JPS585173B2 - 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, when used industrially, there are few catalysts that give high yields, but even those that give high yields have poor reproducibility and are not always satisfactory.

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

The present inventors have conducted intensive research on catalysts used in the above reaction, and have found Mo, P, W, and Y.

A catalyst containing The inventors have discovered that carboxylic acids can be obtained in extremely high yields and with good reproducibility, and have arrived at the present invention.

That is, the present invention uses a catalyst containing Moa, Pb, Wc, Yd, Y is Cs and/or Tl, X is Ti
, Nb, Ta, In, and Ge, and a, b, c, d, and e each represent Mo,
Represents the number of atoms of P, W, Y and X, where a=12, b=0.01-6, c=0.1-10, d=0.1-
4, e=0.1-10.

)) provides a method for producing an unsaturated carboxylic acid.

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, but can be easily oxidized or decomposed during catalyst preparation and ultimately converted into an oxide, such as the metal itself, a metal salt, a metal acid, or There is no problem with anything, such as a base.

Common 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 40 at 700°C (preferably 350 to 550°C)
It is preferable to bake for a period of time (preferably 5 to 20 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, in the unsaturated aldehyde and molecular oxygen,
From an industrial standpoint, an unsaturated carboxylic acid can be obtained in high yield by using a raw material gas prepared by mixing an inert gas and water vapor and passing it over the catalyst of the present invention at high temperature.

The reaction conditions for the catalytic reaction vary somewhat depending on the performance of the individual catalyst used, and there are differences in conditions such as reaction temperature, contact time, and concentration of unsaturated aldehyde, so it cannot be generalized as follows. That's right.

(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 (4) Molar ratio of unsaturated aldehyde to oxygen: 1: 0.5
~5.0 (5) Molar ratio of unsaturated aldehyde to water vapor; 1:1
~50 Air is usually used as the oxygen source, but pure oxygen or oxygen can also be supplemented with an inert gas such as nitrogen or carbon dioxide, helium, argon, or lower saturated hydrocarbons (methane, ethane, propane, and butane, etc.). A mixture 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.

Also, the reaction rate of acrolein and methacrolein, and the selectivity to acrylic acid and methacrylic acid.

Single flow yields of acrylic acid and methacrylic acid were determined using the following formula.

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

Example 1 Ammonium paramolybdate (NH4)6Mo702
A solution prepared by dissolving 85% orthophosphoric acid H3PO4; 7.2 g in distilled water 20 was added to a solution obtained by dissolving 4.4H20; 132.59 in 500 ml of distilled water while stirring.

Add cesium nitrate C5NO3 to the mixture in advance; 24.3
．． 9 dissolved in 100 ml of distilled water, ammonium paratungstate (NH4) 1oW, 2041 5H20: an aqueous solution of 8.2 g dissolved in 300 ml of distilled water, and titanium oxide T
ie2: 5.09 powders were each added with stirring.

While this mixed solution was evaporated to dryness on a hot water bath, the catalyst component was supported on 300 g of silicon carbide.

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 catalyst thus obtained (excluding oxygen) was Mo 12 PlWo, 5 Cs 2 Ti 1.

The catalyst 25TLl obtained in the above manner had an inner diameter of 20 mm.
into a Pyrex glass reaction tube, methacrolein: air: water vapor = 4.6: 35.0: 60.4.
When a raw material gas having a molar composition of:

Reaction rate of methacrolein = 73.3% Selectivity to methacrylic acid = 75.6% Single flow yield of methacrylic acid = 55.5% Examples 2 to 10 A catalyst was prepared by the same method as in Example 1.

Their compositions are shown in Table 1 (however, oxygen was excluded).

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

Table 1 shows the results of the jc training.

Examples 11-14 Mo was prepared using the same catalyst preparation method as in Example 1.

Catalysts with different composition ratios of P, W, Cs or Tt, and the X component were prepared, and 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.

Comparative Examples 1-2 The catalyst shown in Table 3, which does not contain Cs or Tl, was used in Example 1.
Prepared by the same catalyst manufacturing method as in Example.

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

The results are shown in Table 3, and it is clear that the yield of methacrylic acid is significantly lower than that of the catalyst of the present invention.

Examples 15-16 Acrolein:Air using the catalysts of Examples 3 and 6:
Water vapor = 5. A raw material gas having a molar composition of O: 40.0:55.0 was reacted at 5V, 1200 hr, and 1,370°C.

The results are shown in Table 4. Examples 17-26 Catalysts were prepared by the same method as in Example 1, and their compositions are shown in Table 5 (however, oxygen was excluded).

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 5.

Claims (1)

[Claims] 1. In producing an unsaturated carboxylic acid by gas phase catalytic oxidation of an unsaturated aldehyde with a gas containing molecular oxygen, a catalyst containing Moa, Pb, Wc, Yd, Xe and 0 is used. where Y is Cs and/or Tl
, X represents at least one metal selected from Ti, Nb, Ta, In, and Ge, a, b, c, d, and e each represent the number of atoms of Mo, P, W, Y, and X, and a =
12, b=0.01-6, c=0.1-10
, d=0.1-4, e=0.1-10. ) A method for producing an unsaturated carboxylic acid, the method comprising: