JP2892868B2 - Manufacturing method of molded catalyst - 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 producing a molded catalyst having pores, excellent moldability and high mechanical strength.

[0002]

2. Description of the Related Art Generally, a molded catalyst used industrially is used by mixing a catalyst raw material composition and a molding aid, molding and then heat-treating the mixture. It is necessary to have a mechanical strength that does not cause powdering and collapse when performing.

As a method for increasing the mechanical strength of a molded catalyst, there is a dry tableting method in which a molding aid is added to a raw material catalyst composition. For example, Japanese Patent Publication No. 56-38261 proposes a method of adding and molding talc and graphite. However, the dry tableting method has a drawback that when the molding pressure is increased in order to impart strength to the catalyst, pores effective for reaction and gas diffusion are easily crushed.

[0004] As a method for solving this problem, there is an extrusion molding method. In extrusion molding, various molding aids are used. For example, JP-A-60-150834 discloses a method of adding graphite as a molding aid,
Japanese Patent Publication No. 2-36296 proposes a method of adding whiskers. It has been reported that a molding catalyst having excellent mechanical strength can be obtained by adding the molding aid to an extrusion molding.

[0005] However, there is no description about moldability in these publications. In addition, JP-B 63-221
No. 87 proposes a method in which a resin having a water absorption capacity of 150 weight times or more and diatomaceous earth are extruded and a catalyst having excellent moldability is obtained to improve the mechanical strength. Is not seen.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a molded catalyst having pores, excellent moldability and high mechanical strength.

[0007]

According to the present invention, a catalyst raw material composition, polyvinyl alcohol, a molding aid comprising a resin having a water absorption capacity of 140 times by weight or less, and water are kneaded.
A method for producing a molded catalyst characterized by extrusion molding.

[0008] The type of the catalyst raw material composition used in the present invention is not particularly limited. For example, a catalyst for producing an unsaturated carboxylic acid by gas phase catalytic oxidation of a known unsaturated aldehyde, for example, used as a catalyst for producing methacrylic acid by oxidizing methacrolein, phosphorus, molybdenum, vanadium And a catalyst containing molybdenum and vanadium used when oxidizing acrolein to produce acrylic acid.

In the present invention, polyvinyl alcohol and a resin having a water absorption capacity of 140 times by weight or less are used as molding aids.
Polyvinyl alcohol is not particularly limited as long as it is water-soluble because it is used in a form dissolved in water.
Product number 283-10,283 manufactured by Nakarai Tesque Co., Ltd.
-11, 160-03055 manufactured by Wako Pure Chemical Industries, Ltd., and the like.

The resin having a water absorbing ability is a resin which does not dissolve in water but absorbs water up to 140 times its own weight in water (deionized water) and swells. There are many types of resins having a water absorbing ability, for example, sodium polyacrylate, saponified vinyl acetate-acrylate copolymer, starch-acrylic acid graft polymer, isobutylene-maleic anhydride copolymer crosslinked product, Starch-acrylonitrile graft copolymer and the like.

Some of these resins have a water-absorbing capacity of 1000 times or more of their own weight, but in the present invention, it is particularly necessary to use a resin having a relatively small water-absorbing capacity of 140 times or less. If the water absorption capacity exceeds 140 times by weight, it is not preferable in terms of the mechanical strength of the molded catalyst. As the lower limit of the water absorption capacity, a substance having a water absorption capacity of about 70 times its own weight can be used.

In the present invention, the amount of the molding aid is not particularly limited and can be arbitrarily selected according to the purpose.
It is preferable to add in the range of parts by weight, particularly in the range of 1 to 5 parts by weight. If the amount is less than 0.5 part by weight, the moldability at the time of extrusion tends to deteriorate, and if it exceeds 10 parts by weight, the mechanical strength of the molded catalyst tends to decrease.

In the present invention, the amount of water added when kneading the catalyst raw material composition and the molding aid is not particularly limited.
An appropriate amount may be added as long as extrusion molding can be performed smoothly.

