon (Si). Namely, the catalyst preferably includes molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni), iron (Fe), sodium (Na), potassium (K) and silicon (Si), and the atomic ratio of molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni), iron (Fe), sodium (Na), potassium (K) and silicon (Si) in the catalyst preferably satisfies the following Formula (2):

Mo _a Bi _b Co _c Ni _d Fe _e Na _f K _g Si _h (2)

where a to h represent the atomic ratio with respect to each of the elements, and when a=12, the intervals f=0 to 2, g=0 to 2, and h=0 to 70 are satisfied, b to e are the same as b to e in Formula (1) and their preferred options are also the same as in Formula (1).

[0035] Examples of the starting sodium compound (Na) include sodium chloride, sodium carbonate, sodium nitrate, sodium sulfate, sodium acetate, and sodium borate. The amount of starting sodium compound is preferably such that the resulting catalyst satisfies Formula (2), where f=0 to 2, more preferably f=0.1 to 1, even more preferably f=0.2 to 0.5, with a =12. The f value may be a low limit or more, whereby the catalyst is allowed to have a higher unsaturated aldehyde selectivity, the unsaturated carboxylic acid selectivity, and the unsaturated carboxylic acid selectivity ratio, and the f value may be an upper limit or less, thereby enabling the catalyst to be excellent in terms of conversion rate.

[0036] Examples of the starting potassium compound (K) include potassium nitrate, potassium sulfate, potassium chloride, potassium carbonate, and potassium acetate. The amount of starting potassium compound loaded is preferably such that the resulting catalyst satisfies Formula (2), where g=0 to 2, more preferably g=0.05 to 1, even more preferably g=0.05 to 0.5, with a=12. The g value may be a low limit or more, whereby the catalyst is allowed to have a higher unsaturated aldehyde selectivity, the unsaturated carboxylic acid selectivity, and the unsaturated carboxylic acid selectivity ratio, and the g value may be an upper limit or less, thereby enabling the catalyst to be excellent in terms of conversion rate.

[0037] Examples of the original compound of silicon (Si) include silica, granular silica, colloidal silica and fine silica. The amount of silicon starting compound is preferably such that the resulting catalyst satisfies Formula (2) where h=0 to 70, more preferably h=5 to 50, even more preferably h=10 to 30, with a=12. The value of h may be a low limit or more, whereby the catalyst is allowed to be suitable in terms of dispersity of each of the components and also be excellent in terms of conversion. The value of h may be an upper limit or less, thereby allowing the catalyst to maintain a balance between the content of silicon and the contents of other metals and be excellent in terms of conversion.

[0038] Step (b) is a step of molding the powder of the catalytically active component obtained in step (a), thereby providing a shaped product. The powder of the catalytically active component in step (a), while having catalytic activity as such, is preferably densified because the catalyst is usually packed tightly in a fixed bed reactor and is used for catalytic gas phase oxidation. Such molding into a catalyst can lead to an improvement in workability during stacking and removal from the reactor, and accordingly suppresses an increase in pressure loss in catalytic gas phase oxidation. In the case where the molded catalyst has a spherical shape, the average diameter of the catalyst is preferably 2 mm to 15 mm, more preferably 3 mm to 10 mm.

The average diameter of the catalyst can be obtained by measuring the average diameter with respect to each of 100 catalyst particles with a VM-8040 high-precision two-dimensional measurement device manufactured by KEYENCE CORPORATION and determining their average value.

[0039] The method for shaping the powder of the catalytically active component may be any conventional known method, and examples thereof include the following two methods. One method is a method including allowing the carrier to flow and at the same time supplying the catalyst component powder to the flowing carrier to thereby maintain the catalyst component powder on the surface of the carrier, and performing granulation and molding to provide a molded product, ( hereinafter sometimes referred to as "rotary granulation process"). Another method is a method including placing the powder of the catalytically active component in a mold and mechanically pressing it to granulate and mold to thereby provide a molded product (hereinafter, sometimes referred to as "tabletting method").

[0040] It is preferable in the rotary drum granulation process to use a binder in order to help support the catalyst component powder on the carrier and improve the strength of the resulting catalyst. Examples of the carrier for use in the rotary drum granulation process include a spherical carrier preferably having a major axis diameter of 2.5 mm to 10 mm, even more preferably 2.5 mm to 6 mm, such as silica, silicon carbide, alumina, mullite and alund. In particular, the porosity of the carrier is preferably 20% to 60%, more preferably 30% to 57%, even more preferably 40% to 55%. The water absorption rate of the carrier is preferably 10% to 60%, more preferably 12% to 50%, even more preferably 15% to 40%. The porosity and water absorption rate of the carrier can be within the above ranges, thereby not only allowing the catalytically active component to be easily supported on the carrier, but also allowing the total pore volume (A) of the resulting catalyst to be easily within the range of this invention, and allowing the possibility for the ratio (A/B) of the total pore volume (A) to the total pore volume (B) of the pulverized product obtained by grinding the catalyst to be easily adjusted to be within the range of the present invention.

[0041] The rotary drum granulation method is, for example, a method including rotating a flat or irregular disc disposed at the bottom of a fixed container included in the granulator at a high speed, thereby vigorously agitating the carrier in the container due to repetition of rotational movement and circular motion. motion, and adding the catalyst component powder and, as appropriate, an additive such as a binder, a molding aid and/or a strength material thereto, thereby maintaining the catalyst component powder on the carrier. Examples of the additive addition method include (1) a method including mixing a catalyst component powder and the like. with the additive to obtain a homogeneous mixture, and loading the homogeneous mixture into a granulator and stirring it, (2) a method including loading a catalyst component powder and the like. and at the same time adding to the granulator and stirring the resultant mixture, (3) a method including stirring the powder of the catalytically active component and the like. in the granulator, followed by loading the additive into the granulator, and further mixing the resulting mixture, (4) a method including adding the additive to the powder of the catalytically active component and the like to obtain an inhomogeneous mixture, loading the inhomogeneous mixture into the granulator, and stirring the resultant mixture, (5) a method including mixing the powder of the catalytically active component and the like, and additives, which are each separated and loaded into the granulator at the same time, alternately or in random order. The method can also be arbitrarily adapted by combining the methods (1) to (5) in a suitable way to be added in total. Specifically, the method (5) is preferably carried out, for example, at an addition rate adjusted by using an automatic feeder such that a predetermined amount of the catalyst component powder and the like. supported on the carrier without attaching the powder of the catalytically active component to the wall of the fixed container and without aggregation of the powder of the catalytically active component. In addition, the method (5) is particularly preferred in that not only the total pore volume (A) of the obtained catalyst easily falls within the range of this invention, but also the ratio (A/B) of the total pore volume (A) to the total volume the pore (B) of the pulverized product obtained by pulverizing the catalyst is easily controlled within the range of the present invention.

[0042] Examples of the binder include organic binders such as ethanol, glycerol and polyvinyl alcohol and inorganic binders such as an aqueous solution of silicic sol, and organic binders are preferred, glycerin and polyvinyl alcohol are more preferred, and glycerin is particularly preferred. Such an organic binder, while it can be used as it is, is preferably used in the form of an aqueous solution from a workability point of view. The concentration of the aqueous solution is usually 0.1% by mass or more, preferably 2% by mass to 50% by mass, more preferably 3% by mass to 50% by mass, even more preferably 5% by mass to 50% by weight, particularly preferably from 7% by weight to 50% by weight. The amount of binder used is usually from 0.1 parts by weight to 50 parts by weight, preferably from 0.5 parts by weight to 20 parts by weight, based on 100 parts by weight of the powder of the catalytically active component, and is preferably from 1% by weight. up to 40% by weight, more preferably from 2% by weight to 35% by weight, even more preferably from 7% by weight to 30% by weight, particularly preferably from 10% by weight to 28% by weight, relative to catalyst. The binder, in particular, such as an organic binder, is used at the above aqueous solution concentration and in the above amount, thereby not only allowing the total pore volume (A) of the resulting catalyst to be easily within the range of this invention, but also allowing for the ratio (A/B) of the total pore volume (A) to the total pore volume (B) of the pulverized product obtained by grinding the catalyst, be easily adjusted to be within the range of the present invention.

[0043] Examples of a molding aid include silica, diatomaceous earth, alumina, glass, and cellulose powder. Such a molding aid may be used alone or in combination of several kinds thereof, and it is preferably used in combination of several kinds thereof. The amount of forming aid used is usually 1 part by weight to 20 parts by weight based on 100 parts by weight of the catalyst component powder. In addition, it is useful to use, if necessary, a strength enhancing material made of inorganic fiber such as ceramic fiber or whiskers to improve the strength of the catalyst. The amount of strength material used is generally 0.5 parts by weight to 20 parts by weight based on 100 parts by weight of the catalyst component powder.

[0044] It is preferable in the rotary drum granulation process to carry out the granulation at high loading so that the total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in the catalyst is within a certain range , and the ratio (A/B) of the total pore volume (A) to the total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the ground product not passing through a 6 mesh Tyler sieve, in pulverized product obtained by grinding the catalyst was in a certain range. This high loading means an improvement in impact strength between the catalyst component powder and the carrier and an increase in bond strength between the catalyst component powder and the carrier while maintaining the catalyst component powder on the carrier. It is contemplated that the catalytically active component may, as a result, penetrate the pores of the support to a lesser extent, thereby providing a ratio (A/B) in a certain range and providing a total pore volume (A) in a certain range.

[0045] In addition, the time used for granulation depends on the granulation scale, and tends to be longer when the granulation scale is increased, and the time is preferably, in the following order, from 1 minute to 140 minutes, from 1 minute to 130 minutes , 1 minute to 120 minutes, 1 minute to 110 minutes, 1 minute to 100 minutes, 1 minute to 95 minutes, 1 minute to 90 minutes, 1 minute to 85 minutes, 1 minute to 80 minutes, 1 minute to 70 minutes 1 minute to 60 minutes 1 minute to 50 minutes 1 minute to 40 minutes The time may be in a given interval, whereby the possibility of finding the ratio (A/B) in a certain interval is provided. The upper limit of the granulation time can be set up to the above time, thereby preventing the decrease in the total pore volume (A) of the catalyst due to excessive progression of integration on the catalyst surface, and thereby making it possible for the total pore volume (A) to be within a certain range.

[0046] The granulation conditions in the drum granulation process can be set to high loading, thereby making it possible to intensively maintain the catalytically active component on the surface of the support and reduce the granulation time, thereby resulting in a thinner dense bed of packed catalyst in the fixed bed reactor. .

[0047] In addition, it is important to control the total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in the catalyst to take into account the affinity between the support and the powder of the catalytically active component. The carrier generally has a high degree of water absorption and is so-called hydrophilic. The powder of the catalytically active component, when it has the same degree of hydrophilicity, easily penetrates into the pores of the carrier and makes it difficult to control the total pore volume. Accordingly, the penetration of the catalyst component powder into the carrier can be controlled by appropriately selecting a compound having low water solubility as each of the starting compounds in step (a) and adjusting the hydrophilicity of the catalyst component powder. Examples of the compound having low water solubility include bismuth subcarbonate and bismuth oxide.

[0048] The carrier for use in the tabletting process is silica, silicon carbide, alumina, mullite, alundum, or the like, and the size of the carrier is preferably the same as the size of the catalyst component powder. It is preferable to use a binder and a molding aid in order to help support the powder of the catalytically active component on the carrier and improve the mechanical strength of the resulting catalyst. It is preferable to additionally use a pore imparting material, and the pore imparting material can be used to thereby control the total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in the obtained catalyst. It is preferable in the tableting process to sufficiently mix the binder, pore-imparting material, and the like. with powder of the catalytically active component, and the like. pre and post molding the mixture to provide a molded product.

[0049] The binder and molding aid for use in the tabletting process are preferably the same as the binder and molding aid for use in the tumble granulation process, respectively, in terms of types, application modes and amounts.

Examples of the pore imparting material include an organic compound, and cellulose powder, polyvinyl alcohol, and glycerin are preferably used. The pore imparting material is released from the shaped powder by subjecting to high temperature and decomposition and/or combustion while the shaped powder is fired, thereby imparting pores thereto.

The tableting pressure in the tableting process is preferably set to a low pressure so that the total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in the catalyst is controlled. It should be noted that the pressure needs to be set to the proper pressure, taking into account the strength of the resulting catalyst.

