JP2002045693A - Oxide catalyst, method for producing the same, and gas phase catalytic oxidation reaction method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and stable oxide catalyst containing at least molybdenum, vanadium and antimony and a method for producing the same, and to provide a gas phase catalytic oxidation reaction method using this oxide catalyst. provide. SOLUTION: In a method for producing an oxide catalyst containing at least a metal element of molybdenum, vanadium and antimony, a catalyst precursor obtained by drying and calcining a solution or slurry containing a starting compound of each metal element is pulverized. And then firing again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oxide catalyst containing molybdenum, vanadium and antimony, a method for producing the same, and a gas phase catalytic oxidation reaction using the same. More specifically, the present invention relates to a highly active oxide catalyst containing molybdenum, vanadium, and antimony used in a gas phase catalytic oxidation reaction of alkanes, and a method for producing the same.

[0002]

2. Description of the Related Art Composite oxides containing molybdenum, vanadium and antimony or tellurium as essential components are known to exist in the field of catalysts, particularly as partial oxidation catalysts. The method of producing unsaturated nitriles by gas-phase catalytic oxidation from alkanes has direct economic effects resulting from the price difference between alkanes and alkenes, and the effective use of substances that have not been effectively used as raw materials for conventional chemical products. Since it is possible, many proposals have been made,
For example, JP-A-9-157241 discloses an ammoxidation reaction of propane to acrylonitrile at a relatively low temperature of 450 ° C. or lower.

As a catalyst capable of producing an unsaturated nitrile from an alkane at such a low temperature, in addition to a Mo-V-Sb-O-based catalyst, a Mo-V-Te-O-based catalyst (Japanese Patent Application Laid-Open No. 2-2 / 1990)
57, JP-A-5-208136).
On the other hand, those requiring a reaction temperature close to 500 ° C.
-Sb-O based catalysts (JP-A-47-337823, JP-B-50-23016, JP-A-1-268668, JP-A-2-180637, JP-A-2-261544,
JP-A-4-275266, JP-A-5-293374
JP-A-6-15170, JP-A-8-290058
JP-A-9-103677, JP-A-10-2256
No. 34, JP-A-11-33399, JP-A-10-27
No. 2362) is known, but the required reaction temperature of the V-Sb-O catalyst is about 100 ° C. as compared with the Mo-V-Te-O or Mo-V-Sb-O-based catalyst.
And the yield of unsaturated nitriles obtained is clearly lower.

[0004] For Mo-V-Te-O type catalysts, a specific method for producing a catalyst capable of obtaining higher activity and selectivity has been disclosed. For example, JP-A-6-285372 discloses M-V-Te-O type catalysts.
In the o-V-Te-O catalyst, it is disclosed that spray drying or freeze drying is advantageous, and that the obtained dried product is heat-treated, pulverized, and further calcined to improve the performance. However, the performance improvement is a few percent. Applied Catalysis A: Gener
al 194-195 (2000) 479-485, it has been reported that the specific surface area is increased and the reaction rate is improved by applying a hydrothermal synthesis method in the preparation of a Mo-V-Te-O catalyst. However, no significant improvement in yield was reported. On the other hand, Mo-VS
For the b-O catalyst, there is no report that the yield is improved by operations such as pulverization / recalcination or hydrothermal reaction.
-330343 is a specific unit cell parameter,
It is disclosed that a crystalline composite oxide (phase-i) having a specific powder X-ray diffraction peak gives a higher yield, and as a method for obtaining a composite oxide having a specific structure,
A method of performing baking again after washing is exemplified.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Mo-VT
Comparing the e-O-based and Mo-V-Sb-O-based catalysts,
The Mo-V-Sb-O system is considered to be industrially advantageous in that it does not contain Te which is easy to volatilize and is inexpensive,
On the other hand, in the case of the Mo-V-Te-O-based catalyst, the reported value of the single-stream yield of acrylonitrile reaches 56% or more (Japanese Patent Laid-Open No. 2000-126599).
In the case of the o-V-Sb-O system, even when an operation such as cleaning is performed, it is about 52% (JP-A-2000-93796).
In particular, a method for increasing the yield of the -V-Sb-O system has been desired.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that, in a method for producing a gas phase catalytic oxidation reaction using a hydrocarbon as a raw material, at least an oxide containing molybdenum, vanadium and antimony is contained. By using a catalyst prepared by a specific method or using a catalyst whose primary particles have a specific morphology, a much higher yield than a conventionally known Sb-based catalyst can be obtained. Have been obtained, and the present invention has been achieved.

That is, a first gist of the present invention is to provide a method for producing an oxide catalyst containing at least a metal element of molybdenum, vanadium and antimony, wherein a solution or slurry containing a starting compound of each metal element is dried to form a solid. And then calcining the obtained solid, pulverizing a catalyst precursor obtained and calcining the catalyst precursor again, and then calcining the solid again.

[0008] A second gist of the present invention is that an oxide catalyst containing at least molybdenum, vanadium and antimony has a columnar or prismatic shape by electron microscopic observation, or has a unit cell parameter determined by electron beam diffraction. Is a = 2.677 (± 0.04) nm, b
= 2.122 (± 0.04) nm, c = 0.401 (±
0.006) Select at least 100 primary particles of the catalytically active component which are orthorhombic (α = β = γ = 90 °) nm (where a has a possibility of an integer multiple of the above value), An oxide catalyst characterized in that the average value of the anisotropic ratio of the selected primary particles is 0.5 or more.

