JPS581095B2 - 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 for the production of acrylic acid or methacrylic acid by gas-phase catalytic oxidation of acrolein or methacrolein, but these catalysts have advantages and disadvantages, and none are industrially satisfactory. Therefore, it was hoped that an improved catalyst would emerge.

For example, many previously proposed catalysts have low activity.

Some catalysts have relatively high activity and give high yields, but
Its high activity is only in the early stages and its lifespan is short.

Furthermore, 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.

As a result of intensive research into improving the catalyst used in the above reaction, the present inventors have found that by using a specific new catalyst, the corresponding unsaturated carboxylic acid can be produced from an unsaturated aldehyde in extremely high yield. The present inventors have discovered that the catalyst can be obtained with good reproducibility and has a long catalyst life, which is extremely advantageous for industrial production, and has thus arrived at the present invention.

The present invention uses a catalyst containing Moa1Pb, Xc, Yd and Oe (where X is Fe and/or Ni, Y is K, Rb
and Cs.

However, a1b, c, d and e represent the atomic ratio of each element, where a=12, b=0.01-6, c=0.0
1 to 10, d = 0. 1 and e change depending on the oxidation state of other elements) (excluding the combination of Mo-P-Ni-Cs).

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, a coprecipitation method, etc., may be employed.

However, the catalyst preparation reagent does not necessarily have to be in the form of an oxide; it may be a metal itself, a metal salt, There is no problem even if it is in any form such as a metal acid or base.

Specific examples thereof include nitrates, organic acid salts, ammonium salts, and hydroxides.

Catalysts prepared by the above-mentioned methods were tested at temperatures ranging from 300 to
2 to 4 at 700°C (especially preferably 350 to 550°C)
It is preferable to bake for 0 hours (particularly 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 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.

As the unsaturated aldehyde, acrolein, methacrolein, etc. can be used.

According to the present invention, unsaturated aldehyde and molecular oxygen are preferably mixed with an inert gas and/or water vapor, and the raw material gas is passed over the catalyst of the present invention at a high temperature to remove the unsaturated carboxylic acid. It can be obtained in high yield.

The reaction conditions for the catalytic reaction vary somewhat depending on the performance of the individual catalyst used, and there is a correlation among conditions such as reaction temperature, contact time, and concentration of unsaturated aldehyde, and although it cannot be generalized, it is generally as follows. It is.

(1) Reaction temperature: 250 to 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 (360 seconds in SV)
00 ~ 180hr) (4) Molar ratio of unsaturated aldehyde and oxygen; 1:0.5~
5.0 (5) Molar ratio of unsaturated aldehyde and water vapor; 1:1-5
0 (This reaction gives better results when water vapor is introduced.) Air is usually used as the molecular oxygen-containing gas, but pure oxygen or oxygen, nitrogen or carbon dioxide, helium, argon, or lower saturated hydrocarbons can also be used. (methane, ethane,
A mixture of inert gases such as propane, butane, etc. 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 unsaturated aldehydes such as acrolein and methacrolein; the selectivity to unsaturated carboxylic acids such as acrylic acid and methacrylic acid; and the single flow yield of unsaturated carboxylic acids such as acrylic acid and methacrylic acid are determined by the following formula: It was determined by

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

Example 1 To an aqueous solution in which 132.5 g of ammonium paramolyphthenate (NH4)6Mo7O24.4H2O was dissolved in 500 ml of distilled water, an aqueous solution in which 72 g of 85% orthophosphoric acid H3PO4 was dissolved in 20 ml of distilled water was added with stirring.

Potassium nitrate KNO3:12. 6g
An aqueous solution of was dissolved in 100 ml of distilled water was added with stirring.

Add ferric nitrate Fe(NO3)3・9H20 to this mixed solution.
: An aqueous solution of 6.3 g dissolved in 50 ml of distilled water was added while stirring.

This mixed solution was evaporated to dryness on a hot water bath while thoroughly stirring, and 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.

The component composition (excluding oxygen) of the obtained catalyst was Mo 12
P1Fe0.25K2.

Put 25 ml of the above catalyst into a Pyrex glass reaction tube with an inner diameter of 20 mm, and add methachloride: air: water vapor = 4.
．． When a raw material gas having a molar composition of 6:3 5.0:6 0.4 was passed over the catalyst at 370°C at a supply rate of SV 1000 hr-1 and reacted, the following results were obtained.

Reaction rate of methacrolein = 78.7% Selectivity to methacrylic acid = 62.0% Single flow yield of methacrylic acid = 48.8% Examples 2 to 7 and Comparative Examples 1 to 4 Same as Example 1 Catalysts with different composition ratios of molybdenum, phosphorus, iron, and potassium were prepared by a catalyst preparation method, and methacrolein oxidation reaction was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 1.

From these Examples and Comparative Examples, P with Mo as the main component
, Fe, and K are found to have high activity.

Examples 8 to 14 and Comparative Examples 5 to 6 Catalysts having the compositions shown in Table 2 were prepared in the same manner as in Example 1, except that rubidium nitrate was used instead of potassium nitrate.

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 2. From these Examples and Comparative Examples, it can be seen that a catalyst containing Mo as a main component in combination with P, Fe, and Rb is highly active.

Examples 15-21 and Comparative Examples 7-8 Catalysts having the compositions shown in Table 3 were prepared in the same manner as in Example 1, except that cesium nitrate was used instead of potassium nitrate.

Using these catalysts, the oxidation reaction of methachlorine was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 3. From these Examples and Comparative Examples, it can be seen that a catalyst containing Mo as a main component in combination with P, Fe, and Cs is highly active.

Example 22 Phosphomolybdic acid P205.24M0O3.nH20:
114. In an aqueous solution of Og dissolved in 200 ml of distilled water,
Preliminarily add 24.3 g of cesium nitrate CsN03 to 10 g of distilled water.
The aqueous solution and ferric nitrate Fe (NO3
) 3.9H20: An aqueous solution of 6.3 g dissolved in 50 ml of distilled water was added with thorough stirring.

This mixed solution was evaporated to dryness on a hot water bath while thoroughly stirring, and 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.

The obtained catalyst components (excluding oxygen) were the same as in Example 18 <Mo12 P1FeO. It was 25Cs2.

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 = 86.7% Selectivity to methacrylic acid = 63.9% Single flow yield of methacrylic acid = 55.4% Examples 23-24 Potassium nitrate or rubidium nitrate was used instead of cesium nitrate Catalysts having the same composition as in Examples 1 and 11 were prepared by the same method as in Example 22 except for this.

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 4. Examples 25 to 28 Using the catalysts of Examples 1, 11, 18, and 22, Example 1
The oxidation reaction of aclein was carried out under exactly the same reaction conditions.

The results are shown in Table 5. Example 29 A catalyst was prepared in the same manner as in Example 1, except that an aqueous solution of nickel nitrate Ni(NO3)2-6H20:4.5P dissolved in 50 ml of distilled water was used instead of ferric nitrate. did.

The component composition (excluding oxygen) of the obtained catalyst was Mo12P
It was 1Ni0.25K2.

When oxidation reaction of methacrolein was carried out under exactly the same reaction conditions as in Example 1 using 25 ml of the above catalyst, the following results were obtained.

Reaction rate of methacrolein = 75.1% Selectivity to methacrylic acid = 67.2% Single flow yield of methacrylic acid = 5 0. 5% Example 30
35 and Comparative Examples 9 to 12 Catalysts with different composition ratios of molybdenum, phosphorus, nickel, and potassium were prepared using the same catalyst preparation method as in Experiment 29, and methacrolein was prepared under exactly the same reaction conditions as in Example 1. An oxidation reaction was carried out.

The results are shown in Table 6.

From these Examples and Comparative Examples, P with Mo as the main component
, Ni, and K are found to have high activity.

Examples 36 to 42 and Comparative Examples 13 to 14 Example 2 except that rubidium nitrate was used instead of limestone potassium
A catalyst having the composition shown in Table 7 was prepared using the same method as in Example 9.

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.

From these Examples and Comparative Examples, it can be seen that a catalyst containing Mo as a main component in combination with P, Ni and Rb is highly active.

Examples 43-44 A catalyst was prepared using the same method as in Example 29.

Their composition (excluding oxygen) is shown in Table 8.

Using these catalysts, the oxidation reaction of methachlorene was carried out under exactly the same reaction conditions as in Example 1.

The results are shown in Table 8.

Examples 45-46 Using the catalysts of Examples 29 and 39, an oxidation reaction of acrolein was carried out under exactly the same reaction conditions as in Example 1.

Examples 47 to 48 and Comparative Example 1 whose results are shown in Table 9
5-19 Examples 18, 39 and Comparative Examples 2, 3, 6, 8
, 11 catalysts were used to conduct continuous experiments for 2 to 30 days, and the lifespan of each catalyst was investigated.

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

The results are shown in Table 10. It can be seen that the patented catalyst has a long life.

Examples 49-53 A catalyst was prepared in the same manner as in Example 22.

Their compositions (excluding oxygen) are shown in Table 11.

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 11.

Claims (1)

[Claims] 1. A catalyst containing Moa, Pb, Xc, Yd and Oe (
Here, X is Fe and/or Ni, Y is K, Rb
and Cs. However, a, b, c, d and e represent the atomic ratio of each element, where a=12, b=0.01-6, c=0.
01-10, d=0. 1 to 4 and e vary depending on the oxidation state of other elements) (However, Mo-P-Ni-Cs
(excluding combinations of).