JP4902991B2 - Method for producing oxide catalyst - Google Patents

Description

  In the present invention, propylene, isobutylene, tertiary butyl alcohol (hereinafter sometimes abbreviated as TBA) and methyl tertiary butyl ether (hereinafter sometimes abbreviated as MTBE) are vapor-phase catalytically oxidized by molecular oxygen. The present invention also relates to a method for producing an oxide catalyst used for producing an unsaturated aldehyde and / or an unsaturated carboxylic acid.

An oxide catalyst containing molybdenum, bismuth, and iron can be produced by, for example, propylene, isobutylene, TBA, MTBE by gas phase catalytic oxidation with molecular oxygen to produce the corresponding unsaturated aldehyde and / or unsaturated carboxylic acid. It is known as a catalyst used in the process.
As a method for producing such an oxide catalyst, after preparing a raw material liquid containing at least molybdenum, bismuth, and iron, the solvent is removed from the raw material liquid, and steps such as drying and firing are appropriately performed. The method is common. For example, in Patent Document 1, as a method for preparing a raw material liquid containing at least molybdenum, bismuth, and iron, an aqueous solution or dispersion containing molybdenum is prepared in advance, and bismuth trioxide is added thereto, followed by ultrasonic waves. A method of treating and then mixing this with an aqueous solution or dispersion containing iron is disclosed, and according to such a method, a high performance oxide catalyst is obtained.
Japanese Patent Laid-Open No. 8-24652

  However, conventional oxide catalysts containing molybdenum, bismuth and iron are not necessarily sufficient in catalytic activity and selectivity, and further improvement in performance is desired.

  This invention is made | formed in view of the said situation, and makes it a subject to manufacture the oxide catalyst excellent in catalyst activity and selectivity.

As a result of intensive studies, the present inventors have found that when producing an oxide catalyst using bismuth trioxide as a bismuth raw material, there is a relationship between the catalytic performance of the obtained oxide catalyst and the sodium content in bismuth trioxide. In addition, since bismuth trioxide used conventionally has a high sodium content, it was found that an oxide catalyst having sufficient performance could not be obtained, and the present invention was completed.
The method for producing an oxide catalyst of the present invention comprises the step of subjecting at least one selected from the group consisting of propylene, isobutylene, tertiary butyl alcohol, and methyl tertiary butyl ether to gas phase catalytic oxidation with molecular oxygen to produce an unsaturated aldehyde. And / or a method for producing an oxide catalyst having a composition represented by the following formula (1) used when producing an unsaturated carboxylic acid, a molybdenum raw material containing molybdenum, a bismuth raw material containing bismuth, And a step of preparing a raw material liquid containing an iron raw material containing iron, wherein the bismuth raw material is bismuth trioxide having a sodium content of 40 ppm or less in terms of mass.
_{Mo a Bi b Fe c M d} X e Y f Z g Si h O i ··· (1)
(In the formula (1), Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively, and M represents at least one element selected from the group consisting of cobalt and nickel. , X represents at least one element selected from the group consisting of chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc, and Y represents phosphorus, boron, sulfur, selenium, tellurium Represents at least one element selected from the group consisting of cerium, tungsten, antimony and titanium, and Z represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium A, b, c, d, e, f, g, h and i represent the atomic ratio of each element, and when a = 12. b = 0.01 to 3, c = 0.01 to 5, d = 1 to 12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, h = 0 to 20, i is the oxygen atom ratio necessary to satisfy the valence of each component.
The raw material liquid may contain a raw material of an element other than molybdenum, bismuth, and iron, and its property may be either a solution or a dispersion. The raw material liquid may be prepared by mixing the raw materials in any order. (1) Prepare a solution or dispersion containing at least a molybdenum raw material and a solution or dispersion containing at least an iron raw material, respectively. And, after adding bismuth trioxide to at least one of them, a method of mixing them, or (2) a solution or dispersion containing at least a molybdenum raw material and a solution or dispersion containing at least an iron raw material, respectively After the preparation, it is preferably produced by a method of mixing them and adding bismuth trioxide to the obtained mixed solution.
Moreover, it is preferable that the said raw material liquid is hold | maintained in the temperature range of 80-120 degreeC after the said process.

  According to the present invention, an oxide catalyst having excellent catalytic activity and selectivity can be produced.

Hereinafter, the present invention will be described in detail.
The oxide catalyst produced by the production method of the present invention is obtained by subjecting at least one selected from the group consisting of propylene, isobutylene, TBA, and MTBE to gas phase catalytic oxidation with molecular oxygen to produce the corresponding unsaturated aldehyde and / or It is used when producing an unsaturated carboxylic acid, and contains at least molybdenum, bismuth, and iron. The oxide catalyst produced by the production method of the present invention is not particularly limited as long as it contains molybdenum, bismuth, and iron, but is represented by the following formula (1) because the catalyst performance is good. Are preferred.

_{Mo a Bi b Fe c M d} X e Y f Z g Si h O i ··· (1)
In the formula (1), Mo, Bi, Fe, Si and O each represent molybdenum, bismuth, iron, silicon and oxygen, M represents at least one element selected from the group consisting of cobalt and nickel, X represents at least one element selected from the group consisting of chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc, and Y represents phosphorus, boron, sulfur, selenium, tellurium, Z indicates at least one element selected from the group consisting of cerium, tungsten, antimony and titanium, and Z indicates at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium. a, b, c, d, e, f, g, h, and i represent the atomic ratio of each element, and when a = 12, b = 0.01-3, c = 0.01-5, d = 1 to 12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, h = 0 to 20, and i is an oxygen atom necessary for satisfying the valence of each component. It is a ratio.

When producing such an oxide catalyst, first, a raw material of each element constituting the catalyst, that is, a molybdenum raw material containing molybdenum, a bismuth raw material containing bismuth, and an iron raw material containing iron. A raw material liquid containing at least is prepared.
The molybdenum raw material and iron raw material used here are not particularly limited, and include oxides, chlorides, hydroxides, sulfates, nitrates, carbonates, ammonium salts that can be converted into oxides when ignited. used. Specifically, ammonium paramolybdate, molybdenum trioxide, molybdenum chloride, or the like can be used as the molybdenum raw material, and ferric nitrate, iron hydroxide, iron trioxide, or the like can be used as the iron raw material. These may be used singly or as a mixture of two or more thereof. Among these, it is preferable to use ammonium paramolybdate as the molybdenum raw material, and as the iron raw material, second nitrate. It is preferable to use iron.

  As the bismuth material, bismuth trioxide having a sodium content of 40 ppm or less in terms of mass is used. When such bismuth trioxide having a sodium content is used, an oxide catalyst having excellent catalytic activity and selectivity can be obtained with good reproducibility. The more preferable sodium content of bismuth trioxide is 20 ppm or less, and the more preferable sodium content is 10 ppm or less. From the viewpoint of the catalytic activity and selectivity of the resulting oxide catalyst, there is no preferable lower limit of sodium content, but from the viewpoint of easy availability of the bismuth trioxide raw material, the preferable lower limit is 0.5 ppm.

When bismuth trioxide having a sodium content of 40 ppm or less in terms of mass is used as the bismuth raw material, the reason why an oxide catalyst having excellent catalytic performance is not clear, but is considered as follows.
That is, the active site of the oxide catalyst containing molybdenum, bismuth, and iron is considered to be a molybdenum-bismuth composite oxide. However, when sodium is contained in the bismuth trioxide used, the molybdenum-bismuth composite oxidation. It can be inferred that sodium is entrapped in this when an object is formed and is present in the vicinity of the active site. Therefore, even if the amount of sodium contained in bismuth trioxide is small, it is considered that the activity and selectivity of the resulting catalyst are adversely affected. Therefore, it is considered that by using bismuth trioxide having a sodium content of 40 ppm or less in terms of mass, such an adverse effect is eliminated and an oxide catalyst having excellent catalytic performance can be obtained.

  In addition, bismuth trioxide having a sodium content of 40 ppm or less is highly reactive, and is good as a raw material of other elements even if a special treatment such as ultrasonic treatment is not essential as in Patent Document 1 exemplified above. Therefore, the production time of the oxide catalyst can be shortened and the production cost can be reduced.

  The method for controlling the sodium content in bismuth trioxide to 40 ppm or less is not particularly limited, but in the bismuth trioxide obtained by not using a sodium compound such as sodium hydroxide during the production process of bismuth trioxide. A method that suppresses the mixing of sodium into the is preferable.

  There is no particular limitation on the method of preparing a raw material liquid containing at least a molybdenum raw material, bismuth trioxide having a sodium content of 40 ppm or less, and an iron raw material. If these raw materials are contained in a predetermined amount in the raw material liquid Good. That is, after preparing each raw material solution or dispersion liquid, the method of mixing all these liquids may be used, the method of adding all the raw materials in the solvent put into one container, etc. may be sufficient. Moreover, also as the addition method of each raw material, the whole quantity may be added at once, and you may add in multiple times.

As a preferable method for preparing a raw material liquid, (1) a solution or dispersion containing at least a molybdenum raw material (hereinafter sometimes referred to as “A liquid”) and a solution or dispersion containing at least an iron raw material (hereinafter referred to as “B liquid”). And, after adding bismuth trioxide to at least one of these, namely, A liquid and / or B liquid, and mixing them, (2) A liquid and B liquid After preparing each, the method of mixing A liquid and B liquid and adding bismuth trioxide to the obtained liquid mixture is mentioned.
Here, the liquid A does not contain an iron raw material, and the liquid B does not contain a molybdenum raw material from the viewpoint of the catalyst performance of the resulting oxide catalyst.

A more preferable method for preparing the raw material liquid is a method of adding bismuth trioxide to the prepared liquid A among the methods (1).
Further, after the addition of bismuth trioxide, the liquid may be atomized and homogenized by a homogenizer.
As a more preferable method of preparing the raw material liquid, a fine particle is obtained with a homogenizer for the liquid A to which bismuth trioxide is added or for the liquid A to which bismuth trioxide is added and the liquid B is further mixed. The method of making it uniform is mentioned. According to this method, it is considered that the catalyst precursor formed in the raw material liquid becomes more uniform and an oxide catalyst with better performance can be obtained.
Further, in order to further improve the catalyst performance of the oxide catalyst, the obtained raw material liquid may be subjected to ultrasonic treatment.

When the produced oxide catalyst has a composition represented by the above formula (1), for example, each raw material other than molybdenum, bismuth, and iron is contained in a predetermined amount in the raw material liquid finally obtained. As long as it is done, it may be added at any timing. For example, it may be added to liquid A and / or liquid B during or after preparation, or may be added to a mixed liquid of liquid A and liquid B. Further, it may be added to the liquid A and / or the liquid B to which bismuth trioxide is added, or may be added to a mixed liquid of the liquid A and the liquid B to which bismuth trioxide is added.
As raw materials for elements other than molybdenum, bismuth and iron, oxides, carbonates, chlorides, ammonium salts, nitrates, acetates, sulfates, metals, sparingly soluble compounds, etc. are generally used as catalyst raw materials. In addition to many water-soluble compounds, various raw materials can be used.

A solvent such as water, alcohol or acetone can be used for preparing the liquid A or liquid B. These may be used singly or in combination of two or more, but it is preferable to use at least water as a solvent, and 50 to 100% by mass of the whole solvent is preferably water.
As for the mass of the solvent used for preparation of A liquid, 70-270 mass parts is preferable with respect to a total of 100 mass parts of the catalyst raw material added to A liquid. As for the mass of the solvent used when preparing B liquid, 30-230 mass parts is preferable with respect to a total of 100 mass parts of the catalyst raw material added to B liquid.

After preparing the raw material liquid in this way, it is preferable to maintain the prepared raw material liquid in a temperature range of 80 to 120 ° C. A more preferable temperature range is 90 to 110 ° C. By maintaining the raw material liquid in such a temperature range, the catalytic performance of the resulting oxide catalyst is further improved. Such a temperature range is advantageous in terms of production cost of the oxide catalyst because it is on the lower temperature side than the temperature range of 100 to 200 ° C. disclosed as a suitable holding temperature in Patent Document 1.
Although it does not specifically limit as holding time which hold | maintains a raw material liquid at 80-120 degreeC, The range of 1 second-30 hours is suitable, Preferably it is 1 minute-20 hours, Most preferably, it is 3 minutes-15 hours. This is because the catalyst performance can be improved by holding for at least 1 second, but the effect obtained is not so much improved even if held for more than 30 hours. Although it is not clear why the catalyst performance of the resulting oxide catalyst is further improved by maintaining the raw material liquid at 80 to 120 ° C., a catalyst precursor having a more preferable structure is formed at this point. We believe that the catalyst performance will be improved.

Thus, preferably, after the raw material liquid is kept at 80 to 120 ° C., the raw material liquid is dried.
As a drying method, various drying methods such as a drying method using a box dryer, an evaporation drying method, and a spray drying method can be employed. The drying conditions are preferably 30 to 150 ° C. when a box dryer is used, and preferably 100 to 500 ° C. at the inlet temperature when a spray dryer is used.

After drying the raw material liquid in this way, it is preferable to fire the obtained dried product.
There are no particular limitations on the firing conditions, and known firing conditions can be applied. However, the firing may be performed usually in the air at a firing temperature of 200 to 600 ° C.

The oxide catalyst thus obtained may be used as it is, but may be molded.
There is no particular limitation on the molding method, and any shape such as a spherical shape, a ring shape, a cylindrical shape, or a star shape may be used using a general powder molding machine such as a tableting molding machine, an extrusion molding machine, or a rolling granulator. Can be formed into a shape. Moreover, you may add conventionally well-known additives, for example, organic compounds, such as polyvinyl alcohol and carboxymethylcellulose, to an oxide catalyst at the time of shaping | molding. In addition, inorganic compounds such as graphite and diatomaceous earth, inorganic fibers such as glass fiber, ceramic fiber, and carbon fiber may be added.
In addition, an oxide catalyst can be supported on a carrier. Examples of the carrier include silica, alumina, silica-alumina, magnesia, titania, silicon carbide and the like.

About the oxide catalyst shape | molded as needed or carry | supported by the support | carrier, you may heat-process further as needed.
The heat treatment conditions are not particularly limited, and known heat treatment conditions can be applied. The heat treatment is usually performed in a temperature range of 300 to 600 ° C.

  The oxide catalyst thus obtained is diluted with an inert substance such as silica, alumina, silica-alumina, magnesia, titania, silicon carbide, etc., if necessary, and then from propylene, isobutylene, TBA, MTBE. It is used when at least one raw material selected from the group is subjected to gas phase catalytic oxidation with molecular oxygen to produce the corresponding unsaturated aldehyde and / or unsaturated carboxylic acid.

As a specific reaction method, a reactor such as a fixed bed reactor or a fluidized bed reactor in which an oxide catalyst is placed is mixed with one raw material selected from the group consisting of propylene, isobutylene, TBA, and MTBE and a molecular form. A method of circulating a source gas containing oxygen is suitable.
At this time, the molar ratio of the raw material to molecular oxygen is preferably in the range of raw material: molecular oxygen = 1: 0.5-3. Although it is economical to use air as the molecular oxygen source, air to which pure oxygen is added, that is, oxygen-enriched air may be used as necessary. Moreover, it is preferable that the source gas further contains an inert gas for dilution.
The reaction temperature is preferably 200 to 450 ° C., more preferably 250 to 400 ° C., and the reaction pressure is suitably set within a range from normal pressure to several atmospheres.

Hereinafter, the present invention will be specifically described with reference to examples. In each example, “part” means part by mass.
The sodium content of bismuth trioxide was determined by quantitative analysis using atomic absorption spectrometry.
The catalytic performance of the oxide catalyst was evaluated by determining the activity (reaction rate of raw materials) when propylene, isobutylene or TBA was vapor-phase contact oxidized and the selectivity of unsaturated aldehyde and unsaturated carboxylic acid. At this time, the reaction gas was analyzed by gas chromatography.
The reaction rate of the raw material, the selectivity of the produced unsaturated aldehyde and unsaturated carboxylic acid are respectively defined as follows.
Reaction rate of raw material (%) = (number of moles of reacted raw material / number of moles of supplied raw material) × 100
Selectivity of unsaturated aldehyde (%) = (number of moles of unsaturated aldehyde produced / number of moles of reacted raw material) × 100
Selectivity of unsaturated carboxylic acid (%) = (number of moles of unsaturated carboxylic acid produced / number of moles of reacted raw material) × 100
The bismuth trioxide used in the following examples was produced by a method in which a sodium compound such as sodium hydroxide usually used in the production process of bismuth trioxide was not used or reduced. As the bismuth trioxide used in the comparative example, commercially available bismuth trioxide (manufactured by Sumitomo Metal Mining) was used.

<Example 1>
Under a temperature condition of 60 ° C., 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, and 1.4 parts of potassium nitrate were added to 1,000 parts of water and dissolved to obtain a solution A. Subsequently, when 44.0 parts of bismuth trioxide having a sodium content of 3 ppm was added to the solution A, a white suspension was formed.
Separately, 133.5 parts of ferric nitrate, 14.0 parts of zinc nitrate, and 322.8 parts of cobalt nitrate were sequentially added to 1,000 parts of pure water to obtain a liquid B.
And B liquid was added to the said A liquid which is a white suspension, and it was set as the slurry-like C liquid.
Subsequently, 10.4 parts of antimony trioxide was added to C solution to prepare a raw material solution.
Thereafter, the raw material liquid was kept (aged) at 80 ° C. for 1 hour, and then most of the water was evaporated.
The obtained cake-like substance was dried at 120 ° C., then fired at 300 ° C. for 1 hour in an air atmosphere and pulverized. Then, once pressure-molded, it was crushed, and among these crushed particles, a particle that passed through a sieve having an aperture of 2.36 mm and not passed through a sieve having an aperture of 0.71 mm was obtained. Thereafter, the particles having a specific size thus classified were again heat-treated in an air atmosphere at 500 ° C. for 6 hours to obtain an oxide catalyst.

The composition of the elements other than oxygen in the obtained oxide catalyst was Mo ₁₂ Bi _0.8 Fe _1.4 Co _4.7 Zn _0.2 W _0.1 Sb _0.3 K _0.06 .
After filling this oxide catalyst into a stainless steel reaction tube, a raw material gas consisting of 5% propylene, 12% oxygen, 10% water vapor, and 73% nitrogen (volume%) is circulated in this reaction tube, and the catalyst layer is contacted with the catalyst. The catalyst performance was evaluated by passing the solution in 3.6 seconds and reacting at 310 ° C. As a result, as shown in the table, the reaction rate of propylene was 99.8%, the selectivity of acrolein was 92.9%, and the selectivity of acrylic acid was 6.7%.

<Example 2>
Except for using bismuth trioxide having a sodium content of 18 ppm, an oxide catalyst was produced in the same manner as in Example 1, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of propylene was 99.5%, the selectivity of acrolein was 92.4%, and the selectivity of acrylic acid was 6.7%.

<Example 3>
Instead of adding bismuth trioxide to liquid A, it is added to liquid C, which is a mixture of liquid A and liquid B in the same manner as antimony trioxide. An oxide catalyst was produced in the same manner as in Example 1 except that the time was maintained, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of propylene was 99.6%, the selectivity of acrolein was 92.5%, and the selectivity of acrylic acid was 6.8%.

<Comparative Example 1>
An oxide catalyst was produced in the same manner as in Example 1 except that a bismuth trioxide having a sodium content of 50 ppm was used, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of propylene was 98.0%, the selectivity of acrolein was 89.0%, and the selectivity of acrylic acid was 6.2%.

<Comparative example 2>
Example 1 except that bismuth trioxide having a sodium content of 50 ppm was subjected to ultrasonic treatment at 60 ° C. for 1 hour on the liquid A, which was a white suspension after addition of bismuth trioxide. An oxide catalyst was produced in the same manner as described above, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of propylene was 99.5%, the selectivity of acrolein was 92.0%, and the selectivity of acrylic acid was 6.5%.

<Example 4>
A liquid A was prepared by adding 500 parts of ammonium paramolybdate, 6.2 parts of ammonium paratungstate, and 27.6 parts of cesium nitrate to 1,000 parts of water under a temperature condition of 60 ° C. Subsequently, when 27.5 parts of bismuth trioxide having a sodium content of 3 ppm was added to the solution A, a white suspension was formed.
Separately, 1000 parts of pure water was added with 200.2 parts of ferric nitrate, 78.9 parts of nickel nitrate, 14.0 parts of zinc nitrate, and 357.1 parts of cobalt nitrate. It melt | dissolved and it was set as B liquid.
And B liquid was added to the said A liquid which is a white suspension, and it was set as the slurry-like C liquid.
Subsequently, 24.1 parts of antimony trioxide was added to the liquid C to obtain a raw material liquid.
Thereafter, the raw material liquid was kept (aged) at 80 ° C. for 1 hour, and then most of the water was evaporated.
About the obtained cake-like substance, the process similar to Example 1 was implemented and it was set as the oxide catalyst.

The composition of elements other than oxygen in the obtained oxide catalyst was Mo ₁₂ Bi _0.5 Fe _2.1 Ni _2.3 Co _5.2 Zn _0.2 W _0.1 Sb _0.7 Cs _0.6 . there were.
After filling this oxide catalyst into a stainless steel reaction tube, a raw material gas consisting of 5% isobutylene, 12% oxygen, 10% water vapor and 73% nitrogen (volume%) is circulated in this reaction tube, and the catalyst layer is contacted with the catalyst for a contact time. It was passed in 3.6 seconds and reacted at 340 ° C. to evaluate the catalyst performance. As a result, as shown in the table, the reaction rate of isobutylene was 98.8%, the selectivity of methacrolein was 92.0%, and the selectivity of methacrylic acid was 3.6%.