A third aspect of the present invention is that an oxide catalyst containing at least molybdenum, vanadium and antimony has a columnar or prismatic shape by electron microscopic observation, or has a unit cell parameter determined by electron beam diffraction. Is a = 2.677 (± 0.04) nm, b
= 2.122 (± 0.04) nm, c = 0.401 (±
0.006) Select at least 100 primary particles of the catalytically active component which are orthorhombic (α = β = γ = 90 °) nm (where a has a possibility of an integer multiple of the above value), An oxide catalyst characterized in that the average value of the maximum length of the selected primary particles is 0.3 μm or less.

[0010] Further, a fourth aspect of the present invention relates to an oxide catalyst produced by the method described in the first aspect, or a hydrocarbon using the oxide catalyst described in the second or third aspect. To perform gas phase catalytic oxidation of

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The oxide catalyst of the present invention is an oxide catalyst containing at least molybdenum, vanadium and antimony as essential elements. Then, in order to further enhance the catalyst performance, niobium, tantalum, tungsten, and titanium are usually contained in addition to these essential components. Of these, especially niobium,
Tantalum, preferably contains titanium, niobium,
Tantalum is more preferred. Most preferably, it is niobium.

The oxide catalyst of the present invention is suitably used for producing an organic compound by a gas phase catalytic oxidation reaction of a hydrocarbon. The gas-phase catalytic oxidation reaction of hydrocarbons is a reaction in which hydrocarbons are oxidized in gaseous phase with oxygen, and also includes a reaction in which ammonia and water vapor are present in the reaction system in addition to oxygen. It is used for the production of various organic compounds such as fluorinated organic compounds and nitriles. The oxide catalyst of the present invention has excellent catalytic activity in the partial oxidation reaction of alkane having low reactivity among hydrocarbons, and by appropriately selecting the conditions of the gas phase catalytic oxidation reaction, the nitriles such as acrylonitrile can be obtained. It is suitably used for various reactions such as production and production of α, β-unsaturated carboxylic acids such as acrylic acid.

The catalyst of the present invention particularly preferably employs a catalyst composition represented by the following general formula (1).

[0014]

Embedded image MoaVbSbcXdOn (1)

In the formula (1), X is Ti, Zr, Nb, T
a, Cr, W, Mn, Fe, Ru, Co, Rh, Ir,
Ni, Pd, Pt, Cu, Ag, Zn, In, Sn, P
b, Bi, Ce, at least one metal element selected from alkali metals and alkaline earth metals;
When it is 1, 0.01 ≦ b ≦ 1, preferably 0.1 ≦ b
b ≦ 0.6, 0 <c ≦ 1, preferably 0.01 ≦ c ≦
0.4, 0 ≦ d ≦ 1, preferably 0.01 ≦ d ≦
0.6 and n are values determined by the oxidation state of other elements.

Next, a method for producing an oxide catalyst, which is the first gist of the present invention, will be described. First, a solution or slurry containing a starting compound of each metal element constituting the catalyst is prepared. The method for preparing the solution is described in, for example,
No. 57241, a method utilizing a chemical reaction when diantimony trioxide is heated in a solution containing vanadium, or oxidation of molybdenum oxometalate, if necessary, described in JP-A-11-226408. An agent may be added to oxidize and dissolve metal antimony or diantimony trioxide. Antimony is molybdenum,
Alternatively, the preparation method is particularly preferable if it can react with oxometalate of vanadium to form a stable solution or suspension and form an aqueous solution or a stable slurry in which molybdenum, vanadium, and antimony are uniformly mixed. Not restricted.

As the raw material compound of each metal element used in the present invention, molybdenum is usually a compound containing Mo, at least a part of which is soluble in water, preferably a water-soluble compound containing Mo. . Preferably, ammonium paramolybdate, molybdic acid, molybdenum trioxide, molybdenum pentachloride, molybdenyl acetylacetonate, molybdenum alkoxides and the like are used, preferably ammonium paramolybdate or molybdic acid, molybdenum trioxide, most preferably. Ammonium paramolybdate.

Vanadium is a compound containing V, which is usually at least partially soluble in water, and is preferably a water-soluble compound containing V. Preferably ammonium metavanadate, vanadyl sulfate, vanadyl oxalate,
Vanadium pentoxide, vanadium oxychloride, alkoxides of vanadium and acetylacetonates are used, preferably ammonium metavanadate, vanadyl sulfate, vanadyl oxalate, and vanadium pentoxide, with ammonium metavanadate being particularly preferred. The antimony raw material is not particularly limited as long as it is a raw material containing antimony. Preferably, diantimony trioxide, metal antimony, and antimony trisalt are used. Among them,
Diantimony trioxide is particularly preferred.

In the thus obtained solution containing antimony, molybdenum, vanadium and the like, a compound containing another catalytic metal component is dissolved or suspended as necessary so that a desired catalyst composition is obtained. Next, the obtained solution or slurry is dried and calcined to obtain a catalyst precursor. Alternatively, the obtained solution or slurry is sealed in a pressure vessel, and a solid is obtained by a hydrothermal reaction in which the solid is treated at a temperature of 100 ° C. to 350 ° C., and the obtained solid is separated and fired as necessary. A catalyst precursor can also be obtained. Compounds containing other catalytic metal components include niobium,
For tantalum, tungsten, and titanium, carboxylate, ammonium carboxylate, ammonium oxyacid, oxyacid, oxide, and the like are used. As for niobium, tantalum and titanium, commercially available oxide sols are also preferably used.

The drying is performed by an evaporation-drying method, a spray drying method, or a vacuum drying method, and the spray drying method is particularly preferable. The drying temperature is usually 80 to 400 ° C, preferably 120 to 280.
° C, more preferably 160-220 ° C. Firing
Usually, the reaction is carried out at 350 to 700 ° C. for 0.5 to 30 hours in an inert gas atmosphere such as a nitrogen gas having a limited oxygen concentration. It is particularly preferred that the temperature is maintained in the temperature range of ６640 ° C. for several hours. The firing method can take various forms such as a fixed bed method, a fluidized bed method, a kiln and a tunnel furnace, but a fluidized bed, a kiln and the like are industrially advantageous.
During firing, the time required to reach a predetermined temperature is several minutes to
It may be several hours, but preferably within 3 hours, more preferably 1 hour or less.

If necessary, heat treatment can be performed prior to firing. Various forms of the heat treatment can be adopted, but it is advantageous industrially to carry out the heat treatment continuously using a kiln or the like. The conditions of this heat treatment are preferably performed at a temperature higher than the drying temperature and lower than the firing temperature, for example, 250 to 400 ° C., and a residence time of several seconds to tens of minutes under the flow of air, nitrogen gas, or the like. is there. The atmosphere for the heat treatment is preferably performed under a flow of an oxygen-containing gas such as air. Most preferably, it is under circulation of air. Heat treatment temperature is 300
-400 ° C is preferred, and 350-400 ° C is more preferred. Most preferably, it is 380-390 ° C.

The catalyst precursor thus obtained functions as it is as a catalyst for a gas phase catalytic oxidation reaction for nitrile production or the like. However, the catalyst precursor is subjected to a pulverization treatment and then calcined again. By doing so, a remarkable improvement in yield is observed. The conditions for the second firing can be the same as those for the first firing. In the above-mentioned pulverization method, the average particle size of the secondary particles after pulverization is usually 20 μm or less, preferably 5 μm or less.
Any known pulverization method can be employed without particular limitation as long as the primary particles of the catalytically active component after the pulverization have been pulverized to an average particle diameter of 0.1 μm or less. In the present invention, the secondary particles constituting the oxide catalyst or the catalyst precursor are particles in which primary particles such as a catalytically active component and silica are aggregated, and the average particle size thereof is a known particle size such as a laser granulometer. Can be used.

Known pulverization methods are roughly classified into a dry pulverization method and a wet pulverization method. The dry pulverization method includes an air flow pulverizer that causes pulverization by collision of particles under a high-speed air flow, and a mechanical pulverization method. Or, on a small scale, crushing with a mortar or the like. In the wet pulverization method, water or an organic solvent or the like is added to the composite oxide to perform pulverization in a wet state, and a cylindrical rotary medium pulverizer, a medium stirring type pulverizer, or the like can be used. The cylindrical rotary medium pulverizer indicates a wet pulverizer in which a container containing a pulverizing medium is rotated, and examples thereof include a ball mill and a load mill. The medium stirring type pulverizer refers to a wet type pulverizer in which a pulverizing medium in a container is stirred, and examples thereof include a screw rotary type and a disk rotary type.

In the case of producing spherical particles used in a fluidized bed reaction, a binder such as silica sol is added as required after pulverization, followed by spray drying and firing. Firing following pulverization is usually performed in an atmosphere of an inert gas such as nitrogen gas with a limited oxygen concentration at a temperature of 350 to 7 ° C.
The reaction is carried out at a temperature of 00 ° C., a temperature rise time of 0.1 to 10 hours, preferably 3 hours or less, and a holding time of 0.5 to 30 hours.
It is particularly preferred that the temperature is kept in the temperature range of 0 to 640 ° C. for several hours.

As described above, it is not clear why the catalyst performance is improved by pulverizing the catalyst precursor and firing it again, but it is speculated as follows. The primary particles of the oxide crystals generated after firing the dried material are changed to finer particles by pulverization, which grows into new crystal particles by re-firing, but the shape of the oxide particles before the pulverization is changed. The performance of the catalyst is different from that of catalysts, for example, by generating primary particles of a new shape with an increased proportion of crystal planes that are advantageous for producing useful substances such as unsaturated nitriles and unsaturated carboxylic acids. It is inferred that it has improved.

Next, an oxide catalyst having a specific primary particle morphology, which is the second or third aspect of the present invention, will be described. As described above, the oxide catalyst or catalyst precursor of the present invention comprises a catalytically active component (composite oxide phase-i shown in JP-A-10-330343), silica, a carrier, a binder, and a catalyst disclosed in JP-A-10-330343. Are composed of secondary particles in which primary particles of an inactive component such as a complex oxide (phase-k) shown in (1) are aggregated, and the form of the primary particles is usually easily observed with a scanning electron microscope. be able to. According to the shape observation by electron microscope observation, phase-i has a width of usually 0.04 to 0.4 μm.
m is a columnar or prismatic composite oxide having a maximum length of usually 0.5 to 2.5 μm, and phase-k is an irregularly shaped composite oxide having an average particle size of 0.2 to 2 μm. These primary particles are sufficiently dispersed in a dispersion solvent (acetone, alcohol, water, etc.) by ultrasonic waves or the like so as to reduce particle overlap, and after removing the dispersion medium by drying, scanning at a magnification of about 30,000 times. The morphology of the primary particles is recorded by a scanning electron microscope, and the primary particles (phase-i) of the Mo-V-Sb-O-based catalytically active component and silica, a carrier, a binder, or other components other than the active component such as phase-k Components. This discrimination is usually possible by the shape of the primary particles (cylindrical or prismatic) as described later, but if it is difficult to discriminate even by the shape, X-ray diffraction, electron beam diffraction and transmission electrophotography It can be identified by a microscope or an elemental analysis such as an X-ray microanalyzer.

In the present invention, the primary particles (phase-i) of the catalytically active component having any of the following (1) and (2) are determined from the surface or fracture surface of the secondary particle containing the catalytically active component. Is selected 100 or more. (1) It has a columnar or prismatic shape as observed by an electron microscope. (2) The unit cell parameter by electron diffraction is a
= 2.677 (± 0.04) nm, b = 2.122 (±
0.04) nm, c = 0.401 (± 0.006) nm
(However, a has the possibility of an integer multiple of the above numerical value) and is orthorhombic (α = β = γ = 90 °). With respect to the selected primary particles (hereinafter, referred to as selected primary particles), the minor axis diameter (width) and the major axis diameter (maximum length) of each particle are measured from the outline, and the arithmetic average value thereof is expressed as the maximum length, Alternatively, an anisotropic ratio (width of particles / maximum length) is calculated to represent the form of primary particles. Here, the maximum length is the distance between two points giving the maximum ferret length in the major axis direction of the characteristic ellipse, and the width is the ferret length orthogonal to the maximum length. When selecting 100 or more primary particles (phase-i), it is preferable to select the primary particles in order from the longest one in the entire recorded visual field.

In the case of (1), in which the shape of the primary particles is selected by recognizing the shape by a scanning electron microscope photograph, the shape is clearly defined as a column or a corner by observing from a plurality of visual fields. It is necessary to select primary particles that can be recognized as columnar. In the case of (2), in which the primary particles are identified and selected by electron beam diffraction or X-ray diffraction, the minute portion X
The secondary particles including the selected primary particles can be specified by showing the X-ray diffraction peaks (using CuKα rays) in the following table in the secondary particles by X-ray diffraction or the like. In order to identify the primary particles, the unit cell parameter by electron diffraction is a = 2.677.
(± 0.04) nm, b = 2.122 (± 0.04) n
m, c = 0.401 (± 0.006) nm (where a
Is an integer multiple of the above value) orthorhombic (α =
(β = γ = 90 °) primary particles of the catalytically active component are selected. The primary particles (phase-i) of the catalytically active component having the above-mentioned characteristic (2) are considered to have a columnar or prismatic shape. Specifying is not practical in terms of cost. Therefore, in the present invention, a practical method for selecting primary particles is to first measure electron beam diffraction for primary particles having the characteristic (1) (columnar or prismatic), and to determine the characteristic (2). Phase-i having
After confirming that the primary particles (phase-
This is a method for selecting primary particles having the same shape as in i). In the method (1) (judgment based on the shape), it is difficult to determine whether or not the primary particles have the characteristic (2). It is preferable to apply the method of (2). Further, the powder X-ray diffraction confirmed that the crystalline oxide having the peaks in the following table was the majority of the secondary particles, and the surface or fracture surface of the secondary particles was observed by a scanning electron microscope. When it can be confirmed that the primary particles are cylindrical, prismatic, or needle-shaped, the secondary particles can be more simply determined to be mostly composed of phase-i primary particles. It is preferable to select a suitable secondary particle.

[0029]

[Table 1]

In calculating the maximum length or anisotropic ratio of the primary particles as described above, the secondary particles containing the catalytically active component may be selected from a single secondary particle or a plurality of secondary particles. However, it is preferable to select the primary particles so that there is no significant deviation from two or more secondary particles. In the present invention, the average value of the maximum length or the anisotropic ratio of the selected primary particles obtained by the above calculation method is regarded as the average value of the entire oxide catalyst or catalyst precursor. For the calculation, a normal image processing system can be used. Even in the case of spherical secondary particles of several tens of microns for a fluidized bed, at least 100 or more primary particles are selected in the same manner, and the primary particles of the catalytically active component are similarly observed by a scanning electron microscope. Can be observed.

The oxide catalyst of the present invention has an average value of anisotropic ratio of selected primary particles (catalytically active components) of 0.5 or more, preferably 0.6 or more, more preferably 0.1 or more, according to the above-mentioned calculation method. The oxide catalyst becomes 7 or more. Further, the oxide catalyst has an average of the maximum length of the selected primary particles (catalytic active component) of 0.3 μm or less, preferably 0.27 μm or less, more preferably 0.25 μm or less.

In the Mo-V-Sb-O-based oxide catalyst of the present invention described above, 95% or more of the selected primary particles of the catalytically active component (phase-i) excluding the carrier, the binder and the like have a maximum length of 0.1%. It is preferred to be composed of primary particles having a width of 2 to 0.4 microns and a width of 0.05 to 0.2 microns.
Further, as the form of the primary particles having a size in this range, those having high uniformity are more preferable, and the coefficient of variation of the maximum length and / or width of the selected primary particles is 60% or less, as measured by the electron microscope. Is preferable, and 50% or less is more preferable. Here, the coefficient of variation (v) is the ratio (%) of the standard deviation (s) of the measured values to the arithmetic mean (<x>),
It is defined by the following equation (2).

[0033]

Equation 1 v = s / <x> × 100 (2)

The oxide catalyst of the present invention comprising the primary particles in the above-mentioned form can be prepared by selecting an appropriate starting compound or by employing a known method such as a hydrothermal synthesis method in combination. However, as described above, the catalyst or precursor obtained by drying and calcining the solution or slurry containing the raw material compound by a conventional method is pulverized, and then calcined again, thereby changing the morphology of the primary particles. It is also possible to prepare an oxide catalyst of The Mo-V-Sb oxide of the present invention, which is useful as a catalyst for selective (ammo) oxidation of alkanes, has its primary particles further finely crushed by pulverization. In this pulverization step, the average particle size of the primary particles is 0.1.
It is easier and more convenient to adopt a method of completely crushing amorphous particles of 1 micron or less or their agglomerates and then firing again and controlling the morphology of primary particles by the degree of sintering and particle growth by firing. preferable.

