JPS5861833A - Calcining method of phosphorus and molybdenum type catalyst - Google Patents

Abstract

PURPOSE:To obtain a catalyst having high performance and uniform activity in an industrial scale, by treating a catalytic composn. under heating in a flow of a gas contg. a specified range of ammonia and water vapor. CONSTITUTION:A catalytic composn. is prepared by adding ammonia or an ammonium compd. to a starting material of catalyst contg. molybdenum and oxygen in manufacturing the catalyst by an oxide mixing process or the like, and drying the obtained slurry. This catalytic composn. can be converted into a catalyst having high performance and uniform activity by calcining this composition in a flow of gas contg. 0.05-3% ammonia and/or water vapor at 300-500 deg.C for 1-several ten hr, when needed, with the gaseous flow direction reversed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for calcination of a catalyst containing phosphorus, molybdenum and oxygen used in the gas phase catalytic oxidation of unsaturated aldehydes to produce the corresponding unsaturated acids. More specifically, the present invention relates to a method for firing a catalyst containing phosphorus, molybdenum, and oxygen used when producing acrylic acid or methacrylic acid by vapor phase catalytic oxidation of acrolene or methachlorolene.

Conventionally, various catalysts have been proposed for gas phase catalytic oxidation of acrolene or methachlorolene, but catalysts containing phosphorus, molybdenum, and oxygen have shown relatively excellent performance. Some of the present inventors also
No. 50-25014, etc., proposed a catalyst containing phosphorus, molybdenum, and oxygen. The above catalyst under certain conditions I
When prepared with iI, the activity and selectivity of target production are significantly improved. However, the reproducibility of performance is insufficient, and the variation in performance increases as the scale of production increases, so it is not necessarily sufficient from the viewpoint of industrial implementation.

The inventors of the present invention have conducted extensive research into methods for manufacturing the above-mentioned catalysts, which have high performance and high homogeneity, and which are advantageous especially when manufactured on an industrial scale. Under gas flow containing strictly controlled concentrations of ammonia and/or water vapor during feeding 3
A high-performance and highly homogeneous catalyst can be obtained by calcining at a temperature of 00 to 500°C for 1 to several tens of hours, reversing the flow direction of the ammonia or water-containing gas if necessary. The present invention has been completed based on this discovery.

Accordingly, the present invention provides a method for calcination of a catalyst containing phosphorus, molypide/and oxygen, which is used in the gas phase catalytic oxidation of acrolene or methachlorolene to produce acrylic acid or methacrylic acid. The present invention will be explained in detail below.

Catalysts containing molybdenum and molybdenum are shown in the above cited references.
Catalysts calcined under air flow often exhibit significantly higher activity than catalysts calcined without air flow, which exhibit activity in various preparation methods as described above. while)
In this calcination, the larger the amount of catalyst, the more the difference in activity between the catalysts, resulting in a catalyst with non-uniform performance, poor reproducibility, and difficulty in calcination on an industrial scale. Improvements were awaited.

Therefore, the present inventors conducted various studies in order to elucidate the mechanism of activity expression and the cause of the non-uniformity of activity in the calcination of a catalyst containing phosphorus, molybdenum and oxygen. As a result, non-uniformity in catalytic activity is caused by the generation of water vapor, ammonia, nitrogen oxides, and other gases or gaseous substances from the catalyst due to decomposition of raw material salts when the catalyst is fired through gas such as air. It was found that this was because the catalyst composition inside was exposed to a non-uniform atmosphere from the inlet to the outlet sK of the gas flow.

Based on these facts, the present inventors studied methods for uniformly firing catalysts on an industrial scale from various angles. They have discovered that by treating the catalyst under gas flow that is regulated to contain a total amount of 0.05 to 3.0%, a catalyst with high performance and highly uniform performance can be obtained.

Catalyst systems that can be subjected to calcination in the present invention are compositions containing phosphorus and molybdenum, and systems in which ammonia or ammonium groups are involved in the preparation process. For example, when preparing a catalyst from a raw material compound of a catalyst by evaporation to dryness method, coprecipitation method, or oxide mixing method, if ammonia or ammonium group does not exist in the raw material, the ammonia or ammonium group may be added. ms in the presence of
This is a composition obtained by drying the resulting slurry. The catalyst calcination method of the present invention can be applied to catalysts containing various elements in addition to phosphorus, molybdenum, and oxygen.

Examples of elements that can be contained include alkaline earth metals, arsenic, antimony, bismuth, copper, vanadium, tungsten, iron, manganese, tin, zirconium, cobalt, nickel, zinc, selenium, cadmium, niobium, tantalum, and silicon. , aluminum, titanium, rhodium,
Examples include cerium, germanium, lead, chromium, thallium, indium, palladium, silver, and tellurium. The raw materials used for preparing the catalyst may be hydroxides, oxides, salts, chlorides, or free acids. Examples of these are phosphoric acid, molybdic acid, phosphomolybdic acid,
Examples include ammonium molybdate, ammonium phosphomolybdate, molybdenum trioxide, and the like. An example of the preparation method is as follows.

Add a phosphoric acid aqueous solution to an ammonium molybdate aqueous solution, and if necessary, add other elemental compounds such as arsenic acid, steel nitrate, ammonium metabazate, etc., and then evaporate to dryness while stirring. . The cake may be crushed and then molded into tablets, or it may be diluted with a diluent and molded. Alternatively, it may be supported on a suitable carrier. The obtained catalyst was
C(.

It may be fired while still in use, or it may be fired after being heat-treated at a temperature of 1°C or less.

In the method of the present invention, in the case of an ammonia-containing gas, the ammonia concentration is preferably (105 to 3 mo, particularly (LD5 to t5-). In the case of a water vapor-containing gas or ammonia and water vapor-containing gas, the ammonia concentration is preferably in the range of α05 to 3 mo.

In any case, if it is smaller than the above lower limit, the effect will be small and the catalyst will have non-uniform activity. In addition, even if the temperature exceeds the above upper limit, the activity of the catalyst obtained after heat treatment will be non-uniform.
In addition, the expression of activity becomes insufficient as a whole. The firing temperature is 30
0 to 500°C, particularly 300 to 420°C is preferred. The time required for firing varies depending on the firing temperature, atmosphere, or concentration thereof, but is preferably 1 to several tens of hours, particularly 1 to 30 hours.

For firing according to the present invention, commonly used equipment and furnaces are sufficient. Furthermore, according to the method of the present invention, a highly homogeneous catalyst can be obtained, so that the size of the catalyst layer during firing can be increased. For example, it can be carried out by filling a reactor with a total length of 5 to 6 m. In this case, the direction of the gas may be reversed if necessary to improve uniformity.

In producing acrylic acid or methacrylic acid by oxidizing acrolene/or methacrolene using the highly activated catalyst according to the present invention, a mixed gas of acrolene or methacrolene and a molecular acid, such as an element such as air, is used as a raw material gas. is used. Steam, nitrogen, carbon dioxide gas, etc. may be introduced as a diluent. In particular, the presence of water vapor has a favorable effect on improving the acrolene or methacrolene conversion rate and the selectivity of acrylic acid or methacrylic acid. The concentration of acrolene or methachlorolene in the raw material gas can be varied within a wide range, but is suitably 1 to 20 vol-, particularly preferably 3 to 15 vol'4. The oxygen concentration is preferably 0.5 to 4, particularly 3.2.degree. 14 to acrolene in molar ratio. The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature is 240-590℃, especially 270-54℃
0°C is suitable. The gas hourly space velocity varies depending on the reaction pressure and reaction temperature, but is suitably 5oO to IQ, DO (If//H).

The method of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. In the following, parts represent parts by weight,
The conversion rate and selectivity are as follows.

×100 × 100 Example 1 3,000 parts of ammonium paramolybdate was dissolved in 1,000 parts of pure water at 70°C, and 163 parts of 85% phosphoric acid was added to this.
60 parts and 147 parts of arsenic acid aqueous solution were added.

The mixture was heated with stirring to evaporate to dryness, and was further dried at 1500°C for about 16 hours. The resulting cake was crushed and molded.

After filling 660 parts of the obtained molded product into a stainless steel pipe with an inner diameter of 27.5 s/1 m and a length of 1 m,
The temperature was raised to 380°C at a rate of 80°C/hour while passing 1000 L/H of air containing 1-1 of ammonia.

After holding for 2 hours, the flow direction was reversed and the heat treatment was further carried out for 4 hours. After cooling, it was divided into 5 equal parts and taken out, and was separated from the inlet side of the first gas flow. These■■■■
Fill the reaction tubes with an inner diameter of 16~- with the catalysts (1) and keep the furnace temperature at 280°C.
．． A raw material gas having a composition of 20 -1 water vapor and 27.2 - nitrogen was introduced at a space velocity of 10,001/i (10,001/i) and reacted with each other.

The results are shown below.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the gas used for heat treatment in Example 1 was changed to air containing 101% ammonia.

As a result, it can be seen that large variations in activity and selectivity occur during calcination of a large amount of catalyst.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the gas used in the heat treatment in Example 1 was changed to air containing 5-ammonia.

Example 2 73,000 parts of ammonium paramolybdate was dissolved in 14,000 parts of pure water at about 60°C. After adding 4tS parts of ammonium metavanadate to this and dissolving it, 8.5% 1
Add 165 parts of triphosphoric acid and then 6 parts of germanium dioxide. Furthermore, 145 parts of potassium nitrate was dissolved in 1700 parts of pure water, and 57.2 parts of ferric nitrate was dissolved in 600 parts of pure water, and then added thereto, and the mixtures were evaporated to dryness while heating and stirring.

After drying at 130°C for 16 hours, it was crushed, mixed with a lubricant, and molded.

Is this 27.5% of the inner diameter? After filling a reaction tube with a length of 5 ns, air containing water vapor O, S-10001711
from 100℃ to 385℃ at a heating rate of 25℃/H.
The temperature was raised to .degree. C., held for 4 hours, and then the direction of the gas was reversed and the treatment was continued for an additional 4 hours. After cooling, divide the catalyst into 5 equal parts and take it out from the inlet side of the first gas flow.
■■■ These catalysts were filled into reaction tubes having an inner diameter of 22 to 4, respectively. Thereafter, the reaction was carried out under the same reaction conditions as in Example 1. However, the reaction temperature was 300[deg.] C., 4 g of methacrosin, 60 g of air, and 36 g of water vapor.

Comparative Example 3 The same procedure as in Example 2 was carried out except that the gas used for the heat treatment in Example 2 was changed to air containing 101- water vapor.

Comparative Example 4 The same procedure as in Example 2 was carried out except that the gas used for the heat treatment in Example 2 was changed to air containing s and ol water vapor.

Example 3 500 parts of molybdenum trioxide, 643 parts of antimony trioxide, and 17.4 parts of chromium trioxide were added to 200 parts of pure water, and then a mixed aqueous solution of 125 parts of steel nitrate and 29.3 parts of potassium nitrate was added, followed by stirring. From this, 667 parts of 85-phosphoric acid are mixed. After holding in SaC for 3 hours with sufficient stirring,
28 - Gradually add 80 parts of aqueous ammonia. After keeping for another 2 hours, it was evaporated to dryness. The resulting cake was dried at 150° C. for 16 hours, then ground and molded.

This was packed into a reaction tube with an inner diameter of 27.5 tplm and a length of 3 liters, and was heated at 65 U/H while passing air containing ammonia (LO51G and water vapor α85-) at 1500 t/'El.
The temperature was raised to 590° C. at a heating rate of 1 hour. After holding for 1 hour, the direction of the gas was reversed and heat treatment was performed for S hours. Thereafter, the same procedure as in Example 2 was taken out and a reaction was carried out. However, the reaction temperature is 510°C, and the space velocity is 6 @ 7 o o l/
b.

Example 4 75,000 parts of ammonium baramolybdate was dissolved in 14,000 parts of pure water at about 70°C. To this, 851 Qnic acid 163
part was added and stirred. Furthermore, 147 parts of a 60% arsenic acid aqueous solution was added with stirring. An aqueous solution of 34.1 parts of steel nitrate and a mixed aqueous solution of 410 parts of potassium nitrate and cesium nitrate 193i1S were added. While stirring the above liquid, 49.6 parts of ammonium metavanadate was added, and finally 415 parts of antimony trioxide was added. It was evaporated to dryness while stirring. The resulting cake was dried at 130° C. for 16 hours and then ground. This powdered silica-alumina spherical carrier contains approximately 50-
carried it.

The obtained catalyst was packed into a reaction tube with an inner diameter of 2 z5 w-1 and a length of 3 tubes. While supplying 1000 tAl of air containing water vapor αB-, the temperature was raised at a temperature increase rate of 25°C/H, and at 380°C
Baked for an hour. After the temperature had cooled, it was divided into five parts and taken out.

After filling each reaction tube with the obtained catalyst at a concentration of 116%/lI, 40% of methachlorolene was added while keeping the bath temperature at 295°C.
%, air 47.8%, water vapor 15-1 nitrogen 3\2-(
The raw material gas has a composition of (volume percent) at a space velocity of 6001
When A was supplied, the following results were obtained.

Comparative Example 5 The same procedure as in Example 4 was carried out except that the gas supplied during firing was changed to air containing 1% ammonia and 4% water vapor. As a result, the following values were obtained.

Example 5 After dissolving 7500 parts of ammonium paramolybdate in 1000 parts of pure water, 82.8 parts of ammonium metavanadate was added.
dissolve. Furthermore, add an aqueous solution of 47.7 parts of ferric nitrate,
Next, an aqueous solution of 210 parts of water glass was added and quickly evaporated to dryness.

The resulting cake was dried at 540° C. for 2 hours and then ground. Then, it was supported on a silica-alumina carrier for about 30 minutes.

After filling the reaction tube, the temperature was raised to 570° C. at a rate of 70° C./hour while passing air containing 5% water vapor α at a space velocity of 5001 A, and the mixture was held for 2 hours to undergo a carbon treatment.

Thereafter, the samples were taken out and reacted in the same manner as in Example 1. However, acrolene was used instead of methachlorolene, and the reaction temperature was 270°C.

Claims (7)

[Claims] (1) A catalyst containing phosphorus, molybdenum, and oxygen used to produce an unsaturated acid by catalytic oxidation of an unsaturated aldehyde in the gas phase is oxidized with ammonia and/or water vapor at a temperature of 300 to 500 °C to 5 to 5% CLO. A catalyst firing method that involves treating the four molds while flowing a gas containing them. (2) The catalyst firing method according to claim 1, wherein the gas is air. (3) The catalyst calcination method according to claim 1 or 2, characterized in that the calcination is carried out in a reaction tube for gas phase catalytic oxidation of unsaturated aldehydes. (4) The catalyst firing method according to claim 1, 2, or 3, characterized in that the direction of gas flow is reversed during firing. (5) When calcining the catalyst at a temperature of 300 to 500°C, the temperature increase rate to the calcining temperature should be set to 10 to b.
A method for firing the catalyst according to item 3 or 4. (6) Catalysts include phosphorus, molybdenum, alkali metals, oxygen and arsenic, antimony, bismuth, copper, vanadium, tungsten, iron, manganese, tin, zirconium, cobalt, nickel, zinc, selenium cadmium, niobium, tantalum,! Claim 1: A catalyst comprising at least one member selected from magnesium, silicon, aluminum, titanium, rhodium, cerium, calcium, strontium, germanium lead, chromium, thallium, indium, badge cum, silver, and tellurium. , 2nd term, 3rd term, 4th term
A method for calcination of the catalyst according to item 1 or item 5. (7) Catalysts include phosphorus, molybdenum, thallium, oxygen and arsenic, antimony, bismuth, steel, sodium,
Tungsten, iron, manganese, tin, zirconium, cobalt, nickel, zinc, selenium cadmium 1, niobium, tantalum, magnesium, silicon, aluminum, titanium, rhodium, cerium, calcium, strontium, kermanium, lead, chromium, indium, palladium Claims 1, 2, 3, and 4 are catalysts consisting of at least one member selected from , chains, and tellurium.
A method for calcination of the catalyst described in Section 5.