JPS59160537A - Preparation of catalyst for manufacturing methacrylic acid - Google Patents

Abstract

PURPOSE:To obtain a catalyst having good reproducibility and securing a high methacrylic acid yield by mixing phosphomolybdic acid and compds. contg. other catalytic component elements therewith in the presence of water, concentrating, aging after adjusting the water content, and heat-treating at a specified temp. CONSTITUTION:When a heteropolyphosphoric acid-type catalyst is prepared, which contains phosphorus, molybdenum, copper and arsenic as catalytic component elements for manufacturing methacrylic acid by allowing isobutyl aldehyde to react with molecular oxygen in the presence of the catalyst at high-temp. vapor phase, phosphomolybdic acid is mixed compds. contg. other catalytic component elements (e.g. arsenic acid, copper oxide) in the presence of water. The obtd. solution or a slurry is concentrated or dried to adjust so as to obtain 5- 15wt% water content. After the product is aged, it is heat-treated at 100-300 deg.C. As a result, the catalyst having good moldability, high reproducibility and securing good methacrylic acid yield is prepared.

Description

Detailed Description of the Invention The present invention provides a heteropolyacid-based catalyst for producing methacrylic acid containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements, which can produce methacrylic acid from isobutyl aldehyde in high yield. It concerns a new manufacturing method.

A method for producing methacrylic acid by reacting inbutyraldehyde with molecular oxygen in a high-temperature gas phase in the presence of a heteropolyacid catalyst containing phosphorus, molybdenum, copper, and arsenic as catalyst components is already known. Heteropolyacid catalysts are generally prepared by starting with a compound containing the catalytic elements, such as an oxide or a phosphate, and adding a carrier if necessary, and mixing these in the presence of water or the like. It is produced by forming it into a solution or slurry, drying it, generally evaporating it to dryness, and optionally firing it (with or without molding) (Japanese Patent Application Laid-Open No. 5-118).
5-100325).

It also commonly contains phosphorus and molybdenum (
or its salt) has a Keggin structure as its skeletal structure,
It is said that the skeleton is surrounded by protons or cations and water of crystallization, and the water of crystallization of heteropolyacids ranges from 0 to 30 molecules.

We obtained phosphorus from inbutyral ahito.

The result of intensive research into a method for producing methacrylic acid using a heteropolyacid catalyst containing molybdenum, copper, and arsenic as catalyst components.

The inventors discovered that it was possible to increase the yield of methacrylic acid by improving the catalyst manufacturing method, leading to the present invention.

The present invention relates to phosphorus and molybdenum used for producing methacrylic acid by reacting isobutyraldehyde with molecular oxygen in the presence of a catalyst in a high-temperature gas phase.

In a method for producing a heteropolyacid-based catalyst for producing methacrylic acid containing copper and arsenic as catalyst component elements, compounds containing phosphomolybdic acid and other catalyst component elements are mixed in the presence of water.

The resulting solution or slurry is concentrated or dried.

Next, the moisture content in the concentrated or dried product is adjusted to 5 to 15% by weight, and then aged,
The present invention relates to a method for producing a catalyst for producing methacrylic acid, which is characterized by heat treatment at a temperature of 00°C.

The present invention is effective for producing a heteropolyacid-based catalyst for producing methacrylic acid containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements.

In addition to molybdenum, copper and arsenic, tungsten, iron, bismuth, antimony, cobalt, zinc, zirconium, calcium, chromium, boron, tin, titanium, palladium, tantalum, The present invention can be applied to the production of catalysts for producing methacrylic acid containing catalyst component elements such as cerium, vanadium, magnesium, silver, and aluminum.

Mo12 P,, C! ubAscXd, O8
[In the formula, +Mo is molybdenum, P is phosphorus, and Ou is copper.

As is arsenic, X is tungsten, iron, bismuth.

antimony, cobalt, zinc, boron, chromium.

One or more elements selected from the group consisting of zirconium, vanadium, titanium, and tin, and 0 represents oxygen, and the subscripts ae represent the number of atoms.

When the number of atoms of MO is 12, a=0.9 to 2. Preferably 1 to 1.6. b=Q', Q 05 to 0, preferably 0.01 to 1. c = 0.0' 1-2. Preferably 0.1-1', 5. d=0-2. Preferably o,
oo1 to 1°e are values determined by the valence of each component.

When applied to the production of a catalyst for the production of methacrylic acid from isobutyraldehyde represented by A catalyst is obtained that can be produced.

In the present invention, it is necessary to use phosphomolybdic acid as a source of molybdenum. If a molybdenum-containing compound other than phosphomolybdic acid, such as ammonium molybdate, is used as the molybdenum source, an ammonium salt of a heteropolyacid is produced, making it impossible to obtain a catalyst exhibiting sufficient selectivity.

Furthermore, for example, when molybdenum oxide, molybdic acid, etc. are used, it takes a long time to produce a stable phosphomolybdic acid compound, making it difficult to obtain a catalyst exhibiting sufficient catalytic performance.

As the molybdenum source used in the present invention, phosphomolybdic acid has an atomic ratio of phosphorus to molybdenum (P/Mo) of
It is not limited to 1/12, and the generally known P/M'O (atomic ratio) is 1/, 11,
'1/'10. '1/9. It may also be phosphomolybdic acid such as 2/, 17, etc.

In the present invention, first, a solution or slurry is prepared by mixing a compound containing phosphomolybdic acid and other catalyst component elements in the presence of water. Typical compounds containing other catalyst component elements include phosphoric acid, arsenic acid, arsenic oxide, copper oxide, etc., as well as oxides, hydroxides, carbonates, etc. of other catalyst component elements. be able to.

The mixing order for mixing compounds containing catalytic component elements, including phosphomolybdic acid, in the presence of water is not particularly limited, but preferably phosphomolybdic acid is dissolved first; then other catalyst component elements are dissolved. It is preferable to mix the compounds. In addition, after mixing, under stirring,
It is desirable to age the mixed solution or slurry at a temperature of 100°C, preferably 30-80°C, for 6 hours or more, preferably 5-30 hours. By aging the mixed solution slurry, a catalyst with higher methacrylic acid yield can be obtained. The reason why the yield of methacrylic acid is increased by this aging is not completely clear, but the crystal structure of the heteropolyacid of phosphomolybdic acid changes, and a new heteropolyacid containing other catalyst component elements is formed. It is assumed that this is not for the sake of safety.

In the present invention, organic reducing substances such as glycolic acid, glyoxylic acid,
Oxycarboxylic acids such as lactic acid.

Glycols such as ethylene glycol, fluoropylene glycol, polyalkylene glycol, dextrin,
Addition of sugars such as starch, aldose, and lactose improves the reproducibility of the catalyst.

Catalyst performance is also improved. What is the amount of organic reducing substances used?

Although it varies depending on the type of organic reducing substance used, it is 0.3 to 12% by weight, preferably 0.
．． A suitable amount is 5 to 9% by weight. If the amount of organic reducing substance used is too large or too small, the yield of methacrylic acid will be low. There is no significant difference in the catalytic performance of the resulting catalyst whether one type or multiple types of organic reducing substances are used.

In the present invention, compounds containing phosphomolybdic acid and other catalyst component elements are mixed in the presence of water, the resulting solution or slurry is concentrated or dried, and then the water content in the concentrated or dried product is is adjusted to 5 to 15% by weight, preferably 7 to 12% by weight. This adjustment can be carried out by concentrating the solution or slurry using a rotary evaporator until the water content in the concentrate falls within the above range, by drying the solution or slurry once using a method such as an evaporation drying method, a spray drying method, etc. It is convenient to do this by adding water to the dried material.

In the present invention, the water content is adjusted.

Let this mature. By aging, the reproducibility of the catalyst is improved and a catalyst exhibiting a high yield of methacrylic acid can be obtained. Aging is generally carried out at 15-50°C2, preferably at 20°C.
It is suitable to carry out the reaction at a temperature of -40 DEG C. for 2 hours or more, preferably for 5 to 25 hours, and the atmosphere at that time is suitably an oxygen-containing gas, such as an air atmosphere or a nitrogen gas atmosphere.

The aged concentrated or dried product is heated at 100 to 300°C2, preferably 120 to 200°C, without molding or molding.
Heat treatment at 50°C.

In the present invention, the adjustment of the moisture content of the concentrated or dried product, the aging after adjustment, and the heat treatment temperature are particularly important.

If the water content is not adjusted within the above range, a forceps medium showing a high yield of methacrylic acid cannot be obtained.

Furthermore, when molding a dried product, moldability is poor if the water content is too high or too low. Even if the water content of the shredded rice is adjusted within the above range, it may not ripen.

If the heat treatment temperature is too high or too low, a catalyst that exhibits a high yield of methacrylic acid with good reproducibility cannot be obtained.

In the present invention, the heat treatment must be carried out at the above-mentioned temperature, but in order to effectively carry out the heat treatment, it is necessary to adjust the moisture content and then ripen it beforehand at a temperature of 100 to 300"C.
It is desirable to rapidly heat treat the material in a heater heated to . The heat treatment time is generally 1 hour or more, and more preferably 5 to 2 hours.
0 hours is suitable, and the heat treatment is suitably carried out under an atmosphere of an oxygen-containing gas, such as air, or under a nitrogen gas atmosphere.

By adjusting the moisture content, aging, and then heat treatment, preferably rapidly at the above temperature, phosphorus, molybdenum, copper, and arsenic produced by conventional methods can be converted into catalytic component elements. The desired catalyst is obtained which exhibits a higher yield of methacrylic acid than when using a heteropolyacid-based catalyst containing as methacrylic acid. The reason for the improvement in methacrylic acid yield is not fully clear, but adjustment of water content.

It is thought that aging and heat treatment, as well as the use of organic reducing substances, cause changes in the crystal structure of the heteropolyacid, which further enhances the catalytic activity.

Each catalyst component element in the catalyst obtained by the present invention includes a mixture of heteropolyacids such as phosphomolybdic acid and their copper salts, a composite oxide in which a plurality of catalyst component elements are combined together with oxygen, and various Catalyst component element alone.

It exists as a mixture of oxides, etc.

In the present invention, a carrier may be added during catalyst production to produce the desired catalyst. Furthermore, when the catalyst obtained according to the present invention is used in the production of methacrylic acid, it may be used together with a carrier.

As the carrier, any of those conventionally known as carriers for catalysts for producing acrylic acid, methacrylic acid, etc. can be used.
Examples include diatomaceous earth, alumina, silica, silica sol, silicon carbide, and graphite.

In producing methacrylic acid by reacting inbutyraldehyde with molecular oxygen in the high temperature gas phase in the presence of the catalyst obtained according to the present invention, the molecular oxygen used in one reaction may be pure oxygen gas, but It is generally economical and convenient to use air since it does not need to be particularly pure. Further, in the reaction, it is preferable to use a diluent gas together with molecular oxygen and isobutyraldehyde. The diluent gas is one that does not adversely affect this reaction.

For example, nitrogen gas, carbon dioxide gas, water vapor, etc. can be used. Among them, water vapor not only has the effect of improving the selectivity of methacrylic acid, but also has the effect of sustaining the catalytic activity, so the reaction can be carried out in the presence of water vapor. It's good to do it.

Furthermore, the inbutyraldehyde used in the reaction does not need to be particularly pure, like molecular oxygen.

The catalyst obtained according to the present invention can be used in any reactor such as a fluidized bed, moving bed, or fixed bed reactor. It is generally advantageous to use a fixed bed reactor because it has the advantages of high reaction rate and high selectivity to methacrylic acid, and the ability to maintain catalytic activity over a long period of time.

The reaction may be carried out under normal pressure, increased pressure, or reduced pressure, but it is generally convenient to carry out the reaction under normal pressure. The reaction temperature is 200 to 400°C, preferably 250 to 35°C.
0°C, especially 260-320°C is preferred. Further, the contact time is 0.1 to 10 seconds.

Preferably, 0.5 to 5 seconds is appropriate. For the reaction, it is preferable to use a mixed gas of isobutyraldehyde and molecular oxygen, generally air, with water vapor added.The composition of the mixed gas is 9 molecular oxygen per 1 mole of isobutyraldehyde and 0.0. 5 to 7 moles, preferably 1 to 5 moles, and water vapor 0.5 to 30 moles, preferably 1 to 10 moles.
Preferably it is in moles.

In addition, methacrylic acid, which is the desired product, can be recovered by conventionally known methods 9, such as condensation.

Methods such as solvent extraction are applied.

Next, Examples and Comparative Examples will be shown. Response rate (person) in the example,
and yield (q6) follow the following definitions.

Reaction rate of isobutyraldehyde (1) = Yield of methacrylic acid (yield) = Yield of methacrolein (a) = Example 1 [Production of catalyst] Phosphormolybdic acid [H3P1M01204o・29H2
,0]1'001 to 300 weight m/? of water (approximately 25°C), add 0.349 of cupric oxide [CuO] and 607 of a 60q6 aqueous solution of arsenic acid [H3AsO4], mix, add 1 g of ethylene glycol, and stir at 50°C for 20 hours. Aged below.

Next, this mixed solution was concentrated under reduced pressure using a rotary evaporator until the water content became 10% by weight, and left at room temperature for 8 hours.
After putting it into a heater kept at ℃ and heat-treating it under a nitrogen atmosphere for 18 hours, 1 weight part of graphite was added to give 4 ru
It was molded into a pellet of nfl x 4 mmH, and the atomic ratio of molybdenum: copper: arsenic was 12:1:0.1:
A catalyst of 0.6 was obtained.