When the above-described method for producing an oxide catalyst according to the first aspect of the present invention is employed, the obtained oxide catalyst may have the above-mentioned (1) and / or (2)
100 or more primary particles of the catalytically active component having the following characteristics are selected, and the anisotropic ratio (average value) of the selected primary particles (selected primary particles) is different from the primary particles of the catalyst precursor before pulverization. 10% or more compared to the direction ratio (average value), and even 20%
As described above, it is particularly preferable to manufacture the oxide catalyst so as to increase by 40% or more. Similarly, the average of the maximum length of the selected primary particles is preferably reduced by 10% or more, more preferably 20% or more, particularly preferably 40% or more, while the width of the primary particles is 1% or more, more preferably Preferably, it is increased by 3% or more, especially 5% or more.

The metal oxide obtained by the method of the present invention can be used alone as a catalyst, but may be selected from the metal oxide obtained by the method of the present invention and Si, Al, Zr, Ti, and alkaline earth metals. One or more carrier components such as oxides may be used in the same particle. Further, the reaction may be used in a state where particles containing a metal oxide and particles made of one or more oxides selected from Si, Al, Zr, Ti and alkaline earth metals are mixed.

Next, a gas phase catalytic oxidation reaction method according to the fourth aspect of the present invention will be described. Examples of the hydrocarbon used as a raw material for the gas phase catalytic oxidation reaction include alkanes or alkenes having 3 to 8 carbon atoms and aromatic compounds having 6 to 12 carbon atoms. Examples of the reaction include production of nitriles by ammoxidation of alkanes or alkenes (for example, production of acrylonitrile by ammoxidation of propane or propene, production of methacrylonitrile by ammoxidation of isobutane or isobutene), and the production of alkanes or alkenes. Production of unsaturated carboxylic acids by partial oxidation reaction (for example, production of acrylic acid from propane or propene, production of methacrylic acid from isobutane or isobutene, etc.), and nitrile reaction with nitrile by partial oxidation reaction of alkane or alkene in the presence of ammonia Simultaneous production of saturated carboxylic acids (eg, simultaneous production of acrylonitrile and acrylic acid from propane), oxidative dehydrogenation of saturated carboxylic acids (eg, production of methacrylic acid from isobutyric acid), oxidative dehydrogenation of hydrocarbons (eg, ethanol From ethylene, from propane to propene, from butene to butadiene, etc.), to produce acid anhydrides by partial oxidation of various hydrocarbons (for example, to produce phthalic anhydride from naphthalene or xylene, or maleic anhydride from butane or butene) Etc.).

The oxide catalyst of the present invention or the production method of the present invention
-Phase catalytic acid of hydrocarbons using oxide catalysts obtained by the process
Conditions for the oxidation reaction include, for example, partial oxidation of alkanes.
At a relatively low temperature of 500 ° C. or less.
Also has the property of high partial oxidation activity of alkanes
At a reaction temperature of 300 to 500 ° C., preferably 350 to 500 ° C.
480 ° C., gas space velocity (SV) in the gas phase reaction is 1
00 ~ 10000hr ^-1, Preferably 300-6000
hr^-1And the pressure of the reaction is not particularly limited.
No. As a diluting gas, nitrogen, helium, argon, etc.
Can be used. The reaction is performed on a fixed bed,
Fluidized bed can be adopted, but fluidized bed has more temperature control
Is preferred because it is easy. In addition, oxidation that is inert to the reaction
Particles in the reaction system,
This can further facilitate the removal of reaction heat. flow
The catalyst particles used in the layer may be spherical fine particles.
Although desirable, in the present invention, the oxide catalyst after pulverization
Spray dry with the addition of an appropriate binder component
After that, a known method such as baking again is appropriately adopted.
With this, it is possible to produce an oxide catalyst that can be used in a fluidized bed.
is there.

The oxide catalyst of the present invention or the oxide catalyst obtained by the process of the present invention is effective for producing nitriles by ammoxidation of alkanes, particularly for producing acrylonitrile from propane. In this case, in the reaction feed gas, oxygen is preferably in a range of 0.2 to 4 moles per mole of propane, and ammonia is preferably in a range of 0.1 to 3 moles per mole of propane. Further, the oxide catalyst of the present invention or the oxide catalyst obtained by the production method of the present invention can obtain acrylic acid in high yield by a partial oxidation reaction of unsaturated carboxylic acid, particularly propane by partial oxidation of alkane. it can. As the reaction raw material gas, propane and an oxygen-containing gas are used, and it is more preferable to use water vapor, and it is possible to suppress the generation of carbon dioxide and the like and further increase the selectivity of acrylic acid. Further, the oxide catalyst of the present invention, or the oxide catalyst obtained by the production method of the present invention, the reaction conditions of the partial oxidation reaction of propane in the presence of ammonia, particularly the molar ratio of ammonia to propane, oxygen, reaction temperature and the like Acrylonitrile and acrylic acid can be simultaneously produced by controlling the temperature.

[0040]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded. The propane conversion (%), acrylonitrile (AN) selectivity (%), acrylonitrile (AN) yield (%), acrylonitrile + acrylic acid (AN + AA) yield (%) in the following Examples and Comparative Examples are as follows. Each is represented by the following equation.

[0041]

## EQU2 ## Conversion ratio of propane (%) = (moles of consumed fluorine / moles of supplied fluorine) × 100 AN selectivity (%) = (moles of produced AN / moles of consumed fluorine) × 100 AN yield Rate (%) = (moles of product AN / moles of supply flown) × 100 AN + AA yield (%) = ((moles of product AN + moles of product AA) / moles of supply flown) × 100

Comparative Example 1 A catalyst having a charged composition represented by Mo ₁ V _0.23 Nb _0.10 Sb _0.09 On was prepared by the following method. 7.1 g of ammonium paramolybdate in a 100 ml beaker of water 9
It was dissolved in 0 ml, and 0.42 g of 31% hydrogen peroxide was added to obtain a yellow solution. Then, 0.529 g of diantimony trioxide (patox-C manufactured by Taiyo Mining Co., Ltd.) was added, and the mixture was completely dissolved at 80 ° C. while stirring with a cover with a watch glass.
To this solution was added ammonium metavanadate 1.08
g was added and completely dissolved at about 70 ° C. to obtain a homogeneous solution.
After cooling this solution to about 50 ° C., 1.5 g of oxalic acid dihydrate was added and dissolved, and then 5.34 g of niobium pentoxide sol (Nb ₂ O ₅ 10% by weight) manufactured by Taki Kagaku was added. A substantially uniform slurry was obtained. Here, “substantially uniform” refers to a stable solution or a colloidal solution or a slurry in which no sediment is generated from the slurry without stirring.

A dry solid was obtained from the resulting slurry by repeating the following operation. The resulting slurry was sprayed on a commercially available hot plate heated to about 200 ° C. by a commercially available spray, dried, and immediately removed from the hot plate. The time required for the slurry sprayed on the hot plate to dry in one spray was about 10 seconds or less. About 2 g of the dried solid was filled in a quartz tubular firing tube having an inner diameter of 20 mm, and the solid was heated within 15 minutes under an air flow of 100 ml / min until the temperature of the solid reached 380 ° C., followed by cooling. Then, the temperature was raised from room temperature to 620 ° C. in about 100 minutes in a nitrogen stream at 100 ml / min.
After calcination at 200C for 2 hours, the mixture was allowed to cool to 200C or lower in a nitrogen stream to obtain a black solid (catalyst precursor).

138 mg of the obtained catalyst precursor was added to 1100
The mixture was diluted with 550 mg of silica-alumina particles calcined at ℃ and filled in a fixed-bed reactor made of Pyrex (registered trademark) glass having an inner diameter of 6 mm, and the molar ratio of propane / ammonia / nitrogen / oxygen was 1 / 0.3 / 1. A space velocity (SV) of about 850 h ^-1 under a normal pressure under a reaction gas flow of 2 / 1.5.
The ammoxidation reaction of propane was performed under the following conditions. Table 1 shows the results. Further, the catalyst precursor obtained here was dispersed in acetone using an ultrasonic cleaner, dropped on a metal sample stage, dried, and then subjected to Au-Pd vapor deposition, and an accelerating voltage of 15 kV was applied by a scanning electron microscope. Multiple fields of view were recorded at a magnification of 30,000. One of the electron micrographs thus recorded is shown in FIG. When one columnar primary particle is selected from the recorded visual field and its electron beam diffraction is measured, it can be seen that it has the feature (2) of the present invention. A total of 164 primary particles having the same shape (cylindrical or prismatic) as the primary particles are selected in order from the longest one in the recorded four visual fields, and the image analysis system MINS manufactured by Mitsubishi Chemical Corporation is used. Measure the maximum length and width of each primary particle, calculate the coefficient of variation of the measured values and the anisotropic ratio, and calculate the maximum length, width,
The arithmetic mean of the anisotropic ratio was determined. Table 2 shows the results.

Example 1 The black solid (catalyst precursor) obtained in Comparative Example 1 was ground manually for 2 minutes using an agate mortar to reduce the average particle size of the secondary particles to 20 μm or less. Electron microscope observation was performed. One of the electron micrographs recorded here is shown in FIG. From the recorded image, the primary particles had been crushed to an average particle size of less than 0.1 micron. The crushed solid is again subjected to 620 ° C. 2 in a nitrogen stream at 100 ml / min.
After calcining for an hour, an oxide catalyst was obtained.

Using the obtained oxide catalyst, an ammoxidation reaction of propane was performed in the same manner as in Comparative Example 1. Table 1 shows the results
Shown in Further, the oxide catalyst obtained here was dispersed in acetone using an ultrasonic cleaner as in Comparative Example 1, dropped on a metal sample stage, dried, and then subjected to Au-Pd vapor deposition, followed by scanning. A plurality of visual fields were recorded with an electron microscope at an acceleration voltage of 15 kV and a magnification of 30,000. An electron micrograph recorded in this way is shown in FIG. From the four visual fields recorded
For 246 primary particles, the maximum length and width of each primary particle were measured in the same manner as in Comparative Example 1, the coefficient of variation of the measured values and the anisotropic ratio were calculated, and the arithmetic average of the maximum length, width and anisotropic ratio was calculated. I asked.
Table 2 shows the results. A comparison between FIG. 1 and FIG. 3 shows that the anisotropic ratio of primary particles and the maximum length of the catalyst precursor and the oxide catalyst obtained by pulverizing and recalcining the precursor change. Also, after crushing the catalyst precursor according to FIG.
By firing again, it can be seen that crystals of the catalytically active component have grown.

[0047]

[Table 2]

[0048]

[Table 3]

As is clear from Table 2, the catalyst of Example 1 which had been pulverized and refired had an anisotropic ratio of primary particles (average value) of about 64% and a width ( Average) is 2
5% increase, while maximum length (average) is about 59%
It can be seen that it has decreased.

Example 2 A catalyst having a charged composition represented by Mo ₁ V _0.3 Nb _0.09 Sb _0.17 On was prepared by the following method. 7.1 g of ammonium paramolybdate in a 100 ml beaker of water 30
Then, 0.73 g of 31% hydrogen peroxide was added to obtain a yellow solution. Next, 0.97 g of diantimony trioxide (patox-C manufactured by Taiyo Mining Co., Ltd.) was added, and the mixture was completely dissolved at 80 ° C. while stirring with a cover with a watch glass. To this solution was added a solution of 1.41 g of ammonium metavanadate dissolved in 50 ml of warm water to obtain a homogeneous solution.
The solution was further cooled to about 50 ° C. This is solution A
And Next, niobium pentoxide sol (Nb
₂ O ₅ 10 wt%) to about 4 4.78 g in water was added 5ml
0.44 g of oxalic acid dihydrate was added to and dissolved in the solution heated to 0 ° C. This is referred to as solution B. Solution B was added to Solution A to obtain a substantially uniform slurry. Here, “substantially uniform” refers to a stable solution or a colloidal solution or a slurry in which no sediment is generated from the slurry without stirring.

A dried solid was obtained from the resulting slurry by repeating the following operation. The resulting slurry was sprayed on a commercially available hot plate heated to about 170 ° C. using a commercially available spray, dried, and immediately removed from the hot plate. The time required for the slurry sprayed on the hot plate to dry in one spray was about 10 seconds or less. A catalyst was obtained from the dried solid by the following operation. About 2 g of this dried solid is
Filled in a 0 mm quartz tubular firing tube, and the solid temperature was 38
The temperature was raised within 15 minutes under an air flow of 100 ml / min until the temperature reached 0 ° C., followed by cooling. Then, the temperature was raised from room temperature to 625 ° C. in about 1 hour in a nitrogen stream at 100 ml / min, and calcined at 625 ° C. for 2 hours, and then allowed to cool to 200 ° C. or lower in a nitrogen stream to obtain a black-violet solid. . Approximately 4 g of a black solid (catalyst precursor) obtained by performing this operation several times is pulverized by a manual operation for 2 minutes using an agate mortar so that the average particle size of the secondary particles becomes 20 micrometers or less. Crushed. When the crushed solid was observed with an electron microscope, the primary particles were crushed to an average particle size of 0.1 μm or less. The solid after pulverization was compression-molded and then crushed. What was sieved from 14 mesh to 32 mesh was collected, and about 2 g thereof was filled into a quartz tubular firing tube having an inner diameter of 20 mm again,
Similarly, the mixture was calcined at 625 ° C. for 2 hours in a nitrogen stream at 100 ml / min to obtain an oxide catalyst. Obtained oxide catalyst 550
mg in a Pyrex glass fixed-bed reactor having an inner diameter of 6 mm, and the molar ratio of propane / ammonia / air was 1 /.
The ammoxidation reaction of propane was performed under the conditions of a space velocity (SV) of about 1200 h ^-1 under a normal pressure under a reaction gas flow of 1.2 / 15. Table 3 shows the results.

Comparative Example 2 A solid (oxide catalyst) obtained in the same manner as in Example 2 except that pulverization and subsequent tableting, sieving and baking were not carried out. An ammoxidation reaction of propane was performed in the same manner as in Example 2. Table 3 shows the results.

Example 3 A catalyst having a charged composition represented by Mo ₁ V _0.3 Nb _0.09 Sb _0.17 On was prepared by the following method. To a substantially uniform slurry obtained in the same manner as in Example 2, 5.4 g of a 10 wt% aqueous sulfuric acid solution was added dropwise and mixed with stirring. Next, a dried solid was obtained from this slurry by spraying on a hot plate heated to 170 ° C. by spraying in the same manner as in Example 2. The dried solid was prepared by the method described in Example 2 for 62 hours.
The obtained black solid (catalyst precursor) is crushed, tableted, crushed and sieved at 5 ° C. under a nitrogen stream, and then baked again at 625 ° C. under a nitrogen stream to obtain an oxide catalyst. Was. An ammoxidation reaction of propane was performed in the same manner as in Example 2 using the obtained oxide catalyst. Table 3 shows the results.

Comparative Example 3 A solid (oxide catalyst) obtained in the same manner as in Example 3 except that pulverization and subsequent tableting, sieving, and calcination were not carried out. In the same manner as in Example 3, propane ammoxidation reaction was performed. Table 3 shows the results.

[0055]

[Table 4]

[0056]

According to the present invention, an inexpensive and stable oxide catalyst containing at least molybdenum, vanadium and antimony can be produced, and when this catalyst is used in a gas phase catalytic oxidation reaction, And selectivity can be improved, which is extremely useful.

[Brief description of the drawings]

FIG. 1 is a view showing one example of an electron micrograph of a catalyst precursor obtained in Comparative Example 1.

FIG. 2 is a view showing one example of an electron micrograph of a solid obtained by pulverizing the catalyst precursor of Comparative Example 1.

FIG. 3 is a view showing one example of an electron micrograph of the oxide catalyst obtained in Example 1 and obtained by grinding and recalcining the catalyst precursor of Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // C07B 61/00 300 C07B 61/00 300 F term (Reference) 4G069 AA02 AA08 AA12 BB06A BB06B BC26A BC26B BC54A BC54B BC55A BC55B BC59A BC59B CB14 CB54 EA01X EA01Y EB18X EB18Y EC22X EC22Y EC27 FA01 FB30 FB80 FC08 4H006 AA02 AC54 BA12 BA13 BA14 BA30 BC32 BE14 BE30 QN24 4H039 CA70 CL50

Claims (21)

[Claims] In a method for producing an oxide catalyst containing at least a metal element of molybdenum, vanadium and antimony, a solution or slurry containing a starting compound of each metal element is dried to obtain a solid, and then the obtained solid is calcined. A method for producing an oxide catalyst, comprising pulverizing the catalyst precursor obtained by the above-mentioned step and then calcining it again. 2. In the obtained oxide catalyst, 100 or more primary particles of a catalytically active component having a columnar or prismatic shape are selected by observation with an electron microscope, and the anisotropic ratio (average) of the selected primary particles is selected. 2. The method for producing an oxide catalyst according to claim 1, wherein the value increases by 10% or more compared to the anisotropic ratio (average value) of the primary particles of the catalyst precursor before pulverization. (Here, the anisotropic ratio is a value defined by the width of the primary particle / maximum length, and the maximum length is the distance between two points giving the maximum Feret length in the major axis direction of the characteristic ellipse, and the width. Is the maximum length and the ferret length that goes straight.) 3. The obtained oxide catalyst has a unit cell parameter a = 2.677 by electron beam diffraction.
(± 0.04) nm, b = 2.122 (± 0.04) n
m, c = 0.401 (± 0.006) nm (where a
Is an integer multiple of the above value) orthorhombic (α =
β = γ = 90 °) 100 or more primary particles (hereinafter referred to as “phase-i”) of the catalytically active component are selected, and the anisotropic ratio (average value) of the selected primary particles is determined before grinding. 3. The method for producing an oxide catalyst according to claim 1, wherein the ratio increases by 10% or more as compared with the anisotropic ratio (average value) of the primary particles of the catalyst precursor. 4. (Here, the anisotropic ratio is a value defined by the width of the primary particle / maximum length, and the maximum length is the distance between two points giving the maximum Feret length in the major axis direction of the characteristic ellipse, and the width. Is the maximum length and the ferret length that goes straight.) 4. An oxide catalyst having an average anisotropic ratio of the selected primary particles of 0.5 or more is obtained.
The method for producing an oxide catalyst according to any one of the above. 5. The process for producing an oxide catalyst according to claim 2, wherein an oxide catalyst comprising primary particles having an average maximum length of the selected primary particles of 0.3 μm or less is obtained. Method. 6. An average particle size of the selected primary particles is 0.1.
6. An oxide catalyst of submicron size is obtained.
The method for producing an oxide catalyst according to any one of the above. 7. When selecting 100 or more primary particles,
The method for producing an oxide catalyst according to any one of claims 2 to 6, wherein the method is selected in order from a longest maximum length. 8. The method for producing an oxide catalyst according to claim 1, wherein the calcination or recalcination is performed at 550 ° C. to 660 ° C. in the substantial absence of oxygen. 9. The resulting oxide catalyst has an atomic ratio of vanadium to molybdenum (V / Mo) of 0.1 to 0.8.
And the atomic ratio of antimony to molybdenum (Sb / Mo) is 0.05 to 0.5.
The method for producing an oxide catalyst according to any one of the above. 10. The method for producing an oxide catalyst according to claim 1, wherein the obtained oxide catalyst contains at least one metal element selected from niobium, tantalum, titanium and tungsten. 11. In an oxide catalyst containing at least molybdenum, vanadium and antimony, 100 or more primary particles of a catalytically active component having a columnar or prismatic shape are selected by electron microscopic observation, and the selected primary particles are selected. An oxide catalyst having an average anisotropic ratio of 0.5 or more. 12. An oxide catalyst containing at least molybdenum, vanadium and antimony, wherein a unit cell parameter by electron beam diffraction is a = 2.677 (±
0.04) nm, b = 2.122 (± 0.04) nm,
c = 0.401 (± 0.006) nm (where a has the possibility of being an integer multiple of the above value) orthorhombic (α = β =
An oxide catalyst, wherein at least 100 primary particles of the catalytically active component whose γ = 90 °) are selected, and the average value of the anisotropic ratio of the selected primary particles is 0.5 or more. 13. An oxide catalyst containing at least molybdenum, vanadium and antimony, wherein at least 100 primary particles of a catalytically active component having a columnar or prismatic shape are selected by observation with an electron microscope, and the selected primary particles are selected. An oxide catalyst, wherein the average value of the maximum length is 0.3 micron or less. 14. An oxide catalyst containing at least molybdenum, vanadium and antimony, wherein the unit cell parameter by electron diffraction is a = 2.677 (±
0.04) nm, b = 2.122 (± 0.04) nm,
c = 0.401 (± 0.006) nm (where a has the possibility of being an integer multiple of the above value) orthorhombic (α = β =
An oxide catalyst, wherein at least 100 primary particles of the catalytically active component satisfying γ = 90 °) are selected, and the average of the maximum length of the selected primary particles is 0.3 μm or less. 15. The primary particle of the selected catalytically active component has an average particle size of 0.1 μm or less.
The oxide catalyst according to any one of the above. 16. The method according to claim 11, wherein when selecting 100 or more primary particles, the primary particles are selected in descending order of the maximum length.
6. The oxide catalyst according to any one of 5. 17. A method for performing gas phase catalytic oxidation of hydrocarbons using an oxide catalyst produced by the method according to claim 1. Description: 18. A method for performing gas phase catalytic oxidation of hydrocarbons using the oxide catalyst according to claim 11. Description: 19. The method according to claim 17, wherein the unsaturated nitrile is produced by reacting an alkane with a nitrogen-containing compound and oxygen. 20. The method according to claim 19, wherein the nitrogen-containing compound is ammonia. 21. The method according to claim 19, wherein the nitrogen-containing compound is urea.
The method described in.