JPH06170237A - Catalyst formed body for production of unsaturated carboxylic acid and use thereof - Google Patents

Abstract

PURPOSE:To provide a special shape of catalyst advantageously producing unsaturated carboxylic acid from unsaturated aldehyde by vapor catalytic oxidation. CONSTITUTION:A Mo and V based catalyst formed body has a cylindrical shape with a through hole and either one of the outer periphery or the inner periphery of the cross section has an elliptical shape, and the other one has a circular shape, the center of the outer periphery coincides with the center of the inner periphery and the ratio of the minor axis to the major axis of the elliptical shape is 1.2-4.0. Thus the yield of the unsaturated acid can be improved by forming such wa catalyst shape that the pressure drop is minimized, even if the catalyst is destroyed by impact at the packing time of the catalyst, etc., by any chance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a molded catalyst used for producing an unsaturated carboxylic acid by vapor phase catalytic oxidation of an unsaturated aldehyde.

[0002]

BACKGROUND OF THE INVENTION Conventionally, a method and a catalyst for producing an unsaturated carboxylic acid by vapor-phase catalytic oxidation of an unsaturated aldehyde,
Many proposals have been made. Various catalyst shapes such as a ring shape and a wheel shape have been proposed therein. For example, JP-A-59-115750 and JP-A-2
There are reports such as Japanese Patent No. 169036. Generally, in the above-mentioned gas phase catalytic oxidation in a fixed bed, the shape of the catalyst and the size of the catalyst body influence the pressure drop of the catalyst deposit, and the pressure drop increases, so that the desired product is selected. It is known to affect sexuality. Therefore, the shape having the through hole has a small pressure drop and is excellent in this respect.

However, the shape having through-holes has a lower mechanical strength of the catalyst body than the shape having no through-holes, and breaks during handling or use to increase small fragments of catalyst particles, fine powder and dust. As a result, on the contrary, the pressure drop increases, which adversely affects the selectivity. In particular, the concentric ring-shaped structure is often divided into four as shown in FIG. 3 when it is broken during handling or use. Since the small pieces of the catalyst divided into four parts increase the pressure drop and adversely affect the selectivity, it is the current situation that further improvement is desired in the use as an industrial catalyst.

[0004]

DISCLOSURE OF THE INVENTION The present invention uses a catalyst having a shape having a through hole to minimize the pressure drop even if a small particle of the catalyst particle is generated due to breakage during handling or during use. It is an object of the present invention to provide a novel catalyst molded body that advantageously produces unsaturated carboxylic acid from unsaturated aldehyde.

[0005]

In the concentric ring-shaped structure, the mechanical strength of the catalyst body is excellent in the direction perpendicular to the cross section, but the mechanical strength is small in the direction perpendicular to the side surface. Moreover, when it breaks in the direction perpendicular to this side surface, it is often divided into four as shown in FIG. This comes from a concentric ring-shaped structure, and when divided into four, the catalyst gap is reduced, and small fragments, fine powder and dust are generated, resulting in a pressure drop. Therefore, by giving a structurally weak portion to the concentric ring-shaped structure in advance, by increasing excessive force in the direction perpendicular to the side surface and breaking it, it is often divided into two.
Minimize the generation of small debris, fines and dust, resulting in
Since the increase in pressure drop is reduced, the adverse effect on the selectivity of the desired product is suppressed.

The present invention has a cylindrical shape having a through hole, the cross section of which has either an outer circumference or an inner circumference having an essentially elliptical shape, and the other has a circular shape. Of the catalyst, the centers of which coincide with each other, and the ratio of the longest distance to the shortest distance on the elliptical shape from the center is 1.2 to 4.0, and the gas of unsaturated aldehyde containing at least molybdenum and vanadium as catalyst components. It is a catalyst for the production of unsaturated carboxylic acids by phase contact oxidation.

The essentially elliptical shape according to the present invention means not only an ellipse based on mathematical grounds but also an essentially elliptical shape that can inscribe a rectangle and an essentially elliptical shape that can circumscribe a rhombus. It also includes those with.
In the present invention, when the ratio of the longest distance to the shortest distance on the elliptical shape from the center is less than 1.2, there is almost no difference from the concentric ring-shaped form, and excessive force is exerted in the direction perpendicular to the side surface. When it is added, it is often divided into four, and the effect of the present invention is not obtained. On the other hand, if this ratio exceeds 4.0, the proportion of the through holes in the catalyst cross section decreases, and the effects of the through holes such as reduction of pressure drop or improvement of diffusion efficiency are reduced.

In the present invention, it is important that either the outer circumference or the inner circumference has a through hole and has an essentially elliptical shape, and the other is a circle. Either the outer circumference or the inner circumference has an essentially elliptical shape, so that when a force is excessively applied in a direction perpendicular to the side surface, a structurally weak portion is cracked (FIGS. 1 and 2). In other words, since it is often divided into two, the reduction of the catalyst gap and the generation of small fragments, fine powder and dust can be minimized.

In the present invention, when the outer circumference is essentially elliptical, the ratio of the shortest distance on the outer circumference to the radius of the inner circumference from the center is preferably 1.1 to 8.0. If this ratio is less than 1.1, the mechanical strength in the direction perpendicular to the side surface is significantly reduced, which is not preferable. Further, if this ratio exceeds 8.0, the proportion of the through holes in the cross section of the catalyst body decreases, and the effect of the through holes such as reduction of pressure drop or improvement of diffusion efficiency decreases, which is not preferable. . Conversely, if the inner circumference is essentially elliptical, the ratio of the outer radius to the longest distance on the inner circumference from the center is 1.1-
8.0 is preferable. If this ratio is less than 1.1, the mechanical strength in the direction perpendicular to the side surface is significantly reduced, which is not preferable. On the other hand, when it exceeds 8.0, the ratio of the through holes of the catalyst body decreases, and the effect of the central hole such as reduction of pressure drop or improvement of diffusion efficiency decreases, which is not preferable.

In the present invention, the length (height) of the catalyst body is preferably 1.0 to 5.0 times the shortest distance on the outer circumference from the center. When the length of the catalyst is less than 1.0 times the shortest distance on the outer circumference from the center, the mechanical strength of the catalyst body is significantly reduced, which is not preferable. Further, if the length exceeds 5.0 times the shortest distance on the outer circumference from the center, the effect of the through hole such as the improvement of diffusion efficiency is reduced, which is not preferable. In the present invention, in the shape of the catalyst, specifically, the shortest distance from the center of the catalyst cross section to the outer periphery is 1 to 10 m.
The range of m and the length of 2 to 15 mm is preferable.

The catalyst can be molded by a usual extrusion molding machine or tablet molding machine. When molding the present catalyst, conventionally known additives, for example, organic compounds such as polyvinyl alcohol and carboxymethyl cellulose, inorganic compounds such as graphite and diatomaceous earth, and inorganic fibers may be further added. The shaped catalyst thus obtained is then heat treated. In the present invention, the processing conditions are not particularly limited, and known processing conditions can be applied. Generally, heat treatment is 300-5
It is carried out at 00 ° C.

The method for preparing the catalyst used in the present invention does not have to be limited to a special method, and the evaporation dryness method, the precipitation method, the oxidation method, which are well known in the art, can be used unless significant uneven distribution of the components is involved. Various methods such as a material mixing method can be used. As a raw material used for preparing the catalyst, an oxide of each element, a nitrate, a carbonate, an ammonium salt, a halide or the like can be used in combination. For example, ammonium paramolybdate, molybdenum trioxide, molybdenum chloride, etc. can be used as the molybdenum raw material, and ammonium metavanadate, vanadium pentoxide, vanadium chloride, etc. can be used as the vanadium raw material.

The catalyst obtained by the method of the present invention may be diluted with an inert carrier such as silica, alumina, silica-alumina, magnesia, titania or silicon carbide before use. When the unsaturated carboxylic acid is produced using the catalyst obtained by the method of the present invention, the concentration of the unsaturated aldehyde in the raw material gas can be varied over a wide range, but the volume is preferably 1 to 20%. And especially 3-10%
Is preferred.

The starting unsaturated aldehyde may contain a small amount of impurities such as water and lower saturated aldehyde, and these impurities do not substantially affect the reaction. It is economical to use air as the oxygen source, but if necessary, air enriched with pure oxygen can also be used. The oxygen concentration in the raw material gas is defined by the molar ratio to the unsaturated aldehyde, and this value is preferably 0.3 to 4, and particularly 0.4 to 2.5. The raw material gas may be diluted by adding an inert gas such as nitrogen, steam or carbon dioxide gas. The reaction pressure is preferably atmospheric pressure to several atmospheres. The reaction temperature can be selected in the range of 200 to 450 ° C, but 210 to 400 ° C is particularly preferable.

Examples of the production of unsaturated carboxylic acid by vapor phase catalytic oxidation of unsaturated aldehyde in the present invention include production of acrylic acid by oxidation of acrolein and production of methacrylic acid by oxidation of methacrolein.

[0016] As the catalyst for production of acrylic acid by oxidation of acrolein, the general formula _{Mo a V b A c X d} Y e O f ( wherein wherein Mo, V and O represent molybdenum,
Represents vanadium and oxygen, A represents at least one element selected from the group consisting of iron, cobalt, chromium, aluminum and strontium, X represents germanium, boron, arsenic, selenium, silver, silicon, sodium,
At least one element selected from the group consisting of tellurium, lithium, antimony, phosphorus, potassium and barium is shown, and Y is magnesium, titanium, manganese, copper, zinc, zirconium, niobium, tungsten, tantalum,
At least one element selected from the group consisting of calcium, tin and bismuth is shown. a, b, c, d, e and f represent the atomic ratio of each element, and when a = 12, b = 0.
01-6, c = 0.1-5, d = 0-10, e = 0-5
And f is the number of oxygen atoms required to satisfy the valence of each component. ) The thing which has a composition represented by these is mentioned.

Further, as a catalyst for producing methacrylic acid by oxidation of methacrolein, a compound represented by the general formula P _a Mo _b V _c Cu _d X _e Y _f Z _g O _h (wherein P, Mo, V, Cu and O are used) Represents phosphorus, molybdenum, vanadium, copper and oxygen, and X represents at least one element selected from the group consisting of arsenic, antimony, bismuth, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron. , Y represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, manganese, cobalt, barium, gallium, cerium and lanthanum, and Z represents potassium, rubidium, cesium and thallium. At least one element selected from the group consisting of a, b, c, d, e, f, g and h is Atomic ratio, a = 0.5 to 3, c when b = 12
= 0.01 to 3, d = 0 to 2, e = 0 to 3, f = 0
3, g = 0.01 to 3, and h is the number of oxygen atoms required to satisfy the valence of each component. ) The thing which has a composition represented by these is mentioned.

[0018]

EXAMPLES The method for producing the catalyst according to the present invention and the reaction examples using the same will be specifically described below. In Examples and Comparative Examples, the reaction rate of unsaturated aldehyde and the selectivity of unsaturated carboxylic acid produced are defined as follows.

[0019]

[Equation 1]

Further, the filling powdering rate and the shape change rate of the molded catalyst are defined as follows. 100 parts of the molded catalyst is weighed, and the number of molded catalysts is X at this time. Next, a weighed molded catalyst is filled from the upper portion of the stainless steel tube into a stainless steel tube having an inner diameter of 30 mmφ and a length of 5 m installed vertically to the horizontal direction, and after the filling, the recovered catalyst is collected from the lower portion of the stainless steel tube. Of the recovered catalysts, the catalyst that does not pass through the 8-mesh sieve is part a, and the number of catalysts that did not pass through the 8-mesh sieve at this time is Y, and the packing powdering rate and the shape change rate are Is represented as follows.

[0021]

[Equation 2] Parts in the following Examples and Comparative Examples are parts by weight, and analysis was by gas chromatography.

Example 1 100 parts of ammonium paramolybdate, 2.2 parts of ammonium metavanadate and 4.8 parts of potassium nitrate were dissolved in 400 parts of pure water. While stirring the solution, a solution prepared by dissolving 8.2 parts of 85% phosphoric acid in 10 parts of pure water was added, and further a solution prepared by dissolving 0.6 parts of copper nitrate in 10 parts of pure water was added. Next, after adding a solution of 2.8 parts of zinc nitrate dissolved in 10 parts of pure water, the temperature was raised to 95 ° C. 60% arsenic acid 2.
A solution prepared by dissolving 2 parts in 10 parts of pure water was added, followed by 2.1 parts of antimony trioxide and 1.0 part of germanium dioxide. The mixture was evaporated to dryness with heating and stirring, and then the obtained solid was dried at 130 ° C. for 16 hours.

The degree of polymerization is 500 with respect to 100 parts of this dry powder.
3 parts of polyvinyl alcohol and 15 parts of water are mixed, and the outer circumference is a circle with a radius of 3.0 mm and the inner circumference has a longest distance of 2.0 mm from the center and a shortest distance of 1.0 by an extruder.
It was extruded into a concentric cylinder having an average length of 5.0 mm, which is an elliptical shape of mm. The shaped catalyst was dried at 130 ° C. for 6 hours, and then heat-treated at 380 ° C. for 5 hours under air flow to be used as a catalyst. The composition of elements other than oxygen in the obtained catalyst (the same applies hereinafter) was P _1.5 Mo ₁₂ V _0.4 Cu.
_{It was 0.05} Ge _0.2 As _0.2 Zn _0.2 K ₁ . The catalyst was filled in a reaction tube, and a mixed gas of methacrolein 5%, oxygen 10%, water vapor 30%, and nitrogen 55% (volume%) was passed at a reaction temperature of 290 ° C. and a contact time of 3.6 seconds. When the product was collected and analyzed by gas chromatography, the reaction rate of methacrolein was 85.8% and the selectivity of methacrylic acid was 85.
It was 2%. In addition, the filling powder ratio was 1.8% and the shape change ratio was 7.2%.

Example 2 In Example 1, the catalyst particles had an elliptical shape with a maximum outer circumference of 3.0 mm and a shortest distance of 2.5 mm, and an inner circumference of a circle having a radius of 1.25 mm. Average length is 5.
Example 1 except that it was formed into a cylindrical shape of 0 mm concentric circles.
Molding and reaction were carried out in the same manner as in. As a result, the methacrolein conversion rate was 85.9% and the methacrylic acid selectivity was 8
It was 5.4%. In addition, the filling powder ratio was 1.5% and the shape change ratio was 6.8%.

Comparative Example 1 The shape of the catalyst particles in Example 1 was 3.0 m on the outer circumference.
Molding and reaction were carried out in the same manner as in Example 1 except that the inner circumference was a circle having a radius of 1.5 mm and the concentric circles had an average length of 5.0 mm. as a result,
The methacrolein conversion was 85.5% and the methacrylic acid selectivity was 84.8%. In addition, the filling powder ratio was 4.5% and the shape change ratio was 12.0%.

Example 3 100 parts of molybdenum trioxide, 4.2 parts of vanadium pentoxide
Parts, boric acid 0.4 parts, antimony pentoxide 4.7 parts and 8 parts
6.7 parts of 5% phosphoric acid are mixed with 800 parts of pure water. After heating and stirring this for 3 hours under reflux, 0.5 part of copper oxide, 0.9 part of cobalt oxide and 0.8 part of manganese nitrate were added, and the mixture was again heated and stirred for 2 hours under reflux. This slurry at 50 ° C
After cooling to 11.2 parts of cesium bicarbonate dissolved in 30 parts of pure water, the mixture is stirred for 15 minutes. Next, a solution prepared by dissolving 10 parts of ammonium nitrate in 30 parts of pure water was added,
The mixed solution was evaporated to dryness with heating and stirring at 100 ° C. After drying the obtained solid matter for 16 hours at 120 ° C., the shape of the catalyst particles in Example 1 was determined such that the outer circumference was a circle with a radius of 3.0 mm, the inner circumference had a longest distance from the center of 1.5 mm, and the shortest distance. Was shaped in the same manner as in Example 1 except that it was in the form of a concentric cylinder having an average length of 5.0 mm and an elliptical shape of 1.0 mm. Drying the shaped catalyst at 130 ° C. for 6 hours,
Then, the one heat-treated at 380 ° C. for 5 hours under air flow was used as a catalyst. The composition of the resulting catalyst was P ₁ Mo ₁₂
V _0.0 Cu _0.2 B _0.1 Sb _0.5 Co _0.2 Mn _0.05 Cs ₁
Met. When this catalyst was used and the reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 270 ° C., the methacrolein conversion rate was 89.9% and the methacrylic acid selectivity was 8%.
It was 8.3%. Further, the filling powdering rate was 1.2% and the shape change rate was 6.3%.

Example 4 In Example 3, the shape of the catalyst particles was elliptical with the longest distance from the center being 3.0 mm and the shortest distance being 2.5 mm, and the inner circumference being a circle with a radius of 1.0 mm. Average length is 5.0
Molding and reaction were carried out in the same manner as in Example 3 except that the shape of the cylinder was concentric circles of mm. As a result, the methacrolein conversion rate was 89.8% and the methacrylic acid selectivity was 88.
It was 1%. In addition, the filling powder ratio was 1.4% and the shape change ratio was 7.0%.

Comparative Example 2 The shape of the catalyst particles in Example 3 was 3.0 m on the outer circumference.
Molding and reaction were performed in the same manner as in Example 3 except that the inner circumference was a circle having a radius of 1.0 mm and the concentric circles had an average length of 5.0 mm. as a result,
The methacrolein conversion was 89.4% and the methacrylic acid selectivity was 87.8%. Further, the filling powdering rate was 4.0% and the shape change rate was 10.8%.

Example 5 100 parts of ammonium paramolybdate and 16.6 parts of ammonium metavanadate were dissolved in 1000 parts of pure water. A solution prepared by dissolving 15.3 parts of ferric nitrate in 200 parts of pure water was added thereto, and a solution prepared by dissolving 6.9 parts of cobalt nitrate in 200 parts of pure water, and 0.6 parts of silver nitrate in 50 parts of pure water. The solution dissolved in was sequentially added. Next, the general formula Na ₂ O.
Water glass 4, represented by 2.2SiO ₂ · 2.2H ₂ O.
A solution prepared by dissolving 5 parts in 30 parts of pure water was added, and further 20
% Silica sol 50.9 parts was added. The mixture was evaporated to dryness with heating and stirring, and the solid obtained was heated to 130 ° C.
And dried for 16 hours.

To 100 parts of this dry powder, 18 parts of ethyl alcohol and 5 inorganic fibers having an average length of 200 μm
The parts were mixed and extruded into the same shape as in Example 1 using an extruder. The shaped catalyst was dried at 130 ° C. for 6 hours, and then heat-treated at 380 ° C. for 5 hours under air flow to be used as a catalyst. The composition of the obtained catalyst was Mo ₁₂ V ₃ F
e _0.8 Si _4.5 Na _0.8 Co _0.5 Ag _0.08 . The reaction tube was filled with this catalyst, and acrolein 5%, oxygen 10
%, Steam 30%, and nitrogen 55% (volume%) were passed through at a reaction temperature of 270 ° C. and a contact time of 3.6 seconds. When the product was collected and analyzed by gas chromatography,
Acrolein conversion 99.5%, acrylic acid selectivity 9
It was 3.4%. In addition, the filling powder ratio was 1.7% and the shape change ratio was 7.0%.

Example 6 Molding and reaction were carried out in the same manner as in Example 5 except that the shape of the catalyst particles in Example 5 was the same as in Example 2. As a result, the acrolein conversion was 99.5% and the acrylic acid selectivity was 93.6%. In addition, the filling powder ratio is 1.
It was 8% and the shape change rate was 7.2%.

Comparative Example 3 Molding and reaction were carried out in the same manner as in Example 5 except that the shape of the catalyst particles was the same as in Comparative Example 1. As a result, the acrolein conversion was 99.3% and the acrylic acid selectivity was 92.7%. Further, the filling powder ratio is 4.
It was 7% and the shape change rate was 11.6%.

[0033]

The catalyst prepared by the method of the present invention has the effect of improving the yield of unsaturated carboxylic acid produced in the gas phase catalytic oxidation reaction of unsaturated aldehydes.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a catalyst of the present invention.

FIG. 2 is a cross-sectional view of another catalyst of the present invention.

FIG. 3 is a cross-sectional view of a conventional catalyst

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[Procedure amendment]

[Submission date] May 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Example 1 100 parts of ammonium paramolybdate, 2.2 parts of ammonium metavanadate and 4.8 parts of potassium nitrate were dissolved in 400 parts of pure water. While stirring the solution, a solution prepared by dissolving 8.2 parts of 85% phosphoric acid in 10 parts of pure water was added, and further a solution prepared by dissolving 0.6 parts of copper nitrate in 10 parts of pure water was added. Next, after adding a solution of 2.8 parts of zinc nitrate dissolved in 10 parts of pure water, the temperature was raised to 95 ° C. 60% arsenic acid 2.
A solution prepared by dissolving 2 parts in 10 parts of pure water was added, followed by 1.0 part of germanium dioxide. The mixture was evaporated to dryness with heating and stirring, and the solid obtained was heated to 130 ° C.
And dried for 16 hours.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Example 3 100 parts of molybdenum trioxide, 4.2 parts of vanadium pentoxide
Parts, boric acid 0.4 parts, antimony pentoxide 4.7 parts and 8 parts
6.7 parts of 5% phosphoric acid are mixed with 800 parts of pure water. After heating and stirring this for 3 hours under reflux, 0.5 part of copper oxide, 0.9 part of cobalt oxide and 0.8 part of manganese nitrate were added, and the mixture was again heated and stirred for 2 hours under reflux. This slurry at 50 ° C
After cooling to 11.2 parts of cesium bicarbonate dissolved in 30 parts of pure water, the mixture is stirred for 15 minutes. Next, a solution prepared by dissolving 10 parts of ammonium nitrate in 30 parts of pure water was added,
The mixed solution was evaporated to dryness with heating and stirring at 100 ° C. After drying the obtained solid matter for 16 hours at 120 ° C., the shape of the catalyst particles in Example 1 was determined such that the outer circumference was a circle with a radius of 3.0 mm, the inner circumference had a longest distance from the center of 1.5 mm, and the shortest distance. Was shaped in the same manner as in Example 1 except that it was in the form of a concentric cylinder having an average length of 5.0 mm and an elliptical shape of 1.0 mm. Drying the shaped catalyst at 130 ° C. for 6 hours,
Then, the one heat-treated at 380 ° C. for 5 hours under air flow was used as a catalyst. The composition of the resulting catalyst was P ₁ Mo ₁₂
V _0.8 Cu _0.2 B _0.1 Sb _0.5 Co _0.2 Mn _0.05 Cs ₁
Met. When this catalyst was used and the reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 270 ° C., the methacrolein conversion rate was 89.9% and the methacrylic acid selectivity was 8%.
It was 8.3%. Further, the filling powdering rate was 1.2% and the shape change rate was 6.3%.

Claims (2)

[Claims] 1. A cylindrical shape having a through-hole, the cross section of which has either an outer circumference or an inner circumference having an essentially elliptical shape, and the other is a circle, and the center of the outer circumference and the inner circumference. And the ratio of the longest distance to the shortest distance on the elliptical shape from the center is 1.2 to 4.0,
A catalyst molded body for producing an unsaturated carboxylic acid by vapor-phase catalytic oxidation of an unsaturated aldehyde containing at least molybdenum and vanadium as a catalyst component. 2. A process for producing an unsaturated carboxylic acid by vapor-phase catalytic oxidation of an unsaturated aldehyde using the molded catalyst according to claim 1.