JP3251642B2 - Preparation of catalyst for unsaturated carboxylic acid production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a catalyst used for producing an unsaturated carboxylic acid by gas 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 subjecting an unsaturated aldehyde to catalytic oxidation in the gas phase are disclosed.
Many suggestions have been made. Some of them use alcohols, nitrogen-containing heterocyclic compounds and other various compounds at the time of catalyst preparation. For example, JP-A-60-2
39439 and JP-A-55-73347. However, these have drawbacks such as insufficient reaction results, a large decrease in catalytic activity with time, and complicated post-treatment, and further improvement is currently desired when used as an industrial catalyst. is there.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing a novel catalyst which advantageously produces an unsaturated carboxylic acid from an unsaturated aldehyde.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to improve the conventional catalyst preparation method, and as a result, the moldability of the catalyst has been improved and the unsaturated carboxylic acid has a higher yield than the conventional method. A new method for preparing the catalyst obtained in the above was found. The present invention relates to a catalyst for producing an unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gas phase contact oxidation with molecular oxygen to produce an unsaturated carboxylic acid, wherein at least a catalyst component containing molybdenum and vanadium is added to activated carbon powder having an average particle size of 1 to 500 μm. Add and shape,
This is a method for preparing a catalyst for producing an unsaturated carboxylic acid, which is characterized by performing a heat treatment.

[0005] In the present invention, it is important that activated carbon powder having a particle size in a specific range is added at the time of shaping the catalyst. If the average particle size of the activated carbon powder is less than 1 μm, the effect of adding the activated carbon powder is small in spite of complicated handling such as secondary agglomeration of the used activated carbon powder and easy dusting. On the other hand, if the average particle diameter of the activated carbon powder to be added exceeds 500 μm, the mechanical strength as an industrial catalyst becomes weak, which is not preferable.

The amount of the activated carbon powder to be added is suitably from 0.1 to 20% by weight based on the catalyst, especially from 0.5 to 1% by weight.
0% by weight is preferred. When the content of the activated carbon powder is less than 0.1% by weight of the catalyst, the effect of the addition of the activated carbon powder is small, and when it exceeds 20% by weight, the moldability at the time of shaping deteriorates and the catalyst is suitable as an industrial catalyst. Disappears. When the catalyst and the activated carbon powder are mixed, conventionally known additives such as polyvinyl alcohol, carboxymethyl cellulose, and inorganic fibers may be further added.

[0007] In the present invention, the method of shaping the catalyst by mixing the catalyst and the activated carbon powder and the shape thereof are not particularly limited, and a general method such as a tableting machine, an extruder, a tumbling granulator and the like is used. It can be shaped into an arbitrary shape such as a spherical shape, a ring shape, a cylindrical shape, and a star shape using a suitable powder molding machine. The size (diameter, length, etc.) of the shaped catalyst is suitably 3 to 10 mm. 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. Usually, the heat treatment is performed at 300 to 500C.

The method for preparing the catalyst used in the present invention does not need to be limited to a special method. Unless accompanied by a significant uneven distribution of components, well-known evaporation-drying methods, precipitation methods, oxidation methods Various methods such as a substance mixing method can be used. As the raw materials used for preparing the catalyst, oxides, nitrates, carbonates, ammonium salts, halides and the like of each element can be used in combination. For example, as a molybdenum raw material, ammonium paramolybdate, molybdenum trioxide, molybdenum chloride and the like can be used, and as a vanadium raw material, ammonium metavanadate, vanadium pentoxide, vanadium chloride and the like can be used.

Although the catalyst obtained by the method of the present invention is effective without a carrier, it is supported on an inert carrier such as silica, alumina, silica-alumina, magnesia, titania, silicon carbide, or diluted with the carrier. It can also be used. When producing an unsaturated carboxylic acid using the catalyst obtained by the method of the present invention, the concentration of the unsaturated aldehyde in the raw material gas can be changed in a wide range, but 1 to 20% by volume is appropriate. And especially 3 to 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. Although it is economical to use air as the oxygen source, air enriched with pure oxygen can be used if necessary. The oxygen concentration in the source gas is defined by the molar ratio to the unsaturated aldehyde, and this value is preferably from 0.3 to 4, particularly preferably from 0.4 to 2.5. The source gas may be diluted by adding an inert gas such as nitrogen, steam, or carbon dioxide. The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature can be selected in the range of 230 to 450 ° C., and particularly preferably 250 to 400 ° C. The reaction can be carried out in a fixed bed or a fluidized bed.

Examples of the production of unsaturated carboxylic acids by gas phase catalytic oxidation of unsaturated aldehydes in the present invention include production of acrylic acid by oxidation of acrolein and production of methacrylic acid by oxidation of methacrolein. The catalyst for acrylic acid production 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 each represent molybdenum, vanadium and oxygen, A is iron, Cobalt, chrome,
X represents at least one element selected from the group consisting of aluminum and strontium, and X is selected from the group consisting of germanium, boron, arsenic, selenium, silver, silicon, sodium, tellurium, lithium, antimony, phosphorus, potassium, and barium. Y represents magnesium, titanium, manganese, copper, zinc,
At least one element selected from the group consisting of zirconium, niobium, tungsten, tantalum, calcium, tin and bismuth. 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 to 5, d = 0 to 10, e = 0 to 5, and f is the number of oxygen atoms necessary to satisfy the valence of each component. )).

Further, as the production of methacrylic acid catalyst for the oxidation of methacrolein, the general formula _{P a Mo b V c Cu d} X e Y f Z g O h ( wherein wherein P, Mo, V, Cu and O Represents phosphorus, molybdenum, vanadium, copper and oxygen, respectively, 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. And at least one element selected from the group consisting of: a, b, c, d, e, f, g, and h Represents the atomic ratio, a = 0.5-3 when b = 12, c
= 0.01-3, d = 0-2, e = 0-3, f = 0
3, g = 0.01-3, and h is the number of oxygen atoms necessary to satisfy the valence of each component. )).

[0013]

EXAMPLES Hereinafter, a method for preparing a catalyst according to the present invention and a reaction example using the same will be specifically described. In Examples and Comparative Examples, the conversion of unsaturated aldehyde and the selectivity of unsaturated carboxylic acid to be formed are defined as follows.

[0014]

(Equation 1)

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

Example 1 100 parts of ammonium paramolybdate and 16.6 parts of ammonium metavanadate were dissolved in 1000 parts of pure water. To this was added a solution of 19.1 parts of ferric nitrate dissolved in 200 parts of pure water, followed by a solution of 2.5 parts of barium nitrate dissolved in 200 parts of pure water. Next, the general formula Na
₂ O · 2.2SiO ₂ · 2.2H ₂ O-3.9 parts of water glass represented a solution prepared by dissolving 30 parts of pure water was further added 20% silica sol 52.4 parts. The mixture was evaporated to dryness while heating and stirring, and the obtained solid was dried at 130 ° C. for 16 hours.

20 parts of water, 5 parts of activated carbon powder having an average particle size of 50 μm and an average length of 200 μ
m of inorganic fiber were mixed and molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and an average length of 4 mm using an extruder. Drying the shaped catalyst at 130 ° C. for 6 hours,
Next, a material that had been heat-treated at 380 ° C. for 5 hours while flowing air was used as a catalyst. The composition of elements other than oxygen in the obtained catalyst (the same applies hereinafter) is Mo ₁₂ V ₃ Fe ₁ Si _4.5 Na _0.7
Ba was _0.2 . This catalyst was charged into a reaction tube, and a mixed gas of acrolein 5%, oxygen 10%, steam 30%, and nitrogen 55% (volume%) was reacted at 270 ° C. for a contact time of 3.6.
Seconds passed. The product was collected and analyzed by gas chromatography. As a result, the reaction rate of acrolein was 99.5% and the selectivity of acrylic acid was 95.5%.

Comparative Example 1 A molding and reaction were carried out in the same manner as in Example 1 except that the activated carbon powder mixed with 100 parts of the dry powder had an average particle size of 0.5 μm. As a result, the acrolein conversion was 98.9%, and the selectivity for acrylic acid was 95.2%.

Comparative Example 2 Molding was performed in the same manner as in Example 1 except that the average particle size of the activated carbon powder mixed with 100 parts of the dry powder was 10,000 μm. However, the mechanical strength was weak, and a shaped product usable as an industrial catalyst could not be obtained.

Comparative Example 3 A molding and a reaction were performed in the same manner as in Example 1 except that no activated carbon powder was added. As a result, the acrolein conversion was 98.9%, and the selectivity for acrylic acid was 95.0%.

