JPH0516308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preparing a catalyst for use in the production of unsaturated carboxylic acids by gas phase catalytic oxidation of unsaturated aldehydes.

When producing unsaturated carboxylic acids by vapor phase catalytic oxidation of unsaturated aldehydes, the lifetime of the catalyst,
From the viewpoint of suppressing side reactions and equipment costs, it is advantageous to maintain a high yield at a low reaction temperature, but using a catalyst prepared by a conventional method does not necessarily give satisfactory results. In order to improve this conventional catalyst preparation method, the present inventors conducted intensive research focusing on the structure of the catalyst, and found that it is effective at lower reaction temperatures than when using catalysts prepared by conventional methods. We have discovered a new method for preparing a catalyst that allows unsaturated carboxylic acids to be obtained in high yield.

The present invention is a method for preparing a multicomponent catalyst for producing an unsaturated carboxylic acid containing phosphorus and molybdenum, which is characterized by adding hydrogen peroxide to catalyst raw materials and causing the reaction.

The catalyst obtained by the method of the present invention has the general formula Mo _a P _b X _c Y _d O _e (where X is an alkali metal and/or thallium, Y
represents vanadium, silver, magnesium, zinc, selenium, tellurium, arsenic, copper, germanium, nickel, silicon, rhodium, tungsten, boron, bismuth, tantalum, chromium, barium, antimony and/or tin, a, b, c , d, e represent the atomic ratio of each element, a=12, b=0.01~3, c
=0 to 5, d=0 to 10, and e is a value determined by the oxidation state of the catalyst).

Using the catalyst obtained by the process of the invention, acrylic acid or methacrylic acid can be obtained economically and advantageously from unsaturated aldehydes to unsaturated carboxylic acids, in particular from acrolein or methacrolein.

Examples of the alkali metal X in the catalyst composition include potassium, rubidium, and cesium.

Catalyst raw materials are used as nitrates, ammonium salts, halides, oxides, etc. of each element.

When carrying out the present invention, the catalyst raw material is first dissolved in water. At this time, each catalyst raw material may be dissolved simultaneously or sequentially, or the catalyst raw materials may be dissolved separately and then their aqueous solutions may be mixed. In the present invention, hydrogen peroxide is added to this solution,
It is preferable to react. Hydrogen peroxide may be added to the residue obtained by removing water from the aqueous solution of the catalyst raw material to cause a reaction, followed by heat treatment. As the hydrogen peroxide, for example, commercially available 30% hydrogen peroxide solution is used. Hydrogen peroxide may be added to an aqueous solution in which only molybdenum is dissolved, or may be added to an aqueous solution in which molybdenum and other catalyst raw materials are dissolved. The amount of hydrogen peroxide used is 5 to 30% by weight of the total weight of the catalyst raw materials, expressed as a 30% hydrogen peroxide solution. If the amount of hydrogen peroxide used is less than 5% by weight, no sufficient effect will be obtained, and if it is more than 30% by weight, no enhancement of the effect will be observed, which is economically disadvantageous. The heating temperature is preferably 30 to 70°C, and the reaction is completed in 1 to 10 minutes.

For example, in order to produce a catalyst consisting of phosphorus, molybdenum, and vanadium, water is usually added to ammonium paramolybdate and ammonium metavanadate, heated and dissolved, and then an aqueous solution of phosphoric acid is added with stirring to prepare an aqueous solution of the catalyst raw materials. do.
In this case, hydrogen peroxide may be added after dissolving ammonium paramolybdate, either before or after adding the phosphoric acid aqueous solution.

When using ammonium paramolybdate as a catalyst raw material, the amount of hydrogen peroxide used is 0.1 part by weight of this compound as a 30% hydrogen peroxide solution.
The amount is at least 0.2 parts by weight, preferably at least 0.2 parts by weight.

Next, the aqueous solution of the catalyst raw material is heated under normal pressure or reduced pressure to remove water, and the resulting catalyst component is dried at about 130°C and then pulverized. This powder is compression-molded by a conventional method and then heat-treated under air circulation to obtain the desired catalyst.

The catalyst obtained by the method of the present invention can be supported on an inert carrier such as silica, alumina, silica/alumina, or silicon carbide, or can be used after being diluted with these.

The catalyst obtained by the method of the present invention is generally used in a fixed bed, but it can also be used in a fluidized bed. When performing gas phase catalytic oxidation of unsaturated aldehydes using this catalyst, the concentration of unsaturated aldehydes in the raw material gas can be varied within a wide range, but 1 to 20% by volume is appropriate, particularly 3 to 10% by volume. Volume % is preferred.

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 raw material gas is defined by the molar ratio to unsaturated aldehyde, and this value is
0.3-4, particularly 0.4-2.5 is preferred. The raw material gas may be diluted by adding an inert gas such as nitrogen, water vapor, or carbon dioxide gas. The reaction pressure is preferably from normal pressure to several atmospheres. Although the reaction temperature can be selected within the range of 240 to 450°C, 260 to 400°C is particularly preferred.

The conversion rate of the unsaturated aldehyde, the selectivity and single flow yield of the unsaturated carboxylic acid produced are defined as follows.

Conversion rate of unsaturated aldehyde (%) = Number of moles of unsaturated aldehyde reacted / Number of moles of unsaturated aldehyde supplied ×
100 Selectivity of unsaturated carboxylic acid (%) = Number of moles of unsaturated carboxylic acid produced/Number of moles of reacted unsaturated aldehyde ×
100 Single flow yield (%) of unsaturated carboxylic acid = Number of moles of unsaturated carboxylic acid produced/Number of moles of unsaturated aldehyde supplied x 100 Also, in the examples below, parts mean parts by weight, and analysis was performed using gas chromatography. I went to Tographi.

Example 1 100 parts of ammonium paramolybdate, 2.8 parts of ammonium metavanadate and 4.8 parts of potassium nitrate
1 part was dissolved in 400 parts of pure water. This includes 85% phosphoric acid 6.0
Add a solution of 1 part dissolved in 50 parts of pure water, and then add 30%
Dilute 20 parts of hydrogen peroxide with 50 parts of pure water and add 60 parts of hydrogen peroxide.
The mixture was heated and stirred at ℃ for 1 minute. Next, a solution of 4.6 parts of copper nitrate dissolved in 50 parts of water was added, and the mixture was evaporated to dryness while heating. After drying the residue at 130℃, it is pulverized and compression molded under air circulation.
Heat treatment was performed at 380°C for 5 hours. The composition of elements other than oxygen (the same applies hereinafter) of the obtained catalyst is P _1.1 Mo ₁₂ V _0.5
It was Cu _0.4 K ₁ .

This catalyst was packed into a reactor and methacrolein 5
%, oxygen 10%, water vapor 30%, nitrogen 55% (volume %)
A mixed gas was passed through the reactor at a reaction temperature of 290°C and a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography, and the conversion rate of methacrolein was 83.4.
%, methacrylic acid selectivity was 85.0%, and single flow yield of methacrylic acid was 70.9%.

Comparative Example 1 A catalyst having the composition of Example 1 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 1. As a result, the conversion of methacrolein was 81.3%, and the conversion of methacrylic acid was 81.3%. The selectivity was 82.0% and the single flow yield of methacrylic acid was 66.7%.

Example 2 100 parts of ammonium paramolybdate and 400 parts of pure water
It was dissolved in parts. Add 6.0 parts of 85% phosphoric acid to this and 50 parts of pure water.
20 parts of 30% hydrogen peroxide solution diluted with 50 parts of pure water was added, and the mixture was evaporated to dryness while heating at 60° C. for 1 minute. The residue was dried at 130°C, pulverized, compression molded, and heat treated at 380°C for 5 hours under air circulation. The composition of the obtained catalyst was P _1.1 Mo ₁₂ .

This catalyst was packed into a reactor and methacrolein 5
%, oxygen 10%, water vapor 30%, nitrogen 55% (volume %)
A mixed gas of 300° C. was introduced at a reaction temperature of 330° C. and a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography, and the conversion rate of methacrolein was 57.9.
%, methacrylic acid selectivity was 73.0%, and methacrylic acid single flow yield was 42.3%.