Next, the kneaded material is extruded into a catalyst having an arbitrary shape such as a ring shape, a column shape, a cylindrical shape, or a star shape using a general granule forming machine such as an extrusion granulator or a vacuum extruder. I do.

The extruded catalyst thus obtained is then heat-treated. In the present invention, the heat treatment conditions are not particularly limited, and known treatment conditions can be applied. Usually, as a heat treatment condition, after drying at a temperature of 60 to 150 ° C., firing is performed at a temperature of 300 to 500 ° C. in a nitrogen or air stream. It is expected that such heat treatment will form pores effective for the reaction.

In the present invention, a conventionally known molding aid may be further added during the mixing. However, the amount of addition should not be so great as to impair the effect of the molding aid specified by the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. “Parts” in the text means parts by weight. The mechanical strength of the molded catalyst was measured by the following method. Crushing strength: A load was applied in the direction of the vertical axis and the vertical direction of the vertical axis of one molded catalyst, and the load when cracks were generated was measured. Falling powdering ratio: Internal diameter 27 standing upright
2,000 g (a) of a molded catalyst was dropped from the upper part of an iron pipe having a length of 5000 mm and received by an 8 mesh sieve, and the weight (b) of the catalyst remaining on the sieve was measured. Was measured.

[0018]

(Equation 1)

The molded catalyst has an outer diameter of 5 mm and an inner diameter of 2 m.
m, and cut to an average length of 5 mm, and used for each measurement.

[0020]

【Example】

[Example 1] 100 parts of ammonium paramolybdate,
3.3 parts of ammonium metavanadate and 9.2 parts of cesium nitrate were dissolved in 100 parts of pure water. A solution prepared by dissolving 8.2 parts of 85% phosphoric acid in 30 parts of pure water was added thereto, and the mixture was evaporated to dryness while heating. The obtained solid was pulverized into a powder, and 100 parts of this powder was mixed with 2 parts of polyvinyl alcohol (283-11 manufactured by Nacalai Tesque) and the water absorption capacity was 70%.
Add 3 parts by weight of sodium polyacrylate and an appropriate amount of water,
After sufficient kneading, the mixture was extruded and cut from an extruder. After drying this molded product at 100 ° C.,
After calcination for a time, a completed catalyst was obtained. The moldability during extrusion of the catalyst raw material composition was extremely good as shown in Table 1, and the mechanical strength of the molded catalyst was also excellent.

Example 2 Extrusion molding was performed in the same manner as in Example 1 except that the amounts of polyvinyl alcohol and sodium polyacrylate having a water absorption capacity of 70 parts by weight were changed to 0.5 parts and 1.5 parts, respectively. Was performed. Table 1 shows the obtained results.

Example 3 Extrusion molding was conducted in the same manner as in Example 1 except that the amounts of polyvinyl alcohol and sodium polyacrylate having a water absorption capacity of 70 times by weight were changed to 5.0 parts and 4.0 parts, respectively. Was performed. Table 1 shows the obtained results.

Example 4 Extrusion molding was carried out in the same manner as in Example 1 except that the amounts of polyvinyl alcohol and sodium polyacrylate having a water absorption capacity of 70 times by weight were changed to 0.2 part and 0.5 part, respectively. Was performed. Table 1 shows the obtained results.

Example 5 Extrusion molding was carried out in the same manner as in Example 1 except that the amounts of polyvinyl alcohol and sodium polyacrylate having a water absorption capacity of 70 times by weight were changed to 5.0 parts and 6.0 parts, respectively. Was performed. Table 1 shows the obtained results.

Example 6 Extrusion molding was performed in the same manner as in Example 1 except that the amounts of polyvinyl alcohol and sodium polyacrylate having a water absorption capacity of 70 times by weight were both changed to 0.2 part. Table 1 shows the obtained results.

Example 7 100 parts of ammonium paramolybdate and 16.6 parts of ammonium metavanadate were dissolved in 1000 parts of pure water. A solution of 21.0 parts of ferric nitrate dissolved in 200 parts of pure water was added thereto, and 1.0 part of germanium oxide was further added. Next, 61.0 parts of 20% silica gel was added, and the mixture was evaporated to dryness while heating and stirring. The obtained solid was pulverized into a powder, and 100 parts of the powder was mixed with 2 parts of polyvinyl alcohol (160-03055 manufactured by Wako Pure Chemical Industries, Ltd.), 3 parts of sodium polyacrylate having a water absorption capacity of 70 times by weight, and an appropriate amount of water. After sufficient kneading, the mixture was extruded and cut by an extruder. After drying this molded product at 130 ° C.,
Calcination at 5 ° C. for 5 hours gave a finished catalyst. This catalyst raw material composition
The moldability during extrusion of the product is extremely good as shown in Table 1.
Also, the mechanical strength of the molded catalyst was excellent. Got
The composition of the elements other than oxygen in the catalyst is Mo ₁₂ V ₃ Fe _1.1
It was a Si _4.3 Ge _0.2. This molded catalyst in the reaction tube
Fill, acrolein 5%, oxygen 10%, steam 30
% And nitrogen 55% (volume%) at a reaction temperature of 270.
C. and a contact time of 3.6 seconds. Collect the product and gas
Chromatographic analysis showed that acrolein anti-
The reaction rate was 99.1% and the selectivity for acrylic acid was 95.5%.
Was.

Example 8 In Example 7, the water absorption capacity was 7
Extrusion molding was carried out in the same manner except that a saponified polyvinyl acetate-acrylate copolymer having a water absorption capacity of 120 weight times was used instead of the 0 weight weight sodium polyacrylate.

[0028]

[Table 1]

[Comparative Example 1] Extrusion molding was performed in the same manner as in Example 1 except that neither polyvinyl alcohol nor sodium polyacrylate having a water absorption capacity of 70 times by weight was used. Table 2 shows the obtained results.

Comparative Example 2 Extrusion molding was performed in the same manner as in Example 1 except that polyvinyl alcohol was not used. Table 2 shows the obtained results.

Comparative Example 3 Extrusion molding and reaction were carried out in the same manner as in Example 1 except that sodium polyacrylate having a water absorption capacity of 70 times by weight was not used. Table 2 shows the obtained results. In addition, metachlore
In reaction rate 80.0%, methacrylic acid selectivity 75.0%
Met.

Comparative Example 4 Extrusion molding was performed in the same manner as in Example 1 except that water-soluble starch was used instead of polyvinyl alcohol. Table 2 shows the obtained results.

Comparative Example 5 Extrusion molding was carried out in the same manner as in Example 1 except that hydroxypropyl cellulose was used instead of polyvinyl alcohol. Table 2 shows the obtained results.

[Comparative Example 6] In Example 1, the water absorption capacity was 7
Water absorption capacity is 3 instead of 0 weight times sodium polyacrylate
Extrusion molding was carried out in the same manner except that sodium polyacrylate was used at a weight ratio of 00. Table 2 shows the obtained results.

[Comparative Example 7] Instead of polyvinyl acetate-acrylate having a water absorption capacity of 120 times by weight in Example 8, the water absorption capacity was 100 weight.
Extrusion molding and reaction were carried out in the same manner except that a saponified polyvinyl acetate-acrylate copolymer of 0 times was used. Table 2 shows the obtained results. Also, acrolein
The conversion was 99.0% and the selectivity for acrylic acid was 95.3%.
Was. The reaction rate and selectivity in Examples and Comparative Examples are
The following definitions were followed.

[0036]

[Table 2]

The guideline for ranking the moldability in Tables 1 and 2 is as follows. ○ Smooth extrusion and good yield. Δ The extrusion was not smooth, the yield was slightly poor, and separation of the kneaded material and water was observed. × Cannot be extruded.

Claims (1)

(57) [Claims] 1. A method for producing a molded catalyst, comprising kneading a catalyst raw material composition, a polyvinyl alcohol, a molding aid composed of a resin having a water absorption capacity of 140 times by weight or less, and water, followed by extrusion molding.