JPS581094B2 - Fuhouwa Carbon Sanno Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the vapor phase catalytic oxidation of unsaturated aldehydes using novel catalysts to produce the corresponding unsaturated carboxylic acids.

Various catalysts have been proposed in the past for methods of producing acrylic acid or methacrylic acid by vapor phase catalytic oxidation of acrolein or methacrolein, but these catalysts have advantages and disadvantages.

In other words, conventional catalysts have low activity, or even if they give high yields, they only do so in the initial stages and have short lifetimes.They also have low selectivity, which is an important factor in industry, and poor reproducibility. It has drawbacks and is not necessarily industrially satisfactory.

In particular, the above drawbacks are significant in the oxidation reaction of methacrolein to methacrylic acid.

The present inventors have conducted extensive research on catalysts used in the above reaction, and have found that the corresponding unsaturated carboxylic acid can be obtained from an unsaturated aldehyde in extremely high yield and with good reproducibility using a specific new catalyst. They discovered this and arrived at the present invention.

That is, the present invention provides a method for producing an unsaturated carboxylic acid by catalytically oxidizing an unsaturated aldehyde with a gas containing molecular oxygen, using (1) a catalyst containing Moa, Pb, Tac, Yd, and Of; or (2) Moa, Pb, Tac, Yd, Xe and Of
(where Y is K and/or Rb, X is Ca, Sr
, Ba, Ti, V, Nb, Cr, In, pb and Ge
Indicates at least one metal selected from a, b, c
, d, e and f represent the number of atoms of Mo, P, Ta, Y, X and O, respectively, and when a=12, b=0.0
1-6, c=0.1-10, d=0.1-4, e=0-
10, and f changes depending on the oxidation state of the metal element).

As a method for preparing the catalyst, any method known in the field of oxidation reactions, such as an oxide mixing method, an evaporation to dryness method, and a coprecipitation method, may be employed.

Therefore, the catalyst preparation reagent does not necessarily have to be in the form of an oxide; it can be the metal itself, as long as it can be easily oxidized or decomposed during catalyst preparation and ultimately turn into an oxide.
It does not matter whether it is a metal salt, a metal acid or a base, etc.

Common examples of these include sulfates, organic acid salts,
These include ammonium salts and hydroxides.

Catalysts prepared by the aforementioned methods were tested at temperatures of 300 to
It is preferable to bake at 700°C (preferably 350 to 550°C) for 2 to 40 hours (preferably 5 to 30 hours).

Although the catalyst used in the method of the present invention can be used without a carrier, it is preferred industrially to use a carrier.

Specific examples of the carrier include carriers commonly used in oxidation reactions, such as silica, alumina, alundum, silicon carbide, pumice, and aluminum sponge.

Although the amount of the catalyst component supported on the carrier varies somewhat depending on the catalyst preparation method adopted, it is usually 1 to 1000 parts by weight based on 100 parts by weight of the carrier, assuming that the catalyst component is an oxide.

According to the present invention, an unsaturated carboxylic acid is produced in a high yield by passing the unsaturated aldehyde and molecular oxygen, preferably using a raw material gas mixed with an inert gas and water vapor, over the catalyst of the present invention at a high temperature. You can get it at

The reaction conditions for the catalytic reaction vary somewhat depending on the performance of the individual catalyst used, and there are interrelationships with conditions such as reaction temperature, contact time, and concentration of unsaturated aldehyde, so it cannot be generalized, but it is approximately It is as follows.

(1) Reaction temperature: 250 to 500°C (2) Reaction pressure: It can be carried out under increased pressure or reduced pressure, but preferably under normal pressure (3) Contact time: 0.1 to 20 seconds (4) Reaction of unsaturated aldehyde and oxygen Molar ratio; 1:0.5~
5.0 (5) Molar ratio of unsaturated aldehyde and water vapor; 1:1-5
0 The oxygen source is usually air, but pure oxygen or oxygen mixed with nitrogen or an inert gas such as carbon dioxide, helium, argon, or lower saturated hydrocarbons (methane, ethane, propane, butane, etc.) You can also use it.

The reaction product can be separated and recovered by a commonly used method, such as a condensation method, an extraction method, a distillation method, or any other suitable method.

Analysis in the following examples was by gas chromatography.

In addition, the reaction rate of acrolein and methacrolein, the selectivity to acrylic acid and methacrylic acid, and the single flow yield of acrylic acid and methacrylic acid were determined by the following formulas.

In addition, in the following examples, these mol% are simply written as %.

Example 1 Ammonium paramolybdate (NH,)6Mo7o244H20: 85% orthophosphoric acid H3 was added to an aqueous solution of 132.5 g dissolved in 500 ml of distilled water.
An aqueous solution of 7.2 g of PO dissolved in 20 ml of distilled water was added with stirring.

Add potassium nitrate KNO3 to the mixture in advance: 1 2.6
An aqueous solution prepared by dissolving 100 ml of distilled water was added with stirring.

