JPS5829290B2 - Method for producing unsaturated carboxylic acid - 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.

For example, many catalysts have low activity.

Even if a catalyst has high activity and gives a high yield, its high activity is only in the early stages and its lifespan is short.

Moreover, such catalysts have drawbacks such as low selectivity, which is an industrially important factor, and poor reproducibility, and are not necessarily industrially satisfactory.

The above drawbacks are particularly noticeable in the oxidation reaction of methacrolein to methacrylic acid, which is difficult to industrialize.
・.

The present inventors have conducted extensive research on the catalysts used in the above reaction, and have found that the corresponding unsaturated carboxylic acid can be produced 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, in the present invention, Moa, Pb, 'l'ac,...
YJ Catalyst containing Xe and Of (where Y is Cs
and/or T1, X is Ca, Sr, Ba, Ti,
represents at least one metal selected from Cr, In, Pb, Ge, alb, c, d, e and f each represent the number of atoms of Mo, P, Ta, Y, X and O, a-12 In the case, b=o, oi~6, c=0.1~1
01 d=0.1 to 4, e-0 to 10, and f changes depending on the oxidation state of the metal element.

) is provided.

Methods for preparing the catalyst include methods known in the oxidation reaction field;
For example, any method such as an oxide mixing method, evaporation to dryness method, or coprecipitation method may be employed.

Therefore, catalyst preparation reagents do not necessarily have to be in the form of oxides, but can be easily oxidized or decomposed during catalyst preparation and ultimately turn into oxides, such as metals themselves, metal salts, or metals. There is no problem whether it is an acid or a base.

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

Catalysts prepared by the above-mentioned methods were tested at temperatures ranging from 300 to
2-40 at 700°C (preferably 350-550°C)
It is preferred to bake for a period of time (preferably 5-30 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 employed, 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 high yield by using a raw material gas containing an unsaturated aldehyde and molecular oxygen, preferably a mixture of an inert gas and water vapor, and passing it over the catalyst of the present invention at high temperature. You can get it at a rate.

The reaction conditions for the catalytic reaction vary somewhat depending on the performance of the individual catalyst employed, and are interrelated with conditions such as reaction temperature, contact time, and concentration of unsaturated aldehyde. The details are as follows.

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

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 paramorifthenate (NH4)6Mo7024 4H20: 132.5
? To an aqueous solution in which 85% orthophosphoric acid H3PO4: 7.2f was dissolved in 20 ml of distilled water was added with stirring.

The mixed solution was mixed with an aqueous solution in which cesium nitrate C3NO324,31 was dissolved in 100 ml of distilled water in advance, and calcium nitrate Ca (NO3)2 4 H2Onia, 4 L? An aqueous solution prepared by dissolving .

Ta205:6.9 of tantalum pentoxide was added to the obtained mixed solution.
After stirring thoroughly, evaporate to dryness on a hot water bath to remove the catalyst component from silicon carbide 3.00? It was carried by

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

The component composition (excluding oxygen) of the obtained catalyst was Mo12
PHTa0.5 cao,! 'i Cs2.

25rnl of the catalyst obtained in the above manner was used with an inner diameter of 20m
yn Pyrex glass reaction tube, methacrolein: air: water vapor - 4,6: 35.0: 60.4
When a raw material gas with a molar composition of

Reaction rate of methacrolein - 63.1% Selectivity to methacrylic acid - 77.0% Single stream yield of methacrylic acid - 48.6% Examples 2 to 8 and Comparative Examples 1 to 5 Example 1 and Catalysts were prepared using a similar catalyst preparation method, and their compositions are shown in Table 1 (with the exception of 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 1. These Examples and Comparative Examples show that the catalyst activity of the present invention is significantly improved.

Example 9 Ammonium paramolyphthenate (NH4)6Mo7024-4 H2O: 132.5
? 85% orthophosphoric acid H3PO4 in an aqueous solution of 2? An aqueous solution of was dissolved in 20 ml of distilled water was added with stirring.

Add thallium nitrate TlNO3 to the mixture in advance: 33.
3? An aqueous solution of Ca (NO3)2 dissolved in 100 ml of distilled water and calcium nitrate Ca (NO3)2 4H20: 7.4? An aqueous solution prepared by dissolving .

Add tantalum pentoxide Ta205 to this mixed solution: 6.9
? was added and evaporated to dryness on a hot water bath with sufficient stirring to support the catalyst component on silicon carbide 3001.

After supporting, 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.

The component composition of the obtained catalyst (excluding oxygen, <) was Mo, □P, Tao, CaO1, T'i2.

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

Reaction rate of methacrolein - 63.0% Selection rate for methacrylic acid -77.3% Single flow yield of methacrylic acid - 48,7% Examples 10-16 and Comparative Examples 6-8 By the same catalyst preparation method as in Example 9, Adjust the catalyst* *Made.

Their compositions are shown in Table 2 (however, oxygen was excluded).

Using these catalysts, the oxidation reaction of methacrolein was carried out under the same reaction conditions as in Example 9.

The results are shown in Table 2. These Examples and Comparative Examples show that the catalyst activity of the present invention is significantly improved.

Examples 17 to 20 Using the catalyst of Examples 4.7.13.16, raw material gas having a molar composition of acrolein:air:steam-5,〇240.0:nose★55.0 was heated at 5V for 1200 hours.
The oxidation reaction of acrolein was carried out by passing the mixture over the catalyst at 370°C at a feed rate of '.

The results are shown in Table 3.

Example 21-32 A catalyst was prepared using the same catalyst preparation method as in Example 9.

Their compositions are shown in Table 4 (however, oxygen was excluded).

Using these catalysts, methacrolein oxidation reaction was carried out under exactly the same reaction conditions as in Example 9.

Claims (1)

[Claims] 1. In producing an unsaturated carboxylic acid by catalytically oxidizing an unsaturated aldehyde with a gas containing molecular oxygen, a catalyst containing Moa 1Pb, Tac, Yd, Xe and Of ( where Y is Cs and/or T
I, X are Ca, 5r1Ba, Ti, Cr11n,
represents at least one metal selected from Pb, Ge, a, b, c, d, e and f are MOIP, respectively;
It represents the number of atoms of Ta, Y, X and O, and in the case of a-12, b=0.01-6, C-0,1-10, d=0.
1 to 4, e=0 to 10, and f changes depending on the oxidation state of the metal element. ) A method for producing an unsaturated carboxylic acid, the method comprising: