JP2671040B2 - Method for preparing catalyst for producing unsaturated carboxylic acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a catalyst used for producing an unsaturated carboxylic acid by vapor phase catalytic oxidation of an unsaturated aldehyde.

[Conventional technology]

Hitherto, many proposals have been made regarding a method and a catalyst for producing an unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gas phase catalytic oxidation. In particular, since the discovery of heteropolyacid catalysts as methacrolein oxidation catalysts, a number of patents have been submitted for their improvement.
There are 74142, JP-A-60-239439, Japanese Patent Application No. 63-172369, etc., but the reaction results are not sufficient, the catalytic activity is significantly decreased over time, and a nitrogen-containing heterocyclic compound during catalyst preparation or Since various other compounds and the like are used, they have drawbacks such as complicated post-treatment, and under the present circumstances, further improvement is desired when they are used as industrial catalysts.

[Object of the invention]

The present invention aims to provide a method for preparing a novel catalyst for advantageously producing an unsaturated carboxylic acid from an unsaturated aldehyde.

[Means for solving the problem]

The present inventors have conducted extensive studies to improve the conventional catalyst preparation method, and as a result, they are effective at a lower reaction temperature and have a higher yield of unsaturated carboxylic acid than when using a catalyst prepared by the conventional method. The method for preparing the resulting novel catalyst has been found.

The present invention has the general formula _{P a Mo b V c Ce d} La e X f Y g Z h O i ( where in the formula P, Mo, V, Ce, La and O represent phosphorus, molybdenum, vanadium, cerium, Lanthanum and oxygen, X is at least one element selected from the group consisting of iron, copper, zinc, bismuth, chromium, magnesium, silver, tantalum, nickel, manganese, barium and calcium, Y is arsenic, antimony, zirconium, Boron,
Germanium, at least one element selected from the group consisting of tellurium and gallium, Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, a, b, c, d, e, f,
g, h, and i represent the atomic ratio of each element, and when b = 12, a = 0.5 to 3, c = 0.01 to 3, d = 0.01 to 2, e = 0.01
˜2, f = 0 to 3 (preferably 0.01 to 3), g = 0 to 3
(Preferably 0.01 to 3), h = 0.01 to 2, and i is the number of oxygen atoms required to satisfy the valence of each component. ), A catalyst having a composition represented by
Unsaturated carboxylic acid production, characterized in that a complex oxide and / or a mixed oxide obtained by preliminarily heat treating a mixture of a component and a La component at a temperature of 500 to 1200 ° C. is introduced into the above general formula at the time of catalyst preparation. Is a method for preparing a catalyst for use.

In the present invention, by using a composite oxide and / or a mixed oxide obtained by previously heat-treating a mixture of a Ce component and a La component as a source of Ce and La in the catalyst component, the activity and the selectivity are increased. Is unexpected. Since the catalyst of the present invention has a high activity, it is possible to achieve a sufficient unsaturated carboxylic acid yield even at a lower reaction temperature, and as a result, a high catalytic activity is maintained over a long period of time, which is industrially valuable. Extremely high.

The unsaturated aldehyde used as a raw material for the reaction of the present invention is acrolein, methacrolein, etc., and the resulting unsaturated carboxylic acid is acrylic acid, methacrylic acid, etc.

The method for producing the catalyst used in the present invention does not need to be limited to a special method other than defining the Ce and La sources, and as long as there is no significant uneven distribution of the components, it is well known in the art to evaporate to dryness. Various methods such as a method, a precipitation method, and an oxide mixing method can be used.

Raw materials used to prepare catalysts other than Ce and La include nitrates, carbonates, ammonium salts, and halides of each element,
A combination of oxides and the like can be used. For example, as a molybdenum raw material, ammonium paramolybdate,
Molybdenum trioxide, molybdenum chloride or the like can be used, and as the vanadium raw material, ammonium metavanadate, vanadium pentoxide, vanadium chloride or the like can be used.

The method for preparing the complex oxide and / or the mixed oxide of lanthanum and cerium does not need to be limited to a special method, and known methods such as a thermal decomposition method of a nitrate mixed aqueous solution and a thermal decomposition by coprecipitation with ammonia can be performed. The method, the method of using various organic acids such as citric acid, and the like can be used. As raw materials for lanthanum and cerium, these oxides,
Hydroxides, chlorides, acetates, oxalates, sulfates, nitrates, carbonates, ammonium sulfates, ammonium nitrates and the like can be used.

The heat treatment temperature is preferably 500 to 1200 ° C, particularly preferably 500 to 1100 ° C. The Ce / La atomic ratio is particularly preferably 0.1-10. X-ray diffraction of complex oxides and / or mixed oxides of lanthanum and cerium detected individual diffraction lines of CeO ₂ and La ₂ O ₃ respectively, and partly because CeO ₂ diffraction lines were shifted. It is considered to form a solid solution or a complex oxide.

It is preferable to prepare the target catalyst by adding the composite oxide and / or mixed oxide of the Ce component and the La component thus obtained to an aqueous solution of another catalyst component and evaporating to dryness with heating and stirring. .

The catalyst obtained by the method of the present invention may be carrier-free, may be supported on an inert carrier such as silica, alumina, silica-alumina, and silicon carbide, or may be diluted with this carrier before use.

When using the catalyst prepared by the method of the present invention,
The concentration of the unsaturated aldehyde in the raw material gas can be varied over a wide range, but the volume is preferably 1 to 20%, particularly 3 to 10%. The raw material unsaturated aldehyde may contain a small amount of impurities such as water and lower saturated aldehydes, and these impurities do not substantially affect the reaction.

Although it is economical to use air as the oxygen source, air enriched with pure oxygen can be used if necessary. The oxygen concentration in the raw material gas is defined by the molar ratio with respect to the unsaturated aldehyde, and this value is preferably 0.3-4 and particularly 0.4-2.5. The source gas may be diluted by adding an inert gas such as nitrogen, steam, or carbon dioxide.

The reaction pressure is preferably normal pressure to several atmospheres. The reaction temperature is
The range of 230 to 450 ° C, particularly 250 to 400 ° C is preferable. The reaction can be carried out in a fixed bed or 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 described.

The reaction rates of unsaturated aldehydes and the selectivities of unsaturated carboxylic acids produced in Examples and Comparative Examples are defined as follows.

Parts in the following Examples and Comparative Examples are parts by weight, and analysis was carried out by gas chromatography.

Example 1 2.05 parts of cerium nitrate and 6.13 parts of lanthanum nitrate were dissolved in 30 parts of pure water. This was heated and stirred to evaporate most of the water, then heat-treated at 700 ° C. for 2 hours and finely pulverized (A powder).
Separately, 100 parts of ammonium paramolybdate, 2.76 parts of ammonium metavanadate and 4.77 parts of potassium nitrate are purified water.
It was dissolved in 100 parts. A solution prepared by dissolving 8.16 parts of 85% phosphoric acid in 10 parts of pure water was added thereto, and 4.13 parts of antimony trioxide was further added. The mixture was heated to 95 ° C. while stirring. Next, a solution prepared by dissolving 1.14 parts of copper nitrate in 30 parts of pure water was added. Powder A was added to this, and evaporated to dryness with heating and stirring. 13 solids obtained
After drying at 0 ℃ for 16 hours, press molding and under air flow at 380 ℃ for 5 hours.
What was heat-treated for a while was used as a catalyst. The composition of elements other than oxygen in the obtained catalyst (the same applies hereinafter) was P _1.5 Mo ₁₂ V _0.5 Ce _0.1 La _0.4 Cu _0.1 Sb _0.6 K ₁ .

This catalyst is filled in a reaction tube, and methacrolein 5%, oxygen
A gas mixture of 10%, water vapor 30%, and nitrogen 55% (volume%) was passed 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, the methacrolein conversion was 90.5% and the methacrylic acid selectivity was 88.5%.

Comparative Example 1 A comparative catalyst P _1.5 Mo ₁₂ V _0.5 Cu _0.1 Sb _0.6 K ₁ was prepared in the same manner as in Example 1 except that Ca and La were not added, and the reaction was performed under the same reaction conditions as in Example 1 using this catalyst. As a result, the reaction rate of methacrolein was 80.5% and the selectivity of methacrylic acid was 80.1%.

Comparative Example 2 In place of the A powder of Example 1, 0.81 part of cerium oxide and 3.08 part of lanthanum oxide were used, and the others were the same as in Example 1. Comparative catalyst P _1.5 Mo ₁₂ V _0.5 Ce _0.1 La _0.4 Cu _0.1 Sb _0.6 K ₁ Was prepared and the reaction was carried out using this catalyst under the same reaction conditions as in Example 1. The methacrolein conversion was 89.7% and the methacrylic acid selectivity was 87.7%.

Comparative Example 3 In Example 1, the heat treatment temperature of the A powder was 700 ° C. to 450 ° C.
The temperature was changed to 0 ° C., and a comparative catalyst P _1.5 Mo ₁₂ V _0.5 Ce _0.1 La _0.4 Cu _0.1 Sb _0.6 K ₁ was prepared in the same manner as in Example 1, and the reaction was carried out using this catalyst under the same reaction conditions as in Example 1. However, the methacrolein conversion rate was 89.1% and the methacrylic acid selectivity was 87.5%.

Example 2 6.15 parts of cerium nitrate and 3.07 parts of lanthanum nitrate were dissolved in 30 parts of pure water. To this was added 5.81 parts of 28% aqueous ammonia to obtain a yellowish white precipitate and a colorless solution. This was heated and stirred, most of the water was evaporated, and then dried at 120 ° C. for 16 hours. The dried product was heat-treated at 800 ° C. for 2 hours and finely pulverized (B powder).

The powder A was used in place of the powder A of Example 1, and the powder of Example 1 was used.
P ₁ Mo ₁₂ V ₁ Ce _0.3 La _0.2 Fe _0.2 Zn _0.1 As _0.1 K _0.5 Cs _0.5 was prepared according to the above, and the reaction was carried out under the same reaction conditions as in Example 1 using this catalyst. The reaction rate of methacrolein was 90.3. %, And the selectivity for methacrylic acid was 88.6%.

Examples 3 to 12 Each catalyst shown in the following table was prepared according to Example 1, and Example 1
The reaction was carried out under the same conditions as above, and the results shown in the following table were obtained.

Example 13 Using the catalyst prepared in Example 1, acrolein 5%,
When a mixed gas of oxygen 10%, water vapor 30% and nitrogen 55% (volume%) was introduced into the catalyst at a reaction temperature of 270 ° C. and a contact time of 3.6 seconds, the acrolein conversion rate was 93.6% and the acrylic acid selectivity was 95.4%.
%. 4

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-56-150436 (JP, A) JP-A-60-239439 (JP, A) JP-A-52-133893 (JP, A) JP-A-2- 119942 (JP, A) JP-A-2-22243 (JP, A) JP 59-13259 (JP, B1)

Claims (1)

(57) [Claims] 1. A general formula _{P a Mo b V c Ce d} La e X f Y g Z h O i ( where in the formula P, Mo, V, Ce, La and O represent phosphorus, molybdenum, vanadium, cerium , Lanthanum and oxygen, X is at least one element selected from the group consisting of iron, copper, zinc, bismuth, chromium, magnesium, silver, tantalum, nickel, manganese, barium and calcium, and Y is arsenic, antimony, zirconium. , Boron,
Germanium, at least one element selected from the group consisting of tellurium and gallium, Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, a, b, c, d, e, f,
g, h and i represent the atomic ratio of each element, and when b = 12, a = 0.5-3, c = 0.01-3, d = 0.01-2, e = 0.0
1 to 2, f = 0 to 3, g = 0. To 3 and h = 0.01 to 2 and i is the number of oxygen atoms required to satisfy the valence of each component). When preparing a catalyst having a composition, a mixture of Ce component and La component is preliminarily 500 to 1
A method for preparing a catalyst for producing an unsaturated carboxylic acid, which comprises introducing a composite oxide and / or a mixed oxide obtained by heat treatment at a temperature of 200 ° C. into the above general formula when preparing the catalyst.