<Example 5>
Except for using bismuth trioxide having a sodium content of 18 ppm, an oxide catalyst was produced in the same manner as in Example 4, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of isobutylene was 98.5%, the selectivity of methacrolein was 91.5%, and the selectivity of methacrylic acid was 3.5%.

<Example 6>
As in Example 4, except that bismuth trioxide having a sodium content of 18 ppm was used, and the clouded liquid A after addition of bismuth trioxide was subjected to ultrasonic treatment at 60 ° C. for 1 hour. Thus, an oxide catalyst was produced and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of isobutylene was 98.8%, the selectivity of methacrolein was 91.8%, and the selectivity of methacrylic acid was 3.6%.

<Example 7>
Instead of adding bismuth trioxide to liquid A, it is added to liquid C, which is a mixture of liquid A and liquid B in the same manner as antimony trioxide. An oxide catalyst was produced in the same manner as in Example 4 except that the time was maintained, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of isobutylene was 98.6%, the selectivity of methacrolein was 91.6%, and the selectivity of methacrylic acid was 3.6%.

<Comparative Example 3>
An oxide catalyst was produced in the same manner as in Example 4 except that a bismuth trioxide having a sodium content of 50 ppm was used, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of isobutylene was 98.0%, the selectivity of methacrolein was 89.1%, and the selectivity of methacrylic acid was 3.4%.

<Comparative example 4>
Same as Example 4 except that bismuth trioxide having a sodium content of 50 ppm was used and sonication was performed for 1 hour at 60 ° C. on the liquid A which was a white suspension after addition of bismuth trioxide. Thus, an oxide catalyst was produced, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of isobutylene was 98.5%, the selectivity of methacrolein was 91.0%, and the selectivity of methacrylic acid was 3.2%.

<Example 8>
An oxide catalyst was produced in the same manner as in Example 4 except that the raw material for gas phase catalytic oxidation was changed from isobutylene to TBA, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of TBA was 100%, the selectivity of methacrolein was 90.5%, and the selectivity of methacrylic acid was 3.3%.

<Comparative Example 5>
An oxide catalyst was produced in the same manner as in Comparative Example 3 except that the raw material for gas phase catalytic oxidation was changed from isobutylene to TBA, and the catalyst performance was evaluated. As a result, as shown in the table, the reaction rate of TBA was 100%, the selectivity of methacrolein was 88.1%, and the selectivity of methacrylic acid was 3.0%.

From the above results, each of the oxide catalysts of each Example in which bismuth trioxide having a sodium content of 40 ppm or less in terms of mass was excellent in catalytic activity and selectivity.
On the other hand, the oxide catalysts of Comparative Examples 1, 3, and 5 in which bismuth trioxide having a sodium content exceeding 40 ppm was used had particularly poor selectivity. Therefore, in order to improve the catalyst performance, ultrasonic treatment was performed at 60 ° C. for 1 hour on the liquid A which was a white suspension after addition of bismuth trioxide (Comparative Examples 2 and 4). The performance improvement was slight, and the results were not as good as the oxide catalysts of the examples.

Claims (1)

When producing unsaturated aldehydes and / or unsaturated carboxylic acids by vapor-phase catalytic oxidation of at least one selected from the group consisting of propylene, isobutylene, tertiary butyl alcohol, and methyl tertiary butyl ether with molecular oxygen A method for producing an oxide catalyst having a composition represented by the following formula (1) used in:
Having a step of preparing a raw material liquid containing a molybdenum raw material containing molybdenum, a bismuth raw material containing bismuth, and an iron raw material containing iron;
The said bismuth raw material is a bismuth trioxide whose sodium content is 40 ppm or less in mass conversion, The manufacturing method of the oxide catalyst characterized by the above-mentioned.
_{Mo a Bi b Fe c M d} X e Y f Z g Si h O i ··· (1)
(In the formula (1), Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively, and M represents at least one element selected from the group consisting of cobalt and nickel. , X represents at least one element selected from the group consisting of chromium, lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc, and Y represents phosphorus, boron, sulfur, selenium, tellurium Represents at least one element selected from the group consisting of cerium, tungsten, antimony and titanium, and Z represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium A, b, c, d, e, f, g, h and i represent the atomic ratio of each element, and when a = 12. b = 0.01 to 3, c = 0.01 to 5, d = 1 to 12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, h = 0 to 20, i is the oxygen atom ratio necessary to satisfy the valence of each component.