Comparative Example 2 A catalyst having the composition of Example 2 was prepared without adding aqueous hydrogen peroxide, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 2. As a result, the conversion of methacrolein was 48.7%, and the conversion of methacrylic acid was 48.7%. The selectivity was 71.3% and the single flow yield of methacrylic acid was 34.7%.

Example 3 100 parts of ammonium paramolybdate and 7.0 parts of rubidium nitrate were dissolved in 400 parts of pure water. to this
A solution of 5.4 parts of 85% phosphoric acid dissolved in 50 parts of pure water and 1.5 parts of boric acid were added, and 80 parts of 30% hydrogen peroxide solution diluted with 50 parts of pure water were added, followed by heating and stirring at 60°C for 1 minute. . Next, add 12.1 parts of magnesium nitrate to 100 parts of water.
The solution dissolved in one portion was added, and the mixture was evaporated to dryness while heating. This material was dried at 130℃, pulverized, compression molded, and heated to 380℃ under air circulation.
Heat treatment was performed at ℃ for 5 hours. The composition of the obtained catalyst is
P ₁ MO ₁₂ Mg ₁ B _0.5 Rb ₁ .

This catalyst was packed into a reactor and methacrolein 5
%, oxygen 10%, water vapor 30%, nitrogen 55% (volume %)
A mixed gas of 300° C. was passed through the reactor at a reaction temperature of 300° C. and a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography, and the conversion rate of methacrolein was 82.5.
%, methacrylic acid selectivity was 81.2%, and single flow yield of methacrylic acid was 67.0%.

Comparative Example 3 A catalyst having the composition of Example 3 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 3. As a result, the conversion rate of methacrolein was 75.8%, and the conversion rate of methacrylic acid was 75.8%. The selectivity was 79.2% and the single flow yield of methacrylic acid was 60.0%.

Example 4 Same as Example 1, the composition was P _1.3 Mo ₁₂ Rh _0.01
A catalyst was prepared that was Cs ₁ V _0.4 W _0.3 Se _0.2 . Using this catalyst, the reaction was carried out at a reaction temperature of 275°C and other conditions were the same as in Example 1. The methacrolein conversion rate was 83.5% and the methacrylic acid selectivity was 86.3.
%, and the single flow yield of methacrylic acid was 72.1%.

Comparative Example 4 A catalyst having the composition of Example 4 was prepared without adding aqueous hydrogen peroxide, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 4. As a result, the conversion of methacrolein was 81.0%, and methacrylic acid was The selectivity was 84.8%, and the single flow yield of methafrylic acid was 68.7%.

Example 5 Same as Example 1, composition is P _1.2 Mo ₁₂ V _0.6
A catalyst was prepared that was Cu _0.5 Zn _0.1 Tl _0.8 . Using this catalyst, the reaction was carried out at a reaction temperature of 270°C under the same conditions as in Example 1, and the results showed that the methacrolein conversion rate was 80.3%, the methacrylic acid selectivity was 81.5%, and the reaction temperature was 270°C.
The single flow yield of methacrylic acid was 65.4%.

Comparative Example 5 A catalyst having the composition of Example 5 was prepared without adding aqueous hydrogen peroxide, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 5. As a result, the conversion of methacrolein was 74.6%, and the conversion of methacrylic acid was 74.6%. The selectivity was 78.8% and the single flow yield of methacrylic acid was 58.8%.

Example 6 Similar to Example 1, the composition was P _1.2 Mo ₁₂ V _0.6
A catalyst was prepared that was Mg _0.5 Ag _0.1 Te _0.3 Bi _0.3 . Using this catalyst, the reaction was carried out at a reaction temperature of 300°C and under the same conditions as in Example 1. The conversion rate of methacrolein was 85.2%, and the selectivity of methacrylic acid was 85.2%.
The single flow yield of methacrylic acid was 65.1%.

Comparative Example 6 A catalyst having the composition of Example 6 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 6. As a result, the conversion of methacrolein was 78.3%, and methacrylic acid was The selectivity was 73.5% and the single flow yield of methacrylic acid was 57.6%.

Example 7 Same as Example 1, the composition is P _1.3 Mo ₁₂ V _0.6
A catalyst was prepared that was Cu _0.5 Ni _0.3 Si _0.5 As _0.5 K ₁ . Using this catalyst, the reaction was carried out at a reaction temperature of 280°C and under the same conditions as in Example 1. The conversion rate of methacrolein was 84.6%, and the selectivity of methacrylic acid was 84.6%.
The single flow yield of methacrylic acid was 72.3%.

Comparative Example 7 A catalyst having the composition of Example 7 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 7. As a result, the conversion rate of methacrolein was 80.6%, and the conversion of methacrylic acid was 80.6%. The selectivity was 84.8% and the single flow yield of methacrylic acid was 68.3%.

Example 8 Same as Example 1, the composition is P _1.3 MO ₁₂ V _0.4
A catalyst was prepared that was Cu _0.4 Ta _0.3 Ba _0.2 Sn _0.2 K ₁ .
Using this catalyst, a reaction was carried out at a reaction temperature of 300°C and under the same conditions as in Example 1. As a result, the methacrolein conversion rate was 82.5%, and the methacrylic acid selectivity was 82.5%.
The single-stream yield of methacrylic acid was 63.9%.

Comparative Example 8 A catalyst having the composition of Example 8 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 8. As a result, the conversion of methacrolein was 78.4%, and methacrylic acid was The selectivity was 75.8% and the single flow yield of methacrylic acid was 59.4%.

Example 9 100 parts of ammonium paramolybdate, 1.7 parts of ammonium metavanadate, 4.8 parts of potassium nitrate and 4.6 parts of cesium nitrate were dissolved in 400 parts of pure water.
To this was added 7.1 parts of 85% phosphoric acid diluted with 50 parts of pure water, and further added 3.4 parts of antimony trioxide, followed by heating and stirring. Next, a solution of 3.4 parts of copper nitrate dissolved in 50 parts of water was added, and finally 20 parts of 30% hydrogen peroxide solution diluted with 50 parts of pure water was added, and the mixture was evaporated to dryness while heating. After drying the residue at 130℃, finely pulverize it,
The compression molded product was heat treated at 380°C for 5 hours under air circulation. The composition of the obtained catalyst is P _1.3 Mo ₁₂ V _0.3
Cu _0.3 Sb _0.5 K ₁ Cs _0.5 .

This catalyst was packed into a reactor, and methacrolein 5
%, oxygen 10%, water vapor 30%, nitrogen 55% (volume %)
A mixed gas of 270° C. was passed through the reactor at a reaction temperature of 270° C. and a contact time of 3.6 seconds. The product was collected and analyzed by gas chromatography, and the conversion rate of methacrolein was 84.3.
%, methacrylic acid selectivity was 84.5%, and single flow yield of methacrylic acid was 71.2%.

Comparative Example 9 A catalyst having the composition of Example 9 was prepared without adding hydrogen peroxide solution, and a reaction was carried out using this catalyst under the same reaction conditions as in Example 9. As a result, the conversion of methacrolein was 82.0%, and methacrylic acid was The selectivity was 81.9% and the single flow yield of methacrylic acid was 67.2%.

Example 10 100 parts of ammonium paramolybdate, 2.8 parts of ammonium metavanadate and 9.2 parts of cesium nitrate
1 part was dissolved in 400 parts of pure water. This includes 85% phosphoric acid 6.5
A solution of 50 parts of pure water and 2.5 parts of germanium dioxide dissolved in 50 parts of pure water were added, and then 30 parts of 30% hydrogen peroxide was diluted with 50 parts of pure water, and the mixture was heated at 60°C. The mixture was heated and stirred for 1 minute. A solution of 3.8 parts of chromium nitrate dissolved in 50 parts of water was then added, and the mixture was evaporated to dryness while heating. Residue at 130℃
After drying, the product was pulverized, compression molded, and heat treated at 380° C. for 5 hours under air circulation. The composition of the obtained catalyst was P _1.2 Mo ₁₂ Ge _0.5 Cs ₁ V _0.5 Cr _0.2 .

This catalyst was packed into a reactor, and methacrolein 5
%, oxygen 10%, water vapor 30%, nitrogen 55% (volume %)
A mixed gas of 280° C. was passed through the reactor at a reaction temperature of 280° C. and a contact time of 3.6 seconds. When the product was collected and analyzed by gas chromatography, the methacrolein conversion rate was 85.3.
%, methacrylic acid selectivity was 83.0%, and single flow yield of methacrylic acid was 70.8%.

Comparative Example 10 A catalyst having the composition of Example 10 was prepared without adding aqueous hydrogen peroxide, and a reaction was conducted using this catalyst under the same reaction conditions as in Example 10. As a result, the conversion of methacrolein was 78.8%, and the conversion of methacrylic acid was 78.8%. The selectivity was 81.0% and the single flow yield of methacrylic acid was 63.8%.

Comparative Example 11 Dilute 30 parts of 30% hydrogen peroxide solution with 400 parts of pure water,
Ammonium paramolybdate, ammonium metavanadate, and cesium nitrate were added to this solution in the same manner as in Example 10, and dissolved by heating. Next, phosphoric acid and germanium dioxide were added, heated and stirred, and further chromium nitrate was added and evaporated to dryness. In this way, a catalyst having the same composition as in Example 10 was prepared, and
When the reaction was carried out under the same reaction conditions as in 10, the methacrolein conversion rate was 79.3% and the methacrylic acid selectivity was 81.3.
%, and the single flow yield of methacrylic acid was 64.5%. This indicates that if hydrogen peroxide solution is added before ammonium paramolybdate is dissolved, there is almost no effect.

Example 11 A catalyst having the composition of Example 10 was added to 30% hydrogen peroxide solution.
It was prepared in the same manner as in Example 10 except that the amount was changed to 100 parts.
When a reaction was carried out using this catalyst under the same reaction conditions as in Example 10, the methacrolein conversion rate was 85.2%,
The methacrylic acid selectivity was 82.9%, and the single flow yield of methacrylic acid was 70.6%. Increasing the amount of hydrogen peroxide in this way is also effective.

Example 12 A catalyst having the composition of Example 10 was mixed with 30% hydrogen peroxide solution 10
It was prepared in the same manner as in Example 10 except that 1 part was changed. When a reaction was carried out using this catalyst under the same reaction conditions as in Example 10, the methacrolein conversion rate was 83.9%.
The methacrylic acid selectivity was 82.5%, and the single flow yield of methacrylic acid was 69.2%. It is known that even if the amount of hydrogen peroxide solution is smaller than this, it is still effective, but the ratio of the effect is reduced.

Example 13 Using the catalyst prepared in Example 1, a mixed gas of 5% acrolein, 10% oxygen, 30% water vapor, and 55% nitrogen (by volume) was introduced into the catalyst layer at a reaction temperature of 300°C and a contact time of 3.6 seconds. As a result, the acrolein conversion rate
The acrylic acid selectivity was 89.5%, and the single flow yield of acrylic acid was 81.9%.

Comparative Example 12 A catalyst having the composition of Example 1 was prepared without adding hydrogen peroxide solution, and a reaction was carried out under the same reaction conditions as in Example 13. As a result, acrolein conversion rate was 90.1%, acrylic acid selectivity was 89.0%, and acrylic acid Single stream yield of acid 80.2%
It was hot.

Claims (1)

[Scope of Claims] 1. A method for preparing a multi-component catalyst for producing an unsaturated carboxylic acid containing phosphorus and molybdenum, which comprises adding hydrogen peroxide to a catalyst raw material and causing the reaction. 2. The method according to claim 1, characterized in that hydrogen peroxide is added to an aqueous solution of catalyst raw materials to cause a reaction, water is removed, and the residue is heat-treated. 3. The method according to claim 1, characterized in that hydrogen peroxide is added to the residue obtained by removing water from the aqueous solution of the catalyst raw material, and the mixture is reacted, followed by heat treatment. 4 General formula Mo _a P _b X _c Y _d O _e (wherein X is an alkali metal and/or thallium, Y
represents vanadium, silver, magnesium, zinc, selenium, tellurium, arsenic, copper, germanium, nickel, silicon, rhodium, tungsten, boron, bismuth, tantalum, chromium, barium, antimony and/or tin, a, b, c , d, e represent the atomic ratio of each element, a=12, b=0.01~3, c
= 0 to 5, d = 0 to 10, and e is a value determined by the oxidation state of the catalyst. The method described in.