[0050] The resulting shaped product provided by powder molding of the catalytically active component in step (b) may then be dried and calcined to thereby provide a catalyst. The pore imparting material is released from such catalyst particles due to evaporation and/or combustion during calcination, and pores are thus formed in the catalyst particles. The firing temperature is usually 250°C to 800°C, preferably 300°C to 600°C, and the firing time is 1 hour to 50 hours. Such a calcination step is preferably carried out in a stream of air in order to quickly remove the pore-imparting material released from the catalyst particles. Accordingly, a catalyst which has a high strength with a plurality of pores formed can be obtained. Moreover, a uniformly fired catalyst can be obtained by quickly removing any gas generated from the catalyst particles and introducing air to the catalyst particles. If the air flow is insufficiently supplied, the catalyst breaks down due to the change in change in pressure when the pore-forming agent is released, and thereby not only deteriorates in strength, but also deteriorates in conversion rate, unsaturated aldehyde selectivity, and unsaturated carboxylic acid selectivity.

[0051] The catalyst thus obtained is fed into a fixed bed reactor and used to react to produce an unsaturated aldehyde and an unsaturated carboxylic acid such as acrolein and acrylic acid by catalytically gas-phase oxidation of an olefin such as propylene and a gas containing oxygen. The olefin content of the gas fed to the fixed bed reactor is preferably in the range of 5% by volume to 15% by volume, and the space velocity of the olefin is preferably in the range of 50 h ^-1 to 320 h ^-1 , more preferably in the range of 80 h– ¹ to 320 h– ¹ .

The space velocity here is the quantity represented by the equation below.

Space velocity SV (h ^-1 ) = Volumetric flow rate of gaseous olefin fed into the reactor (under conditions of 0°C and 1 atm) / Volume of catalyst tightly packed in the reactor (not including any non-reactive solid)

[0052] For example, the reaction for producing acrolein and acrylic acid by catalytic gas-phase oxidation of propylene and an oxygen-containing gas is carried out by supplying a gas having a composition comprising 5% by volume to 15% by volume of propylene, 5% by volume to 18 % by volume of molecular oxygen, 0 to 40% by volume of steam, and 20% by volume to 70% by volume of an inert gas such as nitrogen gas or carbon dioxide to a fixed bed reactor where the catalyst prepared as above is placed in a tight manner. The reaction conditions preferably include a temperature range of 300°C to 450°C, a pressure of normal pressure to 150 kPa, and a catalyst contact time of 0.5 seconds to 5 seconds.

EXAMPLES

[0053] Hereinafter, this invention is more specifically described in detail with reference to Examples, however, this invention is not limited to these Examples.

[0054] <Maintenance Ratio Measurement>

Thirty catalyst particles were taken and the total weight (weight A) was measured. Thirty carrier particles were sampled and the total weight measured (weight B). The maintenance ratio was calculated according to the following equation.

Maintenance ratio (%) = (Mass A - Mass B) / Mass A × 100

[0055] <Measurement of Pore Distribution Spectrum and Total Pore Volume>

The sample was decompressed under reduced pressure (50 µm Hg or less) by using an AutoPore IV 9520 Model manufactured by Micromeritics Japan G.K. for 10 minutes, and the total pore volume for pores having a diameter of 1 µm or more to 100 µm or less, determined from the resulting mercury intrusion porosimetry curve.

[0056] <Measurement of the major axis diameter, minor axis diameter and average catalyst diameter>

One hundred catalyst particles were sampled, the major axis diameter, the minor axis diameter, and the average diameter of each of the particles were measured by a VM-8040 high-precision two-dimensional measurement device manufactured by KEYENCE CORPORATION, and thereafter, the average major axis diameter, the average diameter of minor axis and average diameter with respect to such 100 particles. In addition, the ratio of the major axis average diameter to the minor axis average diameter was calculated, and the shape of the catalyst was evaluated.

[0057] <Measurement of Catalyst Pulverization>

The catalyst was sieved through a sieve having a mesh size of 2.36 mm, and the material on the sieve was taken as a measurement sample for the degree of pulverization. A funnel (150 mm in diameter at the top of the cone and 25 mm in diameter at the bottom of the cone) was inserted into an acrylic cylinder (ø 66 mm) having a height of 1 m, and the tray was placed at the bottom of the cylinder. Approximately 20 g of the sample for measuring the degree of powdering was accurately weighed, loaded through the top section of the cone of the funnel and dropped through the cylinder onto the tray. The loaded sample for measuring the powdering ratio was removed from the tray, and sifted through a sieve having a hole size of 2.36 mm to provide fine particles, and the mass (mass of the powder material) of the fine particles was measured to calculate the powdering ratio of the catalyst according to with the equation below.

Powdering ratio (%) = (Weight of powder material/Weight of sample for measuring powdering ratio) × 100

[0058] (Example 1)

<Getting a Catalyst>

The catalytically active component was prepared according to the procedure described in Examples JP 2017-176931 A. The catalytically active component was calcined in an air atmosphere at 440°C for 6 hours, crushed and mixed with 5 parts by weight of cellulose and 5 parts by weight of glass powder as molding aids based on 100 parts by weight of the catalytically active component, thereby providing a powder including the catalytically active component (hereinafter referred to as "powder A").

[0059]

A supported shaped product was prepared by using a spherical carrier mainly including powder A, an aqueous solution of 30% by mass of glycerol, alumina and silica, in accordance with the rotary drum granulation method. Namely, 150 g of a spherical carrier (50% porosity, 20% water absorption rate) having a diameter of 4.0 mm was loaded into a Marmelizer QJ-230T-2 Model manufactured by DALTON Corporation (cylinder diameter 23 cm) and rotated at 150 rpm. min. Then, alternate addition of powder A and glycerol aqueous solution was repeated for 16 minutes, thereby maintaining powder A on the carrier to provide a supported shaped product. The amount of the aqueous glycerol solution used here was 71 parts by weight based on 100 parts by weight of powder A.

The supported shaped product was dried and fired in a cylindrical container in an air stream at 505° C. for 2 hours, thereby providing Catalyst A. The ratio of the major axis average diameter to the minor axis average diameter of Catalyst A was 1.095, the shape of the catalyst could be determined as spherical shape, and the average diameter was 5.53 mm. The degree of pulverization of catalyst A was measured and the results are summarized in Table 1.

The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in Catalyst A was 0.174 ml/g. The maintenance ratio for Catalyst A was 54%. The atomic ratio of the catalytically active elements in Catalyst A was as follows.

Mo/Bi/Co/Ni/Fe=12/2.9/3.4/3.4/0.8

[0060] <Crushing Catalyst A>

One hundred g of Catalyst A was placed in a Marmelizer QJ-230T-2 Model manufactured by DALTON Corporation (cylinder diameter 23 cm), operation was started at 300 rpm, and the rotation speed was gradually increased to 1000 rpm over 1 minute, thus most grinding for 2 minutes. Upon completion of this operation, the bulk material remaining on the Marmelizer barrel was removed and sieved through a 6 mesh Tyler sieve. The total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the ground product on the sieve was 0.213 ml/g. Based on the above, the ratio (A/B) of the total pore volume (A) to the total pore volume (B) was 0.82.

[0061] <Catalytic Gas-Phase Oxidation of Propylene>

Forty ml of Catalyst A was mixed with 52 ml of mullite beads, the resulting mixture was placed tightly in a stainless steel reactor tube, provided with a shell of saltpeter, a mixed feed gas comprising 10% v/v propylene, 17% v/v steam, 15% v/v. volume of oxygen and 58% by volume of nitrogen were introduced into the reactor tube at a pressure of 70 kPa, and the propylene oxidation reaction was carried out. The space velocity of propylene was 100 h– ¹ in this case. The results are summarized in Table 1.

[0062] The degree of conversion of propylene and selectivity (acrolein+acrylic acid) is determined as follows.

Propylene conversion rate (mole%) = (Molar amount of propylene reacted/Molar amount of propylene supplied) × 100

Selectivity of acrolein (mole%) = (Molar amount of acrolein produced/Molar amount of propylene reacted) × 100

Acrylic acid selectivity (mole%) = (Molar amount of acrylic acid produced/Molar amount of propylene reacted) × 100

[0063] (Example 2)

The catalyst component was obtained according to the procedure described in Examples JP 2017-176931 A. The catalyst component, without calcination and grinding, was mixed with 5 parts by weight of cellulose and 5 parts by weight of glass powder as forming aids, in the calculation per 100 parts by weight of the catalytically active component, thereby providing a powder including the catalytically active component (hereinafter referred to as "powder B").

A support shaped product was prepared by using a carrier mainly including powder B, an aqueous solution of 30% by mass of glycerol, alumina and silica, in accordance with the rotary drum granulation method. Namely, 5 kg of a spherical carrier (50% porosity, 20% water absorption rate) having a diameter of 4.0 mm was loaded into a rotary granulator with an inclined rotating tank having a cylinder diameter of 58 cm and rotating at 30 rpm, in the state when its bottom is tilted at 45 degrees from horizontal. Then, alternate addition of powder B and glycerol aqueous solution was repeated for 80 minutes, thereby maintaining powder B on the carrier to provide a supported shaped product. The amount of the aqueous glycerol solution used here was 34 parts by weight based on 100 parts by weight of powder B.

The supported shaped product was dried and fired in a cylindrical container in an air stream at 505° C. for 2 hours, thereby providing catalyst B. The ratio of the major axis average diameter to the minor axis average diameter of catalyst B was 1.071, the shape of the catalyst could be determined as spherical shape, and the average diameter was 5.40 mm. The degree of pulverization of catalyst B was measured and the results are summarized in Table 1.

The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in Catalyst B was 0.135 ml/g. The maintenance ratio for Catalyst B was 54%. The atomic ratio of the catalytically active elements in Catalyst B was as follows.

Mo/Bi/Co/Ni/Fe=12/2.9/3.4/3.4/0.8

[0064] Catalyst B was ground under the same conditions as in Example 1. The total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the ground product on a sieve was 0.210 ml/ G. Based on the above, the ratio (A/B) of the total pore volume (A) to the total pore volume (B) was 0.64.

Catalyst B was used to carry out the propylene oxidation reaction under the same conditions as in Example 1. The results are summarized in Table 1.

[0065] (Example 3)

A supported molded product was prepared by using a carrier mainly comprising powder A prepared in Example 1, an aqueous solution of 30% by mass of glycerol, alumina and silica, in accordance with the rotary drum granulation method under the conditions described in Example 1. this carrier was 500 g, the amount of an aqueous solution of glycerol per 100 parts by weight of powder A was 56 parts by weight, and the granulation time was 30 minutes.

The supported shaped product was dried and fired in a cylindrical container in an air stream at 505° C. for 2 hours, thereby providing Catalyst C. The ratio of the major axis average diameter to the minor axis average diameter of Catalyst C was 1.070, the shape of the catalyst could be determined as spherical shape, and the average diameter was 5.48 mm. The degree of pulverization of catalyst C was measured and the results are summarized in Table 1.

The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in Catalyst C was 0.145 ml/g. The maintenance ratio for Catalyst C was 55%. The atomic ratio of the catalytically active elements in Catalyst C was as follows.

Mo/Bi/Co/Ni/Fe=12/2.9/3.4/3.4/0.8

[0066] Catalyst C was pulverized under the same conditions as in Example 1. The total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the pulverized product on a sieve was 0.215 ml/ G. Based on the above, the ratio (A/B) of the total pore volume (A) to the total pore volume (B) was 0.67.

Catalyst C was used to carry out the propylene oxidation reaction under the same conditions as in Example 1. The results are summarized in Table 1.

[0067] (Comparative Example 1)

A supported molded product was prepared by using a carrier mainly comprising powder A prepared in Example 1, an aqueous solution of 30% by mass of glycerol, alumina and silica, in accordance with the rotary drum granulation method under the conditions described in Example 2. this carrier was 10 kg, the amount of the aqueous glycerol solution per 100 parts by weight of powder A was 31 parts by weight, and the granulation time was 140 minutes.

The supported shaped product was dried and fired in a cylindrical container in an air stream at 505° C. for 2 hours, thereby providing catalyst D. The ratio of the major axis average diameter to the minor axis average diameter of catalyst D was 1.068, the shape of the catalyst could be determined as spherical shape, and the average diameter was 5.44 mm. The powdering ratio of catalyst D was measured and the results are summarized in Table 1.

The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in catalyst D was 0.046 ml/g. The maintenance ratio for Catalyst D was 57%. The atomic ratio of the catalytically active elements in catalyst D was as follows.

Mo/Bi/Co/Ni/Fe=12/2.9/3.4/3.4/0.8

[0068] Catalyst D was used to pulverize the catalyst under the same conditions as in Example 1. The total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the pulverized product on a sieve was 0.208 ml/g. Based on the above, the ratio (A/B) of the total pore volume (A) to the total pore volume (B) was 0.22.

Catalyst D was used to carry out the propylene oxidation reaction under the same conditions as in Example 1. The results are summarized in Table 1.

[0069] (Comparative Example 2)

A supported molded product was prepared by using a carrier mainly comprising powder A prepared in Example 1, an aqueous solution of 30% by mass of glycerol, alumina and silica, in accordance with the rotary drum granulation method under the conditions described in Example 1. this carrier was 200 g, the amount of an aqueous solution of glycerol per 100 parts by weight of Powder A was 61 parts by weight, and the granulation time was 15 minutes.

