JPS6176436A - Production of unsaturated carboxylic acid - Google Patents

Abstract

PURPOSE:To produce an unsaturated carboxylic acid in high yield and selectivity, by the vapor-phase catalytic oxidation of an unsaturated aldehyde with O2 in the presence of a catalyst prepared by adding a specific element to a catalyst composed of P, Mo, V, Cu, Sb and Ag, and having high catalytic activity and selectivity and long catalytic life. CONSTITUTION:The objective unsaturated carboxylic acid can be produced by the vapor-phase catalytic oxidation of an unsaturated aldehyde with O2 in the presence of a catalyst of formula I (X is K, Rb, Cs and/or Tl; Y is Zn, S, Cr, Si, Ge, Zr, Sn, Se, W, Ta, Te, Ni, Ba, Bi, As, B, Mg, Rh and/or Pd; a-i are atomic ratio of each element, and a=0.3-3, c=0.01-3, d=0.01-3, e=0.01-3, f=0.001-2, g=0.01-3, h=0.001-8 when b=12; i is the number of oxygen atoms necessary to satisfy the atomic valence of each component) (e.g. the catalyst having the elemental composition of formula II excluding oxygen).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a catalyst used in the production of unsaturated carboxylic acids by gas phase catalytic oxidation of unsaturated aldehydes.

[Conventional technology]

Conventionally, a large number of patents have been proposed regarding a method for producing a corresponding unsaturated carboxylic acid by vapor phase catalytic oxidation of an unsaturated aldehyde.

These mainly focus on methods for producing acrylic acid from aqutetralein, and when the catalysts proposed there are used for producing methacrylic acid, the selectivity is low due to large side reactions, and the life is short. On the other hand, many catalysts have been proposed for the production of methacrylic acid from methacrolein. 55-1920iS No. 59
No. -24140, No. 52-31327, JP-A-49-
There are many known such as No. 126616, but all of them are
It has drawbacks such as insufficient reaction performance, large drop in catalyst activity at red time, and too high reaction temperature, and currently two further improvements are desired when used as an industrial catalyst. .

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide a method for advantageously producing methacrylic acid from methacrolein, and the inventors of the present invention have conducted intensive research on the catalyst used in this process, and have improved the above-mentioned drawbacks and improved the activity, selectivity, and lifespan. Both of them found a highly practical catalyst, and further discovered that this catalyst can be applied to a method for producing acrylic acid from acrolein, leading to the completion of the present invention.

[Means for solving problems]

The present invention uses the general formula % formula % (where P, Mo, V, Cu, 8b, Ag and 0 are respectively Phosphorus, molybdenum, vanadium, copper, antimony, silver and oxygen; X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium; Y represents zinc, sulfur, chromium and silicon , kermanium, zirconium, tin, selenium, tungsten, tantalum, tellurium, nickel, barium,
Indicates at least one element selected from the group consisting of bismuth, arsenic, boron, magnesium, rhodium, and palladium.

However, “1bICIdl” If+g +h and 1
represents the atomic ratio of each element, and when b=12, a=CL
5-3, c-[101-3, dxO,01-A
, e = 0.01-5. f-α001~2,
g=0.01 to M, h=0.001 to 8, and 1 is the number of oxygen atoms necessary to satisfy the valences of each of the above components. ) is a method for producing an unsaturated carboxylic acid characterized by using a catalyst represented by:

[Effect]

According to the method of the present invention, it is possible to obtain an unsaturated carboxylic acid from an unsaturated aldehyde in high yield and high selectivity,
In particular, it maintains high catalytic activity over a long period of time, so it has extremely high industrial value.

The method for producing the catalyst used in the present invention does not need to be limited to a special method, and various conventionally well-known methods such as evaporation to dryness method and precipitation method may be used as long as the method does not involve significant uneven distribution of components. can be used.

As the raw material compounds used for the preparation of the catalyst, nitrates, carbonates, ammonium salts, -logenides, oxides, etc. of each element can be used in combination.

The catalyst used in the method of the present invention is extremely effective even without a carrier, but it can also be supported on an inert carrier such as silica, alumina, silica-alumina, silicon carbide, or diluted with an inert carrier.

The catalyst of the present invention is generally used in a fixed bed, but can also be used in a fluidized bed.

Although the concentration of unsaturated aldehyde in the raw material gas can be varied within a wide range, a range of 1 to 20% by volume is appropriate, and a range of 3 to 10% is particularly preferred.

The raw material unsaturated aldehyde may contain small amounts of impurities such as water and lower saturated aldehydes, but these impurities do not substantially affect the reaction.

It is economical to use air as the oxygen source, but air enriched with pure oxygen can also be used if necessary.

The oxygen concentration in the raw material gas is defined by the molar ratio to the unsaturated aldehyde, and this value is 0.3 to 4, especially α4 to 2.5.
is preferred.

The raw material gas may be diluted by adding an inert gas such as nitrogen, water vapor, or carbon dioxide. The reaction pressure is preferably from normal pressure to several atmospheres. Although the reaction temperature can be selected within the range of 230 to 450°C, 250 to 400°C is particularly preferred.

〔Example〕

The method of the present invention will be explained in more detail below with reference to Examples and Comparative Examples.

In the examples, parts represent parts by weight, and unsaturated carboxylic acid selectivity is the ratio (percentage) of the number of moles of unsaturated carboxylic acid produced to the number of moles of unsaturated aldehyde reacted.
represents.

Example 1 100 parts of ammonium paramolybdate, 2.8 parts of ammonium metavanadate, and 4.8 parts of potassium nitrate were dissolved in 400 parts of pure water. To this, add 85 tyrinic acid & 5 parts dissolved in 50 parts of pure water, and further add 1 part of tantalum oxide.
1 part and 6.9 parts of antimony trioxide were added, and the mixture was heated and stirred.

Next, 91 parts of steel nitrate dissolved in 100 parts of pure water and 0.8 parts of silver nitrate dissolved in 56 parts of pure water were added.
The mixture was evaporated to dryness while heating. The obtained solid product was dried at 160°C for 16 hours, then pressure molded, and then heated under air circulation for 3
The catalyst was heat-treated at 80° C. for 5 hours and used as a catalyst.

The composition of elements other than oxygen (the same applies hereinafter) of the obtained catalyst is P
H1M, oll v,, Cu6481) I A g
6. It was @ Kl Ta a64.

This catalyst was packed into a reactor, and 5 g of methacrolein and 1 g of oxygen were charged.
A mixed gas of 0% water vapor, 30% water vapor, and 55% nitrogen (volume To) was passed through the reactor at a reaction temperature of 290°C and a contact time of 16 seconds. When the product was collected and analyzed by gas chromatography, it was found that the methacrolein reaction rate was 84.1% and the methacrylic acid selectivity was 8a3.

When the reaction was continued for about 1000 hours under the same conditions, the methacrolein reaction rate was 818% and the methacrylic acid selectivity was 88.5.
%Met.

Examples 2 to 15 According to Example 1, 1 ml of each catalyst in Table 1 was added! L. The reaction was carried out under the same conditions as in Example 1, and the results shown in Table 1 were obtained.

Comparative Examples 1 to 3 The following comparative catalysts were prepared according to Example 1, and reacted under the same conditions as Example 1 to obtain the results shown in Table 2.

Example 16 Using the catalyst prepared in Example 1, acrolein 5
Oxygen ion, water vapor 30 cm, nitrogen 55 cm (volume: !1%)
When a mixed gas of
The acrylic acid selectivity was 94.1.

Claims (1)

[Claims] In producing an unsaturated carboxylic acid by gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen, the general formula PaMobVcCudSbeAgfXgYhOi (wherein P, Mo, V, Cu, Sb, Ag and O are Each represents phosphorus, molybdenum, vanadium, copper, antimony, silver and oxygen, X represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, and Y represents zinc, sulfur, chromium, silicon,
Indicates at least one element selected from the group consisting of germanium, zirconium, tin, selenium, tungsten, tantalum, tellurium, nickel, barium, bismuth, arsenic, boron, magnesium, rhodium, and palladium. However, a, b, c, d, e, f, g, h and 1 represent the atomic ratio of each element, and when b = 12, a = 0.3 to 3
, c=0.01~3, d=0.01~3, e=0.01
~3, f=0.001~2, g=0.01~3, h=0
．． 001 to 8, and i is the number of oxygen atoms necessary to satisfy the valence of each component. ) A method for producing an unsaturated carboxylic acid, characterized by using a catalyst represented by: