JPH02240043A - Production of unsaturated carboxylic acid - Google Patents

Abstract

PURPOSE:To industrially and advantageously obtain the subject compound without deteriorating catalyst activity with time and causing problems is post- treatment by using a specific catalyst in catalytically oxidizing an unsaturated aldehyde in the vapor phase. CONSTITUTION:An unsaturated aldehyde is catalytically oxidized with molecular oxygen (the oxygen concentration is preferably 0.4-2.5 molar ratio based on the unsaturated aldehyde) in the vapor phase in the presence of a catalyst expressed by the formula (X is Cu, Zn, Bi, Cr, Mg, Ag, Ta, Ni, Mn, Ba or Ca; Y is As, Sb, Zr, B, Ge, Te or Ga; Z is K, Rb, Cs or Tl; a to i represent atomic ratios of the respective elements; when b is 12, a is 0.5-3; c is 0.01-3; d is 0.01-2; l is 0.01-2; f is 0.01-3; g is 0.01-3; h is 0.01-2; i is the number of oxygen atoms required to satisfy the valences of the above-mentioned respective components) to afford the objective compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a process for producing unsaturated carboxylic acids by using specific catalysts during the gas phase catalytic oxidation of unsaturated aldehydes.

[Conventional technology]

Conventionally, many proposals have been made regarding methods and catalysts for producing unsaturated carboxylic acids by gas-phase catalytic oxidation of unsaturated aldehydes. In particular, since heteroboric acid catalysts were discovered as catalysts for methacrolein oxidation, many patents have been filed regarding their improvements.
No. 74142, Japanese Unexamined Patent Publication No. 60-239459, Patent Application No. 1983
3-t72369, etc., but the reaction results are not satisfactory, the catalyst activity decreases greatly over time, and because nitrogen-containing heterocyclic compounds and other various compounds are used during catalyst preparation, post-treatment is required. It has drawbacks such as being complicated, and there is currently a need for further improvement when using it as an industrial catalyst.

[Purpose of the invention]

The present invention aims at providing a method for advantageously producing unsaturated carboxylic acids from unsaturated aldehydes.

[Means for solving problems]

In the present invention, in producing an unsaturated carboxylic acid by gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen, the general formula P Mo V Ce La
Oa be de fgh 1 (in the formula, P., Mo, V, Ce, La and O are phosphorus, molybdenum, vanadium, cerium, lanthanum and oxygen, respectively, X is copper, zinc, pismuth, chromium, magnesium, silver, tantalum, At least one element selected from the group consisting of nickel, manganese, barium and calcium; Y is at least one element selected from the group consisting of arsenic, antimony, zirconium, boron, germanium, tellurium and gallium; 2 is potassium, rubidium,
At least one element selected from the group consisting of cesium and thallium, a, b1C1d1e1 fSg1h and 1 indicate the atomic ratio of each element, and when b = 12, a =
0. 5-3, c=O. O j ~3, d=0
．． 01-2, e=o. Oj~2, f=0.01~3, g
= o. 01 to '5, h = 0.01 to 2, and 1 is the number of oxygen atoms necessary to satisfy the valence of each component). This is a method of cleaving carboxylic acids.

The present invention is characterized in that cerium and lanthanum are introduced in combination in a catalyst containing phosphorus, molybdenum, vanadium, and other specific elements. Since the catalyst used in the present invention has high activity, it is possible to achieve a sufficient yield of unsaturated carboxylic acid even at a lower reaction temperature, and as a result, high catalytic activity is maintained over a long period of time, so it has no industrial value. Extremely high. Although the effect of the combination of cerium and lanthanum on the catalyst is not strictly clear, it is thought that it provides an ideal oxidation-reduction balance.

The unsaturated aldehydes used as raw materials for the reaction of the present invention include acrolein, methacrolein, etc., and the unsaturated carboxylic acids obtained include acrylic acid, methacrolein, etc.

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

The raw materials for preparing the catalyst include nitrates of each element,
Carbonates, ammonium salts, halides, etc. can be used in combination. For example, molybdenum raw materials include Nononara ammonium molybdate, molybdenum trioxide,
As vanadium raw materials such as molybdenum chloride, ammonium metavanadate, vanadium pentoxide, vanadium chloride, etc. can be used.

The catalyst used in the method of the present invention may be unsupported, or may be supported on an inert carrier such as silica, alumina, silica-alumina, silicon carbide, or diluted with such an inert carrier.

In carrying out the present invention, the concentration of unsaturated aldehyde in the raw material gas can be varied within a wide range, but the concentration ranges from 1 to 2.
0% is suitable, and 6 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 preferably 0.6 to 4, particularly preferably 0.4 to 2.5. The raw material gas may be diluted by adding an inert gas such as nitrogen, water vapor, or carbon dioxide gas.

The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature is 23
It can be selected within the range of 0 to 450°C, but especially 250°C.
~400°C is preferred. The reaction can be carried out in a fixed bed or in a fluidized bed.

〔Example〕

Hereinafter, a method for preparing a catalyst according to the present invention and a reaction example using the same will be specifically explained.

In Examples and Comparative Examples, the reaction rate of unsaturated aldehyde and the selectivity of unsaturated carboxylic acid produced are defined as follows.

Parts in the following examples are parts by weight, and analysis was performed using gas chromatography.

Example 1 100 parts of ammonium baramolybdate, 2.76 parts of ammonium metavanadate, and 4.77 parts of potassium nitrate were dissolved in 300 parts of pure water. Add to this 85% phosphoric acid 8.1
A solution of 6 parts dissolved in 10 parts of pure water was added thereto, followed by 4.13 parts of antimony trioxide, and the temperature was raised to 95° C. with stirring. Next, 1.14 parts of nitric acid steel and 1.2 parts of sericum oxide.
A mixture of 30 parts of pure water and 62 parts of lanthanum oxide and 1.54 parts of lanthanum oxide was added, and the mixture was evaporated to dryness while heating and stirring. The obtained solid material was dried at 130° C. for 16 hours, pressure molded, and heat-treated at 380° C. for 5 hours to create air flow, which was then used as a catalyst.

The composition of elements other than oxygen (the same applies hereinafter) of the obtained catalyst is P
I,5MOHVO,5C8o,2teao. ，
Cuo. I Sbo, 6 K1.

A reaction tube was filled with the present catalyst, and a mixed gas of 5% methacrolein, 10% oxygen, 30% water vapor, and 55% nitrogen (volume %) was passed through the reactor at a reaction temperature of 270° C. and a contact time of 3.6 seconds.

When the product was collected and analyzed by gas chromatography, it was found that the methacrolein reaction rate was 896% and the methacrylic acid selectivity was 87.8%.

Examples 2 to 12 Each catalyst shown in the table below was prepared according to Example 1, and reacted under the same conditions as Example 1. The results are shown in the table.

Comparative Example 1 Comparative catalyst P 1.5 Mol, V6.5 CuO. l SbO
．． When 5 Kl was prepared and a reaction was carried out using this catalyst under the same reaction conditions as in Example 1, the methacrolein reaction rate was 80.5% and the methacrylic acid selectivity was 80.1%.

Comparative Example 2 Comparative catalyst P 1.5 MO12 V04 C e0,z Cuo according to Example 1
,ISb(,,6Kl) was prepared and a reaction was carried out using this catalyst under the same reaction conditions as in Example 1.The methacrolein reaction rate was 86.6% and the methacrylic acid selectivity was 88.
It was 0%.

Example 13 Using the catalyst split in Example 1, a mixed gas of 5% acrolein, 10% oxygen, 30% water vapor, and 55% nitrogen (by volume) was introduced into the catalyst at a reaction temperature of 270°C and a contact time of 6 seconds. As a result, the acrolein reaction rate was 92.5% and the acrylic acid selectivity was 94.6%.

Claims (1)

[Claims] In producing an unsaturated carboxylic acid by gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen, the general formula P_aMo_bV_cCe_dLa_eX_fY_gZ
_hO_i (in the formula, P, Mo, V, Ce, La and O are phosphorus, molybdenum, vanadium, cerium, lanthanum and oxygen, respectively, and X is copper, zinc, bismuth, chromium, magnesium, silver, tantalum, nickel, manganese, barium and at least one selected from the group consisting of calcium.
The seed element, Y is at least one element selected from the group consisting of arsenic, antimony, zirconium, boron, germanium, tellurium, and gallium, and Z is at least one element selected from the group consisting of potassium, rubidium, cesium, and thallium. Species elements, a, b, c, d, e, f, g, h
and i indicates the atomic ratio of each element, and when b=12, a=
0.5~3, c=0.01~3, d=0.01~2, e
=0.01~2, f=0.01~3, g=0.01~3
, h=0.01 to 2, and i is the number of oxygen atoms necessary to satisfy the valence of each component. Manufacturing method.