JP5794862B2 - Oxides containing molybdenum, bismuth, iron and cobalt - Google Patents

Description

  The present invention relates to an oxide containing molybdenum, bismuth, iron and cobalt, a method for producing the same, and uses of the oxide.

  It is known that transition metals such as molybdenum, bismuth, and iron become so-called complex oxides in which a plurality of types of metals are in a solid solution in addition to oxides obtained by oxidizing each of them. Composite oxides have different characteristics from single metal oxides, and the characteristics change greatly depending on the selection of metal species, composition ratio, etc., so pigments, battery electrode materials, catalysts, etc. Studies are underway in various fields.

  For example, a metal oxide containing molybdenum, bismuth, and iron exhibits catalytic activity in a reaction of oxidizing an olefin or alcohol to produce an unsaturated aldehyde or diolefin. For this reason, it has been reported so far that metal oxides containing molybdenum, bismuth and iron are used as a catalyst for producing an unsaturated aldehyde as a main component. Many composite oxide catalysts containing molybdenum, bismuth and iron as essential components and obtained by heat treatment with addition of organic compounds have been reported.

  As described above, since the characteristics of the oxides are different when the composition ratio is different, the catalyst characteristics of the composite oxides with various composition ratios can be improved for the purpose of improving the catalytic activity and the production rate of the target compound. Preparation conditions are being studied. For example, Patent Document 1 describes a production method in which a catalyst precursor containing molybdenum, bismuth and iron is calcined in an atmosphere of a molecular oxygen-containing gas and then heat-treated in the presence of a reducing substance.

As the composition of the composite oxide is studied, it has been found that there is a certain limit to the composition with which the metal can be combined. For example, Non-Patent Document 1 describes characterization using an XRD diffraction method for a phenomenon in which iron is dissolved in a complex oxide of cobalt and molybdenum (CoMoO ₄ ). In addition, in a catalyst (composition formula: Mo ₁₂ Bi ₁ Co _11-X Fe _x ) calcined in an air atmosphere, the interplanar spacing d value of CoMoO ₄ is small until the atomic ratio X of iron is iron. Is dissolved in CoMoO ₄ , but in the iron atomic ratio X = 4 or more, the d value does not change, and it is described in Non-Patent Document 1 that iron does not dissolve in CoMoO ₄ . Further, the solid solution of iron in CoMoO ₄ is due to the expression of catalytic activity. Specifically, the solid solution of Fe ³⁺ in CoMoO ₄ , that is, substitution of Co ²⁺ with Fe ³⁺ causes an oxygen defect (Φ) due to the principle of charge neutrality. It is considered that the migration is the mechanism of expression of activity.

JP 2007-117866 A

Catalyst vol. 28, no. 6, 1986

Patent Document 1 describes 0 <c ≦ 10 as the Fe composition ratio c. However, in practice, even if the Fe composition ratio c is 4 or more, it is possible to form a solid solution in CoMoO ₄ simply by forming a single oxide of iron or a binary composite oxide of trivalent iron and molybdenum. Does not increase the amount of iron.

In the bismolybdenum (Bi-Mo) catalyst used in this field, iron is an essential component, and it is said that it has the effect of increasing the reoxidation rate and improving the activity by the coexistence of iron. As a result, the catalyst containing a large amount of iron accelerates the reaction even under a low oxygen partial pressure, so that the target product can be obtained in a high yield without by-producting oxygen addition compounds other than aldehyde (for example, carbon dioxide). be able to. Further, when a catalyst containing a large amount of iron is used, redox during the reaction is facilitated, so that the effect of extending the life of the catalyst is also expected. Therefore, it is desirable that a large amount of iron is contained in the oxide serving as a catalyst. However, as described above, the amount of iron dissolved in CoMoO ₄ is limited, and the composition ratio cannot be set freely. In other words, although there is a concept of composition ratio to prevent by-products such as carbon dioxide in catalysts containing molybdenum, bismuth, iron and cobalt, the composition ratio design is not free and the concept has been realized. Not in.

  According to the study by the present inventors, when a composite oxide of trivalent iron and molybdenum is formed in an oxide containing molybdenum, bismuth, iron and cobalt, or when an iron compound such as iron oxide is formed, It has been found that when the oxide is used as a catalyst for the production reaction of an unsaturated aldehyde, the combustion reaction is accelerated and the yield of the target product is not improved. The present inventors presume this reason as follows. The cause of the undesired combustion reaction described above is that iron forms a complex oxide or a single oxide in a trivalent state. That is, not only the metal composition but also the valence of each metal affects the function of the composite oxide. Iron compounds and the like do not all exhibit a negative effect as described above, but rather can exhibit a preferable catalytic action if iron is in a divalent state. Therefore, a catalyst including an oxide with a controlled redox degree can further improve various functions.

  As a result of intensive investigations on means for achieving control of the oxidation-reduction degree of the oxide, the present inventors have found use of an oxidizing agent, a reducing agent and reduction firing, so that the iron is in a divalent state. By making it possible to form a composite oxide, a composite oxide composition that could not be obtained by conventional oxidation firing was realized. And when this novel oxide is used as a catalyst for the production of unsaturated aldehyde and butadiene, it has also been found that the production of carbon dioxide is suppressed and the yield of the target product is improved under a low oxygen partial pressure, The present invention has been conceived.

  That is, the present invention is as follows.

[1]
Contains molybdenum, bismuth, iron and cobalt,
An oxide having a ratio of Fe ²⁺ / (Fe ²⁺ + Fe ³⁺ ) of 0.7 or more and less than 1.0.

[2]
The oxide according to [1], wherein the atomic ratio b of iron is 5 ≦ b ≦ 11 with respect to 12 atoms of molybdenum.

[3]
The oxidation according to [1] or [2], wherein the ratio (b / c) of the atomic ratio b of iron to the atomic ratio c of cobalt is 0.5 ≦ b / c ≦ 11 with respect to 12 atoms of molybdenum. object.

[4]
The oxide in any one of [1]-[3] whose atomic ratio a of bismuth is 0.5 <= a <= 5 with respect to 12 atoms of molybdenum.

[5]
The oxide contains a composite oxide of cobalt and molybdenum;
In the X-ray diffraction of the oxide, at least the (002) plane X-ray diffraction angle (2θ) of the complex oxide of cobalt and molybdenum shows a peak (maximum intensity) at 26.15 ° to 26.35 °. The oxide according to any one of [1] to [4].

[6]
The oxide according to any one of [1] to [5], having a composition represented by the following composition formula (1).

(In the formula (1), Mo represents molybdenum, Bi represents bismuth, Fe represents iron, Co represents cobalt, A represents at least one alkali element selected from the group consisting of cesium, rubidium and potassium, and a to e are The atomic ratio of each element to Mo12 atoms is shown, 0.5 ≦ a ≦ 5, 5 ≦ b ≦ 11, 0.5 ≦ b / c ≦ 11, 0.01 ≦ d ≦ 2, and e is other than oxygen (The atomic ratio of oxygen is determined by the valence of the constituent elements.)
[7]
The catalyst containing the oxide in any one of [1]-[6].

[8]
Mixing a raw material for forming an oxide containing molybdenum, bismuth, iron and cobalt to obtain a mixture;
Drying the obtained mixture to obtain a dried product;
A step of pre-baking the obtained dry body to obtain a pre-fired body,
Including a step of subjecting the obtained temporarily fired body to main firing to obtain an oxide,
In the oxide, the atomic ratio a of bismuth to 12 atoms of molybdenum is 0.5 ≦ a ≦ 5, the atomic ratio b of iron is 5 ≦ b ≦ 11, and the ratio of the atomic ratio b of iron to the atomic ratio c of cobalt ( b / c) is adjusted so that the mixing ratio of each raw material is 0.5 ≦ b / c ≦ 11,
The pre-baking is performed in the presence of an oxidizing agent and a reducing agent;
The preliminary baking and the main baking are performed in an inert gas atmosphere,
The method for producing an oxide, wherein the main baking is performed at a temperature higher than the temperature of the preliminary baking.

[9]
The manufacturing method of unsaturated aldehyde using the catalyst as described in [7].

[10]
The manufacturing method of a butadiene using the catalyst as described in [7].

[11]
A method for producing an unsaturated aldehyde, comprising a step of oxidizing at least one selected from the group consisting of propylene, isobutylene and t-butyl alcohol using the catalyst according to [7].

[12]
A process for producing butadiene, comprising a step of oxidizing n-butene using the catalyst according to [7].

According to the present invention, in the oxide containing molybdenum, bismuth, iron and cobalt, the ratio of trivalent iron (Fe ³⁺ ) is reduced, and the ratio of divalent iron (Fe ²⁺ ) is within an appropriate range. A controlled oxide can be provided. This oxide suppresses the production of carbon dioxide under low oxygen partial pressure in the production of unsaturated aldehydes and / or butadienes from olefins and / or alcohols, and produces high yields of unsaturated aldehydes and / or butadienes. Therefore, it is useful as a catalyst.

6 is a graph showing X-ray diffraction peaks of oxides obtained in Example 4, Example 7, Comparative Example 2, and Comparative Example 6. FIG. It is a figure which shows the enlarged view of 2 (theta) = 25-27 degree of the X-ray-diffraction peak in FIG. 6 is a graph showing a Mossbauer spectrum of the oxide obtained in Example 4. FIG. It is a figure which shows the Mossbauer spectrum of the oxide obtained by the comparative example 6. It is a figure which shows the structure and specification of an iron valence measuring device.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified within the scope of the gist.

[1] Oxide The oxide of this embodiment contains molybdenum, bismuth, iron, and cobalt, and the ratio of Fe ²⁺ / (Fe ²⁺ + Fe ³⁺ ) is 0.7 or more and less than 1.0.

  In the oxide of this embodiment, the iron atomic ratio b is preferably 5 ≦ b ≦ 11 with respect to 12 atoms of molybdenum, and the atomic ratio b of iron and cobalt atoms with respect to 12 atoms of molybdenum. The ratio (b / c) to the ratio c is preferably 0.5 ≦ b / c ≦ 11, and the atomic ratio a of bismuth to 12 atoms of molybdenum is 0.5 ≦ a ≦ 5. preferable.

(1) Composition The oxide of this embodiment includes molybdenum (hereinafter also referred to as “Mo”), bismuth (hereinafter also referred to as “Bi”), iron (hereinafter also referred to as “Fe”), and cobalt (hereinafter referred to as “Co”). Is also written.).

In general, it is indispensable to contain Mo, Bi, Fe, and Co from the viewpoint of making each metal element complex in a Mo-Bi-based metal oxide. In the oxide of the present embodiment, it is preferable that the atomic ratio a of Bi to Mo12 atoms is 0.5 ≦ a ≦ 5. From the viewpoint of further increasing the selectivity of the target product, the atomic ratio a of Bi is more preferably 1 ≦ a ≦ 5, and further preferably 2 ≦ a ≦ 4. Bi and Mo preferably form Bi—Mo—O complex oxides such as Bi ₂ Mo ₃ O ₁₂ and Bi ₂ MoO ₆ that are active species such as gas phase catalytic oxidation and ammoxidation reaction. As will be described later, in this embodiment, in the production of an oxide, the oxidation-reduction degree of the oxide is precisely controlled in an inert gas atmosphere during firing. Mo and Bi are preferably formed to form a Bi—Mo—O composite oxide, and are preferably controlled so as not to be overreduced. When Mo or Bi is overreduced, Mo forms MoO ₂ , metal Mo, and metal Bi, and does not form a Bi—Mo—O composite oxide, so the yield of the target product is reduced.

In the oxide of the present embodiment, Fe is an essential element for industrially synthesizing the target product, similarly to Mo and Bi, from the viewpoint of increasing the catalytic activity without reducing the selectivity of the target product. In the oxide of this embodiment, the Fe content is preferably controlled within a specific range. In the production of oxides, when firing in an oxidizing atmosphere containing oxygen, if the Fe content increases, Fe ₂ O ₃ is generated, and a by-product such as CO and CO ₂ tends to increase. When such an oxide is used as a catalyst, the selectivity of the target product is lowered. Accordingly, as described in International Publication No. 95/35273 pamphlet, conventionally, when an oxide containing Mo, Bi, Fe, Co is used as a catalyst, in order to obtain a target product with a high yield, the oxidation is performed. In the product, the atomic ratio of Fe to Mo12 atoms needs to be 0 <Fe ≦ 2.5. In this regard, the present inventors controlled the oxidation-reduction degree of the oxide in an inert gas atmosphere with the aim of suppressing by-products such as Fe ₂ O ₃ in the production of the oxide, A method for controlling the valence to be divalent was found. By this control, the inventors succeeded in creating an oxide having a composition range in which the Fe ratio is larger than that of the conventional one. And when this oxide was used as a catalyst, it discovered that the yield of the target product could be raised further. It is clear that divalent iron is dissolved in CoMoO ₄ even when the atomic ratio of iron to 12 atoms of molybdenum is 4 or more, and a ternary crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O is formed. became. By controlling the oxidation-reduction degree of the oxide, substitutional solid solution of iron in CoMoO ₄ can be made regardless of the composition, and in the oxide, the composition ratio can be freely set and Co ²⁺ -Fe ^{2 +} —Mo—O ternary crystals can be generated. That is, as a result of intensive studies by the present inventors to make the oxidizing power of the oxide appropriate, the formation of a divalent iron compound in the oxide is promoted, and the ratio of Mo, Bi, Fe, and Co is appropriately set. In addition, by suppressing the formation of the trivalent iron compound, it was possible to create a new oxide in which Fe was dissolved in CoMoO ₄ even when the Fe ratio was large.

  In the oxide of this embodiment, the atomic ratio b of Fe to Mo12 atoms is preferably 5 ≦ b ≦ 11, more preferably 5 ≦ b ≦ 10, and further preferably 5 ≦ b ≦ 9.

In the oxide of this embodiment, Co is an essential element for industrially synthesizing a target product, like Mo, Bi, and Fe. In the oxide of this embodiment, Co forms a composite oxide CoMoO ₄ , and the CoMoO ₄ serves as a carrier for highly dispersing active species such as Bi—Mo—O, and oxygen from the gas phase. It is presumed that it plays a role of taking in and supplying to Bi-Mo-O and the like. When an oxide containing Mo, Bi, Fe and Co is used as a catalyst for producing an unsaturated aldehyde, in order to obtain an unsaturated aldehyde in a high yield, in the oxide, Co is compounded with Mo and combined oxidation. The product CoMoO ₄ is preferably formed. In the unsaturated aldehyde production, if a single oxide such as Co ₃ O ₄ or CoO is present, a side reaction occurs. Therefore, the formation of a single oxide such as Co ₃ O ₄ or CoO may be reduced in the oxide. preferable. From the viewpoint of suppressing the formation of a single oxide and improving the activity of the catalyst, the ratio (b / c) of the Fe atomic ratio b to the atomic ratio c of Co is preferably 0.5 ≦ b / c ≦ 11, More preferably, 0.5 ≦ b / c ≦ 5, and further preferably 0.7 ≦ b / c ≦ 3.

  The oxide of the present embodiment preferably has a composition represented by the following composition formula (1).

(In the formula (1), Mo represents molybdenum, Bi represents bismuth, Fe represents iron, Co represents cobalt, A represents at least one alkali element selected from the group consisting of cesium, rubidium and potassium, and a to e are The atomic ratio of each element to the Mo12 atom is shown, and 0.5 ≦ a ≦ 5, 5 ≦ b ≦ 11, 1 ≦ c ≦ 12, 0.7 ≦ b / c ≦ 11, 0.01 ≦ d ≦ 2. E is the atomic ratio of oxygen determined by the valence of the constituent elements other than oxygen.)
A represents at least one alkali element selected from the group consisting of cesium, rubidium and potassium, and is considered to have a role of neutralizing acid sites such as MoO ₃ which have not been complexed in the oxide. Whether or not cesium and / or rubidium are contained does not affect the crystal structure of Fe—Co—Mo—O described later. In the composition represented by the composition formula (1), the atomic ratio d of these alkali elements to Mo12 atoms is 0.01 ≦ d ≦ 2 from the viewpoint of catalytic activity. By adjusting the atomic ratio d of the alkali element to the above numerical range, the oxide having the composition represented by the composition formula (1) tends to exhibit sufficient catalytic activity. When the atomic ratio d of the alkali element exceeds the above range, the oxide becomes basic. For example, when the oxide is used as a catalyst for the oxidation reaction of olefin or alcohol, the raw material olefin or alcohol is hardly adsorbed on the catalyst. , There is a tendency that sufficient catalytic activity cannot be expressed.

  In the present embodiment, the atomic ratio of each element in the oxide can be measured by the method described in the examples described later.

(2) Crystal structure When an oxide containing molybdenum, bismuth, iron and cobalt is measured by X-ray diffraction (XRD) in an X-ray diffraction angle range of 2θ = 5 ° to 60 °, it is a composite oxide composed of cobalt and molybdenum. The peak due to the object is shown at 26.40 °. When iron is dissolved in this composite oxide composed of cobalt and molybdenum and combined, this peak shift occurs due to the difference in ionic radius between Co ²⁺ and Fe ²⁺ . Since iron is a solid solution and a complex structure, the peak attributed to the complex oxide composed of cobalt and molybdenum is not 26.40 ° but 26.40 ° -α ° (0 <α). It is.

Although the detailed mechanism by which the peak due to the complex oxide of cobalt and molybdenum shifts is not clear, the present inventors presume as follows. When the oxide is produced, if it is fired in an air atmosphere containing oxygen, trivalent Fe further dissolves in the composite oxide of Co and Mo. Accordingly, it is presumed that the peak due to the complex oxide composed of cobalt and molybdenum is slightly shifted as described above. This peak shift ratio (α °) is considered to be 0 ≦ α <0.05. In a composition having an Fe atomic ratio b to Mo atom 12 of more than ₃ , to form a binary oxide of iron and molybdenum, such as Fe ₂ Mo ₃ O ₁₂ , 3 to a composite oxide of Co and Mo is formed. It is considered that no solid solution of valent iron occurs and the peak shift ratio (α °) does not become 0.05 or more.

On the other hand, when the valence of iron is divalent, a peak shift occurs even in a composition having an Fe atomic ratio b to Mo atom 12 of more than 3, and the peak shift ratio (α °) is 0.05 ≦ α ≦ 0. 25. This is because a new crystal structure of a composite ternary system of Co ²⁺ -Fe ²⁺ -Mo-O is newly obtained by further dissolving divalent Fe in a composite oxide of Co and Mo. It is thought that it was formed. The ternary crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O is formed because the ionic radius of iron becomes close to the ionic radius of divalent cobalt when iron becomes divalent. It is presumed that the substitution solid solution becomes possible. The ionic radius of divalent cobalt is 0.72Å, the ionic radius of trivalent iron is 0.64Å, and the ionic radius of divalent iron is 0.74Å. To form a crystal structure of three-component system of Co ²⁺ -Fe ²⁺ -Mo-O, the presence ratio of the metal is also important. For example, when the atomic ratio b of Fe to Mo12 atoms satisfies the range of 5 ≦ b ≦ 11, it tends to form a ternary crystal structure of Co ²⁺ —Fe ²⁺ —Mo—O, and the atomic ratio b Is less than the lower limit value, a Co ²⁺ -Fe ²⁺ -Mo-O ternary crystal structure is not formed or is very small even if formed, and the resulting oxide is CO _x (CO ₂ and CO) are difficult to suppress. That is, when the atomic ratio b of Fe is in the above range, oxides generated is suppressed in CO _x (CO ₂ and CO, etc.) is obtained, as a result, when using the oxide as a catalyst, not The yield of saturated aldehyde or butadiene is improved.

In order to promote formation of a ternary crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O in the above oxide from the viewpoint of increasing the yield of unsaturated aldehyde or butadiene, The proportion of iron is important. In the oxide of this embodiment, the ratio (atomic ratio) of divalent iron to divalent and trivalent iron, that is, the ratio of Fe ²⁺ / (Fe ²⁺ + Fe ³⁺ ) is 0.7 or more and 1. It is less than 0, preferably 0.8 or more and less than 1.0, and more preferably 0.9 or more and less than 1.0.

  The oxide of this embodiment contains a composite oxide of cobalt and molybdenum. In the X-ray diffraction of the oxide, at least the (002) plane X-ray diffraction angle of the composite oxide of cobalt and molybdenum. (2θ) preferably exhibits a peak (maximum intensity) at 26.15 ° to 26.35 °. The range of the X-ray diffraction angle 2θ in which the peak (maximum intensity) due to the complex oxide of cobalt and molybdenum in the oxide is shown is more preferably 26.15 ° to 26.30 °, and still more preferably 26. 20 ° to 26.30 °.

Note that, as an index for compositing the ternary crystal structure Co ²⁺ —Fe ²⁺ —Mo—O, a peak shift from an X-ray diffraction angle 2θ = 26.40 ° is used as a reference. The index of the valence of Fe can be determined from the Mossbauer spectrum.

  The oxide of this embodiment can be obtained by, for example, a manufacturing method described later.

[2] Catalyst The catalyst of the present embodiment includes the above-described oxide. The catalyst containing the above-mentioned oxide can be suitably used as a catalyst for producing an unsaturated aldehyde or butadiene.

  The catalyst of this embodiment may contain a support for supporting the above-described oxide. A catalyst including a support is preferable in that the oxide can be highly dispersed and the supported oxide is provided with high wear resistance. On the other hand, when producing acrolein or methacrolein in a fixed bed reactor, when used as a tablet-molded catalyst, the catalyst of this embodiment may not contain a support. When the catalyst is molded by an extrusion molding method, it may be preferable that the catalyst of this embodiment includes a carrier component. Examples of the carrier include silica, alumina, titania, and zirconia. In general, silica is an inert carrier compared to other carriers, and is a preferred carrier in that it has a good binding action on the above-mentioned oxides without reducing the selectivity for the target product. Further, the silica support is preferable in that it easily imparts high wear resistance to the supported oxide. When the catalyst is molded by the extrusion molding method, the support may not be used and an organic binder may be used. However, when the above-mentioned support is used, the content of the support with respect to the whole catalyst is 5 to 10% by mass. It is preferable that

In the case of a catalyst used in a fluidized bed reactor, it is preferable to use silica as a support from the same viewpoint as described above. In view of the influence on the crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O and the improvement of fluidity by making the apparent specific gravity appropriate, the content of the support in the catalyst is based on the total mass of the catalyst. 80 mass% or less is preferable, More preferably, it is 70 mass% or less, More preferably, it is 60 mass% or less. In the case of a catalyst requiring strength, such as a fluidized bed reaction catalyst, the content of the carrier is 20% by mass or more with respect to the total mass of the catalyst from the viewpoint of practically sufficient anti-crushing and wear resistance. Preferably, 30 mass% or more is more preferable, and 40 mass% or more is further more preferable.

[3] Method for Producing Oxide The method for producing an oxide of the present embodiment includes a step of obtaining a mixture by mixing raw materials for forming an oxide containing molybdenum, bismuth, iron and cobalt,
Drying the obtained mixture to obtain a dried product;
A step of pre-baking the obtained dry body to obtain a pre-fired body,
Including a step of subjecting the obtained temporarily fired body to main firing to obtain an oxide,
In the oxide, the atomic ratio a of bismuth to 12 atoms of molybdenum is 0.5 ≦ a ≦ 5, the atomic ratio b of iron is 5 ≦ b ≦ 11, and the ratio of the atomic ratio b of iron to the atomic ratio c of cobalt ( b / c) is adjusted so that the mixing ratio of each raw material is 0.5 ≦ b / c ≦ 11,
The pre-baking is performed in the presence of an oxidizing agent and a reducing agent;
The preliminary baking and the main baking are performed in an inert gas atmosphere,
The main baking is performed at a temperature higher than the temperature of the preliminary baking.

As described above, the present inventors do not use Fe and Mo alone and / or binary oxides, but by diluting Fe into solid solutions in binary oxides of Co and Mo. Focusing on obtaining a Co ²⁺ -Fe ²⁺ -Mo-O-based composite oxide in which three components are complexed, the composition ratio and the preparation method were comprehensively studied.

As a result of repeated trial and error to solve this problem, the present inventors surprisingly controlled the valence of iron in the oxide after the main firing to be bivalent, and Mo and Bi were combined. It has been found that the oxides as described above can be obtained by controlling the redox degree so as to form the oxide Bi—Mo—O. For example, by using a new manufacturing technology that satisfies the three requirements of (a) a specific composition ratio, (b) a valence of a specific metal element, and (c) a specific firing method, the generation of simple oxides is suppressed for the first time. The present inventors have found that a catalyst in which crystals of Co ²⁺ -Fe ²⁺ -Mo-O in which three components are complexed is newly formed can be obtained. Simply increasing the Fe content does not cause compounding like the oxide of this embodiment. That is, by controlling the percentage of divalent iron in the oxide, the new crystal structure it was found that the resulting three components of Co ²⁺ -Fe ²⁺ -Mo-O is the first time compatible.

That is, for example, a two-component system of Co and Mo by a new manufacturing technique that satisfies three conditions of (a) a specific composition ratio, (b) a specific iron valence, and (c) a specific firing method. In this composite oxide, divalent Fe is dissolved, and an oxide in which a composite Co ²⁺ -Fe ²⁺ -Mo-O ternary crystal structure is formed can be obtained. The oxide can be used as a catalyst with a high yield of unsaturated aldehyde. In addition, by a new manufacturing technique that satisfies the above three conditions, a binary composite oxide such as Co—Mo—O or Fe—Mo—O, or a simple oxide such as Fe ₂ O ₃ , MoO ₃ , or CoO is used. The X-ray diffraction angle (2θ) of the (002) plane of the complex oxide of cobalt and molybdenum tends to show a peak at 26.15 ° to 26.35 °, and the oxide When Y is used as a catalyst, the yield of unsaturated aldehyde tends to be improved.

  The design concept of an oxide that controls the above-described ratio of divalent iron and controls the degree of oxidation-reduction so that Mo and Bi form Bi—Mo—O is a completely new finding that has not existed before. According to the present embodiment, it is possible to synthesize a novel structural oxide containing a large amount of iron, which is not found in conventional oxides. Oxides containing a large amount of iron, when used as a catalyst, increase the reoxidation rate, become highly active, and are advantageous in that the redox cycle of the catalyst during the reaction is advantageous, so that the reaction proceeds even under a low oxygen partial pressure. . For this reason, the by-product of an oxygen addition compound can be suppressed as much as possible.

  The oxide manufacturing method of this embodiment includes, for example, a first step of obtaining a mixture by mixing raw materials for forming an oxide containing molybdenum, bismuth, iron, and cobalt, and drying and drying the obtained mixture. A second step of obtaining a body, and a third step of firing the obtained dried body to obtain an oxide. Hereinafter, the preferable aspect of each process is demonstrated in detail.

(1) Preparation of raw materials In the first step, raw materials of respective metal elements constituting the oxide are mixed to obtain a mixture (for example, raw material slurry or mixed powder). In the oxide finally obtained, the atomic ratio a of bismuth to 12 atoms of molybdenum is 0.5 ≦ a ≦ 5, the atomic ratio b of iron is 5 ≦ b ≦ 11, the atomic ratio b of iron and cobalt The mixing ratio of each raw material is adjusted so that the ratio (b / c) to the atomic ratio c is 0.5 ≦ b / c ≦ 11.

  As each element source of molybdenum, bismuth, iron, cobalt, rubidium, cesium, potassium, ammonium salt, nitrate, hydrochloride, organic acid salt soluble in water or nitric acid can be mentioned, oxide and hydroxide Carbonate or the like may be used. In the case of an oxide, each raw material oxide powder may be mixed to form a raw material mixed powder without forming a slurry. In the case of an oxide, a dispersion liquid dispersed in water or an organic solvent is preferable, and an oxide dispersed in water is more preferable. In the case of being dispersed in water, a surfactant such as a polymer may be contained in order to suppress aggregation of the oxide and highly disperse it. The particle diameter of the oxide is preferably 1 to 500 nm, more preferably 10 to 80 nm. When producing a catalyst containing a carrier, it is preferable to add silica sol as a silica raw material to the raw slurry.

From the viewpoint of controlling the ratio of divalent iron in the oxide after the main firing and from the viewpoint of forming Bi—Mo—O by complexing molybdenum and bismuth, the raw material mixed powder or the raw material mixed slurry. Add an oxidizing agent and a reducing agent. As the oxidizing agent, a preferable oxidizing agent can be selected and used from nitric acid, hydrogen peroxide, and perchloric acids, and two or more oxidizing agents may be mixed and used. Examples of reducing agents include water-soluble polymers and amines such as polyethylene glycol, polyvinyl alcohol, polyacrylic acid, polycarboxylic acid, and polyacrylamide; polyvalent carboxylic acids such as aminocarboxylic acids, malonic acid, and succinic acid; glycolic acid, apples Examples thereof include organic acids such as acid, oxalic acid, tartaric acid, and citric acid, and ammonia water may be appropriately added thereto, or two or more reducing agents may be mixed and used. Although the addition amount of an oxidizing agent and a reducing agent is not specifically limited, It is preferable to add in 0-40 mass% with respect to a metal oxide from a viewpoint of the balance of a uniformity and a production amount. When the addition amount of the reducing agent is more than 40% by mass with respect to the metal oxide, Fe is divalently reduced, but Mo is easily overreduced to MoO ₂ or metal Mo and Bi is easily reduced to metal Bi.

  The method of preparing the raw slurry is not particularly limited as long as it is a commonly used method. It can be prepared by mixing a solution dissolved in an aqueous solution. The metal element concentration in the slurry after mixing is preferably 1 to 50% by mass, more preferably 10 to 40% by mass, and further preferably 20 to 40% from the viewpoint of the balance between uniformity and production amount. % By mass.

  When the ammonium salt and the nitrate are mixed, precipitation occurs to form a slurry. Therefore, homogenizer treatment and aging may be appropriately performed on the raw slurry. The purpose of homogenizer treatment and aging is to pulverize solids and promote the formation of oxide precursors to make finer and more uniform slurries. It is particularly preferable to perform a homogenizer treatment and aging because it tends to be a slurry having low properties. From the viewpoint of further pulverizing the solid content, the homogenizer rotation speed is usually 5000 to 30000 rpm, and it is generally preferable to carry out in the range of 5 minutes to 2 hours. When the slurry is aged, in order to obtain a target composite crystal, it is preferable to heat the slurry to a temperature higher than room temperature and keep the slurry medium in a liquid state. The aging time is not limited, but 1 to 24 hours is preferable.

When the raw material slurry is not homogeneous, the oxide composition after firing becomes heterogeneous, and it becomes difficult to form a homogeneous composite crystal structure. Therefore, it is a preferable aspect to try to optimize the slurry preparation process when the obtained oxide is not sufficiently compounded. In addition, the preparation process of the raw material slurry described above is an example and is not limited. The addition procedure of each element source is changed, or the pH of the slurry is adjusted by adjusting the concentration of nitric acid or adding aqueous ammonia to the slurry. It may be modified. To form more Co ²⁺ -Fe ²⁺ -Mo-O crystal structure is preferably a homogeneous slurry. From the viewpoint of obtaining a homogeneous slurry, the pH of the raw slurry is preferably 2.0 or less. The pH of the raw material slurry is more preferably 1.5 or less, and still more preferably 1.0 or less. When the pH of the raw material slurry exceeds 2.0, precipitation of a bismuth compound may occur.

(2) Drying In the second step, the mixture (eg, raw material slurry) obtained in the first step is dried to obtain a dried body (eg, dry particles). The drying method is not particularly limited and can be performed by a generally used method, and can be performed by any method such as an evaporation drying method, a spray drying method, or a reduced pressure drying method. The spray drying method can be performed by a method such as a centrifugal method, a two-fluid nozzle method, a high-pressure nozzle method, etc., which are usually carried out industrially, and air heated by steam, an electric heater or the like is used as a drying heat source. Is preferred. At this time, the temperature at the inlet of the dryer of the spray dryer is preferably 150 to 400 ° C, more preferably 180 to 400 ° C, and further preferably 200 to 350 ° C.

(3) Firing In the third step, the dried body obtained in the second step is fired. Since calcination includes both an oxidizing agent and a reducing agent in the dried product, it is preferable to carry out the catalyst in a small amount as much as possible in order to suppress heat generation, so that the oxidation / reduction control can be performed with high accuracy. preferable. Oxidation / reduction can be controlled not with an inert gas such as nitrogen but with oxygen or air diluted with nitrogen. However, if oxygen is included during the heat treatment, heat is generated when the reducing agent decomposes, which is very dangerous, and requires precise control of the firing time for reduction, which is difficult. In the oxide manufacturing method of this embodiment, the firing is performed in an inert gas atmosphere. Examples of the inert gas include helium, argon, and nitrogen. Nitrogen is preferable from the economical viewpoint.

  Firing can be performed using a firing furnace such as a rotary furnace, a tunnel furnace, or a muffle furnace.

  The dried body is fired by two-stage firing of temporary firing and main firing. That is, a step of pre-baking the obtained dried body to obtain a pre-fired body and a step of subjecting the obtained pre-fired body to main firing to obtain an oxide are performed.

The first stage pre-baking is preferably pre-baking in a temperature range of 120 to 350 ° C, more preferably 150 to 350 ° C, and further preferably 200 to 350 ° C. The purpose of the preliminary calcination is to remove nitric acid remaining in the dried body, and to gently burn ammonium nitrate and the oxidizing agent and reducing agent derived from the raw material that is an ammonium salt and the raw material that is a nitrate. Therefore, in the first stage pre-baking, the dried body may be heated to such an extent that this purpose can be achieved. The pre-baking time is preferably 0.1 to 72 hours, more preferably 1 to 48 hours, and even more preferably 3 to 24 hours. In the case of a low temperature of 150 ° C. or lower, it is preferable to carry out temporary baking for a long time, and in the case of a high temperature of 330 ° C. or higher, it is preferable to perform a short temporary baking for 2 hours or less. Too temperature of calcination is high, the time is too long, 2 result component only oxides becomes easy to grow a cobalt and molybdenum in calcination stage, Co ²⁺ in the firing described below The crystal structure of —Fe ²⁺ —Mo—O becomes difficult to generate. Therefore, it is preferable that the upper limit of the calcination temperature and time is set to such an extent that the generation of the binary oxide of cobalt and molybdenum does not occur.

  In the preliminary firing step, an oxidizing agent and a reducing agent are present in the firing environment. In the raw material preparation process described above, when the raw material mixed slurry or mixed powder contains an oxidizing agent and a reducing agent, the raw material slurry is temporarily fired after drying, and the mixed powder is subjected to temporary baking as it is. These are also present in the firing step.

  When the oxidizing agent and / or reducing agent is not added to the raw material, the raw material mixed slurry may be dried, pre-fired by adding the oxidizing agent and / or reducing agent to the slurry, stirring and mixing, After drying, an oxidizing agent and / or a reducing agent may be added and mixed using a mixing apparatus such as a powder blender, a powder mixer, a jet mill, or a ball mill, and then calcined. As for the mixed powder, an oxidizing agent and / or a reducing agent may be added to the mixed powder, mixed using a mixing apparatus such as a powder blender, a powder mixer, a jet mill, or a ball mill, and temporarily fired. If it does in this way, it will be in the state in which an oxidizing agent and / or a reducing agent exist also in a temporary baking process.

  At the time of pre-baking, it is desirable that the rate of temperature increase is slow from the viewpoint of suppressing a rapid combustion reaction. In the manufacturing method of this embodiment, since the obtained oxidizing agent is a multi-component system, when the raw material is, for example, metal nitrate, the decomposition temperature of each metal nitrate is different, and nitric acid moves during firing, The oxide composition tends to be inhomogeneous. In particular, when there are many reducing agents, a sudden heat generation may occur. For this reason, in the production of oxides, in order to form a more homogeneous composite structure, the temperature is raised slowly, combustion and decomposition components such as nitric acid and organic substances are removed, and iron is trivalent to divalent. It is preferable to reduce to The rate of temperature rise is preferably 0.01 ° C / min to 100 ° C / min, more preferably 0.01 ° C / min to 75 ° C / min, and still more preferably 0.01 ° C / min to 50 ° C / min. .

After the pre-baking, second-stage main baking is performed. The purpose is to facilitate the formation of the desired crystal structure. According to the knowledge of the present inventors, since the crystal structure is affected by the product of the firing temperature and the firing time, it is preferable to appropriately set the firing temperature and the firing time. The temperature for the main firing is higher than the temperature for the preliminary firing from the viewpoint of generating Co ²⁺ -Fe ²⁺ -Mo-O crystals. The upper limit of the main baking temperature is preferably set to a temperature of 700 ° C. or lower. The firing temperature of the main firing is preferably 400 to 700 ° C., more preferably 400 to 650 ° C., and further preferably 450 to 600 ° C., from the viewpoint of easy formation of a Co—Fe—Mo—O crystal structure. It is. When firing at such a temperature, the firing time is preferably 0 from the viewpoint of promoting the formation of Co ²⁺ -Fe ²⁺ -Mo-O crystals by appropriately setting the product of the firing temperature and the firing time. .1 to 72 hours, more preferably 2 to 48 hours, and further preferably 3 to 24 hours. In view of making the firing temperature and firing time appropriate for the generation of the crystal structure, it is preferable to carry out the main firing for a long time of about 24 to 72 hours, for example, at a low temperature of 400 ° C. or lower, and a high temperature of 600 ° C. or higher. In this case, from the viewpoint of preventing the surface area of the resulting oxide from becoming too small and reducing the catalytic activity, it is preferable to perform the main firing for a short time of 1 hour or less.

  By performing all of the above steps, a complex Co—Fe—Mo—O ternary crystal structure is easily formed.

It can be confirmed by performing an X-ray structural analysis of the oxide obtained after the main firing that the three-component crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O is generated in the main calcination step. When the X-ray structural analysis of the oxide is performed after the main calcination, if a ternary crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O is generated, as described above, 26.40 °- A peak is observed at α °. When an oxide crystal composed of cobalt and molybdenum is formed, a peak appears at 26.40 °. However, in the case of a ternary system of Co ²⁺ -Fe ²⁺ -Mo-O, this peak shifts. Using this shift as an index, the formation of ternary crystals can be confirmed.

The magnitude of this shift (α °) is examined, and the X-ray diffraction angle of a complex oxide of cobalt and molybdenum having a peak at 26.40 ° is examined. In this embodiment, if the X-ray diffraction angle (2θ) of the (002) plane of the complex oxide of cobalt and molybdenum shows a peak at 26.15 ° to 26.35 °, Co ²⁺ -Fe ^It is determined that a 2 ⁺ -Mo-O ternary crystal structure was formed. The valence of iron is calculated from the Mossbauer spectrum.

[4] Method for Producing Unsaturated Aldehyde or Butadiene The method for producing an unsaturated aldehyde of this embodiment uses the above-described catalyst. Moreover, the above-mentioned catalyst is used for the manufacturing method of the butadiene of this embodiment.

  Moreover, the manufacturing method of the unsaturated aldehyde of this embodiment includes the process of making at least 1 sort (s) chosen from the group which consists of a propylene, isobutylene, and t-butyl alcohol using the above-mentioned catalyst, for example. The method for producing butadiene of this embodiment includes, for example, a step of oxidizing n-butene using the above-described catalyst. Hereinafter, the specific example is demonstrated, However, The manufacturing method of the unsaturated aldehyde of this embodiment or the manufacturing method of the butadiene of this embodiment is not limited to the following specific examples.

(1) Method for producing methacrolein Methacrolein can be obtained, for example, by performing a gas phase catalytic oxidation reaction of isobutylene and t-butyl alcohol using the catalyst of the present embodiment. In the gas phase catalytic oxidation reaction, for example, in the presence of the above-mentioned catalyst, the molecular oxygen concentration is 1 to 20% by volume with respect to 1 to 10% by volume of isobutylene, t-butyl alcohol, or a mixed gas of both. A raw material gas composed of a mixed gas obtained by adding a molecular oxygen-containing gas and a diluent gas is applied to a catalyst layer in a fixed bed reactor at a space velocity of 400 to a temperature range of 250 to 450 ° C. and a pressure of normal pressure to 5 atm. It can carry out by introduce | transducing at -4000 / hr [normal temperature pressure (NTP) conditions]. From the viewpoint of controlling the outlet oxygen concentration of the reactor in order to improve the yield of unsaturated aldehyde, the molar ratio of oxygen and the mixed gas of isobutylene, t-butyl alcohol or both is preferably 1.0 to 2. 0.0, more preferably 1.1 to 1.8, still more preferably 1.2 to 1.8.

Examples of the molecular oxygen-containing gas include pure oxygen gas, and gas containing oxygen such as N ₂ O and air, and air is preferable from an industrial viewpoint. As dilution gas, nitrogen, a carbon dioxide, water vapor | steam, and these mixed gas are mentioned, for example. Regarding the mixing ratio of the molecular oxygen-containing gas and the dilution gas in the mixed gas, the volume ratio should satisfy the condition of 0.01 <molecular oxygen / (molecular oxygen-containing gas + dilution gas) <0.3. Is preferred. Furthermore, the concentration of molecular oxygen in the source gas is preferably 1 to 20% by volume.

  Although water vapor in the raw material gas may be included in terms of preventing coking to the catalyst, the water vapor concentration in the dilution gas should be reduced as much as possible in order to suppress by-production of carboxylic acids such as methacrylic acid and acetic acid. Is preferred. The water vapor in the raw material gas is usually used in the range of 0 to 30% by volume.

(2) Method for producing acrolein A method for producing acrolein includes, for example, a step of vapor-phase catalytic oxidation of propylene using the catalyst described above.

Conditions for producing acrolein by vapor-phase catalytic oxidation of propylene are not particularly limited, and can be performed by a method generally used for producing acrolein by vapor-phase catalytic oxidation of propylene. For example, a mixed gas composed of 1 to 15% by volume of propylene, 3 to 30% by volume of molecular oxygen, 0 to 60% by volume of water vapor, 20 to 80% by volume of inert gas such as nitrogen and carbon dioxide, etc. What is necessary is just to introduce | transduce into a catalyst layer under the space velocity (SV) 300-5000hr < ^-1 > under the pressurization of 250-450 degreeC and 0.1-1 MPa. As the reactor, a general fixed bed reactor, fluidized bed reactor or moving bed reactor is used.

(3) Method for Producing Butadiene For example, butadiene can be obtained by performing a gas phase catalytic oxidation reaction of n-butene using the above-mentioned catalyst. In the gas phase catalytic oxidation reaction, a molecular oxygen-containing gas and a dilution gas are mixed so that the molecular oxygen concentration is 1 to 20% by volume with respect to 1 to 10% by volume of n-butene in the presence of an oxide catalyst. A raw material gas comprising a mixed gas is added to a catalyst layer in a fixed bed reactor under a temperature range of 250 to 450 ° C. and a pressure of normal pressure to 5 atmospheres, and a space velocity of 400 to 4000 / hr [Normal temperature pressure (NTP). ) Under the conditions].

  Hereinafter, the present embodiment will be described in more detail with reference to examples. However, the present embodiment is not limited to the examples described below.

  The atomic ratio of oxygen atoms in the oxide catalyst is determined by the valence conditions of other elements. In the examples and comparative examples, the atomic ratio of oxygen atoms in the formulas representing the composition of the catalyst is Omitted. Further, the composition ratio of each element in the oxide catalyst was calculated from the composition ratio of preparation.

<Measurement of powder X-ray diffraction (XRD)>
XRD is measured by measuring the (111) plane and the (200) plane of the LaB ₆ compound as defined by the National Institute of Standards & Technology as the standard reference material 660, and the measured values are 37.441 °, 43.43 °, respectively. It normalized so that it might become 506 degrees.

  Bruker D8 ADVANCE was used as the XRD measuring device. The XRD measurement conditions are: X-ray output: 40 kV-40 mA, divergent slit (DS): 0.3 °, Step width: 0.01 ° / step, counting time: 2.0 sec, measurement range: 2θ = 5 ° to The angle was 45 °.

<Measurement of iron valence>
Information on the valence of iron was obtained from Mossbauer spectroscopy (transmission method). The measurement conditions are shown below.
-Measurement conditions of iron valence (1) Preparation of measurement sample: About 55 to 60 mg of a sample was measured as it was.
(2) Device configuration and specifications: As shown in FIG.
(3) Transition used for observation: Transition between ground state and lowest excited state of ⁵⁷ Fe
(Energy: 14.4 [keV])
(4) Measurement method: uniform acceleration mode, room temperature, normal pressure (5) Storage device: card type multi-channel analyzer
MCS mode 512 channel (6) radiation source: ⁵⁷ Co / Rh matrix, 1.85 [GBq]
(7) Velocity axis calibration method: Out of six magnetic splitting peaks of pure iron foil at room temperature, the inner four peak center positions are x ₂ , x ₃ , x ₄ , x ₅ [channel]. As follows.
x0 [channel] = (x ₂ + x ₃ + x ₄ + x ₅ ) / 4
r [mm / s / (channel)] = 20.422 / {3.0835 (x ₅ -x ₂ ) +0.8385 (x ₄ -x ₃ )}

In Examples and Comparative Examples, the conversion rate, selectivity, and yield used to represent reaction results are defined by the following equations.

Conversion rate = (number of moles of reacted raw material / number of moles of supplied raw material) × 100
Selectivity = (number of moles of compound produced / number of moles of reacted raw material) × 100
Yield = (Mole number of produced compound / Mole number of supplied raw material) × 100
[Example 1]
(Production of oxide)
In a mixed solution of 89.6 g of ion-exchanged water and 126.3 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, 54.0 g of molybdenum trioxide is added, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. Further, 212.5 g of a 10% by mass average particle diameter of 51 nm bismuth oxide aqueous dispersion, 15% by mass of 75.7 g of cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide having an average particle diameter of 39 nm. 11.4 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 80.4 g of the aqueous dispersion to obtain a solution (liquid B).

  147.7 g of 5% nitric acid solution as an oxidant was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. The obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
Using the obtained oxide as a catalyst, methacrolein was synthesized from isobutylene as follows. A jacketed SUS reaction tube with a diameter of 14 mm was filled with 5.5 g of oxide, and at a reaction temperature of 430 ° C., isobutylene was 8% by volume, oxygen was 12.8% by volume, water vapor was 3.0% by volume, and nitrogen capacity was 76.2%. A mixed gas consisting of was aerated at a flow rate of 120 mL / min (NTP) to carry out a methacrolein synthesis reaction. The reaction evaluation results are shown in Table 3.

[Example 2]
(Production of oxide)
59.1 g of molybdenum trioxide is added to a mixed solution of 98.2 g of ion-exchanged water and 138.3 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, and the mixture is stirred and mixed at about 70 ° C. and dissolved. (Liquid A) was obtained. Further, 48.0 g of 10% by mass bismuth oxide aqueous dispersion having an average particle diameter of 51 nm, 141.0 g of 15% by mass cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide water having an average particle diameter of 39 nm. A solution obtained by adding 8.5 g of ammonium polycarboxylate as a reducing agent to a liquid obtained by mixing 88.1 g of a dispersion, 5.1 g of a 10% by mass cesium hydroxide solution, and 1.9 g of 10% by mass potassium hydroxide. (Liquid B) was obtained.

  170.1 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. The obtained spray-dried oxide precursor was heated from room temperature at a heating rate of 0.14 ° C./min in a helium gas atmosphere and pre-baked at 250 ° C. for 3 hours to obtain a pre-fired oxide precursor. The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a helium gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 4.0 g. The reaction evaluation results are shown in Table 3.

[Example 3]
(Production of oxide)
In a mixed solution of 93.5 g of ion-exchanged water and 131.7 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, 56.3 g of molybdenum trioxide is added, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. Further, 110.9 g of a 10% by mass bismuth oxide aqueous dispersion having an average particle diameter of 51 nm, 110.6 g of a 15% by mass cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide water having an average particle diameter of 39 nm. 9.6 g of ammonium polycarboxylate as a reducing agent was added to a liquid obtained by mixing 88.9 g of the dispersion liquid and 16.5 g of a 10% by mass potassium hydroxide liquid to obtain a solution (liquid B).

  164.6 g of 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 5.9 g. The reaction evaluation results are shown in Table 3.

[Example 4]
(Production of oxide)
A mixed solution of 89.3 g of ion-exchanged water and 125.7 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidizing agent is charged with 53.7 g of molybdenum trioxide, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. In addition, 211.6 g of a 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.4 g of a 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. 11.4 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 80.1 g of the dispersion and 4.7 g of a 10% by mass cesium hydroxide solution to obtain a solution (solution B).

  147.6 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.7 g. The reaction evaluation results are shown in Table 3.

[Example 5]
(Production of oxide)
59.2 g of molybdenum trioxide is added to a mixed solution of 98.3 g of ion-exchanged water and 138.5 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, and is stirred and mixed at about 70 ° C. to dissolve and dissolve the solution ( A liquid) was obtained. Further, 77.7 g of a 10% by mass bismuth oxide aqueous dispersion having an average particle size of 51 nm, 49.8 g of a 15% by mass cobalt oxide aqueous dispersion having an average particle size of 22 nm, and 15% by mass of iron oxide water having an average particle size of 39 nm. To a liquid obtained by mixing 158.7 g of the dispersion liquid and 5.1 g of a 10% by mass cesium hydroxide liquid, 8.9 g of ammonium polycarboxylate as a reducing agent was added to obtain a solution (liquid B).

  162.6 g of 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was finally calcined at 520 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was carried out under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Example 6]
(Production of oxide)
In a mixed solution of 98.2 g of ion-exchanged water and 138.3 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, 59.1 g of molybdenum trioxide is stirred and mixed at about 70 ° C., dissolved, dissolved (solution ( A liquid) was obtained. Further, 77.6 g of 10% by mass bismuth oxide aqueous dispersion having an average particle diameter of 51 nm, 33.2 g of 15% by mass cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide water having an average particle diameter of 39 nm. 8.9 g of ammonium polycarboxylate as a reducing agent was added to a liquid obtained by mixing 176.1 g of the dispersion liquid, 3.1 g of 10 mass% cesium hydroxide liquid, and 1.8 g of 10 mass% rubidium hydroxide liquid. Solution (Liquid B) was obtained.

  162.5 g of 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was finally calcined at 520 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was carried out under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Example 7]
(Production of oxide)
58.8 g of molybdenum trioxide is added to a mixed solution of 97.7 g of ion-exchanged water and 137.6 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, and the mixture is stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. Further, 77.2 g of a 10% by mass average particle diameter of 51 nm bismuth oxide aqueous dispersion, 15% by mass of 16.5 g of cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide water having an average particle diameter of 39 nm. To a liquid obtained by mixing 192.7 g of a dispersion liquid, 5.1 g of a 10 mass% cesium hydroxide liquid, and 3.8 g of a 10 mass% potassium hydroxide liquid, 8.9 g of ammonium polycarboxylate was added as a reducing agent. A solution (liquid B) was obtained.

  162.8 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was finally calcined at 520 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was carried out under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Example 8]
(Production of oxide)
The spray-dried oxide precursor obtained in Example 3 was heated from room temperature at a heating rate of 75 ° C./min in a nitrogen gas atmosphere, and pre-fired at 250 ° C. for 3 hours to obtain a pre-fired oxide precursor. It was. The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Example 9]
(Production of oxide)
The spray-dried oxide precursor obtained in Example 3 was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and pre-baked at 250 ° C. for 3 hours. Got. The obtained calcined oxide precursor was calcined at 400 ° C. for 48 hours in a nitrogen atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.9 g. The reaction evaluation results are shown in Table 3.

[Example 10]
(Production of oxide)
The spray-dried oxide precursor obtained in Example 3 was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and pre-baked at 250 ° C. for 3 hours. Got. The obtained calcined oxide precursor was calcined at 640 ° C. for 30 minutes in a nitrogen atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 4.8 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 1]
(Production of oxide)
The spray-dried oxide precursor obtained in Example 1 was heated from room temperature at a heating rate of 0.14 ° C./min in an air atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. Obtained. The obtained calcined oxide precursor was finally calcined at 530 ° C. for 3 hours in an air atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 5.9 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 2]
(Production of oxide)
57.7 g of molybdenum trioxide is added to a mixed solution of 95.9 g of ion-exchanged water and 135.0 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, and the mixture is stirred and mixed at about 70 ° C. (Liquid A) was obtained. In addition, 166.6 g of 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 121.4 g of 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. To a liquid obtained by mixing 31.0 g of a dispersion liquid, 15.0 g of a 10 mass% cesium hydroxide liquid and 1.9 g of potassium hydroxide liquid, 9.9 g of ammonium polycarboxylate as a reducing agent was added, and the solution (liquid B )

  150.97 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 2 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 4.5 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 3]
(Production of oxide)
58.5 g of molybdenum trioxide is added to a mixed solution of 97.2 g of ion-exchanged water and 136.8 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, and the mixture is stirred and mixed at about 70 ° C. and dissolved. (Liquid A) was obtained. In addition, 76.8 g of a 10% by mass bismuth oxide aqueous dispersion having an average particle diameter of 51 nm, 13.1 g of a 15% by mass cobalt oxide aqueous dispersion having an average particle diameter of 22 nm, and 15% by mass of iron oxide water having an average particle diameter of 39 nm. 9.0 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 200.4 g of the dispersion and 5.1 g of a 10% by mass cesium hydroxide solution to obtain a solution (solution B).

  162.6 g of 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was finally calcined at 520 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.3 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 4]
(Production of oxide)
In a mixed solution of 125.7 g of ion-exchanged water and 89.3 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, 53.7 g of molybdenum trioxide is stirred and mixed at about 70 ° C., dissolved, dissolved (solution ( A liquid) was obtained. In addition, 211.6 g of a 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.4 g of a 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. A solution obtained by adding 11.4 g of ammonium polycarboxylate as a reducing agent and 35.3 g of tartaric acid as a reducing agent to a solution obtained by mixing 80.1 g of the dispersion and 4.7 g of a 10% by mass cesium hydroxide solution (B Liquid).

  147.6 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.7 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 5]
(Production of oxide)
A solution (solution A) was obtained by dissolving 67.4 g of ammonium heptamolybdate in 199.1 g of warm water at about 90 ° C. In addition, 211.6 g of a 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.4 g of a 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. 11.4 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 80.1 g of the dispersion and 4.7 g of a 10% by mass cesium hydroxide solution to obtain a solution (solution B).

  Both liquids A and B were mixed and stirred and mixed for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a heating rate of 0.14 ° C./min in a helium gas atmosphere, and pre-fired at 250 ° C. for 3 hours to obtain a pre-fired oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a helium gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.7 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 6]
(Production of oxide)
In a mixed solution of 125.7 g of ion-exchanged water and 89.3 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidant, 53.7 g of molybdenum trioxide is added, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. In addition, 211.6 g of a 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.4 g of a 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. 80.1 g of the dispersion liquid and 4.7 g of 10% by mass cesium hydroxide liquid were mixed to obtain a solution (liquid B).

  147.6 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
A methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.7 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 7]
(Production of oxide)
A mixed solution of 89.3 g of ion-exchanged water and 125.7 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidizing agent is charged with 53.7 g of molybdenum trioxide, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. In addition, 211.6 g of a 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.4 g of a 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass of iron oxide water with an average particle size of 39 nm. 11.4 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 80.1 g of the dispersion and 4.7 g of a 10% by mass cesium hydroxide solution to obtain a solution (solution B).

  246.0 g of a 5% nitric acid solution as an oxidizing agent was added to the mixture obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 8]
(Production of oxide)
The spray-dried oxide precursor obtained in Example 3 was heated from room temperature at a heating rate of 0.14 ° C./min in an air atmosphere and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. Obtained. The obtained calcined oxide precursor was finally calcined at 520 ° C. for 8 hours in a nitrogen gas atmosphere to obtain an oxide. Table 1 shows the composition of the obtained oxide, and Table 2 shows the measurement results of powder X-ray diffraction.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

[Comparative Example 9]
(Production of oxide)
The calcined oxide precursor obtained in Example 3 was calcined at 520 ° C. for 8 hours in an air atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 1, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 2.

<X-ray diffraction peaks of oxides obtained in Examples 4 and 7 and Comparative Examples 2 and 6>
The X-ray diffraction peaks of the oxides obtained in Examples 4 and 7 and Comparative Examples 2 and 6 are shown in FIG. FIG. 2 shows an enlarged view of the range of 2θ = 25 to 27 ° of the X-ray diffraction peak in FIG. 1 and 2, in the X-ray diffraction of the oxides obtained in Examples 4 and 7, the X-ray diffraction angle (2θ) of the (002) plane of the complex oxide of cobalt and molybdenum is 26.24 in order. It was found that peaks were observed at 26 ° and 26.16 °. That is, in the oxides obtained in Examples 4 and 7, divalent Fe was further dissolved in the composite oxide of Co and Mo, so that composite Co ²⁺ -Fe ²⁺ -Mo was formed. It is considered that a new crystal structure of a three-component system of —O was newly formed. On the other hand, in the X-ray diffraction of the oxides obtained in Comparative Examples 2 and 6, the X-ray diffraction angle (2θ) of the (002) plane of the complex oxide of cobalt and molybdenum both peaks at 26.38 °. I found out. That is, in the oxides obtained in Comparative Examples 2 and 6, it is considered that a new ternary crystal structure of Co ²⁺ -Fe ²⁺ -Mo-O was not formed.

<Mossbauer spectrum of oxides obtained in Example 4 and Comparative Example 6>
FIG. 3 shows the Mossbauer spectrum of the oxide obtained in Example 4, and FIG. 4 shows the Mossbauer spectrum of the oxide obtained in Comparative Example 6.

  From FIG. 3, it was found that the oxide obtained in Example 4 had a divalent iron ratio of 92% and a trivalent iron ratio of 8%.

  From FIG. 4, it was found that the oxide obtained in Comparative Example 6 had a ratio of divalent iron of 0% and a ratio of trivalent iron of 100%.

[Synthesis of methacrolein]
The methacrolein synthesis reaction was performed under the same reaction conditions as in Example 1 except that the obtained oxide was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 3.5 g. The reaction evaluation results are shown in Table 3.

<T-butyl alcohol->methacrolein>
[Example 11]
[Synthesis of methacrolein]
Using the oxide obtained in Example 4 as a catalyst, methacrolein was synthesized from t-butyl alcohol as follows. An SUS reaction tube with a diameter of 14 mm was charged with 4.0 g of oxide, and at a reaction temperature of 430 ° C., t-butyl alcohol 8 vol%, oxygen 12.8 vol%, water vapor 3.0 vol%, and nitrogen capacity 76 A mixed gas composed of 2% was aerated at a flow rate of 120 mL / min (NTP) to perform a methacrolein synthesis reaction. The reaction evaluation results are shown in Table 4.

[Comparative Example 10]
[Synthesis of methacrolein]
The methacrolein was converted from t-butyl alcohol under the same reaction conditions as in Example 11 except that the oxide obtained in Comparative Example 6 was used as a catalyst and the amount of oxide charged in the reaction tube was changed to 4.6 g. Synthesized. The reaction evaluation results are shown in Table 4.

<Propylene → Acrolein>
[Example 12]
(Production of oxide)
A mixed solution of 89.5 g of ion-exchanged water and 126.1 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidizing agent is charged with 53.9 g of molybdenum trioxide, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. Further, 212.2 g of 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.6 g of 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass iron oxide water with an average particle size of 39 nm. 11.4 g of ammonium polycarboxylate as a reducing agent was added to a solution obtained by mixing 80.3 g of the dispersion and 1.4 g of a 10% by mass cesium hydroxide solution to obtain a solution (solution B).

  246.1 g of a 5% nitric acid solution as an oxidizing agent was added to the mixed solution obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 5, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 6.

Synthesis of A Kurorein]
Acrolein was synthesized from propylene using the obtained oxide as a catalyst. 20 mL of catalyst is packed in a SUS jacketed reaction tube with an inner diameter of 15 mm, a source gas having a propylene concentration of 10% by volume, a water vapor concentration of 17% by volume and an air concentration of 73% by volume is passed through to conduct acrolein synthesis reaction at a reaction temperature of 320 ° C Carried out. Table 7 shows the reaction evaluation results.

[Comparative Example 11]
(Production of oxide)
A mixed solution of 89.5 g of ion-exchanged water and 126.1 g of hydrogen peroxide solution having a concentration of 30% by mass as an oxidizing agent is charged with 53.9 g of molybdenum trioxide, stirred and mixed at about 70 ° C., dissolved, and dissolved. (Liquid A) was obtained. Further, 212.2 g of 10% by mass bismuth oxide aqueous dispersion with an average particle size of 51 nm, 75.6 g of 15% by mass cobalt oxide aqueous dispersion with an average particle size of 22 nm, and 15% by mass iron oxide water with an average particle size of 39 nm. 80.3 g of the dispersion and 1.4 g of 10% by mass cesium hydroxide solution were added to obtain a solution (solution B).

  246.1 g of a 5% nitric acid solution as an oxidizing agent was added to the mixed solution obtained by mixing both the A and B solutions, and the mixture was stirred for about 3 hours to obtain a raw material slurry. This raw material slurry was sent to a spray dryer and spray-dried at an inlet temperature of 250 ° C. and an outlet temperature of about 140 ° C. to obtain a spray-dried oxide precursor. Further, the obtained spray-dried oxide precursor was heated from room temperature at a temperature rising rate of 0.14 ° C./min in a nitrogen gas atmosphere, and calcined at 250 ° C. for 3 hours to obtain a calcined oxide precursor. . The obtained calcined oxide precursor was calcined at 530 ° C. for 3 hours in a nitrogen gas atmosphere to obtain an oxide. The composition of the obtained oxide is shown in Table 5, and the valence of iron in the oxide and the measurement result of powder X-ray diffraction are shown in Table 6.

Synthesis of A Kurorein]
Acrolein was synthesized from propylene under the same reaction conditions as in Example 12 except that the obtained oxide was used as a catalyst and 20 mL of the catalyst was charged into a reaction tube. Table 7 shows the reaction evaluation results.

<N-butene → butadiene>
[Example 13]
[Butadiene synthesis]
Using the oxide obtained in Example 4 as a catalyst, butadiene was synthesized from n-butene as follows. A jacketed SUS reaction tube with a diameter of 14 mm was charged with 4.0 g of oxide, and a mixed gas consisting of 8% by volume of n-butene, 12.8% by volume of oxygen, and 79.2% of nitrogen volume at a reaction temperature of 360 ° C. Aeration was conducted at a flow rate of 120 mL / min (NTP) to carry out a butadiene synthesis reaction. Table 8 shows the reaction evaluation results.

[Comparative Example 12]
[Butadiene synthesis]
Butadiene was synthesized from n-butene under the same reaction conditions as in Example 13 except that the oxide obtained in Comparative Example 6 was used as a catalyst. Table 8 shows the reaction evaluation results.

Claims (12)

Contains molybdenum, bismuth, iron and cobalt,
An oxide having a ratio of Fe ²⁺ / (Fe ²⁺ + Fe ³⁺ ) of 0.7 or more and less than 1.0.   The oxide according to claim 1, wherein the atomic ratio b of iron is 5 ≦ b ≦ 11 with respect to 12 atoms of molybdenum.   The oxide according to claim 1 or 2, wherein a ratio (b / c) of an atomic ratio b of iron to an atomic ratio c of cobalt is 0.5 ≦ b / c ≦ 11 with respect to 12 atoms of molybdenum.   The oxide as described in any one of Claims 1-3 whose atomic ratio a of bismuth is 0.5 <= a <= 5 with respect to 12 atoms of molybdenum. The oxide contains a composite oxide of cobalt and molybdenum;
In the X-ray diffraction of the oxide, at least the (002) plane X-ray diffraction angle (2θ) of the complex oxide of cobalt and molybdenum shows a peak (maximum intensity) at 26.15 ° to 26.35 °. The oxide as described in any one of Claims 1-4. The oxide according to any one of claims 1 to 5, which has a composition represented by the following composition formula (1).
(In the formula (1), Mo represents molybdenum, Bi represents bismuth, Fe represents iron, Co represents cobalt, A represents at least one alkali element selected from the group consisting of cesium, rubidium and potassium, and a to e are The atomic ratio of each element to Mo12 atoms is shown, 0.5 ≦ a ≦ 5, 5 ≦ b ≦ 11, 0.5 ≦ b / c ≦ 11, 0.01 ≦ d ≦ 2, and e is other than oxygen (The atomic ratio of oxygen is determined by the valence of the constituent elements.) The catalyst for unsaturated aldehyde manufacture or the butadiene manufacture containing the oxide as described in any one of Claims 1-6. Mixing a raw material for forming an oxide containing molybdenum, bismuth, iron and cobalt to obtain a mixture;
Drying the obtained mixture to obtain a dried product;
A step of pre-baking the obtained dry body to obtain a pre-fired body,
Including a step of subjecting the obtained temporarily fired body to main firing to obtain an oxide,
In the oxide, the atomic ratio a of bismuth to 12 atoms of molybdenum is 0.5 ≦ a ≦ 5, the atomic ratio b of iron is 5 ≦ b ≦ 11, and the ratio of the atomic ratio b of iron to the atomic ratio c of cobalt ( b / c) is adjusted so that the mixing ratio of each raw material is 0.5 ≦ b / c ≦ 11,
The pre-baking is performed in the presence of an oxidizing agent and a reducing agent;
The preliminary baking and the main baking are performed in an inert gas atmosphere,
The method for producing an oxide, wherein the main baking is performed at a temperature higher than the temperature of the preliminary baking.   The manufacturing method of unsaturated aldehyde using the catalyst of Claim 7.   A method for producing butadiene using the catalyst according to claim 7.   A method for producing an unsaturated aldehyde, comprising a step of oxidizing at least one selected from the group consisting of propylene, isobutylene and t-butyl alcohol using the catalyst according to claim 7.   A method for producing butadiene, comprising a step of oxidizing n-butene using the catalyst according to claim 7.