The supported molded product was dried and fired in a firing capsule set in a muffle furnace at 505° C. for 2 hours, thereby providing catalyst E. The ratio of the major axis average diameter to the minor axis average diameter of catalyst E was 1.079, catalyst shape could be defined as a spherical shape, and the average diameter was 5.54 mm. The pulverization ratio of catalyst E was measured and the results are summarized in Table 1.

The total pore volume (A) for pores having a diameter of 1 µm or more to 100 µm or less in catalyst E was 0.191 ml/g. The maintenance ratio for Catalyst E was 54%. The atomic ratio of catalytically active elements in catalyst E was as follows.

Mo/Bi/Co/Ni/Fe=12/2.9/3.4/3.4/0.8

[0070] Catalyst E was used to pulverize the catalyst under the same conditions as in Example 1. The total pore volume (B) for pores having a diameter of 1 µm or more to 100 µm or less in the pulverized product on a sieve was 0.216 ml/g. Based on the above, the ratio (A/B) of the total pore volume (A) to the total pore volume (B) was 0.88.

Catalyst E was used to carry out the propylene oxidation reaction under the same conditions as in Example 1. The results are summarized in Table 1.

[0071]

[Table 1]

Catalyst pulverization ratio (%) Propylene oxidation reaction Volumetric velocity (h ^-1 ) Reaction temperature (°C) Propylene Conversion Rate (mole%) Selectivity of acrolein (mol.%) Acrylic acid selectivity (mole%) Selectivity of acrolein + acrylic acid (mol.%) Example 1 0.2 100 340 97.6 70.8 22.6 93.4 Example 2 0.6 100 340 97.3 72.4 21.2 93.6 Example 3 0.8 100 340 98.1 67.9 24.0 91.9 Comparative Example 1 0.0 100 340 97.0 65.5 26.6 92.1 Comparative Example 2 8.4 100 340 97.7 63.1 26.8 89.9

Claims (16)

1. A catalyst for the production of acrolein and acrylic acid containing molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe), and in the specified catalyst the total pore volume (A) in this catalyst for pores having a diameter of 1 µm or more to 100 µm or less is 0.12 ml/g or more to 0.19 ml/g or less, and the ratio (A/B) of the total pore volume (A) to the total pore volume (B) having a pore diameter of 1 µm or more to 100 µm or less in the ground product not passing through a 6 mesh Tyler sieve (sieve with opening size 3.36 mm), for the pulverized product obtained by pulverizing the catalyst under the pulverizing condition A, is 0.30 or more to 0.87 or less; where the refinement condition A is as follows: 100 g of the catalyst is loaded into a drum granulator which comprises a cylindrical body fixed in a vertical position and a disk placed horizontally at the lower end of the cylindrical body, and which allows rotational movement and circular movement of the particles by rotating the disk around the center of the cylindrical body, the operation of the disk start at 12 G relative centrifugal acceleration and increase to 130 G relative centrifugal acceleration for 1 minute and continue disk rotation at 130 G relative centrifugal acceleration for 2 minutes; where relative centrifugal acceleration is defined as a numerical value expressed as the ratio of the amount of centrifugal force applied per unit mass of the catalyst to the acceleration due to gravity, and is represented by the following Equation (X): F=1118 × r × N ² × 10 ^–8 Equation (X) where F: relative centrifugal acceleration (G), r: distance (cm) from the center of rotation to the lower end of the cylindrical body, N: rotation speed (rpm). 2. The catalyst according to claim 1, wherein the atomic ratio of molybdenum (Mo), bismuth (Bi), cobalt (Co), nickel (Ni) and iron (Fe) in the catalyst satisfies the following Formula (1): Mo _a Bi _b Co _c Ni _d Fe _e (1), where the values a to e represent the atomic ratio for each of the elements and, when a=12, the intervals b = 0.5 to 7, c = 0.1 to 10, d = 0.1 to 10 and e are satisfied = from 0.05 to 5. 3. The catalyst of claim. 1, where the catalyst contains a carrier. 4. The catalyst of claim. 1, where the catalyst has a spherical shape. 5. A method for producing acrolein and acrylic acid, where this method includes the step of performing catalytic gas-phase oxidation of propylene and an oxygen-containing gas using a catalyst according to any one of paragraphs. 1–4.