Add tantalum pentoxide Ta205 to this mixed solution: 6.9
The catalyst component was supported on 300 g of silicon carbide by evaporation to dryness on a hot water bath while thoroughly stirring.

After supporting, it was dried at 130° C. for 16 hours, and then calcined in an air stream at 450° C. for 10 hours.

Component composition of the catalyst thus obtained (excluding oxygen)
was Mo12P1Ta0.5K2.

25 ml of the above catalyst was placed in a Pyrex glass reaction tube with an inner diameter of 20 mm, and methacrolein: air: water vapor = 4
．． A raw material gas with a molar composition of 6: 3 5.0: 6 0.4 was passed over the catalyst at a feed rate of SV 1000 hr'.
When the mixture was allowed to pass through and react at 70°C, the following results were obtained.

Methacrolein reaction rate = 64.1% Selectivity to methacrylic acid = 72.4% Single flow yield of methacrylic acid = 46.4% Examples 2 to 7 Molybdenum, Catalysts with different composition ratios of phosphorus, tantalum, and potassium were prepared.

Their component compositions (excluding oxygen) are shown in Table 1.

The oxidation reaction of methacrolein was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 1.

Examples 8 to 14 Potassium nitrate KN was prepared using the same catalyst preparation method as in Example 1.
A catalyst having the composition shown in Table 2 (excluding oxygen) was prepared by replacing O3 with rubidium nitrate RbNO3.

The oxidation reaction of methacrolein was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 2.

Example 15 Ammonium paramolybdate (NH4) 6Mo70244H20: 85% orthophosphoric acid H3 was added to an aqueous solution in which 132.5 g was dissolved in 500 ml of distilled water.
PO4: 7.2 g was dissolved in 20 ml of distilled water and an aqueous solution was added with stirring.

An aqueous solution in which 12.6 g of potassium nitrate KNO3 was dissolved in 100 ml of distilled water and 3.7 g of ammonium vanadate NH4VO3 were added to the mixed solution in 100 ml of distilled water.
were added with stirring.

Add tantalum pentoxide Ta205:6 to this obtained mixed solution.
．． Add 9g, evaporate to dryness on a hot water bath while stirring thoroughly,
The catalyst component was supported on 300 g of silicon carbide.

After being supported, it was dried at 130°C for 16 hours, and then dried in an air stream for 4 hours.
It was baked at 50°C for 10 hours.

Component composition of the catalyst thus obtained (excluding oxygen)
was Mot2P1Ta0.5V (1.5K2).

When the oxidation reaction of methacrolein was carried out using the above catalyst under exactly the same reaction conditions as in Example 1, the following results were obtained.

Reaction rate of methacrolein -67.8% Selectivity to methacrylic acid = 79.4% Single flow yield of methacrylic acid -53.8% Examples 16-28 A catalyst was prepared by the same method as in Example 15.

Their compositions are shown in Table 3 (excluding oxygen). Using these catalysts, methacrolein oxidation reaction was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 3.

Examples 29-30 A catalyst was prepared by the same method as in Example 16.

Their compositions are shown in Table 4 (excluding oxygen). An oxidation reaction of methacrolein was carried out using these catalysts under exactly the same reaction conditions as in Example 1.

The results are shown in Table 4. Examples 31 to 36 Using the catalysts of Examples 1, 11, 15, 23, 26, and 27, acrolein:air:steam-50:40.
The raw material gas with a molar composition of 0:55.0 is SV12
The oxidation reaction of acrolein was carried out by passing the mixture over the catalyst at 390° C. at a feed rate of 00 hr −1 .

The results are shown in Table 5. Comparative Examples 1 to 5 Using the same preparation method as Example 1, Mo12Ta0.5K2,
MO12P1K2, Mo12P1Ta0.5, Mo12
Catalysts P1Ta3 and Mo12P1Rb2 were prepared and methacrolein was oxidized under exactly the same reaction conditions as in Example 1. As shown in Table 6, the results were not good.

Examples 37-46 A catalyst was prepared using the same preparation method as in Example 15.

Their compositions are shown in Table 7 (excluding oxygen). Using these catalysts, methacrolein oxidation reaction was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 7.

Claims (1)

[Claims] 1. In producing an unsaturated carboxylic acid by catalytically oxidizing an unsaturated aldehyde with a gas containing molecular oxygen, (1) a catalyst containing Moa, Pb, Tac, Yd, and Of; , or (2) Moa, Pb, Tac, Yd, Xe and Of
(where Y is K and/or Rb, X is Ca, Sr,
At least one metal selected from Ba, Ti, ■, Nb, Cr, In, Pb and Ge, a, b, c,
d, e and f represent the number of atoms of Mo, P, Ta, Y, X and O, respectively; in the case of a-12, b-0.01
~6, C-0.1~10, d = 0. 1-4, e-
0 to 10, f changes depending on the oxidation state of the metal element)
A method for producing an unsaturated carboxylic acid, characterized by using.