[Manufacture of methacrylic acid]

The above catalyst 9.3m? (13,11) was charged into a glass U-shaped reaction tube with an inner diameter of 8 doors, and this was filled with 4% by volume of inbutyraldehyde, 10 parts of oxygen, 0 parts of steam filter, and 5 parts of nitrogen.
6% mixed gas 4 Q OH1! The contact reaction was carried out for 1 hour at a flow rate of /min at a reaction temperature of 290°C. The contact time at that time was 1.4 seconds.

The results of the contact reaction are shown in Table 1.

Comparative Example 1 A catalyst was produced in the same manner as in Example 1, except that the water content was not adjusted and the catalyst was dried using a rotary evaporator, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. I did it.

The results of the contact reaction are shown in Table 1.

Comparative Example 2 Instead of phosphomolybdic acid in Example 1, ammonium molybdate [(NH4)6MO7'024・4H20
] 91g and 85% phosphoric acid [: a, Po4] 4.9
A catalyst was produced in the same manner as in Example 1, except that 9 was used, and the catalytic reaction was carried out under the same reaction conditions as in Example 1 (!). The results of the catalytic reaction are shown in Table 1.

Table 1 Example 2 [Production of catalyst] Phosphormolybdic acid [H3, PI Mo1204o・29
Dissolve 100 g of H2'O] in 300 liters of water (about 25°C).

Cupric oxide [0u(1)] 0.68? , 60% aqueous solution of arsenic acid (CH3AsO4) 6. Of and antimony trioxide (sb,,oa] 0.62 @ were added and mixed, ethylene glycol 22 was added, and the mixture was heated at 50°C.
Aged for an hour under stirring.

Next, this mixed solution was concentrated under reduced pressure using a rotary evaporator until the water content was 10% by weight, and the concentrate with a water content of 10% by weight was allowed to stand at room temperature for 24 hours (the water content in the concentrate was Almost no change), 1
Heat treated at 3[)°C for 10 hours, added 1% by weight of graphite and formed into pellets with Awnm
A catalyst of 2:1:0.2:0, 6:0.1 was obtained.

[Manufacture of methacrylic acid]

A catalytic reaction was carried out under the same reaction conditions as in Example 1 using the above catalyst.

The results of the contact reaction are shown in Table 2.

Example! 1 to 13 The catalyst manufacturing method was the same as in Example 2, except that the catalyst component elements were changed to have the atomic ratios listed in Table 2.

A catalyst was produced in the same manner as in Example 2, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. In addition to the phosphorus material described in Example 2 as a starting material for catalyst production, bimuth oxide [B12O3] was used as a bismuth source.

Tungsten oxide [WO3] is used as a tungsten source.

Chromium oxide [Cr2O3] was used as a chromium source, boric acid [:HaBOsl] was used as a boron source, and ferric oxide [Fe2O3] was used as an iron source. The results of the contact reaction are shown in Table 2. In addition, when the atomic ratio of P was 1 or more, phosphoric acid was added.

Comparative Example 3 A catalyst was produced in the same manner as in Example 2, except that the water content of the concentrate in Example 2 was changed from 10% by weight to 1% by weight, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. I did it.

The results of the contact reaction are shown in Table 6.

Comparative Example 4 A catalyst was produced in the same manner as in Example 2, except that the heat treatment temperature of 130°C in Example 2 was changed to 350°C.

A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of contact degree and response are shown in Table 6.

Example 14' Example 20 A catalyst was produced in the same manner as in Example 2, except that the aging at 50°C for 206 hours was changed to aging at 60°C for 15 hours, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. I did this.

The results of the contact reaction are shown in Table 6.

Example 15 The water content of the concentrate of Example 2 was reduced from 10% by weight to 15% by weight.
A catalyst was produced in the same manner as in Example 2, except that
A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of the contact reaction are shown in Table 6.

Example 16 A catalyst was produced in the same manner as in Example 2, except that the heat treatment temperature of 130°C in Example 2 was changed to 180°C.

A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of the contact reaction are shown in Table 3.

Table 3

Claims (1)

[Claims] A heteropolyacid-based catalyst for producing methacrylic acid containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements, which is used to produce methacrylic acid by reacting isobutyraldehyde with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. In the method for producing phosphomolybdic acid and other catalyst component elements, compounds containing phosphomolybdic acid and other catalyst component elements are mixed in the presence of water, the resulting solution or slurry is concentrated or dried, and then the water content in the concentrated or dried product is reduced. After adjusting to a weight of 5 to 15 degrees and aging, it is heated to 100 to 300 degrees.
1. A method for producing a catalyst for producing methacrylic acid, which is characterized by heat treatment at a temperature of C.