Example 2 According to Example 1, Mo ₁₂ V _3.5 Fe _0.7 Sr _0.5 Co _0.5
A mixed solution containing a catalyst component of Si _4.5 Na _0.7 Ag _0.08 was prepared, evaporated to dryness, and the obtained solid was dried at 130 ° C. for 16 hours. To 100 parts of the dried powder , 3 parts of activated carbon powder having an average particle diameter of 100 μm were mixed, and molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and an average length of 4 mm by a tableting machine. This was heat-treated at 380 ° C. for 5 hours under air flow and used as a catalyst. Using this catalyst, a reaction was carried out under the same conditions as in Example 1. as a result,
Acrolein conversion 99.6%, acrylic acid selectivity 9
It was 4.1%.

Comparative Example 4 A molding and a reaction were performed in the same manner as in Example 2 except that no activated carbon powder was added. As a result, the acrolein conversion was 99.3%, and the selectivity for acrylic acid was 93.2%.

Example 3 According to Example 1, Mo ₁₂ V ₃ Fe ₁ Si _4.5 Na _0.7
A mixed solution containing a catalyst component of Sn _0.4 Mn _0.1 Ta _0.2 was prepared, and evaporated to dryness.
For 16 hours. 100 parts of this dry powder is mixed with water 2
0 parts, 5 parts of activated carbon powder having an average particle size of 50 μm, and 10 parts of inorganic fibers having an average length of 200 μm were mixed and granulated into a sphere having an average particle size of 5 mm using a tumbling granulator. The granulated catalyst is dried at 130 ° C. for 6 hours and then
What was heat-processed at 5 degreeC for 5 hours was used as a catalyst. Using this catalyst, a reaction was carried out under the same conditions as in Example 1. As a result, the conversion of acrolein was 99.6%, and the selectivity for acrylic acid was 95.1%.

Comparative Example 5 Granulation and reaction were carried out in the same manner as in Example 3 except that no activated carbon powder was added. As a result, the acrolein conversion was 98.9%, and the selectivity for acrylic acid was 94.7%.

Example 4 100 parts of ammonium paramolybdate, 4.42 parts of ammonium metavanadate and 4.77 parts of potassium nitrate were dissolved in 400 parts of pure water. While stirring this, 85
A solution of 8.16 parts of phosphoric acid in 10 parts of pure water was added, and a solution of 1.14 parts of copper nitrate in 10 parts of pure water was further added. Next, 6.96 parts of 60% nitric acid and 40 parts of pure water were added to 6.87 parts of bismuth nitrate, and the obtained homogeneous solution of bismuth nitrate was added to the mixture, and then the temperature was raised to 95 ° C. To this was added a solution of 2.23 parts of 60% arsenic acid in 10 parts of pure water, followed by 2.06 parts of antimony trioxide and 1.62 parts of cerium dioxide. The mixture was evaporated to dryness while heating and stirring, and the resulting solid was
Dry at 0 ° C. for 16 hours.

The degree of polymerization is 500 per 100 parts of the dried powder.
3 parts of polyvinyl alcohol, 15 parts of water and average particle size 3
Seven parts of 0 μm activated carbon powder were mixed and molded into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and an average length of 5 mm by an extruder. Drying the shaped catalyst at 130 ° C. for 6 hours,
Next, a material that had been heat-treated at 380 ° C. for 5 hours while flowing air was used as a catalyst. The composition of the obtained catalyst is P _1.5 Mo
₁₂ V _0.8 Cu _0.1 Sb _0.3 Bi _0.3 As _0.2 Ce _0.2 K
_{Was one} . The catalyst was charged into a reaction tube, and a mixed gas of methacrolein 5%, oxygen 10%, steam 30%, and nitrogen 55% (volume%) was passed at a reaction temperature of 290 ° C and a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography to find that the conversion of methacrolein was 91.3% and the selectivity of methacrylic acid was 88.5%.

Comparative Example 6 A molding and reaction were carried out in the same manner as in Example 4 except that no activated carbon powder was added. As a result, the conversion of methacrolein was 90.1% and the selectivity of methacrylic acid was 88.4%.

[0028]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-169538 (JP, A) JP-A-60-150834 (JP, A) JP-A-57-59639 (JP, A) 24183 (JP, A) JP-A-5-138028 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 C07C 51/235 C07C 57/05

Claims (1)

(57) [Claims] 1. An unsaturated aldehyde obtained by gas phase catalytic oxidation of an unsaturated aldehyde, wherein activated carbon powder having an average particle size of 1 to 500 μm is added to a catalyst component containing at least molybdenum and vanadium, followed by shaping and heat treatment. Method for preparing catalyst for carboxylic acid production.